Periosteum coverage versus collagen-membrane coverage in periodontally accelerated osteogenic orthodontics: a randomized controlled clinical trial in Class II and Class III malocclusions.

BACKGROUND: Periodontal accelerated osteogenic orthodontics (PAOO) is a widely-used clinical procedure that combines selective alveolar corticotomy, particulate bone grafting, and the application of orthodontic forces. Different modifications of PAOO such as collagen-membrane coverage can better benefit patients from preventing displacement of grafts. Due to its stability, collagen-membrane coverage gradually gained popularity and became a widely-used procedure in traditional PAOO technique. OBJECTIVES: To quantitatively investigate the radiographic changes of alveolar bone, periodontal soft tissue changes of the mandibular anterior teeth and postoperative complications in periosteum-covered techniques compared with traditional surgical technique in PAOO. METHODS: Orthodontic camouflage for dental Class II or decompensation for skeletal Class III malocclusions were included; Patients with bone defects on the buccal aspects of the anterior mandible regions confirmed by clinical and radiographic examination were randomly divided into the periosteum coverage group or traditional technique group for PAOO. Cone-beam computerized tomography (CBCT) scans were obtained before treatment (T0) and 1 week (T1) and 12 months (T2) after operation. The primary outcome variable was the vertical alveolar bone level (VBL), the secondary evaluation parameters included labial horizontal bone thickness at the midpoint of the middle third (MHBT) or apical third (AHBT) to the limit of the labial cortical surface during a 12-month follow-up. Postoperative sequelae were evaluated after 2 days and 7 days in both the groups. Periodontal parameters were analyzed at T0 and T2. RESULTS: Thirty-six adult subjects were eligible and recruited in the present study. Although experimental group exhibited more severe infection, no significant differences of the postoperative symptoms or periodontal parameters was found between the 2 groups (P > 0.05). All patients were examined respectively using CBCT at baseline (T0), postoperative 1 week (T1) and 12 months (T2). Both alveolar bone height and width increased from T0 to T1 (P < 0.001) and then reduced from T1 to T2 (P < 0.001) in both groups. However, significant bone augmentation was achieved in each group from T0 to T2 (P < 0.001). Furthermore, the vertical alveolar bone augmentation in the experimental group increased significantly than that in the traditional surgery (P < 0.05). CONCLUSIONS: Compared with traditional PAOO surgery, the periosteum-covered technique provides superior graft stabilization and satisfactory vertical bone augmentation in the labial mandibular anterior area.

Timing of force application on buccal tooth movement into bone-grafted alveolar defects: A pilot study in dogs.

INTRODUCTION: The aim of this pilot study was to evaluate the effect of the timing of postoperative orthodontic force application on bone remodeling during tooth movement into surgical alveolar defects with bone grafts in beagle dogs. METHODS: Six beagle dogs underwent surgery for buccal dehiscence-type defects (width, 5 mm; height, 6 mm) on the distal root of maxillary second premolars bilaterally for 12 defects. After 1-month healing, bone-augmentation procedures were undertaken at the dehiscence defects. The second premolars were protracted buccally for 6 weeks into the surgical sites immediately (F-0), at 4 weeks (F-4), or 8 weeks (F-8) after grafting. Orthodontic tooth movement was monitored using digital models. Remodeling of alveolar bone was evaluated by histology, histomorphometry, immunohistochemistry, microcomputed tomography, and fluorescence microscopy. RESULTS: Group F-0 showed significant expansion (mean, 2.42 mm) and tipping (mean, 9.03°) after completing orthodontic tooth treatment. The vertical bone defect was significantly lower in groups F-4 and F-8 than that in group F-0 (mean, 2.1, 2.7, and 4.5 mm, respectively). In group F-4, the formation of new bone and mineralization were significantly greater than those in groups F-0 and F-8 (P <0.05). Group F-4 showed a minimal amount of bone-material remnants. Immunohistochemistry showed the highest expression of collagen-1 and osteopontin in group F-4, followed by group F-8 and group F-0, which demonstrated high osteoblast activity and enhanced bone remodeling in group F-4. CONCLUSIONS: Orthodontic force application at 4 weeks after an augmentation procedure provided the best functional stimulation for an alveolar bone graft. This strategy enhanced new-bone regeneration and degradation of bone substitutes and, eventually, promoted bone remodeling in the bone-grafted area.

