Subantimicrobial Dose Doxycycline in the Treatment of Periodontal Disease
Canadian College of Dental Health
Periodontal disease is an infectious disease and as any other inflammation, the best approach for treatment are antimicrobial or antibiotics as an adjunct to a conventional periodontal scaling and root planing (SRP). Studies up do date has shown that standard antibiotic therapy of 200 to 300 mg is not effective due to immediate repopulation of bacteria flora in oral cavity and increased chance for resistance. Since the host response is the main issue in destruction of periodontal tissue in periodontal disease, the most effective antimicrobial approach was found to be an administration of subantimicrobial dose of Doxycycline of 20 mg. bid, for a period not shorter than three months that help to suppress host response and decrease even more pocket depths after SRP, but has no effects on present bacterial flora thus removing the possibility of development of resistance to antimicrobials.
The aetiology of chronic periodontitis involves complex host-parasite interactions modified by environmental and genetic factors.
Periodontal destruction with Matrix Metalloproteinases (MMPs).
MMPs are peptidases that act together as degrading agents of periodontal connective tissue and proteins including collagen. Study done in 1998 by Golub LM, Lee H-M and Ryan ME (5) has shown that prominent amongst the MMPs that promote the breakdown of periodontal supporting structures are neutrophil-derived MMP-8 (collagenase), MMP-9 (gelatinase), and MMP-13 (collagenase which is bone derived).
Effects of conventional antimicrobial treatment
Traditional nonsurgical treatments such as scaling and root planning (SRP) also known as periodontal debridement mechanically reduce the bacterial load in the oral cavity by removing dental plaque as a major cause of periodontal inflammation, calculus as a contributory cause, and bacterial endotoxins from the root surface of the teeth.
The novel treatment approach: Tetracyclines as host-modulatory agents and role of subantimicrobial doses of doxycycline (SDD) in the treatment of periodontal disease
Along with their bacteriostatic capabilities, tetracyclines are also known as inhibitors of tissue-destructive MMPs in crevicular fluid including MMP-8, MMP-9 and MMP-13, whereas doxycycline (a semisynthetic tetracycline) has been shown to be the most potent inhibitor of MMP activity. Study done in 1997 by Golub LM, Lee H-M and Greenwald RA (4) acknowledged for the first time in human studies, that subantimicrobial doses doxycycline (SDD), have reduced the elevated levels of specific collagenase (MMP-8) and bone type collagen degradation fragment (MMP-13) in gingival crevicular fluid (GCF), as compared with patients receiving placebo (p<0.05).
Do subantimicrobial doses of doxycycline (SDD) have an antibacterial effect on the subgingival flora?
Multiples studies have failed to identify an antimicrobial effect of SDD on the subgingival microflora. Walker C, Thomas J. and Nango S. In their study done in 2000 (10) , for instance, found no microbial differences between the study groups, for coccoid forms, motile and non-motile rods, fusiforms and filamentous rods. Only spirochetes were found to be lower in the SDD group as compared to the placebo group.
What are the effects of subantimicrobial doses of doxycycline (SDD) treatment in conjunction with scaling and root planning (SRP) on patients with chronic periodontitis?
The most extensive study was published by Caton JG, Ciancio SG and Blieden in 2000 (2). This study included 190 patients in five dental centers in the United States. All patients received scaling and root planning (SRP) and than they were assigned to receive 20 mg doxycycline or placebo bid. Baseline measurements such as probing depth (PD), clinical attachment level (CAL), bleeding on probing (BOP) was monitored every three months up to nine months. The results of this study were significantly reductions in probing depths and increases in clinical attachment levels with adjunctive doxycycline therapy in conjunction with root planning.
What should be the minimal duration and dosage of subantimicrobial doses of doxycycline (SDD) therapy?
In a unique study, Golub LM, McNamara TF and Ryan ME in 2001 (6), were evaluated 51 patients up to 36 weeks. After supra and subgingival scaling and prophylaxis, the patients were divided in 5 groups:
In all three groups receiving SDD a reduction in GCF collagenases and gain of CAL was observed as compared to the placebo groups.
To date, no study has examined the effect of SDD treatment for a period longer than nine months.
How beneficial is the treatment with subantimicrobial doses of doxycycline (SDD) on smokers
In the study done by Preshaw PM, Bradshaw MH and Hefti AF in 2003 (8), was reported that SDD treatment in conjunction with SRP, for a period of nine months, showed better results as compared to the placebo in both smokers and non-smokers groups. Interestingly in this study is the finding that smokers study group with SDD accomplished more PD reduction and CAL gain when compared to the non-smokers placebo group. The explanation lies in bad effects of smoking to periodontal tissues making their host response weaker, thus reducing the amount of destruction of periodontal tissues.
The novel approach in antimicrobial therapy as adjunct to conventional SRP using subantimicrobial doses of doxycycline in an amount of 20 milligrams twice per day for a period not less than three months has been shown very beneficial and effective in reduction of pocket depths and clinical attachment loss, and is highly recommended as a tool for Dental Hygienists in ongoing battle against periodontal disease.