F-Chin/Feminizing the Chin: A Genioplasty Technique with Virtual Planning for Male-to-Female Transgender Patients.

The chin is an essential structure in facial harmony and an important gender marker. Advancing a receding chin is fundamental to improve the facial appearance, particularly in male-to-female transgender patients. However, in patients with microgenia and/or retrognathia, desiring a more feminine appearance, a chin advancement can result in a wider, square shape; an undesirable effect. Genioplasty is a versatile procedure used in facial feminization surgery that allows modifying the natural anatomy of the chin in all three spatial dimensions. The technique herein described proposes a simple genioplasty procedure for feminizing the chin (F-chin genioplasty) in transgender patients where anteroposterior advance is required. Virtual planning was used to establish the landmarks for an anteroposterior advancement with transverse reduction in the chin. A perpendicular line to the Frankfurt plane passing through the incisal edge of the upper central incisor was used to plan the anteroposterior movement, and two vertical lines on the outer wall of the nasal cavity  for the chin transverse measurement. The authors present three case reports with the F-chin genioplasty transgender technique with satisfactory results, ensuring a more feminine facial appearance.Level of Evidence V This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Temporomandibular Joint Minimally Invasive Procedures in the Pediatric Population: A Prospective Study.

Over recent years, temporomandibular joint (TMJ) minimally invasive procedures, such as arthrocentesis and arthroscopy, have been appointed as an initial TMJ intra-articular treatment. Both procedures present safe and effective clinical results in managing temporomandibular disorders (TMD) by reducing pain and improving mouth opening. The use of these techniques in adults is validated in the literature. However, data on the safety and effectiveness of minimally invasive TMJ interventions in pediatric patients are scarce. This study aims to investigate the effectiveness of TMJ arthrocentesis and arthroscopy in the pediatric population. A prospective study was conducted at Instituto Português da Face (IPF) in Lisbon, Portugal, including patients treated for TMD from 1 June 2019 to 30 June 2023. In the present study, 26 patients (17 female and 9 male) were included, representing a total of 48 joints operated. A statistically significant reduction was observed in the primary outcome, TMJ pain, from 3.93 ± 2.80 preoperatively (mean ± SD) to 0.50 ± 1.53 (mean ± SD) postoperatively (p < 0.05). An improvement in the secondary outcome, maximum mouth opening, from 36.92 ± 8.79 preoperatively to 42.96 ± 5.07 postoperatively, was observed (p < 0.05). The overall success rate was 84.62%. This prospective study showed that TMJ arthrocentesis and arthroscopy appear to benefit pediatric patients with TMD, significantly lowering pain and improving MMO without relevant postoperative complications.

Considerations for the Use of Alloplastic Temporomandibular Joint Replacement in Irradiated Patients: Report of an Off-Label Indication.

BACKGROUND: Custom-made alloplastic temporomandibular joint replacement (ATMJR) is not validated in irradiated patients. However, in specific situations, after previous reconstructive surgical failures, the authors hypothesized the role of a customized ATMJR after radiotherapy. METHODS: A 65-year-old male patient was referred to Instituto Português da Face-Lisbon, Portugal-after failed attempts of mandibular reconstruction secondary to oral carcinoma resection and partial hemi-mandibulectomy plus radiotherapy of 60 total Grays. Primary reconstruction was performed with fibula free flap. Due to failure, secondary reconstructions were performed with osteosynthesis plate without success. The patient was unable to have adequate mastication and deglutition due to a severe crossbite. The authors treated the patient with an extended customized alloplastic temporomandibular joint replacement (F0M2). RESULTS: With 3 years of follow-up, the patient showed an improvement in masticatory function, mandibular motion, pain levels, and overall quality of life. No complications were observed related to ATMJR. CONCLUSIONS: The presented case described how ATMJR, although not a validated option after radiotherapy, can be considered to restore functionality in complex cases with bone and soft tissues problems.

