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A histologic and electronic evaluation of electrosurgical currents: Nonfiltered full-wave modulated vs. filtered current
A histologic and electronic evaluation of electrosurgical currents: Nonfiltered full-wave modulated vs. fi|tered current Ralph B. Sozio, D.M.D.,* Edwin J. Riley, D.M.D.,** and Gerald Shklar, D.D.S., M.S.*** Harvard School o/Dental Medicine, Boston, Mass.
I n 1924, William L. C l a r k / a noted surgeon and considered by many to be the "father of American electrosurgery," wrote (with his colleagues) : "Knowledge concerning the electrothermic methods is, however, not so general, owing, perhaps, to meager teaching in medical schools, to a dearth of authentic literature upon the subjects, to prejudice against the method employing electricity, to want of standardized and efficient equipment, to improper technique (hence poor results and fallacious conclusions), and to the failure of the comparatively few who do employ them correctly to report their work in a convincing manner." What Clark wrote in 1924 is true today, in many respects, especially in the dental field, where widespread confusion and controversy exist regarding the physical and biologic factors relating to the use of electrosurgery.
BACKGROUND From 1910 to 1930, the various forms of electrosurgery became widely used in the field of tumor surgery. Clark felt one form, "desiccation", which is monoterminal, was subject to perfect control, and he used it to remove growths from the cornea with no impairment of vision, from the vocal cords with no impairment of speech, as well as for various carcinomas, t However, others felt that the biterminal currents designed for "coagulation" produced better resultsY A controversy thus developed and was enlarged in 1924 when Wyeth a introduced the endothermic knife, which was a prototype of many of the instruments being proRead before the Greater New York Academy of Prosthodontics, New York, N. Y. *Assistant Clinical Professor; Director of Post-Doctoral Fixed Prosthodontics. **Clinical Fellow in Prosthodontics. ***Charles A. Brackett Professor of Oral Pathology and Head, Department of Oral Medicine and Oral Pathology. 300
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Fig. 1, (A) The precision-machined interlocked Lucite grid with tongue properly positioned and stabilized. (B) Probe tip inserted into grid with desired depth and stability established by acrylic stop.
duced today for dental use. In 1925, Ward's 4 histologic and clinical studies did much to achieve acceptance of the idea of the endothennic knife, and he concluded that the then new electrothermic machines provided more accurate control. In 1929, McLean ~ confirmed the histologic observations of Clark and Ward, but he warned against overstressing and making a mystery of wave form, something which still persists today. Results of recent investigations and thus recommendations concerning the use of electrosurgery in the dental field have varied widely. Using a partially rectified current for gingival retraction in dogs, Klug '~ found that healing was rapid and uneventful in all instances and caused a crestal height loss in gingiva of only 0. l ram. He concluded, therefore, that electrical retraction is safe and effective. Malone; performed gingivectomies on 10 patients one quadrant with electrosurgery and the other with a b l a d e ~ a n d found no clinical difference in healing. Malone and associates s and Eisenman and co-workers:' performed gingivectomy with electrosurgery and knife and then examined the tissue with the light and electron microscope immediately and after seven days. They concluded that the results of electrosurgery and conventional blade were indistinguishable and found no difference in healing. On the other hand, Pope ~° found delayed healing and more bone injury with electrosurgery than with the blade. Schmitz a~ and Poswillo v'- also found delayed healing with electrosurgery when compared to knife. Glickman and Imber a:~ found essentially no differences for shallow resections but significant differences in deep resections, including pronounced recession and bone necrosis with electrosurgery. Schieda and co-workers, TM however, have shown that a detrimental effect does not necessarily occur when an electroscalpel comes in direct contact with crestal bone. The controversy over healing is not new. It was present among the early tumor surgeons, with Ward ~ and Burgess ~'~ claiming no difference between knife and electrosurgery while Ellis ~ and McLean 5 felt that there was. It persisted, among the early dental advocates, with Ogus ~7, TM claiming faster healing with electrosurgery and Saghirian a"-'~ claiming slower healing. Despite the healing controversy, which continues to this day, the use of electrosurgery has become widespread, receiving clinical recommendations from many authors. -~'-'-3~ The diverse opinions and results of the
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Fig. 2. (A) Mechanized apparatus with constant-speed motor, proper gear ratio, and animal in position. (B) Mechanical movement of probe tip in Lucite grid.
past are not surprising if one considers that, except for a few earl), tumor surgeons, none of the investigators knew the amperage and voltage he was applying; some were confused as to whether they were using full-tuave modulated, half-wave modulated, or filtered current~; instruments of different design were used, which meant that differences in performance could be expected; and, fietally, the operator's technique or stroke with the electrosurgical instrument was never controlled, operator variability being significant. PURPOSE
The purpose of this investigation was twofold: 1. To develop a controlled system for examining tissue response to electrosurgery. A controlled system includes: A. Mechanical control, i.e., standardization o f - 1. Depth of wound 2. Width of wound 3. Speed and continuity of incision (lack of acceleration and deceleration) B. Electronic control, i.e., standardization of--1. Amperage 2. Average voltage 3. Wave form II. Utilizing the above controls, to compare nonfiltered full-wave modulated and filtered electrosurgical currents histologically, with respect to tissue alteration and healing. METHODS AND MATERIALS
Three incisions were made on the dorsal surface of the tongues of inbred adult guinea pigs from one lateral border to the other under general anesthesia (Nembutal, 30 rag. per kilogram of body we~ght intraperitoneally). One control incision was * I n past dental literature, full-wave modulated current has been referred to as fully rectified, half-wave modulated as partially rectified, and filtered current as fully rectified filtered current.
