Incisal paths during habitual mouth opening and closing movements of children with anterior reverse bite in the early mixed dentition

The purpose of this study was to investigate whether the pathways of habitual mouth opening and closing in children with anterior reverse bite in the early mixed dentition differed from those of children with normal occlusion. The two subject groups for this study were composed of ten children with anterior reverse bite (reverse bite group) and twelve children with normal occlusion (normal occlusion group), respectively. These movements were measured by an optoelectronic analyzing system with six degrees of freedom. Movements of the incisal point were projected on the sagittal plane to characterize the paths, and sagittal angles between the incisal path and the horizontal plane were calculated and compared. Opening and closing sagittal angles in the reverse bite group were almost equal over the entire pathway, indicating that the pathways of habitual mouth opening and closing were similar. In contrast, all opening and closing sagittal angles in the normal occlusion group were different, especially close to maximum intercuspation, indicating that their pathway of habitual mouth opening differed from their mouth closing pathway. In conclusion, children with anterior reverse bite in the early mixed dentition have different patterns of habitual mouth opening and closing movements than children with normal occlusion.     

Translation and rotation of the mandible during habitual mouth opening movement in children with anterior reverse bite in the primary dentition

Translation and rotation of the mandible during habitual mouth opening movements were studied in 13 children with skeletal-based anterior reverse bite (reverse bite group) and in 13 children with normal occlusion (normal occlusion group) whose dental stage was the primary dentition. Movements were recorded by an opto-electronic movement-analyzing system that could measure mandibular movements with six degrees of freedom. Inferior translation of the mandible was analyzed at the left primary central incisor, both of the primary canines, and both of the primary second molars. Anterior translation of the mandible was analyzed at both of the condyles. Rotation of the mandible was measured in the sagittal plane. The results showed that the associations between the translation and rotation of the mandible during habitual mouth opening in the reverse bite group differed from those in the normal occlusion group. The reverse bite group had greater anterior translation of both of the condylar points than did the normal occlusion group. No significant differences were found in the inferior translation or rotation of the mandible between the two groups.     

恒牙期前牙开正畸治疗时机和疗效的研究

目的　通过对恒牙初期和恒牙晚期正畸治疗成功的病例进行分析 ,探讨恒牙期前牙开患者正畸治疗的时机及引起颅面形态的变化。方法　选择 13名恒牙初期和 12名恒牙期前牙开患者 ,利用计算机X线头影测量分析治疗前后的软硬组织变化 ,并进行统计学处理。结果　正畸的治疗变化以牙齿倾斜度的变化为主 ,前牙有一定的伸长 ,垂直高度有所增加 ,软组织面型有一定程度的改善。恒牙初期与恒牙期正畸治疗相比 ,除了上下前牙倾斜度的变化以外 ,还存在一定的下颌逆时针旋转趋势 ,而恒牙期者下颌平面角有顺时针旋转倾向。结论　提倡在恒牙初期即开始正畸治疗。     

Factors associated with anterior open bite in children with developmental disabilities

Aim: To investigate factors associated with anterior open bite in individuals aged from 2 to 33 years with developmental disabilities. Design: This is a cross‐sectional study. A total of 271 dental records were examined. The anterior open bite analyzed was determined based on clinic exam. These variables were also analyzed: gender, age, education level of mother, International Code of Diseases (ICD), mouth breathing, use of anticonvulsant drugs, hyperkinesis, pacifier use, thumb sucking, seizure, and involuntary movements. For the purposes of analysis, the individuals were categorized as being with and without anterior open bite. Variables with a p ‐value of < 0.25 in the bivariate analysis were incorporated into the logistic regression models. Results: Mouth breathers had a 2.60‐fold (95% CI: 1.35–5.01) greater chance of exhibiting anterior open bite than nasal breathers. Pacifier users are more likely to have an anterior open bite (3.32‐fold, 95% CI: 1.62–6.77). Individuals with reported involuntary movements had a 2.66‐fold (95% CI: 1.26–5.63) greater chance of exhibiting anterior open bite. Users of anticonvulsants drugs had a 3.05 (95% CI: 1.57–5.92) greater chance of showing anterior open bite. Conclusion: Involuntary movements, mouth breathing, using anticonvulsant drugs, and using pacifier are factors associated with anterior open bite in patients with developmental disabilities.     

