微钛板支抗在远中移动磨牙中的临床应用

目的介绍微钛板支抗在远中移动磨牙中的临床效果及特点。方法选择7名应用微钛板矫治患者,分析其治疗前后头颅侧位片、模型等临床资料,测量磨牙远中移动量。结果 1)利用微钛板远中移动磨牙效果明显,最多可达3.5mm。2)中轻度牙列拥挤患者利用微钛板远中移动磨牙获得间隙排齐整平牙列,不需拔除双尖牙便可达到较理想的治疗效果。结论微钛板作为一种绝对支抗,远中移动磨牙有效而稳定,同时可避免常规拔牙矫治,维持上下颌第二磨牙间的全部牙齿和牙弓的连续性。     

Open-bite closure by intruding maxillary molars with skeletal anchorage

Most anterior open bite cases are characterized by the excessive vertical development of the posterior maxilla. Intrusion of the overerupted molar teeth with traditional orthodontic methods is hardly possible; therefore, there is no real alternative to a combined orthodontic and surgical approach. Skeletal anchorage has recently been offered for the orthodontic movement of teeth. Titanium miniplates implanted in the zygomatic buttress area can serve as absolute anchorage for maxillary molar intrusion. The aim of this study was to evaluate skeletal anchorage for closing open-bite malocclusions. Seven patients with severe anterior open-bites were selected. In all cases the deformity was due to the overeruption of the maxillary molars. Titanium miniplates were inserted bilaterally in the zygomatic buttress region. Fixation was performed with 3 miniscrews. Elastic bands or coil springs were used to reduce excessive maxillary molar heights. The mean active treatment time was 6 months. In all cases the anterior open-bite significantly improved. No side-effects were observed. Our results suggest that skeletal anchor plates offer successful treatment for closing skeletal anterior open bites.     

微螺钉直接支抗直立下颌第二磨牙的临床研究

目的 评价微螺钉直接支持的片段弓矫治器直立下颌第二磨牙的效果.方法 本研究包括18例种植修复前正畸患者,平均年龄32.8±5.7岁.样本人群总计有25颗下颌第二磨牙近中倾斜,需要正畸直立治疗.所有患者经牙周专科医师检查不存在活动期牙周病.18例患者在其下颌前磨牙区植入一颗微螺钉(1.6×9.0mm,慈北医疗器械有限公司),植入高度在膜龈结合部位或稍偏向方.愈合一周后,微螺钉头部连接由0.016×0.022英寸(1英寸=25.4 mm)的TMA丝制作的磨牙直立片段弓丝.下颌第二磨牙远中直立治疗前后分别拍摄头颅侧位定位片,并进行头影测量的分析比较.结果 18例患者的25颗近中倾斜的下颌第二磨牙均获得良好的正畸直立治疗效果,直立治疗的平均时间为4.0±1.0个月.相对于下颌平面,第二前磨牙的角度和高度均未发生变化.而第二磨牙角度平均增加16.5度(P＜0.001),第二磨牙和第二前磨牙距离平均增加4.4 mm(P＜0.001),均有显著性意义.第二磨牙远中颊尖高度未发生显著性变化.结论 应用微螺钉直接支抗支持的TMA丝片段弓矫治器可以有效地远中直立下颌倾斜磨牙,支抗稳定,第一磨牙间隙适度扩大.     

Distal movement of maxillary molars using a lever-arm and mini-implant system

Recently, many studies have been reported on distal molar movement using temporary anchorage devices. However, the side effects of distal movement, such as distal tipping, rotation, or extrusion, are still unsolved. This article describes the use of the lever-arm and mini-implant system for controlled distal movement of maxillary molars and two clinical cases in which patients were treated with this system. Mini implants are needed to control the point of force application in the posterior area with no anchorage loss. When the length of the lever arm and the position of the mini implant are adjusted, the desired line of action of the distal force is determined with respect to the center of resistance of maxillary molars. The lever-arm and mini-implant system is useful not only for absolute anchorage, but also for three-dimensional control during distal movement of the upper molars.     