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Fig. 3. (A) Oscilloscope, electrosurgical unit, and special component for monitoring amperage and average voltage. (B) Electronic and mechanical controls,
made in each animal with scalpel blade. The other two incisions were made with the Whaledent Strobex electrosurgical unit, utilizing the same electrode tip, the difference being that one incision was made with filtered current and the other with nonfiltered full-wave modulated current. Mechanical standardization
Depth of wound. The depth and spacing between the two incisions were controlled by a precision-machined grid, consisting of two interlocked pieces of Lucite which encased the extended tongue. The dorsum of the tongue was stabilized against the inner surface of the upper member of the grid by means of a Plasticine material* (Fig. 1, A). The outer surface of the grid was designed.so that a scalpel blade or electrosurgical probe could be inserted into one of three slots and slid across the tongue at a desired depth. The actual depth was held constant by p l a c i n g a n acrylic stop on the probe tip and blade. The acrylic stops fit into the slots of the Lucite grid, which prevented lateral, vertical, and rotational movements of the probe and blade (Fig. 1, B). Width of wound. The width of the probe was measured with a micrometer (0.356 ram.), and a scalpel blade was selected which had the same thickness (Fisher No. 11). Speed and continuity o/incision. The stroke was controlled by a constant-speed synchronous motor (Herst heavy duty ARDA 10) which pushed the electrode probe along the slots and across the tongue without acceleration or deceleration. The speed was maintained at 1.27 era. per second by means of the 10 r.p.m, motor and the proper gear ratio (Fig. 2, A and B). Electronic standardization Wave form was verified on an oscilloscope (547 Tetronic). Amperage.was monitored by means of a Simpson RF milliammeter (0 to 500 ma.). Average voltage was monitored by means of a Simpson RF miIliammeter (0 to I00 ma.) converted to a *Periphery plastic, Van R. Dental Products, Inc., Los Angeles, Galif.
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- FILTERED
Fig. 4. Actual photographs of the two currents employed as seen on the oscilloscope: filtered and nonfiltered full-wave modulated.
Fig. 5. (A) Unit employing "cut" setting (filtered current) with intensity dial positioned so that the established amperage and average voltage were delivered. (B) Unit employing "coagulation" setting (nonfiltered full-wave modulated current) with intensity dial positioned so that the established amperage and average voltage were delivered. voltmeter by placing it in series with a noninductive resistor (25W, 2K) (Figs. 3 and 4, ,4 and B). Trial incisions were performed to obtain the optimum current intensity necessary to produce the desired incision with absence of drag and sparking with the filtered current. The amperage and average voltage were recorded, and tile power was calculated. T h e amperage and average voltage were then held constant in each incision regardless of wave form, whether filtered or non filtered, and regardless of the dial setting on the electrosurgical instrument (Fig. 5, A and B). Thus, with the above mechanical and electronic controls, tile only difference in any of the electronically made incisions was the wave form: nonfiltered full-wave modulated vs. filtered.
Surgical procedures T h e three incisions (blade, filtered current, and nonfiltered full-wave modulated current) were made on the tongues of 18 adult guinea pigs. T h e middle wound was in all instances made by the scalpel blade, and the wounds at the tip and base of the
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Fig. 6. (A) Sagittal survey section of tongue immediately after the cross-sectional incisions were made on the dorsal surface. Anterior and posterior wounds show deeply stained coagulative margins. (Hematoxylin and eosin stain. Original magnification x50.) (B) High-power view of anterior incision made with nonfiltered full-wave modulated electrosurgical current. Note the coagulation of the surface epithelium and the zone of coagulation within the connective tissue and musculature along tile margins of the incision. (Hematoxylin and eosin stain. Original magnification x150.) (C) High-power view of middle incision made with scalpel. There is no margin of coagulation. (Hematoxylin and eosin stain. Original magnification x150.) tongue were m a d e with the electrosurgical currents. T h e two electrosurgieal incisions (nonfiltered full-wave m o d u l a t e d a n d filtered) were a l t e r n a t e d between a p e x a n d base so as to eliminate a n y a n a t o m i c differences which could influence tissue alteration or healing. T h r e e animals were killed i m m e d i a t e l y a n d at time intervals of one, two, four, seven, a n d 14 days.
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Histology The tongues were carefully dissected free. and fixed in 10 per cent formalin. The specimens were prepared for histologic study, sectioned in paraffin, and stained with hematoxylin and eosin. The specimens were coded so that blind histologie evaluations were carried out.
RESULTS Immediately following the incisions, a distinct difference was noted between the incisions made by the knife and those made by eittler electrosurgical current. The latter demonstrated coagulated margins where the tissue appeared amorphous in texture and deeply stained. The incisions made by the knife presented clean, uncoagulated margins (Fig. 6, A to C). After 24 hours, the knife wound was healing by first intention with apposition of lateral walls while the electrosurgical wounds were healing by second intention. In the eleetrosurgical wounds, the incision walls were separated, and the surface of the tissue was densely infiltrated with polymorphonuclear leukocytes and lymphocytes. Leukocytes were also noted within the base of the wound. The epithelial margins of the wound presented coagulative degeneration and necrosis. In the knife wound at 24 hours, the epithelial margins were in close apposition and presented no evidence of coagulation or necrosis. The wound itself was'filled in with blood clet, and only the surface epithelium was separated (Fig. 7, A to C). After four days, the knife wound demonstrated re-epithelization, and normal anatomic topography ",,,,as returning. The blood clot was being replaced with connective tissue. The electrosurgical wounds demonstrated delayed healing. Epithelization was progessing at the electrosurgical wotmd sites; however, they demonstrated a greater degree of inflammation, and surface morphology had not achieved the level of the blade incisions. In comparing the filtered and non filtered electrosurgical incisions, a slight variation in healing was observed. The nonfiltered full-wave modulated wound sites at both apex and base demonstrated somewhat slower healing than did the filtered electrosurgical wound sites (Fig. 8). After one week, all the wounds were epithelized, although the blade wounds were healing more rapidly. In contrast to the blade wounds, the electrosurgical wounds demonstrated more intense connective tissue inflammation and a foreign-body reaction. However, there was essentially no discernible difference in healing in the oneweek specimens between non filtered full-wave modulated and filtered current wounds (Fig. 9). After two weeks, the healing was more advanced, but some subepithelial pathology was still evident. However. little difference in healing existed at the three wound sites (Fig. 10).
