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Compendium

April 2010, Volume 31, Issue 3
Published by AEGIS Communications


Stepping Onto the Threshold of Laser Technology

Robert A. Lowe, DDS, FAGD, FICD, FADI, FACD

Today, dentists are at a threshold where laser technology is beginning to profoundly impact the day-to-day practice of esthetic and restorative dentistry. In 1960 Theodore H. Maiman inserted a ruby rod into a photographic flash lamp and the laser was born. In 1966 Leon Goldman used a laser clinically on enamel and dentin. The first lasers marketed for use in dentistry appeared in the early 1970s. In the 1970s and 1980s CO2 lasers were used primarily by medical and dental specialists for various soft-tissue procedures. Then, in 1987 the Nd:YAG laser with a wavelength of 1064 nm received marketing clearance from the Food and Drug Administration for treating intraoral soft-tissue procedures and later for intrasulcular debridement (curettage). In 1996 the semiconductor diode laser was introduced to dentistry for soft-tissue applications and has become a popular alternative to conventional scalpels or electrosurgery for different soft-tissue dental procedures. The end of the 1990s saw the erbium-class laser wavelengths (2940-nm Er: YAG and 2780-nm Er, Cr: YSGG), which received clearance for caries removal and cavity preparation (hard-tissue applications), as well as for various soft-tissue procedures. This article will discuss some of the latest uses for lasers in the practice of clinical esthetic/restorative dentistry.

The Use of Lasers in the Esthetic/Restorative Practice

Esthetic and restorative dentistry delivered at its optimal level often encompasses the correction of both hard-tissue (teeth and alveolar bone) and soft-tissue abnormalities. The restoration of the harmonic balance between tooth contour, position, and color is not complete without addressing gingival and bony asymmetries. Using lasers to perform indicated dental procedures often results in the infliction of less surgical trauma, which can mean less postoperative discomfort with more rapid recovery and healing times. Various types of lasers have been used for some time to perform soft-tissue procedures in the dental practice. Almost all surgical lasers can be employed to perform different surgical (soft-tissue) procedures and tissue management with varying efficacy, including 1) esthetic gingival recontouring; 2) sulcular curettage in periodontal pockets; 3) biopsy; 4) gingival troughing to aid in master impression making; and 5) frenectomy. The use of dental lasers have been shown to be an effective aid in treating and managing different periodontal problems, including attachment loss.1

Some laser wavelengths exploit their increased absorption of laser energy in water, enabling convection cooling with water of the adjacent target tissue. This allows lasers to be used on hard tissues—enamel, dentin, and bone, as well as in management of the collateral spread of heat in soft-tissue applications. Lasers can now be used effectively to remove decay and prepare a cavity for restoration with direct restorative materials. Some dental operations that can be performed with an erbium-class laser are: 1) Class I, II, III, IV, and V cavity preparations; 2) dentin desensitization; 3) enamel etching; 4) osseous recontouring during gingival surgery; 5) endodontic therapy (sterilization of the root canal system); and 6) osseoectomy during tooth/root extraction or ridge recontouring.

Gingival Tissue Excisionand Recontouring

When adequate amounts of free gingiva are present, laser contouring (gingivectomy) can predictably increase cervicoincisal heights of clinical crowns to create esthetic symmetry. Provided the biologic width is not violated (2 mm for connective tissue and epithelial attachments and 1 mm for minimal sulcus depth), amounts of free gingiva in excess of the 1-mm minimal sulcus depth can be excised for esthetics. Removal of gingival tissue can be accomplished using almost any dental laser with varying degrees of efficiency.

Another valuable application for laser technology is the removal of excess gingival tissue around healing abutments and fixture platforms of dental implants. Being able to perform this bloodlessly without a scalpel is very convenient for the restorative dentist during the impression and restorative phase of implant reconstruction. The use of diode, CO2, and erbium lasers, unlike electrosurgery, is safe around metallic surfaces, such as titanium or metal restorative materials. Also, when healing abutments loosen, the gingival tissues can migrate into the space between the abutment and implant platform. When this occurs, it is impossible to properly place implant components on the implant platform. This tissue can be safely cleared from the platform of the implant using these lasers so that the restorative components will fit properly.

