The International journal of prosthodontics最新文献

Purpose: To evaluate changes in color and translucency of stained and glazed monolithic lithium disilicates and zirconia after toothbrushing with conventional or whitening dentifrices followed by thermocycling.

Materials and methods: Samples (n = 20/material) from CAD/CAM (IPS e.max CAD [EC]) and pressable (IPS e.max Press [EP]) lithium disilicates and 5Y-PSZ zirconia (Prettau 4 Anterior [PA]) were prepared and received staining and glazing procedures. Aging was performed by toothbrushing with conventional (n = 10) or whitening (n = 10) dentifrices, followed by thermocycling simulating 5, 10, and 15 years. Color coordinates L*, a*, b*, , and C* and h° values were assessed with a spectrophotometer at baseline and after each aging period to calculate color changes (ΔE00), lightness (ΔL*), and translucency parameter (TP). Data were analyzed using three-way repeated measures ANOVA's followed by Sidak post-hoc test (α = .05).

Results: When comparing the dentifrices, EC and EP produced the greatest ΔE00 after 15 years with the whitening dentifrice (P < .05). Regardless of the dentifrice, PA showed greater ΔE00 than EC after 10 years (P < .05). When comparing the aging periods, EC and PA did not show differences in ΔE00 for both dentifrices (P ≥ .05). EC and EP produced an increased ΔL* after 15 years in the whitening group (P < .05). In the whitening groups, the ΔL* values of PA differ (P < .005) from those of lithium disilicates. Regardless of the experimental group, the TP values followed the inequality: PA < EC < EP (P < .05).

Conclusions: Overall, the color of stained and glazed monolithic lithium disilicates and zirconia changed under aging with greater effects for whitening dentifrice. Aging did not influence translucency.

Purpose: To evaluate the clinical survival and impact on oral health-related quality of life (OHRQoL) of immediate loading of implant-supported full-arch CAD/CAM-milled PMMA interim restorations.

Materials and methods: This was a practice-based prospective cohort study performed in a Portuguese dental clinic. Eleven patients received a total of 17 CAD/CAM fully implant-supported, screw-retained, full-arch restorations with milled PMMA and were followed up for 1 year. The primary outcome was prosthesis survival, determined with a modification of the California Dental Association score and a Kaplan-Meier survival function analysis. The secondary outcome was the patient quality of life, as defined by application of the OHIP-14-PT questionnaire and standardized effect size variation between two visits. Significance was set at 5%.

Results: Survival probability at 12 months was 76%, complete fracture of the prosthesis occurred in 17.6% of the cases, and small fractures without lab involvement occurred in 5.9% of cases. There was a significant improvement in OHRQoL between visit 1 and visit 4. The mean difference and effect size for total OHIP-14-PT score were -32.91 ± 3.68 and 3.66 (95% CI -1.83 to -5.80) respectively (P < .001* Wilcoxon matched paired rank test).

Conclusions: Fullarch implant-supported CAD/CAM-milled PMMA interim prosthesis seem to be a viable approach with good survival rate and great impact on patient OHRQoL.

The review focuses on the progressive role of 3D-printing in dentistry, particularly emphasizing the use of zirconia-based and lithium disilicate (LS2) -based ceramic materials. Celebrated for their biocompatibility and esthetic resemblance to natural teeth, these materials have shown promising results with high success rates. Digital light processing (DLP) and stereolithography (SLA) have been noted for producing superior 3D-printed ceramic products. Despite facing challenges such as surface defects, mechanical strength limitations, and esthetic inconsistencies, active research is dedicated to refining the quality and esthetics of 3D-printed zirconia-based and LS2-based ceramics. The review acknowledges the need to mitigate the steep costs of this manufacturing form and recognizes the current shortfall in clinician and technician awareness of these advanced techniques. Addressing these issues through focused research on improving surface quality, dimensional accuracy, and mechanical properties of 3D-printed dental prostheses is crucial, as is enhancing the dental community's understanding and acceptance of this innovative technology.

Purpose: Sintering procedures influence the properties of zirconia. This study evaluated the effect of varying sintering rates on flexural strength (σ) of 3, 4, and 5 mol% yttria (Y) containing monochrome (Mo) and multilayer (Mu) zirconia. Materials and Methods: 270 specimens (width×length×thickness = 11.2×20×1.5 mm) were prepared from Mo and Mu of 3Y, 4Y, and 5Y zirconia and randomly sintered at regular (RS: 10 °C/min), fast (FS: 35 °C/min), and speed (SS: 70 °C/min) sintering (n = 15/group). Three-point bending test was determined for σ. ANOVA and Bonferroni test were analyzed for significant differences of σ (a=0.05). The microstructure and crystalline [monoclinic (m), tetragonal (t), and cubic (c)] phases were evaluated by SEM and XRD.Results: σ of zirconia was affected by zirconia type, shade pattern, and sintering rate. Significant higher σ for 3Y>4Y>5Y (p<0.05). Significant greater σ for Mu>Mo (p<0.05). Significant reduction of σ upon SS than RS and FS (p<0.05). However, no significant effect on σ upon varying sintering rates within each type of zirconia (p>0.05). SEM indicated greater grain size in 5Y than in 4Y and 3Y. XRD indicated higher t phase in 3Y, whereas higher c phase in 5Y. Mo indicated a higher c phase than Mu.Conclusions: σ was influenced by Y content (3Y>4Y>5Y), shade pattern (Mu>Mo), and sintering rate (RS@FS>SS). Nonetheless, no influence of varying sintering rates on σ for each type of zirconia, suggesting sintering zirconia with RS and FS for expecting higher σ and at SS for acceptable σ for chair-side cost-effective restoration.

