Diode Lasers in Dentistry: Current and Emerging Applications


Tahira Hyder          MDS Resident




OBJECTIVE: The objective of this review is to describe basic diode laser physics and to delineate the application of diode
lasers in dentistry.
REVIEW: Over the past few decades lasers have become a popular alternative to conventional methods owing to the advantages
they carry such as decreased cellular destruction and tissue swelling, minimal bleeding, enhanced visualization of surgical sites
and reduced requirement for suturing. Among the various lasers in dentistry, diode lasers are currently the most commonly used,
with applications extending from soft tissue procedures to photo-activated disinfection of periodontal pockets, endodontics and
laser-assisted tooth whitening. With its versatility and numerous benefits, small size, ease of operation and, relative and
cost-effectiveness when compared to other lasers, the diode laser is proving itself as a valuable addition to dental setups.
CONCLUSION: The diode laser provides a relatively pain-free minimally invasive technique for removal of soft tissue lesions
such as exophytic lesions and operculum, gingival depigmentation, implant exposure, biostimulation, canal disinfection in
endodontics and teeth whitening.
KEYWORDS: laser dentistry, biostimulation, oral surgery.
HOW TO CITE: Hyder T. Diode lasers in dentistry: Current and emerging applications. J Pak Dent Assoc 2022;31(2):100-105.
DOI: https://doi.org/10.25301/JPDA.312.100
Received: 14 August 2021, Accepted: 26 December 2021

The term LASER is an abbreviation for “Light Amplification by the Stimulated Emission of Radiation”.1 Since its introduction in dentistry in the 1960s by Maiman2 , there has been continuous research on its numerous soft and hard tissue applications. Lasers are broadly classified on basis of tissue adaptability into two types: the first type being hard lasers, such as Neodymium Yttrium Aluminum Garnet (Nd: YAG), Er:YAG and Carbon dioxide (CO2 ), which have both hard tissue and soft tissue applications, but are more costly and can potentially cause thermal injury to tooth pulp3 , while the second type are cold or soft lasers usually semiconductor diode devices, which are compact, affordable and versatile devices used for soft tissue surgical procedures and “biostimulation”.4 A second classification is based upon the physical construction of the laser (such as solid laser and gas laser) and a third one is according to the range of wavelength.

In order to get material on the application of diode lasers in dentistry a, literature search was conducted, using Medline-PUBMED and Google Scholar search based electronic databases. Reviews of literature, clinical trials and case series that used diode laser to evaluate histologic or clinical variables were selected. “Diode laser”, “dentistry”, “oral cavity” and “oral surgery” were employed for the search strategy.

Laser light is a single wavelength, monochromatic light.5 A laser essentially consists of three parts: a source of energy, lasing medium and mirrors that cause resonation. Typically an optical flexible fiber ranging from 200 to 600 µm to deliver the laser light from the laser to the target tissues. The wavelength and other properties of the laser are determined primarily by the composition of an active medium
which produces photons of energy on stimulation, and can be a gas, a crystal, or a solid-state semiconductor.6
When laser energy hits a target issue, four possible interactions occur depending on optical properties of the target tissues and the wavelength of the laser: reflection transmission, scattering, and absorption.7,8 Once the laser light is absorbed in the tissues its temperature elevates, thereby causing photochemical effects which are dependent upon the water content of the tissues. At temperature between
60°C and 100°C protein denaturation occurs; at temperature exceeding 100°C, ablation or vaporization of the water occurs and at temperatures above 200°C, the tissue lose their water content and dehydrate, resulting in burn or carbonization.
For absorption to occur, a chromophore or an absorber of light with affinity for a particular wavelength is required.9 Common chromophores in the soft tissues of the oral cavity include water, melanin and hemoglobin while those of hard tissues are typically water and hydroxyapatite.10,11 Absorption coefficients of lasers differ with respect to hard and soft tissues, thereby making the laser selection proceduredependent.8,12,13 Accordingly, dental lasers are classified as hard or soft tissue lasers, depending on their affinities.

