Purpose: Botulinum neurotoxin (BoNT) is a biological toxin produced by Clostridium botulinum. BoNT is a potent toxin extensively used in therapeutic interventions. This review provides an updated overview of the mechanisms of action and clinical applications of BoNT in head and facial region.

Study selection: MEDLINE/PubMed searches were conducted using the terms “botulinum neurotoxin” and “dentistry” along with a combination of other related terms. In addition, studies were manually selected from reference lists of the selected articles.

Results: The Food and Drug Administration in the United States initially approved BoNT to treat strabismus, blepharospasm, and hemifacial spasms. The use of BoNT in dermatology and cosmetics has been widely established and has created a revolution in these fields. Over the years, its applications in various medical specialties have expanded widely. Owing to its safety, efficacy, and long duration of action, it is well-accepted by patients. BoNT/A and BoNT/B are widely used in clinical practice. Several off-label uses of BoNT in the dental fraternity have yielded promising results. We have elaborated on the speculated mechanism of action, dosage, effective sites of injection, and adverse effects of each therapeutic application. The various clinical indications for BoNT include bruxism, myofascial pain, temporomandibular joint dislocation, hemifacial pain, orofacial dystonia, facial paralysis, chronic migraine, and trigeminal neuralgia.

Conclusions: BoNT is a safe treatment that can be used effectively, provided that the clinician has adequate knowledge regarding the mechanism, injection techniques, and local and systemic side effects and that it is administered cautiously and purposefully.

Purpose: This systematic review aimed to evaluate the effect of the abutment material on peri-implant soft tissue health and stability.

Study Selection: An electronic and hand search was conducted until February 2022. Only prospective randomized trials (RCTs) and controlled clinical trials (CCTs) comparing titanium abutments with abutments made of different materials, with a follow-up of at least 6 months, were selected by two independent reviewers. Data on marginal bone loss (MBL) and peri-implant tissue indexes, i.e., plaque index (PI), bleeding on probing (BOP), probing depth (PD), and recession (REC), were collected. The risk of bias for RCTs and non-RCTs was evaluated according to the tool reported in the Cochrane Handbook for Systematic Reviews of Interventions and the ROBINS-I tool, respectively. Both pairwise and network meta-analyses (NMA) were performed.

Results: We included 18 relevant studies from 1,437 identified studies. Overall, 612 patients were treated, and 848 abutments were inserted. Five studies presented a low risk of bias. Pairwise meta-analysis showed that, as compared to titanium, zirconia abutments presented a significantly reduced MBL (0.20 mm, 95% Confidence Interval CI [0.14–0.26], P < 0.00001). No significant differences were found for the other outcomes. In the NMA, zirconia abutments demonstrated an 83.3% probability of achieving the highest rank in PI, an 87.0% in BOP, and a 65.0% in PD outcome, suggesting that zirconia abutments generally performed better than titanium and alumina abutments.

Conclusions: Within the limits of the present study, zirconia abutments seem a viable alternative to titanium ones.

Purpose: The aim of this retrospective study was to determine the outcome of double crowns (DCs) using pooled data over a period of 27 years.

Methods: Billing data were obtained from the digital accounting system of a university dental clinic. All DCs inserted and invoiced from January 1, 1992, to December 31, 2019, were collected. The maximum observation period of a DC was determined by a recorded follow-up or the occurrence of a target event. Target events were divided into primary, i.e., tooth extraction, and secondary, i.e., failure of DC, types. The dataset was analyzed using descriptive statistics and Kaplan–Meier survival and multivariate Cox regression analyses.

Results: A total of 4,097 tooth-supported DCs in 1,148 patients were included in the analysis. The mean observation period for individual DC was 5.32 years. The cumulative survival rates at 5 and 10 years for the primary target event were 89.7% and 73.8%, respectively. The cumulative survival rates at 5 and 10 years for the secondary target event were 83.6% and 60.6%, respectively. In the multivariate analysis, age and metal denture bases were significantly associated with both target events.

Conclusions: This study confirmed DCs as a reliable and long-term successful treatment option for anchoring removable partial dentures. The use of a metal denture base and a younger patient age might reduce the risk of complications.

