3- final NGU access to posteriors [Autosaved]_9bb52a66bdf123a171db1e6f4812ee21.pdf
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Access To Root Canal System :Posterior teeth BDS 8127 Date : xx / xx / xxxx Aims: The educational aims of this lecture are to explain the pulp space morphology of posterior teeth to eastablish an understanding of the shape of access to root canals in those teeth Objectives: On completion of this...
Access To Root Canal System :Posterior teeth BDS 8127 Date : xx / xx / xxxx Aims: The educational aims of this lecture are to explain the pulp space morphology of posterior teeth to eastablish an understanding of the shape of access to root canals in those teeth Objectives: On completion of this lecture, the student should have an understanding of how to assess the root canal system in posterior teeth keeping in mind the pulp space morphology Pulp Space Morphology of Premolar Teeth Pulp anatomy: 1-Number of roots. 2- Number of root canals. 3- Number of pulp horns. 4- Access cavity and outline form 5-Mesiodistal dimension and bucco-lingual dimension. 6- Cross section of the root. Maxillary 1st Premolar 1- Number of roots: •Two roots 60% •One root 38% •Three roots 2% 2- Root canal type: Two roots : each has type I One root: type III most frequent type II less frequent type I the least frequent Three root each has type I 3- Number of pulp horns: Two pulp horns (buccal more prominent than palatal) 4-Access cavity preparation & outline form: Oval in shape on the occlusal surface. 5-Mesiodistal dimension and buccolingual dimension • Buccolingual view is wider than mesiodistal one. • Mesio distal direction narrow resembling the upper canine. 6- Root Cross-section Cervical third: oval, kidney shape or figure 8 shape being wider B-L than M-D. Middle third :slightly ovoid. Apical third: round cross section . •With two roots (type I): Apical Middle Cervical Maxillary 2nd Premolar 1-Number of roots: One root Two roots 85% 15% 2-Number of root canals: • One root: type I most frequent(50%) type II less frequent type III least frequent •Two roots: each has type I 3- Number of pulp horns:) 2 pulp horns( 1buccal and 1 palatal) 4- Access cavity preparation & outline form: Oval in shape on the occlusal surface. 5-Mesiodistal dimension and buccolingual dimension •Pulp chamber narrow mesiodistally . •Two pulp horns one buccal & one palatal. 6- Root cross section: Cervical third: oval, being wider B-L than M-D. Middle third :slightly ovoid. Apical third: round cross section . Apical middle cervical Mandibular 1st Premolar 1- Number of roots : • Mainly single root rarely two roots 1 buccal and 1 lingual. 2- Canal type One root 75% (type I) 25% (Type II,III,IV) Two roots one canal is present in each root 3- Number of pulp horns: Two pulp horns (buccal more prominent than lingual) 4- Outline form& access cavity: Ovoid on the occlusal surface slightly towards the buccal cusp. 5-Mesiodistal dimension and buccolingual dimension •Mesiodistally: Narrow simulating lower canine •Buccolingually: wide with prominent buccal pulp horn. 6-Root cross section Cervical third: oval, being wider B-L than M-D. Middle third :slightly ovoid or round. Apical third: round cross section. Type I cervical middle Apical Mandibular 2nd Premolar 1- Number of roots : •Mainly single root rarely two roots one buccal and lingual 2- Canal type: One root 85% (Type I) •type III, Type II ,Type IV 15% Two roots type I 3- Number of pulp horns: Two pulp horns (buccal more prominent than lingual) 4- Outline form & access cavity: Ovoid on the occlusal surface 5-Mesiodistal dimension and buccolingual dimension •Similar to mandibular first premolar except that lingual pulp horn is more prominent under well developed lingual cusp 6-Root cross section Cervical third: oval, being wider B-L than M-D. Middle third :slightly ovoid or round. Apical third: round cross section Type I cervical middle Apical Access Cavity Preparation for Premolar Teeth (Step by Step) Coronal cavity preparation of maxillary and mandibular premolars: • The initial penetration is carried out on the occlusal