The International journal of prosthodontics最新文献

Purpose: To evaluate the marginal and internal fit of anterior monolithic zirconia crowns fabricated over preparations with different TOC angles with and without a rounded incisal design.

Materials and methods: Crown preparations of fourteen maxillary central incisors were digitally designed and fabricated using photosensitive resin. The axial wall inclinations were -8°, -4°, 0°, 8°, 12°, 16°, 22° with and without rounded incisal corners and a 1-mm-wide chamfer-type finish line. Monolithic zirconia crowns (n=10) were milled and assessed for fit using the dual-scan technique using an intraoral scanner. The STL files were analyzed in Geomagic Control X, measuring fit at 100, 150, and 175 points on the incisal, axial and marginal areas, respectively. Data normality was tested (Shapiro-Wilk), and TOC angle groups were compared using One-way ANOVA, Levene's test, Tukey HSD, and Independent Samples T-tests (p<0.05).

Results: TOC angle groups showed statistically significantly differences (p<0.001). The 22° preparation had the lowest marginal discrepancies (36±5 μm rounded, 61±5 μm non-rounded), while -8° had the highest (117±9 μm rounded, 147±30 μm non-rounded). Axial discrepancies were lowest at 22° (77±14 μm) and highest at -8° (208±52 μm) in non-rounded samples (p<0.001). The smallest incisal discrepancy was found in 22° (95 ± 13 μm); while the largest (163 ± 31μm) was at -4° in the non-rounded groups (p<0.001).

Conclusions: TOC angle and rounded preparations have a significant impact on the fit of CAD/CAM milled monolithic zirconia crowns. Rounded incisal corners and preparations with higher TOC angles increased marginal and internal adaptation of the crowns.

Purpose: To investigate the effect of titanium surface treatment and heat-cured acrylic resin (AR) thickness on color differences (ΔE00) in AR.

Materials and methods: Thirty AR specimens were divided into three groups: 1.0, 2.0, and 3.0 mm (n = 10 each). Each AR thickness group underwent testing over six titanium surface treatments (n = 10): untreated titanium (T), gleaming titanium (PT), 50 V anodization (G), polished gold-anodized (PG), 70 V anodization (P), and polished pink-anodized titanium (PP). All specimens from the 18 experimental groups were examined using a spectrophotometer and compared with the control group (10.0 mm AR, n = 5) to establish the color difference (ΔE00). ΔE00 < 4.08 was considered 50% clinically acceptable (50%AT), whereas ΔE00 < 1.72 denoted 50% clinically perceptibility (50%PT). The data collected were statistically analyzed using analysis of variance and post-hoc tests (P =.05).

Results: The AR thickness and type of titanium surface treatment significantly affected the observed ΔE00 (P <.05). When using a 1.0-mm AR over P- and PP-treated titanium, the mean ΔE00 was below 50%AT. When using a 2.0-mm AR over the P and PP, the 95% CIs of ΔE00 were < 50%PT.

Conclusions: The use of a 1.0-mm AR over pink-anodized titanium potentially results in acceptable color matching with 95% CIs.

Purpose: This study evaluated the marginal and internal adaptation, fabrication trueness, and retention of endocrowns made from additively manufactured (AM) glass-filler-reinforced resin composite and zirconia, and subtractively manufactured (SM) advanced lithium disilicate (ALD).

Materials and methods: A resin typodont model was scanned to design endocrowns. Sixty restorations (n=20/group) were fabricated using AM composite (Group C), AM zirconia (Group ZrO2), or SM lithium disilicate (Group ALD). All restorations were scanned with the same intraoral scanner; adaptation (marginal and internal gaps) was quantified with cross-sectional measurements, and trueness was analyzed as RMS deviations. Endocrowns were cemented on resin dies, thermomechanically aged, and tested for pull-out forces. One-way ANOVA (α = .05) was used for statistical analysis.

Results: ALD showed the lowest marginal (30.81 ±2.45 μm) and internal (33.41 ±2.62 μm) discrepancies, followed by ZrO2 (40.45 ±2.80 μm; 46.23 ±2.20 μm), and C (63.92 ±4.30 μm; 60.34 ±3.30 μm). Significant differences were observed between C and ALD (p=.003; p=.009) and between C and ZrO2 (p=.007; p=.012), but not between ALD and ZrO2 (p=.386; p=.115). Trueness was highest in ALD (38.72 ±3.91 μm), followed by ZrO2 (43.55 ±4.16 μm) and C (51.08 ±4.84 μm), with significant differences between ALD and C (p<.001) and ZrO2 and C (p=.004). ZrO2 showed the highest retention (754 ±211 N), significantly greater than ALD (709 ±208 N; p=.014) and C (634 ± 363 N; p=.002).

