Lasers in Dentistry and Pediatric Dentistry

Introduction

• Lasers have garnered significant interest and widespread use in dentistry.

• Benefits of laser systems have attracted practitioners, leading to the displacement of conventional therapies.

• Dentistry now has access to modern tools for enhanced dental care.

• Laser technology can be used as a diagnostic tool for caries detection, resin curing, cavity preparation, soft and hard tissue surgery, and dentin hypersensitivity.

• Lasers offer superior results compared to conventional methods, enabling clinicians to perform procedures not possible with routine therapy.

• The article emphasizes the basic science and review of lasers in dentistry, with a focus on applications in pediatric dentistry.

• LASER stands for "Light Amplification with the Aid of Stimulation Emission of Radiation."

• Conventional methods involve local anesthesia, needles, and noisy, vibrating rotational devices and can be tiresome for pediatric dentists due to patient anxiety and uncooperative behavior.

• Evidence-based dentistry and ongoing research in laser technology may advance conventional treatment.

Laser History

• Lasers have been used in medicine and dentistry for a long time and are the result of years of research rooted in quantum mechanics theories from the early 1900s (Niels Bohr).

• Schawlow and Townes discovered LASER in 1958.

• Maiman of the Hughes Research Laboratories built the first operational laser, a pulsed ruby apparatus, in 1960 $[1]$$$[1]$$.

Classification of Lasers

• Classifications for lasers include:

  • Wavelength

  • Method of laser production (gas, solid-state, liquid, or semiconductor diode)

  • Tissues on which it is presently used (supple and challenging tissues)

  • Degree of risk to the skin or eyes after unintentional exposure

  • Type of lasing medium (Erbium, yttrium aluminum garnet, etc.) $[2]$$$[2]$$

Types of Lasers and Their Applications Based on Wavelength

• CO2 Laser:

  • Wavelength: $10,600 nm$$$10,600 nm$$

  • Applications:

    • Ablation of soft tissues

    • Contouring of the gingiva for cosmetic reasons

    • Oral ulcerative lesions treatment

    • Gingivectomy and frenectomy

    • Removal of dead epithelial tissue

    • Regenerative periodontal procedures

• Nd-YAG Laser:

  • Wavelength: $1064 nm$$$1064 nm$$

  • Applications:

    • Root canal therapy: cleans debris and infectious bacteria

    • Periodontal surgery and scaling: removes disease-causing germs and necrotic tissues

    • Caries eradication

• Er-YAG Laser:

  • Wavelength: $2940 nm$$$2940 nm$$

  • Applications:

    • Eliminating caries

    • Preparing enamel and dentin for cavities

    • Root canal cleaning

• Er,Cr-YSGG Laser:

  • Wavelength: $2780 nm$$$2780 nm$$

  • Applications:

    • Etching Enamel

    • Eliminating caries

    • Preparing the cavity

    • Ablation of bones without melting, overheating, or altering the calcium or phosphorus ratios

    • Preparation of the root canal

• Argon Laser:

  • Wavelength: $572 nm$$$572 nm$$

  • Applications:

    • Polymerization of materials made of restorative resin

    • Tooth whitening

    • Removal of dead tissue and shaping of the gingiva

    • Therapeutic management of oral lesions (persistent aphthous ulcers or herpetic lesions)

    • Gingivectomy and frenectomy

• Diode Laser:

  • Wavelength: $810 or 980 nm$$$810 or 980 nm$$

  • Applications:

    • Fibroblast proliferation and improved healing of surgical wounds or oral lesions

    • Frenectomy and gingivectomy

    • Gingival contouring correction for aesthetic reasons

• HO-YAG Laser:

  • Wavelength: $2100 nm$$$2100 nm$$

  • Applications:

    • Contouring Gingival elongation

    • Oral lesions treatment

    • Gingivectomy and frenectomy

Wavelengths of Lasers

• Each laser has a distinct wavelength spectrum, resulting in precise absorption properties.

• Most lasers used in dentistry and periodontics have wavelengths within the red and near-infrared spectrum $[3]$$$[3]$$.

Mechanism of Action

• Lasers need a medium, an optical chamber or laser tube, and an externally supported power supply to produce an emitting monochromatic power beam.

• Electrons are stimulated to a higher power orbit when power is applied to the medium.

• Upon returning to their normal orbit, a photon (a mild particle) is released.

• The laser beam is "coherent" because all of the photons have the same wavelength.

• The wavelength of a laser is dependent on the medium (semiconductor, solid, or gas).

• Lasers are named after the energetic component(s) that produce the power beam when stimulated.

• Argon, gas (diode), Nd: YAG, Er: YAG, Er, Cr: YSGG, and CO2 lasers are frequently used in dentistry.

• Wavelengths can be added using continuous, pulsed (gated), and walking pulse waveforms $[4]$$$[4]$$.

Laser Transport Machine

• The transport device can be a quartz fiber-optic, bendy hole waveguide, articulated arm, or hand piece housing, depending on the wavelength.

• A positive power density is produced by the laser beam's diameter, whether or not it comes into contact with the tissue.

• The smaller the beam, the higher the power density.

Laser Tissue Interaction

• There are 4 unique interactions between the laser light and the target tissue:

  • Absorption: Laser energy is absorbed by the targeted tissue. The amount of energy absorbed depends on the tissue's properties (pigmentation, water content), as well as the laser's wavelength and emission mode.

  • Transmission: Rapid transfer of laser energy through tissue without impacting the target tissue. This effect is very reliant on the laser light's wavelength. Erbium family and CO2 are easily absorbed by tissue fluids, while shorter wavelengths like argon, diode, and Nd: YAG are extremely visible to water.

