The use of locally delivered metronidazole in the treatment of periodontitis. Clinical results

Injectable metronidazole-eluting gelatin-alginate hydrogels for local treatment of periodontitis

Infection of the periodontal pocket presents two major challenges for drug delivery: administration into the periodontal pocket and a high fluid clearance rate in the pocket. The current study aimed to develop and study a novel hydrogel system for delivery of the antibiotic drug metronidazole directly into the periodontal pocket via injection followed by in situ gelation. The natural polymers gelatin and alginate served as basic materials, and their crosslinking using a carbodiimide resulted in a dual hydrogel network. The study focused on the effects of the hydrogel's formulation parameters on the drug release profile and the hydrogel's physical and mechanical properties. A cell viability test was conducted on human fibroblasts. The metronidazole-loaded hydrogels demonstrated a decreasing release rate with time, where most of the drug eluted within 24 h. These hydrogels exhibited fibroblast viability of at least 75% after 24 and 48 h, indicating that they are highly biocompatible. Although the alginate concentration used in this study was relatively low, it had a strong effect on the physical as well as the mechanical properties of the hydrogel. An increase in the alginate concentration increased the crosslinking rate and enabled enhanced entanglement of the 3D structure, resulting in a decrease in the gelation time (less than 10 s) and swelling degree, which are both desired for the studied periodontal application. Increasing the gelatin concentration without changing the crosslinker concentration resulted in significant changes in the physical properties and slight changes in the mechanical properties. Metronidazole incorporation slightly decreased the hydrophilicity of the hydrogel and therefore also its viscosity, and affected the sealing ability and the tensile and compression moduli. The developed hydrogels exhibited controllable mechanical and physical properties, can target a wide range of conditions, and are therefore of high significance in the field of periodontal treatment.

Efficacy of subgingivally applied minocycline in the treatment of chronic periodontitis

BACKGROUND

The use of adjunctive minocycline with mechanical debridement in treating periodontitis has been widely studied using different methods. However, the results from these studies are equivocal.

OBJECTIVE

The purpose of this study was to clarify the efficacy of the adjunctive use of subgingival minocycline application plus scaling/root planing as compared with the results of one episode of scaling/root planing in the treatment of chronic periodontitis.

METHODS

Fifteen patients were enrolled in this split-mouth clinical trial. Probing depth, clinical attachment loss, gingival index, and bleeding on probing were evaluated at the baseline before scaling/root planing and 6, 10, 14, and 18 weeks later according to a single-blind protocol. The amount of interleukin-1beta (interleukin-1beta pg/site) at each lesion was also simultaneously measured in gingival crevicular fluid in a parallel comparison design. After full-mouth baseline measurements and scaling/root planing, 78 lesions with a residual mean probing depth of 5 mm at anterior teeth were selected and equally distributed in either right or left sites based on a split-mouth symmetrical design and randomly assigned to one of two treatment groups (with or without minocycline administration, n = 39 for each group).

RESULTS

Probing depth significantly decreased from the baseline (week 0) to week 6 after scaling/root planing (p < 0.05) in both groups, but there was no statistically significant difference between the two groups (p > 0.05). However, at weeks 10, 14, and 18, the experimental group showed significantly greater improvement in pocket reduction than the control group (p < 0.05). Similarly, both groups also showed significant decreases in gingival index scores from weeks 0-6 (p < 0.05), but gingival index reductions at weeks 10, 14, and 18 were statistically significant in favor of the experimental group (p < 0.05). The experimental group had more attachment gain than the control group at weeks 14 and 18 (p < 0.05). Values of interleukin-1beta (pg/site) at the experimental sites were significantly reduced at weeks 10, 14, and 18, as compared to values at control sites (p < 0.01). Finally, the incidence of bleeding on probing showed no differences between the two groups for any time interval (p > 0.05).

CONCLUSIONS

In this 18-week clinical trial, the results suggested that scaling/root planing with adjunctive subgingival administration of minocycline ointment has a significantly better and prolonged effect compared to scaling/root planing alone on the reduction of probing depth, clinical attachment loss, gingival index, and interleukin-1beta content, but not on bleeding on probing.

Microflora cultivable from minocycline strips placed in persisting periodontal pockets

OBJECTIVE

The microflora that develops on minocycline strips, used as an adjunct in non-surgical periodontal therapy was studied.

DESIGN AND METHODS

Minocycline (1.4 mg in polycaprolactone vehicle) and control strips were applied into all residual pockets (PD > or = 5mm, > or =2 pockets/subject) of patients with chronic periodontitis 1 month after a course of non-surgical periodontal therapy. Strips were inserted and retained for 3 days, changed to new strips for 3 more days and then removed. Strips were recovered from 14 (eight test, six control) of the 34 participants at day 0 (strip inserted, left for 30 s, removed), days 3 and 6, for (i) anaerobic culture, (ii) coliforms culture, using MacConkey agar, (iii) yeast culture, using Sabouraud's dextrose agar.

