Effects of lactational dioxin exposure to development of alveolar bone in SD rat offspring / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To study the influence of lactational dioxin exposure (2, 3, 7, 8-tetrachlorodibenzo-p-dixon, TCDD) on development of alveolar bone in SD rat offspring.</p><p><b>METHODS</b>The rats of TCDD exposure group and control group were sacrificed and the alveolar bone with molars of PD60 rats in the two groups were embedded in resin. The sections were observed by fluorescent microscope. The alveolar bone formation was evaluated by histological examination, tetracycline fluorescence marker and quantitative histomorphometry. The indices of quantitative histomorphometry were compared.</p><p><b>RESULTS</b>The trabecular structure of alveolar bone was looser in TCDD exposure group than in the control group. The tetracycline fluorescence markers were more disorganized in TCDD group. The indices of quantitative histomorphometry of alveolar bone between two groups showed significantly different.</p><p><b>CONCLUSIONS</b>Lactational 2,3,7,8-TCDD exposure decreased the quality and quantity of alveolar bone in SD rat offspring. It is suggested that dioxins exposure may interrupt the spatial configuration.</p>

Association of vitamin D receptor gene polymorphisms with the susceptibility to chronic periodontitis of Han nationality / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate association of vitamin D receptor (VDR) gene polymorphisms with the susceptibility to chronic periodontitis (CP) of Han Nationality.</p><p><b>METHODS</b>Buccal swabs from 166 patients with severe, moderate and mild CP respectively and 80 matched control individuals were collected. DNA was extracted from these buccal swabs using Chelex-100 method. VDR BsmI, ApaI, TaqI were tested with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The distribution of the genotypes and allele frequencies in the patient and control groups were analyzed.</p><p><b>RESULTS</b>The frequency of VDR ApaI allele A was significantly higher among patients with CP than controls. Frequencies of VDR ApaI allele A were significantly higher in severe CP patients than in moderate CP and mild CP respectively. There was no significant difference in the genotype distribution or the allele frequencies of VDR BsmI and TaqI between the controls and CP patients.</p><p><b>CONCLUSIONS</b>These data indicate that VDR ApaI allele A may be related to the susceptibility to CP in Han Nationality.</p>

The effect of lead exposure in utero on the teeth eruption and enamel development of rat offspring / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To investigate the effects of lead exposure at different levels in utero on the teeth eruption and enamel development of rat offsprings.</p><p><b>METHODS</b>27 pregnant SD rats were divided into three groups randomly: high level lead group (HLG), low level lead group (LLG) and control group with nine rats in each group. The three groups from the gestation day to the end of the gestation were given either deionized water in control group or deionized water containing 200 mg/L Pb2+ as lead acetate through drinking method in high level lead experimental group and 50 mg/L Pb2+ as lead acetate through drinking method in low level lead experimental group. The incisors of newborn rats were marked at the level of the gingival papilla on the 26th day after birth. On the 36th day, the incisors of newborn rats were marked again at the same level. Then the rat offsprings were killed and their blood was collected for lead analysis. The mandible incisors of rat offspring were separated and the content of Pb in incisors was determined by using a graphite furnace atomic absorption spectrometric method. The teeth of rat offspring were observed and the distance between two marks were measured by means of stereomicroscope. The ratio of calcium to phosphate of enamel of rat offspring was compared by electron probe microanalyses.</p><p><b>RESULTS</b>The level of blood lead in 200 mg/L, 50 mg/L treated rat offspring groups was higher than that in control group. The tooth lead of 200 mg/L, 50 mg/L treated rat offspring groups [(77.3 +/- 6.3), (27.8 +/- 4.5) microg/g] were higher than the control [(6.6 +/- 0.8) microg/g, P < 0.01]. Compared with the control group, the teeth of lead exposure experimental groups were smaller and severity of attrition was obvious and pulpal perforations were often observed. These appearances was more distinct in rats of high level lead experimental group. The incisors of lead-treated rat offspring erupted [(0.25 +/- 0.08), (0.30 +/- 0.09) mm/d] more slowly than control ones [(0.39 +/- 0.09) mm/d, P < 0.01]. The ratio of calcium to phosphate (Ca/P) decreased with the increase of lead exposure. It was found that Ca/P in lead exposure experimental groups (1.68 +/- 0.54), (1.37 +/- 0.47) was significantly lower than that in the control group (2.14 +/- 0.33).</p><p><b>CONCLUSION</b>Lead exposure in utero affects the normal eruption of teeth and enamel formation and the degree was related with the lead exposure level.</p>

An experimental study on the influence of osteoporosis to bone repairing with bone matrix gelatin in ovariectomized rats / 中华整形外科杂志

<p><b>OBJECTIVE</b>To study the influence of experimentally osteoporosis to osteogenic efficiency of bone matrix gelatin(BMG) implanted into the calvarial defects of rats.</p><p><b>METHODS</b>Sixty-eight female SD rats of 12 +/- 1 weeks were randomly divided into two groups with 34 rats in each group. The ovaries were excised in the ovariectomized group (VG). The control group underwent sham surgery. Ninety days after ovariectomy, 10 rats from each group were examined to ensure the formation of postmenopausal osteoporosis by measuring bone density of the femur with single photon absorptiometric measurements. A critical-sized (8 mm in diameter) calvarial defect was created on the rest of 48 rats. Bone matrix gelatin was implanted to the defect. The rats were scarified at the 21st and 56th day after surgery respectively. The new bone forming capability of BMG was evaluated with undecalcified histological observation, tetracycline fluorescence marker, quantitative bone histomorphometry, At 90th day after ovariectomy, bone density of scanning electron microscopy and X-ray spectrometry.</p><p><b>RESULTS</b>OVG showed very significant difference compared with the control group (0.315 +/-.015) g/cm2 vs [(0.347 +/- 0.017) g/cm2, P < 0.01 ]. At the 21st day following the implantation operation, new bone formed within the bone defects in both groups. The amount of new bone in OVG was lower than the control group. The tetracycline-labeled region in the bone defect was sparser in the OVG. At the 56th day, the bone defects healed mostly in the control group but fibrous tissue filled parts of bone defect in the OVG. The distance between two fluorescent lines of incorporated tetracycline and the mean mineralization deposition were significantly lower in the OVG than the control at the 21st day and 56th day. Mineralization of callus in OVG was inferior. Significant difference was found between the OVG and the control group in the calcium to phosphate ratio of callus in bone defects at the two time-points.</p><p><b>CONCLUSIONS</b>Experimentally induced osteoporosis depressed osteogenic efficiency of BMG, suggesting that estrogen could play an important role in bone remodeling with bone substitute participating.</p>