Purpose: This study evaluated the effects of two additive manufacturing technologies and three orientations on the accuracy of three-dimensional (3D)-printed complete dentures. Additionally, we examined whether resin differences affected the accuracy of the denture bases under varying printing systems and orientations.

Methods: We printed denture bases using digital light processing (DLP) and a liquid crystal display (LCD) in three orientations (0°, 45°, and 90°) with two photopolymer resins (n = 6). Intaglio surfaces were scanned to obtain experimental data. We evaluated trueness by superimposing experimental data onto master data, and assessed precision by pairing and superimposing two of the six datasets. Deviation was evaluated using root mean square (RMS) and color map data. Statistical analysis was conducted using the Kruskal–Wallis method and Mann–Whitney U test (α = 0.05).

Results: The DLP printer achieved the highest trueness at an orientation of 90°, whereas the precision was minimally affected by the orientation or printing systems. DLP printers performed well with both recommended and non-recommended resins; however, LCD printers demonstrated better accuracy with the recommended resins. At 0° orientation, the trueness color map for both printers showed negative deviation patterns over the entire palatal surface. Across all manufacturing methods, the precision color maps indicated high reproducibility.

Conclusions: Printing system and orientation affect the trueness of 3D-printed dentures. DLP printers set at 90° demonstrated superior trueness for clinical applications. The accuracy was affected by resin, printer, and orientation.

Purpose: This study proposes the development of “Motion-DSD”, an artificial intelligence-assisted workflow for digital smile design (DSD), which enables a dynamic 2-dimensional (2D) simulation of digital diagnostic waxing by transferring an intraoral design onto a frontal facial video, and validates its clinical feasibility.

Methods: A total of 2,000 facial and 190 intraoral images were used to fine-tune the pre-trained neural network, Segment Anything model (SAM), via two sets of low-rank adaptation (LoRA) modules for facial structures and teeth segmentation respectively. A transformation algorithm incorporating a “standard” facial image was developed to align intraoral and facial structures. A Flask-based web user interface (web-UI) was developed for clinical deployment. A participant sample set was prepared to validate the workflow’s performance in a clinical setting.

Results: Two fine-tuned SAMs achieved robust segmentation performance, with a mean Dice score coefficient of 0.886 for the facial dataset and 0.969 for the intraoral dataset. The alignment algorithm effectively transferred the intraoral DSD design onto the participant’s frontal facial video and enabled a 2D simulation of digital diagnostic waxing under various facial expressions, demonstrating its clinical feasibility. The web-UI allows dentists to interactively refine the design and preview simulation results in real time.

Conclusions: Motion-DSD enables the 2D simulation of digital diagnostic waxing from intraoral DSD designs in a dynamic facial context. The workflow overcomes the limitations of static imaging methods and manual alignment, bringing dynamics prior to the physical mockup phase. Further investigations are warranted to quantitatively validate the simulation accuracy and demonstrate its potential advantages over conventional static methods.

Purpose: Polyetheretherketone (PEEK), a high-performance thermoplastic polymer, has been explored as a dental material because of its excellent mechanical strength and biocompatibility. Composite resin has been reported as a viable prosthetic material when appropriate surface treatment is applied to PEEK. We evaluated the effects of ultraviolet and ozone (UV/ozone) irradiation on the bond strength of PEEK.

Methods: Eighty-six rectangular PEEK specimens were fabricated and divided into two surface-pretreatment groups: untreated (CO) and UV/ozone-treated (UV). The contact angle, surface roughness, and chemical composition were analyzed using contact angle goniometry, laser scanning microscopy, and X-ray photoelectron spectroscopy (XPS), respectively. The remaining specimens were assigned to two conditioning groups: no conditioning (NT) and primer conditioning (AD). Cylindrical specimens fabricated by Computer-Aided Design, Computer-Aided Manufacturing (CAD-CAM) composite resin blocks were bonded to the PEEK surface using resin cement. Half of the specimens in each group were subjected to 5000 thermal cycles. The shear bond strength was tested using a universal testing machine and the fracture surfaces were examined under a stereomicroscope. Statistical analyses were performed using t-tests (α = 0.05).

