Regenerative endodontic treatment of an immature permanent tooth at an early stage of root development: a case report.

INTRODUCTION: Regenerative endodontic treatment (RET) has been used in treating nonvital immature permanent tooth whose root formation ranged from approximately two-thirds of the full root length to almost completely developed root with open apex at least 1.1 mm in diameter according to the reported cases. However, this case report was to introduce RET in an affected tooth at an early stage of root development. METHODS: The premolar #29 in an 8-year-old girl had pulpal necrosis and apical periodontitis caused by the fracture of dens evaginatus. Its root was at the beginning of formation. Copious hemorrhagic drainage was observed after preparing of an access cavity. The canal was irrigated with 3% NaOCl solution, sterile normal saline, and chlorhexidine. Root dressing with triple antibiotic was then performed and left for 4 weeks. We used a K-file to create bleeding into the canal after flushing and drying the root canal. Mineral trioxide aggregate was carefully placed over the formed blood clot. RESULTS: Clinical examination at 1, 3, 6, 9, and 12 months revealed an asymptomatic tooth. Radiographic examination revealed resolution of periapical radiolucency, increased thickening of the canal wall, and lengthening of the root, which demonstrated the continual development of the tooth root. Noticeably, the first-month postoperative radiograph showed radiopaque image in the root canal like an isolated island, which was gradually obvious during follow-up. Cone-beam computed tomography revealed that the calcification was attached with dentin wall in buccolingual direction, and the root canal was not completely obliterated. CONCLUSIONS: RET is feasible for a tooth at an early stage of root development that has necrotic pulp and periapical lesion.

[Effect of PG0839 gene of Porphyromonas gingivalis on inflammatory cytokine in human oral epidermoid carcinoma KB cell].

OBJECTIVE: To investigate the effect of PG0839 gene form Porphyromonas gingivalis (Pg) on inflammatory cytokine expression in human oral epidermoid carcinoma KB cell. METHODS: A mutant in the PG0839 gene of Pg was created by insertional inactivation. Group 1 was chanllenged with PgW83 strain, group 2 with PG0839-defective mutant, and the control group with Dulbecco's modified Eagle's medium only. KB cells were co-cultured with presence of bacteria for 24 h. At the time point of 0.5, 2, 6, 12 and 24 h, cells were stored in Trizol. The mRNA expression of interleukin-1ß (IL-1ß) and Toll like recepector-4 (TLR-4) was examined by reverse transcription polymerase chain reaction. RESULTS: At 2 h and 6 h, IL-1ß mRNA expression was lower in group 2 than in group 1 (2 h: 0.31 ± 0.11 versus 0.95 ± 0.48, P < 0.05; 6 h: 0.57 ± 0.20 versus 1.29 ± 0.55, P < 0.05). At 0.5 h and 6 h, TLR-4 mRNA expression was lower in group 2 than in group 1 (0.5 h: 0.20 ± 0.09 versus 0.58 ± 0.09, P < 0.05; 6 h: 0.34 ± 0.04 versus 0.71 ± 0.18, P < 0.05). CONCLUSIONS: PG0839 gene may play an important role in Pg-induced inflammatory effects of KB cell.

[Initial study of biological characterization and virulence of Porphyromonas gingivalis PG0839-defective mutant].

