Resin-dentine interfacial morphology following CPP-ACP treatment.
OBJECTIVE
To evaluate the quality of bonded resin-dentine interfaces produced by two self-etching primer adhesives after casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) treatment, in comparison to untreated dentine.


METHODS
Thirty-four adult molar teeth were sectioned to obtain dentine with tubule orientations parallel/oblique or perpendicular to the surface. The specimens were divided into 'smear layer' (1A, 1B) and 'no smear layer' groups, after treatment with 15% EDTA (2A, 2B). The specimens were then left either untreated (1A, 2A) or treated (1B, 2B) with CPP-ACP paste (Tooth Mousse, GC Corp.) for 60 min x 7 days. Each treatment group was divided into three subgroups and specimens etched/conditioned (no conditioning; 30-40% phosphoric acid (H(3)PO(4)); 20% polyacrylic acid) and bonded with either a 2-step self-etching primer adhesive (Clearfil SE Bond, Kuraray Medical) or an 'all-in-one' adhesive (G-Bond, GC Corp.) and a hybrid resin composite. After 24-h water storage, the bonded specimens were sectioned, polished up to 4000-grit abrasive silicon carbide paper and 0.25-microm diamond paste, prepared for FE-SEM using the acid-base technique, critical point-dried, gold-coated and examined. Bonded and fractured dentine interfaces were also prepared and examined.


RESULTS
The 2-step adhesive produced a similar appearance of bonded resin-dentine interface irrespective of smear layer group, treatment or etching/conditioning. After polyacrylic acid conditioning, the 'all-in-one' adhesive exhibited more areas with bond failures. The bond failures were within the hybrid layer and more pronounced following CPP-ACP treatment.


CONCLUSIONS
The quality of the bonded resin-dentine interface produced after CPP-ACP treatment may depend on the adhesive system used.
Melbourne Dental School, University of Melbourne, 720 Swanston Street, Victoria 3010, Australia.
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Adebayo
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Burrow
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Tyas
D000134:Acid Etching, Dental / Q000379:methods; D000180:Acrylic Resins / Q000737:chemistry; D000268:Adhesiveness; D000328:Adult; D017554:Carbon Compounds, Inorganic / Q000737:chemistry; D002327:Cariostatic Agents / Q000737:chemistry*; D002364:Caseins / Q000737:chemistry*; D002614:Chelating Agents / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003775:Dental Polishing / Q000379:methods; D003804:Dentin / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry; D018130:Diamond / Q000737:chemistry; D004492:Edetic Acid / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D010756:Phosphoric Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry*; D017655:Silicon Compounds / Q000737:chemistry; D016369:Smear Layer; D013499:Surface Properties; D013997:Time Factors; D014867:Water / Q000737:chemistry
D000180:Acrylic Resins; D017554:Carbon Compounds, Inorganic; D002327:Cariostatic Agents; D002364:Caseins; D002614:Chelating Agents; C438313:Clearfil SE Bond; D003188:Composite Resins; D017220:Dentin-Bonding Agents; C498353:G-Bond; D008689:Methacrylates; D010756:Phosphoric Acids; D019279:Resin Cements; D017655:Silicon Compounds; C447032:casein phosphopeptide-amorphous calcium phosphate nanocomplex; C541508:clearfil majesty; D014867:Water; C006903:carbopol 940; D018130:Diamond; D004492:Edetic Acid; C030242:phosphoric acid; C022088:silicon carbide