Journal of Prosthodontics-Implant Esthetic and Reconstructive Dentistry最新文献

Purpose: To compare mechanical, optical, and physical properties of denture base materials fabricated with various 3D printing systems to reference milled and conventionally heat-processed denture base materials.

Materials and methods: Specimens of denture base materials were either 3D-printed (DLP in-office printer, CLIP laboratory printer, or material jetting laboratory printer), milled, or heat processed. 3-point bend flexural strength testing was performed after 50 hours of water storage following 1hour of drying (dry testing) or in 37°C water (wet testing). Fracture toughness was performed with a notched beam specimen after 7 days of water storage and tested dry. The translucency parameter was measured with 2 mm thick specimens. Stain resistance was measured as color change following 14 days of storage in 37°C coffee. Water sorption was measured following 7 days of storage in 37°C distilled water.

Results: For dry testing, all but one of the 3D-printed materials attained higher or equivalent flexural strength as the reference materials. For wet testing, all 3D-printed materials attained higher or equivalent strength as the reference materials and dry-tested materials. For 3D-printed materials, wet testing increased displacement before fracture whereas it decreased displacement for the reference materials. Only two of the 3D-printed materials had similar fracture toughness as the reference materials. One of the 3D-printed materials was more translucent and one was more opaque than the reference materials. Only one of the 3D-printed materials absorbed more water than the reference materials.

Conclusion: 3D-printed denture base materials have mostly equivalent mechanical, optical, and physical properties to conventional and milled denture base materials.

A novel technique was devised to create a stabilizing guide to accurately maintain the position of CAD-CAM-milled artificial teeth in their denture base socket during the bonding process. This ensures that the artificial teeth and denture base are adequately bonded to reproduce the designed occlusion and reduce chair-side adjustment.

Purpose: To study the effect of different vertical angulations on the ability to radiographically assess vertical marginal discrepancies of lithium disilicate crowns.

Materials and methods: Twenty-one lithium disilicate crowns were fabricated for three different prepared natural teeth: incisor, canine, and premolar. Vertical marginal discrepancies ranging from 0 to 300 µm were intentionally created. The seated crowns were radiographed using seven different vertical angulations, totaling 147 images. Thirty experienced evaluators scored each image for marginal discrepancy, and values were statistically analyzed.

Results: Significant differences in the ability to accurately assess marginal discrepancies from radiographs were observed for the study factors of angulation, tooth type, and degree of marginal discrepancy (p < 0.001).

Conclusions: The radiographic interpretation of the marginal discrepancies of lithium disilicate crowns is significantly affected by the dimension of the marginal discrepancy. Specifically on premolar crowns, it is significantly affected by different vertical angulations of the X-ray beam. When evaluating marginal discrepancy on lithium disilicate crowns radiographically, vertical beam angulation within ±10° to the cemento-enamel junctionCEJ plane is recommended.

Purpose: To evaluate, through in vitro studies, the bond strength of vitreous and hybrid ceramics with self-etching surface treatment compared to conventional treatment.

Methods: This systematic review followed the preferred reporting items for systematic reviews and meta-analyses (PRISMA) and was registered on the open science framework (OSF) platform for in vitro studies. A population, intervention, control, and outcome (PICO) question was formulated: "Does the surface conditioning of glass and hybrid ceramics with self-etching silane present a bond strength similar to that of conventional bonding?". A literature search was carried out in the PubMed, Embase, Web of Science, Cochrane Library, and ProQuest databases until September 2023. The Joanna Briggs Institute (JBI) critical appraisal guidelines for quasi-experimental studies were used for risk assessment of bias. The meta-analysis was based on the inverse variance (IV) method (p < 0.05).

Results: A total of 29 in vitro studies published between 2017 and 2022 were included in this systematic review, totaling 1889 ceramic samples. The meta-analysis indicated a significant decrease in the bond strength of HF 4%-5% with silane compared to self-etching (p < 0.05; MD: 0.34; 95% CI: 0.13-0.35; I² = 3%, p = 0.42), while it indicated that there was no significant difference between self-etching compared to 9%-10% HF with silane (p = 0.92; MD: 0.02; 95% CI: -0.32 to 0.36; I² = 14%, p = 0.32).

Conclusion: Self-etching primer presents bond strength that is superior to or similar to conventional surface treatment on glass and hybrid ceramics.

Purpose: To investigate the effects of different surface treatments and thermal cycling on the shear bond strength between 3D-printed teeth and denture bases.

Material and methods: For the shear bond strength (SBS) test, the specimens were the maxillary central incisors (11 × 9 × 7 mm) bonded on a cylindrical base (20 × 25 mm). The control group was heat-cured polymethylmethacrylate (PMMA) (N = 20). The printed group was divided into five subgroups (N = 20): no treatment, sandblasting with aluminum oxide (Al₂O₃), methyl methacrylate monomer, acetone, and adhesive with urethane dimethacrylate. Half of the samples were subjected to 2000 thermal cycling cycles, and all samples were subjected to the SBS test. The failure mode was established as adhesive, cohesive, or mixed through stereomicroscopic analysis. The surface roughness test (Sa) was performed using optical profilometry, and the rectangular specimens (14 × 14 × 2.5 mm) were divided into four groups according to the surface treatments (N = 7 per group). Paired T and Wilcoxon tests were conducted to perform comparisons within the same group. The Kruskal-Wallis and Dwass-Steel-Critchlow-Fligner post-hoc tests were conducted to compare the groups.

