Maxillary molar distalization with a bone-anchored pendulum appliance

To obtain an effective and compliance-free molar distalization without an anchorage loss, we designed the bone-anchored pendulum appliance (BAPA). The aim of this study was to evaluate the stability of the anchoring screw, distalization of the maxillary molars, and the movement of teeth anterior to maxillary first molars. The study group comprised 10 patients (mean age 13.5 +/- 1.8 years) with Class II molar relationship. A conventional pendulum appliance was modified to obtain anchorage from an intraosseous screw instead of the premolars. The screw was placed in the anterior paramedian region of the median palatal suture. Skeletal and dental changes were measured on cephalograms, and dental casts were obtained before and after distalization. A super Class I molar relationship was achieved in a mean period of 7.0 +/- 1.8 months. The maxillary first molars distalized an average of 6.4 +/- 1.3 mm in the region of the dental crown by tipping distally an average of 10.9 degrees +/- 2.8 degrees . Also, the maxillary second premolar and first premolar moved distally an average of 5.4 +/- 1.3 mm and 3.8 +/- 1.1 mm, respectively. The premolars tipped significantly distally. No anterior incisor movement was detected. The BAPA was found to be an effective, minimally invasive, and compliance-free intraoral distalization appliance for achieving both molar and premolar distalization without any anchorage loss.     

Dentoalveolar and skeletal changes associated with the pendulum appliance.

The purpose of the study was to examine the dentoalveolar and skeletal effects of the pendulum appliance in Class II patients at varying stages of dental development and with varying facial patterns (high, neutral, and low mandibular plane angles). Specifically, the amount and nature of the "distalization" of the maxillary first molars and the reciprocal effects on the anchoring maxillary first premolars and incisors were studied, as were skeletal changes in the sagittal and vertical dimensions of the face. Pretreatment and posttreatment cephalometric radiographs obtained from 13 practitioners were used to document the treatment of 101 patients (45 boys and 56 girls). The average maxillary first molar distalization was 5.7 mm, with a distal tipping of 10.6 degrees. The anchoring anterior teeth moved mesially, as indicated by the 1.8-mm anterior movement of the upper first premolars, with a mesial tipping of 1.5 degrees. The maxillary first molars intruded 0.7 mm, and the first premolars extruded 1.0 mm. Lower anterior facial height increased 2.2 mm; there was no significant difference in lower anterior facial height increase between patients of high, neutral, or low mandibular plane angles. In patients with erupted maxillary second molars, there was a slightly greater increase in lower anterior face height and in the mandibular plane angle and a slightly greater decrease in overbite in comparison to patients with unerupted second molars. Similar findings were observed in patients with second premolar anchorage versus those with second deciduous molar anchorage. The results of this study suggest that the pendulum appliance is effective in moving maxillary molars posteriorly during orthodontic treatment. For maximum maxillary first molar distalization with minimal increase in lower anterior facial height, this appliance is used most effectively in patients with deciduous maxillary second molars for anchorage and unerupted permanent maxillary second molars, although significant bite opening was not a concern in any patient in this study.     

Combined Therapy with Pendulum and Lingual Arch Appliances in the Early Mixed Dentition

