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Lookup NU author(s): Dr Matthew GermanORCiD, Dr James Field, Professor Giles McCrackenORCiD
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Objectives: Despite over 40-years of clinical use there are still no clear guidelines on what pre-treatment is required in order to repair fractured composite restorations predictably. Here, we compare the in vitro efficacy of three common surface pre-treatments on the shear bond strength (SBS) of composite repairs.Methods: Disc specimens (diameter=12mm, thickness=3mm, n=45) were fabricated from five commercially available composites (table 1) using custom-made resin moulds. Specimens were polymerised for 40s on both faces (Coltolux LED, 500mW/cm2) and then left to condition for 24-hours in distilled water at 37°C. Specimens were divided into 3 treatment groups:Group1: Polished for 60s (P600, SiC paper)Group2: As group1, plus etched for 15s (36% H3PO4, Conditioner 36, DeTrey)Group3: As group2, plus treated with a bonding agent as per manufacturer’s instructions (Optibond Solo Plus, Kerr)For each group, fresh composite of the same brand was then applied to the treated surface (5mm diameter, 5 mm height) and polymerised for 40 seconds before incubating at 37°C for 24 hours in distilled water. SBS was then measured for each group (1mm/min, Instron 5567) and representative specimens of G1 and G2 profiled (Surftest SV-2000, Mitutoyo).Results: Polishing the surface in isolation resulted in a low SBS for all materials. While acid-etching resulted in no increase in Ra for any composite (P>0.05, Kruskal-Wallis) the SBS increased for most composites (P<0.05, ANOVA), suggesting that some sub-micron roughening must have occurred. Group3 could not be profiled but the SBS significantly increased for all groups compared to group2 and group1 (P<0.05).Conclusions: Within the limits of this study, simply polishing composites prior to repair resulted in a low SBS. To optimise SBS, both etching and applying a bonding agent were required. Further work is required to consider the compound effect of composite aging and bonding dissimilar composites together.TABLE:Table 1: Summary of SBS and Roughness Data Shear Bond Strength: [MPa] mean (SD)Roughness (Ra): [μm] median (IQR)MaterialG1 (Polished)G2 (Acid Etch)G3 (Bonding Agent)G1 (Polished)G2 (Acid Etch)Filtek Z25010.0 (5.1)a15.2 (4.6)d17.5 (5.0)h,i0.26 (0.05)0.28 (0.05)Kalore8.4 (2.4)a,b13.5 (3.1)d,e19.3 (4.6)h0.33 (0.11)0.31 (0.04)Filtek Supreme XTE2.9 (2.4)8.7 (4.3)f,g13.4 (2.9)h,j0.23 (0.08)0.22 (0.04)Heliomolar3.7 (1.4)c11.4 (2.4)e,f16.9 (2.6)h,i0.19 (0.05)0.20 (0.05)N`Durance6.8 (2.7)a,b,c6.1 (1.8)g15.6 (3.4)i,j0.25 (0.07)0.25 (0.02)Same letter = no significant difference (P>0.05)TABLE FOOTER:Same letter = no significant difference (P>0.05)
Author(s): German M, Al-Bazaranchi T, Field J, McCracken G
Publication type: Conference Proceedings (inc. Abstract)
Publication status: Published
Conference Name: IADR/AADR/CADR General Session 2017
Year of Conference: 2017
Acceptance date: 26/01/2017
