Date of Award

Fall 2006

Document Type


Degree Name

Master of Science (MS)


Dental Hygiene


Dental Hygiene

Committee Director

Michele L. Darby

Committee Member

Sharon Stull

Committee Member

Carleen M. Lynch

Call Number for Print

Special Collections LD4331.D46 L33 2006


The purpose of this study was to determine the extrinsic tooth stain removing effectiveness of a 90° counter-rotating disposable prophylaxis angle (DPA) with rubber cup as compared to the traditional 360° unirotational DPA with rubber cup. Four randomly assigned groups of cleaned, sterilized, extracted human teeth, artificially stained with coffee, tea, tobacco, and red wine were polished on the buccal and lingual surfaces using one of the two rubber cup DP As under study. Each dependent variable (four different stain types) was tested four times with each prophylaxis angle, using each of the four prophylaxis paste conditions, and three different rpm; therefore, 2 trials x 2 angles x 3 speeds x 4 stains x 4 grits = 192 trials on 96 teeth. For each trial, a rubber cup DPA attached to a handpiece and controlled by an eStylus™ was mounted on a researcher-designed testing apparatus that together controlled handpiece rpm and force of the rubber cup against the tooth; a timer was used to control contact time of the rubber cup against the tooth. Stain removal effectiveness of the DPA was measured, based on a before and after comparison of the tooth with a Bioform Color Ordered Shade Guide after the prophylaxis angle was used with one of three different grits of prophylaxis pastes and a trial using no paste at 1500, 2000, and 3000 rpm. The dental hygienist who scored the teeth was blind to the treatment status of each of the teeth. Four trials for each treatment were conducted and means and standard deviations were computed. Data were analyzed using a three-way analysis of variance at the .05 level.

After 192 trials on stained teeth, the results revealed no statistically significant difference between the two DPAs in extrinsic tooth stain removal. There was a statistically significant interaction among rpm (3,000) of the DPA and the grit abrasivity of the prophylaxis paste suggesting that additional study may be indicated since coarse prophylaxis pastes remove stain more rapidly, but in doing so, can scratch and roughen the tooth enamel. Extrinsic stain removal effectiveness of the two DP As were comparable when using different abrasivity prophylaxis paste and different rpm.


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