Effectiveness of double-puncture temporomandibular joint arthrocentesis with viscosupplementation in different categories of severity - a prospective study.

This 3-year prospective study evaluated the efficacy of temporomandibular joint (TMJ) arthrocentesis with viscosupplementation in different severity stages based on the Dimitroulis classification (categories 2-4 were included). TMJ arthrocentesis was performed under local anaesthesia, and the protocol consisted of a double-puncture technique with lavage of ≥150 cc Ringer Lactate plus viscosupplementation. Incobotulinum toxin A was administered 10-15 days preoperatively in patients with concomitant masticatory myalgia. The primary outcome was TMJ pain, assessed by visual analogue scale (VAS, 0-10), and the secondary outcomes were the maximum mouth opening (MMO, mm) and myalgia degree (0-3). All outcomes were assessed on the intervention day (T0) and after the procedure (T1) (minimum 1 month and then 3 months, 6 months, 1 year and every year since). A total of 108 patients were enrolled (mean age of 43.1 ± 18.9 years); 86 (80%) were women and 22 (20%) were men. Preoperative pain was 4.02 ± 3.12 (mean ± SD), MMO was 38.10 ± 9.56 (mean ± SD) and myalgia degree was 1.80 ± 1.18 (mean ± SD). After an average of 215.4 days (31-1253 days), a statistically significant improvement of pain (P < 0.0001), MMO (P = 0.005) and myalgia degree (P < 0.0001) was observed. The overall successful outcome of TMJ arthrocentesis with viscosupplementation was 76%. The authors observed increased arthrocentesis effectiveness and success rate with viscosupplementation in Dimitroulis category 2 (88.6%) compared to 3-4 (71.4%). An association was found between arthrocentesis with viscosupplementation failure and painful myalgia (ρ = 0.477; P < 0.0001). Thirteen patients (12%) underwent a second TMJ intervention after finalising the present trial. With a low complication rate, TMJ arthrocentesis with viscosupplementation led to an overall benefit for all the included patients. This study reinforces the important role of minimally invasive TMJ arthrocentesis as a first treatment option, with better results in the early stages compared to more severe stages.

Bilateral arthroscopy of the temporomandibular joint: clinical outcomes and the role of a second intervention-a prospective study.

OBJECTIVE: Evaluate the efficacy of bilateral temporomandibular joint (TMJ) arthroscopy in patients with different categories of severity based on Dimitroulis classification (categories 2-4) and the role of a second TMJ intervention in primary failure. METHODS: A 3-year prospective study was designed, including patients submitted to bilateral TMJ arthroscopy. The primary outcome was TMJ pain (VAS, 0-10) and the secondary outcomes were the maximum mouth opening (MMO) and masticatory myalgia degree (0-3). In cases of symptomatic relapse, a second TMJ intervention was performed (TMJ arthrocentesis or TMJ open surgery). RESULTS: Eighty patients (93.4% women) were enrolled, with a mean age of 32.40 ± 11.41 years. With an average follow-up of 523.7 days (34-1606), a statistically significant improvement in TMJ pain, MMO, and myalgia degree was observed (P < 0.0001). The overall successful outcome of one-single bilateral arthroscopy was ~ 69%. Twenty-two patients relapsed: (1) arthralgia (n = 15, 68.18%); (2) arthralgia + myalgia (n = 4, 18.18%); (3) dislocated disc without reduction (DDwoR) (n = 2, 9.09%); (4) DDwoR + osteoarthrosis (OA) (n = 1, 4.55%). Arthralgia was re-managed with TMJ arthrocentesis with local anesthesia (n = 19, 86.36%). New DDwoR with or without OA was re-treated with TMJ open surgery (n = 3, 13.64%). After the second intervention, the success rate increased to 85%. CONCLUSIONS: Bilateral TMJ arthroscopy presented overall benefit in all parameters evaluated. CLINICAL RELEVANCE: This study highlights the importance of TMJ arthroscopy as the first line of treatment for moderate-severe temporomandibular disorders cases contributing to the reduction of TMJ open surgeries. In cases of arthroscopy unsuccess, TMJ arthrocentesis under local anesthesia was an effective and safe intervention for patients with recurrent TMJ arthralgia.

