endodontics Editor: MILTON SISKIN, D.D.S. College of Dentistry The University of Tennessee 847 Monroe Avenue Memphis, Tennessee 38163

Analysis of endodontic therapy in patients irradiated for head and neck cancer Bradley G. Seto, D.D.S.,* John Beumer III, D.D.S., MS.,** Takumi Kagawa, D.D.S.,*** Perry Klokkevold, * * * * and Larry Wolinsky. Ph.D., D.D.S.,***** &QS Angeles and San Francisco, Cai$

The outcome of endodontic therapy in 16 patients irradiated for head and neck cancer was studied. Thirty-five postradiation endodontically treated teeth (54 roots) were included in the study. The follow-up period ranged from 6 months to 54 months. At the time of last follow-up, 46 of 54 roots were being maintained. No osteoradionecroses were seen in association with teeth that had been endodontically treated. From this review, it is clear that endodontic therapy is a viable method of treating diseased teeth in patients irradiated for oral neoplasms.

(ORAL SURG. ORAL MED. ORAL PATHOL. 60540-545, 1985)

T he effects of cancericidal doses of radiation therapy on the tissues of the oral cavity and related structures are well known. Changes have been noted in the mucosa, taste buds, salivary glands, bone, perjodontium, teeth, oral flora, and muscles of mas- tication.1’4 The most significant complication of irra- diation for head and neck neoplasms is osteoradione- crosis.5-8

Postradiation dental extraction of diseased teeth within the radiation field leads to a high rate of osteoradionecrosis.g It would follow that other means of controlling dental disease should be pursued, particularly in the mandibular dentition. Endodontic therapy has been employed on occasion in these

*Hospital Dental Service, School of Dentistry, University of California Los Angeles. **Maxillofacial Prosthetics, School of Dentistry, University of California Los Angeles. ***Removable Prosthodontics, School of Dentistry, University of California Los Angeles. ****Senior, School of Dentistry, University of California San Francisco. *****Oral Biology, School of Dentistry, University of California Los Angeles.

patients, but there are few studies assessing its applicability and success in the face of specific dental disease states.10-12 Hence, information is not available concerning the effectiveness of endodontics in reduc- ing the risk of osteoradionecrosis. The purpose of this study is to evaluate the applicability of endodontic therapy for treating advanced dental disease in patients who have undergone radiation therapy for head and neck neoplasms.

REVIEW OF THE LITERATURE

The success of endodontic therapy in the patient irradiated for head and neck cancer has not been well documented. One study reported that, after 18 months of follow-up, endodontic treatment was suc- cessful in only two of eleven teeth in patients irradiated for oral neoplasms.L2 Both of the success- fully treated teeth were out of the radiation fields. It was theorized that the failures were due to the reduced healing potential of irradiated tissue and the presence of nonvital pulps prior to endodontic treat- ment. The criteria for success or failure were not well described. Another report demonstrated the diflicul- ty of performing endodontic therapy in irradiated

volun~c ho Endodontic therapy in patients irradiated for head and neck cancer 541 Number 5

patients and reported the successful treatment of six teeth.” Various techniques for endodontic therapy were discussed, but criteria of success and indica- tions for endodontic therapy were not defined.

METHODS

All patients included in the study received cancer- icidal doses of radiation to the head and neck and subsequently underwent root canal therapy. Radio- therapy data collected included the radiation fields, doses, dates of delivery, and means of treatment. The date of the root canal treatment, the location of the teeth with respect to the radiation field, indications for endodontic treatment, and postendodontic sequelae were recorded.

