NBDE Part 2 – Orthodontics UPDATED
ACTUAL Exam Questions and CORRECT
Answers
Indirect bonding technique bonding requires - CORRECT ANSWER - -more complex
-technique sensitive
-extra precautions
indirect bonding - CORRECT ANSWER - 1. accurate impression with alignate is taken
and poured up with orthodontic model stone
2. vertical lines are drawn on the teeth to lay brackets
3. brackets are loaded with a filled resin paste and cured
4. individual positioning of tray with silicone is prepared by applying it over the bracket teeth on
plaster model
5. place in warm water to dissolve the separating media
6. silicone tray is then removed from the plaster model with brackets embedded in it
7. brackets are cleaned under running water to make sure that pads have cured resin
8. enamel is etched, conditioned and unfilled resin is applied
9. silicone tray with embedded brackets is then positioned on teeth and bonded
types of appliances - CORRECT ANSWER - equal and opposite forces: elastic band
stretched between two brackets produces equal and opposite forces
one couple appliance: inserted into a bracket at one end and tied as a point contact at the other.
two couple appliances: inserted into a bracket at each end. both a couple and a force are
produced at each end. The magnitude of the couple is largest at the end closer to the bend in the
wire.
,All the sum of the forces are 0.
functional appliances examples - CORRECT ANSWER - Tissue borne: frankel functional
appliance is the only tissue borne functional appliance, which serves to expand the arch by
"padding" against the pressure of the lips and cheeks on the teeth and postures the mandible
forward and downward
toothborne:
-activator: advances the madible to an edge to edge position to induce mandibular growth for the
correction of class 2 malocclusion. Maxillary teeth are prevented from erupting by the acrylic
shelf while mandibular posterior teeth are free to erupt. This improves the deep bite seen in class
2.
-bionator: similar to the activator in function but its design is trimmed down version of the
activator to make it more comfortable to wear
-herbst: fixed or removable. metal rod and tube telescopic apparatus is attached bilaterally to the
maxillary first molars and mandibular first premolars. This helps to posture the mandibule
forward and induce growth.
-twin block appliance: 2 piece acrylic appliance postures the mandible forward with help of
occlusally inclined guiding planes and bite blocks. the vertical seperation of the jaws is also
configued by the height of the bite block. It postures the mandibular forward to induce growth.
functional appliances - CORRECT ANSWER - changes the posture of the mandible,
holding it open or open and forward. strech of the muscles and soft tissues creates pressures
transmitted to the dental and skeletal structures, moving teeth and modifying growth. they are
used to treat class 2 malocclusion
quad helix - CORRECT ANSWER - fixed appliance that consists of 4 helix (2 anterior, 2
posterior), used for posterior cross bite with digital sucking habit
lip bumper - CORRECT ANSWER - -removable
-placed on the molars to move them more distal
-maintain space
-removes the pressure from the mandibular lip (allow for less crowding)
,anchorage used to - CORRECT ANSWER - maintain space
traction is used to - CORRECT ANSWER - create space
headgear is an orthopedic appliance that allows ortho to - CORRECT ANSWER - -control
growth of facial structures
-various designs
-growing patients
greatest advantage of using extraoral anchorage - CORRECT ANSWER - permits
posterior movement of teeth in one arch without adversely disturbing the opposite arch
ideal wire material - CORRECT ANSWER - 1. high strength
2. low stiffness
3. high working range
4. high formability
stainless steel wires - CORRECT ANSWER - -excellent corrosion resistance
-low cost
-18% chromium and 8% nickel
-Highest modulus of elasticity (stiffness) and lowest springback
NiTi - CORRECT ANSWER - highly desirable combinatin of low modulus of elasticity
and wide working range
beta titanium - CORRECT ANSWER - TMA
, highly desirable combination of strength and springness and reasonably good formability
strength = - CORRECT ANSWER - stiffness x range
doubling the length of a wire - CORRECT ANSWER - -decreases the strength by half
-makes 8x less stiff
-4x the range
edgewise appliance - CORRECT ANSWER - -automatic rotational control: control and
correct rotations
-horizontal control: relative thickness of the bracket base for teeth of different thickness
-mesiodistal tip control: angulating the bracket or slot to provide the proper tipping movement
from each tooth.
-torque: having the bracket slot inclined to compensate for the inclination of the facial surface
excessive orthodontic forces - CORRECT ANSWER - 1. cause hyalinization (necrosis) of
the PDL membrane
2. cause undermining resorption
3. crush the periodontal ligament
place bands with - CORRECT ANSWER - glass ionomer or zinc phosphate cements (no
etching)
reciprocal tooth movement - CORRECT ANSWER - two teeth or resistance units of equal
size are moved against each other and move the same amount towards or away from each other
reinforced anchorage - CORRECT ANSWER - accomplished by adding additional teeth to
unit to distribute the force over a larger root surface area in the anchorage unit.
