We present a summary of the clinical studies carried out at Unilaser Médica, which have led us to the following considerations:
- Laser is most effective on legs
- The long-term result duration is real with the laser
- Long-term hair reduction is achieved permanently if reductions greater than 90% are achieved for more than one year.
- Laser hair removal on the face has the lowest response.
- Alexandrite laser treatment is more likely to cause burns than diode lasers.
- Laser is effective when the hair population is dense and extensive.
after 6 laser
sessions
after 18 laser
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after 19 laser
sessions
Laser hair removal is the most popular cosmetic procedure in the world. Its benefits are overwhelming.
All hairs present at the laser hair removal site should show the effect of the laser.
Not all hair falls out after laser
When patients are seen at shorter intervals, less than 8 days, we will find in many cases with thick and dense hair, where not all of the hairs have been captured by the laser.
If we have not previously shaved the patient, after 15 days, in the densest areas we will find some new hairs (with a fine tip)
On day 21, we will find that many hairs have already fallen out, but the population of pointed hairs is more abundant.
On day 30, depending on the area and especially with thick hair, hairs of all lengths will be observed to begin the second session.
In an area with abundant fine hair such as the upper lip, we will observe on day 8 of using the Alexandrite laser that, in many cases, the smallest hairs are in the same state, while the medium-sized hairs will look burnt and come out when pulled.
Laser hair removal for areas with thick hairs gives a response in 15 to 21 days. By then, we will have fine and medium-thick hairs starting to appear.
When we perform laser hair removal on large areas such as the legs with different hair thicknesses, we will find similar findings depending on the amount of thick or medium hair.
If we have a high population of lighter colored hair, it will be observed that many hairs will have had no effect by day 8. These will continue to grow and, by day 15, the majority of hairs will fall out.
What happens between hair and laser?
The laser will consume the most superficial, thickest, darkest and densest hairs.
A dense area requires more laser sessions at the beginning of treatment than a less dense area.
The deep hairs that are actively growing will be the ones that appear earliest.
A study analyzed the benefit of seeking a better laser action by performing waxing before laser hair removal. They found a greater reduction (15%)
https://pubmed.ncbi.nlm.nih.gov/12562338/
So what do the hair growth phases involve in laser hair removal?
Laser hair removal causes the hair growth phases to become more uniform, as observed when the hairs reappear as they all come out at the same time.
The persistence of hair between sessions could be explained by the incomplete effect of the laser.
There may be deficits in coverage, power, or pulse length.
If coverage deficits occur, some hairs will be observed to be longer than others, which will show those that were not exposed.
Power or laser type deficits will occur when it is observed that no change occurred and instead the hairs continued to grow. This occurs with thin, light hair using diode or Nd-YAG lasers.
It may also happen that the applied pulses were not sufficient to affect all the follicles; when firing with long pulses, it will be observed that the thin hair does not respond while the thick hair does not burn but if pulled, it will come out gently.
A reduction in the amount of hair should be achieved in each session, with increasing intervals in weeks between sessions.
We encourage touch-ups within the same month of the session to ensure complete coverage.
This strategy is very evident in dense areas of thick hair where a more follicular action can be sought.
On the face with thick hair, sessions every 3-8 days remove persistent hair. However, it does not prevent the paradoxical stimulation of hair, which causes the aesthetic defect of replacing dense areas of thick hair with larger areas of thinner hair.
Analysis of research work on laser hair removal carried out at Unilaser
An early evaluation carried out with Dr. Sara Gutierrez and Dr. Adriana Motta in the 1990s led us to calculate a first approach to the results by estimating the satisfaction levels of the patients at that time. We found that the satisfaction levels were lower in the face areas despite a greater number of sessions in a shorter follow-up time (65 days). At double the follow-up time, 90 days, the patients showed greater satisfaction in the areas of the legs, bikini and armpits (87%).
Later, in early 2000, Dr. Sara Gutiérrez and I analyzed the reduction in different areas.
Finding lower results in the anterior neck, eyebrows, areolas, upper lip, sideburns. All these areas reached a maximum of 61%.
The lower limbs already showed better results than the bikini and armpit areas. The subsequent arrival of diode lasers significantly improved the results of hair removal in these areas.
