Cytogenetic analysis of gingival epithelial cells, as related to smoking habits and occurrence of periodontal disease.

Periodontal disease, progressing from gingivitis to periodontitis, affects the majority of the world population. Its pathogenesis is related to a complex interaction between environmental, microbial, genetic and other host factors, tobacco smoking being the most important environmental risk factor. Conflicting results are reported in the literature regarding the effects of smoking habits on cytogenetic damage in exfoliated oral cells. We report herein the results of a study evaluating, for the first time, the frequency of micronucleated and binucleated cells in the gingival epithelium. There was no significant elevation of these cytogenetic end-points in 43 subjects as related to smoking habits (never-smokers, ex-smokers, and current smokers) and periodontal disease (mild, moderate, or severe forms of gingivitis and periodontitis). Therefore, the overall data emerging from the present study do not support the evidence for an association between smoking habits, periodontal disease and genotoxic damage in gingival epithelial cells.

Genotoxic damage in the oral mucosa cells of subjects carrying restorative dental fillings.

A large proportion of the population carries restorative dental fillings containing either classic Hg-based amalgams and/or the more frequently used methacrylates. Both Hg- and resin-based materials have been shown to be released into the buccal cavity and to be spread systemically. In addition, they induce toxic and genotoxic alterations in experimental test systems. Using the comet assay, we previously demonstrated that circulating lymphocytes of subjects with dental fillings have an increased DNA damage. Here, we analyzed the oral mucosa cells of 63 young subjects of both genders, by using both the comet assay and the micronucleus (MN) test and by monitoring cell death markers. The results obtained show that both amalgams and resin-based composite fillings can induce genotoxic damage in human oral mucosa cells, as convincingly and dose-dependently inferred from the results of the MN test and, more marginally, from comet assay data. Lifestyle variables, also including alcohol intake and smoking habits, did not affect the genotoxic response and did not act as confounding factors. Thus, we provide unequivocal evidence for the genotoxicity of both amalgams and resin-based dental fillings in humans not only by testing circulating lymphocytes but also by analyzing oral mucosa cells. These findings are of particular relevance due to the circumstance that subjects with restorative materials are exposed continuously and for long periods of time.

A randomized clinical trial to evaluate and compare implants placed in augmented versus non-augmented extraction sockets: 3-year results.

BACKGROUND: The alveolar ridge undergoes reabsorption and atrophy subsequent to tooth removal and thus exhibits a wide range of dimensional changes. Preservation of the alveolar crest after tooth extraction is essential to enhance the surgical site before implant fixture placement. The aim of this randomized clinical study is to investigate and compare the need for additional augmentation procedures at implant insertion, as well as the success rate and marginal bone loss for implants placed in the grafted sites versus those placed in naturally healed sites. METHODS: Forty patients with ≥1 hopeless tooth were randomly allocated to: 1) a test group, receiving extraction and grafting corticocancellous porcine bone; and 2) a control group, receiving extraction without any graft. After 7 months of healing, implants were inserted in each of the sites. The implants were submerged and loaded after 4 months with metal-ceramic rehabilitation. The follow-up included evaluation of implant diameter and length, the need for additional augmentation procedures at implant placement, implant failure, and marginal bone level changes. All patients were followed over a 3-year period. RESULTS: One implant failed in the control group at the second stage of surgery (6 months after placement); one implant failed in the test group after 2 years of loading. The cumulative implant success rate at the 3-year follow-up visit reached 95% for both groups. No statistically significant differences were detected for marginal bone changes between the two groups. CONCLUSIONS: It was concluded that implants placed into grafted extraction sockets exhibited a clinical performance similar to implants placed into non-grafted sites in terms of implant survival and marginal bone loss. However, grafted sites allowed placement of larger implants and required less augmentation procedures at implant placement when compared to naturally healed sites.

Evaluation of effects on bone tissue of different osteotomy techniques.

The aim of this study is to evaluate and compare the response of bone tissue after osteotomy carried out with either rotating cutters or with piezoelectric terminals.Bioptic samples of bone tissue were taken during operations with rotating burs and piezoelectric terminals to increase bone volume before implantology. Samples first underwent histomorphometric analysis. Subsequently, osteoblastic cells, obtained from different samples, were placed in culture and allowed to proliferate to in vitro evaluate the time to initiate growth and to reach confluence. Finally, a molecular biologic study by reverse transcription polymerase chain reaction was performed to evaluate the expression of typical osteoblastic molecular markers, such as osteoprotegerin and osteopontin.Histomorphometric analysis showed that the width of necrotic line on the osteotomic margins from samples taken using different techniques did not vary significantly. Moreover, the times of initial growth and of confluence in cells from the 2 groups did not show any statistically significant differences. However, a highly significant correlation was revealed between the age of the patient and the initial growth time and the confluence. Similarly, reverse transcription polymerase chain reaction showed that the osteoprotegerin and osteopontin expression levels did not change significantly according to the surgical technique used.In conclusion, osteotomies carried out with either instrument do not seem to substantially influence the vitality of the bone tissue. The variability of the expression levels of typical osteoblastic markers seems to be linked more to other factors than to the surgical technique used.

Biomonitoring of DNA damage in peripheral blood lymphocytes of subjects with dental restorative fillings.

Dental fillings provide a major iatrogenic exposure to xenobiotic compounds due to the high prevalence of surface restorations in developed countries. Experimental data suggest that both amalgams, which contain mercury, and resin-based dental materials cause an impairment of the cellular pro- and anti-oxidant redox balance. The aim of this study was to assess the potential genotoxicity of dental restorative compounds in peripheral blood lymphocytes of young exposed subjects compared with controls. The study examined, by use of the comet assay, 68 carefully selected subjects taking into account the major known confounding factors. In the 44 exposed subjects, the mean numbers of restored surfaces was 3.0 and 3.8 in males and females, respectively. Tail length, percentage of DNA in the tail, tail moment or Olive tail moment were twofold higher in the exposed group than in unexposed controls, with significant differences. No significant difference was observed between amalgam and composite fillings. Furthermore, as shown by multivariate analysis, the association between dental fillings and DNA damage was enhanced by the number of fillings and by the exposure time. Among the lifestyle variables, a moderate physical activity showed a protective effect, being inversely correlated to the DNA damage parameters evaluated. On the whole, the use of DNA-migration allowed us to detect for the first time the potential adverse impact on human health of both kinds of dental filling constituents, the amalgams and the methacrylates. The main mechanism underlying the genotoxicity of dental restorative materials of various nature may be ascribed to the ability of both amalgams and methacrylates to trigger the generation of cellular reactive oxygen species, able to cause oxidative DNA lesions.