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目的采用光学相干断层成像技术(optical coherence tomography,OCT)观察充填体下窝洞底壁人工酸蚀脱矿模型的成像特点。方法选用36颗牙面光滑、无釉质破损和色素沉着的人离体前磨牙,在牙冠颊面制备“长×宽”为“3 mm×3 mm”的,深度在0.6~1.0 mm的Ⅴ类洞,随机分为3组,每组12颗。实验A组窝洞底壁用格鲁玛酸蚀剂酸蚀2 min,实验B组酸蚀5 min,空白对照组不做酸蚀处理。各组样本牙窝洞均使用复合树脂充填,在充填前后采用OCT系统对窝洞底壁、充填体扫描成像,而后作充填后牙样本近远中向的X-ray投照平片观察窝洞底壁的酸蚀改变。结果充填前窝洞OCT扫描成像显示空白对照组未酸蚀底壁釉质光滑,在表面强反射亮带下可以看到清晰釉质、牙本质层散射信息和釉牙本质界;酸蚀实验组形成窝洞底壁的明显脱钙背向散射层。窝洞充填后OCT扫描成像显示充填体可完整成像;未酸蚀底壁则显示有清晰底壁反射亮带,酸蚀底壁为光信号吸收无显像,二者具有明显不同的成像特点。X-ray投照平片未能发现底壁部位釉质密度改变。结论 OCT可以对牙充填体及其底壁牙体组织成像,酸蚀脱矿的牙体底壁与未酸蚀者有明显不同的成像特点。该方法有助于判断充填体底壁早期继发龋的脱矿改变,与传统X-ray检测方法相比具有明显的优越性。
OBJECTIVE To observe the imaging characteristics of the artificial acid-etching ore demineralization model in the bottom wall of the lower cave by optical coherence tomography (OCT). Methods Thirty - six human premolar premolars with smooth, enamel - damaged and pigmented surfaces were prepared and their length, width and length were measured on the buccal surface of the crown of 3 mm × 3 mm, 1.0 mm class Ⅴ holes were randomly divided into three groups of 12 each. In experiment A, the bottom wall of the cave was etched with Glutamic acid for 2 min. The acidity of the test in group B was 5 min, while the blank control group was not acid etched. The dental casts of each group were filled with composite resin. Before and after filling, the OCT system was used to scan the images of the bottom walls and the fillers of the cavities, and then the orthopedic X-ray casts were used to observe the cavities The acidity of the wall changes. Results The OCT scan images of the foramen ovale before filling showed that the smooth enamel on the bottom wall of the control group was clear, and the enamel and dentin scattering information and enamel dentin boundaries were clearly visible under the bright reflection band on the surface. Clearly decalcified backscattered layer on the bottom wall of the cave. The OCT scan imaging of the foramina filling showed that the filling body can be completely imaged. The bottom of the acid-etched bottom wall shows clear bright reflection on the bottom wall, and the bottom wall of the acid etching is the optical signal absorption non-imaging. Both have distinct imaging features. X-ray cast plain film failed to find the bottom wall of the enamel density changes. Conclusion OCT can be used to image the dental arch and its bottom wall tissue. The bottom wall of acid-demineralized tooth is obviously different from the non-erodible ones. This method is helpful to determine the demineralization changes of the early secondary caries in the bottom wall of the filling body, which has obvious advantages compared with the traditional X-ray detection method.