Clinical Responses Following Periodontal Treatment by Local Drug Delivery

A 4-quadrant, single-blind study was designed to test the efficacy of periodontal disease therapy by local drug delivery. A delivery system made of extruded ethylene vinyl acetate fibers loaded with 25% USP tetracycline hydrochloride was placed and maintained in periodontal pockets for 10 days. The clinical effects of this form of therapy were compared with treatment by periodontal scaling. In addition, the effect of treatment by combined local delivery and scaling was investigated. Untreated quadrants were included as control. Placement of tetracycline-loaded ethylene vinyl acetate fibers into periodontal pockets established a drug concentration of approximately 0.06%. By covering the delivery system with a periodontal dressing, this concentration level was maintained throughout the 10-day therapeutic period. The average tetracycline dose used was 2.4 mg/tooth treated. Following fiber therapy, treated sites improved clinically, as evidenced by a gain in periodontal attachment and a decrease in periodontal pocket depth. The rate of new lesion formation at fiber-treated sites decreased from a pretreatment rate of 26.5% of sites/year to a posttreatment rate of 4.8% of sites/year. Periodontal scaling also produced clinical improvement, as indicated by significant attachment gain, pocket depth reduction and a decreased rate of new lesion formation. However, in no case were clinical results by scaling superior to results by local drug delivery, and by several measures local drug delivery was found to provide a better clinical response. Principal measures by which the clinical response using local drug delivery exceeded that by scaling were in early (3-6 months) attachment gain and in the degree of reduction of new lesion formation. The combination of fiber therapy with scaling reduced the rate of new lesion formation; however, attachment gain appeared delayed in comparison with either scaling alone or fiber therapy alone. This delay in healing was probably due to mechanical interference by the delivery system, which was packed into the periodontal pocket immediately following scaling. Although delayed, the final attachment gain was equal to that of other treatment modalities. Untreated sites exhibited clinical signs of significant improvement which appeared 6 to 12 months after the therapeutic period. Attachment level gains were consistently less than at periodontal sites which had been treated but were nevertheless significant when compared to pretreatment levels. It is suggested that host response mechanisms triggered by periodontal scaling may have been responsible for this effect.