Purpose Completely edentulous arches can be restored using various prosthetic modalities, and the treatment outcome may include masticatory and speech discomforts. This study aimed to investigate the current status of prosthetic restoration modalities used for completely edentulous patients and investigate the association between prosthetic restoration modalities and subjective discomfort in mastication and speech by analyzing nationwide big data.

Methods Of 97,622 individuals, data from 1,576 adults aged ≥40 years with no natural teeth and no requirement for 
additional prosthetic treatments were included. Oral examination data were analyzed, and the prostheses of the edentulous arches were categorized as follows: CD, removable complete denture; OD, implant-retained overdenture; and IF, implant-supported fixed dental prosthesis. Discomforts in mastication and speech according to the prosthetic restorative modality groups was statistically analyzed using analysis of covariance (α = 0.05).

Results The maxillary/mandibular prosthetic restorative modality most commonly used was CD/CD, followed by CD/OD, IF/IF, OD/OD, and CD/IF, with weighted percentages of 93.23%, 2.48%, 1.83%, 1.46%, and 0.84%, respectively. Even after adjusting for various covariates, masticatory discomfort in the CD/CD group was significantly greater than that in the OD/OD (P = 0.0004) and IF/IF (P = 0.0002). The CD/CD group also had significantly greater discomfort in speech than did the IF/IF group (P = 0.0119).

Conclusions Most completely edentulous patients were rehabilitated with bimaxillary removable complete dentures; however, the discomforts in mastication and speech were the lowest when both arches were restored with implant-supported fixed restorations.

Purpose: To verify the effect of abutment tooth location on the accuracy of digital impressions obtained using an intraoral scanner (IOS) for removable partial dentures (RPDs).

Methods: The target abutment teeth included the left first premolar (#34), second molar (#37), and right second premolar (#45) in a mandibular Kennedy class II model and the left and right second molars (#37, #47) in a class III model. Only #37 was isolated from the remaining teeth by the mucosal area in both models. Digital impressions were obtained using a desktop scanner (reference data) and an IOS (IOS data; scanning origin #37; n=10). The general trueness based on the entire model superimposition (T_G), local trueness (T_L) of an individual tooth, and dimensional accuracy (coordinate and linear accuracy) of the IOS data of the target abutment teeth were compared (α=0.05).

Results: In both models, #37 showed significantly inferior T_G (P<0.01), superior T_L (P<0.01), and mesial coordinate displacement (P<0.01 and P<0.05 in class II and III models, respectively). Intra-model comparisons showed that #45 in the class II model and #47 in the class III model had significantly inferior linear accuracy (P<0.05 and P<0.01, respectively) and buccal coordinate displacement (P<0.05 and P<0.01, respectively) compared with the other target teeth.

Conclusions: In digital impressions of RPDs, isolation of abutment teeth by mucosal areas can reduce general trueness based on the entire dental arch and mesial tooth displacement, whereas increased distance from the scanning origin can adversely affect local trueness and dimensional accuracy.

Purpose: Removable partial dentures have a wide range of applications as missing tooth prostheses, and the denture design can be quite diverse. However, the factors affecting masticatory function remain unclear. We investigated the effect of denture design, especially the use of indirect retainers and major connectors, on masticatory function in patients with mandibular bilateral distal extension dentures.

Methods: Fifty-three patients with mandibular Kennedy Class I and Eichner classification B occlusal support were included in this study. Masticatory performance (MP) was assessed using gummy jelly. For the dentures, the type of major connector (bar or apron), presence or absence of indirect retainers, number of rests, and number of artificial teeth were evaluated. The number of functional teeth and occlusal support, Eichner classification, maxillary denture usage, mandibular residual ridge height, and duration of denture use were also evaluated. The factors influencing on the MP were evaluated using the Mann-Whitney U test, Spearman’s correlation coefficient, and logistic regression analysis.

Results: MP was significantly higher when the major connector was bar-type or when there was an indirect retainer than with an apron-type or no indirect retainer. MP was positively correlated with the number of functional teeth, occlusal support, and number of rests. Logistic regression analysis revealed that the number of functional teeth and the presence or absence of an indirect retainer were factors that significantly influenced the MP.

