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Diode laser technology in dentistry has advanced greatly over the past 30 years. Yet while the possible applications of this technology in the dental setting are more far-ranging than ever before, many dental professionals often continue to use diode lasers in only a very limited capacity.
The word laser actually originated as an acronym, namely, "LASER," which stands for light amplification by stimulated emission of radiation.1 Diode lasers have been in use for several decades and are widely used in dermatology, medicine, and ophthalmology. However, dental diode lasers were not available to dental professionals until 1990, when the Nd:YAG laser was developed and received approval for use in general dentistry.2 Since that time, laser dentistry has grown to include several different laser types and wavelengths. Diode lasers with wavelengths spanning from 810 to 980 nm are the laser types most commonly used in dentistry, owing to their affinity for hemoglobin and melanin.3,4 Recently, dentists and dental hygienists have begun utilizing low-level laser (light) therapy (LLLT) at wavelengths of 600 to 810 nm for photobiomodulation for pain relief, faster healing, and reduction of edema.
CLINICAL APPLICATIONS OF DENTAL DIODE LASERS
Recurrent Herpes Labialis
In the past, many dental patients were not able to keep their dental appointments because of recurrent herpes labialis (RHL). Today, RHL can be treated with diode laser therapy. More than one-fifth of young adults are affected by RHL,5 which may be transmitted by direct contact with an infected person. RHL remains latent in the neural tissues and becomes active with internal or external stimuli.6 RHL not only causes pain and discomfort but can also impact the work and social activities of affected individuals.7LLLT should be considered as an option for the treatment of RHL, as this therapy has been shown in multiple case studies to decrease the frequency of vesicle recurrence and provide comfort.8 With diode laser therapy, the RHL virus can be neutralized at the nerve ending, often preventing the lesion from coming to the surface.9 This not only helps alleviate the pain and discomfort associated with RHL, but also spares the patient the embarrassment and social impact that can result from having oral lesions.
Dentinal hypersensitivity is a common condition that can make routine dental prophylaxis problematic for many patients. When performing dental prophylaxis, dental hygienists may find that they need to adjust treatment based on the individual patient's level of sensitivity, which may risk lowering the standard of care, and they may also find that they need to use desensitizing agents such as potassium nitrate and calcium silicate to treat the hypersensitivity.10
Diode laser therapy has been found to be effective for tooth desensitization. It has been theorized that the sensitivity associated with dentinal hypersensitivity results when a stimulus that is applied to dentine displaces the fluid inside the dentinal tubule.11 During diode laser therapy, the laser energy enters the dentinal tubules and thickens the fluid within, reducing the movement of fluid and thus causing the pain to be relieved when the nerve endings are stimulated.
The use of lasers to treat dentinal hypersensitivity dates back to the 1980s with the advent of erbium lasers.11Although initial results were disappointing, the improvement of technology and increased scientific knowledge since that time have led to the development of new lasers with wavelengths suitable for the treatment of dentinal hypersensitivity.12 Several studies that evaluated different types of lasers (with different wavelengths and durations of application) have demonstrated the effectiveness of diode laser therapy for dentinal hypersensitivity, both immediately upon completion of therapy as well as approximately 6 months after the first treatment.13-15 In these studies, laser therapy resulted in reduction in and, in many cases, eradication of pain.13-15 Proper training in the use of diode lasers allows dental professionals to treat dentinal hypersensitivity and perform dental prophylaxis with a higher standard of care and without the need for additional desensitizing agents.
Bacterial Reduction and Prophylaxis
Dental professionals can use diode laser therapy to decontaminate the gum tissue as an adjunct treatment to prophylaxis procedures. Diode laser therapy has been found to significantly reduce Actinobacillus actinomycetemcomitans from a healthy sulcus.16 In addition, in a study evaluating the application of a 810-nm diode laser to reduce bacteria in the sulcus, when proper motion was used, considerable bacterial reduction was demonstrated, as was elimination of periodontal-specific bacteria, especially Prevotella sp, Streptococcus beta-hemolitico, Fusobacterium sp, and Pseudomonas sp.17
A study completed in 1996 showed an increase of approximately 50% collagen synthesis in the periodontium with the use of laser therapy.18 By stimulating healing and collagen, a low-intensity diode laser stimulates the gingival tissue to tighten around the tooth, creating healthy gingiva.19 Diode laser therapy thus helps provide a higher level of care by addressing the biofilm on the tooth structure and in the gingival crevicular fluid.