PATIENTS AND METHOD: In 20 patients with arch length deficiency and anterior crowding, pendulum and lingual arch appliances were inserted simultaneously in the upper and in the lower arch respectively to gain space. The patients were divided into two groups according to their dental eruption stage: ten children (six boys, four girls; mean age: 9 years, 6 months) were in the early mixed dentition, while an adolescent comparison group of the same size (three boys, seven girls; mean age: 12 years, 3 months) were in the permanent dentition at the beginning of treatment. AIM: The main purpose of the study was to investigate whether simultaneous therapy with pendulum and lingual arch appliances is to be recommended, i.e. whether this therapy should take place as interceptive treatment in the early mixed dentition or only in the permanent dentition in adolescence. Parameters were the extent and quality of dentoalveolar effects and the side effects (mesial movement of the incisors, protrusion of the incisors, tipping of molars). RESULTS: The treatment course was documented by means of study casts and lateral cephalograms. Assessment of the diagnostic records yielded the following findings: In the early treatment group the maxillary molars were distalized by the pendulum appliance by a mean distance of 4.0 +/- 1.46 mm, resulting in distal tipping by 6.1 +/- 2.18 degrees. The incisors were moved reciprocally by 1.08 +/- 1.06 mm to anterior and protruded by 7.65 +/- 4.84 degrees. In the comparison group molar distalization and molar tipping were less pronounced (2.86 +/- 1.54 mm/4.25 +/- 3.78 degrees ), while mesial movement of the incisors was comparably high at 1.62 +/- 0.99 mm. At only 3.8 +/- 2.9 degrees, incisor protrusion was significantly less pronounced than in the early treatment group (p = 0.045). The proportion of molar distalization in the total movement was higher in patients in the early mixed dentition: 79.83 +/- 15.38% vs 60.71 +/- 26.64%. During the early therapy with the lingual arch appliance in the lower arch, the molars were uprighted to the distal by 2.4 +/- 0.97 degrees and the incisors were tipped to labial by 5.0 +/- 1.83 degrees. In the adolescent control group, molar uprighting was less pronounced and the degree of incisor protrusion was significantly lower (2.75 +/- 1.11 degrees, p = 0.004). CONCLUSION: With the appropriate indication, the combined therapy with the two compliance-independent appliances described can be recommended for gaining sagittal arch length in the early mixed dentition.     

Various Anchorage Approaches in Unilateral Mandibular Molar Distalization Using a Fixed Lingual Arch Appliance

PATIENTS AND METHOD: Mean unilateral mandibular molar distalization of 3.33 +/- 1.28 mm was achieved in 20 patients (average age: 13 years, 1 month) by fitting an asymmetrically activated lingual arch appliance for an average treatment period of 4 months. Three different anchorage techniques were used: Anchorage was provided in seven patients by the lingual arm of the appliance alone, while another seven patients received additional sectional archwires, and another six patients sectional archwires and lip bumpers. RESULTS AND DISCUSSION: Anchorage by means of the lingual arm alone proved to be insufficient to prevent labial tipping of the incisors. The mean protrusion and labial tipping recorded at the lower incisors was 7.67 degrees +/- 1.53 degrees and 2.64 +/- 0.48 mm respectively. The anchorage quality was enhanced and satisfactory stabilization achieved by additionally inserting a sectional archwire. In these cases the mean incisor protrusion and labial tipping was 1.75 degrees +/- 0.96 degree and 0.71 +/- 0.76 mm respectively and thus significantly lower (p < 0.01). The additional fitting of a lip bumper provided no further increase in anchorage quality (incisor protrusion 1.75 degrees +/- 2.87 degrees and 0.67 +/- 1.21 mm respectively). CONCLUSION: Fitting additional anchorage aids appears to have no direct impact on the extent and quality of molar distalization.     

Pendulum and modified pendulum appliances for maxillary molar distalization in Class II malocclusion – a systematic review

Objective: The main purpose of the present systematic review was to evaluate the quantitative effects of the pendulum appliance and modified pendulum appliances for maxillary molar distalization in Class II malocclusion.

Materials and methods: Our systematic search included MEDLINE, EMBASE, CINAHL, PsychINFO, Scopus and key journals and review articles; the date of the last search was 30 January 2017. We graded the methodological quality of the studies by means of the Quality Assessment Tool for Quantitative Studies, developed for the Effective Public Health Practice Project (EPHPP).

Results: In total, 203 studies were identified for screening, and 25 studies were eligible. The quality assessment rated four (16%) of the study as being of strong quality and 21 (84%) of these studies as being of moderate quality. The pendulum appliances showed mean molar distalization of 2–6.4?mm, distal tipping of molars from 6.67° to 14.50° and anchorage loss with mean premolar and incisor mesial movement of 1.63–3.6?mm and 0.9–6.5?mm, respectively. The bone anchored pendulum appliances (BAPAs) showed mean molar distalization of 4.8–6.4?mm, distal tipping of molars from 9° to 11.3° and mean premolar distalization of 2.7–5.4?mm.

Conclusions: Pendulum and modified pendulum appliances are effective in molar distalization. Pendulum appliance with K-loop modification, implant supported pendulum appliance and BAPA significantly reduced anchorage loss of the anterior teeth and distal tipping of the molar teeth.     

Efficiency of a pendulum appliance for molar distalization related to second and third molar eruption stage.

