| Abstract: | Fifty extracted maxillary central incisors with the crowns removed 1 mm coronal to the labial cementoenamel junction were endodontically treated. Post spaces were made 7 mm into the roots prior to cementing a 13-mm post with zinc phosphate cement. Twenty-five of the teeth were restored using a #6 (0.060-inch) Para-Post, and the remaining 25 teeth were restored with a #6 Para-Post Plus. Three core buildup materials, Ketac-Silver, Miracle Mix, and Tytin alloy were used in conjunction with the posts. Cast gold copings 10 mm in height with 1 mm collar on the root were cemented to the buildups. The teeth were loaded to failure at 130 degrees to the long axis of the root from the lingual with an Instron testing machine. The mean failure load of all of the teeth in this study was 21.6 kg. All of the teeth failed when the posts dislodged from the canals. The Para-Post Plus was not significantly more retentive than the Para-Post. No failures occurred within the buildup materials. No significant differences were demonstrated between the mean failure loads of the different buildup materials. Increased buccolingual root diameter, however, had a positive correlation (r = 0.46) with higher failure loads which was statistically significant (p less than 0.001). |
