فهرست مطالب golnaz hadidi

Removing cement-retained implant-supported crowns for repair or modification is one of the challenges in dental treatments. Using an access cavity in the crown to reach the abutment screw is one of the procedures proposed for recovering cement-retained dental implants. This study aimed to evaluate the retention rate of crowns having access cavity in a cemented-retained implants-supported prosthesis.

In this laboratory study, 60 casting metal crowns were created and separated into two groups (n=30 per group); with and without access cavity. The crowns were created using the Pro Dent 3D printer and the samples were linked to the universal testing equipment to analyze the retention rate after cementing with temp bond cement. Data were analyzed in SPSS V16 using the Kolmogorov-Smirnov test to determine the normality of data distribution and the t-test to compare the values between the two groups.

The mean retention in control group was 42.641±8.91.67 Newton, whereas it was 40.876±7.76333 Newton in crowns with access cavity. The rates were not significantly different between the two groups (P>0.05).

Preparing an access cavity in the crown has no effect on the retention of cement-retained implant-supported crowns. Therefore, cement-retained implant-supported crowns with retrievability characteristics can provide several benefits.

This study aimed to assess the dentin adaptability of a certain type of fluoride varnish, as a novel root canal sealer, in comparison with AH-Plus sealer.

Twenty-four extracted single-rooted, single-canal human permanent teeth with straight and fully formed roots and no internal calcification, resorption or cracks, were selected and decoronated such that the remaining root length was 14 mm in all teeth. Root canals were prepared using the Mtwo rotary file system according to the manufacturer's instructions and filled with gutta-percha and either AH-Plus (n=12) or fluoride varnish (n=12) via the lateral compaction technique. Each root was then sectioned at 4 and 8 mm distances from the apex for evaluation under a scanning electron microscope (SEM). The gap size between the sealer and dentin was measured. Statistical analysis was performed using the Kolmogorov-Smirnov test and t-test with the significance level set at 0.05.

The mean gap size was 14.407±1.402 µm and 8.342±0.694 µm in the roots obturated with AH-Plus and fluoride varnish sealers, respectively. The t-test revealed a statistically significant difference (P<0.001) in this regard between the two groups.

Fluoride varnish, as a root canal sealer, has a superior adaptation to dentinal canal walls compared to the AH-Plus sealer.