A modified pendulum appliance, including a distal screw and special preactivated pendulum springs (built-in straightening activation and toe-in bending), was used for bilateral maxillary molar distalization in 36 adolescent patients in various stages of the molar dentition. The patients were divided into 3 groups (PG 1-3) according to the stage of eruption of their second and third molars. In PG 1 (18 patients), eruption of the second molars had either not yet taken place or was not complete. In PG 2 (15 patients), the second molars had already developed as far as the occlusal plane, with the third molars at the budding stage. In PG 3 (3 patients), germectomy of the wisdom teeth had been carried out, and the first and second molars on both sides had completely erupted. Analysis of cephalograms to identify any changes in the sagittal plane showed that, in the direction of distalization, a tooth bud acts on the mesial neighboring tooth like a fulcrum, and that tipping of the first molars in patients in whom the second molar was still at the budding stage was thus greater. In patients whose second molars had erupted completely, the degree of tipping was greater again when a third molar bud was located in the direction of movement. After previously completed germectomy of the wisdom teeth, almost exclusively bodily distalization of both molars is possible, even without bands being applied to the second molars. However, if the first and second molars are distalized simultaneously with a pendulum appliance, the duration of therapy will be longer, greater forces will have to be applied, and more anchorage will be lost. Statistical analysis of the results of dental-angular measurements showed significant differences in the degree of molar tipping and reciprocal incisor protrusion. The degree of distal tipping of first molars was less in patients with erupted second molars (PG 2 and PG 3) than in those whose second molars were not yet erupted (PG 1). For instance, the measured angles were 0.9 degrees +/- 3.43 degrees (to the palatal plane) and 0.8 degrees +/- 3.4 degrees (to the anterior cranium floor) in PG 2, and -0.33 degrees +/- 0.58 degrees and 0.67 degrees +/- 2.08 degrees, respectively, in PG 3, contrasting with respective values of 5.89 degrees +/- 3.74 degrees and 5.36 degrees +/- 3.49 degrees in PG 1. Tipping of erupted second molars was much more marked in PG 2 (7.92 degrees +/- 5.83 degrees to the palatal plane and 7.55 degrees +/- 5.28 degrees to the anterior cranium floor), but much less pronounced in PG 3 (2 degrees +/- 1.73 degrees to the palatal plane and 2 degrees +/- 2 degrees to the anterior cranium floor) than the corresponding movement of the second budding-stage molars in PG 1 (4.06 degrees +/- 2.15 degrees and 3.97 degrees +/- 2.27 degrees, respectively). The degree of incisor protrusion occurring reciprocally with molar distalization was much less in these patients (measured angles of 3.28 degrees +/- 1.97 degrees and 2.89 degrees +/- 2.17 degrees to the palatal plane and anterior cranium floor, respectively) than in the patients presenting different stages of the dentition (angles of 5.5 degrees +/- 3.33 degrees and 6.03 degrees +/- 4.29 degrees, respectively, in PG 2, and angles of 5.5 degrees +/- 3.28 degrees and 6.67 degrees +/- 3.09 degrees, respectively, in PG 3). Moreover, measurement of dental casts in the horizontal plane showed not only the targeted mesiobuccal rotation of both maxillary molars, but also a vestibular drift of the unbanded second molars.     

钟摆矫治器联合颊侧推簧远移磨牙的疗效分析

目的：评价钟摆矫治器联合颊侧推簧远移磨牙的疗效.方法：选择40例牙性安氏Ⅱ类错（牙合）畸形的患者,随机均分为两组：钟摆矫治器联合颊侧推簧远移磨牙组（组1）和头帽口外弓远移磨牙组（组2）,在治疗开始前（T0）和远移磨牙完成时（T1）分别拍摄侧位头影定位片进行头影测量,t检验分析组内和组间的差异.结果：组1和组2远移磨牙的平均距离分别是（4.48±1.63） mm、（2.68±1.71） mm;组1和组2磨牙远中倾斜的平均角度分别是5.46°±3.23°、1.02°±2.16°;组1上颌中切牙未发生明显的唇倾和唇向移位,而组2上颌中切牙发生了较为明显的腭侧移位.结论：钟摆矫治器联合颊侧推簧远移磨牙可有效防止前牙支抗的丧失、控制磨牙的近中颊侧旋转.     