Conclusions: An indirect retainer setting is useful for achieving good masticatory performance in mandibular bilateral distal extension dentures.

Purpose: This study aimed to determine the effects of denture adhesives on denture retention and occlusal force in complete denture wearers in a multicenter, randomized, parallel-group controlled trial.

Methods: Two hundred edentulous patients wearing complete dentures were allocated to three groups: powder-type denture adhesive, cream-type denture adhesive, and control (saline solution). Denture adhesives and saline solution were applied to the dentures for 4 days. The retentive force of the dentures and occlusal force were measured using a force transducer occlusal force meter at baseline and after 4 days of intervention. In addition to between-group comparisons, subgroup analyses of denture retention and occlusal force were performed based on the level of difficulty of the edentulism treatment. The levels were ranked as I (easy), II, III, and IV (difficult).

Results: Cream-type denture adhesives significantly improved the retentive force of the dentures (P<0.01) and occlusal force (P<0.05), with no significant differences between baseline and post-intervention forces in the powder-type denture adhesive and control groups. In within-group comparisons, cream-type denture adhesives improved both the retentive and occlusal forces at Level II (P<0.05), and powder-type denture adhesives improved the occlusal force at Level II (P<0.01).

Conclusions: Application of cream-type denture adhesives effectively improves the denture retention and occlusal force in complete denture wearers with a moderate degree of difficulty during edentulism treatment.

Purpose: Most veneers are mixed targeted restorative space (MTRS)-type restorations that are partially within the original tooth and require inconsistent preparation depths. This study aimed to evaluate the accuracy of the preparation depth for MTRS veneer preparation.

Methods: MTRS veneer preparation models were developed using the twisted maxillary central incisor (MCI) as the original tooth and the standard MCI as the waxing. Veneer preparations were performed using freehand (MF), silicone (MS), thermoplastic (MT), 3D-printed uniform (MD), and auto-stop (MA) guides. The prepared and original MCI were scanned and superimposed using a custom-made base. The mean absolute differences (MADs) were measured to evaluate the accuracy of the preparation depth. Statistical analysis was performed using the multivariate analysis of variance (MANOVA) test (α=0.05).

Results: The accuracy of the preparation depth was 0.237±0.090, 0.191±0.099, 0.149±0.078, 0.093±0.050, and 0.059±0.040 mm in MF, MS, MT, MD, and MA, respectively. The MADs between the groups were significant (P<0.05). The accuracy of the trial restoration was 0.140±0.081 mm in the MS, and the accuracy of the guiding tube was 0.055±0.033, 0.036±0.011, and 0.033±0.010 mm in the MT, MD, and MA, respectively.

Conclusions: In MTRS veneer preparation for MCI, tooth preparation guides improved the accuracy of the preparation depth by visualizing the TRS profile and providing clear measurement points. The accuracy of the guide is influenced by its flexibility, and the accuracy of the preparation depth is affected by the accuracy of the measurement points.

Purpose: To investigate the effects of printing-layer thickness and build angle on the surface characteristics and microbial adhesion of denture base polymers manufactured by digital light processing (DLP).

Methods: Specimens were additively manufactured using DLP. The specimens were printed with different printing-layer thicknesses (25, 50, and 100 μm) and build angles (0°, 45°, and 90°). Scanning electron microscopy was used to observe the surface topography, and the arithmetical mean heights (S_a) were measured. Moreover, the initial Candida albicans (C. albicans) adhesion to the specimens was evaluated using an adhesion test. Finally, two-way ANOVA and Tukey’s multiple comparison tests were conducted.

Results: The results regarding the S_a values exhibited a statistically significant interaction (F (4, 45) = 90.77, P < 0.0001). The build angle has a significant impact on the surface topography. Furthermore, quantitative results revealed that the printing-layer thickness significantly affected C. albicans adhesion (F (2, 99) = 6.96, P = 0.0015).

Conclusions: The surface roughness was significantly affected by the printing-layer thickness and the build angle. Additionally, the surface topography was mainly determined by the build angle. Furthermore, the adhesion of C. albicans to the DLP-printed denture surfaces was significantly affected by the printing-layer thickness but not by the build angle. Consequently, it is critical to decrease the thickness of the printing layer to produce digital dentures with optimal material properties.

