Adolescent ; Humans ; Male ; Tooth Ankylosis ; etiology ; surgery ; Tooth Extraction ; methods ; Tooth Root ; Wounds and Injuries ; complications

OBJECTIVETo explore the effect and practical value of repairing the alveolar defects with tissue engineering technique and investigate the influence of the generated new bone on the orthodontic tooth movement.

METHODSThe marrow stromal cells of rats were separated, cultured in vitro and induced to osteoblast-like cells. The osteoblast-like cells were implanted onto the ceramic bovine bone. Then the complex was implanted into the alveolar defect in one side of the rat's mandible. The other side of the mandible served as control. Eight weeks later, the orthodontic appliances were placed between the first molar and incisors of SD rats to move the first molar forward. The tooth movement and root resorption of the molar were observed.

RESULTSWe found that the tooth movement in the experimental area was faster than that in the normal alveolar bone (P < 0.05). The root resorption and the alveolar bone height loss were less than that in the control area (P < 0.05).

CONCLUSIONSThe tissue-engineered bone did not have negative influences on tooth movement. The repair of alveolar bone defect by tissue engineering approach may be used in craniofacial surgery and orthodontics.

Animals ; Bone Substitutes ; Cattle ; Cells, Cultured ; Female ; Male ; Mandibular Injuries ; pathology ; surgery ; Rats ; Rats, Sprague-Dawley ; Tissue Engineering ; Tooth Movement Techniques

Objective To evaluate the feasibility of 3-(4-~(18)F-fluorobenzyl)-8,9-dimethoxy-1,2,3,4-tetrahydrochromeno [3,4-c]pyridin-5-one ( is F-FDTP) as a potential dopamine D4 receptor PET imaging agent.Methods ~(18)F-FDTP solution in ethanol-physiological saline was incubated with calf serum to test its in vitro stability through the determination of radiochemical purity.Normal rats were injected intravenously with ~(18)F-FDTP and then sacrificed at 2,5,10,15,30,60 and 120 min after anesthesia.Blood,organs and brain tissue samples were collected.All samples were weighed and measured for radioactivity.The uptake of samples was expressed as percentage activity of injection dose per gram of tissue ( % ID/g).Results The stability of ~(18)F-FDTP was satisfactory and its radiochemical purity was above 95% after incubation 120 min at 37℃ in calf serum.The biodistribution showed that ~(18)F-FDTP could penetrate through the blood-brain barrier and selectively accumulate in striatum,hypothalamus,frontal certex,hippocampus,cerebellum,where the D_4 receptor was reportedly located.The radioactivities in hippocampus,hypothalamus,striatum,frontal cortex,cerebellum,pons were (0.42±0.03),(0.46±0.05),(0.54±0.04),(0.39±0.04),(0.45±0.06),(0.35±0.04) %ID/g,respectively,2 min post injection.And there was difference between the normal biodistribution results and the blocking experimental results:(0.36 ±0.05),( 0.33±0.05 ),(0.55±0.05 ),(0.30±0.07 ),(0.34±0.07 ) and (0.32±0.04) % ID/g in hippocampus,hypothalamus,striatum,frontal cortex,cerebellum and pons,respectively.Conclusions ~(18)F-FDTP can penetrate through the blood-brain barrier and selectively accumulate in striatum,hypothalamus,frontal cortex,hippocampus,cerebellum,where the D_4 receptor was known to concentrate.These preliminary results suggest that ~(18)F-FDTP is a potential dopamine D_4 receptor imaging agent and further studies are needed.

OBJECTIVETo measure the vertical height of mesio-distal marginal ridge to cusp in posterior teeth, which may be helpful to brackets positioning.

METHODSThe study groups comprised of 60 patients (30 men, 30 women, mostly aged 12-14 years) who underwent orthodontic treatment without tooth extraction and matched the Andrews normal occlusion standard after treatment. Study model of each patient was made. Three-dimensional laser measurer was used to evaluate the vertical height of mesio-distal marginal ridge to mesial cusp in posterior teeth. The data were stored in a personal computer and submitted to statistical analysis of paired t test.

RESULTSNo statistical significant difference was found in the same teeth between men and women. Not only in maxilla but also in mandible, there was no significant difference between the left and the right (P>0.05). The average vertical height of maxillary first premolars was (1.70+/-0.50) mm, the maxillary second premolars was (1.24+/-0.45) mm, and for maxillary first molars, the result was (0.83+/-0.40) mm. The difference between each result was statistically significant (P9< 0.01). The average vertical height of mandibular first premolars was (2.25+/-0.45) mm, the mandibular second premolars was (1.55+/-0.45) mm, and for mandibular first molars, the result was (1.18+/-0.40) mm. The difference between each result was statistically significant (P<0.0 1).

CONCLUSIONThe vertical height of brackets position in posterior teeth should be considered to guarantee that mesio-distal marginal ridges of deferent posterior teeth located in the same plane, so that satisfying goal could be achieved, If the vertical height in the first molar was X mm, the vertical height in the second premolar should be (X+0.5) mm, and (X+1.0) mm might be suit for the first premolar.

Bicuspid ; Dental Occlusion ; Female ; Humans ; Male ; Mandible ; Maxilla ; Molar ; Tooth ; Tooth Extraction ; Tooth Movement Techniques

OBJECTIVEIn this experiment, genes sensitive to mechanical stretch in osteoblast like cells were cloned through subtractive hybridization technique.

METHODSTwo dimensional mechanical stretch with deformation of 12% and frequency of 6 cycles was loaded on human osteoblastic like cell line Saos-2. Complementary deoxyribonucleic acid (cDNA) library of cells was constructed 12 h after loading, acting as tester. cDNA library of cells without loading was constructed, acting as driver. A subtractive cDNA library osteoblastic like cell stimulated with mechanical stretch was constructed through subtractive hybridization technique.