Maxillary unilateral molar distalization with sliding mechanics: a preliminary investigation.

Fifteen patients, eight males and seven females with a mean age of 13.32 years, were selected for unilateral molar distalization. Dentally, all presented with a unilateral Class II molar relationship. The subjects were all in the permanent dentition with second molars erupted and with a well aligned lower dental arch. For maxillary molar distalization a new intra-oral appliance was developed, the Keles Slider, which comprised two premolar and two molar bands. The anchorage unit was a Nance button with an anterior bite plane. From the palatal side, the point of distal force application was carried towards the level of centre of resistance of the maxillary first molar. A Ni-Ti coil spring was used and 200 g distal force was applied to the Class II first molar. Lateral cephalograms were taken and analysed before and 2 months after molar distalization. The Class II molars were distalized bodily, on average, 4.9 mm (P < 0.001). Mesial migration of the Class II first premolars was 1.3 mm (P < 0.05), incisor protrusion was 1.8 mm (P < 0.05) and incisor proclination 3.2 degrees (P < 0.05). The overbite was reduced by 3.1 mm (P < 0.001) and the overjet increased 2.1 mm (P < 0.01). For stabilization, the corrected Class II unilateral molar relationship was maintained with a Nance button for 2 months. The results show that this newly developed device achieved bodily distal molar movement with minimum anchorage loss.     

Treatment effects of intraoral appliances with conventional anchorage designs for non-compliance maxillary molar distalization: a literature review

Since the end of the 1970s, various appliances with intramaxillary anchorage for distalization of the upper molars have been described as an alternative to headgear. The major advantages of these innovative appliances are that they act permanently and are independent of patient compliance. The purpose of this study was to compare the efficiency, both quantitatively and qualitatively, of various appliance types with intramaxillary anchorage for non-compliance molar distalization. Eighty-five papers were reviewed, and 22 were identified as being suitable for inclusion. The selection was based on compliance with the following criteria: treatment group with at least 10 non-syndromal patients, conventional intraoral anchorage design using a palatal button and anchorage teeth, consistent cephalometric measurements in clinical-epidemiological studies, exact data on the course of treatment, and statistical presentation of the measured outcomes and their standard deviations. The results show that non-compliance molar distalization is possible with numerous different appliances. While molar distalization with standard pendulum appliances exhibited the largest values for dental-linear distalization, it also resulted in concurrent, substantial therapeutically undesirable distal tipping. However, specific modifications to the pendulum appliance allow achievement of almost bodily molar distalization. Different outcomes are quoted in the studies for the efficiency of loaded spring systems for distal molar movement, but it seems that the first class appliance and the palatal distal jet are more efficient than the vestibular Jones Jig. The studies identify anchorage loss as being found in the area of the incisors rather than the area of the first premolars. There was a trend for more substantial reciprocal side-effects to occur when only two teeth were included in the anchorage unit. Vertical components acting on the molars, premolars, and incisors, such as intrusion and extrusion, tended to be of secondary importance and, therefore, may be disregarded.     

上颌第二磨牙萌出对“摆”式矫治器远中移动上颌磨牙疗效的影响

目的研究上颌第二磨牙不同萌出阶段对”摆”式矫治器远中移动上颌磨牙疗效的影响。方法选择上颌牙列轻中度拥挤，磨牙远中关系的病例25例。根据上颌第二磨牙萌出情况分为未萌组（15例）和萌出组（10例）。采用“摆”式矫治器远中移动上颌磨牙。以X线头影测量分析为测定手段。结果①两组的磨牙远中移动距离无显著差异。②未萌组的上颌第一磨牙远中倾斜要大于萌出组，但未萌组的上颌第二磨牙远中倾斜要小于萌出组。③萌出组的上颌第一磨牙相对伸长较多。④上颌中切牙唇向倾斜移动量和前牙覆盖增加量在萌出组较大。结论①萌出的上颌第二磨牙对上颌磨牙远中移动无明显影响。②上颌第二磨牙萌出与否对磨牙远中倾斜有较大影响。③萌出的上颌第二磨牙造成较多支抗丧失。④上颌第二磨牙萌出者在治疗后其上颌第一磨牙伸长较多。     

A comparative analysis of distal maxillary molar movement produced by a new lingual intra-arch Ni-Ti coil appliance and a magnetic appliance

