非拔牙正畸治疗牙槽嵴高度变化的CBCT研究

［摘要］目的 采用CBCT评估非拔牙正畸治疗前后釉牙骨质界到牙槽嵴顶的高度变化情况。方法 选择安氏Ⅰ类错〖HT5”,7”〗牙〖KG-*3〗合〖HT5”〗畸形的患者30例,存在轻中度拥挤。正畸前后进行CBCT扫描影像。分别对每个患者的24颗牙齿从釉牙骨质界与颊侧(n=720)和舌侧(n=720)牙槽嵴顶之间的距离进行测量和对比分析。 结果 在1 440处测量中,正畸治疗前有130（9.0%）例,治疗后有199例（13.8%）釉牙骨质界到牙槽骨嵴顶的距离超过2 mm（牙槽骨开裂）。 结论 骨开裂在正畸治疗前的牙齿中占9.0%。正畸治疗后,釉牙骨质界与骨嵴顶的距离发生变化。     

Contribution of cone beam computed tomography to the detection of apical root resorption after orthodontic treatment in root-filled and vital teeth

Objective:To investigate whether root-filled teeth are similar to vital pulp teeth in terms of apical root resorption (ARR) after orthodontic treatment.Materials and Methods:An original sample of cone beam computed tomography (CBCT) images of 1256 roots from 30 orthodontic patients were analyzed. The inclusion criteria demanded root-filled teeth and their contralateral vital teeth, while teeth with history of trauma had to be excluded to comply with exclusion criteria. CBCT images of root-filled teeth were compared before and after orthodontic treatment in a split-mouth design study. Tooth measurements were made with multiplanar reconstruction using axial-guided navigation. The statistical difference between the treatment effects was compared using the paired t-test.Results:Twenty posterior root-filled teeth and their contralaterals with vital pulp were selected before orthodontic treatment from six adolescents (two boys and four girls; mean [SD] age 12.8 [1.8] years). No differences were detected between filled and vital root lengths before treatment (P  =  .4364). The mean differences in root length between preorthodontic and postorthodontic treatment in filled- and vital roots were −0.30 mm and −0.16 mm, respectively, without any statistical difference (P  =  .4197) between them.Conclusion:There appears to be no increase in ARR after orthodontic treatment in root-filled teeth with no earlier ARR.     

Root resorption diagnosed with cone beam computed tomography after 6 months and at the end of orthodontic treatment with fixed appliances

Objective:To investigate the prevalence of orthodontically induced root resorption after treatment and the correlation with resorption found after 6 months of treatment.Materials and Methods:One hundred fifty-six patients (11–18 years) treated with fixed appliances and extraction of four premolars were examined with cone beam computed tomography before treatment, after 6 months of treatment (n  =  97), and at the end of active treatment. The Malmgren Index was used to describe the degree of root resorption.Results:Severe root resorption (>2 mm, score 3) was found in 25.6% of the patients at the end of treatment. Extreme root resorption was found in one patient. Root resorption was seen more frequently in the maxillary incisor region. There was no correlation between the severity of root resorption after 6 months and the amount observed at the end of treatment. Furthermore, no correlation was seen between treatment duration and the severity of root resorption.Conclusions:Clinically significant resorption was diagnosed in 25.6% of the patients, but no correlations, either with the resorption seen after 6 months or with the length of treatment, were found. Radiographic examination after 3 to 6 months of orthodontic treatment is too early and will not reduce the number of patients who will have teeth with severe root resorption.     

Cone beam computed tomography evaluations of marginal alveolar bone before and after orthodontic treatment combined with premolar extractions

