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Dr. Ilay Maden

One of the key problems of dentistry is patient compliance. That is mainly because, for patients, dental treatment is historically linked with fear and pain (Fig 1). Although it is in constant improvement, impression of dentistry is not yet where is should stand.

However some technologies like lasers do help; mainly because the fear of the patient is not of the dentist, but of the procedures, and patients have a very positive perception of lasers for medical/dental applications. Lasers are used to correct eye-sight, remove unwanted hair permanently, break kidney stones up; all “nice” solutions for patients. When patients hear about non-contact caries removal instead of drills, no-bleeding cuts instead of stitches and so on, they not only get relieved but even motivated. This provides a chain of positive events; better compliance, better treatment acceptance, easier treatments, satisfied patients, increased practice revenues; satisfied practitioners.

After decades of evolving and building-up of theories and work to make a working device, laser was finally invented in 1960 (Maiman and Maiman 1960) (Fig 2). LASER is an acronym which stands for “light amplification by stimulation emission of radiation” and is a tool to deliver energy in the form of light, to be used to carry out many different applications from industrial use to telecommunication, medicine to dentistry. First use of lasers in dentistry took place in 1964 (Goldman et al. 1964) (Fig 3). At that time laser-tissue interactions were not clearly known to practitioners who were merely experimenting with lasers. Application of inappropriate lasers types and energy levels on dental tissues caused undesirable results, giving lasers a bad reputation. As the interactions between different lasers and different tissues were studied, more informed applications and better results were gained. With newer devices being developed, lasers became more successful and efficient. Today laser is still one of the state of the art, high-tech inventions which is gaining a larger group of users among dental practitioners. Laser Dentistry is an ever evolving way of practicing dentistry. Both the application varieties and evidence base of applications are continuously increasing. Lasers are used both as assistive as well as completely independent evidence-based tools in practically every field of dentistry, especially in terms of a multi-wave concept. Each type of laser has a different wavelength, and each wavelength has a unique interaction with a specific body tissue that is being treated (Franzen, 2010), with the main effects varying from ablation to decontamination and photobiomodulation. The best feature about those applications is that they provide an advantage either for the patient or the practitioner. Certainly the practitioner having an easier time to carry out the procedure, in turn benefits also the patient. To get the best of any laser a dentist may own, it is crucial to understand how lasers work, how the interaction between the laser and tissue takes place and what modifications of laser parameters would affect the outcome. Preferably this knowledge should be gained before purchasing any laser as one should decide on the purchase, depending on this understanding and correlation of it to the scope of practice of the practitioner.

Indications, benefits, advantages and limitations of lasers
With many indications (Table1), main benefits of lasers are providing effective treatments, increased treatment acceptance by the patient and higher level of patient comfort, better wound healing, more treatment possibilities for the practitioner, more patients kept in the practice instead of referring out and better practice marketing. Selectivity, less or no bleeding, simultaneous disinfection as it cuts; lower risk of infection, decreased sensitivity, reduced need for injections, reducing number of total appointments, smear layer removal, minimal invasiveness and less number of tools to work with on different tissues with various effects are some of the advantages. Advantages and benefits will be discussed on the following parts of this series covering practical use of lasers.

Limitations of dental lasers can be cost, steep learning curve, safety, ergonomics and the need to buy two different lasers or one laser system containing two different lasers with different wavelengths in order to be able to perform all laser dentistry indications.

Even though diode lasers’ cost has gone down greatly in the past few years, hard tissue lasers still do have a considerable cost. The dentist should justify the cost by calculating monthly payments and monthly income generated by the laser. The income may be generated directly either by shortening the appointment times and being able to open up slot for more patients, more number of treatments, increasing treatment acceptance due to lasers’ positive perception or increasing the referrals by patients. One may direct the cost of the equipment to the cost of the treatment once the practitioner feels confident and comfortable to do so. It is important to remember the cost of service and peripherals to be included in the calculations for all kind of lasers.

There is a learning curve for sure, however this curve should start before the purchase, making it easier to operate for the practitioner as s/he would know about indications, laser-tissue interactions, parameters and their effects on the tissue and the end result. Just like improving in prosthetics, implantology or in fact any branch of dentistry, getting better in laser dentistry is also a non-stop on-going process.

Safety is a very important aspect of laser dentistry. As a surgical tool, laser are capable of harming biological tissues. Eyes are particularly delicate to light energy. As seen on Table2, different wavelengths have different effects on the eye. The visible and near infrared wavelengths penetrate through the eye constitute of which is mainly water. This causes the absorption to take place at the retina causing serious problems like blindness. Mid and far-infrared wavelengths are absorbed in water, causing them to damage the more superficial cornea if they are directed to the eye. Not only the direct interaction but also reflected and scattered light of class IV lasers, which have powers more than 0.5W, are considered dangerous for human eye, hence the need of protective goggles (Fig 4) for everyone in the operation room and appropriate signs should be put up at the entrance to let others know that the laser might be active inside (Fig 5). Secondary danger is to the skin, however defocused laser is usually safe especially with the presence of gloves or clothing covering the skin. Other hazards are chemical (plume), fire, service (electrical) and physical. Plume should always be extracted with strong aspiration. Flammable materials should be removed from the room. If flow oxygen (more than 21%) is on through an oxygen tank, lasers should not be used. The device should be checked regularly by engineering services to avoid electrical problems and temperature and humidity of the operation room should comply with the users’ manual of the device. Cables and fibres should be placed carefully to avoid tripping and other physical injuries.

