DIAGNOSIS OF SECONDARY CARIES - A LABORATORY STUDY

Secondary caries is difficult to diagnose accurately. The purpose of t his laboratory study was to investigate various non-invasive clinical and radiographic criteria which might predict the presence of carious dentine beneath the margin of the filling. A total of 331 sites, each 3 mm in length on the tooth restoration margin, were selected on 112 e xtracted and filled teeth. Thirty of these sites showed obvious cariou s cavities. Ditching was apparent in a further 70 sites, while 231 sit es were clinically intact. Staining of the margin of the filling was r ecorded and radiographs were taken of posterior teeth. Restorations we re then removed and the enamel-dentine junction (EDJ) immediately belo w the sites was examined for its consistency (hard/soft) and colour (s tained/stain-free). Results showed that staining around a filling is n ot a reliable predictor of softening or discolouration of the dentine beneath. A clinical carious cavity and radiographic evidence of demine ralisation indicate soft and discoloured dentine and should trigger op erative intervention, while ditching alone should not.