[Effects of mid-palatal suture opening and midfacial bony structure changes induced by maxillary skeletal expansion in adults].

PURPOSE: To analyze the opening of mid-palatal suture, transverse changes in dental and dentoalveolar measurements and shift of midfacial bony structures induced by maxillary skeletal expansion (MSE) with cone-beam CT (CBCT), and to evaluate the effect of maxillary skeletal expansion and its influence on adjacent bony structures in adults. METHODS: The study sample consisted of 12 adult patients with maxillary transverse deficiency (4 males, 8 females) at a mean age of (21.17±4.13) years old. All patients were treated with MSE. After treatment, the posterior crossbite was corrected, and the width of the maxillary arch was achieved the optimal width. Pre- and post-treatment CBCT exams were taken before and after MSE treatment. Multiplanar coronal and axial slices obtained from CBCT images were used to measure the changes in transverse widths, angular changes and tooth inclination with Dolphin Imaging 11.9. SPSS 26.0 software package was used for statistical analysis. RESULTS: After MSE treatment, the anterior nasal spine width increased by (2.38±1.01) mm, posterior nasal spine width increased by (2.25±1.08) mm (P<0.01). The inter-crown and inter-apex distance at the first molar increased by (5.56±1.38) mm and (4.14±1.29) mm, respectively (P<0.01). No significant difference was seen in terms of tooth inclination of the first molar(P>0.05). Pterygoid process angle, pterygoid process width, anterior inter-maxillary distance, upper and lower inter-zygomatic distance were significantly larger after treatment (P<0.01), while the inter-temporal distance and bilateral zygomaticomaxillary angle remained unchanged(P>0.05). CONCLUSIONS: MSE has a favorable effect in adult patients with parallel skeletal expansion of the mid-palatal suture achieved after expansion. The teeth present with certain buccal inclination but show no significant movement relative to the alveolar bone. The midfacial bony structures also shift in three-dimensional under the effect of the expansion force.

[Generation and validation of inducible osteoblast-specific Stat3 knockout mice].

PURPOSE: Based on the Cre-Loxp gene knockout system, this study intended to construct tamoxifen-inducible STAT3 conditional knockout mice and verify the knockout efficiency. METHODS: The inducible osteoblasts-specific Stat3 knockout mice Stat3Col1ERT2 were obtained by hybridization through C57 mice of Stat3fl/fl and Col1 creERT2. Bone mesenchymal stem cells(BMSCs) of these mice were isolated and cultured with or without 4-hydroxytamoxin(4-OTH), to verify the effect of Stat3 knockout in vitro by real-time quantitative PCR and Western blotting in the level of mRNA and protein. Meanwhile, wild type and Stat3Col1ERT2 mice were both intraperitoneally injected with tamoxifen, the expression of STAT3 in the maxillary alveolar bone was observed by immunofluorescent staining to confirm the knockout effect in vivo. Statistical analysis was conducted with SPSS 24.0 software package. RESULTS: Real-time quantitative PCR and Western blotting results demonstrated that mRNA(P<0.05) and protein levels of STAT3 were significantly decreased (P<0.05) in BMSCs derived from Stat3Col1ERT2 mice by 4-OHT induced knockout in vitro. Immunofluorescent staining indicated that STAT3 expression was significantly reduced(P<0.05) in osteoblasts of the maxillary alveolar bone in Stat3Col1ERT2 mice. CONCLUSIONS: This study successfully constructed the inducible osteoblasts-specific Stat3 gene knockout mice, which helped investigators control the time and space of gene knockout, therefore providing new insights and guidance for research fields of orthodontic tooth movement, distraction osteogenesis and jaw fractures in the future.

[Expression of STAT3 in alveolar bone during orthodontic tooth movement in rats].

PURPOSE: To study the changes of expression of signal transducer and activator of transcription 3 (STAT3) during orthodontic tooth movement (OTM). METHODS: Twenty six-week-old SD rats were selected, the upper left first molars were moved by coil spring and lasted for 7 days. The maxillary tissues were obtained at 0, 1, 3, 7 d and subjected to histological study. Statistical analysis was performed using SPSS 16.0 software package. RESULTS: The main changes in alveolar bone during orthodontic tooth movement included significant increase in osteoblast number and bone formation in the tension area, and bone resorption in the pressure area. The positive cells of osteocalcin in the tension area increased during OTM. The expression of STAT3 increased in the tension area at 3 d and 7 d in comparison with that at 0 d. CONCLUSIONS: Orthodontic force can stimulate alveolar bone remolding. The expression of STAT3 in the tension area may have effects on alveolar bone remolding during orthodontic tooth movement.

[The effect of estrogen on adipogenic differentiation of rat bone mesenchymal stem cells].

