title: Influence of thermal stress on marginal integrity of restorative materials.
abstract: The aim of this study was to evaluate the influence of thermal stress on the marginal integrity of restorative materials with different adhesive and thermal properties. Three hundred and sixty Class V cavities were prepared in buccal and lingual surfaces of 180 bovine incisors. Cervical and incisal walls were located in dentin and enamel, respectively. Specimens were restored with resin composite (RC); glass ionomer (GI) or amalgam (AM), and randomly assigned to 18 groups (n=20) according to the material, number of cycles (500 or 1,000 cycles) and dwell time (30 s or 60 s). Dry and wet specimens served as controls Specimens were immersed in 1% basic fuchsine solution (24 h), sectioned, and microleakage was evaluated under x40 magnification. Data were analyzed by Kruskal-Wallis and Mann-Whitney tests: thermal cycling regimens increased leakage in all AM restorations (p<0.05) and its effect on RC and GI restorations was only significant when a 60-s dwell time was used (p<0.05). Marginal integrity was more affected in AM restorations under thermal cycling stress, whereas RC and GI ionomer restoration margins were only significantly affected only under longer dwell times.
authors.affiliation: Dental School of Piracicaba, State University of Campinas, Piracicaba, SP, Brazil.
authors.forename: Maximiliano Sérgio
authors.initials: MS
authors.lastname: Cenci
authors.forename: Tatiana
authors.initials: T
authors.lastname: Pereira-Cenci
authors.forename: Tiago Aurélio
authors.initials: TA
authors.lastname: Donassollo
authors.forename: Leandro
authors.initials: L
authors.lastname: Sommer
authors.forename: André
authors.initials: A
authors.lastname: Strapasson
authors.forename: Flávio Fernando
authors.initials: FF
authors.lastname: Demarco
mesh_terms: D000818:Animals; D002417:Cattle; D004396:Coloring Agents; D003188:Composite Resins / Q000737:chemistry; D003723:Dental Amalgam / Q000737:chemistry; D003737:Dental Cavity Preparation / Q000145:classification; D003739:Dental Cementum / Q000648:ultrastructure; D003743:Dental Enamel / Q000648:ultrastructure; D003763:Dental Leakage / Q000145:classification; D018772:Dental Marginal Adaptation; D003764:Dental Materials / Q000737:chemistry*; D003793:Dental Restoration, Permanent; D003804:Dentin / Q000648:ultrastructure; D005899:Glass Ionomer Cements / Q000737:chemistry; D011897:Random Allocation; D012394:Rosaniline Dyes; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors
chemical_list: D004396:Coloring Agents; D003188:Composite Resins; D003764:Dental Materials; D005899:Glass Ionomer Cements; D012394:Rosaniline Dyes; C025485:basic fuchsin; D003723:Dental Amalgam