Use of a 3-Dimensional Custom-Made Porous Titanium Prosthesis for Mandibular Body Reconstruction With Prosthetic Dental Rehabilitation and Lipofilling

The use of customized 3D-printed mandibular prostheses with pressure-reducing device: A clinical trial

BACKGROUND

Segmental bone defects of the mandible result in the complete loss of the affected region. We had incorporated the pressure-reducing device (PRD) designs into the customized mandible prostheses (CMP) and conducted a clinical trial to evaluate this approach.

METHODS

Seven patients were enrolled in this study. We examined the association among the history of radiotherapy, the number of CMP regions, the number of chin regions involved, and CMP exposure.

RESULTS

We included five men and two women with an average age of 55 years. We excised tumors with an average weight of 147.8 g and the average weight of the CMP was 68.5 g. No significant difference between the two weights was noted (p = 0.3882). Three patients received temporary dentures and the CMP remained stable in all patients.

CONCLUSION

The use of PRD in CMP may address the previous challenges associated with CMP, but further research is necessary.

Use of customized 3-dimensional printed mandibular prostheses with a dental implant pressure-reducing device in mandibular body defect: A finite element study performing multiresponse surface methodology

Background/purpose

Segmental body defects of the mandible result in the complete loss of the affected region. In our previous study, we investigated the clinical applicability of a customized mandible prosthesis (CMP) with a pressure-reducing device (PRD) in an animal study. In this study, we further incorporated dental implants into the CMP and explored the use of dental implant PRD (iPRD) designs.

Materials and methods

By employing a finite element analysis approach, we created 4 types of CMP: CMP, CMP with iPRD, CMP-PRD, and CMP-PRD with iPRD. We developed 2 parameters for the iPRD: cone length (CL) in the upper part and spring pitch (SP) in the lower part. Using the response surface methodology (RSM), we determined the most suitable structural assignment for the iPRD.

Results

Our results indicate that CMP-PRD had the highest von Mises stress value for the entire assembly (1076.26 MPa). For retentive screws and abutments, CMP with iPRD had the highest von Mises stress value (319.97 and 452.78 MPa, respectively). CMP-PRD had the highest principal stress (131.66 MPa) in the anterior mandible. The iPRD reduced principal stress in both the anterior and posterior mandible. Using the RSM, we generated 25 groups for comparison to achieve the most favorable results for the iPRD and we might suggest the CL to 12 mm and the SP to 0.4 mm in the further clinical trials.

Conclusion

Use of the PRD and iPRD in CMP may resolve the challenges associated with CMP, thereby promoting its usage in clinical practice.

Implant-supported prosthetic rehabilitation after Ameloblastomas treatment: a systematic review

BACKGROUND

Ameloblastoma (AM), the benign counterpart of ameloblastic carcinoma, is a benign odontogenic tumor of epithelial origin, naturally aggressive, with unlimited growth potential and a high tendency to relapse if not adequately removed. Patients with AM treated surgically can benefit from dental implant therapy, promoting oral rehabilitation and improving their quality of life. The present study aimed to determine the survival rate of dental implants placed after surgical treatment of patients affected by AM. In addition, there were two secondary objectives: 1) To evaluate which dental implant loading protocols are most frequently used and 2) To determine the type of prosthetic restoration most commonly used in these patients.

METHODS

The Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines were followed during the study. Searches were performed in three databases (PubMed/MEDLINE, Scopus, and Google Scholar) until November 2023. Additionally, the electronic search was enriched by an iterative hand search of journals related to oral pathology and medicine, maxillofacial surgery, and oral prosthodontics and implantology. Only reports and case series in English from January 2003 to date were included. The Joanna Briggs Institute tool (JBI-Case Reports/Case Series) was used for the study quality assessment.

RESULTS

The total number of patients and implants studied were 64 and 271, respectively, all with surgically treated AM. The patient's ages ranged from 8 to 79 years, with a mean (SD) age of 37.3 ± 16.4. Fifty-three percent were male and 47% were female. The range of follow-up duration was 1 to 22 years. An implant survival/success rate of 98.1% was reported. In addition, most of them were conventionally loaded (38.3%). Hybrid implant-supported fixed dentures were the most commonly used by prosthodontists (53%).

