Progression of radiopacities and radiolucencies under amalgam restorations on bite-wing radiographs

Radiolucent and radiopaque areas in the dentine under amalgam fillings represent demineralized tissue. The aim of this study was to investigate whether caries progresses in radiolucent and radiopaque areas under amalgam fillings, by assessing their enlargement longitudinally on bite-wing radiographs. Bite-wings from dentitions of persons aged 17, 20 and 23 years were compared. For a 3-year evaluation, 365 teeth with class I and class II amalgam restorations were available on bite-wings; 16 radiopacities, 46 radiolucencies and 28 combinations could be followed longitudinally. All radiopacities remained the same size, 14 radiolucencies enlarged and 8 combinations enlarged. For a 6-year evaluation, 236 filled teeth were available; 10 radiopacities, 30 radiolucencies and 11 combinations could be compared longitudinally. All radiopacities remained the same size, 12 radiolucencies enlarged and 6 combinations enlarged. Because the radiopaque areas had not enlarged visibly on bite-wing radiographs over 3 or even 6 years, it was concluded that radiopacities may be non-progressing caries. A substantial number of radiolucent areas, with or without concomitant radiopacities, did not enlarge while radiolucent areas are considered as progressing caries.