Maxillary molar distalization: Pendulum and Fast-Back, comparison between two approaches for Class II malocclusion

Objectives

To compare the dento-alveolar and skeletal effects produced by two different molar intraoral distalization appliances, Pendulum and Fast-Back, both followed by fixed appliances, in the treatment of Class II malocclusion.

Materials and methods

41 patients for Pendulum (18 males and 23 females) and 35 for Fast-Back (14 males and 21 females) were selected, with a mean age at the start of treatment of 12.11 years in the Pendulum group and 13.3 for in the Fast-Back group. The durations of the distalization phase were 8 months in the Pendulum group and 9 months in the Fast-Back group, and the durations of the second phase of treatment with fixed appliances were 19 months in the Pendulum group and 20 months in the Fast-Back group. Lateral cephalograms were analyzed at 3 observation times: before treatment, after distalization and after comprehensive orthodontic treatment.

Results

During molar distalization the Pendulum subjects showed greater distal molar movement and less anchorage loss at both the premolars and maxillary incisors than the Fast-Back subjects. Pendulum and Fast-Back produced similar amounts of distal molar movement and overcorrection of molar relationship at the end of distalization though the Fast-Back induced a more bodily movement. Very little change occurred in the inclination of the mandibular plane at the end of the 2-phase treatment in both groups. At the end of treatment the maxillary first molars were on average 1 mm more distal in the Pendulum group compared to the Fast-Back group, while the total molar correction was 3.2 mm with 3.9° of distal inclination for the Pendulum and 2 mm with 1.1° of mesial inclination for the Fast-Back. Both appliance were equally effective in inducing a satisfactory Class I relationship in 97.2% of the cases.

Conclusion

The Pendulum and the Fast-Back induce similar dentoskeletal effects. The use of the two distalization devices, therefore, can be considered clinically equivalent.     

Interaction between deglutition,tongue posture,and malocclusion: A comparison of intraoral compartment formation in subjects with neutral occlusion or different types of malocclusion

Objective:To test the null hypothesis of no significant difference in terms of intraoral pressure curve characteristics assessed simultaneously at the subpalatal space (SPS) and the vestibular space (VS), during different oral postures, between four groups with either an Angle Class II/1 (II1), Angle Class II/2 (II2), anterior open bite (O) malocclusion, or a neutral occlusion control group (I).Materials and Methods:Intraoral pressure recordings were performed simultaneously in the VS and SPS of 69 consecutive subjects (n_II1  =  15; n_II2  =  17; n_O  =  17; n_I  =  20; mean age/standard deviation 18.43/6.60 years). Assessments included defined sections of open mouth posture (OMP, 30 seconds), anteriorly closed mouth condition (60 seconds), dynamics by a tongue-repositioning maneuver (TRM, 60 seconds), swallowing, and positive pressure generation (PP, 10 seconds). Interactions of malocclusion, compartment location, and posture on pressure curve characteristics were analyzed by Kruskal-Wallis and Mann-Whitney U-tests, adopting an α level of 5%.Results:Globally significant group differences were detected at the VS (plateau duration and median peak heights during TRM; area under pressure curve [AUC] during PP) and SPS (AUC during TRM and PP). Subjects with anteriorly nonopen dental configurations (groups I and II2) were able to keep negative pressure levels at the VS for longer time periods during TRM, compared to groups O and II1.Conclusions:The null hypothesis was rejected for mean VS plateau durations and peak heights and for SPS AUC. Negative pressures at the VS may stabilize outer soft tissues passively and may explain the dental arch form shaping effect by mimic muscles.     

Malocclusion and masticatory muscle activity: a comparison of four types of malocclusion.

Electromyographic activities of the temporalis and masseter muscles during mastication were measured in patients who visited this clinic for orthodontic treatment of progenia. The results obtained were compared with those previously obtained in patients with other types of malocclusion and relationships between types of malocclusion and activities of the masticatory muscles were examined. Several interesting results were obtained, including: 1) the muscle activities were significantly higher in patients with deep bite than in patients with any other types of malocclusion and 2) inefficient mastication patterns, evidenced by higher temporalis muscle activities on the balancing side than on the working side, were most frequently observed in patients with edge bite. These results indicate that the clinical evaluation of masticatory muscle activities may be useful in improving orthodontic treatment and in determining a proper retention period after the treatment. The results also suggest that orthodontic treatment should include some type of dynamic myofunctional therapy in addition to the correction of static structural abnormalities.     

