Purpose: To evaluate the clinical use of CAD/CAM hybrid ceramics in patients with severe tooth wear.

Methods: Forty-nine patients with severe tooth wear underwent prosthetic management with 116 hybrid ceramic restorations. The restorations were evaluated at 1 week and at 3, 6, 12, 18, 24, 30, and 36 months after placement. The amount of wear on the restorations, antagonist teeth, and opposite teeth was compared using digital superimposition analysis. A questionnaire was used to evaluate participants’ satisfaction with the restorations. Complications were recorded, and survival rates were estimated using Kaplan–Meier analysis.

Results: The clinical performance of the restorations was stable for esthetic, functional, and biological parameters up to 3 years, except for greater changes in “surface and margin staining” and “fracture and retention.” There was no significant difference in the amount of progressive wear among the restorations, antagonist teeth, and opposite side teeth until 18 months; however, the wear on the restorations increased gradually up to 36 months. Higher scores and identical satisfaction results were obtained for the chewing efficiency and cleanability during the observation period. The most common complications were restoration dislodgement (5.2%) and partial marginal chipping (4.3%), which were clinically repaired. Four restorations (3.4%) were extensively fractured and replaced. The estimated survival rate of the hybrid ceramic restorations at 3 years was 88.0%.

Conclusions: The clinical use of hybrid ceramic restorations in patients with severe tooth wear improved chewing efficiency and esthetics, provided adequate resistance for load-bearing, and delivered a stable treatment outcome after functional use.

Purpose: To evaluate the influence of cleaning methods on bonding to zirconia ceramic over a long period after airborne-particle abrasion (APA).

Methods: A total of 140 disc-shaped zirconia specimens were divided into five groups based on the cleaning methods after a 72-hour delay between APA and bonding: A-(alcohol), V-(Ivoclean), K-(Katana Cleaner), P2-(Clearfil Ceramic Primer Plus after 72 hours), and P1-(Clearfil Ceramic Primer Plus directly after APA). The specimens were APA-treated with 50-µm alumina particles (Al₂O₃) and stored at room temperature for 72 hours (n=28/group). Surface free energy (SFE) was measured for 12 specimens per group using a goniometer. For each group, 16 Plexiglas tubes filled with composite resin were bonded to zirconia specimens using a self-adhesive luting resin. Tensile bond strength (TBS) was tested for subgroups of eight specimens after 3 days of water storage and 150 days with 37500 thermal cycles. Failure modes were categorized as adhesive or cohesive using light microscopy.

Results: SFE increased significantly in groups V (68.4 mN/m) and A (61.8 mN/m) (P ≤ 0.05), but decreased in group K (33.1 mN/m) (P ≤ 0.05). TBS after 3 days of water storage ranged from 60.7 MPa in group A to 51.6 MPa in group P2 without significant difference between the tested groups (P > 0.05), and after 150 days with thermocycling, it ranged from (45.4 MPa) in group K to 33.9 MPa in group P2 with a significant difference between groups K and P2 (P ≤ 0.05).

Conclusions: Cleaning significantly affected the strength and durability of bonding in non-retentive zirconia restorations when there was a considerable time gap between APA and bonding.

Purpose: This study aimed to investigate the characteristics of jaw movement trajectories in the horizontal plane and the maximal activities of the masseter muscle during grinding events associated with rhythmic masticatory muscle activity (RMMA), as a potential biomarker for the diagnosis of sleep bruxism.

Methods: The biological signals and jaw movement data of eight participants were recorded using a custom-developed intraoral sensor, a six-degree-of-freedom magnetic jaw-tracking device, and polysomnography. These recordings were synchronized using Global Positioning System time data. Jaw movement data during grinding events were compared with simulated grinding (lateral excursion) data obtained before sleep, focusing on deviations from the anteroposterior direction in the horizontal plane. Additionally, the timing of the maximal masseter muscle activity was examined.

Results: No sleep disturbances were reported by the participants. During tooth grinding, the jaw movement trajectories of the lateral excursions in the horizontal plane frequently deviated from the simulated grinding trajectories, indicating variability among participants. Notably, the deviations were more pronounced during lateral excursions to the lateral side, with movements diverging both anteriorly and posteriorly from the simulated grinding trajectories. Regarding the masseter muscle activity, greater activity was observed on the balancing side. Peak masseter muscle activity increased when the jaw movement trajectories deviated posteriorly from the simulated grinding trajectory, on both the working and balancing sides.

Conclusions: Excursions deviating posteriorly during RMMAs from the simulated grinding were associated with significantly greater masseter muscle activity than either excursions deviating anteriorly or those along the simulated grinding trajectory.

Patients: A 22-year-old female patient presented with a lower right first molar exhibiting an extensive carious lesion beneath an old direct resin composite restoration. Radiographic evaluation revealed pulpal involvement with a periapical infection, accompanied by grade II mobility and a circumferential probing depth of <3 mm. The compromised molar rehabilitation was carried out using a multichromatic 3D-printed onlay. A fully digital workflow was employed, enabling the completion of the procedure in a single clinical session. Following endodontic and restorative treatments, intraoral scans were acquired using a Trios5 scanner. The restoration was digitally designed and 3D printed from STL files using the DWS Systems Dfab printer. The hybrid composite onlay was adhesively luted using a universal self-adhesive resin cement (Panavia SA, Kuraray). Clinical evaluations at 6 months and 1 year demonstrated favorable outcomes, with high patient satisfaction.

Discussion: 3D printing represents a digital evolution in the fabrication of dental restorations, introducing an additive manufacturing approach distinct from the subtractive processes used in traditional CAD/CAM systems. In cases of severely compromised teeth, 3D-printed, adhesively bonded partial restorations represent a viable treatment option. The hybrid composite used in this study demonstrated favorable clinical and esthetic performance, enabling minimally invasive preparations while preserving sound tooth structure.

Conclusions: Chairside 3D printing technology presents an alternative approach for the fabrication of indirect composite restorations in posterior teeth. Although 3D printing is not yet widely adopted in restorative dentistry, its versatility may offer significant advantages for both clinicians and patients in the production of indirect partial restorations.

Purpose: To clarify the intra- and inter-examiner reliability of an occlusal force-measuring device equipped with a capacitive-type pressure-mapping sensor sheet in older adults.

Methods: Thirty-eight individuals (23 women) aged ≥65 (mean ± SD: 79.3±6.1) years were included. The numbers of present and functional teeth were visually examined. Occlusal force was measured using the Oramo-bf device (Sumitomo Riko Co., Aichi, Japan). To evaluate intra-examiner reliability, one dentist measured each participant’s occlusal force thrice and calculated the intraclass correlation coefficient (ICC; case 1) and the coefficient of variation (CV). To examine inter-examiner reliability, three dentists measured the occlusal force once per participant and calculated the ICC case 2.

Results: The median (first quartile–third quartile [Q1–Q3]) numbers of present and functional teeth were 22.5 (18–27) and 28 (26–28), respectively. The median (Q1-Q3) occlusal force measured by a single examiner across the measurements was 604.8 (261.7–731.5) N. The ICC for a single measurement by one examiner based on all three measurements per participant was 0.982 (95% confidence interval [CI]: 0.969–0.990). The ICC (1,3) for the mean of three repeated measurements by one examiner was 0.994 (95% CI: 0.990–0.997). The mean ± SD CV was 0.052 ± 0.046. The ICC (2,1) for inter-examiner reliability was 0.950 (95% CI: 0.917–0.972).

Conclusions: This study revealed high intra- and inter-examiner reliability of measurements obtained using an occlusal force-measuring device equipped with a capacitive-type pressure-mapping sensor sheet. This device may provide reliable results with a single measurement, regardless of the examiner.

Purpose: This was a prospective study conducted alongside a randomized controlled trial (RCT) that evaluated the incidence of fractures and associated risk factors in single-implant overdentures (1-IOD) compared with two-implant overdentures (2-IOD).

Methods: The participants received either a mandibular 1-IOD or 2-IOD (attachments: Straumann® retentive anchor and elliptical titanium matrix with gold insert; implants: 4.1 mm diameter, Straumann® Standard Plus SLActive® Regular Neck), within the context of a randomized clinical trial. The primary outcome of interest was the incidence of IOD fractures at 5-year follow-up. Prosthetic factors, such as area and cervico-incisal height in the attachment region, and volume at the inter-canine region, were measured. Patient-related factors including age, sex, handgrip strength, manual dexterity, bite force, and chewing performance were assessed. Data analysis included descriptive statistics, bivariate tests, Kaplan-Meier plots, and linear discriminant analysis with log₁₀ transformation for variable normalization.

Results: A total of 47 patients were recruited, and 34 (n = 34, 1-IOD = 16, 2-IOD = 18; mean-age: 63.9 ± 8.6 years; 79.4% women) completed the 5-year follow-up. There were no differences in the incidence of fractures between the 1-IOD and 2-IOD groups (P < 0.05). Fractures were more frequent in younger patients, and reduced cervico-incisal IOD height was significantly associated with fractures (P = 0.040). Linear discriminant analysis predicted fractures with 84.4% accuracy and identified cervico-incisal height and age as key predictors.

