BACKGROUND: The filling compactness can not be guaranteed due to apparatus retention in traditional lateral condensation.The warm gutter filling can achieve good results because of the easy changeable of gutta-percha in softening states.OBJECTIVE: To compare the warm gutta-percha fillings (Obtura Ⅱ and BeeFill 2 in1 filling) and cold lateral compacted gutta-percha with the bypassing root canal preparation in the intracanal separated instrument of oval canal.METHODS: Firstlythe 60 oval root canals of fiat mandibular central incisors were randomly divided into three groups, with 20 teeth in each group. After that, the root canal was filled with BeeFill 2 in1, Obtura Ⅱ condensation, and lateral condensation.The percentage of void at 5-mm to root tip versus cress section area was observed under a scanning electron microscope.RESULTS AND CONCLUSION: Under in vitro condition, the difference of percentage of void area versus root canal area between the Obtura Ⅱ condensation group and the lateral condensation group had significance (P=0.013), and the similar difference could be found between the BeeFill 2 in1 condensation group and the lateral condensation group (P=0.014), but the difference had no significance between the BeeFill 2 in1 condensation group and the Obtura Ⅱ condensation group (P=0.088).The results revealed that the root canal can be sealed accurately when establish hypass root next to the separated instrument and filled with BeeFill 2 in1 warm gutter filling.

BACKGROUND:Location relationship between maxilary incisor labial inclination and the thickness of anterior alveolar bone displays ethnic and regional differences. OBJECTIVE:To study the correlation of alveolar bone structure and incisor labial inclinationin adolescents with skeletal class II malocclusion in Uygur and Han populations of Xinjiang, China. METHODS:Sixty Uygur and 60 Han patients at 11-16 years of age (average 13.8 years old), 32 males and 28 females, with skeletal class II malocclusion wereincluded. The thickness of anterior alveolar bone and incisor labial inclination were measuredon lateralcephalometric films, and the results were analyzed using SPSS 17.0 statistical software. RESULTS AND CONCLUSION:In Han and Uygur populations, palatalalveolar bone thicknessin maxilary incisor regionwas significantly negatively correlated with the inclination of maxilary incisor (r=-0.715 for Han,r=-0.651 for Uygur,P< 0.05), while labial alveolar bone thicknessin mandibular incisor regionwas significantly positively correlated with the lower incisor inclination (r=0.902 for Han,r=0.745 for Uygur,P< 0.05). These results indicate thatthepalatal alveolar bone thicknessin maxilary incisor region decreases with the increase of the inclinationof maxilary incisor; however,thelabial alveolar bone thicknessin mandibular incisor regionincreases with the increase of the lower incisor inclination.

Objective:To investigate the expression of human telomerase reverse transcriptase(hTERT)gene in salivary gland tumors and to study its clinicopathological significance.Methods:In situ- mRNA hybridization method was used to detect the expression of hTERT mRNA in 10 cases of normal salivary gland tissues, 30 of benign salivary gland tumors and 43 of malignant salivary gland tumors.The relationship between hTERT mRNA expression and sex,age, tumor size, location, histologic differentiation of the malignant tumors was analyzed by using ?2 test.Results:hTERT expression was negative in all normal tissues. Positive rate of hTERT mRNA expression was 3.3%(1/30) and 83.7%(36/43) in benign and malignant salivary gland tumors respectively(P0.05).Conclusion:hTERT mRNA expression may be used to distinguish malignant salivary gland tumors from benign.

Aerosol and splatter formed during dental procedure were collected pre and post rinsing with Xipayi mouth rinse or 1% H2O2,cultured 48 hours with blood agar plates,counted the bacterial colonies.Both groups were effective in reducing bacterial aerosols(P 0.05).Bacterial aerosols by dental procedure can be reduced by using mouthwash pre-operationally,both Xipayi mouth rinse and 1% H2O2 are effective mouthwashes.

