Does Smoking Affect the Ki67 and p53 Expressions in Asymptomatic Fully Impacted Lower Third Molar Follicles?

Vitamin E ameliorates oral mucositis in gamma-irradiated rats (an in vivo study)

BACKGROUND

Radiation therapy is the primary treatment for neck and head cancer patients; however, it causes the development of oral mucositis accompanied by tissue structure destruction and functional alteration. This study was conducted to evaluate the effect of different doses of vitamin E as a treatment for radiationinduced oral mucositis in rat model.

METHODS

35 male albino rats were randomly divided into five groups: control, untreated radiation mucositis (single dose of 20 Gy), treated radiation mucositis; radiation (single dose of 20 Gy) then vitamin E at doses of 300, 360 and 500 mg/Kg for seven days started 24 h after irradiation. Body weight and food intake were evaluated for each rat. The mucositis score was assessed every day. Rats were sacrificed once at the end of the experiment, and tongue specimens were stained with hematoxylin and eosin, anti P53 and anti Ki67 antibodies.

RESULTS

Results indicated more food intake and less weight reduction in vitamin E treated groups and the contrary for gamma-irradiated group. Additionally, vitamin E delayed the onset and decreased the severity and duration of mucositis. It also restored the histological structure of lingual tongue papillae. Vitamin E treated groups showed a significant higher Ki67 and lower P53 expression as compared to untreated radiation group. The overall improvement increased as vitamin E dose increased. Finally, the amelioration can be attributed to the decreased apoptosis and increased proliferation of cells.

CONCLUSIONS

Vitamin E especially at dose of 500 mg/Kg could be an effective treatment for radiation-induced oral mucositis.

Repeated exposure to whole cigarette smoke promotes primary human gingival epithelial cell growth and modulates keratin expression

BACKGROUND AND OBJECTIVE

The gingiva is the first oral tissue directly exposed to cigarette smoke (CS). Exposure to CS compromises the structure and function of gingival tissue. Damaging or altering the gingival epithelium leads to a compromised protective barrier of the periodontium, resulting in several diseases. The aim of this study was to assess the effect of repeated exposure to CS on gingival epithelial cell growth and on expression of apoptotic protein and keratin.

MATERIAL AND METHODS

Primary human gingival epithelial cells were seeded on a collagen scaffold for 5 d to allow growth and stratification. The cells were then exposed for 5 min to whole CS for 3, 6 and 9 d. At the end of each exposure period, cell proliferation [using (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) (MTT) and 5-bromo-2'-deoxyuridine (BrdU) assays], gene expression [by quantitative reverse transcription polymerase chain reaction (qRT-PCR)] and protein production (by western blot analysis) were investigated.

RESULTS

Higher metabolic activity was found in the CS-exposed cells than in the nonexposed cells, specifically after 3 and 6 d of exposure to CS. At 9 d there was no significant difference between CS-exposed and nonexposed cells. Metabolic activity was supported by the BrdU cell-proliferation analyses, which showed increased cell growth at 3 d compared with the control. However, at 6 and 9 d, cell proliferation in the CS-exposed culture was comparable to that in the nonexposed culture. Interestingly, the Bax/Bcl-2 protein ratios decreased with increased CS exposure, suggesting cell resistance. Moreover, protein analyses showed that CS decreased expression of keratin(K) 5 at 3, 6 and 9 d, and increased expression of K14 at 6 and 9 d. Finally, mRNA analyses showed significant decreases of K1, K6, K10 and K16 in CS-exposed cultures, correlating, at times, with a decrease of protein production.

CONCLUSION

CS was shown to increase epithelial cell proliferation, which may involve cell resistance to apoptosis. This is supported by the modulation of expression of different keratin genes and proteins. Altogether, these data may explain the hyperplasia reported in gingival tissue, as well as periodontal disease, in smokers.

Impacted Mandibular Third Molars: Review of Literature and a Proposal of a Combined Clinical and Radiological Classification

Tooth impaction is a pathological situation where a tooth fails to attain its normal functional position. Impacted third molars are commonly encountered in routine dental practice. The impaction rate is higher for third molars when compared with other teeth. The mandibular third molar impaction is said to be due to the inadequate space between the distal of the second mandibular molar and the anterior border of the ascending ramus of the mandible. Impacted teeth may remain asymptomatic or may be associated with various pathologies such as caries, pericoronitis, cysts, tumors, and also root resorption of the adjacent tooth. Even though various classifications exist in the literature, none of those address the combined clinical and radiologic assessment of the impacted third molar. Literature search using the advanced features of various databases such as PubMed, Scopus, Embase, Google Scholar, Directory of Open Access Journals and Cochrane electronic databases was carried out. Keywords like impaction, mandibular third molar, impacted mandibular third molar, complications, anatomy, inferior alveolar nerve injury, lingual nerve injury were used to search the databases. A total of 826 articles were screened, and 50 articles were included in the review which was obtained from 1980 to February 2015. In the present paper, the authors have proposed a classification based on clinical and radiological assessment of the impacted mandibular third molar.