Particles and molecules in endodontic leakage

Abstract

It is assumed that above a critical level, microleakage causes periapical disease and jeopardizes periapical tissue repair. The purpose of this investigation was first to find out to what degree obturation prevents leakage of bacteria-sized particles or large protein molecules, and second if leakage of the commonly used dye methylene blue is comparable with that of a small bacterial metabolic product of similar molecular size. Sections, 9 mm long, obtained from 46 extracted human incisor roots had their root canals prepared in a standardized manner and obturated in four experimental ways using gutta-percha. The root sections were mounted in the middle of tubes that were closed at both ends with rubber membrane stoppers, which permitted sampling from the apical reservoir. The coronal reservoir was filled with a solution of 1 mg/ml latex beads, 4 micrograms/ml endotoxin, 0.5 per cent butyric acid, 0.1 per cent valeric acid and 0.1 per cent methylene blue water. After 1 and 2 weeks, samples were taken from the apical reservoir and tested for the presence of latex beads by phase-contrast microscopy, for endotoxin with a limulus lysate test, for butyric acid with gas-chromatography and for methylene blue with spectrophotometric analysis. Leakage of bacteria-sized particles and large-sized protein molecules could be prevented only when both sealer and pressure were used in obturating root canals with gutta-percha. Leakage of butyric acid proved to be comparable with leakage of methylene blue; microleakage of these small molecules could not be prevented in this study whatever method of filling was used.

Apical seal of root canals with gutta-percha points with calcium hydroxide

“…Some researchers believe that it is difficult to evaluate the biological significance of major or minor dye leakage (19). The molecular weight of the bacterial endotoxin is greater than that of methylene blue (20). When it is evaluated directly, the leakage of endotoxin is less than the minor leakage of methylene blue (19).…”

Microbial leakage of MTA, Portland cement, Sealapex and zinc oxide-eugenol as root-end filling materials

“…The methodology employed in this study was based on that of previous investigations using the in vitro microbial leakage model (2,4,5). Despite the restraint of leakage study methodology (5), dye and radioisotope leakage models have limitations such as the molecular size of most dye particles being smaller than that of bacteria and these models do not reproduce the interactions between microbial and non-microbial tracers (17). Therefore, several studies have pointed out that microbial leakage tests should preferably be used (18).…”

The effect of irrigation solutions on the apical sealing ability in different root canal sealers

“…However, dyes can chemically interact with sealing materials or dentin, which may influence its diffusion or promote tracer decoloration, impairing an adequate marginal leakage evaluation. 8,11 Because of their small molecular size, 12 dye penetration has been used as a dependent measure of sealing ability; however, whether dyes mimic penetration of microorganisms or antigens is still not known. 13 Moreover, entrapped air in the canal filling may falsify dye penetration depth, 14,15 suggesting the application of vacuum techniques or centrifugation, 15,16 even if previous studies 17,18 showed that dye penetration did not differ whether centrifugation was applied or not.…”