Evaluation of microleakage in cervical margins of various posterior restorative systems.
OBJECTIVE
The purpose of this in vitro study was to evaluate the microleakage and dye penetration patterns of various restorative systems in the cervical margins of Class II cavities using the dye penetration technique.


METHODS
Ninety bovine incisors were selected and part of the crown was sectioned producing a standardized occlusogingival margin of 4 mm. Standardized Class II box cavities were designed on the mesial (MO) and distal (OD) surfaces with the gingival margin in dentin. The cavities were randomly divided into six groups (n = 30): group 1 (control), Etch & Prime 3.0 (Degussa AG) + Definite (Degussa AG); group 2, Prime & Bond NT (Dentsply De Trey) + Definite; group 3, Etch & Prime 3.0 + flowable composite resin Wave (SDI) + Definite; group 4 (control), Prime & Bond NT + TPH Spectrum (Denstply De Trey); group 5, Etch & Prime 3.0 + TPH Spectrum; group 6, Prime & Bond NT + Wave + TPH Spectrum. After they were finished and polished, the specimens were subjected to 1500 thermal cycles in baths of 5 degrees+/-2 degrees C and 55 degrees+/-2 degrees C with 60 seconds of dwell time for each bath. After the thermocycling, the specimens were sealed with acid-resistant varnish, leaving a 1-mm window around the cervical margin interface, and immersed in 2% methylene blue buffered solution for 4 hours. Then the specimens were sectioned longitudinally in half and qualitatively evaluated under stereomicroscopy at 45 times magnification, using ranked scores for the dentin cervical margin (0-4). The dye penetration pattern (adhesive or dentinal) was also evaluated. The data were subjected to a reproducibility kappa test, and the mean of the three examiners' scores was analyzed by the Kruskal-Wallis nonparametric test and a multiple comparison nonparametric test. Fisher's exact test was used to evaluate the dye penetration pattern.


RESULTS
The rank sums of the groups were expressed in decreasing order: group 4, 67.23a; group 3, 72.58ab; group 6, 78.43ab; group 5, 93.19bc; group 2, 112.97c; group 1, 113.52c. (Statistically significant differences are expressed by different superscript letters.) The results indicate that none of the systems used in this study was able to impede microleakage, and that the use of a flowable resin decreases the values of leakage only for Definite composite resin. The dye penetration pattern for the groups that used Prime & Bond NT was predominantly dentinal, whereas the pattern for Etch & Prime 3.0 groups was adhesive.


CONCLUSIONS
An ormocer-based resin that was developed to improve the physical properties of composite resin and a self-etching primer adhesive system obtained higher values of microleakage compared with a one-bottle adhesive system and a microhybrid composite resin. The flowable composite resin decreased the values of microleakage only for the ormocer-based resin.
Bedran de Castro
Ana Karina Barbieri
AK
Department of Restorative Dentistry, School of Dentistry of Piracicaba, University of Campinas, Brazil.
Pimenta
Luiz André Freire
LA
Amaral
Cristiane Mariote
CM
Ambrosano
Gláucia Maria Boni
GM
D000818:Animals; D002417:Cattle; D004396:Coloring Agents; D003188:Composite Resins / Q000737:chemistry*; D003737:Dental Cavity Preparation / Q000145:classification; D003743:Dental Enamel / Q000648:ultrastructure; D003763:Dental Leakage / Q000145:classification*; D018772:Dental Marginal Adaptation; D003775:Dental Polishing; D003793:Dental Restoration, Permanent / Q000145:classification* / Q000379:methods; D003804:Dentin / Q000648:ultrastructure; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D011756:Diphosphates / Q000737:chemistry; D000431:Ethanol / Q000737:chemistry; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D008751:Methylene Blue; D011109:Polymethacrylic Acids / Q000737:chemistry; D011897:Random Allocation; D015203:Reproducibility of Results; D012833:Siloxanes / Q000737:chemistry; D013223:Statistics as Topic; D018709:Statistics, Nonparametric; D013499:Surface Properties; D013729:Terpenes / Q000737:chemistry; D013816:Thermodynamics; D013997:Time Factors
D004396:Coloring Agents; D003188:Composite Resins; C421785:Definite composite resin; D017220:Dentin-Bonding Agents; D011756:Diphosphates; C121187:Etch&Prime; D008689:Methacrylates; D011109:Polymethacrylic Acids; C425843:Prime and Bond NT; D012833:Siloxanes; C420128:Spectrum composite resin; C113300:TPH hybrid; D013729:Terpenes; C111840:flowable hybrid composite; D000431:Ethanol; D008751:Methylene Blue