A classification of endodontic treatment length was developed and defined by radiographic means (Fig. 1). A fill was considered normal when the endodontic filling material was from 0 to 2 mm short of the radiographic apex. A short fill was more than 2 mm short of the radiographic apex. A long fill had filling material beyond the radiographic apex. Pos- tendodontic complications, including percussion sen- sitivity, pain, swelling, and an association with osteo- radionecrosis, were documented. The periodontal status of the treated teeth, including pocket depth, mobility, and inflammation was assessed. The pos- tendodontic restorative course was also documented. Success of endodontic therapy was based upon the absence of symptoms and purulence and on stable periapical changes. Because of the compromised healing potential of irradiated bone, resolution of bony changes was not considered a criterion neces- sary for success.

The data were exposed to statistical analysis by the chi-square test. Significance was accepted when p < 0.05.

RESULTS

Sixteen postradiation patients who underwent endodontic therapy were followed. The average age was 66.5 years. Sixty-three percent (10/16) received a tumor dose greater than 6,500 R and 37% (6/16) received between 4,500 R and 6,500 R. Eleven preradiation endodontically treated teeth (twenty- three canals) and thirty-five postradiation endodon- tically treated teeth (fifty-four canals) were evaluat- ed. The period of time from endodontic treatment to follow-up ranged from 6 months to 54 months (median, 21.6 months) for the postradiation group. The indications for postradiation root canal treat- ment were caries (80%), periodontal disease (17%), and periapical abcess (3%) (Table I). In the postra- diation group, pretreatment periapical changes were

LONG

Fig. 1. Classification of endodontic length.

evident in 31% and pain in 29%. All teeth with pain were also noted to be carious. There were no differ- ences seen in postendodontic changes, regardless of whether the teeth involved were in the radiation field or whether the teeth involved were treated before or after radiation therapy.

Evaluation of the length of endodontic fills showed 22 normal, 25 short, and 7 long fills in the postradia- tion root canals according to the previously defined criteria. In the preradiation group, there were 3 normal, 7 short, and 3 long fills. When multiple- rooted teeth were present, each canal was evaluated separately where possible.

In 22 teeth (3 preradiation and 19 postradiation root canals) coronal tooth structure was amputated at or below the level of the gingiva. Eighteen teeth were provided with full-coverage crown restorations. Five of these crowns were eventually amputated at or below the gingiva (Table II).

Eight postradiation endodontically treated roots and three preradiation endodontically treated roots exfoliated spontaneously or were extracted. No rela- tionship was found when we compared length of endodontic fills and postendodontic restorative treat- ment to subsequent tooth loss.

In the immediate posttreatment period (within 1 week), 31% of the postradiation endodontically treated teeth (11 of 35) had postoperative pain and 42.9% (15 of 35) had local edema (Table III).

On long-term follow-up (range, 6 months to 54 months), 12 teeth and 2 roots of 35 postradiation (40%) and 3 of 11 preradiation endodontically treated teeth did not have periapical changes, puru- lence, or pain. Fifty-nine percent (27 of 46) of the teeth demonstrated periapical changes (5 of 11 of the

542 set0 et al. Oral Surg. November, I985

Table I. Indications for endodontic treatment (postradiation root canals-Field and Arch versus changes)

Arch

Periodontal Periapical Caries disease

Radiation changes Swelling Pain

field Yes No Yes No Yes No Yes No Yes No

Maxilla In 11 I 1 1 - 1 out - 3 6 1 8 5 4

9 9 Mandible In 11 6 6 11 4 13 17 3 14

out 7 1 - 8 3 5 - 8 2 6 28 7 6 29 11 24 1 34 10 25

(80%) (17.1%) (3 1.4%) (2.9%) (28.6%)

Table II. Postendodontic treatment

Arch

Maxilla

Mandible

Radiation field

In out In out

Amputated PFM*

1 1 (4) 4 (1) 4 (1)

13 (3) 3 (1) 6 2

24 (4) 10 (8)

Extract/exfoliation

(2) 1 (1) 2 5

8 (3)

Preradiation figures are given in parentheses. *Porcelain-fused-to-metal crow.

