Evaluation of modified clear Twin Block aligner in treating adolescents with skeletal class II malocclusion: A two-centre cephalometric study.

INTRODUCTION: The purpose of this study was to evaluate the therapeutic effect of modified clear Twin Block (CTB) aligner and traditional twin block (TB) appliance from skeletal, dentoalveolar and soft tissue changes in adolescents with skeletal class II malocclusion. METHODS: A total of 80 adolescents, included in this study from two medical centres, were distributed into CTB group, TB group and control group based on the treatment they received. Lateral cephalograms at pre-treatment (T1) and post-treatment (T2) were measured by modified Pancherz's cephalometric analysis, and dentoskeletal and soft tissue changes were analysed by independent-sample t-test, paired-sample t-test, ANOVA test and Scheffe's Post Hoc test. RESULTS: Seventy-five adolescents completed the study, including 32 in the CTB group, 32 in the TB group and 11 in the control group. Both CTB and TB treatment showed significant differences in most dentoskeletal and soft tissue measurements. Compared with the control group, improvements were observed in class II molar relationship through significant different in S Vert/Ms-S Vert/Mi in the CTB group (P < .01) and the TB group (P < .001), as well as deep overjet through significant different in S Vert/Is-S Vert/Ii in the CTB group (P < .001) and the TB group (P < .001). Besides, the CTB group also showed less protrusion of lower incisors and resulted in a more significant improvement in profile with fewer adverse effects on speaking, eating and social activities. CONCLUSIONS: For adolescents with skeletal class II malocclusion, CTB appliance was as effective as TB on improving dentoskeletal and soft tissue measurements, featuring more reliable teeth control and patient acceptance.

Effects of Twin-block vs sagittal-guidance Twin-block appliance on alveolar bone around mandibular incisors in growing patients with Class II Division 1 malocclusion.

INTRODUCTION: The purpose of this study was to comparatively evaluate the effects of Twin-block (TB) appliance and sagittal-guidance Twin-block (SGTB) appliance on alveolar bone around mandibular incisors in growing patients with Class II Division 1 malocclusion, using cone-beam computed tomography. METHODS: The sample consisted of 25 growing patients with Class II Division 1 malocclusion (14 boys and 11 girls, mean age 11.92 ± 1.62 years) and was randomly distributed into the TB group (n = 13) and the SGTB group (n = 12). The treatment duration was 11.56 ± 1.73 months. Pretreatment (T1) and posttreatment (T2) cone-beam computed tomography scans were taken in both groups. Height, thickness at apex level, and volume of the alveolar bone around mandibular left central incisors were measured respectively on labial and lingual side, using Mimics software (version 19.0; Materialise, Leuven, Belgium). Based on the stable structures, 3-dimensional (3D) registrations of T1 and T2 models were taken to measure the sagittal displacement of incisors. Intragroup comparisons were evaluated by paired-samples t tests and Wilcoxon tests. Independent-samples t tests and Mann-Whitney U tests were used for intergroup comparisons. RESULTS: In both groups, alveolar bone height and volume on the labial side of the incisors significantly decreased after treatment (P <0.05). Lingual alveolar bone height, lingual and total alveolar bone volume, labial, lingual and total alveolar bone thickness showed no significant difference between T1 and T2 (P >0.05). In both groups the incisors tipped labially and drifted to the labial side. Compared with the TB group, less labial alveolar bone loss, less incisor proclination and crown edge drift were found in the SGTB group (P <0.05). CONCLUSIONS: Labial alveolar bone loss around mandibular incisors was observed after both types of appliances treatment in growing patients with Class II Division 1 malocclusion. Less labial alveolar bone loss, less incisor proclination, and crown edge drift were found in the SGTB group than in the TB group during treatment.

A cone-beam computed tomography analysis of angulation and inclination of whole tooth and clinical crown in adults with normal occlusion.