Conclusions: There were no significant differences in the incidence of overdenture fractures between groups. Reduced cervico-incisal denture height in the attachment region of ball-retained IODs was associated with mandibular IOD fractures. Further studies with larger cohorts are recommended to identify additional risk factors for mandibular IODs.

Patients: A 56-year-old man with a left-sided cleft lip and palate was referred to our department due to mastication and speech difficulties. His existing prostheses have become unstable owing to changes in the remaining dentition over 10 years. For the fabrication of the new interim maxillofacial prostheses, a digital impression technique was selected as the conventional technique posed medical risks due to hypermobile teeth and maxillary defects. New interim maxillofacial prostheses were fabricated using a combination of the digital impression technique and a bite-seating impression, performed with trial prostheses and impression material. The patient has been using the new interim prostheses comfortably since delivery. The oral functional evaluation yielded favorable results.

Discussion: Patients with cleft lip and palate should use their existing maxillofacial prostheses during the fabrication of new ones, even if they are of suboptimal quality. Although addressing these issues using conventional techniques is challenging, digital technology provides a viable solution. However, impression material is essential for capturing mucosal defects and complex anatomy in cleft lip and palate cases; therefore, digital data should be supplemented by either well-adjusted existing prostheses or bite-seating impressions using impression material before new prostheses fabrication. Although his occlusal force was lower than the criterion for the oral hypofunction test, his masticatory performance remained favorable. Speech analysis revealed persistent air leakage; however, all scores improved with the prostheses.

Conclusions: Digital technology has enabled the safe fabrication of interim maxillofacial prostheses, resulting in improved masticatory and speech performance.

Purpose: To assess the predictability of using the roots of the maxillary anterior teeth in advantageous positions to guide immediate implantation and enhance the positioning precision of placed implants.

Methods: Existing root canals were used in the test group for manual preparation of the implant bed, whereas traditional freehand techniques were employed in the control group. The three-dimensional position of the placed implants was measured using radiological images taken on the day of surgery and again six months post-surgery and evaluated using self-developed rating criteria for the radiographic positions of the implants. The spatial relationship between the axial orientation of the implant and prosthetic crown was assessed using a self-developed scoring scale. Statistical analysis of the three-dimensional positional imaging scores of the implants was conducted immediately after surgery and at six months post-implantation. Intergroup statistical analysis was conducted on the scores reflecting the spatial relationship between the axial orientation of the implants and their prostheses.

Results: The test group demonstrated significantly higher scores for the labial-palate and horizontal positions, both immediately following surgery and at six months post-implantation, than the control group. Furthermore, the test group significantly outperformed the control group in terms of scores reflecting spatial relationships.

Conclusions: Utilizing the roots of the anterior teeth in advantageous positions as guides for preparing implant beds can lead to more ideal implant placement than traditional manual techniques.

Purpose: To evaluate how the depth of the intaglio surface on the denture and the scanning method influence the trueness using two types of intraoral scanners (IOS) for complete dentures.

Methods: Four complete denture types (Extra-deep, Deep, Moderate, Shallow) with varying intaglio surface depths (Extra-deep > Deep > Moderate > Shallow) for the maxilla and mandible were designed using two computer-aided design software, resulting in 8 denture models. Reference data were obtained using a laboratory scanner (D2000). Each denture was scanned eight times using two IOSs: a confocal microscopy-based scanner (Trios 5) and a dual-triangulation-based scanner (i700), resulting in 64 scans per IOS (128 scans in total). Scan data were superimposed using three-dimensional editing software, and the root mean square (RMS) was calculated to assess trueness. Statistical analyses included the Shapiro-Wilk test for normality and two-way analysis of variance with Bonferroni correction (α=0.05).

Results: For Trios 5, the RMS value for the Extra-deep was significantly higher than that for the Moderate and Shallow in both the maxilla and mandible. Furthermore, the Deep showed significantly higher RMS values than the Shallow in the maxilla. For i700, the RMS values did not significantly differ among the denture types. Across all denture types, the RMS values for i700 were significantly higher than those for Trios 5.

Conclusions: The depth of the intaglio surface on the denture influenced trueness when using the Trios 5. The Trios 5 showed higher trueness than the i700 did across all denture types.

Purpose: Evaluation of the impact of ultraviolet (UV) photofunctionalization on titanium–cement interfaces, specifically its ability to transform titanium into a high-energy surface and enhance crown retention.

Methods: Commercial titanium abutments (standard: 4.0 mm; long: 5.5 mm) were treated with vacuum UV (VUV) light at 172 nm for 1 min. Milled polymethyl methacrylate crowns were cemented using resin-modified glass ionomer cement. Tensile testing quantified the maximum tensile load and interfacial energy. Surface changes were analyzed using contact angle measurements and X-ray photoelectron spectroscopy (XPS). Post-failure interfaces were examined via scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX).

Results: UV-treated standard-length abutments exhibited a 4.1-fold increase in maximum tensile load and 27-fold increase in bonding energy compared with untreated control counterparts. UV-treated long abutments showed a 4.6-fold increase in maximum tensile load and 54-fold increase in bonding energy. UV treatment rendered the titanium surface superhydrophilic and low in carbon, whereas untreated specimens remained carbon-rich and hydrophobic. UV-treated long abutments exhibited 3.1-fold higher energy than UV-treated standard abutments. Notably, long abutments without UV treatment did not outperform standard untreated abutments. SEM and EDX confirmed extensive residual cement on UV-treated abutments, indicating cohesive failure and strong interfacial bonding.

Conclusions: A 1-min UV photofunctionalization transforms titanium into a superhydrophilic, high-energy surface that significantly enhances cement bonding. This physicochemical surface strategy outperforms geometric modifications alone. As a rapid, non-invasive approach, UV photofunctionalization may establish a new standard for durable implant-supported restorations, reducing prosthetic failure and influencing both material selection and clinical and laboratory workflows.

Purpose: This systematic review evaluates the effectiveness of artificial intelligence (AI) models in dental implant treatment planning, focusing on: 1) identification, detection, and segmentation of anatomical structures; 2) technical assistance during treatment planning; and 3) additional relevant applications.

Study selection: A literature search of PubMed/MEDLINE, Scopus, and Web of Science was conducted for studies published in English until July 31, 2024. The included studies explored AI applications in implant treatment planning, excluding expert opinions, guidelines, and protocols. Three reviewers independently assessed study quality using the Joanna Briggs Institute (JBI) Critical Appraisal Checklist for Quasi-Experimental Studies, resolving disagreements by consensus.

Results: Of the 28 included studies, four were high, four were medium, and 20 were low quality according to the JBI scale. Eighteen studies on anatomical segmentation have demonstrated AI models with accuracy rates ranging from 66.4% to 99.1%. Eight studies examined AI’s role in technical assistance for surgical planning, demonstrating its potential in predicting jawbone mineral density, optimizing drilling protocols, and classifying plans for maxillary sinus augmentation. One study indicated a learning curve for AI in implant planning, recommending at least 50 images for over 70% predictive accuracy. Another study reported 83% accuracy in localizing stent markers for implant sites, suggesting additional imaging planes to address a 17% miss rate and 2.8% false positives.

Conclusions: AI models exhibit potential for automating dental implant planning with high accuracy in anatomical segmentation and insightful technical assistance. However, further well-designed studies with standardized evaluation parameters are required for pragmatic integration into clinical settings.

Purpose: To evaluate and compare the effect of bulb wall thickness and build angle on the trueness and weight of an open-hollow obturator fabricated using digital light processing (DLP) technology.

Methods: A 3D model of an edentulous maxillary jaw with an Aramany Class I defect was designed using computer-aided design (CAD) software, and 45 obturators with bulb wall thicknesses of 1, 2, and 3 mm were fabricated using a DLP printer at build angles of 0, 45, and 315 degrees, respectively. The weight of each obturator was measured. All obturators were scanned using cone-beam computed tomography, and the data were converted to the standard tessellation language format. The CAD and scanning data were superimposed for inspection. Statistical analysis was performed using two-way analysis of variance (ANOVA) and Tukey’s test.

Results: The two-way ANOVA showed a significant effect of the build angle on the denture base (P < 0.001); however, the bulb wall thickness had no significant effect (P = 0.73). Both the bulb wall thickness and build angle significantly affected the inner and outer bulb surfaces (P < 0.001), and a significant interaction between these factors was observed (P < 0.05). Significant differences were observed between bulbs (P < 0.001). Additionally, weight was significantly affected by both factors and their interactions (P < 0.001).

Conclusions: The bulb wall thickness and build angle significantly influenced the trueness and weight of the open-hollow DLP obturator, with the least error observed at a zero-degree build angle.

Purpose: This in vitro study evaluated the adaptation and fracture resistance of screw- and cement-retained implant-supported restorations using lithium disilicate crowns cemented onto titanium bases and universal abutments of different heights.