DISCUSSION In all instances, the scalpel wounds demonstrated more rapid healing in the early stages than did the wounds made by either of the two electrosurgical currents. The exl~erimental electrosurgical wounds were characterized by a microscopic layer of coagulum and delayed healing. Essentially. the knife wound healed by first intention, with incision walls in close apposition and sealed by blood clot.
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Fig. 7. (A) Sagittal survey section of tongue 24 hours after incisions. Note the deep anterior and posterior wounds with intense inflammatory infiltration and the relatively shallow wound in the middle. (Hematoxylin and eosin stain. Original magnification ×50.) (B) High-power view of anterior incision made with nonfiltered full-wave modulated electrosurgical current. There is extensive suppuration, and the walls of the wound are separated. The epithelium facing the wound appears necrotic. (Hematoxylin and eosin stain. Original magnification x150.) (C) High-power view of central wound made with a scalpel. The wound has been filled in with blood clot, and only the surface epithelium is separated. The epithelium appears normal on either side of the wound. (Hematoxylin and eosin stain. Original magnification x150.)
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Fig. 8, A and B. Sagittal survey section of two tongues four days after incisions were made. Central knife wounds demonstrate epithelization and return of anatomic topography. Electrosurgical wounds at anterior and posterior sites demonstrate delayed healing when compared to the knife wounds. The nonfihered electrosurgical wound sites demonstrate a somewhat slower healing response than do the filtered wounds.
Healing by first intention was inhibited in tim electrosurgical wounds. Tissue apposition appeared to be inhibited by the necrotic, coagulated surface of the incision walls. While the electrosurgical wounds healed with a more gradual epithelization, the subepithelial tissue presented a "foreign-body" reaction, presumably caused by the coagulated fragments of epithelium, connective-tissue collagen, and muscle bundles. However, in our controlled circumstances, tile healing rates of the electrosurgical and blade wounds were essentially comparable at tile two-week level, and subsequently, one could expect little difference at any of the healing sites.
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Fig. 9. Sagittal survey section of tongue one week after the incisions were made. All are now epithelized, but tire central knife wound shows relatively normal connective tissue and muscle while the anterior wound shows extensive, deep involvement. The posterior wound demonstrates less subepithelial pathosis than is shown at the anterior wound, but a deep pit is evident. (Hematoxylin and eosin stain. Original magnification x50.) Fig. 10. Sagittal survey section of tongue two weeks after the incisions were made. All are epithelized, and the pits are shallow. Some subepithelial pathosis is evident. (Hematoxylin and eosin stain. Original magnification x50.) W h e n nonfi]tered full-wave m o d u l a t e d a n d filtered c u r r e n t wounds were comp a r e d , the nonfiltered electrosurgical incisions healed at a slightly slower rate t h a n the filtered c u r r e n t incisions, b u t the healing sites were c o m p a r a b l e within one week. T h e histologic findings are i m p o r t a n t , because they d e m o n s t r a t e t h a t u t i l i z i n g a p a r t i c u l a r wave form does not g u a r a n t e e a p a r t i c u l a r tissue effect. T h e r e is no mystery in wave form, for a p p a r e n t l y little if a n y a d v a n t a g e existed in this study in utilizing filtered c u r r e n t over nonfiltered full-wave m o d u l a t e d c u r r e n t w h e n dealing with n o r m a l tissue. However, in a p a t i e n t with r e t a r d e d healing responses resulting
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from some systemic cause, the slight differential exhibited between the filtered and nonfiltered wounds could be of some clinical importance. In the course of the investigation, we also found, as did Friedman, '~0 that the so-called "cut" and "coagulation" modalities on most electrosurgical instruments available for dental use provide only one wave form, i.e., nonfiltered full-wave modulated current. We also monitored analgerage and voltage and found that the only difference in those instruments with one type of wave form was a slight decrease in voltage when the coagulation setting was employed. Our observation, therefore, concurs with that of Friedman that there is basically no difference in most of the units between the coagulation and cut settings.
CONCLUSIONS What do these findings mean for the dental profession? 1. We should not make a mystery of wave form. In our controlled circumstances, filtered current did not demonstrate remarkably better healing than nonfiltered fullwave modulated current. In addition, both currents demonstrated coagulated incision margins. Thus, when making a pure, undisturbed, controlled incision through epithelium, subepithelial connective tissue, and muscle, neither current "cut exactly like a knife." 2. We should demand from the electrosurgical manuf,scturers an increased standardization of power controls and an elimination of some confusing and apparently meaningless controls. 3. We should re-evaluate our clinical techniques so as to more efficiently employ this extremely useful adjunct in dental therapy. Intelligent use of electrosurgery demands a recognition and understanding of both its limitations and its capabilities. In otlr opinion, it can be effectively employed in restorative dentistry. :':~ To achieve its full potential, however, further standardization and perfection of both the instrumentation and clinical techniques should be pursued.
SUMMARY A controlled system for examining the tissue alteration and healing of electrosurgicaIly produced wounds was established. Standardization of width, depth, stroke, anlperage, average voltage, and w,'ive form was achieved. A histologic comparison of tissue alteration and healing produced by a conventional blade and two electrosurgical currents was carried out. The need for standardization of instrumentation and clinical procedures is discussed. Sincere thanks is expressed to Sidney Lees, Ph.D., of Forsyth Dental Infirmary, and Karl Kreeb, B.L.A.S., of G.T.E. Sylvania, Inc., for their technical advice and to Gert Quigley of Forsyth Dental Infirmary for her help and assistance.
