Evaluation of structural skeletal asymmetry of the glenoid fossa in adult patients with unilateral posterior crossbite using surface-to-surface matching on CBCT images

ObjectivesTo compare, using surface-to-surface (StS) matching, any shape differences between the crossbite and noncrossbite side of the glenoid fossa and articular eminence in adult patients affected by posterior unilateral crossbite (PUXB) and compare them with unaffected controls.Materials and Methods32 cone beam computed tomography (CBCT) scans of patients (mean age: 23.72 ± 3.74 years) undergoing surgical maxillary expansion were analyzed to obtain three-dimensional models of the left and right glenoid fossae that were superimposed using stable anatomical reference points and then compared using StS matching to evaluate the presence of any shape differences. These findings were compared with those obtained from 16 CBCT scans of unaffected controls (mean age: 23.72 ± 3.73 years).ResultsA mean difference of >11% was found between the study group and controls when comparing the matching percentages of the two sides of the glenoid fossa and articular eminence at all three levels of tolerance selected for this study. These differences were found to be highly statistically significant (P ≤ .0001).ConclusionsAccording to the shape analysis findings, adult PUXB patients exhibit a higher degree of glenoid fossa and articular eminence shape differences compared to unaffected controls.     

Effects of therapy on masseter activity and chewing kinematics in patients with unilateral posterior crossbite

ObjectiveTo describe the effects of therapy on masseter activity and chewing kinematic in patients with unilateral posterior crossbite (UPC).DesignFifty children (age: mean ± SD: 9.1 ± 2.3 years) with UPC (34 on the right side, 16 on the left side) and twenty children (age: 9.5 ± 2.6 years) with normal occlusion were selected for the study. The mandibular motion and the muscular activity during chewing soft and hard boli were simultaneously recorded, before and after correction with function generating bite, after a mean treatment time of 7.3 ± 2.4 months plus the retention time of 5–6 months. The percentage of reverse cycles and the percent difference between ipsilateral and contralateral peaks of the masseter electromyography envelopes were computed.ResultsBefore therapy, the percentage of reverse cycles during chewing on the crossbite side was greater in patients than in controls (P < 0.001) and significantly reduced after therapy (P < 0.001) towards the reference normal value (soft bolus; pre: 57 ± 30%, post:12 ± 17%; hard bolus; pre: 65 ± 34%, post: 12 ± 13%; reference value: soft bolus 4 ± 2%, hard bolus 5 ± 3%). Before therapy the percent difference between electromyography envelope peaks in patients was lower than in controls (P < 0.01) and significantly increased after therapy (P < 0.05) becoming similar to the reference normal value.ConclusionsThe correction induced a normal-like coordination of masseter muscles activity together with a significant reduction of the reverse chewing patterns. The previous altered muscular activation corresponded to the altered kinematics of reverse chewing cycles that might be considered a useful indicator of the severity of the masticatory function involvement.     

