II級アマルガム修復における歯肉隣接部二次う蝕の視認性に関するX線写真学的検討

The radiographic investigation of the visibility of secondary caries adjacent to the gingiva in Class II amalgam restorations.

抄録

本研究の目的は、アマルガム修復した歯の歯肉頬側および歯肉舌側コーナーにおける二次う蝕の可視性を調査することである。歯列矯正で抜去した下顎前臼歯15歯に標準的なII級窩洞を形成し、無作為に3歯ずつ5群に分けた。そのうち4群では、修復物の歯肉側コーナーまたは歯肉頬側コーナーに1.0mmまたは1.5mmの窩洞を作製した。対照群である5群では病変は形成されなかった。歯はアマルガムで修復された。歯は、下顎小臼歯が1本欠損している15名のボランティアの実際の歯腔に適合させた。各患者のレントゲン写真を二等分角法とバイトウィング法で撮影した。これらのX線写真を無作為に分類し、う蝕の検出によく携わる教授陣15名と、普段はう蝕の検出に携わらない教授陣17名に配布した。バイトウィング法は、歯肉頬側近心角の二次う蝕の検出において、二等分角法よりも信頼性が高いことが判明した（P < 0.05）。また、グループ1では、歯肉側隅角部のう蝕の検出において、バイセクティングアングル法はバイトウィング法よりも信頼性が高いことが明らかになった（P < .05）。う蝕の検出に普段から携わっている教員とそうでない教員の間で、X線写真の正しい評価に有意差は認められなかった。

The aim of this study was to investigate the visibility of secondary caries in the gingivobuccal and gingivolingual corners of teeth restored with amalgam restorations. Standard Class II cavities were created in 15 orthodontically extracted mandibular premolar teeth, and the teeth were randomly divided into five groups of three teeth each. In four of the groups, a 1.0- or 1.5-mm cavity was prepared in the gingivolingual or gingivobuccal corner of the restoration. No lesions were created in group 5, the control group. The teeth were restored with amalgam. The teeth were adapted in the actual tooth space of 15 volunteers with one mandibular premolar missing. Radiographs of each patient were taken with the bisecting-angle technique and the bite wing technique. The radiographs were sorted at random and given to 15 members of the professoriate who were often involved in detecting caries and to 17 members who were not normally involved in detecting caries. The bitewing technique was found to be more reliable than the bisecting-angle technique in detecting secondary caries in gingivobuccal approximal corners (P < .05). It was also found that, in group 1, the bisecting-angle technique was more reliable than the bitewing technique in detecting caries in gingivolingual corners (P < .05). No significant differences were found in the correct evaluation of radiographs between the faculty who were normally involved in the detection of caries and those who were not.