Morphological changes in the pharyngeal airway of female skeletal class III patients following bimaxillary surgery: A cone beam computed tomography evaluation

Using cone beam computed tomography (CBCT), the present study compared three-dimensional (3D) changes in the pharyngeal airway and surrounding tissues in female skeletal class III patients treated with bimaxillary surgery. Twenty-nine female skeletal class III patients with both maxillary hypoplasia and a mandibular excess underwent bilateral sagittal split ramus osteotomy for mandibular setback combined with Le Fort I osteotomy for maxillary advancement. Volumetric measurements were performed using CBCT scans taken at 1 week presurgery and 6 months post-surgery. The oropharynx volumes and the cross-sectional area behind the soft palate decreased significantly. There was an insignificant change in the volume of the nasopharynx (P > 0.05). The hyoid bone moved downward and posteriorly after surgery. The morphology of the soft palate also changed dramatically, with an increase in the length and thickness. Negative correlations were found between the pharyngeal airway space and the position of the hyoid bone. The change in morphology of the soft palate was significantly correlated with the changes in hyoid bone position. These 3D results suggest that bimaxillary orthognathic surgery significantly changes the position of the hyoid bone and the soft palate together with a significant decrease in the pharyngeal airway space in the correction of skeletal class III malocclusion.     

Cervical vertebra morphology in different skeletal classes: A Three-Dimensional Computed Tomography Evaluation

Objective:To describe cervical vertebra morphology in subjects with different anteroposterior jaw relationships.Materials and Methods:Cone-beam computed tomography images of 31 female subjects aged 19 to 41 years were evaluated. Subjects constituted two groups according to the ANB angle: group 1, skeletal Class II (ANB angle >5); and group 2, skeletal Class III (ANB angle <1). Nine linear measurements and one angular measurement were used to assess the vertebral morphology. The Mann-Whitney U-test was used for statistical analysis.Results:The mean atlas dorsal arch height was significantly shorter in Class II subjects compared with those in Class III (P < .05). The cervical vertebra morphological analysis by cone-beam computed tomography was of comparable precision to three-dimensional computed tomography evaluations. This study confirmed previous findings that Class II subjects have significantly lower atlas dorsal arch heights.Conclusion:The height of the atlas dorsal arch of cervical vertebrae is affected by the anteroposterior skeletal pattern.     

Assessment of mini-implant displacement using cone beam computed tomography

Objectives: To assess, through cone beam computed tomography (CBCT), the mini‐implants' stability and behaviour when submitted to orthodontic force during upper molars' intrusion. Material and methods: Forty‐one mini‐implants were divided into two groups: 30 in the buccal and palatal mini‐implants group (BPMI), inserted into buccal and palatal sides, and 11 in the midpalatal mini‐implants group (MPMI), inserted into midpalatal suture. One day after insertion, a 200 gf was applied on the mini‐implants during a 5‐month period. CBCT was performed twice: before force application (CBCT 1) and 5 months later (CBCT 2). For mini‐implant displacement assessment, the distance of mini‐implants' head (HMI) and tail (TMI) to coronal, sagittal and axial planes was measured at CBCT 1 and 2. Results: For the BPMI group, the displacement rate was statistically significant (P<0.05) in all three dimensions for both the head and the tail. For the MPMI group, the displacement rate was statistically significant (P<0.05) only in the antero‐posterior (head and tail) and vertical (head) dimensions. Conclusions: Buccal, palatal and midpalatal mini‐implants showed some displacement (mean value ≤0.78) when submitted to force, although they are aimed to provide stable skeletal anchorage. To cite this article:
Alves M Jr, Baratieri C, Nojima LI. Assessment of mini‐implant displacement using cone beam computed tomography.
Clin. Oral Impl. Res. 22 , 2011; 1151–1156.
doi: 10.1111/j.1600‐0501.2010.02092.x     

上海地区少年儿童颈椎骨成熟度与手腕骨成熟度的相关研究

目的:通过评价上海地区少年儿童颈椎骨成熟度和手腕骨成熟度的相关性,探讨利用颈椎骨成熟度评判生长发育阶段的可行性。方法:样本包括上海地区170例5～18岁(男52例,女118例)正畸就诊患者。治疗前同期摄取左手腕掌指骨片和头颅侧位定位片,分别评价手腕骨成熟度和颈椎骨成熟度(手腕骨采用Grave和Brown法,颈椎骨采用Hassel和Farman改良分期法)。以SPSS11.0统计软件包进行相关性分析(Spearman法)。结果:颈椎骨成熟度和手腕骨成熟度具有高度相关性。男性组r=0.858(P<0.01),女性组r=0.882(P<0.01);男女合并r=0.918(P<0.01)。结论:在正畸治疗中,头颅侧位定位片上的颈椎骨成熟度可作为判断少年儿童生长发育阶段的可靠指标。     

