Sk. Sidhu et Tf. Watson, INTERFACIAL CHARACTERISTICS OF RESIN-MODIFIED GLASS-IONOMER MATERIALS- A STUDY ON FLUID PERMEABILITY USING CONFOCAL FLUORESCENCE MICROSCOPY, Journal of dental research, 77(9), 1998, pp. 1749-1759
The tooth interface with resin-modified glass-ionomer cements (RM GICs
) is poorly understood. This study examined the interface, especially
with dentin. Cervical cavities in extracted teeth were restored with F
uji II LC, Vitremer, Photac-Fil, or a conventional GIG, Fuji Cap II. F
luorescent dye was placed in the pulp chambers for 3 hrs before the sp
ecimens were sectioned. Examination of the tooth/material interface wi
th a confocal microscope showed that dye uptake by the restoration var
ied among materials. A ''struetureless'', non-particulate, highly-stai
ned layer of GIC was observed next to dentin in Fuji Il LC. This layer
varied in width, was prominent where the dentin tubules were cut ''en
d-on'' and in areas closer to the pulp, and was not seen adjacent to e
namel. Vitremer showed minimal dye uptake, and the ''structureless'' l
ayer was barely discernible. Photac-Fil showed more uniform uptake and
absence of this layer. Cracking of enamel was also noted with these m
aterials. The conventional GIC did not show any dye uptake, presence o
f a ''structureless'' layer, or enamel cracking. We elucidated the pot
ential mechanisms involved in the formation of a ''structureless'' int
erfacial layer in Fuji II LC by studying the variables of cavity desig
n, surface pre-treatment, water content of the tooth, time for it to d
evelop, early finishing, and coating of the restoration. This layer, t
he ''absorption layer'', is probably related to water flux within the
maturing cement, depending on environmental moisture changes and commu
nication with the pulp in a wet tooth. The ''micropermeability model''
was useful in this study of the interfacial characteristics of RM GIC
s.