Enamel wear caused by monolithic zirconia crowns after 6 months of clinical use

Abstract

The purpose of this study was to evaluate enamel wear caused by monolithic zirconia crowns and to compare this with enamel wear caused by contralateral natural antagonists. Twenty monolithic zirconia crowns were placed in 20 patients requiring full molar crowns. For measurement of wear, impressions of both jaws were made at baseline after crown cementation and at 6-month follow-up. Mean and maximum wear of the occlusal contact areas of the crowns, of their natural antagonists and of the two contralateral natural antagonists were measured by the use of plaster replicas and 3D laser scanning methods. Wear differences were investigated by the use of two-sided paired Student's t-tests and by linear regression analysis. Mean vertical loss (maximum vertical loss in parentheses) was 10 (43) μm for the zirconia crowns, 33 (112) μm for the opposing enamel, 10 (58) μm for the contralateral teeth and 10 (46) μm for the contralateral antagonists. Both mean and maximum enamel wear were significantly different between the antagonists of the zirconia crowns and the contralateral antagonists. Gender and activity of the masseter muscle at night (bruxism) were identified as possible confounders which significantly affected wear. Under clinical conditions, monolithic zirconia crowns seem to be associated with more wear of opposed enamel than are natural teeth. With regard to wear behaviour, clinical application of monolithic zirconia crowns is justifiable because the amount of antagonistic enamel wear after 6 months is comparable with, or even lower than, that caused by other ceramic materials in previous studies.

An overview of monolithic zirconia in dentistry

“…That is why, to obtain more reliable results, in vivo studies are needed. In their in vivo study, Stober et al [57] evaluated the enamel wear caused by MZCs under clinical conditions (20 MZCs placed in 20 patients requiring full molar restoration). The patients had natural opposing teeth, and two natural contralateral antagonistic teeth were included.…”

Antagonist wear of monolithic zirconia crowns after 2 years

“…Further clinical work on full-contour zirconia has shown differences between zirconia crowns and antagonist wear after 6-month in situ [8]. The study selected natural enamel or filled teeth as antagonists.…”

Fracture resistance of zirconia-composite veneered crowns in comparison with zirconia-porcelain crowns

“…An alternative approach is to eliminate the veneer and produce a full contour monolithic zirconia crown 12) . While monolithic zirconia crowns have recently become popular, there are still concerns regarding the wear they could cause to natural opposing teeth 13,14) . Further the possible decrease in strength associated with a phenomenon known as low temperature aging or degradation (LTD) that could be induced in the aqueous environment 15,16) .…”