Table III. Postendodontic complications within one week of treatment

Arch Radiation

Jield

Periapical changes

Yes No

Swelling Pain

Yes No Yes No

Maxilla In - 1 - I - 1 out 3 6 1 8 2 7

Mandible In out

6 11 1 16 6 11 6 2 - 8 3 5

i-3 35 z 73 ii 5i (42.9%) (5.7%) (3 1.4%)

preradiation and 22 of 35 of the postradiation root canals). Seven percent (3 of 46) of the teeth had pain to percussion or palpation (1 of 11 of the preradia- tion and 2 of 35 of the postradiation root canals) (Table IV).

Relationships between endodontic length and postendodontic changes in teeth treated after radia- tion therapy are outlined in Table V. Chi-square analysis showed no relationships between the length of endodontic fill and subsequent periodontal dis- ease, pain, or extractions. However, a significant relationship existed between periapical changes and endodontic length. The short endodontic lengths resulted in significantly fewer periapical changes than either the long or normal lengths (p < 0.05).

Comparisons were made between maxillary and mandibular teeth with respect to complications of endodontic treatments (Tables III and IV). Statisti-

cal analysis showed that there was no significant relationship between the maxillary and mandibular teeth with respect to periapical changes or pain. The overall retention of postradiation endodontically treated roots was 85% (46 of 54 roots). No osteora- dionecrosis were associated with endodontically treated teeth.

DISCUSSION

No osteoradionecroses were seen in association with endodontic therapy, despite the group of patients studied having received significant radiation to the jaws. This is in contrast to the high incidence of osteoradionecrosis seen when severely diseased teeth are removed after irradiation for head and neck neoplasms.7-g~ I39 I4 Therefore, it appears that endo- dontic therapy is a safe procedure in patients who have been irradiated for oral tumors.

Volume 60 Endodontic therapy in patients irradiated for head and neck cancer 543 Number 5

The most common indication for endodontic ther- apy was caries. The caries were asymptomatic and often led to rapid pulpal involvement and coronal amputation.3, I5 Since periapical abscesses resulting from carious pulpal involvement have reportedly precipitated osteoradionecrosis,‘4 endodontic therapy is vital to eliminate the infectious process and ulti- mately avoid extraction. Following caries debride- ment and endodontic therapy, the crown should be amputated at or below the gingiva and the canal should be filled with amalgam to prevent the risk of coronal leakage leading to periapical failure. Full- coverage restorations should be used only if oral hygiene is optimal and fluoride use is consistent. When a crown is desired, one must consider the risk of complications from post and crown construction; such complications include occlusal trauma, tooth fracture, root perforation, or bone exposure from excessive force of gingival retraction. This is espe- cially important for the mandibular dentition within the field of radiation, where reparative procedures such as extractions, apicoectomy, and periodontal surgery are contraindicated.

Periodontal disease is a major cause of osteora- dionecrosis in dentulous postradiation patients.9 En- dodontic therapy of diseased teeth allows for coronal amputation and greater access to deep periodontal pockets (Fig. 2). However, when multiple-rooted teeth are amputated coronally care must be exercised to avoid exposure of the interradicular bone. The furcation should be opened only short of the gingival attachment and incrementally fluted as the soft tissue recedes. In this way, extraction of teeth that demonstrate moderate to severe periodontal disease can be avoided and such teeth can be maintained with hope of exfoliation or gingival coverage.

Subjectively, there seems to be a lower incidence of pain in the mandibular teeth within the field of radiation versus teeth within the field of radiation in the maxilla or outside the field of radiation, but no statistically significant relationships were seen.

The shorter endodontic fill lengths had the fewest postendodontic periapical changes. This implies a lesser pathologic response and a more biologically acceptable result. It is probable that fills close to the radiographic apex as seen in the normal-fill category are overextended, thus precipitating the same patho- logic responses as seen in long fills. Therefore, in the radiation patient, shorter lengths would appear to be more desirable than overextended fills; however, further study is needed.

