TY - JOUR
T1 - The theoretical optimal center of rotation for a temporomandibular joint prosthesis
T2 - A three-dimensional kinematic study
AU - van Loon, J.-P.
AU - Falkenström, C.H.
AU - de Bont, L.G.M.
AU - Verkerke, G.J.
AU - Stegenga, B.
PY - 1999/1/1
Y1 - 1999/1/1
N2 - A unilateral temporomandibular joint (TMJ) prosthesis may cause dysfunction of the contralateral, natural TMJ because of lack of translatorial movements of the prosthetic side. The natural translatorial capacity of the mandible can be restored in part by a TMJ prosthesis with a fixed center of rotation (CR), positioned inferiorly to the center of the natural mandibular condyle. The aim of this study was to determine the optimal position for the fixed CR of a unilateral TMJ prosthesis. A mathematical model was used to analyze different positions of the CR. These positions were evaluated based on the calculated rotation of the mandible in the frontal (Θf) and horizontal (Θh) plane, and the mediolateral movement (MLM) of the contralateral natural condyle. For current TMJ prostheses, with the CR positioned in the center of the natural condyle, Θh exceeded the natural limits. When the CR was shifted inferiorly, all parameters improved, particularly Θh. The addition of an anterior shift to an inferior shift slightly worsened Θf, while the addition of a posterior shift to an inferior shift slightly improved Θf and worsened MLM. We concluded that the functioning of the contralateral TMJ improves by shifting the CR inferiorly. An anterior shift may be added to remain within the contour of the mandibular ramus. The proposed position of the CR is 15 mm inferior to the center of the natural condyle, combined, if necessary, with an additional anterior shift of 5 mm.
AB - A unilateral temporomandibular joint (TMJ) prosthesis may cause dysfunction of the contralateral, natural TMJ because of lack of translatorial movements of the prosthetic side. The natural translatorial capacity of the mandible can be restored in part by a TMJ prosthesis with a fixed center of rotation (CR), positioned inferiorly to the center of the natural mandibular condyle. The aim of this study was to determine the optimal position for the fixed CR of a unilateral TMJ prosthesis. A mathematical model was used to analyze different positions of the CR. These positions were evaluated based on the calculated rotation of the mandible in the frontal (Θf) and horizontal (Θh) plane, and the mediolateral movement (MLM) of the contralateral natural condyle. For current TMJ prostheses, with the CR positioned in the center of the natural condyle, Θh exceeded the natural limits. When the CR was shifted inferiorly, all parameters improved, particularly Θh. The addition of an anterior shift to an inferior shift slightly worsened Θf, while the addition of a posterior shift to an inferior shift slightly improved Θf and worsened MLM. We concluded that the functioning of the contralateral TMJ improves by shifting the CR inferiorly. An anterior shift may be added to remain within the contour of the mandibular ramus. The proposed position of the CR is 15 mm inferior to the center of the natural condyle, combined, if necessary, with an additional anterior shift of 5 mm.
KW - Biomechanics
KW - Models
KW - Movement
KW - Temporomandibular joint
KW - Temporomandibular joint prosthesis
UR - http://www.scopus.com/inward/record.url?scp=0033278151&partnerID=8YFLogxK
U2 - 10.1177/00220345990780010501
DO - 10.1177/00220345990780010501
M3 - Article
C2 - 10065944
AN - SCOPUS:0033278151
SN - 0022-0345
VL - 78
SP - 43
EP - 48
JO - Journal of dental research
JF - Journal of dental research
IS - 1
ER -