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Difference between revisions of "Transverse Hinge Axis"
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==Occlusal Clutch and Cuspal Errors== | ==Occlusal Clutch and Cuspal Errors== | ||
We will first focus on the scientific philosophy behind the concept of the transverse hinge axis, commonly projected onto a sagittal plane and labeled '<math>_tHA</math>'. The main goal is to establish whether this concept should continue to be used as a reference in masticatory rehabilitation practices, or if it should be revised or abandoned to avoid clinical practice errors, as asserted by the RDC. A key aspect to explore is the phenomenon of rototranslation, a fundamental element of mandibular kinematics. This complex movement will be analyzed through practical examples and explanatory figures, demonstrating how tools such as the paraocclusal clutch can avoid the incorporation of significant errors in the registration of mandibular movements and occlusal dynamics. Precision in determining mandibular movements is crucial not only to ensure the accuracy of rehabilitative treatments but also to avoid discrepancies in prosthetic restorations. Small variations, if not adequately considered, can compromise the recording of movements and, consequently, alter the functionality of rehabilitation. A method of recording condylar tracings will be illustrated using the clutching with a paraocclusal | We will first focus on the scientific philosophy behind the concept of the transverse hinge axis, commonly projected onto a sagittal plane and labeled '<math>_tHA</math>'. The main goal is to establish whether this concept should continue to be used as a reference in masticatory rehabilitation practices, or if it should be revised or abandoned to avoid clinical practice errors, as asserted by the RDC. A key aspect to explore is the phenomenon of rototranslation, a fundamental element of mandibular kinematics. This complex movement will be analyzed through practical examples and explanatory figures, demonstrating how tools such as the paraocclusal clutch can avoid the incorporation of significant errors in the registration of mandibular movements and occlusal dynamics. Precision in determining mandibular movements is crucial not only to ensure the accuracy of rehabilitative treatments but also to avoid discrepancies in prosthetic restorations. Small variations, if not adequately considered, can compromise the recording of movements and, consequently, alter the functionality of rehabilitation. A method of recording condylar tracings will be illustrated using the clutching with a paraocclusal clutch, which has the advantage of not altering the vertical relationship between dental arches. This method will be compared with the mounting of an occlusal clutch to highlight the differences between the two approaches. | ||
*Figure 1: To precisely determine a geometric center of rotation or, more accurately, of rototranslation, it is necessary to connect a writing stylus to a frame attached to the mandible. This system follows mandibular movements during chewing cycles, tracing a path on a perpendicular plate fixed to a rigid support on the skull. This connection is generally made through the cementation of an intraoral | *Figure 1: To precisely determine a geometric center of rotation or, more accurately, of rototranslation, it is necessary to connect a writing stylus to a frame attached to the mandible. This system follows mandibular movements during chewing cycles, tracing a path on a perpendicular plate fixed to a rigid support on the skull. This connection is generally made through the cementation of an intraoral clutch, called an occlusal clutch. | ||
*Figure 2: The figure shows a typical paraocclusal | *Figure 2: The figure shows a typical paraocclusal clutch, which does not interfere with the maxillary occlusal surface, allowing for maximum intercuspation without causing a vertical lift or a rototranslation of the condylar joint. | ||
*Figure 3: The figure depicts the tracing generated from mandibular opening and closing movements and left mediotrusion using a paraocclusal | *Figure 3: The figure depicts the tracing generated from mandibular opening and closing movements and left mediotrusion using a paraocclusal clutch. Some key points are as follows: | ||
<blockquote>First point: A red point located on a horizontal line representing the 'Axis-Orbital' plane. This point corresponds to the guided hinge axis and is labeled as <math>P_c</math> (Paraocclusal clutch), with an orbital reference point indicated as <math>O_p</math> (Orbital point). The red point approximately represents the <math>_tHA</math> axis. | <blockquote>First point: A red point located on a horizontal line representing the 'Axis-Orbital' plane. This point corresponds to the guided hinge axis and is labeled as <math>P_c</math> (Paraocclusal clutch), with an orbital reference point indicated as <math>O_p</math> (Orbital point). The red point approximately represents the <math>_tHA</math> axis. | ||
