[Study on promoting bone formation in osteoporotic zebrafish by lithium-doped hydroxyapatite nanowires].

PURPOSE: To observe the regulatory effect of lithium-doped hydroxyapatite nanowires on bone metabolism in osteoporotic zebrafish induced by dexamethasone. METHODS: Pure hydroxyapatite nanowires(nHA) and hydroxyapatite nanowires doped with 10% lithium ions (Li-nHA) were prepared by using hydrothermal method, and then material characterization was performed. The juvenile zebrafish cultured for 3 days(3dpf) were selected and co-cultured with nHA and Li-nHA extracts up to 7dpf. A negative(0.1% DMSO) control group was set up and transgenic zebrafish Tg(ola.sp7:nlsGFP) was used to select the best concentration for promoting bone formation. The osteoporotic zebrafish were induced by dexamethasone and incubated with nHA and Li-nHA extracts. The wild-type zebrafish was stained with alizarin red and the osteogenic differentiation was observed in transgenic zebrafish. Real-time quantitative PCR was adopted to detect osteogenic maker genes, such as zinc finger transcription factor (SP7), alkaline phosphatase (ALP), osteoprotegerin (OPG), Runt related transcription factor 2(Runx2) and osteocalcin (OCN). Statistical analysis was performed with GraphPad Prism 9.3 software. RESULTS: nHA and Li-nHA promoted bone formation and up-regulated expression levels of ALP, OCN, Runx2, SP7 and OPG of osteoporotic zebrafish. Compared with nHA, Li-nHA significantly increased the mineralization specific staining area and cumulative optical density of zebrafish bone, and the expression of osteogenic maker genes was also significantly increased. CONCLUSIONS: Doping lithium ions in nano hydroxyapatite can enhance its osteoinductive properties, and Li-nHA can effectively improve bone formation of osteoporotic zebrafish.

Sagittal maxillary growth pattern in unilateral cleft lip and palate patients with unrepaired cleft palate.

OBJECTIVE: The objective of the study was to examine the sagittal maxillary growth pattern during the mixed and permanent dentition in unilateral cleft lip and palate (UCLP) patients with unrepaired cleft palate. PATIENTS AND METHODS: A total of 30 nonsyndromic UCLP patients with unrepaired cleft palate were included, 15 of whom were in mixed dentition and 15 in permanent dentition.Cephalograms were analyzed and compared in the patients with UCLP who have operatively undergone repair with both the lip and palate as well as normal subjects. RESULTS: The UCLP patients with unrepaired cleft palate in mixed dentition showed decreased anterior-posterior length of the maxilla. The UCLP patients with unrepaired cleft palate in permanent dentition demonstrated an almost normal maxillary growth. The operated-on patients both in mixed and permanent dentitions showed maxillary retrusion as well as decreased maxillary length. CONCLUSIONS: There appears that there may be the potential normal maxillary growth in UCLP patients, and early surgical repair of the cleft palate may affect sagittal maxillary growth pattern in patients with cleft.

The effects of a newly designed twin-slot bracket on severely malpositioned teeth--a typodont experimental study.

The aims of this study were to design a twin-slot bracket featuring two horizontal slots and to examine its efficiency in tooth displacement. Based on the structure of a traditional edgewise bracket, an additional slot was added to a twin-slot bracket and the prototype products were fabricated for the typodont experiments. The orthodontic correction of malpositioned canines was conducted on a typodont to examine the efficiency of the twin-slot bracket in tooth displacement compared with a single-slot edgewise bracket. Three modalities of tooth movement requiring a heavy force moment, namely, axial rotation, mesiodistal tipping, and bodily translation, were conducted. The canine positions before and after simulation were measured and the changes identified. Statistical analysis was undertaken using a t-test to determine the significance of the differences in canine repositioning between the two bracket types. The results showed that in the twin-slot bracket group, the treatment changes in the canine position by derotation and uprighting were 40 +/- 3 and 25 +/- 2 degrees, respectively, compared with 20 +/- 5 and 10 +/- 2 degrees in the edgewise group (P < 0.01). When retracted into an extraction space with an initial 10 degrees of mesial tip, the mesiodistal angulation of the canines in the twin-slot bracket group remained unchanged while in the edgewise group the canines became distally tipped by 5 +/- 2 degrees (P < 0.01). The twin-slot bracket significantly increased the bracket width without reducing the interbracket span and therefore can generate increased force moments within the bracket, leading to an improved manipulation in tooth repositioning.

