Chapter 4 G: Eugnathic Dental Arch Flashcards
Evolution of dentition: primates
- median diastema, space between canine and incisors
- They had:
UPPER: 2, 1, 3, 3
LOWER: 3, 1, 3, 3 - They had an incisal dental comb in the mandible
- Then the incisors started to decrease, the comb disappeared and now the dental formula was:
UPPER: 2,1,3,3
LOWER: 2,1,3,3 - Progressive reduction in the number of incisors and premolar.
- Canines: long broad and prominent
Evolution of dentition: apes
- dental formula more similar to humans:
UPPER: 2,1,2,3
LOWER: 2,1,2,3 - Incisors attain spatulate shape, and a lateral diastema between premaxillary and maxillary suture (between anterior and posterior teeth)
Evolution of dentition: in the next stages:
- broad central incisors
- Prominent canines
- Upper molars: 4 cusp pattern and oblique ridge
- Lower molars: 5 cusp dryopithecus pattern
- In lower molars: the cusps are grouped into talnoid: 2 cusps, trigonoid: 3 cusps.
- Canines smaller, incisors less sharp, molars more cusps
Neanderthal man: facial characteristics
no chin, squashed cranial vault, big supraorbital processes, thick mandibular ramus.
Neanderthal man: stomatognathic characteristics
absence of diastemas, contact surfaces, large retromolar space, mesial drift, no third molar impactation problems, taurodontism, large canines and incisors, heavy wear on front teeth
Cro magnon man: facial characteristics
increased cranial capacity, more reduced face, face and skull with same proportion, emergence of chin.
Cro magnon man: stomatognathic characteristics
up righted incisors, crowding problems because same number of teeth but less space
Top step of evolutionary scale: steps
- teeth present—>conoid/microdontia—>agenesis
Is the agenesis of 3rd molars, PM, or lateral incisors a malocclusion?
3rd molars no
Rest yes
Crowding is a?
Negative discrepancy
Diastemas are a?
Positive discrepancy
Buccolingual direction:
- inner forces/intraoral forces are protrusive : tongue
- Outer forces/perioral forces are compressive: lips and cheeks
- The balance between these: tomes corridor determines the shape of the dental arch
- Balanced tomes corridor: adequate dental arch -Unbalanced tomes corridor: in correct dental arch
Vertical/frontal direction:
Eruptive and intrusive forces
Mesiodistal direction: upper molars tend to
rotate to mesial and lower molars tend to tilt
What determines the arch shape?
- Intrinsic morphology of the bones
- Muscular pattern with regard to facial pattern
- Tomes corridor
In deciduous dentition: assessment of the arches
- Rounded arch
- 20 teeth erupt from ages of 6months to 3years
- Primate spaces
- Flat spee curve
- Minimum overbite
Primate spaces are?
upper ( mesial to canine), lower (distal to canine)
In mixed dentition: assessment of the arches
- Arch increases in size and depth
- Flat spee curve
- Reduction of overbite
In permanent dentition: assessment of the arches
- parabolic shape
- Sagittal growth of arches
- 1/3 overbite
- Deeper spee curve
Individual analysis of the arches: transverse/horizontal
- compression and expansion
Individual analysis of the arches: sagittal
Protrusion, retrusion, mesialisation, distilsation
Individual analysis of the arches: occlusal plane
Flat/curved, canting
Relationship of the arches: what do we analyse from the transverse plane
Transverse/horizontal plane: posterior cross bite, scissor bite, midline deviations
TH PSM
Relationship of the arches: what do we analyse from the sagittal plane:
- profile
- molar and canine classes
- overjet (anterior cross bite)
JHS
Relationship of the arches: what do we analyse from the frontal plane?
- vertical plane
- normal correct bite
- 2/3 and 3/3 increased over bite
- open bite
