Evaluation of the F2000 bonding procedure: a high resolution SEM study

Objectives: The aim of this study was to define the morphological bonding o f the F2000 Restorative System QM Dental Product) to enamel and dentin. For this purpose, high resolution scanning electron microscope (SEM) in conjun ction with a tensile bond strength analysis was used to correlate the morph ological findings to the bonding potential. Scotchbond 1 (SB1) adhesive sys tem was utilized as a control. Materials and methods: Teeth were prepared in vivo and prepared as: (1) F20 00 PA. for 15 s, (2) F2000 PA for 30 s, (3) 35% phosphoric acid for 15 s an d SB1 and (4) 35% phosphoric acid for 30 s and SB 1. All teeth were then re stored with the F2000 compomer restorative material, extracted, sectioned a nd analyzed by means of a field emission in-lens SEM (FEISEM). The conditio ning/etching patterns of the two adhesive systems were also evaluated in vi tro on dentin disks in order to show high resolution details of every singl e step of the bonding procedure. Results: FEISEM images showed a repetitive pattern of the enamel crystals w ith several microporosities after the 30 s application of F2000 PA; moreove r a good adaptation of the adhesive resin on the conditioned enamel was obs ervable. FEISEM analysis of the dentin surface revealed no evidence of a sm ear layer after the application of F2000 PA for 30 s. Residual smear plugs were partially obliterating the tubule orifices when F2000 PA was used, whi le they were completely absent after etching with 35% phosphoric acid. The total etching technique revealed open tubules and resin tags formation afte r the application of SB 1. Conclusions: The one step etching/priming/bonding procedure of the F2000 PA showed favorable results at ultra-structural level when applied on both th e enamel and the dentin surface for 30 s (as per manufactures' instructions ), but the bond strength analysis showed higher values of bonding of the F2 000 compomer when the SB1 adhesive agent (after etching with 35% phosphoric acid) was used (7.7 +/- 2.2 vs 19.0 +/- 4.4 Wa). (C) 2001 Elsevier Science Ltd. All rights reserved.