Outcomes of IncobotulinumtoxinA Injection on Myalgia and Arthralgia in Patients Undergoing Temporomandibular Joint Arthroscopy: A Randomized Controlled Trial.

BACKGROUND: Several studies have considered Botulinum Neurotoxin Type A injections effective in treating temporomandibular joint disorder (TMD) symptoms. A double-blind, randomized, controlled clinical trial investigated the benefit of complementary incobotulinumtoxinA (inco-BoNT/A) injections in the masticatory muscles of patients submitted to bilateral temporomandibular joint (TMJ) arthroscopy. METHODS: Fifteen patients with TMD and an indication for bilateral TMJ arthroscopy were randomized into inco-BoNT/A (Xeomin, 100 U) or placebo groups (saline solution). Injections were carried out five days before TMJ arthroscopy. The primary outcome variable was a Visual Analogue Scale for TMJ arthralgia, and secondary outcomes were the myalgia degree, maximum mouth opening, and joint clicks. All outcome variables were assessed preoperatively (T0) and postoperatively (T1-week 5; T2-6-month follow-up). RESULTS: At T1, the outcomes in the inco-BoNT/A group were improved, but not significantly more than in the placebo group. At T2, significant improvements in the TMJ arthralgia and myalgia scores were observed in the inco-BoNT/A group compared to the placebo. A higher number of postoperative reinterventions with further TMJ treatments were observed in the placebo group compared to inco-BoNT/A (63% vs. 14%). CONCLUSIONS: In patients submitted to TMJ arthroscopy, statistically significant long-term differences were observed between the placebo and inco-BoNT/A groups.

Prevalence of Clinical Signs and Symptoms of Temporomandibular Joint Disorders Registered in the EUROTMJ Database: A Prospective Study in a Portuguese Center.

Temporomandibular joint disorders (TMDs) are characterized by their multifactorial etiology and pathogenesis. A 3-year prospective study was conducted in a Portuguese TMDs department to study the prevalence of different TMDs signs and symptoms and their association with risk factors and comorbidities. Five hundred ninety-five patients were included using an online database: EUROTMJ. Most patients were female (80.50%), with a mean age of 38.20 ± 15.73 years. The main complaints were: (1) temporomandibular joint (TMJ) clicking (13.26%); (2) TMJ pain (12.49%); (3) masticatory muscle tension (12.15%). The main clinical findings were myalgia (74%), TMJ clicking (60-62%), and TMJ arthralgia (31-36%). Risk factors such as clenching (60%) and bruxism (30%) were positively associated with TMJ pain and myalgia. Orthodontic treatment (20%) and wisdom tooth removal (19%) were positively associated with TMJ clicking, while jaw trauma (6%), tracheal intubation (4%) and orthognathic surgery (1%) were positively associated with TMJ crepitus, limited mandibular range of motion, and TMJ pain, respectively. In total, 42.88% of TMDs patients had other associated chronic diseases, most of them were mental behavioral or neurodevelopmental disorders (33.76%), namely, anxiety (20%) and depression (13%). The authors also observed a positive association of mental disorders with the degree of TMJ pain and myalgia. The online database seems to be a relevant scientific instrument for healthcare providers who treat TMDs. The authors expect that the EUROTMJ database can serve as a milestone for other TMDs departments.

Patient experience and satisfaction with different temporomandibular joint treatments: A retrospective study.

