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J Prosthodont ; 29(8): 693-698, 2020 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-32767417


PURPOSE: This study was done to compare the survival rates of cast gold and ceramic onlays placed in a dental school setting. MATERIAL AND METHODS: An electronic search was conducted in the patient records at Adams School of Dentistry, University of North Carolina at Chapel Hill for onlay codes that were in the database (From 1998 until 2018). Progress notes and radiographs were scrutinized to establish the survival time of the restorations. Any complications that occurred during the life time of the restorations were noted. The survival was summarized by categorization based on ranges of survival time in years; group 1: 1 to 5 years, group 2: 6 to 22 years. The mean survival time and standard deviation were calculated. One-way ANOVA was used to determine whether there was a statistically significant difference in the survival times between gold and ceramic onlays. RESULTS: The mean survival rate of cast gold onlays (86.6%) was comparable to that of ceramic onlays (81.1%). The gold onlays in Group 1 had a higher mean survival time (2.43 years) than the ceramic onlays (2.03 years). This difference was statistically significant (p = 0.002). The ceramic onlays in Group 2 had a mean survival time of 19.75 years while gold onlays had a mean survival time of 17.63 years. This difference was not statistically significant (p = 0.91). CONCLUSION: It was concluded that while the survival rate of ceramic onlays (81.1%) was inferior to that of cast gold onlays (86.6%), it was comparable.

Oro , Incrustaciones , Cerámica , Porcelana Dental , Fracaso de la Restauración Dental , Humanos , Estudios Retrospectivos
J Prosthet Dent ; 123(4): 635-640, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-31383533


STATEMENT OF PROBLEM: A direct relationship has been reported between yttria concentration and translucency in zirconia restorations. However, increased yttria concentration also increases the cubic phase of the zirconia, which reduces its strength. The effect of increased yttria content on the fracture resistance of zirconia as a function of material thickness after fatigue testing requires evaluation. PURPOSE: The purpose of this in vitro study was to use the biaxial flexural test to evaluate the effect of yttria concentration on the mean fracture load (N) before and after fatiguing and thermocycling as a function of zirconia thickness. MATERIAL AND METHODS: Disk-shaped specimens of 5 mol% yttria partially stabilized zirconia (5Y-PSZ, BruxZir Anterior Solid Zirconia) and 3 mol% yttria partially stabilized zirconia (3Y-PSZ, BruxZir Shaded Zirconia) were prepared to thicknesses of 1.2 and 0.7 mm. For each thickness, the biaxial flexural test was used to measure the fracture load (N) before and after fatigue testing, with 1.2 million cycles at a 110-N load and simultaneous thermocycling at 5 °C to 55 °C (n=20). The data were analyzed by repeated-measures ANOVA (α=.05). RESULTS: Yttria concentration, thickness, and exposure to fatiguing had a statistically significant effect on the mean biaxial flexural load (yttria concentration: P<.001; thickness: P<.001; fatiguing: P=.004 for the 3Y-PSZ). One of the major findings in this study was that 30% of the 1.2-mm-thick 5Y-PSZ specimens and 80% of the 0.7-mm-thick 5Y-PSZ specimens fractured during fatiguing. All specimens of the 3Y-PSZ groups survived the fatiguing protocol. The 3Y-PSZ groups had statistically significant higher flexural loads than the 5Y-PSZ groups. The 1.2-mm thickness groups had statistically significant higher flexural loads than the 0.7-mm thickness groups. CONCLUSIONS: Yttria concentration had a significant effect on the strength of zirconia. 5Y-PSZ was considerably less resistant to fracture before and after fatigue testing than 3Y-PSZ. Decreasing the thickness of zirconia reduces its fracture resistance, regardless of the zirconia type.

Materiales Dentales , Circonio , Análisis del Estrés Dental , Ensayo de Materiales , Propiedades de Superficie
J Prosthet Dent ; 124(1): 10-13, 2020 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-31757442


Trying to capture all the details of multiple teeth preparation in one impression is challenging. Techniques have been suggested to extend the working time of an impression material. This article describes a segmental impression technique to accurately capture all the preparation margins while allowing additional impression-making time.

