Adjunctive interventions to accelerate orthodontic tooth movement / 华西口腔医学杂志

Orthodontic treatment is a time-consuming process whose duration usually takes 2-3 years. In general, long-term treatment duration possesses higher risks of complications, which may have adverse impact on patients. Therefore, exploring safe and effective adjunctive interventions to accelerate orthodontic tooth movement and shortening the treatment duration are of profound clinical significance. Currently, numerous adjunctive interventions have been generated and developed to accelerate orthodontic tooth movement, which can be divided into two main categories: surgical and non-surgical. However, an intervention that is widely accepted as a routine practice in orthodontic clinic is lacking. This article aims to review com-mon adjunctive interventions used to accelerate orthodontic tooth movement. This review can be used as a basis to guide clinical practice, shorten treatment duration, and improve patients' prognosis.

Research progress on the relationship between centric relation and orthodontic treatment / 华西口腔医学杂志

Centric relation (CR) is one of the core research contents in orthodontics, prosthodontics, and gnathology, acting as an important physiological factor in reconstructing the occlusion and adjusting the occlusal relationship. For over a century, CR is still a controversial subject in dentistry. CR has been redefined for several times, and recently, its application has been widened in orthodontics, including orthodontic diagnosis, clinical examination and analysis, and treatment goals. The purpose of this article is to review the definition of CR, its relationship with malocclusion, and the application of this relationship in orthodontic treatment.

The role of microRNAs in bone remodeling / 国际口腔科学杂志·英文版

Bone remodeling is balanced by bone formation and bone resorption as well as by alterations in the quantities and functions of seed cells, leading to either the maintenance or deterioration of bone status. The existing evidence indicates that microRNAs (miRNAs), known as a family of short non-coding RNAs, are the key post-transcriptional repressors of gene expression, and growing numbers of novel miRNAs have been verified to play vital roles in the regulation of osteogenesis, osteoclastogenesis, and adipogenesis, revealing how they interact with signaling molecules to control these processes. This review summarizes the current knowledge of the roles of miRNAs in regulating bone remodeling as well as novel applications for miRNAs in biomaterials for therapeutic purposes.

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.

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>

Influence of the peri-implantitis to the microscrew-bone interface / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To study the histological change of microscrew-bone interface, detect the relative cytokine of gingival crevicular fluid, and explore the impossible mechanism of peri-implantitis.</p><p><b>METHODS</b>Four male Beagles were collected. Randomly select one side of animals jaw as the experimental group to induce the peri-implantitis, and another side as the control group. Four microscrews were implanted on each side. In the 1st, 2nd, 3rd, 4th weeks after implantation, collect peri-implant sulcular fluid (PISF) and detect tumor necrosis factor-alpha (TNF-alpha) levels before sacrificed, and the harvest tissue were observed in histological ways.</p><p><b>RESULTS</b>According to the extension of time after implantation, the experimental group showed visible progress of interface destruction: 1st week after implantation showed large numbers inflammatory cells collected at the neck but did not undermine the cortical bone; 2nd week after implantation, cortical bone were observed angular absorption; Bone resorption continued to develop and at the 4th week, bone resorption were enlarged to the second thread of microscrew and the interface was filled with a large number of collagen fibers.</p><p><b>CONCLUSION</b>The destruction of interface began at the neck of microscrew, and the further development was along the interface in depth. Both microscrews with peri-implantitis and the healthy controls showed the presence of TNF-alpha. Inflammation accumulation might trigger the up-regulation of TNF-alpha level, and the onset of inflammation would enhance the up-trend.</p>

The measurement of utility value for skeletal malocclusion / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To measure the utility value of different skeletal malocclusion for patients receiving orthodontic treatment.</p><p><b>METHODS</b>Utility value of different skeletal malocclusion for patients was measured by rating scale and time trade-off.</p><p><b>RESULTS</b>The youth group had higher utility values than adult group for skeletal malocclusion Class II (protruding facial type) with median mandibular angle. The utility value of skeletal malocclusion Class III (concave facial type) with low mandibular angle was the lowest, and the utility value of skeletal malocclusion Class II (protruding facial type) with median mandibular angle was the highest. There was no difference in the utility values by rating scale and by time trade-off.</p><p><b>CONCLUSION</b>For some skeletal malocclusion, the youth had different utility values with the adult.</p>