This retrospective study aimed to evaluate patient satisfaction with different temporomandibular joint (TMJ) treatments. Patients were included in the study according to the following inclusion criteria: 1) arthrogenous and/or myogenous temporomandibular disorders (TMD); 2) Dimitroulis classification category between 1-4; 3) conservative treatment without any improvement at least for 3 months; 4) indication for one of the following TMD treatments: injection of botulinum toxin; arthrocentesis; arthroscopy, and open surgery without alloplastic material; and 5) age ≥16 years. An independent satisfaction questionnaire with 11 queries was applied via phone call to all patients, which included 6 questions using a 10-point Likert scale and 5 yes-or-no questions. The principal outcome was the overall satisfaction with the clinical result of the treatment, and the secondary outcomes were specific satisfaction with the following: 1) pain reduction; 2) range of mouth opening; 3) chewing ability; 4) postoperative recovery; 5) the fulfillment of expectations; 6) treatment choice; 7) treatment recommendation to a friend; and 8) the need for another intervention. Anxiety and depression were also included as variables. Data were analyzed using descriptive statistics, non-parametric Kruskal-Wallis and Spearman rank correlation coefficient tests. A total of 120 patients (mean age 41.20 ± 17.78 years) were enrolled, comprising 109 women (90%) and 11 men (10%). The overall clinical satisfaction of all patients was 8.24 ± 2.23 (mean ± SD), and 97 patients (80.8%) stated that they would repeat the treatment. Patients submitted to TMJ arthrocentesis and arthroscopy had higher overall clinical satisfaction (9.09 ± 0.971 and 9.03 ± 1.13, p = 0.021) followed by open surgery (8.38 ± 1.84). The authors observed three statistically significant correlations: 1) overall clinical satisfaction and patient expectations (r = 0.803; p < 0.0001); 2) overall clinical satisfaction and post-treatment pain (r = -0.299; p = 0.003); and (3) the presence of depression and the need for further TMJ treatment (r = 0.186; p = 0.043). Within the limitations of the study it seems that patient expectations should be addressed ad initium, and the presence of a diagnosis of depression with concomitant TMD must alert the clinical team and patient for the possible need of additional treatment.

The ESTMJS (European Society of Temporomandibular Joint Surgeons) Consensus and Evidence-Based Recommendations on Management of Condylar Dislocation.

Although condylar dislocation is not uncommon, terminology, diagnostics, and treatment concepts vary considerably worldwide. This study aims to present a consensus recommendation based on systematically reviewed literature and approved by the European Society of TMJ Surgeons (ESTMJS). Based on the template of the evidence-based German guideline (register # 007-063) the ESTMJS members voted on 30 draft recommendations regarding terminology, diagnostics, and treatment initially via a blinded modified Delphi procedure. After unblinding, a discussion and voting followed, using a structured consensus process in 2019. An independent moderator documented and evaluated voting results and alterations from the original draft. Although the results of the preliminary voting were very heterogenous and differed significantly from the German S3 guideline (p < 0.0005), a strong consensus was achieved in the final voting on terminology, diagnostics, and treatment. In this voting, multiple alterations, including adding and discarding recommendations, led to 24 final recommendations on assessment and management of TMJ dislocation. To our knowledge, the ESTMJS condylar dislocation recommendations are the first both evidence and consensus-based international recommendations in the field of TMJ surgery. We recommend they form the basis for clinical practice guidelines for the management of dislocations of the mandibular condyle.

Biological Treatments for Temporomandibular Joint Disc Disorders: Strategies in Tissue Engineering.

The temporomandibular joint (TMJ) is an important structure for the masticatory system and the pathologies associated with it affect a large part of the population and impair people's lifestyle. It comprises an articular disc, that presents low regeneration capacities and the existing clinical options for repairing it are not effective. This way, it is imperative to achieve a permanent solution to guarantee a good quality of life for people who suffer from these pathologies. Complete knowledge of the unique characteristics of the disc will make it easier to achieve a successful tissue engineering (TE) construct. Thus, the search for an effective, safe and lasting solution has already started, including materials that replace the disc, is currently growing. The search for a solution based on TE approaches, which involve regenerating the disc. The present work revises the TMJ disc characteristics and its associated diseases. The different materials used for a total disc replacement are presented, highlighting the TE area. A special focus on future trends in the field and part of the solution for the TMJ problems described in this review will involve the development of a promising engineered disc approach through the use of decellularized extracellular matrices.

