Mouth Preparation

which teeth will need to be extracted?

• periodontally hopeless teeth

• residual roots

• teeth detrimental to the design of the RPD

• impacted teeth

what is the fate of severely malposed or extruded teeth?

• extraction

• orthodontic correction

• dentoalveolar segment osteotomy

what is wrong here?

mesial drift

How will you correct this?

this is mesial drift of third molar and can be corrected with extraction, orthodontic correction

what are examples of surgical preparations necessary in the case of displaceable soft tissues?

• soft, flabby ridges

• folds of redundant tissue

• surgical stents

• how would you correct malposed teeth or unacceptable counter?

• enameloplasty

• surveyed crown

what are some restorative preparations that you might do to prepare a mouth for an RPD?

• occlusal plane modification

• correction of malposed teeth or unacceptable contour

  • enameloplasty

  • surveyed crown

when is splinting indicated?

when tooth’s bony support is not significantly compromised

what are object8ives of abutment preparation?

• acceptable path of insertion

• esthetics

• comfort

• retention

• stablility

• support

what is a potential seuwnece of events in abutment preparation?

1. guiding plane

2. HOC adjustment

3. retentive groove or depressions

4. rest seats

what bur is used to prepare guiding planes?

cylindrical diamond burs

you should follow _________ when preparing the guiding plane?

the long axis of the tooth

why must you keep the bur parallel with the long axis of the tooth when preparing guiding planes? (rewatch and fact check)

how should guiding planes be prepared

2-4 mm parallel to the long axis of the tooth

which third of the tooth should you prepare the guiding plane in?

occlusal 1/3-2/3

T or F: the guiding plane should be angled

FALSE

• it should be flat

guiding planes are prepared on what surface of the teeth?

proximal

describe the guiding planes in the faciolinugal dimension

rounded in harmony with the existing tooth contour

reciprocating arms are placed on the lingual surface of abutment teeth, in which third of the tooth should the lingual guiding plane for the reciprocal arm be placed?

middle third of the clinical crown

what is the occlusogingival height of the lingual guiding plane preparation for the reciprocating arm?

2-4 mm

what bur should be used for HOC adjustments in abutment preparation?

tapered diamond or burs

adjusting the HOC permits what?

circumferential clasp

what area specifically is adjusted when adjusting the HOC in abutment preparation? (fact check)

prep in location above the original HOC

what is the purpose of a HOC adjustment?

eliminates sharp facioproximal and linguoproximal line angles (B)

HOC adjustments are limited by what?

thickness of enamel, so no more than 0.03” undercut

HOC adjustment is done on which surfaces of which teeth?

• MB of upper molars

• DB or premolars

• ML of lower molars

a retentive groove or depression preparation is done to increase the depth of an undercut and should be proportional to what?

the amount of retention required

why is a retentive groove or depression abutment preparation done?

to increase the depth of an undercut

what bur should be used when increasing the depth of an undercut (retentive groove or depression preparation)

tapered diamond

retentive groove abutment preparations should follow what measurements?

Occlusogingival height: 

Mesiodistal height:

Occlusogingival height: 3 mm

Mesiodistal height: 4 mm

a retentive groove abutment preparation should establish what undercut?

0.01”

what does the following describe?

• gently sloping contoured depression, NOT a sharply defined dimple or pit

• parallel to the gingival margin

• in the line angle area

retentive grooves

retentive grooves should be parallel to what?

gingival margin

dimples prepaared into tooth are used for what?

I bar

• done with a #4 round bur

occlusal rest seats should be ___ at the marginal ridge 

1.5 mm

occlusal rest seats are 1.5mm at the marginal ridge and ___ deeper at the deepest portion of the rest seat

the occlusal rest seat should be lass than ___ degrees

90 degrees

what bur should be used to prepare an occlusal rest seat?

#4 or 6 round carbide or diamond

line angle should be ___ in an occlusal rest seat preparation

rounded

to round the line angle in an occlusal rest seat preparation, what bur should you use?

tapered diamond

the depth and inclination of an occlusal rest set prep should be checked with what?

wax

which of the following is NOT used when finishing and polishing of an occlusal rest seat?

white disk

what is used when finishing and polishing an occlusal rest seat preparation?

fine diamond or green stone and rubber point

an embrasure clasp occlusal rest seat should be ____ - ____ mm deep

1.5-2 mm

an embrasure clasp occlusal rest seat should be ____ - ____ mm wide

3.0 - 3.5 mm

cingulum rest seat shapes ?

• crescent or inverted V-shaped

• ledge-shaped

• ball or lug

what bur is used for a wedge-shaped cingulum rest seat?

#37 inverted cone bur

the wedge-shaped cingulum rest seat should go from where to where?

one marginal ridge to the other

what are the dimensions for a wedge-shaped cingulum rest seat?

MD width:

FL width: 

IG depth: 

• MD width: 2.5-3 mm

• FL width: 1.5 mm

• IG depth: 1.5 mm

which rest seat?

• axial wall: parallel to the path of insertion

• gingival floor: 1-1.5 mm wide

• 90 degrees

• flat end diamond bur or tapered fissure bur

ledge-shaped

which rest seat?

• #37 inverted cone bur

• round internal line angle

• one marginal ridge to the opposite

• MD width: 2.5-3 mm

• FL width: 1.5 mm

• IG depth: 1.5 mm

crescent or inverted V-shaped

which rest seat?

• like a small occlusal occlusal rest seat

• #4 or #6 round bur

• marginal ridge reduction

• junction of middle 1/3 and gingival 1/3

ball or lug rest seat

crowns that are used as abutments of RPD are called…

surveyed crowns

the following are characteristics of what?

• more ideal retentive contour

• definite guiding plane

• optimum occlusal rest

• effective reciprocation

surveyed crowns

in what case is additional reduction for the rest seat needed?

in surveyed crown preparation