[A novel magnetic orthopedic appliance in treatment of preadolescent mild skeletal Class â ¢ patients].

PURPOSE: This study was to develop an intraoral Class Ⅲ orthopedic appliance using attractive magnetic forces, and investigate the effect of magnetic orthopedic appliance (MOA-Ⅲ) on skeletal and dental structures in mild skeletal Class Ⅲ children. METHODS: Thirty patients (12 boys and 18 girls) with mild skeletal Class Ⅲ jaw discrepancies were treated with MOA-Ⅲ. The average age was 9 years 3 months at the beginning of the treatment. The mean treatment period was 6.6 months. A paired t test was carried out to evaluate 40 parameters measured on cephalometric radiographs. Another 18 untreated patients (7 boys and 11 girls) according to upper criteria served as control group. SPSS15.0 software package was used for data analysis. RESULTS: The MOA-Ⅲ produced significant positive changes in maxillomandibular relationship. The maxilla was displaced anteriorly with clockwise rotation. The mandible showed slight downward and backward rotation. No significant changes were displayed in the length of the mandibular body and mandibular ramous. Significant labial tipping of the upper incisors and lingual tipping of lower incisors were noted after treatment. The measurement of soft tissues indicated that the upper lip moved forward and the lower lip retruded backward. In control group, most of the cephalometric measurements were not significantly changed except for some mandibular skeletal measurements and soft tissue measurements. CONCLUSIONS: By comparing to the untreated control, this type of magnetic orthopedic appliance is effective in the early treatment of mild skeletal Class Ⅲ malocclusion children.

[Preparation of lyophilized lentiviral vector of bone morphogenetic protein 2].

PURPOSE: To construct recombinant lentiviral vectors of bone morphogenetic protein 2(BMP-2) gene and prepare a stable lyophilized state. METHODS: The BMP-2 gene lentiviral vector was constructed by recombinant DNA technology and mixed with different stabilizers in an appropriate proportion and then lyophilized. The optimum stabilizer was selected according to the appearance and virus titer after being lyophilized. The quality of lyophilized product was measured by thermal stability of the virus, PCR and gene sequencing. SPSS13.0 software package was used for statistical analysis. RESULTS: Recombinant BMP-2 lentiviral vector was successfully constructed. 10% trehalose, 1% bovine serum albumin, 3%mannitol and 0.5% gelatin in group B showed good protection on BMP-2 gene lentiviral vector. The virus titer decreased 0.42 LgPFU/mL after being lyophilized, which was better than group A, C and the control group and the difference was statistically significant (P<0.05); Lyophilized protective agent made from group B still maintained a good appearance at 37 degrees centigrade after 28 days and the virus titer decreased 0.63 LgPFU/mL. The virus titer in liquid lentiviral infection control group decreased rapidly to 2.37 LgPFU/mL 1 week later and the difference between the two groups was statistically significant (P<0.05); PCR and gene sequencing showed that the target gene information after redissolve had no loss or mutation. CONCLUSIONS: Appropriate selection of lyoprotectants can effectively protect the biological stability of recombinant BMP-2 gene lentiviral vector.

[Study on the relationship between some genetic factors and peak bone mineral density in Beijing young women].