Endodontic treatment for postradiation patients is technically difficult because of limited rubber-dam

Fig. 2. Coronal amputation, endodontic treatment, and root contouring to improve cleansibility of deep periodon- tal pockets about teeth whose extraction is contraindi- cated.

use and access for instrumentation and filling.*O~” Rubber-dam isolation is complicated by minimal coronal tooth structure and the risk of tissue trauma and resultant bone exposure. Oropharyngeal reflexes may also be compromised by surgery and/or radia- tion that leads to a greater likelihood of aspiration of files. A throat screen consisting of an open 2 X 2- inch piece of gauze should be used whenever a rubber dam is not possible. All files should have floss or thread attached for easy retrieval if inadvertently dropped beyond normal reach. Trismus and small pulp canals make access for instrumentation and filling difficult. When access is limited by trismus, the files can be bent along the noncutting portion of the shank to increase working space between the maxillary and mandibular dentitions. Hemostats can be used on the noncutting portions of the file to instrument the canals. Coronal amputation or facial access can also be helpful in location and instrumen- tation of root canals in the presence of canal sclerosis and trismus. Canal obturation with gutta-percha by means of finger spreaders and lateral condensation is effective. In summary, any technique that aids in the access, preparation, and completion of endodontic therapy can be used as long as the patient is protected from aspiration and soft-tissue trauma.

The criteria for success must be altered for the irradiated patient because of the compromised heal- ing potential of bone and the technical difficulty of

544 Set0 et al. Oral Surg. November, 1985

Table IV. Postendodontic complications at follow-up

Arch Radiation

field

Caries Perio Periapical Pain

Yes No Yes No Yes No Yes No

Maxilla In 1 (3) 0 (1) 0 (3) 1 (1) 0 (2) 1 (2) 0 (0) 1 (4) out 3 (0) 6 (2) 0 (0) 9 (2) 5 (1) 4 (0 0 (0) 9 (2)

Mandible In 5 (2) 12 (1) 10 (2) 7 (1) 10 (2) 7 (1) 2 (1) 15 (2) out 3 (1) 5 (1) 2 (0) 6 (2) 7 (0) 1 (2) 0 (0) 8 (2)

- - - - - - 12 (6) 23 (5) 12 (5) 23 (6) 22 (5) i?qJ 2 (1) 33 (IO) 34.3% (54.5) 34.3% (45.5) 62.9% (45.5) 5.7% (9.1)

Preradiation figures are shown in parentheses.

Table V. Postradiation root canal length versus complications

Caries Periodontal

Length Arch Field Yes No Yes No

Periapical Pain

Yes No Yes No Extraction

Maxilla In I - 1 - I I Normal out 2 I 3 2 I 3

Mandible In 3 II 5 9 8 6 4 10 1 out 3 I 2 2 4 - _- 4 3

- - - - - Maxilla

In

Short out 2 1 - 3 I 2 3

Mandible In I I6 I3 4 4 I3 6 11 out 1 4 - 5 2 3 4 I 2 In - - -

Maxilla - - 3 2 I 1 2 I Long

out 3 In 2 2 - I 1 - 2 I

Mandible out -! _1 -

22

-2 1 _I -L _I -

16 (29.6%)38 (40.7%::. 25 (41

.3%)29 16 38 s (29.6%)

endodontic therapy. When the criteria for success were defined as nonprogressive periapical changes and a lack of pain, a low success rate (40%) was seen. However, a high percentage of roots (85%) were retained despite minor periapical changes and pain. No incidences of osteoradionecrosis were seen in association with endodontic therapy. Therefore, the success rate in treatment of severely diseased teeth in irradiated patients, based on avoidance of extraction and prevention of osteoradionecrosis, was 100%.

