In vitro evaluation of three curettes with edge retention technology after extended use.

This study assessed the edge cutting efficiency of three new curettes with different edge retention technologies after simulated wear in vitro. Three test curettes (two with a titanium nitride coating and one without coating, but made of a cryogenically treated stainless steel alloy) were used to root plane prepared bovine dentin specimens. Nine curettes of each type were used to instrument one dentin sample each. Dentin removal was determined after the first ten strokes and again cumulatively for the strokes 500-510 and 1,000-1,010 by means of atomic absorption spectrophotometry (AAS). The effects of chemical and thermal stress were analysed after repeated disinfection and sterilization of the instruments then followed by a final 10-stroke sequence of dentin removal to determine cutting efficacy. A standard, untreated stainless steel curette was used as a control. Test and control instruments showed no statistical evidence of diminished dentin removal over 1010 strokes. Dentin surface roughness also displayed insignificant differences for all instruments. However, sterilization negatively affected the test and control instruments to an equal degree. Sterilization procedures appear to be an important factor in the dulling of curettes, which affected dentin removal efficacy but not surface roughness.