Methods: Thirty crowns were designed, milled, and divided into three groups: TBA (titanium base abutment - 4.7-mm-height and 4.65-mm-diameter), UA-4 (universal abutment - 4.0-mm-height and 4.5-mm-diameter), and UA-6 (universal abutment - 6.0-mm-height and 4.5-mm-diameter) (n=10). The abutments were placed in a mandibular first premolar model, torqued to 20 Ncm, and scanned using a digital intraoral scanner. The crowns were designed and fabricated using computer-aided design/computer-aided manufacturing technology. Adaptation was assessed using a stereomicroscope before and after ceramic sintering and after cementation with RelyX Ultimate resin cement. Fracture resistance was evaluated using a universal testing machine, and the failure modes were analyzed. The collected data were subjected to statistical analysis using one-way ANOVA and the Tukey least significant difference test (α=0.05).

Results: The abutment type influenced restoration adaptation and fracture resistance. No differences in adaptation were found before or after luting (P > 0.05). However, after sintering, the TBA group exhibited smaller marginal gaps than the UA-4 (P = 0.0339) and UA-6 (P = 0.0006) groups. TBA showed a higher fracture resistance than UA-4 (P = 0.0093); no differences were observed between TBA and UA-6 or between UA-4 and UA-6 (P > 0.05). The UA-4 and UA-6 groups showed higher ceramic fracture rates, whereas the TBA group showed increased abutment deformation and ceramic fractures.

Conclusions: The type and height of abutments influenced the fracture of screw-and-cement-retained implant-supported restorations.

Purpose: This study aimed to evaluate the performance of 3D-printed denture base resins (DBRs) compared with conventionally printed DBRs, examine their biofilm formation and physical properties, and determine the viability of 3D-printed DBRs as a superior alternative in removable prosthodontics.

Methods: The DBR samples were fabricated using traditional packing (TRA), milling (MIL), and 3D printing (3DP) methods. All samples were serially polished with an abrasive paper. Biofilm formation was assessed using SYTO 9 and propidium iodide staining as well as confocal laser scanning microscopy. Color and dimensional stability were evaluated following immersion in artificial saliva, and volumetric changes were assessed after the samples were subjected to thermocycling (TC) and highly accelerated stress (HA) aging. Statistical analyses were conducted using one-way analysis of variance with post-hoc Tukey’s honestly significant difference test (α = 0.05).

Results: MIL exhibited the highest Aggregatibacter actinomycetemcomitans biofilm coverage (94.59%), whereas 3DP exhibited the lowest coverage (58.86%). All DBRs exhibited slight perceptible color changes after immersion in artificial saliva, with 3DP demonstrating the least dimensional changes (2.86%). Following TC and HA aging, all DBRs experienced a volume increase, with TC inducing greater volumetric changes (2.8%–3.9%) than HA (0.8%–2.4%); however, the difference was not statistically significant (P < 0.05).

Conclusions: The 3D-printed DBRs demonstrated superior resistance to biofilm formation, along with good color and dimensional stability. These properties indicate strong potential for enhanced hygiene maintenance, esthetics, and long-term clinical performance in denture applications.

Purpose: This systematic review evaluated the clinical performance, physical-mechanical properties, and accuracy of removable partial denture (RPD) frameworks fabricated using three-dimensional (3D) printing technologies—specifically, selective laser sintering (SLS), selective laser melting (SLM), and direct metal laser sintering (DMLS)—compared to those produced by conventional casting or methods using a partial digital workflow.

Study selection: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines, a literature search was conducted in the PubMed, Scopus, Web of Science, and Cochrane databases in October 2024. Studies were included if they compared the fit, accuracy, mechanical and physical properties, and clinical outcomes of metal RPD frameworks made using 3D printing technologies with those produced using conventional casting or partial digital methods. The risk of bias was assessed using appropriate tools (modified CONSORT, ROB2, and ROBINS-I) based on the study design and a qualitative analysis was conducted. This study received no funding and was registered with PROSPERO (#CRD42024597225).

Results: Thirty studies were included: 12 compared 3D printing technologies with conventional casting, eight with partial digital methods, and 10 with both. Clinically, 3D-printed frameworks could improve retention and patient satisfaction. The laboratory results showed higher density, better mechanical properties (yield strength, surface roughness, and microhardness), and varied accuracy by component and method, with SLM and DMLS often outperforming conventional casting. The evidence was limited by methodological variability, a moderate risk of bias in many studies, and inconsistencies across the study designs and parameters.

Conclusions: 3D-printed RPD metal frameworks demonstrated clinical accuracy and mechanical-physical performance comparable or superior to those of conventional and partially digital methods for RPD frameworks, with ongoing advances expected to further enhance their precision and clinical applicability.

Purpose: To investigate the effect of ceramic material (lithium disilicate, LDS vs. composition-gradient multilayered zirconia [4Y-PSZ and 5-PSZ], Z) and ceramic layer thickness (0.5 mm, 1.0 mm, and 1.5 mm) on fatigue performance and failure load of occlusal veneers on molars.

Methods: Seventy-two CAD-CAM-fabricated occlusal veneer restorations (IPS e.max CAD; IPS e.max ZirCAD Prime Esthetic, Ivoclar Vivadent) were divided into six groups (n=12, LDS-1.5, LDS-1.0, LDS-0.5; Z-1.5, Z-1.0, Z-0.5). Restorations were adhesively cemented (Variolink Esthetic DC, Ivoclar Vivadent) to dentin-analogue composite dies (Z100, 3M ESPE) and exposed to thermomechanical fatigue (1.2 million cycles, 49 N, 1.6 Hz, 5-55° C). Single-load-to-failure was tested with a universal testing machine. Data were analyzed using ANOVA with Tukey post-hoc tests and t-tests (P < 0.05).

Results: The overall success rate across all materials and layer thicknesses was 91.7%. Half of the specimens of group Z-0.5 revealed cracks after chewing simulation. Occlusal veneers fabricated from LDS withstood significantly higher failure loads than gradient multilayered zirconia veneers in all tested thicknesses. The mean failure load values led to the following ranking: 3194 N (LDS-0.5)>2683 N (LDS-1.0)>2338 N (LDS-1.5)>1744 N (Z-1.5)>1310 N (Z-0.5)>1198 N (Z-1.0).

Conclusions: Ultrathin LDS occlusal veneers outperformed thin and standard thick counterparts, as well as gradient multilayered zirconia veneers at all thickness levels. Ultrathin gradient multilayered zirconia occlusal veneers were prone to cracks during thermomechanical fatigue. Individual mechanical properties need to be considered when aligning the restoration within the multilayered zirconia blank.

Purpose: Supports are essential for ensuring dimensional accuracy in 3D printing; however, an excessive number of supports compromises printing efficiency. This study aimed to investigate how a varying number of support arrangements affects the precision and trueness of 3D-printed dentures.

Methods: Three denture base printing files were designed, each with different numbers of supports: 40 (group 40), 55 (group 55), and 70 (group 70). Thirty samples were printed and measured across the groups. Accuracy was evaluated by assessing trueness and precision using the root mean square error (RMSE). The error areas in each group were analyzed through micro-computed tomography (micro-CT) 3D imaging.

Results: Group 70 showed a significantly lower RMSE for trueness than Group 40 (P < 0.05), but showed no significant difference from Group 55 (P ≥ 0.05). For precision, Group 70 outperformed both Groups 40 and 55 (P < 0.05), which did not differ significantly (P ≥ 0.05). Micro-CT revealed no mismatches in the palatal region. Discrepancies—areas where the supports in Groups 40 and 55 did not accurately align with those in Group 70—were predominantly observed at initiation points of overhangs in thinner sections.

Conclusions: Based on these results, this study recommends placing support structures strategically around overhangs and thin-walled areas to enhance the accuracy of 3D-printed denture fabrication. These findings indicate that optimizing support placement, rather than merely increasing the number of supports, is crucial in improving the quality and reliability of 3D-printed dental prostheses.

Purpose: To evaluate the effects of various cleaning methods on the bond strength between lithium disilicate (LS₂) ceramics and resin cement under short- and long-term aging conditions using network meta-analysis (NMA) and pairwise meta-analysis (PMA).

Study selection: An electronic search of seven databases (PubMed, Scopus, Embase, Web of Science, Google Scholar, Defense Technical Information Center, and LILACS) with a manual search of the reference lists was conducted for articles published up to March 10, 2025. Eligible studies included those that assessed the bond strength of LS₂, either uncontaminated or contaminated with human saliva, fit-checking materials, try-in paste, or their combinations, using different cleaning methods. Risk of bias was evaluated using the RoBDEMAT tool. A frequentist multivariable random-effects model was used to calculate the effect sizes.

Results: Fifteen studies met the inclusion criteria. Under short-term aging conditions, NMA showed higher bond strengths in the uncontaminated LS₂ group and the contaminated groups cleaned with hydrofluoric acid etching, commercial ceramic cleaning agents, or phosphoric acid etching than those uncleaned or cleaned with water or alcohol. In long-term aging, PMA and NMA exhibited higher bond strengths in the uncontaminated LS₂ group and contaminated group cleaned with phosphoric acid etching than those contaminated groups cleaned with water or alcohol.