Purpose: We examined blood and protein dynamics potentially influenced by implant threads and hydrophilic/hydrophobic states of implant surfaces.

Methods: A computational fluid dynamics model was created for a screw-shaped implant with a water contact angle of 70° (hydrophobic surface) and 0° (superhydrophilic surface). Movements and density of blood and fibrinogen as a representative wound healing protein were visualized and quantified during constant blood inflow.

Results: Blood plasma did not occupy 40–50% of the implant interface or the inside of threads around hydrophobic implants, whereas such blood voids were nearly completely eliminated around superhydrophilic implants. Whole blood field vectors were disorganized and random within hydrophobic threads but formed vortex nodes surrounded by stable blood streams along the superhydrophilic implant surface. The averaged vector within threads was away from the implant surface for the hydrophobic implant and towards the implant surface for the superhydrophilic implant. Rapid and massive whole blood influx into the thread zone was only seen for the superhydrophilic implant, whereas a line of conflicting vectors formed at the entrance of the thread area of the hydrophobic implant to prevent blood influx. The fibrinogen density was up to 20-times greater at the superhydrophilic implant interface than the hydrophobic one. Fibrinogen density was higher at the interface than outside the threads only for the superhydrophilic implant.

Conclusions: Implant threads and surface hydrophilicity have profound effects on vector and distribution of blood and proteins. Critically, implant threads formed significant biological voids at the interface that were negated by superhydrophilicity-induced contact hemodynamics.

Purpose In the treatment of oral tumors, extensive jaw defects due to surgical resection can reduce masticatory performance. Herein, we aimed to clarify the factors related to masticatory performance in patients with jaw defects.

Methods In total, 76 patients (42 male and 34 female) underwent prosthetic treatment with a removable denture for a jaw defect following oral tumor surgery. Data on history of radiation therapy, period of time since surgery, period of use of the present denture, number of remaining teeth, and site of the jaw defect were collected. Masticatory performance was evaluated using test gummy jelly. In addition, maximum bite force, tongue pressure, tongue-lip motor function (oral diadochokinesis /pa/, /ta/, /ka/), and oral dryness were evaluated. Logistic regression analysis was performed with lower masticatory performance scores as the dependent variable. Since multicollinearity was suspected between the oral diadochokinesis /ta/ and /ka/ syllables, two logistic regression analyses were conducted: Model 1 with the /ta/ syllable as an explanatory variable, and Model 2 with the /ka/ syllable as an explanatory variable.

Results In Model 1, a history of radiation therapy, maximum bite force, number of remaining teeth, tongue pressure, and oral diadochokinesis /ta/ were significant explanatory variables. In Model 2, a history of radiation therapy, maximum bite force, number of remaining teeth, and tongue pressure were significant explanatory variables.

Conclusions A history of radiation therapy, maximum bite force, tongue pressure, number of remaining teeth, and motor function of the proglossis are related to decreased masticatory performance in patients with jaw defects.

Purpose: Prenatal stress affects the hippocampal structure and function in pups. Maternal chewing ameliorates hippocampus-dependent cognitive impairments induced by prenatal stress. In this study, we investigated hippocampal microglia-mediated neuroinflammation in pups of dams exposed to prenatal stress with or without chewing during gestation.

Methods: Pregnant mice were randomly assigned to control, stress, and stress/chewing groups. Stress and stress/chewing animals were subjected to restraint stress for 45 min three times daily from gestation day 12 to parturition, and were given a wooden stick to chew during the stress period. Four-month-old male pups were intraperitoneally administered with lipopolysaccharide (LPS). Serum corticosterone levels were determined 24 h after administration. The expression levels of hippocampal inflammatory cytokines were measured, and the microglia were analyzed morphologically.

Results: Prenatal stress increased serum corticosterone levels, induced hippocampal microglia priming, and facilitated the release of interleukin-1β and tumor necrosis factor-α in the offspring. LPS treatment significantly increased the effects of prenatal stress on serum corticosterone levels, hippocampal microglial activation, and hippocampal neuroinflammation. Maternal chewing significantly inhibited the increase in serum corticosterone levels, suppressed microglial overactivation, and normalized inflammatory cytokine levels under basal prenatal stress conditions as well as after LPS administration.

