Effect of Minocycline Root Detoxification on Human-Periodontal-Ligament-Fibroblast Attachment

Objective: To determine if the application of minocycline HCL may render diseased root surfaces as biocompatible as conventional root instrumentation, and whether its use as an adjunct to root instrumentation has a beneficial effect on human periodontal ligament fibroblast (HPLF) attachment in vitro. Methods: HPLF were isolated and cultured from extracted clinically healthy impacted 3rd molar teeth of two patients rendering two cell lines. Two groups of ten extracted periodontally involved human teeth were collected from different patients. The diseased aspect of the roots were delineated and processed so as to render 4 different test samples with the following modalities applied to each: root planing, root planing treated with minocycline HCL, diseased surface (control), diseased surface treated with minocycline HCL. Each test area were inoculated with a calibrated cell suspension of HPLF and examined under the SEM with respect to the number of cells, cell shape, elongation, perimeter and area and statistically compared. Results: No cells attached to any of the control samples. For cell line 1 non statistically significant differences were found between the different treatment modalities with respect to adhered cells. For cell line 2, no cells attached to any of the control/minocycline samples. On average, 12 cells adhered to the root surfaces in each root planed test area while an average of 3.8 cells adhered to the test areas on the root planed/minocycline treated group which was statistically significant (p=0.0143). Five cells per field were analyzed and compared with respect to shape, elongation, perimeter and area. No significant difference was found. Conclusions: No additional benefit was achieved when a high (100mg.ml^-1) concentration minocycline HCL was applied to diseased or root-planed root surfaces for 30 seconds. Bacteria and endotoxin render root surfaces unfavourable for cell repopulation. Residual minocycline HCL could have had a cytotoxic effect on the HPLF.