Correlation of spheno-occipital synchondrosis fusion stages with a hand-wrist skeletal maturity index: A cone beam computed tomography study

ObjectivesTo examine the correlation between spheno-occipital synchondrosis fusion stages and the hand-wrist skeletal maturity index.Materials and MethodsDigital records of 164 individuals (77 males, 87 females) aged 10 to 18 years old were examined. Three-dimensional CBCT scans and hand-wrist two-dimensional radiographs were scored for the spheno-occipital synchondrosis fusion stages and hand-wrist skeletal maturity index, respectively. Statistical analyses were performed for associations using R software with a significance threshold of P< .01.ResultsA significant positive relationship was demonstrated between spheno-occipital synchondrosis fusion stages and hand-wrist skeletal maturity in both sexes. The Kendall''s rank correlation τ between hand-wrist skeletal maturity index and spheno-occipital synchondrosis fusion percentage were high and positive in males and females (r = .74 and r = .71, respectively).ConclusionsThe significant, positive relationship between the hand-wrist skeletal maturity index and spheno-occipital synchondrosis fusion stages support the idea of using spheno-occipital synchondrosis fusion as a biological indicator for craniofacial and mandibular growth spurt prediction.     

不同垂直骨面型尖牙区牙槽骨形态的锥形束CT研究

目的通过锥形束CT(CBCT)影像学分析,探讨不同垂直骨面型尖牙区牙槽骨形态结构的差异,为正畸临床治疗提供参考。方法选取正畸治疗前病例84例,以FMA角(眶耳平面-下颌平面角)大小为分组标准:FMA>32°为高角型,FMA<22°为低角型,FMA在22°～32°为均角型,通过CBCT获得颅颌面三维影像,测量右侧上下尖牙的牙槽骨高度、厚度及旋转角度,以单因素方差分析和LSD-t检验进行统计学分析。结果上尖牙牙轴与腭侧骨皮质的夹角、上尖牙根尖至腭侧骨皮质的距离、上尖牙旋转角度以及移动距离在三种垂直骨面型中差异有统计学意义(P<0.05),下尖牙牙轴与骨皮质的夹角及距离、下尖牙颊腭侧牙槽骨高度、下尖牙腭侧旋转角度和总旋转角度、下尖牙移动距离在三种垂直骨面型中差异有统计学意义(P<0.05)。结论不同垂直骨面型尖牙区的牙槽骨高度、厚度及旋转角度存在差异。     

Evaluation of condyle-fossa relationships in adolescents with various skeletal patterns using cone-beam computed tomography

Objectives:To evaluate the condyle-fossa relationship in adolescents with various skeletal patterns using cone-beam computed tomography (CBCT).Materials and Methods:CBCT images obtained in 120 adolescent patients were used for this study. The patients were divided into 3 groups according to 3 criteria: (1) age (early, middle, and late adolescence); (2) facial height ratio or Jarabak quotient (hyperdivergent, normodivergent, and hypodivergent); and (3) ANB classification (Class I, Class II, and Class III). Temporomandibular joint space (TMJS: AS, anterior space; SS, superior space; PS, posterior space; MS, medial space; LS, lateral space), width and depth of the condyle (MLT, mediolateral thickness; APT, anteroposterior thickness), articular slope (ArS) and vertical height of the fossa (VHF) were measured and compared using CBCT.Results:Differences in condyle-fossa relationships were not significantly different between male and female adolescents, but were significantly different (P < .05) between left and right sides. The mean values showed no statistical differences according to age and skeletal pattern. Most measurements in the sagittal view showed that SS was the greatest, and the mean ratio of AS to SS to PS was 1.00 to 1.27 to 1.19, respectively. The mean values of coronal MS and LS were not significantly different.Conclusions:There were almost no statistical differences in the TMJS in adolescents across various factors except between left and right sides.     