单侧完全性唇腭裂前方牵引治疗后的稳定性研究

目的 通过对唇腭裂术后反（牙合）患者前方牵引治疗患者的纵向研究,探讨唇腭裂患者前方牵引治疗的稳定性.方法 单侧完全性唇腭裂术后前牙反（牙合）患者,下颌不能后退至切牙对刃、凹面型;骨龄显示患者处于生长发育高峰前期的患者18例,平均年龄（9.63±1.24）岁.进行前方牵引治疗,建立前牙正常覆盖关系,治疗时间平均（1.07±0.23）年.12名患者于（2.71±0.77）年之内完成了随访,患者分别于治疗前、前方牵引治疗后及治疗完成2年后进行头颅侧位X线片检查,手工描图并进行9项角度和15项线距测量.不同时点的（牙合）颌面特征进行配对t检验,并对影响前牙覆盖的因素进行了逐步回归分析.结果 前方牵引治疗后,经过平均（2.71±0.77）年的随访,NA-PA减小了2.92°±3.52°（P＜0.05）、OJ减小了（2.83±3.83） mm（P＜0.05）;L1-TL、B-TL、Po-TL、分别增加了（1.38±4.22） mm,（1.29±4.85） mm,（1.79±5.18） mm差异均有显著性（P＜0.05）;随访期间前面高N-ME、前下面高ANS-Me及后面高S-Go分别增加了（5.33±3.11） mm（P＜0.01）、（5.42±2.61）mm（P＜0.01）和（5.25±3.79） mm（P＜0.01）;治疗结束两年后患者SNA、ANB、NA-PA、U1-Sn、Y轴角、下颌平面角仍较治疗前增加;L1-MP及OP-SN、UL-U1保持较治疗前减小水平;U1-TL、A-TL、OJ与治疗前相比分别增加了5.38±2.79（P＜0.01）、3.13±1.60（P＜0.01）、4.78±2.96（P＜0.01）;而L1-TL、B-TL、PO-TL、UL-EL在治疗后的随访期与治疗前无显著性差异.以随访时前牙覆盖的复发量（T2-T1）为因变量对前方牵引治疗前及治疗后变化量的（牙合）颌面形态测量值做自变量进行逐步回归分析,得出回归方程：OJ（T2-T1）＝20.43-1.172OJT1-T0—0.548 L1-T1T1-T0—0.229U6-PPT1-T0 （R2=0.969）.结论 唇腭裂术后反（牙合）患者前方牵引治疗后的复发主要来自下颌的继续生长,前方牵引产生的上颌变化基本稳定.     

单侧后牙反(牙合)髁突前伸运动轨迹的研究

目的:探讨单侧后牙反牙合髁突前伸运动轨迹的特征并比较与正常牙合之间的差异。方法:正常牙合5人,单侧后牙反牙合7人,采用计算机化的髁突运动轨迹Ⅰ型描记仪及分析软件,记录下颌最大前伸运动时髁突在水平面及矢状面上的运动轨迹。结果:单侧后牙反牙合者前伸后退运动轨迹多不重合,反牙合侧前伸髁道斜度明显大于对侧。结论:单侧后牙反牙合者存在前伸牙合干扰,其两侧颞下颌关节不对称。     

Evaluation of dehiscence and fenestration in adolescent patients affected by unilateral cleft lip and palate: A retrospective cone beam computed tomography study

Objective:To evaluate the presence of dehiscence and fenestration defects around anterior teeth in the cleft region and to compare these findings with the noncleft side in the same patients using cone beam computed tomography (CBCT).Materials and Methods:CBCT scans of 44 patients (26 males, 18 females; mean age, 14.04 ± 3.81 years) with unilateral cleft lip and palate (UCLP) were assessed to define dehiscences and fenestrations of the anterior teeth in both cleft and noncleft sides of the UCLP patients and a control group of noncleft patients (51 patients; 21 males, 30 females; mean age, 14.52 ± 1.16 years). Data were analyzed using Pearson’s χ² and Student’s t-test.Results:The prevalence of dehiscences at the maxillary central incisors, lateral incisors, and canines teeth were 43.2%, 70.6%, and 34.1% on the cleft side and 22.7%, 53.1%, and 27.3% on the noncleft side of UCLP patients, and 13.7%, 7.8%, and 13.7% in controls, respectively (statistically no difference between the sides of cleft patients). The cleft patients had a statistically significantly higher prevalence of dehiscences than did the controls on both the cleft and noncleft sides (P < .05), except for the maxillary central incisors. Fenestrations for these teeth were significantly more common on the cleft side in UCLP patients compared with controls (P < .05), whereas the difference for maxillary lateral incisors was not statistically significant.Conclusions:Patients with UCLP showed a higher prevalence of dehiscence and fenestration defects around the maxillary anterior teeth.     

