In-vitro assessment of dental biofilm and calculus formation and debridement by hand and ultrasonic instrumentation

The removal of subgingival biofilm and calculus is vital in the successful treatment of periodontitis, which can primarily be achieved using hand and/or ultrasonic scalers. The present study aimed to compare hand instrumentation with ultrasonic instrumentation in a biofilm-calculus model.A multi-species mixture consisting of 11 bacterial strains was used to generate an initial calculus over 14 days. Inserts carrying human dentin specimens, either with biofilm or with a combination of biofilm and calculus, were placed in a periodontal pocket model equipped with a multi-axis force sensor, followed by treatment with hand or ultrasonic instrumentation. During instrumentation, the forces applied were recorded, and the remaining biofilm or biofilm/calculus was analyzed after instrumentation for bacterial colony-forming unit (CFU) counts and calcium levels.The results revealed that the cfu counts and calcium levels in the biofilm/calculus group were higher compared to the respective biofilm controls. Ultrasonic instrumentation was more effective in reducing cfu counts than hand instrumentation in both the biofilm and biofilm/calculus groups. Furthermore, both hand and ultrasonic instrumentation reduced calcium levels in the biofilm/calculus groups. The peak forces Fy in the hand instrumentation groups were significantly higher in both the biofilm only and biofilm/calculus groups compared to the respective ultrasonic groups.The model enabled an initial reproducible calculus formation and evaluation of different instrumentation modalities, including the measurement of the forces applied. When comparing hand and ultrasonic instrumentation, the results favored the ultrasonic scaler due to its superior removal of biofilm and calculus and lower lateral forces.