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头颅锥形束CT(CBCT)不仅能够提供便捷、准确的颅颌面三维影像,还具有扫描时间短、放射剂量小、费用低廉等优点,这使其近年来在正畸临床快速普及应用.本文结合我院CBCT临床应用的经验,对CBCT在正畸头影测量、埋伏牙、微种植体、气道测量、成人颞颌关节病及牙周病、正颌外科等方面的辅助诊断应用做一总结.     

Assessment of asymmetry in a normal occlusion sample and asymmetric patients with three-dimensional cone beam computed tomography: A study for a transverse reference plane

Objective:To characterize symmetrical features of patients with facial asymmetry and thus to find the most reliable horizontal reference lines easily used in three-dimensional images. The hypothesis was that there is a difference in the location of bilateral landmarks of the upper skull between the normal occlusion sample and skeletal Class III patients with asymmetry.Materials and Methods:Group 1 (normal occlusion sample) was composed of 20 Korean adults with normal occlusion and no noticeable asymmetry. Groups 2 through 4 were selected from patients who were diagnosed as skeletal Class III malocclusion and grouped according to the extent of asymmetry (group 2: symmetric mandible, no maxillary cant; group 3: asymmetric mandible, no maxillary cant; group 4: asymmetric mandible, more than 4 mm maxillary cant measured at maxillary first molars). Three-dimensional cone beam computed tomography images were taken before treatment, and bilateral landmarks of the skull were located and their vertical and horizontal differences compared.Results:No statistically significant difference was noted in the position of bilateral landmarks between groups, except for AG (P < .05). AG showed significant differences in vertical dimension (P < .001) and in horizontal dimension (P < .0001) between groups. The mean of the difference was clearly greatest at FM.Conclusions:The hypothesis is rejected. All groups had a similar pattern of asymmetry in the upper third of the face. Therefore, the transverse reference line of the bilateral Z or orbitale may be used even in patients with severe asymmetry of the maxilla with reference to the clinical photos.     

The relationship of vertical skeletofacial morphology to oropharyngeal airway shape using cone beam computed tomography: Possible implications for airway restriction

Objective:To determine if the shape of the oropharyngeal airway is related to the vertical morphology of the skeletofacial complex, including the hyoid bone.Materials and Methods:Cone beam computed tomography scans from 50 pretreatment adult orthodontic records were used to obtain skeletal and airway measurements. Linear regression statistics were used to compare soft tissue variables to hard tissue predictor variables.Results:Transverse airway widening was significantly increased when the distance between the hyoid and vertebrae was reduced; when the three-dimensional (3D) facial axis angle decreased (became more vertical); when the 3D mandibular plane angle increased; when the width of the hyoid increased, or when the calculated length of the geniohyoid decreased.Conclusions:A laterally elliptical airway—found when the face is more vertical and when the hyoid is closer to the cervical vertebrae—is hypothetically more resistant to collapse. Patients with a retrognathic, skeletal deep bite and a rounded oropharynx should be identified and corrected early to prevent potential airway problems.     

正常人群颞骨茎突的锥形束CT研究

目的研究正常人群颞骨茎突的形态,为临床诊断茎突综合征提供理论依据。方法挑选20~30岁无茎突综合征患者1000例(男女各500例),使用锥形束CT(cone beam computed tomography,CBCT)扫描,测量左右两侧颞骨茎突长度、体积、前倾角、内倾角,研究正常颞骨茎突的各项指标和特点。结果正常成人茎突的参数指标:双侧茎突长度分别为26.202±5.771mm和26.751±6.183mm (P>0.05);双侧茎突前倾角分别为31.721±4.495°和30.204±8.602°(P>0.05);双侧茎突内倾角分别为19.883±6.645°和22.605±6.334°(P<0.05);双侧茎突体积分别为202.966±13.826mm~3和224.489±14.746mm~3(P<0.05)。不同性别的双侧茎突长度与前倾角无明显差异(P>0.05),而双侧茎突内倾角和体积与性别有关(P<0.05)。结论 CBCT可清晰显示颞骨茎突影像,用于建立正常人群茎突的长度、角度、体积及对称性等参考数据,依此对临床诊断茎突综合征具有重要指导意义。     

Retrospective analysis of maxillary sinus septa – A cone beam computed tomography study

