Clinical assessment of enamel wear caused by monolithic zirconia crowns

Abstract

The purpose of this study was to measure enamel wear caused by antagonistic monolithic zirconia crowns and to compare this with enamel wear caused by contralateral natural antagonists. Twenty monolithic zirconia full molar crowns were placed in 20 patients. Patients with high activity of the masseter muscle at night (bruxism) were excluded. For analysis of wear, vinylpolysiloxane impressions were prepared after crown incorporation and at 6-, 12-, and 24-month follow-up. Wear of the occlusal contact areas of the crowns, of their natural antagonists, and of two contralateral natural antagonists (control teeth) was measured by use of plaster replicas and a 3D laser-scanning device. Differences of wear between the zirconia crown antagonists and the control teeth were investigated by means of two-sided paired Student's t-tests and linear regression analysis. After 2 years, mean vertical loss was 46 μm for enamel opposed to zirconia, 19-26 μm for contralateral control teeth and 14 μm for zirconia crowns. Maximum vertical loss was 151 μm for enamel opposed to zirconia, 75-115 μm for control teeth and 60 μm for zirconia crowns. Statistical analysis revealed significant differences between wear of enamel by zirconia-opposed teeth and by control teeth. Gender, which significantly affected wear, was identified as a possible confounder. Monolithic zirconia crowns generated more wear of opposed enamel than did natural teeth. Because of the greater wear caused by other dental ceramics, the use of monolithic zirconia crowns may be justified.

Retrospective clinical evaluation of posterior monolithic zirconia restorations after 1 to 3.5 years of clinical service

“…In our clinical experience it is sometimes difficult to provide anatomical tooth morphology when MZR thickness is less than 1.0 mm. Stober et al used preparations that were 0.5-0.7 mm circular and 1.0-1.2 mm occlusal (31). In the present study most teeth had an MZR thickness greater than 1.0 mm, and only one MZR fractured, after 38 months of function.…”

“…Previous studies suggest that well-polished surfaces are critical for minimizing wear (17,20,27). A previous clinical study of wear behavior reported that MZR use might be justified because MZRs exhibit less wear than other dental ceramics, although, as compared with natural teeth, monolithic zirconia results in significantly greater wear of natural antagonists (31). In the present study, all MZRs were polished after occlusal adjustments, as recommended in previous studies, and no patients reported occlusal discomfort or tooth wear.…”

“…Recent in vitro studies of the basic properties and clinical performance of zirconia restorations yielded promising findings (17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28). Although several clinical reports have highlighted the effectiveness of MZRs, including single restorations and fixed partial dentures for teeth and implants (29)(30)(31), few studies have investigated the outcomes of MZRs. This study retrospectively assessed MZR outcomes and describes MZR treatment modalities in light of the present findings.…”

Randomized clinical study of wear of enamel antagonists against polished monolithic zirconia crowns

“…This is the reason for incorporating an enamel-enamel control that is patient specific where the enamel antagonist wear for each material can be compared with the enamel-enamel wear within the same conditions. Three [26,27], including this study, out of the five studies employed enamel-enamel controls. For enamel versus enamel in patients with zirconia crowns, the enamel wear values are: 26.2 μm [27], 95 μm [26] and 61.6 μm for this study, However, there are differences among the three studies in that the time period is different with Stober’s [26] study at 2 years and the others at 1-year analysis and that the higher valued studies all report maximum wear whereas Munde’s [27] study reported mean wear.…”

Grinding and polishing efficiency of a novel self-glazed zirconia versus the conventional dry-pressed and sintered zirconia ceramics

“…However, it has been revealed that the high hardness per se is not the determining factor responding for the wear of the opposite teeth [12]. The excessive abrasion of the opposite natural teeth is more of the result of a rougher surface of the restorations formed by clinic adjustment and/or by breaking of the veneering or glazing layer [8,13,14].…”