The aim of the study was to evaluate cephalometrically the dental and skeletal treatment effects of a new lingual intra-arch Ni-Ti coil appliance for molar distalization and to compare these with those of an established intra-arch appliance that uses repelling magnets for distal molar movement. Two groups of 21 adolescents, all girls, participated in this retrospective study. One group was treated with the new lingual Ni-Ti coil appliance for 6.5 months and the other with the magnetic appliance for 5.8 months. The treatment effects were analysed by measurements on lateral head radiographs at the start of treatment and after the molar distalization was completed. The mean amount of distal molar movement was 2.5 mm (SD 0.69) in the lingual coil group and 2.6 mm (SD 0.51) in the magnet group. A significantly higher degree of distal molar tipping was found in the magnet group, -8.8 degrees, compared with -2.2 degrees for the lingual coil group. Due to anchorage loss, the maxillary incisors moved forwards, and the overjet was increased by an average of 1.2 mm in the lingual coil group and 1.7 mm in the magnet group. The results indicate that the new lingual Ni-Ti coil appliance was better choice than the magnet appliance for distal bodily movement of maxillary molars. The benefits of the new Ni-Ti appliance were due to the design preventing molar tipping and its single activation.     

Effects of a three-dimensional bimetric maxillary distalizing arch

This study aimed to investigate the dental effects of a three-dimensional (3D) bimetric maxillary distalizing arch. The Wilson rapid molar distalization appliance for Class II molar correction was used in 14 patients (10 girls and four boys with a mean age of 12.18 years). The open coil springs were activated with bent Omega stops and Class II intermaxillary elastics. The mandibular anchorage was gained by a 0.016 x 0.016 utility arch with a 3D lingual arch or a lip bumper with a standard lingual arch. The lateral cephalograms taken before and after treatment formed the material of the research. A Wilcoxon test was used to statistically evaluate the treatment effects. The results showed that the distal tipping of the maxillary first and second molars, and first and second premolars and canines were statistically significant. Significant distal movement occurred in all posterior and canine teeth. The maxillary first molar distalization was found to be 3.5 mm. The maxillary incisor showed significant proclination and protrusion. The decrease in overbite was found to be statistically significant. The mandibular plane angle significantly increased by a mean of 0.5 mm. In addition, significant soft tissue changes were observed.     

Effects of a segmented removable appliance in molar distalization

The aim of the present investigation was to evaluate the skeletal and dentoalveolar treatment effects of a segmented removable appliance [removable molar distalizer (RMD)] for molar distalization. The study was conducted on 28 patients (12 females and 16 males), with a mean age of 11.8 years. All presented with a skeletal Class I malocclusion and a bilateral dental Class II molar relationship. The pre- and post-distalization records included lateral head films, study models and standard photographs. The findings were evaluated with a paired samples t-test. The average maxillary first molar distalization with the RMD was 3.98 mm, with 4.61 degrees of distal tipping. The maxillary second premolars drifted distally 2.13 mm on average with 1.54 degrees of distal tipping, while the maxillary first premolars showed 1.23 mm of mesial movement and 1.98 degrees of mesial tipping. The incisors protruded 1.09 mm with 1.27 degrees of labial tipping. The RMD was effective in distal molar movement and all patients attained a bilateral Class I molar relationship in an average period of 4.5 months. Hygiene problems and mucosal irritations, frequently found with fixed intraoral distalization techniques, were not observed during the distalization period.     

Evaluation of maxillary molar distalization with the distal jet: a comparison with other contemporary methods

