الفهرس 
Review of LiteratureOnly 14 pages are availabe for public view
 |  | from | 102 |  |  |
| | | from | 102 | | |
Abstract
R
oot canal therapy, despite having a high degree of success, may not lead to the desired response, and failure may occur. The success of root canal treatment depends on completely cleaning and shaping, and then filling the root canal systems. When root canal therapy fails treatment options include conventional retreatment, periradicular surgery or extraction. Nonsurgical retreatment should be considered as the treatment of choice for most cases of failed endodontically treated teeth.
Several methods for removing the filling material were tested including the use of solvents, heat and mechanical instrumentation either alone or in combination with each other. In root canal retreatment, solvents are often used as an aid for removing gutta-percha. Chloroform, an organic solvent, has been shown to be the most effective when used with gutta-percha and most filling materials when compared with other solvents but it was shown to have a high toxicity.
Studies have shown that essential oils, such as eucalyptol, orange oil, grapefruit oil and turpentine oil, may be used in retreatment because they are safe and useful for dissolution of gutta-percha and root canal sealers.
During root canal retreatment, the root and coronal dentine are exposed to gutta-percha solvents deposited in canals which may alter the chemical composition of dentine surface and affect bond strength of restorative materials to dentine. However, there is little or no information about the effects of various gutta-percha solvents used on the bond strength of sealers to root dentine.
The goal of this study was to compare the cleanliness and the push-out bond strength of resin-based endodontic sealer to root dentine exposed to different essential oils gutta-percha solvents 5 min. The null hypothesis is that various gutta-percha solvents do not affect the bond strength of several root canal sealers.
In this study 64 teeth were collected, access cavity was done and the canals were prepared and filled with gutta-percha and AHplus sealer, Then stored for 2 weeks to let the sealer reached its setting time.
In the present study, 48 teeth were exposed to two different organic solvents and chloroform, while the 16 remaining teeth obturation was removed using H-files only. Then the 64 teeth were divided randomly into two groups 32 teeth each; group I teeth were split longitudinally and examined with scanning electron microscope for the remaining obturation material. While group II teeth were re-obturated then split horizontally into 3 specimens coronal, middle and apical and placed over a supporting jig of the universal push out test machine.
The load was applied with an indentor until debonding took place. Samples were examined under a stereomicroscope to verify which type of failure took place in every specimen. Results were collected, tabulated and statistically analyzed.
Results of this study according to cleanliness effect showed that there was no statistically significant difference between the control group, chloroform group, orange oil and grapefruit groups at the middle, coronal level, While there was a significant difference between the four groups at apical levels where the control groups showed the statistically significantly highest mean debris scores.
Data from the push-out testing machine was collected and statistically analyzed. Results showed that there was a statistically significant difference between the control group and the other three groups where the chloroform group showed the highest mean push-out bond strength at all levels followed by orange oil and grapefruit oil groups.
Based on the results obtained and discussed, following conclusions were drawn from the present study:
1. None of the solvents could eliminate gutta-percha residues completely from the root canal.
2. The maximum amount of cleanliness was observed in the coronal third and the least amount in the apical third in all tested groups.
3. Solvency power of orange oil to gutta-percha/sealer was similar to chloroform, confirming that orange and grapefruit oils can be used as an alternative solution to aid in endodontic retreatment.
4. Gutta-Percha solvents had an adverse effect on bond strengths of resin sealers to root canal dentin.