Purpose: To evaluate the preferences of dental practitioners for tooth-supported crowns dental ceramics by means of an online survey and to assess the influence of age, gender, years of experience, and dental specialty on those preferences. Materials and Methods: An anonymous questionnaire was delivered online through Google Surveys, targeting 796 dentists. It contained 17 dichotomous, closed questions with two sections. The first section dealt with general characteristics, including age, gender, years of experience, training in prosthodontics, and hours worked per week. The second section included questions regarding preferences of different materials for crowns, and the use of digital workflows. Analyses were carried out with Stata 14.0 software (StataCorp, TX, USA). A significance level of p=0.05 was adopted. Results: 248 surveys were answered. Practitioners in Chile preferred lithium disilicate for the anterior region (55.2%) but also for the posterior area (40.7%), regardless of their age, gender, years since graduation, hours worked per week or any training in prosthodontics. Chilean dentists over 50 years old considered zirconia almost 4 times more than those under 30 years old for anterior crowns (51.85%). 59.68% of dentists take digital impressions, and 37.10% have access to chairside CAD/CAM technology. In this group, 54.4% preferred feldspathic ceramic for anterior and 23.9% for posterior crowns. Conclusions: While there is a wide range of dental ceramic materials, these results provide a snapshot of the current trends in Chile where lithium disilicate is the most preferred ceramic material for tooth-supported crowns, and metal-ceramic is the least preferred material.

Purpose: To evaluate the elution of residual monomers from resins used in additive and subtractive manufactured permanent restorations over a period of one month, using highperformance liquid chromatography (HPLC). Materials and Methods: Two additive manufacturing permanent crown resins (Crowntec, CT and VarseoSmile Crown Plus, VS) and a subtractive manufacturing resin nanoceramic (Cerasmart, CS) were used to fabricate 30 disc-shaped samples (10 × 2 mm) (n=10). The elution of bisphenol A ethoxylate dimethacrylate (BisEMA), urethane dimethacrylate (UDMA), and triethylene glycol dimethacrylate (TEGDMA) monomers was measured with HPLC at 1 day and 30 days after immersion. One-way analysis of variance (ANOVA) and post-hoc Tukey tests were used to evaluate differences in eluted monomer concentrations. Paired-sample t tests were used to test the differences in monomer concentration between storage times. Results: CS released BisEMA and UDMA residual monomers, while VS and CT released BisEMA and TEGDMA residual monomers. The residual monomer elution from CT was consistently lower than that from VS for both BisEMA (p <0.001) and TEGDMA (p <0.001). CS showed a decreasing release pattern in BisEMA (p =0.002) and UDMA (p <0.001) residuel monomers, whereas VS and CT showed an increasing release pattern in BisEMA (p <0.001) and TEGDMA (p <0.001) residuel monomers. Conclusions: The additive manufactured composite resins released higher amounts of residual monomers than the subtractive manufactured resin nanoceramic. Although the amounts of residual monomers released in the additive manufactured composite resins increased over time in contrast to subtractive manufactured resin nanoceramic, these values were below cytotoxic levels.

Purpose: To investigate the available evidence on the accuracy of conventional and digital workflows for complete arch implant supported frameworks. Materials and methods: This scoping review was conducted according to the 5-stage framework of Arksey and O'Malley. A systematic literature search was performed adhering to the PRISMA guidelines to identify studies with a direct comparison of conventional and digital methods for the fabrication of complete arch implant supported frameworks. 58 in-vitro studies with the focus on edentulous arches with at least four implants published between 2000 and 2024 were included. The reported outcomes were examined to determine the value of a statistical analysis for adding up the individual errors to a cumulative error of the workflow. Results: Evidence on the accuracy assessment of digital and conventional workflows for complete arch implant supported frameworks is available. However, also studies with the same assessment methods and outcome units appear to be too heterogeneous to perform a statistical analysis of error accumulation. While there is no consensus in the impression and cast fabrication stage, digital techniques show a superior accuracy for the fabrication of complete arch implant supported frameworks compared to conventional casting. Conclusion: In-vitro studies assessing the accuracy of entire workflows and classifying their outcomes regarding the clinical relevance are lacking.