Using cone beam computed tomography (CBCT) we investigated the distance between the cemento-enamel junction (CEJ) and the marginal bone crest (MBC) at buccal, lingual, mesial, and distal surfaces of incisors to first molars in adolescents before (baseline) and after extractive orthodontic treatment (study end point). Patients with Class I malocclusion, crowding and an overjet of ≤ 5 mm were examined with a CBCT unit using a 60 × 60-mm field of view and a 0.125-mm voxel size. Large differences in marginal bone height were found at baseline, particularly between tooth surfaces. There was a slight correlation between age and CEJ-MBC distance. From baseline to the study end point, large bone-height changes among teeth and tooth surfaces could be seen. Lingual surfaces, followed by buccal surfaces, showed the largest changes. Eighty-four per cent of lingual surfaces of mandibular central incisors exhibited a bone-height decrease of > 2 mm. The bone-height decrease was larger at lingual surfaces in the mandible than in the maxilla, and larger in girls (mean=1.8 mm) than in boys (mean=1.5 mm). Fewer than 1% of proximal surfaces exhibited changes of > 2 mm. It is unknown whether the changes in marginal bone height are transitory. A high-quality CBCT technique may help to determine this by providing a deeper insight into the long-term side effects of orthodontic treatment.     

锥形束计算机体层摄影术在牙槽外科中的应用

牙槽外科为口腔颌面外科的一部分,但其不仅局限于颌面外科专业,而且涉及多学科的基础治疗方法。因此．牙槽外科手术越来越受到学者们的重视。锥形束计算机体层摄影术（CBCT）是当今最有前途和实用性的口腔颌面影像设备,它的应用给口腔颌面部疾病的诊断和治疗带来了革命性的变化,使口腔临床诊断变得更加容易、更加准确,其不仅克服了曲面断层片的局限,同时还避免了传统cT诸多不足．因而在牙槽外科中得到越来越广泛的应用。本文结合国内外最新研究成果．对CBCT的优势及其在牙槽外科各领域中的应用做一综述。     

慢性牙周炎基础治疗前后牙槽骨锥形束CT评价

目的 应用锥形束CT(CBCT)评价慢性牙周炎牙周基础治疗前后牙槽骨的改变.方法 选择重度慢性牙周炎患者30例,对牙周基础治疗前、后上颌前磨牙牙槽骨进行临床疗效观察及拍摄CBCT片,利用CBCT随机软件测量牙槽骨高度和相对骨密度变化.结果 重度慢性牙周炎基础治疗后,患者牙周袋探诊深度、附着丧失明显好转,较治疗前差异均有统计学意义(P＜0.05).牙槽骨密度升高差异有统计学意义(P＜0.05),牙槽骨吸收程度变化差异无统计学意义(P＞0.05).不同阅片者之间对牙槽骨密度及牙槽骨吸收状况的测量,一致性检测结果显示组内相关系数大于0.9,差异无统计学意义.结论 CBCT可用于重度慢性牙周炎牙周基础治疗前、后牙槽骨状态的评价,定点方法具有可行性和可重复性.     

锥形束CT在上颌窦内提升术中的应用

目的探讨锥形束CT(cone beam computed tomography,CBCT)在上颌窦内提升术中的应用价值。方法收集18例需上颌窦内提升行人工牙种植的患者,术前CBCT检查制定手术计划,术后CBCT检查评价上颌窦内提升效果及上颌窦黏膜情况。结果 18例患者平均骨高度为6.5 mm,上颌窦内未见囊肿等病变,3例存在冠状位骨间隔,提升后种植体尖端骨质情况可清晰显示,其中1例患者内提升后上颌窦底穿孔。结论 CBCT在种植术前评估及术后检查中具有良好的效果,能够清晰显示出上颌窦内部结构及术后种植体根尖区骨质情况,对于上颌窦穿孔的判断具有重要意义。     

Impact of orthognathic surgery on the prevalence of dehiscence in Class II and Class III surgical-orthodontic patients:: A cone beam computed tomographic study

ObjectivesThe objectives were to evaluate and compare the presence of bone dehiscence before and after orthognathic surgery.Materials and MethodsIn this retrospective study, 90 cone-beam computed tomography (CBCT) scans from 45 patients were evaluated. Class II (n = 23) and Class III (n = 22) orthodontic patients who were being prepared for orthognathic surgery were measured. CBCT scans were obtained about 30 days prior to (T0) and 6 months after (T1) double jaw orthognathic surgery. The distance between the cemento-enamel junction (CEJ) and the alveolar bone crest was assessed at the buccal and lingual surfaces of all teeth, on both sides and arches, except for the second premolars and the second and third molars. A total of 1332 sites were measured for Class II (644) and Class III (688) patients. The software used was OsiriX (version 3.3 32-bit). Data were compared with Wilcoxon and McNemar tests at the 5% level.ResultsBone dehiscence before surgery was present in 26% and 15% of the Class II and III groups, respectively. The presence of dehiscence increased to 31% in the Class II and 20% in the Class III patients after surgery (P < .05).ConclusionsThe prevalence of dehiscence increased slightly in Class II and Class III surgical-orthodontic patients after orthognathic surgery. Temporary vascular supply reduction and oral hygiene difficulties may explain these results; however, more studies are needed.     

