Wear Behavior of Graded Glass/Zirconia Crowns and Their Antagonists

Abstract

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 (mm 3) 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 mm 3. The combination of polishing and glass infiltration on the occlusal surface of monolithic zirconia crowns yielded reduced wear on both crown and antagonist.

Monolithic Zirconia: An Update to Current Knowledge. Optical Properties, Wear, and Clinical Performance

“…The wear properties of monolithic zirconia were evaluated in many in vitro studies (Table S2) [73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101,102,103,104,105,106,107,108,109,110]. Some of them compared the wear properties of various restorative materials including monolithic zirconia [1,74,85,86,87,88,89,90,91,92] and others compared the wear properties of monolithic zirconia following different ways of surface treatment [77,78,80,81,84,92,93,94,95,96,97].…”

“…The only objecting study attributes the diversity of the results to the different polishing techniques used [94]. According to recent studies, polished and glazed monolithic zirconia crowns demonstrate reduced wear of their antagonists as well as of the restoration itself according to Kaizer et al [84]. However, this is not in agreement with Gundugollu et al [98], who reported that glazed polished monolithic zirconia is more likely to cause wear of the antagonist enamel compared to unglazed polished monolithic zirconia.…”

Wear of feldspathic-ceramic-veneered zirconia posterior FPDs after 10 years

“…demonstrated that zirconia crowns polished in the pre-sintered state with occlusal glass in ltration are not only resistant to the wear phenomenon, but also gentle on the natural antagonist [56].…”

Wear of glass-ceramic-veneered zirconia posterior FPDs after 10 years

“…These differences may be caused by differences in the surface condition, as this in uences the wear behavior. For example, Kaizer et al demonstrated that zirconia crowns polished in the pre-sintered state with occlusal glass in ltration are not only resistant to the wear phenomenon, but also gentle on the natural antagonist [56].…”