A randomized controlled preclinical trial on 3 interposal temporomandibular joint disc implants: TEMPOJIMS-Phase 2.

The effort to develop an effective and safe temporomandibular joint (TMJ) disc substitute has been one of the mainstreams of tissue engineering. Biodegradable customized scaffolds could approach safety and effectiveness to regenerate a new autologous disc, rather than using non-biodegradable materials. However, it is still technically challenging to mimic the biomechanical properties of the native disc with biodegradable polymers. In this study, new 3D tailored TMJ disc implants were developed: (1) Poly(glycerol sebacate) (PGS) scaffold reinforced with electrospun Poly(εcaprolactone) (PCL) fibers on the outer surface (PGS+PCL); (2) PCL and polyethylene glycol diacrylate (PEGDA) (PCL+PEGDA); and (3) PCL. The TMJ implants were tested in a randomized preclinical trial, conducted in 24 black Merino sheep TMJ, perfoming bilateral interventions. Histologic, imaging, and kinematics analysis was performed. No statistical changes were observed between the PGS+PCL disc and the control group. The PCL+PEGDA and PCL groups were associated with statistical changes in histology (p = 0.004 for articular cartilage mid-layer; p = 0.019 for structure changes and p = 0.017 for cell shape changes), imaging (p = 0.027 for global appreciation) and dangerous material fragmentation was observed. No biomaterial particles were observed in the multi-organ analysis in the different groups. The sheep confirmed to be a relevant animal model for TMJ disc surgery and regenerative approaches. The PCL and PCL+PEGDA discs presented a higher risk to increase degenerative changes, due to material fragmentation. None of the tested discs regenerate a new autologous disc, however, PGS+PCL was safe, demonstrated rapid resorption, and was capable to prevent condyle degenerative changes.

Multi-Material Implants for Temporomandibular Joint Disc Repair: Tailored Additive Manufacturing Production.

Temporomandibular disorders (TMD) affect a substantial percentage of the population, and the resources spent on their treatment are considerable. Despite the worldwide efforts around Tissue Engineering of the temporomandibular joint (TMJ) disc, a proper implant offering a long-term solution for TMD was not yet developed. To contribute to these efforts, this work is focused on the research and development of implants for TMJ disc regeneration. Scaffolds and hydrogels mimicking the TMJ disc of black Merino sheep were produced using different materials, poly(ε-caprolactone) (PCL) and poly(ethylene glycol) diacrylate (PEGDA), and as a multi-material structure. Different parameters of the scaffold manufacturing were assessed: the influence of processing temperatures, filament diameter, and biological environment. Moreover, two multi-material approaches were also assessed, scaffold with a hydrogel shell and scaffold with a hydrogel core. It was found that increasing temperature, the scaffolds' porosity decreases, increasing their compressive modulus. Decreasing the filament size (300 to 200 µm) decreases the compressive modulus to almost half of the initial value. Scaffolds with 200 µm filaments are the ones with a closer modulus to the native disc and their properties are maintained under hydrated conditions. The introduction of a hydrogel core in these scaffolds presented better mechanical properties to TMJ disc substitution.

The Role of Custom-made Subperiosteal Implants for Rehabilitation of Atrophic Jaws - A Case Report.

