Effect of finishing instrumentation on the marginal integrity of resin-based composite restorations.
OBJECTIVE
This study evaluated the effect of the use of different finishing instruments on the marginal integrity of resin composite restorations.


METHODS
Bovine incisors (N = 75) embedded in epoxy resin had the facial enamel ground and polished to 1200-grit. A standardized cavity (3 x 3 mm, 2 mm deep) was prepared on each specimen and restored with a 2-step total-etch adhesive (Single Bond, 3M ESPE, St. Paul, MN, USA) and a hybrid resin composite (Filtek Z250, 3M ESPE) in a single increment. The restorations were mechanically polished to 1200-grit. Specimens were randomized into different groups (N = 5) according to finishing technique: positive control (1200-grit paper), negative control (regular-grit diamond), fine cross-cut laminated burs, straight-cut laminated burs, spiral-cut laminated burs, and finishing diamonds. The straight-cut burs, spiral-cut burs, and finishing diamonds were tested individually as fine, extra-fine, and ultra-fine, as well as sequentially as a series. A high-speed, water-cooled handpiece under standardized pressure (0.5 N) and time (40 seconds) was used for all finishing procedures. Specimens were processed for scanning electron microscope, and margin gaps were systematically measured. Data were analyzed with one-way analysis of variance and Duncan test.


RESULTS
The negative control specimens (course diamond) presented the largest gaps, whereas the positive control specimens (mechanically polished) generated the smallest gaps. No statistically significant difference was noted between the finishing diamonds and the positive control. The negative control exhibited significantly larger gaps when compared with the other finishing instruments. Intermediate results were observed for cross-cut, straight-cut, and spiral-cut laminated burs. Fine, extra-fine and ultra-fine finishing diamonds generated smaller gaps compared with laminated burs, but the differences were not always statistically significant.


CONCLUSIONS
Fine, extra-fine and ultra-fine finishing diamonds used to finish composite restorations generated better marginal integrity when compared with carbides and regular-grit diamonds. CLINICAL SIGNIFICANCE When finishing composite restorations, finishing diamond burs result in better composite margins than carbide laminated burs.
Maresca
Cristina
C
Department of Operative Dentistry, University of North Carolina, School of Dentistry, Chapel Hill, NC, USA.
Pimenta
Luiz A F
LA
Heymann
Harald O
HO
Ziemiecki
Thomas L
TL
Ritter
André V
AV
D000818:Animals; D017438:Bisphenol A-Glycidyl Methacrylate; D002417:Cattle; D003188:Composite Resins; D001840:Dental Bonding; D003754:Dental High-Speed Equipment; D018772:Dental Marginal Adaptation; D003775:Dental Polishing / Q000295:instrumentation*; D003793:Dental Restoration, Permanent / Q000379:methods*; D018130:Diamond; D008855:Microscopy, Electron, Scanning; D011897:Random Allocation; D019279:Resin Cements; D017973:Tungsten Compounds
D003188:Composite Resins; C444701:Filtek Z250; D019279:Resin Cements; D017973:Tungsten Compounds; C115612:single bond; C002802:tungsten carbide; D017438:Bisphenol A-Glycidyl Methacrylate; D018130:Diamond