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An 18-month analysis of the duration of the clinical effects and tolerability of Definissse™ core + lidocaine volumizing filler for midface volume restoration: A prospective and single-center study
, Siham Rharbaoui3, Dennis Malvin Malgapo4, Martina Manni5, Silvia Innocenti5
*Corresponding author: Giovanni Salti, Medlight Istituto Medico, Via Claudio Monteverdi, Florence, Italy. giovannisalti@gmail.com
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Received: ,
Accepted: ,
How to cite this article: Salti G, Siquier-Dameto G, Rharbaoui S, Malgapo DM, Manni M, Innocenti S. An 18-month analysis of the duration of the clinical effects and tolerability of Definissse™ core + lidocaine volumizing filler for midface volume restoration: A prospective and single-center study. J Cutan Aesthet Surg. 2025;18:286-93. doi: 10.25259/JCAS_46_2025
Abstract
Objectives:
Definissse™ core + lidocaine (DEFCL) volumizer is a cross-linked high G’ hyaluronic acid (HA) filler that restores midface volume. The previous studies have documented its effects and tolerability up to 12 months after injection. This 18-month analysis aimed to establish the long-term tolerability and clinical effects of DEFCL volumizer in treating midface volume loss in middle-aged women.
Material and Methods:
This paper continues the previously published analyses of the prospective and single-center study documenting HA safety and effects after 12 months. Adverse events and injection site reactions were monitored throughout the study. Outcomes were assessed using the Global Aesthetic Improvement Scale, facial volume loss scale, and various skin measurements. Descriptive statistics were provided for all time points. A paired t-test was used to assess outcomes, the Shapiro-Wilk test was done to determine the Gaussian distribution assumption of each outcome, and in case of rejection, a Wilcoxon signed-rank test was applied.
Results:
All adverse reactions were addressed post-trial, and satisfaction ratings for injectors and patients remained high. Analysis showed ongoing volumization, enhanced skin quality and thickness after 18 months.
Conclusion:
DEFCL provided sustained volumization, enhanced skin quality, and high satisfaction ratings at 18 months. Further research is warranted on the observed long-term volume-enhancing effects of DEFCL. It is advisable to investigate DEFCL’s influence on tissue reorganization and remodeling to ensure safety at the molecular level.
Keywords
Clinical trial
Durability
Hyaluronic acid filler
Tolerability
Volumization
INTRODUCTION
DEFCL volumizer filler (Definisse™ core filler + lidocaine) is a Conformité Européenne (CE)-marked (CE 0120) injectable class III hyaluronic acid (HA) device used for volume correction. It is made of cross-linked sodium hyaluronate 25 mg/mL (with 0.3% lidocaine hydrochloride) manufactured with XTR™ Technology (RELIFE S.r.l. [Menarini Group]).1,2 We have previously reported the 12-month durability and safety of DEFCL volumizer based on investigator- and subject-led grading.3 This post-market clinical investigation was conducted to evaluate the performance and safety of DEFCL for facial volume restoration and augmentation after 18 months.
MATERIAL AND METHODS
Subjects
A total of 50 women, with an average age of 51 years, were included in the study, with one subject lost to follow-up through M9 and M12. The subjects were instructed to return on M3, M6, M9, M12, and M18 after the first study visit [Figure 1].
- Procedural flow diagram.
All subjects involved in this clinical investigation were thoroughly informed verbally and in writing about the investigational device, its clinical effects and duration, and the study procedures before any investigational activity. Each subject was required to sign an informed consent form written in clear, understandable language. The investigator kept a log of all subjects who signed the consent form. This investigation was conducted according to European Norm (EN) and International Organization Standardization (ISO) standard 14,155:2012 and their subsequent updates and local regulatory requirements from the National Ethics Committee of France. In accordance with local regulation, the plan and investigation documents were reviewed and received a favorable opinion from the Independent Ethics Committee on March 12, 2020. All procedures complied with the ethical guidelines established by the Declaration of Helsinki.
Study design
As in the 6-month and 12-month studies,2,3 the Global Aesthetic Improvement Scale (GAIS) was used to assess both primary and secondary endpoints based on improvements rated by the subject and the injector. Other endpoints reported include the facial volume loss scale (FVLS),4 stereophotogrammetry (Mini 3D LifeViz Mini, QuantifiCare),5 skin density and thickness,6 skin elasticity, firmness, tonicity, and suppleness.7
The previously described Pegasus technique was used to inject DEFCL volumizer at specific points in the midface. The injection points on the patient’s face are strategically placed to mimic the shape of the wings of this mythical winged horse in mid-flight, contributing to a distinct reshaping and lifting effect.2,3
Using a 27G needle, the filler material is injected into the zygomatic area, malar area, and deep pyriform fossa.2 Touchups were performed at 1 month (M1) as needed. As reported in our previous publications, approximately 2 mL of filler material is injected supraperiosteally per hemifacial region (totaling 3.2–4.4 mL).