Conclusions: ALD and ZrO2 endocrowns showed superior adaptation and trueness compared to AM composite. ZrO2 exhibited the highest retention. Within the study's limitations, AM-zirconia appears to be a viable alternative to SM lithium disilicate for endocrown fabrication.

Objective: To compare the effectiveness of four intermaxillary relation recording methods for guiding the virtual adjustment of all-ceramic restorations.

Materials and methods: Twelve participants underwent buccal intermaxillary relation recording using traditional methods (Control group), 3Shape TRIOS3 dynamic scans (SD group), Zebris mandibular motion trajectories (ZT group), and Zebris articulator parameters (ZP group). Virtual adjustments were performed for four restoration types: single anterior/posterior crowns, two posterior crowns, and three-unit fixed bridge. Three-dimensional (3D) occlusal surface deviations between the natural teeth and restorations were measured.

Results: All three digital intermaxillary relation recording methods met clinical requirements. The Zebris trajectory group demonstrated significantly smaller 3D deviations compared with the 3Shape dynamic scan group (P<0.05), exhibiting superior performance in eliminating occlusal interferences of restorations. Notably, the Zebris trajectory group showed significantly reduced 3D deviations only in the single anterior tooth subgroup compared with the Zebris articulator parameter group (P<0.05), indicating better efficacy in removing restorative occlusal interferences.

Conclusions: The three digital techniques matched or exceeded traditional methods in eliminating occlusal interferences, with the Zebris mandibular motion trajectory recording technique demonstrating superiority over the 3Shape dynamic recording method.

Clinical significance: Application of the mandibular motion trajectory recorded by the Zebris mandibular motion analysis system to guide restorative fictive adjustment outperformed the utilization of 3Shape dynamic occlusion.

The study was aimed to retrospectively evaluate differences in marginal bone loss (MBL) between bone level (BL) implants, with (LMS) and without (noLMS) laser-microtextured collar surface, restored with screwed single crowns with different emergence profiles (EP) and emergence angles (EA). Materials and methods: A retrospective evaluation of records and radiographs of 90 patients scheduled for single implant therapy at the molar region over a period of up to 10 years after prosthetic restoration was performed. The radiographic MBL and clinical parameters were measured over time and statistically analyzed. Results: LMS implants presented a statistically significant higher cumulative success rate (97.7 % vs. 91.1%. p<.05) and lower mean MBL compared to noLMS (0.8mm vs. 1.7 mm, p<.05). Around noLMS BL implants an EA.

This dental technique presents a fully digital protocol for designing, fabricating, and assembling a mandibular denture with a resilient liner using readily available CAD/CAM software and 3D printing technologies. The digital method allowed denture teeth, denture base, and resilient liner as components to be designed and exported as separate files for additive manufacturing. It involves importing a cast into CAD software to create a T-shaped key, designing a 2 mm resilient liner with six positioning points, generating a mandibular denture base and alignment jig, 3D printing all components, post-processing, assembling with photopolymer, and final trimming and polishing. The additional cast and alignment jig design demonstrated ensured ease of component assembly and stable occlusion. The development of this novel technique using additive manufacturing advances the applications of the digital workflow in removable prosthodontics. The method is proposed as a potential solution to the problems associated with the traditional relining process, with a particular emphasis on its compatibility with additive manufacturing processes that utilise diverse methacrylate formulations, in contrast to conventional polymethylmethacrylates.

Purpose: To investigate the influence of the printing angle on the physicomechanical properties of PMMA.

Materials and methods: This systematic review included the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA 2020) and was registered with the Open Science Framework. Electronic searches were carried out in the PubMed/MEDLINE, SciELO, Scopus, Embase, and Science Direct databases. Risk of bias was analyzed using the Joanna Briggs Institute (JBI) instrument for quasiexperimental studies.

Results: Of the 1,917 studies identified, 25 were included and qualitatively assessed after the selection stages. Printing dental devices for prosthetic use in PMMA-based resins provides satisfactory performance, with better resistance to bending and fracture at 0 degrees. After polishing, the differences observed in surface roughness concerning the printing angle became insignificant. The different printing angles can influence the optical properties significantly, but other factors such as the composition of the resin can also influence these results.

