A classification of cranial implants based on the degree of difficulty in computer design and manufacture

Breaking Barriers in Cranioplasty: 3D Printing in Low and Middle-Income Settings-Insights from Zenica, Bosnia and Herzegovina

Background and Objectives: Cranial defects pose significant challenges in low and middle-income countries (LIMCs), necessitating innovative and cost-effective craniofacial reconstruction strategies. The purpose of this study was to present the Bosnia and Herzegovina model, showcasing the potential of a multidisciplinary team and 3D-based technologies, particularly PMMA implants, to address cranial defects in a resource-limited setting. Materials and Methods: An observational, non-experimental prospective investigation involved three cases of cranioplasty at the Department of Neurosurgery, Cantonal Hospital Zenica, Bosnia and Herzegovina, between 2019 and 2023. The technical process included 3D imaging and modeling with MIMICS software (version 10.01), 3D printing of the prototype, mold construction and intraoperative modification for precise implant fitting. Results: The Bosnia and Herzegovina model demonstrated successful outcomes in cranioplasty, with PMMA implants proving cost-effective and efficient in addressing cranial defects. Intraoperative modification contributed to reduced costs and potential complications, while the multidisciplinary approach and 3D-based technologies facilitated accurate reconstruction. Conclusions: The Bosnia and Herzegovina model showcases a cost-effective and efficient approach for craniofacial reconstruction in LIMICs. Collaborative efforts, 3D-based technologies, and PMMA implants contribute to successful outcomes. Further research is needed to validate sustained benefits and enhance craniofacial reconstruction strategies in resource-constrained settings.

Can Steam Sterilization Affect the Accuracy of Point-of-Care 3D Printed Polyetheretherketone (PEEK) Customized Cranial Implants? An Investigative Analysis

Polyetheretherketone (PEEK) has become the biomaterial of choice for repairing craniofacial defects over time. Prospects for the point-of-care (POC) fabrication of PEEK customized implants have surfaced thanks to the developments in three-dimensional (3D) printing systems. Consequently, it has become essential to investigate the characteristics of these in-house fabricated implants so that they meet the necessary standards and eventually provide the intended clinical benefits. This study aimed to investigate the effects of the steam sterilization method on the dimensional accuracy of POC 3D-printed PEEK customized cranial implants. The objective was to assess the influence of standard sterilization procedures on material extrusion-based 3D-printed PEEK customized implants with non-destructive material testing. Fifteen PEEK customized cranial implants were fabricated using an in-house material extrusion-based 3D printer. After fabrication, the cranial implants were digitalized with a professional-grade optical scanner before and after sterilization. The dimensional changes for the 3D-printed PEEK cranial implants were analyzed using medically certified 3D image-based engineering software. The material extrusion 3D-printed PEEK customized cranial implants displayed no statistically significant dimensional difference with steam sterilization (p > 0.05). Evaluation of the cranial implants’ accuracy revealed that the dimensions were within the clinically acceptable accuracy level with deviations under 1.00 mm. Steam sterilization does not significantly alter the dimensional accuracy of the in-house 3D-printed PEEK customized cranial implants.

Quantitative Assessment of Point-of-Care 3D-Printed Patient-Specific Polyetheretherketone (PEEK) Cranial Implants

Recent advancements in medical imaging, virtual surgical planning (VSP), and three-dimensional (3D) printing have potentially changed how today's craniomaxillofacial surgeons use patient information for customized treatments. Over the years, polyetheretherketone (PEEK) has emerged as the biomaterial of choice to reconstruct craniofacial defects. With advancements in additive manufacturing (AM) systems, prospects for the point-of-care (POC) 3D printing of PEEK patient-specific implants (PSIs) have emerged. Consequently, investigating the clinical reliability of POC-manufactured PEEK implants has become a necessary endeavor. Therefore, this paper aims to provide a quantitative assessment of POC-manufactured, 3D-printed PEEK PSIs for cranial reconstruction through characterization of the geometrical, morphological, and biomechanical aspects of the in-hospital 3D-printed PEEK cranial implants. The study results revealed that the printed customized cranial implants had high dimensional accuracy and repeatability, displaying clinically acceptable morphologic similarity concerning fit and contours continuity. From a biomechanical standpoint, it was noticed that the tested implants had variable peak load values with discrete fracture patterns and failed at a mean (SD) peak load of 798.38 ± 211.45 N. In conclusion, the results of this preclinical study are in line with cranial implant expectations; however, specific attributes have scope for further improvements.

