Tf. Watson et al., CONFOCAL MICROSCOPIC OBSERVATION OF STRUCTURAL-CHANGES IN GLASS-IONOMER CEMENTS AND TOOTH INTERFACES, Biomaterials, 19(6), 1998, pp. 581-588
This study aimed to develop techniques to allow dynamic imaging of a c
avity before, during and after placement of glass-ionomer restorative
materials. Cavities were cut in recently extracted third molars and th
e teeth longitudinally sectioned. Each hemisected tooth surface was pl
aced in green modelling compound at 90 degrees to the optical axis of
the microscope. The cavity surface was imaged using a video rate confo
cal microscope in conjunction with an internally focusable microscope
objective. The sample on the stage was pushed up to the objective lens
which 'clamped' the cover glass onto it. Water, glycerine or oil was
placed below the coverglass, with oil above. Internal tooth structures
: were imaged by changing the internal focus of the objective. The res
torative material was then placed into the cavity. Video images were s
tored either onto video tape or digitally, using a frame grabber, comp
uter and mass memory storage. Software controls produced time-lapse re
cordings of the interface over time. Preliminary experiments have exam
ined the placement and early maturation of conventional glass-ionomer
cements and a syringeable resin-modified glass-ionomer cement. Initial
contact of the cement matrix and glass particles was visible as the p
lastic material rolled past the enamel and dentine: before making a bo
nd Evidence fnr water movement from the dentine into the cement has al
so been seen. After curing the early dimensional changes in the cement
s due to water flux were apparent using the time-lapse facility. This
new technique enables examination of developing tooth/restoration inte
rfaces and the tracking of movement in materials. (C) 1998 Published b
y Elsevier Science Ltd. All rights reserved.