embryology, histology and tooth morphology

Question 1

what are the stages of prenatal developmental periods and critical times

Answer 1

germinal period - takes place during first two weeks

embryonic period - third to eight week, most critical period as this is when development of all major structures begin

fetal period - ninth week til birth

Question 2

what is the tooth numbering systems

Answer 2

universal numbering system
- 1 to 32
- A to K for primary

international standards organization
- 1.2, 1.4 etc

palmers method
- brackets

Question 3

eruption of the permanent dentition (maxillary)

Answer 3

first molar - 6 to 7 years old
central incisor - 7 to 8 years old
lateral incisor - 8 to 9 years old
first premolar - 10 to 11 years old
second premolar - 10 to 12 years old
canines - 11 to 12 years old
second molar - 12 to 13 years old
third molar - 17 to 21 years old

Question 4

eruption of permanent dentition (mandibular)

Answer 4

first molar - 6 to 7 years old
central incisors - 6 to 7 years old
lateral incisors - 7 to 8 years old
firsts pre molar - 9 to 10 years old
second pre molar - 10 to 11 years old
canines - 12 to 13 years old
second molar - 11 to 13 years old
third molar - 17 to 21 years old

Question 5

eruption of primary dentition (max)

Answer 5

central incisors - 6 o 10 months
lateral incisors - 9 to 12 months
first molar - 12 to 18 months
canine - 16 to 22 months
second molar - 24 to 32 months

Question 6

eruption of primary dentition (mand)

Answer 6

central incisors - 6 to 10 months
lateral incisors - 7 to 10 months
first molar - 12 to 18 months
canine - 16 to 22 months
second molar - 20 to 32 months

Question 7

what are the types of teeth, their names, position in the orcal cavity, function, number of roots and anatomy

Answer 7

incisors
- located at the front of the mouth
- designed to cut food without heavy force
- single root
- lingual surface is shaped like a shovel to guide food into the mouth

canines
- located at the corner of the arch
- designed to cut and tear food with force
- one long root
- best anchored tooth

premolars
- sits in between canine and molars
- buccal cusps hold food while lingual cusps grind it
- lower premolars and second upper premolars have 1 root, upper first premolars have 2 roots

molars
- positioned in the very back of the arch
- used to chew or grind teeth
- molars have 4 or more cusps
- usually 2 or 3 molars

Question 8

names and locations of each tooth surface

Answer 8

• facial, vestibular, buccal (faces the lips)
• lingual surface ( tongue side of the teeth)
• incisal surface ( chewing surface of the anterior teeth)
• occlusal surface (chewing surface of posterior teeth)
• mesial surface (surface of tooth facing midline of mouth)
• distal surface ( surface of tooth facing away from midline)

Question 9

what are the names and location of the tissues of the tooth including types of cementum and dentin

Answer 9

• enamel
• dentin (primary, secondary, tertiary)
• cementum (primary is formed as the roots develop, secondary forms after the tooth has reached functional occlusion)
• pulp (pulp horns, coronal pulp, accessory ppulp, radicular pulp, apical foramen)
• periodontium (cementum , alveolar bone, periodontal ligament)
• dentoenamel junction (where the dentin and enamel meet)
• cementoenamel junction (where the cement and enamel meet)
• alveolar process (bone that supports teeth in functional position)

Question 10

alveolar crest fiber

Answer 10

resists in rotational forces and tilting of tooth

Question 11

horizontal fiber groups

Answer 11

resists rotational forces and tilting of tooth

Question 12

oblique fiber groups

Answer 12

resists forces that try to push tooth inward

Question 13

apical fiber groups

Answer 13

resists forces that try to pull tooth outward, and rotational

Question 14

interradicular fiber group

Answer 14

only found in multi-rooted teeth and resists rotational forces and holds teeth in interproximal contact

Question 15

interdental fiber group

Answer 15

resists rotation, holds teeth in interproximal contact

Question 16

what are the periodontal fiber groups

Answer 16

alveolar crest fiber group
horizontal fiber group
oblique fiber group
apical fiber group
interradicular fiber group
interdental fiber group

Question 17

what are the names and function of the components of the alveolar process

Answer 17

cortical plate - dense outer covering that makes up the central part of the alveolar process

alveolar process - highest point of alveolar ridge

alveolar socket - cavity within the alveolar process that surrounds the root of tooth

lamina dura - a thin layer of compact bone lining the alveolar socket

Question 18

what are landmarks of the hard palate

Answer 18

incisive papilla - pear shaped soft tissue that covers incisive foramen
palatal rugae - irregular ridges of masticatory mucosa
palatine raphe - runs posteriorly from incisive papilla at midline
palatal gands - small glands that open onto the palatal mucosa as small pits

Question 19

landmarks of the soft palate

Answer 19

palatoglossal arch - arch runs from soft palate down to side of the tongue

palatopahryngeal arch - a free posterior border of the soft palate

isthmus of fauces - an opening between the two arches and contains the tonsils

Question 20

types of lining of the oral cavity

Answer 20

• labial mucosa (lips)
• mucobuccal fold ( where the buccal mucosa meets the alveolar mucosa)
• mucogingival junction ( a distinct line of colour change can be seen where alveolar membrane meets attached gingivav)
• buccal vestibule (area between the cheeks and the teeth)
• parotid papilla (protects opening of parotid duct)
• fordyces spots (yellow elevations)
• linea alba ( white ridge of raised tissue)

Question 21

components of gingival unit

Answer 21

• unattached gingiva ( border of gingiva that surrounds the teeth)
• interdental gingiva (extension of free gingiva that fills interproximal embrasure between theeth
• gingival groove (shallow groove that marks the beginning of the attached gingiva)
• attached gingiva (extends from base of the sulcus to the mucogingival junction)

Question 22

divisions into thirds of crowns and roots

Answer 22

roots
- apical
- middle
- cervical

crown vertical
- distal
- middle
- mesial

crown horizontal
- occlusal
- middle
- cervical

Question 23

line angles and point angles

Answer 23

line angle
- formed by junction of two surfaces

point angle
- formed by the junction of three surfaces at one point

Question 24

succedaneous teeth

Answer 24

• central incisors replace central incisors
• lateral incisors replace central incisors
• canines replace caninces
• premolars replace primary molars

Question 25

blacks classification

Answer 25

class I - decay on the pits and fissures
class II - decay on the proximal surfaces of posterior teeth
class III - decay on the proximal surfaces of anterior teeth
class IV - decay on the proximal and incisal surfaces of anteriors and canines
class V - decay on the gingival third of the buccal or lingual surfaces of the teeth

Question 26

difference between diastema and primate spaces

Answer 26

-diastema is a space between two teeth
- primate spaces are spaces between every primary tooth

Question 27

embrasure

Answer 27

is triangular space between two teeth