Dueling Lasers by Dr. Samuel B. Low

Dueling Lasers 

A gingival treatment case study and a look at today’s laser options


by Dr. Samuel B. Low


While it may be difficult to determine when the first gingivectomy was performed in the oral cavity, some suggest it was performed by the French dentist Etienne Bourdet, who in 1757 created a V-shaped incision between a patient’s teeth to the bottom of the pocket. However, the gingivectomy did not truly become highlighted in the discipline of periodontics until the mid-1940s. Major periodontal icons such as Goldman, Glickman, Beube and Hirschfeld all describe the gingivectomy as a major “go-to” in managing periodontal pockets. With the advent of the flap procedure in the 1950s, the gingivectomy slowly became less popular because of patient complaints of discomfort and the significant recession as the result of the blade excisions.

Traditional definitions for the gingivectomy can be convoluted, but still should be differentiated from the gingivoplasty. Definitions of each can be found below:


Gingivectomy: Excision of gingiva by removing the diseased pocket wall, thereby exposing tooth surface to provide the visibility and accessibility that are essential for the complete removal of irritating surface deposits and thorough smoothing of the roots. Benefits include:
  • Diseased tissue is removed.
  • Pocket depth is reduced.
  • Periodontal disease is controlled.
  • Patient has improved ability to maintain good hygiene.
Gingivoplasty: A surgical reshaping of the gingiva for a more ideal physiologic contour, including sculpting gingivae for aesthetic reasons. Benefits include:
  • Reducing a gummy smile.
  • Fixing uneven gingival contours.
With the advent of the flap creating excellent visualization for access to both teeth and osseous structures, the gingivectomy should be utilized more frequently as a monotherapy for the management of periodontal disease. It is an excellent procedure for excisional removal of supragingival (pseudo-pocket) tissue to gain access for multiple objectives, from orthodontics to restorative. It indeed is an angular excision to the tooth structure with the resulting collar removed for exposure. Therefore, the new, more modern definition of gingivoplasty would be contouring existing gingiva without a complete dissection of the connective tissue and more sculpting of the gingivae.


Indications
While there may be a perception of relative simplicity of the gingivectomy procedure, there are major contraindications.


Compromising attached gingivae. Creating an excision that eliminates or significantly reduces the zone of attached gingivae truly compromises the periodontium and the ensuing periodontal health. The zone of attached keratinized tissue is immovable and fibrous, surrounding the neck of each tooth. It extends from the free gingival margin to the mucogingival junction. This tissue is resistant to recession from oral hygiene, mastication and trauma. Alveolar mucosa composed of elastic fibers cannot resist most trauma or even normal oral hygiene because of its mobility. The respective sulcus can also be a reservoir for biofilm. When deciding between a flap or gingivectomy, if the gingivectomy is chosen, one must maintain at least 3 mm of attached gingivae after the excision (Fig. 1). The option of utilizing an apically repositioned flap is preferred any time the attached gingivae zone may be compromised.

Fig. 1
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Fig. 1: To ensure biologic width, the zone of attached gingivae should be 2–3 mm.


Encroachment on supracrestal attached tissues. Supacrestal attached tissues (as biologic width is now called by the American Academy of Periodontology) are composed of the junctional epithelium and the supracrestal connective tissue attachment. There can be a significant variability in this width. However, placement of restorative materials within this zone is associated with inflammation. Most would agree that there must be a distance of 2.5mm between a restorative margin and the height of crestal bone. When gingival crown lengthening is performed as in orthodontics, excision of gingivae without adherence to this “zone” will result in the relapse/rebound of the gingivae, which will move coronally from the surgical position. A technique for sounding the osseous levels including the relationship to the cementoenamel junction is to probe under topical or local anesthesia. That measurement determines how much gingivae can be removed or whether a flap with osseous crown length is the preferred procedure.

In summary, if a clinician is presented with a patient condition demonstrating adequate attached gingivae, and there is no need to have access to perform osseous recontouring, a gingivectomy is often the preferred procedure.



