Measurement of Adhesion of Endodontic Sealers to Dentin
Tagger, Tagger, Tjan, and Bakland
Comparison Between Two Clinical Procedures for Bonding Fiber Posts into a Root Canal: A Microscopic Investigation
Vichi, Grandini, and Ferrari
Electronic Detection of Root Canal Constrictions
Oishi, Yoshioka, Kobayashi, and Suda
Measurement of Adhesion of Endodontic Sealers to Dentin
Michael Tagger, DMD, MS, Etty Tagger, DMD, Anthony H. L. Tjan, Dr Dent, DDS, and Leif K. Bakland, DDS
The bond strength of root canal sealers to dentin seems to be an important property for maintaining the integrity of the seal of root-canal fillings. In the few studies published, various assessment methods were used so quantitative comparison is not possible. The purpose of this study was to develop an effective and easily reproducible model and to test it with nine contemporary, commercially available endodontic sealers. After slicing off the coronal 2 mm of extracted third molars, the exposed dentin served as test surfaces. The teeth were fixed with plaster in 1-inch phenolic rings. Five-mm long sections of polyethylene tubing, filled with freshly mixed sealer, were placed on the dentin and tested for shearing bond strength after setting. A custom-made holder allowed the rings to be attached to an Instron machine, activated at a cross-arm speed of 0.5 mm/min. The mean bond strength, ranged from 0 to 4.9 Mpa. The sealers were ranked and those that did not differ statistically in their bond strength were grouped together. This model provides a simple and reproducible means for measuring the in vitro bond strength of endodontic sealers.
Comparison Between Two Clinical Procedures for Bonding Fiber Posts into a Root Canal: A Microscopic Investigation
Alessandro Vichi, DDS, Simone Grandini, DDS, and Marco Ferrari, MD, DDS, PhD
The purpose of this study was to evaluate the influence of two brushes used as carriers of a primer-adhesive solution as to the formation of resin tags, adhesive lateral branches, and a hybrid layer when used to bond translucent fiber posts. Twenty endodontically treated teeth, extracted for periodontal reasons, were used. The samples were randomly divided into two groups of 10 samples each (Group 1: Microbrush + Scotchbond 1 + Rely X ARC resin cement; Group 2: small plastic brush + Scotchbond 1 + Rely X ARC resin cement). The adhesive system and resin cement were used strictly following manufacturers’ instructions. The priming-adhesive solution of the one-bottle system was light-cured before placing the resin cement and the post. Twenty translucent fiber posts were used. After luting procedures, root samples were processed for SEM observations. The adhesive system showed a resin dentin interdiffusion zone (RDIZ), resin tag, and adhesive lateral branch formation, Microscopic examination of restored interfaces of group 1 showed a higher percentage (p < 0.05) of RDIZ than those found in samples of group 2. In group 1 samples, RDIZ morphology was well detectable and uniform in all thirds of the root canals. In group 2, RDIZ was not visible in the apical third. No statistically significant differences were found among the two groups coronally and at the middle third, but the apical third of group 1 showed significantly more resin tag formation than group 2. The characteristic reverse cone shape of resin tags was always noted in the coronal and middle third of the root canals of both groups and in the apical third of group 1. In the apical third of group 2 root canals, the resin tags showed a less uniform morphology and a shorter length than those found in the other observed thirds.
Electronic Detection of Root Canal Constrictions
Asako Oishi, DDS, Takatomo Yoshioka, DDS, PhD, Chihiro Kobayashi, DDS, PhD, and Hideaki Suda, DDS, PhD
The aim of this study was to investigate the possibility of detecting root canal constrictions by using an apex locator. Seventy impenetrable canals in extracted human teeth were used. Based on contact microradiographic findings, they were divided into three groups: group A (constricted within 3 mm of the radiographic apex, 23 canals), group B (nonconstricted within 3 mm of the radiographic apex, 28 canals), and group C (constricted more than 3-mm short of the radiographic apex, 19 canals). Electrical impedances at two different frequencies (8 kHz and 0.4 kHz), as well as the meter values of the Root ZX were recorded at the position where a file tip could reach. The impedance ratios (Z8kHz:Z0.4Hz) and the meter values of the Root ZX showed a statistically significant difference between groups A and B. It was suggested that the Root ZX might be useful for detecting root canal constrictions.