Results: UV/ozone treatment significantly reduced the contact angle, improved the surface wettability, and caused slight changes in the surface roughness. XPS analysis revealed a decrease in the C=O bonds and an increase in the C-OH bonds in the UV/ozone-treated group. The shear bond strength improved significantly, particularly in the AD group.

Conclusions: UV/ozone treatment of PEEK surfaces increased the wettability and significantly improved the shear bond strength of the composite resin blocks.

Purpose: To evaluate the trueness of denture bases fabricated using digital light processing (DLP) and milling methods using three-dimensional (3D) models with varying residual ridge morphologies.

Methods: Edentulous mandibular 3D models representing a well-rounded ridge (WR), knife-edge ridge (KR), and flat ridge (FR) were designed using computer-aided design (CAD) software. Denture bases for these models were created using dental CAD software and fabricated via DLP 3D printing at build angles of 0 and 45 degrees (DLP0 and DLP45) and by milling (MIL). A total of 90 denture bases were fabricated, with 10 bases per model–method combination. These bases were digitized and compared to their original CAD data to assess the adaptation across three regions: denture border, alveolar ridge, and retromolar pad. Measurements were performed at three time points: before water storage, after 1 day of water storage, and after 7 days of water storage.

Results: The MIL bases exhibited significantly lower 3D surface deviations than the DLP0 and DLP45 bases. The KR models generally exhibited greater 3D surface deviations than the WR and FR models. Temporal changes in the denture bases were significant across almost all ridge types and manufacturing methods.

Conclusions: The trueness of digitally fabricated denture bases is influenced by the residual ridge morphology and manufacturing method. Milling demonstrated superior trueness compared to DLP. Temporal dimensional changes were observed in almost all the bases.

Purpose: This systematic review aimed to investigate and compare peri-implant soft-tissue responses to tooth-colored abutment materials frequently used in implant dentistry.

Study selection: A comprehensive electronic search was performed in three databases (MEDLINE via PubMed, Google Scholar, and Scopus) to identify relevant literature. The study-selection criteria included original research articles written in English that investigated the effects of various tooth-colored abutment materials on peri-implant soft-tissue responses.

Results: In total, 136 articles were included in this systematic review. Tooth-colored abutment materials, particularly zirconia and polyetheretherketone (PEEK), facilitated favorable soft-tissue adaptation, enhanced esthetics, and contributed to long-term implant success. Zirconia demonstrated excellent biocompatibility, enhanced cell viability and attachment, and lower inflammatory responses compared to titanium, suggesting improved soft-tissue integration and reduced biofilm-related risks. PEEK exhibited favorable mechanical properties and biocompatibility but limited cell attachment due to its hydrophobicity, indicating the need for surface modification. Titanium remains the clinical standard for integration but is associated with greater inflammation and biofilm formation than tooth-colored materials.

Conclusions: This review highlights the effects of tooth-colored abutment materials on peri-implant soft-tissue responses and emphasizes the importance of selecting appropriate materials for successful dental implants. Zirconia represents a promising biological alternative to titanium, promoting a stable soft-tissue barrier that contributes to minimizing inflammation and maintaining long-term tissue health. Conversely, while PEEK offers strong mechanical properties, it faces challenges regarding cell proliferation and matrix production, limiting its optimal biological performance. Further research will provide deeper insights into the best options for enhancing patient and esthetic outcomes.

Purpose: We aimed to verify the hypothesis that patients who undergo prosthetic treatment with a definitive obturator following maxillectomy for oral tumors show decreased oral functions when the maxillary defects are extensive.

Methods: This study comprised 77 patients (46 men, 31 women; mean age, 71.0 years) who underwent prosthetic treatment with definitive obturators designed to restore maxillary defects following maxillectomy owing to an oral tumor. Oral function, masticatory performance, maximum bite force, tongue pressure, and tongue-lip motor function (oral diadochokinesis /pa/, /ta/, /ka/) were evaluated. The extent of maxillary defects was evaluated based on Aramany’s classification. The maxillary defects were classified into three groups, namely, no oroantral communication (NOC), small oroantral communication (SOC), and large oroantral communication (LOC) groups. Multiple regression analyses were performed with each oral function as the objective variable and age, sex, maximal mouth opening, history of radiotherapy, number of functional teeth, and the extent of the maxillary defect as explanatory variables.

