Three-dimensional changes in lip vermilion morphology of adult female patients after extraction and non-extraction orthodontic treatment / 대한치과교정학회지

OBJECTIVE@#To investigate the three-dimensional lip vermilion changes after extraction and non-extraction orthodontic treatment in female adult patients and explore the correlation between lip vermilion changes and incisor changes.@*METHODS@#Forty-seven young female adult patients were enrolled in this study (skeletal Class III patients were excluded), including 34 lip-protruding patients treated by extraction of four first premolars (18 patients requiring mini-implants for maximum anchorage control and 16 patients without mini-implants) and 13 patients requiring non-extraction treatment. Nine angles, seven distances, and the surface area of the lip vermilion were measured by using pre- and post-treatment three-dimensional facial scans. Linear and angular measurements of incisors were performed on lateral cephalograms.@*RESULTS@#There were no significant changes in the vermilion measurements in the non-extraction group. The vermilion angle, vermilion height, central bow angle, height/width ratio, and vermilion surface area decreased significantly after the orthodontic treatment in the extraction groups, but the upper/lower vermilion proportion remained unchanged. Significant correlations were found between the changes in incisor position and those in vermilion angles, vermilion height, and surface area.@*CONCLUSIONS@#Extraction of the four first premolars probably produced an aesthetic improvement in lip vermilion morphology. However, the upper/lower vermilion proportion remained unchanged. The variations in the vermilion were closely related to incisor changes, especially the upper incisor inclination changes.

Exploring a new method for superimposition of pre-treatment and post-treatment mandibular digital dental casts in adults / 北京大学学报(医学版)

OBJECTIVE@#To explore a cone beam computed tomography (CBCT)-independent method for mandibular digital dental cast superimposition to evaluate three-dimensional (3D) mandibular tooth movement after orthodontic treatment in adults, and to evaluate the accuracy of this method.@*METHODS@#Fifteen post-extraction orthodontic treatment adults from the Department of Orthodontics, Peking University School and Hospital of Stomatology were included. All the patients had four first premolars extracted, and were treated with straight wire appliance. The pre- and post-treatment plaster dental casts and craniofacial CBCT scans were obtained. The plaster dental casts were transferred to digital dental casts by 3D laser scanning, and lateral cephalograms were created from the craniofacial CBCT scans by orthogonal projection. The lateral cephalogram-based mandibular digital dental cast superimposition was achieved by sequential maxillary dental cast superimposition registered on the palatal stable region, occlusal transfer, and adjustment of mandibular rotation and translation obtained from lateral cephalogram superimposition. The accuracy of the lateral cephalogram-based mandibular digital dental cast superimposition method was evaluated with the CBCT-based mandibular digital dental cast superimposition method as the standard reference. After mandibular digital dental cast superimposition using both methods, 3D coordinate system was established, and 3D displacements of the lower bilateral first molars, canines and central incisors were measured. Differences between the two superimposition methods in tooth displacement measurements were assessed using the paired t-test with the level of statistical significance set at P<0.05.@*RESULTS@#No significant differences were found between the lateral cephalogram-based and CBCT-based mandibular digital dental cast superimposition methods in 3D displacements of the lower first molars, and sagittal and vertical displacements of the canines and central incisors; transverse displacements of the canines and central incisors differed by (0.3±0.5) mm with statistical significance.@*CONCLUSION@#The lateral cephalogram-based mandibular digital dental cast superimposition method has the similar accuracy as the CBCT-based mandibular digital dental cast superimposition method in 3D evaluation of mandibular orthodontic tooth displacement, except for minor differences for the transverse displacements of anterior teeth. This method is applicable to adult patients with conventional orthodontic treatment records, especially the previous precious orthodontic data in the absence of CBCT scans.

Compensation trends of the angulation of first molars: retrospective study of 1403 malocclusion cases / 国际口腔科学杂志·英文版

We investigated the compensatory trends of mesiodistal angulation of first molars in malocclusion cases. We compared differences in the angulation of first molars in different developmental stages, malocclusion classifications and skeletal patterns. The medical records and lateral cephalogrammes of 1403 malocclusion cases taken before treatment were measured to evaluate compensation of molar angulation in relation to the skeletal jaw. The cases were stratified by age, Angle classification and skeletal patterns. Differences in the mesiodistal angulation of the first molars were compared among the stratifications. We observed three main phenomena. First, angulation of the upper first molar varied significantly with age and tipped most distally in cases aged <12 years and least distally in cases aged >16 years. The lower first molar did not show such differences. Second, in Angle Class II or skeletal Class II cases, the upper first molar was the most distally tipped, the lower first molar was the most mesially tipped, and opposite angulation compensation was observed in Class III cases. Third, in high-angle cases, the upper and lower first molars were the most distally tipped, and opposite angulation compensation was observed in low-angle cases. These data suggest that the angulation of the molars compensated for various growth patterns and malocclusion types. Hence, awareness of molar angulation compensation would help to adjust occlusal relationships, control anchorage and increase the chances of long-term stability.