OBJECTIVES: To identify the mesiodistal angulation and faciolingual inclination of whole tooth and clinical crown in Chinese young adults with normal occlusion, by examining CBCT digitalized images. SETTING AND SAMPLE POPULATION: Forty-two volunteers, who presented with normal occlusion and without previous orthodontic treatment, were selected for this study. MATERIALS AND METHODS: The subjects were advised to take dental CBCT and the digital images of the dentition were obtained. The widely recognized University of Southern California (USC) root vector analysis was adopted to detect the angulation and inclination of the whole tooth, as well as of the clinical crown. RESULTS: No statistically significant difference was detected between male and female subjects. The fluctuations of the angulation and the inclination of the whole tooth from anterior to posterior in both arches manifested distinctive trends. The changes in maxillary dentition seem relatively marked, whereas those in mandibular dentition show less obvious, demonstrating moderate fluctuation both in angulation or inclination. The angulation and inclination of clinical crown are obtained and are shown positively correlated with that of each whole tooth. CONCLUSIONS: The normal range of the mesiodistal angulation and faciolingual inclination of whole tooth and clinical crown in Chinese adults with normal occlusion are identified. This study could establish clinical standards for designing 3D dental data-based orthodontic appliances for Chinese, and for providing the guidance for orthodontic treatment.

Does systemic administration of casein phosphopeptides affect orthodontic movement and root resorption in rats?

OBJECTIVES: To assess the potential effects of casein phosphopeptides (CPPs) on orthodontically induced iatrogenic root resorption (OIIRR) and orthodontic teeth movement. MATERIALS AND METHODS: Forty Wistar rats (aged 11 weeks) were randomly divided into experimental group (EG; n = 20) that received a diet supplemented with CPP and control group (CG; n = 20) devoid of diet supplement. A 150 g force was applied using nickel titanium (NiTi) coil that was bonded on maxillary incisors and extended unilaterally to a maxillary first molar. At Day 28, animals in both groups were euthanized. Volumetric assessment of root resorption craters and linear measurement of maxillary first molars movement were blindly examined using a micro-computed tomography scan. RESULTS: Nine rats were excluded from the experiment due to loss during general anesthesia or appliances' failure. Intra-operator reproducibility was high in both volumetric and linear measurements, 92.8 per cent and 98.5-97.6 per cent, respectively. The results reveal that dietary CPP has statistically insignificant effect on the overall OIIRR and orthodontic movement. CONCLUSIONS: CPP seems to have statistically insignificant effect on the volume of OIIRR and orthodontic movement in rats. A long-term study with larger sample size using a different concentration of CPP is required to clarify the dentoalveolar effect of CPP.

Asymmetric Dental Development Investigated by Cone-Beam Computed Tomography in Patients With Unilateral Cleft Lip and Alveolus.

OBJECTIVE: To investigate a possible delay in dental development of cleft-side teeth compared with the contralateral teeth in patients with unilateral cleft lip and alveolus with or without cleft palate (UCLA ± CP) and to correlate this delay to developmental stages of the corresponding teeth. DESIGN: Cross-sectional study. SETTING: Cleft Lip and Palate Care Center of Shanghai Ninth People's Hospital, Shanghai, China. PATIENTS: Forty Chinese patients with UCLA ± CP. MAIN OUTCOME MEASURE: Crown height (CH), root length (RL), and full length (FL) of permanent incisors, canines, premolars, and first molars were measured using cone-beam computed tomography and compared between cleft and noncleft sides. Discrepancies in tooth length between sides during different developmental stages of delayed teeth were also compared. RESULTS: There were no statistically significant differences in tooth length between sides in the mandible, except for RL of lateral incisors and RL and FL of the second premolars. In the maxilla, CH, RL and FL of cleft-side incisors, as well as RL and FL of cleft-side canines and first premolars, were all significantly shorter than those on the noncleft side (P < .05). The lateral incisors showed the highest reductions in RL and FL (47% and 29%). Moreover, reduction of RL of cleft-side maxillary central incisors was most evident in the early developmental stage (23%) and decreased with dental maturation (5%). CONCLUSIONS: Asymmetric dental development was presented in both jaws but mainly in maxillary anterior region. The RL deficiency of cleft-side central incisors differed at different developmental stages.

Severe Class II Division 1 malocclusion in an adolescent patient, treated with a novel sagittal-guidance Twin-block appliance.

Class II malocclusion is a challenging anomaly in orthodontic practice. Various types of functional appliances are used to correct Class II skeletal and occlusal disharmonies in growing patients, including the Twin-block. We used a modified sagittal-guidance Twin-block appliance combined with a fixed appliance and microimplant anchorage to treat a 13-year-old Chinese boy with a severe skeletal Class II malocclusion and mandibular retrognathia. Normal overjet and a Class I molar relationship were achieved because of the advancement of mandibular development, the restriction of maxillary growth, and dentoalveolar modifications in both the maxilla and the mandible. Favorable skeletal, dental, and soft tissue relationships were accomplished after 24 months of treatment. After 2 years of retention, the results remained stable.

