Innovation in Laser Epilation: Evaluation of Triple Wave Emission in Super Hair Removal (SHR) and Hair Removal (HR) Combined Protocols

Jéssica Helena Franco Dorigatti^1,2*, Patricia Brassolatti², Livia Assis¹, Elisabete Loro de Oliveira Gonçalves³, Giulianna Bau Cesar^3, Michele Akemi Nishioka², Fabiele Cheiregato², José Ricardo de Souza², Laurita dos Santos¹, Ana Laura Andrade¹, Carla Tim¹

¹Scientific and Technological Institute, Biomedical Engineering, Sao Paulo, SP, Brazil
²IBRAMED, Brazilian Medical Equipment Industry LTDA, Amparo, SP, Brazil
³UNIFAE, University Center of Associated Teaching Faculties – FAE, Sao Joao da Boa Vista, SP, Brazil

*Correspondence author: Jéssica Helena Franco Dorigatti, Scientific and Technological Institute, Biomedical Engineering, Sao Paulo, SP, Brazil and IBRAMED, Brazilian Medical Equipment Industry LTDA, Amparo, SP, Brazil;
Email: [email protected]

Citation: Dorigatti JHF, et al. Innovation in Laser Epilation: Evaluation of Triple Wave Emission in Super Hair Removal (SHR) and Hair Removal (HR) Combined Protocols. J Dermatol Res. 2025;6(2):1-11.

Copyright^© 2025 by Dorigatti JHF, et al. All rights reserved. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Table 1: Fluence and energy used on the SHR protocol.

Table 2: Fluence and Energy ranges used on the HR protocol.

Evaluations

The participants attended twice a month: one day for evaluation and trichotomy and the following day for the epilation treatment. This protocol was repeated for each session, with a 30-day interval between them. For hair count and satisfaction analysis, the participants were reassessed 30 days after the sixth session.

Anamnesis

Anamnesis was always performed by the same evaluator, which was blinded regarding the treatment protocol. The following information were collected: volunteer age, inspection of axillae, skin phototype and hair density. The skin phototype was determined following the Fitzpatrick Rating. Hair density was categorized based on evaluator previous experience, whose visual analysis indicated the hair thickness: 1 = fine, 2 = medium, 3 = thick.

Hair Count

The patients were comfortably positioned in a supine position, with their arms behind their heads to expose the axillas. Photographic records were taken with a digital camera set on a tripod, 10 centimeters from the axilla, vertically aligned with the volunteers. Images were collected 24 hours before each procedure, capturing pre-treatment photos and followed monthly. A photographic evaluation was also conducted 30 days after the last laser application. For the initial assessment, participants were instructed not to perform hair trichotomy three days prior. For subsequent sessions, the evaluator conducted trichotomy 24 hours before the procedure. The collected images were analyzed using Image J software to quantify hair in the treatment area.

Volunteer Satisfaction

Volunteer satisfaction with hair reduction was assessed using an adapted version of the Global Aesthetic Improvement Scale (GAIS). This evaluation began after the second session and continued until 30 days after the final laser application.

Pain Perception

All volunteers were asked to report their pain perception after each laser application, using the Visual Analogue Scale (VAS). On the VAS, pain is categorized as mild (0 to 2), moderate (3 to 7) and intense (8 to 10).

Procedure Safety

To assess the safety of the procedure, a scale was established for volunteers to report the presence or absence of adverse effects, such as edema, erythema, dryness, tingling, itching, hyperpigmentation, post-inflammatory hypopigmentation and burns. The scale is categorized as follows: 0 = no effects; 1 = minimal effects; 2 = mild; 3 = moderate; and 4 = severe. Reports were collected after each application at intervals of 30 minutes, 1 day, 2 days and 3 days.

Temperature

To assess the surface temperature of the treated tissue, a FLIR-E49001 thermographic camera and a Multilaser Saúde – HC260 infrared consultation were used. Participants rested for 15 minutes in an air-conditioned room at approximately 22 ºC. Temperature measurements were taken before and immediately after each laser application and were repeated for all sessions.

Statistical Analysis

All data obtained in this study were subjected to the Shapiro-Wilk normality test. The data that showed normal distribution, where compared using a two-way ANOVA followed by post hoc Tukey test (hair count; pain perception; satisfaction via GAIS; adverse reactions). For temperature data, the comparison was performed using an one-way ANOVA with post hoc Tukey test. For all tests in this study, the significance level was considered to be p<0,05.

Results

Characterization of the Triple Wave Light Spectrum

Figure 1 shows the recorded emissions of the 763 nm, 800 nm and 1064 nm wavelengths from the Vega device. These peaks confirm the spectral regions claimed by the manufacturer, validating the triple-wave technology.

Figure 1: Light spectrum of the Vega equipment.

Sample Specification

Eighty volunteers were recruited for the study, of which 68 met the eligibility criteria and were randomly divided into three experimental groups. During the study period, 20 volunteers were excluded for missing two consecutive sessions. As a result, 48 women completed the procedure.

