充填体底壁人工脱矿的光学相干断层成像观察

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。?

Imaging of dental cavities bottom demineralized by artificial acid etching beneath restorations using Optical Coherence Tomography

Objective To analyse the imaging characteristics of artificial acid etching demineralization model of the dental cavities bottoms beneath the restorations using Optical Coherence Tomography（OCT）.Methods A dental cavity whose square was 3mm×3mm and depth ranged form 0.6mm to 1mm was prepared on each of 36 premolar teeth crown buccal surface without enamel breakage and pigmentation.All specimens were divided into three groups randomly with 12 in each group.The 1st group was experimental group A whose bottoms of prepared cavities were etched for 2 minutes by GLUMA etchants,and the 2nd group was experimental group B whose bottoms were etched 5 for minutes.The 3rd group was control group whose bottoms of prepared cavities were not etched.All specimen′s cavities were restorated by composite resin.Before restoration procedure the cavities bottoms of samples were imaged by OCT,and then all restorations were imaged too.Mesial-distal direction X-ray of each tooth sample in the three groups was carried out to identify the lesions on etching bottoms.Results OCT images showed that the information in enamel and dentinal layer and enamelo-dentinal junction could be seen clearly under the cavity′s smooth enamel bottom of control group.OCT imaging showed significant demineralized layer on bottoms of cavities were formed by acid etching.Composite resin restorations could be imaged completely by OCT which had clear bouncary with the enamel.OCT imaging of etched bottom beneath the restoration showed the characteristics of optical signal disappearance,and imaging of bottom without being etched showed clear reflecting light band.There were obviously different imaging characteristics on the bottom of the cavity benenath the restoration between the acid etching and contorl groups.No obvious changes of X-ray gray scale could be found at the bottoms beneath the restorations.Conclusions The composite resin restroations and the bottom of dental cavity beneath the restorations could be imaged by OCT.There were obviously different imaging characteristics on the bottoms of the cavities benenath the restorations between the acid etching and contorl groups.Compared with traditional X-ray OCT has apparent superiority.