Wear behavior of new composite restoratives

This study investigated the wear resistance of recently introduced nanofill (Filtek Supreme [FS], 3M-ESPE) and ormocer (Admira [AM], Voco) composites and compared their wear characteristics to microfill (Filtek A110 [AO], 3M-ESPE]), minifill (Esthet X [EX], Dentsply; Filtek Z250 [ZT], 3M-ESPE) and polyacid-modified (Dyract AP [DY], Dentsply) composites. Six specimens were made for each material. The specimens were conditioned for one week in distilled water at 37 degrees C and subjected to wear testing at 20 MPa contact stress against SS304 counter-bodies using reciprocal compression-sliding wear instrumentation. Distilled water was used as lubricant. Wear depth (microm) was measured using profilometry every 5,000 cycles up to 20,000 cycles. The results were analyzed using ANOVA/Scheffe's test (p<0.05). Wear of the materials was cycle and fatigue dependent. Although no significance in wear was observed between materials after 5,000 cycles of wear testing, significant differences were observed at 10,000 cycles and greater. After 20,000 cycles of wear testing, ranking was as follows: ZT > DY >AM > AO > FS > EX. Wear ranged from 39.90 microm for EX to 113.32 microm for ZT. The wear resistance of ZT and DY was significantly lower than AO, FS and EX In addition, ZT experienced significantly more wear than AM. Under the conditions of this in-vitro study, the wear resistance of nanofill and ormocer composites was comparable or superior to polyacid-modified, microfill and minifill composites.