CBCT assessment of alveolar buccal bone level after RME

Objective:To evaluate the maxillary alveolar buccal bone levels after expansion with banded and bonded expanders, using cone-beam computed tomography (CBCT).Materials and Methods:The population sample consisted of 22 patients who required expansion during their comprehensive treatment; 10 patients (five males and five females) with a mean age of 13.5 years (CVMS 3) had bonded hygienic expanders, and 12 (six males and six females) with a mean age of 12.6 years (CVMS 3) had banded hyrax expanders. CBCT was taken both before (T1) and 6 months after last activation (T2). Measurements were made for buccal bone thickness (BT), buccal marginal bone level (MBL), and bone thickness level (BTL) at the right first molar (M_Rt), left first molar (M_Lft), right first premolar (PM_Rt), and left first premolar (PM_Lft). A mixed-design analysis of variance assessed differences between and within the groups. Post hoc t-tests were completed on significant analysis of variance results to determine where differences occurred.Results:Analysis of variance revealed no significant differences between or within the two groups. BT significantly decreased horizontally following rapid maxillary expansion. The amount of bone lost was −0.59 mm M_Rt, −0.72 mm PM_Rt, −0.50 mm M_Lft, and −0.57 mm PM_Lft (P < .003).Conclusions:There was no significant difference between or within the two groups. Buccal bone loss in the vertical dimension (MBL) only showed significance in the banded group for M_Rt (0.63 mm) and PM_LFt (0.37 mm) as evidenced by the paired t-test (P < .05).     

Three-dimensional changes of the hyoid bone and airway volumes related to its relationship with horizontal anatomic planes after bimaxillary surgery in skeletal Class III patients

Objective:To evaluate longitudinal changes of the hyoid bone position and pharyngeal airway space after bimaxillary surgery in mandibular prognathism patients.Materials and Methods:Cone-beam computed tomography scans were taken for 25 mandibular prognathism patients before surgery (T0), 2 months after surgery (T1), and 6 months after surgery (T2). The positional displacement of the hyoid bone was assessed using the coordinates at T0, T1, and T2. Additionally, the volume of each subject''s pharyngeal airway was measured.Results:The mean amount of posterior maxilla impaction was 3.76 ± 1.33 mm as the palatal plane rotated 2.04° ± 2.28° in a clockwise direction as a result of bimaxillary surgery. The hyoid bone moved backward (P < .05, P < .001) and downward (P > .05, P < .05) at 2 months and 6 months after surgery, while the total volume of the pharyngeal airway significantly decreased at the same time points (P < .001, P < .001). There was significant relationship between the changes of the hyoid bone position and airway volume at 2 months after surgery (P < .05). The change of the palatal plane angle was positively correlated to the decrease in the total airway volume (P < .001).Conclusions:The null hypothesis was rejected. The hyoid bone moved inferoposteriorly, and the pharyngeal airway volume decreased for up to 6 months after bimaxillary surgery. The decrease in the pharyngeal airway volume was correlated to the changes in the palatal plane inclination and the positional change of the hyoid bone.     

Location and Dimensions of the Mental Foramen: A Radiographic Analysis by Using Cone-beam Computed Tomography

Introduction

The mental foramen (MF) is an important landmark in dentistry. Knowledge of its position is central to perform block anesthesia of the mental nerve or to avoid nerve damage during surgical procedures in the premolar area of the mandible. The present radiographic study aimed at evaluating the location and dimension of the MF and measuring distances to neighboring structures by using limited cone-beam computed tomography (CBCT).

Methods

Sagittal, axial, and coronal CBCT images of 142 patients (26 bilateral and 116 unilateral cases) were retrospectively screened to determine the location of the MF with respect to adjacent teeth and to take linear measurements of the size of the MF and its distances to the upper and lower borders of the mandible. In addition, the course and angulation of the mental canal exiting the MF were assessed.

Results

The majority of MF (56%) were located apically between the 2 premolars, and another 35.7% of MF were positioned below the second premolar. On average, the MF was localized 5.0 mm from the closest root of the adjacent tooth (range, 0.3–9.8 mm). The mean size of the MF showed a height of 3.0 mm and a length of 3.2 mm; however, individual cases showed large differences in height (1.8–5.1 mm) and in length (1.8–5.5 mm). All mental canals exiting the MF demonstrated an upward course in the coronal plane, with 70.1% of the mental canal presenting an anterior loop (AL) in the axial view. The mean extension of AL in cases with an AL was 2.3 mm.

