Objective: To study the differences of the superficial masseter muscle morphology characteristics between adult high-angle and low-angle facial skeletal types. Methods: The subjects consisted of 37 yellow race adults,17 of them with high-angle facial skeletal type and 20 with low-angle. Ultrasound scanning was used to measure the perimeter, area, width, thickness, and length of masseter muscle. All the items were measured under relaxed, maximal clenching and maximal protrusive mandibular position.Results:①In the various mandibular positions, the masseter muscle size of adults with high-angle facial skeletal type was smaller than that of those with low-angle.②Except for the changes of width from the relaxed to maximal clenching position and from the relaxed to maximal protrusive position(P0.05).③Stature and weight influenced the size of the masseter muscle.Conclusion:The masseter muscle size of adult with high-angle facial skeletal type is smaller than that of those with low-angle.

BACKGROUND:Implant stability is mainly influenced by peri-implant inflammatory stimulation.
OBJECTIVE:To build a beagle model of peri-implantitis under orthodontic force and to observe the bone remodeling of the Beagle dog model.
METHODS: Micro-implants were randomly implanted into the maxilary interradicular region at the center of the mesial and distal roots of bilateral P2, P3, P4 and M1 of Beagle dogs. One side served as a loaded micro-implant with peri-implantitis under 100 g of orthodontic force at 1, 2, 3, 4 weeks of peri-implantitis, and the force lasted for 1 month. After that, the animals were kiled to prepare specimens with micro-implants. Bone-to-implant contacts were calculated and histological changes of the bone interface under continuous orthodontic force at different stages of peri-implantitis were observed under light microscope.
RESULTS AND CONCLUSION:There were a large number of inflammatory cels after micro-implants were implanted with silk thread ligation to the cervical part. Over time, inflammatory cels were gradualy diffused to the tip of micro-implant, and there were a great quantity of colagenous fibers, osteocytes and active bone remodeling. When the inflammation was diffused to the tip of micro-implant after 2 weeks of peri-implantitis, woven bones composed of newly formed trabeculae appeared, and imflammatory cels dispersed. The medulary cavity was irregular after colagen fibrils absorption, and there were 3-4 layers of osteoblasts in the bone lacunae, with active bone formation. These findings indicate that the Beagle model of pure titanium peri-implantitis under orthodontic force was successfuly built in the experiment, and bone formation became active at 2 weeks after modeling.

Objective To evaluate the effectiveness of Typodont-based table clinic competition (TCC) on undergraduate orthodontic education. Methods Students who have finished basic orthodon-tic courses made diagnosis,treatment strategy and performed orthodontic treatment for malocclusion cases on Typodonts. A self-design questionnaire was employed to investigate their perception to this pedagogy. Results The majority of participants(82.2%-92.9%) highly evaluated Typodont-based TCC. Conclu-sions Typodont-based TCC course is conducive to arousing students' study internets and to promoting association between theory and practice.

OBJECTIVETo study the effects of pulsed ultrasound (PUS) and pulsed electromagnetic fields (PEMF) on the secretion of extracellular matrix from a culture complex during in vitro chondrogenesis.

METHODSAll the rat bone marrow mesen- chymal stem cell pellets were cultured in achondrogenic medium. Different intensities of PUS (100, 150, and 200 mW · cm⁻²) and PEMF (1, 2, and 5 mT) were applied to the cell pellets for 2 weeks. Group N was cultured without PUS and PEMF stimu- lation as control. The culture medium was collected after 2 weeks of culture. Enzyme-linked immunosorbent assay (ELISA) was used to detect the type of collagen and glycosaminoglycan (GAG) in the culture medium.

RESULTSPUS increased the secreting-type collagen and GAG from cell pellets compared with group N (P < 0.05), whereas there was no difference in different intensities (P > 0.05). PEMF had no significant effect on the secretion of the type of collagen (P > 0.05). A PEMF of 1 mT had no significant effect on the secretion of GAG (P > 0.05). A PEMF 2 and 5 mT decreased the secretion of GAG (P < 0.05).

CONCLUSIONTo prevent the secretary of extracellular matrix may play a role in chondrogenic effect of PEMF.

Animals ; Bone Marrow Cells ; radiation effects ; Cells, Cultured ; Chondrogenesis ; radiation effects ; Electromagnetic Fields ; Extracellular Matrix ; Glycosaminoglycans ; Hematopoietic Stem Cells ; Mesenchymal Stromal Cells ; radiation effects ; Rats ; Ultrasonic Waves

Objective To study the influence factors of the release rate of benorilate from sustained release matrix tablets. Methods The matrix tablets of benorilate were prepared by using hydroxypropylmethylcellulose (HPMC) as the matrix material. The effects of the contents of HPMC, polyvinyl pyrrolidone (PVP), and microcrystaline cellulose (MCC), and the method of preparation on in vitro drug release were studied by evaluating the n value in the Peppas equation. Results The increasing HPMC content led to decrease of benorilate release. However, PVP and MCC used in this experiment accelerated the benorilate release from the tablets. The drug released from the tablet prepared by dry method was faster than that by wet method. Conclusion The contents of HPMC, PVP, and MCC, especially HPMC, have effects on the release rate of benorilate, but the two preparation methods have less effect.

It is to address torquing an individual tooth using a gate spring. The gate spring is made of a rectangular stainless steal wire, in the shape of a gate, which is incorporated to the archwire by spot welding. Torque is generated by the combined effects of the gate spring and the archwire. After 2-3 months, the gate spring can obviously torque individual tooth.
Orthodontic Appliance Design ; Orthodontic Brackets ; Orthodontic Wires ; Tooth ; Tooth Movement Techniques ; Torque

OBJECTIVETo investigate the development of third molar embryo and establish the normal value of posterior arch length of adolescence in Chengdu.