RESULTSOf clones randomly selected from this library, fifteen genes were identified to be the differentially expressed genes. Comparing with the sequences published in GeneBank via Internet, two sequences located in chromosome 9 and 18 respectively were identified to be novel, which were named as stretch sensitive gene 1 and stretch sensitive gene 2.

CONCLUSIONIt is an efficient approach to clone and study genes relative to mechanical stretch through subtractive hybridization technique.

Cell Line ; Cloning, Molecular ; Gene Expression Profiling ; Gene Library ; Humans ; Nucleic Acid Hybridization ; Osteoblasts ; physiology ; Stress, Mechanical

OBJECTIVETo evaluate the outcome of the treatment of malocclusion with mandibular congenital missing teeth guided by Bolton index.

METHODS26 class I and II cases (males 10, females 16) were chosen in this study. Guided by Bolton index, enamel stripping, denture and two types of tooth extraction were used in the treatment.

RESULTSNormal Bolton index was achieved and the results of treatment were satisfactory.

CONCLUSIONSMalocclusion with mandibular congenital missing teeth can be treated successfully guided by Bolton index.

Adolescent ; Adult ; Anodontia ; complications ; Cephalometry ; methods ; standards ; Child ; Female ; Humans ; Male ; Malocclusion ; etiology ; therapy ; Orthodontics, Corrective ; methods ; standards ; Treatment Outcome

OBJECTIVETo investigate the orthodontic retention and adjustment of the occlusion after orthognathic surgery.

METHODS18 patients were divided into three groups. Group I: Cases with skeletal Class I bimaxillary protrusion treated by subapical osteotomy; Group II: Cases with skeletal Class II mandibular retrusion treated by sagittal split mandibular advancement surgery; Group III: Cases with skeletal Class III treated by Le Fort I osteotomy on maxilla and sagittal split osteotomy on mandible. There were 6 patients in each group. Three kinds of orthodontic elastic tractions were used based on different categories of malocclusion and different types of operation.

RESULTS18 patients attained functional occlusion after the orthodontic occlusion adjustment. There was no relapse and malocclusion by surgery.

CONCLUSIONIntermaxillary elastics based on different categories of occlusion and different kinds of surgery can improve the occlusion after orthognathic surgery and attatin the functional occlusion.

Adult ; Cephalometry ; Dental Occlusion ; Humans ; Male ; Malocclusion ; Mandible ; Maxilla ; Orthognathic Surgery ; Osteotomy ; Osteotomy, Le Fort

OBJECTIVETo investigate the osteoblast-like characteristics of human periodontal ligament cells affected by elastic stress in vitro, and the role of corebinding factor a 1 (cbfa1) in alveolar bone formation during orthodontic tooth movement.

METHODSRat dig-labeled cbfa1 cDNA probe was prepared from SD rat osteoblasts cultured in vitro. Human periodontal ligament cells were cultured on the elastic bottom plate and stimulated by elastic stress using mechanical loading system for cultured cells in vitro. The expression of cbfa1 mRNA was detected by in situ hybridization method.

RESULTSCbfa1 mRNA express in human periodontal ligament cells stimulated by elastic stress and did not express in normal human periodontal ligament cells.

CONCLUSIONIt is suggested that elastic stress plays a role in the differentiation process from human periodontal ligament cells to osteoblast-like cells. Cbfa1 is a transcription factor in alveolar bone remodeling during orthodontic tooth movement.

Adolescent ; Animals ; Cells, Cultured ; Child ; Core Binding Factor alpha Subunits ; DNA-Binding Proteins ; genetics ; Elasticity ; Humans ; Periodontal Ligament ; cytology ; metabolism ; RNA, Messenger ; analysis ; Rats ; Transcription Factors ; genetics

OBJECTIVETo analyze the effects about inclinations of the second and the third molars in patients treated with or without premolar extractions.

METHODSFifty-six adolescents were chosen and divided into the first premolar extraction and non-extraction groups, 30 and 26 patients respectively. The pre-treatment and post-treatment panoramic radiographs were made. Angles between long axis of the third molar and the occlusal plane (the second molar alike), and long axis of the second and the third molar were measured and evaluated.

RESULTSThe maxillary and mandibular third molar angulations were all improved after treatment in two groups. Compared with non-extraction group, the average changes of angle between long axis of the third molar and the occlusal plane increased significantly in maxilla and mandible (P < 0.05). Average changes of angles between long axis of the second and the third molar decreased and had statistically significant difference (P < 0.05). The change of angle between long axis of mandibular second molar and the occlusal plane had statistically significant difference (P < 0.05), but there was no statistically significant difference in maxillary second molar (P > 0.05).

CONCLUSIONThe first premolar extraction in orthodontic treatment could improve the third molar angulations and it would promote the eruption of the third molar.

Adolescent ; Bicuspid ; Dental Occlusion ; Female ; Humans ; Male ; Mandible ; Maxilla ; Molar ; Molar, Third ; Radiography, Panoramic ; Tooth Eruption ; Tooth Extraction

Here in this paper introduced is an analysis system for X-ray cephalometry developed through Windows platform,which includes three parts: data input, cephalometry analysis & calculation, and display & printing of diagnostic results. It has been applied in orthodontic department of Stomatological Hospital of the Fourth Military Medical University, and it is quite convenient for doctors' cephalometry diagnosis.
Cephalometry ; instrumentation ; Computers ; Humans ; Medical Records Systems, Computerized ; instrumentation ; Orthodontics ; instrumentation ; methods ; Radiographic Image Enhancement ; instrumentation ; Radiography ; instrumentation ; Software