Changes in collagen types during the healing of rabbit tooth extraction wounds

Three alpha chains of type V collagen--alpha 1 (V), alpha 2 (V), and alpha 3 (V)--were initially demonstrated together with the expected collagen types I and III in the pepsin-soluble fraction of both normal mandibular bone and tooth extraction wound tissues of rabbits, as analyzed by sodium dodecyl sulfate-gel electrophoresis. The total collagen content of each extraction wound, as determined by the hydroxyproline assay, was observed to increase continuously from day 5 through day 17 and then leveled off or decreased. The ratio of type V to type I collagen was significantly higher in the initial stage of wound healing and decreased sharply down to the level of mandibular bone by day 5. The ratio of type III to type I collagen in the pepsin-soluble fraction increased and reached a maximum on day 5, whereas it was maximal on day 7 in the cyanogen bromide-soluble fraction, and thereafter decreased gradually in both fractions. The ratio for the pepsin-soluble fraction was, however, significantly higher than that for the cyanogen bromide-soluble fraction in the early stage of wound healing.     

Study of the location of mandibular mental foremen in modern and neolithic adult]

37 cases of mandible of Neolithic adult that both sexes without missing teeth,alveolar bone were studied.The result showed that the location of the mental foramen below the apex of the lower second premolar was the most common(67.97%) in the modern adult,and the location of the mental foramen below between the apex of the lower second premolar and the first molar was the most common (64.86%) in the neolithic adult.     

The association of osteoprotegerin gene polymorphisms with periodontitis

Background:  It has been demonstrated that genetic variation accounts for approximately half of the variance in periodontitis. The reported association of polymorphisms in the osteoprotegerin (OPG) gene with osteoporosis suggests that the OPG gene may also influence the genetic risk for periodontitis.
Subjects and methods:  We investigated the distribution of OPG gene polymorphisms in 49 patients with aggressive ( n  =   14) or chronic ( n  =   35) periodontitis and 49 control subjects without periodontitis, using polymerase chain reaction (PCR)–restriction fragment length polymorphism and PCR–single strand conformation polymorphism followed by direct sequencing.
Results:  A total of seven known polymorphisms and one new mutation, G373A, were identified. The T950 and G1181 alleles were more common in patients with periodontitis ( P  =   0.028 and P  =   0.047, respectively) than in control subjects. Especially, G1181 allele was associated with patients with aggressive periodontitis.
Conclusion:  The TG haplotype of T950C and G1181C polymorphisms in the OPG gene may be useful genetic markers for the prediction of periodontitis. Further studies in a larger population are required to determine whether these alleles directly contribute to periodontitis susceptibility.     

The removal torque of titanium implant inserted in rabbit femur coated with biomimetic deposited Ca-P coating

A number of experimental data on biomimetic deposition CaP (BDCaP) coating implants have reported promising outcomes by histological evaluation. But little is investigated on the role of the BDCaP coating and osseointegration mechanism by interface shear strength. To make a direct biomechanical comparison between the BDCaP coating implants and the uncoated rough titanium implants (control), a well-established animal model for implants removal torque testing was employed in rabbits, using a self-matching experimental design. All implants had an identical cylindrical screw shape without any macroscopic retentive structure. After 2, 4, 6, 8 and 12 weeks of bone healing, removal torque testing was performed to evaluate the interfacial shear strength of each implant type. The torqued implants were sputter-coated with gold for morphology observation and observed with a field-emission electron microscopy. Results showed that the interfacial shear strength of the BDCaP coating implants was similar to that of the uncoated rough implants at 2 and 4 weeks of healing. The mean removal torque values of the BDCaP coating implants were lower than those of control implants (P < 0.05) after 6 weeks of healing. The removal torque values for both types of implants revealed similar mean values after 8 and 12 weeks of healing; there were no significant difference between the two types of implants (P > 0.05). It can be concluded that the BDCaP coating implants had no beneficial effect on the interfacial shear strength at early bone healing stage.     

Biological properties of the native and synthetic lipid A of Porphyromonas gingivalis lipopolysaccharide

