Written by Keith Rossein, DDS Sunday, 31 August 2003 19:00
One type of surgical intervention that was used in the 1960s, had resurgence in the 1990s, and is currently very popular is electrosurgery or radiosurgery. Its instruments use high-frequency radio energy to accomplish every type of surgery that can be performed with a knife but with many additional advantages. If you were to consult a medical dictionary about the definition of radiosurgery, it would refer to a type of radiation treatment for malignant tumors. However, the term radiosurgery, although unofficial, has also come to be accepted within the dental profession as electrosurgery in the higher frequency ranges of 3 to 4 MHz. A study by Maness1 concluded that the higher frequency range produced less lateral heat, and therefore, less tissue destruction.
|Figure 1. RadioSurge instrument with active electrode in the handpiece and passive dispersive electrode (Macan Engineering).||Figure 2. UltraFlex bendable electrodes (Macan). These are bendable with finger pressure for easier access to the oral cavity.|
Radiosurgery has many advantages when compared to a cold knife. In radiosurgery, the instrument can cut (filtered waveform) tissue, cut and coagulate (rectified waveform) at the same time, or only coagulate (partially rectified waveform), depending on what mode the clinician chooses. This ability to control bleeding ensures greater visibility during surgical procedures. Because the electrodes are bendable at the insulated portion of their shaft, they provide easy access to difficult posterior and lingual areas of the mouth (Figures 1 and 2). These benefits usually result in reduced chair time and better quality restorations. When using a scalpel, the clinician is crunching bacteria into the wound, thus increasing the possibility of infection. As soon as an electrosurgical tip is activated, it vaporizes any microorganisms it contacts.
The capability to plane soft tissue is unique to radiosurgery, is less invasive than an incision, and usually requires no sutures. Radiosurgery gives the clinician a fantastic tool to sculpt and contour soft tissue, making it the instrument of choice in many cosmetic situations.
When utilizing radiosurgery, the clinician needs to be confident in the final results; they should be consistent and predictable. By controlling lateral heat, this can be achieved. It’s a simple concept. Produce enough heat to accomplish the task without producing additional heat that will alter or destroy the tissue. The electrode tip never gets hot. The tissue offers resistance to the radio waves (RF waves) as they enter, causing the cells to heat up and explode. Lateral heat is represented by a formula, not in the mathematical sense, but rather one that must keep the various factors in balance:
Lateral Heat = Time x Power x Size x Waveform x Frequency x Tissue Resistance
Most of these factors are under the control of the clinician, including the amount of time in which the electrode is in contact with the tissue, the size of the chosen electrode, and the waveform and power settings being utilized. In other words, the clinical results will directly correspond to the handling of these dynamics. Clinicians must understand how to stay within the parameters of the lateral heat theory, using their professional judgment to adjust the settings appropriately for each patient.
CLINICAL APPLICATIONS OF RADIOSURGERY
Some of the cosmetic applications for radiosurgery include (1) elongation of a clinical crown, (2) development of an emergence profile for a pontic or an implant abutment, (3) soft-tissue grafting, (4) troughing before crown and bridge impressions, (5) removal and contouring of hypertrophied tissue, (6) maxillary frenectomies, and (7) various gingivoplasty procedures. When utilizing radiosurgery for these procedures, there will be an absence of tissue shrinkage and a high degree of predictability (as long as the tissue is healthy from the start). As a general rule, when working near bone, implants, or thin delicate tissue, use only the cut (filtered) waveform.
Most restorative dentists perform crown and bridge procedures every day. Prior to taking the final impression, it is traditional to pack the sulcus with retraction cord to achieve hemostasis and to create separation of the sulcular tissue from the margin of the tooth preparation. This is time-consuming and often is very traumatic to the tissue, sometimes resulting in a tear of the gingival attachment.