Technique
Initial incisions for gingivectomies are similar to those created when using a blade with an external bevel approach. The distance of the incision from the coronal gingival margin is based on pocket depth and amount of existing attached gingiva. A gingival chamfer (beveled edge) is achieved, rather than a direct right angle into the gingiva (Figs. 2a–2c, p. 55). The initial cut is made slightly apically to the pocket depth measurement. A slow, unidirectional hand motion is used, moving the tip at an external bevel toward the tooth structure.

Fig. 2a
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Fig. 2b
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Fig. 2c
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Fig. 2: Incision made with external bevel for crown length. (2a: Preoperative view with clinically short lateral. 2b: Initial incision. 2c: Excised collar removed.)

 Determine where the excision should be outlined from the distance of the coronal gingival margin without compromising the attached gingivae.

The angle of the excision as an external bevel should be based on the thickness of gingivae. With very thin gingivae, the excision can be more perpendicular to the long axis of the tooth (Fig. 3a). If the gingivae lies within normal limits, an obtuse angle can be utilized (Fig. 3b). However, with thick gingivae, the excision angle should be more acute to the long access of the tooth (Fig. 3c). This can create a wide-beveled edge with thick gingivae. We desire parabolic margins that blend with the new gingival margin.

Several passes may be necessary to excise the tissue to the tooth surface. The action should be slow and done in a unidirectional hand motion. The collar then can be removed with a curette.

Fig. 3
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Fig. 3:  The bevel is dependent on the thickness of the gingival biotype. a. Thin, b. Normal, c. Thick


Gingivectomy instrumentation
Since the beginning of the gingivectomy, several instrumentation devices have been implemented including knives, blades, scissors, chemicals, diamonds, rotary burs, electrosurgery and, more recently, dental lasers. As we move from the gingivectomy being a procedure for periodontal disease to more of a procedure for restorative access and aesthetics, devices will continue to change.


Knives and blades: The advantage of utilizing manual cutting instruments is that they are plentiful and inexpensive. The primary essential periodontal knives are the Kirkland 15/16 and the Orban 1/2 (Fig. 4). The Kirkland is more for gross excisions, especially on the straight buccal and lingual/palatal area, and is a pointed kidney-shaped knife. The Orban 1/2 is thinner in width, angled and provides great access to interproximal posterior areas for excision of gingivae. Some clinicians prefer to lead with the Kirkland knife and retrace the excision with the Orban knife. The Orban can separate the collar in the interproximal area and remove the gingival collar intact. Both knives are angled and double-ended for access.

The greatest disadvantage of the manual knife is that it requires repeated sharpening. If not razor-sharp, cutting efficiency is compromised, which not only affects time it takes to perform a procedure, but also can result in irregular tissue margins. While vasoconstriction can be achieved with local anesthetics, there can be significant hemorrhage during the procedure, hindering visualization and possibly creating postoperative complications.

Fig. 4a
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Fig. 4b
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Figs. 4a and 4b: Gingivectomy manual cutting instruments. (4a: Kirkland 15/16. 4b: Orban 1/2.)


Electrosurgery: This device can create division of tissue by high-frequency electrical current applied locally with a metal instrument or needle. They are readily available and relatively inexpensive. The primary mode of tissue interaction with electrosurgical instruments is by heat ablation. The zone of necrosis after electrosurgery can be between 500–1,500 μm. Most activity with electrosurgical devices is excisional with a single wire electrode. The radiofrequency energy is concentrated, disrupting tissue cells with lateral heat. Results depend on contact duration, dose and electrode tips. Bipolar electrosurgery units are an improvement over monopolar in that they generate less heat and rely more on a continuous pulse.

One must be concerned with electrosurgery that is utilized near teeth, bone and implants because of thermal conduction. Bone necrosis can occur with delayed healing because of compromised vascularity due to heat. One should avoid contact with osseous structures, such as dental implants. Electrode contact with a root surface can create resorption and inhibit tissue attachment. Studies differ on pulpal necrosis.