Rehabilitation of atrophic jaws with conventional endosseous implant-supported overdentures and immediate loading protocols still presents a challenge nowadays. Custom-made implants with immediate loading overdenture are emerging as a solution for atrophic jaws rehabilitation. The authors describe the case of a 44-year-old male with a history of congenital dental agenesis. A previous oral rehabilitation with an all-on-6 type, implant-fixed mandibular overdenture, had failed due to peri-implantitis. The patient was successfully treated with bimaxillary custom-made subperiosteal implants with an innovative design, combining subperiosteal and endosseous support. The authors consider custom-made subperiosteal implants, in selected patients, present several advantages over classic bone-grafting plus endosseous implant-placement techniques such as (1) possibility of a single-stage procedure with immediate loading in atrophic jaws; (2) possible primary option to approach atrophic jaws as a simpler and less time-consuming technique; and (3) a valid rescue option for failed endosseous implants. More long-term studies with large samples of patients will be necessary to confirm previous assumptions.

Preclinical randomized controlled trial of bilateral discectomy versus bilateral discopexy in Black Merino sheep temporomandibular joint: TEMPOJIMS - Phase 1- histologic, imaging and body weight results.

INTRODUCTION: The role of temporomandibular joint (TMJ) surgery is not well defined due to a lack of quality randomized controlled clinical trials, comparing different TMJ surgical treatments with medical and placebo interventions. The temporomandibular joint interposal study (TEMPOJIMS) is a rigorous preclinical trial divided in 2 phases. In phase 1 the authors investigated the role of the TMJ disc and in phase 2 the authors evaluated 3 different interposal materials. The present work of TEMPOJIMS - phase 1, aims to evaluate histopathologic and imaging changes of bilateral discectomy and discopexy in Black Merino sheep TMJ, using a high-quality trial following the ARRIVE guidelines. MATERIAL AND METHODS: This randomized, blinded and controlled preclinical trial was conducted in 9 Black Merino sheep to investigate histopathologic (primary outcome), imaging and body weight (secondary outcomes) changes after bilateral discectomy, discopexy and sham surgery. RESULTS: Significant changes were noticed in discectomy group, both in imaging and histopathologic analyses. Body weight changes were most pronounced in the discectomy group in the first 4 months after surgery with recovery to baseline weight 6 months after surgery. Discopexy induced nonsignificant changes in histopathologic, imaging and body weight analyses. CONCLUSIONS: This study reinforces the importance of developing an effective interposal material to substitute the TMJ disc and the need to explore the molecular mechanisms that underlie TMJ cartilage degeneration. The study design proposed in TEMPOJIMS represents an important progress towards future rigorous TMJ investigations.

Preclinical Animal Models for Temporomandibular Joint Tissue Engineering.

There is a paucity of in vivo studies that investigate the safety and efficacy of temporomandibular joint (TMJ) tissue regeneration approaches, in part due to the lack of established animal models. Review of disease models for study of TMJ is presented herein with an attempt to identify relevant preclinical animal models for TMJ tissue engineering, with emphasis on the disc and condyle. Although degenerative joint disease models have been mainly performed on mice, rats, and rabbits, preclinical regeneration approaches must employ larger animal species. There remains controversy regarding the preferred choice of larger animal models between the farm pig, minipig, goat, sheep, and dog. The advantages of the pig and minipig include their well characterized anatomy, physiology, and tissue properties. The advantages of the sheep and goat are their easier surgical access, low cost per animal, and its high tissue availability. The advantage of the dog is that the joint space is confined, so migration of interpositional devices should be less likely. However, each species has limitations as well. For example, the farm pig has continuous growth until about 18 months of age, and difficult surgical access due to the zygomatic arch covering the lateral aspect of joint. The minipig is not widely available and somewhat costly. The sheep and the goat are herbivores, and their TMJs mainly function in translation. The dog is a carnivore, and the TMJ is a hinge joint that can only rotate. Although no species provides the gold standard for all preclinical TMJ tissue engineering approaches, the goat and sheep have emerged as the leading options, with the minipig as the choice when cost is less of a limitation; and with the dog and farm pig serving as acceptable alternatives. Finally, naturally occurring TMJ disorders in domestic species may be harnessed on a preclinical trial basis as a clinically relevant platform for translation.

