Energy And Density Of Fractional Laser Treatment For Scars

Introduction

Fractional CO₂ laser is currently the first-line treatment recommended by guidelines and expert consensus for scar treatment.

In clinical practice, energy and density are the two core parameters that determine the effectiveness of fractional laser treatment and control safety.

So, is it true that “higher energy and greater density mean better treatment results” with fractional lasers?

How can we accurately control the matching logic of fractional laser energy and density and achieve a proper clinical balance between the two?

This is a core concern in clinical treatment within the laser cosmetic industry and a topic we need to research.

The Core Theory of Fractional Laser Therapy

The clinical application of fractional CO₂ lasers is based on the focal photothermal (FP) theory. Its core mechanism comprises four main functions:

1. Precise Vaporization Ablation

It can instantly vaporize scar tissue, causing rapid coagulation and carbonization of local hyperplastic tissue, directly improving the problem of thickened and raised scars.

2. Regulation of Cell Metabolism

Through controlled thermal damage, it activates the skin repair mechanism, regulates the secretion of inflammatory cytokines, inhibits abnormal proliferation of fibroblasts and induces their apoptosis, thus blocking the process of scar hyperplasia.

3. Remodeling Collagen Structure

Utilizing the thermal effect to promote collagen regeneration and orderly reorganization, it optimizes the extracellular matrix ratio, downregulates the abnormal proportion of type I and type III collagen, and achieves scar loosening and softening.

4. Activation of Skin Regeneration

It initiates the differentiation of scar in situ stem cells, promotes the repair of the entire skin layer, and restores the normal structure and texture of the skin.

Compared to traditional lasers, fractional CO₂ lasers regenerate the epidermis faster, completing epidermal repair in 24-48 hours and significantly shortening the recovery period.

Scar Treatment Parameter Settings Reference

The clinical parameters of fractional CO₂ laser include four indicators: energy, density, pulse width, and frequency. Among them, energy and density are included in the expert consensus on scar treatment and are the core control indicators for clinical treatment.

• Energy determines the depth of laser penetration into tissue, directly affecting whether it can reach the hypertrophic dermal layer of scar tissue, and is the core factor ensuring treatment effectiveness.
• Density refers to the proportion of scar tissue covered by the laser per unit area, representing the extent of treatment trauma per unit skin area, and is crucial for controlling treatment safety and postoperative recovery.

Simply put, energy addresses the question of “how deeply the laser penetrates,” while density addresses the question of “how widely it can be treated.”

So, does increasing energy + raising density equal improved treatment effectiveness? Of course not!

The most crucial clinical principle is that fractional laser energy and density have no additive synergistic effect; combining high energy with high density is strictly prohibited.

Numerous clinical studies have confirmed that simultaneously increasing both does not improve scar treatment outcomes; instead, it can cause excessive thermal overload on the skin. Excessively high combined parameters lead to a large overlap in skin thermal diffusion, triggering a severe inflammatory response. This directly induces persistent erythema and edema, delayed wound healing, and thick crust formation, significantly increasing the risk of adverse reactions such as post-inflammatory hyperpigmentation, hypopigmentation, and secondary hypertrophic scarring. Simultaneously, severe thermal damage significantly prolongs the skin repair cycle, necessitating longer treatment intervals, which ultimately reduces overall treatment efficiency.

Based on a balance between safety and efficacy, two fundamental treatment combinations have been established clinically:

1. High energy, low density: Suitable for old hypertrophic scars with significant dermal hyperplasia and severe thickening. High energy ensures treatment depth, while low density controls the extent of trauma and avoids large-area thermal damage.
2. Low energy, medium-to-high density: Suitable for superficial scars and early-stage immature red scars. Appropriately expanding the coverage area improves the overall texture of the scar, while low energy avoids over-stimulating delicate new skin tissue.

So, what is low density? And what is high density?

Clinical Treatment Exploration at Different Densities

Based on recent comparative studies and authoritative guidelines and consensus, we can divide the commonly used densities of fractional lasers in clinical practice into two major categories: low density (1%~5%) and medium-high density (10%~26.5%).

1. Low-Density (1%~5%) Treatment

Features: Safety first, suitable for special populations and high-risk scenarios.

The low-density regimen is a high-safety treatment parameter recommended by authoritative guidelines. Its core advantages are minimal trauma, mild inflammatory response, rapid postoperative recovery, and extremely low risk of pigmentation.

