Amaroli A, Ravera S, Parker S, Panfoli I, Benedicenti A, Benedicenti S
Lasers Med Sci. 2016 May,31(4):741-7. doi: 10.1007/s10103-016-1901-3. Epub 2016
Photobiomodulation is proposed as a non-linear process, and only low-level laser therapy (LLLT) is assumed to stimulate exposed cells, whereas high powered laser and fluences can cause negative effects, exhausting the cell’s energy reserve as a consequence of excessive photon-based stimulation. In our work, we investigated and compared the effects of 808-nm diode laser (CW) with a new flat-top handpiece. To this purpose, we tested the photobiomodulation effects of 1 and 3 J/cm2 fluence, both generated by 100 mW or 1 W of laser power and of 64 J/cm2 of fluence generated by 100 mW, 1 W, 1.5 W or 2 W, as expressed through oxygen consumption and ATP synthesis of Paramecium. Data collected indicates the incremental consumption of oxygen through irradiation with 3 J/cm2-100 mW or 64 J/cm2-1 W correlates with an increase in Paramecium ATP synthesis. The Paramecium respiration was inhibited by fluences 64 J/cm2-100 mW or 64 J/cm2-2 W and was followed by a decrease in the endogenous ATP concentration. The 1 J/cm2-100 mW or 1 W and 3 J/cm2-1 W did not affect mitochondrial activity. The results show that the fluence of 64 J/cm2-1 W more than the 3 J/cm2-100 mW causes greater efficiency in Paramecium mitochondria respiratory chain activity. Our results suggest that thanks to flat-top handpiece we used, high fluences by high-powered laser have to be reconsidered as an effective and non-invasive therapy. Possible associated benefits of deeper tissue penetration would increase treatment effectiveness and reduced irradiation time.
High fluence, Laser irradiation, Laser phototherapy, Low-level laser therapy, Mitochondria, Photobiostimulation
Meire MA, Havelaerts S, De Moor RJ
Lasers Med Sci. 2016 May,31(4):653-8. doi: 10.1007/s10103-016-1892-0. Epub 2016
Laser-activated irrigation (LAI) using erbium lasers is an irrigant agitation technique with great potential for improved cleaning of the root canal system, as shown in many in vitro studies. However, lasing parameters for LAI vary considerably and their influence remains unclear. Therefore, this study sought to investigate the influence of pulse energy, pulse frequency, pulse length, irradiation time and fibre tip shape, position and diameter on the cleaning efficacy of LAI. Transparent resin blocks containing standardized root canals (apical diameter of 0.4 mm, 6 % taper, 15 mm long, with a coronal reservoir) were used as the test model. A standardized groove in the apical part of each canal wall was packed with stained dentin debris. The canals were filled with irrigant, which was activated by an erbium: yttrium aluminium garnet (Er:YAG) laser (2940 nm, AT Fidelis, Fotona, Ljubljana, Slovenia). In each experiment, one laser parameter was varied, while the others remained constant. In this way, the influence of pulse energy (10-40 mJ), pulse length (50-1000 mus), frequency (5-30 Hz), irradiation time (5-40 s) and fibre tip shape (flat or conical), position (pulp chamber, canal entrance, next to groove) and diameter (300-600 mum) was determined by treating 20 canals per parameter. The amount of debris remaining in the groove after each LAI procedure was scored and compared among the different treatments. The parameters significantly (P < 0.05, Kruskal-Wallis) affecting debris removal from the groove were fibre tip position, pulse length, pulse energy, irradiation time and frequency. Fibre tip shape and diameter had no significant influence on the cleaning efficacy.
Erbium laser, Fibre tip shape, Laser-activated irrigation, Pulse energy, Pulse length, Root canal irrigation