Bonding to cervical sclerotic dentin: effect of acid etching time.
OBJECTIVE
The aim of this in vitro study was to evaluate the microtensile bond strengths (MTBS) of two total-etch one-bottle adhesive systems to natural cervical lesions with 2 different etching times (15 s vs 30 s).


METHODS
Thirty-two human canines and premolars with saucer-shaped noncarious cervical defects were cleaned and randomly assigned to 4 groups. The adhesive systems - Single Bond (SB; 3M ESPE) or OptiBond Solo Plus (OP; Kerr) - were applied on cervical dentin after acid etching with the proprietary acid gel (35% or 37.5% phosphoric acid) for 15 s (manufacturer's instruction) or for 30 s. The respective hybrid composite was inserted in three increments and light cured. After 24 h water storage, the specimens were cut perpendicularly with a low-speed diamond saw (Isomet) to obtain slices with a cross section of ca 0.8 mm. After that, the slices were trimmed with a diamond bur to obtain a surface area of 0.7 +/- 0.05 mm2 (n = 12). MTBS was measured in a Bencor device with an Instron machine at a crosshead speed of 0.5 mm/min. The data were subjected to two-way ANOVA and Tukey's LSD post-hoc test (p < 0.05).


RESULTS
MTBS are given in MPa (mean +/- SD), where means with the same superscript letter are not statistically different at p < 0.05: OP15 = 30.9 +/- 8.8ab, SB15 = 25.6 +/- 9.6bc, OP30 = 19.0 +/- 4.8c, SB30 = 35.9 +/- 11.0a. When data were pooled for "adhesive system", SB resulted in statistically higher bond strengths than OP (p < 0.043). "Acid etching time" had no significant effect (p < 0.766), but the interaction of the two main factors yielded significant differences (p < 0.0001). Extending etching time to 30 s resulted in a more predictable bond to noncarious cervical sclerotic dentin with SB, but resulted in lower MTBS with OP.


CONCLUSIONS
Composite bonding to cervical sclerotic noncarious dentin may depend on acid demineralization capacity and bonding system. Knowing the etching demineralization rates of the commercially available acid etching seems to be an important factor for selecting the best acid-etching time of cervical sclerotic dentin.
Lopes
Guilherme Carpena
GC
Department of Operative Dentistry, Universidade Federal de Santa Catarina, Florianópolis, Brazil. guilherme_lopes@ig.com.br
Baratieri
Carolina Mascarenhas
CM
Baratieri
Luiz Narciso
LN
Monteiro
Sylvio
S
Cardoso Vieira
Luis Clovis
LC
D000134:Acid Etching, Dental / Q000379:methods*; D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003799:Dental Stress Analysis / Q000295:instrumentation; D003809:Dentin, Secondary / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry; D006801:Humans; D010756:Phosphoric Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D013718:Tensile Strength; D013997:Time Factors; D019237:Tooth Cervix / Q000648:ultrastructure*; D014076:Tooth Diseases / Q000473:pathology; D014867:Water / Q000737:chemistry
D003188:Composite Resins; D017220:Dentin-Bonding Agents; C444701:Filtek Z250; C451600:OptiBond Solo Plus; D010756:Phosphoric Acids; C099128:Prodigy; D019279:Resin Cements; C115612:single bond; D014867:Water; D017438:Bisphenol A-Glycidyl Methacrylate