正畸治疗中磨牙的拔除和保留（五十二）——骨钉牵引全牙弓后移中的咬合打开问题探讨

目的：评价各种打开前牙咬合方法在应用骨钉牵引牙弓整体远移过程中的效果及其作用机理。方法：共选取采用骨钉进行全牙弓整体后移的病例100例,其中男性22例,女性78例,年龄12～45岁,平均19.4岁。减数第二或第三磨牙者82例,不减数者18例。所有病例均采用上颌颧牙槽嵴区及下颌外斜线区骨钉牵引全牙弓远中移动。采用不同方式打开前牙咬合。结果：以临床打开咬合的效果来看,单纯应用高弹摇椅形圆丝打开咬合效果最差,应用高弹摇椅形圆丝与平导组次之,其余组均有好的咬合打开效果,最好为NiTi方丝复合牵引钩组。结论：摇椅形唇弓不适用于应用骨钉全牙弓整体向后牵引,而NiTi方丝附复合牵引钩不仅可以产生明显的前牙咬合打开效果,同时不妨碍全牙弓的整体后移,是骨钉应用的一种重要矫治手段。     

弹性包绕式牙合垫加前方牵引矫治替牙期骨性反(牙合)

目的探讨弹性包绕式垫加前方牵引矫治替牙期骨性反的适用性及治疗前后的牙颌结构变化。方法选择替牙期骨性Ⅲ类错患者9例,平均年龄8.1±1.5岁,患者前牙反,上颌相对于下颌后缩,应用弹性树脂材料制作包绕上颌全部牙齿及部分牙槽骨的包绕式垫,中部连接螺旋扩弓器快速扩弓,加前方牵引矫治反。在头颅侧位片上测量矫治前后牙、牙槽骨及颌骨的变化。结果弹性包绕式垫固位良好,腭中缝在2～3周内打开,前牙反在6～11个月内解除;上颌骨前移,下颌骨轻度向下后旋转,SNA平均增大1.9°,ANB角平均增大2.8°;治疗后上切牙唇倾,下切牙舌倾。结论在替牙期采用弹性包绕式垫加前方牵引能够促进上颌骨生长,简便、有效地治疗替牙期骨性反。     

Correlations between incisor and condylar movements during lateral excursion in children with primary dentition

The purpose of this study was to look for associations between lower incisor movement and working and balancing condylar movement during lateral excursion in children with primary dentition and adults with permanent dentition. Mandibular movement was recorded using a TRI-MET (an optoelectronic analysis system with six degrees-of-freedom) at a sampling frequency of 100 Hz. The movement data was transferred to a graphics workstation for analysis. Subjects were categorized by age into two groups. The primary dentition group consisted of 19 children (mean age: 5 years and 5 months, s.d.: 8.7 months), and the permanent dentition group consisted of 22 women (mean age: 20 years and 5 months, s.d.: 26.3 months). The occlusion and TMJ in both groups were normal, with no history of orthodontic treatment. Three orthogonal excursive ranges and the 3D linear distance of the incisal and balancing and working condylar points, along with inter- and intra-individual correlations between the incisor and the balancing and working condyles during lateral excursion, were estimated by using multilevel statistical models. Lateral excursion in children with primary dentition was characterized by smaller incisor excursive ranges and 3D linear distance than in adults, and stronger inter- and intra-individual correlations between incisor and balancing condylar movements than in adults. In both children and adults the lateral excursion of the incisor was a good indicator of the extent of balancing condylar movement, but not working condylar movement.     

