BDS 7130: Morphological Differences Between Primary And Permanent Teeth PDF

BDS 7130: Morphological differences between primary and permanent teeth Aim: The aim of this lecture is to describe the differences between primary and permanent teeth and how this influences management. Objectives: -Differentiate between the morphology of primary and permanent teeth as Subject Ti...

BDS 7130: Morphological differences between primary and permanent teeth Aim: The aim of this lecture is to describe the differences between primary and permanent teeth and how this influences management. Objectives: -Differentiate between the morphology of primary and permanent teeth as Subject Title Goes Here regards color, size, crown, root and pulp - Describe the differences in crown shape, width and contact area between primary and permanent teeth -Describe the differences in thickness of enamel, dentine and pulp between primary and permanent teeth -Understand how this influences restorative approaches and extraction in both dentitions Morphological differences between primary Morphological differences between primary and and permanent teeth permanent teeth Successor and corresponding teeth For the first primary molar D: the successor is the first premolar 4 while the corresponding tooth is the first permanent molar 6 For the second primary molar E: the successor is the second premolar 5 while the corresponding tooth is the second permanent molar 7 Morphological differences Between Primary and Permanent teeth 1. 2. 3. 4. 5. Size Color Crown Root Pulp 1. Size • Smaller in all dimensions • MD (mesiodistal) width of primary incisors and canines is less than their permanent successors • The MD width of the primary molars is wider than their successors(premolars) but smaller than their corresponding permanents. 1. Size (Cont.) Thickness of E and D in primary teeth is half the thickness in permanent teeth. Clinical consideration: The occlusal cavity in primary teeth must be shallower. 2. Colour Primary teeth color is bluish white The color of permanent teeth ranges from grayish white to yellowish white 3. Crown 1. Wider in MD diameter than in OG height Anterior teeth Posterior Teeth cup -shaped squat -shaped 3. Crown (cont.) 2. Primary molars are bulbous due to: A-Markedly constricted necks. B-Pronounced cervical ridges. Clinical consideration: 1. Difficulty in application of the matrix band. 2. Special care in the placement of the gingival seat in class II cavity preparation. 3. Crown (cont.) 3. The primary molars have narrow occlusal table (B and L surfaces converge sharply occlusally) Clinical consideration: The isthmus portion of a class ǁ amalgam filling is very narrow and liable to fracture Therefore the width of the isthmus portion should be 1/3-1/2 the intercuspal width. 4. The buccal and lingual inclines flatten above the cervical bulge. 3. Crown (cont.) 5. In primary teeth the contact is large ellipsoid and flattened area Clinical consideration: Wider proximal box 6.Cusp heights are less steep than permanent (more flexible interdigitation). 3. Crown (cont.) 7. The enamel cap in primary teeth is thinner and has a constant depth. 8. The enamel cap in primary molars ends abruptly at the CEJ (feather-edge in permanent). 3. Crown (cont.) 9. The enamel rods at the cervix slope occlusally in primary teeth instead of gingivally in permanent teeth. • Clinical consideration There is no need for beveling of gingival floor in class ǁ cavity preparation in primary molars. 4. Roots The roots of primary teeth are: a. Narrower mesiodistally. b. Longer and more slender in comparison to the crown (crown/root 1:2). c. Flare out near the cervix leaving no root trunk. 4. Root (cont.) d. Diverge as they reach the apex to envelop the permanent successor of posterior. Clinical consideration: Special care in extraction of primary molars with un-resorbed root. e. Curved roots, thin walls Clinical consideration: Difficult mechanical preparation of canals and care during mechanical preparation. 5. Pulp a. The pulp outline follows the DEJ more closely in primary than in permanent teeth. a. The pulp chambers are proportionally larger than permanent teeth . b. The pulp horns are higher in primary molars especially the mesial horn. Clinical consideration: Special attention should be taken when establishing the depth of cavities in primary teeth. 5. Pulp (cont.) The root canals of the primary molars show: d. More lateral branching and apical ramifications. Clinical consideration: This makes it impossible to remove all pulp tissue in the root canals during root canal therapy. e. The apical foramina in primary teeth are relatively wider than in permanent teeth. Primary teeth Permanent teeth References: • Dean, J.A., Avery, D.R. and McDonald, R.E., 2010. McDonald and Avery Dentistry for the Child and Adolescent 10th edition, 2010. Elsevier Health Sciences. • Mathewson R et al; Fundamentals of Pediatric Dentistry, 3rd edition, Quintessence publishing. • Reading material: Students are advised to review any relevant teaching provided in the first year. In addition they are advised to read relevant sections of the following texts: • Prevention and Management of Dental Caries in Children, Scottish Dental • Clinical Effectiveness Programmehttp://www.sdcep.org.uk/published-guidance/caries-in-children/ • Koch G et al; Pediatric Dentistry - a Clinical Approach; 3rd Edition, Wiley Blackwell • Welbury R et al; Paediatric Dentistry; 5th Edition, Oxford Press Aim: The aim of this lecture is to describe the differences between primary and permanent teeth and how this influences management. Objectives: -Differentiate between the morphology of primary and permanent teeth as Subject Title Goes Here regards color, size, crown, root and pulp - Describe the differences in crown shape, width and contact area between primary and permanent teeth -Describe the differences in thickness of enamel, dentine and pulp between primary and permanent teeth -Understand how this influences restorative approaches and extraction in both dentitions