Study endpoints
Improvement in the injector-assessed GAIS at M1 (the primary endpoint) has been described previously. Here, the durability of this parameter and subject-assessed GAIS, improvements in skin quality, the need for touch-up injection/s, and objective evaluation of restoration and/or augmentation of facial volume, are reported. Finally, Injection Site Reactions (ISRs), including redness, pain/tenderness, induration, edema, lumps/bumps, bruising/hematoma, itching, and coloration/discoloration, were monitored and outcomes are reported here.
Statistical analysis
No changes were made to the initial statistical analysis plan (SAP). The SAP outlining the detailed statistical methodology was written and approved before the first intermediate data review. All statistical tests were conducted at an α = 5% level of significance using a bilateral approach. No specific strategy was defined for handling missing data.
RESULTS
As reported in the 6- and 12-month analyses, individuals who had received treatments such as lasers, dermabrasion, chemical peels, mesotherapy, or other ablative procedures, as well as those who had undergone treatments with other fillers, threads, or surgery within the past 12 months, were excluded from the study.
Investigator-assessed and subjective GAIS’s
According to the investigator’s assessment, 100% of the subjects showed global esthetic improvement from immediately after the initial injection through M9. As expected, the percentage of subjects rated as at least “much improved” declined from 86% at M3 to 19% at M18. However, at 12 and 18 months post-injection, 98% and 94% of subjects continued demonstrating global esthetic improvement, respectively.
As outlined previously, 76% of subjects were rated as “much improved” to “very much improved” immediately after the initial injection, and this figure increased to 87.5% immediately following the touch-up injection [Figure 2 and Table 1].
- Distribution of Global Aesthetic Improvement Scale as assessed by the investigator. D0 after: immediately after the initial injection; M1 before: before touch-up; M1 after: after touch-up; M3-18: at M3 and M18 after the initial procedure.
| Time | Category | n(%) | 95% CI (%) |
|---|---|---|---|
| D0a | Improved | 50 (100) | (92.9, 100.0%) |
| M1b | Improved | 50 (100) | (92.9, 100.0) |
| M1a | Improved | 48 (100) | (92.6, 100.0) |
| M3 | Improved | 50 (100) | (92.9, 100.0) |
| M6 | Improved | 50 (100) | (92.9, 100.0) |
| M9 | Improved | 49 (100.0) | (92.7, 100.0) |
| M12 | Improved | 48 (98) | (89.3, 99.6) |
| No change | 1 (2.0) | ||
| M18 | Improved | 45 (93.8) | (83.2, 97.9) |
| No change | 3 (6.3) |
D0a: Immediately after the initial injection, M1b: Before touch-up, M1a: After touch-up, M3-18: At M3 and M18 after the initial procedure, respectively, GAIS: Global Aesthetic Improvement Scale, CI: Confidence interval
As reported in the 12-month publication, persistence in improving subjective GAIS was observed at M18. At M6, M9, M12, and M18, 94%, 88%, 90%, and 90% of the subjects still felt they had “improved,” respectively [Table 2].
| Time | Category | n(%) | 95% CI |
|---|---|---|---|
| D0a | Improved | 49 (98.0) | (89.5, 99.6) |
| No change | 1 (2.0) | ||
| M1b | Improved | 47 (94.0) | (83.8, 97.9) |
| No change | 1 (2.0) | ||
| Worsened | 2 (4.0) | ||
| M1a | Improved | 46 (95.8) | (86.0, 98.8) |
| No change | 2 (4.2) | ||
| M3 | Improved | 46 (92.0) | (81.2, 96.8) |
| No change | 4 (8.0) | ||
| M6 | Improved | 47 (94.0) | (83.8, 97.9) |
| No change | 3 (6.0) | ||
| M9 | Improved | 43 (87.8) | (75.8, 94.3) |
| No change | 6 (12.2) | ||
| M12 | Improved | 44 (89.8) | (78.2, 95.6) |
| No change | 5 (10.2) | ||
| M18 | Improved | 43 (89.6) | (77.8, 95.5) |
| No change | 6 (12.2) |
D0a: Immediately after the initial injection, M1b: Before touch-up, M1a: After touch-up, M3-18: At M3 and M18 after the initial procedure, respectively, GAIS: Global Aesthetic Improvement Scale, CI: Confidence interval
As mentioned in the first studies, 62.0% of subjects rated themselves as “much improved” immediately after the initial injection and 54.0% rated themselves as “very much improved” immediately after the touch-up injection. Subjective GAIS tended to be rated similarly throughout the follow-up period of 18 months [Figure 3].
