Objective:
To evaluate the effect of polished, glazed, aged and adjusted zirconia on opposing enamel.
Methods:
The study (n=8) included 5 groups of zirconia ceramic (Table), a veneering porcelain (Ceramco 3) and enamel (control). The cusps of molars were standardized with a tapered diamond (Brasseler/USA) to serve as the opposing enamel tooth stylus. The ceramic and tooth specimens were mounted in holders using acrylic resin, scanned to determine surface roughness (Ra) and then load cycled in a newly developed UAB-chewing simulator (10N vertical load/2mm slide/20cycles/min). A solution of artificial saliva (33.3% glycerin/66.6 % water) was used as third body media. PVS impressions (3M ESPE/USA) of each opposing enamel cusp were taken at baseline, 200,000 and 400,000 cycles and poured with vacuum mixed die stone (WhipMix/USA). The stone models were separated from the impression and scanned using a 3D non-contact surface profilometer (Proscan 2000/UK). Scans from baseline were compared to scans obtained after 200,000 and 400,000 load cycles and were super-imposed (Proform/UK) to determine enamel and ceramic wear (mm3). Data was analyzed with ANOVA and Tukey-Kramer post-hoc tests (p=0.05).
Results:
Mean±SD
|
| Ceramic volume loss(mm³) | Opposing enamel volume loss (mm³) | Original roughness (µ) | |||
Cycles | |||||||
200,000 | 400,000 | 200,000 | 400,000 | ||||
1 | Polished zirconia | 0.00±0.0a | 0.00±0.0a | 0.11±0.04a | 0.21±0.05a | 0.17±0.07 | |
2 | Glazed zirconia | 0.381±0.1c,d | 0.62±0.16c,d | 0.87±0.21c,d | 1.18±0.2c,d | 0.76±0.12 | |
3 | Polished then reglazed zirconia | 0.27±0.06c | 0.49±0.10c | 0.59±0.1c | 0.88±0.12c | 0.69±0.1 | |
4 | Glazed and adjusted Zirconia | 0.32±0.08b | 0.53±0.09b | 0.29±0.15b | 0.43±0.19b | 3.8±0.2 | |
5 | Artificially aged zirconia | 0.00±0.00a,b | 0.00±0.00a | 0.16±0.04a,b | 0.25±0.05a | 0.23±0.04 | |
6 | Ceramco3 | 0.87±0.1b | 0.42±0.11b | 1.46±0.5b | 2.15±0.5b | 2.6±1.1 | |
7 | Enamel | 0.24±0.08d | 1.29±0.1d | 0.29±0.21d | 0.49±0.2d | 1.6±0.16 | |
Similar superscripts represent statistically similar groups.
Conclusions :
- Polished zirconia wears enamel the least (p<.05).
- Glazed zirconia had the greatest enamel wear (p=.05).
- Ceramco 3 veneering porcelain had significantly greater wear than all other ceramics. Supported in part by a grant from Ivoclar.