Structure, properties, and bioactivity of 3D printed PAEKs for implant applications: A systematic review

Additive manufacturing (AM) of high temperature polymers, specifically polyaryletherketones (PAEK), is gaining significant attention for medical implant applications. As 3D printing systems evolve toward point of care manufacturing, research on this topic continues to expand. Specific regulatory guidance is being developed for the safe management of 3D printing systems in a hospital environment. PAEK implants can benefit from many advantages of AM such as design freedom, material and antibacterial drug incorporation, and enhanced bioactivity provided by cancellous bone-like porous designs. In addition to AM PAEK bioactivity, the biomechanical strength of 3D printed implants is crucial to their performance and thus widely studied. In this review, we discuss the printing conditions that have been investigated so far for additively manufactured PAEK implant applications. The effect of processing parameters on the biomechanical strength of implants is summarized, and the bioactivity of PAEKs, along with material and drug incorporation, is also covered in detail. Finally, the therapeutic areas in which 3D printed PAEK implants are investigated and utilized are reviewed.

3D-Printer-Assisted Patient-Specific Polymethyl Methacrylate Cranioplasty: A Case Series of 16 Consecutive Patients

BACKGROUND

To develop a novel 3D-printer-assisted method to fabricate patient-specific implants for cranioplasty and to demonstrate its feasibility and its use in 16 consecutive cases.

METHODS

We report on 16 consecutive patients who have undergone cranioplasty surgery for an extensive skull defect after decompressive surgery and in which the bone flap was not available. We present the workflow for the implant production using a 3D-printer-assisted molding technique. Preoperative, intraoperative, and postoperative data were analyzed/evaluated.

RESULTS

Eleven out of our 16 patients (68.7%) presented with extensive hemispheric bone defects. Indication for initial craniotomy were traumatic brain injury (4; 25%), acute subdural hematoma (4; 25%), ischemic stroke (3; 18.8%), tumor (3; 18.8%), and ruptured aneurysm (2; 12.5%). Median (range) operation time was 121 (89-206) minutes. Median (range) intraoperative blood loss was 300 (100-3300) mL. The mean (range) follow-up period is 6 (0-21) months. Complications occurred in 7 out of our 16 patients (43.8%), in 6 (37.5%) of which a reoperation was required to evacuate an extra-axial hematoma (3; 50%), for shunting of an epidural fluid collection (1; 16.7%), or for skin flap necrosis (1; 16.7%). One patient (16.7%) developed a chronic asymptomatic subdural fluid collection that was stable over the follow-up period.

CONCLUSIONS

Our workflow to intraoperatively produce patient-specific implants in a timely manner to cover cranial defects proved to be feasible. The results are cosmetically appealing, and postoperative CT scans show well-fitting implants. As implantable printable substrates are already available, we aim to advance and certify 3D-printed patient-specific implants in the near future.

Selective Laser Melting of Patient Individualized Osteosynthesis Plates-Digital to Physical Process Chain

We report on the exemplified realization of a digital to physical process chain for a patient individualized osteosynthesis plate for the tarsal bone area. Anonymized patient-specific data of the right feet were captured by computer tomography, which were then digitally processed to generate a surface file format (standard tessellation language, STL) ready for additive manufacturing. Physical realization by selective laser melting in titanium using optimized parameter settings and post-processing by stress relief annealing results in a customized osteosynthesis plate with superior properties fulfilling medical demands. High fitting accuracy was demonstrated by applying the osteosynthesis plate to an equally good 3D printed bone model, which likewise was generated using the patient-specific computer tomography (CT) data employing selective laser sintering and polyamid 12. Proper fixation has been achieved without any further manipulation of the plate using standard screws, proving that based on CT data, individualized implants well adapted to the anatomical conditions can be accomplished without the need for additional steps, such as bending, cutting and shape trimming of precast bone plates during the surgical intervention. Beyond parameter optimization for selective laser melting, this exemplified digital to physical process chain highlights the potential of additive manufacturing for individualized osteosynthesis.