Conclusions: Our findings indicate that maternal chewing can alleviate the increase in corticosterone levels and inhibit hippocampal microglia-mediated neuroinflammation induced by LPS administration and prenatal stress in adult offspring.

Purpose: To evaluate the influence of retainer design and ceramic materials on the durability of minimally invasive cantilever resin-bonded fixed dental prostheses (RBFDPs) after artificial aging.

Methods: One hundred caries-free human mandibular molars were prepared as abutments for all-ceramic cantilevered fixed dental prostheses using the following retainer designs: One wing (OW), Two wings (TW), Inlay ring (IR), Lingual coverage (LC), and Occlusal coverage (OC). Two ceramic materials were used: monolithic high translucent zirconia(z) and zirconia-reinforced lithium disilicate (ZLS₂) (n=10). All restorations were adhesively bonded with resin cement. The thermocycling of the specimens were performed between 5°C and 55°C for 10,000 cycles and then exposed to 240.000 cycles of dynamic loading on a chewing simulator. All surviving specimens were loaded onto the pontic until failure using a universal testing machine.

Results: The mean failure load ranged from 124.00 to 627.00 N for the zirconia groups and from 133.30 to 230.00 N for the ZLS₂ groups. Regarding the materials, a significantly higher failure load was recorded in the zirconia groups than in the ZLS₂ groups (P<0.001), except for OW (P=0.748). Regarding the retainer designs, a significant different failure load was recorded between the different designs except for IR and LC in the zirconia groups, IR and OC, OW and TW, and TW and LC in the ZLS₂ groups (P<0.001).

Conclusions: Zirconia IR, LC, and OC can be used as cantilever RBFDP in the premolar region. The fracture resistance of the ZLS₂ design was below the normal bite force and should not be recommended as the first option.

Purpose: To determine whether the fracture resistance of computer-aided design/computer-aided manufacturing (CAD/CAM) resin-based composites and polymer-infiltrated ceramic network materials cemented on dentin is influenced by the restoration thickness and composite cement application strategy.

Methods: Disc-shaped specimens (Ø = 7 mm) of 0.8 mm and 1.5 mm thicknesses were milled from two CAD/CAM materials: resin-based composite (RBC, Cerasmart 270) and polymer-infiltrated ceramic network (PICN, Vita Enamic). The discs (n = 8 per group) were cemented on flattened dentin using three different cementation strategies: 1) self-adhesive composite cement (RelyX U200) in light-curing mode (LC-SAC), 2) universal adhesive (Single Bond Universal) with composite cement (RelyX Ultimate) in auto-curing mode (AC cement), and 3) adhesive and composite cement as in 2) but in light-curing mode (LC cement). The restorative surface was indented perpendicularly with a compressive load using a universal testing machine until fracture. The fracture resistance (N) of RBC and PICN was separately analyzed using two-way ANOVA and Tukey’s post-hoc test (α = 0.05).

Results: The fracture resistance of each material was significantly influenced by the material thickness and cementation strategy (P < 0.05). Irrespective of the material type and cementation strategy, thicker materials exhibit higher fracture resistance. For RBC, the fracture resistance of the LC cement group was significantly higher than that of AC cement only at 0.8 mm thickness. For PICN, the LC-cement cementation strategy produced superior fracture resistance, regardless of the restoration thickness.

Conclusions: The fracture resistance of Cerasmart 270 was higher for the thicker material; the fracture resistance of LC cement was higher than that of AC cement at 0.8 mm thickness cemented to dentin. In comparison, LC cement showed the highest fracture resistance for Vita Enamic for both material thicknesses.

Purpose Herein, the bond strength (BS) of denture teeth to a denture base resin in a milled monolithic unit was investigated and compared with those of 3D printed teeth to a 3D printed denture base and prefabricated teeth to a heat-cured acrylic resin before and after thermocycling.

