ROOT SURFACE REMOVAL WITH DIAMOND-COATED ULTRASONIC INSTRUMENTS - AN IN-VITRO AND SEM STUDY

ADEQUATE ROOT PREPARATION in periodontal procedures includes the remov al of plaque, calculus, and perhaps contaminated cementum and dentin. The purpose of this study was to evaluate and compare the amount of ro ot surface removal and residual surface texture using similarly shaped regular (US) and both fine (FINDIAM) and medium (MEDDIAM) grit diamon d-coated ultrasonic inserts. Forty-five (45) premolars extracted for o rthodontic reasons were randomly divided into 3 groups of 15 teeth eac h. They were individually mounted in a jig and instrumented with a sta ndardized 500 gram force while they were moved a precise horizontal di stance of 12 mm over a 1.2 second period using specially designed and computer controlled instrumentation. Three measurements were made to t he nearest 0.0005 '' at 3 points along the test area before instrument ation and after 10 and 20 strokes. The mean depth of root structure re moved was US 5.8 +/- 6.6 mu m, FINDIAM 50.1 +/- 14.2 mu m, MEDDIAM 30. 8 +/- 12.1 mu m, after 10 strokes, and US 12.7 +/- 10.9 mu m, FINDIAM 83.3 +/- 20.1 mu m, MEDDIAM 58.7 +/- 17.9 mu m after 20 strokes, respe ctively. All 3 instruments were different from each other (P < 0.001) in the 10 stroke group, while in the 20 stroke group FINDIAM and MEDDI AM were different from US (P < 0.001), but not from each other. Only F INDIAM showed a significant difference between 10 and 20 stroke values for depth of root removal. Modified loss of tooth substance index SEM scores indicated increasingly greater root surface roughness from US to FINDIAM to MEDDIAM. Substantially greater root surface removal and greater residual root surface roughness occurred with diamond-coated u ltrasonic inserts under standardized in vitro conditions. These result s suggest that caution should be used with diamond-coated ultrasonic i nstruments during periodontal root planing procedures.