Purpose: The improvement of computer-aided design and computer-aided manufacturing (CAD/CAM) has changed the methods of fabricating laminate veneers. The objectives of this study were to evaluate the marginal and internal fit of ceramic veneers manufactured with different CAD/CAM techniques. Materials and methods: A metal die was made by copying a prepared plastic maxillary central right incisor and scanned for designing a laminate veneer. One hundred laminate veneers were made with four different CAD/CAM techniques (n=25), including milled lithium disilicate (MLD), heat-pressed lithium disilicate with 3-dimensional (3D) printed wax patterns (PLD), milled zirconia (MZ), and 3Dprinted zirconia (PZ). The virtual marginal and internal fit of fabricated veneers was evaluated with digital crown fitting software. The actual marginal and internal fit was measured with the silicone replica method under a digital microscope. The measured data were analyzed using the one-way analysis of variance and the Turkey test. Results: There were significant differences in marginal and internal fit (P < 0.001) among manufacturing techniques. Both the virtual and actual marginal and internal gaps were higher in the PLD and PZ groups compared to the MLD and MZ groups. Conclusion: All four CAD/CAM techniques of manufacturing veneers, that is, milled lithium disilicate, heat-pressed lithium disilicate with 3D-printed wax patterns, milled zirconia, and 3D-printed zirconia, have clinically acceptable marginal and internal fit. Milled zirconia and lithium disilicate veneers demonstrated superior marginal and internal fit compared to 3D-printed zirconia and heat-pressed lithium disilicate veneers with 3D-printed wax patterns.

Purpose: To analyze the microgap changes between hybrid-abutment crowns made of two materials and three internal taper connec9on implants with different connection designs before and after thermodynamic loading.

Materials and methods: A total of 30 implants-10 each of Straumann Bone Level Implant-RC (STR); GC AADVA Implant (AAD); and Astra-Tech OsseoSpeed EV (AST)-were included in this laboratory study. Each implant had an internal taper connection, but their designs were slightly different. Five hybrid-abutment crowns were fabricated using a lithium disilicate ceramic (LD), and five were fabricated using polymethylmethacrylate (PMMA) with CAD/CAM technologies for each implant system, providing six sample groups STR-LD, AAD-LD, AST-LD, STR-PMMA, AAD-PMMA, and ASTPMMA. The microgap volume was measured using micro-CT images obtained before and after thermodynamic loading equivalent to 4 months of clinical use. Student t test, one-way ANOVA, and Tukey test were used for comparisons.

Results: The greatest microgap volume increase was recorded (3.405% ± 1.567%) in the AST-LD group, and the lowest increase (0.45% ± 0.373%) was in the STR-PMMA group. A statistically significant difference in microgap increase was not detected among PMMA and LD groups: for STR-LD/STR-PMMA (t test: P = .273); for AAD-LD/AAD-PMMA (t test: P = .374); and for AST-LD/AST-PMMA (t test: P = .268). However, the difference in the microgap increase between the different implant systems was statistically significant.

Conclusions: The microgap between hybrid-abutment crowns and implants increased after short-term thermodynamic cycling. Hybrid-abutment crowns with different elastic modulus showed similar microgap increase. The geometric shape of the connection influenced the microgap increase.

Purpose: To analyze the effect of disinfectants on the roughness and mechanical properties of CAD/ CAM polymethylmethacrylate (PMMA) dentures.

Materials and methods: Two groups of denture base resins were tested-heat-polymerized and milled blocks. For each resin, 120 specimens were produced for flexural strength (FS) and flexural modulus (FM) analyses (total: 240 specimens), and 40 were produced for microhardness and surface roughness evaluations (total: 80 specimens). They were categorized into the following groups based on immersion: control (deionized water); H1 (1% sodium hypochlorite); H05 (0.5% sodium hypochlorite); and C2 (2% chlorhexidine) groups. The immersion periods were 0 (T0), 130 (T1), and 260 (T2) cycles. Statistical analyses were performed for flexural properties using threeway ANOVA. Microhardness (KHN) and surface roughness (Ra) were analyzed using repeated-measures ANOVA. A significance level of 5% was set.

Results: CAD/CAM PMMA showed higher FS (P = .001) and FM (P < .001) than conventional PMMA. The KHN value was superior to the conventional PMMA (P < .001). The chemical solution affected the surface roughness of both resins (P = .007). The CAD/ CAM PMMA block showed increased Ra values when H1 was used. Cycling separately increased the FS of conventional PMMA (T1 vs baseline; P < .05). However, the FM of CAD/CAM PMMA was higher (T1 and T2 vs baseline; P < .05). The time factor increased the microhardness of both resins (T2 vs baseline; P < .05).

Conclusions: The CAD/CAM resin showed higher values compared to conventional PMMA in all tests, regardless of the chemical solution used; however, the values obtained for both resins were clinically acceptable.