Efficacy of vertical control by using mini-implant anchorage in maxillary posterior buccal area for Angle class Ⅱ extraction patients / 北京大学学报(医学版)

OBJECTIVE@#To investigate the efficacy of vertical control by using conventional mini-implant anchorage in maxillary posterior buccal area for Angle class Ⅱ extraction patients.@*METHODS@#Twenty-eight Angle class Ⅱ patients [9 males, 19 females, and age (22.6±2.8) years] were selected in this study. All of these patients were treated by using straight wire appliance with 4 premolars extraction and 2 mini-implant anchorage in maxillary posterior buccal area. In this study, the self-control method was used to measure and analyze the lateral radiographs taken before and after orthodontic treatment in each case, the main cephalometric analysis items were related to vertical changes. The digitized lateral radiographs were imported into Dolphin Imaging Software (version 11.5: Dolphin Imaging and Management Solutions, Chatsworth, California, USA), and marked points were traced. Each marked point was confirmed by two orthodontists. The same orthodontist performed measurement on the lateral radiographs over a period of time. All measurement items were required to be measured 3 times, and the average value was taken as the final measurement result.@*RESULTS@#Analysis of the cephalometric radiographs showed that, for vertical measurements after treatment, the differences of the following measurements were highly statistically significant (P < 0.001): SN-MP decreased by (1.40±1.45) degrees on average, FMA decreased by (1.58±1.32) degrees on average, the back-to-front height ratio (S-Go/N-Me) decreased by 1.42%±1.43% on average, Y-axis angle decreased by (1.03±0.99) degrees on average, face angle increases by (1.37±1.05) degree on average; The following measurements were statistically significant (P < 0.05): the average depression of the upper molars was (0.68±1.40) mm, and the average depression of the upper anterior teeth was (1.07±1.55) mm. The outcomes indicated that there was a certain degree of upper molar depression after the treatment, which produced a certain degree of counterclockwise rotation of the mandibular plane, resulting in a positive effect on the improvement of the profile.@*CONCLUSION@#The conventional micro-implant anchorage in maxillary posterior buccal area has a certain vertical control ability, and can give rise to a certain counterclockwise rotation of the mandible, which would improve the profile of Angle Class Ⅱ patients.

Analysis of single-nucleotide polymorphism of Sonic hedgehog signaling pathway in non-syndromic cleft lip and/or palate in the Chinese population / 北京大学学报(医学版)

OBJECTIVE@#To study the relationship between Sonic hedgehog (Shh) associated single-nucleotide polymorphism (SNP) and non-syndromic cleft lip and/or palate (NSCL/P), and to explore the risk factors of cleft lip and/or palate. Many studies suggest that the pathogenesis of NSCL/P could be related to genes that control early development, in which the Shh signaling pathway plays an important role.@*METHODS@#Peripheral blood was collected from 197 individuals (100 patients with NSCL/P and 97 healthy controls). Haploview software was used for haplotype analysis and Tag SNP were selected, based on the population data of Han Chinese in Beijing of the international human genome haplotype mapping project. A total of 27 SNP were selected for the 4 candidate genes of SHH, PTCH1, SMO and GLI2 in the Shh signaling pathway. The genotypes of 27 SNP were detected and analyzed by Sequenom mass spectrometry. The data were analyzed by chi-squared test and an unconditional Logistic regression model.@*RESULTS@#The selected SNP basically covered the potential functional SNP of the target genes, and its minimum allele frequency (MAF) was >0.05: GLI2 73.5%, PTCH1 91.0%, SMO 100.0%, and SHH 75.0%. It was found that the genotype frequency of SNP (rs12674259) located in SMO gene and SNP (rs2066836) located in PTCH1 gene were significantly different between the NSCL/P group and the control group. Linkage disequilibrium was also found on 3 chromosomes (chromosomes 2, 7 and 9) where the 4 candidate genes were located. However, in the analysis of linkage imbalance haplotype, there was no significant difference between the disease group and the control group.@*CONCLUSION@#In China, NSCL/P is the most common congenital disease in orofacial region. However, as it is a multigenic disease and could be affected by multiple factors, such as the external environment, the etiology of NSCL/P has not been clearly defined. This study indicates that Shh signaling pathway is involved in the occurrence of NSCL/P, and some special SNP of key genes in this pathway are related to cleft lip and/or palate, which provides a new direction for the etiology research of NSCL/P and may provide help for the early screening and risk prediction of NSCL/P.

