Authors: Tanzilli JP, Nevins AJ, Borden BG.
Title: A histologic study comparing Hydron and gutta-percha as root canal filling materials in monkeys.
Journal: J Endod
Date: Sep 1981
Citation: 7(9):396-401
Category: Obturation
Evidence-based Ranking: 5
Purpose/Objectives: To evaluate the histological response in the periapical tissues of monkeys to Hydron (a hydrophilic methacrylate based plastic) and gutta-percha.

Materials & Methods: 26 max. and mand. incisors in monkeys were prepared and placed into 4 groups. Group 1 - 10 teeth were over-instrumented and overfilled with Hydron; Group 2 - 4 teeth were over-instrumented and overfilled with gutta-percha and sealer; Group 3 - 7 teeth were under-instrumented and under-filled with Hydron; Group 4 - 5 teeth were under-instrumented and under-filled with gutta-percha and sealer. After 6 months the monkeys were euthanized and bone sections were prepared for histological examination. The analysis included the following criteria – apical radiolucency, apical resorption, pulpal apical calcification, resorption of material within canal, presence of lymphocytes, and presence of macrophages.

Results: The most significant finding was the presence of a severe inflammatory reaction with a predominance of macrophages in the lesion in the Hydron overfill group. This is possibly the start of a self-perpetuating lesion in that the macrophages that had engulfed the foreign material were not being removed from the lesion. The gutta-percha overfill group also had a severe inflammatory reaction but the predominate cells were lymphocytes which is less suggestive of a self perpetuating lesion.

Author’s Conclusion: While more studies need to be done Hydron is probably not a suitable obturation material.

Validity of Conclusion: No statistics but based on the study the conclusion is valid.