Comparison of Various Ultra-Sonication Periods’ Protocols on Dentures' Plaque- A Microbiological Study

Abstract

Aim:The aim of this study is to describe and compare different ultra-sonication protocols used for microbial and candidal sampling, and then test their diagnostic accuracy when correlating microbial loads with a visual plaque score.Methodology: Dentures of consenting subjects were stained and baseline plaque-scores recorded for the fitting and polished surfaces separately. Upper and lower Dentures were sonicated separately in 200 ml distilled-sterile water using one of the following methods (n=10 each): G1: a continuous 30-minutes sonication (Cnt 15 min) cycle, G2: 6 intermittent cycles, (Int 5 min)cycles.G3: a (Cnt 10 min) cycle then 4 (Int 5 min) cycles, G4: a continuous (Cnt 15 min) cycle then 3 (Int 5 min) cycles. G5: a continuous (Cnt 10 min) cycle, then a soaking step (Sk 10 min) then 2 (Int 5 min) cycles. Microbial samples were collected regularly -every 5 minutes-and cultured on two media (Candida selective and non-selective media). Results: G1:The microbial load on non-selective agar began to rise till the third sampling point, then gradually declined with continuous ultrasonications (p>0.05). G2:The microbial load was significantly high in the first then second (Int 5 min) cycles (56.00 ± SE 21.21 @ 5 min, 22.40 ± SE 7.43 @ Int 10 min) (p<0.05). Then it gradually declined in intermittent cycles (p>0.05). G3:The first cycle produced highest numbers (67.40 ± SE 29.02 @ Cnt 10 min) (p<0.05) then gradually decreased in intermittent cycles (p>0.05) till zero. G4:The microbial load was high at the first 15minute cycle (90.20 ± SE 26.72 @ Cnt 15 min) (p<0.05), then sharply decreased in intermittent cycles (p>0.05) till zero. G5:Was similar to G3 till minute 20. The soaking step was contaminated microbiologically, although no ultrasonication was applied (23.8 ± SE 17.03 @ Sk 10 min). Only the continuous 10-minutes ultrasonication protocols (in Gs 1, 2 and 5) had their microbial and candidal counts, on both media, correlate significantly with baseline plaque-scores of the denture as a whole and with each surface separately (Wilcoxon's Signed Ranks Test, p<0.05).