Early risk factors for posterior crossbite and anterior open bite in the primary dentition

Objective:To investigate risk factors specific to posterior crossbite and anterior open bite at the age of 3 years.Materials and Methods:The study included 422 children of the French EDEN mother-child cohort. The main outcomes were the presence of posterior crossbite and anterior open bite assessed by dentists at 3 years. Social characteristics (collected during pregnancy), neonatal characteristics (collected at birth), duration of breast-feeding (collected prospectively), sucking habits at 3 years, and open lips (as a proxy for mouth breathing) were studied and two logistic regressions conducted.Results: Preterm birth appears to be a risk factor specific for posterior crossbite (OR: 3.13; 95% CI: 1.13–8.68), whereas small for gestational age seems to be associated with a lower risk of posterior crossbite (OR: 0.32; 95% CI: 0.12–0.87). Ongoing pacifier or thumb sucking at 3 years is a risk factor for both posterior crossbite and anterior open bite.Conclusions: Children born preterm seem to be more at risk for posterior crossbite than those born at term. Different mechanisms may be involved in posterior crossbite and anterior open bite.     

单侧后牙锁患者前伸及后退髁突运动轨迹的研究

目的探讨单侧后牙锁者在下颌前伸、后退运动过程中髁突运动轨迹的特征及其与正常者之间的差异。方法选择单侧后牙锁患者24例和个别正常25例,应用髁突运动轴图描记仪(computer aided diagnosis axiograph,CADIAX)记录下颌前伸、后退运动时髁突的运动轨迹。结果实验组在下颌前伸、后退运动过程中髁突轨迹曲折、不流畅、重合性差,两侧髁突运动不对称、侧方位移增大;其锁侧在矢状方向和空间位移上以及髁突矢状面倾斜度小于非锁侧(P<0.05),锁侧髁突矢状面倾斜度较对照组小(P<0.05),在髁突位移5mm处水平面髁突倾斜度大于对照组(P<0.05)。结论单侧后牙锁者下颌前伸、后退运动时两侧髁突运动不对称,侧方位移增加。     

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目的    探讨镍钛（NiTi）摇椅弓附加前牙区垂直牵引对前牙开牙合畸形的治疗效果。 方法    利用NiTi摇椅弓加前牙区垂直牵引对2007—2009年在厦门市第一医院思明分院口腔科就诊的18例前牙开牙合畸形患者进行矫治,并对矫治前后的头颅侧位片进行测量分析。结果    X线头影测量显示治疗后骨骼无显著变化,下切牙伸长,下磨牙压低,上切牙及上下后牙竖直,上颌牙合平面有顺时针旋转的趋势,下颌牙合平面有逆时针旋转的趋势。开牙合间隙关闭,前后牙建立良好的咬合关系,所有病例治疗后均取得满意疗效。结论    NiTi摇椅弓加前牙区垂直牵引是治疗前牙开牙合的有效方法。     

自制的简易咬合块在口腔临床治疗中的应用

目的 探讨用自制的简易咬合块对口腔门诊患者治疗时张口舒适度的应用效果。方法 将就诊于成都市中西医结合医院口腔科的162 例患者随机分为试验组（84例患者）与对照组（78例患者）,在进行口腔治疗时,试验组患者放置医院自制的简易咬合块,对照组患者不放置咬合块。治疗完成后使用问卷调查表,记录两组患者治疗时的张口舒适度。结果 试验组患者的张口舒适度明显优于对照组（P<0.01）。结论 简易咬合块有利于增加口腔患者治疗时的张口舒适度。     

Relations between anterior disc displacement and maxillomandibular morphology in skeletal anterior open bite with changes to the mandibular condyle

In this study we investigated the relation between anterior disc displacement (ADD) and maxillomandibular morphology in skeletal anterior open bite with changes to the mandibular condyle. Thirty female patients (60 joints) with both conditions were evaluated. Magnetic resonance imaging of the temporomandibular joint (TMJ) was used to diagnose both ADD and changes to the mandibular condyle (erosion, osteophyte, and deformity). The relations among ADD, changes to the mandibular condyle, and maxillomandibular morphology were examined statistically. Changes to the mandibular condyle had a higher score than sym anterior open bite, the deviated side in asymmetric anterior open bite, and the non-deviated side. The score for disc displacement on the non-deviated side was lower than both the sym side and the deviated side. Unilateral changes to the mandibular condyle and unilateral disc displacement were not apparent in sym anterior open bite, but a unilateral non-displaced disc was seen only on the asymmetric side. Mandibular condylar changes were significantly more common on the deviated, than on the non-deviated, side. The SNB angle was significantly smaller, and the ANB, GZN, and SN-mandibular plane angles were significantly larger in sym anterior open bite. Overjet, ANB angle, GZN angle, and SN-MP angle were significantly larger, and the SNB angle was significantly smaller, in the presence of ADD without reduction and mandibular condylar deformity. We conclude that the prevalence of ADD without reduction and changes to the mandibular condyle were related to mandibular asymmetry and mandibular morphology in anterior open bite. This retrospective study suggests that ADD without reduction and mandibular condylar bone changes may be related to the progression of skeletal class II open bite and mandibular asymmetry in cases of skeletal open bite.     