Effects of mechanical tensile stress on the expression of ODF mRNA in osteoblasts differentiated from rBMSCs in vitro / 医用生物力学

Objective To investigate the correlation between mechanical tensile stress and the expression of ODF mRNA in osteoblasts differentiated from rBMSCs, and elucidate the mechanism for osteoclastogenesis regulated by osteoblasts in bone modeling and remodeling during the process of orthodontic tooth movement. Method rBMSCs derived osteoblasts were isolated and cultured in vitro, and subjected to static mechanical tensile stress of 1, 3, 5 kPa or dynamic tensile stress of 3, 5 kPa at 0.017 Hz using the cellular tensile stress system for 24 h. The control groups were subjected without any strain. Cells were collected in 0, 3, 6, 9, 12, 24, 48 h respectively after stress loading. The expression patterns of ICAM-1 mRNA were examined by semiquantitative RT PCR assay. Results ODF mRNA level significantly decreased after dynamic tensile strain, compared with the control groups；the effects of inhibition did not positively correlated with the magnitude of strain; the expression of ODF mRNA gradually decreased at 6 h, significantly decreased at 9 h, then slightly rebounded and still stayed at a considerably lower level, reached the minimum transcription at 48 h. Conclusions The mechanical tensile strain can regulate osteoclastogenesis by inhibiting the expression of ODF in osteoblasts derived from rBMSCs. It could lead to a better understanding of the molecular basis for osteoblast osteoclast communication in bone resorption induced by the application of mechanical strain during the orthodontic tooth movement.

Biomechanical effects of bracketless appliance technology: a finite element method study / 医用生物力学

Objective To develop an initial numerical model for bracketless appliance technology, and to analyze the biomechanical effects. To provide the fundamental basis to optimize the clinical application of bracketless appliance technology. Method A 3D numerical model of a dry skull was developed from sequential computed tomography (CT) scan images taken at 0.5 mm intervals by using Mimics and ABAQUS software. This model consisted of three parts: a dento maxillary model of upper anterior section, a matching bracketless appliance model, and their assembly to simulate orthodontic force stressed by bracketless appliance. The nonlinear finite element method (FEM) was used to analyze the instant biomechanical effects. As the control group, the same dento maxillary model was loaded to simulate fixed appliance working pattern. Results The instant dento periodontal stress with bracketless appliance loading was much higher than that with fixed appliance working pattern by 50~500 times. With bracketless appliance loading，the tendency of tooth movement wasn’t exactly performed as planned with orthodontic teeth tending to affect each other. The canine designed to do mesiodistal translation tended to do tipping movement rather than bodily movement. Bracketless appliance itself performed stress concentration mainly in places of great deformation, but the maximal stress was less than its elastic limit of 53.1 MPa. Conclusions In this study, bracketless appliance loading performed unexpected high instant stress on dento periodontal tissue, with limit in controlling tooth movements. The bracketless appliance is not suggested to replace the traditional fixed appliance. This study suggested bracketless appliances should be designed more reasonable, and the material of Anglealign appliances used should be further improved, to enhance the control of orthodontic tooth movement. An ideal material for the bracketless appliance was expected to perform smaller elastic modulus, higher elastic limit and better stress relaxation.

