China ; Humans ; Orthodontics ; trends

Adult ; Computer-Aided Design ; Humans ; Male ; Malocclusion ; diagnostic imaging ; therapy ; Orthodontic Appliance Design ; Orthodontic Brackets ; Orthodontic Wires ; Radiography, Panoramic

Objective:To compare soft-tissue morphology changes by cephalometric measurements be-tween extraction and non-extraction orthodontic treatment in borderline cases.Methods:The samplesconsisted of 33 cases selected as borderline cases by 5 orthodontic specialists.They were divided into 21extraction cases(including 13 four first premolar extraction cases and 8 four second premolar extractioncases)and 12 non-extraction cases by checking patients' treatment records.Conventional cephalometricanalysis was made to compare soft tissue structures before and after orthodontic treatments and the samecomparison was made between two different extraction patterns.Results:No statistical difference wasfound in pretreatment soft-tissue morphology between extraction and non-extraction groups divided fromborderline cases.The PosBs/FH of the four first premolars extraction group was smaller than that of non-extraction group,and the Ns-Sn-Pos of the four first premolars extraction group was smaller than that offour second premolar extraction group.None of the post-treatment soft-tissue measures showed significantstatistical differences between four first premolars extraction group and non-extraction group,but therewere 6 items showed significant statistical differences between four second premolars extraction group andnon-extraction group.Compared with extraction and non-extraction treatments,the most significant soft-tissue changes were:PosBs/FH,LL-SnPos,and Bs-EP.Conclusion:Although pre-treatment soft-tissuemorphology of second premolar extraction group was close to that of non-extraction group,the post-treat-ment soft-tissue morphology of first premolar extraction group became closer to that of non-extractiongroup.Compared with non-extraction treatment,the more significant changes caused by extraction treat-ment were located in the lower lip and chin,but not the upper lips.

OBJECTIVETo analyze effects of non-surgical treatment on subjects of 12-20 years old with severe skeletal Class III deformity and to directly evaluate dental and facial profile changes.

METHODSEighteen patients with severe skeletal Class III malocclusion (male 5, female 13), diagnosed as indication for orthognathic surgery, were included in the study. The average age was 14.6 +/- 2.5 years old., with age range from 12 years old to 20 years old. 12 cases were treated with Tip-Edge straight-wire technique and 6 cases with Begg light wire technique. The average treatment time was 2.5 +/- 0.8 years. The selection criteria included: (1) mesial or superior mesial Class III molar relationship, with maxillary first molar occlude the buccal groove of the mandibular second molars (2) no mandibular shift (3) ANB < -1.5 degrees (4) high angle cases with average value of SN-MP 34.9 degrees +/- 5.9 degrees, 4 cases present with openbite (5) concave facial profile (6) originally classified as surgery cases. Lateral cephalometric films taken at the beginning and the end of the treatment were analyzed with traditional cephalometric analysis. The arithmetic mean (Mean) and standard deviation (SD) were calculated for each variable. Paired t-test was performed to evaluate the significant treatment change.

RESULTSNormal overjet and overbite were established with proclination of upper incisors and retroclination of lower incisors. Inclination of upper incisors was increased 5.9 degrees when measured with the angle of upper incisor to SN plane (P < 0.01). Inclination of lower incisors was decreased 6.6 degrees when measured with the angle of lower incisor to mandibular plane (P < 0.001). Negative value of the distance difference of upper lip and lower lip to Sn-Pg' at the beginning of treatment changed to positive value with significant difference (P < 0.001).

CONCLUSIONSuccessful treatment effects could be obtained with non-surgical therapy in severe skeletal Class III malocclusion in permanent dentition. Remarkable soft-tissue change was noted after the treatment and concave facial profile changed to straight profile.

Adolescent ; Adult ; Child ; Female ; Humans ; Male ; Malocclusion, Angle Class III ; therapy ; Orthodontics, Corrective

OBJECTIVEThe alveolar bone density quantitative measuring system was established on the basis of grey level measuring on standardized-exposed direct digital periapical radiograph by referring to an aluminum step wedge with the aid of computer technique. We tested it's accuracy and sensibility by measuring a series of specimens and made it possible to estimate the area density of hydroxyl-phosphorite (HP) in the alveolar bone with the system.

METHODSThe average grey level intensity of 19 specimens containing different amount of HP within certain area was measured with the system. The equivalent aluminum thickness (EAT) and corrected grey level intensity (CGL) of each specimen were calculated according to known grey level intensity of the aluminum step wedge and it's corresponding thickness. The liner regression equations between EAT, CGL and HP density (mg/mm2) were established. We put the values of EAT and CGL into the equations and calculated the corresponding values of estimated HP density. The bias ratios of estimation were then calculated. We measured two randomly chosen specimens 10 times respectively to calculate the system's measurement error range, then the sensibility of the system for measuring HP density was calculated according to the regression equations.

RESULTSEAT and CGL were significantly correlated with HP density. When EAT was larger than 0.67 mm or CGL larger than 41, the system's bias ratio of estimated HP density was lower than 5%. When we estimated the HP density with the use of EAT, the system could effectively check out a HP density change larger than 0.17 mg/mm2, with the use of CGL, a HP density change larger than 0.18 mg/mm2 could be effectively checked out.

CONCLUSIONThe accuracy and sensibility of the quantitative alveolar bone density measuring system are acceptable, it can be widely used to compare alveolar bone density longitudinally and cross-sectionally.

Alveolar Process ; Bone Density ; Humans ; Minerals ; Phosphates

OBJECTIVETo establish the normal MESH diagrams of Chinese in Beijing, and to build a computerized MESH analysis system for orthodontic practice.

