Week 7 Chptr.6 Occlusion

Question 1

Occlusion

Answer 1

Occlusion describes the relationship of the mandibular and maxillary teeth when the teeth are closed together or during excursive movements when the teeth are touching.

Question 2

Facial profile class 1

Answer 2

• Facial profile of a person of Class I forms a straight line from top half of face (forehead) to chin (orthognathic)

Question 3

Tips to remember

Answer 3

Anterior teeth have less bone coverage, therefore their buds begin formation earlier than posterior teeth. This results in most of the anterior teeth erupting before the post teeth.
Some posterior teeth must wait until growth has occurred in the mandible, as they are trapped under the ramus of the mandible

Question 4

Intercuspation

Answer 4

At 16 months primary molars erupt and establish
-vertical height of primary occlusion, -Intercuspation, the mesial-distal and buccal-lingual relationship that determines how the upper teeth will touch, hit and interlock with lower teeth.

Question 5

Position and Sequence of Eruption

Answer 5

The upper primary first molars also help establish the anteroposterior (mesial-distal)
relationship of the remaining deciduous teeth because their presence allows the canines and 2nd deciduous molars to erupt around them.
n The primary dentition erupts in a more upright position than permanent teeth replacements.
n Eruption is Complete at 2.5 years for deciduous teeth

Question 6

Primary Occlusion

Answer 6

3 possible anteroposterior (mesial/distal) molar relationships in PRIMARY OCCLUSION…
1. Mesial Step- 2nd primary mandibular molars (distal surface) are situated more mesial (anteriorly) than the maxillary molars. (most common)
2.
Flush Terminal Plane- 2nd primary mand molars even with each other on both arches
3.
3. Distal Step- 2nd primary mandibular molars are situated more distal (posterior) than the maxillarv

Question 7

Development of Mesial Step

Answer 7

Development of Mesial Step
• permanent 1st molars erupt and push up against the deciduous molars causing the primate spaces to close ~ causing a chain reaction that pushes all of the interproximal spaces closed (mesial drift)
• a mesial step is further enhanced as the deciduous molars exfoliate and are replaced by narrower permanent premolars
• Extra space is created called LEEWAY SPACE
• mesial step occurs in majority of individuals

Question 8

Leeway space

Answer 8

n Leeway space is extra space that deciduous canines and molars occupy to help save room for their
permanent successors.
Permanent teeth take up less space.

Question 9

development of the Mesial Step cont.

Answer 9

ㅁ
the mandible continues to grow later than the maxilla
O this mesial advancement heads the patient toward a class I relationship (will be discussed later)
a if further growth of the condyle head occurs, an
extreme mesial step results in a class III relationship
a class II relationship results if the mandible does not continue to grow or if the maxilla outgrows the mandible
it is possible for this type of relationship to occur on just one side and the other side remaining in class 1

Question 10

Horizontal
Alignment

Answer 10

• If this balance of forces is disturbed, a malocclusion, or an abnormal alignment of the teeth within the dental arches, can result. example: tongue thrusting causes maxillary anterior teeth to protrude
• Or overdeveloped lower lip causes
RETRUSION of the lower teeth

Question 11

Malocclusion of teeth

Answer 11

• Can be detrimental if it adversely affects appearance, comfort, or function
• Can occur in Class I, II, III jaw relationships
• Can be an individual tooth or groups of teeth that affect the occlusal plane
• Labioversion/buccoversion: a tooth out of alignment to the labial or buccal
• Linguoversion: tooth out of alignment that is lingual

Question 12

Supraeruption, crossbite, edge to edge

Answer 12

• Supraeruption: a tooth that is overerupted, abnormally long relative to the rest of the occlus surfaces
• Crossbite: a tooth or teeth that are out of alignment in a buccal/lingual version”
• Edge to edge: max incisal edges line up with touching mand incisal edges with NO vertical

Question 13

Horizontal Alignment

Answer 13

• balance between tongue and facial muscles allows proper horizontal alignment of teeth

Question 14

Retrusion

Answer 14

The lower teeth will be pushed back from under developed lip

Question 15

Intercuspation

Answer 15

n The intercuspation of the teeth helps prevent tooth deviations in a buccal or lingual direction.
u When the jaws are closed, the buccal cusps of the mandibular posterior teeth are interlocked between the buccal and lingual cusps of the
26
maxillary teeth. (like gears)

