Journal of Advanced Prosthodontics最新文献

Purpose: The aim of this study was to compare the marginal and internal adaptation of polymethyl methacrylate interim fixed partial denture (FPD) restorations fabricated by three-dimensional (3D) printing with different layer thicknesses.

Materials and methods: A standard typodont was scanned by a laboratory scanner. The maxillary left first premolar and first molar teeth received an all-ceramic full-coverage crown preparation, and the second premolar was removed to create a pontic space. The prepared teeth were then scanned, and metal dies were fabricated by a milling machine. Restorations were designed and fabricated in 3 groups (n = 12 in inch) with 25, 50 and 100 µm layer thicknesses. The marginal and internal gaps were measured by the replica technique. Data were analyzed by one-way ANOVA (α = 0.05).

Results: The mean gap size (MGS) in the cervical area of premolar restorations was significantly higher in 100 µm than in 50 and 25 µm thicknesses (P < .05). The MGS in the marginal area of premolar restorations was significantly higher in 100 µm thickness than in 50 µm thickness (P < .05), with no statistically significant difference with 25 µm thickness (P > .05). The MGS at the occlusal and cervical areas of the molar restorations was significantly higher in 100 µm thickness than in 50 µm thickness (P < .05), with no statistically significant difference with 25 µm thickness (P > .05).

Conclusion: Different thicknesses of additive layers in 3D printing affected the marginal and internal gaps. The smallest gap size was recorded in 50 µm layer thickness.

Purpose: This study evaluates the fracture strength and failure mode of implant-supported provisional resin composite crowns fabricated over hydroxyapatite-coated sulfonated polyetheretherketone (PEEK) and sandblasted PEEK abutments after thermomechanical loading.

Materials and methods: Thirty customized PEEK provisional abutments were surface-treated by (1) sandblasting with 50 µm aluminum oxide (n = 15) (Sa) and (2) HA coating after sulfonation (n = 15) (HA). These abutments were veneered to create crowns for the mandibular right first permanent molar using bulk-fill resin composites after applying a thin layer of universal adhesive. All specimens were stored in distilled water at 37℃ for 24 hours, underwent thermocycling for 1000 cycles at 5℃ and 55℃ (30 s dwell time and 10 s transfer time), and were subjected to mechanical cyclic loading for 120,000 cycles with 50 N using a chewing simulator at room temperature. Fracture strength was evaluated with a universal testing machine, and failure mode was analyzed using a 3D surface profilometer. The Mann-Whitney U test was used for statistical analysis (α = 0.05).

Results: The HA group exhibited significantly higher fracture strength (1469.71 N ± 200.36 N) than the Sa group (1152.36 N ± 180.89 N). Most failures were adhesive and included irreparable fractures of the crown.

Conclusion: HA coating after sulfonation effectively enhances the fatigue strength of PEEK abutments veneered with resin composites for implant-supported provisional crowns.

Purpose: The location of the edentulous area in the dental arch can influence the design of the bridge prosthesis in the surrounding region and the forces it will encounter. This study assessed the fracture strength of restorations with various geometric designs produced using different additive and subtractive manufacturing methods.

Materials and methods: Co-Cr metal and zirconia fixed partial denture (FPD) frameworks were designed in both linear and curved geometries. The Co-Cr metal frameworks were produced through casting (C) and laser sintering (L), while the zirconia (Z) frameworks were obtained through milling (n = 10). After veneering the frameworks, a four-point bending test was conducted on the specimens to assess their fracture strength. All obtained values were statistically analyzed (P < .05).

Results: In both linear and curved groups, Z group showed the lowest fracture resistance values followed by C and L groups and the differences between the groups were found statistically significant (P < .05). In L group, curved FPDs showed statistically significantly higher fracture resistance values than linear FPDs (P < .05). In both Z and C groups, curved FPDs showed statistically significantly lower fracture resistance values than linear FPDs (P < .05).

Conclusion: The geometric configuration of the restoration and manufacturing technique affects the fracture resistance of different framework materials in FPDs.

Purpose: This study aimed to analyze the relationship between self-perceived dental esthetics and the selected esthetic mathematical proportions.

Materials and methods: Descriptive cross-sectional study was conducted among 48 dental students who fit into the inclusion criteria. The subjects rated their self-perceived dental esthetics based on the given Likert scale. Standardized portrait photographs of each subject were taken and the mesiodistal measurements of the maxillary anterior teeth were measured using a graphic editing software. The golden proportion, golden percentage and RED proportion in maxillary anterior teeth were then calculated.

