Microscopic Endodontics Therapy
Clinical application of dental operating microscope
07762088818
Background
In traditional root canal therapy, having a good vision and skillful handling are essential. In general, if a dentist can't see clearly, he can't do his job very well. Before dental microscopy was applied in clinical practice, doctors almost always searched for root canals in the medullary cavity with naked eyes and clinical experience. However, the field of vision in the deep medullary cavity and root canals was very dark, so it was difficult for traditional mouth mirror to provide a clear surgical field for doctors, thus increasing the difficulty of treatment. Though for teeth problems is of simple structure, and for patients with chronic diseased teeth and older teeth, medullary cavity and root canal calcification will happen, in other words, the inside of the medullary cavity cavity gap will be small, and there are some hard tissues will jam, root canal orifice can be hidden. At this time, finding the root canal is as difficult as finding a needle in a dark room full of debris, which not only makes it more difficult for doctors to operate, but also makes the bacteria in the pulp cavity and the residual pulp can not be completely cleared, resulting in the success rate of root canal treatment greatly reduced (1). Therefore, the dental microscope comes into the eye of the dentist.
Introduction
At the beginning of the 21st century, the Commission on Dental Accreditation (CODA) of the American Dental Association incorporated the microscope training into the "Accreditation Standards for Advanced Specialty Education Programs in Endodontics", and in the following years, dental microscopy was gradually applied in various clinical oral treatments, such as microscopic root canal therapy. Nowadays, dental operating microscopes are widely recognized and are available in almost every dental clinic or stomatological hospital (2,3). Microscope is generally composed of bracket system, optical amplification system, lighting system and accessories. Bracket system: used to support and stabilize the microscope, usually consists of a base, connecting arms, and joint locks. Optical amplification system: Includes objective lens, amplifier converter and binocular. Dental operating microscope is about 2 to 30 times. When the magnification is 2-4 times, the field of vision is wide, and it is usually used to locate the operative area. 6-16 times more suitable for root canal treatment; When the magnification is greater than 20 times, it is used to observe the finer structures in the teeth and root canals. Lighting system: The light source of the operating microscope is a halogen lamp, xenon lamp or LED. During microscopic root canal therapy, because the light is not consistent with the long axis of the tooth, the surgeon can see the structure of the root canal clearly by reflecting the light into the root canal with the help of a high-quality oral mirror. Accessories: A video camera or camera can be connected to a microscope by means of a spectrometer. It displays images of the surgeon's field of vision on a monitor so that the assistant can observe the progress of the operation. The picture below is the dental operating microscope.
First, dental operating microscope is better at helping dentists make diagnoses. Some patients with pulpitis caused by a split tooth may not be able to find the cause of the pulp infection on routine examination. This can be examined with a dental operating microscope. Under a clear, bright view and high magnification, it is easy to detect cracks in the enamel. In addition, with the help of dental operating microscope, dentists can also accurately diagnose dental caries, microleakage and other difficult diseases (1).
In terms of treatment, microscopic root canal therapy is with the aid of dental operating microscope and microscopic instrument in the treatment of root canal, and the traditional root canal's biggest difference lies in the operating microscope can provide adequate light source into the root canal, and root canal system can be amplified, the performer can see root canal internal structure, confirm the treatment area, cure under direct vision and immediately check the quality. With the application of dental operating microscope in clinical treatment, the once more complex and less successful treatment will become no longer difficult.
Microscopic endodontics therapy
Location of root canal orifice
In traditional root canal treatment, dentists can only judge the approximate location according to clinical experience and descriptions in textbooks, and often miss root canals due to concerns about perforation and other reasons, such as MB2 orifice of maxillary first molars. Microscopically, however, the color of the dentine at the bottom of the pulp chamber is different from that of the dentine around the root canal orifice, with the former usually opaque yellow and the latter translucent yellow or brown. Microscopically, the bottom of the pulp can also be seen as a groove connecting the root canal orifice, which is usually at the end of the groove. As a result, the root canal orifice can be easily and accurately located and the canal is almost never missed (4). The image below shows the root canal orifice in maxillary first molar.
2. Clearance of calcified root canals
Root canal calcification is common in clinical practice. Usually, K file and C file are used to gradually clear the root canal wall down. However, due to unclear or small root canal images on X-ray films, the root canal orifice cannot be explored or the root canal is blocked after pulp opening, so doctors will spend a lot of time to explore the root canal orifice or access. However, at high magnification under the microscope, small canals are often visible in the pulp cavity, and the canal can be directly dredged with an 8 or 10 K file, a C + file, or a C pioneer file. In addition, in the case of patients with complete root canal calcification, dentists usually prefer implantation or crown post restoration after tooth extraction. However, the dentist can use a small ball drill under a microscope to gradually remove calcified tissue along the canal until the canal is cleared. Cutting prosthetic or secondary dentin with machine guided under microscope can make the treatment process more accurate and effectively avoid the occurrence of root canal migration and perforation. In the two images below, calcification of the root canal under microscopic (left picture) and x-rays of calcified root canals (right picture).(5)
3. Removal of broken instrument in root canal
Instrument separation during root canal preparation is a common clinical complication which can occur in any part of the root canal. Traditional treatment is first determined by preoperative X-ray separation equipment type, location, length and root tube bending degree, then expand the medullary cavity, with k file from the separation between the instrument and the root tube wall into slowly lift up again, out of the broken equipment, but this is only limited to the upper broken instruments in root canal, and needs to be done by dentists' experience and to feel, the success rate is very low. If the broken instrument is located in the middle or lower part of the canal, it is completely impossible to remove it by conventional means. However, the dental operating microscope can enhance the light entering the root canal, improve the operator's field of vision, and improve the controllability of the entire removal process. The position of the broken instrument is determined under a microscope, and the coronal portion of the canal is then flared under the microscope with Gates Glidden drills or ultrasonic tips. Instruments with linear access created to allow visual separation. Using an ultrasound tips or K file to bypass the debris, create a tunnel around the coronal surface of the disconnecting instrument, then release the separated instrument and flush it. During the operation, cotton pellets are placed in other canal foramen to prevent the separation of instruments from flowing into those canals (6). The two images below, one on the left shows an X-ray of the broken instrument in the lower part of the canal, and the other on the right shows the broken instrument in the canal under a microscope.
