Marginal integrity and secondary caries of selectively excavated teeth in vitro

Objectives

Selective caries removal involves sealing of carious dentine beneath restorations, which might decrease their marginal integrity and increase the susceptibility for secondary caries and microleakage. The present study compared these marginal characteristics of restorations in selectively and completely excavated teeth.

Methods

In 32 premolars, shallow and deep artificial lesions were created on pulpo-axial walls of mesial-distal-occlusal cavities, with mesial and distal margins located in enamel and dentine, respectively. Demineralised dentine was either removed or left before adhesively restoring the teeth (n = 8), which were then submitted to thermo-mechanical cycling. The integrity of gingivo-cervical margins was assessed using scanning electron microscopy. In half of each margin, caries was induced adjacent to restorations using a continuous-culture biofilm model, and resulting lesions were evaluated using transversal microradiography. The other half of each margin was used to assess microleakage.

Results

Integrity or microleakage of margins located in enamel did not differ significantly between groups, and bacterial biofilms did not induce distinct caries lesions in enamel. Dentinal margins in teeth with deep compared with shallow lesions showed a significantly higher proportion of marginal imperfections, gaps and microleakage (p ≤ 0.05, Mann–Whitney/χ²-test). In contrast, neither marginal integrity nor microleakage differed significantly between completely and selectively excavated teeth (p > 0.05). Dentinal mineral loss adjacent to restorations did not differ significantly between groups (p > 0.80).

Conclusions

The marginal characteristics of restorations were affected by the depth of sealed or excavated lesions, but not by the performed caries excavation. This study did not find selective excavation detrimental for restoration integrity in vitro.

Clinical significance

Selective excavation of deep lesions was shown to reduce pulpal risks, whilst leaving caries beneath restorations is feared to compromise the marginal characteristics of the subsequently placed restoration. Based on the present in vitro study, such assumptions cannot be supported.