- Distribution of GAIS scores as assessed by the subject. D0after: Immediately after the initial injection; M1 before: Before touch-up; M1 after: After touch-up; M3-18: At M3 and M18 after the initial procedure, respectively.
FVLS, cheekbone volume, skin density, and thickness measurements
The improvement in facial volume, observed at 12 months, persisted through M18 (P < 0.0001). The proportion of subjects with mild volume deficit remained low at this time point, and no new cases of severe volume loss were observed [Figure 4].
- Distribution of facial volume loss scale score as assessed by the investigator.
Objective measurements of cheekbone volume restoration declined consistently from baseline to M12, as expected, but showed an increase at M18, indicating a gain in maximum volume. This phenomenon may be due to the initial breakdown of the HA network early in the study followed by a rebound in volume expansion due to increased water absorption and tissue regeneration. The authors suggest that the cross-linking agent, 1,4-butanediol diglycidyl ether, degrades, exposing highly hydrophilic sites attracting surrounding interstitial water. Over time, cellular-level changes lead to tissue remodeling and regeneration of underlying tissue. These processes may explain the observed volume increase during the study’s later stages. All volume variations remained statistically significant throughout the observation periods [Figures 5 and 6]. Notably, despite the increase in volume at M18, neither edema nor swelling was reported.
- Total cheekbone volume variation as measured by the 3D LifeVizTM system *P < 0.001.
- Photographic series showing volume variation from D0 to M1, M3, M6, M9, M12, and M18 (R to L) in two patients: (a) A middle-aged woman with midfacial volume loss. (b) A younger patient with low zygomatic prominence.
From M3 to M9, skin density significantly increased compared to baseline. The most notable improvement was observed at M6, with a 21% reduction in the non-echogenic proportion compared to baseline (−0.076, P < 0.0001). At M12 and M18, the improvement in skin density was less pronounced, showing a 7% reduction at M12 (−0.0025, P = 0.1382) and a 6% decrease at 18 months (−0.0023, P = 0.0547). Changes in skin thickness were not observed from M3 to M12. However, a slight but statistically significant increase was documented at M18 (0.085 mm, 6%, P = 0.0002) [Table 3].
| Parameters | M3-D0 | M6-D0 | M9-D0 | M12-D0 | M18-D0 |
|---|---|---|---|---|---|
| Skin density | |||||
| n(miss) | 50 (0) | 50 (0) | 49 (1) | 49 (1) | 48 (2) |
| Mean (SD) | −0.048 (0.079) | −0.076 (0.062) | −0.067 (0.099) | −0.025 (0.117) | −0.023 (0.077) |
| P-value | <0.0001* | <0.0001* | <0.0001* | 0.1382* | 0.0457* |
| Thickness | |||||
| n(miss) | 50 (0) | 50 (0) | 49 (1) | 49 (1) | 48 (2) |
| Mean (SD) | 0.036 (0.202) | 0.041 (0.222) | 0.045 (0.231) | 0.038 (0.210) | 0.085 (0.200) |
| P-value | 0.2115* | 0.1998* | 0.1783* | 0.2173* | 0.0002† |
The investigators also noted further changes in skin biomechanical properties, including suppleness (elasticity and firmness) and tonicity (retraction). As previously reported, tonicity (Ur) and gross skin elasticity (Ua/Uf) changes remained significant until M6 only. Substantial changes in immediate extensibility (Ue), firmness (Uf), viscoelastic-to-elastic ratio (Uv/Ue), and total retraction (Ua) were reported from M3 through M12. All these changes, except for Ua, persisted through M18. In addition, a significant increase in the Uv/Ue ratio was observed at all-time points up to M18. These changes are consistent with the loss of skin elasticity, which is typical after HA injections. The changes in skin elasticity ranged from 10% to 17% for the Uv/Ue ratio [Table 4].
