A histopathologic investigation on the effects of electrical stimulation on periodontal tissue regeneration in experimental bony defects in dogs.

BACKGROUND: One endpoint of periodontal therapy is to regenerate the structure lost due to periodontal disease. In the periodontium, gingival epithelium is regenerated by oral epithelium. Underlying connective tissue, periodontal ligament, bone, and cementum are derived from connective tissue. Primitive connective tissue cells may develop into osteoblasts and cementoblasts, which form bone and cementum. Several procedural advances may support these regenerations; however, the regeneration of alveolar bone does not always occur. Therefore, bone stimulating factors are a main topic for periodontal reconstructive research. The present study was designed to examine histopathologically whether the application of an electrical field could demonstrate enhanced alveolar and cementum regeneration and modify tissue factors. METHODS: Seven beagle dogs were used for this experiment. Mandibular left and right sides served as control and experimental sides, respectively, and 4-walled intrabony defects were created bilaterally between the third and fourth premolars. The experimental side was treated with a capacitively coupled electrical field (CCEF) (sinusoidal wave, 60 kHz, and 5 V peak-to-peak), applied for 14 hours per day. The following measurements were performed on the microphotographs: 1) the distance from the cemento-enamel junction to the apical notch (CEJ-AN) and from the crest of newly formed bone (alveolar ridge) to the apical notch (AR-AN); 2) the thickness of new cementum in the apical notch region; and 3) the length of junctional epithelium. The following histopathologic parameters were assessed by a semiquantitative subjective method: 1) inflammatory cell infiltration (ICI); 2) cellular activity of the periodontal ligament; 3) number and morphology of osteoclasts; 4) resorption lacunae; and 5) osteoblastic activity. RESULTS: The results showed that the quantity of new bone fill and the mean value of the thickness of the cementum were significantly higher for the experimental side (P < 0.01). The location of the base of the pocket was positioned more coronally with respect to the apical point of the coronal notch in the experimental side (statistically significant P < 0.01). The length of the junctional epithelium and the number of osteoclasts were higher in the stimulated side than the coronal side; these findings were also statistically significant (P < 0.01). The comparison of the electrically stimulated versus non-stimulated mandibles with the semiquantitative subjective method demonstrated statistically significant differences in defined histopathologic parameters, except for osteoclast morphologies (P > 0.05). CONCLUSIONS: This study demonstrated that the CCEF method has the potential to produce reconstructive effects and bone deposits. Further investigations with respect to the theoretical determination of local field parameters of the periodontal tissue complex, such as permittivity, conductivity, strength of the field electrical stimulation applied to the periodontal field current density, wavelength, and signal frequency appropriate for this field, should be undertaken. Using different electromotive forces alone or in combination with bone graft materials, guided tissue regeneration techniques, and dental implants may achieve a new dimension in periodontal therapy in the near future.

A histopathological investigation on the effect of systemic administration of the bisphosphonate alendronate on resorptive phase following mucoperiosteal flap surgery in the rat mandible.

BACKGROUND: The present study was designed to assess histopathologically whether the systemic administration of aminobisphosphonate (alendronate), 0.5 mg/kg body weight, is effective in preventing alveolar bone resorption following mucoperiosteal flap surgery, and whether alendronate modulates tissue factors. METHODS: The effect of alendronate on bone resorption was evaluated in mucoperiosteal flaps used as a resorptive model. The animals were given subcutaneous injections of either saline (control group) or 0.5 mg/kg of alendronate (experimental group). The alendronate or saline was administered subcutaneously 1 week prior to surgery, immediately prior to surgery, and 1 week after surgery. The parameters determined with a semiquantitative subjective method for histopathological evaluation were as follows: inflammatory cell infiltration (ICI) of adjacent periodontal tissue, degree of fibrosis and collagen bundle formation, number and morphology of osteoclasts of the alveolar bone and interdental septum, resorption lacunae (osteoclast surfaces), and osteoblastic activity (forming surfaces). RESULTS: There were no statistically significant differences between the saline and alendronate groups with regard to inflammatory cell infiltration, number of osteoclasts, and osteoblastic activity. Fibrosis and collagen bundle formation, osteoclast morphologies, and resorption lacunae formation were significantly different between the two groups, in favor of the alendronate group. CONCLUSIONS: The systemic administration of 0.5 mg/kg alendronate was effective in preventing alveolar bone loss and in modulating tissue factors. These findings indicate that alendronate would be a valuable addition to the therapeutic armamentarium available for the treatment of periodontal diseases, either alone or in combination with regenerative components such as anti-inflammatory drugs, bone graft materials, and guided tissue regeneration techniques, and even with dental implants.

Clinical comparison of cellulose and expanded polytetrafluoroethylene membranes in the treatment of class II furcations in mandibular molars with 6-month re-entry / Comparação clínica de celulose e membranas de politetrafluoroetileno em tratamento de furcas classe II em molares mandibulares com 6 meses de reentrada

The present study compared two barrier membranes, ePTFE and cellulose, used to treat Class II furcations in mandibular molars. Fifteen patients with no history of systemic diseases and presenting matched pair defects were selected. The following soft tissue measurements were taken at baseline (after the hygienic phase), and 6 months after surgery: gingival recession, probing depth, clinical attachment level, and width of keratinized tissue. At the time of membrane placement, and 6 months later (re-entry), the following hard tissue parameters were recorded: cemento-enamel junction (CEJ) to alveolar crest, CEJ to base of osseous defect, alveolar crest to base of osseous defect, and horizontal defect depth. According to the surgical protocol, the ePTFE membranes were completely covered by the flaps (subgingival placement), whereas the cellulose membranes extended 1 mm coronal to the gingival margin (supragingival placement)...