Gnatho 1-21

Question 1

1. Articulator

Answer 1

a mechanical instrument that represents the TMJs and jaws, to which maxillary and mandibular casts may be attached to simulate some or all mandibular positions and movements.

Question 2

2. Occludor

Answer 2

a prosthetic device intended to set the upper and lower cast in a given position. It is mostly used recording ICP.
Some occludors may simulate mouth opening and closing.

Question 3

3. „Scribing”/”Positional” Articulators

Answer 3

Instruments permit eccentric motion based on engraved records obtained from the patient.
For imitating the tooth guidance primarily in horizontal plane. Movements are guided by the 3 or 4 pins and cups holding the guiding material, which are developed similarly to the incisal pin and table of the articulators.
In vertical dimension only the vertical and horizontal overbite determines the movements of the mandible.

Question 4

4. Arcon articulator

Answer 4

an articulator that applies the arcon design (articulator condylar)
this instrument maintains anatomic guidelines by use of condylar analogs attached to the mandibular element and fossae assemblies attached to the maxillary element.

Question 5

5. Non-arcon articulator

Answer 5

an articulator
whose condylar path components are part of the lower member of the articulator and
whose condylar replica components are part of the upper member.

Question 6

6. Occlusal plane

Answer 6

an imaginary plane, which rests on 3 characteristic points:
the mesial corner of the incisal edge of the lower left central incisor (incision inferius), and
the disto-buccal cusp tips of the two distal most (third or second) mandibular molars.

Question 7

7. Incision inferius

Answer 7

the mesial corner of the incisal edge of the lower left central incisor.

Question 8

8. Panthograph

Answer 8

an instrument used to graphically record the paths of mandibular movement in one or more planes, and
to provide information for the programming the adjustable articulators.

Question 9

9. Frankfort horizontal plane

Answer 9

called also eye-ear plane or auriculo-orbital plane.
A plane passing through
the lowest point of the margin of the left orbit (orbitale) and
the highest point in the margin of each external auditory meatus (porion).
[It approximates to the horizontal, when the head is in a normal upright position].
It is the most important reference plane of the head; it is theoretically parallel to the horizon when the patient is in the natural head position.

Question 10

10. Camper’s plane

Answer 10

called also acanthion-external auditory meatus plane.
Established by the left tragion-subnasale point-right tragion.
A plane extending from the inferior border of the ala of the nose to the superior border of the tragus of the ear.
After the patient has lost the teeth it can be used to determine the occlusal plane, because it is parallel with this.

Question 11

11. Intercuspation

Answer 11

The cusp-to-fossa relationship of the upper and lower posterior teeth to one another.
The interlocking or fitting together of the cusps of opposing teeth. Also called interdigitation.
A cusp creates occlusal contacts around the fossa or on the marginal ridge of the opposing tooth.

Question 12

12. Occlusal unit

Answer 12

each tooth makes contacts with two opposing teeth, with the exception of the lower central incisor and the upper wisdom tooth.
The three occluding teeth are called an occlusal unit.

Question 13

13. Occlusal surface

Answer 13

The collective surface of the individual teeth that is intended to make contact with the occlusal surfaces of the opposing teeth.
This surface is a complicated, curved surface, with a horseshoe shape.
The area of the grinding surface is only a few square centimeters.

Question 14

14. Curve of Spee

Answer 14

the edges of the mandibular incisors and the cusps of the mandibular grinding teeth are situated under the chewing plane, on a concave arch.
From lateral view, an imaginary line is drawn through the buccal cusp tips of the lower posterior teeth (molars and premolar) conformed to a fairly even curve in an anterior to posterior direction. This curvature is within the sagittal plane only.
The occlusal surface of the lower premolars look distally, while the occlusal surface of the second and third molar looks mesially,
deepest point of the Spee curve is on the place of the first lower molar.

Question 15

15. Curve of (Monson) Wilson

Answer 15

From the frontal aspect, the buccal cusps of the mandibular molars are higher than the lingual cusps. The cusps are situated in the frontal plane on a concave curve.

Question 16

16. Bonwill triangle

Answer 16

is an imaginary equilateral triangle bounded by lines connecting 
the contact points of the mandibular central incisor’s incisal edge (incision inferius) to
each condyle (usually its midpoint) and from one condyle to the other. 
It has an importance in the construction of articulators and in the mounting of casts in the articulator.

Question 17

17. Balkwill angle

Answer 17

the angle formed between the Bonwill triangle and the occlusal plane, it is on average 22º, and opened distally.

Question 18

18. Cusp

Answer 18

part of the occlusal surface of a posterior tooth (premolar, molar).
A cusp is a hard eminence on a tooth that emerges from the occlusal surface of the tooth.
The cusp is similar to a prism, with three surfaces, rounded edges and convex surfaces,
like a trieder, the apex has also a rounded form, is not sharp.

Question 19

19. Mesial and distal cusp ridges

Answer 19

cylindrical slopes started from the tip of the cusp to mesial and distal direction,
cusp ridges are eminences that radiate from cusp tips.
There are two marginal ridges, mesial and distal. They are located on the mesial and distal borders of the occlusal surface.

Question 20

20. Triangular ridge

Answer 20

is a convex surface, lying between the tip of the cusps and the central groove of a cuspal tooth.

Question 21

21. Marginal ridge

Answer 21

cylindrical feature of the teeth which borders the occlusal surface of the premolar and molar teeth mesially and distally.