References 1. Clark, W. I,., Morgan, J. D., and Asnis, E. J.: Electrothermic Methods in the Treatment
of Neoplasms and Other Lesions, With Clinical and Histological Observations, Radiology 2: 233-246, I924.
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2. Corbus, B. C.: Diathermy in Stomatology, J. A, M. A. 85: 1614-1619, 1925. 3. Wyeth, G. A.: Surgery of ]Neoplastic Diseases by Electrothermlc Methods, New York, 1926, Paul B. Hoeber, Inc. 4. Ward, G. E. : Value of Electrothermic Methods in the Treatment of Malignancy, J. A. M. A. 84: 660-666, 1925. 5. MeLea.n, A. J.: The Boyle Electrosurgieal Current Generator, Arch. Surg. 18: 1863-1873, 1929. 6. Klug, R. G.: Gingival "l'issue Regeneration Following Electrical Retraction, J. PROSTHE'r. D~"r. 16: 955-962, 1966. 7. Malone, W. F.: Electrosurgery in Restorative Dentistry, J. PaosTrlr'r. DENT. 20: 417-425, 1968. 8. Malone, W. F., Eisenmann, D., and Kusek, J.: Interceptive Periodontics With Electrosurgery, J. PROSa'HST. DENT. 22: 555-564, 1969. 9. Eisenmann, D., Malone, W. F., and Kusek, J.: Electron Microscopic Yvaluation of Electrosurgery, Oral Surg. 29: 660-665, 1970. 10. Pope, J. W.: Effect of Electrosurgery on Wound Healing, J. Tenn. State Dent. Assoc. 51: 18-28, 1971. 11. Schmitz, J.: Clinical Study of Inflammatory Papillary Hyperplasla, J. PROSTH~.T. DENT. 14: 1034-1039, 1964. 12. Poswillo, D. E.: A Comparative Study of the Effects of Eleetrosurgery and Cryosurgery in Management of Benign Oral Lesions, Br. J. Oral Surg. 9: 1-7, 1971. 13. Glickman, I., and Imber, I.. R.: Comparison of Gingival Resection With Electrosurgery and Periodontal Knives. A Biometrie and Histologie Study, J. Periodontol. 41: 142-148, 1970. 14. Schieda, J. D., De Marco, T. J., and Johnson, L. E., Jr.: Alveolar Bone Response to the Electrosurgical Scalpel, J. Periodontol. 43: 225-232, 1972. 15. Burgess, A.: Electrosurgery, Lancet 2: 1355-1359, 1933. 16. Ellis, J. D.: The Rate of Healing of Electrosurgieal Wounds as Expressed by Tensile Strength, J. A. M. A. 96: 16-18, 1931. 17. Ogus, W. I.: "]'he Elimination of the Pyorrheal Pocket by Electrosurgery, Am. J. Orthod. Oral Surg. 27: 135-144, 1941. 18. Ogus, W. I.: Electrosurgery in Dentistry, Dent. Dig. 48: 411-417, 1942. 19. Saghirian, L. M.: Stomatological Aspects of Electrosurgieal Methods, Dent. Items Interest 64:112-121, 212-230, 1942. 20. Saghirian, L. M.: Electrosurgery in the Mouth, Dent. Dig. 46: 20-28, 1940. 21. Saghirian, L. M.: Electrosurgical Correction of Low Frenum and Oval Tissue Bands, Dent. Dig. 48: 10-15, 1942. 22. Sch6n, F.: The Technique of Electrosurgery in the Treatment of Periodontal Diseases, Quintessence Int. 2: 51-56, 1971. 23. Podashly, A. G.: Electrosurgical Preparation of Gingival Tissue for Elastic Impression Materials, J. Tenn. State Dent. Assoc. 48: 104-108, 1968. 24. Podashly, A. G.: Electrosurgical Procedures in Crown and Bridge Restorations, J. Am. Dent. Assoc. 77: 1321-1326, 1968. 25. Myer, I.: Electrocoagulation of Oral Lesions, Oral Surg. 16: 522-528, 1963. 26. Weaver, D. F.: Use of Electrosurgery in Head and Neck, Arch. Otolaryngol. 77: 289294, 1963. 27. Feldman, G., Solonlon, C., Notaro, P., et al.: Electrosurgery~Endodontic Applications, N. Y. State Dent. J. 36: 605-608, 1971. 28. Oringer, M. J.: Fundamentals of Electrosurgery, J. Oral Surg., Anesth. Hosp. Dent. Serv. 18: 39-40, 1960. 29. Oringer, M. J.: Electrosurgery for Definitive Conservative Modern Periodontal Therapy, Dent. Clin. North Am. 13: 53-73, 1969. 30. Oringer, M. J: Evaluation of Dental Electrosurgical Devices, J. Am. Dent. Assoc. 78: 799-802, 1969. 31. Oringer, M. J.: Electrosurgery in Dentistry, Philadelphia, 1962, W. B. Saunders Company.
