The Treatment of Periodontal Diseases. A Randomized, Blinded, Five Years Follow-up, Four-arm, Placebo Controlled Clinical Intervention Trial

This is a clinical research project in the odontologic special field; periodontology. Periodontitis affects > 50% of all persons over 40 years-of-age, whereof 5 - 10% is prone to loose one or more teeth due to the disease. In Norway, less than 40% of the periodontal treatment costs are carried (refunded) by the public. The proportion of personal expenses vs. public spending depends on how serious the periodontitis is diagnosed, and on the individual treatment provided. In addition comes expenses connected to the restoration of the dentition when teeth are lost as a consequence of the disease, and therefore the social, personal and economical consequence of serious tooth loss can be devastating to the patient.

Background and established knowledge Periodontal disease is a family of bacterial infections characterized by the destruction of periodontal supporting tissues. The bacterial flora at the diseased sites is complex, counting > 500 different species in the subgingival dental plaque. Three main hypotheses exist in explaining the infectious nature of periodontal disease; the non-specific infection hypothesis (Theilade 1986), the specific infection hypothesis (Slots and Rams 1991, Loesche 1992) and the ecological plaque hypothesis (Marsh 1994).

Dental biofilm is an important factor in periodontal health and disease (review: Socransky and Haffajee 2002), and is a more correct wording for the term plaque. Most biofilms are biologically compatible with health, as their formation is influenced by the selective pressure of the host organism. It is also of great practical interest that bacteria organized in biofilms are highly resistant to antibiotics as compared to those in a planktonic state. In the development of dental biofilms, the host receives bacteria with different properties from close relatives and others, depending on the living conditions (Tinoco et al 1998). If there are pathogenic bacteria among these, the possibility for developing periodontitis increases (Preus et al 1995). This indicates that periodontal treatment must be aimed at breaking the ecology of the pathogenic biofilm, and then increase the organisms' ability to perform its selective pressure, following treatment, in the making of a new biofilm low of, or free from pathogenic microorganisms.

Traditional Treatment strategies have so far aimed at preventing or retarding the progression of the disease through mechanical, non-specific treatment, and we have succeeded to a certain extent.

Scaling and root planing (SRP) is the standard treatment, aiming to mechanically reduce the number of bacteria present on the affected root surfaces. Representing a non-specific form of treatment to a non-specific infection, it has proven effective in most cases and short follow ups(Hill et al 1981, Pihlstrøm et al 1983, Lindhe et al 1984, Becker et al 1990, Kaldahl et al 1993). However, recurrence rate is fairly high, suggesting that these diseases are life-long traits. Also, a small - still significant - group of patients shows remaining inflammation and continuous destruction of periodontal support despite adequate oral hygiene and proper mechanical treatment (Lang et al 1986, Greenstein & Caton 1990, Walker et al 1993, Bragd et al 1987, Renvert et al 1990, Haffajee et al 1991, Grossi et al 1994, Slots and Rams 1991, Socransky and Haffajee 1992).