OBJECTIVE: To evaluate the relationship between the peak bone mineral density (PBMD) and vitamin D receptor (VDR), estrogen receptor (ER) allelic variants in Beijing young women. METHODS: From March, 2000 to July, 2001, one hundred and fifty-nine young healthy women (25 - 37 years old) in Beijing were voluntarily enrolled in the study. (1) BMD were measured by dual energy X-ray absorptiometry (DXEA) at lumbar and hip. (2) The polymorphism of VDR and ER genes were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). (3) The relationship between BMD and polymorphism of VDR and ER genes were examined. RESULTS: (1) Lumber BMD was positively correlated to height, weight and body mass index (BMI), whereas, the femoral neck BMD only to weight, and the other sites of hip BMD to BMI. (2) Although subjects with the VDR bb genotype had higher BMD than those with Bb genotype at lumber, femoral neck, inter and troch, no significant difference was found (P > 0.05). (3) In Ward triangle, subjects with ER PP genotype had significantly lower BMD than those in ER Pp and pp genotypes (P < 0.05). (4) Women with BbPP genotype combination had lower BMD levels at lumber and hip, and with bbPP and Bbpp genotypes combination significantly higher lumber BMD levels than BbPP genotype (P < 0.05). However, the differences of BMD among subjects with different VDR and ER genotypes became not significant after adjusting the confounder of body weight. CONCLUSIONS: (1) Body weight and BMI play important roles to PBMD of Beijing women. (2) There was no significant difference of BMD levels between VDR genotypes at any site. (3) PvuII polymorphism of ER gene was associated with low Ward triangle BMD. (4) There was significant relationship between the combination of ER and VDR polymorphisms at lumbar and hip BMD. Our data suggest that genetic variation at the ER locus, singly and in relation to the VDR locus, may influence the attainment and maintenance of peak bone mass in young women.

[Study of the mandibular growth phases and quantities in Shanghai adolescents].

PURPOSE: To study the growth phases and quantities of mandible in Shanghai adolescents. METHODS: The samples included 480 Shanghai adolescents from 8-20 years of age, 240 were male and 240 were female. Both male and female groups were divided into 6 consecutive developmental periods according to cervical vertebral maturation stages. Their cephalometric radiographs were measured and analyzed. Independent-sample t test was conducted by SPSS 15.0 software package. RESULTS: The total mandibular length (Co-Gn) increased significantly from CVMS1 to CVMS2 and CVMS3 to CVMS4 in both male and female group. For male the maximum increase was from CVMS3 to CVMS4 (P<0.01,average 9.54 mm), while female was from CVMS1 to CVMS2(P<0.01,average 9.09 mm). The height of mandibular ramus (Co-Go) increased continuously from CVMS2 to CVMS5 in male group, the significant increase was observed from CVMS2 to CVMS3 (P<0.01, average 8.80 mm). The significant increase in female group was observed from CVMS1 to CVMS2 (P<0.01, average 6.51 mm). In male group, the greatest increase of the mandibular base length (Go-Pog) appeared from CVMS3 to CVMS4 (P<0.01, average 7.55 mm), while in female group, it occurred from CVMS1 to CVMS2 (P<0.01, average 5.73 mm). CONCLUSIONS: The growth amounts of total mandibular length (Co-Gn), mandibular base length (Go-Pog) and ramus length are different at every CVM stages in male and female groups. The present finding will help to make reasonable diagnosis and treatment planning.

[Effect of semi-fixed Twin-block appliance on temporomandibular joint remodeling].

PURPOSE: To evaluate quantitatively the effect of semi-fixed Twin-block appliance on the temporomandibular joint remodeling during the Class II malocclusion treatment. METHODS: Twenty two Class II division 1 patients treated with semi-fixed Twin-block appliance were included. Pre- and post-orthopedic treatment cephalometric data were analyzed with SPSS13.0 software package for paired t test. RESULTS: The mandibular condylar growth was directed superiorly(2.7mm) and posteriorly (3.6mm) (P<0.01), the glenoid fossa was displaced in a inferior(1.5mm) (P<0.01) and posterior (0.8mm)(P<0.05) direction, the effective TMJ changes showed a pattern similar to condylar growth in a superior(4.2mm) and posterior(2.7mm) direction(P<0.01), the mandibular rotation was slightly clockwise(P>0.05). CONCLUSIONS: The application of semi-fixed Twin-block appliance shows its effectiveness on patients' compliance and the remodeling in temporomandibular joint, contributing to the correction of sagittal jaw relationship discrepancy.

[The effectiveness of asymmetric extraction in treatment of Class II division 1 malocclusions].