When replacing failing dental restorations, it is common to find unhealthy marginal gingival tissues, even when the patient’s homecare is adequate. Localized chronic inflammatory tissue can be removed and hemorrhaging can be controlled by using a soft-tissue laser prior to the impression-making process. Laser troughing is a procedure by which a laser is used to create a space between the preparation margin and tissue to aid in the proper registration of master impressions. Removal of redundant soft-tissue on restorative margins that grows under ill-fitted provisional restorations or soft tissue that covers implant abutment preparation margins can be easily and safely performed with most lasers prior to cementation of the definitive restoration.

Cavity Preparation for Operative Dentistry

When restoring teeth in cases of dental decay and/or faulty restorations, the use of erbium lasers allows for efficient preparation of enamel and dentin and, in many cases, without the use of local anesthesia.

Use of Lasers for Osseous Recontouring

The use of erbium lasers for bony recontouring is making a tremendous impact on the way traditional osseous surgery is performed in dental practice. Because the laser cuts only at the end of the tip, control of osseous removal is much greater than with any form of rotary instrumentation. When using diamond burs to perform osseous removal, there is always a chance that the instrument rotation will damage adjacent root surfaces. Also, because the surgical laser wound is less traumatic, there is a lower chance of bony damage due to frictional heat that is eliminated, which is always possible when using rotary instrumentation without proper water cooling. This translates into less postoperative discomfort and quicker healing times.

Surgical Crown Lengthening—Closed Technique

For minor localized biologic width and esthetic corrections, a closed-flap procedure using a laser sometimes can be employed in lieu of an open-flap procedure to make the soft-tissue and bony correction and complete the restorative process without the extended healing time required for open-type surgeries. The osseous crest is sounded using a periodontal probe to determine the distance from the restorative margin. Then, the laser is used to remove bone by holding the tip adjacent to the tooth and “walking” the tip across the affected area with a “sewing machine” (up and down) movement to a 3-mm depth. This technique, referred to as perio-by-the-numbers, has been described by Kois.2 The restorative margin should be 3 mm from the osseous crest on the facial surfaces of anterior and posterior teeth, as well as interproximally of posterior teeth.

Integration of Lasers into Dental Practice

Integration of dental lasers into clinical practice is easier than with many other technologies because they are cutting instruments in many ways similar to conventional handpieces, only less invasive and with more control. One difference is that with some procedures, cutting with a laser is a noncontact phenomenon. Therefore, magnification is important to obtain visual feedback on how efficiently the laser is cutting the target tissue. Training courses are available to learn how to effectively use lasers for various dental procedures. Many clinicians report they are able to perform clinical procedures more efficiently and easily with better predictability while offering other procedures to their existing patients who would have been referred from their office. Lasers and their systems are also being used in dentistry to help diagnose caries, cure composites, and take optical impressions.

Conclusion

Some techniques have been described using various wavelengths of lasers in the esthetic/restorative dental practice. With time, more uses will be discovered for this wonderful adjunctive technology to aid the dentist in creating beautiful and functional smiles for patients in a more comfortable manner.

References

1. Yukna RA, Carr RL, Evans GH. Histologic evaluation of an Nd:YAG laser-assisted new attachment procedure in humans. Int J Periodontics Restorative Dent. 2007;27(6): 577-587.

2. Kois JC. Altering gingival levels: the restorative connection. Part 1: biologic variables. J Esthet Dent. 1994;6(1):3-9.

About the Author

Robert A. Lowe, DDS, FAGD, FICD, FADI, FACD
Diplomate
American Board of Aesthetic Dentistry

Private Practice
Charlotte, North Carolina


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