  • Reflection: The beam reflects off the ground without striking the intended tissue. Reflected light is used by caries-detection laser equipment to gauge the degree of healthy enamel structure. If the reflected image is too strong it could be dangerous because the power is being directed at the eyes.

  • Dispersion: Scattering of the laser light reduces the intended strength and may have no beneficial biological effects. The laser beam scatters, causing heat to transfer to the tissue next to the surgical site and causing injury, however, a beam diverted according to specific rules is advantageous for speeding up the cure of composite resin.

Soft Tissue Management

• Treatment for Ankyloglossia:

  • Ankyloglossia is very common in newborns and accounts for breastfeeding issues.

  • Kotlow L. A. (2004) $[5]$$$[5]$$ found that ankyloglossia may be seen in $3.2\%$$$3.2\%$$ of pediatric patients in a study of more than 350 children.

  • He asserts that the odd attachment of the lingual frenum is one of the most frequently misdiagnosed and ignored congenital defects seen in children and developed helpful diagnostic criteria.

• Diagnosis and remedy for maxillary frenum:

  • In severe cases, the maxillary frenum may stretch between the important incisors and into the palate in toddlers, inserting it into the alveolar ridge.

  • This may result in a diastema between the valuable incisors in the front region and may lead the lip to become wedged between them, interfering with oral hygiene practices.

  • A good maxillary frenum may also interfere with the newborn's ability to latch on correctly and cause breastfeeding issues, according to Ballard J, Khour J C et al., (2002) $[6]$$$[6]$$.

  • Kotlow L. A. (2004) $[5]$$$[5]$$ claims that between the ages of eight and 18 months is when a cure is most likely to take place. Er: YAG 30 hz, 50 mj and Er, Cr: YSGG 20 hz, 50 mj, each without water, are the laser settings he suggests for ankyloglossia.

• Exposure of tooth:

  • The enamel will be seen using a variety of laser frequencies, but the best one is an erbium laser.

  • There is no need for local anaesthetic when only delicate tissue needs to be removed.

  • Kotlow LA (2004) $[5]$$$[5]$$ recommended Er: YAG 30 hz, 45 mj and Er, Cr: YSGG 20 hz, 70 mj for laser settings, both in touch and noncontact mode $[5]$$$[5]$$.

• Gingival recon touring and gingivectomies:

  • Guelman et al. (2003) advised doing laser treatment to restructure gingiva in cases of gingival hyperplasia or gingival development caused by utilizing medications like dilatin sodium.

  • Lasers can remove the gingival tissue to make room for a recovery without experiencing bleeding problems.

  • Most of those procedures can be completed without local anaesthetic and with quite minimal postoperative pain $[7]$$$[7]$$.

• Pericoronal flap troubles related to erupting enamel:

  • Children who have newly or already erupted enamel frequently complain of pain, swelling, or infection in the tissue beneath the new or already erupted enamel.

  • Lasers can be used in a noncontact way to vaporize the anxious tissue and reveal the worried enamel's scientific crown.

  • Most of the time, laser therapy can be performed without the need for local anaesthesia. Kotlow L. A. (2004) $[5]$$$[5]$$ advised using an Erbium laser in a noncontact mode without water with settings of 20–30 hz and 45–55 mj $[4]$$$[4]$$.

• Treatment of aphthous ulcers and herpetic lesions:

  • One of the most straightforward and effective methods for treating aphthous ulcers or recurrent aphthous ulcers is laser therapy, which has been supported by Parkins et al (1994) $[8]$$$[8]$$.

• Pulp remedy in number one tooth:

  • In the past, formocresol and other root canal medications were used to treat the pulp of the first and permanent tooth.

  • However, Kotlow LA (2004) studied more than 150 teeth over the course of two years and found that using the Erbium laser has comparable to or better results than using traditional formocresol.

Laser Approaches for Hard Tissue

• Lasers are thought to be a safe procedure since they are effective at removing cavities from enamel's tough tissue. Nd: YAG laser wavelength was recommended by White J. M. et al. (1993) for the removal of superficial pigmented caries.

• The best laser for removing cavities from deep teeth, dentin, and other materials is an Erbium-based laser from its own family $[9]$$$[9]$$.

• In their study, Hadley J et al. (2000) found that the Er, Cr: YSGG laser machine is effective for training of type I, III, and V cavities and resin restorations are preserved utilizing lased enamel surface $[10]$$$[10]$$.

• According to Kotlow L. A. (2004) $[5]$$$[5]$$, laser treatment avoids micro-fractures that appear frequently following standard drilling. In most cases, local anaesthetic is not necessary. He examined the successful removal of caries using erbium laser.

• He came to the conclusion that the most important thing is to put the least amount of effort into achieving a successful outcome. Higher treatment is no longer guaranteed by more energy.

• Removal of amalgam and different restorations:

  • Although Kotlow L. A. (2004) $[5]$$$[5]$$ no longer recommends using a laser machine to remove damaged amalgam restorations, it can still be used to remove secondary cavities that have formed underneath amalgam restorations.

  • If eliminating the current amalgam recovery is required for caries ablation, the laser tip must be pointed at the neighbouring teeth to create a tiny trough.

  • Metal can be removed with hand tools. Lasers can be used to remove bad glass ionomer and composite cements $[5]$$$[5]$$.

• Sealant placement:

  • The dentist can easily, sterilize, and unquestionably see the grooves in the teeth thanks to the laser.

  • After etching, enamel indicates unique types of fashions.