PURPOSE: To analyze hard and soft tissue profile changes before and after asymmetric extraction treatment of Angle Class II division 1 malocclusion. METHODS: Thirty patients of Angle Class II division 1 malocclusions (11 males, 19 females, average age 13.6 years) were divided into two groups according to their extraction approach. In asymmetric extraction group, 2 first maxillary premolars and 1 first mandibular premolar were extracted. In the control group, all 4 first premolars were extracted. Lateral cephalometric radiographs were taken before and after treatment to compare hard and soft-tissue changes between the two groups, and the cephalometric measurements were analysed by SAS6.12 software package for independent sample t test. RESULTS: In comparison of the changes between the two groups, significant differences in dentoskeletal measurements were observed with NAPog, SNA, ANB, MP-SN and with the inclinations of the upper and lower incisors (P<0.01). Significant differences in soft-tissue changes were also observed in the thickness of upper lip, the Z angle (P<0.01) and the nasolabial angle (P<0.05). Compared to the profile before treatment,only inclination of lower incisors changed significantly after treatment (P<0.01). CONCLUSIONS: Asymmetric extractions is feasible in treatment of Class II division 1 malocclusions evidenced by retractions of both upper and lower incisors and improves sagittal soft-tissue profile. Supported by Research Fund of Science and Technology Commission of Shanghai Municipality (Grant No.08DZ2271100).

[Identification of cell apoptosis during premaxillary suture expansion in rat].

PURPOSE: To identify the incidence of cell apoptosis during premaxillary suture expansion. METHODS: Forty SD rats were randomly allotted into experimental and control groups. The experimental animals were subjected to premaxillary suture expansion by a helix spring with (200+/-10)g initial force. They were sacrificed on day 1, 2, 3 and 5(n=5). The sequence of histological changes and osteoblast proliferation in the premaxillary suture were evaluated by hematoxylin and eosin(HE) and toluidine blue staining. Cellular apoptosis was identified by ssDNA immunostaining. The difference between experimental and control groups was analyzed by Student's t test with SPSS 15.0 software package. RESULTS: The width of premaxillary suture was enlarged 1 day after expansion and osteoblasts were accumulated along the suture. After 2 days of stretching, the number of the osteoblasts increased to the peak. New bone deposition was identified on day 3 and projection of suture with bone trabeculae was apparent on day 5. ssDNA immunostaining showed few apoptotic cells in premaxillary suture during natural growth. Upon expansion, cell apoptosis was identified in osteoblasts along the suture and the osteocytes embedded in premaxillary bone, especially on day 2 and day 3(P<0.01). CONCLUSION: Apoptotic cell death might regulate the growth modification of premaxillary suture upon mechanical stretching.

[Establishment of cervical vertebral skeletal maturation of female children in Shanghai].

PURPOSE: To establish a method for quantitatively evaluating skeletal maturation of cervical vertebrae of female children in Shanghai. METHODS: The samples were selected from lateral cephalometric radiographs of 240 Shanghai girls, aged 8 to 15 years. The parameters were measured to indicate the morphological changes of the third (C3) and fourth (C4) vertebrae in width, height and the depth of the inferior curvature. The independent-sample t test and stepwise multiple regression analysis were used to estimate the growth status and the ratios of C3, C4 cervical vertebrae by SPSS 15.0 software package. RESULTS: The physical and morphological contour of C3, C4 cervical vertebrae increased proportionately with the increment of age. The regression formula for indicating cervical vertebral skeletal age of female children in Shanghai was expressed by the equation Y= -5.696+8.010 AH3/AP3+6.654 AH3/H3+6.045AH4/PH4 (r=0.912). CONCLUSION: The regression formula resulted from morphological measurements quantitatively indicates the skeletal maturation of cervical vertebrae of female children in Shanghai.

[Effect of high pull J hook headgear on root resorption during orthodontic treatment].