Question 16

Vertical Alignment

Answer 16

Question 17

Vertical alignment

Answer 17

• from a lateral view all the teeth show a slight mesial inclination, with the possible exception of the maxillary third molar 18, 28 (straight)
• anterior teeth have a slight labial protrusion of crowns and their roots seem to incline laterally
O in other words, the anterior teeth tip out to the side and toward the front

Question 18

Centric relation

Answer 18

1. A relationship of the upper jaw to the lower jaw (centric relation).
   Centric relation is defined as the relationship of the mandible to the maxilla when the condyles of the
   TMJ are in their most upward, backward and unstrained position (mandible is pushed backwards)
   Position of the mandible relative to maxilla determined by the maximum contraction of the muscles of the jaw

Question 19

Centric Occlusion

Answer 19

2. A relationship of the maxillary teeth to the mandibular teeth (centric occlusion).

Question 20

Acromegaly

Answer 20

n
Acromegaly: is a condition where a crossbite all the mandibular teeth occurs u WHY? growth hormone causes the mandible to grow faster than the maxilla

Question 21

There are 2 basic classifications of occlusion:

Answer 21

1. Skeletal; based on the relationship of the bone of the maxilla to the bone of the mandible
   1 Referred to as skeletal classification- because related to the bones.
2. Dental; based on the relationship of the teeth of the mandible to the teeth of the maxilla.
   • Referred to as dental classification because it is concerned with the teeth.

Question 22

Skeletal classification
3 classes

Answer 22

classes of relationship:
a Class I: The maxilla and mandible are in normal
relationship to each other.
B neutroclusion
§ Class /I: The mandible is retruded. (it has a distal relationship with the maxilla.)
• Retrognathic.
B Class III: The mandible is protruded.(it has a mesial relationship with the maxilla.) Prognathic

Question 23

Occlusion inventor

Answer 23

• Dr. Edward Angle defined classes of jaw relationships in 1887.
• Each class of occlusion is defined by the relationship of the 1st teeth to erupt in the permanent dentition, max/mand 1st molars
• If the 1st molars are absent, the relationship btw the max/mand canines
• “ideal occlusion” the teeth are aligned within each arch so that they fit together and function harmoniously, interdigitation, in Class |
relationshin

Question 24

Class 1

Answer 24

Question 25

Class 2

Answer 25

Question 26

Class 2
2 Divisions

Answer 26

Question 27

Class 3

Answer 27

Question 28

Lateral Mandibular Glide (Lateral
Excursion)

Answer 28

In lateral excursion the mandible moves toward the right or left side.
u The side to which the mandible moves is refer to as the working side, and the other side is referred to as the nonworking side (when no teeth are in contact with each other).

Question 29

Canine rise

Answer 29

In lateral mandibular glide, only a few pairs of interlocking cusps make occlusal contact, the canines carry the bulk of the contact
This is referred to as CANINE RISE
As mand canine opens and glides down the lingual surface of the max canine

Question 30

Group function

Answer 30

it is common to have the premolars/canines occluding in lateral excursion
u when the premolars also occlude during lateral
excursion it is called group function u The canines should still be the dominant occluding teeth, the premolars only assist through part of the lateral side

Question 31

Premature Contact

Answer 31

if one tooth hits more than the others, it becomes an interference and bears more force than the others, becoming a premature contact area

Question 32

Stolarized Molars

Answer 32

• The max first molar is tipped mesially so that it touches the mandibular 1st molar and 2nd molars
• In contact with 2
• teeth

Question 33

Black’s classification of cavities
(see photos on following pgs.) 5 classifications
Class 1

Answer 33

Class I
•Cavities located in pits or fissures. These are located in the occlusal surfaces of molars and premolars, the occlusal two-thirds of the buccal surfaces of molars, the lingual surfaces of upper incisors, and occasionally in the lingual surfaces of upper molars.

Question 34

Black’s classification of cavities
(see photos on following pgs.) 5 classifications

Answer 34

Class 2
Cavities located in the proximal surfaces of molars and premolars.

Question 35

Class 3

Answer 35

Class III
n Cavities in the proximal surfaces of canines. and incisors not involving the incisal angle

Question 36

Class 4

Answer 36

Cavities in the proximal surfaces of incisors or canines which also involve one or both of the incisal angles.
Class V

Question 37

Class 5

Answer 37

Cavities located in the gingival third of the labial, buccal, lingual, or palatal surfaces of any tooth.