The International journal of prosthodontics最新文献

Purpose: To evaluate the distortion probability in impressions of completely dentate arches when different impression materials are used in relation to operator experience.

Materials and methods: A total of 28 students (Group A) and 7 dentists (Group B) performed three maxillary impressions on 28 participants, each using vinyl siloxane ether (VSE), polyether (PE), and irreversible hydrocolloid (IHC). Gypsum master casts were fabricated and subsequently digitized. Intraoral scans were taken as a control. Differences between master casts and intraoral scans were visualized with heatmaps, and planar deviations were investigated. If planar deviations > 120 μm were found, the impression was rated as 'distorted.' An additional superimposition using the casts from VSE or PE was performed to confirm the presence of distortions. The relative number of surfaces with distortions in each impression was calculated. The procedure was repeated for a distortion threshold of 500 μm. The statistical analyses included repeated measures ANOVA (RMA) and post hoc tests (α < .05).

Results: When 120 μm was considered as the threshold for distortions, IHC impressions showed higher distortion probability than PE impressions in Group A (P = .003) and Group B (P < .0001). In Group B, PE showed a lower distortion probability than VSE (P = .02). There was no significant difference between the study groups (P = .42). Considering 500 μm as a threshold for distortions, there was no difference between impression materials (P = .17) or study groups (P = .53).

Conclusions: There were no statistically significant differences in relation to operator experience. Different impression materials had a significant impact on distortion probability. PE impressions showed the lowest distortion probability.

This paper presents an efficient method for fabricating a full-arch implant prosthesis within one day, using a verification index through a three-dimensional (3D)-printed surgical guide. The technique involves the use of simple impression coping and laboratory analogs to ensure accurate prosthesis placement. Directly using 3D-printed surgical guides as a verification index simplifies and streamlines the procedure, offering a significant clinical advantage. This approach provides a clinically relevant advancement in prosthodontic practices by demonstrating a practical and instructive approach to enhance treatment outcomes.

Purpose: To compare the masking ability of monolithic CAD/CAM veneers placed over different resin cement shades and substrate colors.

Materials and methods: Veneers were milled from four different monolithic CAD/CAM restorative materials: feldspathic ceramic (VMII), lithium disilicate ceramic (Emax CAD), zirconiareinforced lithium silicate ceramic (VS), and high-translucency zirconia ceramic (YZ-XT). Veneers were luted on natural tooth-colored (ND1) or discolored substrates (ND3 or ND5) using two different resin cement shades (opaque white or translucent). Each CAD/CAM material, resin cement shade, and substrate combination comprised 9 sample veneers (N = 216). Color parameters were obtained using a dental spectrophotometer before and after luting. Color differences (ΔE00) were calculated using CIEDE2000 formula and compared to perceptibility (P = .81 ΔE00 units) and acceptability (AT = 1.77 ΔE00 units) visual thresholds. Color variation data were statistically analyzed using Kruskal-Wallis and Mann-Whitney U tests with Bonferroni-Holm correction (α = .05).

Results: The highest ΔE00 value was obtained in the VMII group placed over a discolored substrate, followed by the Emax CAD, YZ-XT, and VS groups. The effect of material types on ΔE00 values was significantly observed when the veneers were luted on discolored substrates using translucent resin cement (P < .05).

Conclusions: Restorative material type, substrate color, and resin cement shade affect the masking ability of monolithic CAD/CAM laminate veneers.

Treatment of acute cases of amelogenesis imperfecta (AI) is challenging in children due to the absence of a consensus statement on therapeutic recommendations. This article presents the effectiveness of an interdisciplinary approach-including orthodontics, orthognathic surgery, and prosthodontics using digital technology-in a child with AI and skeletal deformities. The early management over a 6-year period had a very positive impact on the quality of life related to oral health. The full-mouth rehabilitation in adulthood with all-ceramic crowns showed a fully satisfactory result after 60 months of follow-up.

Purpose: To investigate the effect of irradiation time and zirconia thickness using low power Er,Cr:YSGG laser irradia)on (for debonding purposes) on the thermal changes and shear bond strength (SBS) of resin-bonded 3% mol yIrium oxide stabilized tetragonal zirconia polycrystal (3YTZP) specimens.

Materials and methods: 3Y-TZP slices of 0.5-, 2-, and 3- mm thick were used. The temperatures during laser irradiation using single spot irradiation at different times (30 seconds, 60 seconds, 90 seconds, and 120 seconds) and line scanning irradiation from one spot to another at three different distances (2, 4, and 6 mm) were recorded. Single spot and line scanning irradiation data were analyzed using three-way ANOVA (α = .05) and generalized linear mixed model, respectively. Nonirradiated (control) and irradiated resin-bonded 3Y-TZP specimens were shear tested, and the data were analyzed using two-way ANOVA (α = .05).

