Evaluation of The Effectiveness of Alloplastic Prostheses for Atm Reconstruction: A Systematic Review

Evaluation of The Effectiveness of Alloplastic Prostheses for Atm Reconstruction: A Abstract Objective: To evaluate the efficacy of total reconstruction of temporomandibular joint with alloplastic prostheses through a systematic literature review, focusing on pain, mouth opening and postoperative complications. Method: This is a systematic review of the scientific production of the PubMed indexer. A combination of the terms “tmj reconstruction” and /


Introduction
The reconstruction of the Temporomandibular Joint (TMJ) represents one of the most complex surgical approaches within maxillofacial surgery. The objectives of TMJ reconstruction include the three-dimensional restoration of joint morphology and function, reduction of existing symptoms and limitations, in addition to preventing the progression of some diseases [1].
Replacement of the TMJ with an alloplastic prosthesis is usually the last resort in cases of temporomandibular diseases in its terminal state [2]. The first alloplastic prosthesis for TMJ was developed in the 1960s by Christensen [3]. Since then, a range of new models and new techniques has been tested and improved, with the aim of promoting maximum use of these devices, bringing benefits to patients [4]. Alloplastic prostheses have been a widely accepted option and several surgeons have used them in different cases. The number of alloplastic prostheses implanted for reconstruction of mandibular segments involving the TMJ has grown significantly in recent decades, mainly due to the demand for quality of life of the population [5]. Some advantages of TMJ reconstructions with alloplastic materials include the possibility of starting physiotherapy in the immediate postoperative period, and the fact that a graft donor site is not necessary, which reduces surgical time and possible morbidity, resulting in fewer days inpatient [4] some complications can occur, such as fracture of the prosthesis, pain, infection, exposure and wear of the material, among others. This is because the location where the prosthesis is installed is extremely challenging, not only due to the biomechanical characteristics of the ATM, but also due to the remaining structures around it [6].
However, advances in imaging and advances in computing, including three-dimensional image processing with exact parameters, have allowed surgeons to more accurately diagnose their patients, in addition to enabling better planning and simulations, bringing ever more predictable results [7]. The ideal characteristics of a prosthesis include biocompatibility, functionality, low weight, adaptability, stability, resistance and nontoxic. These characteristics are the target of alloplastic material companies, in order to produce materials that can physiologically reconstruct the ATM and thus have increasingly predictable results [8]. However, it has been observed that it is very difficult to

Methodology
This is a systematic bibliographic review study of the scientific production of the PubMed indexer about the effectiveness of using alloplastic prostheses for the reconstruction of the temporomandibular joint, focusing on the variables mouth opening, pain and complications. A combination of the following search terms was used: "TMJ reconstruction" and / or "temporomandibular joint prosthesis" and / or "TMJ replacement" and / or "alloplastic prostheses". The results were submitted to the classification and inclusion protocols of the studies.
Controlled clinical trials and prospective and retrospective observational studies in humans, with more than 10 cases studied, comparing or containing results of surgical techniques for TMJ "temporomandibular joint prosthesis" and / or "tmj replacement" and / or "Alloplastic Prostheses (AP)" was used. Studies with a follow-up time of less than 2 years were excluded years, studies published outside the current decade, case reports, reports, animal studies and reviews. Clinical trials and prospective and retrospective observational studies that had pre-and postoperative information on mouth opening, pain, incidence of complications and recurrence were included.
Results: Nine (9) studies were analyzed, all in English. The average follow-up time ranged from 2 to 21 years. In total, 438 patients were evaluated, the vast majority of whom were female.
Conclusion: All articles brought positive data regarding improvements in pain and mouth opening Prostheses for TMJ are considered a viable option for the reconstruction of compromised temporomandibular joints, bringing important benefits to patients with advanced stage TMJ diseases. It has been observed, however, that it is very difficult to predict many of the interactions between prosthesis and patient, and only with results of clinical experiments and research it is possible to evaluate the success and the failures in the use of those devices.

Results
A total of 9 (nine) studies were included, all in English, of which 6 (six) were prospective cohort studies and 3 (three) were retrospective studies. Detailed data for the nine studies are shown in Table 1. The average follow-up time ranged from 2 to 21 years.
In total, 438 patients were evaluated, the vast majority of whom were female (gender data missing in 1 of 9 articles). TMJ surgical approaches were the same in all studies that reported them. Six of the nine articles reported the technique used to install the prostheses, which consisted of pre-auricular access combined with submandibular or retromandibular access. Three articles did not report the technique used. Data regarding mouth opening, pre-and postoperative pain and complications are available in Table 2.

Discussion
This review study sought, in a systematic way, to evaluate the efficacy of TMJ alloplastic prostheses for the treatment of diseases that affect this joint, evaluating the variables pain, mouth opening and complications. The selected and studied articles are heterogeneous as to the type of study, sample size, materials, systems and patient characteristics, therefore, the present results should be interpreted with caution. Regarding pain, the data present in one of the studies [9] showed subjective pain relief for up to 3 years after surgery in most patients and in the global average (Table 2) The results of another publication [7] also showed a significant reduction in pain intensity after two years of follow-up. There was a significant reduction in pain in 25 cases of TMJ replacement (48% of the patients studied), with a reduction in pain of more than 80% (compared to preoperative pain values). Twelve of these 25 patients (23% of the total cases) were in the 100% pain reduction category, that is, with a postoperative pain score of 0 (total absence of pain).
The other studies reported pain reduction based on the global average of their results [8,[10][11][12]. Regarding mouth opening, all studies have shown positive results with regard to improvement in mouth opening [7][8][9][10][11][12][13][14][15]. However, one of the studies 13 reports that of the 12 patients in the sample, two had no gains in mouth opening.
These two patients admitted that they did not perform the mandible opening exercises, required by the preoperative agreement, which indicates that the postoperative physical exercises are important so that the patients reached an acceptable opening capacity.
The results of another study [7] show that there was an improvement of mouth opening 2 years after surgery (Table   2), although the author himself acknowledged that there was a discrepancy in the distribution of data, since some patients gain), which makes the distribution highly asymmetric, tilting to the right. A similar situation is also identified in another publication [12], where the specific group of ankylosing patients had much greater improvements in mouth opening compared to the rest of the sample, which also generates a bias in the study result, since ankylosing patients have marked signs disease, limitation of mouth opening. The complications reported in the studies were quite standardized, with facial nerve injuries being the most common [7,[10][11][12]. One of the studies [11] points out that 27% of patients reported adverse problems even after 1 year of surgery (Table   2), a relatively high rate of complications. However, for the group with persistent complications, the average number of previous procedures was 2.60 compared to an average of 1.77 for the group without complications. This finding suggests that the number of previous operations is a significant predictor of adverse outcomes in the postoperative period. One study did not report postoperative complications.

Conclusions
TMJ reconstructions with alloplastic materials reduce the perception of pain after the surgical procedure of installation, in addition to improvements in the opening of the mouth that are maintained even for long periods of follow-up. The most frequent complications were injuries to the facial nerve and its branches.