An Animal Model for Inducing Deviation of the Mandible.

PURPOSE: Altering the occlusal surface is still a common choice for inducing a deviated mandible in an animal model. Botulinum neurotoxin type A (BoTx/A) can block the action potential transmission in neuromuscular junctions by inhibiting acetylcholine release without damaging the nerves and muscle structures. Our present study was aimed at developing an easy-to-reproduce animal model of asymmetric mandibles in which injection of BoTx/A was applied. MATERIALS AND METHODS: A total of 96 healthy 4-week-old male Sprague-Dawley rats were divided into 2 groups: an experimental group (n = 48) with BoTx/A injection and a control group (n = 48) with sterile saline injection at 4 sites of the right masseter muscle. Twelve rats from each group were humanely euthanized at weeks 1, 2, 3, and 4 for morphometric analysis using the micro-computed tomography (CT) findings. RESULTS: The micro-CT scans revealed facial asymmetry in the experimental group, with no facial asymmetry in the control group after injection. Significant differences were found between the experimental and control groups regarding the indexes containing the mandibular length (length from condyle to menton, length from coronoid to menton, and length of mandibular corpus from gonion to menton) and ramus height (posterior border and middle region near coronoid, and height of anterior mandible at vertical distance from menton). CONCLUSION: Our data have indicated that this deviated mandible animal model induced by injection of BoTx/A is highly reproducible and might be proved suitable for future studies of the asymmetric mandible.

Asymmetric maxillary protraction for unilateral cleft lip and palate patients using finite element analysis.

OBJECTIVE: Unilateral cleft lip and palate (UCLP) patients frequently present with an asymmetry in the nasomaxillary complex and a maxillary hypoplasia. The aim of this study was to investigate biomechanic effects of asymmetric maxillary protraction in UCLP patients using finite element method. METHODS: A finite element model of a UCLP patient's skull was generated using data from spiral computed tomographic scans. On the basis of this finite element model, three groups of orthopedic forces were loaded. All forces were applied in a direction that was 30 degrees downward and forward to the occlusal plane on the region of the alveolar of the maxillary canine. The value of orthopedic force was 5 N in cleft side and 5 N in noncleft side (group A), 6 N in cleft side and 5 N in noncleft side (group B), and 7 N in cleft side and 5 N in noncleft side (group C), respectively. RESULTS: All 3 groups were effective in promoting maxilla forward. In group B, the displacement difference between the cleft side and the noncleft side was the smallest. The largest value difference between the cleft side and the noncleft side was found in group C. CONCLUSIONS: Maxillary protraction with a loading of 6 N in the cleft side and 5 N in the noncleft side produced the most favorable outcome. It can be suggested that it might be advantageous to perform asymmetric maxillary protraction on UCLP patients.

Correction of a skeletal Class II malocclusion with severe crowding by a specially designed rapid maxillary expander.

To correct an Angle Class II malocclusion or to create spaces in the maxillary arch by nonextraction treatment, distal movement of the maxillary molars is required. Various modalities for distalizing the buccal segment have been reported. Conventional extraoral appliances can be used to obtain maximum anchorage. However, many patients reject headgear wear because of social and esthetic concerns, and the success of this treatment depends on patient compliance. Intraoral appliances, such as repelling magnets, nickel-titanium coils, pendulum appliance, Jones jig appliance, distal jet appliance, and modified Nance appliance, have been introduced to distalize the molars with little or no patient cooperation. However, intraoral appliances can result in anchorage loss of the anterior teeth and distal tipping of the maxillary molars. In this case report, we introduce a diversified rapid maxillary expansion appliance that was custom designed and fabricated for the treatment of a growing girl with a skeletal Class II malocclusion and severe crowding from a totally lingually positioned lateral incisor. The appliance concomitantly expanded the maxilla transversely and retracted the buccal segment sagittally, distalizing the maxillary molars to reach a Class I relationship and creating the spaces to displace the malpositioned lateral incisor. The uniqueness of this special diversified rapid maxillary expansion appliance was highlighted by a series of reconstructions and modifications at different stages of the treatment to reinforce the anchorage.

Severe anterior open bite with mandibular retrusion treated with multiloop edgewise archwires and microimplant anchorage complemented by genioplasty.

