Fixed Partial Dentures

Question 1

what is a dental bridge?

Answer 1

supports artificial tooth on one or both sides of the abutment

Question 2

What is a pontic?

Answer 2

the suspended part of the bridge that replaces a missing natural tooth

Question 3

what is an abutment?

Answer 3

the prepared tooth or implant-retained post that supports the bridge

Question 4

what is a retainer in a bridge?

Answer 4

the crown or partial crown that supports the pontic

Question 5

what is a connector?

Answer 5

the section that joins the unit (retainer and pontic) together

Question 6

what is a pier?

Answer 6

the intermediate abutment used as a centre support in a long span bridge

Question 7

what are the types of dental bridges?

Answer 7

fixed-fixed bridge
fixed-movable bridge
cantilever bridge
spring cantilever bridge
maryland or minimum preparation bridge

Question 8

what are the advantages of a fixed-fixed bridge?

Answer 8

strong and retentive
allows for single or multiple pontics

Question 9

what are the drawbacks of a fixed-fixed bridge?

Answer 9

requires parallel abutments which can lead to over preparation of the tooth potentially weakening the tooth and endangering pulp tissues

teeth do not move independently in function and can lead to cementation failture

Question 10

what are the advantages of fixed-movable bridge?

Answer 10

conservative tooth structure is maintained (doesnt require over preparation)

suitable for divergent or nonparallel abutments

enables stress breaking situation to exist in complex bridges

two paths of insertion can occur if abutments are not parallel (independently prepared teeth)

Question 11

what are the disadvantages of fixed-movable bridge?

Answer 11

time-consuming
increased expense
temporary bridge preparation is more difficult due to tilting of abutment teeth

Question 12

what are some advantages of cantilever bridge?

Answer 12

abutments carries occlusal load

occlusion is protected against damaging rotational forces

conservative design (no parallel abutments needed)

at least two abutments are needed to support bridge (exception if abutment is strong canine or molar)

Question 13

what are some disadvantages of cantilever bridge?

Answer 13

pontic is limited to one or two units (due to leverage forces)

possible rotations (especially without proximal contact with adjacent teeth)

Question 14

what are the potential issues of cantilever bridge?

Answer 14

potential rotations without proximal contacts of adjacent teeth

Question 15

what are the design rules of spring cantilever bridge?

Answer 15

rigid bar, no post dam or bead lines, highly polished fitting surface, 4mm wide bar, no contact with gingival tissues

Question 16

what are the clinical applications of spring cantilever bridge?

Answer 16

ideal for replacing anterior tooth with diastema

Question 17

what are some advantages of a maryland/ minimum preparation bridge?

Answer 17

less invasive

minimal tooth preparation

Question 18

what are the potential issues of maryland bridge?

Answer 18

debonding can occur with excessive lateral or occlusal load

not suitable for certain conditions (severe tooth wear, parafunction or insufficient interocclusal clearance)

Question 19

what are advantages of implant-supported bridge?

Answer 19

aesthetics
maybe retrievable (screw-retained)
no tooth preparations
preservation of exisiting bone

Question 20

what are the disadvantages of implant-supported bridge?

Answer 20

prohibitive cost
time-consuming clinical and laboratory procedures
gingival aesthetics can be difficult

Question 21

How do you ensure the strength of the framework is sufficient?

Answer 21

proper design
material (alloys, ceramics and polymers)
health and position of abutment teeth

Question 22

what is required during the selection of abutment teeth?
Hint: there are 4 requirements

Answer 22

ante’s law
crown/root ratio
root configuration
periodontal ligament area

Question 23

what is the optimum crown:root ratio?

Answer 23

1:2, minimum being 1:1

Question 24

what type of retainers can be used?

Answer 24

full crowns
3/4 crown
post and cores
modified class III or IV inlays (with pins)
wings

Question 25

when are retainers ideal?

Answer 25

with least bulk resist distortion under forces of mastication require removal of minimal tooth substance self-cleansing aesthetically acceptable

Question 26

for a connector in the anterior area what should the reinforcement look like?

Answer 26

horizontal reinforcement in lingual direction

Question 27

what shape of connector groove should be avoided?

Answer 27

avoid V-shape grooves, use U-shape instead

Question 28

what is the minimum depth of MCR connectors recommended from 3-unit brige?

Answer 28

3x3mm

Question 29

what dictates pontic design?

Answer 29

aesthetics function ease of cleaning patient comfort maintenance of healthy tissue

Question 30

what are the types of pontics?

Answer 30

saddle/ridge lap modified ridge lap hygienic/sanitary conical/dome shape ovate

Question 31

what is a saddle/ridge lap pontic?

Answer 31

this pontic looks like a natural tooth and replaces all missing contours, recreates emergence profile it fills the embrasures and overlaps the ridge with large concave tissue contact

Question 32

what is a disadvantage of a saddle/ridge lap pontic?