A 2020 international expert consensus showed that 95% of international plastic surgery laser experts prefer the 1%~3% low-density regimen. The core logic is that low density significantly reduces laser thermal overlap damage. When combined with high-energy treatment, it can minimize the problem of skin thermal overload, achieving a “deep penetration, broad safety” treatment effect.

For the treatment of hypertrophic scars in children, 3%~5% low-density fractional laser is preferred. This is because children’s skin is delicate, their dermal repair capacity is unique, and their intraoperative cooperation is poor. The low-density regimen can significantly reduce intraoperative pain, reduce postoperative adverse reactions, improve treatment compliance, and avoid scar aggravation or pigmentation abnormalities due to excessive treatment stimulation.

Overall, the low-density treatment offers gentle results, with limited improvement in scar size after a single treatment. It is suitable for children with mild hypertrophic scars, early-stage immature congestive scars, scars in sensitive facial areas, and individuals at high risk of pigmentation. The core focus of this treatment is not rapid and potent repair, but rather safe, controllable, and steady improvement, making it suitable for long-term, multiple-treatment sessions.

2. Medium-to-High Density (10%~26.5%) Treatment

Features: Prioritized efficacy, suitable for severe hypertrophic scars in adults

Liton Laser’s comparison of 13% and 20% density treatment for hypertrophic scars after burns revealed that the 20% high-density group showed significantly better improvement in scar texture and color, without adverse reactions such as pigmentation or scar aggravation.

Further research indicates that among the 7.4%, 12.6%, and 25.6% density groups, the 25.6% high-density group showed the most significant scar improvement, and with proper postoperative care, the incidence of adverse reactions was not significantly different from the low-density group.

Studies on pediatric scars show that, under the same energy conditions, the 10% density group had a faster onset of action and a higher number of effective cases than the 5% low-density group.

These studies confirm that increased density has a clear beneficial effect on scar repair. Moreover, the treatment effect of medium-to-high density regimens is significantly better than low density, making it the preferred parameter for adult hypertrophic scars.

However, it is crucial to note that medium- and high-density treatments require even higher safety management standards. Higher density means more laser beams per unit area, resulting in larger areas of thermal overlap, more intense intraoperative pain, longer scab removal and healing periods, and a simultaneously increased risk of pigmentation. In clinical application, strict control of energy levels is essential; high-energy layers must be avoided, and treatment intervals should be appropriately extended to ensure the skin completes its repair and regeneration process.

This treatment plan is primarily suitable for moderate to severe scarring issues in adults, including hypertrophic scars after burns, old, thickened, and rigid scars, and mild contracture scars around joints.

Treatment plans for different types of scars

1. Red, pitted scars (with telangiectasia)

Treatment Plan: Direct CO2 laser fractional treatment immediately seals blood vessels and thermally shrinks raised areas.

Post-operative Management: Moist healing is encouraged to reduce the risk of pigmentation that may be caused by high-energy laser treatment.

Therapeutic effect: After three treatments, the scar has largely flattened, and erythema and capillaries have subsided.

2. Postoperative red depressed scar

Treatment Plan: Immediate fractional laser treatment, followed by two additional laser treatments.

Key Points of Operation: During the CO2 fractional laser procedure, the scar tissue is brought towards the center with both hands, and each scar is treated individually during this process. This results in more significant scar contraction and a more pronounced lifting effect. Immediate observation shows that the erythema reaction subsides rapidly, and the scar tissue noticeably flattens.

Therapeutic effect: At the 2-month and 7-month follow-up visits, the scar tissue had almost completely disappeared.

3. Before and after treatment of old atrophic scars

Treatment plan: Liton CO₂ laser, fractional laser + moist wound healing.

Operation points: Bring both hands together to bring the scar tissue closer together, then apply fractional laser treatment to the scar tissue.

Efficacy: After 4 treatments, the scar is flush with the skin.

4. Depressed scars with raised areas

Treatment plan: Fractional laser treatment (for sunken areas) + smoothing (for raised areas).

Post-operative care: Erythromycin eye ointment applied at least 6 times daily to keep the area moist.

Therapeutic effect: Immediate results after treatment; sunken areas quickly become smooth. After five treatments, the pre-operative sunken areas have essentially smoothed out, and the previously lacking white skin texture has also recovered well. The pre-operative raised areas have also largely smoothed out.