成年人上前牙缺失伴前牙反矫治后修复的临床意义

目的　探讨用固定矫治的方法矫正成年人上前牙缺失伴前牙反牙合后再修复缺失牙的效果和临床价值。方法　 2 0例患者均用固定矫治的方法解除前牙反牙合后再行固定义齿或种植义齿修复缺失的前牙。结果　2 0例矫治后均取得正常的咬合关系和正常的失牙修复 ,平均追踪 2年 ,未见反牙合复发和修复牙的异常。结论　用固定矫治方法解除成年人前牙缺失后的反牙合再行义齿修复 ,保证了失牙修复功能和美观效果 ,是保证缺牙区良好咬合关系的有效方法     

First molar cross‐bite is more closely associated with a reverse chewing cycle than anterior or pre‐molar cross‐bite during mastication

A posterior cross‐bite is defined as an abnormal bucco‐lingual relationship between opposing molars, pre‐molars or both in centric occlusion. Although it has been reported that patients with unilateral posterior cross‐bite often show unique chewing patterns, the relationship between the form of cross‐bite and masticatory jaw movement remains unclear in adult patients. The objective of this study was to investigate masticatory jaw movement among different forms of cross‐bite. One hundred and one adults were recruited in this study: 27 had unilateral first molar cross‐bite (MC group); 28, unilateral pre‐molar cross‐bite (PC group); 23, anterior cross‐bite (AC group); and 23, normal occlusion (control group). Masticatory jaw movement of the lower incisor point was recorded with six degrees of freedom jaw‐tracking system during unilateral mastication. Our results showed that the reverse chewing ratio during deliberate unilateral mastication was significantly larger in the MC group than in the PA (P < 0·001), AC (P < 0·001) and control (P < 0·001) groups. These findings suggest that compared to the anterior or pre‐molar cross‐bite, the first molar cross‐bite is more closely associated with a higher prevalence of a reverse chewing cycle.     

Temporalis and masseter muscle activity in patients with anterior open bite and craniomandibular disorders

Abstract – Activity in temporalis and masseter muscles, and traits of facial morphology and occlusal stability were studied in 22 patients (19 women, 3 men; 15–45 yr of age) with anterior open bite and symptoms and signs of craniomandibular disorders. Facial morphology was assessed by profile radiographs, occlusal stability by tooth contacts, and craniomandibular function by clinical and radiological examination. Electromyographic activity was recorded by surface electrodes after primary treatment with a reflex-releasing, stabilizing splint. Maximal voluntary contraction was reduced compared to reference values, particularly in subjects with muscular affection, but maximal activity increased significantly when biting on the splint. Maximal voluntary contraction was positively correlated to molar contact and negatively to anterior face height, mandibular inclination, vertical jaw relation and gonial angle. Relative loading of the muscles was markedly increased during resting posture. It was concluded that reduced occlusal stability and long-face morphology were associated with weak elevator muscle activity with disposition overload and tenderness. The results also indicated that increase of occlusal stability might lead to increased muscle strength and possibly reduce risk of physical strain.     