儿童单侧后牙反患者下颌及颞颌关节的对称性研究

目的研究儿童单侧后牙反牙合患者下颌及颞颌关节的对称性。方法以26例替牙期单侧后牙反牙合患儿为试验组,28名正常牙合替牙期儿童为对照组,分别摄定位颏顶位片及双侧颞颌关节中位断层片进行比较。结果替牙期单侧后牙反牙合患儿在下颌骨坐标系中DMP点更靠颊侧。在颅底坐标系中,反牙合侧DMP点更靠远中,DMP、MM、DM点更靠颊侧。双侧髁突位置不对称、非反牙合侧关节前间隙减小,上后间隙均增大。结论相对于下颌坐标系,反牙合侧第一磨牙位置与对侧相比更靠远中及颊侧。在骨性结构上,未见下颌的不对称。试验组双侧髁突位置及关节间隙有差异,说明下颌发生功能性侧方移动。     

Three-dimensional assessment of palatal area changes after posterior crossbite correction with tooth-borne and tooth bone–borne rapid maxillary expansion: A randomized controlled trial with 5-year follow-up

ObjectivesTo assess and compare the three-dimensional treatment changes in palatal surface area and volume using either tooth-borne (TB) or tooth bone–borne (TBB) rapid maxillary expanders and to evaluate the long-term effects of the two devices and the incidence of the relapse between the groups.Materials and MethodsA total of 52 consecutive patients who met the eligibility criteria were recruited and allocated to either the TB group, mean age 9.3 years (standard deviation [SD], 1.3), or the TBB group, mean age 9.5 years (SD, 1.2). Study casts were taken before, directly after, 1 year after, and 5 years after expansion. Study casts were digitized, superimposed, and evaluated. Participants were randomly allocated in blocks of different sizes using the concealed allocation principle in a 1:1 ratio.ResultsChanges in palatal volume, palatal surface area, and palatal projection area within and between the groups up to 5 years after expansion followed the same pattern and did not show any statistically significant differences between the groups. Relapse was seen in 15% of the patients. It seemed that open-bite and a Class III growth pattern could be assumed as prognosis-deteriorating factors in regard to stability of the treatment.ConclusionsThere were no significant differences between the TB and TBB groups in palatal volume, palatal shell area, or palatal projection area directly after expansion or at 1 year and 5 years after expansion, which implies that the two devices gave rise to the same immediate and long-term outcomes.     

Kinesiographic study of the mandible in young patients with unilateral posterior crossbite.

It is generally assumed that children with posterior crossbites have abnormal mandibular movements; however, this assumption has not been clearly evaluated. The purpose of this investigation was to study the movements and the resting position of the mandible in 2 samples of 30 subjects, one aged 10 to 14 years with right posterior crossbite, the other aged 10 to 15 years with normal occlusion. Subjects in both groups exhibited a Class I skeletal relationship and mesofacial growth pattern. A mandibular kinesiograph was used to record both the mandibular resting position and dynamic movements. Mandibular movements were recorded during (1) maximum excursions (opening-closing, protrusion, right and left excursions), (2) swallowing, and (3) mastication. The results showed no differences between groups in the extension of the movements during closing and protrusion. However, crossbite patients exhibited a significant lateral shift during these movements. Right and left excursions were also similar between groups. The dimension of the freeway space was similar between groups, but the lateral shift found in centric occlusion was also present in the crossbite group when the mandible was at rest. The crossbite group more frequently showed a pattern of abnormal swallowing. No differences were found in any of the parameters studied during the masticatory cycle. There was no relationship between the side of the crossbite and the masticatory preference side. In conclusion, posterior crossbite patients showed a lateral shift in some movements that persisted when the mandible was at rest.     

3D evaluation of mandibular skeletal changes in juvenile arthritis patients treated with a distraction splint: A retrospective follow-up