Quality Characteristics and Clinical Relevance of In-House 3D-Printed Customized Polyetheretherketone (PEEK) Implants for Craniofacial Reconstruction

Additive manufacturing (AM) of patient-specific implants (PSIs) is gradually moving towards in-house or point-of-care (POC) manufacturing. Polyetheretherketone (PEEK) has been used in cranioplasty cases as a reliable alternative to other alloplastic materials. As only a few fused filament fabrication (FFF) printers are suitable for in-house manufacturing, the quality characteristics of the implants fabricated by FFF technology are still under investigated. This paper aimed to investigate PEEK PSIs fabricated in-house for craniofacial reconstruction, discussing the key challenges during the FFF printing process. Two exemplary cases of class III (Group 1) and class IV (Group 2) craniofacial defects were selected for the fabrication of PEEK PSIs. Taguchi’s L9 orthogonal array was selected for the following nonthermal printing process parameters, i.e., layer thickness, infill rate, number of shells, and infill pattern, and an assessment of the dimensional accuracy of the fabricated implants was made. The root mean square (RMS) values revealed higher deviations in Group 1 PSIs (0.790 mm) compared to Group 2 PSIs (0.241 mm). Horizontal lines, or the characteristic FFF stair-stepping effect, were more perceptible across the surface of Group 1 PSIs. Although Group 2 PSIs revealed no discoloration, Group 1 PSIs displayed different zones of crystallinity. These results suggest that the dimensional accuracy of PSIs were within the clinically acceptable range; however, attention must be paid towards a requirement of optimum thermal management during the printing process to fabricate implants of uniform crystallinity.

Cumulative Inaccuracies in Implementation of Additive Manufacturing Through Medical Imaging, 3D Thresholding, and 3D Modeling: A Case Study for an End-Use Implant

In craniomaxillofacial surgical procedures, an emerging practice adopts the preoperative virtual planning that uses medical imaging (computed tomography), 3D thresholding (segmentation), 3D modeling (digital design), and additive manufacturing (3D printing) for the procurement of an end-use implant. The objective of this case study was to evaluate the cumulative spatial inaccuracies arising from each step of the process chain when various computed tomography protocols and thresholding values were independently changed. A custom-made quality assurance instrument (Phantom) was used to evaluate the medical imaging error. A sus domesticus (domestic pig) head was analyzed to determine the 3D thresholding error. The 3D modeling error was estimated from the computer-aided design software. Finally, the end-use implant was used to evaluate the additive manufacturing error. The results were verified using accurate measurement instruments and techniques. A worst-case cumulative error of 1.7 mm (3.0%) was estimated for one boundary condition and 2.3 mm (4.1%) for two boundary conditions considering the maximum length (56.9 mm) of the end-use implant. Uncertainty from the clinical imaging to the end-use implant was 0.8 mm (1.4%). This study helps practitioners establish and corroborate surgical practices that are within the bounds of an appropriate accuracy for clinical treatment and restoration.

Computer-Aided-Design/Computer-Aided-Manufacturing Titanium Cranioplasty in a Child: Critical Appraisal

Large skull bone defects of the cranial vault can result from various reasons. Reconstruction of these defects is performed for protective and aesthetic reasons but is also required for adequate intracranial homeostasis. Computer-aided-design/computer-aided-manufacturing (CAD/CAM) patient-specific skull implants have become the most valuable alternative to the traditional methods of reconstruction and a growing number of publications is dealing with this topic in adults. Literature related to the application of these implants in pediatric cranioplasty is, however, still scarce.The authors present a case of a 9-year-old boy, where cranioplasty using a CAD/CAM additive manufactured titanium implant led to improvement of symptoms attributed to cerebrospinal fluid circulation problems and intracranial homeostasis disbalance. The authors further reflect on what the role of cranioplasty should be in the therapeutic treatment plan.

Polymethyl Methacrylate in Patient-Specific Implants: Description of a New Three-Dimension Technique

Polymethyl methacrylate (PMMA), an easily moldable and economical synthetic resin, has been used since the 1940s. In addition, PMMA has good mechanical properties and is one of the most biocompatible alloplastic materials currently available. The PMMA can serve as a spacer and as a delivery vehicle for antibiotics. Prior studies have indicated that no significant differences in infection rates exist between autologous and acrylic cranioplasty. Although inexpensive, the free-hand cranioplasty technique often yields unsatisfactory cosmetic results. In the present study, the application of a recently developed, economic modality for the perioperative application, and molding of PMMA to ensure a precise fit in 16 patients using computer-aided design, computer-aided manufacturing, and rapid prototyping was described.The mean defect size was 102.0 ± 26.4 cm. The mean volume of PMMA required to perform the cranioplasty procedure was 51 mL. The cost of PMMA was approximately 6 Euro (&OV0556;) per mL. The costs of fabricating the implants varied from 119.8 &OV0556; to 1632.0 &OV0556; with a mean of 326.4 &OV0556; ± 371.6. None of the implants required removal during the follow-up period.

