Fixed Prostodontic Lecture 28A

Front 1

Why is the occlusal reduction and incisal reduction important? (1.5-2.0 mm)

Back 1

-Optimum tooth anatomy reproduction
-Space for substructure of PFM or all-ceramic crowns
-Long-term wear of metal crowns
-Optimum esthetics for tooth-colored crowns
-lab tech. can fabricate the crown but anatomy, esthetics, longevity will suffer

Front 2

Flat occlusal tooth anatomy reduction will result in

Back 2

Flat and wide occlusal surfaces on crowns

Front 3

-Flat axial surface will result in
-Under-reduced axial surfaces will result in

Back 3

-Over-contoured crowns and wide occlusal tables
-Over-contoured crowns and compromised esthetics

Front 4

For adequate retention, a taper of no more than ____ from long axis of tooth.

Back 4

-10-15 degree
-Operator should aim for at least 4 mm of axial wall

Front 5

If a build-ups is required how do you improve the retention of build-up materials

Back 5

-Improve dentinal bonding agent
-Retentive grooves
-Undercuts
channels
-Retentive pins

Front 6

TOC on preparations serving as abutments for individual crowns or fixed partial dentures should range between ___ degrees.

Back 6

-10-20 degrees

Front 7

__ mm of OC dimension is required for anteriot teeth and premolars. Because of their typically higher TOC.

Back 7

3 mm

Front 8

___ mm of OC dimension is suggested for prepared molars

Back 8

4 mm

Front 9

If these dimensions are unable to be met, ___

Back 9

Auxillary retention and resistance devices such as grooves and boxes are suggested to improve the preparation

Front 10

An OC/FL ratio of ___ is recommended for ALL teeth

Back 10

0.4

Front 11

Molars are usually prepared with greater occlusal congergence than premolars and anterior teeth and possess a shorter occlusocervical dimension than other teeth. (T/F)

Back 11

True: Molars have less favorable OC/FL dimension ratio. So they could benefits from auxiliary tooth prep

Front 12

Proximal grooves provided complete resistance to ____ forces, whereas facial or lingual grooves provided only partial resistance to ___ dislodgement

Back 12

-Faciolingual forces
-Faciolingual

Front 13

Subgingival finish lines frequently are required for the following reasons?

Back 13

-To provide adequate OC dimension for R&R form
-Extend beyond dental caries, fractures, erosion/abrasion or tooth structure defects
-Produce cervical crown ferrule on endo. treated teeth
-Improve esthetics of discolored teeth

Front 14

Many studies have supported the use of supragingival finish lines whenever possible to ensure periodontal health (T/F)

Back 14

True

Front 15

Finish lines should be located ___ when R&R form, tooth condition, esthetics permit. When subgingival finish lines are required, they should extend where?

Back 15

-Supragingivally
-Should not extend to epithelial attachments

Front 16

Chamfer advantages?

Back 16

-Easy to form, readily visible on the prepared tooth, impression and die.
-Adequate bulk for restorative ridigity
-Recommended that chamfer finish lines for all-metal crowns possess a minimum depth of approximately 0.3 mm

Front 17

Selection of finish lines used with metal ceramic crowns should not be based on marginal fit but on ___.

Back 17

-Personal preferences, esthetics, ease of formation, type of metal-ceramic crown (metal marginal collar vs. collarless design) being fabricated

Front 18

___ of translucent porcelain (not including metal and opaque) is required to repdroduce the color of a shade guide.

Back 18

-1.0mm

Front 19

Shoulder finish lines are recommended for what?

Back 19

-All ceramics crowns that are not etched and bonded to teeth
-Either shoulder or camfer

Front 20

It has not been advantageous to increase all-ceramic crown finish line depth beyond 1 mm with the use of a semitranslucent all-ceramic material (T/F)

Back 20

True

Front 21

Axial and incisal/Occlusal Reduction depend on what?

Back 21

-Anatomy of tooth, tooth position, alignment of tooth
-Type of restorative material being used.
-Regardless of reduction depth = there MUST be normal contours, appropriate esthetics, adequate strength

Front 22

A reduction depth of at least __ mm should be used for occlusal surfaces, while an axial depth at least __ mm is recommened.

Back 22

-1.00 mm
-0.5 mm

Front 23

A general consensus is that ___ is a recommended reduction depth for axial surfaces.
The incisal/occlusal reduction depths are recommended to be ___ mm

Back 23

-1.0-1.7 mm
-2.0-2.5 mm

Front 24

Studies have found that optimum esthetifcs usually require an axial reduction greather than ___. As in the case of a metal-ceramic restoration, an occlusal reduciton of ___ mm is recommended for all-ceramic preparations.

Back 24

-1.00 mm (Closer to 1.5mm)
-2.00 mm

Front 25

Studies have shown that lingual effect on strength is likely to only impact the structural integrity of all-ceramic restorations (T/F)

Back 25

True

Front 26

Strength of all-metal and metal-ceramic restorations is either minimally enhanced or not enhanced but rounded line angles are still recommended b/c they facilitate lab rpoduces and optimize fit (T/F)

Back 26

True

Front 27

Wha tis the general consesus about tooth surface texture?

Back 27

-Surface roughness improves crown retention with zinc phospate luting cements
-However; no relationship b/t roughness and adhesion has been found for cements as polycarboxylate, GI, resin-based cements