Reliability assessment and correlation analysis of evaluating orthodontic treatment outcome in Chinese patients / 国际口腔科学杂志·英文版

This study aimed to assess the reliability of experienced Chinese orthodontists in evaluating treatment outcome and to determine the correlations between three diagnostic information sources. Sixty-nine experienced Chinese orthodontic specialists each evaluated the outcome of orthodontic treatment of 108 Chinese patients. Three different information sources: study casts (SC), lateral cephalometric X-ray images (LX) and facial photographs (PH) were generated at the end of treatment for 108 patients selected randomly from six orthodontic treatment centers throughout China. Six different assessments of treatment outcome were made by each orthodontist using data from the three information sources separately and in combination. Each assessment included both ranking and grading for each patient. The rankings of each of the 69 judges for the 108 patients were correlated with the rankings of each of the other judges yielding 13 873 Spearman rs values, ranging from -0.08 to +0.85. Of these, 90% were greater than 0.4, showing moderate-to-high consistency among the 69 orthodontists. In the combined evaluations, study casts were the most significant predictive component (R(2)=0.86, P<0.000 1), while the inclusion of lateral cephalometric films and facial photographs also contributed to a more comprehensive assessment (R(2)=0.96, P<0.000 1). Grading scores for SC+LX and SC+PH were highly significantly correlated with those for SC+LX+PH (r(SC+LX)vs.(SC+LX+PH)=0.96, r(SC+PH)vs.(SC+LX+PH)=0.97), showing that either SC+LX or SC+PH is an excellent substitute for all three combined assessment.

Individualized three-dimensional finite element model of facial soft tissue and preliminary application in orthodontics / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To get individualized facial three-dimensional finite element (FE) model from transformation of a generic one to assist orthodontic analysis and prediction of treatment-related morphological change of facial soft tissue.</p><p><b>METHODS</b>A generic three-dimensional FE model of craniofacial soft and hard tissue was constructed based on a volunteer's spiral CT data. Seven pairs of main peri-oral muscles were constructed based on a combination of CT image and anatomical method. Individualized model could be obtained through transformation of the generic model based on selection of corresponding anatomical landmarks and radial basis functions (RBF) method. Validation was analyzed through superimposition of the transformed model and cone-beam CT (CBCT) reconstruction data. Pre- and post-treatment CBCT data of two patients were collected, which were superimposed to gain the amount of anterior teeth retraction and anterior alveolar surface remodeling that could be used as boundary condition. Different values of Poisson ratio ν and Young's modulus E were tested during simulation.</p><p><b>RESULTS</b>Average deviation was 0.47 mm and 0.75 mm in the soft and hard tissue respectively. It could be decreased to a range of +0.29 mm and -0.21 mm after a second transformation at the lip-mouth region. The best correspondence between simulation and post-treatment result was found with elastic properties of soft tissues defined as follows. Poisson ratio ν for skin, muscle and fat being set as 0.45 while Young's modulus being set as 90.0 kPa, 6.2 kPa and 2.0 kPa respectively.</p><p><b>CONCLUSIONS</b>Individualized three-dimensional facial FE model could be obtained through mathematical model transformation. With boundary condition defined according to treatment plan such FE model could be used to analyze the effect of orthodontic treatment on facial soft tissue.</p>

Patient-specific modeling of facial soft tissue based on radial basis functions transformations of a standard three-dimensional finite element model / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>An important purpose of orthodontic treatment is to gain the harmonic soft tissue profile. This article describes a novel way to build patient-specific models of facial soft tissues by transforming a standard finite element (FE) model into one that has two stages: a first transformation and a second transformation, so as to evaluate the facial soft tissue changes after orthodontic treatment for individual patients.</p><p><b>METHODS</b>The radial basis functions (RBFs) interpolation method was used to transform the standard FE model into a patient-specific one based on landmark points. A combined strategy for selecting landmark points was developed in this study: manually for the first transformation and automatically for the second transformation. Four typical patients were chosen to validate the effectiveness of this transformation method.</p><p><b>RESULTS</b>The results showed good similarity between the transformed FE models and the computed tomography (CT) models. The absolute values of average deviations were in the range of 0.375 - 0.700 mm at the lip-mouth region after the first transformation, and they decreased to a range of 0.116 - 0.286 mm after the second transformation.</p><p><b>CONCLUSIONS</b>The modeling results show that the second transformation resulted in enhanced accuracy compared to the first transformation. Because of these results, a third transformation is usually not necessary.</p>

