July 3, 2018
by Robert A. Lowe, DDS, FAGD, FADI, FACD, FIADFE, FASDA Diplomat, American Board of Aesthetic Dentistry
Diode Lasers as a Tool in Tissue Management
Diode lasers have been used for many years as an effective adjunct for management of the gingival tissues in many areas of restorative dentistry. Prior to the development of diode lasers, electrosurgery had been used exclusively for some of the same soft tissue management indications. While there are still some procedures that are arguably useful with electrosurgery, its extensive amount of tissue damage (necrosis) limits its proper and judicious use. The electrosurgery necrosis zone is 3-5 times wider than that of a diode laser. Also, electrosurgery devices cannot be used safely around metal dental restorations or titanium implants. At a time where many restorative dentists are placing and/or restoring implants, the use of electrosurgery around them is strictly contraindicated.
The main clinician complaint with diode lasers till now has been their slow cutting due to the limits on their power (watts) to minimize collateral thermal damage. As a result, they are often used in “continuous wave” to cut faster. The down side is that the constant stream of energy can result in more tissue damage than desired, although not nearly as much as with electrosurgery. It is important that the clinician understand periodontal tissue, biotype, and crestal bone position relative to restorative margin position, before performing any laser soft tissue procedure. The clinical goals, as advances in laser technology become incorporated into the newest diode lasers, are better control of cutting and less peripheral tissue damage. 1
“Super Pulsed” Diode Lasers – A Leap in Technology
With the above goals in mind, a “super pulsed” diode laser has recently been introduced. One of the first of this “new” generation of diode lasers specifically designed for dentistry is the Gemini 810+980 Dual Wavelength Diode Laser (Ultradent Products, South Jordan UT). Most traditional diode lasers are either 810 or 980 nanometer (nm) wavelengths. The chromophores that these laser photons seek in the tissue are hemoglobin (pigment) and water. Traditional 810nm wavelength diodes are better at coagulation (hemostasis) while 980nm wavelength diodes are better at tissue ablation (cutting). Gemini combines 810nm and 980nm wavelengths in one unit to enhance the coagulation and ablation performance of traditional dental diode lasers. However, the real difference seen by combining wavelengths is the ability to achieve 20 watts of peak power (the average traditional diode peak power range is 2-5 watts) over an extremely short duty cycle (the time the laser energy is actually on). As a result, the amount of thermal relaxation that is achieved between pulses allows the tissue to cool to such a degree that the collateral necrosis (collateral tissue damage) is drastically reduced. This translates into cleaner cuts (no charring), faster healing, more control, and less patient discomfort during and after the procedure. The extent of collateral thermal effects can be decreased by a factor of about 2-3 for the super pulsed mode when compared to continuous wave traditional diode laser. Comparable incisions in depth can be achieved quickly and efficiently at lower average powers with the super pulsed diode laser. Optimal clinical results with the least risk of collateral thermal damage can be achieved with very short pulses (duty cycles) at the highest peak power possible using super pulsed technology. And, since super pulsed lasers have such low heat output, they are extremely safe to use around implant components and to uncover implants prior to the impression phase of treatment. 2
Diode Lasers Make “Everyday” Restorative Dentistry Easier and More Predictable
When asked why the average dentist looks at integration of a diode laser into his or her practice, it is usually for one reason – to replace retraction cord when taking a master impression for crown and bridge. While there are many cases where this may be true, the clinician should evaluate the gingival tissues prior to “troughing” around a preparation. A few of the questions that should be asked are: 1) is there enough attached gingiva present? 2) what is the horizontal thickness of the gingival tissue prior to troughing? 3) what is the proximity of the mucogingival junction to the base of the sulcus to be troughed? and 4) where is the crest of bone relative to the free gingival margin (high crest, normal crest, or low crest)? As long as there is a normal to thick biotype or periotype, adequate thickness in both horizontal and vertical dimensions, and a normal or high crest bone position (biologic width), troughing can be a useful tool to expose margins for both conventional and digital impressions (Figs. 1-4).
A diode laser is used to widen the gingival sulcus after placement of a #00 retraction cord (UltraPak: Ultradent Products) to make it easier to place the #1 cord above it prior to making a master impression. This will ensure total patency of the sulcular area so that the light bodied impression material will readily flow in to the submarginal area.