Gingivitis and Periodontal Diseases
Over the past few years, the worldwide prevalence of periodontal disease has increased from 80% to greater than 90%.20 In 2017, dental professionals were given a new classification system to help better understand the status of periodontal disease. The American Association of Periodontology in collaboration with the European Federation of Periodontology developed three new subdivided categories:
• Necrotizing periodontal disease
• Periodontitis as a manifestation of systemic diseases20
Patients with periodontitis have a 24% greater risk of coronary artery disease than individuals without periodontitis, after adjusting for confounding factors.21 Several epidemiologic studies and more than three meta-analyses show a moderate positive association between periodontal disease and atherosclerotic vascular disease.22The American Heart Association ranks atherosclerotic vascular disease as one of the leading causes of death and disability in the United States.22
By incorporating diode laser therapy into periodontal protocols, dental healthcare professionals may effectively treat their patients with periodontitis. Because periodontal disease is a chronic inflammatory disease caused by bacterial infection, the bactericidal and detoxifying effects of diode laser therapy are highly advantageous in the treatment of periodontitis.23 With conventional treatment of periodontal disease, it is not possible to completely remove bacterial deposits and endotoxins from deep areas within the periodontal pockets.24 Although the use of antimicrobials or antibiotics with conventional treatment can help reduce bacterial colonization after periodontal therapy, it may also potentially be offset to varying degrees by the risk of increased resistance of the infective microorganisms.25 In one study, combining periodontal laser therapy with periodontal treatment provided more effective decontamination of the periodontal pockets and was associated with a slower recolonization rate compared with traditional scaling and root planing at periodontal sites.26 The curettage effect that occurs with diode laser therapy in the periodontal pocket reduces the bacterial load without causing any damage to the underlying connective tissue.27 Diode laser therapy as an adjunct to conventional periodontal therapy can be used to treat periodontal pathogens not only on the cementum but also within the periodontal pocket wall.
Research shows that using a laser in conjunction with periodontal scaling and root planing accelerates and improves wound healing, decreases gingival bleeding and inflammation, and improves pocket depths.28Several researchers attribute the faster healing rate and reduction in pathogens to the clot formation that occurs in the periodontal pocket, which essentially seals the pocket lining.29 The use of laser periodontal pocket irradiation removes the granulation tissue of the periodontal pocket, thereby promoting the healing of the connective tissue, which in turn leads to reduced probing depths and tooth mobility and improved gingival indices.30
Many dental hygienists are concerned about the possibility of causing thermal damage when using a diode laser as an adjunct to periodontal therapy. However, in a study by Castro et al, the in vivo effects of scaling and root planing associated with 980-nm diode laser irradiation on periodontally diseased root surfaces were evaluated31; the researchers concluded that the laser did not cause any mechanical alteration or thermal damage to the cementum and could be used routinely as an adjunct to scaling and root planing.31 In an in vitro study published in 2020 comparing the effect of diode lasers at different wavelengths with regard to potential thermal damage, necrosis, and lost tissue area in the oral mucosa, the values were higher in the 1470 nm laser group (0.818 µm2 ± 0.961) and minimal in the 810 nm laser group (0.003 µm2 ± 0.010) in all of the variables studied.32
Temporomandibular Joint Dysfunction
Temporomandibular joint dysfunction is a common disorder in which the temporomandibular joint moves out of alignment. LLLT (photobiomodulation) can be used to decrease the discomfort caused by TMD, giving patients much-needed relief.
Photobiomodulation can be used to treat several other conditions, from mucositis to nausea and gagging. Oral mucositis, a painful inflammation and ulceration of the mucous membranes, occurs in 30% of patients who undergo chemotherapyand 100% of patients receiving radiation therapy by the time of their third treatment.33
Photobiomodulation as a noninvasive alternative treatment to acupuncture has also been explored in multiple studies.34 This application aids dental hygienists greatly when exposing radiographs: by applying photobiomodulation to the acupuncture sites on the wrist for nausea and gag reflex, the dental hygienist can expose the needed radiographs while allowing for a more comfortable experience for the patient, as well as a less stressful experience for the hygienist. Preventing the gag reflex also allows for improved opening of the contacts, enabling interproximal decay to be noted earlier.
A dentist or dental hygienist with proper training can use a diode laser with a 600- to 980-nm wavelength to induce wound healing, tissue repair, reduction of inflammation, pain, and edema, improvement of acute injuries, and alleviation of neurogenic pain.35 Because the energy from laser therapy targets only damaged tissue, stimulating natural biological healing, healthy cells are not affected.18 Statistical analysis showed clear differences between the 1470 nm and 810 nm laser groups, demonstrating an increase in thermal damage and necrosis in the periodontal pocket surface with the higher wavelength.32
With proper training in the use of diode lasers, dental professionals can use dental laser therapy to greatly improve their patients' oral healing, comfort, and overall dental health. Diode laser therapy results in more predictable outcomes during periodontal procedures and decreases oral pathogens when used as adjunctive treatment to prophylaxis and other dental procedures. By implementing laser therapy, dental hygienists and other dental professionals can help provide patients with complete and truly comprehensive preventive dental care.
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