The diode laser has a compact and portable unit with a wide variety of clinical applications. A solid state semiconductor is made up of aluminum, gallium, arsenide, and occasionally indium converts electrical energy into light energy of approximately 810 nm to 980nm wavelength.14 These wavelength are easily absorbed by “chromophores” such as hemoglobin and melanin, while they are poorly absorbed by the hydroxyapatite and water which constitute the enamel, therefore diode lasers have no role in hard tissue application.10
A flexible optic fibre in the form of a headpiece delivers the treatment rays to the target area. The clinical approach and treatment methods dictate the selection between continuous and pulsed modes and between contact and noncontact tissues application.15 Literature suggests some advantages of the laser over conventional methodologies like scalpel, including precise soft tissue incisions, a relatively bloodless surgical field and better visualization, no requirement for suturing, good post-operative recovery period with minimal to none bleeding, swelling and reduced postsurgical pain.16
Dental lasers do carry some disadvantages. The high financial cost makes it not accessible to all dental set ups. Secondly, eye damage is a serious complication that can occur, but is prevented by the use of wavelength-specific eye wear.17 Operations of lasers also require specialized training. Additionally, laser soft tissue incision is slower than that performed with a scalpel.16

Crown-Lengthening Laser-assisted crown-lengthening surgery has a wide variety of clinical applications such as surgical exposure of
fractured tooth or subgingival caries, correction of gummy smile in altered passive eruption cases, and access to root perforations.18 Because of its inability to remove hard tissue, diode laser assisted crown lengthening can only be performed for the treatment of type 1A altered passive eruption19 with a wide band of keratinized tissue and optimal space (approximately 1.5 mm) between the alveolar crest and
cemento-enamel junction.
When compared with conventional crown lengthening using scalpel, laser has been associated with minimal bleeding which allows improved visualization of the surgical field, with reduced post-operative pain and lower visual analogue score (VAS), thereby demonstrating laser-assisted crown lengthening as a safe and effective alternative to conventional methods.19,20

Gingival depigmentation is a periodontal plastic surgical procedure whereby hyper-pigmented zones of the attached gingiva are removed or reduced by various techniques including scalpel surgery, ablation with high-speed handpiece, cryosurgery, electrosurgery, and dental laser.21 Laser assisted gingival depigmentation is typically performed as a single step technique with no requirement of the use of a periodontal dressing, and is accompanied by a fast healing process with minimal pain and discomfort.22

Diode lasers allow precise and easy excision of soft tissue over unerupted or partially erupted teeth such as the maxillary canine for the placement of a bracket or for the removal of an operculum around a partially erupted third molar, with an additional advantage over conventional scalpel surgery in sealing small blood and lymphatic vessels, thereby.23 Postoperative tissue shrinkage is reduced, resulting
in decreased scarring. In most cases the need for suturing is eliminated and healing occurs by secondary intention.24

Denture-induced fibrous hyperplasia is a benign overgrowth of soft tissue that occurs in response to a chronically ill- fitting denture. These overgrowths can be removed without the need of sutures and with good hemostasis and less post-operative pain using diode lasers. Diode laser can also be a useful treatment modality for obtaining biopsy specimens.25

    When the removal of a high labial frenal attachment is indicated, laser-assisted frenectomy provides a relatively painless, bloodless procedure not requiring suturing or a periodontal pack, and without the requirement of any special postoperative care. Diode lasers can also be used to remove the thick frenular band seen in ankyloglossia, in which a band of tissue extends from the bottom of the tongue’s tip
to the floor of the mouth and limits the tongue movements. The attachment of the tongue to the floor of the mouth results in difficulty in speech and deglutition, malocclusion and occasionally difficulty in performing oral hygiene, resulting in periodontal problems, thereby requiring removal of the band of tissue.

