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??Objective??To evaluate the effect of articular disc repositioning combined with orthodontic functional appliance in the treatment of juvenile bilateral temporomandibular joint ??TMJ??anterior disc displacement??ADD?? and  skeletal class ??malocclusion. Methods??Fourteen juvenile patients with bilateral TMJ ADD and skeletal class ?? malocclusion were selected from March 2016 to March 2018 in the Department of Oral Surgery??Ninth People’s Hospital??Shanghai Jiao Tong University School of Medicine. Magnetic resonance imaging ??MRI?? and cephalometric radiographs before surgery and  follow-ups were performed for all patients. Condylar height and relevant cephalometric radiographs were measured and compared by statistical analysis. Results??Compared with pre-surgery??MRI showed the condylar height increased ??1.74±0.98??mm during follow-ups after surgery ??P??0.001??. New generated bone was observed on all condyles. About 84.61% of the new bone formed at superior and posterior-anterior surface. Cephalometric radiographs showed that SNB increased ??1.83±1.56??°??P??0.001????pogonion position ??pog-G?? moved ??2.18±3.13??mm ??P = 0.028?? forward and incisor overjet decreased ??3.55 ± 1.86??mm ??P??0.001????whereas no significant changes were found in SNA??Sn - G Vert??Y-Axis??U1 - SN??IMPA ??L1-MP?? or U1-L1 ??P > 0.05??. Conclusion??Articular disc repositioning combined with postoperative orthodontic functional appliances can effectively promote condylar growth and reduce oral-maxillofacial deformities in juvenile patients with bilateral  TMJ ADD and skeletal class??malocclusion.     

Root proximity of miniscrews at a variety of maxillary and mandibular buccal sites: Reliability of panoramic radiography

Objectives:To assess the root proximity and the insertion angles of miniscrews after miniscrew placement at a variety of maxillary and mandibular buccal sites using cone-beam computed tomography (CBCT) and to determine the differences in root proximity between CBCT and panoramic radiography (PR).Materials and Methods:This retrospective study included 50 patients (mean age, 22.0 ± 4.5 years) who underwent postoperative CBCT and PR after miniscrew placements for intermaxillary fixation in orthognathic surgery. Twelve miniscrews were placed in the buccal bone of each patient: at sites between the central incisor and lateral incisor (SII), sites between the canine and first premolar (SCP), and sites between the second premolar and first molar (SPM) on the right and left sides of the mandible and maxilla. The insertion angles were measured on CBCT, and the root proximity was assessed on CBCT and PR.Results:The mean vertical placement angles ranged from 84.27° to 95.12°, and the mean horizontal placement angles ranged from 90.93° to 101.1°. The rates of no contact between the root and the miniscrew were 68.0% in the SII, 50.5% in the SCP, and 57.8% in the SPM, which were significantly different (P = .000). The total concordance rate between PR and CBCT was 41.3%.Conclusions:Clinicians should use extreme caution during placement of miniscrews in the SCP. There are limitations on the use of PR for evaluating the root proximity of miniscrews.     

Temporary replacement of missing maxillary lateral incisors with orthodontic miniscrew implants in growing patients: rationale,clinical technique,and long-term results

Abstract

The missing maxillary lateral incisor in adolescent patients presents an orthodontic challenge. Historically, there have been three treatment options to address this clinical problem: (1) canine substitution, (2) tooth auto-transplantation, and (3) dental restoration. Unfortunately, these methods are not without limitation. A novel treatment concept, originating in 2003 and utilizing orthodontic miniscrew implants, is presented along with the rationale, clinical technique and 8 years of follow-up.     

正畸治疗中磨牙的拔除和保留(九)——微型自攻种植钉支抗的初步应用

目的：探讨种植体支抗在涉及磨牙拔除和保留的正畸病例中的应用效果。方法：在7例涉及磨牙拔除和保留病例中应用微型自攻种植钉以增强后牙或前牙的支抗。结果：7例矫治病例所应用的种植体均显示明显的支抗效果。结论：微型自攻种植钉在矫治严重和复杂的错殆畸形病例中是有效增强支抗的手段。     

Histomorphometric Evaluation of Cortical Bone Thickness Surrounding Miniscrew for Orthodontic Anchorage

Background: Recently, the use of miniscrews as an anchorage device has become a routine approach in the orthodontic field. However, there is no report that has analyzed the healing process of the miniscrew, such as the thickness of the cortical bone, in the past. Purpose: In the present study, to histologically assess the healing process of the osseous tissue surrounding miniscrews used as an orthodontic anchorage, the change in the thickness of the cortical bone was analyzed after 3, 6, and 12 weeks after the placement. Furthermore, the change in the bone‐implant contact in different regions of the miniscrew during the initial healing period was also investigated. Materials and Methods: Ninety‐six miniscrews were placed in eight beagle dogs. After 3, 6, and 12 weeks of healing, a force of 200–300 g was applied to the force‐applied groups for 12 weeks. Non‐forced groups remained in the jaw without force application. Results: In the non‐forced groups, a significant amount of cortical bone was formed at the head of the miniscrew at the initial stage of the healing process in the maxilla. However, less cortical bone formation was observed in the mandible. After the force application, increased bone formation was observed within 1 mm of the miniscrew compared to other regions in both jaws. In the mandible, significantly less cortical bone was observed 3 and 6 weeks after the force application. Bone‐implant contact revealed that the osseous tissue surrounding the miniscrew matured from the apex toward the head of the miniscrew. Conclusion: We suggest that this sufficient amount of cortical bone at the initial stage of healing enables the immediate loading in miniscrews to resist against orthodontic force. Furthermore, less amount of cortical bone formed at the head of the miniscrew may be one reason for the higher failure rate in the mandible.     