Conclusions: Phosphoric acid etching effectively eliminates contaminants, whereas the application of water or alcohol is ineffective. Although ceramic cleaning agents effectively decontaminate surfaces under short-term aging conditions, their performance deteriorates over time, potentially compromising long-term bond durability.

Purpose: Sleep-disordered breathing (SDB) has received limited attention in stroke rehabilitation, and screening for SDB is inadequate. This study aimed to examine the association between nocturnal hypoxia and functional independence improvement in stroke patients during recovery, with a focus on the potential relevance of SDB in rehabilitation outcomes.

Methods: This prospective cohort study included 89 patients admitted for stroke rehabilitation in Chiba, Japan, between August 2021 and March 2024. SDB was assessed using WatchPAT, focusing on nocturnal oxygen saturation parameters, including the minimum SpO₂ (MinSpO₂) and the oxygen desaturation index at 3% (ODI3%). The functional independence measure (FIM) improvement per day of hospitalization (FIM change rate) was the primary outcome. The covariates included age, sex, body mass index, stroke severity, comorbidities, and levels of consciousness.

Results: Multivariate regression analyses showed that MinSpO₂ was significantly associated with the total FIM change rate (B [95% CI] = 0.008 [0.003–0.012], P = 0.001) and had a standardized coefficient of 0.337, whereas ODI3% showed no significant association. MinSpO₂ was associated with both motor and cognitive FIM change rates.

Conclusions: Nocturnal hypoxia is associated with functional recovery in patients with stroke, highlighting the importance of sleep monitoring in rehabilitation. As a detectable and modifiable factor, it may present opportunities for dental professionals to contribute to patient care through airway assessment and collaborative intervention.

Purpose: The aim of this systematic review was to analyze the reported flexural strength values of commercially available translucent zirconia materials. Additionally, data were evaluated to assess the impact of different specimen preparations and test methods.

Study selection: This systematic review was conducted according to the PRISMA guidelines. Electronic searches were performed to identify in vitro studies published between January 1, 2013, and March 15, 2025, that reported flexural strength values of translucent zirconia and included the names of the tested materials and manufacturers. Flexural strength values were analyzed to assess the effects of yttria content, specimen processing, surface treatments, and test methods using Kruskal–Wallis analysis of variance (α = 0.05) and forest plots.

Results: A total of 78 laboratory studies met the inclusion criteria. The overall flexural strength values were significantly higher for 4Y-PSZ (803± 233 MPa) than for 5Y-PSZ materials (570 ± 116 MPa) (P = 0.005). Specimen processing, surface treatments, and test methods significantly affected the flexural strength values for 5Y-PSZ (P < 0.001) but not for 4Y-PSZ (P > 0.05).

Conclusions: This systematic review highlights the challenges in comparing the flexural strength values of translucent zirconia owing to differences in processing parameters. Further standardization of test methods and adherence to ISO 6872 would improve comparability. Our findings support the clinical use of 4Y-PSZ for three-unit fixed dental prostheses (FDPs) and 5Y-PSZ for three-unit FDPs in the anterior region based on ISO 6872.

Purpose: This study compared the scanned data obtained from four conventional silicone impressions using a laboratory scanner to investigate the effects of impression materials on accuracy and precision.

Methods: The master model was a gauge with four small height increments constructed from an assembly of ceramic gauge blocks. Impressions of the master model were made using four silicone impression materials (Imprinsis Regular: blue; Fusion II: pink; Fit Checker: white, Imprint3: yellow). The impressions were scanned under blue light using a laboratory scanner. The points of inquiry were 1) advisability of three-dimensional (3D) reconstruction, 2) reproducibility at the surface level, and 3) microstep detectability. Data were analyzed using a one-way analysis of variance and Tukey’s multiple comparison test.

Results: 3D reconstruction was achieved for all impressions except Imprint3. The scanning performance of the impression material affected the spectral reflection factor. There was no significant difference in surface reproducibility among the three impression materials, and the detectability of small step height in Imprinsis Regular was significantly better than that in other impression materials (P < 0.05).

Conclusions: The color of the impression material affected digitization when a blue-light scanner was used. The digitization accuracy of Imprinsis Regular was higher than that of the other impression materials. However, the digitization accuracy of the three impression materials that could be 3D-reconstructed was within clinical tolerance. These findings can broaden the clinical applications of digital dentistry and mitigate the errors associated with dental materials.

Purpose: This systematic review and meta-analysis investigated the effects of mandibular advancement device (MAD) therapy on temporomandibular disorders (TMDs) in patients with obstructive sleep apnea (OSA).

Study selection: We included 14 clinical studies assessing the signs and symptoms of TMDs in patients with OSA treated with MAD therapy. The analysis was divided into short-term (<6 months) and long-term (≥1 year) follow-up phases. Odds ratios (OR) and 95% confidence intervals (CI) were calculated for each study during follow-up. The certainty of the evidence was assessed using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology, and meta-analysis was conducted using Review Manager version 5.4.

Results: Across the 14 studies included, the average follow-up period was 18.4 months, and the overall certainty of the evidence was rated as very low. Four studies used the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD), six used the Helkimo Anamnestic Index, and four employed questionnaires. In short-term follow-up, a significant increase in pain-related TMDs was observed, including pain in the temporomandibular joint (TMJ) or masticatory muscles (pain-related TMDs: OR:4.49; 95%CI: 1.46 to 13.81, TMJ or masticatory muscles pain: OR:2.90; 95%CI: 1.26 to 6.71). Conversely, during long-term follow-up, the odds of pain in the TMJ or masticatory muscles were significantly reduced (OR:0.21; 95%CI, 0.05 0.89)

Conclusions: MAD therapy for OSA did not cause long-term adverse effects on the TMJ or masticatory muscles. However, its short-term use may result in pain-related TMDs, highlighting the need to monitor and manage these symptoms during this period.

Purpose: To evaluate the color stability of light-cured resin luting agents after artificial aging using an amine-free initiator system.

Methods: Five groups, each with eight samples, were produced. Specimens were divided as follows: two light-cured resin luting agents (PANAVIA Veneer LC; PVL [experimental group] and Variolink Esthetic LC; VEL [control group]), one dual-cured resin luting agent (PANAVIA V5; PV5 [control group]), and one composite resin (ESTELITE Σ QUICK; ESQ [control group]). The samples were divided into five groups subjected to different accelerated aging conditions: Condition 1 (air storage), Condition 2 (water storage), Condition 3 (temperature–moisture combination: as a control for Condition 2), Condition 4 (ultraviolet (UV) aging: to predict the performance in a laminate veneer restoration margin area), and Condition 5 (without UV aging to serve as a baseline control by eliminating environmental factors). Spectrophotometric measurements were performed. Changes in the color (∆E₀₀) and a transparency parameter (ΔTP₀₀) were determined. Data were analyzed using one- and two-way ANOVAs at a significance level of 5%.

Results: PANAVIA V5 in water storage exhibited the highest ΔE₀₀ across all materials, except Variolink Esthetic LC (P < 0.001). PANAVIA Veneer LC under Condition 1 did not show a statistically significant difference in ΔE₀₀ compared to the other materials (P = 1.000). PANAVIA Veneer LC and ESQ showed significantly smaller ΔTP₀₀ values than the other materials (P < 0.001).

Conclusions: Based on the results of this study, PANAVIA Veneer LC shows better color stability, even under artificial aging conditions, which is clinically desirable.

Purpose: To establish the relationship between rhythmic masticatory muscle activity (RMMA) of the masseter muscle during sleep bruxism (SB) and occlusal wear and distortion in the stabilization occlusal appliance (OcA) used for its treatment.

Methods: Seventeen adults with SB wore OcAs composed of polymethyl methacrylate for 28 days. Weekly recordings included electromyography (EMG) of the masseter muscle using a wearable EMG device, evaluation of SB variables, and 3D scanning of the OcA using a 3D dental model scanner. The awake bite force at the time of recruitment was measured using a film-based bite force measurement system. The 3D data collected weekly before and after wearing the OcA were superimposed, and the weekly deformations in the coronal-apical directions were calculated. The masseter muscle activity per hour (RMMA index) and OcA deformation were compared weekly. Finally, we investigated the relationship between the frequency and intensity of the masseter muscle activity patterns and OcA deformation.

Results: No significant differences were observed in weekly RMMA index; however, all OcA deformations were significant. Apical deformation, including occlusal wear, was positively correlated with awake bite force. Coronal deformation reflecting distortion was positively correlated with the number of sustained tonic masseter muscle activities and maximum masseter muscle activities.

Conclusions: OcA deformation measured using this system reflects the frequency and intensity of the RMMA and masseter muscle activity in patients with SB, suggesting its potential as a novel clinical diagnostic tool for SB.

Purpose: Measuring enamel depth distribution (EDD) is of great importance for preoperative design of tooth preparations, restorative aesthetic preview and monitoring enamel wear. But, currently there are no non-invasive methods available to efficiently obtain EDD. This study aimed to develop a machine learning (ML) framework to achieve noninvasive and radiation-free EDD predictions with intraoral scanning (IOS) images.