Answer 32

very difficult to maintain hygiene often causes tissue inflammation

Question 33

what is a modified ridge lap pontic?

Answer 33

gives the illusion of a complete tooth, it still occupies most of the area of the missing tooth except it eliminates concave area has convex shape tissue contact area lingual surface should have slightly deflective contour to prevent food packing and minimise plaque accumulation contact is diamond or 'T' shaped

Question 34

what is a hygienic pontic?

Answer 34

a self-cleansing space of 3mm left below the pontic so tongue and cheeks can remove food build up

Question 35

what are some disadvantages of hygienic pontic?

Answer 35

poor aesthetics possible entrapment of food particles

Question 36

what is a conical/dome-shaped pontic?

Answer 36

contacts ridge in one spot and allows for good oral hygiene

Question 37

what is a disadvantage of conical/dome-shaped pontic?

Answer 37

poor aesthetics

Question 38

what is a fixed-fixed bridge?

Answer 38

a bridge where the pontic is supported rigidly on either side by one or more retainers (abutment teeth)

Question 39

what is important for abutment teeth?

Answer 39

they are stable have no caries have no periodontal conditions

Question 40

what is ante's law?

Answer 40

states the total root surface area of all teeth that will support bridge must be equal or exceed total root surface area of teeth being replaced

Question 41

what is an exception to ante's law?

Answer 41

when opposing teeth are apart of a removable denture - they cannot produce same biting force as natural dentition

Question 42

what may short clinical crown have?

Answer 42

grooves or pins - increase retention by creating larger surface area moveable connector - reduces pressure on retainer

Question 43

why is more inter-radicular (alveolar) bone better for abutment tooth support?

Answer 43

increases periodontal ligament area, providing better support and load distribution for abutment teeth

Question 44

how does root alignment affect abutment support?

Answer 44

roots aligned perpendicular to occlusal plane provide better resistance to vertical forces than tilted teeth - improving abutment support

Question 45

which single-root shape offers better support: elliptical or circular?

Answer 45

elliptical cross-sections offer better support due to greater surface area and improved resistance to rotational forces

Question 46

how do divergent molar roots compare to convergent ones in terms of support?

Answer 46

divergent roots provide better support by increasing the root spread and alveolar bone, improving resistance to tipping and lateral forces

Question 47

what are 4 ideal root features of an abutment tooth?

Answer 47

high inter-radicular bone perpendicular root alignment elliptical cross-section (single-rooted teeth) divergent molar roots

Question 48

what must the margin of a crown have?

Answer 48

accuracy of fit demonstrate permanent stability of shape withstand effects of masticatory stress produce a smooth, gapless transition to prepared tooth

Question 49

what is a fixed-movable bridge?

Answer 49

when a pontic is supported on one side, usually the distal by one or more retainers (abutment teeth) and the other part is modified with a movable joint (precision attachment) to allow a small degree of movement

Question 50

what is a centilever bridge?

Answer 50

when the pontic is supported on one side by one or more retainers (abutment teeth)

Question 51

what is a spring cantilever bridge?

Answer 51

the pontic is supported by a connecting bar to one or more retainers (abutment teeth)

Question 52

what is a maryland/minimum preparation bridge?

Answer 52

when thin retainer wings are cemented to the lingual/palatal surface of the enamel on retainers (abutment teeth) by composite resin using acid-etch technique

Question 53

what type of bridge can the maryland/minimum preparation bridge be?

Answer 53

fixed-fixed fixed-movable cantilever

Question 54

how is the maryland/minimum preparation bridge bonded?

Answer 54

with adhesive composite resin using acid-etch technique

Question 55

when is a modified ridge lap pontic the preferred design?

Answer 55

when aesthetics and hygiene are important offers natural appearance from front with minimal tissue contact for easier cleaning

Question 56

why is the hygienic pontic contraindicated in aesthetic zones?

Answer 56

does not contact the ridge and has open space underneath making it visually unappealing

Question 57

in a patient with poor oral hygiene, which pontic design is more suitable?

Answer 57

hygienic or conical pontic both designs have minimal ridge contact and easier to clean

Question 58

when should you avoid using a saddle/ridge lap pontic?

Answer 58

in any situation with poor hygiene

Question 59

what pontic type would be used in the mandibular posterior region where ridge is narrow and tapered?

Answer 59

conical/dome-shaped pontic it suits narrow ridges, minimal tissue contact and is good for hygiene and posterior occlusion

Question 60

a patient is missing their 36, the adjacent 35 and 37 are both strong and well-aligned. What is the best bridge type?

Answer 60

fixed-fixed bridge

Question 61

a patient is missing a 45, the 44 is tilted mesially, the 46 is upright. What type of bridge would accomodate the misalignment?

Answer 61

fixed-movable bridge

Question 62

a patient has lost their 22, the 21 is heavily restored but canine is strong. what bridge would be considered?

Answer 62

cantilever bridge