DENTITION IN MAMMALS B.Sc. (H), SEM II:
Description: DENTITION IN MAMMALS B.Sc. (H), SEM II: ZOOL-H-DC4-T Dr. Dip Mukherjee Assistant Professor of Zoology S.B.S. Government College, Hili Delivered on: 04.01.2020 Introduction Dentition is the arrangement of teeth in the upper and lower jaws,
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slide1. DENTITION IN MAMMALS B.Sc. (H), SEM II: ZOOL-H-DC4-T
Dr. Dip Mukherjee
Assistant Professor of Zoology
S.B.S. Government College, Hili
Delivered on: 04.01.2020<br>
slide2. Introduction Dentition is the arrangement of teeth in the upper and lower jaws, mainly on the premaxilla, maxilla and dentary bones.
Adult platypus (Ornithorhynchus sp.), spiny anteater (Echidna sp.)- No true teeth.
Absence of teeth: Myrmecophaga sp., Balaena sp., Balaenoptera sp. etc.<br>
slide3. Origin and structure Origin: Denticles, near the margins of mouth as ossification in the integument.
Two parts: Crown (exposed part, above root) and Root (hidden part, anchored to alveolus of jaw bone).
Central pulp cavity (blood vessels, nerves, connective tissue), junction of crown and root is neck.
Enamel (thin, hard, shiny) covers crown (hardest and heaviest tissue); Dentine (hard, dermal, bony layer); Cement (acellular, non-vascular, covers root); pulp cavity lined by bone cells called odontoblasts.<br>
slide4. Types of Dentition<br>
slide5. Types of teeth Incisors: conical, single root, monocuspid; cutting & cropping; chisel-shaped, open rooted, grows continuously through life (rodents, lagomorphs)
Canines: large pointed, long crowned, single root; -nt in rodents (gap b/w i & pm: diastema)
Premolars: bicuspid, 2 roots; grinding
Molars: 2/more roots, several cusps; crushing; pm+m=cheek teeth; fissipeds: last upper pm & 1st m in lower jaw with chisel-shaped cusps called as carnassial teeth; last molar of humans: wisdom tooth.<br>
slide6. Cusp patterns of cheek teeth<br>
slide8. Dental Formula Equation to express number of teeth.
Number of each type of tooth in each half of upper & lower jaw.
Upper jaw (numerator), lower jaw (denominator); separated by horizontal line.
Indicated by letters i(incisors), c(canines), pm(premolars), m(molars).<br>
slide9. Unusual specialised teeth Elephant’s tusk: 2nd pair of incisors in the upper jaw.
Pig’s tusk: Upper canines.
Male Barking deer’s tusk: Enlarged canines.
Walrus’s tusk: Modified upper canines.<br>
Dr. Dip Mukherjee
Assistant Professor of Zoology
S.B.S. Government College, Hili
Delivered on: 04.01.2020<br>
slide2. Introduction Dentition is the arrangement of teeth in the upper and lower jaws, mainly on the premaxilla, maxilla and dentary bones.
Adult platypus (Ornithorhynchus sp.), spiny anteater (Echidna sp.)- No true teeth.
Absence of teeth: Myrmecophaga sp., Balaena sp., Balaenoptera sp. etc.<br>
slide3. Origin and structure Origin: Denticles, near the margins of mouth as ossification in the integument.
Two parts: Crown (exposed part, above root) and Root (hidden part, anchored to alveolus of jaw bone).
Central pulp cavity (blood vessels, nerves, connective tissue), junction of crown and root is neck.
Enamel (thin, hard, shiny) covers crown (hardest and heaviest tissue); Dentine (hard, dermal, bony layer); Cement (acellular, non-vascular, covers root); pulp cavity lined by bone cells called odontoblasts.<br>
slide4. Types of Dentition<br>
slide5. Types of teeth Incisors: conical, single root, monocuspid; cutting & cropping; chisel-shaped, open rooted, grows continuously through life (rodents, lagomorphs)
Canines: large pointed, long crowned, single root; -nt in rodents (gap b/w i & pm: diastema)
Premolars: bicuspid, 2 roots; grinding
Molars: 2/more roots, several cusps; crushing; pm+m=cheek teeth; fissipeds: last upper pm & 1st m in lower jaw with chisel-shaped cusps called as carnassial teeth; last molar of humans: wisdom tooth.<br>
slide6. Cusp patterns of cheek teeth<br>
slide8. Dental Formula Equation to express number of teeth.
Number of each type of tooth in each half of upper & lower jaw.
Upper jaw (numerator), lower jaw (denominator); separated by horizontal line.
Indicated by letters i(incisors), c(canines), pm(premolars), m(molars).<br>
slide9. Unusual specialised teeth Elephant’s tusk: 2nd pair of incisors in the upper jaw.
Pig’s tusk: Upper canines.
Male Barking deer’s tusk: Enlarged canines.
Walrus’s tusk: Modified upper canines.<br>