CONCLUSIONS

Oral rehabilitation with dental implants inserted in free flaps for orofacial reconstruction in surgically treated patients with AM can be considered a safe and successful treatment modality.

Do Case Reports on Total Mandibular, Extended, and Bilateral Total Temporomandibular Joint Reconstruction Prostheses Adhere to the Surgical CAse REport Guidelines?

PURPOSE

The Surgical CAse REport (SCARE) guidelines are a standardized format for reporting surgical cases. The aim of this study was to evaluate the completeness of case reports documenting alloplastic reconstruction of large craniomaxillofacial defects involving total mandibular, bilateral, and extended temporomandibular joint in major high-quality craniomaxillofacial journals, based on the SCARE guidelines.

METHODS

An extensive online search was performed according to the Priority Reporting Items for Systematic Reviews and Meta-Analyses statement in PubMed, Embase, Scopus, Google Scholar, and Dimensions databases to identify relevant case reports. Each selected case report was assessed on 16 topics (38 items) of the SCARE guidelines, using a scoring scale of "0" (No/noncompliance), "1" (Yes/compliance), and 2" (unclear). The completeness of reporting (COR) score was calculated as the ratio of "yes" responses to "total" (ie, yes + no + unclear) responses. Adequacy of case reporting was denoted by a COR score of 70% or more.

RESULTS

A total of 35 case reports were selected, where the male to female patients ratio was 3:4 cases, mean ± standard deviation (SD) age: 34.9 ± 16.7 years, mean ± SD follow-up duration: 17.0 ± 12.9 months, and number of patients with left, right, and bilateral temporomandibular joint reconstruction prostheses were 16, 10, and 09, respectively. The mean ± SD COR score for all 35 case reports and the individual item of the SCARE guidelines was 70.2 ± 10.5% and 66.5 ± 31.2%, respectively. The minimum and maximum COR score was found for "Keywords" (0.0%) and "Introduction" (100%) and "Clinical Findings" (100%), respectively. Adequate reporting was found for 20/35 (57%) case reports.

CONCLUSIONS

This study revealed that case reports in major high-quality craniomaxillofacial journals suffer from insufficient reporting. Widespread adoption of available standards, such as SCARE guidelines, is proposed to improve the quality and robustness of case reporting.

Mandibular Reconstruction after Resection of Ameloblastoma by Custom-Made CAD/CAM Mandibular Titanium Prosthesis: Two Case Reports, Finite Element Analysis and Discussion of the Technique

Virtual surgical planning for CAD/CAM mandibular reconstruction by titanium prosthesis was recently reported for resected cases. Even if some advantages are evident, difficulties that may arise for TMJ function after reconstruction originate from prosthesis contamination through oral mucosa dehiscence. In these two cases reported of mandibular reconstruction after resection of ameloblastoma by custom-made CAD/CAM titanium prosthesis, the procedures were aimed to preserve the TMJ glenoid cavity and articular disc avoiding functional problems for hemi-mandibular resections that included the condyle (as in case #1) or with condylar preservation (as in case #2) and avoiding intraoral incisions in both cases. The entire surgical planning and prosthetic fabrication were explained with specifications and the sequence of the surgical procedure. Finite elements analysis (FEA) was performed to check the force distribution and efficacy of the prosthetic device (case 1 with hemi-mandibular resection and rehabilitation). Although successful in these two cases, surgical reconstruction of the mandibular defect after resection by a CAD-CAM custom-made prosthesis still shows some drawbacks and failure risks. Several advantages of this technique and the surgical success in these two cases were presented, but limitations and side effects must be considered when cases are selected.

