In this article, the décolleté refers to the upper chest between the base of the neck and the upper breast. The area is exposed to intrinsic aging, sunlight, and mechanical stress related to breast movement and weight, all of which can contribute to thinning, laxity, and static wrinkles.
In July 2026, the Aesthetic Surgery Journal published an evaluator-blinded, randomized delayed-treatment study of a finished CaHA-CMC product diluted 1:2 with sterile saline for moderate-to-severe décolleté wrinkles. The paper is currently available as an accepted manuscript; copyediting may change its wording, but the DOI will remain the same.
The Study Enrolled 152 Women
The multicenter trial was conducted at nine sites in the United States and enrolled 152 women aged 30 to 65. The FDA Summary of Safety and Effectiveness Data reports 116 participants in the immediate-treatment group and 36 in the delayed-treatment control group for the Week 24 analysis.
The immediate-treatment group could receive up to three sessions under the study protocol, with optional retreatment. The delayed-treatment group remained untreated through Week 24, the primary endpoint, and then entered the same treatment program. Blinded evaluators assessed wrinkles at rest with the Merz Décolleté Wrinkles Assessment Scale.
| Study element | Protocol |
|---|---|
| Immediate-treatment group | 116 participants; CaHA-CMC diluted 1:2 with sterile saline under the study regimen |
| Delayed-treatment control | 36 participants; no treatment through Week 24, followed by treatment |
| Primary endpoint | Week 24 |
| Primary assessment | At least a one-point improvement from baseline on the wrinkle scale, judged by blinded evaluators |
The study examined a defined finished CaHA-CMC product and dilution regimen, not isolated CaHA microspheres or conventional HAp powder. The 1:2 dilution was part of this specific protocol and should not be treated as a universal ratio for other products, carriers, or anatomical areas.
What Does the 71.2% Response Rate Mean?
At Week 24, the estimated responder rate was 71.2% in the immediate-treatment group (95% CI, 61.4%–79.4%) and 6.3% in the untreated control group (95% CI, 1.5%–22.9%). The between-group difference was statistically significant.
A responder was defined as a participant with at least a one-point improvement from baseline on the wrinkle-at-rest scale. The figure therefore represents the proportion that met a prespecified scale threshold. It does not mean that wrinkles disappeared, nor does it show that one session would produce the same result.
The scale captured visible clinical change. The abstract did not report quantitative histology, so these data cannot be used to calculate changes in dermal collagen or elastic fibers.
Dilution Changes the Question Being Asked
Conventional contour augmentation focuses on localized support, volume, and shape. The décolleté covers a broader area, and this study evaluated static wrinkles and overall skin appearance rather than a defined increase in local volume.
Dilution with saline lowers the concentration of the CMC carrier and changes the rheology of the formulation. Tissue distribution also depends on injection depth and technique. The result therefore has to be read together with the product composition, dilution ratio, number of sessions, and outcome measure; the material name alone is not enough.
How Should the Safety Findings Be Read?
The accepted-manuscript abstract describes treatment as generally well tolerated, with predominantly transient, mild-to-moderate injection-site reactions. This supports a tolerability statement for the study population and observation period, but it does not establish an absence of risk or apply automatically to other formulations and treatment regimens.
The primary effectiveness comparison was made at Week 24. Longer-term durability, uncommon adverse events, and the contribution of each treatment session require additional follow-up and larger samples.
Why Was Breast Imaging Reviewed?
Because the treated area lies near the upper breast, the investigators retrospectively reviewed available post-treatment breast imaging. The paper and FDA summary report no interference attributable to diluted CaHA-CMC in the mammograms or breast-ultrasound images that were evaluated.
That finding applies to the imaging available within this study; it does not cover every imaging method, time point, or patient population. At approval, the FDA required a prospective post-approval imaging study in 30 women to evaluate mammography and ultrasound after treatment. The FDA database currently lists that study as pending.
This Was a Finished-Product Study
The trial used Radiesse diluted 1:2 with sterile saline. It was sponsored by Merz North America, and several authors were employees of Merz-affiliated companies. These disclosures do not invalidate the findings, but they belong alongside the randomized design, blinded assessment, and product-specific scope.
The FDA label expansion dated March 31, 2026 likewise applies to this specific finished product and dilution for correction of décolleté wrinkles in patients aged 22 and older. The trial itself enrolled women aged 30 to 65. Those populations should not be conflated, and the approval is not a class-wide finding for every CaHA-CMC or HA-CaHA formulation, or for isolated CaHA microspheres.
What Does the Study Add?
An earlier global consensus on skin tightening discussed diluted and hyperdiluted CaHA for the neck and body, while noting the need for stronger controlled evidence.
This trial adds a clearer Week 24 comparison through randomized allocation, a delayed-treatment control, and blinded scale assessment. Under a defined finished-product formulation, 1:2 dilution, and multi-session protocol, the proportion with at least a one-point improvement was higher than in untreated controls.
The evidence belongs to a particular product and study plan rather than to CaHA raw material as a category. For a broader discussion of why CaHA microspheres, CMC carriers, and other composite formulations need to be described separately, see “How CaHA Composite Systems Are Evaluated.”
This article reviews a published clinical study and its evidentiary limits. It does not provide injection instructions, recommend a medical product, or offer individual treatment advice.
References
- Fabi S, Moradi A, Hill D, Odena G, Kim SW, Graul V. Diluted Calcium Hydroxylapatite Carboxymethylcellulose (Radiesse) for Décolleté Wrinkles: Safety and Effectiveness in Adult Females. Aesthetic Surgery Journal. Published online July 9, 2026. DOI: 10.1093/asj/sjag142.
- ClinicalTrials.gov. Evaluation of the Effectiveness and Safety of Diluted RADIESSE in the Treatment of Décolleté Wrinkles. NCT05163353.
- U.S. Food and Drug Administration. RADIESSE Injectable Implant, PMA Supplement P050052/S162. Decision date: March 31, 2026.
- U.S. Food and Drug Administration. Summary of Safety and Effectiveness Data, P050052/S162.
- U.S. Food and Drug Administration. Safety Study to Assess Radiographic Imaging. Post-Approval Study P050052 S162/PAS001.