The effect of tooth loss on the TM-joint articular eminence inclination.

The inclination between the posterior wall of the articular eminence and the referential plane (Frankfurt line) was measured on 137 dry skull specimens (78 with complete dental arches and 59 edentulous). Both left and right joints were measured using direct craniometric method. The results were compared with respect to the loss of teeth, side and sex. A large range of measured values of the eminence inclination shows great individual differences, so that the mean values can have only orientational significance. The mean value of eminence inclination for all measured specimens was 61.9 angular degree. The difference between the two groups established upon dental status is very small and without any statistical significance (P > 0.05). The right joint shows a slightly steeper eminence inclination compared to the left one, but without any statistical significance (P > 0.05). Asymmetry between the right and left joint appears almost as a rule, while maximum measured differences reach up to 33 degrees, with mean absolute difference of 6.9 degrees. The group of edentulous specimens shows a greater symmetry and less differences between the left and right joint, which indicates that different bimechanical conditions in the joint, due to tooth loss might lead to remodellation of the articular eminence. The eminence inclination was significantly steeper in male specimens in all subgroups (P < 0.001), which confirms sexual dimorphism.

Bond strengths of two dental bonding systems.

A new bonding system named Kevloc has been introduced. It is based on acrylization of the metal surface with the goal of preventing the occurrence of a marginal gap between the metal and the resin. The purpose of this investigation was to determine the values of the shear bond strength achieved using the Kevloc technique on Ag-Pd (Auropal SE) and Co-Cr (Basil S) alloys and to compare them with those obtained with the OVS technique. The shear bond strengths were measured with the Smitz-Schulmayer shear test in a universal testing machine for polymer materials. A microscope image analyzer was used to measure the thickness of bonding layers and to reveal the possible occurrence of the marginal gap with both techniques. No marginal gap was detected with either technique. Kevloc provided better results than OVS only in a group of specimens tested after polymerization. Immersion in water and thermocycling reduced the initially high bond strength values of Kevloc specimens, whereas the bond strength values of OVS specimens remained unchanged regardless of which aging treatment was used. Microscopic examination did not reveal the existence of the marginal gap for either bonding system. According to the results obtained, it can be concluded that the Kevloc bonding system does not provide better shearing bond strength than the OVS bonding system.