In this case report, we introduce the combined use of multiloop edgewise archwire and microimplant anchorage to treat an 18-year-old Chinese woman who had a severe anterior open bite and a retrusive chin. Her diagnosis included a skeletal Class II base with severe anterior open bite, backward rotated mandible, and mesially tipped buccal dentition. The treatment plan emphasized vertical control of the posterior dentoalveolar dimension. Microimplant anchors were placed in the mandibular buccal segment to provide rigid anchorage and deliver intruding forces to the posterior teeth; a multiloop edgewise archwire was applied to generate uprighting forces to the maxillary and mandibular posterior teeth. Intrusion and uprighting of the posterior teeth contributed to the counterclockwise rotation of the mandibular plane, which consequently contributed to the facial profile improvement. Orthognathic genioplasty was implemented to further improve the chin prominence. After 1.5 years of retention, ideal intercuspation was evident, and the improved facial contour was stable.

Validation of the American Board of Orthodontics Objective Grading System for assessing the treatment outcomes of Chinese patients.

INTRODUCTION: Orthodontics in China has developed rapidly, but there is no standard index of treatment outcomes. We assessed the validity of the American Board of Orthodontics Objective Grading System (ABO-OGS) for the classification of treatment outcomes in Chinese patients. METHODS: We randomly selected 108 patients who completed treatment between July 2005 and September 2008 in 6 orthodontic treatment centers across China. Sixty-nine experienced Chinese orthodontists made subjective assessments of the end-of-treatment casts for each patient. Three examiners then used the ABO-OGS to measure the casts. Pearson correlation analysis and receiver operating characteristic curve analysis were conducted to evaluate the correspondence between the ABO-OGS cast measurements and the orthodontists' subjective assessments. RESULTS: The average subjective grading scores were highly correlated with the ABO-OGS scores (r = 0.7042). Four of the 7 study cast components of the ABO-OGS score-occlusal relationship, overjet, interproximal contact, and alignment-were statistically significantly correlated with the judges' subjective assessments. Together, these 4 accounted for 58% of the variability in the average subjective grading scores. The ABO-OGS cutoff score for cases that the judges deemed satisfactory was 16 points; the corresponding cutoff score for cases that the judges considered acceptable was 21 points. CONCLUSIONS: The ABO-OGS is a valid index for the assessment of treatment outcomes in Chinese patients. By comparing the objective scores on this modification of the ABO-OGS with the mean subjective assessment of a panel of highly qualified Chinese orthodontists, a cutoff point for satisfactory treatment outcome was defined as 16 points or fewer, with scores of 16 to 21 points denoting less than satisfactory but still acceptable treatment. Cases that scored greater than 21 points were considered unacceptable.

[A reflectional insight into orthodontic theoretical renovation and technological innovation].

Orthodontics, among other specialties in dentistry, remains most dynamic and vigorous in upgrading and reforming its fundamental doctrines and clinical technologies. Orthodontic specialty in China has played a leading role in recent years in reshaping fundamental theories and in creating cutting-edge therapeutic modalities. The newly developed diagnostic classification system, a complementary addition to that of Angle's, not only defines the natures, but also identifies the developmental mechanisms of malocclusions. Orthopedic therapy aiming to relocate the mandible before correcting the dentition is emerging as an indispensable treatment mode to malocclusions concurring with mandibular deviation. Whilst correlations exist between malocclusion and TMD susceptibility and incidence, the specifically designed orthopedic and orthodontic approaches have proven effective in managing cases inflicted by TMD conditions. Innovative efforts that create the GS products, have redefined the clear appliances much more beyond merely clear aligners, thus further pushing the boundaries of both the indications and clinical use for clear appliances.

Metal-organic Zn-zoledronic acid and 1-hydroxyethylidene-1,1-diphosphonic acid nanostick-mediated zinc phosphate hybrid coating on biodegradable Zn for osteoporotic fracture healing implants.

