RESUMO
An in vitro nondestructive fatigue test was applied to adhesive posts and cores made on endodontically treated human teeth. Five post-and-core systems were evaluated: one zircon oxide post, two titanium posts (with resinous or ceramic coating), and two resin-fiber posts. Each test specimen was intermittently loaded and thermocycled. The scanning electron microscope observation of sample sections showed that only the interfaces between restorative materials and dentin exhibited substantial deficiencies. The Komet ER (Brasseler) exhibited the greatest percentages of continuity at the coronal (83.88%) or the radicular (78.12%) dentin levels, while the Zircon experimental post presented insufficient adaptation to the radicular (21.25% continuity) and to the coronal (53.25% continuity) dentin. Seven of eight samples in the Komet group showed root fractures. The carbon-fiber post (Composipost) behaved satisfactorily (67.38% radicular continuity), in spite of the use of an older bonding agent formulation.
Assuntos
Dentina/efeitos dos fármacos , Técnica para Retentor Intrarradicular , Análise de Variância , Análise do Estresse Dentário/métodos , Análise do Estresse Dentário/estatística & dados numéricos , Dentina/ultraestrutura , Análise de Falha de Equipamento/métodos , Análise de Falha de Equipamento/estatística & dados numéricos , Humanos , Técnicas In Vitro , Microscopia Eletrônica de Varredura , Técnica para Retentor Intrarradicular/instrumentação , Materiais Restauradores do Canal Radicular/química , Estresse Mecânico , Propriedades de Superfície , Fraturas dos Dentes/etiologia , Raiz Dentária/lesõesRESUMO
Prosthetic treatment failures related to the biomechanical deficiencies of post and cores still represent a problem of clinical significance. To overcome the difficulties of clinical studies, numerous in vitro methods were developed to address specific properties of post-and-core restorations. Most of them, however, were based on an oversimplified mechanical testing of the restored tooth. Experience proved that the fatigue of restorative materials was a primordial factor in clinical failures. Therefore, special devices were built that stimulate the physiological masticatory cycle. Tests performed with adhesive post-and-core systems seem to indicate that materials placed in the tooth should have physical properties as close as possible to those of natural tissues. New carbon-epoxy posts appear to offer a promising solution for restoring the endodontically treated tooth.