Materiales de Impresión Dental , Técnica de Impresión Dental
J Prosthet Dent ; 122(4): 404-409, 2019 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-30928224


STATEMENT OF PROBLEM: Translucent zirconia has been marketed to dentists seeking to provide esthetic monolithic dental restorations. Evidence on differences in translucency between recently introduced translucent zirconia and conventional zirconia before and after fatigue testing with thermocycling is lacking. PURPOSE: The purpose of this in vitro study was to evaluate the effect of fatiguing and thermocycling on the translucency of 5 mol% yttria partially stabilized zirconia (5Y-PSZ) and 3 mol% yttria partially stabilized zirconia (3Y-PSZ) at clinically relevant thicknesses. MATERIAL AND METHODS: Translucent zirconia (BruxZir Anterior Solid Zirconia [5Y-PSZ]) and conventional zirconia (BruxZir Shaded Zirconia [3Y-PSZ]) were evaluated. Disk-shaped specimens were prepared to 0.7-mm and 1.2-mm thicknesses for each zirconia type. Four groups (n=10/group) were evaluated. Translucency parameter (TP), contrast ratio (CR), and light blockage percentage (Lb%) were recorded by using an integrating sphere spectrophotometer before and after fatiguing (1.2 million cycles at 110-N load with simultaneous thermocycling at 5 °C to 55 °C). Data were analyzed by repeated-measures analysis of variance for statistical significance (α=.05). CR values were compared with the reported 0.06 translucency perception threshold of the human eye. RESULTS: A statistically significant difference was found in TP, CR, and Lb% between 5Y-PSZ and 3Y-PSZ (P<.001). Thickness had a statistically significant effect on TP, CR, and Lb% (P<.05). The 0.7-mm thickness groups were more translucent and had lower Lb% than the 1.2-mm thickness groups (P<.001). Baseline ranking from most to least translucent according to TP and CR measurements was as follows: 5Y-PSZ (0.7 mm), 3Y-PSZ (0.7 mm), 5Y-PSZ (1.2 mm), and 3Y-PSZ (1.2 mm). Lb% was 64% at the 1.2-mm and 56% at the 0.7-mm thickness in the 3Y-PSZ groups. Lb% was 61% at the 1.2-mm and 53% at the 0.7-mm thickness in the 5Y-PSZ groups. None of the groups, before and after fatiguing, had a CR value exceeding the clinically perceivable 0.06 translucency perception threshold value. CONCLUSIONS: Translucent (5Y-PSZ) and conventional (3Y-PSZ) zirconias evaluated in this study displayed degrees of translucency that were inversely related to the zirconia thickness. 5Y-PSZ was more translucent and blocked less light than 3Y-PSZ, but this difference may not be perceivable to the human eye. Both 5Y-PSZ and 3Y-PSZ were optically stable after fatiguing and thermocycling.

Estética Dental , Circonio , Materiales Dentales , Humanos , Ensayo de Materiales , Espectrofotometría
J Esthet Restor Dent ; 31(1): 40-50, 2019 01.
Artículo en Inglés | MEDLINE | ID: mdl-30302909


OBJECTIVES: To assess and compare the 5-year success rate of resin-bonded fixed partial dentures (RBFPDs) fabricated from different materials. METHODS: An electronic search on 3 databases from January 1965 to March of 2017 was done for human randomized clinical trials (RCTs), and prospective and retrospective cohort studies. The key words used in the search were: Bridge OR bridges OR fixed partial OR fixed dental AND resin bonded OR Maryland OR ceramic bonded. Quality assessment was done using the Newcastle-Ottawa scale. Success was defined as the RBFPDs remaining in situ and not having experienced debonding, biological failures, or mechanical failures at the examination visit. RESULTS: Meta analyses of the included studies showed an estimated 5-year success rate of 88.18% for the metal framework RBFPDs and 84.41% for the nonmetal framework RBFPDs. The estimated 5-year success rate for each nonmetal material category was 92.07% for zirconia, 94.26% for In-Ceram alumina, and 84.83% for fiber-reinforced composite. The failure rate was not statistically significant among the single, double, and multiple retainers RBFPDs (P > .05). Technical complications were the main reason for failures. CONCLUSION: The 5-year clinical performance of RBFPDs is similar to the performance of conventional fixed partial dentures (FPDs) and implant-supported crowns. CLINICAL SIGNIFICANCE: Clinicians should consider using RBFPDs more often because their clinical performance is similar to the performance of conventional FPDs and implant-supported crowns.

Diseño de Dentadura , Dentadura Parcial Fija con Resina Consolidada , Resinas Sintéticas , Fracaso de la Restauración Dental , Dentadura Parcial Fija , Humanos , Estudios Prospectivos , Ensayos Clínicos Controlados Aleatorios como Asunto , Estudios Retrospectivos