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Objective: The purpose of this paper is to report the use of custom implants as an esthetic correction method for craniofacial defects.
Materials and methods: The case series introduced in this paper corresponds to three patients, which have craniofacial congenital malformations. The defects were corrected using PoreStar (Anatomics Pvt. Ltd. Wellington street St. Kilda, Australia) custom implants.
Results: The craniofacial implants adapted and integrated themselves optimally to the patients. None of them exhibited failures during the research study and follow-up period, showing a 100% survival rate. The esthetic results and acceptance by the patient were very satisfactory.
Conclusion: The custom implants accomplish optimal esthetic results regarding the handling of craniofacial defects, facilitating the unique and specific reconstruction of human characteristics.
Keywords: Implants, Craniofacial defects, Esthetics
The complex esthetic and functional consequences that craniofacial defects generate require planning reconstruction and an ideal selection of materials for their restoration . Congenital malformations, defects due to tumor ablation and sequels of trauma are the main causes of these defects. The complex anatomy of the malar region turns this facial region into one of the most vulnerable. Since after altering its natural position, esthetic deficiencies are produce in its projection and the shape and function of the eyeball is compromised . Likewise, it produces in the patient a severe emotional burden that justifies the integral rehabilitation of these defects .
The autologous grafts for the reconstruction of craniofacial defects are considered as the first option for reconstruction, however, the need for a donor site and the additional surgical interventions, limit their use . The extension of the defect, the anatomical characteristics of the zone that will be operated and the presence of vital structures near the affected area, highlight the importance of using custom prostheses that can work with these requirements, restoring the esthetic and function in accordance with the requirements of each patient [4,5]. Alloplastic implants are an efficient option for the reconstruction of craniofacial defects, since their high predictability and surgical stability allows decreasing the operation times and improves the defect’s reconstruction capacity .
The craniofacial implants are medical devices manufactured to replace/reconstruct an absent biological structure, a damaged structure or improve an existing structure . These materials must be compatible, easy to manipulate, resistant to infection and allow an easy extraction-insertion. Some of the materials used for these implants are high-density-porous-polyethylene (HDPP), expanded-poli-tetrafluoroethylene (ePTFE), polyether-ether-ketone (PEEK), methyl-methacrylate, silicone, bio-ceramic/bio-glass, etc. [6,7].
The purpose of this paper is to report the use of PoreStar (Anatomics Pvt. Ltd. Wellington street St. Kilda, Australia) custom implants as an esthetic correction method for cranio-facial defects.
MATERIALS AND METHODS
The case series corresponds to patients with craniofacial defects who were subjected to surgical interventions to place custom implants (personalized) made with alloplastic materials. The patients had facial congenital malformations and an acceptable health status. Eight high-density porous polyethylene (HDPP) PoreStar (Anatomics Pvt. Ltd. Wellington street St. Kilda, Australia) implants were placed on three patients.
The patients included in the research study exhibited congenital craniofacial defects and an ASA I or ASA II classification per the American society of anesthesiologists 2014: physical status classification system. The patients excluded from the research study were patients that exhibited craniofacial defects associated to trauma consequences or tumor ablation. Besides this, they also had an ASA III or higher classification per the American society of anesthesiologists 2014: physical status classification system.
This research study was conducted in accordance with the Declaration of Helsinki and was approved by the researchers from the ethics committee from the corresponding service. Patient release form was obtained from all the patients included in this research study.
The initial evaluation was conducted using a CT scan from the face with high-resolution specifications and minimal distance cuts between corresponding images at 0.5 mm of spacing, under the strict imaging calibration from the PoreStar (Anatomics Pvt. Ltd. Wellington street St. Kilda, Australia) implants protocol. The craniofacial three-dimensional reconstruction was obtained through stereolithographic models and the alloplastic implants were custom designed in the models. The virtual assistance conducted jointly with biomedical engineers from the parent company allowed to fully comply with the specific technical requirements of each patient. The three patients were treated at the Simon Bolivar Hospital (Bogota, Colombia).