Ergonomics is always a glitch to be solved when a new equipment is introduced into the practice but most of the time trying out the best position for the placement and handling of the device leads to the solution.

The reason of the necessity of two different wavelengths lies in the rules of physics. Physics dictate what laser can do for us. That means for more coagulation, deeper disinfection and biomodulation of the tissues we need a near infrared laser whereas to be able to remove hard tissues, we need a wavelength absorbed highly in water making it explode strong enough to be able to break the bonds between hard tissue molecules. If want the whole spectrum of laser dentistry two is the minimum number of different wavelengths we need.

Lasers can’t be used on amalgam fillings and to remove crowns, they can’t 100% eliminate the need for anaesthesia, can’t do finishing of the composite fillings to polish.

Deciding on whether to buy a laser or which laser to buy needs time, research and commitment, or disappointment may follow. First step is to choose which wavelength(s) is more compatible with the procedures you do or want to do. Majority of the practitioners increase their spectrum of treatments they do after owning a laser. It is very important to understand the advantages and limitations of different wavelength and their interactions with different tissues. One thing to realize is that there is no one laser that can do all the effects possible to do with a laser. It is true that some of them have more indications or are safer than others, but this does not mean it has it all. Other than the wavelength, other technological specifications like power, pulse modes choices and minimum and maximum pulse durations are vital for the effectivity of the laser. Energy delivery system is also important especially for erbium lasers as all soft tissue lasers have fibres for delivery. Fibres for erbium lasers are more flexible than articulated arms however they have a limit to how much energy they can carry and are more delicate to damage. If there will more than one dental unit in different rooms at the practice where the laser will be used, portability is important whether it can be carried around with battery like some diode lasers or if needs plugging or even compressor connection for the bigger devices. The more connections it needs the more hassle will be moving it around. Some other points to consider are: consumables costs, user interface, and presence of pre-sets of or programmable parameter settings.

Education is of paramount importance both before purchasing and after purchasing the laser. The prior education is to guide you to an informed decision and latter education should also include training on handling the laser with various treatments. Local regulations should be checked as to learn any preparation needed to operate a laser at the practice.

Following parts of this series of Laser Dentistry will give more information on Erbium lasers, diode lasers and Nd:YAG lasers with their wavelength specific indications, advantages and limitations for the readers to be able to learn about and compare different lasers.

Table 1: Soft and hard tissue applications

Soft Tissue Applications

Periodontal pocket disinfection & deepitelialization

Necrotizing ulcerative gingivitis

Alveolitis
Pericoronitis
Troughing
Aphthous ulcer treatment
Herpes lesion treatment
Haemangioma/vascular lesion treatment
Relief of pain from soft tissue irritations
Incisions and excisions;
Gingivectomy
Gingivoplasty
Crown lengthening – only gingival
Frenectomy
Vestibuloplasty
Implant uncovering
Exposure of unerupted teeth
Exposing subgingival caries
Mucocele
Biopsies
Fibroma/ Granuloma/ Epulis/Hyperplasia/hypertrophy/ pyogenic granuloma etc. removal
Incising abscesses
Operculectomy
Retro-molar/tuber-plasty
Haemostasis
Sleep apnea surgical/ nonsurgical
Depigmentation
De-epithelialization
Pulp capping
Pulpectomy
Granulation tissue removal
Biomodulation;
Anti-inflammatory effect
Vasodilatation
Oedema resolution
Activation of immune system, enzymes and metabolism
Nerve regeneration
Muscular TMJ problems
Chronic pain
Analgesia

Hard tissue Indications

Cavity preparation; Enamel, dentin, composite removal
Inhibition of demineralization
Selective caries removal
Surface modification/conditioning
Root surface detoxification
Calculus removal
Implant surface disinfection & detoxification
Hypersensitivity treatment
Root canal disinfection
Apicoectomy
Osteoplasty
Bone incisions; bone splitting, cyst/tori removal, obtaining block graft
Bone removal, unerupted tooth exposure
Flapless bone removal for crown lengthening
Implant bed preparation
Whitening
Caries/subgingival calculus detection
Analgesia
Orthodontic bracket/ Laminate veneer debonding

Table 2:

Wavelength

Effect

400–780 nm (visible)

retinal burn

780–1400 nm (near-IR)

retinal burn

1400–3000 nm (mid-IR)

corneal burn

3000 nm–10000 nm (far-IR)

corneal burn

References

Franzen R (2010) Principles of Medical and Dental Lasers.

Goldman L, Goldman L, Hornby P, et al. (1964) Impact of the Laser on Dental Caries. Nature 203:417-417.

Maiman T, Maiman TH (1960) Stimulated Optical Radiation in Ruby. Nature 187:493-494.

 

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