  • Studies conducted with the help of Visuri S. R. et al., (1996), confirmed that the properties of erbium-etched teeth are similar to those of acid-etched teeth $[11, 12]$$$[11, 12]$$.

• Tooth preparation:

  • Kotlow L. A. (2004) praised the erbium laser for eliminating caries and claimed that it does so effectively.

  • Because of the low water content in the fluorosis condition, the ablation process may also proceed slowly. Here, a turbine with an excessive speed can be used.

  • He demonstrated that for optimal cutting efficiency, the laser tip must be perpendicular to the enamel surface.

• Apicoectomies and removal of impacted teeth under the bone will be carried out using an Erbium laser, special laser tips, settings, and water spray, as determined in a study carried out with the aid of Sasaki K et al (2002) $[13]$$$[13]$$.

• A comparison of the retention of pit and fissure sealants applied using traditional acid etching and Er, Cr: YSGG laser etching reveals that Er, Cr: YSGG laser etching has retention and patient acceptance characteristics similar to those of acid etching $[14]$$$[14]$$.

Use of Laser Treatments Is Contraindicated $[15]$$$[15]$$

• In the uterus region in pregnant women, or with prudence in pacemaker patients

• In those who have epilepsy or frequently

• Patients with a history of chest discomfort or an arrhythmia

• Tumorous tissues or benign tumors having a predisposition to become malignant

• On glands, such as the thyroid gland

• Lupus patients or sufferers who used medications safe for light

Miscellaneous Application of Lasers $[16]$$$[16]$$

• The laser has the aforementioned additional dental applications:

  • The effects of the lasers' analgesia

  • Regeneration and restoration of nerves

  • Pain following surgery

  • Sinusitis

  • Proliferation of stem cells:

  • Hypertonia/xerostomia

  • Periodontitis:

  • Sterilization of challenging tissue

  • Interphase healing after bone implants

  • Lasers are effective treatment options for mucositis and ulcers.

Advantages of Lasers $[17, 18, 19]$$$[17, 18, 19]$$

• No need for sutures

• Does not need anesthetic anymore

• Patients experience less bleeding

• Reduced postoperative discomfort

• Patient compliance is improved

• Viral and bacterial infections are reduced since the high-power laser sterilizes the area being worked on.

• Decreased swelling, postoperative trauma, and scarring. The technique significantly reduced haemorrhage and oedema by sealing up the small blood vessels and lymphatics.

• Tissues may regrow and wounds heal more quickly.

• Shorter surgery time.

• Laser may be precisely controlled to remove thin layers of tissues,

• Lymphatic closure minimizes tumor cell dispersion.

Disadvantages of Lasers $[15]$$$[15]$$

• Laser use results in no tactile feeling.

• No single wavelength can effectively treat all tooth diseases.

• Sometimes using it can be difficult.

• The CO2 laser will diminish a lot of tissues, including the assistant's finger, since it is absorbed with the help of water molecules.

• The price of the gadget.

• The inability to remove defective metal and solid porcelain restorations.

Regulations of lasers

• The use of a dental laser is governed by numerous safety regulations. The most important ones are:

  • The presence of a selected security guard.

  • A location with minimal reflected surfaces and restricted access.

  • The surgical team, the patient, and any observers must wear safety goggles.

  • Compliance with contamination control

Dangers of Lasers

• The various dangers that may arise during clinical dental management can be divided into the following categories:

  • Ocular Injury: Potential injury to the eyes may result from either direct laser emission or the mirrored image of a specular (mirror-like) floor.

  • Tissue damage: The heat interaction of radiant energy with tissue proteins can result in laser-induced damage to skin and other non-target tissue.

  • Environmental risks: Another type of risk is the potential for inhaling airborne biologically dangerous compounds that laser surgery may release.

  • Combustion dangers: In the presence of flammable materials, lasers may furthermore provide a number of substantial concerns. If exposed to a laser beam, flammable liquids, solids, and gases utilized in surgical settings may easily catch fire.

  • Electrical Risks: Elegance IV lasers frequently employ very high currents and high voltage energy sources, both of which have the potential to be fatal.

Laser Hazard Control Measures

• In the context of dental lasers, management measures have been divided into four categories:

  • Engineering controls, first Protective housing, Interlocks Beam enclosures, shutters, provider panels, and warning systems for devices are required for this.

  • Personnel safety equipment Eye Protection Everyone exposed to a minimal risk should wear adequate eye protection, such as safety goggles or screening devices. Control of airborne contaminants can be accomplished using either a recirculating air filtering equipment or the proper air flow evacuation.

  • Procedures and administrative controls:

    • A laser protection officer is a person who oversees all administrative tasks related to ensuring the safe functioning of lasers.

    • The responsibilities of ISO include:

      • In-room evaluation and identification of hazards.

      • Determining if a sector is capable of posing a threat or not.

      • Developing well-liked working techniques.

      • Ensuring that all staff have the proper laser protection.

      • Implementing programs for accident files and clinical surveillance.

• Environmental measures: These include the physical environment where the laser is being used.

Discussion

• Pediatric dentists deal with several clinical circumstances on a daily basis, and laser therapy is a very effective mode of treatment. Kotlow L. A (2004) claims that modern laser technology has made treating children with laser therapy more effective than using more conventional methods $[5]$$$[5]$$.

Conclusion

• There are specific wavelengths of lasers available for specific types of packaging.

• Lasers are now being used in practically all dental specialties.

• With more laser companies entering the field and offering the profession more options of smaller, less expensive devices, it's sure to gain popularity over conventional approaches in the years to come and makes the baby's visit to the dentist simpler, much less stressful, and make your baby's visit a whole lot greater great and enjoyable!

