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

The effect of endosonic and hand manipulation on the amount of root canal material extruded Howard Martin, D.M.D..* and Walter T. Cunningham, D.D.S., MS., M.A.,** Washington, D.C., and Bethesda, Md.

GEORGETOWN UNIVERSITY DENTAL SCHOOL AND NAVAL MEDICAL RESEARCH INSTITUTE

The amounts of root canal material extruded from extracted human teeth during hand and endosonic manipulation were compared. Less material was extruded when preparation was within the confines of the canal and when the endosonic system was employed.

C hemomechanical debridement of the pulp canal is considered essential for successful endodontic therapy. A possible consequence of both the mechan- ical and chemical components of canal preparation is inflammation resulting from the creation of a wound or from extrusion of debris into the periapical area. The toxic material that can be extruded generally consists of necrotic debris, dentin particles, frag- ments of tissue, microorganisms, and the tidal irri- gant.

Seltzer and associates’ demonstrated that even instrumentation short of the apex will set up an inflammatory response in the periapical area. Ingle and Beveridge2 state that files are likely to force material from the apical third of the canal into the surrounding tissue and referred to this as the

The opinions and assertions contained herein are the private ones of the writers and are not to be construed as official 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 Center, Bethesda, Md.

“worm” of necrotic debris. It was recommended that irrigation be used to clean the canal. Grossman) believed that the root canal instrument acts as a plunger, forcing material ahead of it and through the apical foramen. VandeVisse and Brilliant4 quantitat- ed the effect of irrigation by measuring the extrusion of debris through the apex and demonstrated Gross- man’s plunger effect by their use of large files against the canal walls. However, the method employed was the quarter-turn push-pull action of a file, while both Ingle and Grossman describe the push-pull motion of a file as the mode of action for extrusion.

The endosonic method of endodontics employs a high-volume continuous flow-through irrigation sys- tem with the endosonic instrument engaged in a push-pull modes as a result of ultrasonic wave energy. This study was undertaken to compare con- ventional push-pull K-type instrumentation and irri- gation with the endosonic system of endodontics for the amount of debris that is extruded through the apical foramen during debridement.

MATERIALS AND METHODS

Thirty-eight extracted human teeth were opened for endodontic access and filed through the apex with a No. 15 file to ensure canal patency. The teeth were

611

612 Martin and Cunningham OEd SUrg. June, 1982

Table I. The amount of material extruded using endosonic and hand canal preparation

Preparation Preparation

+wthod length

Hand

Ultrasonic

Hand

Ultrasonic

Protruding

Protruding

I mm. inside

1 mm. inside

(a) vs (b)

(~1 vs Cd)

(cl vs (a)

Cd) vs (b)

e~tZZ~~~. 1

1.39 + 0.28 (a)

0.87 + 0.41 (b)

0.53 2 0.21 (c)

0.22 + 0.14 (d)

p < 0.01 p < 0.001 p < 0.001 p < 0.001

randomly placed into four groups. All groups were irrigated copiously with 2.5 percent sodium hypo- chlorite, files were cleaned regularly, and canals were prepared to size 40 to 45 with a push-pull motion only.

Group I consisted of nine teeth which were hand manipulated at a length such that the file was observed to just protrude through the apex, while the nine teeth of Group II were ultrasonically prepared to that same length. Group III consisted of ten teeth prepared by hand to a distance 1 mm. short of the foramen, while the ten teeth of Group IV were ultrasonically prepared to that same distance just inside the canal.

The amount of material extruded in each case was collected on a filter paper, desiccated over phospho- rus pentoxide for 4 days to eliminate the variable of differing moisture content within the test material, and weighed. The mean weight extruded for each group was compared by means of Student’s t test.

RESULTS

The results of this study are presented in Table I. The endosonic system produced significantly less extruded material than hand manipulation, whether the canal was prepared short of the foramen (p < 0.001) or past the apex (p < 0.01). In addition, less material was extruded with either method when the canal was prepared to a distance just inside the apical foramen (p < 0.001).

DISCUSSION

The results of this study demonstrate the reduced extrusion of material through the apex that occurs with endosonic canal preparation. The studies by Seltzer and associates’ on the effects of over and under instrumentation show that, for optimum repair, instrumentation should be confined to the canal. Any additional irritation will aggravate an already susceptible periapical tissue. Therefore, this

study substantiates that debridement should be care- fully controlled as to length and method in order to minimize the extrusion of toxic material through the apex.

The rasping action, or push-pull motion, of the K-type file creates a greater pressure apically than does the quarter-turn method. The result is a tenden- cy, especially if applied within 1 to 2 mm. of the apex, to force debris through and into the periapical tissue. However, the quarter-turn method is less successful in cleaning the canal because the instru- ment tends to behave rather as a reamer than as a file. The common ovoid or ribbon-shaped canal will be debrided more effectively with a push-pull action, since this filing motion can engage these configura- tions.

