Einfluss selbstadhäsiver Unterfüllungen auf die Dichtigkeit von Klasse-I-Füllungen

For some time resin composite has replaced amalgam as material of choice for dental direct restorations. Polymerization shrinkage is still problematic and acquires a suitable adaption of composite at dental hard tissues. That should avoid leakage formation between tooth and resin composite. Bonding of resin composite needs time and is technique sensitive. For this reason manufacturers always try to simplify the application procedure of bonding to dental hard tissues. Since 2001 so called self-adhesive resin cements for bonding of indirect restorations are available. These materials don’t need any pretreatment of dental hard tissues. The aim of this study was to investigate the influence of self-adhesive resin cements used as underfilling materials on marginal adaption of composite restorations in deep class-I-cavities. For this trail 3 different materials were used. 56 extracted human molars have received 4x4x4mm sized occlusal cavities. Afterwards 4 groups were filled with Clearfil Majesty Posterior (Kuraray, Tokio, Japan) using different increment technics and another 3 groups were lined with three different self-adhesive resin cements before restoring with Clearfill MP. Afterwards the specimens were stored for 6 months at a temperature of 39°C and were put into the Thermocycler for 5000 cycles. Finally dye penetration was assessed after sawing the specimens according to a five-point scale from 0-4 using a light microscope. The conventionally filled groups 1-4 showed significant lower dye penetration scores (p<0.05) than the groups 5-7 that were treated with self-adhesive liners before filling with well-tried resin composite. Simply by observation it is detectable that the groups 1-4 are more resistant against dye penetration. It is noticeable that the dye penetration score 0 is the frequent score among the conventionally filled groups. Concerning the groups 5-7 this was score 1. If the groups 1-4 (conventionally filled) are compared to each other, no significant difference (p>0.05) was shown. The same result could be observed among the groups 5-7 (underfilled groups). Although the dye penetration scores of the underfilled groups are significantly higher than the scores of the conventionally filled groups, there is no evidence advising against the use of these materials as liners. This significant difference is a consequence of dye penetration score 1 that concerns the enamel margins which interact with Clearfil Majesty Posterior (Kuraray, Tokio, Japan). This is a well-tried material. The common observation of dye penetration score 1 can be explained by the high C-factor created by the big increments. Additionally self-adhesive resin cements are said to create a sufficient bonding to dentine. This is the dental hard tissue which interacts with the tested materials. The formation of Nanoleakage between dentine and auto-adhesive cements that was observed in several previous studies stays questionable. This fact makes the longevity of these restorations unpredictable.