An evaluation of postoperative pain incidence following endosonic and conventional root canal therapy Howard Martin, D.M. D., and Walter T. Cunningham, D.D.S., M.S., M.A., Wcishington, D.C., and Bethesda, Md.

GEORGtTOU’Y I hIIVk.RSITY Dt:UTAL SCHOOL AND NAVAL MEDICAL RESEARCH INSTlTlJTE

Endosonic and conventional techniques of root canal preparation were compared for the incidence of postoperative pain following treatment by the two methods. No significant difference in the amount of postoperative pain was recorded in 328 patients treated by the two techniques.

P ain resulting from endodontic procedures is linked to the inflammatory reaction and its varied stages. These may last from several hours to several days. This pain is dependent upon the damage sustained by the periapical tissue and the nature of the damaging agent. These agents may be of a bacterial, chemical, or mechanical nature. The post- treatment pain potential of various endodontic treat- ment components, such as medication, irrigation2 and instrumentation3 have been analyzed.

Endosonic endodontics, the ultrasonic synergistic system of endodontics, combines the energy of sound with a mechanical and irrigant chemical action. The purpose of this study was to compare the experience of postoperative pain in conventional procedures and in endosonic endodontics.

PROCEDURES

Cases were randomly selected as patients appeared for treatment. Patients ranged in age from 14 to 79 years, and all teeth were permanent with closed apices. All treatments were performed by one

The opinions and assertions contained herein are the private ones

of the writers and arc not to be construed as ofkial or reflecting the views of the Navy Department or the naval service at large.

The mention of commercial products in this manuscript does not constitute an endorsement or recommendation of these products by the Department of the Navy or the Department of Defense.

*Professorial Lecturer. Endodontics, School of Dentistry. George- town University. Washington. D.C.

**Dental Research Branch. Casualty Care Research Program Center. Naval Medical Research Institute, National Naval Med- ical Ccntcr. Bethesda. Md.

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operator in order to avoid the variable of individual facility, and an aseptic technique was used. The irrigant in all cases was 2.5 percent sodium hypo- chlorite, the medicament was Formocresol on a No. 3 cotton pledget squeezed dry, and the temporary seal was Cavit-G. The average time for case comple- tion was 2.5 appointments. Thus, the control group of 164 conventionally treated teeth were treated in the same manner as the experimental group of 164 teeth, except for the use of the endosonic system.

Pain, as defined in this study, meant that the patient called or returned to the office requesting a medication other than aspirin for analgesia. Thus, this study of clinical pain, like others4 was based upon the patient’s subjective evaluation. The pain incidence was compared by means of the chi-square test.

In addition, the effects of pretreatment pain and radiolucency on posttreatment pain were analyzed by means of the binomial test.

RESULTS

Of the 164 patients treated conventionally, ten experienced postoperative pain. Six of the 164 endo- sonically treated cases reported pain. The difference was not significant (p > 0.05).

The presence of preoperative pain had no signifi- cant effect on the incidence of postoperative pain for either the hand-filed (p = 0.377) or the endosonic group (p = 0.344).

The presence of a radiolucency also had no signif- icant effect in either the hand-filed (p = 0.055) or endosonically filed (p = 0.109) cases.

Volume 54 Postoperative pain following endosonic and conventional therapy 75 Number I

DISCUSSION

The results of this investigation demonstrate that postoperative pain, as defined in this study, did not occur with any significantly greater frequency when either hand or endosonic therapy was used. Seltzer5 points out that the endodontic procedures which result in pain are instrumentation of the canal, medication, irrigation, and obturation. Previous studies’-’ have recorded the type and incidence of pain to all these modalities and it is generally accepted that there is an increase in pain if there is mechanical or chemical trauma to the periapical tissues. Pain incidence of a severe nature during endodontic therapy was reported by Ingle and Zel- dowh to be 7 percent. However, Seltzer, Bender, and Ehrenreich? reported that 11 percent of their patients undergoing treatment had severe pain of more than one day’s duration while O’Keefe* showed that 13 percent of his patients had their greatest pain during or after a treatment visit. Harrison and associates2 in evaluating sodium hypochlorite toxicity for pain reaction, recorded a 6.7 percent level of moderate to severe pain. A corollary study by Harrison and associates’ regarding medication with Formocresol showed a 4 percent incidence of pain.

