正畸患者切牙影像失真发生情况分析

目的研究正畸患者曲面体层片上的切牙影像失真发生情况,并分析其原因。 方法从中山大学附属口腔医院放射科影像数据库中选取500例正畸患者的曲面体层片和头影测量侧位片,所有曲面体层片均采用咬合杆投照,分别从切牙牙体影像放大、缩小、牙根变短、根尖模糊等评价指标分析上下颌切牙影像失真的发生情况,在头影测量侧位片上测量中切牙根尖-对颌切牙切缘的距离,探讨切牙影像失真发生的原因。采用SPSS 19.0统计软件对所得数据进行统计学检验。 结果500例患者中,切牙牙体影像正常者共417例,切牙牙体影像失真者共83例,影像失真发生率16.6%,其中切牙牙体影像放大17例、牙体影像缩小0例、牙根变短30例,牙根影像变短伴模糊36例。影像失真患者的根尖-切缘距离大于影像正常的患者,差异有统计学意义（F = 5 187.18,P = 0）;影像失真患者的覆盖值大于影像正常的患者,差异有统计学意义（F>477,P = 0）。 结论严重牙颌面畸形如反 、深覆盖是导致曲面体层片的切牙影像失真的主要原因之一。

Analysis of the incidence and reason of image distortion of incisors of orthodontic patients

ObjectiveTo study the incidence and reasons of image distortion of incisors on panoramic photography of orthodontic patients. MethodsThe panoramic and cephalometric photography of 500 orthodontic patients were evaluated retrospectively. All of the photography was gotten from the department of radiology, Hospital of Stomatology, Sun Yat-sen University and was taken with bite rod. The image amplifying, shrinking, shortening, and blurring were used as evaluation indicators to analyze the incidence of image distortion of upper and lower incisors. In order to explore the reasons of image distortion, the distance from the root apex of the incisor to the edge of opposite incisor was measured. The One-way ANOVA was used as statistic method to analyze the data with SPSS 19.0. ResultsThere were 417 patients who had normal incisor image, and 83 patients with incisor image distortion. The incidence of image distortion was 16.6%. There were 17 patients with amplified incisor image. None of the patient had image shrinking. There were 30 patients with shorten incisor image, and 36 patients with blurred image incisor. The distance from the root apex of the incisor to the edge of opposite incisor of the patients with incisor image distortion was significant greater than the patients with normal incisor image. The One-way ANOVA results shown that the F value was 5 187.18, P value was 0. The overjet of upper and lower incisors of the patients with image distortion was greater than the patients with normal incisor image. The One-way ANOVA results shown that the F value was larger than 477, P value was 0. ConclusionSerious dental and maxillofacial malformation such as serious anterior crossbite and deep overjet was one of the main reasons which caused the incisor image distortion on panoramic photography.