Novel Mutation of Cleidocranial Dysplasia-related Frameshift Runt-related Transcription Factor 2 in a Sporadic Chinese Case / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Cleidocranial dysplasia (CCD) is an autosomal dominant disease that affects the skeletal system. Common symptoms of CCD include hypoplasia or aplasia of the clavicles, delayed or even absent closure of the fontanels, midface hypoplasia, short stature, and delayed eruption of permanent and supernumerary teeth. Previous studies reported a connection between CCD and the haploinsufficiency of runt-related transcription factor 2 (RUNX2). Here, we report a sporadic Chinese case presenting typical symptoms of CCD.</p><p><b>METHODS</b>We made genetic testing on this sporadic Chinese case and identified a novel RUNX2 frameshift mutation: c.1111dupT. In situ immunofluorescence microscopy and osteocalcin promoter luciferase assay were performed to compare the functions of the RUNX2 mutation with those of wild-type RUNX2.</p><p><b>RESULTS</b>RUNX2 mutation was observed in the perinuclear region, cytoplasm, and nuclei. In contrast, wild-type RUNX2 was confined in the nuclei, which indicated that the subcellular compartmentalization of RUNX2 mutation was partially perturbed. The transactivation function on osteocalcin promoter of the RUNX2 mutation was obviously abrogated.</p><p><b>CONCLUSIONS</b>We identified a sporadic CCD patient carrying a novel insertion/frameshift mutation of RUNX2. This finding expanded our understanding of CCD-related phenotypes.</p>

Analysis of treatment templates of Angle's Class III malocclusion patients / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To analyze the morphological characters of Angle's Class III malocclusion patients and the relationship between characters and treatment options.</p><p><b>METHODS</b>A 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.</p><p><b>RESULTS</b>472 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.</p><p><b>CONCLUSION</b>The mechanism of malocclusion of different Class III patients are not necessarily same. The typing has significance to choose the treatment method.</p>

Accuracy and sensibility of computer -aided alveolar bone density quantitative measuring system / 华西口腔医学杂志

<p><b>OBJECTIVE</b>The 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.</p><p><b>METHODS</b>The 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.</p><p><b>RESULTS</b>EAT 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.</p><p><b>CONCLUSION</b>The 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.</p>

Intruding upper incisors using mini-screw anchorage in patients with gummy smile / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the effectiveness of mini-screw anchorage on intruding upper incisors in patients with gummy smile.</p><p><b>METHODS</b>Sixteen female patients (mean age: 23.8 years) were involved in this study. The mini-screws were placed between upper lateral incisors and canines on both sides for intruding upper incisors together with fixed appliance. The cephalometric analysis was carried out.</p><p><b>RESULTS</b>Totally 63 teeth in 16 patients were intruded successfully and the deep overbite was decreased by (2.74 +/- 2.00) mm (P < 0.001). The distance from the edge of the upper incisor to palatal plane was reduced by (5.00 +/- 2.76) mm (P < 0.001), and the incisors were proclined by (9.34 +/- 10.06) degrees (P < 0.01). The duration for intrusion was 10.8 months on average.</p><p><b>CONCLUSIONS</b>It was practicable and effective to improve gummy smile by intruding upper incisors with mini-screw implant.</p>

