Sectioned apex containing a fragment of Hedstroem’s file C The root has been bevelled and the two canals filled with a single

amalgam filling. D. Postoperative radiograph. E. Eighteen months later.

C

D

32 Endodontics 3 - Definition, Scope, and Indications for Endodontic Therapy 33

to conventional therapy: the root canals may be ne- gotiated, although not without difficulty (Figs. 3.14, 3.15). The use of the surgical operating microscope is very helpful in finding and negotiating calcified root canals. As it will be discussed later on, the pulp tissue gets inflammed, calcifies, and dies in a coro- nal-apical direction, therefore even the most calci- fied root canal is almost always negotiable in the apical one third.

– Anatomical difficulties. Highly pronounced curva- tures can sometimes discourage the endodontist, so much so that he may recommend retrofilling, possi- bly even extraction (Fig. 3.16). Indeed, Weine 37 _sta- tes that, even if canals with pronounced curvatu- res can sometimes be treated successfully, the best approach is extraction, unless the tooth is of great strategic importance. He claims that such teeth re- quire two or three times the normal working time

Fig. 3.14. A. Preoperative radiograph of a nonvital upper left central incisor. The pulp chamber and the root canal seem to be com- pletely calcified. Note the width of adjacent root canals. B. A gutta-percha point has been introduced in the fistulous tract. C. Using the surgical operating microscope, the patency of the root canal has been found in the apical one third. D. Postoperative radio- graph. E. Six month recall. F. One year recall.

A B C

E F

Fig. 3.15. A. Preoperative radiograph of the maxillary first molar, from which the mesiobuccal root has just been removed for periodontal reasons. B. The ac- cess cavity having been created, the rubber dam has been removed so that the clamp would not interfere with the radiographic examination of the canal orifices, which was performed with the help of an endodontic probe. C. An 06 file has been introduced in the distobuccal canal after the palatal canal had been found, cleaned and shaped. The rubber dam clamp has been removed to better check radiographically the course of the canal. The instrument han- dle has been secured with dental floss to the pincers of the patient’s bib D. The dam has been repositioned and the therapy is completed in the traditional manner. E. Postoperative radiograph. F. Four-year recall.

C D

34 Endodontics 3 - Definition, Scope, and Indications for Endodontic Therapy 35

Fig. 3.17. Nonsurgical retreatment of the maxillary central incisor, which has already been treated with a silver cone. The mesial radiolucency is a contraindi- cation to the surgical approach. A. Preoperative radiograph: a gutta percha cone has been introduced into the fistula and reaches the lesion on the side of the root. B. The postoperative radiograph shows that the lesions had been maintained by three lateral canals that had not been filled. C. The one-year recall shows the healing (Courtesy of Dr. C. J. Ruddle).

C

A B

for enlargement and filling, cause a great deal of frustration, and are frequently treatment failures. In contrast, the same amount of time spent on a pro- sthetic replacement will usually afford a better final result.

As a matter of fact, one need not be so pessimistic. The motivated patient will appreciate the time spent in treating his or her tooth, especially if, a precise treatment plan having been established, he or she is apprised from the beginning about the difficulty that the case presents. With patience, a good supply of very fine instruments, and a good canal prepara- tion technique, even the most difficult cases can be treated; thus the number of cases will be reduced that on a superficial examination may have been judged untreatable. However, one must recall that “untreatable by conservative means” does not mean “indication for extraction” and thus prosthesis: befo- re using forceps for extracting teeth, it is well to at- tempt surgical Endodontics.

– Difficulty of retreatment. The presence of a silver cone within a root canal, the crown of which is co- vered by a gold-ceramic prosthesis (Fig. 3.17) does not per se indicate the need for surgical interven-

Fig. 3.16. First upper molar with an endodontic ana- tomy that makes the clinical approach extremely difficult.

prosthesis, the removal of the old obturating material and the three-dimensional filling of the root canal sy- stem, so as to seal all the portals of exit.

– Size of the lesion. Many authors, including Harnish,14 Grossman,12 _{and Tay et al.}34 _{are still convinced that} if a lesion is very large it is almost certainly a cyst, and thus cannot heal unless excised in its entirety. Indeed, Harnish writes that, given that the distinc-

tion between a granuloma and a cyst is extremely difficult on the basis of clinical and radiographic criteria, “it is well to make extensive use of api- coectomy”. “The smaller the radiographic image, the more likely it is that the diagnosis of granuloma is correct”. In support of his claim, Harnish reports a study by Lalonde 17 _{which demonstrated that pe-} riapical lesions from 0 to 1 cm2 _{in area represented} granulomas in 70% of cases and cysts in 30%; those from 1 to 2 cm2 _{represented granulomas in 40% of} cases and cysts in 60%; and 100% of those greater than 2 cm2 _{were cysts. “The differential diagnosis} between granuloma and cyst is important”, conti- nues Harnish, “inasmuch as the treatment of granu- lomas can be attempted through proper canal treat- ment. The granuloma, however, containing epithe- lial tissue that may lead to the formation of apical cysts, is generally considered an indication for in- tervention (i.e., apicoectomy), since the removal of the epithelium eliminates the possibility that a cyst will form”.

Among the indications for apicoectomy, Grossman 12 lists first the extensive destruction of the periapical tis- sue, bone, or periodontal ligament that involves one- third or more of the root apex, and second the root apex involved in a cystic condition.

Tay et al.34 _{have demonstrated that the success of con-} servative endodontic therapy diminishes with increa- sed size of the periapical lesion.

