Simulated oral environment and microleakage of Class II resin-based composite and sandwich restorations.
OBJECTIVE
To evaluate the influence of the simulation of intra-oral conditions on the interfacial microleakage of Class II composite restorations.


METHODS
40 Class II cavities were prepared on freshly extracted human third molars and filled with a direct resin composite technique (SBMP+ + Z100) or open sandwich technique (Fuji II LC + SBMP+ + Z100). Extreme intra-oral conditions were simulated (35 degrees C/95% of relative humidity) and compared with ambient conditions (20 degrees C/40% RH). After thermocycling (2,000 cycles--5 and 55 degrees C), 2 hours immersion in silver nitrate aqueous solution and embedding into epoxy resin, samples were longitudinally sectioned. The extent of microleakage was expressed as a percentage of silver penetration of enamel and dentin interfaces. The influences of environmental conditions and restorative technique were evaluated by a two-way ANOVA and the comparison between the different groups with a Fisher PLSD test.


RESULTS
In comparison with values obtained in ambient conditions, the simulation of extreme environmental conditions resulted in increased silver penetration percentages for direct resin composite restorations. On the contrary, the open sandwich technique, using resin-modified glass-ionomer cements, did not seem sensitive to excessive "temperature/relative humidity" parameters. Restorations made with resin-modified glass-ionomer cements used in the open sandwich technique appear to be more tolerant towards "temperature/relative humidity" parameters, which simulated intra-oral conditions, compared with modern adhesive systems.
Besnault
Catherine
C
Groupe de Recherches Biomatériaux, Faculté de Chirurgie Dentaire, Université Paris V, 1 rue Maurice Arnoux, F-92120 Montrouge, France. cath.besnault@wanadoo.fr
Attal
Jean-Pierre
JP
D000704:Analysis of Variance; D001831:Body Temperature / Q000502:physiology; D003188:Composite Resins / Q000737:chemistry*; D003743:Dental Enamel / Q000473:pathology; D003763:Dental Leakage / Q000517:prevention & control*; D003793:Dental Restoration, Permanent / Q000145:classification* / Q000379:methods; D003804:Dentin / Q000473:pathology; D005899:Glass Ionomer Cements / Q000737:chemistry; D006801:Humans; D006813:Humidity; D008422:Materials Testing / Q000379:methods; D008954:Models, Biological; D009055:Mouth / Q000502:physiology; D019279:Resin Cements / Q000737:chemistry*; D012117:Resins, Synthetic / Q000737:chemistry; D012822:Silicon Dioxide; D016622:Silver Staining; D013696:Temperature; D013997:Time Factors; D015040:Zirconium
D003188:Composite Resins; C079765:Fuji II LC cement; D005899:Glass Ionomer Cements; D019279:Resin Cements; D012117:Resins, Synthetic; C084018:Scotchbond Multi-Purpose; C083568:Z100 composite resin; D012822:Silicon Dioxide; D015040:Zirconium