An occlusal view of a multiple unit prepared mandibular arch case after placement of the second retraction cords (#1 and # 2 UltraPak: Ultradent Products).
An occlusal view of the prepared arch from Figure 2 after removal of the top retraction cord. The fact that the entire second cord was visible around each preparation ensured that when pulled, 360 degrees of sulcus patency was available for the impression material to capture not only the preparation margin, but the root surface apical to the margin. The master die will now have critical emergence profile information for the dental technician to create a seamless restorative contour.
A close up of the master impression made of the prepared arch shown in Figures 2 and 3.
It is important to note however, that here are many other soft tissue procedures that can make routine dental procedures proceed more smoothly. With Class II, Class III, or Class V direct composite restorations, the gingival tissues often come into play, and most of the time this has a negative impact (bleeding) on the procedure. Since adhesive resins and composite materials are hydrophobic, moisture (saliva and/or blood) control of the operating field is essential for optimal bonding to tooth structure. Some of these areas, particularly the gingival margins of proximal boxes in Class II’s or gingival margins of Class III’s and Class V’s may be located on root surface (dentin) possibly compromising successful bonding. In these areas, there are more dentinal tubules per square millimeter and therefore less peritubular dentin to bond to, so bonding successfully in these areas requires optimal technique and moisture control. a diode laser can increase substantially the chances of successful adhesion in these areas by making the margins supragingival and stopping bleeding prior to matrix and restorative material placement (Figs. 5-7).
Tooth # 15 has an abfraction lesion on the facial surface to be restored. Since there is adequate keratinized free gingiva present, a diode laser can be used to make the gingival margin of the restored area supragingival facilitating placement of the restorative material.
The super pulsed Gemini Dual Wavelength Diode Laser (Ultradent Products) is used to expose the margin of the abfracted area on tooth #15. A long bevel has also been placed using a course diamond instrument (Komet USA) occlusal to the abfracted area on enamel for additional retention and to make it possible to aesthetically blend the composite restorative material into the facial surface making the restoration virtually invisible.
The completed Class V composite restoration on the facial surface of tooth #15. Note the seamless blend of the restorative material and also the minimal tissue necrosis as a result of the Gemini super pulsed laser.
Another useful diode laser procedure is the removal of redundant (excess) gingival tissue that may creep over crown margins during the provisional phase of treatment (if the provisional restoration has an ill-fitting (open) margin). One quick pass with a diode laser eliminates excess tissue and bleeding at the same time, simplifying the cementation process. This procedure eliminates the possibility of trapping excess tissue between the preparation and restorative margins, creating a gap for the ingress of bacteria and potential recurrent decay. This same procedure is also very useful when placing a cementable implant restoration. Often times the gingival tissues around an implant abutment will collapse around the abutment obscuring the margin on the platform of the abutment. As implant crowns usually fit very tightly and have very little space between the restoration and abutment, hydraulic pressure from excess cement can be a potential barrier to full seating of the prosthetic. If the gingival tissues are also in the way, the crown may never completely seat. It is recommended to use a diode laser to clear the platform (margin) of the implant abutment to help attain full seating of the implant restoration. It is important to mention again, that diode lasers are safe to use around implant components – electrosurgery is not.
Aesthetic gingivectomies (Figs. 8 & 9) can be easily and predictably performed to balance gingival zenith profiles using a diode laser as long as the clinician has a thorough understanding of biologic width and tissue biotypes. Based on the original work by Wentz, Orban, and Gargiulo in 1961 3, the average minimum sulcular depth in 1 mm. Spear, Kois 4, and others use this as part of their “magic numbers” whereas the measurement from the free gingival margin to the crest of bone should be 3 mm on the facial aspect of a crown preparation. So, if a patient measures a 3 mm sulcus, based on the literature, 2 mm can be excised without a need to reposition the bony crest (Figs. 10–12). Diode lasers afford the clinician a very controlled way to artistically perform these procedures and maintain physiologic contour of the marginal gingiva without fear of gingival recession due to tissue necrosis.
A diode laser is being used to perform aesthetic soft tissue recontouring to equalize the gingival heights of two maxillary central incisors prior to placing porcelain veneer restorations. It is important to note that a 1 mm sulcular depth must remain after the gingivectomy procedure is performed to maintain proper biologic width.