Advances in cytomechanics in orthodontic tooth movement / 医用生物力学

In recent years, great development has been made in cytomechanics in orthodontic tooth movement（OTM）.The essential role of periodontal ligament in OTM has been widely accepted. The in vitro models have become an important way to reveal the biological mechanism in OTM,largely based on periodontal ligament cells(PDLCs), as well as other cells, including bone marrow mesenchymal stem cells, osteoblast, cementoblast and myoblast.The in vitro models have been renovated from the traditional ways stressing the 2D cultured cells by deformation of the bottom,gravity, hydrostatic pressure or centrifugation, to the establishment of various novel models loading mechanical stimulation on cells 3D cultured in bioscaffolds. The molecular expression involved in the osteoblastic differentiation and osteoclastogenesis induction in the bone remodeling cycle has drawn great attention, and will continue to be a focus of study. Furthermore, with the identification of periodontal ligament stem cells(PDLSCs), the cytomechanics involved in OTM and periodontitis, will undoubtedly be a promising new direction.

The technique characteristic and clinical application of HX straight-wire appliance / 华西口腔医学杂志

HX straight-wire appliance (HX-SWA) is designed and adjusted by doctors of Orthodontic Department, West China College of Stomatology, Sichuan University. It is a set of appliance that is constructed according to normal occlusion features of the Chinese people, including the prescription of tip, torque, in/out, counter-tip, counter-rotation and overcorrection in brackets and buccal tubes. Some ingredients of the appliance are different from that of the most popular Roth straight-wire appliance in the world wide. Over a period of the last 10 years, doctors in our hospital kept on summarizing treatment experience with HX-SWA, which will help more doctors promote practice and results in orthodontic clinic.

Study on the posterior teeth mesiodistal tipping degree of normal occlusion subjects among different facial growth patterns / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To study the relationship between the mesiodistal tipping degree of maxillary and mandible posterior teeth and different vertical facial skeletal types of subjects with normal occlusion.</p><p><b>METHODS</b>163 subjects with normal occlusion were selected, lateral cephalograms were taken and divided into three different facial skeletal types. The difference of the mesiodistal tipping degrees and intersection angles of upper and lower posterior teeth between the three different facial skeletal types were analyzed.</p><p><b>RESULTS</b>Among 163 subjects, vertical growth pattern, average growth pattern and horizontal growth pattern were 24, 96 and 43 respectively. There were statistic differences of mesiodistal tipping degrees of the first and second maxillary and mandible premolar and the first permanent molar between vertical growth and horizontal growth pattern, horizontal growth and average growth pattern (P < 0.05). But there were no statistically significant differences between vertical growth and average growth pattern (P > 0.05). The differences of the maxillary and mandible posterior teeth's intersection angle among three vertical facial skeletal types had no statistic significance (P > 0.05).</p><p><b>CONCLUSION</b>Different vertical facial skeletal type has its own normal and coordinated posterior teeth mesiodistal tipping degrees.</p>

Morphological characteristics of mandibular symphysis in adult skeletal class II and class III malocclusions with abnormal vertical skeletal patterns / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To figure out the differences of the morphological characteristics of mandibular symphysis between Class II and Class III adult skeletal malocclusions with different abnormal vertical skeletal patterns.</p><p><b>METHODS</b>109 Chinese female adults of skeletal Class II and Class III were chosen and divided into four groups according to vertical and sagittal skeletal pattern: Class II--vertical-growth-pattern group (n=30), Class III--vertical-growth-pattern group (n=25), Class II--horizontal-growth-pattern group (n=29), Class III--horizontal-growth-pattern (n=25). Lateral cephalograms were taken. The symphyseal widths and heights, along with lower incisor positions were evaluated. Observation and statistics analysis were done to clarify the morphological characteristics of the symphyseal region of different skeletal patterns.</p><p><b>RESULTS</b>There were morphological differences of symphyseal region between Class II and Class III skeletal malocclusions, but not significant in width and total height. With a vertical-growth-pattern, Class II malocclusions had higher alveolus than Class III, but smaller chin prominence and lower basal bone (P < 0.01). With a horizontal-growth-pattern, Class II malocclusions had higher alveolus (P < 0.05) and larger alveolar top width (P < 0.001). With a same sagittal skeletal pattern, vertical-growth-pattern group had thinner but higher symphyseal region and bigger chin prominence (P < 0.001 in Class II while P < 0.05 in Class III). Besides, a vertical-growth-pattern malocclusion was prone to have a cucurbit-morph chin, of which Id width was larger than basal width (P < 0.01).</p><p><b>CONCLUSION</b>There are morphological differences in symphyseal region between Class II and Class III skeletal malocclusions with different abnormal vertical skeletal patterns. The influence of abnormal vertical skeletal pattern to symphyseal morphological characteristics is greater than that of abnormal sagittal skeletal pattern. There is a risk of orthodontic movement of low incisors in vertical-growth-pattern skeletal malocclusion.</p>

