Wear Behavior of Graded Glass/Zirconia Crowns and Their Antagonists.

Monolithic zirconia crowns have become very popular; their surface finish is considered a key factor for restoration longevity. While polishing has shown excellent results in vivo, the surface glass infiltration of zirconia may offer superior damage resistance and aesthetic advantages by using tooth-colored glasses. Thus, the purpose of this study is to evaluate the efficacy of polishing and glass infiltration on the wear behavior of monolithic zirconia crowns. The wear behavior of intact natural molar teeth was investigated as a reference. Zirconia crowns were divided into 3 groups: PolZ-sintered then polished; PolGZ-polished in the presintered state and then glass infiltrated and sintered; NoPolGZ-as machined, glass infiltrated and sintered. Crowns were adhesively bonded to a dentin-like abutment. Zirconia crowns and molar teeth ( n = 15) were subjected to contact-slide-liftoff cyclic loading (200 N, 1.25 million cycles) with a steatite sphere ( r = 3 mm) as an antagonist in water. Surface and subsurface damages were investigated with optical and scanning electron microscopies. Wear depth and volume loss were determined with micro-computed tomography. PolGZ and NoPolGZ crowns exhibited shallow wear scars, where material loss remained within the glass/zirconia layer with no visible cracks. Meanwhile, PolZ crowns presented no visible wear damage. Volume loss (mm3) in the steatite antagonist was as follows (mean ± SD): PolZ = 0.022 ± 0.007, PolGZ = 0.011 ± 0.004, and NoPolGZ = 0.014 ± 0.006. Molar teeth yielded no measurable wear on the antagonist, while the wear scar on the teeth was greater than that on zirconia crowns, ranging from 0.07 to 0.35 mm3. The combination of polishing and glass infiltration on the occlusal surface of monolithic zirconia crowns yielded reduced wear on both crown and antagonist.

Correlation of previous experience, patient expectation and the number of post-delivery adjustments of complete dentures with patient satisfaction in a Brazilian population.

A number of variables may influence the outcome of complete denture therapy. The objective of this study was to verify possible correlations between previous experience with dentures, patient expectation and the number of post-delivery adjustments with patient satisfaction after treatment. One hundred patients (mean age 61·9 ± 10·3) rated their previous experiences with complete dentures and their expectations before and satisfaction after treatment on a visual analogue scale (VAS) using scores from 0 (worst results) to 10 (best results). The number of post-delivery adjustments and other patient-related clinical variables was also noted. Patient expectation scores were higher than previous experience scores and satisfaction after treatment scores. Positive and weak correlations were found between previous chewing experiences with complete dentures, with regard to chewing expectations and comfort of use. Phonetics and comfort of use in previous experiences presented a positive correlation with expectations for chewing, aesthetics, phonetics and comfort of use. Groups of patients with different levels of education presented significant differences in expectation scores regarding comfort of use as well. A negative and weak correlation was found between phonetics satisfaction and the number of post-delivery adjustments. Patients' expectations for the therapy were higher than their satisfaction after treatment. Previous experiences with complete dentures could slightly influence patients' expectations and satisfaction, whereas lower scores for previous experience with complete dentures caused lower scores for both expectation and satisfaction. Patients' educational levels and the number of post-delivery adjustments influenced negatively the expectations about comfort of use and patient satisfaction, respectively.

Three-dimensional finite element analysis of stress distribution in peri-implant bone with relined dentures and different heights of healing caps.

The purpose of this study was to evaluate the influence of height of healing caps and the use of soft liner materials on the stress distribution in peri-implant bone during masticatory function in conventional complete dentures during the healing period by using finite element analysis. Three-dimensional models of a severely resorbed mandible with two recently placed implants in the anterior region were created and divided into the following situations: (i) submerged implants, (ii) healing cap at gingival level and (iii) 1·5-mm supragingival. All these situations were also analysed for a conventional complete denture and a denture relined with a 3-mm-thick layer of soft liner material. The models were exported to mechanical simulation software that presented two simulations, one with load in the inferior right canine (35 N) and the other in the inferior right first molar (50 N). Data were evaluated using Maximum Principal Stress provided by the software. All models showed a stress concentration in the cortical bone corresponding to the cervical part of the implant. The simulations with non-submerged implants showed higher values of stress concentration than those that were submerged. Likewise, soft liner materials presented better results than when the denture base was not relined. The height of the healing caps seems to have a direct influence on the stress distribution in the peri-implant bone during the healing period. Considering the values obtained in this study, the use of soft liners with submerged implants seems to be the most suitable method to use during the period of osseointegration.

Patients' expectations and satisfaction of complete denture therapy and correlation with locus of control.

Considering the importance of patients' satisfaction with complete denture therapy and the influence of psychosocial aspects and expectations regarding satisfaction with their dentures, the present study aimed to test for a correlation between locus of control profiles and expectations before and satisfaction after complete denture therapy. Sixty-four patients rated their expectations for aesthetic and functional results of complete denture therapy on a 10-cm visual analogue scale (VAS), using scores from 0 (worst results) to 10 (best results). A similar questionnaire was used regarding satisfaction after final denture adjustments. Patients also answered a locus of control questionnaire in the initial interview. ANOVA and a chi-squared test were used to test for correlations among ratings, patient gender and locus of control profiles. The significance level adopted was 0.05. The expectation ratings before treatment were significantly lower than the post-treatment completion ratings, both for aesthetics (P < 0.001) and function (P = 0.004). There was no correlation between locus of control profiles and patients' ratings or between gender and VAS scores. No correlation was found between locus of control profiles and scores for expectations before and satisfaction after complete dentures.