BACKGROUND: In the tooth regeneration and dental tissue engineering study, finding suitable stem cells are the central issues.OBJECTIVE: To isolate and culture child exfoliated deciduous tooth pulp stromal cells, and compare difference in dentin sialophosphoproteln expression prior to and following mineralization.DESIGN, TIME AND SETTING: The cell observational experiment was performed at the Central Laboratory of Daqing Oil Field General Hospital from December 2006 to December 2007.PARTICIPANTS: Dental pulp were obtained from exfoliated deciduous molar tooth of eight children aged from eight to ten, four males, four females. The possibility of infectious diseases, endocrine disease, dental caries and periodontal disease was excluded.METHODS: Deciduous teeth pulp stromal cells were obtained by tissue block adhesion method, and then cultured in DMEM with 10% fetal bovine serum for 14 days. Following digestion and passage, cells were incubated in DMEM/F12 supplemented with 50 pmol/L laevo-ascorbic acid, 10 nmol/L vitamin D3. 10 mmol/L Na β-glycerophosphate and 10-8 mol/L dexamethasone for another 14 days. Cells cultured in complete DMEM served as controls.MAIN OUTCOME MEASURES: Cell morphology and growth rule were observed under a microscope. Difference in dentin sialophesphoproteln expression was determined prior to and following mineralization using immunocytochemical staining.RESULTS: Dental pulp stromal cells from human exfoliated deciduous tooth, adhered to the wall, were polygon-shaped and characterized by large cell size and a relatively large nucleus and plenty cytoplasm after mineralization for 14 days. Over 80% cells were positive for dentin sialophosphoprotein. Non-induced cells were spindle, and only 2% cells were positive for dentin sialophosphoprotein.CONCLUSION: Odontogenic inductive culture might improve odontoblastic differentiation. It seems that human exfoliatod deciduous tooth pulp represents an new reservoir of adult stem cells with odontogenic potential.

OBJECTIVETo compare the periodontal indices and Porphyromonas gingivalis (P. gingivalis) between the use of self-ligating brackets and conventional brackets.

METHODSThirty patients were divided into 2 groups(n=15). Self-ligating brackets were used in the experimental group. Conventional brackets were used in the control group. Clinical periodontal indices, including plaque index (PLI), gingival index (GI) and probing depth (PD) of observed teeth were examined at three different time points: Before orthodontic treatment, the first month after treatment and the third month after treatment. Subgingival plaques were collected simultaneously at each time point. The number of total bacteria and P. gingivalis in each sample were detectd and quantitated by real-time quantitative polymerase chain reaction, the percentage of P. gingivalis in total bacteria was obtained.

RESULTSBefore treatment, the periodontal indices and the percentage of P. gingivalis in total bacteria had no difference between the two groups (P>0.05). After 1 and 3 months respectively, the periodontal indices and the percentage of P. gingivalis in total bacteria increased with time (P<0.05) and were obviously lower than those of the control group (P<0.05).

CONCLUSIONCompared with conventional brackets, the self-ligating brackets are better for periodontal health. But it is adverse effect on oral health.

Dental Plaque ; Dental Plaque Index ; Humans ; Periodontal Index ; Porphyromonas gingivalis