Clinical Pros

Question 1

jaw reg data

Answer 1

OVD
centre line
high lip line
occlusal plane
arch form (width-lip support)
canine line

Question 2

occlusal guide plane

Answer 2

clear perspex sheet is fixed to the lower base with hot wax to correspond to the occlusal plane on the upper rim
profile of upper rim trimmed by dentist in clinic transferred to occlusal guide plane
provides arch form for setting teeth
mould of teeth should be chosen to correspond to width of canine lines

Question 3

long axis of anterior teeth set

Answer 3

not parallel to centre line

Question 4

setting lower anterior teeth

Answer 4

lower incisor teeth set to uppers
overlap & overjet included
by providing space between anterior teeth in centric relation; the space facilitates the principle of occlusal balance for dentures

Question 5

impact of condylar guidance on lower anteriors

Answer 5

unlock condylar guidance on articulator to provide protrusive movement as indicator of overlap & overjet
the amount of OL/OJ should permit contact of incisor teeth in protrusion
a shallow IGA (incisal guidance angle) is recommended i.e. 10-15o
OL/OJ are assessed at the trial dentures stage

Question 6

marginal ridge position for setting lower posteriors

Answer 6

aim is to provide a common fossa for opposing supporting cusp so marginal ridges must all be at the same level
they can be adjusted by reviewing the long axis of each adjacent tooth

Question 7

summary for setting posterior lowers

Answer 7

• determined by occlusal plane and guides such as centre of mandibular alveolar ridge & retro molar pad
• length of occlusal table determined by mandibular ridge contour; teeth should not be set on an incline
• supporting cusps of maxillary posterior teeth are set to the centre of the lower alveolar ridge
• teeth set according to factors affecting dynamic occlusion

Question 8

sagittal condylar guidance angle

Answer 8

obtained by means of a facebow
if facebow not used it is set at an arbitrary angle of 35o

Question 9

inclination of occlusal plane

Answer 9

also determined by facebow which provides the maxilla to hinge axis relationship
if facebow not used the angle is generally set between horizontal and 10o

Question 10

compensating curves

Answer 10

allow for downward travel of the condyle
compensating curve used to compensate for the difference between the condylar guidance angle and the incisive guidance angle - Christensen’s phenomenon

Question 11

cusp angle

Answer 11

cusp angles interact with the condylar guidance angle and compensating curves in balanced articulation
artificial teeth cusp heights range from 0-30o

Question 12

setting maxillary posteriors

Answer 12

maxillary supporting cusps are set directly over the centre of the lower ridge to direct occlusal loads over the ridge and within the neutral zone

Question 13

factors that affect the shape and contour of complete dentures

Answer 13

• 3 surfaces of complete denture i.e. impression, polished, occlusal
• muscle balance
• aesthetics (tooth position)
• gingival contour i.e. shape/profile, gingival margins, interdental papillae, surface texture

Question 14

biometric guidelines

Answer 14

average dimension or biometric guides from remnant of the lingual gingival margins to replace the lips & cheeks in their pre extraction position

Question 15

uses of incisive papilla in setting teeth

Answer 15

1. centre line
2. labial surface of central incisors; labial aspect of central incisors is 10mm from this distal of incisive papilla forwards
3. centre of canine; line extended horizontally from distal of incisive papilla at right angles to median sagittal plane will indicate position of centre of canine

Question 16

alma gauge

Answer 16

used to determine the vertical & horizontal position of anterior teeth relative to a point on the denture base e.g. incisive papilla

Question 17

requirements of occlusal rim

Answer 17

• well adapted
• stable both on the cast and in situ; rigid
• free from voids
• no thicker than 1mm over residual ridge
• easily removed from working cast
• smooth & rounded
• dimensionally stable at mouth temp
• free of fraena / muscle attachments

Question 18

light cure acrylic resin

Answer 18

• gives optimum retention & stability, valuable for upper or lower rims when little ridge remains
• valuable when occlusal rim bases are to be used as close fitting special trays for wash impressions

Question 19

when are thermoplastic bases useful

Answer 19

• posterior inter ridge distance is small (modification of rims to avoid premature contact in this area is more readily carried out)
• position of the post dam on the upper working cast is uncertain