Additively manufactured versus conventionally pressed cranioplasty implants: An accuracy comparison

This article compared the accuracy of producing patient-specific cranioplasty implants using four different approaches. Benchmark geometry was designed to represent a cranium and a defect added simulating a craniectomy. An ‘ideal’ contour reconstruction was calculated and compared against reconstructions resulting from the four approaches –‘conventional’, ‘semi-digital’, ‘digital – non-automated’ and ‘digital – semi-automated’. The ‘conventional’ approach relied on hand carving a reconstruction, turning this into a press tool, and pressing titanium sheet. This approach is common in the UK National Health Service. The ‘semi-digital’ approach removed the hand-carving element. Both of the ‘digital’ approaches utilised additive manufacturing to produce the end-use implant. The geometries were designed using a non-specialised computer-aided design software and a semi-automated cranioplasty implant-specific computer-aided design software. It was found that all plates were clinically acceptable and that the digitally designed and additive manufacturing plates were as accurate as the conventional implants. There were no significant differences between the additive manufacturing plates designed using non-specialised computer-aided design software and those designed using the semi-automated tool. The semi-automated software and additive manufacturing production process were capable of producing cranioplasty implants of similar accuracy to multi-purpose software and additive manufacturing, and both were more accurate than handmade implants. The difference was not of clinical significance, demonstrating that the accuracy of additive manufacturing cranioplasty implants meets current best practice.

In vitro cytotoxicity and surface topography evaluation of additive manufacturing titanium implant materials

Custom-designed patient-specific implants and reconstruction plates are to date commonly manufactured using two different additive manufacturing (AM) technologies: direct metal laser sintering (DMLS) and electron beam melting (EBM). The purpose of this investigation was to characterize the surface structure and to assess the cytotoxicity of titanium alloys processed using DMLS and EBM technologies as the existing information on these issues is scarce. "Processed" and "polished" DMLS and EBM disks were assessed. Microscopic examination revealed titanium alloy particles and surface flaws on the processed materials. These surface flaws were subsequently removed by polishing. Surface roughness of EBM processed titanium was higher than that of DMLS processed. The cytotoxicity results of the DMLS and EBM discs were compared with a "gold standard" commercially available titanium mandible reconstruction plate. The mean cell viability for all discs was 82.6% (range, 77.4 to 89.7) and 83.3% for the control reconstruction plate. The DMLS and EBM manufactured titanium plates were non-cytotoxic both in "processed" and in "polished" forms.

Three-dimensional printing for restoration of the donor face: A new digital technique tested and used in the first facial allotransplantation patient in Finland

BACKGROUND AND AIMS

Prosthetic mask restoration of the donor face is essential in current facial transplant protocols. The aim was to develop a new three-dimensional (3D) printing (additive manufacturing; AM) process for the production of a donor face mask that fulfilled the requirements for facial restoration after facial harvest.

MATERIALS AND METHODS

A digital image of a single test person's face was obtained in a standardized setting and subjected to three different image processing techniques. These data were used for the 3D modeling and printing of a donor face mask. The process was also tested in a cadaver setting and ultimately used clinically in a donor patient after facial allograft harvest.

RESULTS

and Conclusions: All the three developed and tested techniques enabled the 3D printing of a custom-made face mask in a timely manner that is almost an exact replica of the donor patient's face. This technique was successfully used in a facial allotransplantation donor patient.

Interval cranioplasty with patient-specific implants and autogenous bone grafts--success and cost analysis

Different options exist for the reconstruction of craniectomy defects following interval cranioplasty. The standard procedure is still based on the re-implantation of autogenous bone specimen which can be stored in the abdominal wall or be cryopreserved. Alternatively patient-specific implants (PSIs) can be used. We conducted a retrospective study based on 50 consecutive patients with skull bone defects of 100 cm(2) or more being operated on by the same team of surgeons. Thirty-three patients agreed to take part in the study. Seventeen patients who underwent reconstruction with PSIs (titanium and polyether ether ketone, PEEK) (follow-up, 43 months [range, 3-93]) were compared with 16 control subjects who had autogenous bone grafts re-implanted (follow-up, 32 months [range, 5-92]). Criteria analyzed were the success and complication rates, operation time, duration of hospitalization and the treatment costs. Complication rate and the rate of reoperation were significantly lower, and the hospital stay was shorter in the PSI group. The treatment costs for reconstruction with autogenous bone were considerably lower than skull bone reconstruction based on PSIs (average costs: 10849.91 €/patient versus 15532.08 €/patient with PSI). Due to biological reasons some of the autogenous bone implants fail due to infection and resorption and the patients have to undergo another operation with implantation of a PSI in a secondary attempt. For those patients the highest overall treatment costs must be calculated (average costs: 26086.06 €/patient with secondary stage PSI versus 15532.08 €/patient with primary stage PSI).