Membrane fixation for osseous graft stabilization in periodontally accelerated osteogenic orthodontics: a comparative study.

BACKGROUND: Periodontally accelerated osteogenic orthodontics (PAOO) is a treatment for bone defects associated with a lack of bone graft stability, especially in coronal locations. This study aimed to compare a modified technique of membrane fixation that utilizes periosteal sutures (using a pouch design) with the traditional approach, which does not use membrane fixation. METHODS: Twenty-eight patients with a total of 168 teeth treated were divided into two groups: 1-A, in which patients were treated using the modified technique (with membrane fixation), and group 2-B, in which patients were treated using the traditional technique (without membrane fixation). The postoperative bone thickness was evaluated via radiographic examination. RESULTS: Postoperative improvements in bone augmentation were detected in both groups. At 12 months, the values of the CHBT (measured from the midpoint of the coronal third to the labial cortical surface, 0.84 ± 0.33 mm) and the values of VBL (measured from the alveolar crest to the cemento-enamel junction, - 2.35 ± 0.80 mm)were significantly greater in the modified technique group than those in the traditional technique group (CHBT:0.12 ± 0.21 mm and VBL:-1.39 ± 0.99 mm; P = 0.00 and P = 0.01). CONCLUSIONS: This study shows that compared to the traditional technique, the modified PAOO technique with membrane fixation using periosteal sutures provides improved graft stabilization, superior coronal augmentation and satisfactory vertical volume.

A Novel Surgical Technique for Augmented Corticotomy-Assisted Orthodontics: Bone Grafting With Periosteum.

PURPOSE: To introduce grafting fixed with the periosteum (dumpling technique) as an alternative surgical technique for augmented corticotomy-assisted orthodontics in the lower anterior region and evaluate the preliminary outcomes. MATERIALS AND METHODS: Eleven patients (9 women, 2 men; mean age, 21.4 yr) with a thin alveolus or alveolar defect in the lower anterior region by clinical and radiographic examination underwent an augmented corticotomy using the new dumpling technique. Cone-beam computerized tomography was used to evaluate morphologic changes of the lower anterior ridge before treatment (T0) and 1 week (T1) and 6 months (T2) after the bone-augmentation procedure. Repeated-measures analysis of variance with Bonferroni multiple-comparison test was used to compare variables at each time point. RESULTS: No severe postsurgical complications occurred in any patient. The mean alveolar bone thickness of the labial plate increased from T0 to T1 (P < .001) and decreased from T1 to T2 (P < .001). However, compared with T0, there was still a significant increase in horizontal bone thickness at T2 (P < .05). The vertical alveolar bone level increased from T0 to T1 (P < .001) and was maintained from T1 to T2 (P > .05). No significant differences were found in root length of the lower anterior teeth at these 3 time points (P > .05). CONCLUSIONS: In this preliminary study, the dumpling technique for augmented corticotomy-assisted surgical orthodontics showed alveolar bone augmentation by increasing the vertical alveolar height and the horizontal bone thickness in the labial aspect of the anterior mandibular area. However, long-term follow-up is necessary.

Feasibility of simultaneous TMJ arthroscopy in ADDwoR patients undergoing orthognathic surgery for jaw deformity.