CONCLUSION

Analysis of 54 endodontically treated roots in patients irradiated for head and neck cancer is reported. No incidents of osteoradionecrosis was associated with endodontic treatment. Shorter endo- dontic fills resulted in the fewest postendodontic changes, but further study is needed to elaborate on optimal endodontic length. Eighty-five percent of the roots were retained despite clinical signs of mild pain or periapical changes, with treatment in 40% of the teeth being successful as defined by a lack of progression of periapical changes and pain. Endo-

dontic therapy was 100% successful in avoiding extractions and preventing osteoradionecrosis. In summary, despite poor success expectations because of technical difficulty and impaired healing, endo- dontic treatment appears to be a viable means of avoiding extraction of severely diseased teeth within the radiation field, thus decreasing the risk of osteo- radionecrosis.

REFERENCES

I. Rohrer MD, Kim Y, Fayos JV: The effect of cobalt-60 irradiation on monkey mandibles. ORAL SURG ORAL MED ORAL PATHOL 48: 424-440, 1978.

2. Bonanni G, Perazzi F: Variation of tastes sensitivity in patients subjected to high energy irradiation for tumors of the oral cavity. Nunt. Radio1 316: 383-397, 1965.

3. Frank RM, Herdy J, Philippe E: Acquired dental defects and salivary gland lesions after irradiation for carcinoma. J Am Dent Assoc 70: 868883, 1965.

4. Brown LR, Dreizen S, Handler S, Johnston DA: Effect of radiation induced xerostomia on human oral microflora. J Dent Res 54: 740-750, 1975.

5. Beumer J, Curtis T, Harrison RE: Radiation therapy of the oral cavity: sequelae and management. Part I. Head Neck Surg 1: 301-312, 1979.

6. Beumer J, Curtis T, Harrison RE: Radiation therapy of the

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Endodontic therapy in patients irradiated for head and neck cancer 545

oral cavity: sequelae and management.1 Part II. Head neck 13. Morrish RB, Chan E, Silverman S, Meyer J, FU KK, Surg 1: 392-408, 1979. Greenspan D: Osteoradionecrosis in patients irradiated for

7. Murray CG, Herson J, Daly TE, Zimmerman S: Radiation head and neck carcinoma. Cancer 47: 1980-1983, 1981. necrosis of the mandible: a ten year study. Part I. Factors 14. Regezi JA, Courtney RM, Kerr DA: Dental management of influencing the onset of necrosis. lnt J Radiat Oncol Biol Phys patients irradiated for oral cancer, Cancer 38: 994-1000, 6: 543-548, 1980. 1976.

8. Murray CG, et al: Radiation necrosis of the mandible: a ten 15. Poyton HG: The effects of radiation on teeth. ORAL SURG year study Part II. Dental factors: onset, duration and management of necrosis. Int J Radiat Oncol Biol Phys 6: 549-553, 1980.

9. Beumer J, Harrison, R, Sanders B, Kurrasch M: Osteoradio- necrosis-predisposing factors and outcomes of therapy: a renort of 83 euisodes during an eleven vear neriod. Head Neck S&g 7: 45-53, 1984. - . L

10. Cox FL: Endodontics and the irradiated patient. ORAL SURG ORAL MED ORAL PATHOL 42: 679-684, 1976.

Il. Montgomery S: Endodontic complications in an irradiated patient. J Endod 3: 277-279, 1977.

12. Markitziu A, Heling I: Endodontic treatment of patients who have undergone irradiation of the head and neck. ORAL SURG ORAL MED ORAL PATHOL 52: 294-298, I98 1.

ORAL MED ORAL PATHOL 26: 639-646, 1968. 16. Driezen S, Brown LR, Daly TE, Drane JB: Prevention of

xerostomia related dental caries in irradiated cancer patients. J Dent Res 56: 99-104, 1977.

17. Walker R: Direct effect of radiation on the solubility of human teeth in vitro. J Dent Res 54: 901. 1975.

Reprint requests to: Dr. Bradley G. Seto Hospital Dental Service School of Dentistry University of California Los Angeles, CA 90024