Sample Specification

Eighty volunteers were recruited for the study, of which 68 met the eligibility criteria and were randomly divided into three experimental groups. During the study period, 20 volunteers were excluded for missing two consecutive sessions. As a result, 48 women completed the procedure.

Table 3: Sample profile of the study.

Hair Count

In terms of overall efficacy, all three application methods demonstrated a significant reduction in hair quantity after six laser sessions, with the SHR group showing a 95.59% reduction, the HR group showing a 93.86% reduction and the SHR+HR group showing a 96.60% reduction (Fig. 2). When hair reduction was evaluated across the sessions, a significant decrease in hair quantity was observed up to the third session for all groups. Between sessions 3 and 4 and between sessions 4 and 5, significant reductions were observed for both the SHR and HR groups. However, no significant differences were noted between sessions 5 and 6 for any of the groups.

Figure 2: a) Rate of hair reduction; b) Patient satisfaction (GAIS scale). Source: Author data. (SHR) super hair removal; (HR) hair removal; (SHR+HR) super hair removal + hair removal.

Volunteer Satisfaction

Regarding volunteer satisfaction with the treatment, Fig. 2 shows that there were no significant differences in satisfaction levels between the different application methods, indicating that all groups experienced a similar degree of satisfaction with the epilation. However, satisfaction increased progressively across all three groups as the number of sessions increased. Significant differences in satisfaction were observed between sessions 1 and 2 for all groups. Additionally, a significant difference was noted between sessions 5 and 6 for the SHR group and between sessions 3 and 4 for the HR and SHR+HR groups. Notably, volunteers reported maximum satisfaction from session 4 onward in the HR and SHR+HR groups, which was maintained until the end of the treatment.

Pain Perception

Fig. 3 shows the statistical differences in pain levels reported by the volunteers throughout the sessions. The SHR and SHR+HR groups experienced lower pain levels across all sessions compared to the HR group. In session 4, the SHR+HR group reported statistically higher pain levels compared to the SHR group. It is important to note that for the SHR+HR group, session 4 marked the first use of the HR method. When assessing pain levels within each group, it was observed that pain decreased as the number of sessions increased. In the SHR group, although pain levels decreased with each session, a significant difference was observed between sessions 1 and 2 and between sessions 4 and 5. In the HR and SHR+HR groups, pain levels significantly decreased with each session, with notable differences between sessions 1 and 2, 2 and 3, 3 and 4, 4 and 5 and 5 and 6.

Figure 3: Scale for pain. Source: Author data. (SHR) Super Hair Removal; (HR) Hair Removal; (SHR+HR) super hair removal + hair removal. (****) p < 0,0001.

Procedure Safety

Among the adverse reactions evaluated, only erythema and edema were observed, occurring 30 minutes after each application. As shown in Fig. 4, these adverse reactions were reported only in the HR and SHR+HR groups, with statistically significant differences when compared to the SHR group from sessions 1 to 5. When comparing the HR and SHR+HR groups, significant differences were observed in all sessions. During the first three sessions, the SHR+HR group did not report any adverse reactions. However, from session 4 onward, reactions in this group were significantly greater than in the HR group. It’s important to note that for the SHR+HR group, adverse reactions were only observed during the sessions in which the HR method was used. In the intragroup analysis, the SHR group did not show any adverse reactions in any session. In contrast, the HR group experienced adverse reactions throughout all sessions, with a gradual decrease over time. However, this decrease was only statistically significant between sessions 2 and 3.

For the SHR+HR group, adverse reactions were observed only during the sessions where the HR method was applied. A statistically significant increase in adverse reactions was noted between sessions 3 and 4. In the following sessions (between sessions 4 and 5 and 5 and 6), a statistically significant decrease in adverse reactions was also observed.

Figure 4: Adverse reactions. Source: Author data. (SHR) Super Hair Removal; (HR) Hair Removal; (SHR+HR) super hair removal + hair removal. (#) SHR vs HR; (@) SHR+HR vs HR; ($) SHR vs SHR+HR.

Temperature

The measurement of axillary temperature after epilation was performed using two equipment: a thermographic camera and a digital thermometer. Both devices showed similar behavior in the variation of axillary temperature. Thus, for both equipment, the SHR group showed smaller temperature variation, with statistically significant difference when compared to the HR and SHR+HR groups. Besides, when comparing the HR and the SHR+HR methods, it was also observed a statistically significant difference with the method SHR+HR showing greater temperature variation (Fig. 5). Regarding the comparison between temperature measurement methods, Table 4 shows the statistical significances. For all groups, the physical evaluation performed with the thermographic camera registered lower temperatures than the ones obtained from the digital thermometer.

Figure 5: Average temperature variation. Source: Author data. (SHR) Super Hair Removal; (HR) Hair Removal; (SHR+HR) super hair removal + hair removal. (*) p < 0,001; (**) p < 0,01; (***) p < 0,0001.