光棒引导经鼻插管在张口困难患者中临床应用

目的:探讨光棒引导经鼻气管插管在张口困难患者中应用的可行性.方法:选择82例口腔颌面外科张口困难(张口度＜2.5 cm)患者,在快诱导麻醉下由光棒引导经鼻气管插管.记录患者麻醉诱导前后、插管过程中和插管后的SBP、DBP和HR.记录插管成功时的插管次数、插管时间及术后24 h并发症发生率.结果:82例患者中,53例(64.6％)一次性插管成功,29例(35.4％)经2～3次插管成功.插管操作时间(75.4-±26.4)s.与诱导前相比,插管时的BP和HR差异无显著性.术后随访2例有轻微咽部不适,1例主诉咽喉疼痛.结论:光棒引导经鼻气管插管对血流动力学影响轻微,口咽部损伤小,成功率高,在张口困难患者中值得推广应用.     

A comparison and validation of amorphous sensor condylar movement analysis to MRI diagnosis of anterior disc displacement

This study compared temporomandibular joint condylar movements in a sample of six patients with clinically normal joints, with those of nine patients with joints diagnosed by magnetic resonance imaging (MRI) to have anterior disc displacement with reduction (ADD). The aim of this study was to compare and validate the use of the amorphous sensor to MRI diagnosis in condylar movement analysis. The measuring device consisted of an amorphous sensor and a small magnet. Condylar and jaw movements were recorded simultaneously over the course of 10 open-close cycles. Maximum velocity of condylar movement during the opening phase in the ADD joints was significantly higher than the normal joints. The degree of jaw opening at the turning point of condylar movement in the ADD joints was significantly larger than the normal joints. The diagnostic sensitivity and specificity of the maximum velocity of condylar movement during the opening phase was 75.0 and 75.0%, respectively, while those of the degree of jaw opening at the turning point of condylar movement were 91.7 and 91.7%, respectively. These results suggest that the analysis of condylar movement, employing the amorphous sensor may be a reliable method for diagnosis of ADD.     

混合牙列期身体重心动摇和咬合力的相关性研究

目的：调查混合牙列期身体重心动摇与咬合力之间的关系。方法56名处于Hellman咬合发育Ⅲ期A阶段的健康小学生纳入研究。通过检查咬合平衡中点与中线的距离( X)关系,X≤5 mm被划分为正中组,X>5 mm被划分为偏移组。使用自动姿态分析系统测定了身体平衡相关开闭眼时的重心动摇距离、重心动摇面积。使用牙齿压力感应装置Dental Prescale?测定了咬合接触面积、平均咬合力、最大咬合压力,咬合力和咬合平衡。结果咬合接触面积和咬合力的测试结果男女分别为18.1 mm2、712.2 N和14.1 mm2、541.8 N,差异均具有统计学意义(P<0.05)。咬合平衡中点正中组与偏移组的咬合接触面积、咬合力之间差异具有统计学意义(P <0.05)。咬合平衡中点正中组开、闭眼时期的重心动摇距离、面积明显小于偏移组,咬合平衡与开、闭眼时期的重心动摇距离、面积有关且具有统计学意义(P<0.05)。重心动摇稳定组的咬合接触面积大于动摇组,两者差异具有统计学意义(P<0.05)。结论 Hellman咬合发育Ⅲ期A阶段儿童咬合平衡和人体重心动摇存在相关性,咬合接触面积与身体重心动摇相互影响。     

Local kinematic and anthropometric factors related to the maximum mouth opening in healthy individuals

The aim of the present study was to investigate the influence of local anthropometric (mandibular length and width) and kinematic (forward and downward condylar translation and angle of rotation) variables upon the maximum mouth opening (MMO). Thirty-five healthy individuals, 17 men and 18 women, mean age 23 years with a range from 18 to 31 years, performed six to eight maximal, symmetrical and pain-free open-close movements during a 20-s recording. Mandibular movements were recorded by means of the OKAS-3D jaw movement recording system. A stepwise regression analysis showed that differences in MMO are mainly explained by differences in the angle of rotation and in mandibular length (R2adj=91.5%). Including the downward and forward component of condylar translation into the regression model increased the explained variance with only 4.7%. A second stepwise analysis showed that the angle of rotation is positively related to the forward component of the condylar translation and negatively related to its downward component (R2adj=52.7%). In conclusion, differences in MMO between healthy individuals are, to a large extent, explained by differences in the angle of rotation and in mandibular length. In its turn, differences in the angle of rotation are related to differences in condylar translation.