|Figure 3. Tooth No. 9 will be replaced with a fixed bridge. (Figures 2 through 7 courtesy of Joseph L. Caruso, DDS, MS.)||Figure 4. Biological width is being determined and measured.|
|Figure 5. Radiosurgery was utilized to provide pre-impression troughing around the prepared teeth. It was also used to contour the pontic ridge and to create a buccal emergence profile.||Figure 6. Note the accuracy of the impression because of electrosurgical soft tissue management.|
Radiosurgery is excellent for managing the soft tissue when preparing for crowns and bridges (Figures 3 through 6). It can be used to contour the ridges upon which pontics will sit and to modify interproximal papillae. It can also can be used to trough around a tooth prior to the impression as well as prior to cementation. This widens the sulcus into a funnel shape that allows the impression material to flow unimpeded. The electrode tip also removes tissue tags that could create notches along the finishing line in the impression. For anterior troughing, a thin wire electrode on the cut (filtered) waveform with the lowest possible power setting is critical in preventing tissue shrinkage and the possibility of having to remake the crown because of exposed margins. It is critical that the clinician avoids cutting through the epithelial attachment.
|Figure 7. After tooth preparation for ceramic inlays, interproximal tissue has been removed utilizing radiosurgery.||Figure 8. Note the precise impression with clear interproximal margins.|
With the great advances in strength and longevity of aesthetic materials and the development of computerized technology such as the Cerec machine, ceramic inlays and onlays have become popular. Often, interproximal tissue creates bleeding problems or interferes with the accuracy of the impression material. Radiosurgery is a quick and easy solution to these problems (Figures 7 and 8).
|Figure 9. Gingivectomy to increase clinical crown height as well as to establish the proper biological width prior to crown placement. (Figures 8 through 20 courtesy of Peter Liaros, DDS.)|
|Figure 10. Removal of palatal tissue.|
|Figure 11. Tissue sutured in place.|
Single- or multiple-tooth gingivectomies are commonly performed with radiosurgery (Figures 9 through 11). Often it is necessary to expose subgingival decay, and radiosurgery is very useful in these circumstances. With the current emphasis on aesthetic dentistry, radiosurgery is used to increase the crown-to-root ratio for cosmetic purposes and for clinical crown elongation to establish a more aesthetic smile line prior to bonding, porcelain veneers, or crowns in the aesthetic zone. However, the clinician must be careful not to violate the biologic width unless bone surgery is part of the treatment plan. The lateral heat parameters for these procedures would be the use of thin wire electrodes on the cut waveform with low power settings and preferably a higher frequency radiosurgery unit.
|Figure 12. Donor graft site on maxillary right palate marked.||Figure 13. Electrode in position prior to removal of donor tissue.|
|Figure 14. Thin wire electrode on filtered cut mode removes the donor tissue.||Figure 15. Recipient site prior to initial radiosurgical incision.|
|Figure 16. Incision with thin wire electrode on filtered cut waveform to create recipient site.||Figure 17. Recipient site established.|
|Figure 18. Donaor graft sutured in place.|
There are instances where soft-tissue grafts are necessary to replace lost or receded tissue (Figures 12 through 18). An electrode on the cut (filtered) mode can touch bone as long as the clinician keeps the electrode moving. When harvesting tissue from the donor site, be sure to use only the filtered cut waveform so there is no hemostasis. If you get coagulation, the graft won’t take.
|Figure 19. Presurgical: hyperplastic tissue due to denture irritation. Small oval loop will be used to remove and contour the tissue using cut-and-coag mode (fully rectified).||Figure 20. Tissue “shaving” accomplished.|
Tissue shaving or planing is an exceptional technique for various types of gingivoplasty. The clinician becomes an artist—a tissue sculptor. When not near bone, the loops should be used on cut-and-coag waveform (fully rectified), which provides a blend of 50% cutting and 50% coagulation. This is excellent for patients who have hypertrophied tissue from drugs such as Dilantin, irritation from orthodontic bands and braces, or irritation from dentures (Figures 19 and 20).
Cosmetic dentistry has become the mainstay of most restorative practices. Optimizing success when treating patients in the aesthetic zone requires training, skill, an excellent dental laboratory, and a variety of materials, instruments, and techniques. The ability to manage soft tissue in its relationship to the teeth and restorations is essential to the final outcome. Radiosurgery offers the clinician a modality for safe and predictable manipulation of the soft tissue through controlled-use RF energy.
1. Maness WL, Roeber FW, Clark RE, et al. Histologic evaluation of electrosurgery with varying frequency and waveform. J Prosthet Dent. 1978;40:304-308.
Disclosure: Dr. Rossein is a paid consultant for Macan Engineering and Manufacturing Company.
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