Confocal microscopy evaluation of post-resin-dentine interfaces

Objectives: The objectives of this study were to compare the number of voids and the cement thickness in post-resin-dentine interfaces of teeth restored with conventional and anatomically modified glass fibre posts. Methods: 48 single-rooted mandibular premolars were selected. After removing the crowns at the cemento-enamel junction the coronal portions of the root canals were prepared using Gates Glidden drills and instrumented to a size 40 master apical file. The apical portions of the roots were obturated with vertically condensed gutta-percha. The roots were divided into 2 groups. The teeth in group 1 were restored with standard fibre posts (Easypost Lux) and the teeth in group 2 were restored with anatomically modified glass-fibre posts (Periodent). The posts were cemented using a dentine bonding system (Sealbond Ultima) and composite cement (Corecem). The bonding agent was labelled with Rhodamine B, applied on the root dentine and on the surface of each post and light cured for 60s. Each tooth was sectioned along the long axis in a mesio-distal direction and sections were randomly selected for the study, 24 independent specimens were therefore included in each group. Confocal microscopy was used to assess the presence of voids between cement and fibre post (G1) between dentine and adhesive (G2) and between cement and adhesive (G3) at six sites for each specimen (two coronal, two middle, and two apical).The thickness of the cement was also evaluated at the same sites. All data were statistically analyzed using Pearson's X² Results: The presence of voids in Group 1 was significantly greater than in group 2. No significant differences were found between the cement thicknesses of the two groups. Conclusions: Anatomically modified glass fibre posts produced a post-resin-dentine interface of better quality than conventional posts.