EFFECT OF TUBULE ORIENTATION IN THE CAVITY WALL ON THE SEAL OF DENTALFILLING MATERIALS - AN IN-VITRO STUDY

Dentinal tubules are oriented perpendicularly to the root canal walls hut parallel to the lateral walls of class I occlusal preparation. It was hypothesized that the contact surface area of the material map dep end on the tubule orientation in the cavity wall to which the material is applied and that the difference in contact surface may affect the seal provided by the filling material. Standard central lumens, 2.6 mm in diameter and 3 mm high, were machined in human crown or root speci mens. After removal of the smear layer with a conditioner, the specime ns in each experimental group, consisting of 20 crown and 20 root spec imens, were filled with amalgam, Fuji II glass ionomer (with or withou t varnish), or gutta-percha with Ketac-Endo root canal sealer. A modif ied fluid transport model was used to test the leakage along the filli ngs. Selected specimens were then split longitudinally and observed in a scanning electron microscope. The micrographs showed that all the t est materials were pressed into the dentinal tubules, The contact surf ace of the material was calculated to be at least 45% larger in root s pecimens than in crown specimens, depending on the depth of the tubula r penetration of the test material. The leakage results showed that al l the test materials leaked less in root specimens than in crown speci mens (P = 0.0000 for amalgam, P = 0.0374 for Fuji II with varnish, P = 0.0088 for Fuji II without varnish, P = 0.002 for gutta-percha with s ealer), It was concluded that the tubule orientation in the cavity wal l map influence the seal provided by certain dental filling materials.