Hair removal was effective with the three tested treatment techniques (P < 0.0001). The average clearance achieved using the conventional (HR), in-motion (SHR) and stacking techniques were 75.5% (r =58–94%), 70.1%(r =63–91%), and 41.9%, (r =33–46%), respectively. No signiﬁcant differences were detected between the clear-ance observed in patients with previous hair removal treatments and patients receiving treatment for the ﬁrst time, nor were differences observed between light and dark phototypes. No signiﬁcant differences in terms of clearance were found between the conventional and in-motion techniques, whereas the stacking technique proved to be less effective.
The degree of patient satisfaction on a scale of 0–10 was 7.4 (r =4–10) for the conventional technique, 8.1 (r =5–10) for the in-motion technique, and 6.8 (r =5–8) for the stacking technique.
The treatments were well tolerated. The degree of pain reported during the ﬁrst treatment session for each of the three methods used is shown in Table 1.
TABLE 1. Degree of Pain Reported by the Interviewed Patients in the First Session and Percentage of the Samples for Each of the Treatment Methods
The characteristics of the new equipment, as well as its effectiveness (efﬁcacy under the conditions we used), have been very positive for the clinical research team, which is aware of the limitations and problems associated with hair removal and with the demands of patients. We consider the subjective efﬁcacy scores expressed by the participants to be clearly satisfactory, taking into account that these tend to be demanding patients and that a painless, rapid and perfect solution for removing all types of hair has yet to be found.
The conventional and in-motion techniques achieved high clearance levels, with a good efﬁcacy/safety proﬁle, both in ﬁrst-time patients and in patients who had been treated before. The personalization of the dosimetries and of the type of treatment chosen enabled similar efﬁcacy levels to be achieved in cases with a wide range of difﬁculty levels. The difﬁcult cases in terms of anatomical areas, skin phototype, and hair characteristics were resolved as satisfactorily as the cases that do not usually present problems. This was possible thanks to the personalization of the treatments and to the safety that the in-motion technique appears to offer for dark phototypes, although our sample of phototype V was very small.
On average, we consider that the clearances achieved were good in the context of the literature [7–11], and very good in comparison with our previous experience with other equipment [6,12–14]. The efﬁcacy percentages obtained appear lower than those achieved by Paasch et al. in a single patient with more suitable hair removal characteristics, using lower (and less painful) ﬂuences, with the same laser . Paasch observed a clearance of 91.6% using the in-motion technique and 88.8% using the conventional technique. Our study obtained relatively lower averages, which do not highlight the best cases. The images shown in the photographs are of results from the higher end of the efﬁcacy range.
It should also be noted that comparing clearances from very different studies, using different patients and methodologies, presents many limitations. For example, Jin et al. found reductions or clearances of 29.1% after four sessions using the 755-nm alexandrite laser , whereas Khouri describes clearances of up to 70.3% after just three sessions using the same laser . Even in our study, using the same hair-counting methodology, the observed vari-ability between subjects was relatively wide.
The concept of using low ﬂuences at a high average power with a multiple pass in-motion technique was introduced for the 810-nm diode lasers, leading to a dramatic decrease in therapy-related pain, less discomfort and good efﬁ-cacy [15–17]. The pain experienced by our patients was more signiﬁcant than in the case presented by Paasch et al.  because higher ﬂuences were required to achieve the results obtained. However, we should stress the good tolerance of the in-motion method, in which the level of pain was comparable when applying much higher total accumulatedenergythanwiththe conventional method.
The 755-nm wavelength, with a greater afﬁnity for melanin than the 810-nm wavelength proved to be capable of eradicating ﬁne and slightly pigmented hair, or miniaturized hair, in phototypes III, IV, and V when applied using the in-motion method. This therapeutic window is not well covered by other equipment available on the market. The results using the SHR method suggest that low ﬂuences (8–12 J/cm2) administered using a high pulse frequency (10 Hz) will enable a gradual, destructive heating of follicles, with little risk of thermal injuries, also potentially in phototypes V and VI. Hair survival and growth would be affected by the high energy deposit per surface unit, which is achieved by the multiple laser pulses and the constant movement of the handpiece on the treated surface. The shortage of phototype V subjects and the absence of phototype VI subjects in the researched sample do not allow us to provide more information in this regard.
In our clinical experience, we have found that residual hair responds poorly to the 810-nm diode laser and that, when using the 755-nm alexandrite laser, we can only safely achieve ﬂuences of 26–28 J/cm2. Using the new 755-nm diode laser in in-motion mode, the total accumulated energy was 143 J/cm2, which was very high but well tolerated and with a low risk of burns, and was able to remove residual hair from patients previously treated using the 810-nm diode laser and the 755-nm alexandrite laser.