Zn and its alloys are increasingly under consideration for biodegradable bone fracture fixation implants owing to their attractive biodegradability and mechanical properties. However, their clinical application is a challenge for osteoporotic bone fracture healing, due to their uneven degradation mode, burst release of zinc ions, and insufficient osteo-promotion and osteo-resorption regulating properties. In this study, a type of Zn2+ coordinated zoledronic acid (ZA) and 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) metal-organic hybrid nanostick was synthesized, which was further mixed into zinc phosphate (ZnP) solution to mediate the deposition and growth of ZnP to form a well-integrated micro-patterned metal-organic/inorganic hybrid coating on Zn. The coating protected noticeably the Zn substrate from corrosion, in particular reducing its localized occurrence as well as suppressing its Zn2+ release. Moreover, the modified Zn was osteo-compatible and osteo-promotive and, more important, performed osteogenesis in vitro and in vivo of well-balanced pro-osteoblast and anti-osteoclast responses. Such favorable functionalities are related to the nature of its bioactive components, especially the bio-functional ZA and the Zn ions it contains, as well as its unique micro- and nano-scale structure. This strategy provides not only a new avenue for surface modification of biodegradable metals but also sheds light on advanced biomaterials for osteoporotic fracture and other applications. STATEMENT OF SIGNIFICANCE: Developing appropriate biodegradable metallic materials is of clinical relevance for osteoporosis fracture healing, whereas current strategies are short of good balance between the bone formation and resorption. Here, we designed a micropatterned metal-organic nanostick mediated zinc phosphate hybrid coating modified Zn biodegradable metal to fulfill such a balanced osteogenicity. The in vitro assays verified the coated Zn demonstrated outstanding pro-osteoblasts and anti-osteoclasts properties and the coated intramedullary nail promoted fracture healing well in an osteoporotic femur fracture rat model. Our strategy may offer not only a new avenue for surface modification of biodegradable metals but also shed light on better understanding of new advanced biomaterials for orthopedic application among others.

The effects of maxillary protraction and its long-term stability--a clinical trial in Chinese adolescents.

The purpose of this study was to evaluate the effect of reverse pull headgear (RPHG) in the treatment of Class III malocclusions in the late mixed and early permanent dentition and its long-term stability at the time when facial growth was close to completion. The treatment group comprised 22 subjects (12 males and 10 females, mean age: 11.38 ± 0.69 years). The control group included 17 subjects (7 males and 10 females, mean age: 11.54 ± 1.07 years). The mean RPHG treatment time was 1.5 ± 0.95 years and the observation time for the control group was 1.75 ± 0.83 years. For each subject, lateral cephalograms were obtained before (T1) and after (T2) treatment or observation. These cephalograms were traced and analyzed and the differences between T1 and T2 values were examined with paired t-tests. Of the 22 treated cases, 10 patients were followed up until at the mean age of 16.18 years (T3). Since there was no relapse in anterior crossbite, the long-term effects of RPHG were evaluated by measuring the maxillary and mandibular skeletal changes. The follow-up patients were divided into two groups based on the change in ANB: a stable group (decrease in ANB < 2 degrees) and an unstable group (decrease in ANB > 2 degrees). The skeletal effects of RPHG in treating Class III anomalies just before or at the beginning of the pubertal growth spurt include protraction of the maxilla and dentition and inhibition of forward growth of the mandible. With regard to the long-term change, a slight alteration in the position of the maxilla and in the position and growth direction of the mandible resulted in a slight decrease in ANB in the stable group. The slight retrusion in the maxilla, combined with the significant protrusion in the mandible and the more horizontal mandibular growth direction, resulted in a decrease in ANB in the unstable group. This indicated that the maxilla remained relatively stable and that the unstable factor was continuing mandibular growth during the pubertal and post-pubertal period. For patients with an excessive mandible, orthopaedic therapy should start at the beginning of pubertal growth and orthodontic fixed appliance should follow immediately after RPHG so that mandibular growth in the sagittal direction during puberty or even after pubertal growth may be effectively inhibited.

[Consistency of the subjective evaluation of malocclusion severity by the Chinese orthodontic experts].

OBJECTIVE: To assess the consistency of the subjective evaluation of malocclusion severity by the Chinese orthodontic experts. METHODS: Sixty-nine Chinese orthodontic experts subjectively evaluated the malocclusion severity for 120 cases which were selected randomly from 6 University orthodontic clinics by checking each case's pretreatment records including study cast, lateral head film, panoramic radiograph, facial photographs and patient chart. Each orthodontist was asked to independently rate the severity of every case into five grades: mild, mildly moderate, moderate, severely moderate and severe. Rating data was finally gathered to evaluate the intra-judge's reliability and the inter-judges' consistency. RESULTS: Weighted Kappa test revealed that 8.33% orthodontists showed excellent intra-judge's reliability (Kappa ≥ 0.81), 78.33% orthodontists showed good intra-judge's reliability (Kappa ≥ 0.61) and 96.67% specialists displayed general intra-judge's reliability (Kappa ≥ 0.41). And intra-class correlation coefficient demonstrated a high level of inter-judges' consistency (r=0.989, P<0.01). CONCLUSION: Good intra-judge's reliability and inter-judges' consistency can be demonstrated in the subjective evaluation of malocclusion severity by the Chinese orthodontic experts, which could the basis for establishing the objective grading system of malocclusion severity.

