Lecture 3- Nomenclature II Flashcards
Line angle
When two surfaces meet
Mesiolabial line angle
Where mesial and labial surfaces meet
How many line angles do anterior teeth have?
6
How many line angles do posterior teeth have?
8
Point angle
When three surfaces meet
How many point angles does each anterior tooth have?
4
How many points angles does each posterior teeth have?
4
Face of a tooth
The area on the facial surface of teeth that is bounded by the line angles and height of contour
Only area of a tooth that reflects light
face of a tooth
What can change the APPEARANCE of the size of a tooth?
Change in the position or contour of line angles control the appearance of the size of the tooth
Line angles have…
Dramatic effects on esthetics
Height of contour
The greatest amount of a curve, or greatest convexity or bulge, farthest from the root axis line
Where is the lingual height of contour found on anterior teeth?
On the cingulum, or on the cervical third
Where is the lingual height of contour found on posterior teeth?
Middle third
Where is the facial height of contour found for ALL teeth?
Cervical third
Function of the height of contour (1)
Forms contact area on proximal surfaces
Function of the height of contour (2)
Protects gingiva surrounding the root
Function of the height of contour (3)
Affects the final esthetics of the tooth
Over-contouring consequences
Under-stimulation deflects food from gingiva and results in under-stimulation of supporting tissue
Under-contouring consequences
Irritation of soft tissue
Correct contour
Adequate stimulation for supporting tissue, leads to healthy teeth (provides protection and adequate stimulation)
Height of lingual and facial height of contour
.5 mm
Occlusocervical location of proximal height of contour
Interproximal contacts are located progressively closer to the gingiva the more distal they are located from the midline
Faciolingual location of proximal height of contour
Proximal contacts are facial to the center of the tooth (lingual embrasure is larger than facial)
Proximal contact areas are largest in what area?
In molar regions
Reason for this? Prevents food impaction during mastication
Which embrasures are wider in anterior teeth and why?
Lingual embrasures are wider than labial. This is due to marked lingual convergences seen in anterior teeth
Which embrasure are wider in ALL teeth and why?
Lingual embrasures are wider than facial embrasures of ALL teeth because the proximal contact is toward the facial surface and the lingual convergence
What happens to the occlusal/incisal embrasure as you move distally?
It widens as you move away from the midline
increases from incisors to molars
Mandibular incisal embrasure
Very minimal as their contact areas are more incisally located (nearer to the incisal ridge)
Odontogenesis/tooth development
The complex process by which teeth form from embryonic cells, grow and erupt into the mouth
2 components of tooth development
1) Crown and root formation
2) eruption of teeth
Eruption vs emergence
Tooth always eruption, only emerges once in breaks gingiva. Emergence through mucous membrane is a SINGLE event while tooth eruption is a continuous process
When does crown and root formation begin?
6 weeks intra uterine
Development of primary teeth
Begins prenatally and continues postnatally
Permanent teeth development
Entirely postnatally
Calcification
Tooth tissues harden by deposition of minerals salts in enamel, dentin and cementum
When do primary tooth begin to calcify?
4 months in utero
When do permanent teeth begin to calcify?
Soon after birth
Lobe formation
Initiates in 4-5 growth centers
Lobe
One of the primary sections of formation in the development of the crown; considered a growth center
Lobes coalesce into a crown, then formation of what takes place?
Then root formation follows
Anteriors form from 4 main lobes:
1) Mesial
2) Central/labial
3) Distal
4) Lingual
Mammelon
Rounded protuberance found on the incisal ridges of newly erupted incisors
(Wear away with function)
Cingulum
Rounded elevation of an anterior tooth making up most of the cervical third of the lingual surface
All premolars develop from 4 lobes EXCEPT
Except mandibular 2nd premolar which develops from 5 lobes
All molars develop from 4 lobes EXCEPT
1st molars develop from 5 lobes
Emergence
Tooth emergence through gingiva
Eruption
Continuous tooth movement to reach opposing tooth (occlusal contact)
Eruption is what kind of a process?
Multifactorial process
Why is eruption a multifactorial process?
When the tooth reaches occlusion, root development is not complete (only 2/3)
How long does root formation need to be completed with primary vs permanent teeth?
1.5 years for primary and approximately 3 years for permanent
Does teeth eruption take place earlier in males or females?
Females
The first permanent tooth to erupt
Mandibular 1st molar
The first primary tooth to erupt
Mandibular central incisor
Chronology chart (4 parts)
1) First evidence of calcification
2) Crown formation
3) Eruption
4) Root completion
Primary mandibular Maxillary Central incisor
8-12 months
Primary mandibular Lateral incisor
9-13 months
Primary mandibular Canine
16-22 months
Primary mandibular First molar
13-19 months
Primary mandibular Second molar
25-33 months
Primary mandibular central incisor
6-10 months
First to erupt
Primary mandibular lateral incisor
10-16 months
Primary mandibular Canine (cuspid)
17-23 months
Primary mandibular first molar
14-18 months
Primary mandibular second molar
23-31 months
Permanent maxillary central incisor
7-8 years
Permanent maxillary lateral incisor
8-9 years
Permanent maxillary cuspid
11-12 years
Permanent maxillary first bicuspid/premolar
10-11 years
Permanent maxillary second bicuspid/premolar
10-12 years
Permanent maxillary first molar
6-7 years
Permanent maxillary second molar
12-13 years
Permanent maxillary third molar
17-21 years
Permanent mandibular central incisors
6-7 years
Permanent mandibular lateral incisors
7-8 years
Permanent mandibular cuspid/canine
9-10 years
Permanent mandibular 1st premolar/bicuspid
10-12 years
Permanent mandibular 2nd premolar/bicuspid
11-12 years
Permanent mandibular 1st molar
6-7 years
Permanent mandibular 2nd molar
11-13 years
Permanent mandibular 3rd molar
17-21 years
Physiological resorption of roots of primary teeth leads to exfoliation of primary teeth. When does this happen?
