Association of tumor necrosis factor receptor type 2 +587 gene polymorphism with severe chronic periodontitis

BACKGROUND: Genetic polymorphisms for cytokines and their receptors have been proposed as potential markers for periodontal disease. Tumor necrosis factor receptor 2 (TNFR2) is one of the cell surface receptors for TNF-alpha. Recent studies have suggested that TNFR2 gene polymorphism is involved in autoimmune and other diseases. OBJECTIVES: The aim of the present study is to evaluate whether TNFR2(+587T/G) gene polymorphism is associated with chronic periodontitis (CP). METHODS: One hundred and ninety-six unrelated subjects (age 40-65 years) with different levels of CP were identified according to established criteria, including measurements of probing pocket depth (PPD), clinical attachment level (CAL), and alveolar bone loss (BL). All subjects were of Japanese descent and non-smokers. Single nucleotide polymorphism at position +587(T/G) in the TNFR2 gene was detected by a polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP) method. RESULTS: The frequency and the positivity of the +587G allele were significantly higher in severe CP patients than in controls (p=0.0097; odds ratio=2.61, p=0.0075; odds ratio=3.06). In addition, mean values of PPD, CAL, and BL were significantly higher in the +587G allele positive than in the negative subjects (p=0.035, 0.022, and 0.018, respectively). CONCLUSIONS: These findings suggest that the TNFR2(+587G) polymorphic allele could be associated with severe CP in Japanese.     

Persistent endodontic lesion due to complex cementodentinal tears in a maxillary central incisor--a case report

The cementodentinal tear is rarely detected by noninvasive procedures owing to its clinical picture simulating a root fracture or a periodontal or endodontic lesion. We present a case of complex cementodentinal tears in a 79-year-old woman who presented a repeated swelling at the labial mucosa of the left maxillary central incisor for 6 months. Periapical radiographs demonstrated a vertical radiolucent fracture line extending from the root apex along the mesial aspect of the root to near the middle portion of the root of the left maxillary central incisor. Because endodontic re-treatment failed to cure the disease, periapical surgery was performed, and 2 fractured U-shaped root fragments around the apical root surface were removed. Histologic examination showed that the 2 fractured root fragments were composed mainly of the dentin covered by a thin layer of the cementum and overlying periodontal ligament tissue, suggesting cementodentinal tears. A swelling recurred 8 months after the initial operation. Therefore, a second periapical surgery was performed. Although no obvious fracture line was observed around the root surface, the second surgery did not cure the disease, either. A persistent small swelling was noted at the alveolar mucosa of the affected tooth during the follow-up. We conclude that although a cementodentinal tear can be detected by a careful radiographic examination, its clinical outcome is not predictable by surgical removal only.     

Regenerative treatment of serious periodontosis with grafting of cancellous iliac bone and gingival flaps and replanting of patients' teeth

The purpose of this study was to assess the ability of serious periodontosis patients to regain satisfactory biting function, using the patients' own teeth, by regeneration of the alveolar bone. Twelve serious periodontosis patients whose alveolar bone was markedly absorbed and whose teeth were quite unstable were treated with replanting of their teeth and grafting of cancellous iliac bone and gingival flaps by the clinical team, which consisted of plastic surgeons and dentists. No patients developed postoperative complications (e.g., infections), and grafted iliac bone took in all patients. The total number of replanted teeth was 65, and only 4 of them fell off (92% take rate). Three to 4 months after surgery, the replanted teeth received prosthetic treatment so that the patients could begin biting. Ten patients were monitored for 5 months or longer, and they started to eat normal food after the fifth month. Regained biting function and satisfaction of having food were almost the same as before the periodontosis became severe in these 10 patients. Regeneration of alveolar bone was confirmed in later radiographs. To date, the maximum follow-up period is 2 years and 8 months (average = 1 year and 6 months). All patients have good biting function, and there have been no findings of absorption of reconstructed alveolar bone or of the root of replanted teeth. This treatment method would be quite useful for patients with serious periodontosis.     

