International Journal of Oral and Maxillofacial Surgery
Clinical PaperTMJ DisordersA ten-year experience and follow-up of three hundred patients fitted with the Biomet/Lorenz Microfixation TMJ replacement system
Introduction
The temporomandibular joint (TMJ) is an atypical diarthrodial synovial joint capable of performing both translation and rotation movements, formed by the mandibular condyle and glenoid fossa of the squamous part of the temporal bone, and separated into upper and lower cavities by the presence of an articular fibrocartilaginous disc.1 This joint may be the subject of change as a result of numerous different factors, with different causes and intensities, leading to partial or complete loss of functionality.2, 3, 4
Although minor disarrangements may be treated by means of more conservative procedures such as discopexy, eminectomy, or arthroplasties, extreme cases can result in ankylosis, severe resorption, or irreparable joint degeneration, making the reestablishment of the functions of the TMJ by these surgical procedures impossible. In these cases, reconstruction by installation of prosthetic TMJ devices has become the best therapeutic choice and provides a safe and viable alternative.2, 3, 5, 6
The use of a TMJ prosthesis, when compared to other reconstructive procedures (costochondral grafts, for example), reduces the duration of surgery, reduces morbidity since a donor site is not required, leads to shorter hospitalization times, and provides immediate function, with no need for postoperative intermaxillary fixation (IMF). However, the TMJ prosthesis may also present some disadvantages, including the lack of predictability for a surgical revision, prosthesis failure secondary to either loosening of a screw or fracture of the prosthesis from metal fatigue, the limited fit of stock prostheses, the loss of laterality and protrusion movements due to detachment of the lateral pterygoid muscle, and its high cost.7
In recent decades, many prosthetic systems have been developed and marketed but in the long term have given unsatisfactory clinical results and have led to postoperative complications of great importance. Nowadays, just three of these devices are still in use and have been approved by the US Food and Drug Administration (FDA): TMJ Concepts (Ventura CA, USA), TMJ Implants (aka Christensen) (Golden, CO, USA), and Biomet/Lorenz (Jacksonville, FL, USA).5
The aim of this study was to evaluate the postoperative clinical results obtained in 300 patients submitted to installation of the Biomet/Lorenz Microfixation TMJ Replacement System over a period of 10 years.
Section snippets
Materials and methods
For this study, data were collected from 300 patients (180 men and 120 women) aged between 20 and 60 years who underwent installation of the Biomet/Lorenz Microfixation TMJ Replacement System between the years 2000 and 2010. Among these patients, 201 underwent unilateral reconstruction and 99 bilateral reconstruction. All patients were considered candidates for joint reconstruction after clinical and imaging examinations (panoramic radiography, computed tomography scans (CT), and, if necessary,
Results
Numerical MIO results were obtained using a calliper rule, with reference to the upper and lower central incisors on the same side. The subjective data evaluation (function and speech, diet, and pain) was performed using a visual analogue scale (VAS), where for each variable there were six scores (ranging from 0 to 5). Descriptions of the scores for each variable are presented in the separate results sections below (Fig. 1).
Discussion
The TMJ can be affected as a result of various types of changes that can significantly compromise the functioning of the stomatognathic system.3, 5 In most cases, the TMJ and the associated muscles are affected by a heterogeneous group of multifactorial origin changes triggering a series of signs and symptoms such as pain in the preauricular region and/or the muscles of mastication, abnormal jaw movement, joint sounds such as clicking and/or crepitus during mandibular movements, ear pain, neck
Funding
None.
Competing interests
None declared.
Ethical approval
Not required.
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