Tooth Morphology Flashcards
What is the cheek side of the tooth?
Buccal
What is the opposite to the cheek side of the tooth?
Palatal if upper
Lingual if lower
What is the orientation of the teeth towards the front of the head?
Mesial
What is the orientation of the teeth towards the back of the head?
Distal
What is cingulum?
Portion of the teeth that forms a convex protuberance at the cervical third of the anatomic crown
What distinguishes an upper/lower incisor?
Uppers have roughly rectangular labial surface
Lowers have triangular or fan shaped labial surface
For upper incisors how do you determine whether its central/lateral?
1st is larger
2nd is small/narrow
For upper incisors how do you determine whether its R/L of mouth?
Mesial profile of crown is in straight line with root, distal side flares
Junction of mesial and incisal edge is sharp, distal is rounded
Cingulum is skewed distally
For lower incisors how do you identify whether its 1st/2nd?
1st is smaller and crown is almost symmetrical
2nd is larger and crown shows more pronounced distal flare
For lower incisors how do you determine left or right?
Mesial profile of crown is in straight line with root, distal side flares
Junction of mesial and incisal edge is sharp, distal is rounded
Cingulum skewed distally
How do you distinguish an upper or lower canine?
- Crown shape - upper canine has stout crown with broad-diamond shaped surface and pointed cusp - lower canine has high, narrower crown with less pointed cusp
- Crown-root - Upper canine has crown set in straight line with root, lower is at an angle
- Level of ACJ - upper has ACJ at same level on labial and lingual sides
Lower has enamel extending further apically on labial side
How do you determine left or right?
- Mesial slope is shorter
- Mesial profile of crown is straighter and in line with root, distal side bulges out into a marked convexity and forms angle
- Cingulum skewed distally
How do you determine whether upper/lower premolar?
Shape of occlusal surface - upper oval, lower round
Crown-root angle - Upper straight line, lower curved buccal
For an upper premolar, how do you determine whether its first or second?
Upper 1st has larger cusps, buccal larger than lingual
Upper 1st has marked concavity “canine fossa” on mesial surface
Upper 2nd has smaller cusps than 1st
Upper 2nd has flat mesial surface
Upper 1st sometimes has 2 roots
Upper 2nd usually has one
For upper premolar how do you determine orientation in mouth?
Proximal surfaces - upper 1st has concavity (CANINE FOSSA) on mesial surface, upper 2nd has flat mesial surface/convex distal surface
Lingual (palatal) cusp - both upper premolars show mesial displacement of lingual cusp, though this is less marked in second premolar
For lower premolars how can you distinguish 1st/2nd?
Lower 1st premolar has large buccal cusp and very small lingual cusp
Lower 2nd has one or two cusps more closely approximating the buccal cusp in height
For lower premolars how can you distinguish left or right orientation?
Lower 1st has flattened area on mesio-lingual aspect and often fissure running from mesial pit over on to this surface
Lingual cusp is often displaced slightly distally
Lower 2nd has mesial displacement of single lingual cusp, or if 2 cusps, mesial is larger
How can you distinguish upper or lower molar?
Upper have 3 or 4 cusps with 3 roots
Lower has 4 or 5 cusps with 2 roots
How can you distinguish upper 1st molar?
Has 4 cusps
Occlusal surface rhomboidal
Roots are long, well-shaped and separated
How can you distinguish upper 2nd molar?
Varying degrees of reduction of disto-lingual cusp, which can either be slightly reduced/reduced/absent
Occlusal surface usually compressed mesiodistally, or may be triangular
Roots are shorter. more irregular, may be partly fused
How can you distinguish upper 3rd molar?
Shows greater degree of reduction of disto-lingual cusp, which may be considerably reduced/absent
May be compressed/triangular
Shorter roots, more irregular, or completely fused
How can you distinguish lower 1st molar?
Usually has 5 cusps
Crown regular and well shaped
Roots are long, well-shaped and well-separated
How can you distinguish lower 2nd molar?
Usually 4 cusps
Crown regular
Roots are shorter, more irregular and partly fused
How can you distinguish lower 3rd molar?
May have 3-6 cusps
Crown usually irregular
Roots shorter, more irregular, could be completely fused
How do you identify primary incisors?
Same as permanent incisors
How do you identify primary canines?
Often very difficult to identify as point of cusps may be placed centrally, or skewed mesially or distally
How do you identify primary molars?
1st molars unlike any permanent tooth
2nd primary molars same morphology as 1st permanent molars, with 4 cusps in maxilla and 5 in mandible
How do you identify upper/lower and left/right in 1st primary molars?
Upper - quadrilateral in shape, wider buccolingually
Lower - compressed buccolingually and longer mesodistally
Molar tubercle is always found at mesiobuccal corner of cervical margin
How do you identify 2nd primary molar orientation?
Same as for 1st molar in permanent dentition
When do primary teeth begin mineralisation?
4-6 months
Which primary teeth are the first to erupt and when?
Central incisors (A) - 6-7 months
Which primary teeth are second to erupt and when?
Central incisors (B) - 7-8 months
Which primary teeth are third to erupt and when?
1st molars (D) - 12 months
Which primary teeth are fourth to erupt and when
Canines (C) - 18 months
Which primary teeth are last to erupt and when?
2nd molars (E) - 24 months
In what order do the permanent dentition erupt?
First molars - 6y Central incisors - 7y Laterals - 8y Canines - 9y Premolars - 10y Second molar -12y Third molars - 18y
When do the permanent teeth begin mineralisation?
First molars - at birth Anteriors - 3-5 months (upper laterals 11 months) Premolars - 2y 2nd molars - 3y 3rd molars - 9y
