In vitro microleakage of luting cements and crown foundation material.
BACKGROUND
Microleakage is a concern for the long-term prognosis of a cemented crown and foundation.


OBJECTIVE
The aims of this investigation were, first, to evaluate microleakage of zinc phosphate cement and resin-reinforced glass ionomer cement under ideal (dry) versus contaminated (wet) conditions, and second, to compare 3 foundations under both ideal and contaminated conditions.


METHODS
One hundred forty extracted molar teeth were cleaned and mounted. Tooth preparations for complete veneer cast crowns were completed with a chamfer finish line. A mesial surface class II cavity preparation 4 mm wide buccolingually and 2 mm deep was made in each tooth. Seven restorative groups were formed: amalgam/cavity varnish, amalgam/dentinal bonding agent, and composite/dentinal bonding agent, each with dry and contaminated groups, and a seventh group of class II cavity preparations without foundations. Finish lines for crown margins were refined 1.5 mm gingival to the restoration. Artificial crowns were cast in type III gold. Treatment groups were divided into 4 cement groups: dry and contaminated zinc phosphate cement and dry and contaminated resin-reinforced glass ionomer cement. The specimens were thermocycled and immersed in erythrosine B solution for 24 hours. Subsequently, they were rinsed, and their coronal portions were embedded in clear resin. Teeth were sectioned mesiodistally, and standard photomicrographs were made. The microleakage of each restoration and crown was measured.


RESULTS
The least foundation microleakage was recorded for amalgam/dentinal bonding agents (ideal group) and composite/dentinal bonding agents (ideal group). The most microleakage was observed within the group without a foundation. In cement groups, the control and experiment sides were evaluated separately but displayed the same order of finding. The least leakage was recorded with resin-reinforced glass ionomer cement (ideal group); the most microleakage was noted with zinc phosphate cement (ideal group). An interaction was demonstrated on the experimental side between cements and the foundations (P=.0001).


CONCLUSIONS
Within the experimental conditions of this study, less microleakage was recorded with resin-reinforced glass ionomer cement (ideal or contaminated) than with zinc phosphate cement (ideal or contaminated). There also was less microleakage evident with a foundation of silver amalgam or composite when a dentinal bonding agent was used under ideal conditions.
School of Dentistry, University of Iowa, Iowa City, Iowa 52242, USA. terry-lindquist@uiowa.edu
T J
TJ
Lindquist
J
J
Connolly
D000704:Analysis of Variance; D002484:Cementation; D003188:Composite Resins / Q000737:chemistry; D003442:Crowns; D003723:Dental Amalgam / Q000737:chemistry; D003736:Dental Cavity Lining; D003738:Dental Cements / Q000737:chemistry*; D003763:Dental Leakage / Q000145:classification*; D003801:Dental Veneers; D017220:Dentin-Bonding Agents / Q000737:chemistry; D004866:Equipment Contamination; D004923:Erythrosine; D005456:Fluorescent Dyes; D005899:Glass Ionomer Cements / Q000737:chemistry; D006047:Gold Alloys / Q000737:chemistry; D006801:Humans; D016018:Least-Squares Analysis; D008963:Molar; D011379:Prognosis; D019279:Resin Cements / Q000737:chemistry; D013499:Surface Properties; D013816:Thermodynamics; D019231:Tooth Preparation, Prosthodontic; D014867:Water; D015036:Zinc Phosphate Cement / Q000737:chemistry
D003188:Composite Resins; D003738:Dental Cements; D017220:Dentin-Bonding Agents; D005456:Fluorescent Dyes; D005899:Glass Ionomer Cements; D006047:Gold Alloys; D019279:Resin Cements; D014867:Water; D015036:Zinc Phosphate Cement; D003723:Dental Amalgam; D004923:Erythrosine