PURPOSE: The purpose of this study was to evaluate the effect of high pull J hook headgear(HPHG) on root resorption of maxillary incisors during orthodontic treatment. METHODS: Sixty female adolescent subjects who had finished orthodontic treatment were selected. They were either Class I or Class II division I cases treated with standard edgewise appliances. Half of the patients(30 cases) had an additional HPHG to assist upper anterior teeth retraction. They were matched to the other 30 cases with age and type of malocclusion. Panoramic radiographs taken before and after the orthodontic treatment were used to evaluate the degree of root resorption on upper incisors. Chi(2) test was used for statistical analysis. RESULTS: The incidence of root resorption on upper incisors was significantly increased after orthodontic treatment in both HPHG and non-HPHG groups (P<0.01). Compared to the non-HPHG group, more teeth in HPHG group showed moderate or severe root resorption (P<0.01). Some cases even encountered extremely severe root resorption. CONCLUSION: A combination of HPHG might lead to more severe root resorption on maxillary incisors during orthodontic treatment.

[The feasibility and reliability of Pancherz's analysis in evaluating the treatment effects of bite-jumping on skeletal class II malocclusion].

OBJECTIVE: This study was designed to conduct an in-depth evaluation on Pancherz's analysis. METHODS: A typical Class II case with bite-jumping therapy was selected for the whole process of Pancherz's Analysis. The skeletal growth modification and dental compensation were examined and portioned for their respective contribution to the correction of excessive overjet and Class II molar relationship. RESULTS: The following traits and properties of Pancherz's analysis were found: (1) A fixed reference system characterized by SN and OLp was established which led to an accurate detection of the moving objects. (2) Skeletal and dental changes were separated for evaluation, which resulted in a true assessment of the bite-jumping on growth pattern modification.(3) A segmental examination for dental changes indicated the magnitude of skeletal modification. Conclusion Pancherz's analysis is a feasible and reliable evaluation system which could reflect with accuracy the skeletal and dental effects caused by bite-jumping therapy.

[The effects of combined reverse Nance and TPA on reinforcement of anchorage].

PURPOSE: To evaluate the effects of combined reverse Nance and TPA on anchorage control. METHODS: 16 female adults with Class II division 1 malocclusion were treated with the combined mechanism of reverse Nance and TPA in an attempt to reinforce molar anchorage. Cephalometric analysis and model measurements were conducted for the assessment of anchorage control. RESULTS: The mesial movement of the upper first molars were minimized within 1/5 extracted space, parameters such as UMVD, MP-FH, ANS-Me remained unchanged, indicating the molar anchorage was controlled effectively. CONCLUSION: The modified combination of reverse Nance and TPA might be effective in anchorage forcement.

[An immunohistochemical study on neovascularization in TMJ during mandibular advancement].

OBJECTIVE: Neovascularization is proved to be closely correlated with ossification. This study was designed to determine the biochemical path through which the new bone formation is enhanced in TMJ during mandibular protrusion. METHODS: SD Rats were fitted with bite-jumping appliances to allow for an adequate advancement of the mandible. The animals were sacrificed 3, 7, 14, 21 and 30 days, respectively, after placement of the appliances. Slides with TMJ tissue were prepared for biochemical procedure. Immunohistochemical approaches were adopted to examine neovascularization in TMJ by immuno-localizing the newly formed endothelial cells. Computer-assisted image analysis system was applied to quantify the positive immunoreaction. RESULTS: Neovascularization in connective tissue close to the condyle was 200% higher in the experimental groups than that in the control, and, within the bony tissue of the condyle, neovascularization in experimental animals was found to be 103% higher than that of the control. CONCLUSION: Increased neovascularization triggered by mandibular protrusion might intensify new bone formation in condyle and glenoid fossa and finally lead to a growth adaptation of TMJ to bite-jumping therapy.

[A clinical study of twin-wires on anchorage reinforcement].

OBJECTIVE: This clinical trial was designed to impose a simultaneous placement of large-size stainless steel round wire and small-size NiTi, and to assess its effect on anchorage reinforcement. METHODS: Twin-arch wires were in place for relief of severe crowding. Distalization of canines were well conducted with support of rigid wire, together with a simultaneous repositioning of upper lateral incisors facilitated by resilient wire. The linear distance between APo and the first molar, together with other parameters, was measured for the evaluation of anchorage consolidation. RESULTS: Anchorage molars and anteriors, as well as the integrity of dental arches remained unchanged upon fulfillment of crowding relief, which was justified by statistical analysis. CONCLUSION: Application of Twin-wires leads to a concurrence of efficient crowding relief and sufficient anchorage consolidation.