As VandeVisse and Brilliant4 point out, the larger the size of the file used, the greater the amount of material extruded from the apex. The endosonic system employs smaller files, allowing for less pres- sure even in a push-pull action and thus maintaining a smaller apical matrix. SchildeP emphasizes that the apex should not be enlarged beyond a No. 25 file. This will prevent internal apical translocation and decrease the potential for excessive perapical irrita- tion. The use of smaller endosonic files and safe- ended endosonic diamonds allows for the develop- ment of a proper apical matrix while reducing the amount of potential irritation.

Grossman’ states that “in all cases a combination of biomechanical and chemical means, i.e., instru- mentation and irrigation, will be necessary to effect complete debridement and cleansing of the root canal.” Irrigation is a necessary and important phase of cleansing the canal. The irrigant functions as a lavage and flush, a solvent, a disinfectant, and a lubricant within the canal. VandeVisse and Brilliant4 used 5 ml. of the irrigant, 5.25 percent sodium hypochlorite, per treatment of canal and concluded that, although irrigation was necessary, it led to extrusion. This pushing of material from the canal into periapical tissue has been confirmed in viva.’ The endosonic system employs a high-volume, con- tinuous irrigation with an effective treatment volume of 35 to 45 ml. per minute. Although the endosonic technique used considerably more irrigant, which other studies7,8 show to be the most effective method of canal cleansing, less material was found to be extruded. This may be due to the fact that the constant aspiration decreases the ability of the irri- gant to force debris apically and removes material that is floating due to sonication. VandeVisse and Brilliant4 did not use suction methods, whereas aspiration is an integral part of the endosonic system

Volume 53 Number 6

of endodontics. Also, the warmed 2.5 percent sodium hypochlorite9 has a strong solvent action on organic material which allows for effective sonication, flota- tion, and aspiration, thus leading to a rapid reduction of material within the root canal.

The energized endosonic file, even though operat- ing in the push-pull mode, requires very little positive apical pressure. This is due to Huygen’s classic principle of physics which states that an energy wave always propagates in a forward motion away from its original source. In this case, the energy wave is moving along the entire length of the endosonic instrument into the canal, pulling the instrument along the canal pathway. The drawing of the file into the canal does not require the operator to apply the amount of pressure that is necessary with the inac- tive hand-manipulated file. This is another signifi- cant difference in the method of canal preparation by the endosonic system.

Thus, the lack of apical pressure due to the ultrasonic energizing of the instrument, the use of small-sized endosonic files and safe-ended diamonds, and an ultrasonically activated high-volume continu- ous irrigation coupled with proper aspiration all contribute to an ultrasonic canal preparation tech- nique that allows for effective canal dibridement with significantly reduced extrusion of canal materi- al.

SUMMARY

Whether prepared within the confines of the canal or overinstrumented, endosonic preparation tech-

Effect of endosonic and hand manipulation 613

niques produced significantly less extruded material than did hand manipulation. In addition, preparation past the apex produced significantly more extruded material.

REFERENCES

I.

2.

3.

4.

5.

6.

I.

8.

9.

10.

Seltzer, S., Soltanoff, W., Sinai, I., Goldenberg, A., and Bender, I.: Biologic Aspects of Endodontics. Ill. Periapical Reactions to Root Canal Instrumentation, ORAL SURG. 26: 534, 1968. lngle, J., and Beveridge, E.: Endodontics, ed. 2, Philadelphia, 1976, Lea & Febiger, pp. 168-176. Grossman, L.: Endodontic Practice, ed. 8, Philadelphia, 1974, Lea & Febiger, pp. I63- 164. VandeVisse, J., and Brilliant, J.: Effect of Irrigation on the Production of Extruded Material at the Root Apex During Instrumentation, J. Endod. 1: 243-246, 1975. Martin, H., Cunningham, W., and Norris, J.: A Quantitative Comparison of the Ability of Diamond and K-Type Files to Remove Dentin, ORAL SURG. 50: 566-568, 1980. Schilder, H.: In Cohen, S., and Burns, R.C. (editors): Pathways of the Pulp, ed. 2, St. Louis, 1980, The C.V. Mosby Company, pp. I I I-1 20. Salzgeber, R., and Brilliant, J.: An In Vivo Evaluation of the Penetration of an Irrigating Solution in Root Canals, J. Endod. 3: 394-398, 1911. Baker, N., Eleazer, P., Averbach, R., and Seltzer, S.: Scan- ning Electron Microscope Study of the Efficacy of Various Irrigating Solutions, J. Endod. 1:127-135, 1975. Cunningham, W., and Joseph, S.: Effect of Temperature on the Bacterial Action of Sodium Hvoochlorite Endodontic lrrigant, ORAL SURG. 50: 569-571, l!%O. Cunningham, W., Martin, H., and Forrest, W.: Evaluation of Root Canal Dtbridement by the Endosonic Ultrasonic Syner- gistic System, ORAL SURC. 53: 401-404, 1982.

Reprint requests to: Dr. Howard Martin 909 Pershing Dr. Silver Spring, Md. 20910