Adjunctive systemic and locally delivered metronidazole in the treatment of periodontitis: a controlled clinical study.

Objective: To compare clinical and microbiological responses following non-surgical treatment of moderate to advanced adult periodontitis using subgingival scaling with and without adjunctive topical or systemic metronidazole.

Design: A single blind randomised clinical trial of 90 subjects, stratified for periodontitis disease severity and smoking status, divided into three treatment groups: 1. Subgingival scaling using ultrasonic scalers and local anaesthesia; 2. Subgingival scaling using ultrasonic scalers and local anaesthesia plus seven days of systemic metronidazole (200 mg tds); 3. Subgingival scaling using ultrasonic scalers and local anaesthesia plus two applications of 25% metronidazole gel one week apart in all sites with probing depths more than 4 mm. Evaluations were made before treatment, and 8 weeks and 24 weeks post treatment.

Main Outcome Measures: Probing depths, probing attachment levels and bleeding on probing were measured using a Florida probe. Bacterial morphotypes were evaluated with darkfield microscopy. Results were analysed for all sites with baseline probing depths equal to or greater than Florida probe recordings of 4.6 mm using analysis of variance.

Results: 84 subjects completed the trial and the three treatment groups did not differ at baseline for any clinical parameter. Mean probing depths were reduced following treatment by greater than 1.6 mm (Group 1 = 1.68 mm, Group 2 = 1.62 mm, Group 3 = 1.74 mm at six months post treatment) but no significant differences were detected between treatment groups at any time point. Similarly, no significant differences were detectable between treatments for changes in mean probing attachment levels, bleeding on probing, plaque scores or proportions of bacterial morphotypes.

Conclusions: This study does not support the routine use of adjunctive metronidazole in the non-surgical treatment of periodontitis.