CONCLUSION

High success rates and reliability of PSIs may change the treatment strategy in patients undergoing interval cranioplasty.

A Novel Classification and Online Platform for Planning and Documentation of Medical Applications of Additive Manufacturing

Additive manufacturing technologies are widely used in industrial settings and now increasingly also in several areas of medicine. Various techniques and numerous types of materials are used for these applications. There is a clear need to unify and harmonize the patterns of their use worldwide. We present a 5-class system to aid planning of these applications and related scientific work as well as communication between various actors involved in this field. An online, matrix-based platform and a database were developed for planning and documentation of various solutions. This platform will help the medical community to structurally develop both research innovations and clinical applications of additive manufacturing. The online platform can be accessed through http://www.medicalam.info .

Inaccuracies in additive manufactured medical skull models caused by the DICOM to STL conversion process

INTRODUCTION

The process of fabricating physical medical skull models requires many steps, each of which is a potential source of geometric error. The aim of this study was to demonstrate inaccuracies and differences caused by DICOM to STL conversion in additively manufactured medical skull models.

MATERIAL AND METHODS

Three different institutes were requested to perform an automatic reconstruction from an identical DICOM data set of a patients undergoing tumour surgery into an STL file format using their software of preference. The acquired digitized STL data sets were assessed and compared and subsequently used to fabricate physical medical skull models. The three fabricated skull models were then scanned, and differences in the model geometries were assessed using established CAD inspection software methods.

RESULTS

A large variation was noted in size and anatomical geometries of the three physical skull models fabricated from an identical (or "a single") DICOM data set.

CONCLUSIONS

A medical skull model of the same individual can vary markedly depending on the DICOM to STL conversion software and the technical parameters used. Clinicians should be aware of this inaccuracy in certain applications.

Craniofacial bone reconstruction with bioactive fiber-reinforced composite implant

BACKGROUND

A novel, bioactive, fiber-reinforced composite implant is a solution to address the shortcomings in craniofacial bone reconstruction. A longitudinal clinical investigation with a follow-up time of 4 years was conducted.

METHODS

A cranial bone reconstruction with the implant was performed on 12 patients. In these patients, the reasons for craniotomies resulting in craniofacial bone defects were traumatic and spontaneous intracranial bleeding as well as infections to the primary reconstruction material. The implant material consisted of a supporting fiber-reinforced framework, porous inner layers, and a bioactive glass (BG; S53P4) filling. The framework and the porous layers were made of a bisphenol-a-glycidyl methacrylate and triethyleneglycoldi-methacrylate (pBisGMA-pTEGDMA) resin matrix, which was reinforced with silanized E-glass.

RESULTS

In clinical examinations and skull X-rays, the implants were in original positions providing the expected functional and aesthetic outcome at all time points.

CONCLUSION

The implants functioned appropriately, which would provide a potential solution for craniofacial bone reconstruction in the future.

A digital process for additive manufacturing of occlusal splints: a clinical pilot study

The aim of this study was to develop and evaluate a digital process for manufacturing of occlusal splints. An alginate impression was taken from the upper and lower jaws of a patient with temporomandibular disorder owing to cross bite and wear of the teeth, and then digitized using a table laser scanner. The scanned model was repaired using the 3Data Expert software, and a splint was designed with the Viscam RP software. A splint was manufactured from a biocompatible liquid photopolymer by stereolithography. The system employed in the process was SLA 350. The splint was worn nightly for six months. The patient adapted to the splint well and found it comfortable to use. The splint relieved tension in the patient's bite muscles. No sign of tooth wear or significant splint wear was detected after six months of testing. Modern digital technology enables us to manufacture clinically functional occlusal splints, which might reduce costs, dental technician working time and chair-side time. Maximum-dimensional errors of approximately 1 mm were found at thin walls and sharp corners of the splint when compared with the digital model.

Skull vault destruction after rhinocerebral mucormycosis

BACKGROUND

Mucormycosis is a relatively rare form of fungal infection that can be rapidly progressive. Clinical presentation depends on the anatomic area of involvement; however, the commonest form is that of rhinocerebral.