Objective:To evaluate three-dimensional (3D) condylar and mandibular growth in patients with juvenile idiopathic arthritis (JIA) with unilateral temporomandibular joint involvement treated with a distraction splint.Materials and Methods:Cone-beam computed tomography (CBCT) scans were taken for 16 patients with JIA with unilateral TMJ involvement before treatment (T₀) and 2 years after treatment (T₁). All patients received orthopedic treatment with a distraction splint. Eleven patients without JIA who were undergoing orthodontic treatment without a functional appliance or Class II mechanics and who had taken CBCT scans before and after treatment, served as controls. Reconstructed 3D models of the mandibles at T₀ and T₁ were superimposed on stable structures. Intra- and intergroup growth differences in condylar and mandibular ramus modifications and growth vector direction of the mandibular ramus were evaluated.Results:In all patients with JIA there were asymmetric condylar volume, distal and vertical condylar displacement, and ramus length differences that were smaller on the affected side. Condylar displacement was more distal and less vertical in the JIA group than in the control group. A larger distal growth of the condylar head and a more medial rotation of the ramus on the affected side were found in the JIA group.Conclusion:The orthopedic functional treatment for patients with JIA allows for condylar adaptation and modeling, thereby hindering, although with a widely variable response, a further worsening of the asymmetry. Unilateral affection has a possible influence on the growth of the nonaffected side.     

A 3D cone beam computed tomography (CBCT) investigation of mandibular condyle morphometry: Gender determination,disparities, asymmetry assessment and relationship with mandibular size

ObjectiveCBCT (cone beam computed tomography) analysis of condyle morphometry, to investigate the gender differences, symmetry and relationship with mandibular size.Materials and methodsThis is a retrospective study. 800 CBCT scan obtained for the measurement of condyle in anterior-posterior and medio-lateral aspect using OnDemand 3D software. Participants were Saudi nationals of age above 18 years. 395 Males and 405 Females with the mean age of 38.2 ± 10.5 years. Right and left anterior-posterior width and medio-lateral width of the condyle were measured. Condyles were not isolated on the CBCT for volume measurement.ResultsMean right and anterior-posterior condyle width was 9.02 mm and 8.74 mm in males whereas in females it was 9.01 mm 8.69 mm respectively. For males mean medio-lateral width of the condyle in right and left side was 17.40 mm and 16.95 mm. For females, mean medio-lateral width of the condyle in right and left side was 17.14 mm and 16.93 mm. The prediction rate of gender was 57.2% for males and 53.3% for females. Statistically significant differences (p < 0.05) were found in the anterior–posterior and medio-lateral width of right and left condyles among males and females. Left anterior-posterior and medio-lateral width of average vs small mandible shows statistically significant difference (p < 0.05).ConclusionCondyle morphometry is a weak predictor for gender. Irrespective of gender, right and left condyle are asymmetrical in relation to condyle morphometry of anterior-posterior and medio-lateral aspect. Left mandibular condyle morphometry is different in relation to the mandible size.     

单侧下颌骨发育过度畸形咀嚼肌肌电活性的研究

目的：研究下颌骨发育性不对称畸形患者下颌骨附丽肌的功能状况,探讨该类畸形与咀嚼肌肌电活性的关系。方法：以１０例成年单侧下颌骨过度发育性不对称畸形患者为研究对象,通过肌电图仪测试双侧颞肌、咬肌、二腹肌在功能活动时的肌电变化,进行该类患者双侧咀嚼肌肌电活性比较;并以１０例正常下颌骨双侧咀嚼肌肌电活性作为对照。结果：在单侧下颌骨发育过度性不对称畸形患者中,双侧咀嚼肌的肌电活性具有显著差异,其双侧肌电活性     

安氏II类骨性下颌后缩患者Twin－Block矫治前后下颌骨变化的三维测量研究鄢

目的：观察安氏Ⅱ类下颌后缩病例Twin－Block矫治器治疗前后下颌骨的三维变化,探讨Twin－Block对下颌骨生长发育的影响。方法：替牙晚期、恒牙列早期安氏Ⅱ类骨性下颌后缩病例10例,采用Twin－Block矫治器矫治,矫治前、后拍摄CBCT,应用Mimics 17．0软件进行下颌骨三维重建后定点测量,SPSS 13．0软件进行统计分析。结果：矫治后下颌骨综合长度、下颌体、下颌升支长度增长明显,有统计学差异,但是髁突宽度及喙突长度无明显变化。结论：Twin－Block功能矫治可以促进安氏Ⅱ类骨性下颌后缩患者下颌骨长度及升支高度的增长。     

