Penetration of a bonding agent into De- and remineralized enamel in vitro.
OBJECTIVE
To evaluate bonding penetration into different enamel substrates.


METHODS
Ten extracted human molars were mesiodistally sectioned. Buccal and lingual enamel surfaces were divided into four equal areas using sticky wax. The central two areas of each tooth (n = 20) were demineralized for 12 weeks using an acidic gel (pH 4.8). The lateral areas served as controls. After demineralization, ten specimens were remineralized in a saliva substitute for three weeks. An amine fluoride solution (Elmex Fluid) was applied on one half of each specimen before acid etching. After etching for 120 s, an enamel-bonding agent (Heliobond) containing 0.1% rhodamine was applied onto test and control areas, and was light cured for 60 s. Subsequently, the specimens were sectioned and tag length was determined using a confocal laser scanning microscope (CLSM). Results were statistically compared with ANOVA followed by Scheffe's and Bonferroni/Dunn post hoc tests.


RESULTS
With a mean penetration depth of 68 +/- 22 microm, tags in demineralized enamel were significantly longer than in other groups (p < or = 0.01). Penetration decreased significantly in remineralized areas or when fluoride was used (p < or = 0.01), but was still significantly deeper than in control sites (p < or = 0.01).


CONCLUSIONS
Penetration of an unfilled resin into enamel was considerably influenced by the degree of dental hard tissue mineralization. Penetration was increased in demineralized enamel; however, remineralized enamel also allowed good penetration of the bonding agent.
Department of Preventive Dentistry, Periodontology and Cariology, Center for Dental Medicine, University of Zürich, Switzerland. patrick.schmidlin@zzmk.unizh.ch
Patrick R
PR
Schmidlin
Matthias
M
Zehnder
Tibor
T
Pasqualetti
Thomas
T
Imfeld
Mario J
MJ
Besek
D000134:Acid Etching, Dental; D000179:Acrylates / Q000737:chemistry*; D000180:Acrylic Resins / Q000737:chemistry*; D000588:Amines / Q000737:chemistry; D000704:Analysis of Variance; D002327:Cariostatic Agents / Q000737:chemistry; D001840:Dental Bonding; D003743:Dental Enamel / Q000648:ultrastructure*; D003959:Diamines; D005456:Fluorescent Dyes; D005459:Fluorides / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D018613:Microscopy, Confocal; D019279:Resin Cements / Q000737:chemistry*; D012235:Rhodamines; D012464:Saliva, Artificial / Q000737:chemistry; D013997:Time Factors; D017001:Tooth Demineralization / Q000473:pathology*; D014089:Tooth Remineralization
D000179:Acrylates; D000180:Acrylic Resins; D000588:Amines; D002327:Cariostatic Agents; D003959:Diamines; D005456:Fluorescent Dyes; D019279:Resin Cements; D012235:Rhodamines; D012464:Saliva, Artificial; C040415:heliobond; C495399:Olaflur; D005459:Fluorides