An Overview of Polycaprolactone (PCL) in Facial Bone Reconstruction
- Dr. Park
- Mar 25
- 5 min read
Hello, I am Dr. Park Jong-chul, a specialist in Oral and Maxillofacial Surgery. Various types of implant materials are used in facial bone restoration and reconstruction. Among them, I would like to provide a detailed overview of Polycaprolactone (PCL).
Implant Materials in Facial Bone Reconstruction and Characteristics of PCL
Materials used in facial bone reconstruction include non-absorbable materials that maintain their shape within the body, such as Bone Cement (PMMA), PEEK (Polyetheretherketone), Titanium, Goretex, Medpore, and Silicone. In contrast, PCL (Polycaprolactone) is generally known as a biodegradable, or absorbable, material.
Types of Commercialized PCL Implants and Guidance of Bone Formation
Commercially available PCL-based implants can be broadly categorized into two types:
Those made of pure PCL.
Those made by mixing pure PCL with other materials.
Among the latter, depending on the components mixed with PCL, they are further classified into:
PCL - β-TCP (Beta-tricalcium phosphate)
PCL - BGS 7
While PCL itself is a biodegradable material, it is not an osteoinductive material that promotes bone formation. Therefore, beta-TCP or BGS 7 are sometimes mixed with PCL to aid bone formation. However, it is difficult to consider that PCL - β-TCP or PCL - BGS 7 alone can lead to complete bone formation.
Characteristics and Clinical Considerations of PCL - β-TCP
PCL - β-TCP exhibits a degree of elastic deformation, which can help form a mechanical interlock, allowing the implant to be stably maintained within the body, especially in cases where there are minor irregularities around the reconstructed bone. There have been reports of bone formation without mixing autologous bone when reconstructing the middle part of the bone with intact bone on both sides.
However, it is not yet clearly confirmed whether PCL - β-TCP alone is sufficient for bone formation when reconstructing widely open areas. Therefore, the bone formation potential of PCL - β-TCP used alone requires further clinical reports, and currently, it is recommended to use it in conjunction with autologous bone.
Characteristics and Clinical Outcomes of PCL - BGS 7
PCL - BGS 7 was first released around August 2021, and there are reports of over 3 years of follow-up data on bone formation when used with autologous bone.
Research results indicate that the bone strength achieved after bone grafting using PCL - BGS 7 and autologous bone is strong enough to support dental implants.
According to a report by Professor Lee Ui-Lyong's research team in the Department of Oral and Maxillofacial Surgery at Chung-Ang University, reconstructing the alveolar bone using PCL and autologous bone and then placing implants resulted in excellent bone strength at the time of implant placement (ISQ 70 or higher), and the upper prostheses were successfully loaded and functioning.
Role of Bone Formation and PCL in the Field of Oral and Maxillofacial Surgery
Autologous bone generation is a widely used technique in the field of oral and maxillofacial surgery, and more broadly in dentistry. In dentistry, bone regeneration through Guided Bone Regeneration (GBR) is common when there is insufficient alveolar bone. This principle can be understood as being extended to facial bone areas such as the mandibular angle (jawline).
In other words, PCL can be used as one of the various barrier membranes for bone formation induction. One of its advantages over other barrier membranes is its rigidity, which allows for sufficient space maintenance for bone formation.
Notably, PCL is a representative example of a Shape Memory Polymer (SMP) or thermoplastic polymer, as it is hard at low temperatures and softens at high temperatures.
Considerations for Autologous Bone Reconstruction Using PCL
There are several factors to consider when performing autologous bone reconstruction using PCL.
Firstly, if a large amount of bone needs to be reconstructed, it may be necessary to harvest autologous bone from the hip bone (iliac crest),
which may inevitably cause discomfort in walking for a certain period. If the amount of reconstruction is small, autologous bone can be harvested from the mandibular ramus area in the mouth, in which case the bone harvesting does not significantly affect recovery.
The advantages and disadvantages of attempting additional surgery on other parts of the body for aesthetic rather than functional restoration require sufficient discussion between the medical team and the patient.
For those who are reluctant to undergo additional procedures, commercially available allografts are recommended.
Secondly, the fact that bone has been generated means that the area is living tissue and can respond to physiological changes. Therefore, through the physiological bone remodeling process, the autologous bone may adapt to the new physiological environment, potentially resulting in a slightly different appearance than originally planned. On the other hand, other non-absorbable implants are non-living inert materials, so their shape remains the same even within the human body.
Thirdly, although PCL is generally known to be resorbed by the body over time, it is not easy to accurately predict how quickly or to what extent this resorption will occur.
Consideration of PCL Absorbability: Possibility of Replacement with Soft Tissue
Although PCL is generally known as a biodegradable material, commercially available products are used not only as scaffolds for autologous bone generation but also as standalone implants, despite being a bioresorbable material.
If PCL were completely absorbed and disappeared within the body as generally understood, it would be difficult to use it alone. Conversely, if it remains, it contradicts the generally known characteristics of PCL.
Regarding this, an opinion has been proposed that PCL may not simply dissolve and disappear but rather be replaced by fibrous connective tissue. According to presentation materials from Professor Lee Jung-woo's research team in the Department of Oral and Maxillofacial Surgery at Kyung Hee University, clinical photographs show that the area reconstructed with PCL maintains its shape for several years.
J.-W. Long-Term Follow-Up of a
Novel Surgical Option Combining
Fibula Free Flap and 3D-Bioprinted,
Patient-Specific Polycaprolactone
(PCL) Implant for Mandible
Reconstruction. Bioengineering 2023,
10, 684. https://doi.org/10.3390/
bioengineering10060684
J.-W. Long-Term Follow-Up of a
Novel Surgical Option Combining
Fibula Free Flap and 3D-Bioprinted,
Patient-Specific Polycaprolactone
(PCL) Implant for Mandible
Reconstruction. Bioengineering 2023,
10, 684. https://doi.org/10.3390/
bioengineering10060684
J.-W. Long-Term Follow-Up of a
Novel Surgical Option Combining
Fibula Free Flap and 3D-Bioprinted,
Patient-Specific Polycaprolactone
(PCL) Implant for Mandible
Reconstruction. Bioengineering 2023,
10, 684. https://doi.org/10.3390/
bioengineering10060684
If the PCL had been absorbed and disappeared, the area should appear sunken. However, it is actually well-maintained. Professor Lee's team explains that this shape maintenance is likely due to PCL being replaced by soft tissue, adding that clear radiological evidence of complete replacement with bone during this period has not yet been confirmed.
When using PCL alone as an implant, it can help maintain volume. However, it is important to fully consider that the strength of the implant may weaken and deform over time when applied to areas that need to withstand load.
Conclusion
So far, we have explored PCL among the materials used for facial bone restoration and reconstruction, such as the cheekbones, jawline, and chin. PCL can play an effective role in bone regeneration when used in conjunction with autologous bone grafting. In particular, PCL - BGS 7 has shown clinical results of achieving bone strength sufficient for implant placement. However, further research and clinical observation are needed regarding the absorption and replacement process of PCL.
Thank you.
Polycaprolactone (PCL) in Facial Bone Reconstruction