Restorative
Dina Hamdy, Master of Pediatric Dentistry (she/her/hers)
Doctoral Candidate
Justus-Liebig-University Giessen
Justus-Liebig-University
Cologne, Nordrhein-Westfalen, Germany
Stefanie Amend, Dr.
Department of Pediatric Dentistry, School of Dentistry, University Medical Center Giessen and Marburg, Campus Giessen, Justus-Liebig-University Giessen, Germany
Giessen, Hessen, Germany
Norbert Kraemer, Prof. Dr. Dr.
Head of Department
Department of Pediatric Dentistry, School of Dentistry, University Medical Center Giessen and Marburg, Campus Giessen, Justus-Liebig-University Giessen, Germany
Giessen, Hessen, Germany
Purpose: Our aim was evaluating the effect of phosphoric acid etching time on the microtensile bond strength (µTBS) of universal adhesives to primary enamel and its stability after aging.
Methods: Sound human primary molars were sectioned mesiodistally. Tooth halves (n=101) were randomized into 3 groups based on the adhesive: SU: Scotchbond Universal (3M); CU: Clearfil Universal Bond Quick (Kuraray Noritake); iBU: iBond Universal (Heraeus Kulzer). Aprismatic enamel was removed, then groups were subdivided according to etching time (DeTrey Conditioner 36, Dentsply) into 3 subgroups (SG): SG1: 0s; SG2: 15s; SG3: 30s. Adhesives and composite were added (Filtek Z250, 3M). Samples were incubated in distilled water at +37°C for 24h, while separate samples for SG1& SG2 were aged for 6 months. Specimens were dissected (0.7 mm × 0.7 mm; IsoMet Highspeed Pro, Buehler), then tested (µTBS; TC-550, Syndicad). Failure patterns were evaluated under light microscope (AZ100M, Nikon). Data were analysed with linear mixed effects model (restricted maximum likelihood, REML) and Sidak post-hoc-tests using SPSS 26.0 with significance level set at P < .05.
Results: Selective-etching increased µTBS of universal adhesives to primary enamel (P < .001) without significance between enamel etching for 15s and 30s (P>.05). Six-month aging significantly reduced the µTBS of SU in SG2 (P < .014) compared to µTBS after 24h incubation.
Conclusions: Selective-etching with phosphoric acid remains the gold standard for bonding universal adhesives to primary enamel. Etching time showed no significant effect on µTBS. Aging may affect the µTBS of SU applied on 15s phosphoric acid etched primary enamel.