INTRODUCTION AND METHODS: A pentaacyl and diphosphoryl lipid A molecule found in the lipid A isolated from Porphyromonas gingivalis lipopolysaccharide (LPS) was chemically synthesized, and its characteristics were evaluated to reconfirm its interesting bioactivities including low endotoxicity and activity against LPS-unresponsive C3H/HeJ mouse cells. RESULTS: The synthesized P. gingivalis lipid A (synthetic Pg-LA) exhibited strong activities almost equivalent to those of Escherichia coli-type synthetic lipid A (compound 506) in all assays on LPS-responsive mice, and cells. LPS and native lipid A of P. gingivalis displayed overall endotoxic activities, but its potency was reduced in comparison to the synthetic analogs. In the assays using C3H/HeJ mouse cells, the LPS and native lipid A significantly stimulated splenocytes to cause mitosis, and peritoneal macrophages to induce tumor necrosis factor-alpha and interleukin-6 production. However, synthetic Pg-LA and compound 506 showed no activity on the LPS-unresponsive cells. Inhibition assays using some inhibitors including anti-human Toll-like receptor 2 (TLR2) and TLR4/MD-2 complex monoclonal antibodies showed that the biological activity of synthetic Pg-LA was mediated only through the TLR4 signaling pathway, which might act as a receptor for LPS, whereas TLR2, possibly together with CD14, was associated with the signaling cascade for LPS and native lipid A of P. gingivalis, in addition to the TLR4 pathway. CONCLUSION: These results suggested that the moderated and reduced biological activity of P. gingivalis LPS and native lipid A, including their activity on C3H/HeJ mouse cells via the TLR2-mediated pathway, may be mediated by bioactive contaminants or low acylated molecules present in the native preparations having multiple lipid A moieties.     

Oral health status and behaviours of children in rural districts of Cambodia

OBJECTIVE: To describe the caries and periodontal status of children in rural Cambodia and to study their oral health habits. METHOD: Field examinations were conducted in Pailin, Kampong Thom and Kratie which are three rural districts in Cambodia. Children aged 6 and aged 12 were selected for report of caries status of primary and permanent teeth respectively. The periodontal status of the 12-year-old children in Kampong Thom and Kratie were assessed. A parental questionnaire survey was performed to study the children's tooth brushing habits, snacks habits and their diet. RESULTS: A total of 120 6-year-old children and 196 12-year-old children were examined. The caries experience (dmft) of the 6-year-old children was 7.9 +/- 5.6. The caries experience (DMFT) of the 12-year-old children was 1.1 +/- 1.6 and all were untreated caries (DT). None of the surveyed 12-year-old children had healthy gums and 62% had calculus. A total of 316 questionnaires were collected. The result found 44% and 22% of the 6- and 12- year-old children had never brushed. Their meals were all mainly rice, soup and congee and snacks were not common. CONCLUSION: The caries experience of the 6-year-old children was high and most of the caries was untreated. The 12-year-old children had a mean score of 1.1 DMFT in their permanent teeth. They all had bleeding gums and more than half had calculus. Their oral health habits need to improve as many children never brushed their teeth.     

Effects of salivary ultrafiltrates on the production of phenol from tyrosine by oral microorganisms

The metabolism of oral microorganisms is known to correlate with oral diseases. Protein degradation by oral microorganisms is usually followed by the production of phenol from tyrosine. The purpose of this study is to clarify the effect of salivary ultrafiltrates [MW: less than 10,000, 1,000-10,000 (intermediate fraction), less than 1,000, less than 500] on the production or the decomposition of phenol by oral microorganisms. Salivary sediment and salivary ultrafiltrate, the molecular weight of which is less than 10,000 unless otherwise stated, were incubated at 37 degrees C for 24 hours with tyrosine or phenol at a final concentration of 2.5 mg/100 ml. After incubation, the phenol produced (or remained) was extracted with ether and determined spectrophotometrically. Phenol production by oral microorganisms was not seen in the non-dialyzable fraction of saliva even when tyrosine was added. It was confirmed that the presence of the salivary ultrafiltrates was essential for the production of phenol by oral microorganisms. Phenol production in the salivary ultrafiltrate was further increased with the addition of tyrosine or non-dialyzable fraction of saliva. Phenol disappeared within 48 or 72 hours after the salivary sediment was incubated with phenol. The decomposition of phenol was inhibited with the salivary ultrafiltrate. Phenol production was enhanced with the addition of Good's buffer. Optimum pH of phenol production by oral microorganisms in the ultrafiltrate of saliva was within the range from 6.5 to 7.0 in the presence of Good's buffer (MOPS). Phenol production decreased with the reduction of the molecular weight of the salivary ultrafiltrates. The phenol production was increased when the intermediate fraction was added to the ultrafiltrate (MW: less than 1,000). The increase of the phenol production was considered to be due to the peptides in the intermediate fraction.     

Ameloblastic fibrosarcoma of the right mandible: immunohistochemical and electron microscopical investigations on one case, and a review of the literature

A case of a 7-year-old girl with ameloblastic fibrosarcoma of the right mandible is described. Immunohistochemical techniques (detection of intermediate filaments, tissue polypeptide antigen, lactoferrin, lysozyme, Factor VIII-related protein, S-100 protein, carcinoembryonic antigen, alpha-foeto-protein, "lectin-receptors") and electron microscopy were applied. The epithelial part of the tumor, which was positive for keratin, showed distinct tonofilaments in electron microscopy. In contrast, the mesenchymal part was vimentin positive. The cells displayed the ultrastructural features of fibroblasts. The observations are compared with those reported in the literature.