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Endodontic problems Abstract Root canal treatment has changed considerably since the hollow tube theory was first postulated in Research continues into the elaborate anatomy of root canal systems, and also into the microbial causes of endodontically related diseases. Only by understanding these aspects in detail can the practitioner quickly and effectively shape the main root canals to facilitate thorough cleaning of the entire system, and easy and effective filling.
Download PDF Main In Kakehashi, Stanley and Fitzgerald 1 showed conclusively that pulpal and endodontic problems are primarily related to microbial contamination of the root canal system. Since that time endodontology has increasingly focussed on the ways and means of eliminating micro-organisms from the entire root canal system.
The majority of patients who require root canal treatment will have been diagnosed as suffering from the disease of periradicular periodontitis. The treatment of this disease must address the microbial contamination of the entire root canal system. It must also be carried out under aseptic conditions in order to prevent further microbial ingress, in particular from saliva.
The use of a rubber dam very much reflects the use of a surgical drape in other invasive medical procedures. Such a biological approach will be emphasized throughout this text. Research into the morphology of the pulp has shown the wide variety of shapes, and the occurrence of two or even three canals in a single root.
The many nooks and crannies within the root canal system make it impossible for any known technique, either chemical or mechanical, to render it totally sterile. The objective of treatment must be to reduce the level of microbial contamination as far as is practical, and to entomb any remaining microorganisms with an effective three-dimensional seal.
Figure 1: The root canal system of this lower molar has been stained and the tooth totally decalcified, showing the complex nature of the root canal system. Courtesy of Professor R T Walker.
Full size image The prime aim when preparing the root canal has long been stated as cleaning and shaping. One of the prime aims of this text will be to encourage the practitioner to see this in reverse, ie shaping and cleaning. Modern instruments and techniques will be described which rapidly open and shape the main root canals, thus permitting the effective access of antimicrobial irrigants to the entire root canal system, including lateral canals, fins, anastamoses and other canal aberrations.
It is imperative that these instruments are not seen as providing a route to quick and speedy root canal treatment. To achieve success the time saved by the rapid opening of the canal system must be spent in thorough and effective antimicrobial irrigation. Research has also shown that when an infected root canal is accessed, the number of different species of microorganisms is small, rarely above single figures.
Isolation of the tooth under treatment is essential not only for medicolegal reasons to protect the airway, but, far more importantly, to prevent further contamination of the root canal system and to permit the use of strong intracanal medicaments.
Other areas of research have had the significant effect of changing the approach to endodontic treatment. The hollow tube theory put forward by Rickert and Dixon in 4 postulated that tissue fluids entering the root canal stagnated and formed toxic breakdown products which then passed out into the periapical tissues.
This theory, that dead spaces within the body must be obturated, originally formed the basis for filling root canals. However, a variety of different studies have demonstrated that, on the contrary, hollow tubes are tolerated by the body. As a result there are currently two indications for filling a root canal, once the canal system has been shaped and cleaned.
Firstly, to prevent the entry of microorganisms to the root canal system from either the oral cavity, should the coronal restoration leak or fail, or via the bloodstream anachoresis. Secondly, to prevent the ingress of tissue fluid which would provide a culture medium for any bacteria remaining within the tooth following treatment.
A report by Klevant and Eggink 5 is particularly relevant. They shaped and cleaned a number of root canals, but the experimental group were not obturated. They ensured that an effective, well-sealed, coronal restoration was placed. Figure 2 shows a lower molar with a large periradicular lesion. The root canal system was shaped and cleaned, and an intervisit dressing of calcium hydroxide placed.
The patient did not return for further treatment for 6 months, when a radiograph revealed that complete healing had taken place. Figure 2: a The pre-operative radiograph of tooth LR6 46 shows a large radiolucent area associated with the root apex and the furcation area. Root canal treatment was commenced. Full size image Of course, this does not mean that obturation is unimportant. It is essential for the reasons described earlier.
Similarly, Ray and Trope 6 found that root-treated teeth with a poor obturation on radiograph but a good coronal restoration had a better prognosis than teeth with a good obturation but a poor restoration.
The majority of root canal sealers are soluble and their only function is to fill the minute spaces between the wall of the root canal and the root filling material. Their importance, judged by the number of products advertised in the dental press, has been over-emphasized. Despite much research, gutta-percha remains the root filling of choice, although it is recognized that a biologically inert, insoluble and injectable paste may be better suited for obturation of the root canal.
Most of the new root canal filling techniques are concerned with methods of heating gutta-percha, making it softer and easier to adapt to the irregular shape of the canal wall. It must be emphasized, however, that, whatever the obturation system used, if the root canal system has not been adequately cleaned healing may not occur Fig.
Figure 3 A radiograph of tooth LL7 37 showing a root canal treatment carried out 12 months previously, with what appears to be an effective obturation yet no evidence of healing of the periradicular lesion. Full size image Finally, lesions of endodontic origin which appear radiographically as areas of radiolucency around the apices or lateral aspects of the roots of teeth are, in the majority of cases, sterile. This finding suggests that the removal of microorganisms from the root canal followed by root filling is the first treatment of choice, and that periradicular surgery, including an apicectomy with a retrograde filling, can only be second best.
The long-term success rate of apicectomy must inevitably be lower than orthograde root treatment. In summary, the principles of treatment of the disease of periapical periodontitis are as follows.
Shape: Produce a gradual smooth taper in the root canal with its widest part coronally and the narrowest part at the apical constriction, which, as discussed in Part 4, is normally about 1 mm short of the apex. Clean: Use antimicrobial agents to remove microorganisms and pulpal debris from the entire root canal system. Fill: Obturate the canal system with an inert, insoluble filling material. The effects of surgical exposures of dental pulps in germfree and conventional laboratory rats.
J South California Dent Assoc ; — Scanning electron microscopy of bacteria in endodontically treated teeth. III In vivo study. J Endod ; 7: — The controlling of root surgery. Section a p Paris, The effect of canal preparation on periapical disease. Int Endod J ; 68— Periapical status of endodontically treated teeth in relation to the technical quality of the root filling and the coronal restoration.
Int Endod J ; 12— Google Scholar 7 Grossman LI. Bacteriologic status of periapical tissue in cases of infected pulpless teeth. J Endod Special Issue ; 8: — Bacteria on the apical root surfaces of untreated teeth with periradicular lesions: a scanning electron microscopy study. Int Endod J ; — Surgical treatment of apical periodontitis.
Endodontics: Part 1 The modern concept of root canal treatment
Tadamichi Kuribayashi was born into a minor samurai family in Hanishina District , Nagano prefecture. According to Kumiko Kakehashi, the Kuribayashi family had lived in the district since the 15th century. He just escaped expulsion by a hair. In those days, he was already good in poetry-writing, composition, and speech writing.
The two single-headed arrows point to the CEJ , which is the line separating the crown in this case, heavily decayed and the roots. The double headed arrow bottom right shows the extent of the abscess that surrounds the apex of the palatal root. In response to tissue injury , neutrophils leave the circulatory system in great numbers and gather at the site of tissue injury. They are drawn to the site by chemotaxis , following a concentration gradient of chemotactic molecules until they reach the site of greatest concentration: the site of injury and microbial presence. Once there, the antimicrobial action of superoxide and hydrogen peroxide , derived from the metabolic processes of the neutrophils, act to combat the microbial invasion.
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