Custom-Made 3D Titanium Plate for Mandibular Reconstruction in Surgery of Ameloblastoma: A Novel Case Report

Ameloblastoma is a benign yet locally invasive odontogenic neoplasm, characterised by slow growth and painless swelling. The treatment for ameloblastoma varies from curettage to en bloc resection, with recurrence commonly occurring. The safety margin of resection is hence essential to avoid recurrence. Understanding the three-dimensional anatomy for reconstruction of mandibular defects after tumour resection often poses problems for head and neck surgeons. Historically, various autografts and alloplastic materials have been used in the reconstruction of these types of defects. Over time, advances in technology with computed tomography scanners and three-dimensional images enhance the surgical planning and management of maxillofacial tumours. The development of new prototyping systems provides accurate 3D biomodels on which surgery can be simulated, especially in cases of ameloblastoma, in which the safety margin is vital for the clinical outcome. The objective of this paper was to report a clinical case of employing these methodologies for reconstruction after an extensive mandibular resection. The clinical outcomes were observed. A case of follicular ameloblastoma of the mandible is depicted in the following paper, where a 3D biomodel was used throughout the surgery. A 3D printed patient-specific titanium implant was manufactured and placed intraoperatively for reconstruction. The treatment had satisfactory postoperative results without complications. Titanium implants being bioinert, customisable and easily workable, especially with the help of 3D virtual planning techniques, can be considered as ideal alloplastic materials for mandibular reconstruction.

Facial Fat Grafting (FFG): Worth the Risk? A Systematic Review of Complications and Critical Appraisal

Introduction: Autologous fat is ideal soft tissue filler. It is easily accessible, biocompatible, cheap, and it provides both volume augmentation and skin quality improvement. Fat grafting has been used since 1893, but it has only gained widespread popularity since the development of modern liposuction by Colemann and Illouz in the 1980s. Every year more than half a million facial fat grafting procedures are carried out worldwide and the trend is rapidly increasing. Overall, general complications associated with facial fat grafting are assumed to be around 2%. Is that true? Material and Methods: Until July 2021, a systematic search of the literature was performed interrogating PubMed search engines. The following algorithm was used for the research: (fat graft OR lipofilling) AND face AND complications. Exclusion criteria applied hierarchically were review articles, not reporting recipient site complications; not in English and paediatric population. Abstracts were manually screened by LS, GS, JM and PDS separately and subsequently matched for accuracy. Pertinent full-text articles were retrieved and analysed and data were extracted from the database. The flow chart of article selection is described following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Results: In total, 462 papers were identified by PubMed search. A total of 359 were excluded: 38 papers were not in English, 41 were review articles, 279 articles did not report recipient site complications and 1 was not on human subjects. Average complication rate ranged from 1.5% to 81.4%. A total of 298 adverse events were identified: 40 (13.4%) intravascular injections, 13 (4.3%) asymmetry, 57 (19.1%) irregularities, 22 (7.4%) graft hypertrophy, 21 (7%) fat necrosis, 73 (24.5%) prolonged oedema, 1 (0.3%) infection, 6 (2%) prolonged erythema, 15 (5%) telangiectasia and 50 (16.8%) cases of acne activation. Conclusions: FFG related side effects could be resumed in three categories: severe, moderate, and minor. Severe (13.4%) side effects such as intravascular injection or migration require neurological or neurosurgical management and often lead to permanent disability or death. Moderate (38.3%) side effects such as fat hypertrophy, necrosis, cyst formation, irregularities and asymmetries require a retouch operation. Minor (48.3%) side effects such as prolonged oedema or erythema require no surgical management. Despite the fact that the overall general complication rate of facial fat grafting is assumed to be around 2%, the real complication rate of facial fat grafting is unknown due to a lack of reporting and the absence of consensus on side effect definition and identification. More RCTs are necessary to further determine the real complication rate of this procedure.

