B17 - Teeth, blood supply and innervation, development

Question 1

Give the structures to mention of dentes

Answer 1

• Corpus dentis
• Corona dentis (Crown, civered by enamel and der´marcated from the root by the neck)
• Infundibulum dentis (Invagination of enamel on the occlusal surface of incisors (su, ru), premolars and molars (ru, eq))
• Cervix dentis (Neck of the tooth, constriction between crown and root)
• Radix dentis (Not covered by enamel)
• Apex radicis dentis
• Facies occlusalis (Meets the teeth of the opposite jaw)
• Facies vestibularis (Outer surface, directed towards the tongue)
• Facies lingualis (Inner surface, directed towards the tongue)
• Facies contactus (Related to the adhacent teeth in the same dental arch)
  
  • Facies mesialis
  • Facies distalis
• Cavum dentis [pulpare] (Cavity of the tooth that contains the pulp)
  
  • Cavum coronale dentis
  • Canalis radicis dentis
• Foramen apicis dentis (Orifice of the canalis radicis dentis)
• Pulpa dentis (Pulp of the tooth)
  
  • Pulpa coronalis (Pulp in the crown)
  • Pulpa radicularis (Pulp in the root canal)
• Dentinum (Dentin, main substance of the tooth)
• Enamelum (Hard white substance covering the dentin in the crown or the body)
• Cementum (Bone-like substance that covers the root)
• Periodontium (Connective tisse that attaches the tooth and gingiva to the alveolus)
• Arcus dentalis superior (Arch formed by all of the upper teeth)
• Arcus dentalis inferior (Arch formed by all of the lower teeth)
• Diastema (Space between two adjacent teeth in the same dental arch, usually between incisors and premolars)
• Dentes incisivi (First 3 teeth on either side of the median plane)
• Dentes canini (ø ru) (Between incisors and premolars)
• Dentes premolares (First 4 cheek teeth)
  
  • Dens lupinus (eq) (Wolf tooth, 1^st premolar)
• Dentes molares (Last 3 teeth in each jaw)
• Dens sectorius (ca) (Largest cutting tooth in each jaw, last upper premolar and 1^st lower molar)
• Dentes decidui (Milk teeth)
• Dentes permanentes (Permanent teeth)
• Diphyodonty (Replacement of the teeth first erupted (milk teeth)
• Polyphyodonty (Multiple succession)
• Thecodont (Teeth are implanted in sockets set along the margin of the jaws)
• Hypsodont teeth (Herbivores: high crowned teeth)
• *Brachydont teeth** (Primates, carnivores: low crowned teeth)

Question 2

Give the main groups of theeth

Answer 2

• Incisors
• Canine
• Premolar
• Molar
• ​Dens lupinus (eq)
  
  • First upper premolar
• Dens sectorius (car)
  
  • Last upper premolar
  • First lower molar

Question 3

Give the parts of the tooth

Answer 3

• Body (corpus dentis)
  
  • ​Applied to hypsodont teeth
  • At hypsodont teeth the corona and radix cannot be distinguished
• Crown (corona dentis)
  
  • ​Encased in enamel
  • Composed of:
    
    • Cuspis coronae dentis (one of the main projections on the occlusal surface
    • Apex cuspis
    • Tuberculum coronae dentis (secondary projection of the crown, fe, bo: on the lingual surface of some incisors in fe, bo)
• Root (radix dentis)
  
  • ​Encased in cement
  • Not covered by enamel
  • Composed of:
    
    • Apex radicis dentis
    • Radix clinica (correlated by the gingiva and alveolus)
    • Canalis radicis dentis (root canal)
    • For. apicis dentis (orifice of the root canal)
    • Pulpa dentis
    • Pulpa coronalis
    • Pulpa radicularis
• Neck (cervix dentis)
  
  • ​Enamel and cement meet
  • Constriciton between the crown and root

Question 4

What is the tooth composed of?

