固定正畸治疗上颌水平埋伏阻生尖牙28例分析

2003年2月~2007年2月,我们采用固定正畸治疗上颌水平埋伏阻生尖牙28例(30颗),疗效满意。现分析报告如下。1临床资料1.1一般情况28例(30颗)中,男10例,女18例;年龄11~19岁,平均17岁。其中唇侧阻生21颗,腭侧阻生9颗。本组病例均摄X线头颅定位侧位片、曲面断层片、定位牙矢状轴向断层片,以确定埋伏尖牙的唇腭向位,水平高度及倾斜度与邻牙关系,是否有萌出能力等。1.2治疗方法1.2.1矫正方案的确定唇向阻生尖牙多因间隙或牙弓长度不足而造成,常须手术及正畸减数治疗,以开创充足间隙[1]。腭侧埋伏阻生尖牙则主要是由于腭侧骨板过厚,骨皮质致密而阻碍尖牙萌出[2],故须正畸治疗才能萌出。外科暴露尖牙后,在尖牙上粘贴附件发挥矫治力,正畸治疗时使尖牙进入牙弓内。1.2.2牙槽外科开窗术牵引导萌术前参考定位投照X线显示的埋伏牙位置和形态,在局麻下行开窗导萌术,在上颌离埋伏牙最近的部位做定位标志。埋伏牙位于唇侧,切口从牙槽嵴开始,采用梯形切口,钝性分离,做唇侧翻瓣,充分开辟出埋伏牙的萌出通道。当所需间隙<3mm,可通过扩弓、减数推磨牙向远中的方法获得间隙,若间隙相差很大,则须拔牙。对唇侧阻生牙行黏膜瓣移位术...     

螺旋CT对上颌前部埋伏牙定位的应用及评价

目的　评价螺旋CT对上颌前部埋伏牙定位的应用价值。方法　对 16例疑上颌埋伏牙患者作上颌牙轴位螺旋CT扫描 ,应用螺旋CT的图像处理功能作多层面重建 (Multiplanarreformation ,MPR)和三维重建 (3dimensionalreconstruction ,3D) ,获得单纯牙体的任何平面、任何曲面的断层像。结果　 16例患者 ,11例埋伏牙位于腭侧 ,4例埋伏牙位于唇侧 ,1例埋伏牙牙根位于腭侧 ,而牙冠位于唇侧。中切牙 9例 ,侧切牙 1例 ,尖牙 6例。结论　螺旋CT对上颌埋伏牙的定位精确 ,能清晰显示上颌前部埋伏牙的形态、唇侧或腭侧位置、萌出方向及与邻牙关系 ,可作为上颌埋伏牙外科处理和正畸治疗的重要检查手段。     

固定矫治器矫治上颌尖牙腭侧埋伏阻生5例

上颌尖牙埋伏阻生是正畸临床中常见的错颌畸形．其发病率为0.92％～2．2％。据有关报道：白种人以上颌尖牙腭侧埋伏阻生较多见，而中国人以上颌尖牙唇侧埋伏阻生较常见．上颌尖牙腭侧埋伏阻生矫治难度大，传统的治疗方法是在局麻下拔除埋伏牙，用固定矫治器进行矫治或在缺隙处做固定或活动义齿进行修复。由于尖牙对美观及颌功能有重要的作用．在临床实践中，作者应用固定矫治器结合牙槽外科手术矫治上颌尖牙腭侧埋伏阻生获得满意疗效，现报道如下。     

腭侧与唇侧开髓路径的上颌中切牙三维有限元比较分析

目的 利用三维有限元分析的方法,比较腭侧与唇侧两种开髓路径的上颌中切牙力学性能的差异,研究牙体开髓路径对各层结构应力分布的影响,为设计优化及临床应用提供理论依据.方法 以螺旋CT薄层扫描的人离体上颌中切牙的影像数据为基础,采用Mimics及Abaqus软件辅助建立腭侧和唇侧开髓路径下的两组上颌中切牙三维有限元模型.100 N的模拟静态咬合力,与牙长轴呈45°的方向加载于牙冠腭侧面中1/3与切1/3交界处,比较分析两组模型牙体组织的位移值以及牙体组织的应力分布情况.结果 在模拟咬合力作用下,中切牙唇侧开髓方式的最大综合位移、最大唇腭向位移、最大垂直向位移以及最大近远中向位移均略小于腭侧开髓方式,尤其是最大唇舌向位移和最大垂直向位移更为显著,提示唇侧开髓方式对切牙的生物力学稳定性影响更小.腭侧开髓方式下的中切牙的最大Von Mises应力远大于唇侧开髓方式,而唇侧开髓方式下的中切牙Von Mises应力分布更为均匀.结论 上颌中切牙两种不同开髓路径的力学性能不一致,唇侧开髓应力性能更趋于合理.     