Contrary to these authors’ claims, it can be stated with the support of extensive evidence in the literature and clinical experience based on thousands of cases that the size of the lesion has no bearing on its healing. Once it has been confirmed that the lesion, large or

demic and can be confirmed only by electrophoretic 22,23,25 _{or histological examination.}

Even with histologic techniques, however, it is impos- sible to provide precise statistics, because there are numerous intermediate forms. Thus, if the presence of epithelial cells is used to distinguish between the two, one arrives at the easy conclusion that all lesions are cysts.

The presence of epithelium in periradicular inflamma- tory lesions is a consistent finding, so much so that it is the rule to find nests of epithelial cells (the epithe- lial rest of Malassez, which remain after the disappea- rance of Hertwig’s root sheath) in the periodontal liga- ment of a healthy tooth.

A study by Bhaskar 5 _{confirmed by Lalonde and} Luebke,18 _{showed that the percentage of periapical ra-} diolucencies classifiable as cysts is close to 45%. It is logical, therefore, to conclude that many cysts heal af- ter nonsurgical endodontic therapy, since the success rate of clinical endodontics is much higher than just 55%! Furthermore, even though a surgical endodon- tic procedure is planned, the root canal system has to be three-dimensionally cleaned, shaped, and obtura- ted first any how, therefore the non-surgical therapy has nothing to loose! 38

From a practical point of view, the distinction between a granuloma and a cyst is completely use- less, since they are two different histologic aspects of the same lesion. Their (endodontic) etiology is the sa- me, and they require the same (endodontic) therapy (Fig. 3.18).

The endodontist must therefore not be alarmed by the size of the lesion or the presence of epithelium, which will surely always be variably present. Instead, he must focus his attention on the etiology (i.e., whether the lesion is of endodontic origin), since the therapy in either case is the same.

According to Lalonde,17 _{the surgical treatment is ju-} stified only when conservative endodontic treatment has failed (for reasons independent of the lesion’s bio- logy). The purpose of such intervention is to impro- ve the apical seal that had been imperfectly comple-

36 Endodontics 3 - Definition, Scope, and Indications for Endodontic Therapy 37

D E

Fig. 3.18. A. The panoramic radiograph shows the presence of a large cyst involving several teeth, from the first premolar to the second molar. The first pre- molar tested vital, the second premolar had a necrotic pulp, the first molar needed a retreatment and the second molar had a pulp exposure. B. The preope- rative radiograph shows the radiolucency of the lesion. C. Postoperative radiograph after nonsurgical treatment. D. Another postoperative radiograph with a different angulation shows the root canal anatomy. E. 24 months recall. Why do oral surgeons still insist that it is important to remove the cystic wall?

B C

Today, most North American oral surgeons concur in not curetting the lesion, since this is considered a mal- practice risk.31

Another reason why some authors are convinced of the need for surgical removal of cysts is the fear of so- called “residual” cysts. According to these authorities, if the lesion is not excised down to the last epithelial cell, it will re-form, since it has the potential of a self- sustaining lesion.32

In 1950, Grossman 11 _{wrote: “root canal therapy is} contraindicated in teeth with a cyst, since the cyst will continue to develop unless its epithelial wall is surgi- cally removed in its entirety”. Contradicting this theory is the fact that apical cysts heal spontaneously after

lowed by scrupulous curettage of the alveolar bone. In fact, there are not only odontogenic cysts, but many other pathological varieties that can present as cysts in edentulous zones: it would be too simple to list all such entities as residual cysts (Fig. 3.20).

On the other hand, if a careless curettage were enough to cause the number of residual cysts to increase, one would expect that such lesions would be very fre- quent, given the widespread “malpractice” everywhe- re. Fortunately, this is not the case.

Finally, one might be faced with cysts or, even better, with residual infections, but frequently (if not always) such infections are due to the presence of an apical fragment left in the alveolus after an extraction perfor-

A B

Fig. 3.19. A. Preoperative radiograph of the maxillary central incisor, which has been previously treated endodontically. A large, probably cystic lesion, possi- bly sustained by the irritant matieral beyond the apex, is present. B. Postoperative radiograph after nonsurgical retreatment. C. Postoperative radiograph fol- lowing apicoectomy with retrofilling, performed because of persistent symptoms. In the course of the procedure, performed only to improve the apical seal and remove the irritant material, the cystic wall has been intentionally left in place, so as not to compromise the vitality of the adjacent tooth. D. Four years later. The vitality of the cuspid has been preserved. The radiolucency between the two apices does not indicate treatment failure, but rather represents hea- ling with an apical scar, a typical outcome of the treatment, nonsurgical or surgical, of large lesions.

38 Endodontics 3 - Definition, Scope, and Indications for Endodontic Therapy 39

med hurriedly, rather than to a careless apical curet- tage (Fig. 3.21).

Alternatively, they may be due to the presence of a concretion of tartar that has fallen into the bleeding alveolus during tooth extraction, or to the presence of a bony sequestrum.

That which is left behind in these cases is not so

much the epithelium that covers the lesion, so mu- ch as a closed system containing bacteria and toxins. Because it is impenetrable to the organism’s defense mechanisms, the pathogens continue their pathoge- nic action undisturbed. One must therefore conclude that the lesions named as “residual cysts” are lesions of unknown etiology.

C

Fig. 3.20. A. Mandibular first premolar during apexification. B. Six months later, a cyst is developing in the adjacent zone which is edentulous for the agenesis of the second premolar. C. Nineteen months later the cyst is still growing. D. Two years later, the cyst has reached a considerable size. E. Healing one year after surgical excision of the cyst. A histological examination confirmed that it was a keratocyst in a patient with Gorlin’s syndrome. F. Three year recall.

E

D

F

A

Fig. 3.21. A. The preoperative radiograph of the mandibular se-