Methods: Cone-beam computed tomography (CBCT) and IOS images of right maxillary central incisors, canines, and first premolars from 200 volunteers were included and preprocessed with surface parameterization. During the training stage, the EDD ground truths were obtained from CBCT. Five-dimensional features (incisal-gingival position, mesial-distal position, local surface curvature, incisal-gingival stretch, mesial-distal stretch) were extracted on labial enamel surfaces and served as inputs to the ML models. An eXtreme gradient boosting (XGB) model was trained to establish the mapping of features to the enamel depth values. R² and mean absolute error (MAE) were utilized to evaluate the training accuracy of XGB model. In prediction stage, the predicted EDDs were compared with the ground truths, and the EDD discrepancies were analyzed using a paired t-test and Frobenius norm.

Results: The XGB model achieved superior performance in training with average R² and MAE values of 0.926 and 0.080, respectively. Independent validation confirmed its robust EDD prediction ability, showing no significant deviation from ground truths in paired t-test and low prediction errors (Frobenius norm: 12.566–18.312), despite minor noise in IOS-based predictions.

Conclusions: This study performed preliminary validation of an IOS-based ML model for high-quality EDD prediction.

Purpose: To investigate the association of removable partial denture (RPD)/complete denture (CD) and fixed partial denture (FPD) use with health-related quality of life (HRQoL), evaluated using the EuroQol 5-dimension, 5-level instrument (EQ-5D-5L) among older adults with tooth loss.

Methods: Cross-sectional data from the 2022 Japan Gerontological Evaluation Study. Participants were classified as RPD/CD users, FPD users, or nonusers. Generalized linear regression models stratified by the number of teeth were used to explore the association of RPD/CD and FPD use with the HRQoL evaluated using the EQ-5D-5L. The interactions among the number of teeth, RPD/CD, and FPD use were examined.

Results: After adjusting for all covariates, RPD/CD and FPD users with 5–19 teeth had higher predicted HRQoL utility scores than nonusers (RPD/CD [n=14,297]: 0.837 vs. 0.850; FPD [n=7,476]: 0.858 vs. 0.861 [nonusers vs. users]). The interaction between number of teeth and RPD/CD and FPD use revealed that differences in HRQoL between users and nonusers were greater among those with 1–14 teeth for RPD/CD use and among those with 10–14 teeth for FPD use (RPD/CD: β = −0.008, P < 0.01; FPD: β = −0.008, P = 0.183).

Conclusions: RPD/CD and FPD users with 5–19 teeth had a higher HRQoL than nonusers, with differences appearing to depend on the number of teeth. The World Health Organization has promoted the incorporation of oral health into universal health coverage (UHC). Given the minimal HRQoL difference between CD users and nonusers among edentulous individuals, unconventional dentures may merit inclusion in UHC.

Purpose: Comminution of food into small particles through mastication is important for safe swallowing. However, few studies have evaluated the functional improvement provided by newly fabricated removable dentures in terms of changes in the comminution of food at the swallowing threshold (CF-ST). This prospective cohort study aimed to clarify the changes in CF-ST associated with the fabrication of newly removable dentures.

Methods: Eighty patients (age: 57.3 ± 11.9 years) requiring new removable dentures were enrolled. Masticatory performance (MP) and CF-ST were assessed before and after new denture insertion. MP and CF-ST were defined as the increase in surface area of 5.5 g of test gummy jelly after 30 chewing cycles and after chewing until the premeasured swallowing threshold, respectively. Other oral functions, including tongue pressure, oral diadochokinesis, and stimulated salivary flow rate, were measured concurrently. All evaluation items were compared before and after new denture insertion. Multiple regression analysis was performed to identify factors affecting changes in CF-ST.

Results: CF-ST, MP, and other oral functions significantly improved after new denture insertion. Multiple regression analysis identified changes in MP (β = 0.467), number of chewing cycles at the swallowing threshold (β = 0.322), and belonging to Eichner index C group (β = 0.245) as significant factors influencing changes in CF-ST.

Conclusions: Newly fabricated removable dentures have the potential to improve CF-ST. This improvement may result from enhanced masticatory function and changes in masticatory behavior, such as increased chewing.

Purpose: Jaw movements in sleep bruxism (SB) presumably play a functional role in salivary stimulation and oral tissue protection. This study aimed to investigate the relationships between SB, oral wetness, and salivary flow.

Methods: Participants underwent polysomnography in a sleep laboratory, during which rhythmic masticatory muscle activity (RMMA) and swallowing were recorded. The degree of oral moisture was measured before sleep, during sleep, and upon waking. The unstimulated salivary flow rate (USFR) and stimulated salivary flow rate (SSFR) were measured before sleep and upon waking. Correlations between the RMMA index, degree of oral moisture, and salivary flow were examined.

Results: Seventeen participants (10 males, 7 females, 28.2 ± 8.6 years old) were included. The degree of oral moisture and USFR were not significantly correlated with the RMMA index. The SSFR before sleep demonstrated a significant moderately negative correlation with the RMMA index (ρ = -0.637). The frequency of RMMA that occurred with swallowing per hour demonstrated a significant negative correlation with the SSFR before sleep and upon waking (ρ = -0.703, -0.527, respectively). Swallowing occurred significantly more frequently in the last one-third of the RMMA episodes, and the frequency of phasic and mixed types of RMMA that occurred with swallowing demonstrated a significant negative correlation with the SSFR before sleep (ρ = -0.583, -0.511, respectively).

Conclusions: These results suggest a relationship between SB and the ability to secrete stimulated saliva. SB may have a functional role in stimulating saliva secretion, and an increase in SSFR may alleviate SB.

Purpose: This study aimed to investigate the effect of light-curing on the fracture load of glass-ceramic discs bonded to dentin.

Methods: IPS e.max CAD (lithium disilicate) and Celtra Duo (zirconia-reinforced lithium silicate) glass-ceramic discs, each 7 mm in diameter, were bonded to flattened dentin using three different cementation strategies. The discs varied in thickness, measuring 0.8 mm and 1.5 mm. The three strategies implemented were as follows: (1) SBU/ULT(AL): auto-cured adhesive and light-cured resin cement, (2) SBU/ULT(LL): light-cured adhesive and light-cured resin cement, and (3) resin composite, which served as the positive control. The fracture loads of eight specimens from each group were evaluated after storing the samples for one week and one year. Data were analyzed using linear mixed-effects models with a significance level of 0.05.

Results: The thickness of the ceramic material and the cementation strategy significantly influenced the fracture load (P < 0.05). Ceramics bonded using SBU/ULT(LL) and composite cement, regardless of thickness, demonstrated significantly higher fracture loads than those bonded using SBU/ULT(AL) (P < 0.05). Ceramics with a thickness of 0.8 mm bonded with either SBU/ULT(LL) or composite cement exhibited fracture loads comparable to those of 1.5 mm thick ceramics bonded with SBU/ULT(AL) (P > 0.05).

Conclusions: Light-curing the adhesive separately from the resin cement (SBU/ULT(LL)) and employing composite cement are recommended strategies for cementing glass ceramics with dentin to enhance fracture load resistance.

Purpose: To investigate the remnant cement in the subgingival regions (RCS) of abutments fabricated with different CAD/CAM parameters, including margin curvature radius, convergence angle, top fillet radius, and subgingival abutment shape.

Methods: Twelve experimental groups were fabricated to test the following parameters: abutment margin curvature radii of 0.8 mm, 1.2 mm, and 1.6 mm; convergence angles of 4°, 8°, and 12°; top fillet radii of 0.6 mm, 1.0 mm, and 1.4 mm; and subgingival abutment shapes of straight, S-curve, and concave. A constant amount of cement was injected into each crown. Vertical and continuous loads were applied to each specimen using a universal machine. RCS values were measured using a 3D intraoral scanner and an analytical balance. Statistical analysis was performed using one-way analysis of variance followed by post hoc Tukey test (α = .05).

Results: Regarding margin curvature radius, RCS values were significantly higher in the order of 1.6 mm, 1.2 mm, and 0.8 mm (P < 0.001). For convergence angle, higher RCS values were observed at 12° > 8° > 4°(P < 0.001). Among subgingival abutment shapes, concave yielded the highest RCS values, followed by S-curve and straight (P < 0.001). No significant differences in RCS values were found among the groups with different top fillet radii (P > 0.05).

Conclusions: Within the limitations of this study, a smaller margin curvature radius, smaller convergence angle, and straight subgingival shape were associated with reduced RCS length, surface area, and weight.

Purpose: The hyoid bone plays a key role in several physiological functions by interacting with the attached muscles. Understanding its kinematics and positional stability is essential for evaluating its functions: swallowing, mastication, intraoral transport, vocalization, and respiration. This study aimed to assess the position of the hyoid bone relative to the cranial base and mandible using cephalometric imaging and to examine its stability.

Methods: Cephalometric images of 140 patients were analyzed using specialized software. The positional relationship between the cranial base and hyoid bone was assessed by measuring the Porion-Hyoid distance (Po-Hy) and the angle between the Po-Hy and the Nasion-Porion line (∠CB-Hy). The relationship between the mandible and the hyoid bone and the cervical angle was also evaluated.