Methods Sixty specimens of a denture tooth attached to a cylindrical denture base were fabricated following ISO Standard 19736. Three fabrication techniques—3D printing, conventional compression molding, and milling using monolithic technology—were employed to mill teeth and denture base parts as a single unit. The BS was investigated before and after thermocycling. Data were statistically analyzed using the Kruskal–Wallis test with Bonferroni correction (α = 0.05).

Results Before thermocycling, the mean BS of the milled group was significantly higher than that of the conventional group (P = 0.002). The 3D printed group showed no statistically significant difference from the milled (P = 0.051) and conventional (P = 0.824) groups. After thermocycling, although the mean BS values of the milled (P = 0.00) and 3D printed 
(P = 0.01) groups were significantly higher than that of the conventional group, there was no significant difference between them (P = 0.226). Only the BS of the conventional group was significantly reduced by thermocycling (P = 0.00).

Conclusions The milled monolithic fabrication technique, which eliminates the need for a bonding step, offered a promising combination of high-precision digital fabrication and a significantly high BS. The BS of the conventional group significantly decreased after thermocycling.

Purpose: This study aimed to clarify the effect of occlusal force on appropriate optical interocclusal registration in clinical practice, considering periodontal ligament and jawbone deformation.

Methods: Forty participants with natural, healthy dentition were enrolled (19 men and 21 women; mean age, 27.7 ± 2.0 years). A TRIOS3 intraoral scanner was used to scan the right lateral first premolar to the second molar areas of the upper and lower jaws. During scanning for interocclusal registration, participants were instructed to “bite normally,” “bite lightly,” and “bite strongly” to obtain data for the three occlusal patterns. The standard triangulated language (STL) data for each occlusion condition were superimposed using the appropriate software, following which the tooth displacement was calculated. The conventional method was also used to record the occlusal contact area for a silicone model using a dental contact analyzer.

Results: Tooth displacement was significantly lower for the strong-bite condition than for the weak-bite condition (0.018 mm vs. 0.028 mm, P<0.05). As the occlusal force increased, the occlusal contact area also increased, and significant differences were observed among the different occlusal conditions (P<0.05).

Conclusions: Occlusal contact area changed depending on the bite force when using the silicone impression or optical intraoral scanning methods. Moreover, using optical impression methods in “strong bite force” may reduce the deviation and allow for stable interocclusal registration.

Purpose: In this study, the fatigue properties of additively manufactured titanium clasps were compared with those of commercially pure titanium (CPTi) and Ti–6Al–4V (Ti64), manufactured using laser powder-bed fusion.

Methods: Fourteen specimens of each material were tested under the cyclic condition at 1 Hz with applied maximum strokes ranging from 0.2 to 0.5 mm, using a small stroke fatigue testing machine. A numerical approach using finite element analysis (FEA) was also developed to predict the fatigue life of the clasps.

Results: The results showed that although no significant differences were observed between the two materials when a stroke larger than 0.35 mm was applied, CPTi had a better fatigue life under a stroke smaller than 0.33 mm. The distributions of the maximum principal stress in the FEA and the fractured position in the experiment were in good agreement.

Conclusions: Using a design of the clasp of the present study, the advantage of the CPTi clasp in its fatigue life under a stroke smaller than 0.33 mm was revealed experimentally. Furthermore, the numerical approach using FEA employing calibrated parameters for the Smith–Watson–Topper method are presented. Under the limitations of the aforementioned clasp design, the establishment of a numerical method enabled us to predict the fatigue life and ensure the quality of the design phase before manufacturing.

Purpose: To compare the trueness and precision of different impression techniques for two-implant-supported fixed dental prostheses between extraoral and intraoral conditions at different locations.

Methods: Six volunteers participated in this study. A resin block with two parallel analogs was fabricated as an implant site simulator (ISS). The ISS was bonded to a molded ethylene vinyl acetate sheet to create a reference model. For each participant, four reference models were prepared based on the locations of the ISSs: maxillary posterior/anterior region (MaxP/MaxA) and mandibular posterior/anterior region (ManP/ManA). Five impressions were taken extraorally using the open-tray (conventional implant impression technique, CIT) and intraoral scanning (digital implant impression technique, DIT) techniques. The reference models were positioned in the participants’ mouths, and impressions were obtained intraorally using the CIT and DIT. The interanalog distance (d) and angulation (θ) were measured to calculate trueness (Δd, Δθ) and precision (d_P, θ_P). Two-way ANOVA and t tests were performed (α=0.05).