Results: Al₂O₃ sandblasting in the 3D-printed groups achieved high SBS values comparable to those of the control group in the thermal cycled (p = 0.962) and non-thermal cycled samples (p = 0.319). It was the only treatment capable of modifying the surface of the 3D-printed resin, thereby increasing the roughness (p = 0.016).

Conclusions: Sandblasting is recommended to increase the bond strength between the tooth and denture bases.

Purpose: The purpose of this study was to compare the effects of finishing and polishing techniques on the fit accuracy, metal loss, and surface roughness of conventional versus CAD-CAM removable partial denture (RPD) frameworks.

Materials and methods: A 3D-printed maxillary Kennedy class III modification I model served as the master cast. Forty impressions (20 conventional and 20 digital) were divided into four groups: lost-wax technique (Group I: LWT), CAD-printed (Group II: CAD-RP), CAD-printed from a stone cast (Group III: CAD-RPS), and lost-wax technique from resin-printed models (Group IV: LWTR). Various finishing and polishing techniques were applied, followed by digital scanning for fit accuracy assessment using surface matching software. Metal thickness loss and surface roughness were evaluated pre- and post-finishing and polishing. The Kruskal-Wallis test followed by the Scheffe post-hoc test were conducted to evaluate the fit accuracy between groups (α = 0.05).

Results: Color mapping revealed significant differences (p < 0.001) between conventionally casted RPD frameworks and 3D-printed groups post-finishing and polishing. The most significant gap was observed with the guide plates from printed RPD frameworks. The D-Lyte technique resulted in less metal loss compared to the conventional finishing and polishing technique (p < 0.001).

Conclusion: Within the limitations of this study, conventionally processed RPD groups exhibited better overall fit accuracy post-finishing and polishing. Both conventional cast and 3D-printed RPD frameworks showed clinically acceptable fit accuracy. The D-Lyte technique presented less metal loss and smoother surfaces compared to other groups, suggesting it as a viable alternative.

Purpose: The purpose of this study was to assess the effect of Ga-Al-Ar diode, Nd:YAG lasers, and chemical disinfectants (NaOCl, vinegar, and Corega) on surface roughness (Ra) and hardness (VHN) of polymethylmethacrylate (PMMA), thermoplastic polyamide, milled and 3D-printed denture base resins.

Materials and methods: About 432 specimens of PMMA, thermoplastic polyamide, milled, and 3D-printed resins were divided into six subgroups (n = 18): distilled water (control:C), Ga-Al-Ar diode laser (L1), Nd:YAG laser (L2), 1% sodium hypochlorite (NaOCl), vinegar (AA), and Corega (CR). Each specimen's Ra and VHN were measured. Surface topography assessment was done using scanning electron microscopy (SEM). Analysis was done using ANOVA and post hoc Tukey's test (p = 0.05).

Results: A significant difference was noted in Ra and VHN as affected by denture base materials, surface disinfectants, and their interaction (p < 0.001). Results showed a significant increase in Ra of PMMA with NaOCL (p < 0.001), AA (p = 0.005), and CR (p = 0.009), thermoplastic polyamide with L1 (p = 0.012), L2 (p = 0.015), NaOCL AA, and CR (p < 0.001 each), milled resin with AA NaOCL, and CR (p < 0.001 each), and 3D-printed resin with L1, NaOCl, AA (p < 0.001 each), and CR (p = 0.008). The VHN increased in PMMA with NaOCL (p < 0.001), AA (p = 0.044), and CR (p < 0.001), thermoplastic polyamide with L1 (p = 0.037), milled resin with L1, L2, and CR (p < 0.001 each), and 3D-printed resin with L1, NaOCl (p < 0.001 each), and decreased with CR (p = 0.007).

Conclusion: The tested properties showed variations affected by denture base material and surface disinfectants. Laser treatments induced smoother surfaces than chemical disinfectants. Laser improved the surface hardness of CAD-CAM resins, while chemical immersion improved that of PMMA.

Purpose: This study aimed to comparatively analyze full-arch mandibular reconstruction using dental implants. It focused on two distinct prosthesis configurations: completely splinted and segmentally splinted. These configurations were evaluated under two different occlusal schemes-group function and canine guidance-utilizing finite element analysis (FEA).

Materials and methods: The methodology involved developing three-dimensional finite element models from computed tomography data acquired from an edentulous patient. Six dental implants were utilized to complete the mandibular reconstruction. Prosthetic reconstruction was conducted with completely and segmentally splinted prostheses, each employing group function and canine guidance occlusal schemes. Consequently, four distinct models were analyzed. Following meshing, a 200 N load was applied at a 30-degree angle. Subsequent evaluation encompassed stress, strain distribution, and the overall deformation of the implants, crowns, and underlying bone structure assessment.

Results: The group function occlusal scheme generally exhibited lower stress values than the canine guidance occlusal scheme, with three-piece prostheses demonstrating even lower stress levels than one-piece prostheses. Conversely, the canine guidance occlusal scheme exhibited higher stress values overall.

Conclusion: The findings of this study may assist clinicians in selecting the most effective occlusal scheme and prosthetic configuration for implant-supported mandibular restorations, potentially enhancing treatment outcomes and reducing the risk of mechanical complications. In summary, results indicated that group function loading, irrespective of prosthesis type, offers more uniform load distribution and lower stress values, making it a preferable choice over canine guidance. Within the group function occlusal scheme, three-piece prostheses demonstrated lower stress values than one-piece prostheses, but the clinical significance of this difference appears to be minimal.