Second point: Another point, located about 2 mm in protrusion, corresponds to a mandibular opening of about 4 mm, measured at the incisors, and is due to the use of an occlusal | Second point: Another point, located about 2 mm in protrusion, corresponds to a mandibular opening of about 4 mm, measured at the incisors, and is due to the use of an occlusal clutch between the arches. This point is labeled as <math>O_c</math> (Occlusal Clutch). | ||
Third point: At the end of the mandibular opening trace is point <math>H</math>. | Third point: At the end of the mandibular opening trace is point <math>H</math>. | ||
From these strategic points, important considerations can be made regarding the determination of the hinge axis using a paraocclusal or occlusal | From these strategic points, important considerations can be made regarding the determination of the hinge axis using a paraocclusal or occlusal clutch. In Figure 3, a line has been drawn from <math>P_c</math> to <math>H</math>, representing the angle of the Articular Eminence, calculated with Geogebra, yielding a value of <math>41.69^\circ</math> compared to an angle of <math>50.20^\circ</math> for the line drawn between <math>O_c</math> and <math>H</math>. | ||
The choice of using <math>P_c</math> or <math>O_c</math> can generate a significant error, with an angular variation of <math>8.51^\circ</math>, which can reach up to <math>10^\circ</math>, as indicated by Oliver Schierz et al.<ref>[https://www.researchgate.net/profile/Oliver-Schierz/publication/319390817_Impact_of_mounting_methods_in_computerized_axiography_on_assessment_of_condylar_inclination/links/5ecfad1992851c9c5e63ba15/Impact-of-mounting-methods-in-computerized-axiography-on-assessment-of-condylar-inclination.pdf?origin=publicationDetail&_sg%5B0%5D=5gcZcMPe-o4_Pl6wkh2xujLIHsSjxIskFKb2rDTsy5LK5G_iE-MroMtkjg0O9gUHRBkjnYu5GTqV-fxPRuinww.XRi95a2o7EJ4r8p3CoKKbPn6ghsFjZ4Jr3JU30vq9Uzz_e34x4HMd2fd9xEt4SGZWuK88KfPaaSfAINagYBlMA&_sg%5B1%5D=P6dZ5Xgw8ZYwG8EW4imuRv2P_BjeMIsu711me70-6nx-0D-yjv4t34n8KnBn_ciDfa5km_cLb0t_AhxuDKiNtTTwZOB2W7nuktpkvFGBvMJG.XRi95a2o7EJ4r8p3CoKKbPn6ghsFjZ4Jr3JU30vq9Uzz_e34x4HMd2fd9xEt4SGZWuK88KfPaaSfAINagYBlMA&_iepl=&_rtd=eyJjb250ZW50SW50ZW50IjoibWFpbkl0ZW0ifQ%3D%3D&_tp=eyJjb250ZXh0Ijp7ImZpcnN0UGFnZSI6InB1YmxpY2F0aW9uIiwicGFnZSI6InB1YmxpY2F0aW9uIiwicG9zaXRpb24iOiJwYWdlSGVhZGVyIn19 Oliver Schierz et al.]</ref> This error is transferred to the prosthetic phase, generating a spatial discrepancy in the cuspal position. </blockquote> | The choice of using <math>P_c</math> or <math>O_c</math> can generate a significant error, with an angular variation of <math>8.51^\circ</math>, which can reach up to <math>10^\circ</math>, as indicated by Oliver Schierz et al.<ref>[https://www.researchgate.net/profile/Oliver-Schierz/publication/319390817_Impact_of_mounting_methods_in_computerized_axiography_on_assessment_of_condylar_inclination/links/5ecfad1992851c9c5e63ba15/Impact-of-mounting-methods-in-computerized-axiography-on-assessment-of-condylar-inclination.pdf?origin=publicationDetail&_sg%5B0%5D=5gcZcMPe-o4_Pl6wkh2xujLIHsSjxIskFKb2rDTsy5LK5G_iE-MroMtkjg0O9gUHRBkjnYu5GTqV-fxPRuinww.XRi95a2o7EJ4r8p3CoKKbPn6ghsFjZ4Jr3JU30vq9Uzz_e34x4HMd2fd9xEt4SGZWuK88KfPaaSfAINagYBlMA&_sg%5B1%5D=P6dZ5Xgw8ZYwG8EW4imuRv2P_BjeMIsu711me70-6nx-0D-yjv4t34n8KnBn_ciDfa5km_cLb0t_AhxuDKiNtTTwZOB2W7nuktpkvFGBvMJG.XRi95a2o7EJ4r8p3CoKKbPn6ghsFjZ4Jr3JU30vq9Uzz_e34x4HMd2fd9xEt4SGZWuK88KfPaaSfAINagYBlMA&_iepl=&_rtd=eyJjb250ZW50SW50ZW50IjoibWFpbkl0ZW0ifQ%3D%3D&_tp=eyJjb250ZXh0Ijp7ImZpcnN0UGFnZSI6InB1YmxpY2F0aW9uIiwicGFnZSI6InB1YmxpY2F0aW9uIiwicG9zaXRpb24iOiJwYWdlSGVhZGVyIn19 Oliver Schierz et al.]</ref> This error is transferred to the prosthetic phase, generating a spatial discrepancy in the cuspal position. </blockquote> | ||
<center> <gallery widths="350" heights="282" perrow="2" mode="slideshow"> File:Epoc-0040 copia.jpg|'''Figure 1:''' Axiography performed through occlusal | <center> <gallery widths="350" heights="282" perrow="2" mode="slideshow"> File:Epoc-0040 copia.jpg|'''Figure 1:''' Axiography performed through occlusal clutch | ||
File:Axiography 1.jpg|'''Figure 2:''' | File:Axiography 1.jpg|'''Figure 2:''' Paraocclusal clutch | ||
File:Paraocclusal Clouth 1 .jpg|'''Figure 3:''' | File:Paraocclusal Clouth 1 .jpg|'''Figure 3:''' | ||
Representation of angular discrepancies due to the use of paraocclusal <math>P_c</math> and occlusal <math>O_c</math> | Representation of angular discrepancies due to the use of paraocclusal <math>P_c</math> and occlusal <math>O_c</math> clutch </gallery> </center> | ||
==Localization Error <math>_tHA</math> from Chord <math>s</math> and Sagitta <math>h</math>== | ==Localization Error <math>_tHA</math> from Chord <math>s</math> and Sagitta <math>h</math>== | ||