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3'2. Friedman, J.: The Technical Aspects of Electrosurgery, Oral Surg. 36: 177-187, 1973. 33. Sozio, R. B.: Use of Electrosurgery in Restorative Dentistry, Visucassette Lecture Tape Series, Health Information Systems Inc., 1971. DR. SozIo 100 CHARLES RIVER PLAZA No. 603 BOSTON, MASS. 02114 DR. RILEY DEPARTMENT OF PROSTHETIC DENTISTRY H[ARVARD SCHOOL OF DENTAL MEDICINE 188 L O N G W O O D AVE. BOSTON, MASS. 02115
DR. SHKLAR DEPARTMENT OF ORAL MEDICINE AND ORAL PATHOLOGY HARVARD SCHOOL OF DENTAL MEDICINE 188 L O N O W O O D AVE. BOSTON, MASS. 02115
I n 1924, William L. C l a r k / a noted surgeon and considered by many to be the "father of American electrosurgery," wrote (with his colleagues) : "Knowledge concerning the electrothermic methods is, however, not so general, owing, perhaps, to meager teaching in medical schools, to a dearth of authentic literature upon the subjects, to prejudice against the method employing electricity, to want of standardized and efficient equipment, to improper technique (hence poor results and fallacious conclusions), and to the failure of the comparatively few who do employ them correctly to report their work in a convincing manner." What Clark wrote in 1924 is true today, in many respects, especially in the dental field, where widespread confusion and controversy exist regarding the physical and biologic factors relating to the use of electrosurgery.
BACKGROUND From 1910 to 1930, the various forms of electrosurgery became widely used in the field of tumor surgery. Clark felt one form, "desiccation", which is monoterminal, was subject to perfect control, and he used it to remove growths from the cornea with no impairment of vision, from the vocal cords with no impairment of speech, as well as for various carcinomas, t However, others felt that the biterminal currents designed for "coagulation" produced better resultsY A controversy thus developed and was enlarged in 1924 when Wyeth a introduced the endothermic knife, which was a prototype of many of the instruments being proRead before the Greater New York Academy of Prosthodontics, New York, N. Y. *Assistant Clinical Professor; Director of Post-Doctoral Fixed Prosthodontics. **Clinical Fellow in Prosthodontics. ***Charles A. Brackett Professor of Oral Pathology and Head, Department of Oral Medicine and Oral Pathology. 300
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Fig. 1, (A) The precision-machined interlocked Lucite grid with tongue properly positioned and stabilized. (B) Probe tip inserted into grid with desired depth and stability established by acrylic stop.
duced today for dental use. In 1925, Ward's 4 histologic and clinical studies did much to achieve acceptance of the idea of the endothennic knife, and he concluded that the then new electrothermic machines provided more accurate control. In 1929, McLean ~ confirmed the histologic observations of Clark and Ward, but he warned against overstressing and making a mystery of wave form, something which still persists today. Results of recent investigations and thus recommendations concerning the use of electrosurgery in the dental field have varied widely. Using a partially rectified current for gingival retraction in dogs, Klug '~ found that healing was rapid and uneventful in all instances and caused a crestal height loss in gingiva of only 0. l ram. He concluded, therefore, that electrical retraction is safe and effective. Malone; performed gingivectomies on 10 patients one quadrant with electrosurgery and the other with a b l a d e ~ a n d found no clinical difference in healing. Malone and associates s and Eisenman and co-workers:' performed gingivectomy with electrosurgery and knife and then examined the tissue with the light and electron microscope immediately and after seven days. They concluded that the results of electrosurgery and conventional blade were indistinguishable and found no difference in healing. On the other hand, Pope ~° found delayed healing and more bone injury with electrosurgery than with the blade. Schmitz a~ and Poswillo v'- also found delayed healing with electrosurgery when compared to knife. Glickman and Imber a:~ found essentially no differences for shallow resections but significant differences in deep resections, including pronounced recession and bone necrosis with electrosurgery. Schieda and co-workers, TM however, have shown that a detrimental effect does not necessarily occur when an electroscalpel comes in direct contact with crestal bone. The controversy over healing is not new. It was present among the early tumor surgeons, with Ward ~ and Burgess ~'~ claiming no difference between knife and electrosurgery while Ellis ~ and McLean 5 felt that there was. It persisted, among the early dental advocates, with Ogus ~7, TM claiming faster healing with electrosurgery and Saghirian a"-'~ claiming slower healing. Despite the healing controversy, which continues to this day, the use of electrosurgery has become widespread, receiving clinical recommendations from many authors. -~'-'-3~ The diverse opinions and results of the
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Sozio, Riley, and Shklar
J. Prosthet. Dent.
March, 1975
Fig. 2. (A) Mechanized apparatus with constant-speed motor, proper gear ratio, and animal in position. (B) Mechanical movement of probe tip in Lucite grid.
past are not surprising if one considers that, except for a few earl), tumor surgeons, none of the investigators knew the amperage and voltage he was applying; some were confused as to whether they were using full-tuave modulated, half-wave modulated, or filtered current~; instruments of different design were used, which meant that differences in performance could be expected; and, fietally, the operator's technique or stroke with the electrosurgical instrument was never controlled, operator variability being significant. PURPOSE
The purpose of this investigation was twofold: 1. To develop a controlled system for examining tissue response to electrosurgery. A controlled system includes: A. Mechanical control, i.e., standardization o f - 1. Depth of wound 2. Width of wound 3. Speed and continuity of incision (lack of acceleration and deceleration) B. Electronic control, i.e., standardization of--1. Amperage 2. Average voltage 3. Wave form II. Utilizing the above controls, to compare nonfiltered full-wave modulated and filtered electrosurgical currents histologically, with respect to tissue alteration and healing. METHODS AND MATERIALS
Three incisions were made on the dorsal surface of the tongues of inbred adult guinea pigs from one lateral border to the other under general anesthesia (Nembutal, 30 rag. per kilogram of body we~ght intraperitoneally). One control incision was * I n past dental literature, full-wave modulated current has been referred to as fully rectified, half-wave modulated as partially rectified, and filtered current as fully rectified filtered current.
