title: Does a low-shrinking composite induce less stress at the adhesive interface?
abstract: OBJECTIVE
  Polymerization shrinkage of a composite in a high configuration-factor (C-factor) cavity leads to polymerization shrinkage stress. In the prevention of high polymerization shrinkage stress, a low-shrinking silorane composite (Filtek Silorane, FS, 3M ESPE) was recently marketed. Therefore, we investigated the effect of C-factor (flat surface vs. class-I cavity) and different composite application protocols on the bonding effectiveness of a low-shrinking composite to human dentin.
  
  
  METHODS
  A low-shrinking silorane-based composite (FS) and a conventional methacrylate-based composite (Filtek Z100, 3M-ESPE) were bonded to standardized occlusal class-I cavities (4 mm x 4 mm x 2.5 mm) and to flat mid-coronal dentin surfaces using the two-step self-etch adhesive 'Silorane System Adhesive' (3M-ESPE). Eight experimental groups were formed, according to the following treatment protocols: Z100 'flat'(1), Z100 'cavity'(2), FS 'flat'(3), FS 'flat/bulk-filled'(4), FS 'cavity/bulk-filled'(5), FS 'cavity/layered-filled'(6), FS 'cavity/flowable cured'(7) and FS 'cavity/flowable uncured'(8). For each group, at least 5 teeth were used. After 1 week of water storage, the teeth were sectioned to 1 mm x 1 mm (non-trimmed) sticks to measure the micro-tensile bond strength (microTBS).
  
  
  RESULTS
  No statistical difference in microTBS was recorded between Z100 'flat'(1) and FS 'flat'(3). Bonding to class-I cavity dentin lowered the microTBS in all groups, but this was only statistically significant for FS 'cavity/bulk-filled'(5) and FS 'cavity/flowable uncured'(8).
  
  
  CONCLUSIONS
  Using the two-step self-etch Silorane System Adhesive, the conventional composite Filtek Z100 and the low-shrinking composite Filtek Silorane bonded equally well to dentin. Bulk-filling with Filtek Silorane (FS 'flat/bulk-filled'(4)) significantly decreased the microTBS, suggesting that factors other than polymerization shrinkage influenced the microTBS.
authors.affiliation: Leuven BIOMAT Research Cluster, Department of Conservative Dentistry, School of Dentistry, Oral Pathology and Maxillo-facial Surgery, Catholic University of Leuven, Kapucijnenvoer 7, 3000 Leuven, Belgium.
authors.forename: Annelies
authors.initials: A
authors.lastname: Van Ende
authors.forename: Jan
authors.initials: J
authors.lastname: De Munck
authors.forename: Atsushi
authors.initials: A
authors.lastname: Mine
authors.forename: Paul
authors.initials: P
authors.lastname: Lambrechts
authors.forename: Bart
authors.initials: B
authors.lastname: Van Meerbeek
mesh_terms: D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry; D003737:Dental Cavity Preparation / Q000379:methods*; D018772:Dental Marginal Adaptation; D003793:Dental Restoration, Permanent / Q000379:methods*; D003799:Dental Stress Analysis; D003804:Dentin; D017220:Dentin-Bonding Agents; D006801:Humans; D055115:Light-Curing of Dental Adhesives; D008422:Materials Testing; D012822:Silicon Dioxide; D062047:Silorane Resins; D018709:Statistics, Nonparametric; D013718:Tensile Strength; D015040:Zirconium
chemical_list: D003188:Composite Resins; D017220:Dentin-Bonding Agents; C543062:Filtek LS Low Shrink resin; D062047:Silorane Resins; C083568:Z100 composite resin; D012822:Silicon Dioxide; D015040:Zirconium