Table 4: Comparison between temperature measuring equipment.

Discussion

Laser hair removal has been established as an effective and safe method, utilizing various wavelengths and technologies to accommodate a wide range of skin phototypes. Among these technologies, the HR and SHR application methodologies stand out, offering advanced options for different treatment needs. However, the benefits depend on several factors, including energy delivery, power settings, pulse duration and frequency. These parameters determine the laser’s ability to penetrate the skin and effectively target the hair follicles [10]. 

To explore these aspects in detail, this study compared traditional SHR and HR methods with a combined protocol that initially applied high-frequency, low-energy pulses (SHR) followed by low-frequency, high-energy pulses (HR) in subsequent sessions. The results showed that the hair reduction rate was not significantly influenced by the energy delivery method, as all groups achieved similar levels of hair growth reduction. Additionally, maximum satisfaction was reported by all participants after six treatment sessions.

Koo, et al., also compared the SHR and HR methods, using only the 810 nm laser [17]. Their findings, which showed similar hair reduction rates for both methods, corroborate the results of this study. However, it is important to note that the wavelength used may also affect hair reduction rates. A meta-analysis of laser hair removal revealed reduction rates of 52.8% for rubi (694 nm), 54.7% for Alexandrite (755 nm), 57.5% for Diode (810 nm) and 42.3% for Nd:YAG (1064 nm) lasers, measured at least six months after the last session [19].

In contrast, the study using the 810 nm laser reported hair reductions of 33.5% for the HR method and 40.7% for the SHR method after six months [17]. The present study, which used the triple-wave (755 nm, 810 nm and 1064 nm) methodology with similar treatment intervals (one session every 30 days), achieved hair reduction rates exceeding 93% for all groups. The triple-wave laser’s combination of wavelengths provides a more effective approach in a single session and enhances versatility, accommodating various skin phototypes and hair characteristics [3].

Another factor to consider is the application method’s impact on pain levels during the procedure. This study found that the HR method resulted in statistically higher pain levels in all sessions compared to the SHR and SHR+HR groups. Notably, pain perception increased in session 4 for the SHR+HR group, corresponding to the first application of the HR method. Other studies have also reported higher pain levels with the HR method, even for single-wavelength lasers [15,17].

The SHR method offers more comfort during treatment due to its lower energy and higher repetition rate, leading to gradual heating of the treated area. In contrast, the HR method’s high-energy, low-repetition-rate pulses result in a concentrated energy application over a short period, making it less comfortable [15]. Regarding adverse effects from high-power laser therapy, literature mentions potential issues such as edema, erythema, dryness, tingling, itching, post-inflammatory hyperpigmentation, hypopigmentation and burns with or without residual blisters [20,21]. In this study, only transient reactions of edema and erythema were observed, lasting approximately 30 minutes and occurring after HR method applications, including in the SHR+HR group. Consequently, discomfort and potential adverse reactions can be minimized by using equipment with a cooling tip [22]. The stable cooling of the epidermis during treatment reduces surface temperature while keeping the internal temperature unchanged [23]. Our study’s findings are consistent with this approach, as the integrated cooling tip in the equipment reduced epidermal temperature by up to 16^◦C. Additionally, the SHR method demonstrated less variation in local temperature. This may be due to the SHR method’s continuous energy pulse delivery, which gradually heats the epidermis, resulting in a lower temperature in the skin’s superficial layer [18].

The results of this study indicate that the application method did not significantly affect the hair reduction rate but did enhance treatment comfort. Selective photothermolysis was effectively achieved using the pre-programmed protocols of the VEGA equipment. This underscores the ease of use and safety of the technology, with energy parameters tailored to skin phototype and hair density, which are critical for high-power laser use. The study highlights the benefits of detailed protocol calculations and the advantages of adjusting parameters related to frequency and pulse duration. These findings align with the scientific understanding that high-power laser equipment has evolved over time. With a clear understanding of the required parameters, superior therapeutic results can be achieved, enhancing comfort and ensuring the technology’s safe application.

Conclusion

The results indicate the efficacy and safety of using the triple-wave laser with a cooled tip for hair reduction, regardless of the application method. Regarding adverse effects, only transient reactions such as edema and erythema were observed, with no severe adverse effects reported in this study.

Conflicts of Interest

The authors declare no conflict of interest in this paper.

Ethical Approval

This study was submitted to the Human Research Ethics Committee, registered under the number 6,775,097. After approval, subject recruitment was carried out through advertisement of social media (Instagram and Facebook). Interested parties were invited to participate in the selection process for the study, in which they received the free and informed consent form (TCLE) in order to understand the benefits and possible risks of the treatment offered in this study.

Funding

This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES) – Finance Code 001. The support was for conducting the research and did not influence the preparation of the article in any way.

Authors’ Contributions

All authors contributed to conceptualization, treatment execution, manuscript writing and final approval.

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