Effect of ultrasonic vibration on the retention of adhesively luted intra-radicular posts.

The aim of this study was to determine the effect of prolonged ultrasonic vibration on tensile force necessary to dislodge two different post types luted with an adhesive resin. Extracted human canine teeth were decoronated and root-filled. Either a ceramic or stainless steel intra-radicular post was luted into each root with resin-based cement. Half the samples in each group were randomly assigned to be subjected to ultrasonic vibration of the post (test group), the remaining samples did not receive vibration (control group). The tensile force required to dislodge each post was then determined in a universal testing machine. The mean force required to dislodge the stainless steel posts in the control group was 510.1N (SD 170.6) and in the 'treatment' group it was 539.5N (SD 163.3). For the ceramic posts in the control group the mean force was 447.8N (SD 165.5) and in the 'treatment' group it was 473.9N (SD 137.8). There was no statistical difference between the groups (p = 0.597). Within the limitations of this in-vitro study, the results cast doubt on the ability of application of ultrasonic vibration to displace/loosen intra-radicular posts luted with a resin-based cement.