Methods: 5 materials were tested including one IPN-FRC (everStick®-C&B, StickTech) and four CLP-FRCs (GrandTec®,VOCO; Dentapreg®, ADM; TenderFiber®, Micerium; Splint-It®, Pentron). FRC strands were light polymerized, oxygen-inhibition-layer was removed, adhesive (Optibond-FL®, Kerr) was labelled with fluorescent dye (rhodamine-B), applied on FRCs (5 min) and light polymerized (40 sec). Specimens were prepared for confocal laser scanning microscopy. 15 FRC strands (3 per group) were sectioned into 3 specimens each and depth of adhesive penetration was measured at 4 sites (n=36 per group). Depth of penetration could be clearly detected since monomers of the adhesive material were able to penetrate into FRC strands whereas filler particles of adhesive material were not. Width of fluorescent layer between non-infiltrated FRC strand and filler particle borderline within adhesive layer was measured and taken as depth of penetration. Study was planned as pilot investigation with descriptive statistical analysis.
Results: Depths of penetration [Arithmetic mean ± standard deviation] were 21.8±3.6µm (everStick®), 13.3±3.6µm (Splint-It®), 5.3±1.9µm (TenderFiber®), 4.1±1.7µm (Dentapreg®) and 4.0±2.9µm (GrandTec®). Samples were normally distributed. Differences between groups were analysed by ANOVA (PostHoc Scheffé, p=0.05). Three subgroups were found; i) everStick®; ii) Splint-It®; and iii) GrandTech®, Dentapreg®, TenderFiber®.
Conclusion: The adhesive was able to penetrate significantly deeper into IPN specimens than into CLP materials. The ability of deep adhesive penetration might increase the opportunity to establish a good link between FRC, veneering composite and tooth.