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Fig. 3. (A) Oscilloscope, electrosurgical unit, and special component for monitoring amperage and average voltage. (B) Electronic and mechanical controls,
made in each animal with scalpel blade. The other two incisions were made with the Whaledent Strobex electrosurgical unit, utilizing the same electrode tip, the difference being that one incision was made with filtered current and the other with nonfiltered full-wave modulated current. Mechanical standardization
Depth of wound. The depth and spacing between the two incisions were controlled by a precision-machined grid, consisting of two interlocked pieces of Lucite which encased the extended tongue. The dorsum of the tongue was stabilized against the inner surface of the upper member of the grid by means of a Plasticine material* (Fig. 1, A). The outer surface of the grid was designed.so that a scalpel blade or electrosurgical probe could be inserted into one of three slots and slid across the tongue at a desired depth. The actual depth was held constant by p l a c i n g a n acrylic stop on the probe tip and blade. The acrylic stops fit into the slots of the Lucite grid, which prevented lateral, vertical, and rotational movements of the probe and blade (Fig. 1, B). Width of wound. The width of the probe was measured with a micrometer (0.356 ram.), and a scalpel blade was selected which had the same thickness (Fisher No. 11). Speed and continuity o/incision. The stroke was controlled by a constant-speed synchronous motor (Herst heavy duty ARDA 10) which pushed the electrode probe along the slots and across the tongue without acceleration or deceleration. The speed was maintained at 1.27 era. per second by means of the 10 r.p.m, motor and the proper gear ratio (Fig. 2, A and B). Electronic standardization Wave form was verified on an oscilloscope (547 Tetronic). Amperage.was monitored by means of a Simpson RF milliammeter (0 to 500 ma.). Average voltage was monitored by means of a Simpson RF miIliammeter (0 to I00 ma.) converted to a *Periphery plastic, Van R. Dental Products, Inc., Los Angeles, Galif.
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Fig. 4. Actual photographs of the two currents employed as seen on the oscilloscope: filtered and nonfiltered full-wave modulated.
Fig. 5. (A) Unit employing "cut" setting (filtered current) with intensity dial positioned so that the established amperage and average voltage were delivered. (B) Unit employing "coagulation" setting (nonfiltered full-wave modulated current) with intensity dial positioned so that the established amperage and average voltage were delivered. voltmeter by placing it in series with a noninductive resistor (25W, 2K) (Figs. 3 and 4, ,4 and B). Trial incisions were performed to obtain the optimum current intensity necessary to produce the desired incision with absence of drag and sparking with the filtered current. The amperage and average voltage were recorded, and tile power was calculated. T h e amperage and average voltage were then held constant in each incision regardless of wave form, whether filtered or non filtered, and regardless of the dial setting on the electrosurgical instrument (Fig. 5, A and B). Thus, with the above mechanical and electronic controls, tile only difference in any of the electronically made incisions was the wave form: nonfiltered full-wave modulated vs. filtered.
Surgical procedures T h e three incisions (blade, filtered current, and nonfiltered full-wave modulated current) were made on the tongues of 18 adult guinea pigs. T h e middle wound was in all instances made by the scalpel blade, and the wounds at the tip and base of the
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Fig. 6. (A) Sagittal survey section of tongue immediately after the cross-sectional incisions were made on the dorsal surface. Anterior and posterior wounds show deeply stained coagulative margins. (Hematoxylin and eosin stain. Original magnification x50.) (B) High-power view of anterior incision made with nonfiltered full-wave modulated electrosurgical current. Note the coagulation of the surface epithelium and the zone of coagulation within the connective tissue and musculature along tile margins of the incision. (Hematoxylin and eosin stain. Original magnification x150.) (C) High-power view of middle incision made with scalpel. There is no margin of coagulation. (Hematoxylin and eosin stain. Original magnification x150.) tongue were m a d e with the electrosurgical currents. T h e two electrosurgieal incisions (nonfiltered full-wave m o d u l a t e d a n d filtered) were a l t e r n a t e d between a p e x a n d base so as to eliminate a n y a n a t o m i c differences which could influence tissue alteration or healing. T h r e e animals were killed i m m e d i a t e l y a n d at time intervals of one, two, four, seven, a n d 14 days.
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Histology The tongues were carefully dissected free. and fixed in 10 per cent formalin. The specimens were prepared for histologic study, sectioned in paraffin, and stained with hematoxylin and eosin. The specimens were coded so that blind histologie evaluations were carried out.
RESULTS Immediately following the incisions, a distinct difference was noted between the incisions made by the knife and those made by eittler electrosurgical current. The latter demonstrated coagulated margins where the tissue appeared amorphous in texture and deeply stained. The incisions made by the knife presented clean, uncoagulated margins (Fig. 6, A to C). After 24 hours, the knife wound was healing by first intention with apposition of lateral walls while the electrosurgical wounds were healing by second intention. In the eleetrosurgical wounds, the incision walls were separated, and the surface of the tissue was densely infiltrated with polymorphonuclear leukocytes and lymphocytes. Leukocytes were also noted within the base of the wound. The epithelial margins of the wound presented coagulative degeneration and necrosis. In the knife wound at 24 hours, the epithelial margins were in close apposition and presented no evidence of coagulation or necrosis. The wound itself was'filled in with blood clet, and only the surface epithelium was separated (Fig. 7, A to C). After four days, the knife wound demonstrated re-epithelization, and normal anatomic topography ",,,,as returning. The blood clot was being replaced with connective tissue. The electrosurgical wounds demonstrated delayed healing. Epithelization was progessing at the electrosurgical wotmd sites; however, they demonstrated a greater degree of inflammation, and surface morphology had not achieved the level of the blade incisions. In comparing the filtered and non filtered electrosurgical incisions, a slight variation in healing was observed. The nonfiltered full-wave modulated wound sites at both apex and base demonstrated somewhat slower healing than did the filtered electrosurgical wound sites (Fig. 8). After one week, all the wounds were epithelized, although the blade wounds were healing more rapidly. In contrast to the blade wounds, the electrosurgical wounds demonstrated more intense connective tissue inflammation and a foreign-body reaction. However, there was essentially no discernible difference in healing in the oneweek specimens between non filtered full-wave modulated and filtered current wounds (Fig. 9). After two weeks, the healing was more advanced, but some subepithelial pathology was still evident. However. little difference in healing existed at the three wound sites (Fig. 10).