Dental lasers: Utilization of lasers for gingivectomy and gingivoplasty procedures has resulted in a significant adoption curve by the dental profession, especially for the diode wavelengths. If the gingivectomy procedure is utilized for access, then lasers have a significant advantage over traditional manual blades because they create hemostasis: Lasers seal lymphatics and capillaries. Initial wound healing can be delayed, particularly when compared with blades; however, laser healing can decrease immediate fibroblast regeneration, resulting in less wound contraction and less scar production.

As compared with electrosurgery, most laser wavelengths have a significant decrease in the zone of necrosis. With diode and Nd:YAG lasers (those with neodymium-doped yttrium aluminum garnet crystals), the zone for those wavelengths is 500 μm. Erbium and CO2 lasers are 5–40 μm because of high water absorption, and require less power for removing tissue.

Each laser wavelength has its advantages and disadvantages for excisional procedures, as outlined here.


Diode and Nd:YAG lasers

Advantage: Inexpensive, portable, user-friendly and excellent for hemostasis.

Disadvantage: Slow and can create adverse thermal results if used with incorrect settings (Fig. 5, p. 56). Must be cautious around bone, tooth roots and endosseous implants.

Preferred settings should be pulsed and not continuous (Fig. 6a–c). Continuous does not rely on thermal relaxation of the heat being dissipated in the tissue and thus creates injury.


Fig. 5 GingivectomyTechniques
Fig. 6aGingivectomyTechniques
Fig. 6bGingivectomyTechniques
Fig. 6cGingivectomyTechniques
Fig. 5: Charring of tissue after using a diode laser at high power in a continuous mode.
Fig. 6: Gingivectomy with a diode on a pulsed setting. (6a: Preoperative view. 6b: Immediate postoperative view. 6c: 21-day postoperative view.)


CO2 lasers

Advantages: Fast, great for large areas for excision as biopsy with some hemostasis. Acceptable for most dental surfaces, including implants.

Disadvantage: Costlier than diodes. Larger physical footprint. Some hemostatic properties.



Erbium lasers

Advantages: Fast, minimal thermal activity because tissue interaction is with photoacoustics. Excisions are very precise, especially for aesthetic crown lengthening (Fig. 7). Has the advantage of also being able to remove bone (establish biologic width) and tooth structure (caries control, restorative prep and etch as for Class V lesions) at the time of service. Acceptable for most dental surfaces, including implants.

Disadvantages: Costlier than diodes, larger physical footprint. Hemostasis not as effective as diode.

Fig. 7
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Fig. 7: External bevel gingivectomy created with an Erbium all-tissue laser with a chromium sensitized yttrium scandium gallium garnet (Er,Cr:YSGG) crystal. Note precision and hemostasis.


When using a laser for gingivectomy, the excisions are similar to any other device utilizing an external bevel approach. However, the movement of a laser tip should be slow and methodical because the effectiveness is based on the absorption of the energy, not mechanical or purely thermal action. Again, depending on the laser wavelength, caution is necessary as one approaches tooth structure or an implant—especially with a diode or Nd:YAG because of thermal considerations. Charring is unacceptable as it demonstrates a thermal insult to the tissue and the resulting injury through necrosis. Training is essential in the operation of any laser, whether by a corporate entity or a noncommercial organization such as the Academy of Laser Dentistry.

Today’s gingivectomy is not an antiquated procedure. With the correct techniques and the suitable indications, the procedure can be implemented with minimal patient discomfort, especially when dental lasers are used. Incision/excisions are very precise and generally result in hemostasis. In addition, patients experience excellent wound healing with minimal reliance on analgesics.


Author Bio
Dr. Samuel Low Dr. Samuel B. Low was named vice president, dental and clinical affairs, and chief dental officer of Biolase in October 2016. He is professor emeritus at the University of Florida College of Dentistry and an associate faculty member of the Pankey Institute, with 30 years of private practice experience in periodontics, lasers and implant placement. He is also a diplomate of the American Board of Periodontology and past president of the American Academy of Periodontology.
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