Three-dimensional analysis of molar compensation in patients with facial asymmetry and mandibular prognathism

Objective:To evaluate the characteristic transverse dental compensations in patients with facial asymmetry and mandibular prognathism and to compare features of dental compensations between two types of mandibular asymmetry using 3-dimensional (3D) cone-beam computed tomography (CBCT).Materials and Methods:Seventy-eight adult patients with skeletal Class I (control group; n  =  33; 19 men and 14 women) or skeletal Class III with facial asymmetry (experimental group; n  =  45; 23 men and 22 women) were included. The experimental group was subdivided into two groups according to the type of mandibular asymmetry: translation type (T-type; n  =  20) and roll type (R-type; n  =  19). CBCT images were acquired before orthodontic treatment and 3D analyses were performed.Results:The transverse dental distance was significantly different between the two groups only at the palatal root apex of the maxillary first molar (P < .05). In the experimental group, the first molar axes were compensated significantly on both arches except the maxillary nondeviated side. The vertical molar heights were different between the two groups only on the maxillary arch (P < .001). The R-type showed greater mandibular ramal length difference and menton deviation than the T-type (P < .001). In the R-type, transverse compensation of the maxillary first molars was more obvious than with the T-type, which resulted in canting in the maxillary occlusal plane.Conclusions:Mandibular asymmetry with prognathism showed a characteristic transverse dental compensation pattern. The mandibular asymmetry type influenced the amount and direction of molar compensation on the maxillary arch.     

Morphometric analysis of the mandibular fossa in dentate and edentulous patients: A cone beam computed tomography study

Statement of problemMandibular fossa roof thickness and lateral inclination could be associated with the presence of bone changes in the mandibular condyle in dentate and edentulous patients. However, literature regarding the relationship between the presence and absence of teeth and the morphologic features of the temporomandibular joint is lacking. This knowledge could provide a better understanding of changes affecting the correct functioning of the stomatognathic system.PurposeThe purpose of this clinical study was to assess the mandibular fossa roof thickness and lateral inclination in relation to sex, presence or absence of teeth, and bone changes in the mandibular condyle through cone beam computed tomography (CBCT).Material and methodsCBCT scans of 100 individuals (50 dentate and 50 edentulous) were evaluated in terms of mandibular fossa roof thickness and lateral inclination. Bone changes in the mandibular condyle were classified dichotomously in relation to osteophytes, erosion, sclerosis, and flattening. Differences were assessed with the Student t test, the chi-square test, and 2-way analysis of variance (ANOVA), with Tukey post hoc tests (α=.05).ResultsSex was not related to mandibular fossa measurements. Edentulous participants showed a higher mandibular fossa lateral inclination (P<.001) and lower roof thickness (P=.001) than dentate participants. When the association between bone changes in the mandibular condyle was evaluated in dentate and edentulous groups, only sclerosis showed a statistically significant association (P<.001). The 2-way ANOVA showed that the mandibular fossa roof thickness was lower in edentulous participants in the presence of flattening and erosion and that the mandibular fossa lateral inclination was higher in the presence of osteophytes, erosion, and sclerosis (P<.001). Among dentate participants, the mandibular fossa lateral inclination was higher in the presence of flattening (P=.024).ConclusionsMandibular fossa roof thickness and lateral inclination are not associated with sex. However, tooth absence and bone changes in the mandibular condyle are related to mandibular fossa measurements.     

