CO₂ lasers in orthodontics

Dr. Sabrina Dragan discusses an innovative tool with multiple benefits for the orthodontist and the multidisciplinary practice

Modern technology has perfected the instrument that has become almost synonymous with minimally invasive dentistry — the dental laser. While lasers have been utilized in dentistry for over 40 years, their use has been limited in orthodontics. Within the orthodontic practice, there are numerous instances where the orthodontist calls upon the periodontist, the pediatric dentist, or the oral surgeon to solve mucogingival problems that interfere with ongoing therapy or that complicate the therapy itself. Using a laser, the orthodontist can intervene quickly and easily with a minimally invasive treatment for oral and mucogingival surgery.

Knowledge of a laser device’s capabilities is essential for patient care and for making a satisfactory return on investment by the provider. Lasers have emerged as vital tools, revolutionizing the way oral health is managed and treatments are delivered. These precise and versatile devices offer numerous advantages, including faster operating time, reduced pain, minimized intra- and postoperative discomfort, faster healing, and improved quality of results, all of which contribute to a faster completion of the orthodontic therapy.¹ In addition to their benefits in soft-tissue procedures, lasers are instrumental in cavity prevention and cavity preparation.^2,3 Their analgesic effects often eliminate the need for local anesthesia, making dental visits more comfortable for patients. This narrative review serves to introduce the benefits and principles of lasers to orthodontic therapy, a field where it has yet been fully applied.

Many clinical scenarios may benefit from lasers, either by their analgesic or biostimulating effects before and after orthodontic therapy, including:

• Closure of a midline diastema between upper central incisors in the presence of an abnormal or hyperplastic frenum
• Problems related to ankyloglossia with a short lingual frenum and low positioning of the tongue
• Soft-tissue or bony-impacted ectopic teeth that are unerupted or partially erupted
• Gingivectomy during treatment to improve hygiene by debulking hyperplastic tissue or post-ortho to improve esthetics
• Orthodontic debonding of ceramic brackets

A primer on laser technology

Light Amplification by Stimulated Emission of Radiation, or laser, is a term involving the physics of light that is amplified by stimulated emission.^4,5 A laser consists of three components: the laser medium, the pump source, and the optical cavity or optical resonator.⁵ Because the medium is the active element, the medium determines the wavelength of the laser. A laser device’s wavelength is important to its applications in hard tissue versus soft tissue applications and the chromophores (i.e., water, plastic, collagen, hydroxyapatite, etc.) that it seeks. The optical cavity is a compartment of mirrors that contain the medium and the optical resonator. It amplifies the light energy released as it is reflected by the mirrors where it may then be amplified by stimulated emission before exiting onto the target tissue.⁶

A dental laser would be a logical technology pillar to integrate into a forward-thinking practice.

The laser light is monochromatic, meaning that it is one color and one wavelength. Laser light waves all travel in the same direction and without diffusion (collimation). This is important to understand because since the laser beam travels as a single line without diffusion, the operator is able to reach distant areas in the mouth that would otherwise be difficult to reach.⁵

Mechanism of laser action

The light energy that is produced by a laser can have four different interactions with target tissue: reflection, transmission, scattering, and absorption.⁵ When a laser is absorbed, it elevates the temperature and produces photochemical effects, depending on the water content of the tissues. When the water temperature surpasses 100 degrees Celsius, vaporization of the water within the tissue occurs — a process called ablation. Absorption requires targets to absorb light at specific wavelengths. These targets are called chromophores. The primary chromophores in dentistry are water, melanin, hemoglobin, and hydroxyapatite (Figure 2).⁷ Because chromophores have different laser wavelength coefficients, ease of use and procedural success is dependent upon laser wavelength.

Types of lasers in dentistry

Lasers in dental practice today can be classified by the lasing medium being used (such as a gas or solid laser), the tissue applicability (all-tissue versus soft tissue), or by their wavelength range.⁵

Carbon Dioxide Laser

The CO₂ laser has a high affinity for water and hydroxyapatite, and therefore, results in rapid soft tissue removal and best hemostasis with a very shallow depth of penetration. It has the highest absorbance of any laser. CO₂ lasers can be further divided into soft tissue versus all-tissue lasers. The Solea^® All-Tissue Dental Laser from Convergent Dental is a CO₂ laser with a novel 9.3 µm wavelength that is highly absorbed into the tooth structure, vaporizing enamel rather than slowly chipping it away. This laser can equally treat both soft tissue and hard tissue. Applications that are particularly relevant to orthodontic practice include, but are not limited to cavity preparation, caries, restorative removal/ceramic bracket removal, bony removal for exposures of unerupted teeth, laser etching with bonding, treatment of dentinal hypersensitivity, and prevention of demineralization of enamel and dentin.

Neodynium Yttrium Aluminum Garnet Laser

The Nd:YAG wavelength is absorbed by pigmented tissue making it effective in coagulating soft tissues for hemostasis and for surgical laser cutting. Nd:Yag lasers operate with a 1.064 µm wavelength and were the first types of true pulsed lasers to be marketed exclusively for dental use. These are primarily used for periodontal treatments.

Erbium Laser

Erbium lasers operate with a 2.79 to 2.94 µm wavelength and are both hard- and soft-tissue capable.

Diode Laser

Diode lasers operate with an 0.83-1.064 µm wavelength and work only for soft tissue.

Application of laser technology for common orthodontic procedures

Laser technology creates numerous opportunities for orthodontists and fosters a collaborative approach to care that benefits both dental providers and patients. The following is a review of six common procedures that affect orthodontic therapy, and a discussion of how laser technology can positively influence practice protocols and patient outcomes.