DISCUSSION In all instances, the scalpel wounds demonstrated more rapid healing in the early stages than did the wounds made by either of the two electrosurgical currents. The exl~erimental electrosurgical wounds were characterized by a microscopic layer of coagulum and delayed healing. Essentially. the knife wound healed by first intention, with incision walls in close apposition and sealed by blood clot.
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Fig. 7. (A) Sagittal survey section of tongue 24 hours after incisions. Note the deep anterior and posterior wounds with intense inflammatory infiltration and the relatively shallow wound in the middle. (Hematoxylin and eosin stain. Original magnification ×50.) (B) High-power view of anterior incision made with nonfiltered full-wave modulated electrosurgical current. There is extensive suppuration, and the walls of the wound are separated. The epithelium facing the wound appears necrotic. (Hematoxylin and eosin stain. Original magnification x150.) (C) High-power view of central wound made with a scalpel. The wound has been filled in with blood clot, and only the surface epithelium is separated. The epithelium appears normal on either side of the wound. (Hematoxylin and eosin stain. Original magnification x150.)
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Fig. 8, A and B. Sagittal survey section of two tongues four days after incisions were made. Central knife wounds demonstrate epithelization and return of anatomic topography. Electrosurgical wounds at anterior and posterior sites demonstrate delayed healing when compared to the knife wounds. The nonfihered electrosurgical wound sites demonstrate a somewhat slower healing response than do the filtered wounds.
Healing by first intention was inhibited in tim electrosurgical wounds. Tissue apposition appeared to be inhibited by the necrotic, coagulated surface of the incision walls. While the electrosurgical wounds healed with a more gradual epithelization, the subepithelial tissue presented a "foreign-body" reaction, presumably caused by the coagulated fragments of epithelium, connective-tissue collagen, and muscle bundles. However, in our controlled circumstances, tile healing rates of the electrosurgical and blade wounds were essentially comparable at tile two-week level, and subsequently, one could expect little difference at any of the healing sites.
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Fig. 9. Sagittal survey section of tongue one week after the incisions were made. All are now epithelized, but tire central knife wound shows relatively normal connective tissue and muscle while the anterior wound shows extensive, deep involvement. The posterior wound demonstrates less subepithelial pathosis than is shown at the anterior wound, but a deep pit is evident. (Hematoxylin and eosin stain. Original magnification x50.) Fig. 10. Sagittal survey section of tongue two weeks after the incisions were made. All are epithelized, and the pits are shallow. Some subepithelial pathosis is evident. (Hematoxylin and eosin stain. Original magnification x50.) W h e n nonfi]tered full-wave m o d u l a t e d a n d filtered c u r r e n t wounds were comp a r e d , the nonfiltered electrosurgical incisions healed at a slightly slower rate t h a n the filtered c u r r e n t incisions, b u t the healing sites were c o m p a r a b l e within one week. T h e histologic findings are i m p o r t a n t , because they d e m o n s t r a t e t h a t u t i l i z i n g a p a r t i c u l a r wave form does not g u a r a n t e e a p a r t i c u l a r tissue effect. T h e r e is no mystery in wave form, for a p p a r e n t l y little if a n y a d v a n t a g e existed in this study in utilizing filtered c u r r e n t over nonfiltered full-wave m o d u l a t e d c u r r e n t w h e n dealing with n o r m a l tissue. However, in a p a t i e n t with r e t a r d e d healing responses resulting
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from some systemic cause, the slight differential exhibited between the filtered and nonfiltered wounds could be of some clinical importance. In the course of the investigation, we also found, as did Friedman, '~0 that the so-called "cut" and "coagulation" modalities on most electrosurgical instruments available for dental use provide only one wave form, i.e., nonfiltered full-wave modulated current. We also monitored analgerage and voltage and found that the only difference in those instruments with one type of wave form was a slight decrease in voltage when the coagulation setting was employed. Our observation, therefore, concurs with that of Friedman that there is basically no difference in most of the units between the coagulation and cut settings.
CONCLUSIONS What do these findings mean for the dental profession? 1. We should not make a mystery of wave form. In our controlled circumstances, filtered current did not demonstrate remarkably better healing than nonfiltered fullwave modulated current. In addition, both currents demonstrated coagulated incision margins. Thus, when making a pure, undisturbed, controlled incision through epithelium, subepithelial connective tissue, and muscle, neither current "cut exactly like a knife." 2. We should demand from the electrosurgical manuf,scturers an increased standardization of power controls and an elimination of some confusing and apparently meaningless controls. 3. We should re-evaluate our clinical techniques so as to more efficiently employ this extremely useful adjunct in dental therapy. Intelligent use of electrosurgery demands a recognition and understanding of both its limitations and its capabilities. In otlr opinion, it can be effectively employed in restorative dentistry. :':~ To achieve its full potential, however, further standardization and perfection of both the instrumentation and clinical techniques should be pursued.
SUMMARY A controlled system for examining the tissue alteration and healing of electrosurgicaIly produced wounds was established. Standardization of width, depth, stroke, anlperage, average voltage, and w,'ive form was achieved. A histologic comparison of tissue alteration and healing produced by a conventional blade and two electrosurgical currents was carried out. The need for standardization of instrumentation and clinical procedures is discussed. Sincere thanks is expressed to Sidney Lees, Ph.D., of Forsyth Dental Infirmary, and Karl Kreeb, B.L.A.S., of G.T.E. Sylvania, Inc., for their technical advice and to Gert Quigley of Forsyth Dental Infirmary for her help and assistance.