ACTUAL Exam Questions and CORRECT
Answers
Indirect bonding technique bonding requires - CORRECT ANSWER - -more complex
-technique sensitive
-extra precautions
indirect bonding - CORRECT ANSWER - 1. accurate impression with alignate is taken
and poured up with orthodontic model stone
2. vertical lines are drawn on the teeth to lay brackets
3. brackets are loaded with a filled resin paste and cured
4. individual positioning of tray with silicone is prepared by applying it over the bracket teeth on
plaster model
5. place in warm water to dissolve the separating media
6. silicone tray is then removed from the plaster model with brackets embedded in it
7. brackets are cleaned under running water to make sure that pads have cured resin
8. enamel is etched, conditioned and unfilled resin is applied
9. silicone tray with embedded brackets is then positioned on teeth and bonded
types of appliances - CORRECT ANSWER - equal and opposite forces: elastic band
stretched between two brackets produces equal and opposite forces
one couple appliance: inserted into a bracket at one end and tied as a point contact at the other.
two couple appliances: inserted into a bracket at each end. both a couple and a force are
produced at each end. The magnitude of the couple is largest at the end closer to the bend in the
wire.
,All the sum of the forces are 0.
functional appliances examples - CORRECT ANSWER - Tissue borne: frankel functional
appliance is the only tissue borne functional appliance, which serves to expand the arch by
"padding" against the pressure of the lips and cheeks on the teeth and postures the mandible
forward and downward
toothborne:
-activator: advances the madible to an edge to edge position to induce mandibular growth for the
correction of class 2 malocclusion. Maxillary teeth are prevented from erupting by the acrylic
shelf while mandibular posterior teeth are free to erupt. This improves the deep bite seen in class
2.
-bionator: similar to the activator in function but its design is trimmed down version of the
activator to make it more comfortable to wear
-herbst: fixed or removable. metal rod and tube telescopic apparatus is attached bilaterally to the
maxillary first molars and mandibular first premolars. This helps to posture the mandibule
forward and induce growth.
-twin block appliance: 2 piece acrylic appliance postures the mandible forward with help of
occlusally inclined guiding planes and bite blocks. the vertical seperation of the jaws is also
configued by the height of the bite block. It postures the mandibular forward to induce growth.
functional appliances - CORRECT ANSWER - changes the posture of the mandible,
holding it open or open and forward. strech of the muscles and soft tissues creates pressures
transmitted to the dental and skeletal structures, moving teeth and modifying growth. they are
used to treat class 2 malocclusion
quad helix - CORRECT ANSWER - fixed appliance that consists of 4 helix (2 anterior, 2
posterior), used for posterior cross bite with digital sucking habit
lip bumper - CORRECT ANSWER - -removable
-placed on the molars to move them more distal
-maintain space
-removes the pressure from the mandibular lip (allow for less crowding)
,anchorage used to - CORRECT ANSWER - maintain space
traction is used to - CORRECT ANSWER - create space
headgear is an orthopedic appliance that allows ortho to - CORRECT ANSWER - -control
growth of facial structures
-various designs
-growing patients
greatest advantage of using extraoral anchorage - CORRECT ANSWER - permits
posterior movement of teeth in one arch without adversely disturbing the opposite arch
ideal wire material - CORRECT ANSWER - 1. high strength
2. low stiffness
3. high working range
4. high formability
stainless steel wires - CORRECT ANSWER - -excellent corrosion resistance
-low cost
-18% chromium and 8% nickel
-Highest modulus of elasticity (stiffness) and lowest springback
NiTi - CORRECT ANSWER - highly desirable combinatin of low modulus of elasticity
and wide working range
beta titanium - CORRECT ANSWER - TMA
, highly desirable combination of strength and springness and reasonably good formability
strength = - CORRECT ANSWER - stiffness x range
doubling the length of a wire - CORRECT ANSWER - -decreases the strength by half
-makes 8x less stiff
-4x the range
edgewise appliance - CORRECT ANSWER - -automatic rotational control: control and
correct rotations
-horizontal control: relative thickness of the bracket base for teeth of different thickness
-mesiodistal tip control: angulating the bracket or slot to provide the proper tipping movement
from each tooth.
-torque: having the bracket slot inclined to compensate for the inclination of the facial surface
excessive orthodontic forces - CORRECT ANSWER - 1. cause hyalinization (necrosis) of
the PDL membrane
2. cause undermining resorption
3. crush the periodontal ligament
place bands with - CORRECT ANSWER - glass ionomer or zinc phosphate cements (no
etching)
reciprocal tooth movement - CORRECT ANSWER - two teeth or resistance units of equal
size are moved against each other and move the same amount towards or away from each other
reinforced anchorage - CORRECT ANSWER - accomplished by adding additional teeth to
unit to distribute the force over a larger root surface area in the anchorage unit.
