A contagion effect of caries on tooth surfaces in contact with each other has previously been demonstrated; the presence of a caries lesion on an approximal tooth surface increases the risk of developing caries in a sound contact surface on the adjacent tooth. Will this increased risk for caries development be eliminated when restoring the decayed surface with a restoration? A recent publication by the NIOM scientist Dr Kopperud has elucidated the question.

Is the caries risk reduced by placing a restoration?His research group evaluated 750 surfaces in contact with newly placed Class II composite restorations using standardised clinical and radiographic criteria when the restoration was placed (baseline) and after five years. At baseline, the contact surfaces were categorized as being either initially sound (n = 417) or having present caries confined to enamel (n = 333).

After the observation period, 38.8% of the initially sound contact surfaces remained sound, 34.0% had caries confined to enamel and 27.2% showed caries into dentine. For 57.3% of the surfaces with caries confined to enamel present at baseline, the lesion remained in the enamel, while it progressed into dentine for 42.7% of the surfaces.

Risk factors for dentine caries development were assessed by logistic regression analyses. The risk of developing caries on surfaces that were initially sound at baseline was significantly higher in patients with poor or medium oral hygiene, in patients with a high previous caries experience (DMFT), in maxillary teeth and on contact surfaces in the patients’ right sides. For the surfaces with enamel caries already present at baseline, the risk of developing dentine caries was significantly higher in patients with high previous caries experience (DMFT). Significant dentist-related differences in caries development on contact surfaces were found in both regression analyses; surfaces adjacent to restorations placed by some dentists were found to have significantly higher risk, while surfaces adjacent to restorations placed by other dentists showed significantly lower risk of dentine caries development.

Clinical implication
Clinicians should be aware of a notable risk of caries development on the adjacent tooth surface, especially when placing approximal restorations in high-caries-risk patients. A greater use of preventive strategies should be considered after placing approximal restorations. These should be evaluated and repeated at every recall.

More reading
Kopperud SE et al., Risk factors for caries development on tooth surfaces adjacent to newly placed Class II composites – a pragmatic, practice based study, Journal of Dentistry (2015), http://dx.doi.org/10.1016/j.jdent.2015.08.013
Is the caries risk reduced by placing a restoration?Download NIOM Newsletter October 2015