This study evaluated the feasibility of simultaneous temporomandibular joint (TMJ) arthroscopy and orthognathic surgery as a new treatment strategy for anterior disc displacement without reduction (ADDwoR) patients with severe jaw deformities. Twelve ADDwoR patients with facial deformities who underwent arthroscopy and orthognathic surgery between September 2015 and December 2019 were retrospectively evaluated. Pre- and postoperative maximum incisal opening (MIO) and joint pain were recorded. Computed tomography (CT) and three-dimensional cephalometric analysis were performed at 3 (T1) and ≥6 (T2) months postoperatively. Magnetic resonance imaging (MRI) of the TMJ was performed before, ≤7 days after and ≥6 months after surgery. The lateral profile radiological findings, the symmetry of the maxilla and mandible, and the MRI measurements were compared. Anterior disc displacement did not recur, and the maximum incisal opening (MIO) increased from 27.4 mm to 32.7 mm after surgery (p < 0.05). No significant differences were found in the lateral profile, symmetry indices or condylar height via MRI between T1 and T2. Joint morphology and the position of both the maxilla and mandible remained stable during postoperative follow-up, while joint symptoms were markedly relieved and facial appearance was noticeably improved. Combined arthroscopy and orthognathic surgery is effective and recommended for ADDwoR patients with jaw deformities.

Association between bilateral condylar resorption and reduced volumes of the craniofacial skeleton and masticatory muscles in adult patients: A retrospective study.

Objectives: This retrospective cohort study aimed to analyze volumes of craniomaxillofacial bone and masticatory muscles of young adults with bilateral idiopathic condylar resorption. Methods: This was a retrospective cohort study of 84 adults with bilateral idiopathic condylar resorption (BCR) and 48 adults with normal temporal-mandibular joint (TMJ) matched for age and sex (mean age, 23.2 ± 3.6 years). The volumes of craniomaxillofacial bone and masticatory muscles, as well as intercondylar angle were measured. Unpaired t-tests and Pearson correlation tests were applied to analyze the data. Multivariable linear regression models were used to estimate the association between bilateral condylar volume and volumes of craniomaxillofacial bone and masticatory muscles adjusted for age, sex, and disc status. Results: Compared to the control group, the BCR group displayed significant decreased volumes of craniomaxillofacial bone (p < 0.001), craniomaxillofacial bone without mandible (p < 0.001), mandible (p < 0.001), mandible without mandibular condylar process (p < 0.001), bilateral masseter muscle (p < 0.001) and bilateral temporalis muscle (p < 0.001), as well as the intercondylar angle (p < 0.001). These variables were significantly correlated to the volume of mandibular condylar process (0.5< r < 0.8; p < 0.001). By linear regression analyses, significant associations were found for the bilateral condylar volume with craniomaxillofacial bone volume and mandible bone volume. Conclusions: Young adults with BCR displayed smaller volumes of craniomaxillofacial skeleton and masticatory muscles, and smaller intercondylar angle than the normal patients. The craniofacial musculoskeletal volume and intercondylar angle are associated with mandibular condylar process volume.

Marsupialization facilitates eruption of dentigerous cyst-associated mandibular premolars in preadolescent patients.

PURPOSE: The purpose of the present study was to investigate the eruption of dentigerous cyst (DC)-associated mandibular premolars after marsupialization in preadolescents. PATIENTS AND METHODS: The present study was a retrospective cohort study of preadolescent patients with DCs who were treated as outpatients at the Department of Oral and Maxillofacial Surgery, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine. For our study, the data from these patients were collected, and the eruption of the premolar teeth, along with related factors, such as the interval to eruption, cusp depth, angulation, cyst size, and eruption space, were analyzed for the cyst group compared with the noncyst control group. RESULTS: The mean age of the patients was 9.1 years. All teeth associated with DCs erupted successfully after marsupialization. The follow-up panoramic radiograph showed that the cysts had disappeared and had been replaced by regenerated bone. The initial panoramic radiograph showed the angulation of the teeth in the cyst group had a significantly larger inclination angle than did the teeth in the noncyst group (P < .05). However, no significant difference was found for cusp depth, root formation, or space measurement. The gender, age, cusp depth, angulation, and eruption space were not factors influencing the eruption of the DC-associated tooth for preadolescent patients in the present study. In addition, the cyst-associated teeth took less time to erupt than the teeth in the control group. CONCLUSIONS: The results of the present study suggest that DC-associated mandibular premolars can erupt spontaneously after marsupialization in preadolescents.