Results: Under single spot irradiation, the laser-induced temperature was higher through thin 3Y-TZP at any time compared to thick 3Y-TZP. For the line scanning method, short distances (2 and 4 mm) resulted in a significant increase in temperature for 0.5-mm thick specimens. Laser irradiation significantly decreased the SBS of the 0.5-mm group compared to the nonirradiated group. After irradiation, the bond strength of the 2- and 3-mm thick 3Y-TZP was similar to the nonirradiated group.

Conclusions: The temperature and bond strength of low-power laser irradiated 3Y-TZP specimens was affected by the specimen thickness but not by the irradiation time tested. Low-power laser irradiation is an effective debonding method for thin Y-TZP restorations.

Lab-side-fabricated abutments and hybrid zirconia crowns, which are bonded to titanium bases with resin-based composites, require disinfection before insertion. This study investigated the effect of cleaning procedures (ultrasonic, autoclaving) and aging methods (24h, 90d, thermocycling) on the shear bond strength between alumina particle air-abraded titanium and zirconia (3Y-, 4Y- and 5Y-TZP) specimens luted with phosphate monomer containing adhesive systems and resin-based composite. Autoclaving significantly improved SBS (F (27,231) = 17.265, p < .001) compared to no cleaning and three-stage disinfection. No differences were identified with regard to zirconia or aging methods. Bond strength initially benefits from autoclaving but continuously approaches the comparative values over longer periods.

Purpose: To investigate temporomandibular disorder (TMD) prevalence as well as potential TMD risk factors among postgraduate students.

Materials and methods: In this cross-sectional and correlation study, 1,255 postgraduate students from different universities were recruited to answer Fonseca's Anamnestic Index (FAI) in addition to collected demographic data and relevant dental history. FAI was used to classify TMD severity. Of the 1,255 participants included, 593 had previous clinical/radiographic TMD reports. Chi-square and Fisher exact tests investigated the relation between each predictor and TMD at P ≤ .05. A logistic binary regression analysis examined the model fit using -2Log likelihood and Pseudo R2 tests at P ≤ .05.

Results: Based on previous clinical/radiographic reports and FAI, 73.4% of the participants had TMDs, of whom 57% had mild dysfunction, followed by moderate (31.7%) and severe (11.3%). There was a statistically significant association between sex, depression, lip/object biting, and clenching with TMDs (P < .001), where women were 2.302 times more likely to develop TMDs than men. The combination of lip biting and clenching in women dramatically increased the risk of TMDs (-2Log Likelihood = 385.7, P < .001 and a Cox and Snell value = 0.315 and a Nagelkerke value = 0.395).

Conclusions: TMDs seem to be highly prevalent among postgraduate students in Egypt, and female postgraduate students who bite their lips or grind their teeth are particularly highly prone to the condition. Object biting and depression could also be considered risk factors.

Purpose: To compare the translucency parameters and masking abilities of different monolithic CAD/CAM ceramics placed on different-colored substructures.

Materials and methods: Square-shaped specimens (12 × 12 × 1.5 mm) were prepared from feldspathic (C), leucite (EMP), lithium disilicate (e.max), zirconiareinforced lithium silicate (VS), resin nanoceramic (LU), polymer-infiltrated ceramic (VE), hybrid nanoceramic (GC), monolithic zirconia (TZI), and composite resin (TC) blocks (n = 10 per material). After mechanical polishing, the translucency parameter (TP) was calculated. Then, each ceramic specimen was measured on eight substructures, and the color difference between ND2 and each substrate was calculated with the CIEDE2000 formula. TP values were analyzed with one-way ANOVA and Games-Howell tests, and the color differences indicating masking ability were analyzed with two-way ANOVA and Tukey HSD tests.

Results: The highest TP was observed in TC, followed by LU, EMP, C,GC, e.max, VS, VE, and TZI. The ΔE00 color difference values of TZI, VS, and VE on all abutment colors, except for ND9, were below the acceptable threshold value.

Conclusions: All monolithic ceramic materials used in the study masked the ND1 and ND3 substrates. The ND9, representing severely discolored or devitalized preparations, could not be masked by any monolithic CAD/CAM ceramics used in the study.

Purpose: To identify the prevalence of and factors associated with total edentulism in the older Brazilian population and to verify whether edentulism influences self-perception of oral health and difficulty in eating.

Materials and methods: This cross-sectional, population-based study used the database of the National Health Survey conducted in Brazil. Chi-square test was initially used for data analysis. Subsequently, a multivariate analysis of Poisson multiple regression type was performed to verify the adjusted prevalence ratios.

Results: A total of 43,554 older adults participated in the study, of whom 32% had completely lost their teeth. This total edentulism, based on the multivariate analysis, was associated with female gender, advanced age, illiteracy, smoking, and lack of health insurance or dental insurance (P < .001 for all). Total edentulism had an impact on better self-perception of oral health (P < .001) and greater difficulties in eating (P = .001).

Conclusions: Total edentulism in older adults is associated with worse socioeconomic conditions and a worse lifestyle. This condition has a negative impact on diet and positively affects self-perception of oral health.