5. Depressed scars with uneven pigmentation

Treatment plan: Multiple scans using fractional scanning mode + DEEP mode.

Efficacy: Effects can be seen after the second treatment, and the improvement rate is high after 5 treatments.

6. Acne scars (pitted scars) and enlarged pores

Treatment Plan: High-energy fractional laser treatment is used for atrophic scars. For areas with enlarged pores, deep and surface ablation modes are used for enhanced treatment to better improve atrophic scars.

Efficacy: Improvement is seen after the first treatment.

High-quality Fractional CO2 Laser Machine

Liton Laser sells high-quality CO2 fractional lasers, suitable not only for various scar treatments but also for other skin lesions and basic aesthetic treatments.

Our fractional lasers are available in multiple power options: 30W, 60W, and 100W, to meet the needs of any cosmetic and medical procedure. Treatment modes include fractional and cutting modes, with an option to add a vaginal tightening treatment mode.

If you need to purchase a high-quality fractional CO2 laser, please feel free to contact Liton Laser.

Frequently Asked Questions

Q1: Can surgical scars/acne pits from several years ago still be improved?

Yes! It’s a consensus that mature scars can be significantly improved through treatment. Fractional laser treatment can partially reconstruct normal skin structure, not just provide surface repair.

Q2: Why are multiple treatments required for scars?

Scar repair needs to follow the skin’s physiological cycle (approximately 28 days). Each treatment initiates a new cycle of regeneration, and 3-5 treatments for gradual improvement is a scientifically sound process.

Q3: Will scars recur after treatment?

With adequate and standardized combined treatment, the recurrence rate is significantly reduced. The reconstructed healthy skin structure has long-term stability.

Q4: How long is the recovery period for CO2 fractional laser treatment?

We generally recommend a treatment interval of 3 months. Researchers have found that using ultrapulse CO2 fractional laser treatment for acne scars resulted in a physician-evaluated efficacy score of 2.35±0.98 (0-4 grade) at 1 month, which further improved to 3.15±0.73 at 3 months. This indicates that fractional laser treatment has a long-lasting effect, with continuous improvement observed long after the procedure, which is highly instructive for clinical selection of appropriate treatment intervals.

Q5: After CO2 fractional laser treatment, is it better for the scab to be more prominent and thicker?

There is no direct correlation! Scabbing is a problem caused by the thermal coagulation (necrosis) of tissue. A thicker scab indicates more thermally coagulated tissue adhering to the wound surface. We know that CO2 fractional laser treatment achieves its therapeutic goal by inducing tissue healing and repair through thermal damage. This heat consists of three main parts during treatment: vaporization (where each microbeam of the CO2 fractional laser directly acts on the skin tissue, which is then vaporized (removed) during the treatment, reaching 100°C); thermal coagulation occurs around the microbeams due to heat diffusion, resulting in an irreversible protein denaturation and necrosis zone at approximately 70-80°C; and further thermal damage occurs at approximately 55-65°C. The scab that forms after surgery is actually a scab of thermally coagulated necrotic tissue at 70-80°C.

Therefore, a thicker scab does not necessarily indicate a better treatment outcome!

Q6: How long after treatment can I return to normal work and life?

If using a normal fractional laser treatment, scabbing usually lasts 5-10 days. After the scab falls off, there will be a period of erythema. The duration of this erythema depends primarily on the treatment parameters. If the energy level is high, the erythema may last for 1-8 weeks, and in some cases, it may last up to 12 weeks with some redness. Post-treatment care also plays a role. Generally, the face will be noticeably red for about a month, but after about two weeks, the erythema usually doesn’t interfere with daily life with concealer.

Conclusion

For children with hypertrophic scars, those at high risk of pigmentation, and early-stage delicate scars, a 1%–5% low-density regimen can be uniformly selected to prioritize treatment safety. For adults with stable hypertrophic scars and moderate to severe thickened scars, a 10%–26.5% medium-to-high density regimen should be selected to prioritize improving treatment efficacy, while strictly controlling energy parameters and postoperative care.

Clinical studies have clearly shown that the therapeutic benefit of moderately increasing density in scar treatment is superior to simply increasing energy. Clinical parameter optimization should follow the core logic of “primarily adjusting density, secondarily adjusting energy.”