应用锥形束CT诊断颞下颌关节骨关节病的探讨

目的探讨锥形束CT（cone beam CT，CBCT）在颞下颌关节骨关节病诊断中的应用前景。方法临床诊断为颞下颌关节骨关节病（炎）、不可复（可复）性盘前移位伴骨关节病患者共48例（96侧关节）。48例同时拍摄经咽侧位x线平片和CBCT，比较两种x线检查方法的病变检出率、医师判断的重复性和一致性。结果颞下颌关节骨关节病x线表现分为6型：髁突表面皮质骨模糊消失型（I型）、表面缺损破坏型（Ⅱ型）、髁突磨平型（Ⅲ型）、骨质硬化型（IV型）、骨质增生型（V型）、囊样变型（Ⅵ型）。CBCT的检出率分别为65．63％、37．50％、27．08％、31．25％、28．13％、1．04％；经咽侧位x线平片的检出率分别为52．08％、19．79％、32．29％、23．96％、12．50％、2．08％。对每一型病变的程度和范围，同一医师两次判断或不同医师之间，对I、Ⅱ型病变的评判，经咽侧位x线平片和CBCT均有高度的一致性，Kappa值大于0．60。结论除Ⅲ型外，CBCT对每一类型的病变均有很高的检出率，所显示的病变及其部位清晰、明确。CBCT清晰的病变影像、明确的病变部位和显示多层面病变的优势，使其有望成为颞下颌关节骨关节病判定病变程度、预后以及药物治疗后效果的定量评价手段。     

Root resorption diagnosed with cone beam computed tomography after 6 months of orthodontic treatment with fixed appliance and the relation to risk factors

Objectives:To investigate root resorption after 6 months of active orthodontic treatment and its relation to possible risk factors.Materials and Methods:Ninety-seven patients (10–18 years) with a Class I malocclusion and crowding treated with fixed appliance and premolar extractions were examined with cone beam computed tomography before and after 6 months of active treatment. The exposure covered all teeth from first molar to first molar in both jaws. The Malmgren index was used to evaluate the degree of root resorption. Irregular root contour (score 1) was seen in most teeth already before active treatment, and therefore resorptions were registered only as score 2 (<2 mm, minor resorption) or higher.Results:Minor root resorption was noted in 10% of the patients and severe root resorption, >2 mm (score 3) was found in four patients. Root resorption was more frequently seen in the upper jaw, especially the incisors. There was no statistically significant correlation of root resorption with any of the selected risk factors.Conclusions:After 6 months of treatment, clinically significant resorption was diagnosed in 4% of the patients, ie, in 96% of the patients the radiographic examination did not reveal any significant information. The selected risk factors did not have any impact on the amount of resorption after 6 months of active treatment.     

Apical root resorption due to orthodontic treatment detected by cone beam computed tomography

Objective:To determine the frequency of apical root resorption (ARR) due to orthodontic treatment using cone beam computed tomography (CBCT) in a sample of 1256 roots from 30 patients.Materials and Methods:All patients had Class I malocclusion with crowding. Of the 30 patients evaluated, 11 were boys and 19 were girls; their mean age was 13 years (11 to 16 years). Orthodontic treatment followed the nonextraction treatment. CBCT images were obtained before and after orthodontic treatment, and ARR was determined using Axial Guided Navigation of CBCT images.Results:All patients had ARR. No statistically significant association was found between resorption frequency, gender, and age. ARR was detected using CBCT in 46% of all roots that underwent orthodontic treatment.Conclusions:CBCT was effective for detecting in vivo even minimal degrees of ARR due to orthodontic treatment and allowed three-dimensional evaluation of dental roots and visualization of palatine roots of maxillary molars. The highest frequencies and the most significant ARR occurred in incisors and distal roots of first maxillary and mandibular molars.     

