Oral Health Group
Feature

Oral Surgery: Understanding the Principles and Applications of Oral Radiosurgery

October 1, 2003
by Keith D. Rossein, D.D.S.


Oral electrosurgery or radiosurgery is widely accepted throughout the world and has a broad range of clinical applications. Electrosurgery is an excellent alternative to the scalpel or lasers for soft tissue management, and in most instances, would be the instrument of choice. For those practitioners that want to incorporate electrosurgery into their routine patient treatment protocols, there is a learning curve that is critical to its implementation. Once the clinician understands the nature of the various waveforms and how electrosurgical technology relates to clinical results, a comfort level will be reached making clinical applications safe, easy and predictable.

Electrosurgery is the passage of high frequency radio waves (RF energy) into soft tissue resulting in a variety of clinical effects, including cutting, cutting and coagulation at the same time, coagulation or tissue destruction. Because of the resistance offered by the tissue to the incoming RF energy, the tissue heats up. The electrode tip never gets hot. In actuality, the water in the cells is boiled causing the cells to explode. The action is similar to a microwave that places food between two large conductive panels so that the radio waves can travel back and forth from one panel to another, producing heat in the food. The radio frequency waves are in the same range as an AM radio (Fig. 1).

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What is the difference between electrosurgery and radiosurgery? Dorland’s Medical Dictionary defines radiosurgery as, “surgery in which tissue destruction is performed by means of ionizing radiation rather than surgical incision.” It usually involves implanted radioactive material. However, radiosurgery has also become an unofficial but accepted term referring to electrosurgery instruments (Fig. 2) that fall into the higher frequency range of 3-4 mHz (3-4 million cycles per second). A study by Maness et al in 1978 (“Histologic Evaluation with Varying Frequency and Waveform.” J. of Prosthetic Dentistry) concluded that higher frequency electrosurgical units produce less tissue alteration than those instruments with frequencies under 2 mHz.

To reach a level of confidence and competence, the clinician needs to understand how to control lateral heat (Fig. 3). Lateral heat is the build up of heat in the tissue adjacent to the active electrode. It’s a very simple concept. The practitioner must learn to guide and control the RF energy entering the tissue so that enough heat is produced to accomplish the task at hand without creating additional heat that will cause tissue alteration or destruction.

The control of lateral heat depends on various factors that are depicted in the following formula. As long as the formula is kept in balance and the clinician stays within acceptable parameters, electrosurgery will be safe and effective. It’s when the formula becomes lopsided, usually from a clinician’s error that unwarranted tissue destruction occurs.

Time refers to the time the active electrode is in contact with the tissue. The electrode should never be held stationary in soft tissue. The faster the movement of the electrode, the less lateral heat produced, with the reverse being true–the slower the movement, the more lateral heat produced. The clinician should work at a controlled speed wherein they have adequate finger rests and the proper tactile sense–a speed that allows him/her to safely perform the procedure.

An activated electrode should not be placed in the same surgical site for 8-10 seconds, so that the tissue has time to cool down. Accordingly, do not move the electrode back and forth like you were painting. Try to keep it going in one direction.

Time is also significant when touching bone. You can cut a full thickness flap right down to the periosteum, as long as you keep the electrode moving and as long as the waveform is set to cut (filtered), another consideration in the lateral heat formula. There are procedures such as troughing for crown and bridge and gingivectomies where the tooth can be used as a guide for the electrode.

In other situations like bleaching and desensitizing, the electrode is purposely held against the tooth surface. Time is still critical. For every second that an activated electrode touches the tooth, the pulpal temperature will rise 7 degrees. With an increase of 15-20 degrees, the pulp will die. Therefore, one must still remain within the parameters of one second on and ten seconds off. Clinically, for example, when troughing before taking an impression, it should be done in quadrants or halves, waiting sufficient time in between. Always, give soft or hard tissue time to cool down.

Power is the output power of the electrosurgical instrument that is adjusted by the clinician with a dial, as necessary for a specific procedure. As a general rule, try to keep the power as low as possible. The greater the power, the more lateral heat produced and the visa versa. Less power creates less lateral heat.

However, if the clinician is uncertain as to the correct power setting, it is better to err slightly on the high side than on the low end. If the power is too low, the tissue may rip (in response to the practitioner’s pressure trying to avoid drag), the electrode may break or the electrode may become “stuck” in the tissue causing extreme lateral heat from a lack of movement (time factor). Additionally, too low a power causes tissue to adhere to the electrode, inhibiting the radio waves and making the unit less efficient.

