The in vitro morphological effects of some current pre-treatments on dentin surface: a SEM evaluation.
This in vitro study morphologically evaluated the effect of some current surface pre-treatments on dentin, using scanning electron microscopy, and related these morphological alterations to clinical implications. The labial surfaces of 30 bovine lower incisors were ground to obtain a flat dentin surface and were finished with 600-grit SiC paper to produce standardized smear layers. The teeth were randomly divided into six groups of five each. Group 1 was the control group, smear layer covered dentin; Group 2 was etched with 37% phosphoric acid (PA) for 15 seconds; Group 3, 37% PA for 15 seconds, followed by 10% NaOCl for 60 seconds; Group 4, 10% NaOCl for 60 seconds; Group 5, a self-etching primer (Clearfil SE Bond, CSEB-primer) was applied for 20 seconds; Group 6, CSEB-primer for 20 seconds, followed by NaOCl for 60 seconds. The specimens were fixed, dehydrated, dried and analyzed by SEM. Treatment with 37% PA removed the smear layer, funneled the tubules and resulted in a collagen-rich surface which appeared to have collapsed in its outermost part, producing a dense surface layer covered with silica particles. When 37% PA treatment was followed by 10% NaOCl, the collagen network was removed to reveal an eroded, rough mineral surface with numerous lateral branches and larger than normal tubular orifices. The action of 10% NaOCl on the smear layer-covered dentin showed no significant alteration in surface morphology. The treatment with CSEB-primer dissolved the smear layer but only partially dissolved the smear plugs. The tubules did not present the typical funnel shape seen following PA treatment. These morphological aspects on dentin surface must influence bonding results. The dentin surface alterations produced by PA appeared to be a very severe demineralization pattern, quite irregular and less permeable to monomer infiltration, while the surface provided by the self-etching primer appeared to be a more uniform, less porous surface, and the association with simultaneous monomer infiltration may reduce the occurrence of mistakes in clinical bonding procedures.
Montes
Marcos Antonio Japiassú Resende
MA
School of Dentistry of Pernambuco, University of Pernambuco--UPE, Brazil. majrm@uol.com.br
de Goes
Mario Fernando
MF
Sinhoreti
Maŕio Alexandre Coelho
MA
D000134:Acid Etching, Dental / Q000379:methods*; D000818:Animals; D017554:Carbon Compounds, Inorganic / Q000737:chemistry; D002417:Cattle; D003094:Collagen / Q000648:ultrastructure; D003804:Dentin / Q000648:ultrastructure*; D003808:Dentin Solubility; D008855:Microscopy, Electron, Scanning; D010756:Phosphoric Acids / Q000737:chemistry; D016062:Porosity; D011897:Random Allocation; D019279:Resin Cements / Q000737:chemistry; D017655:Silicon Compounds / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry; D016369:Smear Layer; D012973:Sodium Hypochlorite / Q000737:chemistry; D013997:Time Factors
D017554:Carbon Compounds, Inorganic; C438313:Clearfil SE Bond; D010756:Phosphoric Acids; D019279:Resin Cements; D017655:Silicon Compounds; D012822:Silicon Dioxide; D003094:Collagen; D012973:Sodium Hypochlorite; C022088:silicon carbide