An orthodontic technique for minimally invasive extraction of impacted lower third molar.

PURPOSE: To present a novel orthodontic approach for minimally invasive extraction of impacted mandibular third molars (M3s) close to the inferior alveolar nerve (IAN). PATIENTS AND METHODS: Eight patients (8 M3s) requiring extraction of M3s were included in this study; there were 2 cases of horizontal impaction, 4 of mesioangular impaction, and 2 of vertical impaction. Cone-beam computed tomogram showed that the roots of impacted M3s in 2 cases interrupted the cortices of the mandibular canal, and those in the other 6 cases were very close to the IAN. Orthodontic treatment was performed in this study. The crowns of 5 impacted teeth were surgically exposed before the application of the orthodontic device, whereas bonding was performed directly to the occlusal surface of the other 3 M3s, which had partially erupted. The opposing maxillary M3s were removed in 3 cases. One-step orthodontic extraction was applied to vertically impacted M3s and 2-step treatment was applied to horizontally or mesioangularly impacted M3s. Success was defined as the separation of the impacted tooth from the IAN as visualized on cone-beam computed tomogram. RESULTS: After orthodontic treatment, all impacted M3s were extruded and separated from the IAN (mean, 6.6 months; range, 4 to 10 months), without any neurologic consequences. The average time of extraction was 5 minutes. In all 8 cases, new bone formation occurred distal to the adjacent second molar. CONCLUSION: This orthodontic technique may be a minimally invasive approach for the extraction of impacted M3s adjacent to the IAN, with a decreased risk of paresthesias and with osteoperiodontal advantages.

Role of periosteum in alveolar bone regeneration comparing with collagen membrane in a buccal dehiscence model of dogs.

To investigate the role of periosteum on the treatment of buccal dehiscence defects comparing with collagen membrane in canine model. Bilateral dehiscence-type defects at the buccal side on the distal root of the lower 3rd/4th premolars were created in six beagle dogs with a total of 24 defects and assigned into three groups: Group A: blood clot in an untreated defect; Group B: deproteinized bovine bone material (DBBM) covered with an absorbable membrane; Group C: DBBM covered with the periosteum. The structural parameters for trabecular architecture and vertical bone regeneration were evaluated. Histological and histomorphometric evaluation were carried out to observe new bone formation and mineralization in the graft site. Immunohistochemical analysis was performed to identify the expression of osteopontin (OPN) and osteocalcin (OCN) at postoperative 3 months. Group C achieved greater vertical alveolar bone gain than that of group A and group B. The periosteum-covered group showed significantly greater new bone formation and accelerated mineralization. The greater immunolabeling for OPN and OCN was observed in group C than in group A. Periosteal coverage has explicit advantages over collagen membranes for the quality and quantity of new bone regeneration in dehiscence defects repairing.

N-MID, P1NP, ß-CTX, and phosphorus in adolescents with condylar resorption.

OBJECTIVE: Condylar resorption (CR) is a temporomandibular joint disease that causes various physical or functional defects. We aimed to find the association between CR and bone metabolism levels. STUDY DESIGN: In this study, we recruited patients visiting the Orthodontic Clinic at Shanghai Ninth People's Hospital from January 2020 to September 2021. Patient characteristics, magnetic resonance imaging examination results, bone mineral density (BMD), Z-score, bone turnover markers, minerals, and hormones were collected and analyzed. RESULTS: The 89 participants were divided into CR (n = 46) and normal (n = 43) groups. Univariate logistic regression showed that N-terminal mid-fragment of osteocalcin (N-MID), procollagen type 1 N-terminal propeptide (P1NP), ß-C-terminal telopeptide of type 1 collagen (ß-CTX), and phosphorus (P < .001 for all) were protective factors, and BMD (P = .047) was a risk factor for CR. Multivariable logistic regression showed that N-MID, P1NP, ß-CTX, and phosphorus (odds ratio <1, P < .05 for all) were protective factors for CR. Receiver operating characteristic curves showed these indicators to effectively predict CR occurrence (area under the curve >0.7; P < .001). CONCLUSION: Adolescents with low serum N-MID, P1NP, ß-CTX, and phosphorus levels were associated with a higher risk of CR. We suggest that these indicators can guide clinicians in the early detection and prevention of CR in adolescents.

