2 - Bridgework 2

Question 1

What are the different types of bridges that contain a conventional component?

Answer 1

• fixed fixed
• cantilever
• fixed moveable
• hybrid bridge
• spring cantilever

Question 2

What is meant by a conventional component of a bridge?

Answer 2

The retainer is a crown

Question 3

What are the types types of fixed fixed conventional crowns?

Answer 3

• all ceramic
• metal ceramic

Question 4

What are the advantages of conventional fixed fixed bridges?

Answer 4

• robust design
• maximum retention and strength
• abutment teeth are splinted (beneficial in cases involving perio)
• can be used for longer spans
• laboratory construction is simple

Question 5

What are the disadvantages of conventional fixed fixed bridges?

Answer 5

• prep difficult due to parallelism
• prep must be minimally tapered
• common path of insertion for abutments
• removal of tooth tissue

Question 6

What effect does over taper have on conventional fixed fixed bridge prep?

Answer 6

Reduces retention of bridge as it can slide of in different directions

Question 7

What are the advantages of conventional cantilever bridges?

Answer 7

• conservative design (only one tooth prepped)
• laboratory construction simple
• no need to parallelism

Question 8

What are the disadvantages of conventional cantilever bridges?

Answer 8

• short span
• rigid to avoid distortion (more prone to fracture)
• mesial cantilever preferable

Question 9

Why is a mesial cantilever preferable?

Answer 9

• pontic more anterior to retainer
• occlusal contact typically occurs distally first
• can cause a seesaw action if pontic is distal to retainer, causing continual stress to abutment tooth and retainer

Question 10

Describe a fixed moveable bridge.

Answer 10

• rigid connector at the distal of the pontic and a moveable connector mesially
• crown on the more anterior abutment tooth with dovetail cut out - pontic has dovetail to attach to mesial retainer - Pontic attached to distal retainer

Question 11

When is a fixed moveable bridge indicated?

Answer 11

When the abutment teeth long axises are not parallel or parallel prep is not possible due to surrounding teeth

Question 12

What are the advantages of fixed moveable bridges?

Answer 12

• prep doesn’t require common path of insertion
• each prep is designed to be retentive independent of the other prep
• more conservative
• allows minor tooth movement
• can be cemented in two parts

Question 13

What are the disadvantages of fixed moveable bridges?

Answer 13

• length of span limited
• laboratory construction more complicated
• possible difficulty cleaning beneath joint (requires excellent OH)
• no provisional bridge

Question 14

What is a hybrid bridge?

Answer 14

• fixed fixed design
• one retainer is conventional
• one retainer is adhesive

Question 15

What are the disadvantages of a hybrid bridge?

Answer 15

The adhesive wing can debond but the bridge will remain in place due to the crown retainer, the wind then becomes a plaque trap and can develop secondary caries

Question 16

What is a spring cantilever bridge?

Answer 16

One pontic (anterior) attached to the end of a metal arm that runs over the palate to a rigid connector on the palatal side of a posterior connector (historical)

Question 17

What are the advantages of a spring cantilever bridge?

Answer 17

• use if space is between upper incisors
• adjacent anteriors do not require prep
• posterior tooth that is already restored can become abutment

Question 18

What are the disadvantages of a spring cantilever bridge?

Answer 18

• only replace upper incisor teeth
• difficult to clean beneath palatal connector
• can irritate palatal mucosa
• pontic can move around due to springiness of palatal arm

Question 19

What do you evaluate when examining abutment teeth?

Answer 19

• must be able to withstand forces that were previously directed to missing teeth
• supporting tissues should be healthy (free from periapical and periodontal disease)
• crown to root ratio ideally 2:3