These results suggest that cell carrier membranes could affect RGF morphology and thus alter gingival tissue healing following GTR.

Tobacco smoking is considered a major risk factor for the development and progression of periodontal diseases (Haber, J. and Wattles, J. (1994). J. Periodontol., 64, 16-23). The purpose of this study was to determine the effects of nicotine on rat gingival fibroblasts (RGF) cultured in vitro. After ether anesthesia, rat gingival tissues were obtained from the attached gingiva of a Wistar rat. Small fragments of gingiva were maintained in culture in Petri dishes. Fibroblasts developing from these explants were collected to obtain monolayer cultures. After the fourth passage (T4), cells were supplemented with nicotine at various concentrations. Control and treated cells were examined under phase contrast or transmission electron microscopy. They were compared as regards their DNA content, mitochondrial activity, collagen and protein synthesis, and cell death by apoptosis or necrosis. Nicotine from 0.05 microM to 1 mM did not affect the DNA content or protein and collagen synthesis. At concentrations between 3 and 5 mM, growth was significantly diminished and the survival rate reduced. Ultrastructural analysis revealed dilated mitochondria and vacuolization in treated cells, suggestive of necrosis, but increased apoptosis was also revealed by cytometry. On the basis of this in vitro study, it appears that tobacco, through its component nicotine, may directly affect various functions of RGF.

Several grafting techniques and guided tissue regeneration techniques (GTR) have been well-developed in periodontal surgery. However, these techniques could induce pain and side effects, such as a gingival recession during the healing period following the therapy. The graft of a small autologous connective tissue, using non-invasive surgical techniques could yield several benefits for the patients. Our preliminary study explores the feasibility of collecting healthy gingival tissues, culturing them in vitro to amplify rat gingival fibroblasts (RGF) and inoculating the obtained cells into autologous rat gingival tissues in vivo. Gingival tissues samples were cultured as explants as described by Freshney et al. and Adolphe. Confluent cells surrounding explants were detached after 7 d of culture from Petri dishes using 0.05% trypsin and designated "first transferred cells" (T1). At the third passage (T3), cells cultured as monolayer were either examined under microscopy--phase contrast, scanning, or transmission electron--or numerated after trypan blue exclusion test. Autologous RGF labelled with fluorochrome were inoculated at the vestibular and palatine site of gingival tissue close to the superior incisors. In this preliminary study, 12 Wistar rats were used; for each, 2 biopsies were dissected and fixed for phase contrast or fluorescence microscopy. On d 1, 3 and 7 after injection in rat gingival tissues, fluorochrome-labelled cells could be detected in all these.

Objective: The aims of this in vitro study were to evaluate: (1) the influence of 5% NaOCl application on Er:YAGirradiated dentin; and (2) its effect on the quality of adaptation of the composite restoration margins. Background data: Previous research has shown that Er:YAG dentin irradiation produces a thermally affected tissue layer that results in lower bond strength than that of nonirradiated dentin. The removal of this thermally-affected layer may enhance the quality of dentin bonding Materials and methods: Forty-nine caries-free extracted human molars were transversely sectioned in order to totally expose the dentin. Four standardized cavities were created on the dentinal surface of each molar. First, two cavities were irradiated with Er:YAG laser (2.94 nm): 150 mJ, 10 Hz, variable square pulse (VSP) mode (100 lsec), beam diameter = 0.9 mm, speed of irradiation = 1 mm/sec, 20% air and 20% water. Then, one of irradiated cavities and one of nonirradiated cavities were treated for 30 sec with 5% NaOCl solution. Finally, they went through a standard bonding treatment for composite restoration, etching, bonding, and composite filling. We obtained four groups of cavities: (1) one control group of nonirradiated cavities not pretreated with NaOCl; (2) one group of nonirradiated cavities, pretreated with NaOCl; (3) one group of irradiated cavities, not pretreated with NaOCl; and (4) one group of irradiated cavities, pretreated with NaOCl. All samples were subjected to thermocycling. Every cavity was immersed into a 0.5% solution of methylene blue. The percentage of dye penetration (microleakage) in the composite-dentin interface was evaluated. Six molars were analyzed by scanning electron microscope. Results: Dye infiltration depth was significantly reduced in irradiated cavities treated with 5% NaOCl solution. Conclusions: The application of a 5% NaOCl solution on Er:YAG irradiated cavities can significantly improve the marginal quality of composite bonding.