[Malocclusions with mandibular positional deviation: etiological factors, therapeutic restorations and clinical fundamentals].

The definition for a normal mandibular position in orthodontic regime includes two perspectives: an occlusion with maximum contacts with Class I inter-digitation, and an integrated relation between the components within temporomandibular joint (TMJ). Any displacement or deviation of the mandible from its normal position may result in anomalies in occlusion. Mandibular displacement can occur due to either physiological or pathological factors. The physiological deviation of the mandible at sagittal dimension is often caused by the phenomenon where the mandible moves forward or backward to coordinate and match the transverse width with the upper dentition. The physiological deviation of the mandible at transverse dimension, on the other hand, is mainly generated by the scenario where the mandible relocates its position to avoid some regional occlusal irregularities. The pathological deviation of the mandible at sagittal dimension is often taking place when condylar resorption progresses, leading the mandible to retrude backwards. Nevertheless, if the pathological degrading or hyperplasia of the condyles between two sides are unparalleled and asymmetrical, mandibular shift at transverse dimension would occur. The therapeutic restoration of the malpostioned mandible aims to relocate the deviated lower jaw into its relatively normal position, enabling a subsequent correction of the malocclusion. Bite registration and recording based on mandibular re-localization remain the vital and critical procedures in clinical practice. With the advent of clear aligner orthodontics, the clear versions of orthopedic modalities, namely, S8, S9 and S10, are specifically designed to alleviate mandibular displacement, therefore escalating the treatment efficacy by repositioning the mandible and correcting the individual teeth simultaneously. Condylar endochondral ossification triggered by mandibular repositioning not only consolidates the restorative posture of the mandible, but more importantly, repairs the deteriorating condyles and subsequently relieves temporomandibular disorder (TMD) conditions.

Dynamic alternations of RANKL/OPG ratio expressed by cementocytes in response to orthodontic­induced external apical root resorption in a rat model.

The aim of the present study was to investigate the alterations in the formation of cementocytes in response to orthodontic forces and to evaluate the contribution of these cells in the biological changes of tooth movement and associated root resorption. A total of 90 Sprague Dawley rats were randomly assigned to the control, high force, and low force groups. Intrusion forces of 10 and 50 g were applied on the rat molar to induce tooth intrusion. The tooth movement was observed from 0 to 14 days by micro­computed tomography, bone histometric analysis, tartrate­resistant acid phosphatase staining, as well as reverse transcription­quantitative PCR and immunofluorescence staining assays. The results suggested that under low force conditions, osteoclasts were distributed at a higher frequency on the bone side than on the root side. Under high force conditions, both sides suffered osteoclast infiltration. In the low force group, the cementocytes exhibited downregulated sclerostin (SOST) and osteoprotegerin (OPG) mRNA levels and a lower receptor activator of nuclear factor­κB ligand (RANKL)/OPG ratio over a certain period of time. The expression levels of these genes were lower compared with those of the osteocytes at each time­point. In the high force group, both cementocytes and osteocytes upregulated the SOST and RANKL/OPG ratio on days 7 and 14, while the cementocytes expressed higher levels of SOST mRNA than those noted in the osteocytes. These data suggested that cementocytes responded to the orthodontic force via modulation of the RANKL/OPG ratio and SOST expression. The biological response of cementocytes contributed to the mechanotransduction and homoeostasis of the roots under compression. Excessive forces may act as a negative factor of this regulatory role. These results expand our knowledge on the function of cementocytes.

[Establishment of a 3-dimentional finite element system simulating En masse retraction implemented by customized lingual appliances].