上颌骨大型牙瘤并含牙囊肿1例

病人,男,16岁。右上颌尖牙区骨质膨隆,摸之较硬实,无痛,大小约3 cm×3 cm,压迫右中切牙和右第一前磨牙根尖1/3处,尖牙未萌出,12牙位正常,松动I度,其牙冠解剖结构形态为乳牙。口腔曲面断层片显示膨隆牙槽骨内有成堆状高密度牙样物,密度不均匀,边界不清楚,上颌单尖牙位于阴影上部,单尖牙和高密度牙样物之间有一囊状阴影带,环尖牙周围有阻射白线,乳侧切牙上方可见另一高密度阻射影像,形状不规则。X线诊断为组合型牙瘤并含牙囊肿。于局麻下拔除乳侧切牙,口腔内右上颌单尖牙区开龈瓣,翻瓣后即可见颊侧隆起的菲薄骨壁,凿除骨壁后,可见到融合在一…     

多层螺旋CT对颌骨埋伏牙的定位价值

目的:探讨多层螺旋CT多平面重建(MPR)和容积再现(VR)技术对颌骨埋伏阻生牙和多生牙的定位价值.材料和方法:患者25例,男8例,女17例,平均14岁.常规口腔全景片和咬合片不能准确判断其埋伏阻生牙和多生牙的情况.对其进行上下颌骨横轴位薄层扫描,采用多平面重建(MPR)和容积再现(VR)技术重建图像.结果:25例共36颗埋伏阻生或多生牙.多层螺旋CT能准确显示颌骨内埋伏阻生牙及多生牙的数量、牙冠牙根形态、唇腭侧位置、萌出方向及与邻牙关系.结论:多层螺旋CT多平面重建(MPR)和容积再现(VR)技术的应用是颌骨埋伏牙定位的有效方法.     

颌骨牙列体层技术诊断埋伏阻生牙的实验研究

目的 评价颌骨牙列体层摄片在埋伏阻生牙定位中的价值. 材料与方法使用离体牙在干颅模拟临床常见埋伏阻生牙类型,进行全景片及颌骨牙体断层摄片,观测离体牙在不同位置与其体层片影像的关系. 结果 颌骨牙列体层摄片能提供直观的埋伏阻生牙在颌骨内位置的二维影像,包括阻生牙的形态,唇侧或腭侧位置,萌出方向及与邻牙的关系. 结论 对于埋伏阻生牙的放射影像学定位,可选择颌骨牙列体层摄片,临床可以作为骨内埋伏阻生牙外科处理和正畸治疗前的检查手段.     

CBCT应用于下颌低位阻生第三磨牙拔除术的临床研究

目的探讨CBCT研究下颌低位阻生第三磨牙拔除术相关解剖应用。方法对65例(84侧)拟行下颌低位阻生第三磨牙患者CBCT影像学资料进行回顾性分析,与全口曲面断层片比较并作相关统计学分析。结果经对比分析下颌低位阻生第三磨牙CBCT和全口曲面断层片后,对于相关解剖应用及风险的评估二者均具有统计学差异(P0.05)。结论 CBCT相较于全口曲面断层片能更精准更全面地分析下颌低位阻生第三磨牙解剖位置与评估手术风险。     

64层螺旋CT多平面重建技术对颌骨埋伏牙的诊断价值

目的：探讨64层螺旋CT多平面重建技术在颌骨内埋伏牙的定位及临床应用价值。方法：对38例临床疑似埋伏牙患者行牙列轴面螺旋CT容积扫描,应用容积再现（VR）、最大密度投影（MIP）、多平面重建（MPR）、齿科软件获得牙体表面立体图像及任意平面、曲面断层图像。结果：38例患者阻生中切牙10颗,侧切牙8颗,尖牙14颗,第三磨牙6颗,多生牙13颗。结论：64层螺旋CT能清晰显示颌骨埋伏牙的形态,唇腭侧关系及与牙列、邻牙的关系,无论对于正畸牵引还是外科手术都具有极为重要的临床意义和发展前景。     

6┐舌侧多生牙阻生1例

病人，女，28岁。右侧下颌后牙隐痛1年余。口腔检查：无缺牙，舌侧多生牙阻生。多生牙与6┐密贴，均无松动。牙冠类似双尖牙，牙尖向近中，舌尖向远中。全口牙[牙合]关系正常。X片见：6┐与多生牙重叠影，根尖、牙周未见异常，根尖部阴影疑是多生牙的牙根。在阻麻下拨除多生牙，多生牙根尖部膨大。在向舌侧挺松多生牙过程中，     

The assessment of impacted maxillary canine position with panoramic radiography and cone beam CT

Objective

The aim of this study was to correlate the position of impacted maxillary canines on panoramic radiography with cone beam CT (CBCT) and analyse the labiopalatal position of canines and root resorption of permanent incisors in CBCT according to the mesiodistal position of canines on panoramic radiographs.