Preliminary investigation of Tip-Edge Plus technique in the treatment of Class III malocclusion / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the craniofacial and occlusal changes of Class III cases treated with Tip-Edge Plus Technique.</p><p><b>METHODS</b>Thirteen Class III patients (6 girls and 7 boys, mean age 14.9 years) with mandibular protrusion were selected. All the patients were four premolar extraction cases and treated with Tip-Edge Plus technique. Cephalometric analysis was performed to evaluate the changes before and after treatment.</p><p><b>RESULTS</b>After treatment, Wits changed from (-2.50 +/- 1.40) mm to (-1.00 +/- 0.85) mm and ANB changed from (-0.61 +/- 1.41) degrees to (1.31 +/- 1.66) degrees (P < 0.05). UL-E and LL-E were decreased significantly from (7.55 +/- 1.24) mm to (4.82 +/- 1.05) mm and from (10.16 +/- 2.43) mm to (6.03 +/- 2.01) mm respectively (P < 0.01). The incisors were retracted. A remarkable soft tissue change was noted after the treatment. The difference between the distance of the upper lip and lower lip to SnPg' at the beginning of treatment changed from (-1.57 +/- 1.24) mm to (0.62 +/- 1.24) mm (P < 0.01). FCA changed from (2.62 +/- 1.53) degrees to (7.02 +/- 2.21) degrees .</p><p><b>CONCLUSIONS</b>With Tip-Edge Plus straight-wire technique and light continuous force, anterior teeth could be tipped distally and lingually quickly. The hard and soft tissues changed accordingly.</p>

Preliminary clinical application of Tip-Edge Plus appliance in the treatment of Class II patients / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the craniofacial and occlusional changes of Class II patients treated with Tip-Edge Plus technique.</p><p><b>METHODS</b>Twelve Class II patients (7 girls and 5 boys, mean age 14.3 years) with bimaxillary or maxillary protrusion were selected. All the patients were four first premolar extraction cases and treated with Tip-Edge Plus technique. Cephalometric analysis was performed to evaluate the changes before and after treatment.</p><p><b>RESULTS</b>After treatment, the profile was greatly improved. UL-E, LL-E were decreased significantly (P < 0.01) and incisors were retracted (P < 0.05). Upper molars moved forward slightly (P > 0.05).</p><p><b>CONCLUSIONS</b>The anchorage control in Tip-Edge Plus technique was effective without extraoral force, palatal arch and implants. Under very light force, the crown of anterior teeth tipped distally and lingually quickly. In the final stage, it was possible to achieve both desired root uprighting and crown torque.</p>

The differences of hard tissue changes and stability of Angle's Class II division 1 extraction cases treated by Begg appliance and Edgewise appliance / 华西口腔医学杂志

<p><b>OBJECTIVE</b>The purpose of this investigation is to compare the differences of hard tissue changes and stability in patients with Class II division 1 treated with extraction of four first premolars by Begg appliance and Edgewise appliance.</p><p><b>METHODS</b>The study was conducted using lateral cephalometric radiographs taken pretreatment, posttreatment and following-up. Thirty patients who had an Angle's Class II division 1 malocclusion were treated with first premolar extractions (19 by Begg appliance and 11 by Edgewise appliance). Cephalometric radiographs were scanned and the data were analyzed according to the paired and unpaired t-test.</p><p><b>RESULTS</b>The differences between the pretreatment and posttreatment periods were statistically significant for all the incisor and molar cephalometric variables (P<0.05) except UMA-PPV and UMC-PPV by Edgewise appliance. During treatment the incisors moved lingual-inclined and extrusively, the molar moved mesially and extrusively except that the upper molar of the Edgewise group stayed relatively stable anteroposteriorly. During the follow-up period the anterior teeth moved forward and extrusively, the upper molar moved mesially and extrusively. There was no significant differences of tooth movement and stability between Begg appliance and Edgewise appliance (P>0.05).</p><p><b>CONCLUSION</b>There is no significant differences of hard tissue changes and stability between Begg appliance and Edgewise appliance.</p>