Results: For the DIT, under intraoral conditions, the Δd and Δθ in MaxP and Δθ in ManP were significantly higher than those under extraoral conditions. For the CIT, under intraoral conditions, the Δd and Δθ in ManA and ManP and Δθ in MaxP were significantly lower than those under extraoral conditions. No significant differences in the d_P and θ_P of either DIT or CIT were observed between the two conditions.

Conclusions: Intraoral conditions affected the trueness of DIT and CIT in different regions but had no influence on precision.

Purpose: We evaluated the effects of build orientation and bar addition between lingual flanges on the accuracy of mandibular denture bases fabricated using a digital light processing (DLP) device.

Methods: Mandibular denture bases with and without a bar at the lingual flanges were virtually designed and assigned to eight build orientations. Six dentures per condition were fabricated using a DLP device with a methacrylate-based photopolymerizable monomer (Dima Print denture base) (n=96). The fabricated denture surfaces were digitized, and intaglio surfaces were obtained. These digitized surfaces were compared via superimposition using graphical software (Artec studio12 profession) to their original designed files, and root mean square estimates were obtained. The trueness of the entire and intaglio data was statistically analyzed non-parametrically.

Results: The range of trueness of the entire and intaglio denture bases was 0.15–0.31 mm and 0.11–0.38 mm, respectively. The trueness at 135° and 270° for the entire denture base and that at 270° for the intaglio data without the bar were significantly lower than those for the other build orientations. The trueness at 270° was <0.15 mm irrespective of the conditions. The trueness with the bar of all build orientations, except that of 0° for intaglio data, was significantly smaller than or equal to the trueness without the bar of the corresponding build orientations.

Conclusions: Build orientation and bar addition influenced the accuracy of the complete dentures fabricated using DLP. A build orientation of 270° is recommended for fabricating a mandibular complete denture, irrespective of the bar addition.

Purpose: Although digital removable partial dentures have been previously described, there have been no reports on how to fabricate them in one piece. This study proposes a new method for fabricating patient-specific digital removable partial dentures using a custom plate.

Methods: First, a gypsum model was scanned using a laboratory scanner and a removable partial denture was designed using computer-aided design (CAD) software based on standard tessellation language data. The metal clasp was fabricated from Ti-6Al-4V using a 3D printer. For custom plate fabrication, a resin plate frame was designed using computer-aided design (CAD) software and fabricated using a 3D printer. An artificial tooth and metal clasp were fixed on the base surface of the frame, an auto-polymerizing resin was poured into the frame for the denture base, and the artificial tooth and metal clasp were packed to form a custom plate. The plate was cut using a milling machine. Subsequently, the support attached to the denture was removed and polished for complete fabrication of the denture.

Conclusions: Our novel removable partial denture fabrication method is more efficient than the conventional method. The obtained removable partial dentures demonstrated satisfactory accuracy.

Purpose: This report introduces a fully digital workflow for the fabrication of implant superstructures in an esthetic zone using an intraoral scanner (IOS), computer-aided design/computer-aided manufacturing (CAD/CAM) technology, and monolithic multilayer zirconia.

Methods: Digital impressions of scan bodies and occlusal registration were made in the esthetic zone using an IOS. The provisional restoration in the oral cavity was scanned, and the provisional restoration with an optimized surface morphology of the subgingival contour was scanned outside the oral cavity. These morphological data were integrated into the CAD software to generate a digital cast. The morphology of the final superstructure was generated based on morphological data of the provisional restoration. The final superstructure was fabricated from monolithic multilayer zirconia using a CAM machine, sintered, colored with a stain material, and subsequently bonded to a titanium base using resin cement.

Conclusions: The superstructure was successfully fabricated using a model-less, fully digital workflow, and delivered to the patient. No clinical complications were reported. Thus, within the limitations of this report, the novel developed superstructure fabrication techniques can change the clinical and laboratory workflows from analog to digital in the esthetic zone.