Occlusal Relationship PDF

Occlusal Relationship Dr Sandeep Gupta Oral Biology Department Centric occlusion The relation of the upper and lower teeth when they are in maximum intercuspation during swallowing and the terminal position of the masticatory stroke. Centric relation Is a position of the mandible in which the condyl...

Occlusal Relationship Dr Sandeep Gupta Oral Biology Department Centric occlusion The relation of the upper and lower teeth when they are in maximum intercuspation during swallowing and the terminal position of the masticatory stroke. Centric relation Is a position of the mandible in which the condyles are resting in the most retrusive unstrained position in the glenoid fossa and related anteriorly to the distal slope of the articular eminence. 1. Dental arch form: Outline of the maxillary arch is larger than mandibular arch So, maxillary teeth overhang the mandibular teeth when the teeth are in centric occlusion Permits overbite and overjet relation ship 2. Overlap of teeth: Overbite: vertical relation of the upper teeth to the lower teeth in centric occlusion. Over jet: horizontal relation of the upper teeth to the lower teeth in centric occlusion. Importance: Prevent soft tissue biting Guide the mandible through various lateral movement Overbite enables the disocclusion of the posterior teeth during food incision and increases the efficiency of the anterior teeth in biting well. Overjet increases duration of occlusal contact in protrusive and lateral movements in incising and mastication. 3. Compensatory Curvatures of the dental arches: (Curved Occlusal Planes) The significant of these curve as guidance for mandible Movement to complement the condyle paths and for balance of mandible A. Curve of Spee B. Curve of Wilson C. Curve of monsoon A. Curve of Spee Incisal Ridges of the anterior teeth and the Buccal cusps of the posterior teeth follow a curve which end at the anterior surface of the condyle. when the arches were observed from a point opposite 1st Molar Curve of Spee Curve results form variations in axial alignment of lower teeth If the curve were extended, it would form a circle of about 4 inch diameter Long axis of each lower teeth is aligned nearly parallel to its individual arc of closure around the condylar axis The curve in maxillary arch is convex & concave in mandible B. Curve of Wilson Seen in Coronal plane. The occlusal surfaces of posterior teeth conform to a curved plane. The crowns of mandibular posterior teeth must incline to the lingual while the crowns of maxillary posterior teeth must incline toward the buccal. C. Curve of Monson It is obtained by extending the curve of spee & curve of Wilson to all cusps & incisal edges In vertical plane, mandiblular arch is curve e.g.  Sphere with 4 inch radius the center of which is present in the glabella Teeth are inclined because these can best withstand the Masticator force Bonwill’s Triangle Describe the mandible and found that the mandibular dental arch adapts itself to an equilateral triangle of 4 inches length. Apex at the mesial contact area of the lower central incisors Angles of the base at the centers of each condyle 5. Inclination and Angulation of roots of teeth The inclination of a tooth from a vertical axis in mesiodistal and faciolingual directions (Considered root inclination so the crown inclined in opposite direction ). importance: Proper occlusal function ( each tooth must be placed at the angle that best withstand forces during function ) FL angulations All teeth have lingual root inclination except the 2nd PM and mandibular M have buccal root inclination MD angulations All teeth have distally root inclination except the upper incisors teeth have slight mesially root inclination and the lower incisors have slight mesial or straight. 6. Functional form of the teeth at their incisal and occlusal thirds There are no flat planes on the incisal or occlusal surface of any of the teeth. The cusps and incisal ridges acts as cutting blades when they are come to contact in centric occlusion, the concave surface opposing the ridges in circumscribed points or areas and spaces appear all around this point which act as spillways or escapement space No flat planes. Cusps and incisal ridges act as cutting blades Curved surfaces come in to contact with curved surfaces ; may be concave or convex. In centric occlusion & various mandibular movements : curved surfaces come into contact at point or area and spaces appear all around the point of contact where the curved surfaces do not fit together Escapement spaces OR spillways Provided in teeth by cusps, ridges, DG , interdental spaces. its location and form differ when occlousal relation is changed. less space in centric occlusion and large space in lateral relation. 7. Facial and lingual Relations of Each Tooth in One Arch to Its Antagonist in the Opposing Arch in Centric Occlusion. In centric occlusion, each tooth occludes with two teeth in the opposing arch, except the mandibular central incisors and the maxillary third molars. Importance: 1. Prevent the over eruption of the teeth of the opposing arch. 2. prevent the mesial migration of the teeth in the same arch. 3. Distribute occlusal forces to several teeth. mesial migration 8-The Occlusal Contact and Intercusp Relations of all the Teeth During the Various Functional mandibular movements. Mandibular movements are: (rotating & translational) A.Symmetrical bilateral movements: Depression. Elevation. Protrusion. Retrusion. B.Asymmetrical bilateral movements: Right lateral movements. Left lateral movements. Physiological rest position of mandible/ vertical relation Amount of separation between maxilla & mandible when the mandible & all of its supporting muscles are in resting position Free Way Space “When the mandible is at the vertical dimension of rest position, a space is present between the occluding surface of maxillary teeth called intercuspal or freeway space” Free Way Space Which 2-5mm between the incisal & occlusal surface of maxillary & mandibular teeth In centric occlusion maxillary teeth overlap mandibular in anterior & cusp to fossa relation in posterior teeth Key of occlusion  MB cusp of permanent maxillary 1st molar overlaps MB groove of permanent 1st molar This is also called as Angle’s class I Occlusion Centric Occlusion It is also called intercuspal position or Convenience Occlusion Is maximum intercuspation or contact attained between maxillary & mandibular teeth Is a tooth to tooth contact Centric relation & centric occlusion should coincide in order to have perfect harmony between teeth, TMJ & neuromuscular system. Supporting cusps Buccal cusps of lower posteriors & lingual cusps of upper posteriors contact respective fossa  Support cusps  Support the vertical dimension Guiding cusps Buccal cusp of upper & lingual cusp of lower posteriors  Guiding cusp  Guide the teeth into occlusion Where supporting cusps contact with opposite teeth  Centric stops (in centric occlusion) Centric stop part of the tooth where supporting cusp comes to a stop in maximum intercuspation  e.g.– Central fossa of mandibular 1st molar where mesiolingual cusp of maxillary 1st molar occlude Protrusive relation Anterior  Edge to edge Posterior  Not in contact This indicates position of mandible  Moves anteriorly & downward Bring teeth forward Measurement of anterior  Incisal guidance  condyle moves for Protrusive relation Lateral Relation Left side movement Left side  Working side Right side  Balancing side On working side  Contact No contact  On balancing side in natural dentition The masticatory cycle of posterior teeth: The working side shows the buccal cusps of maxillary and mandibular teeth to be in contact. The balancing side shows contact of lingual cusps of the maxillary teeth with the buccal cusps of mandibular teeth. Then both sides move to centric occlusion. Working side Balancing side The masticatory cycle of anterior teeth: In bitting The functioning side is located at the anterior teeth The balancing side at the posterior teeth. Thank You