In vivo analysis of enamel wear against ceramic materials

Objective: (1) To test the hypothesis that wear rates of ceramic are equivalent to the wear rates of their enamel antagonists; (2) To test the hypothesis that the wear rates of contralateral teeth are equivalent to the wear rates of ceramic crowns. Methods: Thirty six (36) teeth (from 31 patients selected) needing full coverage crowns were randomly assigned to receive either a metal-ceramic (D'Sign, Ivoclar, Vivadent) or an all-ceramic crown (IPS Empress2 or Eris EXC, Ivoclar, Vivadent). A single unit crown was fabricated from either one of two all-ceramic materials or a metal-ceramic material. A vinyl polysiloxane impression was made of the maxillary and mandibular arches to record the occlusal surfaces of the cemented crown, its antagonist tooth and its contralateral tooth, after one week, 1 year and 2 years, post cementation. Casts were poured in gypsum (GC Fujirock) and scanned using a 3D Laserscanner (Willytec, Germany). Maximum wear was calculated by superimposing the baseline one-week image with first and second year images. Results: The mean maximum wear rates for the ceramic crowns were 48.7±35.1 μm after year 1 and 58.8±36.5 μm for year 2. The mean maximum wear rates for the natural enamel antagonists were 54.9±23.6 μm for year 1 and 69.1±42.9 μm for the year 2. Teeth contralateral to the crowns exhibited a maximum wear of 42.4±23.4 μm maximum wear for the year 1 and 49.5±31.7 μm for year 2. One-way ANOVA (α = 0.05 ) revealed that there was no significant difference in the maximum wear rates between the ceramic crowns, their natural antagonists and their contralateral teeth. Conclusions: The new breed of ceramics is promising in that in vivo wear rates are within the range of normal enamel wear.

This study was supported by Ivoclar Vivadent.