Results: The number of functional teeth and LOC were significant as explanatory variables for masticatory performance, while sex, number of functional teeth, and LOC were significant as explanatory variables for maximum bite force. Regarding other oral functions, the extent of the jaw defect was not significant as an explanatory variable.

Conclusions: In patients with maxillary defects wearing definitive obturators, a defect exceeding half of the palate and communicating with the nasal cavity was significantly associated with lower masticatory performance and maximum bite force.

Purpose: To investigate the effects of coffee and orange juice on 3 different esthetic ceramic materials regarding color changes, Vickers microhardness, and solubility & sorption changes among patients with reflux.

Methods: A glass-ceramic material (IPS Emax CAD), a polymer-infiltrated ceramic material (Vita Enamic), and a nano-hybrid ceramic material (Cerasmart) were selected for this study (n=32/group). Following the polishing procedure, all the samples were immersed in artificial saliva for 21 days. Half the samples were assigned to the control group and exposed only to artificial saliva (pH 7.3). The remaining 16 samples were exposed to saliva or simulated gastric acid. Sixteen samples from each group were exposed to gastric acid 3 times daily for 30 seconds. The color, Vickers microhardness, and solubility & sorption were then measured. Following this procedure, the samples were exposed to coffee and orange juice (n=8/per group). The samples were exposed to the solutions for 16 hours and 48 minutes to simulate 21 days of consumption. Final measurements were then obtained. Statistical significance was determined using Levene’s test to compare variances, and three-way analysis of variance (ANOVA) followed by Tukey’s post-hoc test, Welch’s ANOVA, and Games–Howell’s test were applied to reveal differences between groups.

Results: According to ANOVA, restorative material type and immersion media had a significant effect on color change (P < 0.001), microhardness (P < 0.001), and solubility & sorption (P < 0.001).

Conclusions: The choice of material is crucial for erosion-prone patients.

Purpose: We evaluated the effects of the particle size and content of surface pre-reacted glass-ionomer (S-PRG) filler on the mechanical properties and antimicrobial efficacy of a hard denture relining material.

Methods: S-PRG microfiller (0.8–1 μm; 5, 10, and 20 wt%) and nanofiller (0.3–0.5 μm; 2.5, 5, and 10 wt%) were incorporated into a Shofu denture liner. The control group did not contain S-PRG fillers. The surface morphology (scanning electron microscopy), roughness (confocal scanning laser microscopy; Shapiro–Wilk’s test followed by Dunnett or Steel’s test), ion release after 24 h immersion in ultrapure water (fluoride, aluminum, borate, sodium, silicate, strontium ions; Shapiro–Wilk’s test followed by one-way ANOVA with Tukey’s test or Kruskal–Wallis and Dunn’s tests), three-point flexural strength (Weibull analysis), shear bond strength after 24 h water immersion or 10,000 thermal cycles (linear mixed-effects model), and antimicrobial activity against Candida albicans (confocal microscopy, Shapiro–Wilk’s test followed by Dunnett’s or Steel’s test) were analyzed and compared. The significance level was set at α = 0.05.

Results: Although a higher S-PRG filler content reduced the flexural and bond strengths, it increased the surface roughness and ion release. Groups treated with 10 wt% nanofiller or 20 wt% microfiller displayed significantly inhibited C. albicans adhesion. The nanofiller-containing groups maintained flexural strength comparable to that of the control.

Conclusions: The incorporation of 10 wt% S-PRG nanofiller provided the best balance between antimicrobial efficacy and mechanical performance, indicating that this formulation may be clinically acceptable for use in hard denture relining materials.

Purpose: This study evaluates the effects of different abutment screw tightening protocols and implant materials on screw loosening and morphological changes after cyclic torsional loading of two-piece implants.

