Effects of oxalate on dentin bond after 3-month simulated pulpal pressure.
OBJECTIVE
Application of an acidic oxalate solution forms calcium oxalate within dentinal tubules and has been used to desensitize dentin and may also improve performance by reducing internal dentin wetness during bonding. The hypothesis tested was that oxalate restriction of dentinal fluid transudation when using an etch-and-rinse two-step adhesive will improve microtensile bond strength (muTBS) and reduce nanoleakage.


METHODS
Occlusal dentin of 60 human molars were bonded (Adper Single Bond Plus, 3M ESPE) while one-half of each tooth received either a liquid (SuperSeal, Phoenix Dental) or gel (BisBlock, Bisco) oxalate treatment after acid etching. The restored teeth were placed under pulpal pressure for 3 months before forming cylindrical dumbbell specimens for muTBS and failure pathway determination. Additional teeth were prepared and stored in a similar manner for transmission electron microscopy (TEM) examination of nanoleakage after tracer immersion.


RESULTS
The mean bond strength in the group with oxalate liquid and the control group was 27.06+/-7.14 and 36.18+/-9.07 MPa, respectively, and for the gel form of oxalate was 25.34+/-13.09 and 33.09+/-14.25 MPa, respectively. The control groups were significantly stronger than either oxalate group using t-tests (liquid p<0.00001; gel p=0.0032) or Weibull (liquid p=0.0002; gel p=0.0029) statistics. Oxalate groups also demonstrated more adhesive failure modes and nanoleakage.


CONCLUSIONS
Under the conditions of this study, the application of oxalate with an etch-and-rinse two-step bonding system produced significantly lower long-term muTBS and enhanced nanoleakage.
Vachiramon
Viracha
V
Department of Conservative Dentistry and Prosthodontics Faculty of Dentistry, Srinakharinwirot University Sukhumvit 23, Wattana District, Bangkok 10110, Thailand. viracha@swu.ac.th <viracha@swu.ac.th>
Vargas
Marcos A
MA
Pashley
David H
DH
Tay
Franklin R
FR
Geraldeli
Saulo
S
Qian
Fang
F
Armstrong
Steven R
SR
D000134:Acid Etching, Dental / Q000379:methods; D017438:Bisphenol A-Glycidyl Methacrylate; D003188:Composite Resins; D001840:Dental Bonding / Q000009:adverse effects; D003763:Dental Leakage / Q000209:etiology*; D003782:Dental Pulp / Q000502:physiology; D003799:Dental Stress Analysis; D003804:Dentin; D003806:Dentin Permeability / Q000187:drug effects*; D017220:Dentin-Bonding Agents; D019234:Dentinal Fluid / Q000502:physiology*; D006801:Humans; D008422:Materials Testing; D008963:Molar; D010070:Oxalates / Q000494:pharmacology*; D016016:Proportional Hazards Models; D016019:Survival Analysis; D013718:Tensile Strength
D003188:Composite Resins; D017220:Dentin-Bonding Agents; D010070:Oxalates; C511238:Single Bond Plus; D017438:Bisphenol A-Glycidyl Methacrylate