Critical to successful electrosurgery is working with a “tuned” unit. To tune your electrosurgical unit, set it up in the room where it will be routinely used. Placed the antenna plate on the dental chair with a piece of beefsteak atop the plate. Adjust the power to an estimated setting, and on the “cut” waveform with a thin wire electrode, make an incision about 2 mm into the steak. If there is sparking while cutting, tune it lower; if there is drag or tissue sticking to the electrode, tune it up; repeat this procedure several times until the electrode moves easily through the tissue in the absence of sparking or drag. A small spark when the electrode first enters or leaves the tissue is not a problem.

Once properly tuned, this will be your starting point for each patient. As a suggestion, place a pencil mark on the instrument to indicate the exact “tuned” position. Just before beginning treatment for any patient, the dial can be “fine tuned” based on the size of the electrode and the nature of the tissue. With this method, your power setting should always be very close to optimum, only having to make minor power corrections.

The greater the size of the electrode, the more lateral heat produced. With thinner diameter electrodes or smaller surface areas of contact, the less accumulation of lateral heat. Size is an important contributing factor when considering good electrosurgical technique. Except in 1-2 procedures (troughing, gingivectomy), the electrode should be held perpendicular to the tissue when making incisions or excisions (Fig 4). Otherwise the clinician is inadvertently creating a larger size electrode, even with the same diameter wire by placing more metal (greater surface area) in the tissue.

Certain procedures require the use of a larger electrode. For example, a spoon electrode, with a wider surface area, is use for bleaching to create and apply heat to more tooth surface. Electrodes utilized for coagulation are designed to be thicker than cutting electrodes.

The appropriate waveform must be chosen and preset by the practitioner depending on the clinical procedure. For some procedures, a combination of waveforms may be utilized. The coagulation wave (partially rectified) produces the most amount of lateral heat. The cut + coag wave (fully rectified) produces less lateral heat, and the cut (filtered) wave produces the least amount of lateral heat. So, the cut setting would be the waveform of choice when working near bone or implants, when performing biopsies or when tissue shrinkage is of concern.

Frequency is the one factor in the lateral heat formula that is controlled o
nly once by the clinician–when he/she purchases an electrosurgery instrument. That is because the manufacturer, by design, establishes a specific frequency, which remains constant and cannot be adjusted by the operator.

The lower frequency electrosurgical units usually seen in a hospital OR (.5 mHz) require that the antenna (passive electrode) contacts the patient’s skin with an applied jelly for better conduction. The higher frequency dental units require no skin contact. Higher frequency units produce less lateral heat and, therefore, less tissue alteration. The optimal frequency appears to be in the 3-4 mHz range.

Tissue resistance is the last factor in keeping the lateral heat formula in balance. Remember the basic concept of electrosurgery/radiosurgery–that RF energy is converted to heat energy when the tissue offers resistance to its flow. Tissue that is very dry will offer more resistance. Some patients will have dry mouths due to decreased salivary flow. Systemic problems such as a salivary gland tumor or Sjgren’s Syndrome may be the cause.

Many medications including anti-histamines, tranquilizers and some blood pressure drugs will cause a dry mouth. In these instances, the tissue should be moistened with a wet gauze pad before using electrosurgery. If the tissue is thick or fibrous such as in a tuberosity reduction, it will offer more resistance. This will necessitate turning up the power, thereby, creating the potential for greater lateral heat.

The lateral heat formula is an excellent guideline for practicing safe and efficient electrosurgery. The clinician must use his/her professional judgment depending on the patient’s medical history, the condition of the mouth and tissues and the procedure to be performed and then choose the appropriate settings to stay within the parameters of the lateral heat formula.

There are numerous indications for oral electrosurgery. Some include bleeding control, cosmetic elongation of clinical crowns, soft tissue management during crown and bridge procedures (Figs. 5-8, Clinical photos courtesy of Joseph L. Caruso, D.D.S., M.S.), biopsies, frenectomies, pulpotomies, harvesting tissue for gingival grafts, any type of incisions or excisions and tissue contouring (Figs. 9-12, Clinical photos courtesy of Peter Liaros, D.D.S.). Tissue planning is unique to electrosurgery/radiosurgery, is minimally invasive and usually requires no sutures.

Electrosurgery offers numerous advantages to the dental practitioner. When integrated into the daily practice routine, electrosurgery can be a terrific stress reducer, especially when it comes to access (bendable electrodes) and visibility (bleeding control) during clinical treatment. With the electrosurgical handpiece, the dentist has better tactile control than with a scalpel, since he/she is guiding RF energy through the electrode without pressure. The end results are reduced chair time and better quality restorations.

Once the practitioner understands his/her radiosurgical instrument and how to control its radio frequency energy, a comfort zone will be reached and both the patient and dentist will benefit.

Dr. Rossein is President of International Dental Consultants a partner in WebDentalMarketing.com.

Oral Health welcomes this original article.


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