Methods: Titanium (T) and zirconia (Z) two-piece implants were used. Abutment screws were tightened to 35 Ncm. Three protocols were tested: (A) retightening after 5 min, (B) immediate retightening, and (C) no retightening (n = 6 each). All samples underwent 100,000 cycles of cyclic torsional loading. Removal torque values before and after loading (RT-pre and RT-post) and torque loss percentage (TL) were calculated. Surface morphology was assessed using scanning electron microscopy (SEM), and dimensional changes were quantified using root mean square (RMS) values from three-dimensional data.

Results: In the titanium group, protocol A (TA) had lower RT-post values than protocols B (TB) and C (TC) (P < 0.001), and TB was lower than TC (P < 0.05). In the zirconia group, protocol A (ZA) was significantly lower than protocols B (ZB) and C (ZC) (P < 0.05, P < 0.001, respectively). RT-post and RT-pre were significantly lower in the zirconia group than in the titanium group under all conditions (P < 0.001). No differences were observed in TL. SEM revealed wear on the screw heads and threads in all groups. RMS values were significantly lower in the zirconia group (P < 0.05).

Conclusions: Abutment screw retightening does not consistently enhance torque maintenance under torsional loading. The implant material affects torque retention and deformation, where titanium implants demonstrating greater stability than zirconia implants.

Purpose: Masticatory exercise promotes systemic health and cognitive function. Although acute masticatory stimuli enhance prefrontal cortical activity, the effects of increased habitual chewing on cortical activity remain unclear. This study evaluated the effects of habitual chewing on cortical activity in young adults.

Methods: Forty-one young adults (aged 21-31 years) were randomly assigned to an intervention group, which used a wearable device to increase attentional chewing strokes during meals for 1 month, or a control group that did not use the device. We monitored the cortical activity during gum chewing using functional near-infrared spectroscopy at baseline and immediately after intervention. We recorded the number of chews per rice ball at baseline, immediately after intervention, and at 3 months post-intervention. Changes across different time points in each group were compared using one-sample t-tests with Bonferroni correction.

Results: The intervention group showed a significant increase in the number of chews after the intervention and at the 3-month follow-up, whereas the control group exhibited no changes. Moreover, the intervention group demonstrated significantly higher activity in the dorsolateral prefrontal cortex (DLPFC) and premotor cortex compared with the control group. A voxel-based correlation analysis revealed a positive correlation between increase in chewing strokes and activity in these brain regions in the intervention group (family-wise error-corrected, P < 0.05).

Conclusions: Intentional chewing, enhanced through an attentional intervention, led to increased activation in the DLPFC and premotor cortex during mastication. These results demonstrated the objective neural effects of interventions targeting habitual masticatory behavior.

Purpose: Extensive maxillectomy may result in rapid contour changes in the unsupported facial tissue, causing irreversible and severe aesthetic deformities. This technical report details a novel digital workflow for the fabrication of obturators with immediate facial support consistent with the existing maxillary contour.

Methods: Preoperative digital impressions were obtained using an intraoral scanner (IOS). A three-dimensional (3D) model of the presurgical maxillofacial hard tissue was constructed using cone-beam computed tomography (CBCT) and aligned with the IOS data. Surgical planning data were used to guide the separation and fusion of anatomical reference data for obturator design from the CBCT and IOS data. The obturator was designed using dental design software, and the existing maxillary morphology for facial support was transferred to the obturator. After the surgical resection, an immediate obturator with a surgical pack was placed at the defect site.

Conclusions: The implementation of a fully digital workflow demonstrated the potential to streamline the complex procedure traditionally required to restore harmonious facial contour support through the transfer of maxillary morphology to the immediate obturator. This method offers a promising and viable alternative to conventional techniques, with the potential to minimize long-term aesthetic compromise, facilitate adaptation and functional restoration, and simplify postoperative prosthetic care.

Purpose: This study aimed to determine whether the maximum compressive force exerted on denture base materials by test foods varies depending on the presence and type of resilient denture liners.