Three-dimensional cone beam computed tomography definition of the anatomical subregions of the upper airway: a validation study

The exact boundaries of the upper airway subregions remain undefined. Consequently, anatomical limits vary greatly among different research groups and impede unbiased comparisons. The aim of this study was to provide clinical three-dimensional anatomical limits for the upper airway subregions, translate them into accurate and reliable cephalometric landmarks in cone beam computed tomography (CBCT) data, and validate the proposed measuring protocol. The upper airway of 40 normative individuals aged 23–35 years was evaluated with Dolphin Imaging^® software. An appropriate grey-scale threshold value was pre-calculated. After adapting specific head positioning and virtual orientation protocols, the volume and minimum cross-sectional area of the nasopharynx, oropharynx, and hypopharynx, as previously defined by the authors, were calculated. Intra- and inter-observer reliability was excellent for volumes and moderate for areas. The sexual dimorphism analysis revealed a significantly greater oropharyngeal volume, hypopharyngeal volume, and minimum cross-sectional oropharyngeal area in males than in females. In conclusion, the proposed subregion definition showed technical feasibility and statistical reliability, especially for three-dimensional calculations. The reliability of two-dimensional calculations may be increased with improved head positioning during CBCT scanning and subsequent virtual head orientation. Standardization of the proposed anatomical limits has the potential to homogenize upper airway subregion analysis and permit comparisons among future studies.     

Three-dimensional position of mandibular third molars and its association with distal caries in mandibular second molars: a cone beam computed tomographic study

Clinical Oral Investigations - To analyze the prevalence of distal caries in mandibular second molars (M2Ms) and its correlation with the three-dimensional position of mandibular third molars...     

Influence of skeletal class in the morphology of cervical vertebrae: A study using cone beam computed tomography

Objectives:To quantify the prevalence of cervical vertebrae anomalies and to analyze any association between them and skeletal malocclusions or head posture positions in the same study.Materials and Methods:Two hundred forty patients who were attending the Department of Orthodontics of the University of Valencia for orthodontic treatment were selected and divided into three groups: skeletal Class I (control group, 0° <ANB < 4°), Class II (ANB ≥ 4°), and Class III (ANB ≤ 0°) according to ANB Steiner angle. The morphology of the first five cervical vertebrae was analyzed with cone beam computed tomography to identify any anomalies. Intra- and interobserver error methods were calculated.Results:Dehiscence and fusion of one unit (both 23.3%) and partial cleft (11.7%) were the most frequent anomalies, while occipitalization was the least common (3.3%). Dehiscence anomaly was observed when the control group was compared with Classes II and III and partial cleft anomaly when Class I was compared with Class III. Furthermore, NSBa and ss-N-sm/ANB angles were associated with partial cleft anomaly, while NSL/NL angle and extended head posture were associated with fusion anomaly.Conclusions:Fusion, dehiscence, and partial cleft were the most frequent cervical vertebrae anomalies. Dehiscence and partial cleft were found to present statistically significant differences between Class I and Classes II and III. Cervical vertebrae anomalies and head posture were associated with fusion.     

Alveolar bone thickness and height changes following incisor retraction treatment with microimplants:: A cone beam computed tomography study

ObjectivesTo evaluate alveolar bone remodeling following incisor retraction treatment with microimplants and to examine the relationship between crown/root distal movement and thickness/height changes of the alveolus.Materials and MethodsA total of 24 patients (mean age, 19.29 ± 4.64 years) with bialveolar protrusion treated by incisor retraction with microimplants were included. The distances of the crown and root tip movements as well as the thickness (alveolar bone thickness [ABT]; labial, lingual, and total) and vertical level (vertical bone level [VBL]; labial and lingual) of the alveolar bone were assessed using cone-beam computed tomography images obtained before treatment (T1) and after treatment (T2). All T1 and T2 variables were compared, and further comparisons of alveolar bone changes were conducted between the two groups based on the distance of the crown (low-crown-movement and high-crown-movement groups) and root movements (low-root-movement and high-root-movement groups). To determine the correlation of the crown or root movement with the variables of alveolar bone changes, Pearson correlation coefficients were calculated.ResultsSignificant differences were found in all VBL and ABT variables after treatment in both jaws but not in total ABT. Based on the crown and root movements, alveolar bone change significantly differed between the root-movement groups, whereas there was no significant difference between the crown-movement groups. In addition, root movement showed significant correlations with the variables.ConclusionsRemarkable changes in the height and thickness of alveolar bone were found after microimplant-aided incisor retraction treatment in all groups except for total ABT. Root movement was significantly correlated with the alveolar bone changes.