Wear of the Enamel Antagonist and Five Restorative Materials

Some restorative materials may wear the opposing tooth while some restorative materials will demonstrate significant wear. Objectives: To measure the wear of occlusal enamel and 5 restorative materials. Methods: 8 flat-specimens (t»3.0mm) of each material (Z100 Composite [Z], Paradigm MZ100 [P], IPS Empress [E], Zirconia ceramic (LAVA) [L], and Cercon ceramic [C]) were placed into specimen holders using PMMA and polished with a series of 400-, 600-, and 1200-grit SiC paper under water-spray. [L] and [C] were polished with additional 180- and 320-grit SiC paper. Specimens were wet-finished with 0.05µ alumina slurry/polishing cloth using a rotational polishing device (Buehler Ltd., IL, USA) and cleaned in an ultrasonic bath (5min) in distilled water and rinsed with water. Specimens were tested against maxillary premolars in the modified Leinfelder wear testing machine for 20,000cycles (load= 75N). 50µ PMMA beads were used as media (15g beads, 9g water). The restorative materials and the cusps of the premolars were scanned before and after wear using a non-contact 3D profilometer (PROSCAN 2000, Scantron, England) to determine loss of restorative material (wear-depth and volume) and volume loss on teeth (ProForm software). Data were analyzed with two factor ANOVA and Tukey/Kramer post-hoc test (p=.05). Results: (Mean±SD).

	Z	P	E	L	C
Volume (mm3)	0.008±0.006	0.004±0.002	0.0003±0.0005	0	0
Depth (µ)	39.4±16	31.9±20	1.8±3	0	0
Enamel wear(mm3)	0.128±0.07	0.131±0.09	0.157±0.03	0.422±0.2	0.194±0.1

Wear on the materials varied significantly for volume loss between Z and other materials, no significant differences were found in wear-depth between Z and P. Ceramic materials had better wear resistance than composite resin. Laboratory fabricated blocks of Z100 had better wear than hand prepared Z100 blocks. L showed significantly higher wear on enamel than all the other materials. Conclusions: Antagonist wear should be considered while materials are placed against natural tooth. Partially supported by T35-HL07473.