Functional orthodontics after arthroscopic disk repositioning in adolescent anterior disk displacement with mandibular retrusion.

OBJECTIVE: Condylar remodeling is crucial in retrognathic adolescents with anterior disk displacement without reduction (ADDwoR). This study aimed to evaluate the efficacy of functional orthodontics after arthroscopic disk repositioning surgery in improving condylar remodeling. STUDY DESIGN: A retrospective cohort study was performed to evaluate the condylar remodeling in patients with retrognathic unilateral ADDwoR who received arthroscopic disk repositioning surgery from March 2013 to December 2017. The primary predictor variable was functional orthodontics, based on which patients were divided into group A and group B. The outcome variables were condylar remodeling on both the affected side and the unaffected side measured by using the 3-circle method. The independent-sample t test was performed to test the difference between the 2 groups. A P value less than 0.05 was considered significant. RESULTS: In total, 117 patients (28 males and 109 females) were included in our study, with 75 cases in group A (follow-up: 7.48 months) and 62 cases in group B (follow-up: 7.95 months). Group A showed better condylar remodeling on the affected side compared with group B, but there was no significant difference on the unaffected side. CONCLUSIONS: Functional orthodontics after arthroscopic disk positioning leads to improved condylar remodeling in patients under 17 years of age with ADDwoR and mandibular retrusion.

Effect of Attapulgite-Doped Electrospun Fibrous PLGA Scaffold on Pro-Osteogenesis and Barrier Function in the Application of Guided Bone Regeneration.

PURPOSE: Guided bone regeneration (GBR) therapy, which is a widely used technique in clinical practice and is effective in improving the repair of alveolar bone defects or bone mass deficiency regeneration, requires the use of membrane materials with good biocompatibility, barrier function, rigidity matching the space maintenance ability, economic benefits and excellent clinical applicability. The aim of this study was to develop an electrospun attapulgite (ATT)-doped poly (lactic-co-glycolic acid) (PLGA) scaffold (PLGA/ATT scaffold) as a novel material for GBR applications. METHODS AND RESULTS: Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to determine the morphology and the crystalline structure of the PLGA/ATT scaffolds, respectively. Porosity and contact-angle measurements were also carried out to further characterize the physical properties of the PLGA/ATT scaffolds. The results of in vitro studies showed that bone marrow mesenchymal stem cells (BMSCs) attached more readily to and spread better over the PLGA/ATT scaffolds than the Bio-Gide membrane. Furthermore, in the in vitro osteoinductive experiments with BMSCs, the PLGA/ATT scaffolds were found to enhance the activity of alkaline phosphatase (ALP), promote the formation of mineralized bone nodules, and up-regulate the expression of several osteogenic markers-namely, runt-related transcription factor 2, alkaline phosphatase, osteopontin, and osteocalcin-which are similar to the effects of the Bio-Gide membrane. Further, in in vivo studies, the results of sequential fluorescent labeling, micro-computed tomography, and histological analysis suggest that using the PLGA/ATT scaffolds for repairing V-shaped buccal dehiscence on a dog's tooth root improved bone regeneration, which is not only similar to the result obtained using the Bio-Gide membrane but also much better than that obtained using PLGA scaffolds and the negative control. CONCLUSION: To achieve satisfactory therapeutic results and to lower the cost of GBR treatment, this study provided a promising alternative material of bio-degradable membrane in clinical treatment.

Can anterior repositioning splint effectively treat temporomandibular joint disc displacement?