Lasers in Paediatric Dentistry, a Boon or a Bane: A Systemic Review

• The American Academy of Pediatric dentistry (AAPD) recognised the judicious use of lasers as a beneficial instrument in providing dental restorative and soft tissue procedures for infants, children, and adolescence including those with special health care needs, through the development of this policy by the Council on Clinical Affairs in 2013.

• Lasers have been used in dental operators since 1987 and since then laser technology has advanced significantly.

• Lasers in paediatric dentistry is a boon since it causes less pain, has an analgesic effect on hard tissue, is vibration less, thus making the child patient comfortable and anxiety less.

• LASER stands for Light Amplification by Stimulated Emission of Radiation.

Classification of Lasers

• Based on active material: Gas lasers, Solid lasers, Liquid lasers $[3]$$$[3]$$

• Based on wavelength: Invisible ionizing radiation, Visible, Invisible thermal radiation $[4]$$$[4]$$

• Based on their operating mode: Continuous, Pulsed $[5]$$$[5]$$

• Based on their power supply: Low power lasers, Mid power lasers

• Based on delivery system: Flexible hollow waveguide or tubes, Articulated arms, Fiber optic

• Based on clinical use: For diagnosis, for non-surgical treatment, For surgical treatment, Soft tissue, Hard tissue, Combined

Benefits of Lasers in Paediatric Dentistry

• Lasers have selective and precise interaction with diseased tissues $[3]$$$[3]$$.

• There is less necrosis in adjacent tissues with lasers as opposed to electrosurgery $[4]$$$[4]$$.

• Hemostasis can be achieved without the need of sutures in most cases $[5]$$$[5]$$.

• Post wound healing is faster with less discomfort, hence there is reduced need for analgesics $[6]$$$[6]$$.

• Less or no anesthesia is required for surgical procedures in soft tissues when lasers are used $[7]$$$[7]$$.

• Reduced operator chair time $[5]$$$[5]$$.

• Post-operative prescription of antibiotics is less because lasers have decontaminating and bactericidal properties $[5]$$$[5]$$.

• Pain from apthous and herpetic ulcers can be relieved by lasers without pharmacological interventions $[8]$$$[8]$$.

• Caries can be removed effectively by lasers with minimal involvement of surrounding tooth structures because caries affected tissues has higher water content than healthy tissues $[4]$$$[4]$$.

• There is no noise and vibrations with the use of lasers $[9]$$$[9]$$.

• The non-contact of lasers with hard tissue eliminates the vibration of a conventional high speed hand piece making tooth preparation to be comfortable and anxiety free for children $[9]$$$[9]$$.

• Erbium and Nd: YAG lasers seems to have an analgesic effect on hard tissue thus eliminating the need for local anesthesia $[10]$$$[10]$$.

Disadvantages of Lasers in Paediatric Dentistry

• The dentist might need more than one lasers since different wavelengths are required for various soft and hard tissue procedures.

• Lasers are expensive $[6]$$$[6]$$.

• Most instruments are both sight cutting and end cutting.

• Lasers required high level of education and training.

• Lasers may require modification of clinical techniques along with additional preparation with high speed hand piece to finish tooth preparation $[3]$$$[3]$$.

Laser Basics

• Lasers are classified according to the active medium that is used to create the laser energy.

• An active medium is stimulated within a laser to produce photon of energy that is delivered in a beam of unique wavelength that is measured in nano meter $[1]$$$[1]$$.

• The determining factor of the level to which the laser energy penetrates the intended tissue depends on the wavelength of the laser.

• The presence of chromophore or the laser absorbing element determines the intended target tissue’s affinity for a specific wavelength of laser energy $[11]$$$[11]$$.

• Oral hard and soft tissues have a distinct affinity for absorbing laser energy of a specific wavelength and this is why a dentist has to select a specific laser depending on the target tissue that he wants to treat $[12]$$$[12]$$.

• Photothermal is the primary effect of lasers within the targeted tissue and when the temperature of the targeted tissue containing water is raised above 100 degrees the vaporization of the water occurs resulting in soft tissue ablation.

• On the other hand hard tissue which are composed of hydroxyapatite crystals and minerals are not ablated at this temperature, but the water component is vaporized and the resulting steam expands and disperses the encompassing material into small particles $[13]$$$[13]$$.

Application of Lasers in Paediatric Dentistry

• These can be divided into soft tissue and hard tissue procedures.

  • Soft tissue applications

  • Paediatric endodontics

  • Treatment of mucocele

  • Dentigerous cyst

  • Frenectomy

  • Ankyloglossia

  • Herpes labialis lesions

  • Apthous ulcers

  • Exposure of teeth to help in the eruption of teeth

  • Gingival remodeling and gingivectomy

  • Leukoplakia

Hard Tissue Applications

• Caries detection by lasers

• Caries removal

• Prevention of enamel and dental caries

• Cavity preparation

• Pit and fissure sealants

• Curing of light activated composites

• Laser paediatric crowns

• Laser fusion of vertical root fracture

• Removal of old restorative materials

• Orthodontic tooth movement

• Dental traumatology

• Laser analgesia

• Bleaching of vital and non-vital teeth

Soft Tissue Applications

• Diagnosis: Diagnosis of vital and non-vital dental pulp can be done by laser doppler flowmetry.

• Indirect pulp capping: analgesia is not required with lasers due to less heat generation in the pulp chamber.

