Laser Photonic Energy Delivery in Clinical Dentistry: Scrutiny of Parameter Variables.

Laser use in the disciplines of clinical dentistry, oral surgery and oral medicine have developed during a period of over 30 years. During that time, from a rudimentary base of non-awareness of the scientific processes involved or scope of possible application, the knowledge and understanding of lasers has grown and benefitted from structured research, postgraduate courses and qualifications. Both the sophistication and scope of use of laser photonic energy has increased significantly, to the extent that lasers can be incorporated to benefit almost all areas of patient-centred clinical dentistry. Research into laser-assisted therapies has reinforced the importance of “light dose” in order to maximise the benefits of applied coherent, monochromatic light energy to a given procedure, while minimising the risk of conversion of excessive energy into collateral thermal damage. This thesis by concurrent publication provides a thorough examination of both ablative surgical laser-tissue interaction and sub-ablative photobiomodulation. The importance of achieving accurate light-dose levels of irradiation of oral hard and soft tissues remains fundamental to delivery of appropriate laser therapy whilst minimising the risk of collateral damage to adjacent, non-target oral hard and soft tissues. As demonstrated through published systematic reviews, it is significant to note the absence of full operating parametry in many peer-reviewed published studies; such omission compromises the opportunity to achieve accurate laser applications that are chosen as adjunctive to a clinical procedure. In addition, the consequence of poorly or inaccurately calibrated optic fibre photonic delivery, as the method of choice with visible and near infra-red wavelength “diode” lasers, may compromise the intended outcome of a clinical procedure; taken as a component of a poorly designed study, such errors may distort the development of laser-assisted therapy through inaccurate data acquisition and interpretation arising out of calibration errors. Once receiving peer-reviewed publication, any reference incorporating laser use helps define the expansion of knowledge and use for the clinician; there is a consequent responsibility to ensure that published studies that directly affect clinical application of laser use are fully detailed, to avoid subsequent misinterpretation and maltreatment. A further area of concern remains the persistence in attribution of post-surgical healing phenomena, by way of photobiomodulation to those laser wavelengths solely within the “optical window” range of 650 – 1350 nanometers. Both clinical and underlying biochemical data support the concept of “uneventful healing” with all laser wavelengths in dentistry, and exploration of key biochemical processes provide testimony to both photo- and possible thermo-biomodulation actions that follow laser irradiation. Through examination of the many potential errors that may affect post-irradiation outcome, it is concluded that the risk would appear of greater significance with lower, photobiomodulation (PBM) fluences. The small difference between benefit and non-benefit with PBM, either as a stand-alone therapy or adjunctive to a surgical laser procedure, defines a perspective that underlines the balance of this thesis.