Francesco Somma

Quality of thermoplasticized and single point root fillings assessed by micro-computed tomography.

AIM To evaluate ex vivo the quality of root fillings completed by two thermoplasticized gutta-percha techniques (Thermafil and System B) and a cold gutta-percha technique (single point) by μCT analysis. METHODOLOGY A total of 30 freshly extracted human single-rooted permanent teeth were selected. Root canals were prepared with ProTaper Universal instruments and then randomly divided into three groups (n = 10) depending on the filling technique. In group 1, canals were filled with a single-point technique; group 2 was filled with Thermafil; in group 3 System B was used. In group 1 and group 3, the root filling was performed using ProTaper Universal gutta-percha points, in group 2 Thermafil obturators were used; AH-Plus sealer was used in all groups. Assessment of the root filling was carried out by μCT, using a desktop X-ray micro focus CT scanner. Percentage of root canal filling materials and voids was calculated for each specimen. Data were statistically analysed using Kruskal-Wallis test (P < 0.05). RESULTS Mean percentages of filling materials were 98.379 ± 1.204 in the single-point group, 99.023 ± 1.457 in Thermafil group, and 98.167 ± 3.432 in System B group. No statistically significant difference was found amongst the groups. CONCLUSION All techniques produced comparable results in terms of percentage of filling and void distribution.

Influence of surface remodelling using burs on the macro and micro surface morphology of anatomically formed fibre posts

AIM To evaluate the effect of modifying preformed fibre-reinforced composite (FRC) endodontic posts on their surface morphology and to determine how this procedure affects the integrity of the posts. SUMMARY Surfaces of 10 preformed glass-fibre posts (group 1) and carbon-fibre posts (group 2) were compared with those of individually formed glass-fibre posts (group 3). Ten FRC posts were modelled in order to give them a shape as close as possible to the anatomy of oval root canals. Starting from a preformed cylindrical fibre post 2.5 mm in diameter, it was modelled in such a way as to passively occupy the entire post-space length, using a cast previously created as a guide. Microscopic analyses (optical stereomicroscope and scanning electron microscope) of the post surfaces revealed similar features in all three groups. All posts had regular surfaces after cutting with a diamond bur. Smear layer mainly attributable to the cutting procedures covered the cut surface of some specimens. In conclusion, modulation of a fibre post using a diamond-coated bur did not show a loss of integrity of the post. *Because of the importance of micromechanical retention, the surface integrity of fibre posts may be important for adhesion between post and composite resin. *Modification of a fibre post using a diamond-coated bur did not damage the surface integrity of the posts. *Fibre posts can be ground to a different shape without losing their surface integrity, resulting in posts with a surface that is not visibly different from unmodified commercially available fibre posts.

A new software for dimensional measurements in 3D endodontic root canal instrumentation

The main issue to be faced to get size estimates of 3D modification of the dental canal after endodontic treatment is the co-registration of the image stacks obtained through micro computed tomography (micro-CT) scans before and after treatment. Here quantitative analysis of micro-CT images have been performed by means of new dedicated software targeted to the analysis of root canal after endodontic instrumentation. This software analytically calculates the best superposition between the pre and post structures using the inertia tensor of the tooth. This strategy avoid minimization procedures, which can be user dependent, and time consuming. Once the co-registration have been achieved dimensional measurements have then been performed by contemporary evaluation of quantitative parameters over the two superimposed stacks of micro-CT images. The software automatically calculated the changes of volume, surface and symmetry axes in 3D occurring after the instrumentation. The calculation is based on direct comparison of the canal and canal branches selected by the user on the pre treatment image stack.