ND:YAG – Global Periolaser

The Neodynium-doped Yttrium Aluminium Garnet (Nd:YAG, wavelength 1064nm) laser was in fact the first laser used in dentistry, and has been very high profile in the periodontal world more recently with the development of LANAP, which has almost become synonymous with ‘laser perio’ due to their targeted advertising; however, this is just one use of this wavelength in periodontics, and several other protocols have been used with some success in the management of periodontitis. Without a doubt, it is an excellent ‘cutting tool’ and therefore useful in many other aspects of periodontology. Its emission mode is a free running pulse, which allows it to reach very high peak powers per pulse, although the clinical working average power is similar to diodes around 1 to 4W as its duty cycle is around 0.2%.

This laser is essentially a soft tissue laser, with limited use on hard tissues, other than perhaps desensitisation and the ability to penetrate into dentinal tubules to kill pathogens, which is something we know from endodontic applications. This has to be carried out with caution and in non-contact mode due to potential for damage through photo-thermal effects. Like diodes, its chromophores are melanin and haemoglobin, with a low absorption in water, which means that it penetrates deeper into the tissues. The penetration depth in vascularised or pigmented tissue is approximately 1mm, and in poorly vascularised, non-pigmented soft and hard tissues, it can penetrate approximately 1cm in non-contact mode. Unlike diodes, they rarely need carbonisation (initiation/ activation) of the fibre due to its high peak power. This therefore allows the laser to truly interact with the tissue and its components rather than creating a ‘hot tip’ to unselectively vaporise tissue. This also allows the practitioner to use the same fibre or tip to both disinfect and biomodulate without needing to cut the end of the fibre, provided it has been kept clean during the surgery.

Safety Considerations

There are safety aspects to consider with this laser wavelength. It has potential to damage the eye (retinal damage) from a distance of metres, and so all people present in the room should wear protective eyewear that is protective for that specific wavelength. In the mouth, there is potential to burn the soft tissues (carbonisation) and also induce bone necrosis due to high temperatures. The same applies for possible damage to the root surface, with melting and carbonisation if used inappropriately, and pulpal damage, again, due to high temperatures. The risk to damage of implant surfaces, with melting and pitting is high, and most of the literature actually stresses that this is an inappropriate wavelength to use on implants. (Park et al 2005, Deppe et al 2007)

Periodontal pockets

Depending on the parameters being used, it can be effective in periodontal pockets as a surgical tool to remove granulation tissue (curettage), which is how it is used as part of the LANAP protocol. However, it is also effective in pocket ‘disinfection’, where it is not cutting, and will have a role to play photo-biomodulation. Again, this is one of the benefits when used with the LANAP protocol. However, several studies have shown some success with Nd:YAG when used just as the latter two mechanisms (Qadri et al), where it is then applied with much lower doses, which are theoretically much less likely to cause damage to the root surfaces or bone. This type of protocol usually requires repeated consecutive treatment (typically four to six), and may be used effectively with a photo-sensitiser, and of course calculus removal is not possible, and no contact should be made with the bone or root surface. In fact, the presence of pigmented calculus could lead to overheating of the root surface, so it is essential to remove all calculus by conventional methods beforehand.

Its affinity to pigment makes it useful in periodontal pockets where several periodontal pathogens are pigmented, and therefore form a target for Nd:YAG wavelength. When used as a surgical tool to remove pocket lining, the tissue interaction is mainly photo-thermal, although there is an element of being more effective at cutting with lower powers in an inflamed periodontal pocket, where tissue is pigmented (red) and full of blood.

