Effects of Different Surface Conditioning Methods on the Bond Strength of Composite Resin to Amalgam

Abstract

SUMMARY Repairing amalgam restorations with composite resins using surface conditioning methods is a conservative treatment approach. This study investigated the effects of different conditioning methods that could be used for repair of amalgam fractures. Amalgam (N=96) was condensed into cavities within autopolymerizing polymethylmethacrylate (PMMA), and the exposed surface of each specimen (diameter, 6 mm; thickness, 2 mm) was ground finished. The specimens were randomly divided into nine experimental groups (n=12 per group), depending on the conditioning method used. The control group had natural central incisors with amalgam (n=12). The combination of the following conditioning methods was tested: silicacoating (Sc), sandblasting (Sb), metal primers, coupling agents, fiber (Fb) application, and opaquers (O). Five types of silanes, metal primers, or adhesives (Visiobond [V], Porcelain Photobond [PP], Alloy Primer [AP], Unibond sealer [Us], ESPE-Sil [ES]), and four opaquers, namely, Clearfil St Opaquer (CstO), Sinfony (S), Miris (M), and an experimental Opaquer (EO-Cavex), were used. The groups were as follows: group 1, Sc+ES+S+V; group 2, Sc+ES+CstO+V; group 3, Sc+ES+M+V; group 4, Sc+ES+EO+V; group 5, Sb+AP+S; group 6, Sb+AP+PP+CstO; group 7, Sc+ES+S+Fb+V+Fb; group 8-control, SC+ES+V; and group 9, Etch+Sc+ES+S+Us. One repair composite was used for all groups (Clearfil Photo Bond Posterior, Kuraray, Tokyo, Japan). Shear bond strengths (SBSs) (MPa ± SD) were evaluated after 5 weeks of water storage (analysis of variance [ANOVA], Tukey honestly significant differences [HSD], α=0.05). Group 1 exhibited significantly higher values (35.5 ± 4.1) than were seen in group 4 (19.4 ± 8.9), group 6 (19.1 ± 7.8), and group 8 (20.1 ± 4.1) (p<0.05). Group 9 exhibited significantly lower values (8.3 ± 3.4) than were noted in groups 1 to 3 (35.5 ± 4.1; 27 ± 12.5; 24.4 ± 5.1, respectively) (p<0.05). Group 7 (16.4 ± 5.9) showed significantly lower values than were observed in group 1 (35.5 ± 4.1) (p<0.05). Surface conditioning techniques affected the bond strengths of composite adhesion to amalgam. Experimental opaquer exhibited lower values. Leaving a small border of enamel around the restoration decreased the bond strength.

Management of Class I and Class II Amalgam Restorations with Localized Defects: Five-Year Results

“…A recent study suggests that repaired restorations could outlast restorations that have been replaced, and one possible reason for this is that most of the original restoration is kept intact [19]. Although the use of resin-based composite to repair amalgam restorations is considered an appropriate process whenever a proper surface conditioned technique is applied [27, 28], restorations were repaired with amalgam based on the low cost and long-term effectiveness of this material [29]. …”

Evaluation of Mercury Contamination in Patients and Water during Amalgam Removal

“…20 Another way to solve this problem could be repairing the amalgam restorations using composite resins. [21][22][23][24][25] When a part of the amalgam restoration and/or the cusp is fractured, that is a common problem, the professional could chose for repair this restoration instead of remove all of it. [21][22][23][24][25] Further studies and broader discussions are recommended to assess the actual environmental impacts of this contamination and lead to safe clinical practices.…”

Evaluation of Effectiveness of Self-Adhesive Composites for Amalgam Repair with or Without Alloy Primer, in Terms of Shear Bond Strength

“…• Group FLD: FLD (Pentron Clinical, USA) was injected to the polyethylene mold (inner diameter, 3mm; height, 2mm) incrementally in two layers measuring not more than 1mm. Each layers of FLD were dispensed to the surface for 20s and light polymerized (at 800 mW/cm², Elipar Trilight, 3M ESPE, Seefeld, Germany) from a distance of 2mm for 10s (9). Another polyethylene mold (inner diameter, 3mm; height, 2mm) was placed upon the first one, and the same procedure was repeated.…”

“…On the other hand, primers and adhesives produce ionic bonds with amalgam surfaces (6). The effect of Alloy Primers (AP), metal primers, opaquers, airborne particle abrasion, fibre sheets, bonding systems, silica coating and silanization on composite and amalgam bonding have been reported in the literature (1,(6)(7)(8)(9). However, these complex methods are not usually suitable for amalgam repair in noncooperate patients.…”