Lecture 2 Flashcards
Crown division arch to back:
Mesial, medial, distal
Crown division top to bottom
Occlusal/incisal, middle, cervical
Crown division proximal view (side view)
Facial, medial, lingual – still occlusal/incisal, middle, cervical
Crown division
Broken in 3rds.
Order of terms in description
- mesial
- distal
- facial/labial/buccal
- lingual
- occlusal/incisal
- Cervical/apical
Surface junctions
Two surfaces that join (line angle) - distolabial is an example.
3 surface point angle example
mesiofacio-occlusal point angle
Point angle
3 surfaces meet.
Dimension
Distance between two opposite walls (mesiodistal dimension is example).
Root to crown ratio
Ratio changes in life, many times clinically the root becomes exposed. Smaller ratio (closer to 1) denotes near equal crown and root length. Larger is opposite.
Linear depressions
Not rounded - the grooves. Not present on anterior, but present on occlusal surface of posterior teeth.
Central groove
Middle between buccal and lingual cusps, run mesiodistally.
Marginal ridge grove
M (see slide)
Fossa developmental grooves
Extend toward line angles (distobuccal fossa group). Separate lobes.
Supplemental grooves
Smaller grooves (marginal ridge, extra, etc). Can surround triangle. Not marking junction of important areas.
Other grooves:
buccal grooves on molar, lingual grooves on molar. Separate lingual and buccal cusps respectively.
Fossae
Shallow bowl-like depressions. On lingual surface of anterior teeth, occlusal of posterior teeth.
Pit and fissure
Decay starts in grooves and spreads more quickly once in dentin. Deepest part of groove - enamel can sometimes not fuse completely, exposing dentin. This is a fissure. Pit is the same but with fossa.
Fissure
Exposure of dentin due to lack of fusing on groove.
Tooth with tendency for pits
Maxillary lateral (sometimes central) incisors. Have deep fossa.
Cingulum
Bump at cervical lingual portion of tooth
Apex
root tip
Furcal area
Area between split roots - triangular, other end for sulcus
Root trunk
Before any split.
Furcation
Area of root where it splits. If 2 - bifurcation. If 3 - trifurcation
CEJ on proximal curves towards
Incisal/occlusal
CEJ on facial curves towards
Apex
Mesial curves more than
Distal
CEJ curvature diminish
from anterior to posterior. Deepest curvature (mesial surface of central incisor - up to 3.5 mm). For 3rd molar is between 1 and 0 mm.
Root Axis Line
Imaginary line that splits the root in half (mesiodistally or faciolingually). Used as a reference for different landmarks. Ex. tip of cusp is facial to root axis line if viewed posteriorly.
Height of contour/Crest of Curvature
Most prominent areas of tooth. If you bring the root axis line outward (parallel to original), the part of the tooth that still touches is this height of contour.
Importance of height of contour
Clinical application: All facial and buccal surface height of contour is located on the cervical 1/3rd. Only one that is true for all teeth. Lingual HOC changes. On anterior it is in the cervical 1/3rd. Posterior is on middle 3rd. It is like this so that the HOC protects gingiva. Also, the bump deflects food away from gingival sulcus.
If HOC is too large
Food debris will stay in gingival sulcus, causing inflammation.
Embrasure Spaces
Triangular negative spaces that occur when two adjacent teeth touch. Cervical embrasure (or interproximal space), and Occlusal (or for incisors incisal) embrasure. From occlusal view, we get buccal/facial embrasure and lingual embrasure (usually larger than buccal).
Tooth development
From lobes
Anterior teeth lobes
3 lobes for facial, 1 lobe for lingual - total of 4. Mesial, middle, distal, lingual lobes.
Premolar teeth lobes
Once called bicuspid, mandibular 2nd premolar occasionally have 3 cusps so this was changed. 3 facial lobes, one lingual cusp lobe. Same naming. Some premolars have two lingual cusps, and have 5 lobes (2 lingual).
How many lobes form mandibular 2nd molar with 3 cusps
5 - 3 for facial cusp, 2 for each lingual cusps
Molar lobes
1 lobe per cusp. Usually 4 or 5 lobes.
Axial inclinations
Not straight angles for how teeth are set. Maxillary teeth: anteirors are mesially inclined, posterios not. Mandibular teeth are all mesially inclined. **Called long axis of the tooth (could be vertical, a little to the buccal, lingual, etc.). Do not confuse this with root axis line. Has to do with orientation of tooth in bone
Axial inclinations - frontal view
Maxillary teeth tilt facially, mandibular teeth tilt lingually.
Maxillary curve
Convex (smiley face)- anteroposterior curve of spee - canine to last molar curve.
Mandibular curve
Concave (frown)
Mediolateral curve (of wilson)
Mandibular (smile face) posterior view of molars, line from 3rd to 3rd concave. Maxillary is the exact opposite - convex.
Interocclusal relationship
These curves allow for buccal cusp of mandibular teeth to fit in sulcus of maxillary, and the lingual cusp fits in sulcus of mandibular teeth. This helps chew.
Occlusion
contact of the occlusal and incisal surfaces of maxillary and mandibular teeth (to close).
Maximum intercuspation
Maximum amount of contact possible between maxillary and mandibular teeth.
Interocclusal space
Little space between teeth when you go from maximum intercuspation and swallow. Approximately 3 mm. Dimension between tip of nose and chin when teeth are contacting (
Vertical dimension in occlusion
Dimension between tip of nose and chin when teeth are contacting (~57 mm on average)
Vertical dimension at rest
Dimension between tip of nose and chin when teeth are at rest (~60 mm on average).
Class 1 occlusion (angle’s classes)
Mesiobuccal cusp of maxillary first molar fits into mesiobuccal groove of mandibular first molar. Maxillary canine will feed between mandibular canine and 1st molar. Maximal intercuspal position. Relationship of 2:1 interaction except for 24 and 25 (front teeth due to small diameter). Leads to overbite.
Vertical overlap
Overbite
Horizontal overlap
Overjet - Separation between lingual and facial surfaces of incisors
Bridge
When making a bridge, you must use teeth w/higher root-crown ratio. 2/3 crown/root = optimal - 1/1 minumum
Tallest tooth/Longest crown
canine or maxillary central incisor (second one)
Longest tooth
maxillary canine
Widest crown
mandibular first molar
narrowest crown
mandibular central incisor
Cusp
Entire pyramid - the tip is the cusp tip or apex. 4 ridges (medial, distal, facial, triangular ridge (cusp tip to middle of tooth))
Cusps
Canines and posterior have between 1 and 5. Most are named after closest tooth surface/line angle
Ridges
Cusp slopes or cusp arms. See slide Buccal ridge is an example.
Mesial and Distal marginal ridges
Connect cusps in posterior teeth, on mesial+distal surface of tooth.
Cingulum
Bump on linguocervical region
Two triangular ridges join to form
One transverse/oblique ridge
Review lab sheet 1
**
Sulcus
Formed by transverse triangle ridge. This is a depression.
Occlusal table
Most of chewing takes place here.
Occlusal outline
Prominant points
Mamelons
3 bumps - form on adult incisors from three labial lobes. Usually wear away.
Perikymata
Very small horizontal wave-like ripples of enamel on newly erupted adult teeth.