RESULTS

The mean anaerobic cfu/strip (x10(5); control/test) were 2/6, 24/2, 11/2 at days 0, 3 and 6, respectively (P > 0.05). The corresponding mean proportion of Gram-negative rods and fusiforms were 27%/21%, 27%/15% and 55%/8%. The proportions of Gram-negative rods on test strips by day 6 were significantly reduced (P < 0.05). A significantly increased prevalence of Streptococcus mitis biovar 1 was found on spent test strips (control versus test; 0% versus 38%, Fisher exact test, P = 0.01). Coliform prevalence at days 0, 3 and 6 on control/test strips were 0/13%, 50%/38% and 50%/13%. Yeasts were occasionally isolated.

CONCLUSIONS

The findings indicated that the minocycline strips but not the control strip supported a microbial colonisation compatible with periodontal health by day 6.

Meta-Analysis of Local Metronidazole in the Treatment of Chronic Periodontitis

BACKGROUND

Meta-analysis was used to assess the effectiveness of local delivery of metronidazole alone or as an adjunct to mechanical therapy in patients with chronic periodontitis.

METHODS

Studies were identified using MEDLINE and other sources. Meta-analyses were performed on the basis of probing depth (PD) at baseline and experimental and control regimens studied (i.e., metronidazole plus scaling and root planing [SRP] versus SRP and metronidazole versus SRP); the effect of local metronidazole on PD and attachment level (AL) was evaluated for follow-up times of 4, 8, 12, 24, and 36 weeks. The DerSimonian & Laird random effects model was used.

RESULTS

Twelve studies that met inclusion criteria were entered into the meta-analysis. A significant mean reduction in PD for the combined metronidazole and SRP was observed in all comparisons with initial PD > or = 4 mm (0.38 mm at 8 weeks to 0.6 mm at 12 weeks); whereas, with initial PD > or = 5 mm a significant mean reduction was observed from 12 weeks (0.29 to 0.48 mm at 24 and 36 weeks, respectively). Meta-analysis could be performed for AL to test the effectiveness of metronidazole as an adjunct to SRP and a significant AL improvement was found in all analyses (0.2 mm at 4 weeks to 0.29 mm at 24 and 36 weeks). Meta-analyses were performed including two to four studies.

CONCLUSION

Our results demonstrated the effectiveness of metronidazole as an adjunct to SRP in the treatment of chronic adult periodontitis, but clinical significance and dissemination of antibiotics should be taken into account in the evaluation of metronidazole as an alternative to SRP.

Probing depth changes following 2 years of periodontal maintenance therapy including adjunctive controlled release of chlorhexidine

BACKGROUND

Multicenter clinical trials have established that the adjunctive use of the subgingival controlled release of chlorhexidine, (CHX chip), significantly reduces probing depth (PD), improves clinical attachment levels, and reduces bleeding on probing compared to scaling and root planing (SRP) alone for periods of up to 9 months. The present report is based on a phase IV clinical trial to examine the adjunctive use of the CHX chip for routine periodontal maintenance therapy (RPMT) over 2 years.

METHODS

Eight hundred thirty-five (835) patients were recruited into the study. At baseline a CHX chip was placed in pocket sites with PD > or = 5 mm. The patients were scheduled to receive RPMT at 3-month intervals with repeated CHX chip placement at sites where the PD remained > or = 5 mm. Patients who did not attend the 24-month recall visit or who failed to attend 2 consecutive time frame examinations were excluded from the analyses.

RESULTS

The 595 patients included showed a continuous decrease in PD over 2 years of 0.95 mm. After 2 years, 23.2% of patients had at least 2 pockets showing a reduction in PD of 2 mm or more and 58.9% of the sites had been reduced to a PD of < 5 mm. Only 2.9% (n = 57) of the sites showed an increase in PD of > or = 2 mm. Adverse events were mild to moderate in nature and resolved spontaneously without medication.

CONCLUSION

The results of this Phase IV or follow-up trial indicate that the adjunctive use of the CHX chip is a clinically safe and effective treatment option for long-term management of chronic periodontitis.

Controlled and targeted drug delivery strategies towards intraperiodontal pocket diseases

Advances in the understanding of the aetiology, epidemiology, pathogenesis and microbiology of periodontal pocket flora have revolutionized the strategies for the management of intraperiodontal pocket diseases. Intra-pocket, sustained release, drug delivery devices have been shown to be clinically effective in the treatment of periodontal infections. Several degradable and non-degradable devices are under investigation for the delivery of antimicrobial agents into the periodontal pocket including non-biodegradable fibres, films (biodegradable and non-biodegradable), bio-absorbable dental materials, biodegradable gels/ointments, injectables and microcapsules. With the realization that pocket bacteria accumulate as biofilms, studies are now being directed towards eliminating/killing biofilm concentrations rather than their planktonic (fluid phase) counterparts. Intraperiodontal pocket drug delivery has emerged as a novel paradigm for the future research. Similarly, bioadhesive delivery systems are explored that could significantly improve oral therapeutics for periodontal disease and mucosal lesions. A strategy is to target a wide range of molecular mediators of tissue destruction and hence arrest periodontal disease progression. Research into regenerating periodontal structures lost as a result of disease has also shown substantial progress in the last 25 years.