Lecture 02. Arrangement and Occlusion of Permanent Teeth PDF

Arrangement and Occlusion of Permanent Teeth 1602305 (Occlusion and TMJ) 20-October-2024 First semester-Third year Dr. Wafaa Alghonemy Week-2 Definition of occlusion Latin occlūs(us) (to close up, shu...

Arrangement and Occlusion of Permanent Teeth 1602305 (Occlusion and TMJ) 20-October-2024 First semester-Third year Dr. Wafaa Alghonemy Week-2 Definition of occlusion Latin occlūs(us) (to close up, shut) It is the relation of the upper and lower teeth during various activities of the mandible as in mastication and swallowing Normal occlusion is established by 2.5 to 3 years (deciduous) and at the end of 12 years (permanent). Definition of centric occlusion It is the relation of the upper and lower teeth when they are intercuspated together and the condyles are resting in the most retrusive unstrained position in the glenoid fossa. Centric Occlusal relation of the permanent teeth  Normal occlusion is established 12 by the end years of ? Occlusion of the anterior teeth Upper central incisor *The incisal ridge is free of contact *The mesial outline is in line with the mesial outline of 1. *The distal outline is centered 1 above the labial surface of 2. 1 2 The cingulum is above the labial embrasure between lower central and lateral incisors  Upper Lateral Incisor The incisal ridge is free of contact 2 The mesial outline is centered above the labial surface of 2. The mesial outline is centered above the labial surface of 2. 2 The distal outline is centered above the labial surface of 3 3 2 The cingulum is directly above the labial embrasure between lower 2 & 3 2 3 2  Upper canine The cusp is free of contact and is located in the labial embrasure of 3 & 4. The mesial outline lies above the tip of the cusp of 3. The distal outline is directly 3 above 4 buccal cusp tip. 3 4 The cingulum is free of contact and is located directly above the lingual embrasure of lower canine and first premolar. 3 4  Lower central incisor Labio incisal ridge strikes 1 lingually near the junction of the incisal and middle thirds The mesial outline is in line with the median line and with the mesial outline of 1. The distal outline is below the mesial two thirds of the 1. The cingulum is free of contact.  Lower lateral incisor The labio incisal ridge contacts both 1 & 2 at the junction of their middle and incisal thirds The mesial outline is identical with the junction of the distal and middle thirds of 1 1 2 The distal outline is centered below mesial half of 2 2 The cingulum is free of contact and lies below the embrasure between upper central and lateral incisors 1 2 2  Lower canine The cusp tip Labially is directly below the linguo-incisal embrasure of 2 & 3. The mesial outline is centered 2 3 below the lingual surfaces of 2. 3 The distal outline is centered below the lingual ridge of 3 The cingulum is 2 3 free of contact and is located directly below the lingual embrasure of 2 & 3 Occlusion of the premolars  Upper first premolar The buccal cusp is free of contact and is located within the buccal embrasure of 4 lower 4&5. The mesial outline is directly 4 above the buccal cusp of 4. The distal outline is directly 5 4 above the buccal cusp of 5. The lingual cusp is in contact with the distal 4 marginal ridge of 4 4 5  Upper second premolar The buccal cusp is free of contact and is located within the buccal embrasure of 5 & 5 6. The mesial outline is almost directly above the buccal cusp of 5. The distal outline is almost directly above the mesio 6 5 buccal cusp of 6. The lingual cusp is in contact with the distal triangular fossa of 5 If 5 is three-cusp type, The lingual cusp of 5 contacts with distal slope of the disto lingual cusp of 5.  Lower first premolar The buccal cusp contacts the mesial marginal ridge of 4. It 4 3 lies below the occlusal embrasure of 3 & 4. The mesial outline is placed directly below the lingual ridge of 3. 4 The distal outline is placed directly below the triangular ridge of the buccal cusp of 4. The lingual cusp is *short *free of contact. *it lies below the lingual 3 4 embrasure of the upper canine and first premolar. 4 5  Lower second premolar The buccal cusp contacts the mesial marginal ridge 5 4 of 5 below the occlusal embrasure of 4 & 5. The mesial outline is placed directly below the lingual ridge of 4. The distal outline is placed directly below the lingual 5 ridge of 5. The lingual cusp is free of contact and is located 4 5 below the lingual embrasure of 4 & 5. 5 If 5 is three cusp type: The mesio lingual cusp is free of contact. The distal slope of the disto lingual cusp strikes the lingual cusp of 5. Occlusion of the molars Generally: *The maxillary molars bear a disto-buccal relation to the mandibular molars. *The maxillary molars are smaller mesiodistally than the mandibular molars. *The maxillary molars are greater bucco-lingually than the mandibular molars.  Upper first molar The mesiobuccal cusp is free, lying Buccal view buccal to the mesio-buccal groove of 6 6 5 The distobuccal cusp is free, lying in the buccal embrasure of the lower 6 and 7. 6 5 The mesiolingual cusp is situated in the center of the Lingual view central fossa of 6. The distolingual cusp is in contact with the mesial 5 6 marginal ridge of 7... 5 6 7  Upper Second Molar The mesiobuccal cusp is free. Its triangular ridge rests in the 7 buccal groove of 7. 6 The distobuccal cusp is free and lies within the buccal embrasure of 7 and 8. 7 6 The mesio lingual cusp lies in the central fosse of Lingual view lower 7 The distolingual cusp strikes the 6 7 distal ridge of the distolingual cusp of 7.. 6 7  Upper Third molar The mesiobuccal cusp is free and its triangular ridge resting in the buccal groove of 8. The distobuccal cusp may be free or its triangular ridge contacts 8 on the distal slope of its disto-buccal cusp. The mesiolingual cusp rests in the central fossa of 8. If it has a disto-lingual cusp it strikes 8 on its distal marginal ridge. Lingual view  Upper molars MBC Free, in the opposing Buccal groove DBC Free in the opposing embrassure 8……. DB slope of DBC of 8 MLC Opposing central fossa DLC 6…….. MMR 7 7 ……..DR of DLC of 7 8 (if present) ……... DMR of 8  Lower first molar The mesio buccal cusp contacts the distal marginal ridge of the 5 and the mesial marginal ridge of 6. 6 5 The disto buccal cusp rests in the central fossa of 6 The distal cusp rests in the distal triangular fossa of 6. 6 5 The mesio lingual cusp is free of contact and is located in the lingual embrasure between the 5&6. 5 6 The distolingual cusp is free and is located immediately lingual to the lingual developmental groove of 6. 5 6  Lower second molar The mesiobuccal cusp contacts the marginal 7 6 ridges of 6 & 7. The distobuccal cusp is centered in the central fossa of the 7. 7 6  The mesiolingual cusp is free 7 of contact and is located in the lingual embrasure of 6 6 &7. The distolingual cusp is free of contact and it is located lingual to the lingual groove of the 7. 6 7  Lower third molar The mesio buccal cusp 8 contacts the mesial triangular fossa of 8. The disto buccal cusp rests in the central fossa of 8 8 The mesiolingual cusp is free of contact and is located in the lingual embrasure of 7 & 8. The distolingual cusp is free of contact and it is located lingual to the lingual groove of the 8.  Lower molars MBC: 6 DMR 5 7 DMR 6 8 M F MMR 6 MMR 7 DBC: Central Fossa of the opposing tooth. MLC: Free, Opposing Lingual embrassure. DLC: Free, Opposing Lingual Groove.