Treatment and posttreatment dentoalveolar changes following intrusion of mandibular molars with application of a skeletal anchorage system (SAS) for open bite correction

The skeletal anchorage system (SAS) consists of titanium anchor plates and monocortical screws that are temporarily implanted in either the maxilla or the mandible as absolute orthodontic anchorage. With SAS, anterior open bite can be improved by the counterclockwise rotation of the mandible, accompanied by the intrusion of molars. The present study was designed to evaluate treatment and posttreatment dentoalveolar changes following the intrusion of mandibular molars. Nine adult open bite patients (7 women and 2 men) successfully treated with SAS were included in the following study. The amount of intrusion, relapse, and dentoalveolar changes were measured on cephalometric radiographs, panoramic radiographs, and dental casts. The results of this study were as follows: (1) the average amount of intrusion of the mandibular first and second molars was 1.7 mm and 2.8 mm, respectively; (2) the average relapse rates were 27.2% at the first molars and 30.3% at the second molars; (3) there were no significant changes in crestal bone heights, clinical crown length, or root length; and (4) counterclockwise rotation of the mandible and decrease of anterior facial height were observed during treatment. Thus, it was concluded that SAS would be a valid modality to intrude mandibular molars for correction of open bite.     

微小种植体支抗远移上颌磨牙的临床应用

目的:观察微小种植体作为强支抗远移上颌磨牙的作用及效果.方法:选取安氏Ⅱ类错(牙合)患者16 例,在上颌颊侧牙槽骨内共植入微小种植体22 颗,利用微小种植体做为支抗推磨牙向远中.拍摄磨牙移动前后的X线头影测量片,记录上颌磨牙及切牙移动情况,并进行统计分析.结果:利用微小种植体远移磨牙4～8 月后,所有病例磨牙达到中性关系.磨牙平均移动4.71 mm(P<0.01),上颌中切牙平均舌向移动2.16 mm(P<0.05);磨牙伸长、颊移、远中倾斜及上切牙伸长无统计学意义.结论:微小种植体可作为绝对强支抗,有效地整体远移上颌磨牙,特别适用于安氏Ⅱ类成人错(牙合)的矫治.     

Intrusion of overerupted molars by corticotomy and orthodontic skeletal anchorage

This article describes the orthodontic treatment of a 26-year-old female patient with overerupted left maxillary molar teeth. Her chief complaint was that the maxillary left first and the second molar intruded into the space required for the mandibular left first and the second molars, preventing prosthodontic treatment. The authors performed a corticotomy and used orthodontic skeletal anchorage with a miniplate and orthodontic miniscrews with a head modified to provide a specially designed hook. With this approach, they were able to achieve a sufficient amount of molar intrusion without discomfort, root resorption, or extrusion of the adjacent teeth. The first molar was intruded 3.0 mm and second molar was intruded 3.5 mm during 2 months of treatment. These results have been maintained for 11 months.     

Remaining mandibular third molars in an adult population

summary Although tooth loss with age has been extensively investigated, there appears to be no literature on the relationship of age to remaining mandibular third molars. The study showed that as age increases so does the frequency of absent vertically erupted mandibular third molars. However, no correlation was found between age and loss of mandibular impacted third molars in men of 71 years of age or older. The evidence presented here suggests that impacted mandibular third molars, which have not been infected, may be more likely to remain compared with other teeth at potential risk.     

Mesial bodily movement of maxillary and mandibular molars with segmented mechanics

The displacement of teeth into areas with substantial atrophy of the alveolar ridge or through the maxillary sinus has been considered a major limitation. Bone formation can, however, be generated if the orthodontic appliance can produce the necessary strain distribution along the entire periodontal ligament. The aim of this case report is to illustrate how bone formation can accompany mesial bodily movement of maxillary and mandibular molars. The necessary strain distribution was generated by the rational use of segmented mechanics. The use of superelastic Ni-Ti springs allows the application of low and constant forces over a wide range of deactivation, thus providing a uniform strain in the periodontium. The result of those appliances is highly predictable and side effects can be minimized effectively.     