Methods

This study was a retrospective radiographic review of 63 patients with 73 impacted maxillary canines. The mesiodistal position of the canine cusp tip was classified by sector location and analysed on 73 impacted canines from 63 panoramic radiographs. The labiopalatal position of the impacted canines and root resorption of permanent incisors were evaluated with CBCT. The sector location on panoramic radiographs was compared with the labiopalatal position of impacted maxillary canines on CBCT. The statistical correlation between panoramic and CBCT findings was examined using the χ² test and the Fisher''s exact test.

Results

Labially impacted canines in CBCT were more frequent in Panoramic Sectors 1, 2 and 3, mid-alveolus impacted canines were more frequent in Sector 4 and palatally impacted canines were more frequent in Sector 5. There was a statistically significant association between the panoramic sectors of the impacted canines and the labiopalatal position of the canines (p < 0.001). Root resorption of permanent incisors showed a significant difference according to sector location (p < 0.001) and was observed in Sectors 3, 4 and 5.

Conclusions

This study suggests that the labiopalatal position of impacted canines and resorption of permanent incisors might be predicted using sector location on panoramic radiography.     

Clinical evaluation of the effects of radiographic distortion on the position and classification of mandibular third molars

OBJECTIVE: Panoramic radiographs are routinely employed for surgical planning of unerupted third molars. The objective of this study was to evaluate distortions in the position of mandibular third molars on panoramic radiographs. MATERIALS AND METHODS: Panoramic radiographs of 14 patients with indication for extraction of the mandibular third molars were used. Transurgical impressions of the crowns of the teeth to be extracted and adjacent second molars (n=19) were achieved with addition silicone and poured with type IV plaster for comparison of the inclinations of the third molars on the radiographs and study casts. RESULTS: There was a mean difference of -5.37 degrees between the position of the third molar on the panoramic radiograph and on the study cast (standard deviation 1.46, P<0.05, Student's t-test). CONCLUSION: There is distortion in the position of teeth on the panoramic radiograph, which may influence the surgical planning; however, this does not invalidate it as the main tool for diagnosis and surgical planning of mandibular third molars.     

Horizontally root fractured teeth with pulpal vitality - two case reports

This case study reports the successful outcome of horizontal root fractures of two different patients, which took place in permanent incisors. Report 1 describes a case of a 29-year-old patient who suffered a mandibular trauma affecting mainly the lower central incisors, caused by a car accident. A panoramic radiograph was taken right after the accident and showed a horizontal root fracture in the middle third of tooth 42, which went untreated. Report 2 illustrates a case of a 17-year-old male patient who searched for orthodontic therapy and the periapical radiograph showed horizontal root fracture in tooth 11 caused by a previous trauma, which went untreated as well. There was healing through the reestablishment of pulp activity and dental coloration without professional intervention.     

Marginal bone in periodontal disease: an evaluation of image quality in panoramic and intra-oral radiography

Five observers assessed the panoramic and full-mouth (14 periapical and four posterior bitewing) radiographs of 20 patients each for the ability to interpret and measure the marginal bone level. The image quality of each site was classified as excellent, acceptable or unacceptable. Depiction errors affecting interpretability and measurability were also noted. In the upper arch, the frequency of uninterpretable and non-measurable sites was almost equal for panoramic and periapical radiography. Image quality was better with periapical radiography in the lower arch. In the posterior regions of both arches, more sites could not be measured from panoramic compared with bitewing radiographs. Due to overlapping the distal surface of the maxillary canine and the mesial surface of the first maxillary premolar could often not be interpreted in either panoramic or periapical radiographs, but infrequently in the bitewings. In the lower arch, the most frequent depiction error was inadequate density in the incisor region of panoramic radiographs. On the basis of these results, we proposed that in clinical practice the panoramic radiograph can be supplemented with individually selected periapicals. In epidemiological studies, the panoramic radiograph should be combined with a premolar bitewing radiograph.     

Comparison of methods for localization of impacted maxillary canines by panoramic radiographs

Objectives:

The objective of this study was to compare three methods for localization of impacted maxillary canines using only conventional panoramic radiographs.

Methods:

The panoramic radiographs of 94 patients (102 impacted maxillary canines) were reviewed and evaluated using the methods magnification, angulation and superimposition. The actual positions of them were decided with cone beam CT images. The predicted positions of impacted canines from the magnification and angulation methods were compared using the McNemar χ² test. Sensitivity, specificity, accuracy, positive-likelihood ratio and negative-likelihood ratio were calculated. The canine-incisor index values and α angles of palatally and bucally non-rotated impacted canines were compared using the Mann–Whitney U test.

