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» Articles -> Smile Magazine Issue 5 September 2007-> Endodontic Surgery, A chance to rewrite history
Dated : 2007-09-01
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Endodontic Surgery: A chance to rewrite history

 

 

  » By: Dr. Dr. Muna Al-Ali ; BDS, Private practice

  » Dr. Jamal Aqrabawi ; Professor of Endodontics, University of Jordan

 

As dentistry aims to maintain the dentition in a healthy and functional status, many procedures and treatment options are now available.

Root canal treatment (RCT) of teeth has long shown high success rates, if done properly. Nonetheless, that does not exclude the occurrence of failures. Most of these failures are in fact related to other factors, like the coronal restoration, rather than the RCT itself (1). The clinician can almost always decide which case can be retreated and restored properly. Yet, some cases are challenging and making it difficult for the clinician to decide.

Some dentists tend to extract questionable teeth and replace them with fixed prostheses, or implant supported restorations, just to avoid the complications and the complexity of treatment procedures required to retain such a tooth. It is well known that implants demonstrated a very high success rates but still, complications do occur (2). Not to mention that implants require an extended treatment protocol. On the other hand, the rapid return of the dentition to its function is the biggest advantage of restoring the tooth even if compromised.

Once the tooth with a failing RCT is diagnosed, three treatment options come to surface; endodontic retreatment, endodontic surgery, and extraction if the tooth is hopeless and not restorable (Figure 1). Based on the clinical and radiographic findings, the dentist should be able to decide which treatment option is more adequate.
If the root canal anatomy was not significantly altered, and the cause of failure is identifiable; root canal retreatment can be done with a chance of success in two thirds of the cases (3).

 » (Fig. 1)

Perforation of the root in the lower second premolar. The tooth can not be restored, even with endodontic surgery due to periodontal break down.

 

 

Endodontic surgery, in a broad meaning, addresses the cases where proper apical seal can not be obtained (3). It is indicated when:
 
 1. Complex root canal anatomy exists
 2. Irretrievable materials in the root canal (Figure 2)
 3. Presence of procedural errors and accidents (Figure 3)
 4. Persistence of symptomatic cases
 5. Refractory lesions
 6. Need for a biopsy
 7. Horizontal root fracture, where the apical portion is infected and causing symptoms.

Only when the tooth can not be treated by non surgical methods, endodontic surgery is indicated.

(Fig. 2):A: Lower first mandibular molar with a fractured file in the mesial root, which can not be retrieved.
               B:
Apical surgery was done for the Molar and the root end was filled with MTA.
               C: The same case after 6 months of healing.

 

The main purposes of endodontic surgery are to remove the undebrided portion of the root, and seal the canal space properly.

Starting from left: (Fig. 3): A: This case presented with persistence of symptoms related to the upper first molar. A non negotiable ledge in the apical third of the mesial root excluded conventional retreatment. / B: So, apical surgery was performed. / C: The case after healing and absence of symptoms.

In the past endodontic surgery carried along with it many risks and procedural errors, due to the difficulty of visualizing and accessing of the apices of the teeth.  Thanks to nowadays advanced technology, endodontic surgery is much easier, more precise, and with more predictable outcomes than before (4). Today, enhanced magnification and illumination (table 1) enhances the ability of the endodontists to visualize the apex and its surroundings, and the ability to identify previously unidentified anatomical structures and defects responsible for failure. These include the isthmus, lateral canals, craze lines, fractures, etc.

(Fig. 4): Operating Microscope with a built in video camera projects magnified images on a computer monitor.

(Fig. 5): Surgical binoculars and a fiber optic headlamps.

 

 

 

 

 

 

 

 

 

Furthermore, surgical endodontic instruments have also been modified to accommodate the small size of the bony window made to expose the apex of the tooth. Table (2) Micro scalpels (figure 6) allow higher precision of the incision and therefore better and faster healing. Piezoelectric hand pieces (Figure 11) not only does it provide a more precise and smoother cavity preparation since it follows the long axis of the root, but it also allows for less bone removal to expose the apex because it is smaller than the earlier microsurgical hand piece. In the past, at least a 10 mm wide bone window had to be prepared to allow for the head of the microsurgical hand piece, but now less than 5mm wide window is needed.

(Table1):                                                                                       (Table 2):

     

Even more, the use of piezoelectric hand pieces requires a smaller bevel angle, thus conserving tooth structure and obtaining a better seal.
The better vision, in addition to illumination and magnification, surgical micro mirrors (Figure 12) can easily accommodate the small bony cavity prepared around the apex.

Microsurgical irrigators (Figure 9) allowed for better control of air and water necessary for proper sealing of the root end.

(fig. 6): Micro scalpel (above) in comparison to standard scalpel (below).

(Fig. 7): Right: Standard contra angle hand piece, Middle: Microhead surgical hand piece, Left: piezoelectric ultrasonic hand piece.

» (Fig. 8): Micromirror in comparison with a standard mirror.

