Marginal and Internal Adaptation Evaluation of Dental Composites Using Micro-CT

The aim of the study was to determine the marginal and internal adaptation after curing of different composite resin restorations, using a nondestructive X-ray micro-computed tomography (micro-CT). Forty previously extracted human molars, kept in 10% formalin to preserve the bonding capabilities of the tooth structures, were divided into four groups based on the composite system used and different light-curing times. Class II (vertical slot) cavities were prepared on one proximal side and restored with dental composite using a Tofflemire matrix, with a bulk-fill composite resin (Venus Bulk Fill, Heraeus Kulzer) and a universal posterior composite (G-ænial Posterior, GC). A curing lamp (Kerr Demi Ultra) was used with different curing times. Micro-CT scanning was performed by using Nikon XTH 225ST to reveal any defects in adaptation or gaps at the tooth restoration interface. The 3D images of the adaptation around the restorations were reconstructed using VG Studio Max 2.2 and myVGL 2.2.6 64-bit software. All samples from the G-ænial group showed marginal and internal gaps, with G-ænial Posterior having higher polymerization shrinkage and marginal gap values. In the Venus Bulk Fill group, there were fewer restorations with internal and external gap formation. Micro-CT is a three-dimensional imaging technique that can nondestructively detect adaptation around the resin composite restorations at every level of the sample.