by Lynn H. Slim RDH, BSDH, MSDH
Imagine that you are a clinical instructor in an accredited dental hygiene program. One of your most curious students challenges you on the subject of subgingival calculus removal. This curious skeptic, who is looking to support or reject his idea, asks: “Which is the more effective means of reducing pocket inflammation — calculus or biofilm removal or both?”
Being a curious instructor, you challenge yourself and the student by answering, “Let's find out!” I'll play the role of an instructor and guide the student to find an answer.
I immediately turn to the periodontal literature, but I also talk to my peers. In this instance, the online periodontal therapist Yahoo group (www.yahoogroups.com/group/periotherapist) has discussed this particular issue in depth. A few members of the group are experienced dental endoscope users who insist that increased inflammation (redness of the pocket wall) is almost always associated with subgingival calculus, and the calculus is covered with thick biofilm.
My student and I search PubMed (www.ncbi.nim.nih.gov/pubmed/) together. It just so happens that there is a newly published pilot study (with limitations because pilot studies have a small number of subjects) that confirms what some clinicians have already observed. Wilson et al. gathered data on 26 subjects with moderate and severe chronic periodontitis and endoscopically examined sites with subgingival calculus and biofilm.1 Data gathered from the use of the dental endoscope established a statistically significant relationship between subgingival calculus, subgingival biofilm, and subgingival inflammation. The combination of subgingival calculus with a biofilm coating was often associated with inflammation when compared to calculus or biofilm alone. The researchers hypothesized that calculus covered with biofilm enhances the inflammatory response.
After an exhaustive search, the most comprehensive source we find is a review of the literature on the effects of nonsurgical therapy on hard and soft tissues. Multiple sources confirm that conventional mechanical debridement cannot completely eradicate all periodontal pathogens from the pocket environment, especially those that live in inaccessible areas like furcations, grooves, concavities, deep pockets, dentinal tubules, and other intraoral sites.
Even so, non-surgical therapy that focuses on calculus removal and biofilm disruption and suppression is an efficient and cost effective way of reducing gingival inflammation, probing pocket depth, and achieving gains in clinical attachment levels. The goal of mechanical debridement, which is often combined with antimicrobial agents to further suppress pathogens, is resolution of inflammatory changes so that the host is not overwhelmed and does not respond inappropriately. Many patients with chronic periodontitis can be managed with nonsurgical therapy alone.2
I quickly realize that the question we started with leads to more questions (no surprise there) with no simple answers. Initial probing depth, root anatomy, instrument design, operator expertise, environmental factors such as quality of oral hygiene efforts, risk factors such as a host's inappropriate immuno/inflammatory response, smoking, or poorly controlled diabetes are additional factors that impact inflammation.
The biofilm nature of dental plaque is, however, changing our thinking about cleaning and disinfecting pockets, and the pilot study by Wilson et al. provides an opportunity to re-think our instrumentation strategy. Why is it that clinicians who use dental endoscopes routinely find an inflamed pocket wall adjacent to subgingival calculus covered with biofilm? Here's my theory, and my reading about biofilm has sparked my curiosity: Calculus irregularities provide an opportunity for thicker biofilm that create an anaerobic environment and perfect home for periodontal pathogens. The student and I agreed about removing as much biofilm and calculus as possible from diseased root surfaces in susceptible individuals.
1. Wilson TG, Harrel SK, Nunn ME, et al. The relationship between the presence of tooth-borne subgingival pockets and inflammation found with a dental endoscope. J Periodontol 2008; 79(11): 2029-2035.
2. Adriaens PA, Adriaens LM. The effects of nonsurgical periodontal therapy on hard and soft tissues. J Periodontol 2000 2004: 34: 121-145.