PURPOSE: This study was designed to establish a 3-dimentional finite element system to simulate the clinical scenario where labial segment was retracted with sliding mechanism in extraction cases treated by individualized lingual orthodontics. METHODS: A typical clinical case was selected. The subject was diagnosed with Class I malocclusion with alveolar protrusion and treated with extraction of 4 first premolars. The subject was under the treatment stage of frontal retraction by eBrace system, an individualized lingual appliance. The subject was also taken cone-beam CT (CBCT) based on which digital 3D reconstruction of dentition structures was formed with Mimics software. With the aid of software platform Pro/E 4.0, the important anatomical structures were defined, and relevant lingual devices, including lingual brackets, arch-wires, mini-screws and other accessories were formed. With the aids of software platform Geomagic Studio 13.0, the 3-dimentional structural mode, featuring maxillary alveolar, upper dentition, periodontal ligament, miniscrew and lingual applicance, were constructed. With the assistance of Ansys Workbench 15.0, 3D model for finite element system was finalised by conducting model meshing and defining the mechanical properties and the interface relations of the selected materials. RESULTS: Based on the digital information drawn from CBCT image, a 3-dimentional finite element system was successfully created, featuring all the elements mimicking the clinical scenario for En masse retraction. This system enabled an insight study on the effects of various retraction modes controlling the incisal torque and maintaining the dental arch integrity. CONCLUSIONS: The creation of a finite element system in this study is based on the digital data from the CBCT image of a real patient diagnosed with prognathic malocclusion and treated by lingual appliance. The clinical scenario of labial segment retraction via sliding mechanism is simulated in this finite element model.

[Expression of TNFAIP6 in oral verrucous carcinoma and oral squamous cell carcinoma and its relationship with clinicopathology].

PURPOSE: This study was designed to establish a 3-dimentional finite element system to simulate the clinical scenario where labial segment was retracted with sliding mechanism in extraction cases treated by individualized lingual orthodontics. METHODS: A typical clinical case was selected. The subject was diagnosed with Class I malocclusion with alveolar protrusion and treated with extraction of 4 first premolars. The subject was under the treatment stage of frontal retraction by eBrace system, an individualized lingual appliance. The subject was also taken cone-beam CT (CBCT) based on which digital 3D reconstruction of dentition structures was formed with Mimics software. With the aid of software platform Pro/E 4.0, the important anatomical structures were defined, and relevant lingual devices, including lingual brackets, arch-wires, mini-screws and other accessories were formed. With the aids of software platform Geomagic Studio 13.0, the 3-dimentional structural mode, featuring maxillary alveolar, upper dentition, periodontal ligament, miniscrew and lingual applicance, were constructed. With the assistance of Ansys Workbench 15.0, 3D model for finite element system was finalised by conducting model meshing and defining the mechanical properties and the interface relations of the selected materials. RESULTS: Based on the digital information drawn from CBCT image, a 3-dimentional finite element system was successfully created, featuring all the elements mimicking the clinical scenario for En masse retraction. This system enabled an insight study on the effects of various retraction modes controlling the incisal torque and maintaining the dental arch integrity. CONCLUSIONS: The creation of a finite element system in this study is based on the digital data from the CBCT image of a real patient diagnosed with prognathic malocclusion and treated by lingual appliance. The clinical scenario of labial segment retraction via sliding mechanism is simulated in this finite element model.

A novel technique for presurgical nasoalveolar molding using computer-aided reverse engineering and rapid prototyping.

OBJECTIVE: To establish a new method of presurgical nasoalveolar molding (NAM) using computer-aided reverse engineering and rapid prototyping technique in infants with unilateral cleft lip and palate (UCLP). METHODS: Five infants (2 males and 3 females with mean age of 1.2 w) with complete UCLP were recruited. All patients were subjected to NAM before the cleft lip repair. The upper denture casts were recorded using a three-dimensional laser scanner within 2 weeks after birth in UCLP infants. A digital model was constructed and analyzed to simulate the NAM procedure with reverse engineering software. The digital geometrical data were exported to print the solid model with rapid prototyping system. The whole set of appliances was fabricated based on these solid models. RESULTS: Laser scanning and digital model construction simplified the NAM procedure and estimated the treatment objective. The appliances were fabricated based on the rapid prototyping technique, and for each patient, the complete set of appliances could be obtained at one time. By the end of presurgical NAM treatment, the cleft was narrowed, and the malformation of nasoalveolar segments was aligned normally. CONCLUSIONS: We have developed a novel technique of presurgical NAM based on a computer-aided design. The accurate digital denture model of UCLP infants could be obtained with laser scanning. The treatment design and appliance fabrication could be simplified with a computer-aided reverse engineering and rapid prototyping technique.