LANAP stands for laser-assisted new attachment procedure. It is essentially a minimally invasive surgical procedure aimed at resolving periodontal pockets and promoting new attachment, be that periodontal ligament, cementum, bone or hopefully all three – in other words, true regeneration. Histology studies (Yukna 2007, Nevins 2012) have demonstrated periodontal regeneration is possible following this procedure. The Nd:YAG laser (Manufacturer specific for this procedure) is used to remove diseased pocket lining, kill periodontal bacteria, and achieve some photo-biomodulation in the pocket, while a piezo-ultrasonic scaler is used to remove the calculus from the root surface and an explorer used to scrape the bone surface, which promotes bleeding into site and the release of stem cells. The laser is used a second time to promote clot formation through heat. This is a little controversial in that some studies suggest bleeding in the pocket promotes reattachment, while coagulation of haem can discourage connective tissue attachment; other studies suggest no difference in the outcome. Having a good understanding of the biological mechanisms involved in this procedure is essential to reduce possible side effects and make it safe. Again, like all lasers, it is not a magic wand, and cannot replace the fundamental need to remove calculus and biofilm from the pocket.

Other soft tissue surgical procedures

The advantage of using an Nd:YAG laser to cut tissues is a ‘bloodless’ cut, although anaesthesia should be used in all procedures. The tissue interaction here is a photo-thermal one. It is effective for gingivectomies, frenectomies, vestibular deepening, lip repositioning, operculectomy, removal of soft tissue swellings, soft tissue crown lengthening and gingivoplasty. Although, in all these cases, care is needed with the angulation used to avoid damage to the bone and tooth surfaces. For this reason also, it is not suitable to use to raise a flap. While it is a very good soft tissue cutting laser, hyperplastic tissue doesn’t have much pigment in it and tends to be very fibrous, and the laser tissue interaction is not so good here, so this isn’t the ideal laser for such cases where tissue thinning is the aim. Due to this wavelengths affinity to pigment and haemoglobin, it makes it a laser of choice to use for the removal of haemangiomas, haemostasis and depigmentation. This same affinity for pigment makes it inappropriate to use on implant surfaces. Due to its haemostatic properties, it is not suitable to prepare a recipient bed for a free-gingival or connective tissue graft, nor harvesting the graft as blood supply is paramount for the success of these procedures.

It also has uses in the management of denture stomatitis and oral ulceration through PBM effects. It can be used as a PBM treatment after any dental procedure to accelerate healing and reduce symptoms of pain and inflammation. It can be used as a desensitisation treatment independently, again, being careful about heat build-up.

Practicalities

The speed of cut is considered to be satisfactory – this can be manipulated by using greater power, but with potential to then do more harm and delay healing. On average, the healing time can be slower than conventional interventions, and slower than erbium lasers. Of course, the advantages of using lasers for surgery has already been outlined. It is moderately easy to use, with a steep learning curve, as it is mandatory to understand all the potential tissue interactions. Damage or harm will occur if the energy transmitted to the tissue is not successfully controlled (e.g through using too high a power or too slow a hand movement). The prices of these machines vary hugely, and some can be very expensive, but in general, running costs tend to be quite low, with not many consumables needed.

Patient acceptance is generally good, and these machines tend to be quite reliable (Dr Maden comments on the use of Fotona lasers here). In terms of billing patients – you tend to be able to offer a greater variety of treatments, such as periodontal pockets (particularly maintenance therapy or decontamination), desensitisation, herpes lesions, and haemangiomas. In terms of the greatest benefits into your practice? Greatest benefits into your practice being improving treatment results with higher patient satisfaction. Biostimulation and disinfection, and use on vascular lesions, are the best indications.

A few final personal comments from our contributor, Ilay Maden:

Can you comment on how you as a clinician have found the use of this laser wavelength to be an advantage to your clinical practice:

Clinical procedures are mostly straightforward with some time needed to learn the best practice for each indication especially the harmony of the power setting and hand movement speed for almost all indications.
Time taken to carry out procedures is usually acceptable with no time spent for sutures etc
The results obtained by incorporating lasers are satisfactory with mild discomfort for the patient and simple application of the laser
Increased practice revenue, better results, and unique treatments like herpes, haemangioma, biostimulation, dentin hypersensitivity.