Results: Most subjects were pleased with the size, form, and color of their maxillary anterior teeth. Only 2.1% of the maxillary canines and 10.4% of the left maxillary lateral incisors complied with the golden proportion. The maxillary lateral incisors demonstrated its occurrence to golden percentage. For the RED proportion, 29.2% of the left maxillary teeth and 16.7% of the contralateral teeth complied with the proportion. Self-perceived dental esthetics and the occurrence these mathematical proportions have no association.

Conclusion: Within the limitations of the study, it can be concluded that most subjects were satisfied with their self-perceived dental esthetics. Only a small percentage of the subjects having their natural dentition coincide with the golden proportion, golden percentage and RED proportion with a higher percentage occurring on the RED proportion. Hence, the mathematical proportions do not represent the naturally occurring dentition. These mathematical proportions can serve as a guide and the perceived teeth width can be customized accordingly.

Purpose: Digitalization in dentistry has increased interest in the use of intraoral scanners (IOs) in clinical practice. However, knowledge of implant digitalization is primarily limited to in vitro studies. This study aimed to compare implant-supported fixed dental prostheses (FDP) fabricated following complete digital workflow using various implant scan bodies (SB) in treatment of short-span partial edentulism.

Materials and methods: Patients with 25 short-span posterior edentulous sites, each receiving two implants to support a fixed restoration, were included. Digital implant records were made consecutively with original, non-original, and generic SBs using IOs. A practitioner implemented a two-stage full-arch scanning protocol, beginning with continuous arch scanning, followed by individual scanning of SBs. For clinical evaluation, each site received screw-retained full-contour restorations to qualify the connection fit to the implants and contacts to the adjacent and antagonist teeth. For analytical comparison, implant axes calculated from SB scans were quantified using reverse engineering software to compare the differences three-dimensionally. Restorative outcomes and implant axes records were statistically analyzed using the chi-square test and generalized estimating equations, respectively.

Results: Clinical delivery conditions did not differ significantly among the three intraoral SBs (P > .05). The analytical implant-position calculations for non-original and generic SBs did not present significant differences compared to original SBs (P > .05).

Conclusion: SBs with different hardware and software characteristics for an implant system are clinically acceptable for fabricating screw-retained short-span implant-supported FDPs using a complete digital workflow.

Purpose: The purpose of this study was to compare the surface characteristics and healing patterns after implantation of implants treated with SLA and those treated with both SLA and femtosecond laser.

Materials and methods: A total of 10 male New Zealand white rabbits were used to compare recovery levels between implants treated with SLA (SLA group) and those treated with both SLA and femtosecond laser (SF group). The implants' surface characteristics were determined through topographic evaluation, element analysis, surface roughness, and wettability evaluation. In total, 4 implants were placed in each rabbit (2 in each tibia), with 20 implants per treatment group. Using the implant stability quotient (ISQ), marginal bone volume, and histological analysis (bone-to-implant contact (BIC), bone volume/tissue volume (BV/TV)), and post implantation outcomes were assessed. Outcome data were analyzed using independent t-tests, Mann-Whitney U tests, Wilcoxon signed-rank tests, and one-way ANOVA (α = 0.05).

Results: No significant differences were noted between SLA and SF groups in terms of ISQ, marginal bone volume, BIC, and BV/TV (P > .05). However, significant differences in ISQ were observed within each group over time (P < .05). Furthermore, significant differences were noted in the marginal bone volume of the SF group (P < .05) and the BV/TV of the SLA group between weeks 4 and 6 (P < .05).

Conclusion: Surface treatment via SLA and femtosecond laser is feasible compared with SLA treatment alone in terms of ISQ, marginal bone volume, BIC, and BV/TV. However, further clinical research is warranted.

Purpose: The aim of this study was to evaluate the clinical performance and survival rate of implant-supported zirconia-lithium disilicate (Zr-LiSi) bilayered ceramic prostheses over 3 years.

Materials and methods: This study included 71 patients, including 34 with implant-supported metal-ceramic prostheses (control group) and 37 with implant-supported Zr-LiSi bilayered ceramic prostheses (test group). The implant survival rate and incidence of prosthetic and biological complications (veneer fractures, dislodgement of screw-access hole filling material, screw loosening, peri-implant mucositis and peri-implantitis, and marginal bone loss) were investigated. The survival rate was analyzed using Kaplan-Meier survival curves, and the identity between two groups was confirmed by the log-rank test.