METHODSThe samples consisted of 40 males and 41 females with Class 1 dentitions, normal second molar occlusion, no history of orthodontic treatment, and good facial balance. Cephalometry and statistic analysis were conducted for all the subject.

RESULTSThe normal value of posterior arch length of maxilla in male was(16.52 +/- 2.35) mm and in female was(16.42 +/- 2.55) mm. The normal length of mandible was(13.00 +/- 2.44) mm in male and(12.43 +/- 2.18) mm in female. But statistic analysis showed no gender difference. Most of the third molar embryo had been formed and their tooth crowns had been calcified, the occurrence ratio was 84.0% in maxilla and 85.2% in mandible. Most of them located in the middle and inclined mesially.

CONCLUSIONThe data obtained in this study will be valuable for our clinical practice and be helpful for the study concerning dento-facial growth and development.

Adolescent ; Alveolar Process ; anatomy & histology ; diagnostic imaging ; Cephalometry ; Child ; Dental Arch ; anatomy & histology ; diagnostic imaging ; Dental Occlusion ; Dentition ; Female ; Humans ; Male ; Mandible ; anatomy & histology ; diagnostic imaging ; Maxilla ; anatomy & histology ; diagnostic imaging ; Molar, Third ; anatomy & histology ; diagnostic imaging ; Radiography ; Reference Values ; Tooth Migration

OBJECTIVEThe purpose of this study was to compare the differences of craniofacial characteristics of adult high-angle and low-angle facial skeletal types.

METHODSThe subjects consisted of 37 yellow race adults (17 high-angle, 20 low-angle). Fifty-three items of cephlometic radiographs were analyzed.

RESULTSThe angle of N-S-Ar and N-S-Ba, the distance of Ptm-A, Co-Go, Po-NB, and S-Go, and the thickness of the mandibular symphysis in high-angle group were smaller than these in low-angle group. The angles of SN-OP, FH-OP, PP-OP, SN-MP, FH-MP, PP-MP, S-Ar-Go, mandibular angle(Ar-Go-Me), Y-angel and SUM, the distance of S-Co, N-Me, and ANS-Me in high-angle group were greater than these in low-angle group. The index of FHI, N-ANS/N-Me, and N-ANS/ANS-Me were smaller, and ANS-Me/N-Me larger in high-angle group. Although the means of Go-Po and FH-RP were smaller in high angle group, but no statistical difference were found.

CONCLUSIONThe craniofacial morphology of adult high-angle and low-angle facial skeletal types demonstrated significant differences, especially in lower facial form.

Adolescent ; Adult ; Asian Continental Ancestry Group ; Cephalometry ; Dental Occlusion ; Facial Bones ; anatomy & histology ; diagnostic imaging ; Female ; Humans ; Male ; Maxilla ; anatomy & histology ; diagnostic imaging ; Radiography ; Reference Values ; Skull ; anatomy & histology ; diagnostic imaging

OBJECTIVEThe purpose of this study was to investigate the effects of Fränkel II appliance on the upper airway of children.

METHODSThe subjects consisted of 20 patients with Angle Class II, division I malocclusion (10 males and 10 females). The ages of all cases were ranged in 9-10 years. Each experimental subject was also served as self-control and cephalometric analysis was conducted.

RESULTSCompared with the results of pretreatment, the distance of PNS-Ba, SPP-SPPW, P-T, V-LPW and the Mcnamara line increased remarkably.

CONCLUSIONThe Fränkel II appliance can improve the sagittal dimensions of the upper airway in children.

Cephalometry ; Child ; Female ; Humans ; Male ; Malocclusion, Angle Class II ; pathology ; therapy ; Orthodontic Appliances, Functional ; Orthodontics, Corrective ; instrumentation ; Pharynx ; anatomy & histology ; Radiography ; Respiratory System ; anatomy & histology ; Skull ; diagnostic imaging

OBJECTIVEThe purpose of this study was to study the changes of available spaces of posterior arch segments in mandible dentitions (ASPAS) from ages of 11 to 20 years, which would provide information on normal growth and development of the dental arches in teenagers in Chengdu area.

METHODSThe data were derived from systematically collected preorthodontic lateral cephalograms of 526 patients, including 232 males and 294 females from the Orthodontic Department of West China College of Stomatology, Sichuan University during the period of 1999-2000 (aged 11-20 years). The values of ANB angle, FH-MP, ASPAS were obtained using the cephalometric analysis. Afterwards, the growth changes of ASPAS from the subjects and their correlations with age, gender, angle malocclusion types and vertical skeletal patterns were analyzed.

RESULTSASPAS was related to age and class II angle malocclusion. Though gender was not associated with ASPAS, significant differences in curves of ASPAS were found between males and females. The growth changes of ASPAS in the patients with skeletal Class III malocclusion were more obvious than in patients with Class I and II malocclusion.

CONCLUSIONOur results reveal that significant differences were demonstrated in growth change values in posterior available spaces of patients with different races and angle malocclusion types.

Adolescent ; Asian Continental Ancestry Group ; Dental Arch ; anatomy & histology ; pathology ; Dentition ; Female ; Humans ; Male ; Malocclusion ; diagnostic imaging ; pathology ; Mandible ; anatomy & histology ; diagnostic imaging ; pathology ; Orthodontics, Corrective ; Pilot Projects ; Radiography ; Reference Values