Spaltreduktion und Höckerstabilisierung durch Self-Etch-Adhäsive und Bulk-Fill-Technik? Multifunktionale Qualitätsprüfung von Klasse-II-Kompositrestaurationen mit einem neuartigen In-vitro-Modell

The aim of this study was to investigate the effect of simplified bonding systems (BS) and bulk-fill-technique on external and internal adaption of composite restorations as well as stabilization on cavity walls. A new in-vitro-model enables determination of those parameters on one tooth. MOD-cavities (n=90) with margins in enamel and dentin and a residual wall thickness of 2,3mm were prepared into human molars. Investigated BS were (n=20): OptiBond FL (OFL), OptiBond XTR (OXT), Clearfil S3 Plus (CS3), AdheSE One F (AOF). 10 cavities of each BS were filled with Tetric EvoCeram (LAYER), 10 cavities were filled with Tetric EvoCeram Bulk Fill (BULK). 10 cavities remained unfilled. SEM-analysis was carried out before and after Thermocycling. Internal adaption was examined by SEM on disks (4mm) cut out of the filled tooth. To determinate the fracture strength the 2,3mm thick cavity walls were loaded until fracture. Statistics: ANOVA (fracture), Kurskal-Walls (gaps). Fracture strength (average) of unfilled cavities was 133N, LAYER 247N (OFL) - 174N (CS3, p=0,000), BULK 203N (OFL) - 181N (AOF; n.s.). Difference between LAYER and BULK was only significant for OFL. Internal gap formation (median) on cavity walls among LAYER was 0,4 % (OFL) - 3,9 % (AOF; p=0,004), on cavity soil 0,0 % - 0,15 % (n.s.); BULK: 0,4 (OFL) - 4,4 % (CS3; p=0,000), 0,0 % (CS3) - 7,3 % (AOF; p=0,000). Gaps on enamel margin among LAYER were 1,3 % (OFL) - 6,1 % (AOF; p=0,023); BULK: 2,6 % (OFL) - 6,2 % (AOF; p=0,016). No influence of technique was observed. Gaps on dentin margin among LAYER were 0,6 % (OXT) - 3,0 (OFL; n.s.); BULK: 0,6 % (OFL) - 15,0 % (AOF; p=0,001). OXT and AOF performed worse with BULK. Altogether little gap formation confirms the development progress of self-etch BS. All BS effect stabilization of remaining tooth tissue. Maximum stabilization was observed for OFL/LAYER