The Use of Customized Three-Dimensionally Printed Mandible Prostheses with a Pressure-Reducing Device: A Finite Element Analysis in Different Chewing Positions, Biomechanical Testing, and In Vivo Animal Study Using Lanyu Pigs

Segmental bony defects of the mandible constitute a complete loss of the regional part of the mandible. Although several types of customized three-dimension-printed mandible prostheses (CMPs) have been developed, this technique has yet to be widely used. We used CMP with a pressure-reducing device (PRD) to investigate its clinical applicability. First, we used the finite element analysis (FEA). We designed four models of CMP (P1 to P4), and the result showed that CMP with posterior PRD deployment (P4 group) had the maximum total deformation in the protrusion and right excursion positions, and in clenching and left excursion positions, posterior screws had the minimum von Mises stress. Second, the P4 CMP-PRD was produced using LaserCUSING from titanium alloy (Ti-6Al-4V). The fracture test result revealed that the maximum static pressure that could be withstood was 189 N, and a fatigue test was conducted for 5,000,000 cycles. Third, animal study was conducted on five male 4-month-old Lanyu pigs. Four animals completed the experiment. Two animals had CMP exposure in the oral cavity, but there was no significant inflammation, and one animal had a rear wing fracture. According to a CT scan, the lingual cortex of the mandible crawled along the CMP surface, and a bony front-to-back connection was noted in one animal. A histological examination indicated that CMP was significantly less reactive than control materials (p = 0.0170). Adequate PRD deployment in CMP may solve a challenge associated with CMP, thus promoting its use in clinical practice.

Mandibular Body Reconstruction Utilizing a Three-Dimensional Custom-Made Porous Titanium Plate: A Four-Year Follow-Up Clinical Report

A clinical case of a 42-year-old woman patient, who had a mandibular reconstruction utilizing a three-dimensional (3D) custom-made porous titanium plate dental restoration, is presented. She showed a recurrence of a unicystic ameloblastoma involving the left hemimandible. The patient declined to be managed by a bone-free flap. A mandibular resection in the healthy areas was provided, followed by reconstruction utilizing a 3D custom-made porous titanium plate dental restoration with a hybrid dental prosthesis. The 3D rehabilitation was created considering slim tomodensitometric sections. The cutting guides and custom-created 3D plate were fabricated employing medical software via computer-aided design and fabricating with locations planned for healing abutments. The patient was contented with the rehabilitation, and the condition continued stable at the four-year follow-up.

Design Criteria for Patient-specific Mandibular Continuity Defect Reconstructed Implant with Lightweight Structure using Weighted Topology Optimization and Validated with Biomechanical Fatigue Testing

This study developed design criterion for patient-specific reconstructed implants with appearance consideration and structural optimization of various mandibular continuity defects. The different mandible continuity defects include C (from left to right canines), B (from 1^st premolar to 3^rd molar), and A (from 3^rd molar to ramus) segments defined based on the mandible image. The finite element (FE) analysis and weighted topology optimization methods were combined to design internal support beam structures within different reconstructed implants with corresponding occlusal conditions. Five continuity mandibular defects (single B/C/A+B and combination of B+C and B+C+B segments) were restored using additive manufacturing (AM) reconstructed implant and bone plate to confirm reasonable design criterion through biomechanical fatigue testing. The worst mandible strength was filtered based on the material mechanics and results from segmental bone length, thickness, and height statistics from the established database containing mandible images of 105 patients. The weighted optimization analysis results indicated that the sizes and positions of internal supporting beams within the reconstructed C, B, and A+B implants can be defined parametrically through corresponding segmental bone length, width, and height. The FE analysis found that the weight variation percentage between the parametric designed implants and original core solid implants in the C, B, and A+B was reduced by 54.3%, 63.7%, and 69.7%, respectively. The maximum stress values of the reconstructed implant and the remaining bone were not obviously reduced but the stress values were far lower than the material ultimate strength. The biomechanical fatigue testing indicated that all cases using the AM reconstructed implant could pass the 250,000 dynamic load. However, condyle head, bone plate fracture, and bone screw loosening could be found in cases using bone plates. This study developed a design criterion for patient-specific reconstructed implants for various mandibular continuity defects applicable for AM to further clinical use.