Apical root resorption of maxillary first molars after intrusion with zygomatic skeletal anchorage

The aim of this study was to evaluate radiographically the apical root resorption of maxillary first molars after their intrusion was done using zygomatic miniplates as skeletal anchorage in open-bite cases. The study group comprised 16 consecutively treated open-bite cases who had received special titanium miniplates in their zygomatic bones for use as anchorage to apply orthodontic intrusive forces to the maxillary posterior region. The control group consisted of 16 patients, who were matched regarding age, sex, and treatment duration but who had undergone fixed orthodontic treatment without intrusion mechanics for molars. Tooth lengths were measured on pretreatment, and posttreatment panoramic radiographs of all patients and mesiobuccal and distobuccal roots of left and right maxillary first molars were measured on-screen using a software program. The difference between the pre- and posttreatment tooth lengths was defined as apical root resorption. Comparison of the differences in root resorption of the two groups using the t-test for independent samples showed a statistically significant difference (P = .004) only for mesial roots on the right side. But because the mean difference in apical root resorption was only 0.5 mm, it was concluded that the apical root resorption of maxillary first molars after intrusion was done using zygomatic skeletal anchorage was not clinically significant.     

应用鞋拔曲近中移动下颌第二磨牙的临床研究

目的探讨应用鞋拔曲近中移动下颌第二磨牙的临床效果。方法选择22例下颌第一磨牙严蘑龋坏的错硷畸形患者,随机平均分为2组．均拔除2颗下颌第一磨牙,均采用MBT直丝弓矫治器矫治,排齐整平牙弓后,试验组11例患者采用鞋拔曲近中移动下颌第二磨牙,对照组11例患者采用不锈钢平直方弓丝近中移动下颌第二磨牙,对两组下颌第二磨牙近中移动前后的X线头颅侧位片和研究模型进行测量和统计学分析。结果2组的I.7-MP角、L7轴角和L7支抗强度在下颌第二磨牙近中移动的差值差异有统计学意义（P〈0．05）;其他测量项目差异均无统计学意义（P〉0．05）。结论应用鞋拔曲近中移动下颌第二磨牙临床效果良好,有一定的临床实用价值。     

Nonsurgical treatment of adult skeletal Class III malocclusion with crowding and missing four premolars corrected with extraction of mandibular first molars

An adult male patient was present with anterior cross bite. He was referred to Orthodontic Clinic of Niigata University Medical and Dental Hospital for recommendation of surgical orthodontic treatment by general practitioner. The patient was diagnosed as skeletal Class III with anterior crowding and missing four premolars. To correct anterior cross bite and crowding, surgical orthodontic treatment was considered, but the patient refused orthognathic surgery. We therefore determined that nonsurgical treatment with mandibular bilateral first molar extraction would be indicated.After treatment, suitable overjet, overbite and proper functional occlusion were attained with Class I molar relation. Active treatment was 34 months, and the treatment result remained stable 2 years and 4 months after debonding.     

Bodily distalization of molars with absolute anchorage

Palatal implants have been used over the last two decades to eliminate headgear wear and to establish stationary anchorage. In this case report, the stability of a palatal implant for distalization of molars bodily and for anchorage maintenance was assessed. The implant was a stepped screw titanium (4.5 mm diameter x 8 mm length), and it was placed in the palatal region for orthodontic purposes. A surgical template containing a metal drill housing was prepared. Angulation of the drill housing was controlled according to the radiologic tracing of the maxilla transferred to a plaster cast section in the paramedian plane. The implant was placed using a noninvasive technique (incision, flap, and suture elimination) and left transmucosally to facilitate the surgical procedure and to reduce the number of operations. The paramedian region was selected (1) to avoid the connective tissues of the palatine suture and (2) because it is considered to be a suitable host site for implant placement. After three months of healing, the implant was osseointegrated and orthodontic treatment was initiated. For molar distalization, the Keles Slider appliance was modified and, instead of a Nance button, a palatal implant was used for anchorage. The results showed that the molars were distalized bodily at five months, and no anchorage loss was observed. At the end of the treatment, the smile was improved, and an ideal Class I molar and canine relationship, an ideal overbite, and an ideal overjet were all achieved. In conclusion, palatal implants can be used effectively for anchorage maintenance and in space-gaining procedures. Use of a three-dimensional surgical template eliminated implant placement errors, reduced chair time, minimized trauma to the tissues, and enhanced osseointegration. This method can be used effectively to achieve distalization of molars bodily without anchorage loss.