The surgical bio-model with the custom implants in place was sterilized. Before placing the implants, they were submersed in a dilution of 500 ml of SSN 0.9%/2 g cefazolin. Subsequent conventional approaches were conducted and the implants were placed. The fixation of the implant had a minimum of two screws (medial and lateral). The implant considered successful when the 12 months post-implant period ended without producing associated adverse events.
Male patient, thirty years old, diagnosed with Treacher Collins syndrome. Exhibits marked deficiency on the projection frontal, temporal and bilateral malar (Figures 1A-1C). Additionally, the patient exhibits class II malocclusion with severe micrognathism and sequels of facial esthetic surgery done to correct bilateral microtia. For the correction of the craniofacial defects the following were conducted: osteogenic mandibular distraction, functional septum-rhinoplasty and camouflage through custom implants in the frontal-temporal and bilateral malar region. The simultaneous facial-cranial approach as camouflage for congenital defects is poorly referenced in the literature.
The planning begins by three-dimensionally reconstructing the defects that appear in the CT, choosing the ideal position and contour of the implants (Figure 2). The stereolithographic model shows the custom implants in the frontal-temporal region and bilateral malar in place (Figure 3). Subsequently a vestibular approach was made with sub periosteal exposition of the malar region. The implants were adjusted and fixed in the ideal position (Figures 4A-4C). Follow-up of 2 years 3 months without complications (Figures 5A-5C). The esthetic improvement in the frontal, temporal and malar projection and contour optimally camouflages the defects. Additionally, the esthetic correction through osteogenic mandibular distraction and functional septum-rhinoplasty (Figures 6A and 6B) in the patient facilitated the acceptance of the defects, significantly improving his quality of life.
Male patient, nineteen years old, who exhibits craniofacial defects consistent with microtia and left malar hypoplasia. To correct the craniofacial defects, the following were conducted: surgical placing of prosthesis for the auricular left pinna through the epiplating system (Medicon. Tuttlingen, Germany Company) (Figures 7A and 7B) and camouflage through a custom implant in the left malar region.
The stereolithographic model shows the custom implant in the left malar region (Figure 8A). A conventional approach was implemented in the back of the vestibule with a sub periosteal exposure of the left malar region, the implant was adjusted and fixed in the ideal position (Figure 8B). Follow-up of 1 year and 8 months without complications (Figures 9A and 9B). The esthetic improvement in the malar projection and contour camouflages the defect optimally. Additionally, the esthetic prosthesis complements the integral handling of the patient.
Female patient, thirty-three years old, who exhibits surgical sequels due to the congenital alteration of cleft palate and lip. Exhibits marked deficiency in the malar projection and contour bilaterally (Figures 10A and 10B). Additionally, the patient exhibits strabismus, class III malocclusion with maxilla hypoplasia, speech disorder (severe hypernasality) and proportion and volume nasal defect. The craniofacial defects were corrected through bilateral sagittal split osteotomy and chin surgery. The camouflage option by means of the placing of paranasal and malar custom implants was determined through a consensus with the patient and the surgical team to avoid further disruptions in speech. Besides, the poor bone quality and the remaining bone defects hampered the proper completion of the maxilla osteotomy procedure.
The adaptation of the craniofacial implants significantly improved the esthetic of the operated patients. The eight adjusted and adapted implants placed to correct the craniofacial defects showed a success rate of one year over with an implant placing of 100%. The camouflage obtained in the 3 patients was physically and mentally tolerated in a satisfactory manner.
The reconstruction of the craniofacial defects represents a great challenge for the physician , who must remember and implement the general facial analysis, and in specific cases, local specific layouts (for example, the malar zone) . The choice of the ideal reconstruction material may be confusing, since the range of available materials is extensive (poli-tetrafluoroethylene, methyl-methacrylate, HDPP, PEEK, silicone, etc.) . The senior author and other clinicians prefer custom alloplastic implants made of porous polyethylene [11,12] silicone  or PEEK based on patient specific implants . However, despite the morbidity of the donor site and rate of resorption, other authors prefer fatty autologous grafts [15,16] or hyaluronic acid fillers that avoid a donor site and it is analogous to fat transfer techniques for deeper volumetric adjustment .