• Direct pulp capping: When laser is used for DPC the bleeding can be controlled and sterilization is induced. Erbium lasers at 1W, 20Hz with 20% air and 15% water is generally used.

• Pulpotomy: Pulpotomy is one of the most successful treatment in pediatric dentistry with the use of laser.

• Access cavity and canal preparation: Generally Er, Cr: YSGG lasers are used for access cavity preparation and root enlargement and pulsed Nd:YAG laser with 2W at 20pps for 1 second is recommended to sterilize the infected root canals. Lasers are contraindicated in case of curved and narrow root canals.

• Other applications of soft tissue lasers in pediatric dentistry

  • Treatment of mucocele: Using 300 micro meter diameter tip at 1.3W

  • Dentigerous cyst: Lasers can be used to vaporize bony cavity

  • Frenectomy: Er:YAG lasers can be used at a setting of 30Hz and 50mJ

  • Ankyloglossia: Er: YAG at a setting of 30Hz, 50mJ with no water can be used to cut the frenum.

  • Herpes labialis lesions: Nd:YAG laser can be used

  • Apthous ulcers: These lesions can be treated by laser energy in a focused mode

  • Exposure of tooth to help in tooth eruption: Er: YAG at a setting of 30Hz, 45mJ in contact and non-contact mode is generally used $[21]$$$[21]$$.

  • Gingival remodeling and gingivectomy: Erbium laser at a setting of 55-80mJ and frequency of 20-30Hz without water spray is generally used $[22]$$$[22]$$.

  • Leukoplakia: Ablative Er: YAG laser with non-contact digitally controlled hand piece is used $[23]$$$[23]$$.

Hard Tissue Applications

• Caries detection by lasers: Laser fluorescence is used to measure the fluorescence of the tooth that is induced after light irradiation to discriminate between carious and sound enamel.

  • Laser fluorescence is used for caries detection on occlusal surfaces.

• Caries removal: The first to used Er: YAG lasers to remove dental caries were Hibst and Keller in 1980.
  Laser removal of dental caries falls into the category of minimal invasive dentistry. The affected layer is sterilized while retaining its re mineralizing potential.

• Prevention of Enamel and Dental Caries: When Enamel is treated with lasers: Increased acid resistance, Organic blocking theory, Reduced enamel permeability and enamel solubility, lasers can alter the chemical composition and morphology.

• Cavity preparation: Ablation is the mechanism through which lasers are used for cavity preparation.

Advantages of Laser Cavity Preparation

• The cavity that is prepared by laser is irregular in shape and is ideal for placement of composite and GIC.

• Structure and strength of the tooth is maintained.

• The step of acid etching during composite restoration can be avoided.

• Pit and fissure sealants, curing of light activated composites, orthodontic tooth movement and dental traumatology.

• Laser paediatric crowns: The technique of laser paediatric crown was first postulated by Jacboson in 2003
  Tooth preparation eliminates the need of local anaesthesia.

• Removal of Old Restorative Materials

  • Removal of Amalgam filling are contraindicated with lasers because laser ablation causes release of mercury vapour.

Laser Safety

• A mixture of gas and debris which is known as the laser plume is produced during the use of lasers which is why the dentist and the auxiliaries should adhere to infection control protocol and use high speed suction as the dental plume may contain infective tissue particles.

• Palliative pharmacological therapies should be used on patients with viral lesions $[15]$$$[15]$$.

• Laser beams which are scattered and reflected are hazardous to unprotected skin and eyes and that is why wavelength specific protective eyewear should be used by the dental team as well as the patient $[3]$$$[3]$$.

Hazards of Lasers

• Ocular hazard

• Tissue damage

• Respiratory hazard

• Fire and explosion

• Electrical shock

• Combustion hazard

• Equipment hazard

Conclusion

• Lasers have been used in dental operators since 1987 and since then laser technology has advanced significantly.

• Lasers in paediatric dentistry is a boon since it causes less pain, has an analgesic effect on hard tissue, is vibration less, thus making the child patient comfortable and anxiety less.

Lasers in Dentistry: Comprehensive Review for PG Exams

I. Laser Physics and Principles

1. Light Amplification by Stimulated Emission of Radiation (LASER)

   • Definition and significance in dentistry.

   • Explain the process of light amplification.

2. Basic Laser Components

   • Active medium (gas, solid-state, liquid, semiconductor).

     • Examples: CO2, Nd:YAG, Er:YAG, Diode.

   • Pumping mechanism (optical, electrical).

   • Optical resonator (mirrors).

3. Laser Properties

   • Monochromaticity: Single wavelength emission. Importance for specific tissue interaction.

   • Coherence: Photons are in phase, allowing for focused beam.

   • Collimation: Minimal beam divergence, enabling precise targeting.

4. Laser Wavelengths and Tissue Interaction

   • Absorption, transmission, reflection, and scattering.

   • Role of chromophores (water, hemoglobin, melanin, hydroxyapatite).

   • Wavelength-specific tissue effects:

     • CO2 Laser ($10,600 nm$$$10,600 nm$$): High water absorption, ideal for soft tissue ablation.

     • Nd:YAG Laser ($1064 nm$$$1064 nm$$): Absorption by hemoglobin, good for coagulation and deep penetration.

     • Er:YAG Laser ($2940 nm$$$2940 nm$$): High water and hydroxyapatite absorption, suitable for hard and soft tissue.

     • Diode Laser ($810-980 nm$$$810-980 nm$$): Absorption by melanin and hemoglobin, used for soft tissue surgery and bacterial reduction.

II. Laser Types and Dental Applications

1. CO2 Laser

   • Applications:

     • Soft tissue ablation and excision (gingivectomy, frenectomy).

