Effect of finishing technique on the microleakage and surface texture of resin-modified glass ionomer restorative materials.
OBJECTIVE
The purpose of this study was to evaluate the effects of wet and dry finishing/polishing procedures on the microleakage and surface texture of resin-modified glass ionomer (RMGI) restorative materials.


METHODS
Class V cavity preparations were made at the cemento-enamel junction (CEJ) on the buccal and lingual surface of 30 extracted human molars. The teeth were restored in three groups of 10 (20 preparations in each group) using Fuji II LC and Vitremer, both RMGIs, and Fuji II, a capsulated conventional glass ionomer cement (control). One restoration per tooth was finished/polished with copious applications of water and the other was finished/polished without water. All restorations were finished/polished using a sequence of four abrasive disks. Finishing/polishing was initiated according to manufacturers' instructions-immediately after light-curing Fuji II LC and Vitremer, and 15min after placement for Fuji II. The specimens were thermocycled and subjected to a silver nitrate leakage test. Each tooth was sectioned buccolingually and examined with an optical microscope at 40x to determine the extent of microleakage at enamel and dentin margins. The data were subjected to a non-parametric statistical analysis. To evaluate surface roughness after polishing, three disks each of Vitremer and Fuji II LC were fabricated in Teflon molds. One disk of each material was not finished/polished (control). The others were finished/polished using Sof-Lex abrasive disks. One specimen of each material was kept wet during all finishing/polishing procedures, while the other was kept dry. Atomic force microscopy was used to determine the average roughness (R(a)) of the specimens.


RESULTS
For each material, microleakage at the enamel margin was very slight. Leakage of the conventional glass ionomer Fuji II was severe at dentin margins. Statistical analysis indicated that both Vitremer and Fuji II LC had significantly less leakage than Fuji II, and that Vitremer had significantly less leakage than Fuji II LC (p<0.05). Leakage at enamel margins was significantly less than at dentin margins. Differences related to wet and dry polishing were not statistically significant. Profilometry data indicated that polished specimens were rougher than those cured against a Mylar strip. Wet polishing created greater surface roughness than dry polishing.


CONCLUSIONS
RMGIs rather than conventional glass ionomers should be used in Class V cavity sites to allow immediate finishing and to reduce the incidence of microleakage. Dry finishing of RMGIs with abrasive disks is recommended because it produces a smoother surface and does not contribute to microleakage. However, wet finishing of conventional glass ionomers is still recommended to avoid desiccation.
Wilder
A D
AD
Department of Operative Dentistry, School of Dentistry, University of North Carolina, 307A Brauer Hall, Chapel Hill, NC 27599-7450, USA. aldridge_wilder@dentistry.unc.edu
Swift
E J
EJ
May
K N
KN
Thompson
J Y
JY
McDougal
R A
RA
D003188:Composite Resins / Q000737:chemistry; D003737:Dental Cavity Preparation / Q000145:classification; D003743:Dental Enamel / Q000648:ultrastructure; D003763:Dental Leakage / Q000175:diagnosis*; D003775:Dental Polishing; D003793:Dental Restoration, Permanent; D003804:Dentin / Q000648:ultrastructure; D005899:Glass Ionomer Cements / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D018625:Microscopy, Atomic Force; D008963:Molar / Q000648:ultrastructure; D019279:Resin Cements / Q000737:chemistry*; D012117:Resins, Synthetic / Q000737:chemistry; D016622:Silver Staining; D018709:Statistics, Nonparametric; D013499:Surface Properties; D013816:Thermodynamics; D019237:Tooth Cervix / Q000648:ultrastructure; D014867:Water
D003188:Composite Resins; C079765:Fuji II LC cement; D005899:Glass Ionomer Cements; D019279:Resin Cements; D012117:Resins, Synthetic; C084550:Vitremer; D014867:Water; C084541:Fuji glass-ionomer lining cement