Successful treatment of postpeak stage patients with class II division 1 malocclusion using non-extraction and multiloop edgewise archwire therapy: a report on 16 cases / 国际口腔科学杂志·英文版

<p><b>AIM</b>To determine cephalometrically the mechanism of the treatment effects of non-extraction and multiloop edgewise archwire (MEAW) technique on postpeak Class II Division 1 patients.</p><p><b>METHODOLOGY</b>In this retrospective study, 16 postpeak Class II Division 1 patients successfully corrected using a non-extraction and MEAW technique were cephalometrically evaluated and compared with 16 matched control subjects treated using an extraction technique. Using CorelDRAW software, standardized digital cephalograms pre- and post-active treatments were traced and a reference grid was set up. The superimpositions were based on the cranial base, the mandibular and the maxilla regions,and skeletal and dental changes were measured. Changes following treatment were evaluated using the paired-sample t-test. Student's t-test for unpaired samples was used to assess the differences in changes between the MEAW and the extraction control groups.</p><p><b>RESULTS</b>The correction of the molar relationships comprised 54% skeletal change (mainly the advancement of the mandible) and 46% dental change. Correction of the anterior teeth relationships comprised 30% skeletal change and 70% dental change.</p><p><b>CONCLUSION</b>The MEAW technique can produce the desired vertical and sagittal movement of the tooth segment and then effectively stimulate mandibular advancement by utilizing the residual growth potential of the condyle.</p>

Progress of orthodontics in the clinical and basic research / 华西口腔医学杂志

In recent years, clinical diagnostic and treatment techniques of orthodontics have been developed rapidly. The orthopedic mechanism of malocclusion has been the hot spot of basic research of orthodontics.

Modified retention elements of removable reverse headgear appliances / 华西口腔医学杂志

<p><b>OBJECTIVE</b>Retention elements were added in the removable reverse headgear appliances in order to achieve better treatment effects of skeletal Class III malocclusion.</p><p><b>METHODS</b>Eighteen patients who needed treatments with reverse headgear appliances were randomly and equally divided into two groups with traditional type of retention elements (T group) and modified type of retention elements (M group) respectively. For the modified type appliances, an adams clasp was added in the position of central incisors on the basis of the traditional type. The minimum dislocating force for both types was measured with the same forcemeter in the first and second visit, respectively. The occurrence of dislocation caused by traction was recorded during the visits of the first three months.</p><p><b>RESULTS</b>The M group showed significantly greater retention than the T group. The minimum dislocating force for M group was larger in the first and second visit (P<0.01, P<0.001). Furthermore, during the first three months, two times of dislocation occurred in M group while it was nine times for T group, indicating great difference in retention (P< 0.05).</p><p><b>CONCLUSION</b>Adding an adams clasp in the position of upper central incisors could effectively prevent the downward dislocation of the appliance when traction force was applied. Accordingly, the therapeutic efficacy was greatly improved.</p>

Facial profile preference among four panels / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To determine the facial profile preference among four groups of persons and the influence of vertical proportion and skeletal anteroposterior relation on facial profile esthetics.</p><p><b>METHODS</b>One hundred and twenty persons, comprising of adult patients, adolescents' parents, laypersons and orthodontists, participated this study. The subjects were asked to rate 27 silhouettes which represented the male facial profiles with various vertical proportion and anteroposterior relation.</p><p><b>RESULTS</b>The silhouette II-1s scored highest while the one III-4s scored lowest (P < 0.05). The silhouette I-normal was rated highest by orthodontists while the ones II-normal and II-1s were rated highest by other three groups. The silhouette III-4s was scored lowest by all groups (P < 0.05).</p><p><b>CONCLUSIONS</b>Vertical discrepancy had influence on Chinese male facial profile esthetics and the influence was related to the degree of vertical malformation and skeletal anteroposterior relation. Class III skeletal pattern had the most negative influence on male profile esthetics. The four panels had different esthetic standard. The preference of facial profile esthetics was related to orthodontic education background rather than gender or age.</p>

