Effects of two grading techniques of zirconia material on the fatigue limit of full-contour 3-unit fixed dental prostheses

Abstract

Objective This study evaluated the effects of two grading zirconia techniques on the fatigue limit of 3-unit fixed dental prostheses (FDPs). Methods Presintered blocks of 3Y-TZP were milled to obtain sixty-nine 3-unit FDPs, which were divided into three groups (n = 23). The control group (CTL) was sintered and glazed following manufacturer’s instructuctions. The two experimental groups presintered FDPs received a surface silica/glass infiltration treatment before the sintering process. Silica sol-gel group (SSG) was graded by the sol-gel processing route, while the glass-zirconia-glass group (GZG) was graded by an enameling technique. Graded groups did not receive a glaze layer after sintering. All FDPs were then luted with a dual-curing resin cement on composite abutments, embedded in polyurethane and stored in water for five days. The initial load of the fatigue test was calculated based on the results of the monotonic testing applied on three specimens of each group. To determine the fatigue limit, 20 samples of each group were subjected to staircase testing (100,000 cycles/5 Hz). Results The fatigue limits (in Newtons) were CTL = 1607.27, SSG = 1824.31, and GZG = 2006.57, and the Dixon and Mood test indicated statistically significant differences among groups (95% confidence interval). Significance The infiltration of silica and glass on bulk zirconia, by two different grading methods, increased the fatigue limits of monolithic zirconia FDPs.

Effect of Grinding and Multi-Stimuli Aging on the Fatigue Strength of a Y-TZP Ceramic

“…Data were subjected to the Dixon and Mood method, which involves maximum-likelihood estimation techniques for analytical solutions to the problem of determining the mean and standard deviation (22,23). This method assumes that the fatigue strength follows a normal distribution.…”

“…After testing, the biaxial flexure fatigue strength mean (σf), standard deviation (SD) and 95% confidence intervals (CI α= 0.05) was calculated, according to Collins (22), based on the data of the less frequent event (survival or failure), as described on Villefort et al (23).…”

Silica coating followed by heat‐treatment of MDP‐primer for resin bond stability to yttria‐stabilized zirconia polycrystals

“…The free surface for bonding was finished with #400, #600, and #1200 sandpaper in a polishing machine (Politriz PSK‐2V, ERIOS, São Paulo, Brazil). Next, blocks were cleaned in an ultrasonic bath with distilled water for 10 min (Vitasonic II, VITA Zahnfabrik) to remove polishing debris and sintered following manufacture recommendations firing protocol: 1.5 h for increasing temperature → ending temperature (1530°C for 2 h) → cooling to 400°C with firing chamber being closed . After, the blocks were embedded into acrylic resin (Classico, São Paulo, Brazil), keeping the bonding surface to be treated/bonded exposed …”

Fatigue limit of monolithic Y-TZP three-unit-fixed dental prostheses: Effect of grinding at the gingival zone of the connector

“…Restorations were sintered according to manufacturer instructions (1530 ºC/120 min) in a Vita Zyrcomat T furnace (Vita Zahnfabrik) and subjected to the following subsequent treatments: control group ( n = 23) (Villefort et al, 2017): the specimens were coated with a glaze layer (sintering temperature/time: 900 °C/60 s) on the external surface (VITA Akzent Plus Glaze, Vita Zahnfabrik); grinding group ( n = 23): firstly the bridges were ground by a single trained operator under water cooling with diamond burs (30 μm, 3215FF, KG Sorensen): the diamond bur was positioned at the gingival area of the connectors and movements were performed on the buccal-lingual way, respecting the anatomy of the area, until all surface was completely treated by the bur. Cautious was taken to not reduce the connectors sectional area.…”