Maxillary molar distalization is an increasingly popular option for the resolution of Class II malocclusions. This communication describes the effects of one particular molar distalizing appliance, the distal jet, in a sample of 20 consecutively treated and growing subjects (11 females, nine males; mean starting age of 13) and compares these effects with those of similar devices. Pre- and postdistalization cephalometric radiographs and dental models were analyzed to determine the dental and skeletal effects. The distal jet appliances were constructed using a biomechanical couple to direct the distalizing force to the level of the maxillary first molar's center of resistance. The distal jet was the only appliance used during the distalization phase of treatment. Examination of the cephalometric tracings demonstrated that the crowns of the maxillary first molars were distalized an average of 3.2 mm into a Class I molar relationship. In the process, the first molars were tipped distally an average of 3.1 degrees, however, the amount of tipping in each case was influenced by the state of eruption of the second molar. In subjects whose second molars had erupted only to the level of the apical third of the first molar roots, distal tipping was almost twice that seen when the second molar had completed their eruption. Anchorage loss measured at the first premolars averaged 1.3 mm, but the crowns tipped 3.1 degrees distally because of the design of the appliance. The maxillary incisors were proclined an average of 0.6 degrees with minimal effect on the mandibular plane angle and lower facial height. This study suggests that the distal jet appliance effectively moves the maxillary molars distally into a Class I molar relationship with minimal distal tipping, however, some loss of anchorage is to be expected during this process. The distal jet appliance compares favorably with other intraoral distalization devices and with mechanics featuring mandibular protraction for the resolution of patients with Class II, despite the fact that these types of mechanics address different jaws.     

摆形矫治器远移磨牙的矢状方向分析

目的本研究在矢状方向上分析摆形矫治器远移上磨牙的效果及对支抗前磨牙、切牙的交互作用。方法选择14例安氏Ⅱ类错、上牙弓I-Ⅱ°拥挤患者,应用摆形矫治器远移上颌第一磨牙,每一病例治疗前后进行头影测量分析比较。结果14例患者在17.5±7周内上第一磨牙远移3.18±1.62mm,伴有前磨牙1.42±1.16mm、切牙0.97±0.45mm的近中移动,同时注意到上磨牙的远移、第二前磨牙与切牙的近移均是倾斜移动,统计分析显示各评估对象在治疗前后具有显著性差异。结论摆形矫治器是一种简便、对患者依赖少的上磨牙远移装置,可在临床中广泛应用。     

Cephalometric Changes following Simultaneous First and Second Maxillary Molar Distalization Using a Non-Compliance Intraoral Appliance

AIM: The aim of this prospective study was to evaluate the dentoalveolar, skeletal and soft tissue changes induced by a modified minimal-compliance intraoral appliance following the simultaneous distalization of first and second maxillary molars. SUBJECTS AND METHODS: The study sample consisted of 14 patients with a mean age of 13.4 years treated by one clinician. In all cases a bilateral Class II molar relationship was corrected to Class I in a mean treatment period of 16.5 weeks. Lateral cephalometric analysis of the sample was based on the radiographs taken before and immediately after treatment with the appliance. The mean maxillary first molar distal movement was 1.4 mm, accompanied by a mean distal tipping of 6.8 degrees. The vertical change in molar position was insignificant. The anchorage unit was unable to completely resist the reciprocal mesial force of the activated coil spring. The second premolars were moved mesially by a mean 2.6 mm and tipped by a mean 4.1 degrees without significant extrusion. The mean increase in overjet was 0.9 mm, and the mean decrease in overbite 1.0 mm. RESULTS: The results of this study have shown that the presented intraoral appliance is an effective and reliable means of distalizing first and second maxillary molars simultaneously without the need for patient compliance. Appliance effects are limited primarily to the dentoalveolar structures. Mesial movement and slight protrusion of the anchorage unit have to be taken seriously into consideration during intraoral distalization.     

Dentoskeletal effects induced by rapid molar distalization with the first class appliance.

The purpose of this study was to evaluate the treatment effects of the first class appliance (FCA; Leone, Firenze, Italy), a new intraoral device for unilateral or bilateral rapid molar distalizaton. A retrospective study was conducted to compare the predistalization and postdistalization cephalograms of 17 patients (10 male, 7 female) with Class II malocclusions treated with the FCA. Mean age at the start of treatment was 13 years 4 months. The FCA produced rapid molar distalization, and the bilateral Class II molar relationship was corrected in 2.4 months, on average. Maxillary molar distalization contributed to 70% of the space created anterior to the first molars; 30% of the space was due to reciprocal anchorage loss of the maxillary second premolars. The maxillary first molars showed a significant distalization of 4.0 mm, associated with a significant distal axial incline of 4.6 degrees and a significant extrusion of 1.2 mm. As for anchorage loss, the second premolars exhibited a significant mesial movement of 1.7 mm, associated with a significant mesial axial incline of 2.2 degrees and a nonsignificant extrusion of 1.0 mm. In the anterior region, a significant mesial movement of the maxillary incisor of 1.3 mm was associated with a significant incisor proclination (2.6 degrees ) and a significant increase in overjet (1.2 mm). No significant changes in either sagittal or vertical skeletal relationships were observed. The results suggest that the FCA is an efficient and reliable device for distalizing the maxillary permanent first molars.     