     • Treatment of oral lesions (leukoplakia, fibroma).

     • Cosmetic gingival contouring.

   • Advantages: Precise cutting, minimal bleeding.

   • Disadvantages: Poor for hard tissue, potential for thermal damage.

2. Nd:YAG Laser

   • Applications:

     • Periodontal therapy (pocket debridement, bacterial reduction).

     • Root canal disinfection.

     • Caries removal (limited use).

   • Advantages: Good coagulation, deep penetration.

   • Disadvantages: Thermal effects, not ideal for precise hard tissue cutting.

3. Er:YAG and Er,Cr:YSGG Lasers

   • Applications:

     • Hard tissue cutting (cavity preparation, enamel etching).

     • Soft tissue ablation.

     • Periodontal treatment.

     • Bone ablation.

   • Advantages: Precise hard and soft tissue cutting, minimal thermal damage.

   • Disadvantages: Can be slower than traditional methods.

4. Diode Laser

   • Applications:

     • Soft tissue surgery (excision, incision).

     • Periodontal treatment (sulcular debridement).

     • Low-level laser therapy (LLLT) for wound healing and pain relief.

     • Tooth whitening.

   • Advantages: Portable, versatile for soft tissue, LLLT.

   • Disadvantages: Not effective for hard tissue, potential for overheating.

5. Argon Laser
   - Applications:
   - Polymerization of restorative resins.
   - Tooth whitening.
   - Removal of dead tissue and shaping of the gingiva
   - Therapeutic management of oral lesions (persistent aphthous ulcers or herpetic lesions)
   - Gingivectomy and frenectomy
   - Advantages: Precise
   - Disadvantages: Not as effective on hard tissue

6. HO-YAG Laser
   - Applications:
   - Contouring Gingival elongation
   - Oral lesions treatment
   - Gingivectomy and frenectomy
   - Advantages: Precise
   - Disadvantages: Not as effective on hard tissue

III. Laser-Tissue Interaction in Detail

1. Absorption

   • Laser energy is absorbed by the targeted tissue.

   • The amount of energy absorbed depends on:

     • Tissue's properties (pigmentation, water content)

     • Laser's wavelength and emission mode.

2. Transmission

   • Rapid transfer of laser energy through tissue without impacting the target tissue.

   • This effect is very reliant on the laser light's wavelength.

   • Erbium family and CO2 are easily absorbed by tissue fluids

   • Shorter wavelengths like argon, diode, and Nd: YAG are extremely visible to water.

3. Reflection

   • The beam reflects off the ground without striking the intended tissue.

   • Reflected light is used by caries-detection laser equipment to gauge the degree of healthy enamel structure.

   • If the reflected image is too strong it could be dangerous because the power is being directed at the eyes.

4. Dispersion

   • Scattering of the laser light reduces the intended strength and may have no beneficial biological effects.

   • The laser beam scatters, causing heat to transfer to the tissue next to the surgical site and causing injury

   • A beam diverted according to specific rules is advantageous for speeding up the cure of composite resin.

IV. Clinical Applications in Specific Dental Disciplines

1. Periodontics

   • Laser-assisted periodontal therapy (LAPT): Pocket debridement, bacterial reduction, and biostimulation.

   • Specific lasers: Nd:YAG, Diode, Er:YAG.

   • Advantages: Reduced bleeding, improved patient comfort, enhanced healing.

2. Endodontics

   • Root canal disinfection: Removal of bacteria and debris from root canals.

   • Specific lasers: Nd:YAG, Er:YAG.

   • Advantages: Improved disinfection, enhanced treatment outcomes.

3. Oral and Maxillofacial Surgery

   • Soft tissue excisions: Removal of lesions, frenectomies, and biopsies.

   • Specific lasers: CO2, Diode.

   • Advantages: Precise cutting, minimal bleeding, reduced scarring.

4. Restorative Dentistry

   • Cavity preparation: Precise removal of caries and preparation of tooth surfaces.

   • Enamel etching: Creating micro-retentions for bonding.

   • Specific lasers: Er:YAG, Er,Cr:YSGG.

   • Advantages: Minimally invasive, reduced micro-fractures, improved bonding.

5. Pediatric Dentistry

   • Frenectomies, operculectomies, pulpotomies.

   • Benefits of Lasers Over Traditional Methods:

     • Lasers in pediatric dentistry is a boon since it causes less pain, has an analgesic effect on hard tissue, is vibration less, thus making the child patient comfortable and anxiety less.

   • Lasers have selective and precise interaction with diseased tissues

   • There is less necrosis in adjacent tissues with lasers as opposed to electrosurgery

   • Hemostasis can be achieved without the need of sutures in most cases.

V. Laser Safety and Regulations

1. Laser Safety Officer (LSO)

   • Responsibilities:

     • Hazard evaluation and control.

     • Ensuring proper laser protection.

     • Accident and clinical surveillance.

2. Engineering Controls

   • Protective housings: Enclosing the laser system.

   • Interlocks: Shutting down the laser when the housing is opened.

   • Beam enclosures: Containing the laser beam.

   • Warning systems: Indicating laser activation.

3. Personnel Safety Equipment

   • Eye protection: Wavelength-specific safety goggles.

   • Airborne contaminant control: Smoke evacuators and high-speed suction.

4. Procedural and Administrative Controls

   • Standard operating procedures (SOPs).

   • Restricted access to laser operating areas.

   • Training and certification for laser operators.

VI. Advantages and Disadvantages of Laser Use

1. Advantages

   • Precision and control.

   • Minimally invasive.