Hair reduction over a year, greater than 90%, was a predictive factor found by Ballesteros and Ríos in the first research work on results, work carried out with the Epidemiology Department of the Universidad del Rosario (2008). https://repository.urosario.edu.co/handle/10336/2708
Most of the poor outcome cases never achieved greater than 90% reduction at more than 1 year.
Achieving a long-term result of more than 90% takes between 5 and 12 sessions on the legs, which is usually the area with the best response when comparing all areas.
Hair reduction in dense areas such as beard, armpits and bikini usually requires a greater number of sessions in an initial period and is where the incomplete action on the hair removal areas leads to very long treatments.
removal sessions behave at late intervals
between sessions. Note the low reduction.
With lasers it is possible to maintain depilated
areas until massive follicular atrophy, when the
intervals are already longer.
A second study with Dr. Sergio Sanchez (2012) intended to find reduction ranges greater than 90% but these cases were a minority.
A total of 55 women were studied who received treatment over an average period of 6 years (Range 4-14).
The average total reduction was 79.36 ±15.51 %
Average follow-up time 17.49 months (Range 6-72 months)
Latino skin color predominated in 83.6% (n= 47).
89.1% of cases had dark hair color shades.
Average age: 32 ± 9.3 years.
18.2% of patients had a diagnosis of Polycystic Ovary Syndrome (PCOS) or clinical hyperandrogenism.
. https://repository.urosario.edu.co/handle/10336/4063?show=full
The Alexandrite laser was used in 98% of patients.
No significant correlation was found between the fluence used per session and a significant reduction.
Average number of sessions 27 (Range 20 to 61).
A significant correlation was found regarding accumulated values of energy supplied. (p <0.01) not correlated with a higher number of sessions. (r= -0.123, p= 0.370)
Only 32.7% showed reduction > 90%
3 cases had a 100% reduction
3.63% (n=2) of patients presented reduction rates below 50%, (40% and 30.5% respectively).
In both the Ballesteros study and a third study conducted with Dr. Julian Alvarez (2012), we found a similar response in the reduction in areas of thick and dense hair.
The greater number of sessions in the armpits is explained by the fact that it is an area that is easier to evaluate and more amenable to touch-ups.
The study by Ballesteros (2008) analyzed hair reduction levels, average number of sessions, average number of shots per treated area and the dose of energy applied.
The greatest efficiency was obtained in the lower limbs, mostly legs rather than thighs.
It is inferred from the data that 10-pass coverage on legs was 5 times more effective than in dense areas and/or areas with fine, dense hair.
Virtually complete long-term reduction was achieved without area preference and in almost all cases using the Alexandrite laser.
The number of laser hair removal sessions and their results…
Relating the number of sessions and the results greater than 90% in the long term, we find that in a number less than 10 sessions, the majority are not in the range of reductions greater than 90% in the long term.
In the range between 11 and 15 sessions the range is reversed, going to almost 60% of cases compared to 40% that are not yet.
And, in the range sessions #16-20 we have a 20-80% relationship showing that a greater number of sessions increased the cases with better reductions.
For the last range analyzed (<=20), cases of sessions on the face predominated and the greater number of sessions did not affect the proportion in this group, meaning that for this area, with a greater number of laser sessions, it was not possible to proportionally increase more successful cases.
With less than 10 sessions, similar percentages were obtained between the two groups, those with more than 90% reduction and those that did not.
The best response was obtained in the range of 16 to 20 sessions, achieving more than 90% long-term reduction.
In the range of more than 20 sessions, facial hair removal cases exceed more than 20 sessions.
The Ballesteros study was carried out by analyzing areas in 4 zones: face, armpits, bikini and lower limbs.
Age between 17 and 61 with an average of 34.8 years,
The majority of patients (79%) had dark phototypes: light brown and dark brown.
Hair color dark brown 40.4% and black 50.9%. The remaining light brown (8.8%)
Observation intervals averaged just over 2 years (29 months +/- 20.3 months)
Session range 3-53
Of the total number of sessions, 79.7% were performed with the Alexandrite laser.
The duration of treatment was 3.92 years.