Reconstruction of bilateral ramus-condyle unit defect using custom titanium prosthesis with preservation of both condyles

BACKGROUND

Novel technologies for management and reconstruction of complex bony defects regarding both function and facial appearance are interestingly used in maxillofacial surgery. In the current study, we demonstrated reconstruction of a bilateral ramus-condyle unit (RCU) defect while preserving both condyles by a novel designed titanium prosthesis using virtual surgical planning (VSP), computer-aided design and manufacturing (CAD/CAM), and Selective Laser Melting (SLM) technologies.

MATERIALS AND METHODS

A 3D customized titanium prosthesis was designed for a 49 -year-old patient with bilateral mandibular aggressive central giant cell granuloma (CGCG) according to mandibular normal anatomy and structure while preserving bilateral intact condyles. Finite element study was performed to investigate the effects of new design strength and the stress shielding phenomenon. The design of macro-pores inside the body of prosthesis allowed it to act as a scaffold for bone tissue engineering under load bearing conditions.

RESULTS

Analysis of the strength and stress shielding phenomenon demonstrated favorable outcomes regarding the novel design. For instance, there was no stress shielding in any of the preserved condyles with regard to the size and distribution of stresses. Also, the stress distribution around the pores showed that these pores had no effect on the strength of the prosthesis. Thirty month follow-ups after reconstruction of bilateral RCU defect showed normal jaw function with a favorable facial appearance and mandibular contour.

CONCLUSION

We design a novel patient-specific prosthesis with desirable biomechanical features for reconstruction of bilateral RCU defect after resection of the benign tumor with preservation of bilateral intact condyles.

Alloplastic Temporomandibular Joint Reconstruction Following Recurrent Ameloblastoma Resection

ABSTRACT

Ameloblastomas are benign tumors that most commonly affecting the mandible. The current standard of treatment for ameloblastomas is resection followed by reconstruction that has historically been accomplished through the use of a microsurgical vascularized flaps taken from the iliac crest or fibula. Alloplastic reconstruction methods have gained popularity over recent years with success reported in the reconstruction of many pathologies, including ankylosis, condylar fracture, neoplasia involving extensive resection, severe inflammatory/degenerative temporomandibular joint (TMJ) disease, and congenital TMJ abnormalities. The authors present a patient who successfully underwent ameloblastoma resection and TMJ reconstruction with a custom TMJ Concepts alloplastic implant. The authors also present a review of the literature on alloplastic TMJ reconstruction following ameloblastoma resection. To our knowledge, this is the second report in the literature on the use of a TMJ Concepts implant after ameloblastoma resection.

Integrating Finite Element Death Technique and Bone Remodeling Theory to Predict Screw Loosening Affected by Radiation Treatment after Mandibular Reconstruction Surgery

This study developed a numerical simulation to understand bone mechanical behavior and micro-crack propagation around a fixation screw with severe mandibular defects. A mandible finite element (FE) model was constructed in a rabbit with a right unilateral body defect. The reconstruction implant was designed to be fixed using six screws distributed on the distal and mesial sides. The element death technique provided in FE analysis was combined with bone remodeling theory to simulate bone necrosis around the fixation screw in which the strain value reached the overload threshold. A total of 20 iterations were performed to observe the micro-crack propagation pattern for each screw according to the high strain locations occurring in each result from consecutive iterations. A parallel in vivo animal study was performed to validate the FE simulation by placing specific metal 3D printing reconstruction implants in rabbits to compare the differences in bone remodeling caused by radiation treatment after surgery. The results showed that strain values of the surrounding distal bone fixation screws were much larger than those at the mesial side. With the increase in the number of iteration analyses, the micro-crack prorogation trend for the distal fixation screws can be represented by the number and element death locations during the iteration analysis process. The corresponding micro-movement began to increase gradually and induced screw loosening after iteration calculation. The strained bone results showed that relatively high bone loss (damage) existed around the distal fixation screws under radiation treatment. This study concluded that the FE simulation developed in this study can provide a better predictive diagnosis method for understanding fixation screw loosening and advanced implant development before surgery.