Laser and scanning electron microscopy evaluation of residual microislands of calculus.

BACKGROUND: Recent studies suggest a role for microscopic crystalline particles of residual dental calculus in the pathogenesis of periodontitis. The purpose of this ex vivo study was to compare the effectiveness of scaling and root planing (SRP) alone versus SRP combined with 24% ethylenediamine-tetra acetic acid (EDTA) gel in removing calculus from extracted teeth and to determine the optimal length of time for application of the EDTA. METHODS: Specimens consisted of 32 extracted teeth with heavy root calculus. A 4-mm diameter site was prepared on the root surface of each tooth which then underwent SRP. EDTA was applied to four timed groups: 30 s; 60 s; 120 s; and 180 s. Photomicrographs were taken at 40x magnification using white light (WL) and laser fluorescence (LF). Photomicrographs were analyzed using ImageJ. Specimens were also evaluated with scanning electron microscopy (SEM). RESULTS: The mean area of residual calculus after SRP was 45%-53% (45.6% +/- 19.6% WL, 53.8% +/- 19.7% LF). Burnishing with EDTA for one minute following SRP reduced calculus to only 14%-18% (13.9% +/- 12.5% LF, 18.2% +/- 11.1% WL). Use of EDTA for greater than 1 min showed no further calculus removal. SEM revealed the surface of remaining calculus was altered by burnishing with EDTA. CONCLUSION: SRP alone or SRP + 24% EDTA gel failed to remove all calculus. SRP alone removed >60% of calculus from root surfaces. Adjunctive use of 24% EDTA gel burnished on the root surface removed most of the calculus residual after SRP. Calculus remaining after EDTA burnishing exhibited a significantly altered morphologic appearance.