Results: The ∠CB-Hy showed a narrow distribution (mean ± SD: 89.2 ± 5.12°). A weak, but statistically significant, correlation was observed between age and the ∠CB-Hy. Additionally, a significant negative correlation was found between the number of missing molars and ∠CB-Hy, while a strong positive correlation was identified between the cervical angle and ∠CB-Hy. The relationship between the cervical angle and ∠CB-Hy was represented by the following linear regression equation: ∠CB-Hy = 0.484 × Cervical angle + 37.4.

Conclusions: Our findings suggest that the hyoid bone maintains a relatively stable position with respect to the cranial base with only slight variation. However, a significant relationship exists between ∠CB-Hy and cervical inclination. Clinicians and researchers should consider this relationship when assessing the hyoid position in clinical and research settings.

Purpose: To evaluate the effect of proximal box depth and adjacent tooth distance on intraoral scans for inlays.

Methods: Inlay preparation models were designed using a three-dimensional (3D) printing software (Materialise Magics) and manufactured using digital light processing. The models were categorized into three groups based on proximal box depths (4, 6, and 8 mm) and three groups according to adjacent tooth distances (1.2, 1.6, and 2.0 mm). Intraoral scans were performed 10 times using CEREC Primescan (Dentsply Sirona) and TRIOS 3 (3Shape). Reference scan data were obtained using a laboratory scanner (D900L; 3Shape). 3D comparisons between the scan data were performed using 3D analysis software (Geomagic Control X). The root mean square value was calculated to evaluate the trueness of the intraoral scans. Two-way analysis of variance and post-hoc testing with the Bonferroni correction were performed in trueness (α=0.05). Color-coded maps were obtained for the qualitative analysis of deviation.

Results: As proximal box depth increased from 4 mm to 8 mm, the deviation in trueness significantly increased. Similarly, the 1.2 mm distance group showed a greater deviation than the 1.6 and 2.0 mm distance groups. No statistically significant difference was observed between the 1.6 and 2.0 mm distance groups.

Conclusions: The accuracy of intraoral scans is affected by proximal box depth and adjacent tooth distance. A shallow proximal box and a greater distance to adjacent tooth enhance scanning accuracy. However, beyond a certain threshold, further increases in the distance from the adjacent tooth does not improve the scanning accuracy.

Purpose: This clinical study aimed to evaluate the effects of various head positions within physiological movement limits on occlusal contacts (OCs) in digital bite registrations (BRs) obtained using an intraoral scanner (IOS).

Methods: This study included 36 individuals with natural dentition without missing teeth. Maxillary and mandibular scans were performed using an IOS (Trios4). The natural (NHP), forward (FHP), and backward (BHP) head positions were determined using a manual goniometer, and three BRs were obtained using an IOS. A new assessment method, the “digital occlusion analysis” module (oJMA, Zebris), was used to assess the OCs in these BRs. Dental arch scans and BRs were imported into the digital occlusion module. OC evaluation was performed on buccal-lingual cross-sections obtained at 1 mm intervals on the four left and right posterior teeth of the mandible. Each section was evaluated for the number, intensity, and location of OCs between pairwise comparison groups of head positions.

Results: The number of OCs significantly decreased in the BHP-FHP group with respect to contact points (P = 0.03). OC intensity was similar among the three groups. However, OC location was significantly reduced in the NHP-BHP and NHP-FHP groups compared with the NHP group, specifically for functional cusp contacts (P = 0.03, P = 0.018).

Conclusions: Digital BRs obtained in different head positions showed significant differences only in the OC locations in the FHP and BHP compared with the NHP. The effect on the number of OCs was observed as the angle between the head positions increased from FHP to BHP.

Purpose: With the advancement in digital technology, post-and-cores can be produced using full-digital techniques. This study aimed to evaluate the accuracy of two full-digital impression techniques for scanning the post space with different root canal entrance diameters using an intraoral scanner (IOS) (TRIOS 3) with and without a scan post, compared to the half-digital impression technique.

Methods: Standard models of three intact teeth with varying root canal entrance diameters were prepared. Fifteen post-and-core designs per tooth were created using direct IOS and IOS with scan posts, with the half-digital technique as the control. All files were exported as standard tessellation language (STL) files, and the root mean square (RMS) deviations were analyzed between the experimental and control groups. Deviations were measured at standardized points across four regions: the occlusal external, occlusal internal, middle third, and apical third.

Results: No significant differences in the overall RMS were observed among the different root canal entrance diameters (3 mm, 4 mm, and 5 mm) for direct IOS and IOS with scan posts (P > 0.05). However, an independent samples t-test revealed a significant difference (P < 0.05) in both trueness and precision between the two experimental groups, with IOS with scan posts consistently showing lower RMS values.

Conclusions: For post space lengths less than 7.4 mm in single-rooted teeth, both direct IOS and IOS with scan posts can serve as viable alternatives to half-digital techniques. However, in deeper areas, IOS with scan posts are recommended as alternatives to the half-digital technique.

Purpose: This guideline aimed to make evidence-based clinical practice guidelines for the primary treatment of temporomandibular disorders (TMDs) for general practitioners who do not specialize in TMD.

Review process: Following the principles of evidence-based medicine, a systematic review and network meta-analysis (NMA) of multiple treatments was conducted, assessing the certainty of evidence using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach. Randomized controlled trials published between January 2000 and December 2020 were included. Patients diagnosed with TMD according to the Diagnostic Criteria for Temporomandibular Disorders were considered. Myalgia, arthralgia, and maximal mouth opening were selected as outcomes, and 12 treatments were included in the NMA. The modified Delphi method was used to reach a consensus on recommendations during clinical guideline panel meetings of the Japanese Society for the Temporomandibular Joint.

Results: Self-administered mouth opening exercises, stabilization-type oral appliances, and low-level laser therapy (LLLT) were recognized as effective primary treatments, although the evidence level was graded as “very low” (Grade 2D). During the clinical guideline panel meetings, decisions were developed based on the NMA results, and recommendations for clinical practice guidelines were finalized following consensus.

Conclusions: This guideline recommends mouth opening exercises and the use of stabilization-type oral appliances as primary treatments for TMD. Additionally, it suggests that LLLT be a conditional recommendation, supplemented with additional considerations.

Purpose: This study evaluated the cytotoxicity of clinically available dental cements containing resin: conventional adhesive resin cement (ARC), self-adhesive resin cement (SARC), and resin-modified glass-ionomer cement (RMGIC), focusing on their degree of conversion (DC) and effects on cellular responses.

Methods: The DC of all the groups was measured over two weeks under light-free conditions. Cell viability, morphology, and apoptosis were assessed in gingival fibroblasts, dental pulp stem cells, and macrophage cells after exposure to extracts from specimens with different DC values. Eluate analysis was performed using attenuated total reflectance-Fourier transform spectroscopy and gas chromatography/mass spectrometry.

Results: The DC increased rapidly within 20 min for ARC and SARC, reaching a plateau at 24 h, while RMGIC showed a slower increase. ARC and SARC exhibited significant cytotoxicity at lower DC levels, with improved cell viability as DC increased. RMGIC displayed minimal cytotoxicity across all DC levels. Analysis revealed unreacted monomers and other substances contributing to cytotoxicity, with apoptotic effects correlating to their concentration in the eluates.

Conclusions: DC significantly influences the cytotoxicity of resin-containing dental cements, with ARC and SARC showing higher cytotoxic effects at lower DC levels compared with RMGIC. Considering DC levels may guide clinicians in minimizing adverse effects when selecting these cements. Dental cements containing resin can release substances that may affect cell viability.

Purpose: This meta-analysis answers the research question, how does the accuracy of additive manufacturing (AM) compare to that of subtractive manufacturing (SM) for fabricating zirconia fixed dental prostheses (FDPs)?

Study selection: Relevant studies were systematically searched in PubMed, ScienceDirect, Cochrane Library, Scopus, and Web of Science and screened following the PRISMA 2020 guidelines; the inclusion criteria include studies that evaluate the accuracy of FDPs fabricated using AM and SM. Studies were excluded if they did not compare AM and SM, did not use zirconia, or did not assess accuracy. Study quality was assessed using the methodological index for nonrandomized studies, and publication bias was assessed using Egger’s and Begg’s tests.

Results: Sixteen in vitro studies were included. The meta-analysis revealed that FDPs fabricated via AM demonstrated significantly lower trueness compared to that of SM in the intaglio surface (P < 0.01; SMD: 1.37; 95% CI: [0.80, 1.95]; I² = 90%, P < 0.01), marginal area (P < 0.01; SMD: 1.83; 95% CI: [1.17, 2.49]; I² = 91%, P < 0.01), and external surface (P < 0.01; SMD: 2.15; 95% CI: [1.19, 3.12]; I² = 91%, P < 0.01). AM demonstrated significantly higher precision compared to that of SM (P < 0.01; SMD: −1.89; 95% CI: [−2.77, −1.01]; I² = 77%, P < 0.01).

