1. Occlusion
Occlusion : 1- the act or process of closure or of being closed or shut off 2: the static relationship between the incising or masticating surfaces of the maxillary or mandibular teeth or
tooth analogues

2. occlusion analysis : a systematic examination of the masticatory system with special consideration to the effect of tooth occlusion on the teeth and their related structures

3. Angle’s classification of occlusion [Edward Harley Angle, American orthodontist for a classification system of occlusion based on the interdigitation of the first molar teeth originally described by Angle as four major groups depending on the antero- posterior jaw relationship. Class IV is no longer in use.
Class I (normal occlusion or neutrooclusion): the dental relationship in which there is normal anteroposterior relationship of the jaws, as indicated by correct interdigitation of maxillary and mandibular molars, but with crowding and rotation of teeth elsewhere, i.e., a dental dysplasia or arch length deficiency.
Class II (distoclusion): the dental relationship in which the mandibular dental arch is posterior to the maxillary dental arch in one or both lateral segments; the mandibular first molar is distal to the maxillary first molar.
Class II can be further subdivided into two divisions:.

4. Angle’s classification of occlusion
Division 1: bilateral distal retrusion with a narrow maxillary arch and protruding maxillary incisors. Subdivisions include right or left (unilaterally distal with other characteristics being the same). Division 2: bilateral distal with a normal or square-shaped maxillary arch, retruded maxillary central incisors, labially malposed maxillary lateral incisors, and an excessive vertical overlap. Subdivisions include right or left (unilaterally distal with other characteristics the same). Class III (mesioocclusion): the dental relationship in which the mandibular arch is anterior to the maxillary arch in one or both lateral segments; the mandibular first molar is mesial to the maxillary first molar. The mandibular incisors are usually in anterior cross bite. Subdivisions include right or left (unilaterally mesial with other characteristics the same). Class IV: the dental relationship in which the occlusal relations of the dental arches present the peculiar condition of being in distal occlusion in one lateral half and in mesial occlusion in the other (no longer used).

5. Acquired eccentric relation : any eccentric relationship position of the mandible relative to the maxilla, whether conditioned or learned by habit, which will bring the teeth into contact .

6. Centric occlusion : the occlusion of opposing teeth when the mandible is in centric relation. This may or may not coincide with the maximal intercuspal position.
Centric position : the position of the mandible when the jaws are in centric relation.

7. Centric relation:
1- The maxillomandibular relationship in which the condyles articulate with the thinnest a vascular portion of their respective disks with the complex in the anterior- superior position against the shapes of the articular eminencies. This position is independent of tooth contact. This position is clinically discernible when the mandible is directed superior and anteriorly. It is restricted to a purely rotary movement about the transverse horizontal axis
2: The most retruded physiologic relation of the mandible to the maxillae to and from which the individual can make lateral movements. It is a condition that can exist at various degrees of jaw separation. It occurs around the terminal hinge axis .
3: the most retruded relation of the mandible to the maxillae when the condyles are in the most posterior unstrained position in the glenoid fossae from which lateral movement can be made at any given degree of jaw separation
4: The most posterior relation of the lower to the upper jaw from which lateral movements can be made at a given vertical dimension
5: a maxilla to mandible relationship in which the condyles and disks are thought to be in the midmost, uppermost position. The position has been difficult to define anatomically but is determined clinically by assessing when the jaw can hinge on a fixed terminal axis (up to 25 mm).

8. Acquired occlusal position : the relationship of teeth in maximum intercuspation regardless of jaw position

9. Anatomic occlusion : an occlusal arrangement for dental prostheses wherein the posterior artificial teeth have masticatory surfaces that closely resemble those of the natural healthy dentition and articulate with similar natural or artificial surfaces—called also anatomical occlusion.

10. anatomic forms of natural teeth.
Anatomic teeth : artificial teeth that duplicate the
anatomic forms of natural teeth.
2: teeth that have prominent cusps on the masticating surfaces and that are designed to articulate with the teeth of the opposing natural or prosthetic dentition.
3: anatomic teeth with cuspal inclinations greater than 0 degrees that tend to replica natural tooth anatomy—usage cusp teeth (30 to 45 degrees) are considered anatomic teeth. Modified occlusal forms are those with a 20-degree cusp incline or less—called also anatomical teeth.

11. zero-degree teeth :posterior denture teeth having 0-degree cuspal angles in relation to the plane established by the horizontal occlusal surface of the tooth— called also
zero-degree nonanatomic teeth

12. Supporting area 1: the surface of the mouth
available for support of a denture 2: those areas of the
maxillary and mandibular edentulous ridges that are considered best suited to carry the forces of mastication when the dentures
are in function
Supporting cusps : those cusps or incisal edges of teeth that contact in and support maximum intercuspation.
Usually facial cusps of the mandibular posterior teeth, the maxillary palatal cusps, and the incisal edges of the mandibular anterior teeth

13. Anteroposterior curve (CURVE OF SPEE) : the anatomic curve established by the occlusal alignment of the teeth, as projected onto the median plane, beginning with the cusp tip of the mandibular canine and following the buccal cusp tips of the premolar and molar teeth, continuing through the anterior border of the mandibular ramus, ending with the anterior most portion of the mandibular condyle.

15. Bonwill triangle
eponym for a 4 inch equilateral triangle bounded by lines connecting the contact points of the mandibular central incisor’s incisal edge (or the mid-line of the mandibular residual ridge) to each condyle (usually its mid point) and from one condyle to the other, first described by
Bonwill in 1858 while introducing his Anatomical Articulator

16. Bilateral balanced articulation: also termed balanced articulation, the bilateral, simultaneous anterior and posterior occlusal contact of teeth in centric and excentric positions.

17. working side contacts : contacts of teeth made on the side of the articulation toward which the mandible is moved during working movements.
working side : the condyle on the working side
working side condyle path: the path the condyle travels on the working side when the mandible moves in a lateral excursion.

20. Camper’s plane
a plane established by the inferior border of the ala of the nose (or the average between the two) and the superior border of the tragus of each ear.
called also acanthion-external auditory meatus plane

21. ala-tragus line (CAMPER’S LINE)
a line running from the inferior border of the ala of the nose to some defined point on the tragus of the ear, usually considered to be the tip of the tragus. It is frequently used, with a third point on the opposing tragus, for the purpose of establishing the ala tragus plane. Ideally the ala-tragus plane is considered to be parallel to the occlusal plane. The occlusal plane is at an angle of approximately 10 degrees relative to the Frankfort horizontal plane, when viewed in the mid- sagittal plane.

22. Bennett angle : the angle formed between the sagittal plane and the average path of the advancing condyle as viewed in the horizontal plane during lateral mandibular movements.

23. Christensen’s phenomenon
[Carl Christensen, Danish dentist and educator]: eponym for the space that occurs between opposing occlusal surfaces during
mandibular protrusion.

25. Transverse horizontal axis:
an imaginary line around which the mandible may rotate within the sagittal plane .

26. Adjustable articulator : an articulator that allows some limited adjustment in the sagittal and horizontal planes to replicate recorded mandibular movements.