Conclusions

This study is consistent with previous radiographic studies regarding size and location of MF and distances between MF and adjacent anatomic structures. The assessed bilateral cases showed a high intraindividual concordance for certain features when comparing right and left sides.     

锥形束CT诊断颌面部异物1例

<正>张口受限为颌面外科的常见疾患,但颌面部异物引起张口受限多为个案报道[1-3]。准确定位异物位置及其形状大小,是外科手术取出异物,保证手术成功的关键。锥形束CT(cone beam computed tomography,CBCT)因其独特的三维成像特点,可以精确定位,更好地引导外科手术的顺利进行[4-6]。现对我院收治的1例颌面部异物引起的张口受限患者的临床资料进行报道,并结合文献回顾对CBCT在颌面异物诊断中的应用价值进行讨论。     

CBCT结合显微超声技术处理根管内折断器械的临床研究

目的：评价锥体束CT（CBCT）结合显微超声技术处理根管内折断器械的临床疗效。方法：选取济宁医学院附属医院口腔科2012年9月～2013年6月初次根管治疗中出现的器械折断病例24例,对患牙CBCT扫描,进行三维重建,对折断器械的根管进行三维定位及评估,制定临床决策,实施断械取出,计算取出率。结果：CBCT能准确定位断械所在根管,清晰显示根管形态、弯曲度、折断器械位置及周围牙本质厚度。24例断械病例中,20例选择取出治疗,其中16例成功取出,4例未能取出,成功率为80％。4例因折断器械均位于根尖部,弯曲根管下段,且周围牙本质薄弱不选择取出治疗。结论：CBCT结合显微超声技术为临床上评估及取出根管内器械折断病例提供了有效方法。     

Analisi della morfologia radicolare e canalare di molari superiori ed inferiori in una popolazione Caucasica: studio in vivo alla CBCT

AimTo investigate the root and canal morphology of maxillary and mandibular permanent molar teeth in a Caucasian population by using Cone Beam Computed Tomography (CBCT).MethodsA total of 596 permanent molars were included. The number of roots, the number of canals per root and the root canal configurations according to the method of Vertucci were recorded.ResultsAlmost all of maxillary first molars (95.7%) had three separate roots; however, 40.3% of mesiobuccal roots had two canals (MB2). Of 157 maxillary second molars, 88.5% had three roots. Among the mesiobuccal roots, 15.1% had two canals. The majority of mandibular molars (100% of first molars, 89.4% of second molars) had two separate roots. Most distal roots had a simple type I configuration, whereas mesial roots had more complex canal systems, with more than one canal.ConclusionsCBCT is an efficient method of studying root canal systems.     

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口腔影像学是口腔正畸学诊断的重要依据。锥形束CT（CBCT）的临床应用使正畸诊断从二维时代走向了三维时代。CBCT对于正畸治疗方案设计、治疗后的预测以及治疗效果的评价等具有重要的作用。     

锥形束CT与根尖片对牙根纵裂诊断的对比研究

目的:比较锥形束CT(CBCT)和X线根尖片在牙根纵裂诊断中的准确度,探讨CBCT对牙根纵裂诊断的价值。方法:选取临床检查中疑似牙根纵裂患牙50例,分别进行X线根尖片、CBCT检查诊断和外科手术诊断;对X线根尖片和CBCT对牙根纵裂的诊断结果进行统计分析。结果:CBCT诊断牙根纵裂的敏感度(83.33%)高于X线根尖片诊断牙根纵裂的敏感度为(47.61%),P<0.05。结论:CBCT比X线根尖片能更准确诊断牙根纵裂,有助于牙根纵裂诊断。     

多来源颅颌面三维数字化模型的建立

目的 建立一个满足临床和科研要求的可视化的多来源多精度的颅颌面三维数字化模型.方法 采用锥体束断层CT(CBCT)扫描整个头部,利用不同组织的亨氏单位(Houns Field值)的不同,提取出面部软组织、颌面部骨骼以及牙列3种组织结构,利用三维重建的方法,重构出面部、颌骨和牙齿三部分的数字化三维模型,同时采用激光扫描的方法获得带有纹理信息的面部三维模型以及高精度三维数字化牙列模型,利用三维图形学中的配准技术,将激光扫描获得的面部、三维模型转化到CT来源的重建的三维颅颌面数字化模型所在坐标系.结果 获得一个带有颜色信息的面部软组织、高精度牙列和清晰骨骼的复合三维数字化颅颌面模型.结论 多来源的三维数字化颅颌面模型是一种能够达到临床和科研要求的高精度数字化模型.