Conclusions: AM technologies exhibit lower trueness compared to that of SM and offer superior precision. Material jetting achieves trueness comparable to that of SM. Both AM and SM satisfy clinical accuracy requirements.

Purpose: This study aimed to investigate the association between xerostomia severity and oral health-related quality of life (OHRQoL) across various functional occlusal statuses among older adults.

Methods: This cross-sectional study recruited 202 outpatients (130 females and 72 males) from a dental university hospital in Japan. Assessments included the Summated Xerostomia Inventory (SXI) for xerostomia, Oral Health Impact Profile-14 (OHIP-14) questionnaire for OHRQoL, saliva collection, and functional occluding units (FOUs). Analyses included Mann-Whitney U tests and regression models. A directed acyclic graph was constructed to identify potential confounders and mediators and ensure appropriate adjustment in the regression models.

Results: The mean age of the participants was 73.7 (SD: 7.6) years, ranging from 60–89 years, and 64.4% were females. The median SXI score was 7 (IQR: 6-8), and 14.4% had a score of 10 or more. The participants with xerostomia had higher OHIP scores than those without xerostomia (median, 15 vs. 9; P = 0.003). Salivary flow measures were not associated with the OHIP scores. However, SXI and FOUs were associated with the OHIP scores in the regression analysis (R²=29.7%). The subgroup analysis revealed that participants with a more FOUs had a stronger association between xerostomia and OHRQoL.

Conclusions: Among the older adults in this study, those with xerostomia and fewer functional occlusions had poorer OHRQoL. The relationship between dry mouth symptoms and OHRQoL was particularly robust among patients with better functional occlusion, suggesting that xerostomia management deserves attention even in patients with well-maintained dentition.

Purpose: This study evaluated the use of pre-sintered cobalt-chromium (Co-Cr) alloy discs in the fabrication of clasps for removable partial dentures, comparing their accuracy and mechanical properties, as determined via tensile testing, with those of conventional fabrication methods.

Methods: Accuracy of the clasps was assessed by obtaining three-dimensional (3D) data (design data) of the Akers clasp. The clasps were fabricated under three conditions: (1) pre-sintered, fabricated from pre-sintered Co-Cr alloy discs; (2) fully sintered, fabricated from fully sintered Co-Cr alloy discs; and (3) cast, fabricated via casting. For each method, 3D data were collected (fabrication data). The design and fabrication data were subsequently superimposed, and the accuracy of the clasps was investigated based on their inner surfaces. The mechanical properties were assessed via tensile testing of dumbbell-shaped Co-Cr alloy specimens fabricated under the same conditions used for accuracy testing (pre-sintered, fully sintered, and cast).

Results: Cast clasps typically exhibited the highest trueness values and fully sintered clasps exhibited the highest precision values. The pre-sintered clasps exhibited high trueness in every part of the rest area; however, the accuracy at the clasp tip was low. In terms of mechanical properties, the pre-sintered clasps exhibited the highest elongation, meeting the standards for Type 4 metals as specified by ISO 22674:2022.

Conclusions: The present study demonstrates that pre-sintered Co-Cr alloy discs are suitable for fabrication of clasps with good fit and mechanical properties, provided that the accuracy of the clasp tip is improved.

Purpose: To evaluate stress distribution in short-crowned molars with distal subgingival defects with various restorations and materials.

Methods: Residual crowns were restored using a post-and-core crown (model A), a full crown (model B), a fissure-post endocrown (model C), an endocrown (model D), an onlay (model E), and an overlay (model F). The ceramic materials used were IPS e.max (EM), Vita Enamic (VE), and Lava Ultimate (LU). Subsequently, finite element analysis was performed by applying 600 N vertical load (0° to the long axis) and 200 N oblique load (45° to the long axis) to simulate chewing loads.

Results: As the elastic modulus of the material increased, the stress on the restorations also increased, particularly under an oblique loading condition. Under vertical and oblique loading conditions, the peak maximum principal stress (MPS) in the dentin was lowest in Group A-EM (17.28 MPa and 5.61 MPa, respectively), following the trend A < B, C < D, F < E. The MPS within the cement was lowest in Group A-EM (2.74 MPa and 2.58 MPa under vertical and oblique loading conditions, respectively). The MPS within the cement in Group H (4.11 MPa) was reduced to approximately one-third of that in Group G (12.35 MPa).

Conclusions: EM exhibited a more uniform stress distribution than other materials and is a promising material for short-crowned molars. A fissure-post endocrown design is a potentially favorable restorative option for short-crowned molars. Fiber posts should be used with full crown restorations.

Purpose: To investigate the accuracy of static and dynamic computer-aided implant surgery (s/d-CAIS) for immediate implant placement for single-tooth replacement in healthy individuals with partially edentulous zones.

Study selection: A systematic search of six electronic databases for clinical studies reporting on Type 1 implant placement identified 15 eligible articles (seven RCTs, two prospective studies, and six retrospective studies) involving 383 patients. The focus question addressed population, intervention, comparison, and outcome criteria. A meta-analysis was performed using a random-effects model to obtain pooled estimates, presented as forest plots with weighted mean differences and 95% confidence intervals. Quality assessment was conducted using the Robin-I and RoB2 tools.

Results: The meta-analysis revealed that s/d-CAIS demonstrated significantly lower global platform and apex deviation compared to freehand placement, with mean differences of -0.70 mm (95% CI -0.74, -0.66; P < 0.001) and -0.86 mm (95% CI -1.00, -0.73; P < 0.001) respectively. The mean difference in platform depth deviation was statistically significant in favor of CAIS, with a mean difference of -0.73 mm (95% CI -1.04, -0.43; P < 0.001). High heterogeneity was observed across studies. The average global coronal, global apex, and angulation deviation for d-CAIS and s-CAIS were 0.72 mm, 0.81 mm, and 2.04 degrees, and 0.80 mm, 1.10 mm, and 2.12 degrees, respectively.

Conclusions: Data on Type 1 implant placement suggest that s/d-CAIS may enhance implant placement accuracy in several dimensions compared with freehand placement, with d-CAIS demonstrating marginally better control over angulation. However, the high heterogeneity across studies with a moderate-to-high risk of bias limits the generalizability of these findings.

Purpose: This review critically examined the impact of various whitening toothpaste formulations on color stability, surface roughness, gloss, and microhardness of dental restorative materials.

Study selection: A comprehensive literature search yielded 101 articles from PubMed, 159 from Embase, and 617 from SCOPUS, spanning 1983–2024, of which 33 met the inclusion criteria.

Results: Studies have shown that whitening toothpastes influence color change and surface characteristics. Hydrogen peroxide (HP) formulations are generally effective in achieving color alteration, although their impact on microhardness and roughness varies. Charcoal-based toothpastes tend to increase surface roughness because of their abrasive nature, whereas blue covarine toothpaste provide some brightening effects but are also associated with higher roughness. Results regarding nanohybrid and microhybrid composites were mixed; some studies found nanohybrids to be superior in color stability, whereas others favored microhybrids. However, nanohybrids are more susceptible to roughness changes due to whitening agents, whereas nanofilled composites consistently demonstrate better surface integrity under abrasive conditions.

Conclusions: These findings highlight the importance of selecting toothpaste formulations that align with restorative material properties to optimize esthetic results without compromising durability. Although HP formulations show promise in balancing whitening efficacy with surface preservation, their long-term effects require further study. Additionally, continued research is needed to refine the formulations, particularly for charcoal and blue covarine, to reduce abrasiveness and extend restoration longevity.

Purpose: To compare abutment and scan body subsidence and determine the appropriate tightening torque value for a scan body that can accurately replicate abutment subsidence.

Methods: An internally tapered connection implant was placed in a bone model. The titanium abutment (Ti Abut), polyetheretherketone scan body (PEEK SB), and titanium scan body (Ti SB) were tightened to torque values of 10 or 35 Ncm, with the 10 Ncm models used as reference models. Both the 10 and 35 Ncm models were scanned using a laboratory scanner. The vertical displacements of the Ti Abut, PEEK SB, and Ti SB at each torque value were determined using three-dimensional analysis software.

Results: Upon tightening the scan bodies and abutment to 35 Ncm, the displacement was significantly greater than when tightened to 10 Ncm (P < 0.01). At 35 Ncm, Ti SB and Ti Abut showed significantly greater displacements than PEEK SB, whereas no significant difference was observed between Ti SB and Ti Abut.

Conclusions: The titanium scan bodies, when tightened at 35 Ncm, accurately replicated titanium abutment subsidence, unlike the PEEK scan bodies.

Purpose: To investigate the optimal post-polymerization temperature and time to enhance the mechanical properties of three-dimensional (3D)-printed nanocomposites.

Methods: A control group of pure 3D-printed resin was used to fabricate specimens post-polymerized at 40 °C for 15 min (n = 6). Next, 3-wt% functionalized yttria-stabilized zirconia (YSZ) nanoparticles were dispersed in a 3D-printed resin to fabricate YSZ-based nanocomposites for the experimental groups. The post-polymerization conditions of six experimental groups (n = 6) were set as two temperatures (40 °C and 80 °C) and three time periods (30, 60, and 90 min). The degree of conversion (DC), flexural strength, modulus, fractography, and hardness values of each group were evaluated. One-way and two-way analysis of variance were applied to analyze significant differences among the control and experimental groups and interaction effect of temperature and time of post-polymerization, respectively (α = 0.05).