PURPOSE: In this study, 10⁻9 mol/L 17 ß-estradiol (E2) was applied in the adipogenic differentiation of rat bone mesenchymal stem cells (rBMSCs) and the effect of E2 was explored. METHODS: Rat BMSCs were obtained from the femurs and tibias of SD rats. 10⁻9 mol/L E2 was involved in the adipogenic differentiation of rBMSCs. Oil red staining, real time PCR and Western blot were carried out to detect the effect of 10⁻9 mol/L E2 on adipogenic differentiation of rBMSCs. The data was statistically analyzed using SPSS 19.0 software package. RESULTS: The use of 10⁻9 mol/L E2 decreased the amount of lipid droplets in rBMSCs and weakened the expression of adipogenic related genes and proteins like C/EBP α, C/EBP ß, PPAR γ, aP2, and ARDP, which were significantly lower than the adipogenic induced group. CONCLUSIONS: The use of 10⁻9 mol/L E2 inhibited adipogenic differentiation of rBMSCs significantly in vitro.

[Osteogenic gene expression of human periodontal ligament stem cells during osteogenic induction].

URPOSE: To isolate and identify the human periodontal ligament stem cells, evaluate osteogenetic capacity, and investigate the changes of osteogenic bone related gene expression in mineralized medium at different times. METHODS: PDLSCs were isolated by tissue culture and magnetic activated cell sorting. Immunofluorescence staining was used for identification. The general situation of osteogenesis was assessed with alkaline phosphatase (ALP) and alizarin red staining. Real-time PCR was used to detect the expression of genes in osteoinduction. SPSS12.0 software package was used for data analysis. RESULTS: Tissue culture with magnetic cell sorting could isolate high-purity human periodontal ligament stem cells. During the osteogenic process, the expression of FoxO1 and Runx2 firstly increased and then decreased, ALP and OCN gene levels continued to increase. CONCLUSIONS: Similar to osteogenesis, ALP, Runx2, FoxO1 and OCN are regularly expressed during osteogenic induction.

[Changes of the microarchitecture of alveolar bone due to different duration of ovariectomy: a Micro-CT study in rats].

PURPOSE: To study the changes of microarchitecture of alveolar bone due to different duration of ovariectomy in rats. METHODS: Twenty-four virgin Sprague-Dawley rats were randomly assigned to ovariectomy group (OVX) or sham-ovariectomy group (sham). OVX rats were subjected to bilateral ovariectomy and sham-ovariectomy was conducted in sham rats. Six rats of each group were sacrificed respectively 3 months and 6 months after surgery. The right semi-maxilla of all rats were scanned by Micro-CT, and the inter-radicular alveolar bone of the maxillary first molar was analyzed. Statistical analysis was carried out with SPSS 16.0 software package. RESULTS: Two-dimensional and three-dimensional reconstructed images of the alveolar bone showed porotic changes in rats both 3 months and 6 months after ovariectomy, including thinner, looser trabeculae and expanded bone marrow. When compared with corresponding sham rats, BMD, BV/TV and Tb.Th of alveolar bone significantly decreased in OVX rats both 3 months and 6 months after ovariectomy (P<0.05). Tb.N and Tb.Sp significantly increased in both OVX groups (P<0.05). When compared with 3 months after ovariectomy, the rats 6 months after ovaroectomy shared deceased BMD, BV/TV and Tb.Th (P<0.05) and increased Tb.N (P<0.05). CONCLUSIONS: Bone loss and deterioration of trabeculae of alveolar bone aggravates with the extended duration of ovariectomy in OVX rats.

[The effect of estrogen on proliferation and osteogenic differentiation of rat bone marrow mesenchymal stem cells].

PURPOSE: Different concentrations of 17 ß-estradiol (E2) were applied in the osteogenic differentiation of rat bone mesenchymal stem cells (BMSCs), and the proliferation and apoptosis of BMSCs were explored. METHODS: BMSCs were obtained from the femurs and tibias of SD rats. The proliferation curve was conducted to rBMSCs in culture medium containing 0, 10(-9), and 10(-7) mol/L 17 ß-estradiol by CCK-8 for 7 days. Annexin V and PI for flow cytometry were applied to detect the impact of E2 on apoptosis of rBMSCs. After 1, 7, 11 and 14 days of osteogenic induction, the activity of alkaline phosphatase (ALP) was assayed; ALP staining was performed on day 7 and day 14; Alizarin red staining for calcium deposits was carried out on day 21. Concentrations of 0, 10(-9), and 10(-7) mol/L 17 ß-estradiol were administrated to rBMSCs for real-time PCR of osteogenic related genes on day 1, 3, 5, 7, 14, and day 21. The data was statistically analyzed using SPSS 19.0 software package. RESULTS: The effect of 17 ß-estradiol on proliferation and apoptosis of rBMSCs was not obvious. However, after osteogenic induction, the ALP activity and Alizarin red staining were significantly stronger in the groups containing 17 ß-estradiol. Especially, the use of 17 ß-estradiol with the concentration of 10(-9) mol/L enhanced the expression of osteogenic related genes like RUNX2, ALP, COL I, and OCN, which was significantly higher than other groups. CONCLUSIONS: 17 ß-estradiol promotes osteogenic differentiation of BMSCs in a dose-dependent pattern in vitro.