错(牙合)畸形的下颌功能运动轨迹及其分类

目的对错畸形者的下颌运动轨迹进行分类。方法对错畸形患者的口颌功能进行临床检查并以下颌运动轨迹描记仪进行轨迹分析。结果对２２３例错（男１０６名,女１１７名,平均年龄１４６岁）的观察表明,将近４０％的患者存在功能性错,特定的错类型常呈现出特征性的下颌运动轨迹。同时发现,下颌运动轨迹受上下颌骨、肌肉、关节及牙齿等综合因素的影响。结论本项研究总结归纳出功能性错的分类方法（包括功能性１、２、３、４类错）。     

Herbst矫治器双期矫治与拔牙矫治AngleⅡ类错[牙合]的对比研究

目的 比较Herbst矫治器双期矫治和单纯拔牙矫治恒牙期Angle Ⅱ类错(牙合)的效果.方法 选择18例及16例FG-G期恒牙期Angle Ⅱ类错(牙合)患者,分别作为Herbat组和拔牙组;Herbst组经金属铸造夹板式Herbat矫治器矫治后,立即接受方丝弓矫治器完成二期矫治;拔牙组拔出4个双尖牙方丝弓技术矫治;通过X线头影测量方法评价两组疗效.结果 前牙覆盖减小及磨牙关系改善中,Herbst组骨性变化占44%及57%,而拔牙组主要为86%及78%的牙性变化;较拔牙组的变化,Herbst组下颌升支长度、下颌体长度、下颌有效长度分别多增加了1.59mm、1.26mm和2.41mm SNB多增加了2.15°,ANB多减小了1.66°(P<0.001);Herbst组软组织侧貌突度具有更加明显的减小.结论 对以下颌后缩为主要特征的恒牙期Ⅱ类错(牙合),采用Herbst矫治器双期矫治具有显著疗效,而不宜单纯采用拔牙矫治.     

错He畸形的下颌功能运动轨迹及其分类

目的 对错Ｈｅ畸形者的下颌运动轨迹进行分类。方法 对错Ｈｅ畸形患者的口颌功能进行临床检查并以下颌运动轨迹描记进行轨迹分析。结果 对２２３例错Ｈｅ（男１０６名,女１１７名,平均年龄１４．６岁）的观察表明,将近４０％的患者存在功能性错Ｈｅ,特定的错Ｈｅ类型常呈现出特征性的下颌运动轨迹。同时发现,下颌运动轨迹受上下颌骨、肌肉、关节及牙齿等综合因素的影响。结论 本项研究总结归纳出功能性错Ｈｅ的分类方法（包     

Peripheral dentinogenic ghost cell tumor—report of two cases and review of the literature

Oral and Maxillofacial Surgery - Peripheral dentinogenic ghost cell tumor (DGCT) is a rare and non-aggressive benign odontogenic tumor. They usually affect the elderly and are predominantly located...     

Cleft type and Angle's classification of malocclusion in Korean cleft patients

This study was performed to investigate the contributing factors, such as cleft type, side of cleft, patient's age, and gender, associated with Angle's classification of malocclusion in Korean cleft patients. The records of 250 cleft patients (175 males, 75 females) who attended the Department of Orthodontics, Seoul National University Dental Hospital between 1988 and 1999 were examined. The percentages of subjects with cleft lip (CL), cleft lip and alveolus (CLA), cleft palate (CP), and cleft lip and palate (CLP) were 7.6, 19.2, 9.6, and 63.6, respectively. The overall distributions of unilateral and bilateral clefts were 76 and 24 per cent, respectively. The overall percentages of Class I, II, and III malocclusions were 18.5, 8.8, and 72.7. The frequency of Class III malocclusions was most prevalent in all age groups. Bivariate analysis showed that whilst gender was not significant, the type of cleft significantly influenced the development of a Class III malocclusion (P < 0.01). Using logistic regression analysis, subjects in the CP (P < 0.05) and CLP groups (P < 0.01) were 3.9 and 5.5 times more likely to have a Class III malocclusion than those in the CL group. There was, however, no statistical difference in the prevalence of a Class III malocclusion between the CL and the CLA groups (P > 0.05). When the degree of cleft involvement in the palate increased, so did the predominance of a Class III malocclusion.     

A comparison between two types of radiographic film for accuracy of measurements of approximal osseous defects

AIM: The purpose of this study was to compare two types of conventional radiographic film: Ekta-speed plus and Insight (Eastman Kodak Co, Rochester NY, USA) for accuracy of measurements of approximal bone loss. METHODS AND MATERIALS: Four dried human mandibles with complete dentition were selected. Radiographic images were made with a standardized technique. Mesial and distal bone levels on the mandibular premolar and molar teeth were measured on the two types of radiographs (Ekta-speed plus and Insight) by nine observers. The data obtained by the observers were compared with the primary investigators' corresponding measurements, which served as "the ground truth" for this study. RESULTS: The results of the analysis of variance (ANOVA) demonstrated a significant difference for the Ekta-speed plus film (p = .001), but the difference was not clinically significant. The level of intra-rater reliability was high for the observers (0.969 to 0.990). CONCLUSION: Performance of Ekta-speed plus and Insight films was found to be similar.     

A comparison in man of the performance of two types of surface electrode used for electromyography

Two types of surface electrode commonly used for electromyography, one a silver disc applied to the skin, the other a platinum wire hook inserted just into the skin, were compared by determining the amplitude of the surface representation of single motor units. Experiments were performed on the masseter muscle and a small muscle of the hand. The technique employed involved simultaneous recording from a needle electrode, used to detect the discharge of single units, and from the two types of surface electrode. No difference was found between the effectiveness of the two.     

错(牙合)类型对正畸治疗中牙根吸收影响的临床研究

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