Handout Normal Occlusion PDF

8/1/24 NORMAL OCCLUSION NORMAL OCCLUSION vs IDEAL OCCLUSION 1 2...

8/1/24 NORMAL OCCLUSION NORMAL OCCLUSION vs IDEAL OCCLUSION 1 2 Line of Occlusion Angle’s Concept (Upper) a smooth (catenary) curve passing through the central fossa of each upper molar and across the cingulum of upper canine and incisor teeth 3 4 Line of Occlusion Ideal Occlusion (Lower) smooth (catenary) curve that runs along the buccal perfect occlusion cusps and incisal edges of never attained in nature the lower teeth hypothetical goal for orthodontists 5 6 1  8/1/24 1. MOLAR RELATIONSHIP 6 KEYS TO NORMAL OCCLUSION 1. Molar Relationship 2. Crown Angulation 3. Crown Inclination 4. Rotations 5. Spacing 6. Occlusal Plane Lawrence Andrews Improper Improved More improved 7 8 1. MOLAR RELATIONSHIP 1. MOLAR RELATIONSHIP 1. MBC of U6 occludes in the groove between mesial and middle cusps of L6 2. Distal surface of DBC of U6 occludes with the mesial surface of MBC of L7 Proper Molar Relationship 9 10 1. MOLAR RELATIONSHIP 1. MOLAR RELATIONSHIP 11 12 2  8/1/24 Long Axis of Clinical Crown (LACC) 2. CROWN ANGULATION mesiodistal tip gingival portion of LACC is distal to the vertical line - long axis of the incisal portion clinical crown (LACC) expressed in degrees (+ or -) LA spot - center of long axis of + reading = gingival portion of clinical crown (LACC) LACC is distal to the incisal portion - reading = gingival portion of the LACC is mesial to the incisal portion 13 14 2. CROWN ANGULATION 2. CROWN ANGULATION the degree of angulation depends on the type of tooth 15 16 2. CROWN ANGULATION 2. CROWN ANGULATION which tooth with the greatest angulation? least angulation? horizontal plane reference = line passing through LA spots vertical plane reference = perpendicular to the horizontal plane 17 18 3  8/1/24 3. CROWN INCLINATION 3. CROWN INCLINATION labiolingual or buccolingual + reading inclination of LACC gingival portion of the tangent line or of the crown is lingual to the incisal portion expressed as + or - degrees, representing the angle formed - reading by the line which is 90° to OP gingival portion of the tangent and a line tangent to the line or of the crown is labial to bracket site the incisal portion 19 20 3. CROWN INCLINATION 3. CROWN INCLINATION (Anterior Teeth) (Anterior Teeth) overlay spaces resulting from normally occluded posterior teeth and insufficiently inclined anterior teeth are often blamed on tooth size discrepancy Improperly inclined anterior crowns Properly inclined anterior crowns, results in upper contact points being contact points move distally mesial 21 22 3. CROWN INCLINATION 3. CROWN INCLINATION (Anterior Teeth) Upper Posterior Teeth for upper canine through molars lingual crown inclination in upper posterior teeth constant/similar from canine thru second premolars slightly more pronounced in molars 23 24 4  8/1/24 3. CROWN INCLINATION 4. ROTATIONS Lower Posterior Teeth for lower canine through molars no rotations lingual inclination progressively rotated increases from canines through premolars/molars second molars = occupy more space in the arch 25 26 5. SPACING 6. OCCLUSAL PLANE flat occlusal plane to slight curve of Spee intercuspation is best when occlusal plane is flat no spaces contacts points are tight 27 28 Deep Curve of Spee Reverse Curve of Spee results in more contained area for upper teeth, making allows excessive space for each tooth to be intercuspally normal occlusion impossible placed 29 30 5  8/1/24 RETRUDED CONTACT POSITION (RCP) contact of a tooth or teeth along the retruded path of closure initial contact of a tooth OCCLUSION or teeth during closure around a transverse horizontal axis PGT 10ed, 2023 31 32 INTERCUSPAL POSITION (ICP) CENTRIC RELATION (CR) maximal intercuspal position (MIP) the complete intercuspation a maxillo-mandibular of opposing teeth relationship independent of tooth contact, in which independent of condylar the condyles articulate in position the anterior-superior the best fit of the teeth position against the regardless of condylar posterior slopes of the position articular eminence PGT-10ed, 2023 33 34 CR to MIP 35 36 6  8/1/24 CANINE GUIDANCE GROUP FUNCTION multiple contact relations between form of mutually protected the maxillary and mandibular teeth in articulation in which horizontal lateral movements on the working- and vertical overlap of canine side whereby simultaneous contact of teeth disclude the posterior several teeth acts as a group to teeth in excursive mov’t of distribute occlusal forces (PGT, 2023) mandible (GPT, 2023) 37 38 MUTUALLY PROTECTED ARTICULATION an occlusal scheme in which the posterior teeth prevent excessive contact of the anterior teeth in maximal intercuspal position, and the anterior teeth disengage the posterior teeth in all mandibular excursive movements. (PGT, 2023) Teeth of the anterior and posterior dentitions protect each other during function 39 7