Effect of post space preparation on apical seal using solvent techniques and Peeso reamers

The purpose of this study was to evaluate the effect on the apical seal of gutta-percha removal with Peeso reamers and softening agents, both immediately after obturation and one week after obturation. Sixty freshly extracted maxillary central incisors were obturated with gutta-percha and sealer using lateral condensation. In one group, post spaces were prepared with rotary instruments. In a second group, softening agents and files were used. Autoradiographic investigation using Ca⁴⁵ showed significant apical leakage in both groups when gutta-percha was removed immediately after obturation. Neither method caused significant apical leakage when post space preparation was delayed one week to allow sealers to harden.     

A comparative analysis of zinc and non-zinc alloys used in retrograde endodontic surgery. Part 1: apical sealand tissue reaction

This is a study to evaluate periapical tissue reaction and the seal of the apexes of teeth retrofilled with zinc and non-zinc silver alloys. Zinc and non-zinc silver alloy implants elicited severe inflammatory responses after 22 months. Non-zinc silver alloy showed a better seal than zinc silver alloy after 22 months.     

Subcutaneous implantation for the biological evaluation of endodontic materials

The subcutaneous implantation of Teflon tubes as carriers for endodontic materials was evaluated for its suitability as a method for the testing of the biocompatibility of these materials. Three representative types of root canal sealers were used. Tubes filled with sealers were placed in the subcutaneous tissue of 143 rats. The observation periods were 14, 30, 90, and 180 days. The occurrence of acute and chronic inflammatory' cells, presence of material in macro phages, foreign body giant cells, and vessels, demonstrated that all sealers were irritating and resorbable. The severity of the tissue response varied widely within each group. It was concluded that the implantation method was practical for the qualitative evaluation of endodontic materials, but that a ranking of biocompat- ibility of materials would be possible only for materials of considerably different toxicity.