The aim of this study was to determine whether anterior repositioning splint (ARS) can effectively treat temporomandibular joint (TMJ) anterior disc displacement with reduction (DDwR) in juvenile Class II patients. This study investigated disc repositioning clinically and through use of MRI with 12-month follow up. Patients with skeletal Class II malocclusions and DDwR diagnosed by magnetic resonance imaging (MRI) were treated with ARS. The efficacy of ARS was assessed clinically and by means of MRI before treatment (T0), immediately after bite registration (T1), at the end of treatment (T2), and at 12 months after functional appliance treatment (T3). Improvement in TMJ pain, TMJ noises, and range of mandibular movement were assessed. MRI evaluation was based on disc-condylar relationship in parasagittal images. Seventy-two juvenile patients with 91 joints were included in this study. The average age was 15.7 years old (range, 10-20 years) at first visit. There were statistically significant reductions in TMJ pain, disability in daily life and TMJ clicking (P < 0.01). MRI at T2 indicated that the success rate was 92.31% (84/91), but decreased to 72.53% (66/91) at T3. The unsuccessful splint disc capture was mainly observed in late adolescence, especially over 18 years old. Using MRI results as the gold standard, we found that clinical assessment had an accuracy rate of 75.82% at 12-month follow-up. In conclusion, although success rate for ARS treatment decreased over time, both clinical findings and MRI examination indicate that the ARS is relatively effective in repositioning the DDwR, especially for patients in early puberty. However, further and larger studies are needed to evaluate the outcome with ARS.

Occlusal adjustment after local resection of type 1 condylar osteochondroma.

To evaluate the feasibility of the orthodontic traction after local resection of the condylar osteochondroma (OC).From November 2011 to September 2016, consecutive patients with condylar OC who underwent orthodontic extraction after local resection of the mass were reviewed. Clinical data and cone-beam computed tomography (CT) were obtained before treatment (T0), 1 week after surgery (T1), and at least 6-month follow-up after OC resection (T2). Repeated-measures analysis of variance with Bonferroni multiple-comparison test was used to compare the 3-dimensional cephalometric variables at different time points and the paired t test was used to compare changes of temporomandibular joint (TMJ) space between the 2 sides at T1 and T2.The sample consisted of 23 patients (16 females and 7 males). The mean postoperative follow-up interval was 10.9 months. No recurrence was observed during the postoperative follow-up period. Facial symmetry and occlusion were greatly improved. B deviation and the distance of gonion on the OC-affected side to the Frankfort horizontal (FH) were significantly improved from T0 to T1 and T2 (P < .01). The anterior space (AS) and superior space (SS) of the OC-affected side were significantly larger than that of the contralateral side at T1 in parasagittal CT views (P < .05), while no difference was found between the two sides at T2.Local resection is an effective technique with less damage to the condyle. The application of postoperative directional traction could guide the condyle into the fossa, achieve normal TMJ space and stable occlusion, and eventually provide functional and esthetic outcomes.

A new modified bone grafting technique for periodontally accelerated osteogenic orthodontics.

The aim of this study was to introduce an improved surgical technique using a pouch design and tension-free wound closure for periodontally accelerated osteogenic orthodontics (PAOO) in the anterior alveolar region of the mandible.Patients with bone dehiscence and fenestrations on the buccal surfaces of the anterior mandible region underwent the modified PAOO technique (using a pouch design and tension-free closure). Postoperative symptoms were evaluated at 1 and 2 weeks intervals following the procedure. Probing depth (PD), gingival recession depth (GRD), and clinical attachment level (CAL) were assessed at the gingival recession sites at baseline, postoperative 6 and 12 months. Cone-beam computerized tomography (CBCT) was used for quantitative radiographic analyses at baseline, 1 week and 12 months after bone-augmentation procedure.The sample was composed of a total of 12 patients (2 males and 10 females; mean age, 21.9 years) with 72 teeth showing dehiscence/fenestrations and 17 sites presenting with gingival recessions. Clinical evaluations revealed a statistically significant reduction in swelling, pain, and clinical appearance from postoperative week 1 to week 2 (P < .05). Moreover, gingival recession sites exhibited a significant reduction in the GRD and an increase in CAL after surgery with mean root coverage of 69.8% at the end of observation period (P < .01). Both alveolar bone height and width increased after surgery (P < .01) and decreased during the 12-month follow-up (P < .01). However, compared with the baseline records, there was still a significant increase in alveolar bone volume (P < .01).This modified PAOO technique may have advantages in terms of soft and hard tissue augmentation, facilitating extensive bone augmentation and allowing the simultaneous correction of vertical and horizontal defects in the labial aspect of the mandibular anterior area.

