Bridges

Question 1

for an adhesive bridge, what must the quality and quantity of the tooth tissue be like

Answer 1

minimally restored/good enamel

Question 2

for a conventional bridge, what must the quality and quantity of the tooth tissue be like

Answer 2

heavily restored/broken down

Question 3

what needs to be considered when selection the abutment

Answer 3

• assess status of any existing restorations, if it is questionable then replace
• minimum crown: root ratio 1:1
• if root canal treated, consider a fixed movable design
• if the inclination of the abutment is 15-25 degrees, a conventional bridge is preferred, to avoid black triangles and a difficult path of survival

Question 4

what are the factors to consider when doing a pontic design

Answer 4

cleansability, aesthetics, strength

Question 5

what is the wash-through pontic design

Answer 5

no contact with the soft tissue, functional rather than for appearance

Question 6

where is the wash-through pontic design used

Answer 6

lower molars

Question 7

what is the dome-shaped pontic design

Answer 7

point contact with the soft tissue, aesthetically unpleasing in high smile line cases

Question 8

where the is the dome-shaped pontic design used

Answer 8

lower incisors, premolars or upper molars

Question 9

what is the modified ridge lap pontic design

Answer 9

buccal surface flush with gingiva, palatal/lingual is cut away for cleansability, problems with food packing on palatal/lingual surface can occur

Question 10

where is the modified ridge lap pontic design used

Answer 10

moderate-low smile line anteriors

Question 11

what is the ridge lap pontic design

Answer 11

cleansable if designed carefully, less food packing compared to modified ridge lap, greatest contact with soft tissues, avoid blanching and displacement of gingiva

Question 12

where is the ridge lap pontic design used

Answer 12

long span anteriors, high smile line anteriors

Question 13

what is the ovate pontic design

Answer 13

presses into the ridge to create the illusion that the tooth is emerging out of the gingiva, not utilised commonly by clinicians

Question 14

where is the ovate pontic design used

Answer 14

long span anteriors, high smile line anteriors

Question 15

what is the preparation for anterior adhesive bridge design

Answer 15

• single-winged design: ensure parallel wall of the tooth
• no preparation is required if 0.7mm of interocclusal space is present for the retainer
• a minimal palatal/lingual feather edge or chamfer finish can help with seating of the bridge and increases resistance form

Question 16

what is the preparation for posterior adhesive bridge design

Answer 16

• two-winged design: ensure 5-8 degree taper of abutment teeth
• ensure parallel wall of the tooth
• minimum thickness of retainer 0.7mm
• minimum rest seat preparation 0.5x0.5mm
• a minimal palatal/lingual chamfer finish can help with seating of the bridge and increases resistance form

Question 17

what is the tooth preparation for convention bridges

Answer 17

• outer axial walls 6-15 degree taper
• aim for parallel guideplanes
• non-functional cusp reduction 1.5-2mm
• functional cusp reduction 2mm
• axial reduction; ceramic: 1-1.5mm, PFM: buccal 1.5mm and palatal 0.5-1mm