To evaluate properly the toxicity of any agent, consideration must be given to the amount of the agent used and to the manner in which it is used clinically.’ The minimal irritation when endosonic root canal therapy is used may be due to several factors. The use of smaller files which maintain a limited apical opening reduces the extrusion of noxious material to the surrounding tissue. This agrees with Maddox, Walton, and Davis9 who implied that a canal which is opened to the apical tissues is an irritant itself.

In addition, the endosonic system has been shown to produce a cleaner canall than does the conven- tional method, and the enhanced bactericidal activi- ty “.‘? may sufficiently reduce the bacterial flora below the critical concentration for bacterial injury. The reduced time for canal preparation may also decrease the manipulative trauma.”

There are several biophysical factors of ultrasound which may also be involved in the low degree of pain found in this study. It can be shown that the energy released into the surrounding tissues is quite limited because of the amount involved, tooth and bone biophysics, and the manner of usage. The dentin walls of the root canal develop an acoustic imped- ance barrier to the ultrasonic energy. LeesI investi- gated the acoustic properties of mineralized struc- tures and showed that dentin is almost five times

greater than collagen in impedance. Bone imped- ance” and absorption ” is four times greater than collagen. This difference is important in reducing the amount of ultrasonic energy that can be transmitted outside the confines of the canal, since this dentin- bone impedance barrier causes reflection of the energy wave to occur within the root canal. Because of changes in velocity and impedance at the pulpal and dentin-bone interface, the bulk of the ultrasonic energy is internally reflected. Refraction of the energy wave also occurs and induces an internal resonance, leading to further internal reflection of the ultrasonic wave. The remaining ultrasonic wave is reduced by divergence and decreases exponentially in tissue, it being an absorbing biologic medium. Attenuation or reduction of ultrasound in tissue is therefore due to reflection, refraction, divergence, and absorption.

Horton and associates” used ultrasound for surgi- cal removal of alveolar bone and also found postop- erative discomfort to be minimal. The incidence of postoperative endodontic pain evaluated here shows that endosonic root canal preparation caused slightly less pain than conventional methods.

Although trends were evident indicating that the presence of preoperative pain had no effect on postoperative pain and that the presence of an area was associated with less postoperative pain, no signif- icant differences existed for this small sample size.

SUMMARY

In order to compare the incidence of postoperative pain associated with root canal therapy by hand or endosonic canal preparation procedures, 164 patients treated by each of the two techniques were evaluated for the presence of posttreatment pain severe enough to require an analgesic other than aspirin. There was no significant difference in the pain incidence between the two groups.

We thank Ms. D.A. Dunham for her valuable editorial and clerical assistance and Mrs. Sheila Gretz for compiling the data. We also wish to express our appreciation to Dr. W.R. Cotton for his assistance with the manuscript.

REFERENCES

I. Harrison, J., Bellizzi. R., and Osetek, E.: The Clinical Toxicity of Endodontic Medicaments. J. Endod. 5: 42-27. 1979.

2. Harrison. J., Svec. T., and Baumgartner, J.: Analysis of Clinical Toxocity of Endodontic Irrigants, J. Endod. 4: 6-1 I, 1978.

3. Clem, W.: Posttreatment Endodontic Pain, J. Am. Dent. Assoc. 81: 1166, 1970.

4. Kast, E.: Clinical Measurement of Pain, Med. Clin. North Am. 52: 1, 1968.

_5. Seltrcr, S.: Endodontology: Biologic Considerations in Endo-

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the Bactericidal Action of Sodium Hypochlorite Endodontic lrrigant, ORAI SURG. 50~ 569-571, 1980. Martin, H.. Cunningham, W., and Norris, J.: A Quantitative Comparison of the Ability of Diamond and K-Type Files to Remove Dentin. ORAL SURC. 50: 566-569. 1980. Lees. S.: Ultrasonic in Hard Tissues. Int. Dent. J. 21: 403-417, 1971. Martin, B., and McElhaney, .I.: The Acoustic Properties 01 Human Skull Bone. J. Biomcd. Mater. Res. 5: 325-333. 1971. CJoldman. D., and Hueter, T.: Tabular Data of the Velocity and Absorption of High Frequency Sound in Mammalian Tissues, J. Acoust. Sot. Am. 29: 655. 1957. Horton. J., Tarpley, T., Jr., and Jacoaay. J.: Clinical Appli- cations of Ultrasonic Instrumentation in the Surgical Rcmov- al of Bone. ORAI SIJKG. 51: 236-243. I98 I.

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Dr. Howard Martin 909 Pershing Dr. Silver Spring, Md. 30910