Conclusions: Printing dental devices in PMMA-based resins provides satisfactory performance for prosthetic use. In general, better mechanical performance was attributed to a printing angle of 0 degrees compared to 45 and 90 degrees. Varying the printing angle can be a strategy for individualizing prosthetic devices according to the physical and mechanical needs presented by each type of clinical application.

Purpose: To evaluate resin-based posterior restorative materials by comparing the release of BPA, TEGDMA, HEMA, UDMA, and Bis-GMA monomers at 1 hour, 3 days, and 1 month.

Materials and methods: Five different materials were used in this study: Cerasmart (CS), Gradia-Plus Indirect (GI), G-ænial Posterior (GP), Formlabs 3D-Permanent Crown (FPC), and SonicFill 3 (SF). A total of 90 specimens 8 × 8 × 2 mm3 in size were prepared from all the materials. The specimens were immersed in a 75% ethanol/25% water solution and placed in an incubator for 1 hour, 3 days, and 1 month, after which the solutions were analyzed using high-performance liquid chromatography (HPLC). For the comparisons of data with normal distribution among the five different materials, repeated-measures ANOVA followed by Bonferroni post-hoc tests were applied (α = .05).

Results: Except for BPA release in the FPC material, all other materials exhibited an increasing release of monomers over time (P < .001). At all the measured time points, the material with the lowest monomer release was CS, while the highest release was observed in GP. The GI material exhibited the statistically significant highest release of BPA, TEGDMA, and Bis-GMA (P < .001), while the highest UDMA and HEMA release was observed in the GP material (P < .001).

Conclusions: The highest monomer release was observed for UDMA (0.8%) from the GP material at the end of 1 month. However, the monomer release from all examined materials remained well below the clinically acceptable range (1.5% to 5%).

Purpose: To evaluate the accuracy of impression methods using an intraoral scanner and the conventional method based on the implant number and angulation with multiple implants.

Materials and methods: Six implants were placed in the maxillary edentulous typodont using 3D-modeling software. Eight implants were placed in another maxillary edentulous typodont. The implant placement angulation for each model was different. 3D designing and printing were performed to produce reference models. These models were scanned to obtain reference scan data (RSD). In the conventional impression method, reference models were used, and a gypsum model was produced. Scan data was obtained by the lab scanner (Group CI). Models were scanned, and the scan data was obtained (Group IS). The distance and angulation deviation were compared.

Results: In models with six implants, the mean values of all distance and angulation deviations were less in Group CI than in Group IS (P < .05), except for the distance deviation in Model 6-20. In models with eight implants, the mean values of distance and angulation deviations were less in Group CI than in Group IS, except for the distance deviation in Model 8-20, and significant differences were observed between the two groups for Models 8-0, 8-10, and 8-20 (P < .05).

Conclusions: In cases where multiple implants are placed in the completely edentulous arch in vitro, conventional impressions are more accurate than intraoral scans. In cases lacking implant parallelism, intraoral scans can be used as a replacement for conventional impressions.

Purpose: To compare the precision and accuracy of traditional alginate impressions and digital optical impressions taken by second-year dental students using reverse-engineering technology. The null hypothesis posited no significant difference in the accuracy between the two methods when performed by inexperienced operators.

Materials and methods: In total, 20 dental students performed 128 impressions: 64 traditional alginate impressions (Group A) and 64 digital impressions using an intraoral scanner (Group B). The impressions were analyzed and compared to reference models created by an expert operator. Data were captured using a reverse-engineering software (Geomagic Control X), and precision was evaluated through 3D and point-by-point analyses. Statistical analyses, including paired t tests and Wilcoxon signed-rank test, were conducted to compare the deviations from the reference model.

Results: The digital impressions demonstrated superior accuracy compared to traditional alginate impressions, with significantly smaller deviations from the reference model. Digital impressions consistently exhibited higher precision and trueness, so the null hypothesis was rejected. Statistical significance was found at key points, with P < .05 for all comparisons.

Conclusions: This study demonstrates that digital impressions provide significantly greater accuracy and precision than traditional alginate impressions, with lower deviations and higher reproducibility. The findings highlight the dimensional instability of alginate impressions and reinforce the advantages of digital intraoral scanning for standardization and consistency in clinical practice. Intraoral scanners provide more precise and accurate impressions than traditional methods, even when used by inexperienced operators. This study supports the integration of digital impression techniques into dental education to enhance student proficiency and improve clinical outcomes.