Results: Significant reductions in DC values were noted in the experimental groups compared to the control group. The experimental groups demonstrated significantly higher flexural strengths and moduli than those of the control group. At 80 °C, no significant differences were observed for different post-polymerization times. Compared to post-polymerization at 40 °C, the flexural strength, modulus, and hardness were significantly enhanced when the post-polymerization temperature was increased to 80 °C.

Conclusions: Optimal mechanical properties of 3D-printed YSZ-based nanocomposites could be achieved under post-polymerization at 80 °C and 30 min.

Purpose: Human flourishing is a multidimensional concept that encompasses happiness and life satisfaction (happiness), mental and physical health (health), meaning and purpose (purpose), character and virtue (character), and close social relationships (social), which are characterized by comprehensive well-being. This cross-sectional study investigated the association of oral health, number of remaining teeth, and prosthesis use with multidimensional flourishing.

Methods: Data was sourced from the 2022 wave of the Japan Gerontological Evaluation Study, a population-based survey of independent individuals aged 65 years or older. This study utilized multilevel linear regression with multiple imputations. The covariates included sex, age, income, education, marital status, smoking status, diabetes history, instrumental activities of daily living, and depressive symptoms.

Results: This study included 87,201 participants with a mean age of 74.87 years [standard deviation (SD)=6.30], and mean±SD composite flourishing index of 6.77±1.64. Multilevel multivariable regression showed that individuals with dental prostheses or more teeth had a higher flourishing index. Among individuals without dental prostheses, those with >20 teeth showed a composite flourishing index of 0.34 units higher (95% confidence interval (95% CI): 0.26-0.42, P < 0.001) than those with 0-9 teeth. Among those with 0-9 teeth, individuals with dental prostheses showed 0.21 (95% CI: 0.12-0.29, P < 0.001) higher units compared to those without prostheses. The interaction analysis showed that dental prosthesis use was significantly associated with higher indices, especially among those with fewer teeth.

Conclusions: Teeth and prostheses were independently associated with multidimensional flourishing. Using dental prostheses may enhance multidimensional flourishing among individuals with fewer remaining teeth.

Purpose: In this cross-sectional study, we aimed to investigate the association among dietary diversity, ingestible food profiles, and the type of prosthodontic treatment (i.e., removable partial or complete dentures [RD] vs. implant-supported dentures [ID], including implant-supported fixed prostheses and implant-assisted overdentures) in older Japanese outpatients.

Methods: We included 297 patients aged ≥65 years (mean age, 75.3 years) undergoing maintenance therapy for RD or ID. Dietary diversity was assessed using the Dietary Variety Score (DVS) questionnaire. The ingestible food profile, a subjective quantification of the ability to consume foods with high masticatory difficulty, was evaluated using a validated ingestible food questionnaire and assessed using the ingestible food score (IFS). DVS- and IFS-related factors were identified using multiple regression analyses.

Results: The median IFS of the ID group (100.0) was significantly higher than that of the RD group (84.5); however, the median DVS showed no statistically significant difference between the two groups. After adjusting for confounding factors, prosthodontic treatment type (RD) and the number of present teeth (≤20) were found to be significantly associated with low IFS, whereas young age and presence of cardiovascular disease were significantly associated with low DVS.

Conclusions: Older individuals with ID had a better ingestible food profile than those with RD; however, dietary diversity did not differ significantly between the two groups. RD is a potential risk factor for poor ingestible food profile, whereas the prosthodontic treatment type is not a direct risk factor for low dietary diversity.

Purpose: Spark-discharged anodic oxidation coating on commercially pure titanium (SAc.p.Ti) has been shown to promote bone conduction and bone matrix mineralization during new bone formation. This study hypothesized that the combination of SAc.p.Ti with dental pulp stem cells (DPSCs) would enhance new bone formation. The objective was to evaluate the effect of this combination in a rat bone defect model.

Methods: DPSCs were isolated from Sprague–Dawley (SD) rat incisors and cultured. Calvarial bone defects were created in SD rats, followed by transplantation of commercially pure titanium (c.p.Ti), SAc.p.Ti, or SAc.p.Ti combined with DPSCs. Bone formation was assessed using micro-computed tomography (micro-CT). Toluidine blue O staining was employed to evaluate bone-implant contact and the newly formed bone area. Hematoxylin–eosin (HE) staining was performed to identify osteoblast-like cells.

Results: Micro-CT analysis revealed hard tissue formation on the surface of SAc.p.Ti. Toluidine blue O staining showed significantly greater bone-implant contact and newly formed bone area in the SAc.p.Ti/DPSC group compared to the c.p.Ti and SAc.p.Ti groups. HE staining confirmed the presence of osteoblast-like cells at the defect margins, with evidence of new bone formation on the surface of SAc.p.Ti and in the SAc.p.Ti/DPSC groups.

Conclusions: The combination of SAc.p.Ti and DPSCs presents a promising strategy for promoting new bone formation in rat calvarial defect model.

Purpose: We aimed to evaluate the trueness and adaptation of the intaglio surfaces of complete denture metal frameworks fabricated using selective laser melting (SLM) with different building orientations (0°, 45°, and 90°).

Methods: Cobalt-chromium maxillary complete denture metal frameworks were fabricated at 0°, 45°, and 90° using SLM. Trueness measurements were conducted using the best-fit alignment method of three-dimensional inspection software, and adaptation was evaluated using the silicone replica technique. Nonparametric Kruskal–Wallis and Bonferroni tests were performed to determine differences among the groups (P = 0.05).

Results: No significant differences were observed in the root mean square (RMS), positive, and negative deviation values between 0° and 45° group (P > 0.05), and the median, first quartile, and third quartile of each were considered clinically acceptable. For the 90° group, the RMS, positive deviation, and negative deviation values were significantly higher than those of the other groups (P < 0.05). The overall adaptation of the 45° group was better than that of the 0° and 90° groups (P < 0.05), whereas the 0° and 90° groups showed no significant difference (P > 0.05).

Conclusions: The trueness and adaptation of the intaglio surface of cobalt-chromium maxillary complete denture metal frameworks were affected by the building orientation through SLM. Considering both trueness and adaptation, 45° is recommended as the most efficient build orientation for clinical applications.

Purpose: Excessive occlusal forces resulting from inadequate dental prosthesis, along with periodontal infection (PI), lead to severe periodontitis; however, the roles of senescent cells and their involvement in the mechanisms underlying this process remain unclear. Therefore, this study aimed to elucidate the roles of senescent cells and their cell types in severe periodontitis with excessive force (occlusal trauma [OT]).

Methods: To determine whether senescent cells exacerbate alveolar bone resorption, we developed a severe periodontitis rat model by inducing PI and OT and assessed the presence of senescent cells and bone resorption. Senolytics (dasatinib + quercetin [DQ]) were administered to evaluate the changes in the appearance of senescent cells and bone resorption.

Results: PI and OT + PI increased senescent cells as well as osteoclasts. Furthermore, p21 and receptor activator of nuclear factor-kappa B ligand (RANKL) co-expressing cells were observed in the OT + PI group rats, suggesting a correlation between bone resorption and senescent cells. Cell type analysis identified osteoblasts and Th17 cells as RANKL⁺ cells expressing p21 or p16. DQ administration reduced senescent cells and osteoclasts, thereby preventing alveolar bone resorption.

Conclusions: RANKL⁺ senescent osteoblasts and Th17 cells are involved in osteoclastogenesis and bone resorption. Our findings highlight a new target for the prosthetic treatment of severe periodontitis.

Purpose: This study was aimed at investigating the thermal stresses in monolithic zirconia crowns (MZC) of various thicknesses and elucidating their thermal behavior under cooling or heating changes in the oral cavity. Additionally, the clinical availability and potential issues of MZC were examined by comparing them with other crown materials.

Methods: Finite element models comprising MZC (0.5-, 1.0-, and 1.5-mm thick), cement layers, and abutment teeth were subjected to thermal changes from 37 to 5 °C or 60 °C. Using a thermal distribution at 5 s, the thermal stress was calculated and compared with those of gold alloy and resin composite crowns. The loads corresponding to the thermal stresses were also estimated by comparing them with the stresses induced by vertical loading on the occlusal surface.

Results: Tensile stress occurred primarily in the crowns and cement during cooling, whereas compressive stress was generated during heating. Thermal stresses increased from 16.0 to 27.2 MPa with decreasing crown thickness from 1.5 to 0.5 mm and varied with different materials. Although the MZC exhibited the highest thermal stress, the estimated load (200 N) corresponding to the thermal stress was smaller than that of the resin composite (1280 N).

Conclusions: Thinner crowns exhibited higher thermal stress, suggesting an increased risk of failure owing to thermal changes. Despite the higher thermal stress in thinner MZC, the stresses were below the fatigue strength of the material, indicating sufficient resistance to thermal changes in the oral cavity.