5._DEN203_20F_W5_Jaw relations_ with you.pdf

DEN203 Prosthetic Dentistry II Lecturer: Dr. Rana Turunç Oğuzman & Dr. Demet Ayvalıoğlu E-posta: [email protected] Jaw Relations Altınbaş Üniversitesi Rana Turunç Oğuzman [email protected] DEN203 Protetik Diş Tedavisi 2 Jaw Relation Any spatial relationship of the maxil...

DEN203 Prosthetic Dentistry II Lecturer: Dr. Rana Turunç Oğuzman & Dr. Demet Ayvalıoğlu E-posta: [email protected] Jaw Relations Altınbaş Üniversitesi Rana Turunç Oğuzman [email protected] DEN203 Protetik Diş Tedavisi 2 Jaw Relation Any spatial relationship of the maxilla to the mandible or any one of the infinite relationships of the mandible to the maxilla. Jaw relations Vertical dimension refers to the length of the face It is maintained either by the occlusion of the teeth or the balanced tonic contraction of the opening and closing muscles of mandibular movements • Tooth : Acts as a vertical stop. • Musculature : Opening and closing muscles tend to be in a state of minimal tonic contraction. • If not measured accurately, the joint will be strained. • If the VD is altered, severe discomfort in both TMJ and muscles of mastication occurs • Patient’s esthetical appearance is related to VD Two measurable lengths of the face are important guides on deciding vertical relation and are referred to as : • Vertical dimension of rest or physiologic rest position (VDR). • Vertical dimension of occlusion (VDO). • Vertical separation of the jaws when the opening and closing muscles of mandible are in a state of minimal tonic contraction sufficient only to maintain posture. • The position assumed by the mandible when the head is in an upright position, the muscles are in equilibrium in tonic contraction and the condyles are in a neutral unstrained position is the physiologic rest position of the mandible. • Vertical height of the jaws when the teeth or occlusion rims are in contact. It is generally considered that the teeth should not be in contact when the jaws are at the vertical dimension of rest position. 2 to 4mm distance between the upper and lower teeth when the mandible is at physiologic rest position is called interocclusal distance (IOD) frequently referred to as the “free way space”. INCREASE IN VDO / DECREASE IN IOD • The chin-nose distance will increase, and then patients will have an appearance of open mouth. • Constant pressure to the basal seat area which will lead to bone resorption. • Soreness of the tissues of the basal seat. • “Clicking”, of dentures during speech. • Improper phonetics DECREASE IN VDO / INCREASE IN IOD • Potentially damaging to the TMJ. • The normal tongue space is limited. Facial distortion appears more noticeable with over closure that with the slightly opened closure because with over closure the chin appears to be closer to the nose, the commissure of the lips turns down and the lips lose their fullness. • The muscles of facial expression lose their tonicity and the face appears flabby instead of firm and full. • Over closure of jaws may lead to angular chelitis Horizontal Jaw Relation Primary Muscles of Mastication Horizontal jaw relation • Horizontal Jaw relation is the relationship of the mandible to the maxilla in a horizontal plane or it is the relationship of the mandible to the maxilla in an antero-posterior direction. Horizontal jaw relation It can be of two types: •Centric relation •Eccentric relation •Protrusive relation •Lateral relation •Left lateral •Right lateral Centric relation The most retruded relation of the mandible to the maxilla when the condyles are in the most posterior unrestrained position in the glenoid fossa from which lateral movements can be made, at any given degree of jaw separation. Centric Relation • A maxillomandibular relationship in which the condyles articulate with the thinnest avascular portion of their respective disks with the complex in the anteriorsuperior position against the slopes of the articular eminences. • This position is independent of tooth contact. • This position is clinically discernible when the mandible is directed superiorly and anteriorly and restricted to a purely rotary movement about a transverse horizontal axis. Centric Occlusion Is the relation of opposing occlusal surfaces that provide maximum intercuspidation . Centric occlusion with teeth present a tooth to tooth relation, wheras centric relation is a static relation , a bone to bone relation. Purpose of recording centric relation • It is a bone to bone relation and it is constant • It is repeatable and recordable and thus serves as a reliable guide for developing centric occlusion in complete dentures • It is related to the terminal hinge axis ,in CR condyles exhibit pure rotation without any translation Centric relation • Functional movements like chewing and swallowing can be carried out since it is the most unstrained position. Final act of masticatory stroke ends in centric relation • Reference relation • It is more definite than vertical relation since it is independent of tooth contact Centric relation • Functional movements like chewing and swallowing can be carried out since it is the most unstrained position. Final act of masticatory stroke ends in centric relation • Reference relation • It is more definite than vertical relation since it is independent of tooth contact Videos • Centric Relation, RCP, ICP and OVD for Complete Dentures https://www.youtube.com/watch?v=rBv1W5m1h2I • Mandibular Movements https://www.youtube.com/watch?v=uCA7YpS-sfU