Cone-beam CT evaluation of bone mass in the external oblique line of the mandible in adolescents with different cervical vertebral bone ages / 中国组织工程研究

BACKGROUND:The application of miniscrew in adolescents is increasing day by day,but at present,there are few studies on bone mass in the external oblique line of the mandible in adolescents at home and abroad,and there is no systematic study on bone mass in the external oblique line of the mandible in adolescents in different growth and development periods. OBJECTIVE:To measure the bone mass in the external oblique line of the mandible in adolescents with different cervical vertebral bone ages using a cone-beam CT and to investigate the difference of bone mass in the external oblique line of the mandible in adolescents with different cervical vertebral bone ages and the correlation between bone mass in this area and the cervical vertebral bone age. METHODS:The cone-beam CT data of 105 adolescent patients before orthodontic treatment were collected and divided into CS3 group(n=24),CS4 group(n=26),CS5 group(n=29)and CS6 group(n=26)using the cervical vertebral maturation method.The adolescent mandibular buccal shelf was reconstructed by Mimics Medical 21.0 software.The width of buccal bone at 6 and 11 mm under the cemento-enamel junction and the bone height at 4 and 5 mm buccal to the cemento-enamel junction of right mandibular first and second molars were measured.The measured data were statistically analyzed.The measurement was made on four planes:plane 1 is the plane where the proximal mesial root of the mandibular right first molar is located;plane 2 is the plane where the distal mesial root of the mandibular right first molar is located;plane 3 is the plane where the proximal mesial root of the mandibular right second molar is located;and plane 4 is the plane where the distal mesial root of the mandibular right second molar is located. RESULTS AND CONCLUSION:In each group,the bone width on the buccal side of the external oblique line increased gradually from the first molar proximally to the second molar distally in adolescents,and the width of buccal bone at 6 and 11 mm under the cemento-enamel junction showed significant difference among different layers(P<0.05).The bone width of buccal bone at 11 mm under the cemento-enamel junction was greater than that at 6 mm.The bone height on the buccal side of the external oblique line increased gradually from the first molar proximally to the second molar distally in all four groups,and the bone height at 4 and 5 mm buccal to the cemento-enamel junction showed significant differences at different layers(P<0.05).The bone height at 4 mm buccal to the cemento-enamel junction was greater than that at 5 mm.On the fourth plane,the bone width at 11 mm buccal to the cemento-enamel junction was smaller in the CS3,CS4,and CS5 groups than in the CS6 group(P<0.05).On the third plane,the bone heights at 4 mm and 5 mm buccal to the cemento-enamel junction were smaller in the CS3 and CS4 groups than in the CS6 group(P<0.05).On the fourth plane,the bone height at 5 mm buccal to the cemento-enamel junction was smaller in the CS3 and CS4 groups than in the CS6 group(P<0.05).On the fourth plane,the bone height at 4 mm buccal to the cemento-enamel junction was smaller in the CS3 group than in the CS6 group(P<0.05).Spearman correlation analysis showed that there was no correlation between bone mass and the cervical vertebral bone age,except that there was a weak correlation between bone mass at some measurement sites and cervical vertebral bone age.To conclude,the bone mass in the external oblique area of the mandible in adolescents does not change significantly with the increase of cervical vertebral bone age.The buccal side of the mesial root and distal root of the mandibular second molar in the external oblique area of CS3-CS6 adolescents meets the requirement of bone mass for miniscrew implantation,which is a site available for miniscrew implantation.

Advances in the p75 neurotrophic factor receptor in stomatology / 中华口腔医学杂志

The p75 neurotrophic factor receptor is a low affinity receptor for neurotrophic factors and plays an important role in nerve growth, development and function integrity. It is closely related to dental development, oral and maxillofacial tumor, nerve repair and tissue engineering. It shows good prospect for application. In this paper, the research progress of p75 neurotrophic factor receptor in Stomatology is reviewed.

The effects of BMP9 combined with NGF on the osteogenic differentiation of C3H10T1/2 mesenchymal stem cells / 实用口腔医学杂志

Objective:To investigate the effects of BMP9 combined with NGF on the osteogenic differentiation of mesenchymal stem cells(MSCs).Methods:Recombinant BMP9 adenovirus was transfected into C3H10T1/2 cells.The cells were treated by GFP,NGF,BMP9 and BMP9 + NGF respectively.The expression level of COL1,RUNX2 was detected by RT-PCR and Western blot,ALP activity was examined by ALP kit 3,12,24,48 hours,3 and 7 days after treatment,respectively.Results:The ALP activity of BMP9 + NGF group was the highest among the 4 groups.The difference in the groups firstly appeared at 3 h after treatment.The highest expression level of RUNX2 and COL1 was detected in BMP9 + NGF group.Conclusion:NGF and BMP9 may synergisticly promote osteogenic differentiation at the early stage of osteogenic induction of C3H10T1/2 cells.

The capacity and biological characteristic of the p75 neurotrophin receptor-positive ectomesenchymal stem cell in vitro / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the biological characteristic of ectomesenchymal stem cells (EMSC) and the differentiation of p75(+)EMSC and influencing factors.</p><p><b>METHODS</b>The immunohistochemical staining method was used to observe the migration of EMSC from 12.5 d SD rat embryonic facial process. Then EMSC was labeled by p75 neurotrophin receptor, and the cell cycle and stem cell surface antigens of the p75(+) EMSC was examined.</p><p><b>RESULTS</b>Immunohistochemical staining showed that stem cells from the cranial neural crest migrated to embryonic rat facial process at 12.5 days. The sorting rate of the p75(+)EMSC was 6.1%. The proportion of the p75(+)EMSCs' S/G2/M phase was stable during subculture. The special substances CD29, CD146 and Stro-1 were marked for p75(+)EMSC, and the expressions of the markers were all higher (> 90%) in p75(+) EMSC.</p><p><b>CONCLUSIONS</b>The embryonic tooth did not start to grow on the conception 12.5 days of SD rats. The p75(+) EMSC after sorting had stable proliferation ability and had stem cell characteristics during subculture and didn't start differentiation.</p>

A primary study of pulse Nd:YAG laser on morphology and bonding of enamel and dentin / 第三军医大学学报

Objective To investigate the morphology and bonding of enamel and dentin conditioned by 35% phosphoric acid and pulse Nd:YAG laser.Methods A total of 52 human premolars were selected,40 of which were divided into four groups randomly: group A [enamel treated with 35% phosphoric acid(Scotchbond,3M) for 30 s];group B [enamel treated with pulse Nd:YAG laser(Evlaser Friendly A4 Italy) for 20 s];group C(dentin treated with 35% phosphoric acid for 15 s);group D(enamel treated with pulse Nd:YAG laser for 15 s).The tensile bond strength(TBS) were determined.Except 4 out of 12 human premolars without any treatment,8 were divided into 4 groups and were treated with the method mentioned above.The surfaces of 12 human premolars were observed under SEM.Results The highest TBS was obtained in group A in comparison with the other 3 groups(P0.05).The smear layer on enamel and dentin could be removed after conditioned by both phosphoric acid and pulse Nd:YAG laser.The honeycomb structures were observed on all enamel but less regularly in lased group.Almost all the orifices of dentinal tubules were open in the acid group and sealed or half-sealed in lased group.Conclusion The pulse Nd:YAG laser did not contribute to bonding of enamel,but could improve the bonding of dentin and seal most of the orifices of dentinal tubules,which reduced the harmful stimulation to the dental pulp.