Objective: The aim was to compare the "reverse sandwich restoration" to resin composite restorations regarding marginal adaptation, fracture resistance, favourable/unfavourable fractures in the management of external cervical resorption.

Methods: Forty-eight extracted maxillary central incisors were selected and endodontically treated. Cervical regions of the labial root surfaces received simulated resorptive defects and were restored as three randomly allocated groups: Reverse Sandwich Restoration (resin composite + resin-modified glass ionomer) (RSR); resin composite restoration (COMP), and no restoration (NR). Each group was further divided into two subgroups (n=8 each): Thermomechanical Aging (TA) (equivalent to one year) and No Aging (NA). Marginal adaptation was scored by scanning electron microscopy. Fracture resistance was tested using a universal testing machine. Favourable versus unfavourable fractures were classified based on fracture extent.

Results: TA decreased the marginal adaptation for both RSR and COMP. Mean fracture resistance per groups were: RSR-NA 1522.4[+ or -]94.9N, RSR-TA 939.6[+ or -]72.9N, COMP-NA 1197.6[+ or -]95.7N, COMP-TA 870.4[+ or -]86.3N, NR-NA 1057.1[+ or -]88.1N, and NR-TA 836.6[+ or -]81.9N, respectively. Fracture resistance was the highest for RSR-NA compared to all other groups (p<0.05). TA decreased the fracture resistance in all groups (p<0.05), there was no significant difference between RSR and COMP regarding fracture resistance and favourable/unfavourable fractures (p>0.05).

Conclusion: RSR provided comparable results to resin composite fillings to restore artificial cervical defects pertaining to marginal adaptation, fracture resistance, and favourable versus unfavourable fractures. RSR is preferable due to its inherent biocompatibility to the periodontium.