The HDPP implants (PoreStar, Anatomics Pvt. Ltd. Wellington street St. Kilda, Australia – Medpor, porex surgical Inc., College Park, GA) have the advantage of biological integration to the recipient site. The collagen deposits form a highly stable compound that will resist infectious processes, undesired exposures to the material or malformation due to contractile forces . The preference of different authors [3,9,12,18] because of their mechanical and biological capacity justifies their use. On the other hand, silicone implants (Silastic implant Tech, Ventura, CA), have the advantage of biological encapsulation in the recipient site, facilitating their adjustment and possibility of easy removal when needed, dissenting on the use of HDPP implants . Currently, 3D planning facilitates the planning and execution of reconstructions in a custom manner, allowing obtaining more predictable results with minimal morbidity [19,20].
Atherton et al. in 2014  describe the usefulness of malar and paranasal implants related to reconstructions of midfacial and malar hypoplasia defects in patients with history of cleft lip and cleft palate, similar to the case introduced in this paper, where the osteogenic distraction and orthognathic surgery were not viable treatment options. Likewise, they describe their use in situations, where despite acceptable esthetic results, the craniofacial contours are compromised.
The handling of craniofacial deformities through the combination of camouflage techniques and esthetic-functional procedures allows the appropriate correction and integral rehabilitation of the different defects found in these patients. Barreto et al. in 2019  conducted the correction of auricular defects through the auricular epiplating prothesis system (Medicon. Tuttlingen, Germany Company). Likewise, the authors conducted osteogenic distraction surgeries and functional septum-rhinoplasty surgeries using PoreStar implants (Anatomics Pvt. Ltd. Wellington street St. Kilda, Australia) as a protocol for integral craniofacial rehabilitation with optimal esthetic results.
In accordance with Robiony et al. in 1998 , who simultaneously conducted orthognathic surgeries and implant placing in the malar region for the correction of craniofacial defects, in our cases we opted for camouflage interventions that improved the esthetic, without compromising the function of the patient. In a similar manner as the one exposed in case three, Robiony et al. , specify cases where large maxilla advances or movements with poor predictability can be replaced by esthetic camouflages with custom implants.
The complications associated to facial implants are around 31.5%, mainly related to esthetic (dissatisfaction of 10.1% due to asymmetry or implant migration) and infection of the operated place (7.2%) . Other minor complications that may emerge are swelling, ecchymosis, implant malposition, bone resorption, external implant palpation and asymmetry . There were not complications in our cases. The intraoral conventional surgical technique used by the author and in accordance with Atherton et al. 2014 , only exhibits a 0.5% of complications related to infection. Although the periorbital approaches provide a direct vision, they also increase the probability of complications (ectropion, epiphora, infraorbital neurapraxia, etc.) .
The greatest questions the surgeon has are, which implant to use and where to place it. The appropriate implant should be the one with the correct specifications . The esthetic and functional rehabilitation of the craniofacial defects represents a great challenge for the surgeon. The autografts and allografts used for many years implied an increase in the morbidity of the patients and the completion of an optimal functional and esthetic rehabilitation was very unpredictable. The rehabilitation through alloplastic substitutes accomplishes an ideal esthetic camouflage difficult to obtain through other methods . The use of custom implants not only allows camouflaging the esthetic defect, but it also facilitates the acceptance due to psychogenic self-perception, which generates an improvement in the quality of life of the patient and in their immediate social surroundings .
The handling of patients with different craniofacial pathologies (Treacher Collins syndrome, cleft lip and palate, etc.) who exhibit extreme anatomical conditions can be treated with optimal esthetic results and minimal morbidity. Custom HDPP implants accomplish optimal esthetic results in the handling of craniofacial defects, facilitating the unique and specific reconstruction of human characteristics.
Carlos E Buitrago, DDS, who provided excellent feedbacks to the article.
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