[Exploration for micro-osteotomy assisted orthodontic treatment of skeletal Class III malocclusions with alveolar hypoplasia in the lower anterior region].

PURPOSE: To investigate the changes of periodontal conditions after micro-osteotomy assisted lower incisor decompensation for skeletal Class III malocclusions with alveolar hypoplasia in the lower anterior region. METHODS: The sample consisted of 22 cases diagnosed as skeletal Class III malocclusions with alveolar hypoplasia in the lower anterior region, selected from consecutive patients of Department of Oral & Cranio-maxillofacial Science of Shanghai Ninth People's Hospital during 2009-2012. The samples were divided into 2 groups; G1 comprised 10 patients who accepted micro-osteotomy assisted lower incisor decompensation; G2 comprised 12 patients who chose traditional pre-surgical decomposition. The changes of periodontal conditions of both groups were evaluated with the help of cone-beam CT(CBCT). Data was processed using SAS8.02 software package. RESULTS: For subjects in G1, during the micro-osteotomy assisted pre-surgical orthodontics, no significant difference was found in the amount of root resorption of lower incisors.But labial and lingual vertical alveolar bone loss were 2.60 mm and 2.22 mm; alveolar bone thickness increased by 3.05 mm on the labial side and decreased by 0.88 mm on the lingual side (P<0.05). Better periodontal conditions were reserved compared with those of G2. CONCLUSIONS: Micro-osteotomy assisted pre-surgical orthodontics was much safer than traditional orthodontics for skeletal Class III malocclusions with alveolar hypoplasia in the lower anterior region.

[Effects of mechanical tensile stress on the expression of ICAM-1 mRNA in osteoblasts differentiated from rBMSCs].

OBJECTIVE: To investigate the correlation between mechanical tensile stress and the expression of ICAM-1 mRNA in osteoblasts differentiatd from rBMSCs and elucidate the mechanism for osteoclastogenesis regulated by osteoblasts in bone modeling and remodeling during the process of orthodontic tooth movement. METHODS: rBMSCs-derived osteoblasts were isolated and cultured in vitro, and were subjected to static mechanical tensile stress of 1,3,5 kPa or dynamic tensile stress of 3, 5 kPa at 0.017 Hz with the use of cellular tension-stress system for 24 h. Controls were without any stress. Cells were collected at 0 h, 3 h, 6 h, 9 h, 12 h, 24 h and 48 h after stress loading. The expression patterns of ICAM-1 mRNA were examined by semiquantitative RT-PCR assay. RESULTS: ICAM-1 mRNA level significantly decreased after mechanical tensile stress loading, either dysamic or static, compared with controls; the effects of inhibition positively correlated with the magnitude of stress (5 kPa>3 kPa>1 kPa). The inhibition effects of dynamic tensile stress groups exceeded the corresponding static stress (3,5 kPa dynamic stress>3,5 kPa static stress respectively). The expression of ICAM-1 mRNA significantly decreased at 3 h, reached the minimun transcription, as low as 23% of that of control, at 12 h, and then slightly rebounded and stayed at a considerably lower and stable level. CONCLUSION: Mechanical tensile stress can regulate osteoclastogenesis by inhibiting the expression of ICAM-1 in osteoblasts derived from rBMSCs, it can lead to a better understanding of the molecular basis for osteoblast-osteoclast communication in bone resorption induced by application of mechanical tensile stress during orthodontic tooth movement.

[Effects of osteoporosis on experimental tooth movement in aged rats].

OBJECTIVE: To examine the experimental tooth movement and recruitment of new osteoclasts in aged variotomized (OVX) rats. METHODS: Eighty-two 3-month female virgin health rats were divided into two groups. Each group was divided into seven sub-groups of tooth movement: 0,1,3,5,7,10 and 14 days. The tooth movement and the population of osteoclasts were measured and comparatively analyzed. RESULTS: The osteoporosis rats showed larger and faster tooth movement (P<0.05). In the osteoporosis group, the instantaneous tooth movement lasted longer time and traversed larger distance, the delay period was shorter, the population of osteoclasts was larger and displayed a faster recruitment. CONCLUSION: These findings indicate that osteoporosis accelerates tooth movement in aged OVX rats.