Methods: The maximum compressive forces of gummy jelly and peanuts were measured using a texture analyzer equipped with a 500 N load cell, operating at a crosshead speed of 9.78 mm/s. Tests were conducted on rectangular prism-shaped specimens (30 mm × 30 mm × 4 mm) fabricated from various denture base materials. Three commercial silicone-based resilient denture liners—Sofreliner Supersoft (SS), Sofreliner Mediumsoft (MS), and Sofreliner Tough Medium (TM)—and a conventional heat-cured acrylic resin (Urban, UR) were used. Additionally, the Shore A hardness of each material was measured using a hardness tester.

Results: The maximum compressive forces applied to gummy jelly and peanuts on UR specimens were significantly higher than those on TM, MS, and SS specimens. Similarly, the Shore A hardness of UR was higher than that of the other materials. A statistically significant positive correlation was observed between the maximum compressive force of the test foods and the Shore A hardness of the denture base materials.

Conclusions: The maximum compressive force applied to food varied according to the type of denture base materials. In particular, resilient denture liners effectively reduced the force transmitted to the food compared with conventional hard acrylic resin.

Patients: This report presents a minimally invasive, adhesive-friendly approach for the esthetic rehabilitation of multiple anterior teeth using a modified direct-indirect technique with ultrathin composite resin veneers. A 43-year-old woman presented with esthetic concerns and disharmony of the maxillary anterior region. The treatment comprised ultrathin composite resin veneers fabricated using a modified direct-indirect technique, incorporating a fully digital workflow with a smile design and a three-dimensional-printed model used to create a translucent silicone index. Without tooth preparation, the index was filled with composite resin and intraorally positioned to replicate the planned morphology. The veneers were removed, post-cured, and extraorally completed before definitive adhesive cementation.

Discussion: Traditionally, the direct-indirect technique has been limited to single restorations that require enamel reduction and freehand stratification. This report describes a modified approach that enables the fabrication of multiple ultrathin veneers without tooth preparation, thereby preserving the enamel and promoting adhesive longevity. The innovative aspect lies in the integration of a fully digital workflow, ensuring precise replication of the morphology and control of the restoration thickness. Extraoral finishing of proximal contacts and margins before cementation improves clinical efficiency and esthetic predictability.

Conclusions: For patients requiring multiple composite veneers, the modified direct-indirect technique provides a conservative, precise, and predictable solution. It preserves sound tooth structure, optimizes adhesive performance, and enhances efficiency and esthetic outcomes through digital integration.

Purpose: To elucidate how the combination of acidic and sulfur-based monomers enhances bonding to oxidized noble metal alloy surfaces.

Methods: Two types of gold alloys were used: one with a low copper content (DG) and the other with a high copper content (IV). Three primers were used: a sulfur-based monomer primer (VP), a phosphate-based acidic monomer primer (PZ), and a combination of both (MC). Two conditions were used: heated and non-heated. The shear bond strengths before and after thermocycling were determined and compared for each condition. Surface chemical analysis was performed using X-ray photoelectron spectroscopy (XPS).

Results: After thermocycling, the bond strength of MC was significantly higher than that of the VP under all conditions. In the comparison of alloys under heating conditions, IV showed a significantly higher bond strength than that of DG for the PZ and MC groups. XPS revealed peaks attributed to copper oxide (CuO) formation on the heated IV surface.

Conclusions: Multipurpose primers are effective for bonding oxidized noble metal alloys and acrylic resins. The formation of CuO improves the performance of 10-methacryloyloxydecyl dihydrogen phosphate, and its combination with sulfur-based monomers is particularly effective for noble metal alloy surfaces with high copper content.

Purpose: The purpose of this study was to establish chevron-notched beam (CNB) finite element analysis (FEA) models to investigate the fracture toughness of zirconia ceramics.

Methods: Experimental four-point flexural strength data (n = 9; previously published) for 3 mol% yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP; 3M Oral Care, Seefeld, Germany) were combined with numerical data (calculated using the inverse finite element method) to evaluate the input material properties of the CNB-FEA models. These models (n = 8) were then simulated and validated against the CNB test data of specimens with the same geometries (n = 8). The validation criteria included the margin of error, coefficient of determination, and linear regression. FEA was used to evaluate the volumetric strain distribution during deformation.

