Biomechanical Effects of Bonding Pericervical Dentin in Maxillary Premolars

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Introduction:Pericervical dentin (PCD) loss may increase root fracture propensity in root-filled teeth. This study evaluated the impacts of bonding PCD with composite resin (CR) on radicular microstrain distribution and load at failure of root-filled maxillary premolars.Methods:Ten single-canal maxillary premolars decoronated 2 mm coronal to the cementoenamel junction (CEJ) had canals enlarged with ProTaper Universal instruments (Dentsply Tulsa Dental Specialties, Tulsa, OK) to F3. They were root filled with gutta-percha (GP) to the CEJ and restored with Cavit (3M Deutschland GmbH, Neuss, Germany) (GP group, n = 5) or 6 mm apical to the CEJ and restored with bonded CR to simulate bonding of PCD (bonded PCD group, n = 5). Digital moiré interferometry was used to evaluate pre- and postoperative whole-field microstrain distribution in the root dentin under physiologically relevant loads (10–50 N). Another 30 premolars, similarly treated as groups 1 and 2 or left untreated as controls (n = 10/group), were subjected to cyclic loads (1.2 million cycles, 45 N, 4 Hz) followed by uniaxial compressive load to failure. Mechanical data were analyzed with 1-way analysis of variance and the post hoc Tukey test at a 5% level of significance.Results:Microstrain distribution showed bending and compressive patterns at the coronal and apical root dentin, respectively. In the GP group, microstrain distribution was unaltered. In the bonded-PCD group, different microstrain distribution suggested stiffening at the PCD. The load at failure did not differ significantly for the GP, bonded PCD, and control groups (P > .05).Conclusions:CR bonding of PCD might impact the biomechanical responses in maxillary premolar roots at low-level continuous loads. The effect of this impact on root fracture loads when subjected to cyclic load warrants further investigation.HighlightsThis study evaluated the ability of pericervical dentin (PCD) bonding in restoring fracture resistance in maxillary premolars using digital moiré interferometry and load at failure under cyclic and subsequent continuous compressive loading.Bonding PCD shifted the apical microstrain distribution toward the cervical dentin with increasing physiologic loads. This finding suggested that bonding of PCD caused stiffening of cervical root dentin, resulting in redistribution of functional loads away from the apical region.PCD bonding did not provide a significant increase in load to failure under cyclic loading, which highlights the limitations to PCD bonding.

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