改良式摆型矫治器远中移动上颌磨牙的疗效分析

目的 评价改良式摆型矫治器远中移动上颌磨牙的疗效。方法 选择14例牙性安氏Ⅱ类错的患者,应用改良式摆型矫治器远移上颌第一磨牙,通过矫治前和磨牙远移到位后的X线头影测量分析评价其疗效。结果 磨牙平均向远中移动3.85mm,牙冠远中倾斜3.22°;切牙近中倾斜移动2.08mm,覆盖增加1.68mm。结论 改良式摆型矫治器能有效地整体远中移动上颌磨牙,快速矫正磨牙关系,但也会引起少量的支抗丧失和切牙唇向移动。     

Evaluation of the effects of the hybrid Pendulum in comparison with the conventional Pendulum appliance

Objective:To evaluate the anchorage control and distalization of maxillary molars with the hybrid Pendulum appliance and to compare the results with a conventional Pendulum appliance.Materials and Methods:This study was carried out on the pre-(T0) and post-(T1) treatment lateral cephalograms and dental casts of 43 patients with Angle Class II molar relationships who were treated with conventional or hybrid Pendulum appliances. The hybrid Pendulum (HP) group consisted of 22 patients (14 females; eight males; mean age 14.3 ± 2.43 years) and treatment results were compared with a conventional Pendulum appliance (CP) group, which consisted of 21 patients (15 females; six males; mean age 14.6 ± 3.39 years). Intragroup comparisons were made with Wilcoxon test and intergroup comparisons were made with Mann-Whitney U-test (P < .05).Results:The mean distalization duration was 0.70 ± 0.25 years in the HP group and 0.83 ± 0.4 years in the CP group. Maxillary first molars showed significant distal movement and tipping of 4.25 mm and 9.09° in the HP group, and 3.21 mm and 9.86° in the CP group. Loss of anchorage at the first premolars was significantly smaller in the HP appliance group compared to CP group. The second premolars distalized spontaneously in the HP group while they mesialized significantly in the CP group. Proclination and protrusion of maxillary incisors were greater with the CP appliance compared to the HP appliance.Conclusions:Maxillary molar distalization was achieved with both appliances. Mesialization of the anchorage unit was controlled successfully with the hybrid Pendulum; however, the conventional Pendulum appliance caused anchorage loss.     

Cephalometric evaluation of the effects of pendulum appliance on various vertical growth patterns and of the changes during short-term stabilization

The aim of this study was to evaluate the effects of the pendulum appliance in dental Class II patients with varying vertical growth patterns and to evaluate the changes during the short-term stabilization period of 3 months. The sample (n=30) was divided into two groups based on their FMA degrees. The high-angle group consisted of 14 patients (10 girls and 4 boys) and had a mean age of 157.7+/-8.0 months. The low-angle group consisted of 16 patients (8 girls and 8 boys) and had a mean age of 155.5+/-18.6 months. Pretreatment, posttreatment and poststabilization cephalometric radiographs were obtained to measure the changes. Mann-Whitney U and Wilcoxon tests were used for statistical evaluation. The amount of upper molar distalization was 5.9 mm (p<0.001) in the high-angle group and 1 mm (p<0.001) in the low-angle group, showing no intergroup difference. The amount of anchorage loss at the second premolars was 4.8 mm (p<0.001) in the high-angle group and 6.6 mm (p<0.001) in the low-angle group. Upper incisors moved anteriorly for 2.1 mm (p<0.05) in the high-angle group and 4.1 mm (p<0.001) in the low-angle group. Intergroup difference was statistically significant (p<0.001). During the stabilization period, 1.5 mm of anchorage loss was measured at the upper molar region in the high-angle group and 1.7 mm of anchorage loss was measured at the upper molar region in the low-angle group. During the stabilization period, upper second premolars and incisors tended to move back to their original places. The results of this study showed that pendulum appliance could move the upper molars distally in a short period of time without depending on the patient compliance. Care should be taken to prevent anchorage loss and to stabilize the upper molars for, at least, 3 months.