A Comparative Analysis of Microleakage of Roots Filled with Different Obturation Techniques and Materials-an in Vitro Study

论文摘要

Background:Endodontic therapy, over a period of time, has developed into an art and science to retain grossly carious, infected and mutilated teeth whenever possible, hence valuing each tooth more than a diamond; and increasing its longevity in the mouth to the greatest possible extent. The primary objective of a root canal therapy is to remove the organic and inorganic substances and also microorganisms to achieve a perfect seal at the apical region. The necessity to provide a perfect seal at the apical region as well as filling of accessory canals have brought forth many dynamic changes in obturation techniques and materials used as sealers.Gutta-percha has been used for root canal filling for more than a century. Many techniques have been introduced over the years for efficient and effective filling of the root canal space with gutta-percha. The E & Q Plus system （Meta Biomed Co., Ltd., UK） is a relatively new introduction to the endodontic armamentarium for root canal filling. The system consists of a control unit with a pen-grip device holding a heating tip, as well as a gutta-percha injection gun. Recently, a new cold flowable filling system - GuttaFlow （Coltene Whaledent, Germany）, has been introduced for the obturation of root canals, combining sealer and gutta-percha in one product. It consists of a polydimethylsiloxane matrix highly filled with very finely ground gutta-percha, that are homogeneously mixed in a mixing capsule. GuttaFlow is said to have extraordinary chemical and physical properties that offer maximum sealing quality and biocompatibility. It easily flows into lateral canals and dentinal tubules; and it does not shrink upon setting, rather it expands by 0.2%.During the obturation procedure, the gutta-percha cone does not bind by itself to the canal wall, so a root canal sealer is necessary to bind the gutta-percha to the canal walls; and hence adhesiveness of a root canal sealer is a desirable property. Generally root canal sealers should be dimensionally stable, insoluble in fluids, easy to manipulate, well tolerated by periapical tissues, bacteriostatic, radiopaque, and should not be carcinogenic; and in addition it should also have cohesive strength to hold the obturation together. Numerous brands and types of root canal sealers have come forward to fulfill all our clinical requirements. Recently, resin based sealers are often used as they provide a good apical seal and adhesion by all methods of obturation. They are insoluble in oral fluids, stable in volume, undergo less dimensional change and also have good handling characteristics, a good flow and sufficient working time. In this study, AH Plus was used as the sealer. Successful root canal therapy requires a complete obturation of the root canal system with non-irritant biomaterials. It is known that majority of endodontic failures have been caused by the incomplete sealing of the root canal and restorative short comings, confirming the necessity of using materials capable of forming a perfect seal between the root canal system and the periradicular tissues.Thus leakage studies on the sealing properties of endodontic materials constitute an important area of research since a long time. There are a great variety of materials used today, but the most common form of non-surgical endodontic treatment uses a combination of gutta-percha cones and a sealer, which is frequently a resin based or a calcium hydroxide formulation.Another very important factor affecting the seal of the root canal is the‘smear layer’. When the root canals are instrumented during endodontic therapy, a layer of material composed of dentine, remnants of pulp tissue and odontoblastic processes, and sometimes bacteria, is always formed on the canal walls. This layer has been called the smear layer. It has an amorphous, irregular and granular appearance under the scanning electron microscope. The advantages and disadvantages of the presence of smear layer, and whether it should be removed or not from the instrumented root canals, are still controversial. It has been shown that this layer is not a complete barrier to bacteria and it delays but does not abolish the action of endodontic disinfectants. Endodontic smear layer also acts as a physical barrier interfering with adhesion and penetration of sealers into dentinal tubules. In turn, it may affect the sealing efficiency of root canal obturation. If smear layer is to be removed, EDTA （ethylenediaminetetraacetic acid） and NaOCl （sodium hypochlorite） solutions have been shown to be effective, among various irrigation solutions and techniques, including ultrasonics.There is evidence relating microbial microleakage and pulpal inflammation as well. The role of the smear layer in minimizing the harmful effects of microbial microleakage and of chemical toxicity of restorative material has been studied many times. Further research should be aimed at eliminating microleakage by the development of more fully adhesive materials or by improving their antibacterial properties. Hence, improving the periapical seal of the root canal is an important factor to maintain a successful root canal therapy. Endodontic research continues to seek improved sealing efficiency of new materials and techniques.Objective:The purpose of this study was to evaluate the apical sealing ability of three different obturation techniques by using a dye leakage test; to find whether the use of GuttaFlow, or the E&Q Plus System creates a better seal than cold lateral condensation technique; by comparing the dye leakage in root canals filled with each of them; and to statistically analyze the obtained data to come to a conclusion.Study design:One hundred and thirty extracted single-rooted maxillary anteriors were selected for the study. The teeth were decoronated and the root canals prepared using ProFile rotary instruments to an apical dimension of size 40 （0.06 taper）. The specimens were then randomly divided into three experimental groups （n =40） and filled with gutta-percha and AH Plus sealer by using either cold lateral compaction or the E & Q Plus system; and GuttaFlow respectively. Another five teeth each served as the positive and negative controls. A dye leakage test was used for quantitative evaluation of the apical microleakage at ten days, one month, six months and one year; using a stereomicroscope.Results:1. No significant difference in the cumulative amount of leakage was found among the three groups at ten days （Kruskal-Wallis test, P > 0.05）.2. Lateral compaction showed significantly more leakage than the other two techniques at longer intervals （Kruskal-Wallis test, P < 0.05）.3. No significant difference was found between E & Q Plus and GuttaFlow at one and six months.4. However, GuttaFlow showed the best overall result over a one year period. Conclusion:1. Problems associated with the inadequate seal formed by gutta-percha when used as an obturation material have been known for decades. The experiment has also shown us that no matter what kind of method we choose, with the extension of time, the amount of microleakage increases.2. No significant difference in the cumulative amount of leakage was found among the three groups at ten days.3. The E & Q Plus system and GuttaFlow showed a better sealing result than cold lateral compaction of gutta-percha at extended observation periods; i.e., after ten days.4. GuttaFlow showed the best overall result over a one year period. All in all, with respect to the apical sealing ability, cold fluid gutta-percha （GuttaFlow） shows a better result; therefore, its use would be worthwhile among practicing clinicians.5. Further case-controlled study, or better still, randomized clinical trial, is needed if the various filling techniques are to be compared for their clinical performance. Other needed research includes in vivo studies showing long-term success rates of these materials.

论文目录

• ABSTRACT
• PREFACE
• METHOD AND MATERIALS
• 1 PROCEDURE
• 2 OBSERVATION AND RESULT
• 3 DISCUSSION
• CONCLUSION
• LIST OF REFERENCES
• PICTURES
• COMPREHENSIVE LITERATURE REVIEW
• ACKNOWLEDGEMENTS
• VITA