Results: 3Y-TZP has static elastic modulus and fracture strain values of 144.5 GPa and 0.0056, respectively. The fracture toughness of the CNB-FEA models closely matched those of the corresponding test specimens (±3% error). Linear regression yielded a coefficient of determination (R²) of 0.94 (P < 0.05), demonstrating an excellent predictive performance. The CNB-FEA models accurately reflected the actual fracture behaviors of the zirconia ceramics, with the volumetric strain localized at the notch tip.

Conclusions: The volumetric strains of the CNB-FEA models could be determined using the FEA and measured four-point flexural strength data. Thus, CNB-FEA was found to be a valuable method for predicting the fracture toughness of zirconia ceramics.

Purpose: This study evaluated the wear behavior of dental materials for definitive fixed prostheses, including computer-aided design (CAD)- and manufacturing (CAM) composite resins, polyether-ether-ketone (PEEK), Ag-Pd-Au alloys, titanium, and zirconia, under standardized experimental conditions.

Methods: Three CAD-CAM-produced composite resins (HC, HCH, and CS), PEEK (SPE), Ag-Pd-Au alloys (CW), pure titanium class II (TJ), and zirconia (ZL) were tested. Two-body wear tests were conducted using an abrasion-testing machine under wet conditions using stainless-steel styluses as antagonists. Wear traces were examined using laser confocal scanning microscopy and scanning electron microscopy (SEM). Wear depths and heights were analyzed by one-way analysis of variance with Tukey’s multiple comparison test.

Results: The wear depths of CS and TJ were significantly greater than those of the other materials (P < 0.05), whereas ZL exhibited the lowest wear depth. No significant differences were found among HC, HCH, SPE, and CW. The stylus opposing the SPE exhibited the smallest wear height, whereas TJ caused the most antagonist wear. SEM revealed distinct wear mechanisms, including adhesive and abrasive wear, depending on the material.

Conclusions: The SPE and CW showed similar wear behavior. CAD/CAM composite resins demonstrated variable wear rates, which was likely attributable to variations in the composition and morphology of the constituent fillers. The TJ exhibited excessive antagonist wear, suggesting the need for improved tribological properties. These findings provide guidance for selecting materials that preserve occlusion and prevent excessive wear.

Purpose: This review examined clinical and technological factors that influence implant placement accuracy in computer-assisted implant surgery (CAIS) systems.

Study selection: A systematic search of PubMed, Scopus, and Embase identified English-language studies published between January 2015 and January 2025. The eligible studies included randomized controlled trials, observational studies, systematic reviews, in vitro investigations, and case reports. Data extraction focused on the coronal, apical, and angular deviations. Methodological quality was appraised using the Oxford Centre for Evidence-Based Medicine (CEBM) framework and validated bias assessment tools.

Results: Fifty-three studies were included. Accuracy was influenced by patient-related factors (arch type, bone density, and edentulous span), surgical variables (flap design, operator experience, and guide protocol), and technological parameters (imaging modality, fiducial markers, and calibration). Static systems achieved high accuracy in dentate cases with stable guide support, but were less reliable in posterior or edentulous jaws. Dynamic navigation provided intraoperative flexibility and consistent performance across arches, although outcomes depended on calibration precision and operator learning curves. Robotic-assisted systems achieved the lowest mean deviations through trajectory control and haptic feedback, although evidence remains limited to early clinical and in vitro studies.

Conclusions: Although all CAIS systems achieve high accuracy, their performance varies according to the design of the system and clinical context. Static systems are effective when stabilization is ensured, while dynamic navigation offers adaptable accuracy across scenarios, and robotics exhibit the greatest consistency by reducing operator variability. Further multicenter randomized trials and standardized reporting are needed to strengthen the available evidence and guide clinical selection.

Purpose: To assess the time efficiency of an innovative workflow (SafetyCrown) for implant-supported rehabilitation of posterior single-tooth sites against the standard workflow. The hypothesis was that there is no difference in treatment duration and accuracy, as represented by the number of clinical adjustments and additional visits required.