 

 

 

 

 » (Fig. 9): Microsurgical irrigator fitted over a tri-flow syringe.

 

 

 

 

 

 

Amalgam is no longer used as a retrograde filling material. MTA and Super EBA are now the materials of choice. MTA is the best of these two. The sealing ability of MTA is superior to that of amalgam. Also, nowadays white pro root MTA can be used instead of the grey one to avoid tissue staining.
Interestingly, cementum formation is induced when MTA is used over the cut dentin and the MTA filling of the root end. (Figure 13) (4, 5) This is due to the high pH of MTA which is near to that of Calcium Hydroxide(5).

Aside of apical surgery, root resection, hemisectioning and bicuspidization fall within the scope of endodontic surgery. Root resection (Figure 14) and hemisectioning are indicated when there is irretrievable material in the root canal, or non repairable perforation, provided that the remaining roots are periodontally sound and can be properly treated.

Bicuspidization is usually done on a lower molar when a periodontal defect or extensive caries involves only the furcation area, while the rest of the tooth is sound (Figure 15). However, bicuspidization should be avoided when roots are very close or fused together. Also, it should be avoided when the furcation is deep.

» (Fig.10): Micro condenser and micro burnisher compared to commonly used amalgam corresponding instruments.
(Fig. 11):
Miniature ultrasonic handpiece cleans and shapes the root-end preparation.
(Fig. 12):
Micro mirror can easily fit into a small bony window. It allows visualization of completed root-end preparation with two canals and an intercanal isthmus.
(Fig. 13): Histological section of the root-end, showing cementum covering the cut dentin and the MTA filling of the root-end.

As any other dental procedure, endodontic surgery has some limitations. Anatomical factors, like proximity to a neurovascular bundle or the maxillary sinus, can pose a potential limitation. Yet again, these depend on the operator’s skills and experience. The use of advanced technology merely helps the operator and enhances the outcome.

Thick bone, like the buccal bone plate near the lower second molar presents another issue. This molar has lingually inclined roots in addition to the thick bone plate, not to mention proximity to inferior dental canal. This means that a lot of bone has to be removed to reach the apices, and the lingual inclination of roots with the limited visual access makes it very difficult to make sure the cut is extending lingually enough to ensure success (5). So, the extraction of lower second molar and performing the apical surgery, and then replanting it back in place is a better choice. It does not need to be splinted (Figure 16).

(Fig.14): A: Retreatrnent of this case was excluded for the non negotiable ledge, and due to the stripping (close to perforation) present in the mesial root. Apical surgery would solve the ledging but it will not solve the e stripping.
So,
B:
The decision was to resect the mesial root.
C: The case after healing and restoring the tooth.

(Fig.15): A: This lower first molar has a non repairable strip perforation of the mesial root.
                  B:
Instead of extracting the whole tooth, it was hemisectioned.
                  C:
And the mesial part removed.
                  D: The remaining part of the tooth was restored and remained functional in the dentition.

(Fig.16): A: Failure of RCT of the lower second molar, with two periapical lesions related to its roots. Due to the non-negotiable ledges in the apical portion of the roots, apical surgery was the treatment of choice. Since the buccal bone plate is thick, and the root apices are close to the inferior alveolar canal,
B: the tooth was extracted;
C: and apical surgery was preformed (amalgam was used to fill the mesial root-end, while cold burnishing of the Gutta Percha was performed on the distal root;
D: then the tooth was replanted back in place, E: Five years later, demonstrating healing of the apical pathosis to be complete.

Another limitation is unidentified cause of failure. If the cause is unknown, treatment is deemed to fail even if perfectly executed. Exploratory surgery can be performed in an attempt to find the cause. If it is found, the treatment should be provided on the spot.

In conclusion, the clinician should evaluate the restorability, the periodontal health of the tooth in question, and weigh the benefits against the risks of any treatment modality in mind. Non surgical root canal retreatment should come first in mind. If it was not applicable, then endodontic surgery follows, if indicated. With the recent advances in surgical technology, endodontic surgery is much more precise and predictable. Since the natural tooth is the best implant, every effort should be done to retain it functional in the dentition rather than extract it and replace it with an implant (6).

References:

1. Vire DE. Failure of endodontically treated teeth: classification and evaluation. J Endod. 1991; 17: 338-342
2. Scott L. Doyle, et.al: factors affecting outcomes for single tooth implants and Endodontic restorations. J. Endod. (33), 4 April, 2007.
3. Torabinejad and Walton: principles and practice of Endodontics, 3rd edition, 2002.
4. Gerald N. Glickman and Kenneth A. Koch: 21st century Endodontics, JADA, (131) June, 2000.
5. Stephen Cohen and Richard C. Burns: Pathways of the pulp, 8th edition, 2002.
6. Anthony S Dawson and Santo C. Cardaci : Endodontics versus implantology: to extirpate or to integrate? Aust. Endod J, 2006; 32: 57-63

  

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