Evaluation of maxillary buccal alveolar bone before and after orthodontic alignment without extractions: A cone beam computed tomographic study

Objectives:To assess the changes in the maxillary buccal alveolar bone during alignment without extractions. Secondarily, to evaluate the changes in arch dimensions and buccolingual inclinations of teeth and to identify risk factors for bone loss.Materials and Methods:Twenty-two adolescents with crowded permanent dentitions were treated without extractions with Damon 3MX brackets. Cone beam computed tomographic scans were taken before treatment (T0) and after alignment (T1). Bone thickness (BT) and height from the cementoenamel junction to the alveolar crest (BH) were evaluated at the maxillary central incisors, second premolars, and buccal roots of first molars. Changes in all variables from T0 to T1 were assessed. Correlations between bone changes and initial bone thickness, initial arch widths, initial crowding, amount of expansion, amount of tipping, and amount of molar rotation were calculated.Results:BT decreased and BH increased significantly for the incisors and mesiobuccal root of the first molars. Arch dimensions generally increased together with tipping. Bone loss was correlated with crowding and amount of expansion in the premolar region. Initially thinner BT was correlated with greater apical migration of bone for the incisors.Conclusions:Nonextraction alignment with self-ligating brackets led to arch expansion associated with tipping of teeth. Expansion related to alignment resulted in horizontal and vertical bone loss at the incisors and mesiobuccal root of the first molars. Thinner BTs and more severe crowding before treatment increased the risk for buccal bone loss.     

Cone beam computed tomography-assisted treatment planning concepts

Computed tomography (CT) and cone-beam CT (CBCT) technology allows three-dimensional evaluation of each patient's individual anatomy. This article highlights the presurgical planning phase of dental implant procedures that benefit from lower dose CBCT technology so that educated treatment decisions can be accurately determined. Clinicians should gain an understanding of how each view can be individually significant, with unique levels of detail helping to provide a comprehensive overview of the patient's anatomic presentation. This article outlines the benefits of using CBCT technology for dental implant applications for increased accuracy and avoidance of potential surgical and restorative complications.     

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     

Precision,reproducibility, and accuracy of bone crest level measurements of CBCT cross sections using different resolutions

Objective:To evaluate the precision, reproducibility, and accuracy of alveolar crest level measurements on CBCT images obtained with different voxel sizes.Materials and Methods:CBCT exams were made of 12 dried human mandibles with voxel dimensions of 0.2, 0.3, and 0.4 mm. Bone crest level was measured directly on the mandibles with a digital caliper and on CBCT images. Images were measured twice by two examiners. Intra- and interexaminer precision and reproducibility were assessed using paired and t-tests, respectively. Accuracy was evaluated using t-tests.Results:Precision and reproducibility of bone crest level tomographic measurements was good for all voxel sizes evaluated. The images with 0.2-mm voxel size showed a decreased number of intraexaminer errors. A high accuracy for measurements of bone crest level was observed for all CBCT definitions, except for the mandibular incisors using the 0.4-mm voxel size.Conclusions:Precision and reproducibility of alveolar bone level measurements were good for various voxel sizes. CBCT images demonstrated good accuracy for 0.2-mm and 0.3-mm voxel sizes. The mandibular incisor region needs better resolution than that provided by 0.4-mm voxel size for bone crest level measurements.     

Correlation between facial growth patterns and cortical bone thickness assessed with cone-beam computed tomography in young adult untreated patients