Results:

The statistical analysis revealed that there was a significant difference between the magnification and angulation methods (p < 0.01). Using the magnification method, 68.00% of buccal canines and 69.57% of palatal canines could be localized correctly. The results of the angulation method were 28.57% and 84.91%, respectively. The sensitivity of the angulation method for buccal canines was very low. In the superimposition method, 82.98% of the superimposing samples were palatal.

Conclusions:

The magnification and angulation methods were not reliable methods for locating the impacted canine with a single panoramic radiograph. Magnification was more successful than the angulation method. Further research is needed on the magnification method. The image superimposition method could be used as an adjunct to others.     

Possibilty of the lower third molar eruption--radiographic analysis

BACKGROUND/AIM: To assess the possibility of the eruption of the lower third molar on the basis of the measured parameters: retromolar space, mesiodistal crown width of a molar and the third molar angulation. METHODS: The investigation included 104 patients both sexes (43 boys, and 61 girls), 16 to 25 years old (mean age, 18 years). It was performed using the orthopanthomographic radiographs analysis of those patients. Each radiograph was covered by tracing paper, and the contoures of the following anatomic details were drawn: a) the crown and root contours of third molars, upper and lower central incisors, distal molars in occlusion, anterior edge of ramus mandible, b) lines: 1. the occlusal plane, 2. the line of retromolar space, 3. the mesiodistal crown width of third molar, 4. the axial shaft of the third molar and the distal angle between occlusal plane and the axial shaft of the third molar. The values were measured with an orthodontic caliper: the diameter of retromolar space, diameter of mesiodistal width, the value of distal angle between occlusal plane and axial shaft of molar. RESULTS: A favourable angulation of the lower third molar (more than 60 degrees) was found in, boys (left 27.90%, right 32.55%), girls (left 39.34%, right 37.77%). A favourable relationship between the diameters of mesiodistal width of the third molar and retromolar space was found in, boys, (left 13.59%, right 16.27%), girls, (left 8.19%, right 14.75%). A favourable relationship between the diameters of mesiodistal width of the third molar and the retromolar space and the angulation was found in boys, (left 9.30%, right 11.62%), girls, (left 6.56%, right 9.83%). CONCLUSION: There was not any statistically significant difference found between the relation of the retromolar value, third molar mesiodistal diameter, or of the third molar angulation to the left and the right side nor of their mutual relations in comparing boys and girls. A favourable prognosis was found in 9.33% of the patients.     

Narrowing of the inferior dental canal in relation to the lower third molars

OBJECTIVES: To assess narrowing of the inferior dental canal in the lower third molar regions using computed tomography (CT) and to determine the value of radiographic markers on rotational panoramic radiographs in assessing the true relationships of the inferior dental canal. METHODS: Patients referred for CT assessment of impacted lower third molars were used in this study. The lower third molars were assessed using CT to determine the position and morphology of the inferior dental canal relative to the roots and the cortical plates. The radiographic markers on rotational panoramic radiographs were correlated with the CT findings when rotational panoramic radiographs were available. RESULTS: The patients referred had 202 lower third molars. Inferior positioning of the inferior dental canal was the most common location on CT. Narrowing of the inferior dental canal was found in relation to the lower third molars in 66.8% of cases. The chance of narrowing of the inferior dental canal as shown using CT increased when at least one of the radiographic markers, superimposition, narrowing, deviation or reduction in density was present on the rotational panoramic radiograph. Deviation of the inferior dental canal on rotational panoramic radiographs was found to be the most significant predictor of narrowing of the inferior dental canal and a close relationship to the roots, as shown in CT. CONCLUSIONS: Narrowing of the inferior dental canal is a common finding when impacted lower third molars are assessed using CT. On rotational panoramic radiographs deviation of the inferior dental canal is the best predictor of narrowing of the inferior dental canal and a close relationship to the roots.     

Incidence of canine impaction and transmigration in a patient population

In this study, 4500 consecutive panoramic radiographs were prospectively reviewed. The incidence of canine impaction was found to be 3.58% and the incidence of canine transmigration was 0.31%. There were six maxillary and eight mandibular transmigrant canines. The incidence of impacted canine teeth and transmigration of maxillary and mandibular canines may be more frequent than was previously thought, at least in some populations.     

Value of x-ray computed tomography in topographic exploration of an impacted maxillary third molar

A case report of impacted maxillary third molar illustrate the limits of panoramic radiograph in topographic approach of Higmore Antrum. The CT scan in duplicate incidence appears in this case like indispensable complement to the standard X-Ray. It accurates the impacted localisation and the proceeding in the surgical treatment.