PURPOSE: To study the effect of PG0839 gene form Porphyromonas gingivalis (P. gingivalis) on biological characterization and virulence in a murine model of soft tissue destruction, and further to provide evidence for clarifying the gene function of PG0839. METHODS: P. gingivalis W83 and PG0839-defective mutant strains were plated on brain heart infusion (BHI). Colonial formation, micromorphology and growth curve of the two strains were observed. The two strains cells were mixed respectively with sheep erythrocytes, which were prepared to a final concentration of 1% in 1×PBS, to assess hemagglutination activity. The mice were challenged with subcutaneous injections of bacterial suspension,which were P. gingivalis W83 and PG0839-defective mutant strains at the doses of 2×10(10), 1×10(10), 5×10(9) CFU/mL respectively, on the dorsal surface. Difference in survival situation of mice in various groups was examined using Pearson Chi-square and log rank test with SPSS 13.0 software package. RESULTS: In contrast to the wild-type W83 strain, PG0839-defective mutant strain was nonpigmented and the hemagglutinin activities reduced. However, the growth rate of PG0839-defective mutant strain was not affected (U=25.50, P=0.19). Results of the mice subcutaneous infection model indicated that the virulence of the PG0839-defective mutant strain was significantly lower than P. gingivalis W83 strain (P<0.05). CONCLUSIONS: Absence of PG0839 gene altered several biological characteristics of P. gingivalis W83 strain, suggesting that PG0839 gene may regulate the expression of certain gene or gene product of P. gingivalis W83 strain. Moreover, PG0839 gene may contribute to the virulence of P. gingivalis W83.

[Detection of Porphyromonas gingivalis in the subgingival plaque of puberty gingivitis].

PURPOSE: To detect the presence of Porphyromonas gingivalis (Pg) in the subgingival plaque of puberty gingivitis and to investigate its relationship with gingival health. METHODS: The subjects of 14- to 17-year-old children in this study were divided into two groups, puberty gingivitis group and gingival healthy group, with 36 in each group. Periodontal parameters were recorded. A 16S rRNA-based polymerase chain reaction (PCR) detection method was used to determine the prevalence of Pg in the subgingival plaque samples. The AVG of positive band in the agarose gel electrophoresis was analyzed using the automatic gel documentation and image analyzer software. The relative quantity of Pg was determined. The data were statistically analyzed using SPSS11.5 software. Chi-square test was used to compare the prevalence of Pg in the two groups. Wilcoxon rank sum test was used to analyze the relative quantity of Pg and the severity between the Pg-positive and the Pg-negative subjects. Spearman correlation analysis was used to test the relationship between the relative quantity of Pg and periodontal parameters. RESULTS: The prevalence of Pg in the puberty gingivitis group and gingival healthy group was 47.22% and 25.00%, respectively (P<0.05). The relative quantity of Pg in the two groups was 48.02% and 21.46%, respectively(P<0.01). In all the Pg-positive subjects of puberty gingivitis group, there was positive correlation between the relative quantity of Pg and the gingival index (GI),sulcus bleeding index (SBI) and the probe depth (PD). There were statistically differences between them. The GI and SBI index of the Pg-positive subjects were statistically higher than that of the Pg-negative subjects in the puberty gingivitis group (P<0.01). CONCLUSION: Periodontal pathogens can colonize in the subgingival plaque in puberty subjects and colonization of Pg is relevant to the status of gingival health.

[Study of caries polarization in 2-5 year-old children of Shenyang, China].

OBJECTIVE: To investigate dental caries polarization in 2-5 year-old children. METHODS: 3 799 random samples of 2-5 year-old children from attending kindergarten in Shenyang were selected. Means of dmft index and SiC index for each age group were calculated by WHO Collaborating Center. The subjects of each age group were further divided into subgroups of different level of dmft: the dmft of subgroup I was 0, the dmft of subgroup II was 1, the dmft of subgroup III was 2, the dmft of sub-group IV was equal to or more than 3. The obtained data were analyzed statistically with SPSS 10.0. RESULTS: 4.5% of 2-year-old children were carriers of 60.0% of the total dmft in that age group, 13.2% of 3-year-old children were carriers of 69.4% of the total dmft in that age group, 34.4% of 4-year-old children were carriers of 86.6% of the total dmft in that age group, and 47.8% of 5-year-old children were carriers of 89.8% of the total dmft of that age group. CONCLUSION: This study supports the assertion that a small percentage of persons with high dental caries rate and a large percentage of caries-free persons of early childhood caries.