References 1. Clark, W. I,., Morgan, J. D., and Asnis, E. J.: Electrothermic Methods in the Treatment
of Neoplasms and Other Lesions, With Clinical and Histological Observations, Radiology 2: 233-246, I924.
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2. Corbus, B. C.: Diathermy in Stomatology, J. A, M. A. 85: 1614-1619, 1925. 3. Wyeth, G. A.: Surgery of ]Neoplastic Diseases by Electrothermlc Methods, New York, 1926, Paul B. Hoeber, Inc. 4. Ward, G. E. : Value of Electrothermic Methods in the Treatment of Malignancy, J. A. M. A. 84: 660-666, 1925. 5. MeLea.n, A. J.: The Boyle Electrosurgieal Current Generator, Arch. Surg. 18: 1863-1873, 1929. 6. Klug, R. G.: Gingival "l'issue Regeneration Following Electrical Retraction, J. PROSTHE'r. D~"r. 16: 955-962, 1966. 7. Malone, W. F.: Electrosurgery in Restorative Dentistry, J. PaosTrlr'r. DENT. 20: 417-425, 1968. 8. Malone, W. F., Eisenmann, D., and Kusek, J.: Interceptive Periodontics With Electrosurgery, J. PROSa'HST. DENT. 22: 555-564, 1969. 9. Eisenmann, D., Malone, W. F., and Kusek, J.: Electron Microscopic Yvaluation of Electrosurgery, Oral Surg. 29: 660-665, 1970. 10. Pope, J. W.: Effect of Electrosurgery on Wound Healing, J. Tenn. State Dent. Assoc. 51: 18-28, 1971. 11. Schmitz, J.: Clinical Study of Inflammatory Papillary Hyperplasla, J. PROSTH~.T. DENT. 14: 1034-1039, 1964. 12. Poswillo, D. E.: A Comparative Study of the Effects of Eleetrosurgery and Cryosurgery in Management of Benign Oral Lesions, Br. J. Oral Surg. 9: 1-7, 1971. 13. Glickman, I., and Imber, I.. R.: Comparison of Gingival Resection With Electrosurgery and Periodontal Knives. A Biometrie and Histologie Study, J. Periodontol. 41: 142-148, 1970. 14. Schieda, J. D., De Marco, T. J., and Johnson, L. E., Jr.: Alveolar Bone Response to the Electrosurgical Scalpel, J. Periodontol. 43: 225-232, 1972. 15. Burgess, A.: Electrosurgery, Lancet 2: 1355-1359, 1933. 16. Ellis, J. D.: The Rate of Healing of Electrosurgieal Wounds as Expressed by Tensile Strength, J. A. M. A. 96: 16-18, 1931. 17. Ogus, W. I.: "]'he Elimination of the Pyorrheal Pocket by Electrosurgery, Am. J. Orthod. Oral Surg. 27: 135-144, 1941. 18. Ogus, W. I.: Electrosurgery in Dentistry, Dent. Dig. 48: 411-417, 1942. 19. Saghirian, L. M.: Stomatological Aspects of Electrosurgieal Methods, Dent. Items Interest 64:112-121, 212-230, 1942. 20. Saghirian, L. M.: Electrosurgery in the Mouth, Dent. Dig. 46: 20-28, 1940. 21. Saghirian, L. M.: Electrosurgical Correction of Low Frenum and Oval Tissue Bands, Dent. Dig. 48: 10-15, 1942. 22. Sch6n, F.: The Technique of Electrosurgery in the Treatment of Periodontal Diseases, Quintessence Int. 2: 51-56, 1971. 23. Podashly, A. G.: Electrosurgical Preparation of Gingival Tissue for Elastic Impression Materials, J. Tenn. State Dent. Assoc. 48: 104-108, 1968. 24. Podashly, A. G.: Electrosurgical Procedures in Crown and Bridge Restorations, J. Am. Dent. Assoc. 77: 1321-1326, 1968. 25. Myer, I.: Electrocoagulation of Oral Lesions, Oral Surg. 16: 522-528, 1963. 26. Weaver, D. F.: Use of Electrosurgery in Head and Neck, Arch. Otolaryngol. 77: 289294, 1963. 27. Feldman, G., Solonlon, C., Notaro, P., et al.: Electrosurgery~Endodontic Applications, N. Y. State Dent. J. 36: 605-608, 1971. 28. Oringer, M. J.: Fundamentals of Electrosurgery, J. Oral Surg., Anesth. Hosp. Dent. Serv. 18: 39-40, 1960. 29. Oringer, M. J.: Electrosurgery for Definitive Conservative Modern Periodontal Therapy, Dent. Clin. North Am. 13: 53-73, 1969. 30. Oringer, M. J: Evaluation of Dental Electrosurgical Devices, J. Am. Dent. Assoc. 78: 799-802, 1969. 31. Oringer, M. J.: Electrosurgery in Dentistry, Philadelphia, 1962, W. B. Saunders Company.
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3'2. Friedman, J.: The Technical Aspects of Electrosurgery, Oral Surg. 36: 177-187, 1973. 33. Sozio, R. B.: Use of Electrosurgery in Restorative Dentistry, Visucassette Lecture Tape Series, Health Information Systems Inc., 1971. DR. SozIo 100 CHARLES RIVER PLAZA No. 603 BOSTON, MASS. 02114 DR. RILEY DEPARTMENT OF PROSTHETIC DENTISTRY H[ARVARD SCHOOL OF DENTAL MEDICINE 188 L O N G W O O D AVE. BOSTON, MASS. 02115
DR. SHKLAR DEPARTMENT OF ORAL MEDICINE AND ORAL PATHOLOGY HARVARD SCHOOL OF DENTAL MEDICINE 188 L O N O W O O D AVE. BOSTON, MASS. 02115