surface in the center of the central groove. • • • A regular length round bur is aligned parallel to long access of the tooth. Deroofing and extending the cavity buccolingually is then carried out using a round bur or tapered stone with round end or EndoZ bur. Working from inside the chamber to the outside • • Flaring, smoothening and finishing of the cavity are achieved using tapered stone or EndoZ bur. Care should be given to keep the mesiodistal dimension narrow to avoid perforation at the cervical region Oval Ovoid Errors in Access cavity Preparation Pulp Space Morphology of Molar Teeth Maxillary 1st Molar 1-Number of roots. 2- Number of root canals. 3- Number of pulp horns 4- Access cavity and outline form Shape triangle base buccally or quadrilateral MB orifice: under MB cusp tip DB orifice: 2mm distal & palatal to MB P orifice: base of ML cusp (same straight line palatal to DB orifice Extra canal: MB2 (in a groove mesial and palatal to MB1 tail of a coma) 5-Mesiodistal dimension and bucco-lingual dimension. 6- Cross section of the root. P MB DB D 96% II, M III Mesial 2/3 Mesial 2/3 Triangular Rhomboid MB orifice DB orifice MB2 orifice P orifice Maxillary 2nd Molar 1-Number of roots. 2- Number of root canals. 3- Number of pulp horns. 4- Access cavity and outline form Shape triangle base buccally MB orifice: under MB cusp tip DB orifice: 2mm distal & palatal to MB P orifice: Base of ML cusp (same straight line palatal to DB orifice) 5-Mesiodistal dimension and bucco-lingual dimension. 6- Cross section of the root. 3 Roots: 90% ,2 Roots: 10% B & P 1 Root: extremely rare Mandibular 1st Molar 1-Number of roots. 2- Number of root canals. 3- Number of pulp horns 4- Access cavity and outline form Shape triangle base mesially or quadrilateral MB orifice: under MB cusp tip ML orifice: 2mm lingual to MB D orifice: 1mm distal to central fossa Extra canal: 2 distal canals (DB & DL) 5-Mesiodistal dimension and bucco-lingual dimension. 6- Cross section of the root. 2Roots (M+D) Mesial root: 90%III , 10%II (MB, ML) Distal root: 60% I , 40%II, III (DB, DL) M D MB ML Mandibular 2nd Molar 1-Number of roots. 2- Number of root canals. ( 3R.C, 4 R.C, 2 R.C, or rarely 1 R.C) 3- Number of pulp horns 4- Access cavity and outline form Shape triangle base mesially or quadrilateral MB orifice: under MB cusp tip ML orifice: 2mm lingual to MB D orifice: 1mm distal to central fossa 5-Mesiodistal dimension and bucco-lingual dimension. 6- Cross section of the root. Two roots: 76% Mesial root II or III (most frequent) I (least) Distal root: I One root: 21.8% Three roots: 2.2% D C-shaped canal: Most commonly occur in Md 2nd molar Ribbon shaped orifice Access Cavity Preparation for Molar Teeth (Step by Step) Practical steps Shape: Site: Upper Lower Size: Ridges Mainly in the Mesial 2/3 Mainly in the Mesial 2/3 P Whatever the tooth type was, the Basic steps are the same Gaining Access De-Roofing Flaring Cervical triangle Extra canals in upper and lower first molars MB2 96% 2 distal canals 40% Troughing Detection Clinically & Radiographically How can you differentiate between 1- roof and floor Cervical line Convex Color Dentine map 2- mesial from distal MMR is higher than DMR Roots are curved towards the distal Errors in Access cavity Preparation Underextended Overextended Perforation Underextended Aims: The educational aims of this lecture are to explain the pulp space morphology of posterior teeth to eastablish an understanding of the shape of access to root canals in those teeth Objectives: On completion of this lecture, the student should have an understanding of how to assess the root canal system in posterior teeth keeping in mind the pulp space morphology Reading material: The dental reference manual, Geraldine M. Weinstein, springer 2017 (Chapter 12) Essential skills for dentists, Peter A.Mossey et al, Oxford, 2006 (Chapter 2.6) Endodontics, Kishor Gulabivala and Yuan-Ling NG, Mosby Elsevier 2014 Harty`s endodontics in clinical practice, Bun San Chong, Elsevier 2017 Clinical endodontics, Lief Tronstad, Thieme 2009 (main reference) Thank you Date : xx / xx / xxxx