Effects of bilateral discectomy and bilateral discopexy on black Merino sheep rumination kinematics: TEMPOJIMS - phase 1 - pilot blinded, randomized preclinical study.

BACKGROUND: The temporomandibular joint interposal study (TEMPOJIMS) is a rigorous preclinical trial divided in 2 phases. In phase 1 the authors investigated the role of the TMJ disc and in phase 2 the authors evaluated 3 different interposal materials. The present work of TEMPOJIMS - phase 1, investigated the effects of bilateral discectomy and discopexy in sheep mastication and rumination. METHODS: This randomized, blinded and controlled preclinical trial (in line with the ARRIVE guidelines) was conducted in 9 Black Merino sheep to evaluate changes in mastication and rumination after bilateral discectomy and bilateral discopexy, by comparing with a sham surgery control group. The outcomes evaluated were: (1) absolute masticatory time; (2) ruminant time per cycle; (3) ruminant kinematics, and (4) ruminant area. After baseline evaluation and surgical interventions, the outcomes were recorded over 3 successive days, every 30 days, for 6 months. RESULTS: The first month after intervention seemed to be the critical period for significant kinematic changes in the discectomy and discopexy groups. However, 6 months after the bilateral interventions, no significant changes were noticed when compared with the control group. CONCLUSIONS: In this study, bilateral discectomy and discopexy had no significant effect in mastication and ruminatory movement. The introduction of kinematic evaluation presents a new challenge that may contribute to the improvement of future studies on the TMJ domain.

Bioengineered Temporomandibular Joint Disk Implants: Study Protocol for a Two-Phase Exploratory Randomized Preclinical Pilot Trial in 18 Black Merino Sheep (TEMPOJIMS).

BACKGROUND: Preclinical trials are essential to test efficacious options to substitute the temporomandibular joint (TMJ) disk. The contemporary absence of an ideal treatment for patients with severe TMJ disorders can be related to difficulties concerning the appropriate study design to conduct preclinical trials in the TMJ field. These difficulties can be associated with the use of heterogeneous animal models, the use of the contralateral TMJ as control, the absence of rigorous randomized controlled preclinical trials with blinded outcomes assessors, and difficulties involving multidisciplinary teams. OBJECTIVE: This study aims to develop a new, reproducible, and effective study design for preclinical research in the TMJ domain, obtaining rigorous data related to (1) identify the impact of bilateral discectomy in black Merino sheep, (2) identify the impact of bilateral discopexy in black Merino sheep, and (3) identify the impact of three different bioengineering TMJ discs in black Merino sheep. METHODS: A two-phase exploratory randomized controlled preclinical trial with blinded outcomes is proposed. In the first phase, nine sheep are randomized into three different surgical bilateral procedures: bilateral discectomy, bilateral discopexy, and sham surgery. In the second phase, nine sheep are randomized to bilaterally test three different TMJ bioengineering disk implants. The primary outcome is the histological gradation of TMJ. Secondary outcomes are imaging changes, absolute masticatory time, ruminant time per cycle, ruminant kinetics, ruminant area, and sheep weight. RESULTS: Previous preclinical studies in this field have used the contralateral unoperated side as a control, different animal models ranging from mice to a canine model, with nonrandomized, nonblinded and uncontrolled study designs and limited outcomes measures. The main goal of this exploratory preclinical protocol is to set a new standard for future preclinical trials in oromaxillofacial surgery, particularly in the TMJ field, by proposing a rigorous design in black Merino sheep. The authors also intend to test the feasibility of pilot outcomes. The authors expect to increase the quality of further studies in this field and to progress in future treatment options for patients undergoing surgery for TMJ disk replacement. CONCLUSIONS: The study has commenced, but it is too early to provide results or conclusions.