Lasers in Dentistry Part 1: Introduction

Laser Dentistry

Dr Ilay Maden BDS MSc PhD

Part 1

Introduction

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.

Although it is in constant improvement, the impression of dentistry is not yet where it should stand. However, some technologies like lasers help; mainly because the patient's fear is not of the dentist, but of the procedures. Patients have a very positive perception of lasers for medical/dental applications. Lasers are used to correct eyesight, 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 theories and working to make a working device, the laser was finally invented in 1960 (Maiman and Maiman 1960).

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. The first use of lasers in dentistry took place in 1964 (Goldman et al. 1964). 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 are gaining a larger group of users among dental practitioners. Laser Dentistry is an ever-evolving way of practising dentistry. Both the application varieties and evidence base of applications are continuously increasing. Lasers are used both as assistive and 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. Each wavelength has a unique interaction with a specific body tissue 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 occurs, and what modifications of laser parameters would affect the outcome.  Preferably, this knowledge should be gained before purchasing any laser. One should decide on the purchase, depending on this understanding and correlation of it to the practitioner's scope of practice.

 Indications, benefits, advantages and limitations of lasers

With many indications as listed below, 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 being referred 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 the 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 in the following parts of this series covering the practical use of lasers.

Soft tissue laser applications

Periodontal pocket disinfection & deepithelialization

• 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 the immune system, enzymes and metabolism
• Nerve regeneration
• Muscular TMJ problems
• Chronic pain
• Analgesia 

Hard tissue laser 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

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 to perform all laser dentistry indications.

Even though diode lasers’ cost has gone down greatly in the past few years, hard tissue lasers still 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 opening up the slots for more patients, more treatments, increasing treatment acceptance due to lasers’ positive perception or increasing the referrals by patients. One may direct the equipment's cost to the treatment cost once the practitioner feels confident and comfortable to do so. It is important to remember to include the cost of service and peripherals 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 result. Like improving in prosthetics, implantology or fact any branch of dentistry, getting better in laser dentistry is also a non-stop on-going process.

Safety is a crucial aspect of laser dentistry. As a surgical tool, lasers are capable of harming biological tissues. Eyes are particularly delicate to light energy. As seen on the table below, different wavelengths have different effects on the eye.

Table 2

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 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 the human eye, hence the need of protective goggles 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.

The secondary danger is to the skin. However, a defocused laser is usually safe, especially with the use 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. The 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 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 for the necessity of two different wavelengths lies in the rules of physics. Physics dictate what the laser can do for us. That means for more coagulation, deeper disinfection and biomodulation of the tissues, we need a near-infrared laser. To remove hard tissues, we need a wavelength absorbed highly in water, making it explode strong enough to break the bonds between hard tissue molecules. If we 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 for removing crowns, they can’t 100% eliminate the need for anaesthesia, can’t do the 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.  The 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 essential to understand the advantages and limitations of different wavelength and their interactions with different tissues. One thing to realize is that no one laser can have all the possible effects 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 laser's effectivity. 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 be 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 a built-in battery like some diode lasers have. It may be important for the bigger devices, whether it needs to be plugged in or connected to a compressor. 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 guides you to an informed decision, and the 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. This will lead readers to be able to learn about and compare different lasers. 

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.