CASE DESCRIPTION

This is the first case of extensive and progressive destruction of the skull vault despite antifungal therapy. The patient required aggressive surgical resection to arrest the disease progression and complex reconstruction using a custom made titanium cranioplasty.

CONCLUSIONS

This report highlights the need for early aggressive resection for cases of mucormycosis infection where there is bony involvement.

Simultaneous repair of two large cranial defects using rapid prototyping and custom computer-designed titanium plates: a case report

Custom titanium cranioplasty plates, manufactured by a variety of techniques, have been used to repair a range of cranial defects. The authors present a case where two relatively large, adjacent cranial defects were repaired by custom computer-designed titanium plates. The two plates were designed and fabricated simultaneously using a unique methodology. A 28-year-old woman underwent a corpus callosotomy for medically intractable epilepsy. The surgery was complicated by unexpected haemorrhage which necessitated a second craniotomy. Subsequent deep infection required the removal of bilateral bone flaps, presenting a challenge in the reconstruction of extensive, bilateral but asymmetrical cranial defects. The patient underwent a head computed tomography scan, from which a rapid-prototype model of the skull was produced. The surfaces for the missing cranial segments were generated virtually using a combination of software products and two titanium plates that followed these virtual contours were manufactured to cover the defects. The cranioplasty procedure to implant both titanium cranial plates was performed efficiently with no intra-operative complications. Intra-operatively, an excellent fit was achieved. The careful planning of the plates enhanced the relative ease with which the cranial defects were repaired with an excellent cosmetic outcome.

Bone reservoir: Injectable hyaluronic acid hydrogel for minimal invasive bone augmentation

A strategy has been designed to develop hyaluronic acid (HA) hydrogel for in vivo bone augmentation using minimal invasive technique. A mild synthetic procedure was developed to prepare aldehyde modified HA by incorporating an amino-glycerol side chain via amidation reaction and selective oxidation of the pendent group. This modification, upon mixing with hydrazide modified HA formed hydrazone-crosslinked hydrogel within 30s that was stable at physiological pH. In vitro experiments showed no cytotoxicity of hydrogel with the controlled release of active bone morphogenic protein-2 (BMP-2). In vivo evaluation of this gel as a BMP-2 carrier was performed by injecting gels over the rat calvarium and showed bone formation in 8 weeks in correlation with the amount of BMP-2 loaded (0, 1 and 30μg) within the gel. Furthermore, hydrogels with 30μg of BMP-2 induced less bone formation upon subcutaneous injection in comparison with subperiosteal implantation. Histological examination showed newly formed bone with a high expression of osteocalcin, osteopontin and with angiogenic bone marrow when higher BMP-2 concentration was employed. Our result suggests that novel HA hydrogels could be used as a BMP-2 carrier and can promote bone augmentation for potential orthopedic applications.

A treatment algorithm for patients with large skull bone defects and first results

Large skull bone defects resulting from craniotomies due to cerebral insults, trauma or tumours create functional and aesthetic disturbances to the patient. The reconstruction of large osseous defects is still challenging. A treatment algorithm is presented based on the close interaction of radiologists, computer engineers and cranio-maxillofacial surgeons. From 2004 until today twelve consecutive patients have been operated on successfully according to this treatment plan. Titanium and polyetheretherketone (PEEK) were used to manufacture the implants. The treatment algorithm is proved to be reliable. No corrections had to be performed either to the skull bone or to the implant. Short operations and hospitalization periods are essential prerequisites for treatment success and justify the high expenses.

Static and dynamic periosteal elevation: a pilot study in a pig model

The osteoinductive potential of periosteum and bone can be stimulated by elevating the periosteum in a distraction-like modus, but also by an ad-hoc elevation. This was tested and proved in an experiment in 9 Goettingen mini-pigs with elevation heights of 5, 10 and 15mm. Specially designed and perforated titanium meshes were implanted subperiosteally to compare the dynamic elevation procedure with static shielding. The cumulative results for bone formation underneath the mesh were 66% in dynamic and 67% in non-dynamic elevation. The cumulative results for mineralization of the bone regenerates in comparison with the underlying basal bone of the skull showed independently from the technique applied no difference bigger than 5%. No major difference in bone formation could be observed in this pilot study. The main advantages of dynamic periosteal elevation and static shielding are minimal invasion and morbidity. Periosteal elevation could be applied in cranio-maxillofacial surgery, in preimplantological augmentation and in reconstructive surgery of the skull; applications in other specialties may be possible.