Longitudinal changes of crown inclination in juveniles with normal occlusion / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the longitudinal changes in crown inclination of permanent incisors and first molars in juveniles with normal occlusion.</p><p><b>METHODS</b>The untreated sample comprised 20 subjects (6 males and 14 females) with normal occlusion from the Research Centre for Craniofacial Growth and Development of Peking University School and Hospital of Stomatology. Crown inclination was evaluated with Biaggini Rayset in two stages, stage I with first molars and four incisors in occlusion (mean, 9.5 +/- 0.9 years) and stage II with the second molars in occlusion (mean, 13.7 +/- 1.3 years).</p><p><b>RESULTS</b>No significant difference was found between sexual groups. The crown inclination of the upper central incisors decreased (P < 0.001). The crown inclination of the lower central and lateral incisors increased (P < 0.01 and P < 0.05, respectively). The crown inclination of maxillary molars decreased with growth (P < 0.001), whereas that of mandibular molars increased with growth (P < 0.001).</p><p><b>CONCLUSIONS</b>Maxillary molars tended to become upright lingually, whereas mandibular molars upright buccally with growth.</p>

Longitudinal changes of posterior available spaces of lower dental arch in adolescents with normal occlusion from 13 to 18 years of age / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the changes of available spaces of posterior arch segments in mandibular dentition from 13 to 18 years of age, which would provide information for space analysis of whole dental arch in adolescents.</p><p><b>METHODS</b>Twenty-six adolescents (12 males, 14 females) with normal occlusion were selected. All of the subjects had lateral cephalograms taken at the same time each year for 6 years. Longitudinal cephalometry and statistic analysis were conducted for all subjects.</p><p><b>RESULTS</b>Significant differences of available space were found between males and females. The growth of available space from 13 to 18 years of age was 5.12 mm in females and 5.79 mm in males. The completion of mandibular remodeling in males lagged behind females for about 1 year. No significant increase was found in girls beyond 16 years and in boys beyond 17 years. There was a 1.22 mm increase on each side per year in females until 16 years and a 1.45 mm increase in males until 17 years. The increase of available space was made partly by resorption of bone from the anterior border of the ramus and partly by mesial movement of the first molar. The mesial movement of dental arch was probably stimulated by the eruption of the third molars.</p><p><b>CONCLUSIONS</b>The prediction of available space should be based on age and sex.</p>

Treatment effects of magnetic Twin-block appliance for class II cases / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the effects of magnetic Twin-block appliance in the treatment of skeletal class II cases.</p><p><b>METHODS</b>The magnetic Twin-block appliance was embedded with two pairs of neodymium-iron-boron (Nd(2)Fe(14)B) rare earth permanent magnets in the upper and lower inclined planes of Twin-block appliance. The sample comprised of 13 skeletal class II patients in the late mixed or early permanent dentition treated by magnetic Twin-block appliance. Cephalometric films were taken before and after treatment. Helix CT images of the temporomandibular joint (TMJ) in all patients were examined before treatment (T1), during treatment (4 months after appliance placement, T2), after treatment (T3) and one year after treatment (T4).</p><p><b>RESULTS</b>A double contour image was detected in the superior posterior part of the condylar head on the pseudo-sagittal reconstruction plane pictures of T2 in 11 patients. The double contour image could be observed in most patients as well. This image also exhibited on the pictures of T3 in several patients. On the pictures of T2 and T3 in some patients, interruption of cortical bone and "bifurcation phenomenon" of condyles were shown. Pictures of T1 and T4 were similar and no signs of remodeling of TMJ were observed. Cephalometric analysis revealed significant changes in the maxillofacial structure after treatment. The profile of patients improved.</p><p><b>CONCLUSIONS</b>Bone remodeling of condyle occurred during the magnetic Twin-block treatment in class II patients. Magnetic Twin-block appliance was effective in the treatment of the growing skeletal class II patients.</p>