   • Reduced bleeding and swelling.

   • Improved patient comfort.

   • Enhanced healing.

   • Reduced need for anesthesia.

   • Bacterial reduction.

2. Disadvantages

   • High initial cost.

   • Requirement for specialized training.

   • Lack of tactile feedback.

   • Potential for tissue damage if used improperly.

   • No single wavelength can effectively treat all tooth diseases.

VII. Contraindications for Laser Use

1. Absolute Contraindications

   • Direct use in the eye.

   • Use on patients with uncontrolled medical conditions.

2. Relative Contraindications

   • Pregnancy (use with caution).

   • Patients with pacemakers (use with caution, consult cardiologist).

   • Epilepsy.

   • Tumorous tissues.

   • Unprotected skin

VIII. Lasers in Paediatric

Lasers in Dentistry: Comprehensive Review for PG Exams

I. Laser Physics and Principles

1. Light Amplification by Stimulated Emission of Radiation (LASER)

   • Definition: A device that generates an intense, coherent beam of light through stimulated emission.

   • Significance in dentistry: Enables precise cutting, ablation, coagulation, and other therapeutic effects.

   • Process of light amplification:

     • Population inversion: Achieving a higher energy state in the active medium.

     • Spontaneous emission: Photons are emitted randomly.

     • Stimulated emission: Incoming photon triggers the release of another photon with the same phase, direction, and frequency.

     • Chain reaction: Amplification occurs as photons stimulate more emissions.

2. Basic Laser Components

   • Active medium: Substance that emits photons when stimulated.

     • Gas: CO2 (carbon dioxide), Argon, and Helium-Neon mixtures.

     • Solid-state: Nd:YAG (neodymium-doped yttrium aluminum garnet), Er:YAG (erbium-doped YAG), Er,Cr:YSGG (erbium, chromium-doped yttrium scandium gallium garnet).

     • Liquid: Dye lasers using organic dyes.

     • Semiconductor: Diode lasers (Gallium Arsenide, Indium Gallium Arsenide).

   • Pumping mechanism: Energy source that excites the active medium to create population inversion.

     • Optical pumping: Using intense light (flash lamps, other lasers).

     • Electrical pumping: Using electrical discharge (radiofrequency, direct current).

   • Optical resonator: System of mirrors that confines and directs the photons to amplify the light.

     • Two mirrors: One fully reflective and one partially reflective.

     • Resonance: Photons bounce back and forth, stimulating more emissions.

3. Laser Properties

   • Monochromaticity: Emission of a single wavelength or a very narrow band of wavelengths.

     • Importance: Allows selective absorption by specific target tissues.

   • Coherence: Photons are in phase, both spatially and temporally.

     • Importance: Enables the formation of a highly focused and concentrated beam.

   • Collimation: Minimal divergence of the laser beam over distance.

     • Importance: Allows precise targeting of tissues with minimal energy loss.

4. Laser Wavelengths and Tissue Interaction

   • Absorption: Laser energy is absorbed by the target tissue, leading to therapeutic effects.

   • Transmission: Laser energy passes through the tissue without significant interaction.

   • Reflection: Laser energy is reflected off the tissue surface.

   • Scattering: Laser energy is dispersed in various directions.

   • Role of chromophores: Molecules within tissues that absorb specific wavelengths of light.

     • Water: Absorbs CO2 and Er:YAG lasers.

     • Hemoglobin: Absorbs Nd:YAG and Diode lasers.

     • Melanin: Absorbs Diode lasers.

     • Hydroxyapatite: Absorbs Er:YAG and Er,Cr:YSGG lasers.

   • Wavelength-specific tissue effects:

     • CO2 Laser ($10,600 nm$$$10,600 nm$$):

       • High water absorption.

       • Ideal for soft tissue ablation, vaporization, and cutting.

       • Limited penetration depth.

     • Nd:YAG Laser ($1064 nm$$$1064 nm$$):

       • Absorption by hemoglobin and pigmented tissues.

       • Good for coagulation, hemostasis, and deep penetration.

       • Used in periodontal therapy and some soft tissue surgeries.

     • Er:YAG Laser ($2940 nm$$$2940 nm$$):

       • High water and hydroxyapatite absorption.

       • Suitable for both hard and soft tissue applications.

       • Precise cutting with minimal thermal damage.

       • Used for cavity preparation, enamel etching, and periodontal treatments.

     • Diode Laser ($810-980 nm$$$810-980 nm$$):

       • Absorption by melanin and hemoglobin.

       • Used for soft tissue surgery, bacterial reduction, and low-level laser therapy (LLLT).

       • Portable and versatile.

II. Laser Types and Dental Applications

1. CO2 Laser

   • Active Medium: Carbon Dioxide gas.

   • Wavelength: $10,600 nm$$$10,600 nm$$

   • Applications:

     • Soft tissue ablation and excision (gingivectomy, frenectomy): Precise removal of soft tissues with minimal bleeding.

     • Treatment of oral lesions (leukoplakia, fibroma): Vaporization or excision of benign lesions.

     • Cosmetic gingival contouring: Reshaping the gingiva for aesthetic purposes.

   • Advantages: Precise cutting, minimal bleeding due to coagulation.

   • Disadvantages: Poor for hard tissue, potential for thermal damage if used improperly.

2. Nd:YAG Laser

   • Active Medium: Neodymium-doped Yttrium Aluminum Garnet crystal.

   • Wavelength: $1064 nm$$$1064 nm$$

   • Applications:

     • Periodontal therapy (pocket debridement, bacterial reduction): Removal of infected tissue and bacteria from periodontal pockets.