BackgroundSinus lift procedures have become a routine and reliable way to gain bone volume in the posterior maxilla for implant placement. The presence of an antral septum in the maxillary sinus increases the risk of complications and subsequent implant failure. This study was designed to estimate the prevalence of maxillary sinus septa and its correlation with age, sex, dentition status and the risk of perforating the Schneiderian membrane using cone beam computed tomography (CBCT).MethodsThis retrospective, cross-sectional study consisted of a total of 178 CBCT images (100 male, 78 female), 63.0% were dentate, 36.0% partially dentate and 1.1% edentate subjects with a mean age of 35 ± 45 years was analyzed to determine the prevalence, height, location, and orientation of maxillary sinus septa. The septa were classified according to the modified Al-Faraje’s classification into VII septal patterns, and the risk of perforation of the Schneiderian membrane was estimated. The chi-square test was used to compare categorical variables, and Student’s t-test and the Kruskal-Wallis test were used to compare continuous variables.ResultsSepta were present in 25.6% of the sinus segments (37.64% of the subjects). The mean septum height was 5.22 mm ± 2.06 in males and 6.27 mm ± 3.55 in females. The majority of septa were located in the middle 76.92%, while 4.40% were anterior, and 18.68% were posterior; 76.92% were in a buccopalatal direction, whereas 23.08% were in an anteroposterior direction. Class III was the most prevalent type. Overall, 60.4% had a moderate risk of membrane perforation, 30.8% had a low risk, and only 8.8% had a high risk.ConclusionThree-dimensional CBCT image analyses can be used as a diagnostic tool to provide accurate information that can help avoid unnecessary intra- and postoperative complications during sinus augmentation procedures by identifying the anatomic structures inherent to the maxillary sinus.     

Analysis of intensity variability in multislice and cone beam computed tomography

Objectives: The aim of this study was to evaluate the variability of intensity values in cone beam computed tomography (CBCT) imaging compared with multislice computed tomography Hounsfield units (MSCT HU) in order to assess the reliability of density assessments using CBCT images. Material and methods: A quality control phantom was scanned with an MSCT scanner and five CBCT scanners. In one CBCT scanner, the phantom was scanned repeatedly in the same and in different positions. Images were analyzed using registration to a mathematical model. MSCT images were used as a reference. Results: Density profiles of MSCT showed stable HU values, whereas in CBCT imaging the intensity values were variable over the profile. Repositioning of the phantom resulted in large fluctuations in intensity values. Conclusions: The use of intensity values in CBCT images is not reliable, because the values are influenced by device, imaging parameters and positioning. To cite this article:
Nackaerts O, Maes F, Yan H, Couto Souza P, Pauwels R, Jacobs R. Analysis of intensity variability in multislice and cone beam computed tomography.
Clin. Oral Impl. Res. 22 , 2011; 873–879.
doi: 10.1111/j.1600‐0501.2010.02076.x     

Application of cone beam computed tomography in facial imaging science

Facial imaging is used to study the facial shapeand its developmental changes over time.This isimportant to diagnose acquired malformations,to studynormal and abnormal growth and to differentiatebetween the results of treatment and normal growth,and to validate facial recognition.The two mainmethods to study and record facial imaging are bymeans of cephalometry and anthropometry[1].Cephalometrics is the scientific study of themeasurements of the head’s     

Volumetric changes of the upper airway following maxillary and mandibular advancement using cone beam computed tomography

The objective of this project was to retrospectively evaluate changes in volume of different compartments of the upper airway in response to maxillary, mandibular, and bimaxillary advancement surgeries and to predict the extent of volumetric changes associated with these surgical movements. Pre- and post-surgical cone beam computed tomography scans of 36 patients were evaluated for changes in nasal cavity, nasopharyngeal, oropharyngeal, and hypopharyngeal compartments. The amount of movement for each surgery was measured from skeletal landmarks to reference planes and was correlated with volumetric changes. Maxillary advancement of 4.0 ± 2.2 mm increased the oropharyngeal volume significantly (41.40%), and mandibular advancement of 3.8 ± 1.6 mm also significantly increased the oropharyngeal volume (21.17%). Bimaxillary advancement of 5.1 ± 1.3 mm for the maxilla and 6.4 ± 3.1 mm for the mandible significantly increased nasopharyngeal (27.45%), oropharyngeal (66.39%), and hypopharyngeal (52.48%) volumes. Furthermore, for every millimeter anterior movement, oropharyngeal volume increased by 2319.2 ± 771.8 mm³. Bimaxillary advancement showed a greater increase than isolated maxillary and mandibular advancement in all pharyngeal compartments. Every millimeter of advancement in the bimaxillary group led to a significant increase in oropharyngeal volume, while every millimeter downward movement showed a significant increase in nasopharyngeal volume.