Digitized Analysis of Thermal Changes on External Root Surface of Teeth Embodying Separated Endodontic Files Retrieved By Different Ultrasonic Tips /

Abstract

One of the most basic procedures in modern dental practices is endodontic treatment, which has helped in the preservation of teeth that would have been otherwise extracted. Motor driven, endodontic instruments are commonly used in su nickeltitanium (NiTi) ch procedures with a more predictable treatment outcome due to their good shaping ability of the root canal. Unfortunately, not all treatments result in optimum long term healing. Occasionally during root canal therapy, a file could separate within a root canal system blocking access to the apical canal terminus. Even with the introduction of NiTi files, which are more been an increase in file separation incidents. flexible , there has The general principle for removing a fractured instrument is based on th e fundamental principles and objectives of root canal treatment. A fractured instrument may be an obstacle to mechanical and chemical treatment of an infected root canal system. Bacteria and pulp tissue, which remain in the root canal because of insufficie nt cleaning, may have a negative impact on treatment outcome. Several methods have been proposed to remove obstructions from within the root canal, with varying degrees of success . Ultrasonics have been shown to be a highly successful technique in removing separated instruments in vitro and in vivo in association with the operating microscope . This has led to an increase in the popularity of this technique among endodontists. These ultrasonic systems are composed of special designe d tips to trephine the dentin around the fractured fragment. The ultraso nic vibration of the tip is transmitted to the separated file so it becomes loose and is eventually dislodged. However, such a procedure may give rise to complications such as excessiv e loss of dental structure, root perforation, secondary fracture of the fragment, and excessive rise in temperature on the other root surface. The periodontal tissues could suffer sever the temperature rise s above the 10°C threshol e irreversible damage if d. Irreversible bone and attachment damage as well as dehydration effects on dentin will occur if the temperature of the outer root surface exceed 10°C, often resulting in resorption and necrosis to the supporting periodontium. Dentine thickness, type of ultrasonic tips, power setting, and application time are some of t he factors that might influence this temperature rise. Coolant application while ultrasonic tips are activated is another important factor. Previous studies showed a significant decrease in temperature rise on the external root surface during ultrasonic re water or air coolant were used. Trieval of intracanal posts when The use of a coolant during such procedure is thus advisabl will greatly lower the accumulated temperature e; as it on the outer root surface, and by doing so, lower the risk of permanent periodontal t issue damage. However, many clinicians might not always accept the use of a coolant as it lowers their visibility of the operating field. This may increase the time needed for successful retrieval, which increases the chances for errors like root perforati on and excessive thinning of the remaining radicular dentin, resulting in a poorer prognosis for the case. (6,7) T hus t he aim of this study is to assess the thermal changes on the outer root surface and the remaining dentin thickness during the ret of a separated ultrasonic tip file within the apical third of the rieval root canal using different designs, and how will the use of water coolant affect the time needed for file retrieval.