| Biomechanical properties | M3-D0 | M6-D0 | M9-D0 | M12-D0 | M18-D0 |
|---|---|---|---|---|---|
| Immediate extensibility (Ue) | |||||
| n(miss) | 50 (0) | 50 (0) | 49 (1) | 49 (1) | 48 (2) |
| mean (SD) | −0.085 (0.125) | −0.074 (0.092) | −0.048 (0.086) | −0.053 (0.089) | −0.043 (0.079) |
| P-value | <0.0001* | <0.0001* | 0.0003* | 0.0001* | 0.0005* |
| Firmness (Uf) | |||||
| n(miss) | 50 (0) | 50 (0) | 49 (1) | 49 (1) | 48 (2) |
| mean (SD) | −0.085 (0.142) | −0.074 (0.107) | −0.044 (0.102) | −0.037 (0.103) | −0.037 (0.090) |
| P-value | 0.0001* | <0.0001* | 0.0043* | 0.0150* | 0.0059* |
| Immediate retraction/tonicity (Ur) | |||||
| n(miss) | 50 (0) | 50 (0) | 49 (1) | 49 (1) | 48 (2) |
| mean (SD) | −0.048 (0.122) | −0.061 (0.093) | −0.020 (0.104) | −0.027 (0.103) | −0.018 (0.104) |
| P-value | 0.0076* | <0.0001* | 0.1757* | 0.0714* | 0.2419* |
| Total recovery to initial state (Ua) | |||||
| n(miss) | 50 (0) | 50 (0) | 49 (1) | 49 (1) | 48 (2) |
| mean (SD) | −0.082 (0.169) | −0.091 (0.132) | −0.044 (0.133) | −0.049 (0.131) | −0.031 (0.138) |
| P-value | 0.0012* | <0.0001* | 0.0265* | 0.0119* | 0.1304* |
| Viscoelastic-to-elastic ratio (Uv/Ue) | |||||
| n (miss) | 50 (0) | 50 (0) | 49 (1) | 49 (1) | 48 (2) |
| mean (SD) | 0.027 (0.039) | 0.026 (0.041) | 0.022 (0.037) | 0.035 (0.048) | 0.020 (0.041) |
| P-value | <0.0001* | <0.0001* | 0.0002* | <0.0001* | 0.0019* |
| Gross skin elasticity (Ua/Uf) | |||||
| n(miss) | 50 (0) | 50 (0) | 49 (1) | 49 (1) | 48 (2) |
| mean (SD) | −0.018 (0.093) | −0.036 (0.099) | −0.009 (0.104) | −0.019 (0.101) | −0.001 (0.106) |
| P-value | 0.1766* | 0.0131* | 0.5689* | 0.2035* | 0.9589* |
Subject and injector satisfaction ratings
Most subjects were satisfied with the treatment from M1 to M18. At M18, 100% of subjects reported that they felt that the intervention was beneficial, found their cheeks more attractive, considered the result to be natural, and would recommend the treatment to a friend. The majority (98%) were satisfied with the results and found their cheeks more symmetrical. In addition, 96% reported that their skin appeared more beautiful and firmer, while 94% felt that their face looked younger.
Safety
No severe or serious adverse events or device deficiencies were observed throughout the study. Like the 12-month analysis, the subjective- and investigator-observed ISRs gradually decreased over time and were nil by the 18th month (M18). Among the 15 subjects who reported 22 adverse device effects (ADEs) such as headache, injection site pain, oral herpes, gingival pain, injection site mass, injection site inflammation, and injection site paresthesia, all were asymptomatic by M18. Most ADEs lasted only a few days.