Measurement of cortical bone thickness in adults by cone-beam computerized tomography for orthodontic miniscrews placement

The purpose of this study was to investigate the cortical bone thickness of the inter-dental area of both jaws for orthodontic miniscrew placement. The cone-beam computerized tomography images of 32 non-orthodontic adults with normal occlusion were taken to measure the cortical bone thickness in both jaws. One-way analysis of variance (ANOVA) was used to analyze the differences in cortical bone thickness. Buccal cortical bone in the mandible was thicker than that in the maxilla. In the maxilla, cortical bone thickness was thicker in the buccal side than in the palatal side. Buccal cortical bone thickness in the mandible was thickest at the site distal to the first molar, and in the maxilla it was thickest at the site mesial to the first molar, while in the palatal side of maxilla it was thickest at the site mesial to the second premolar. The changing pattern of cortical bone thickness varies at different sites. In the buccal side of maxilla, the thinnest cortical bone thickness was found to be at 4 mm level from the alveolar crest, while the thickest was at 10 mm level (except for the site mesial to the first premolar). The buccal cortical bone thickness at the sites mesial or distal to the first molar in the mandible and palatal cortical bone thickness of maxilla tended to increase with increasing distance from the alveolar bone.     

The effect of disc repositioning and post-operative functional splint for the treatment of anterior disc displacement in juvenile patients with Class II malocclusion

Purpose

To evaluate the effect of temporomandibular joint (TMJ) disc repositioning and post-operative functional splint for the treatment of anterior disc displacement (ADD) in juvenile patients with Class II malocclusion.

New and Recovered Temporary Anchorage Devices,In Vitro Assessment of Structural and Surface Properties

The orthodontic miniscrew (TADs) is a device that is fixed into bone in the short term for the purpose of enhancing orthodontic anchorage. The aim of our study was to investigate the structural and surface properties of recovered TADs after orthodontic treatment, and compare them to new TADs. TADs (n = 15) from the same manufacturer (Absoanchor; Dentos, Daegu, Korea) were assessed; n = 10 were recovered from patients after orthodontic treatment and n = 5 were new. We performed electrochemical investigations, scanning electron microscopy (SEM) and microbiological analysis. Qualitative analysis on general electrochemical polarization revealed that the TADs retrieved from the patients provided much lower current densities in the passivity zone, and the oxidative processes taking place on their surface were of lower intensity. The surface morphologies of the tips of the retrieved mini-implants showed less sharp tips and smooth surfaces. Defects in the form of pores or cracks could be identified in both evaluated TAD groups. All retrieved TADs showed signs of biological materials (SEM analysis) and contamination on their surfaces. In conclusion, these results can assist orthodontists in comprehending the complexities of TAD behavior with respect to their design and structure.     

微型种植钉增强正畸支抗的临床稳定性研究及相关危险因素分析

目的：探讨将微型种植钉作为增强支抗措施的临床稳定性,分析影响微型种植钉成功率的危险因素。方法：选择错骀患者48例（男性18例,女性30例,平均年龄23．2±6．5岁）,植入微型种植钉的总数量为152枚,微型种植钉的负载期为10个月,评价11个临床变量与微型种植钉成功率的关系。结果：微型种植钉的总成功率为90．1％,口腔卫生状况、微型种植钉植入部位的牙周组织肿胀、牙周炎史、下颌平面角的高低等与微型种植钉的稳定性密切相关;而宿主因素（年龄、性别）、微型种植钉因素（长度）、微型种植钉植入的设计因素（上下颌骨植入部位、植入微型种植钉的角度、是否即刻负载、微型种植钉的加力方式）等对微型种植钉成功率的影响无显著性差异。结论：针对使用微型种植钉的患者,维持好的口腔卫生、对下颌平面角较高的患者采取谨慎设计、防止微型种植钉周围组织肿胀,对于提高微型种植钉植入的成功率是非常重要的。     

正畸微种植体精确植入的初步临床研究

目的 在三维牙颌数据基础上,设计制作引导模板,实现正畸微种植体的准确植入.方法 对30例需要植入微种植体的正畸患者进行CT扫描和三维数据重建,在三维数据基础上设计种植体支抗的位置和引导隧道,并采用牙冠唇、腭面数据设计定位的翼板:数据采用快速成型技术,制作成实体树脂模板,并引导微种植体的植入,每位患者随机挑选一侧上颌,采...