A postoperative view of the porcelain veneer restorations on the maxillary central incisor preparations shown in Figure 8. Note the quality of the marginal gingival health in the surgical area of tooth # 21 at only two weeks after the gingivectomy procedure performed with the super pulsed diode laser.
An gingivectomy procedure above tooth # 24 is performed to help create ferrule effect on this preparation prior to fabrication of the definitive restoration.
After performing the gingivectomy procedure, the distance from the corrected gingival margin to the crest of the alveolar bone is measured with a periodontal probe. This distance must not be less than 3 mm, or bony crown lengthening would need to be performed to reestablish biologic width prior to completing the restoration.
An occlusal view of tooth # 24 after retraction cords are placed prior to making the master impression.
Another clinical challenge is managing the soft tissue around implant components. To help crate natural root shaped emergence profiles for implant components and restorations, and if enough soft tissue is present, a diode laser can be safely used around the components to create natural root diameters that can be “molded” using the provisional restoration prior to the placement of the definitive restorations. This procedure also results in the “simulation of papillae” often times eliminating unsightly “black triangles” that are often seen in the interproximal areas between natural teeth and implant restorations. When implant crowns are cemented or placed with screw retention, a diode laser is useful prior to placement, to remove any residual soft tissue that may cover the platform and margin of the implant abutment to ensure complete seating of the restoration (Figs. 13–16).
A super pulsed diode laser (Gemini: Ultradent Products) is shown being used around an implant healing abutment prior to removal and placement of an impression coping. Creation of an “ovate site” around the healing abutment will help to simulate gingival papillae between the implant restoration and the adjacent natural teeth.
An occlusal view of the tissue sculpting done around the custom abutment on the implant in the #12 position. Using a provisional restoration will now help to create natural tissue contours around the implant abutment which will improve the aesthetics of the definitive restoration.
The provisional restoration has been removed to show how the gingival tissues have matured around the implant custom abutment simulating natural emergence profile.
The definitive ceramic restorations after cementation. Note the gingival profiles, it is hard to pick which central incisor is an implant and which one is the natural tooth.
One way to improve upon aesthetics for fixed bridge pontics is to use an ovate pontic design. The tissue (gingival) portion of the ovate pontic is shaped like the large end of an egg and is submerged 2 to 3 mm into the gingival tissues after extraction of a tooth or preparation of the tissue site with a diode laser. The result is an aesthetic pontic that appears to erupt out of the gingival tissue with papillary form interproximally between the adjacent abutment teeth. In both types of clinical cases, the gingival tissues will heal and mature around the provisional ovate pontic, which acts as a “scaffold” creating a “healed” site with papillary and marginal gingiva form. When creating an ovate pontic with a diode laser in an edentulous site, there must be a minimum depth of 3 mm of soft tissue, which is determined by sounding to the crestal bone with a periodontal probe after application of local anesthesia. If this thickness of tissue does not exist, soft tissue grafting can be done to create the necessary environment prior to restoring the area. After four to six weeks of healing, master impressions for the definitive restoration can be taken (Figs. 17 & 18).
The diode laser is used to sculpt the soft tissue around the implant healing abutment in the # 21 position and an ovate pontic site has been created in the #22 site.
The definitive ceramic restorations are shown for the case in Figure 17 from the facial aspect.
Management of the gingival tissues, or lack thereof, during routine dental restorative procedures can have a profound effect on the clinical outcome of the procedure. With modern restorative materials that require absolute control of gingival position and the ability to eliminate hemorrhage in the operative area, a diode laser is an essential tool to simplify the procedure and accomplish these goals. Super pulsed technology is the next step in diode laser technology to create more accurate, less traumatic interactions with the gingival tissues that will result in more predictable and
comfortable procedures for patients. Thermal damage (necrosis) of the adjacent gingival tissues can be reduced to a minimum, the healing time is faster, and the cut more precise. For the applications in restorative dentistry discussed above, this represents a “quantum leap” in dental laser technology and soft tissue management. OH
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About the Author
Dr. Robert A. Lowe has received a fellowship in AGD, ICD, ADI, ACD, IADFE, and ASDA. He is a diplomate on the American Board of Esthetic Dentistry and maintains a private practice in Charlotte, North Carolina. Dr. Lowe can be reached at firstname.lastname@example.org.