DISCUSSION
HA fillers currently available on the market claim that they can effectively sustain tissue augmentation for up to a year.8 However, the longevity of HA in human tissue can vary significantly due to factors such as product characteristics, the depth and area of injection, and the patient’s biological response. Key factors influencing the durability of HA fillers include HA concentration, swelling factor, level of crosslinking, particle size, and other rheological properties, all of which contribute to the gel behavior in vivo.9 In general, HA fillers with a higher degree of cross-linking tend to last longer and are less susceptible to degradation by hyaluronidase.1 When HA fillers are injected, they do not only provide immediate volume and hydration but they also stimulate the body’s natural processes. Fibroblast activity and collagen formation can prolong HA fillers’ durability.10 Pre-incorporated compounds, such as lidocaine, which have become standard in many commercially available HA fillers, do not affect filler durability.11
Although HA is regarded as a fully absorbable product,12 it is now understood to trigger a post-injection tissue response, leading to sustained tissue volume preservation in vivo. The natural biological response to HA, perceived as a foreign substance, generates autologous tissue, contributing to longer-lasting “volumetric changes.” This process may involve cell activation, collagen production, and tissue regeneration, decreasing the need for frequent reinjections. HA fillers provide more than just simple volume restoration; they facilitate long-term tissue remodeling and regeneration, especially in patients with resorbed or atrophied fat and bony tissue. This regenerative ability restores lost volume and encourages collagen production and underlying tissue regeneration, resulting in more sustainable, natural-looking outcomes over time.13
Recent studies challenge the traditional belief that HA filler effects last anywhere from 3 to 12 months. Evidence from imaging studies indicates that subdermal HA filler placement can persist for between 2 and 15 years.13 These findings highlight the importance of careful filler administration and precise placement to address volume deficiencies. Furthermore, there is a need to reevaluate refilling protocols, prioritize accurate clinical placement, and potentially use smaller amounts of filler, which may be more clinically acceptable. In addition, regular assessments should be conducted to determine whether the long-term effects of fillers remain manageable and desirable. Nonetheless, accumulating evidence supports the absence of lasting safety signals associated with HA filler injections following extended treatment periods (i.e., beyond 12 months).14,15
DEFCL volumizer effectively corrects mild-to-moderate tissue volume loss with predictable results when administered using a precise method, such as the Pegasus technique. DEFCL was associated with high ratings for subjective and investigator-assessed outcomes, including tissue volume, skin density, and skin quality improvements, with no lasting adverse reactions documented at 18 months post injection.
The rheological properties of DEFCL make it particularly well-suited for injection into the deeper layers of the skin, helping to restore lost volume. Its higher G’ value, combined with an intermediate degree of cohesivity compared to other fillers used for similar indications, provides a practical volumizing effect with a reduced amount of injected product.16 Although it is hypothesized that the long-term volume rebound observed with DEFCL is due to the exposure to water-binding sites following the degradation of HA cross-linking, further studies are required to validate this mechanism. Because tissue regeneration after HA filler injection is still a relatively new concept, additional research exploring DEFCL-driven tissue reorganization and remodeling at the molecular level is recommended. Finally, though HA filler administration may be done through either a needle or cannula, it should be guided by the injector’s expertise and by the specific requirements of the filler product (i.e., cannulas are generally unsuitable for bolus injections of fillers with elevated G-prime values).
CONCLUSION
In summary, the DEFCL volumizer filler is suitable for facial contouring and sculpting in individuals with mild-to-moderate midface volume loss. This long-term evaluation of the effects of DEFCL highlights the sustained dermatological and volumetric improvements observed in the cited 6- and 12-month studies. Furthermore, it adds to the growing body of research indicating the safety and efficacy of HA fillers, even with prolonged presence in the tissue. While evidence suggests that HA filler presence may persist for years, ongoing monitoring has not shown any significant long-term safety concerns.
Acknowledgment:
We extend our gratitude to RELIFE S.r.l. for providing an unrestricted educational grant to support this project.
Authors’ contributions:
Giovanni Salti, Gabriel Siquier-Dameto, Martina Manni and Silvia Innocenti conceived the research idea and designed the study. Siham Rharbaoui performed the experiments, collected the data, and Giovanni Salti, Gabriel Siquier-Dameto, Martina Manni, and Silvia Innocenti contributed to data analysis. Dennis Malvin Hernandez Malgapo was primarily responsible for writing the original draft of the manuscript. All authors critically reviewed, revised, and approved the submitted version of the manuscript, ensuring the accuracy and integrity of the work.
Ethical approval:
This investigation was conducted according to European Norm (EN) and International Organization Standardization (ISO) standard 14,155:2012 and their subsequent updates and local regulatory requirements from the National Ethics Committee of France. In accordance with local regulation, the plan and investigation documents were reviewed and received a favorable opinion from the Independent Ethics Committee on March 12, 2020. All procedures complied with the ethical guidelines established by the Declaration of Helsinki.
Declaration of patient consent:
The authors certify that they have obtained all appropriate patient consent.
Conflicts of interest:
Giovanni Salti, Gabriel Siquier-Dameto , and Dennis Malvin H. Malgapo have consultancy contracts with RELIFE S.r.l. Siham Rharbaoui is employed by Eurofins-Dermscan, a contract research organization that received funding from RELIFE S.r.l. to conduct this study. Silvia Innocenti serves as the medical director of RELIFE S.r.l. and Martina Manni is the global medical advisor of RELIFE S.r.l.
Use of artificial intelligence (AI)-assisted technology for manuscript preparation:
The authors confirm that they have used artificial intelligence (AI)-assisted technology for proofing of the manuscript.
Financial support and sponsorship: RELIFE S.r.l. provided an unrestricted educational grant for the conduct of the study and for writing the manuscript.
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