BACKGROUND:In the treatment of early caries, fluoride can be used for remineralization of white spot lesions. Varnish XT (durable fluoride-releasing coating) and ICON penetration resins are two new materials. Varnish XT as a new type of resin reinforced glass ionomer can be selected as mineralized material. ICON penetration resin is a high-permeability resin with good liquidity that can infiltrate by capilary action into the pores created by enamel demineralization. Low-viscosity resin is used to replace the lost hard tissue due to demineralization and occupy the micropores, so as to fil the region of enamel demineralization and prevent further development of lesions. OBJECTIVE:To study the effects of two minimaly invasive surgical treatment materials, Varnish XT and ICON penetrating resin, on the microhardness of enamel caries white spot. METHODS:Totaly 100 incisors of cows were selected, embedded with ethoxyline resin and polished. The lip side facing down served as the observation side. An area of at least 6 mm×10 mm on the enamel face was exposed, and there were five regions from incisal to dental cervix, A, B, C, D, E. After demineralization liquid for artificial caries, no treatment was adopted in region A, treatment with Varnish XT was for region B, treatment with ICON penetrating resin for region C, treatment with fluoride for region D, and region E was sealed with antacid nail. Surface micro-hardness was detected. RESULTS AND CONCLUSION: After demineralization, surface micro-hardness of regions A, B, C, D decreases remarkably as compared with region E (P < 0.05). Surface micro-hardness of regions B, C, D was higher than that of region A, and ranged as folows: C > B and D for surface micro-hardness with statistical significance (P < 0.05). There was no statistical significance of surface micro-hardness between regions B and D (P > 0.05). ICON resin infiltration, Varnish XT and fluoride have obvious improvement effects on surface micro-hardness, and ICON resin infiltration is superior to Varnish XT and fluoride.

BACKGROUND:Obturation with warm gutta-percha can achieve perfect three-dimensional root canal obturation effect. Due to specific structure of oval canal, particularly in the bypass preparation process, excessive cutting of local tooth tissue may lead to tooth tissue thinning and irregular shape. The separation equipment is the metal with good heat conduction, so the heat caused by the bypassing warm gutta-percha obturation would burn periodontal tissue remains controversial. OBJECTIVE:To investigate the changes of root surface temperature produced by two bypassing warm gutta-percha obturation for the separation instrument in oval canalin vitro by using infrared thermography. METHODS:Forty mandibular first premolars were harvested from oval canals, and were separated using stainless steel 15# K file at apical 3 mm, with the length of 3 mm. The root canal bypassing was prepared using TF nickel-titanium file under operating microscope. The teeth were randomly divided into two groups, with 20 teeth in each group, and were obturated with the Thermafil warm gutter-percha and E&Q plus warm gutta-percha vertical compaction, respectively. An infrared thermoviewer was used to measure the external root surface temperature before and after the obturation. RESULTS AND CONCLUSION:Two warm gutta-percha obturation methods used for separating instruments bypassing in the oval root canal, had both caused the rise of root surface temperature, which was less than 10℃. In the Thermafil group, the temperature changes were 3.2-8.1℃ and the average change was 4.97℃. In the vertical condensation group, the temperature changes were 5.5-9.8℃ and the average change was 7.35℃. There were significant differences in the change of root surface temperature between the two groups (P < 0.05). Thermafil warm gutter-percha obturation would increase the root surface temperature, but cannot damage periodontal tissues. It is more secure than warm gutta-percha vertical condensation.

Objective To evaluate the biological effect of tumor necrosis factor-α(TNF-α) on the proliferation and multi-directional differentiation of stem cells from rat apical papilla(SCAP).Methods SCAP was extracted by combining enzyme digestion method with tissue block method.The cells were divided into control group(TNF-α 0 ng/mL) and experimental group(TNF-α 5,10,20,50 ng/mL).The ability of proliferation of SCAP was measured by MTT method.The ability of osteogenic/dentinogenic differentiation of SCAP was measured by alizarin red staining and quantitative real-time PCR.The ability of adipogenic of SCAP was measured by oil red O staining.The expression of vascular related genes of SCAP was measured by quantitative real-time PCR.Results SCAP was consistent with the characteristics of mesenchymal stem cells and possessed the ability of multi-directional differentiation.The MTT results showed that experimental group promoted the proliferation of SCAP in comparison with the control group.The difference was statistically significant(P<0.05),and 10 ng/mL was the optimum concentration.The results of alizarin red staining showed that with the increase of the concentration of TNF-α,the mineralized nodules in the experimental group gradually became smaller,and the number of the formation decreased gradually.The results of quantitative real-time PCR showed that the expression of OC,DMP-1 and DSPP in the experimental group was significantly lower than that of the control group at 3 and 7 days,in which the expression of OC was statistically significant different(P<0.05);at 14 days,the expression of OC,DMP-1 in the experimental group was significantly lower than that of the control group(P<0.05).The result of Oil red O staining showed that with the increase of the concentration of TNF-α,the lipid droplets formation in the experimental group gradually decreased.The result of quantitative real-time PCR showed that the expression of ANGPT1,VEGFA,PECAM-1 in the experimental group was significantly lower than that of the control group(P<0.05).Conclusion TNF-α might promote the proliferation and inhibit the multi-directional differentiation of SCAP.