Interleukin-6 receptor gene polymorphisms and periodontitis in a non-smoking Japanese population

AIM: The indispensable role of interleukin-6 receptor (IL-6R) in regulating IL-6 responses has been clearly established. We have previously reported that IL6R polymorphisms strongly influenced the serum levels of soluble IL-6R. In this study, we investigated the association between these genetic variations and periodontitis. MATERIAL AND METHODS: Among the seven novel IL6R single-nucleotide polymorphisms (SNPs) reported, we genotyped two important sites: the +48892 A/C in exon 9 and the -183 G/A in the promoter region. The SNP in exon 9 results in Asp-->Ala substitution in the proteolytic cleavage site of IL-6Ralpha. In total, 212 periodontitis cases and 210 healthy controls were genotyped using polymerase chain reaction, restriction fragment length polymorphisms and direct sequencing methods. RESULTS: Analysis of the genotype distribution of the +48892 A/C SNP in periodontitis patients and in controls revealed a suggestive association with aggressive (p = 0.04) and chronic periodontitis (p = 0.04). In addition, the carriage rate for the A allele was significantly higher in chronic periodontitis patients [p = 0.02, odds ratio (OR) = 2.25]. No association was found in the -183 G/A SNP. The two markers were in linkage disequilibrium (LD) (|D'| = 0.53). CONCLUSION: The IL6R+48892 A/C polymorphism could act as a risk factor for periodontitis; however, further association and biological studies are needed.     

Synergistic effects of verapamil on pingyangmycin-induced cytotoxicity and apoptosis in KB cells

OBJECTIVES: Previous studies have shown that pingyangmycin (PYM; bleomycin A5) can induce two distinct modes of cell death (necrosis, apoptosis). At high concentrations, PYM can be considered as an apoptosis mimetic drug. In this study, we explored the possibility that the membrane-modifying agent verapamil might affect the transport function of PYM through the plasma membrane, resulting in inducing apoptosis of tumor cells at low concentration of PYM. METHODS: Cytotoxicity, flow cytometry and DNA fragmentation assays were used to detect the interaction of verapamil and PYM in human oral carcinoma cell line KB cells. RESULTS: Our results indicated that verapamil can enhance the cytotoxicity of PYM against KB cells with the non-toxic doses (P<0.05). The cell viability at a concentration of 500 microg ml-1 of PYM was 35+/-2% compared with control and 10 microg ml-1 verapamil decreased the cell viability lower to 28+/-1%. In addition, because of the synergistic effect of verapamil, KB cells apoptosis was found to be induced when treated with a lower concentration of PYM (50 microg ml-1) for 24 h by flow cytometry and DNA fragmentation assays. CONCLUSIONS: Verapamil was found to enhance PYM-induced cytotoxicity and apoptosis in KB cells. The responsiveness of PYM might be explained by the effective accumulation of PYM by verapamil in KB cells mediated by the inhibition of PYM efflux function of the cells.     

Resinous perforation-repair materials inhibit the growth,attachment, and proliferation of human gingival fibroblasts

The choice of repair material is one of the important factors in the prognosis of the endodontically treated tooth with a perforation defect. The cytotoxicity of perforation-repair materials must be investigated to ensure a safe biological response. The aim of this in vitro study was to evaluate the effect of resin-modified, glass-ionomer cement, compomer, and resin on human-gingival fibroblasts. Human gingival fibroblasts from crown lengthening surgery were cultured by using an explant technique with the consent of the patient. Cytotoxicity was judged by using an assay of tetrazolium bromide reduction. The results showed that resin-modified, glass-ionomer cement Fuji II LC, compomer Compoglass, and resin SpectrumTPH (TPH) were cytotoxic to primary human gingival fibroblast cultures by inhibiting cell growth and proliferation. TPH alone had an effect on cell attachment. It was found that TPH was the most cytotoxic repair material among those tested in all cultures. The toxicity decreased in the order of TPH>FLC>CG.     

Cool Mist Irrigation Improves Heat Dissipation during Surgical Bone Drilling

Objective High-speed drilling generates heat in small cavities and may pose a risk for neurovascular tissues. We hypothesize that a continuous pressurized cold mist could be an alternative approach for better cooling during drilling of bone to access cranial lesions. This study aims to examine this idea experimentally. Design Ex-vivo drilling tests with controlled speed, feed, and depth were performed on cortical bone samples. Thermocouples were embedded underneath the drilling path to compare the temperature rises under mist cooling (at 3°C, < 300 mL/h) and flood irrigation (at 22°C, > 800 mL/h). Results A significant difference exists between these two systems (p value < 0.05). The measured temperature was ∼ 4°C lower for mist cooling than for flood irrigation, even with less than a third of the flow rate. Conclusion Experimental data indicate the capability of mist cooling to reduce heat generation while simultaneously enabling flow reduction and targeted cooling. An improved field of view in an extremely narrow access corridor may be achieved with this technology.