BackgroundThe vertical facial growth pattern is one of the most important issue in the orthodontic diagnosis and treatment. Previous studies investigated the association between interdental bone thickness and facial divergence using mainly bidimensional analysis. When two-dimensional dental radiographic views are not sufficient for diagnosis and measurements, cone-beam computed tomography (CBCT) images should be used to assess the alveolar bone structure three-dimensionally and with high accuracy and reliability.The aim of the present study was to evaluate the correlation between alveolar bone thickness and facial divergence in young adults untreated patients using a three-dimensional method analysis with CBCT images.MethodsRecords of 30 untreated patients (mean age 16 ± 2 years) with Angle Class I and mild to moderate crowding were analyzed. Subjects were classified as hypodivergent (<39˚), normodivergent (41 ± 2˚), and hyperdivergent (>43°). according to the inter-maxillary angle between the sagittal maxillary plane (ANS-PNS) and the mandibular plane (GN-ME). The alveolar bone thickness measurements were taken for the buccal and palatal/lingual surfaces of maxillary and mandibular anterior teeth. Axial-guided navigation (AGN) was used to locate all landmarks using a specific software (Horos 3.0).ResultsThe statistical analysis showed a significant difference between the hypodivergent and hyperdivergent group regarding buccal bone height (P = 0.005), buccal apical bone thickness (P = 0.003) and palatal mid-root bone thickness (P = 0.006). Moreover, buccal bone height (P = 0.006) was found to be statistically significant different in normodivergent compared with hypodivergent individuals.ConclusionsFacial types were found to be correlated with alveolar bone thickness. The hyperdivergent subjects presented thinner alveolus bone in the anterior maxilla and at almost all sites in the mandible. Clinicians should be aware of the possibility of thin cortical bone plates in hyperdivergent patients, reducing antero-posterior movements to avoid fenestration and dehiscence.     

Evaluation of alveolar bone support around incisors in patients with unilateral cleft lip,alveolus, and palate in late mixed dentition using cone beam computed tomography

Objectives:To evaluate alveolar bone support around cleft-adjacent maxillary central incisors (U1) in patients with unilateral cleft lip, alveolus and palate (UCLAP) in the late mixed dentition and to investigate the correlation between the alveolar bone thickness (ABT) and tooth inclination.Materials and Methods:Cone beam computed tomography scans of 45 subjects with UCLAP (29 boys, 16 girls; mean age = 10.74 ± 1.08 years) were assessed. The distance between the cementoenamel junction (CEJ) and alveolar bone crest (AC), and the ABTs at 3 mm, 6 mm, and the apex were measured on the labial, lingual and distal surfaces of U1. The cleft and normal sides were compared using a paired t-test and Pearson''s χ² test. Pearson''s correlation was used to explore the association between the ABT and tooth inclination of cleft-adjacent U1 in the labiolingual and mesiodistal dimensions.Results:The CEJ-AC distances were significantly greater in cleft-adjacent U1 (P < .01), with more bone height reduction observed labially and distally (P < .001). The labial, lingual, and apico-distal ABTs were decreased on the cleft side (P < .01). A positive correlation was found between the apico-labial ABT and the labiolingual inclination (r = 0.568, P < .01).Conclusions:Patients with UCLAP have reduced alveolar bone support around the cleft-adjacent U1, and the apico-labial ABT tends to decrease with increasing lingual tooth inclination; however, the correlation was weak.     

Mutagenicity and cytotoxicity in patients submitted to ionizing radiation: A comparison between cone beam computed tomography and radiographs for orthodontic treatment

Objectives:To evaluate and compare mutagenicity (micronucleus) and cytotoxicity (karyorrhexis, pyknosis, and karyolysis) in exfoliated buccal mucosa cells of children following cone beam computed tomography (CBCT) or conventional radiograph exposure necessary for orthodontic planning.Materials and Methods:A total of 49 healthy children were submitted to CBCT or a conventional orthodontic radiographic protocol; they were divided into two groups based on exam: CBCT (n  =  24) and Radiographic Set (n  =  25) groups. The micronucleus test in the exfoliated buccal mucosa cells was applied.Results:There was not a statistically significant difference (P > .05) found between the number of micronucleated buccal mucosa cells (MNC) before and after exposure to radiation in either group, showing that neither group experienced a mutagenic effect. However, radiation did cause other nuclear alterations closely related to cytotoxicity, including karyorrhexis, pyknosis, and karyolysis, in both groups (P < .05). The CBCT group presented a greater increase in cell death than was noted in the Radiographic Set group (P < .044).Conclusion:According to the micronucleus test, mutagenicity was not induced by the CBCT or the conventional radiographs, but cytotoxicity was verified after these exams, especially after CBCT. That might have happened once the CBCT group received a greater radiation dose than the Radiographic Set group as a result of the protocols used in orthodontic planning for this study.