RPD system of design: connectors

Question 1

What are connectors

Answer 1

a term used to describe the rigid part of a partial denture that unites other components

Question 2

what are the two types of connectors

Answer 2

major and minor

Question 3

What do minor connectors do

Answer 3

• join component such as rests to the major connector

- transfer functional stresses to and from the abutment teeth

Question 4

What should the characteristics of minor connectors be

Answer 4

• rigid
• finish above (towards occlusal surface) the survey line on teeth
• cross the gingival margin at right angles (to maintain gingival health)
• cover as little gingival tissue as possible
• avoid multiple ‘windows’

Question 5

What does a major connector do

Answer 5

• connects components on one side of the arch to components on the other side of the arch

Question 6

What are the guidelines for a major connector

Answer 6

• rigid
• avoid covering gingival margins
• comfortable (as few edges as possible)
• cover as little tissue as is consistent with rigidity

Question 7

what modifications can be made for major connector

Answer 7

• base distribution
• need for tissue support
• need for indirect retention
• anatomical limitations
• prognosis of the dentition (can modify to allow for extra tooth/teeth to be added)
• previous denture influence (don’t fix things if they are happy the way things are)

Question 8

What are the two kinds of major connectors

Answer 8

plates/strap

bar

Question 9

What is the main advantage of plates

Answer 9

can be made thinner in cross-section and still maintain rigidity (can be as little as 0.5mm)

Question 10

When would you opt for a plate over a bar

Answer 10

mucosa supported designs

Question 11

In what instance is a plate design recommended in the mandibular arch? why?

Answer 11

when there is no space availiable for a bar (plate designs may cover gingival margins)

Question 12

What is the main advantage of a bar

Answer 12

less mucosal coverage

Question 13

what is the main disadvantage of bars

Answer 13

need to be thick e.g. a lingual bar should be 2mm thick

Question 14

For what craddock classification are bars the common choice

Answer 14

class 1, also mandibular arch as little space

Question 15

What are the choices for upper metal connectors

Answer 15

Anterior palatal strap
Mid-palatal strap
Posterior palatal strap
Arterior and posterior strap (ring)
Full palatal coverage

Question 16

What are the choices for upper acrylic maxillary connectors

Answer 16

anterior palatal strap
mid-palatal strap
posterior palatal strap
anterior and posterior strap (ring)
horseshoe
full palatal coverage

Question 17

Names of 3 common maxillary connectors (acrylic)

Answer 17

“spoon”
“modified spoon”
“Every”

Question 18

Common mandibular connectors (metal)

Answer 18

lingual bar
lingual plate
dental bar
sublingual bar
labial bar (rare)

Question 19

What is pretty much the only instance you’d use a labial bar

Answer 19

only when lower anterior teeth are lingually inclined therefore preventing lingual bar

Question 20

Where should mandibular bar connectors be positioned ideally (and how much space do you need in total)?

Answer 20

at least 3mm below gingival margin on lingual side, 1 mm clearance to functional floor of mouth

8mm in total (4mm height of bar)

Question 21

What is the strongest type of bar

Answer 21

anterior and posterior (ring)

Question 22

Advantages of a anterior and posterior ring

Answer 22

• little coverage of gingival tissue
• a rigid connector
• wide relief of gingival margins to prevent food impaction

Question 23

Disadvantages of an anterior and posterior ring

Answer 23

• less support to the free-end saddle across the hard palate (narrow coverage)
• lots of edges that some patients might find uncomfortable
• greater cross-sectional thickness

Question 24

Advantages of full palatal coverage (metal)

Answer 24

• a rigid connector
• wide relief of gingival margins to prevent food impaction
• support across the hard palate for the free end saddle
• less edges that patient might find uncomfortable
• thinner cross section

Question 25

Disadvantages of full palatal coverage

Answer 25

the mucosal tissue is covered - no natural sensation

Question 26

What are some additional functions of major connectors

Answer 26

• assist stability by resisting functional forces in a horizontal direction
• provide indirect retention

Question 27

What does beading (creating a food line) do

Answer 27

prevents food ingression

offers rigidity around plate

Question 28

Where should beading be

Answer 28

all the way around the border but stops 3mm from the gingival margin

Question 29

what influenced wether the design of a major connector is open or closed

Answer 29

the amount of gingival coverage, to do with passing saliva, an open design is better for their health but it isn’t always possible or adviseable

Question 30

What is needed on edentulous areas to check the fit and ensure the denture doesn’t rotate?

Answer 30

a stop

Question 31

the position of teeth can really influence the shape of a denture, how do you establish this

Answer 31

a tooth trial

Question 32

What are the dimensions of a rest

Answer 32

thickness - 0.5mm minimum, 1mm at junction with minor connector

Question 33

What are the dimensions of a lingual bar

Answer 33

height: 4mm
thickness: 2mm
oval or half pear shape

Question 34

what are the dimensions of a sublingual bar

Answer 34

thickness: 4mm (‘kidney shaped’)

Question 35

What are the dimensions of maxillary connectors

Answer 35

5mm clearance clearance from gingival margin

bead: 0.5mm deep to 1mm wide

Bars: width - 6mm, thickness - 1.5mm
Plate/strap: thickness 0.4 mm minimum

Question 36

What are the dimensions of minor connectors

Answer 36

width: 2mm
thickness: 1.5mm

Question 37

what are the dimensions of a cast clasp

Answer 37

length: 15mm to engage 0.25mm