Title: Human Saliva Penetration of Coronally Unsealed Obturated Root Canals
Author: Khayat et al.
Journal: JOE Vol 19, No. 9, September 1993
To determine the length of time for bacteria present in natural human saliva to penetrate through the entire root canal system obturated by lateral and vertical condensation techniques in an in vitro model.
Materials and Methods:
- Forty mandibular and maxillary molar teeth were stored in 10% formalin and kept moist prior and during the experiment.
- Calcified teeth or teeth with multiple canals in the distal or palatal roots were eliminated.
- Apical foramen of each root was enlarged to #40 file, the rest of canal was cleansed and shaped using step-back technique.
- Irrigation between each file with done with 2mL of 5.25% NaOCl
- Teeth were randomly assigned to groups:
- 15 teeth obturated with GP and Roth’s sealer using a vertical condensation technique.
- 15 teeth obturated with GP and Roth’s sealer using lateral condensation technique.
- 5 teeth were obturated with single gutta percha cone without any sealer (positive control).
- 5 roots were obturated with gutta percha and Roth sealer using lateral condensation technique (negative control)
- To obtain standardized length of filling the coronal portion of gutta percha was removed so 10mm of filling material remained in each canal.
- Teeth placed in a sterilized apparatus that would indicate the number it takes for entire root canal to become contaminated by measuring the turbidity of trypticase soy broth.
- Saliva was added ever other day then replenished every 2 days.
- Leakage was confirmed by placing .1mL of India ink into access cavity of each tooth.
- All roots in the positive control group caused broth turbidity within 48 hours, in contrast, broth in the negative control group remained clear throughout the experimental period.
- Student’s t-test showed no significant difference between the lengths of time for contamination in lateral versus vertical condensation groups (p=0.508)
- Canals obturated with lateral condensation technique and vertical condensation technique were 28.8 +/- 4.7 days and 25.4 +/- 13.6 days, respectively.
- The results of the positive control group are a confirmation of studies by Marshall and Massler, Evans and Simon, and Skinner and Himel who showed that sealers are needed to improve the canal seal.
- Motility of bacteria is not an important factor for recontamination of an exposed obturated root canal system.
- Further studies including in vivo animal models simulating clinical conditions are needed to investigate the rate of coronal leakage in unsealed and exposed obturated root canals.