One hundred extracted molar teeth with discoloured fissures but without any visible carious cavitation were selected from a large supply, using standardized criteria. The teeth were mounted, placed on a mechanical balance, and probed with a force of 500 g in every fissure, at as many places as possible. Every time the probe was found to stick, the spot was marked. After probing colour slides were made of the occlusal faces. Subsequently, the crowns were embedded in epoxy resin. 700 μm thick sections were cut in a facial-lingual direction with a diamond wheel. From the sections X-rays were taken which were scored as follows: a measuring grid was placed on the X-ray image of a section, and the caries score (0-4) for every millimetre was determined. By scoring every section of a tooth in this way, an overview was obtained of the location of all caries lesions in the occlusal surface. By comparing this overview with the colour slide of the tooth, the relationship between the sticky spots and the lesions was visualized. The results indicate that only 24% of the caries lesions were discovered by probing for stickiness (low sensitivity), but that the probe seldom stuck in a sound fissure (high specificity, > 99%). Probing proved to be unreliable for the diagnosis of fissure caries.

Grey discolouration of the enamel around a filling and marginal fracture are often reasons to replace restorations due to suspicion of secondary caries. The aim of this study was to establish the validity of grey discolouration and marginal fracture for the diagnosis of caries at the enamel-dentine junction (EDJ) next to an amalgam filling. The occlusal surfaces of 161 extracted molars with occlusal amalgam fillings were photographed on colour slides, from which grey discolourations and marginal fracture were recorded. The size of the fracture was scored using a modified Mahler scale with six categories: score 1 = no marginal fracture ( < 30 μm), score 6 = fracture width > 200 μm. Secondary caries at the EDJ was scored on radiographs of 700 μm sections of the molars. Both radiolucencies and radiopacities in dentine were scored as caries. The sensitivity of grey discolouration for detection of secondary caries was 50% and the specificity 91%. The positive and negative predictive values were 71 and 80%, respectively. Marginal fracture was evaluated at five different levels of severity. Although there was caries present more frequently at the EDJ under severely fractured margins, marginal fracture was found of little diagnostic value at all levels. Only marginal fracture at threshold level V provided a positive predictive value (50%), which was significantly higher than the caries prevalence (31%). It is concluded that width of marginal fracture, as defined by the Mahler scale, has hardly any value for the diagnosis of secondary caries. However, grey discolouration may be a useful diagnostic aid.

Many clinicians take for granted that occlusal caries which is just visible as a cavity is extended (deep) into the dentine. This study was aimed at quantifying this opinion. The study was carried out with 60 molars containing small but visible occlusal cavities. After taking bite-wing radiographs the crowns were separated from the roots and embedded. 700-μm sections were cut and glued on plastic sheets. X-ray pictures were taken of the sections which were scored by independent examiners. The bite-wings provided inaccurate estimates of the extent of caries. Radiographs of the sections revealed that about 25% of the molars had caries which reached just to the dentino-enamel junction, while the remaining 75% showed caries extending far into the dentine.

This investigation was carried out to establish the validity of bite-wing radiographs for the diagnosis of secondary caries in teeth with occlusal amalgam restorations. One hundred and fifty-nine extracted molars with occlusal amalgam fillings and characteristics that might be indicative of the presence of secondary caries were selected. The characteristics were a blueish-gray discolouration of enamel, a brownish discolouration of the amalgam-enamel margin, marginal breakdown of the restoration, and/or deep fissures at the margin of the restoration. The teeth were radiographed in a bucco-lingual direction to obtain images comparable to bite-wings. Subsequently, the crowns were sectioned (700 μm) and glued on plastic sheets. The sections were recorded radiographically and then examined by independent examiners. Radiolucencies as well as radiopacities adjacent to the restoration were considered to be caries. The validation of the bite-wing radiographic diagnosis was achieved by comparison with the radiographs of the sections. A sensitivity of 64% and a specificity of 98% were calculated. Large lesions were always visible on the bite-wing radiograph (100%), the majority of medium-sized lesions (89%) and 40% of small lesions. Small radiopacities were detected more often than small radiolucencies.

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