BACKGROUND:Due to the complexity and irregularity of bypass obturation of oval root canal and the particular stress of the post and core to the tooth, we have not yet found a reasonable post crown for dental restoration after bypass obturation of the oval root canal.
OBJECTIVE:To compare the flexural capacity of the three kinds of post-and-core repair systems (cobalt-chromium cast post and core, zirconium oxide post and core, and CAD/CAM-fabricated glass fiber post and core) after bypass obturation of the oval root canal warm gutta.
METHODS: Ninety mandibular first premolars were selected for bypass obturation of the root canal with Obtura II & System B, and then randomized into three groups that were respectively restored with cobalt-chromium cast post and core, zirconium oxide post and core and CAD/CAM-fabricated glass fiber post and core. After that, cobalt-chromium metal crown was used for ful-crown restoration. Fracture strength and fracture type were recorded in different groups.
RESULTS AND CONCLUSION: The fracture resistance was higher in the cobalt-chromium cast post and core group and zirconium oxide post and core group than the glass fiber post and core group (P < 0.05), and the former two groups had no significant difference. Cobalt-chromium cast post and core was fractured at the root of tooth, and could not be repaired; the zirconium oxide post and core was fractured at the root neck and root of tooth, which was confirmed as reparative fracture; the glass fiber post and core was fractured at the tooth neck, which could be restored. These findings indicate that the cobalt-chromium cast post and core can bear greater occlusal force, but has a higher probability of root fracture; the CAD/CAM-fabricated glass fiber post and core exhibits a lower probability of root fracture

BACKGROUND:Stem cels from the apical papila are a new kind of mesenchymal stem cels, and whether it can
be used in root regeneration is the key to the present study. OBJECTIVE:To culture rat stem cels from the apical papila and periodontal ligament stem celsin vitro, and to compare the biology behaviors of these two kinds of cels, thereby providing experimental basis for the application of stem cels from the apical papila in root regeneration. METHODS:The apical papila, as wel as the periodontal ligament tissues from the healthy mandibular teeth of young rats were digested and cultured. Immunophenotypes of stem cels from the apical papila and periodontal ligament stem cels were detected by immunofluorescence technique. Then, cel growth curves were determined by MTT method and mineralized nodule formation was observed by alizarin red staining. RESULTS AND CONCLUSION:Stem cels from the apical papila and periodontal ligament stem cels were both positive for STRO-1. Stem cels from the apical papila were positive for CD90 and weakly positive for CD146. Periodontal ligament stem cels were positive for CD146 and weakly positive for CD90. The absorbance values of stem cels from the apical papila and periodontal ligament stem cels increased with the increasing of time and became stable at 8 days. Since the 4th day, the proliferation capacity of stem cels from the apical papila was significantly stronger than that of periodontal ligament stem cels (P < 0.05). Both of stem cels are visible to have mineralized nodule formation. Compared with the periodontal ligament stem cels, stem cels from the apical papila were stained obviously deeper and had more mineralized nodules. These results show that stem cels from the apical papila have stronger proliferation capacity and mineralization ability than periodontal ligament stem cels. Cite this article:Zhao L, Yu L, Yuan P, Zhou CM, Wu PL.Stem cels from the apical papila versus periodontal ligament stem cels: biological behaviors. Zhongguo Zuzhi Gongcheng Yanjiu. 2016;20(1):113-117.

Abstract BACKGROUND: Alveolar bone deficiency wil not meet aesthetic and functional requirements for dental implants. OBJECTIVE:To observe the repair effect of passage 3 autologous bone marrow mesenchymal stem cels (BMSCs) and platelet-rich fibrin (PRF) on alveolar bone defects in rabbits. METHODS:Twenty-seven New Zealand rabbits were randomly divided into BMSCs/PRF group, PRF group and model group (n=9 per group). The left mandible incisors were extracted in al the rabbits under general anesthesia. BMSCs/PRF group was immediately implanted BMSCs/PRF composite into the alveolar socket, PRF group only implanted PRF, and model group implanted nothing. RESULTS AND CONCLUSION: In the model group, the alveolar crest and alveolar mucosa become sunken notably and narrowed. In the BMSCs/PRF and PRF groups, the thickness of alveolar bone wal, alveolar bone width, alveolar bone height difference, and bone mineral density were al increased, especialy in the former group. In addition, the trabecular arrangement was better in the BMSCs/PRF groups than the model and PRF group. Our findings indicate that alveolar socket filing with composite of BMSCs and PRF can achieve preservation of alveolar bone width and height after tooth extraction in rabbits.