Studies have concluded that second-stage implant surgeries performed with diode lasers are not only efficient, safe, bloodless and painless procedures but they also linked with a faster rehabilitation phase and greater patient satisfaction.26,27
In a randomized controlled clinical trial Kholey et. al28 concluded that diode laser assisted implant exposure could be performed without the need for local anaesthesia, however it was similar to scalpel surgery in outcomes including duration of surgery, postoperative pain, healing time, and overall success rates of the implants.

Low-level laser energy from a diode laser is being used as a photo-activator of oxygen releasing dyes (such as tolonium chloride), which cause membrane and DNA damage to the microorganisms upon activation. Commonly referred as photoactivated disinfection (PAD), this technique has been proven in literature to effectively kill bacteria including subgingival plaque in deep periodontal pockets, which are
typically antimicrobial agents-resistant.29 Photoactivated disinfection has been demonstrated to kill Gram positive bacteria (including Methicillin resistant Staphylococcus aureus (MRSA)), Gram negative bacteria, fungi, and viruses.30,31The application of PAD is being extended to disinfection in cases of peri-mucositis and peri implantitis.32,33

Low-level laser therapy (LLLT) is commonly referred to as “bio-stimulation”. Studies indicate that low dose of laser energy (e.g., 2 J/cm2) stimulates proliferation of fibroblasts, while high doses (e.g. 16 J/cm2) suppress it.34,35 An increase in proliferation and locomotion of fibroblasts may result in increased tensile strengths of the healed wounds.36 The effects of LLLT on proliferation and differentiation of human osteoblast cells have been investigated.37 Studies report that LLLT bio-stimulates or enhances the multiplication and differentiation of the human osteoblast-like cells during the first 72 hours after irradiation. This application indicates the use of LLLT in combination
with regenerative methods and even as stand-alone treatment for stimulation of bone repair and acceleration of the healing process.38,39

Low levels laser therapy has been demonstrated to reduce pain and enhance healing of aphthous ulcers and recurrent herpetic lesions.40,41 For recurrent herpes simplex labialis lesions, if photostimulation is performed during the prodromal (tingling) stage, the lesions have been shown to get arrested with acceleration of the healing time and a reduction in recurrences.42

In invitro studies diode laser irradiation has been shown to increase disinfection of deep radicular dentin.43,44 It is also associated with effective sealing of dentinal tubules and elimination of Escherichia coli and Enterococcus Faecalis45, thus increasing the efficacy of root canal treatment. For this effect, the diode laser’s optic fibre is first entered 3 mm short of the apex into the canal and gradually withdrawn, being kept in approximately 1 minute per canal.46

Diode lasers are increasingly being used as part of the laser assisted new attachment procedures (LANAP), whereby the epithelium lining the pocket is removed in an attempt to gain new attachment.47 To perform this procedure, after the completion of scaling and root planing the optical fiber is introduced into the periodontal pocket and ascending and descending movement are performed. Through the duration
of the procedure the optical fiber must be maintained parallel to the tooth root main axis, with the laser being rotated around the perimeter of each involved tooth.48

Laser lights activates hydrogen peroxide within the bleaching agent to yield better results compared to hydrogen peroxide activation using light-emiting-diodes (LEDs). It has been noted that the teeth bleached by the LEDs suffer a major chroma reduction and turn gray; laser irradiation however produced better chroma and less gray.49,50 Additionally, better luminosity and less sensitivity was achieved with laser activation of hydrogen peroxide.51

Over the span of the last four decades, applications of diode lasers have steadily increased across dentistry and extends from soft tissue surgical procedures (frenectomy, gingivectomy, operculectomy etc.) to biostimulation of wounds, teeth whitening gel activation, photodynamic disinfection, and improved root canal disinfection. Owing to its relatively low cost and compatible size, it is growing in popularity in dental clinics and hospitals, making it essential for dentists to know its applications and be proficient in its handling.

None declared


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