Abstract
ObjectiveTo develop a novel in vitro periodontal pocket model for evaluating the effect of two different root surface instrumentation modalities on biofilm-epithelial cell interactions.Materials and methodsAn artificial periodontal pocket model was created using an impression material. Dentin discs were prepared and incubated for 3.5 days with a biofilm consisting of 12 bacterial strains. Then, the discs were inserted into the pocket model and instrumented for 10 s or 10 strokes either with ultrasonics (US) or hand instruments (HI). Subsequently, a glass slide coated with epithelial cells was placed in close vicinity to the discs. After incubation of the pocket model in a 5% CO2 atmosphere for 6 h, residual bacteria of the biofilm as well as bacteria adhering to or invaded into epithelial cells were determined using colony-forming unit (cfu) counts and real-time PCR. Further, as a parameter of the pro-inflammatory cell response, interleukin (IL)-8 expression was determined by ELISA.ResultsCompared to untreated control, HI reduced the cfu counts by 0.63 log10 (not significant) and US by 1.78 log10 (p = 0.005) with a significant difference between the treatment modalities favoring US (p = 0.048). By trend, lower detection levels of Tannerella forsythia were detected in the US group compared to HI. Concerning the interaction with epithelial cells, half of the control and the HI samples showed epithelial cells with attaching or invading bacteria, while US displayed bacteria only in two out of eight samples. In addition, US resulted in significantly lower IL-8 secretion by epithelial cells compared to the untreated control. Between HI and controls, no statistically significant difference in IL-8 secretion was found.ConclusionThis newly developed in vitro model revealed in terms of biofilm-epithelial cell interaction after root surface instrumentation that compared to hand curettes, ultrasonic instrumentation appeared to be more effective in removing bacterial biofilm and in decreasing the inflammatory response of epithelium to biofilm.Clinical relevanceUltrasonic instrumentation might be more advantageous to reduce cellular inflammatory response than hand instruments.
Highlights
Periodontitis is an opportunistic infectious disease caused by oral bacteria and their interplay with the intricacy of the host’s immune and inflammatory response
The curettes reduced the counts by 0.63 log10 and US by 1.78 log10 (p = 0.005) compared to the untreated control
Concerning the detection of single bacterial species by PCR 6 h after treatment, it was revealed that P. gingivalis was detected in all control biofilm samples and nearly in Interaction with epithelial cells
Summary
Periodontitis is an opportunistic infectious disease caused by oral bacteria and their interplay with the intricacy of the host’s immune and inflammatory response. Its primary features include the inflammatory-driven destruction of periodontal tissues resulting in periodontal pocketing, bleeding on probing, clinical attachment, and bone loss. The elimination of the biofilm is still the major goal of periodontal therapy (Löe et al 1965; Salvi et al 2012) and includes mechanical instrumentation—either manually or with ultrasonic instruments—of the exposed root surfaces. The consensus is that there is no difference in terms of clinical results between the two treatment modalities [14, 35] but that—in order to achieve an optimum—the combination of hand and ultrasonic instrumentation may be preferred [11]. In vitro models to investigate cell-biofilm interactions and therapeutic modalities are important tools in understanding the pathogenesis of periodontal disease and its therapy. New experimental models could shed light on differences between ultrasonic and hand instrumentation in terms of microbiological and immune-inflammatory parameters
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