Results: Both groups showed a 100% survival rate, whereas the prosthetic survival rates were 77% and 73% for the metal-ceramic and Zr-LiSi groups, respectively. Biological complications did not appear in the metal-ceramic group, and 16.2% of peri-implant mucositis occurred in the Zr-LiSi group, which was significant (P < .05). Prosthetic complications occurred in 5.8% of the metal-ceramic group with veneer fractures and did not occur in the Zr-LiSi bilayered ceramic group.

Conclusion: This study revealed that posterior Zr-LiSi bilayered ceramic implant prostheses showed high survival rates and similar survival rates to metal-ceramic implant prostheses; however, additional consideration should be given to avoid overcontouring. Zr-LiSi bilayered ceramic implant prostheses may be an option for posterior implant-supported prosthetic treatment.

Purpose: This study examines the potential of computer-aided design (CAD) systems equipped with artificial intelligence (AI) in reducing the workload of dental technicians. We aimed to compare the accuracy and design time of crowns designed using conventional CAD with those designed using AI-equipped CAD.

Materials and methods: Abutment tooth models of a maxillary right second premolar (FDI classification #15) and a maxillary left first molar (FDI classification #26) were mounted on a dental model to form the master model. Stereolithography data were acquired using an intraoral scanner, and five dental technicians designed one crown each for #15 and #26 using both conventional and AI-equipped CAD systems. With the #15 and #26 crowns, six measuring points were established for comparing the accuracy of the occlusal surfaces and design time of the crowns designed by the two CAD systems. The occlusal surfaces were also compared for the buccal and palatal sides.

Results: The accuracy of the occlusal surface was 275.5 ± 116.8 µm and 25.7 ± 13 µm for the conventional CAD and AI-equipped CAD systems, respectively. For the buccal and palatal surface comparisons, the conventional CAD system revealed larger misfits on the palatal side for both #15 and #26, with significant differences observed. No significant differences were noted with the AI-equipped CAD system. The AI-equipped CAD resulted in significantly faster design time for both #15 and #26.

Conclusion: The AI-based CAD system significantly reduced design time and enabled the fabrication of uniform crowns regardless of the dental technician's experience and skill.

Purpose: The purpose of this clinical study was to evaluate the extent of intraoral occlusal adjustment required for zirconia crowns designed with a dynamic jaw motion tracking method compared to a conventional approach.

Materials and methods: Fifteen patients needing zirconia crown restorations in the anterior or posterior regions participated in this study. Following tooth preparation, dynamic jaw motion tracking records were gathered using a tracking device. These records were imported into computer-aided design software and aligned with scanned upper and lower jaw data to design each crown's occlusal surface. Two crowns were fabricated for each patient: one using motion tracking data and another without it. Crowns were scanned pre- and post-adjustment following standard protocols. The scanned data were analyzed with 3D inspection software to calculate occlusal adjustments in the segmented occlusal area as root mean square values, with a paired t-test used for statistical analysis (α = 0.05).

Results: Crowns designed with motion tracking data required significantly less intraoral occlusal adjustment than those designed conventionally (P = .028).

Conclusion: Dynamic jaw motion tracking in crown design reduces the extent of intraoral occlusal adjustment, potentially enhancing clinical efficiency.

Purpose: Three-dimensional (3D) printing must go through a post-processing procedure. This study aimed to evaluate the effects of different cleaning methods on 3D printed three-unit fixed partial dentures using 3D analysis.

Materials and methods: A three-unit fixed partial denture was designed and printed using two different printers. The evaluation was taken regarding cleaning method with ethanol (ETH) or isopropanol (IPA), and combining ultrasonic (US) technique for the following groups: group 1, ETH; group 2, ETH+US; group 3, IPA; group 4, IPA+US; and group 5, US. The 3D evaluation was conducted by calculating the mean distance between two specific points and analyzing various angular deviations, utilizing the geometry-embedded library. In addition, visual analysis was performed by creating sectional planes in different points of view. Normality test and independent t-test were performed to compare results between the two printers used in this study. In addition, one-way ANOVA was performed to compare cleaning method groups.

Results: Mean distance results showed statistical differences between printers for groups IPA, US, and IPA+US, whereas no significant differences were found among cleaning methods. Angular measurements were taken at the bucco-lingual, proximal, and occlusal planes to assess deviations in the internal surfaces. Overall results showed a tendency of shrinkage of the printed three-unit fixed partial denture.

Conclusion: Ultrasonic treatment may impact the washing efficiency when used with other cleaning solutions regarding angular and longitudinal deformation. Adequate selection of post-processing methods is crucial to decrease morphological deformities in 3D printed materials.