Will unilateral temporomandibular joint anterior disc displacement in teenagers lead to asymmetry of condyle and mandible? A longitudinal study.

PURPOSE: To evaluate the change of morphological symmetry of the temporomandibular joints (TMJ) during natural course of unilateral juvenile anterior disc displacement (UJADD) by comparing the ipsilateral joint with the contralateral side; and to analyse its effect over mandibular asymmetry (MA). PATIENTS AND METHODS: This study is a self-control longitudinal study. Consecutive UJADD cases with no history of TMJ infection, injuries to the jaws, or congenital, developmental and systematic disorders that may affect the craniofacial growth were collected and followed for at least 6 months. Patients' age at both first visit and revisit was recorded. Pictures of magnetic resonance imaging (MRI) were selected to measure the differences between bilateral condylar height, disc length and condyle-disc distance, and comparison of the measurements before and after follow-up were made. Meanwhile, posteroanterior cephalometric radiographs (PA) were taken and deviation of menton from facial midline was measured before and after follow-up. Severity of MA was divided into 4 stages according to menton deviation: Non-MA (<2 mm), Minor-MA (≥2 mm, <4 mm), Medium-MA (≥4 mm, <6 mm), and Major-MA (≥6 mm). The constituent ratio of MA was evaluated and correlation between TMJ morphological change and asymmetry of the mandible was analysed. RESULTS: Forty four patients were included, with a mean follow-up of 12.22 months. The average age was 16.31 years old (range, 10-20 years) at first visit. Significant progression of disc displacement was found: condyle-disc distance increased, disc shortened and difference between bilateral condylar heights increased. Along with this, occurrence of MA increased from 86.36% to 93.18%, and average menton deviation increased from 5.58 mm to 7.74 mm after follow-up. The correlation coefficient (CC) of increase of condylar height difference and development of MA was 0.681 (p < 0.05). Also, increase of menton deviation was significantly related to age of the patients (CC = -0.760, p < 0.05). CONCLUSION: The results show that UJADD result in asymmetric growth bilateral TMJs, especially condylar height, which was much shorter on the ipsilateral side. In the same time, MA got worse during the natural course of UJADD. It is concluded that UJADD was one of the major causative factors of MA.

Is mandibular asymmetry more frequent and severe with unilateral disc displacement?

PURPOSE: To investigate the prevalence of mandibular asymmetry (MA) within the symptomatic unilateral anterior disc displacement (ADD) patients, and analyze the influence TMJ factors of the MA severity. METHODS: Patients aged under 20 years old with symptomatic unilateral ADD and asymptomatic volunteers with normal disc-condyle relationship diagnosed by magnetic resonance imaging (MRI) were included in this study. Posteroanterior cephalometric radiographs were taken to measure MA. Condylar height, disc length and disc displacement were measured by MRI. The prevalence and severity of MA were compared between the ADD and the control groups. The correlation between the severity of MA with the amount of condylar height shortage, disc deformity and distance of disc displacement were also evaluated within the ADD group. RESULTS: There were 165 cases in the unilateral ADD group, and 156 cases in the control group. One hundred and nineteen cases had MA which accounted 72.12% (119/165) in the ADD group; while in the control group, only 25.64% (40/156) exhibited MA. The mean horizontal menton deviation and condylar height shortage in the unilateral ADD group were significantly larger than that in the control group (5.62 mm vs. 4.19 mm; 3.14 mm vs. 1.32 mm, p < 0.01). The severity of MA was significantly correlated with the amount of disc displacement, disc deformity and condylar height shortage (correlation coefficient: 0.80, 0.70, and 0.82). CONCLUSION: MA is much more common and severe in young unilateral ADD patients. The severity of MA is correlated with the height of condyle and the status of the disc.