Analysis on differences between soft-tissue and hard-tissue profile in malocclusions / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To study the characteristics of soft-tissue integument and the differences between soft-tissue and hard-tissue topography in malocclusions.</p><p><b>METHODS</b>144 female patients, 12-15 years old, were selected. They were divided into class I, class II and class III groups according to the value of angle ANB which was measured on the pre-treatment cephalographs. Each group had 48 patients. Each patient had same type of skeletal pattern and occlusal pattern, full set of permanent teeth and none of cranofacial soft-tissue and hard-tissue diseases. 4 pairs of measurements describing soft-tissue and hard-tissue sagittal facial pattern and the prominence of lips and incisors were measured on each cephalograph. They were angle SnNsB', angle ANB, angle NsSnPos, angleNAPo, UL-SnPos, UI-APo, LL-SnPos and LI-APo. The distribution of soft-tissue sagittal facial pattern in each skeletal group was analyzed. The differences between angle SnNsB' and angle ANB, angle NsSnPos and angle NAPo, UL-SnPos and UI-APo, LL-SnPos and LI-APo were calculated in each patient. Then we calculated the means and the ranges of these differences in each group, the probability of positive and negative difference between each pair of measurements in each group were calculated too. Chi2 test on those probabilities were performed between the three groups. The mean difference between each pair of measurements was then analyzed by ANOVA between the three groups.</p><p><b>RESULTS</b>The disharmony between soft-tissue and hard-tissue sagittal facial pattern was found in 20%-30% of malocclusion patients. There were more or less differences between soft-tissue and hard-tissue topography and the ranges of their variation were quite wide. The soft-tissue integument increasingly tended to augment the convexity of soft-tissue facial profile when skeletal pattern varied from class II to class I to class III, at the same time, tended to increase upper lip prominence and decrease lower lip prominence.</p><p><b>CONCLUSION</b>On the average, soft-tissue integument tends to camouflage the abnormality of hard-tissue topography. But as to individual, the relative independence of soft-tissue integument makes it important to notice the influence of soft tissue on treatment planning and results.</p>

The compensation of post-treatment incisor torque in sagittal jaw relationship / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the dental compensation in different sagittal jaw relationships.</p><p><b>METHODS</b>One hundred and fifty-seven post-treatment cases with satisfied outcome were chosen. Computerized cephalometric analysis was performed to evaluate the sagittal jaw relationship. Incisor torque were measured based on study models. Correlation analysis was performed.</p><p><b>RESULTS</b>Compared with skeletal class I cases, the upper incisors of skeletal class III cases were more proclined, and lower incisors were more retroclined; the opposite result was found in skeletal class II cases. Dental compensation in class I cases took place primarily at lower incisors.</p><p><b>CONCLUSIONS</b>Incisor torque control was important in patients with various sagittal jaw relationships.</p>

Effect of maxillary protraction in patients with unilateral cleft lip and palate and anterior crossbite / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the different changes after maxillary protraction between the cleft and non-cleft patients with anterior crossbite.</p><p><b>METHODS</b>Prospective controlled clinical trial was carried out. Eighteen patients (aged 9.6 +/- 1.2 years) with unilateral cleft lip and palate (UCLP) were chosen as the experimental group. Eighteen non-cleft patients (aged 9.8 +/- 1.4 years) with similar malocclusions were selected as control group. All the patients were before puberty according to the evaluation of the hand wrist radiograms. Hyrax appliance and reverse headgear were used in both experimental and control groups. Lateral cephalometric radiographs were taken before and after treatment. Computerized cephalometric analysis was carried out. Paired t tests or t test were performed using software package SAS 8.1.</p><p><b>RESULTS</b>After treatment, the main changes in experimental group were: SNA +1.45 degrees , A-TFH +2.19 mm, SNB -2.18 degrees , ANB +3.64 degrees , MP/SN +2.78 degrees , LL-EP +0.88 mm in UCLP group. And in control group were: SNA +1.42 degrees , A-TFH +2.12 mm, SNB -1.32 degrees , ANB +2.68 degrees , MP/SN +1.47 degrees , LL-EP -1.37 mm.</p><p><b>CONCLUSIONS</b>Before puberty, maxillary protraction could accelerate maxillary forward growth in UCLP patients and the changes were similar to non-cleft patients. The occlusal relationship and soft tissue profile were improved significantly in both patients with or without cleft. The amount of mandibular posterior rotation in patients with UCLP was larger than in those with no cleft.</p>