Time varied stress effects on the shape-alteration of myoblast in rats / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the effects of time varied stress on the shape-alteration of myoblast in rats and to provide a theoretic base to determine the mechanics of myoblast in orthodontic therapy.</p><p><b>METHODS</b>Based on the pulsatile mechanical system our group founded, this study loaded different strain (2.5 kPa, 5.0 kPa and 10.0 kPa) to the myoblast of lateral pterygoid muscle. The alterations in shape under time varied stress of 6 h and 12 h were assessed by phase-contrast microscopy, scanning electron microscope.</p><p><b>RESULTS</b>The orientation of myoblast seemed no obvious orderliness before loading. But after loading the lower time varied strain (2.5 kPa, 5.0 kPa), they were changed their orientation to paralel with the direction of strain along with the membrane. Meanwhile, there had one trend to set the shape of myoblast more upright along with the membrane after loading the higher time varied stress (10.0 kPa).</p><p><b>CONCLUSION</b>It was proved that the different time varied stress in vitro expressed the different influence on the remolding of myoblast.</p>

Cephalometric evaluation of the effects of pendulum appliance on various vertical growth patterns / 华西口腔医学杂志

<p><b>OBJECTIVE</b>The aim of this study was to investigate the effects of the pendulum appliance in treating dental Class II patients with various vertical growth patterns.</p><p><b>METHODS</b>The samples (n = 30) were divided into three groups equally based on their FMA. Pretreatment and post-treatment cephalometric radiographs were taken to measure the changes.</p><p><b>RESULTS</b>The amount of upper molar distalization in the low-angle group was the fewest, and that in the high-angle group was the most. Upper molars had been intruded insignificantly. The amount of anchorage loss at the first premolars and overjet increased at incisors was different in the three groups. The biggest change happened in the low-angle group, and the smallest in the high-angle group.</p><p><b>CONCLUSION</b>The results of this study showed that pendulum appliance could move the upper molars distally in a short period of time. The upper molars in different groups were intruded insignificantly. Pendulum appliance could be used to move the upper molars distally in high-angle cases.</p>

Expression of osteoclast differentiation factor and intercellular adhesion molecule-1 of bone marrow mesenchymal stem cells enhanced with osteogenic differentiation / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To investgate whether the expression of osteoclast differentiation factor (ODF), intercellular adhesion molecule-1 (ICAM-1) depended on the stage of osteoblastic differentiation from rat bone marrow mesenchymal stem cells (BMSC).</p><p><b>METHODS</b>BMSC (4 passage) were selected for osteogenic differentiation by treated with osteogenic supplements (OS). Cells were harvested by day 0, 3, 6, 9, 12, 18 respectively after osteogenic inducement. In each experiment, control and OS-treated cells were processed in parallel. ODF and ICAM-1 mRNA were analyzed by semiquantitave RT-PCR assay.</p><p><b>RESULTS</b>Expression of ODF was enhanced with osteogenic differentiation guadully. whereas, expression of ICAM-1 was activated at OS-treated day 6, then keeping at a stable level.</p><p><b>CONCLUSION</b>This study indicated that BMSC undergoing osteogenic inducement was an ideal model for studying the differentiation and maturation of osteoblasts. During the early stage of differentiation along osteoblasts from stem cells to osteocytes, BMSC or osteoprogenitor react somewhat differently from osteoblasts, suggesting the ability of osteoblasts to regulating differentiation and maturation of osteoclasts have been improved with osteogenic culture.</p>