     • Root canal disinfection: Elimination of microorganisms from the root canal system.

     • Caries removal (limited use): Not ideal for primary caries removal due to thermal effects.

   • Advantages: Good coagulation, deep penetration, effective for bacterial reduction.

   • Disadvantages: Thermal effects, not ideal for precise hard tissue cutting, risk of charring.

3. Er:YAG and Er,Cr:YSGG Lasers

   • Active Medium: Erbium-doped Yttrium Aluminum Garnet (Er:YAG) or Erbium, Chromium-doped Yttrium Scandium Gallium Garnet (Er,Cr:YSGG) crystal.

   • Wavelength: Er:YAG ($2940 nm$$$2940 nm$$), Er,Cr:YSGG ($2780 nm$$$2780 nm$$)

   • Applications:

     • Hard tissue cutting (cavity preparation, enamel etching): Precise and minimally invasive cavity preparation.

     • Soft tissue ablation: Effective for various soft tissue procedures.

     • Periodontal treatment: Pocket debridement, removal of inflamed tissue.

     • Bone ablation: Osseous recontouring and bone surgery.

   • Advantages: Precise hard and soft tissue cutting, minimal thermal damage, reduced micro-fractures.

   • Disadvantages: Can be slower than traditional methods, requires water cooling.

4. Diode Laser

   • Active Medium: Semiconductor materials (Gallium Arsenide, Indium Gallium Arsenide).

   • Wavelength: $810-980 nm$$$810-980 nm$$

   • Applications:

     • Soft tissue surgery (excision, incision): Frenectomies, gingivectomies, lesion removals.

     • Periodontal treatment (sulcular debridement): Removal of inflamed tissue and bacteria from periodontal pockets.

     • Low-level laser therapy (LLLT) for wound healing and pain relief: Biostimulation to promote tissue regeneration.

     • Tooth whitening: Activation of whitening agents.

   • Advantages: Portable, versatile for soft tissue, LLLT, relatively low cost.

   • Disadvantages: Not effective for hard tissue, potential for overheating, requires careful technique.

5. Argon Laser

   • Applications:

     • Polymerization of restorative resins.

     • Tooth whitening.

     • Removal of dead tissue and shaping of the gingiva

     • Therapeutic management of oral lesions (persistent aphthous ulcers or herpetic lesions)

     • Gingivectomy and frenectomy

   • Advantages: Precise

   • Disadvantages: Not as effective on hard tissue

6. HO-YAG Laser

   • Applications:

     • Contouring Gingival elongation

     • Oral lesions treatment

     • Gingivectomy and frenectomy

   • Advantages: Precise

   • Disadvantages: Not as effective on hard tissue

III. Laser-Tissue Interaction in Detail

1. Absorption

   • Laser energy is absorbed by the targeted tissue.

   • The amount of energy absorbed depends on:

     • Tissue's properties (pigmentation, water content)

     • Laser's wavelength and emission mode.

2. Transmission

   • Rapid transfer of laser energy through tissue without impacting the target tissue.

   • This effect is very reliant on the laser light's wavelength.

   • Erbium family and $CO_2$$$CO_2$$ are easily absorbed by tissue fluids

   • Shorter wavelengths like argon, diode, and Nd: YAG are extremely visible to water.

3. Reflection

   • The beam reflects off the ground without striking the intended tissue.

   • Reflected light is used by caries-detection laser equipment to gauge the degree of healthy enamel structure.

   • If the reflected image is too strong it could be dangerous because the power is being directed at the eyes.

4. Dispersion

   • Scattering of the laser light reduces the intended strength and may have no beneficial biological effects.

   • The laser beam scatters, causing heat to transfer to the tissue next to the surgical site and causing injury

   • A beam diverted according to specific rules is advantageous for speeding up the cure of composite resin.

IV. Clinical Applications in Specific Dental Disciplines

1. Periodontics

   • Laser-assisted periodontal therapy (LAPT): A minimally invasive approach to treating periodontal disease.

     • Pocket debridement: Removal of calculus and infected tissue from periodontal pockets.

     • Bacterial reduction: Eradication of pathogenic bacteria within the pockets.

     • Biostimulation: Promotion of tissue regeneration and wound healing.

   • Specific lasers: Nd:YAG, Diode, Er:YAG.

   • Advantages: Reduced bleeding, improved patient comfort, enhanced healing, reduced pocket depth.

2. Endodontics

   • Root canal disinfection: Adjunctive technique to remove bacteria and debris from root canals.

     • Photoacoustic streaming: Creating acoustic waves to disrupt biofilms.

   • Specific lasers: Nd:YAG, Er:YAG.

   • Advantages: Improved disinfection, enhanced treatment outcomes, potential for better penetration into lateral canals and dentinal tubules.

3. Oral and Maxillofacial Surgery

   • Soft tissue excisions: Precise removal of lesions, frenectomies, and biopsies.

   • Specific lasers: CO2, Diode.

   • Advantages: Precise cutting, minimal bleeding, reduced scarring, decreased postoperative pain.

4. Restorative Dentistry

   • Cavity preparation: Precise and minimally invasive removal of caries and preparation of tooth surfaces.

   • Enamel etching: Creating micro-retentions for bonding.

   • Specific lasers: Er:YAG, Er,Cr:YSGG.

   • Advantages: Minimally invasive, reduced micro-fractures, improved bonding, decreased need for local anesthesia.

5. Pediatric Dentistry
   -Frenectomies, operculectomies, pulpotomies.
   -Benefits of Lasers Over Traditional Methods:
   -Lasers