3 years after roots are completely developed (happens as permanent successor teeth begin their occlusal migration)
All mandibular teeth are shed before their maxillary counterparts EXCEPT
Primary 2nd molars
all 4 are shed simultaneously
Anodontia
A rare genetic disorder characterized by the congenital absence of all primary OR permanent teeth
HYPOdontia/congenitally missing teeth
A condition in which one or more permanent teeth fail to appear
Most commonly congenitally missing teeth IN ORDER (List all 4)
1) 3rd molars (think wisdom teeth)
2) Mandibular 2nd premolar
3) Maxillary lateral incisor
4) Maxillary 2nd premolar
Impacted tooth
An unerupted or partially erupted tooth that is positioned against another tooth, bone, or soft tissue so that complete eruption is unlikely
Top 3 most impacted teeth (in order)
1) 3rd molars
2) Upper canines
3) Lower canines
HYPERdontia/supernumerary teeth
Extra teeth in mouth!
mesiodens but not limited to it
Mesiodens
Extra tooth between two central incisors
Cingulum
Cingulum is the round elevation on the cervical
third of the lingual surfaces of anterior teeth
Lingual fossa
Concavity on lingual surface; cingulum form cervical boundary, marginal ridges form mesial and distal borders of the fossa
Cusp
Elevation on crown portion of tooth
Found in posterior teeth and canines
Cusp tip
Highest point of a cusp
Ridge
A ridge is any linear elevation on the surface of a tooth
It is named according to its location or shape
All teeth have two marginal ridges:
mesial and distal ridges
Facial of all teeth is wider than lingual. Therefore, lingual embrasures are larger than buccal embrasures. Why?
All marginal ridges converge from the buccal toward the lingual
(All adjacent marginal ridges should be at the same height to prevent food impaction and retention)
Cusp ridges (4 of them)
1) Buccal cusp ridge
2) Lingual cusp ridge
2) Mesial cusp ridge
3) Distal cusp ridge
Triangular ridge
It is the ridge that descends from each cusp tip towards the center of the occlusal surface of a posterior tooth. Which is the same as the cusp ridge so it can have 2 names
They take the name of the cusp they belong to, e.g. triangular ridge of the buccal cusp of mandibular permanent 1st premolar
(E.g have to say triangular ridge of buccal cusp or triangular ridge of lingual cusp)
Has 4 ridges (pyramid)
Transverse ridge
The union of two triangular ridges crossing the occlusal surface of a posterior tooth in a transverse (buccolingual) direction, e.g. transverse ridge between buccal and lingual cusps on premolar
aka two triangles come together!
Oblique ridge
It is the ridge that runs at an angle from the DB cusp tip to the ML cusp tip of an upper molar
Oblique ridge is most prominent in what tooth?
Permanent maxillary 1st molar
Cervical ridge
It is a ridge that runs mesiodistally on the cervical third of the buccal surface of the crown
Characteristic of PRIMARY MOLARS
Cervical ridge is a characteristic of which teeth?
Primary 1st molars
Fossae
Shallow rounded concavity
Lingual fossa
Found on the lingual surfaces of anterior teeth
Lingual fossa boundaries
Cingulum, marginal ridges and incisal edge
Central fossa
Found in the center of occlusal surfaces of molar teeth
Where opposing cusp tips occlude
Triangular fossae
2 small fossae on the occlusal surface of posterior teeth, mesial and distal to the marginal ridges (next to central fossa)
Base of the triangle is at the mesial/distal marginal ridge and the apex is at the mesial/distal pit
Developmental grooves (3)
Sharply defined grooves separating the lobes or the primary parts of the crown or root, named according to location
Central developmental groove
Runs mesiodistally on the occlusal surface
Separates the buccal and lingual cusps
Buccal developmental groove
Starts at the central developmental groove and runs buccally separating the Buccal cusps
Ends on the buccal surface in the buccal pit
Lingual developmental groove
Starts at the central developmental groove and runs lingually separating the lingual cusps
Ends on the lingual surface in the lingual pit
Supplemental grooves
Small irregular, less distinct grooves on the occlusal surface a tooth
Do NOT mark the junction of primary parts of the tooth
Pits (3)
Pits are small pinpoint depressions located at the junction of two or more developmental grooves or at the terminus of these grooves (named according to their location)
Central pit
a pit in the central fossa of molars where the developmental grooves meet
Buccal pit
It is a pit on the buccal surface of a molar where the buccal developmental groove terminates.
Lingual pit
a pit on the lingual surface of a molar where the lingual dev. groove terminates. Lingual pit is also seen on lingual surface of upper anteriors
Lingual pit is common in of which anteriors?
Upper lateral (Maxillary lateral incisors)
Fissures
Found in the bottom of the grooves; due to incomplete union of primary lobes
The grooves left a small space where it didn’t mean to
Fissures are not always there, depends on the patient
Why are pits and fissures liable to dental caries?
Due to accumulation of bacteria (class I)