Answer 4

• Dentin (Surrounds pulp cavity)
  
  • Pulp cavity ​ (Central portion of tooth)
    
    • Dental pulp (​Within the pulp cavity)
• Cementum:
  
  • Covers the root
  • Bone-like substance
• Enamel:
  
  • Covers the part of the tooth that is within the oral cavity, hard white substance
  • Composed of:
    
    • Plicae enameli (longitudinal flods, premolar and molar)
    • Infundibulum dentis (invagination of enamel on the occlusal surface, su, eq: incisors, ru, eq: premolars and molars)
    • Crista enameli (free occlusal edge of one of the enamel layers of a worn teeth)
• Peridontium:
  
  • ​Connective tissue
  • Attaches the tooth and the gingive to the alveolus

Question 5

Where does the dental cavity open?

Answer 5

Opens at the apical foramen of the radix dentis

Question 6

Give the teeth surfaces

Answer 6

• Occlusal surface (Meeting the teeth of the opposite jaw)
• Contact surface (To adjacent teeth, each tooth, except the last molar, has two contact surfaces)
• Vestibular surface (Outer surface, towards vestibulum oris)
• Lingual surface (Inner surface, towards the tongue)
• Apical foramen (Opening of the apex of the root)
• Facies mesialis (On the first incisors next to the median plane)
• Facies distalis (Opposite surface of facies mesialis)

Question 7

Give the different types of teeth

Answer 7

• Bachydont:
  
  • ​Consists of:
    
    • Corona dentis
    • Radix dentis
    • Collum dentis
• Hypsodont:
  
  • Corona dentis and collum dentis are not easily distinguished
  • ​Consists of:
    
    • Corpus dentis
    • Radix dentis

Question 8

Give the number of teeth and location in:

1. Eq
2. Ru
3. Sus
4. Ca
5. Fe

Answer 8

Question 9

Interspecies differences

Answer 9

• Ca:
  
  • Brachydont type​
  • Dens sectorius
    
    • Last upper premolar
    • First lower molar
  • P2, P3, P4: have two roots, tricuspid crowns
  • Milk teeth (for the first three weeks of life there are no teeth)
• Eq:
  
  • Hyposdontal type
  • ​Dens lupinus (eq)
    
    • First upper premolar
    • Falls out when young, not replaced
  • Canine
    
    • ​Only in male
    • Diastema: Between canine and cheek teeth
• Ru:
  
  • Hyposdontal type
  • Dental pad
    
    • ​Takes the places of the missing teeth (incisors and canines of upper jaw)

Question 10

Draw a teeth

Answer 10

Question 11

Blood supply

Answer 11

• A. carotis externa → a. maxillaris → a. alveolaris mandibularis → a. incisiva mandibularis
• A. carotis externa → a. maxillaris → a. infraorbitalis → a. incisiva maxillaris
  
  • ​A. infraorbitalis branches:
    
    • R. dentales
    • R. gingivales

Question 12

Innervation

Answer 12

• N. infraorbitalis (ex. n. maxillaris (V₂))
  
  • Runs with canalis infraorbitalis
  • Gives:
    
    • R. alveolares inferiores caudales (→ molars and sinus maxillaris)
    • R. alveolares inferiores medii (→ molars, premolars, gingiva and sinus maxillares)
    • R. alveolares inferiores rostralis (→ canine and incisors)
• N. alveolaris inferior (ex n. mandibularis (V₃))
  
  • Runs with canalis mandibularis → for. mandibularis**​
  • ​In for. mentale: n. mentales

Question 13

Development

Answer 13

1. Ribbon-like thickening of epithelium
   
   • Thickening extends as plates (dental lamina) into the underlying mesendyme
2. Buds deep from deep margin of each dental plate = enamel organs
   
   • Ru: development of incisor is aborted by repression of enamel milk organs allready present
3. Mesenchyme codenses against each bud → invaginates and filled with dental papilla
4. Enamel organ:
   
   • Inner dental epithelia (over the concave surface, towards dental papilla)
   • Outer dental epithelia (over covex surface)
5. After 1^st deposition of enamel, odontoblastes starts producing dentin in center, then spreads towards all directions
   
   • Odentoblast remains as cover of the pulp
6. Dental lamina → extensive destruction
   
   • Its free edge remains to produce a second crop of buds → enamel organs of permanent teeth