21 In-vivo Microtensile Strength of a Silorane vs. Bis-GMA Adhesive System

Wednesday, March 21, 2012: 2:30 p.m. - 4 p.m.
Presentation Type: Oral Session
J. PURK, A. KUMAR, and V. DUSEVICH, Oral Biology, University of Missouri -Kansas City, Kansas City, MO

Gingival margins in class II composite restorations frequently fail.

Objectives: The purpose of this in-vivo pilot study was to compare the in-vivo 24 hour(h) and 28 day(d) microtensile bond strength (µT) of premolars restored with two adhesive systems; a BisGMA PQ1 (UltradentTM)/Filtek Z250 (3M-ESPETM) vs. a Silorane Filtek-LS (3M-ESPETM) adhesive system. 

Methods: After obtaining informed consent, 8 premolar teeth (slated for orthodontic extraction) from three patients received two class II prep/restorations in the proximal of each tooth.  Teeth were randomly restored with two adhesive systems and tested for µT at two times.  The four treatment groups were; 24h Silorane Filtek-LS; 24h PQ1/Z250; 28d Silorane Filtek-LS and 28d PQ1/Z250.  Manufacturer's directions were followed. The teeth were sectioned to obtain thirty-three rectangular specimens from the gingival wall of class II composite restorations with a surface area of ~0.5 mm2. Samples were tested on a Bisco Microtensile tester at 2.0 mm/min till failure. Failure mode was observed under a light microscope at 50x.




Mean MPA (SD)

Cohesive Failures

24h Silorane –Filtek-LS


26.2 (14.5)*


24h  PQ1/Z250


65.4 (14.6)+


28d Silorane –Filtek-LS


26.6 (7.4)*


28d  PQ1/Z250


68.3 (10.1)+


A two-way ANOVA found a statistically significant difference between adhesives at p < 0.001. There was no difference between times, p≤ 0.05. The Bis-GMA adhesive system had more cohesive failures and was statistically stronger than the Silorane adhesive system. Three of the 24h Silorane samples fractured during the preparation phase and could not be tested.  The adjusted R squared was 0.734.

Conclusion: The µT of the Bis-GMA PQ1/Z250 adhesive system was significantly stronger than the Silorane adhesive system bonded to the dentin gingival wall.  Composite resin may bond differently to dentin depending upon the adhesive system used.  Supported in part by USPHS-Grant K23-DE016324.  purkj@umkc.edu


This abstract is based on research that was funded entirely or partially by an outside source: USPHS-Grant K23-DE016324

Keywords: Acid etch, Adhesion, Clinical trials and Dentin bonding agents