Research on Chinese orthodontic specialists' subjective evaluation of orthodontic treatment outcome / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To analyze the results of multiple Chinese orthodontic specialists' subjective evaluation of orthodontic treatment outcome, to investigate the relevance of different experiment items and to explore the weight of each monomial material.</p><p><b>METHODS</b>As a randomized clinical trial, with six orthodontic treatment centers and Angle's classification being regarded as two stratification factors, it contained 108 cases with integrity data, which was random extracted from 2383 cases that received orthodontic treatment in six orthodontic treatment centers during the past five years, gathering post-treatment study casts, cephalometrics and photographs of 48 cases as the research subject. Similarly taking Angle's classification as a stratification factor, 108 cases were randomly divided into 9 groups. The randomization of sampling and grouping were both generated by a pseudo-random number generator. According to the monomial and combined subjects, 69 orthodontic specialists were regarded as the raters to rank the 12 cases in each group, and to judge whether the case was qualified.</p><p><b>RESULTS</b>Correlation analysis: the Spearman r between Post-M + C and Post-M + C + P and the Spearman r between Post-M + P and Post-M + C + P were both greater than 0.950. The Spearman r between Post-M and Post-P and the Spearman r between Post-M and Post-C were about 0.300. The Spearman r between Post-P and Post-C was 0.505. Regression analysis: the linear regression results: M + C = 0.782M + 0.308C - 0.150, M + P = 0.804M + 0.233P - 0.091, M + C + P = 0.764M + 0.243P + 0.131C - 0.291. The r(2) of above three models was greater than 0.9.</p><p><b>CONCLUSIONS</b>It was applicable to use M + C and M + P instead of M + C + P. Study casts could not replace cephalometrics or photographs when doing subjective evaluation. Cephalometrics and photographs could not substitute for each other either. In the combined materials evaluation, model accounted for the largest percentage. Based on the regression model, for the greater part, the integration of several monomial materials could replace the combined material assessment effectively.</p>

Tip and torque changes in maxillary buccal segment after orthodontic treatment: a three-dimensional study / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate three-dimensional imaging registration and superimposition techniques in measuring the tip and torque change of upper canine, premolar and first molar after orthodontic treatment.</p><p><b>METHODS</b>Twenty-eight subjects (14 extraction cases and 14 non-extraction cases) with full records were randomly selected from the Department of Orthodontics, Peking University School and Hospital of Stomatology. The pre-and post-treatment upper dental casts were digitized with three-dimensional spot laser scanner and superimposed with reverse engineering software. The facial axis of the clinical crown (FACC) was transferred from post-treatment teeth to the pre-treatment teeth using three-dimensional imaging registration. The occlusal plane was constructed on the post-treatment upper digital cast and the tip and torque values were measured.</p><p><b>RESULTS</b>In the non-extraction group, the tip of the second premolar decreased by 1.5° (P < 0.05). The buccal crown torque of the first and second premolars increased by 5.1° and 4.2° (P < 0.05), respectively. In the extraction group, the lingual crown torque of upper canine increased by 3.8° (P < 0.05).</p><p><b>CONCLUSIONS</b>Non-extraction orthodontic treatment tended to tip the upper second premolar distally and increased the buccal crown torque of the upper premolars while extraction treatment increased the lingual crown torque of the upper canine.</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>

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>

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>

Inhibitory effect of ginsenoside Rg3 on ovarian cancer metastasis / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Ginsenosides are main components extracted from ginseng, and ginsenoside Rg3 is one of the most important parts. Ginsenoside Rg3 has been found to inhibit several kinds of tumor growth and metastasis. The present study was undertaken to investigate the effect of ginsenoside Rg3 on human ovarian cancer metastasis and the possible mechanism.</p><p><b>METHODS</b>The experimental lung metastasis models of ovarian cancer SKOV-3 and the assay of tumor-induced angiogenesis were used to observe the inhibitory effects of Rg3 on tumor metastasis and angiogenesis. The effect of Rg3 on invasive ability of SKOV-3 cells in vitro was detected by Boyden chamber, and immunofluorescence staining was used to recognize the expression of matrix metalloproteinase 9 (MMP-9) in SKOV-3 cells.</p><p><b>RESULTS</b>In the experimental lung metastasis models of ovarian cancer, the number of tumor colonies in the lung and vessels oriented toward the tumor mass in each ginsenoside Rg3 group, was lower than that of control group. The invasive ability and MMP-9 expression of SKOV-3 cells decreased significantly after treatment with ginsenoside Rg3.</p><p><b>CONCLUSIONS</b>Ginsenoside Rg3 can significantly inhibit the metastasis of ovarian cancer. The inhibitory effect is partially due to inhibition of tumor-induced angiogenesis and decrease of invasive ability and MMP-9 expression of SKOV-3 cells.</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>