Ectopic eruption of maxillary molars

Ectopic eruption of the permanent first molars occurs due to the molar’s abnormal mesioangular eruption path, resulting in an impaction onto the distal prominence of the primary second molar’s crown. This occurs in roughly 3% of the population and is more common in children with transverse and sagittal crowding and those with cleft-lip and cleft-palate.^8-10 Sixty-six percent of ectopic first permanent molars will self-correct by 7 years old.¹¹ For the one third of cases that do not self-correct, delaying orthodontic intervention may ultimately result in space loss due to early loss of the primary second molar.¹¹ Pediatric dentists are trained to assist in de-impacting a maxillary molar as soon as possible to prevent external root reabsorption of the primary tooth, which can lead to further complications. This treatment is conventionally done with an orthodontic separator, a de-impaction or “Arkansas spring,” a brass ligature wire, or a Halterman appliance.¹¹ With some exception of the Halterman appliance, the other orthodontic methods can only be utilized if there is access to the ectopic permanent molar, sometimes resulting in a delayed intervention. Conversely, a laser-savvy pediatric dentist can utilize this technology to quickly and effortlessly uncover the permanent molar, allowing access to where it is ledged on the primary second molar. This access will allow the placement of a distalizing orthodontic appliance such as a brass wire or de-impaction spring.

Orthodontists should be aware of this treatment option, as general dentists may refer patients to them if this scenario arises in their practice. Orthodontists who utilize laser dentistry have the potential to expand their procedural scope and treatment approach, or they may choose to collaborate with a pediatric dentist colleague who uses laser dentistry in their practice.

This less invasive correction to a common orthodontic issue is a successful alternative to the common extraction order that pediatric dentists often receive from the orthodontist. Families and patients will appreciate this collaborative approach because it saves time due to fewer appointments and it reduces costs.

Uncovering unerupted and partially erupted teeth

An all-tissue laser allows dentists to uncover an impacted or partially erupted tooth (Figure 3) so it can be exposed for bonding. With conservative tissue removal and immediate hemostasis, the CO₂ laser allows an orthodontist to bond a bracket or button on the same day as the tissue removal. A 9.3 µm wavelength laser alters the chemical structure of teeth by increasing the ratio of calcium to phosphorus and converting the carbonated hydroxyapatite to the purer hydroxyapatite of enamel and dentin.¹² Not only does the purer hydroxyapatite resist the caries process, but this altered molecular state also possesses enhanced bond strength with resin.¹² Because the laser removes microns of enamel at a time, the precision of the laser traveling from overlying soft tissue and possible cortical bone poses little risk to exposure of the tooth underneath. The nature of a 9.3 µm wavelength laser also has low risk of thermo-damage to the dentin-pulp complex due to the shallow depth of heat absorption.¹²

Maxillary labial and lingual frenectomies

As new and emerging research from Soroush Zaghi, MD, is published regarding the proper technique and correction of prominent maxillary labial frena and mandibular lingual frena, the dental community is realizing the need for a collaborative approach to deliver optimal results for dental practitioners and patients. Collaboration between the release provider, a myofunctional therapist to address tongue tone, and an orthodontist to address tongue space are essential pieces to the airway puzzle.¹³ Research also supports the idea that the most suitable surgical resolution is the use of laser devices because they produce a bloodless field, shorter surgical times, and faster wound healing.¹⁴

Gingivectomy

While conventional gingivectomy is associated with pain and bleeding, orthodontists may benefit from integrating a laser into optimal gingival esthetics at the conclusion of comprehensive orthodontic treatment. The precise pen-like grip of a CO₂ laser device allows the practitioner to complete smile design and gingival contouring with precision and without local anesthetic.

In addition, transient tissue hypertrophy and hyperplasia, such as gingival overgrowth due to poor oral hygiene, overgrown tissue on temporary anchorage devices, or overgrown gingiva over buttons can be excised in the orthodontic office without a referral to a specialist (Figure 5).

Orthodontic debonding

Laser energy provides less force application and less photothermal activity during bracket removal by softening the adhesive resin used to bond brackets.¹⁵ Debonding with lasers is especially useful for ceramic brackets by reducing shear strength without increasing intrapulpal temperature.¹⁵

Airway and sleep disorders

According to Johns Hopkins Medicine, about 45% of adults snore sometimes and 25% snore regularly.¹⁶ Meanwhile, parasomnia can affect up to 50% of children.¹⁶ The Solea laser features an additional handpiece that integrates into the 9.3 µm wavelength CO₂ laser software allowing dentists to target superficial and deep collagen bundles in the soft palate and uvula, thereby shrinking these floppy tissues and decreasing upper airway resistance. Emerging research indicates that this therapeutic approach is promising for adults when collaborating with other care providers in the sleep arena, such as otolaryngology, myofunctional therapists, and allergists.^17-19

The integration of laser technology into dentistry across general and specialized practice areas has, and will continue to, create new business opportunities for practitioners, while transforming the patient experience and influencing the future of oral care.

Because orthodontists are known for embracing technology, they often find themselves at the forefront of new practice protocols. As a result, a modern orthodontic office may feature advanced devices like CBCT, intraoral scanning, and 3D printing. A dental laser would be a logical technology pillar to integrate into a forward-thinking practice. With the right education and training, a laser system enables dentists to increase patient comfort and decrease chair time, thereby increasing profits and productivity. It is also a great marketing vehicle for dental and orthodontic practices alike.