METHODSTwenty-eight subjects with normal occlusion were selected in Beijing and their lateral cephalograms were taken at the age of thirteen and eighteen, respectively. Individual MESH diagrams were then established for each subject mainly according to Moorrees' method from the cephalograms orientated in estimated natural head position. Male and female normal MESH diagrams were created. A computerized MESH analysis system was also developed.

RESULTSThe normal MESH diagrams of Chinese in Beijing, thirteen and eighteen years old respective, were established. The computerized MESH analysis system was constructed and used in orthodontic patients.

CONCLUSIONSMESH analysis is a proportional analysis method. It can show the results directly, succinctly and holistically. It is also a favorable complement and amendment to the commonly used angle and linear X-ray analysis methods.

Adolescent ; Asian Continental Ancestry Group ; Cephalometry ; methods ; Dental Occlusion ; Female ; Humans ; Image Processing, Computer-Assisted ; methods ; Male ; Radiography ; Skull ; anatomy & histology ; diagnostic imaging

OBJECTIVETo analyze the mechanics in correction of skeletal class III malocclusion with Multiloop Edgewise Arch Wire (MEAW).

METHODS15 patients with skeletal class III malocclusion were treated with MEAW technique. Cephalometric analysis was performed with pre-treatment and post-treatment cephalograms. Paired t-test was conducted to assess the treatment effects.

RESULTSL6-XI decreased by 2.87 mm, L6/MP increased by 8.60 degrees, L1-XI decreased by 2.60 mm, OP/MP increased by 2.33 degrees. Skeleton changed a little. There was no significant change in the soft tissue.

CONCLUSION(1) Dento-alveolar compensation is the main change after the treatment by MEAW technique; (2) The improvement in molar relationship and overjet is achieved with upright and distal movement of the lower posterior teeth; (3) The lower anterior teeth moved lingually and protracted. Occlusal plane is flattened.

Adolescent ; Adult ; Cephalometry ; Dentition, Permanent ; Female ; Humans ; Male ; Malocclusion, Angle Class III ; therapy ; Orthodontic Wires ; Orthodontics, Corrective ; methods

OBJECTIVETo evaluate dento-skeletal and soft-tissue profile changes after extraction of lower second molars and treatment using fixed appliances in severe class III subjects.

METHODSFourteen patients with severe skeletal class III malocclusion (male 4, female 10, age rang 12.0 - 17.1 years old, mean age 13.3 +/- 0.8), diagnosed as requiring orthognathic surgery, but rejected surgical therapy were included in the study. Lateral cephalometric films taken at the beginning and end of treatment were analyzed using Pancherz analysis and a traditional cephalometric analysis.

RESULTSAfter active treatment, inclination of lower incisors was decreased 11.7 degrees when measured to the mandibular plane (P < 0.001). A negative value of the distance between upper and lower lip position to SnPg' at the beginning of treatment changed to a positive value (P < 0.001).

CONCLUSIONSThe results of the current preliminary study suggest that success in the treatment of some severe class III deformity in the permanent dentition can be achieved with fixed appliances and extraction of lower second molars. A remarkable soft-tissue change was noted after the treatment and concave facial profiles changed to straight profiles.

Adolescent ; Cephalometry ; Child ; Face ; anatomy & histology ; Female ; Humans ; Male ; Malocclusion, Angle Class III ; therapy ; Molar ; surgery ; Orthodontics, Corrective ; methods ; Tooth Extraction

OBJECTIVETo analyze the morphological characters of Angle's Class III malocclusion patients and the relationship between characters and treatment options.

METHODSA total of 472 Class III patients were collected during 1997-2000. The standardized coordinates' values of the patients were obtained by Procrustes superimposition (PS). Cluster analysis was carried out to divide the patients into different subdivisions and the relationship between treatment options and subdivisions was analyzed.

RESULTS472 patients were divided into 14 subdivisions with special characters. The morphological templates were formed by computer. There were certain relationships between characters and treatment options.

CONCLUSIONThe mechanism of malocclusion of different Class III patients are not necessarily same. The typing has significance to choose the treatment method.

Female ; Humans ; Male ; Malocclusion ; Malocclusion, Angle Class III ; Orthodontic Appliances

OBJECTIVETo investigate the relapse of incisor alignment after orthodontic treatment and possible factors which may related to its stability.

METHODS72 finished cases with full records selected from orthodontic clinic of Peking University School of Stomatology composed the sample. The follow-up lateral head films and study casts were taken at least 2 years after orthodontic treatment. The cephalograms were measured by computerized program and the study casts measured by caliper.

RESULTSThe upper Irregularity Index decreased from (11.5 +/- 5.02) mm before treatment to (2.01 +/- 1.39) mm after treatment and then increased to (3.46 +/- 1.69) mm in the follow-up stage. The lower Irregularity Index decreased from (7.24 +/- 44.35) mm before treatment to (1.75 +/- 1.04) mm after treatment and then increased to (3.39 +/- 1.78) mm in the follow-up stage. The changes are significant statistically. The changes of jaw in the sagittal and vertical directions as well as the related changes of the position of lower incisors, the decrease of the lower canine arch width, Bolton Index and sex all have statistically significant relation with the changes of the lower Irregularity Index after retention.

CONCLUSIONSCompared with lower arch, the alignment in upper arch is more stable in the follow-up stage. The results suggest that some possible factors may have correlations with the change of lower arch crowding during the follow-up stage.

Adolescent ; Child ; Dental Arch ; pathology ; Female ; Follow-Up Studies ; Humans ; Male ; Orthodontics, Corrective ; Recurrence ; Tooth Migration