The carbon dioxide lasers have wavelengths ranging from 9300-10600um in the far infrared spectrum. Older systems had emission modes of continuous wave or gated mode, while more modern systems have super-pulsed modes, which therefore have very high peak powers, low average powers, and with very short pule durations. Depending on the emission mode, the effect on the tissues can be quite dramatically different, and so the literature can be a little misleading if you read older papers that used CO2 continuous wave lasers, and try to extrapolate it to modern day systems. CO2 lasers have a very high absorption in water and hydroxyapatite, with the 9.3 and 9.6um having more affinity for the latter, which makes them effective lasers for use on hard tissues, while the 10.6 is used on soft tissues only.
Due to their very high absorption in water, the penetration depth is far less than Nd:YAG and diodes, being only up to 0.5mm, giving the user good control and precision when cutting soft tissues. It makes for an excellent ‘cutting tool’ and is often the laser of choice in excisional and incisional procedures, as well as haemorrhagic and coagulation disorders producing a bloodless field, with less post-operative discomfort, tissue coagulation, simultaneous wound disinfection, minimal swelling and scarring, but slower healing than with a scalpel blade (Pick & Powell 1993, White et al 2002). Bone charring was a significant problem with these lasers in continuous mode and therefore not so suitable for hard tissue procedures. However, superpulsed modes (1-7W average power, 20W peak power, 170-1170Hz, 300uS) have since been found to be safer to use near or on hard tissues (correct wavelength needed), creating narrower deeper cuts with far reduced collateral damage (Wilder-Smith et al 1997).
Safety issues apply as with all class IV lasers. The CO2 laser has the potential to damage the eye, with a risk of corneal or lens damage, and therefore the correct eyewear for all in the room is essential. Soft tissue burning is less of a risk compared to ‘hot’ lasers due to the very shallow penetration depth. If working with a 10.6um on soft tissue, care should be taken to avoid aiming the beam directly towards bone or tooth, otherwise there is a risk of carbonisation, cracking or melting of the root surface. Implant surface are not damaged by the CO2 laser, and can be used to uncover them and also in the management of peri-implantitis with minimal rise in temperature. Collateral thermal damage also risks damaging the pulp. As with all lasers, it is essential to train specifically on the laser being used and understand the safety aspects specific for that system and the parameters that can be used to achieve clinical benefit and avoid collateral damage.
There is little in periodontal literature supporting the use of CO2 lasers in the management of chronic periodontitis. However, as newer systems emerge which are shown to be safer to use with more effective delivery in flapless periodontal therapy, this may well change. Mechanisms of action for effectiveness in periodontal pockets include the ability to remove both the sulcular and outer epithelium without damaging the underlying connective tissue, which can be useful in new attachment procedures. Their coagulative effect can help with visibility into the pockets, and they have a highly bactericidal effect, with ability to contribute to decontamination of the pocket and biofilm removal. The issue with using CO2 lasers at the moment is that there is currently no effective way to deliver the energy in a safe controlled way into the pocket as a flapless procedure.
In the surgical setting, the CO2 laser can be used to remove granulation tissue, re-contour bone (9.3-9.6um only) and the 10.6um super-pulsed systems have also shown the ability to modify the root surface in such a way so as to make it more favourable for the attachment of fibroblasts. In addition, the 9.3um wavelength has a higher efficiency in heating surface dentine, leading to a desired crystallisation and fusion of the surface layer for a sealing effect in the management of dentine hypersensitivity (McCormack et al 1995)
Hyperplastic gingivae as a side effectof cyclocporine and calcium channel blockers. Tissue removed with CO2 laser. (Dr Robert Covissar)
Other Surgical Procedures
They are good lasers to use for soft tissue procedures such a frenectomies, incisional and excisional biopsies of all soft tissue swellings including fibro-epithelial polyps, pyogenic granulomas, mucoceles, removal of hyperplastic tissue, reverse vestibuloplasty, gingivectomies and gingivoplasty – although care needs to be taken when in close proximity to the tooth. It is often the oral surgeons laser of choice. These procedures are effective through a photo-thermal tissue interaction. Care needs to be taken when approaching the periosteum, so perhaps not ideal for vestibular deepening. The shallow penetration depth (as opposed to diodes and Nd:YAG, but like with Erbium), makes it useful when being used in close proximity to sensitive structures such as the lingual nerve in operculectomies and removal of lingual tissue.
Frenectomy Using a CO2 laser (Dr Robert Convissar)
Haemangiomas can be treated with these lasers due to their good haemostatic and coagulative effects, but careful assessment is required beforehand to investigate the nature of the vascular lesion, be it venous, capillary or arterial in origin, in which case a more multi-disciplinary approach and other lasers may be of more use. Depigmentation is also effective with this laser, through the surgical removal of the melanocytes through photo-thermal ablation and good control due to the shallow penetration, rather than any affinity to pigment. This wavelength is not highly effective in phot-biomodulation other than perhaps a small secondary element through warming of the tissues during a procedure. It can be used to manage aphtous ulcers through vaporisation, coagulation and decontamination of the surgical site, and reducing post-op pain as nerve endings are sealed. However, with any treatment of any ulceration, care should be taken to be certain of the diagnosis due to the risks of it being a carcinoma
When it comes to micro-surgical and grafting procedures, it not ideal to raise flaps (full or partial thickness) or tunnel for root coverage due to potential risks to underlying structures that are not visible and the limited control; however they can be useful to coagulate the palate after harvesting a graft, and for de-epithelisation of papillae, as well as root surface conditioning. They are safe to use to implant surfaces in the management of peri-implantitis and to uncover implants (care needed).
The CO2 laser is a very powerful wavelength that provides a good speed of cut and coagulation at the same time. It has reduced surgical time of various procedures. The average healing time following CO2 laser surgery is two weeks. The wound site has increased levels of hyaluronic acid and so there is reduced scarring compared to the use of scalpel blades. (Pogrel et al 1993). They are relatively easy to use, with a moderate learning curve, and of course it is essential to understand all the parameters to avoid harm. They are quite expensive to buy, but not expensive to use with minimal consumable costs. Reliability varies amongst the machines.
A few final comments from our contributor, Reem Hanna:
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:
Incorporating CO2 laser, 10600nm, into my clinical practice as an oral surgeon has enhanced my patients’ experience, acceptance, and satisfaction of the surgical procedures. Working in bloodless surgical field especially in paediatric oral surgery cases has reduced the surgical time and eliminated the need for sutures, reduced the need for exposing paediatric patients for general anaesthetic. My clinical research study has shown less post-operative complications in the management of paediatric oral surgery using CO2. In terms of increased revenue, or return on investment, I only work in a hospital setting, but imagine the ability of the clinician to offer a wider range of treatments in-house, as well as reduced surgical time, and reduced post-op time due to fewer complications and no need to remove sutures etc, would all help towards covering costs.
Gingivectomy using CO2 laser (Dr Robert Convissar)