Temporomandibular Joint Gape Angles in Normal and Painful Domestic Felines.

The purpose of this study was to determine and compare the gape angles (temporomandibular joint range of motion with mouth opening) of conscious and anesthetized domestic felines and to compare gape angles with and without evidence of oral pain. This prospective study evaluated the gape angle of 58 domestic felines. The cats were grouped into painful (n = 33) and nonpainful cohorts (n = 25) and gape angles were compared during conscious and anesthetized conditions. Gape angles were determined based on measurements of the maximal interincisal distance and lengths of the mandible and maxilla followed by calculation of the law of cosines. The mean feline gape angle (standard deviation) was determined to be 45.3° (8.6°) and 50.8° (6.2°) for conscious and anesthetized felines respectively. There was no significant difference between painful and non-painful feline gape angles during conscious (P = .613) or anesthetized (P = .605) evaluations. There was a significant difference between anesthetized and conscious gape angles (P < .001) for both painful and non-painful cohorts. This study determined the standardized, normal feline temporomandibular joint (TMJ) gape angle in both conscious and anesthetized states. This study suggests that the feline gape angle is not a useful indicator of oral pain. By determining the feline gape angle, which was previously unknown, further evaluation of its utility as a non-invasive clinical parameter for evaluation of restrictive TMJ motions as well as its use for serial evaluations may be pursued.

Combined Gap and Interpositional Arthroplasty Utilizing Three-Dimensional Printed Model in a Dog with Temporomandibular Joint Ankylosis and Pseudoankylosis.

Objective: To report the surgical treatment of a canine with both ankylosis and pseudoankylosis of temporomandibular joint (TMJ). Methods: The patient presented for inability to open his mouth. Facial asymmetry with normal dental occlusion was appreciated and computed tomography (CT) was performed. CT was used to diagnose ankylsosis and pseudoankylosis of left TMJ secondary to chronic maxillofacial trauma. A gap arthroplasty followed by interpositional arthroplasty using temporalis muscle fascia was performed to remove the site of fusion and prevent re-ankylosis between remaining cut boney surfaces. A three-dimensional (3D) printed skull for surgical planning and intraoperative spatial localization was employed. Results: Following preoperative and intraoperative evaluation of the 3D printed skull, the surgery was performed successfully without major complications. The patient's TMJ range of motion was markedly improved and remains improved as noted by inter-incisal distance measurements, ability to pant, and ease of chewing. Conclusion: A combined Gap and interpositional arthroplasty was assisted with the use of a 3D printed skull and immediately resulted in improved TMJ range of motion and patient quality of life. Three-month postoperative CT revealed stable ostectomies with no complications, with the exception of left-sided disuse masticatory muscle atrophy. Long-term follow-up is warranted. Clinical Significance: Three-dimensional printed skull models may be utilized preoperatively and intraoperatively to determine individual variants and landmarks, especially in cases where anatomical structures are difficult to recognize. Gap arthroplasty with interpositional myofascial transposition is an option for a patient with both anklyosis and pseudoankylosis of the TMJ.