The International journal of prosthodontics最新文献

Purpose: To examine the long-term performance of bonded all-ceramic restorations, specifically veneers, in patients with amelogenesis imperfecta (AI). There are few studies of long-term outcomes using a minimally invasive procedure in these patients. This aspect is essential when treating young patients. All-ceramic restorations, especially veneers, offer a more tissue-preserving treatment but rely on successful bonding. However, due to the defect enamel in AI patients, the bond strength is lower.

Materials and methods: A retrospective evaluation of 40 subjects with AI (26 women, 14 men) was provided with a total of 360 bonded restorations (282 veneers, 78 crowns). The restorations were evaluated according to complications, survival, and success rate.

Results: The patients were observed up to 25.3 years (mean 15.4 ± 4.3 years). The mean age when receiving the restorations was 18.5 ± 4.2 years. In total, 59 (16.4%) restorations with prosthetic complications were made, 29 of which (8.1%) were remade (6 due to esthetic reasons, all in one patient) and 30 (8.3%) were recemented (60% caused by trauma). We found 11 teeth with caries and 3 with endodontic complications. The overall survival rate was 91.9%, and the overall success rate was 83.6%.

Conclusions: Bonded all-ceramic restorations with no active retention in AI patients have excellent performance. The most common complications were debonding and fractures. The treatment should be based on individual indications and be preceded by a multidisciplinary approach.

Purpose: To investigate the resistance of an implant crown telescopically engaged to a geometrically defined hexagonal abutment with and without cement under compressive dynamic cyclic fatigue loading.

Materials and methods: 40 crowns, 9 mm in height, were cast from prefabricated plastic copings, each telescopically engaged to a 3-mm-high machined hexagonal abutment. 20 crowns were retained with zinc phosphate cement, and 20 crowns were retained with a screw. A vertical load of 15 kg was applied to all samples under oscilla)on. A Periotest was used to measure the mobility of the implant crown in Periotest values (PTV). Test endpoints were defined by the following: fatigue cycles ≥ 20 million; crown PTV > 10; or if samples became visibly loose or component fracture.

Results: Cement-retained crowns failed on average at 2.60 x 106 cycles ± 2.27, while screw-retained crown samples failed at 2.17 x 106 cycles ± 1.27 with no significant difference (P > .05). Implant and abutment screw fractures were the most prevalent mode of failure in the cement-retained group, while in the screw-retained group, failures were caused by the loosening of one or both screw joints. The rate of increase in PTV was higher in the screw-retained group than in the cement-retained group.

Conclusions: Under the experimental conditions, an implant crown telescopically engaged vertically to a 3-mm-tall hexagonal abutment, under compressive dynamic cyclic fatigue loading with or without cement, demonstrated no differences in resistance or failure outcomes. A cement-retained implant crown with telescopic engagement to the abutment is more rigid, resulting in more implant and abutment screw fractures than loosening.

Purpose: To assess the clinical performance of CAD/CAM laminate veneers placed by a single operator and systematically evaluated for up to 10 years.

Materials and methods: A total of 197 laminate veneers fabricated using either feldspathic ceramics (VMII) or lithium disilicate ceramics (EmaxCAD) were followed up to 10 years in 32 patients. Technical, esthetic, and biologic findings of each restoration were evaluated using modified United States Public Health Service criteria. The survival and complication rates were assessed using Kaplan-Meier survival analysis and compared using log-rank test. Statistical significance was set at P < .05.

Results: The estimated Kaplan-Meier survival rate was 91.9% after the mean observation period. According to the ceramic system used, the estimated Kaplan-Meier survival rate amounted to 92.7% for EmaxCAD and 89.1% for VMII. Survival rates were significantly affected by the location of veneer according to log-rank test (P < .05). A range of survival rates between 83.3% and 98.6% were observed based on the location of veneer.

Conclusions: CAD/CAM laminate veneers milled from feldspathic or lithium disilicate ceramics have comparable long-term survival rates. Oral positioning affects the survival of veneers. Veneers of incisors have higher survival rates than the veneers of maxillary canines and premolars.

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.

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.