IADR Abstract Archives
Kinematic irregularities of total alloplastic temporomandibular joint replacements
Objectives: Despite acceptable mandibular function, patients with total alloplastic temporomandibular joint replacements (TJR) seldom reach norm jaw opening values (Giannakopoulos et al. 2012; Mercuri et al. 2007; Müller et al. 2013). Virtually no clinical studies have investigated in such patients kinematic irregularities predicted theoretically (van Loon et al. 1999). The objective of this study was therefore to describe the mobility of natural and alloplastic condyles in patients with existing TJR compared to controls.
Methods: 14 patients (6 operated unilaterally, 8 bilaterally, 10 F, age 24-72) and 15 healthy subjects (6 F, age 24-56) were included. Mandibular kinematics was analyzed by dynamic stereometry during opening and protrusion: anatomy was acquired by digital volume tomography (patients) or by magnetic resonance imaging (controls) and processed to 3D-models (AMIRA™ software); opening and protrusive movements (3× each) were tracked by means of the system developed at our lab. The central points (CP) between condylar medial and lateral poles were determined. The vector lengths (VL) between the resting positions (RP) and maximal excursions (ME) of CP were calculated. ANOVAs for repeated measurements were performed at a significance level of α=0.05.
Results: In prosthetic joints, VL for opening and protrusion was 5.4±2.6mm and 1.5±1.2mm. There was no significant difference between uni- or bi-lateral prostheses (p=0.802). VL in natural joints of patients was 17.6±9.0mm for opening and 9.5±5.6mm for protrusion. In controls, VL for opening was 9.0±4.0mm and 7.7±1.7mm for protrusion. Prosthetic joints moved significantly less than healthy joints (p<0.001). Conversely, natural joints in unilaterally operated patients moved significantly more than in the control group (p<0.001).
Conclusions: Prosthetic joints translate scarcely, which results in mandibular deviation in unilaterally operated patients and in limited opening range in bilateral surgeries. Larger excursions of natural joints in patients might compensate for the limited motion of the contralateral prosthetic joint.
Methods: 14 patients (6 operated unilaterally, 8 bilaterally, 10 F, age 24-72) and 15 healthy subjects (6 F, age 24-56) were included. Mandibular kinematics was analyzed by dynamic stereometry during opening and protrusion: anatomy was acquired by digital volume tomography (patients) or by magnetic resonance imaging (controls) and processed to 3D-models (AMIRA™ software); opening and protrusive movements (3× each) were tracked by means of the system developed at our lab. The central points (CP) between condylar medial and lateral poles were determined. The vector lengths (VL) between the resting positions (RP) and maximal excursions (ME) of CP were calculated. ANOVAs for repeated measurements were performed at a significance level of α=0.05.
Results: In prosthetic joints, VL for opening and protrusion was 5.4±2.6mm and 1.5±1.2mm. There was no significant difference between uni- or bi-lateral prostheses (p=0.802). VL in natural joints of patients was 17.6±9.0mm for opening and 9.5±5.6mm for protrusion. In controls, VL for opening was 9.0±4.0mm and 7.7±1.7mm for protrusion. Prosthetic joints moved significantly less than healthy joints (p<0.001). Conversely, natural joints in unilaterally operated patients moved significantly more than in the control group (p<0.001).
Conclusions: Prosthetic joints translate scarcely, which results in mandibular deviation in unilaterally operated patients and in limited opening range in bilateral surgeries. Larger excursions of natural joints in patients might compensate for the limited motion of the contralateral prosthetic joint.