ABSTRACT Objectives In vitro models provide valuable insights into treatment options and their effectiveness prior to and alongside clinical evaluation. Such models should be standardized, reproducible, and closely reflect the clinical situation. This study aimed to investigate the removal of subgingival biofilm and calculus by instrumentation, which is vital in the successful treatment of periodontitis. The approach was to (i) develop an in vitro model based on biofilm and calculus formation and (ii) assess it by hand and ultrasonic instrumentation, while (iii) measuring the forces applied in an innovative periodontal defect model. Materials and Methods A multi‐species mixture consisting of 11 bacterial strains was used to form 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. Instrumentation forces were recorded, and the remaining biofilm or biofilm/calculus was analyzed for bacterial colony‐forming unit (cfu) counts and calcium levels after instrumentation. Results 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 than hand instrumentation in reducing cfu counts 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 and biofilm/calculus groups compared to the respective ultrasonic groups. Conclusions The model enabled an initial reproducible calculus formation and evaluation of different instrumentation modalities, including the forces applied. The results favored the ultrasonic instrumentation due to its superior removal of biofilm and calculus and lower lateral forces. The presented biofilm/calculus model offers a new in vitro approach for comparing different instrumentation modalities.
Jungbauer et al. (Wed,) studied this question.