Using a titanium printed resected human mandibular condyle as a potential replacement model: a hypothesis
Article information
Abstract
Our purpose is to present a novel cost-effective therapeutic option for replacing lost mandibular condyle in developing countries. Condyle replacement remains challenging, particularly in reproducing an anatomical form that fits precisely within the glenoid cavity. When rehabilitating patients who have lost their condyle due to tumor resection, idiopathic condylar resorption or ankyloses of the temporomandibular joint, the main difficulty resides in finding a form that fits into the glenoid cavity. Our idea is to use this intact functional condyle preserved and resected from a benign jaw tumor as a scanned model to replace and serve as a template to replace lost mandibular condyles.
INTRODUCTION
Condyle replacement can be challenging, particularly in reproducing a form that fits accurately into the glenoid cavity. When rehabilitating patients who have lost the mandibular condyle due to tumor resection, idiopathic condylar resorption [1], or temporomandibular joint ankylosis, the main difficulty resides in finding a form that fits into the glenoid cavity. In our local context and in developing countries, the incidence of mandibular condyle replacement may be higher than expected because patients with jaw tumors, especially benign ones, are often diagnosed late and receive treatment late leading to large loss of substance, more so in patients presenting with recurrences [2]. Adequate replacement of a lost mandibular condyle helps restore aesthetics and function (mastication, speech, and mandibular movement).
Death as a direct result of oral diseases is rare [3], however, these patients who undergo radical surgery have increased disability-adjusted life years, high morbidities which we hope to remediate with a cost-effective and practical method. The direct and indirect global economic impact of oral conditions may amount to more than US$442 billion [4], and these estimates will keep rising with increasing disability-adjusted life years [3]. Also, the estimated per capita expenditure on dental healthcare in Cameroon is US$0.3 and the total productivity losses due to oral diseases is US$87 million; showing the huge economic impact of poor oral healthcare. Given the economic situation and the absence of universal health coverage in Cameroon, it is difficult for the average patient to undergo a computed tomography scan given that the patients shoulder the majority of the expenses [5]. Therefore, we propose a model of a human adult condyle, resected from a benign jaw tumor, scanned, and 3D printed in titanium as a cost-effective therapeutic option to replace mandibular condyles in patients who have lost theirs especially in developing countries to help address this issue.
IDEA
To present a novel, cost-effective therapeutic option for mandibular condyle replacement that fits precisely into the glenoid cavity. Ethical approval was obtained from the Ethical Committee of the Faculty of Medicine and Biomedical Sciences of the University of Yaoundé I to carry out this study as well as patient consent prior to commencing this work. We used a condyle resected from a benign jaw tumor (Figs. 1, 2). The resected condyle was preserved in formaldehyde for 3 months. We scanned the resected mandibular condyle using a short-range 3D scanner (GO!SCAN 50; Creaform Inc.). After reconstruction (Fig. 3), we used the Polyjet Object 260 and the Single Color Polyjet 3D (both Stratasys) to print out some prototypes using ABS (acrylonitrile butadiene styrene) as the printing material with different colors and tensile strengths for didactic purposes (Fig. 4).
Pre-operative orthopantomography showing extensive left mandibular osteolysis (red circle) due to a late presentation of a benign jaw tumor.
Resected condyle from an adult patient.
Scanned resected condyle.
Printed model of condyle in acrylonitrile butadiene styrene.
DISCUSSION
Our goal is to 3D print this human condyle in titanium, taking advantage of its natural anatomical shape, and to attach a mandibular prosthesis to it. To better describe our goal, we simulated the tumor defect of the patient seen in Fig. 1 and added to our scanned condyle model a mandibular body, a ramus and coronoid process to create a fitting reconstructed model as shown in black in Fig. 5. More precisely, this model will be combined with a porous titanium mandibular body to further reduce weight as titanium has features such as light weight, high resistance, and good biocompatibility [6]. This titanium body can be customized to match bone defects of various sizes, beyond the dimensions presented in this study. Three screws were added to this metallic body to serve as anchor points for the temporal and masseter muscles to facilitate the functioning of the manducatory apparatus. In addition, the model will be fixed to the remaining mandible with three surgical plates to ensure maximum stability while respecting osteo-articular biomechanics (Fig. 5). This model can be applied not only to this patient but also to others undergoing hemimandibulectomy with disarticulation.
(A) Anterolateral view and (B) anterior view of fixed models.
For patients requiring condylar resection, the model can be pre-fabricated and implemented during the primary surgery, thereby reducing the need for a secondary procedure to offer a cost-effective option to replace their lost condyles, improve function and in addition the body of the model will be in function of the initial bone defect. For patients diagnosed, needing condyle resection surgery, our model can be implemented with the primary surgery that is prepared prior and placed after surgery, hence saving costs associated with a secondary surgery, which is critical in resource-limited settings and also better for optimum functional rehabilitation and reducing muscle atrophy due to disuse.
Notes
Conflict of interest
No potential conflict of interest relevant to this article was reported.
Funding
None.
Ethical approval
The study was approved by the Ethical Committee of the Faculty of Medicine and Biomedical Sciences of the University of Yaoundé I (N°0288/UY1/FMSB/VDRC/CSSD).
Patient consent
The patient provided written informed consent for the publication of the case and related images.
Author contributions
Conceptualization: Zilefac Brian Ngokwe, Ntep Ntep David Bienvenue, Bengondo Messanga Charles. Methodology: Zilefac Brian Ngokwe, Ntep Ntep David Bienvenue, Nokam Kamdem Stephane. Visualization: Wirndzerem Blaise Fonyuy. Writing–original draft: Zilefac Brian Ngokwe, Nokam Kamdem Stephane, Bengondo Messanga Charles. Writing–review & editing: Zilefac Brian Ngokwe, Ntep Ntep David Bienvenue, Wirndzerem Blaise Fonyuy. Investigation: Zilefac Brian Ngokwe, Ntep Ntep David Bienvenue, Nokam Kamdem Stephane, Wirndzerem Blaise Fonyuy. Software: Wirndzerem Blaise Fonyuy. Supervision: Zilefac Brian Ngokwe, Bengondo Messanga Charles. Validation: Zilefac Brian Ngokwe, Ntep Ntep David Bienvenue. All authors read and approved the final manuscript.