Influence of eugenol-containing temporary restorations on bond strength ofcomposite to dentin

This study investigated the influence of eugenol-containing temporary resto rations on bond strength of composite to dentin. Thirty-two freshly extract ed human molars were embedded and horizontally sectioned at a level 2 mm fr om the central fossa to obtain a flat dentin surface. The teeth were random ly divided into four groups of eight teeth. Specimens in Group 1 (control) received no pretreatment with any temporary restorations. Group 2 and 3 spe cimens were covered with IRM (eugenol-containing) mixed at powder: liquid ( P:L) ratio of 10g- 1g and 10g- 2g, respectively. Specimens in Group 4 were covered with polycarboxylate cement (eugenol-free) mixed at a P:L ratio of 2.85g: 1g. The temporary restorations were mechanically removed with an ult rasonic scaler after one-week storage in distilled water at 37 degreesC. Th e dentin surfaces were cleaned with pumice-water slurry and treated with Sc otchbond Multi-Purpose Plus bonding system according to manufacturer's inst ructions. Composite (Z100) columns (3 mm diameter, 2 mm high) were applied and shear bond testing was carried out after 24 hours storage in distilled water at 37 degreesC using an Instron Universal testing machine with a cros s-head speed of 0.5 mm/minute. The mode of failure was examined using a ste reomicroscope at X40 magnification. Results were analyzed using one-way ANO VA/Scheffes's post-hoe test at significance level 0.05. Ranking of bond str engths was as follows: Group 1 (22.58 MPa) > Group 2 (21.14 MPa) > Group 4 (15.35 MPa) > Group 3 (13.02 MPa). Group 3 had significantly lower bond str ength than Groups 1 and 2. No significant difference in dentin bond strengt h was observed between the Group I (control) and Groups 2 and 4. Although t he predominant mode of failure for Groups 1, 2 and 4 was cohesive in dentin , all specimens in Group 3 exhibited adhesive failure. Pre-treatment with p olycarboxylate cement or IRM mixed at P:L ratio of 10g- 1g did not affect s hear bond strength of composite to dentin. IRM mixed at a lower P:L ratio o f 10g- 2g significantly decreased bond strength.