Proximal Relationships of Neighbouring Teeth

Question 1

what are the 2 main headings of this feature of static factors (proximal relationships)

Answer 1

1. interproximal contacts

2. interproximal space

Question 2

Proximal CONTACT

Answer 2

point at which two neighbouring teeth touch,

• at the point of GREATEST PROXIMAL CONVEXITY,
• with the remaining surfaces sloping away from the proximal contact in all directions to create:
• space (to give FACIAL, LINGUAL and OCCLUSAL EMBRASURES)

Question 3

IDEAL proximal contact

Answer 3

1. occurs at the MOST CONVEX point of a proximal surface
2. FACIO-LINGUAL PLANE (OCCLUSAL PLANE): occurs in the facial one-third in all teeth (except molars = middle one third)
3. VERTICAL PLANE (FACIAL PLANE): occurs in occlusal-incisal one-third

Question 4

“stepping” of proximal contacts in the Maxillary Arch

Answer 4

Distal contacts on incisors occur slightly more cervically than mesial contacts, similarly dropping lower as you move to the posteriors

Question 5

Proximal contacts in the Mandibular Arch

Answer 5

Incisor contacts all at the same level, canine contacts slightly more cervically than incisors, premolars: more cervical still; molars: more apical than premolars.

Question 6

Embrasures

Answer 6

spaces created around the proximal contacts by the splayed nature of tooth surfaces sloping away from the proximal contact in all directions, ESP. in CERVICAL and LINGUAL direction

Question 7

function of embrasures

Answer 7

creates space for investing and supporting tissues of the teeth

Question 8

the 4 embrasures

Answer 8

1. lingual
2. occlusal
3. buccal
4. gingival embrasure (when the col has receded)

Question 9

largest embrasure

Answer 9

lingual; as all proximal contacts (except molars’) are in the facial one-third & tooth crowns constrict towards the lingual

Question 10

3 factors can disrupt embrasures and proximal contacts

Answer 10

1. tooth imbrication
2. tooth migration
3. tooth loss/failure to erupt

Question 11

4 effects of migrations and impactions

Answer 11

1. unfavourable axial alignment
2. unfavourable marginal ridge height relationships
3. disruption of occlusal “plane”
4. stagnation-promoting angles

Question 12

3 more effects of migrations and impactions

Answer 12

1. distortion & cramping of periodontal tissue space
2. loss of space, in the horizontal plane, in dental arch
3. abnormal proximal contact relationships - from convexity to concavity

Question 13

significance of ideal proximal relationships (arrangement of single-units in multi-unit arches with proximal relationships): 2 reasons

Answer 13

1. allows development of one unit at a time

2. allows greater adaptability to change: loss of one unit at a time

Question 14

significance of ideal proximal relationships: 2 more reasons

Answer 14

3. a more resilient mechanism for coping with forces delivered to teeth
4. gives arch integrity, w the following advantages:
   - maintains interproximal spaces, coronally and between roots
   - dissipation of horizontal (mesial-distal force) w minimal torqueing
   - favours atraumatic gliding-contact relations
   - efficient function of muscles and joints
   - maintains regular arch form in two dimensions
   - maintains occlusal relationships
   - streamlines the passage of food off the occlusal embrasures