Photobiomodulation: How Many Sessions and How Often?

Photobiomodulation (PBM) is a complex treatment modality due to the great variation in possible parameters. Wavelength, power of the source, energy density, power density, irradiation time, and total applied energy present a wide range of combinations and this is obvious in the literature. A further complicating factor is a frequent lack of reporting all the used parameters. Yet another factor is the number of sessions and the intervals between them. Several successful protocols are reported in the literature, but from a practical point of view, these can seldom be used in clinical practice due to complications in traveling, cost, and compliance. This article takes a look at some of such time protocols and suggests a partial solution.

Most conditions treatable with PBM require repeated sessions for a successful outcome. In the conventional dental setting, however, a single application is often applied directly after a surgical intervention. Further applications can be performed upon subsequent visits for additional basic treatment or for control. Such suboptimal protocols are created out of necessity, the patient being unable or unwilling to return very often for a short PBM treatment. Using standard periodontal treatment as an example, the following is a brief account of treatment protocols used in the literature. Other important parameters are not considered here, although very important.

It is known that PBM doses are cumulative, meaning that several sessions in a short space of time can lead to inhibitory levels. Then, are daily irradiations too much? And if so, after how many consecutive days? Should the irradiation be performed daily during the first 3–4 days and then at longer intervals? Let us look at a few examples! Qadri ¹ treated once a week for 6 weeks. Pejcic ² irradiated daily for 10 days. Obradovic ³ irradiated for 5 consecutive days. Calderín ⁴ irradiated one group of patients only once and another group five times in 2 weeks (days 1, 2, 4, 7, and 11). Makhlouf ⁵ irradiated 3 times in weeks 1 and 2, 2 sessions in week 3, and 1 session in weeks 4 and 5, a total of 10 sessions. Aykol ⁶ irradiated on the first, second, and seventh day. Kumaresan ⁷ irradiated after treatment and then weekly, total of six sessions. Pesevska ⁸ compared 5 and 10 daily sessions. From the selected studies, it appears that there is no consensus about the optimal number of sessions or their intervals. The necessity to perform several irradiations is illustrated by Calderín. ⁴ Multiple sessions of PBM showed a faster and greater tendency to reduce proinflammatory mediators and RANKL/OPG ratio. Pesevska ⁸ found significantly decreased level of COX-2 expression for groups 5 sessions and 10 sessions after treatment, and the lowest average expression was found in the group that had the 10 laser sessions.

The literature suggests that PBM can have a positive influence on the outcome of traditional periodontal therapy. It further suggests that several sessions are required. As already underlined, frequent irradiation is possible in a research program but not easily under conventional circumstances. The partial solution could be the use of a simple home care device. Such a battery-operated device in the form of a double impression tray could be used at home in accordance with the instructions of the dentist or dental hygienist. It could use either lasers or light emitting diodes (LEDs). For home bleaching purposes, such products are already available, but these diodes are not reaching the molars and are not facing the bone level. Home care LED devices for joints and muscles can already be found on the Internet, and if used in cooperation with professionals, such adjunctive products can be useful. PMB can replace or supplement pharmaceuticals in many cases, but in contrast to pills, patients cannot take the treatment home.

This brief review is limited to the use of PBM in combination with traditional periodontal treatment, but the question remains valid for PBM in general. Further development of professional as well as home care PBM devices is foreseen.