Hair-removal efﬁcacy was lower when the stacking technique was used, probably due to the way in which the pulses were ﬁred in bursts, with lower accumulated energy per treatment area. However, this technique is useful in areas where the in-motion technique is not sufﬁciently accurate-for hair removal between the eyebrows, the upper edge of eyebrows or the deﬁnition of the upper edge of a beard, for example.
These preliminary results suggest that the 755-nm diode laser may be a highly efﬁcacious, versatile, and efﬁcient tool for medical hair removal. The most notable character-istic of this laser is the high energy that can safely be applied to treat difﬁcult cases. Comparative studies are required between the 755-nm alexandrite laser and the 810-nm diode laser to determine potential advantages and disadvantages of this technological innovation. The per-formance of this laser in phototype VI also remains unknown and requires future research.
1. Ibrahimi OA, Avram MM, Hanke CW, Kilmer SL, Anderson RR. Laser hair removal. Dermatol Ther 2011;24:94–107.
2. Casey AS, Goldberg D. Guidelines for laser hair removal. J Cosmet Laser Ther 2008;10:24–33.
3. Gan SD, Graber EM. Laser hair removal: A review. Dermatol Surg 2013;39:823–838.
Mustafa FH, Jaafar MS, Ismail AH, Mutter KN. Comparsion of alexandrite and diode lasers for hair removal in dark and medium skin: Which is better? J Lasers Med Sci 2014;5:188–193.
5. Grunewald S, Bodendorf MO, Zygouris A, Simon JC, Paasch
U. Long-term efﬁcacy of linear-scanning 808nm diode laser for hair removal compared to a scanned alexandrite laser. Lasers Surg Med 2014;46:13–19.
6. Royo J, Urdiales F, Moreno J, Al Zarouni M, Cornejo P, Trelles MA. Six-month follow up multicenter prospective study of 368 patients, phototypes III to V, on epilation efﬁcacy using an
810- nm diode laser at low ﬂuence. Lasers Med Sci 2011;26:247–255.
7. Paasch U, Wagner JA, Paasch HW. Novel 755-nm diode laser vs. conventional 755-nm scanned alexandrite laser: Side-by-side comparison pilot study for thorax and axillary hair removal. J Cosmet Laser Ther 2015;17:189–193.
8. Jin HZ, Wang JB, Jiang GT, Wang HW, Liu YH, Zuo YG, Li HC, Ma DL, He ZX, Feng JC. Effectiveness and safety of long-pulsed alexandrite laser for hair removal in 1702 patients. Zhongguo Yi Xue Ke Xue Yuan Xue Bao 2006;28:210–213.
9. Khouri JG, Saluja R, Goldman MP. Comparative evaluation of long-pulse alexandrite and long-pulse Nd: YAG laser systems used individually and in combination for axillary hair removal. Dermatol Surg 2008;34:665–670.
10. Davoudi SM, Behnia F, Gorouhi F, Keshavarz S, Nassiri Kashani M, Rashighi Firoozabadi M, Firooz A. Comparison of long-pulsed alexandrite and Nd: YAG lasers, individually and in combination, for leg hair reduction: An assessor-blinded, randomized trial with 18 months of follow-up. Arch Dermatol 2008;144:1323–1327.
11. Kutlubay Z. Alexandrite laser hair removal results in 2359 patients: A Turkish experience. J Cosmet Laser Ther 2009;11:85–93.
12. Ancona D, Stuve R, Trelles MA. A multicentre trial of the epilation efﬁcacy of a new, large spot size, constant spectrum emission IPL device. J Cosmet Laser Ther 2007;9:139–147.
13. Levy JL, Trelles MA, de Ramecourt A. Epilation with a long-pulse 1064 nm Nd: YAG laser in facial hirsutism. J Cosmet Laser Ther 2001;3:175–179.
14. Trelles MA, Urdiales F, Al-Zarouni M. Hair structures are effectively altered during 810 nm diode laser hair epilation at low ﬂuences. J Dermatolog Treat 2010;21:97–100.
15. Pai GS, Bhat PS, Mallya H, Gold M. Safety and efﬁcacy of low-ﬂuence, high-repetition rate versus high ﬂuence, low repetition rate 810-nm diode laser for permanent hair removal. A split-face comparison study. J Cosmet Laser Ther 2011;13:134–137.
16. Brown M. Permanent laser hair removal with low ﬂuence high repetition rate 810nm diode laser: A split leg comparison study. J Drugs Dermatol 2009;8:14–17.
17. Koo B, Ball K, Tremaine AM, Zachari CB. A comparison of two 810 diode lasers for hair removal: Low ﬂuence, multiple pass versus a high ﬂuence, single pass technique. Lasers Surg Med 2014;46:270–274.