Preliminary investigation of lower second molar extraction in correction of severe skeletal class III malocclusion / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate dento-skeletal and soft-tissue profile changes after extraction of lower second molars and treatment using fixed appliances in severe class III subjects.</p><p><b>METHODS</b>Fourteen 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.</p><p><b>RESULTS</b>After 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).</p><p><b>CONCLUSIONS</b>The 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.</p>

MESH diagrams of Chinese in Beijing and its preliminary application in practice / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To establish the normal MESH diagrams of Chinese in Beijing, and to build a computerized MESH analysis system for orthodontic practice.</p><p><b>METHODS</b>Twenty-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.</p><p><b>RESULTS</b>The 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.</p><p><b>CONCLUSIONS</b>MESH 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.</p>

Research of cranio-occlusional change of skeletal class III malocclusion in permanent dentition treated by the multiloop edgewise arch wire technique / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To analyze the mechanics in correction of skeletal class III malocclusion with Multiloop Edgewise Arch Wire (MEAW).</p><p><b>METHODS</b>15 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.</p><p><b>RESULTS</b>L6-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.</p><p><b>CONCLUSION</b>(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.</p>

Stability of molar relationship after orthodontic treatment in Class II division 1 malocclusions treated by extraction / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the changes of occlusal relationship in posterior teeth among the pre-treatment, post-treatment, and to analyze some possible factors which may relate to the relapse of posterior occlusal relationship.</p><p><b>METHODS</b>29 finishing Class II division 1 cases treated by extraction with full records selected were included. The sample consists of 12 males, 17 females. 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.</p><p><b>RESULTS</b>Improvements of molar relationship were shown during treatment and a little bit changes during follow-up. During the treatment, the amount of mesial movement of the lower molars was more than the upper molars in dental Class II malocclusion and the amount was similar between upper and lower molars in skeletal Class II malocclusion although the ANB angle decreased significantly. During the follow-up stage, the movement tendency between upper and lower molars was reversed. The sagittal growth pattern of mandible and irregularity of upper incisors were nearly correlated with the relapse of molar relationship.</p><p><b>CONCLUSION</b>The stability of molar relationship is acceptable during the follow-up stage in Class II malocclusion. The improvement of molar relationship depends on the difference of mesial movements between upper and lower molars in dental Class II malocclusion. However, in skeletal Class II malocclusion the improvement of jaw relationship does the effect. The positive growth of mandible and crowding of upper incisors may affect the relapse of molar relationship.</p>

Changes of profile prominence in borderline cases with extraction and non-extraction orthodontic treatment / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To compare the treatment effect on the prominence of profile in borderline cases between extraction and non-extraction treatment.</p><p><b>METHODS</b>The sample consisting of 33 borderline cases based on the judgment of 5 orthodontic specialists was divided into three groups according to the treatment way selected by the doctor in charge of the case. Three groups comprised 12 non-extraction cases, 13 four first premolars extraction cases and 8 four second premolars extraction cases. Structure superimposition was used to measure landmarks displacements which reflect the change of profile prominence before and after orthodontic treatment using pretreatment FH plane as a frame of reference.</p><p><b>RESULTS</b>Only the prominence of upper and lower incisors showed statistically significance between the extraction and non-extraction treatments. There was no statistically significant difference between the extraction of four first premolars and second premolars.</p><p><b>CONCLUSION</b>The main effect of extraction vs. non-extraction on profile of borderline cases is the prominence of upper and lower incisors, while their influences on upper and lower base bone and soft-tissue profile are not obvious.</p>