A new carbide finishing bur for bracket debonding.
BACKGROUND
The removal of residual bonding resin with rotary instruments after bracket debonding may damage the enamel surface. Conventional carbide burs may scratch the enamel due to the shape and sharpness of their blades.
A new carbide finishing bur with a slightly tapered shape, rounded tip and eight twisted blades has been developed. As a special feature the wedge angle of the blades has been enlarged to ca. 130-135 degrees by means of an oblique ground chamfer (relief angle ca. 0-5 degrees). The transition from head to shaft has been smoothed off with a safety chamfer. Overall, the cutting capacity has been reduced in the enamel, while the bur has remained sufficiently sharp within the adhesive resin.
For prototype testing, incisor brackets were bonded in vitro to 70 human incisors according to the standard clinical technique and removed after 7 days. Residual bonding resin was removed with conventional carbide burs and with gradually modified prototypes of the new finishing instrument respectively. The resulting enamel surfaces were evaluated by scanning electron microscopy. The specimens were then treated with a polishing paste and evaluated again.


RESULTS
Conventional carbide burs remove not only residual bonding resin but also some enamel; scoring may occur. The newly developed finishing bur has been proven by morphological evaluation to be less aggressive in removing residual bonding resin after bracket debonding.
Radlanski
R J
RJ
Department of Experimental Dentistry, Benjamin Franklin University Hospital, Free University, Berlin, Germany. radlanski@ukbf.fu-berlin.de
D017005:Dental Debonding; D003743:Dental Enamel; D003775:Dental Polishing; D006801:Humans; D007180:Incisor; D008855:Microscopy, Electron, Scanning; D016910:Orthodontic Brackets; D013997:Time Factors