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 .

A role for total alloplastic temporomandibular joint replacement in Gardner syndrome

Gardner syndrome (GS) is a rare autosomal dominant disorder that can present with craniomaxillofacial abnormalities. The identification of osteomas or craniomaxillofacial abnormalities can therefore serve as a marker of this condition, facilitating early referral and diagnosis. A 17-year-old female with GS was referred for the management of severe limited mouth opening, causing a major problem for routine endoscopy to monitor the gastrointestinal alterations of GS. Clinical and radiological evaluations showed multiple osteomas in the mandibular angle, condylar and coronoid regions bilaterally and maximum mouth opening of 8 mm. The patient underwent surgery for osteoma removal and bilateral customized alloplastic total temporomandibular joint replacement (TMJ-TJR). At the 2-year follow-up, the patient showed improvements in quality of life, with a maximum mouth opening of 34 mm, allowing routine upper endoscopy to be performed. This is the first report of GS, a rare and challenging craniomaxillofacial abnormality, treated with TMJ-TJR. A comprehensive overview of the patient's clinical presentation, diagnostic assessment, treatment planning, and outcomes is provided.

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.

Septic arthritis of the temporomandibular joint managed with arthroscopy: a case report

Septic arthritis of the temporomandibular joint (SATMJ) is an uncommon bacterial or fungal infection of the joint space. A 68-year-old man with underlying diabetes mellitus and a history of liver transplant, who was on immunosuppressants, presented to the oral and maxillofacial surgery department of the authors´ institution in Portugal. His main symptoms were arthralgia in the right temporomandibular joint, malocclusion, pre-auricular swelling and erythema. After clinical, laboratory, and imaging evaluations, diagnoses of chronic suppurative otitis media and SATMJ were made. The patient was managed with arthroscopy of the right temporomandibular joint, which allowed joint fluid collection for microbiological examination, lavage, and biopsy. The biopsy sample was positive for Pseudomonas aeruginosa. After surgery, targeted intravenous antibiotic treatment (amikacin) was given for 30 days. No recurrence of any complaints was reported after 12 months of follow-up.

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.

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.

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.

Temporomandibular joint arterial variability

The study aimed to investigate temporomandibular joint (TMJ) arterial variability. In this prospective study, the vasculature variability was studied using a 3D volume rendering CT angiography including random patients at two hospitals. A 16-quadrant (A1-D4) evaluation grid was developed using the Frankfurt plan as main reference. For each quadrant, the number of arterial ramus or branches was scored as clearly visible (2), partially visible (1), or not visible (0). A total of 50 patients were enrolled (mean age of 62.9 ± 16.0); 21 (42%) were men, and 29 (58%) were women. The authors observed bilaterally higher arterial density in the posterior aspect of the ascending ramus of the mandible (p < 0.0001), corresponding to quadrants B2 (5.92 ± 2.27 and 6.14 ± 2.56), B3 (9.76 ± 2.97 and 11.18 ± 2.86) and B4 (7.38 ± 2.78 and 8.10 ± 2.42). A strong correlation was found between the number of vessels and the variability of the region (r = 0.87, p = 0.00001). No differences were observed between men and women. Within the limitations of the study, arterial variability was observed in the TMJ territory. The posterior zone of the condyle and ramus is the most vascularized area, with great variability, representing an increased risk for surgical bleeding. Therefore, this knowledge seems to be particularly relevant for surgeons dedicated to TMJ and other facial surgery or facial/cerebral radiologic interventions. The authors encourage future studies to include larger samples and to identify thoroughly the arterial branches in this area.

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.

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.

Synovial entrapment in alloplastic temporomandibular joint replacement

Complications of alloplastic temporomandibular joint (TMJ) prostheses can lead to stress and anxiety for the patient and the surgical team, and prosthesis substitution is sometimes required. The aim of this case report is to describe the surgical finding of synovial entrapment with interposed fibrosis in a postoperative alloplastic TMJ revision, managed effectively with adequate surgical debridement. The authors believe that synovial entrapment needs to be considered as a possible postoperative complication of total joint replacement when no clear symptoms of infection, metal hypersensitivity, osteolysis, or heterotopic bone formation are present. The implications of synovial entrapment in TMJ alloplastic replacement remains relatively unpredictable and poorly understood.

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.

Hearing changes after temporomandibular joint arthroscopy: a prospective study

Temporomandibular Joint (TMJ) arthroscopy is considered an effective and safe minimally invasive surgical approach. While the long-term outcomes of arthroscopy tend to be positive and free of secondary effects, patients occasionally complain about their hearing following the treatment. The aim of this prospective study was to investigate possible hearing changes associated with TMJ arthroscopy. Pure-tone audiograms were performed in patients two weeks before TMJ arthroscopy and repeated six weeks after intervention. A total of 15 patients (mean age of 41.73±16.36) were enrolled; 25 TMJ arthroscopies were performed (five unilateral and ten bilateral). Statistically significant differences were found between preoperative and postoperative audiograms in the frequencies 256Hz (P=0.011) and 8kHz (P=0.058, borderline). For the frequency 256Hz the difference was favourable, but not superior to 5dB. For the frequency 8kHz, in three patients the TMJ arthroscopy resulted in a decrease of 10dB. However, no clinical hearing changes or complaints were observed in the involved patients. No differences in audiograms between level 1 or 2 arthroscopy were observed. The study reinforces the safety of the TMJ arthroscopy level 1 and 2 with the reported protocol. The authors recommend larger studies to validate the results, specially for frequency 8kHz.

Surgical complications related to temporomandibular joint arthroscopy: a prospective analysis of 39 single-portal versus 43 double-portal procedures

Temporomandibular joint (TMJ) arthroscopy is a minimally invasive surgical procedure proposed for diverse TMJ intra-articular disorders. A prospective study was designed with the aim of investigating intraoperative and postoperative surgical complications for single and double-portal TMJ arthroscopy. All interventions were performed by one surgeon with the same surgical protocol. A total of 55 patients were enrolled, resulting in 82 TMJ arthroscopies (28 unilateral and 27 bilateral). A total of 39 single portal (47.57%) and 43 double-portal (52.43%) arthroscopies were performed. No severe and irreversible complications were observed. Most complications were resolved after 4 weeks. Double-portal was associated with more complications (n=23) compared with single-portal TMJ arthroscopy (n=14), with a statistically significant difference found between single and double-portal TMJ arthroscopy in two intraoperative complications: intra-articular bleeding (P=0.044) and oedema of the preauricular area (P=0.042). This study confirms the safety of TMJ arthroscopy for single and double-portal procedures, with the authors suggesting a multicentre study, in an effort to minimize any possible bias.

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.

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.

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.

Early magnetic resonance imaging control after temporomandibular joint arthrocentesis

Temporomandibular joint (TMJ) lysis and lavage arthrocentesis with viscosupplementation are an effective treatment for acute disc displacement (DD) without reduction. Clinical success seems to be related to multiple factors despite the lack of understanding of its mechanisms. The authors present a case report of 17-year-old women with acute open mouth limitation (12 mm), right TMJ pain-8/10 visual analog scale, right deviation when opening her mouth. The clinical and magnetic resonance imaging (MRI) diagnosis was acute DD without reduction of right TMJ. Right TMJ arthrocentesis was purposed to the patient with lysis, lavage, and viscosupplementation of the upper joint space. After 5 days, a new MRI was performed to confirm upper joint space distension and disc position. Clinical improvement was obtained 5 days and 1 month after arthrocentesis. Upper joint space increased 6 mm and the disc remained displaced. We report the first early TMJ MRI image postoperative, with measurable upper joint space.