Accuracy of three-dimensional facial image based on phase measuring profilometry / 中华口腔医学杂志

<p><b>OBJECTIVE</b>Three-dimensional (3-D) facial images are very useful for orthodontic diagnosis. Three-dimensional facial imaging system (DSC-2) based on phase measuring profilometry (PMP) was used to obtain images and tested for accuracy.</p><p><b>METHODS</b>Geometric strips (20 mm in width) was used to test the accuracy of the obtained images. Three-dimensional images of plaster head model with marker of 5 mm x 5 mm were taken by DSC-2 three-dimensional facial imaging system. The difference of measurements was compared between both methods. Measurements were repeated twice by three different doctors.</p><p><b>RESULTS</b>The average value of width in 3-D mode was 19.5 mm. No significant difference was found, compared with actual width (20 mm). There was no significant difference between computer measurement and manual measurement of the plaster head model (P > 0.05).</p><p><b>CONCLUSIONS</b>DSC-2 three-dimensional facial imaging system was accurate and reliable to obtain 3-D facial images.</p>

Inhibitory effect of ginsenoside Rg3 combined with cyclophosphamide on growth and angiogenesis of ovarian cancer / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Ginsenoside Rg3, the main component isolated from ginseng, inhibits some kinds of tumour growth and angiogenesis. The combination of low dose chemotherapy and antiangiogenesis inhibitors suppresses growth of experimental tumours more effectively than conventional therapy. The effect of this combination on ovarian cancer remains to be evaluated. Therefore, we investigated the synergism of ginsenoside Rg3 and cyclophosphamide (CTX) on growth and angiogenesis of human ovarian cancer.</p><p><b>METHODS</b>Twenty-eight female athymic mice were divided randomly into 4 groups of 7: ginsenoside Rg3, CTX, ginsenoside Rg3 and CTX combination and control, after being transplanted with ovarian cancer cells (SKOV-3). The mice were given intraperitoneal injection of ginsenoside Rg3 and CTX for the 10 days following inoculation of SKOV-3 cells. The life quality and number of living days of mice were recorded. The size of tumour, tumour inhibitive rate, life elongation rate, proliferating cell nuclear antigen labelling index (PCNALI), expression of vascular endothelial cell growth factor (VEGF) and microvessel density (MVD) of the tumour tissues were estimated.</p><p><b>RESULTS</b>Life quality of mice in ginsenoside Rg3 and combined treatment groups were better and number of living days longer than control. Average tumour weights of each treated group were less than control and there was no significant difference among the treated groups. PCNALI of treated groups was lower than control. The MVD value and VEGF expression in treated groups were significantly lower than control and the MVD values of ginsenoside Rg3 and combined treatment groups were lower than that of CTX group.</p><p><b>CONCLUSIONS</b>Ginsenoside Rg3 significantly inhibited growth and angiogenesis of ovarian cancer when used alone or combined with CTX. Ginsenoside Rg3 and CTX combination reinforced the antitumour effect each other and improved the living quality and survival time of mice with tumour.</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>

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>

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>

Comparison of straight wire appliance versus edgewise appliance in orthodontic treatment outcome / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the difference between straight wire appliance and edgewise appliance treatment outcome.</p><p><b>METHODS</b>80 cases finished with two-arch straight wire or edgewise appliance between 1994 and 2001 were selected. The PAR index on pre- and post-treatment dental casts and PAR score was recorded respectively. According to the same pre-treatment PAR score and extraction pattern, the samples were divided into two groups, straight wire group and edgewise group, and each group had 40 cases. The data were analyzed statistically.</p><p><b>RESULTS</b>Estimated with the post-treatment PAR score of posterior teeth alignment, the treatment with straight wire appliance was lower than that with edgewise appliance (P < 0.01). There was no statistical difference in other recorded PAR score between two groups. For the mean treatment duration, straight wire appliance (3.95 months) was shorter than edgewise appliance.</p><p><b>CONCLUSION</b>As for the posterior teeth alignment, the straight wire appliance was more accurate, and the straight wire appliance was more efficient than edgewise appliance.</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>