Iatrogenic damage to approximal surfaces in contact with Class II restorations

This study investigated the frequency of iatrogenic damage to approximal surfaces in contact with Class II restorations.

Patients (n = 28) with a Class II restoration in contact with an unrestored surface had elastic separators fitted interproximally. Contralateral (unrestored) control surfaces were also separated. Impressions (light body polyvinylsiloxane) of the separated surfaces were taken 3-6 days later. Interproximal impressions (28 paired, seven unpaired) were examined by binocular microscope and scanning electron microscope (SEM) for iatrogenic damage, attrition and cavitation due to caries.

49-60% of surfaces adjacent to Class II restorations had been iatrogenically damaged. The most frequent types of damage were vertical grooves (26%), extensive damage (17%), indentations (6%) and scratches (6%). Damage was more frequent in maxillary teeth (61%) than mandibular teeth (25%), in permanent teeth (60%) more than deciduous teeth (20%). Qualified dentists produced more iatrogenic damage (64%) than undergraduate students (23%).

The frequency of iatrogenic damage to approximal surfaces following Class II preparations was 49%, and possibly as much as 60% when questionably damaged surfaces were included. Protection of the adjacent enamel is of paramount importance during Class II cavity preparation.