Efficacy of the technique of piezoelectric corticotomy for orthodontic traction of impacted mandibular third molars.

Our aim was to assess the efficacy of piezoelectric corticotomy for orthodontic traction of mandibular third molars close to the inferior alveolar nerve. Thirty patients with impacted third molars close to the nerve were included in the study, 15 of whom were treated with conventional orthodontic traction and 15 with piezoelectric corticotomy. We recorded duration of treatment including exposure and orthodontic traction, and time to the final extraction. Postoperative complications including trismus, swelling, and pain were also noted. Alveolar bone levels mesial and distal to the second molars were evaluated on cone-beam computed tomographic (CT) images. Student's t test was used to assess the significance of differences between the groups. After orthodontic treatments all impacted third molars were successfully removed from the inferior alveolar nerve without neurological damage. The mean (SD) duration of surgical exposure in the piezoelectric corticotomy group was significantly longer than that in the conventional group (p=0.01). The mean (SD) duration of traction was 4 (2.3) months after piezoelectric corticotomy, much shorter than the 7.5 (1.3) months in the conventional group (p=0.03). There were no significant differences in postoperative complications between the groups. There was a significant increase in the distal alveolar height of second molars after treatment in both groups (p<0.01). We conclude that the use of piezoelectric corticotomy allows more efficient and faster traction of third molars with a close relation between the root and the inferior alveolar nerve, although it took longer than the traditional technique.

Case studies on local orthodontic traction by minis-implants before implant rehabilitation.

OBJECTIVE: Dentition defect with malocclusion is a common occurrence in the clinical work. To restore proper occlusion, preprosthetic corrections of these malposed teeth are often indispensible. The use of orthodontic mini-implants as temporary anchorage devices provides a plausible treatment for those patients with local problems. The aim of this study was to present two cases using local orthodontic traction in conjunction with mini-implants to provide necessary conditions for implant rehabilitation in three dimensional space. Clinical consideration: Two cases who had dentition defect with malocclusion were included in the present study. As both of them rejected crown reduction or orthodontics treatment, local orthodontic traction by mini-implants was used to restore normal space for implant rehabilitation in three dimensions. Careful mechanics analysis and personalized mechanical device were under consideration. The results showed that the biological responses of the corrected teeth and the surrounding bony structures appeared normal and acceptable. Moreover the patients achieved an ideal local occlusion with a short treatment time. CONCLUSION: In conclusion local orthodontic traction by mini-implants was a less-invasive and short-term method with favorable effects and less necessary occlusal adjustments.

Three-D imaging of dental alveolar bone change after fixed orthodontic treatment in patients with periodontitis.

OBJECTIVES: The objective of this study was to radiographically quantify bone height and bone density in patients with periodontitis after fixed orthodontic treatment using cone beam computed tomography (CBCT). MATERIALS AND METHODS: A total of 81 patients including 40 patients with chronic periodontitis (group 1) and 41 patients with normal periodontal tissues (group 2) were selected. CBCT scanning for anterior teeth were taken before and after orthodontic treatment. Measurements of bone height and bone density were performed using CBCT software. RESULTS: The group 1 presented a statistically lesser bone density and bone height when compared to group 2 before treatment. There was a significant loss of bone density for both groups after orthodontic treatment, but bone density loss was significantly greater in the group 1. There was no statistically significant bone height change in two groups after treatment. CONCLUSIONS: This study demonstrated that orthodontic treatment can preserve bone height but not capable of maintaining bone density, especially for patients with periodontitis. It is indicated that the change of bone density may be more susceptible than that of bone height when radiographically evaluating bone status under this combined periodontal and orthodontic therapy.