In situ transformation of glass-ionomer into an enamel-like material.
OBJECTIVE
To assess the nature of clinically detectable alterations in glass-ionomer after long-term clinical service.


METHODS
In addition to clinical macro pictures, SEM was carried out on replicas and on two sectioned primary molars SEM-EDAX analysis was performed to determine chemical transformation in the glass-ionomer. Also with SEM-EDAX, the composition was determined of a partially removed half-year old sealant.


RESULTS
The clinically observed altered optical aspect and increased hardness could be related with surface structure changes as identified by SEM. The changed glass-ionomer showed a continuous integration with the adjacent enamel. The SEM-EDAX analysis revealed an increase of calcium and phosphorus in the surface layer, tentatively suggesting a sort of additional "mineralization" of the material. This phenomenon was only observed for restorations that had minimally 2-3 years in vivo dwell time.
Academic Centre for Dentistry Amsterdam, Universiteit van Amsterdam, The Netherlands. dental.materials@acta.nl
Raimond N B
RN
Van Duinen
Carel L
CL
Davidson
Anton J
AJ
De Gee
Albert J
AJ
Feilzer
D000293:Adolescent; D002118:Calcium / Q000737:chemistry; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002648:Child; D003743:Dental Enamel / Q000648:ultrastructure; D004577:Electron Probe Microanalysis; D005500:Follow-Up Studies; D005899:Glass Ionomer Cements / Q000737:chemistry*; D006244:Hardness; D006801:Humans; D008297:Male; D008855:Microscopy, Electron, Scanning; D008963:Molar / Q000648:ultrastructure; D044367:Phase Transition; D010758:Phosphorus / Q000737:chemistry; D010895:Pit and Fissure Sealants / Q000737:chemistry*; D013499:Surface Properties; D014094:Tooth, Deciduous / Q000648:ultrastructure
D005899:Glass Ionomer Cements; D010895:Pit and Fissure Sealants; D010758:Phosphorus; D002118:Calcium