Methods: 31 participants (16 females, 15 males) were included in this analysis from a randomized clinical trial. Participants were randomly assigned to the test group (SafetyCrown workflow, three visits) or control group (conventional digital workflow, six visits). The SafetyCrown workflow combined immediate restoration with a prefabricated definitive abutment and chairside provisional restoration. The control group followed a conventional digital approach in six visits. Treatment times per visit were recorded with a stopwatch; clinical adjustments and additional visits were documented.

Results: The SafetyCrown workflow was completed in three visits in 53% of cases, with a mean of 3.5 visits compared with 6.1 visits in the control group. The total treatment time differed insignificantly by 10 minutes (test: 126.4 minutes; 95% CI: 116.4–136.5; control: 116.8 minutes; 95% CI: 104.4–129.3; P = 0.232), and individual visits lasted longer in the test group (e.g., surgical visit: 62 minutes vs. 33 minutes in control). Clinical adjustments were common in both groups when using model-free workflows.

Conclusions: Limitations aside, the SafetyCrown workflow reduced the total visits while maintaining the overall treatment time despite longer individual appointments, thus increasing efficiency. Both fully digital workflows were feasible, although frequent adjustments highlight the need to investigate sources of inaccuracy to improve the precision and efficiency further.

Purpose: Conventional handheld pH meters have measurement limitations. Therefore, this study aimed to continuously measure the salivary pH at two intraoral locations using a newly developed sensor system.

Methods: In this pilot study, we developed custom-made intraoral mouthguards (MG) with two pH sensors in the anterior region (Channel 1: Ch1) and the buccal side of the maxillary molar (Channel 2: Ch2) to continuously monitor salivary pH at two different locations in the oral cavity.

Results: The coefficient of determination (R²) for all MG sensor measurements was ≥0.99, with a high level of accuracy. Both sensor channels exhibited similar mean pH values for standard solutions, with small and constant variations. However, notable unstable differences in intraoral measurements were observed during rehydration owing to positional differences. Nonetheless, the MG sensors demonstrated excellent reliability with consistently high Intraclass Correlation Coefficients ranging from 0.977 to 0.999.

Conclusions: This pilot study provides valuable insights into salivary pH fluctuations, particularly during exercise, through continuous measurements using a sensor system for the simultaneous acquisition of real-time data from different anatomical sites. These results emphasize the potential of developing an intraoral sensor system that can detect subtle variations in salivary pH.

Purpose: Hard reline procedures are commonly used to improve denture fit; however, the long-term durability of reline materials remains unclear. This study evaluated time-dependent changes in the surface properties and biofilm adhesion of light- and auto-polymerizing hard reline materials following long-term immersion in artificial saliva. The findings may help determine optimal timing for clinical intervention and enhance prosthesis longevity.

Methods: Specimens of three materials—light-polymerizing reline, auto-polymerizing reline, and heat-polymerizing denture base polymethyl methacrylate—were immersed in artificial saliva for up to 180 days. Auto-polymerizing materials continue to polymerize over time, whereas light-polymerizing materials require light irradiation. The surface properties were evaluated based on Vickers hardness, surface roughness, color stability, contact angle, and Candida albicans (C. albicans) biofilm adhesion.

Results: After 180 days, the light-polymerizing material exhibited a significant increase in hardness (P < 0.001), whereas the auto-polymerizing material exhibited an increase from day 120 (P < 0.001). Contrastingly, the heat-polymerizing PMMA exhibited a significant decrease in hardness. The surface roughness increased nearly threefold for the auto-polymerizing material, indicating pronounced degradation. Color changes in the light-polymerizing material were weaker than those in the auto-polymerizing material at all time points except at 60 and 150 days. C. albicans adhesion increased significantly in the auto-polymerizing material (P = 0.034), whereas the light-polymerized material showed no significant change (P = 0.258).

Conclusions: Time-dependent changes in surface characteristics were observed in both reline materials. The light-polymerizing material superior stability throughout the immersion period compared with that of the auto-polymerizing material, indicating superior long-term performance.

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: 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.