1|Page
ORTHODONTICS NBDE PART 2 EXAMS
WITH ACTUAL CORRECT QUESTIONS
AND VERIFIED DETAILED RATIONALES
ANSWERS LATEST 2024 (NEWEST)
ALREADY GRADED A+
A 7-year-old boy was previously diagnosed with marked "bowing of the femurs" and decreased
radiographic bone opacity. What disease does this patient have? What would you notice upon the
examination of this patient's oral cavity and intraoral radiographs?
I. Hyperthyroidism
II. Rickets
III. Scurvy
IV. Missing or delayed tooth eruption
V. Premature exfoliation of primary teeth
VI. Normal eruption pattern
A. III and VI
B. III and V
C. I and VI
D. I and V
E. II and IV
F. II and V
The correct answer is E. The data presented in the question are indicative of rickets disease secondary
to vitaminDdeficiency, which presents with missing or delayed eruption. Scurvy results from dietary
deficiency of water-soluble vitamin C. There may be gingival involvement, which includes swelling,
friability, bleeding, secondary infection, and loosening of teeth.Hyperthyroidism is the result of
increased secretion of thyroxine (T4) by the thyroid gland and usually presents with premature
exfoliation of primary teeth
All these conditions are associated with supernumerary teeth except:
A. Gardner syndrome
B. Down syndrome
C. Ectodermal dysplasia
D. Cleidocranial dysplasia
E. Sturge-Weber syndrome
The correct answer is C. Ectodermal dysplasia is usually associated with oligodontia (congenitally
missing one or more teeth) and other missing ectodermal derivatives such as hair and nails.Although
supernumerary or extra teeth can incidentally be found in healthy children;they are much more
common in children with Gardner syndrome, Down syndrome, cleidocranial dysplasia, and Sturge-
Weber syndrome.The most common site for these is between central incisors (mesiodens)
,2|Page
A 10-year-old boy presents with severe crowding.The patient has a bilateral class I malocclusion and
discrepancy in all four quadrants of 5 mm. As a part of the comprehensive orthodontic treatment, this
patient needs several teeth extracted. Permanent incisors and the first permanent molars are the only
permanent teeth
erupted. Which teeth need to be extracted to correct the malocclusion?
A. Permanent lateral incisor → primary canine→primary first molars
B. Primary first molars→permanent first premolars→permanent second premolars
C. Primary canines→primary first molars→primary second molars
D. Primary first molars → primary second molars→permanent first premolars
E. Primary canines→primary first molars→permanent first premolars
The correct answer is E. Serial extraction is the orderly removal of selected primary and permanent
teeth in a predetermined sequence, which is as follows: primary canines → primary first
molars→permanent first premolars.
Interarch elastics are sometimes used as an aid tool in treatment of malocclusions. What malocclusion is
being treated with the help of the interarch elastic mentioned below?
A. Anterior open bite
B. Class I
C. Class II
D. Unilateral crossbite
The correct answer is D. Interarch forces have side effects, such as widening or constriction of the
dental arches and alteration of the occlusion;therefore, it is best used in treatment of unilateral
crossbite
What is the most efficient way to move teeth, reinforce anchorage, and avoid friction in the appliance
system?
A. Apply gentle constant force.
B. Incorporate springs into archwire.
C. Incorporate interarch elastic.
D. Bond magnets to individual teeth.
E. All of the above
The correct answer is E. All of the above statements are correct. Gentle constant force
must be applied for the survival of cells in the periodontal ligament (PDL). Incorporation of springs
into the archwire eliminates the difficulty in anchorage control caused by frictional resistance.
Reinforcement of anchorage can be produced by using interarch elastic. Magnets in attraction or
repulsion could generate forces of the magnitude needed to move teeth and would have the
advantage of providing predictable force levels without direct contact or friction.
,3|Page
There are multiple forces being applied to teeth #8 and #9 by the step bend between two teeth. What
type of force is being applied to each tooth?
A. Teeth #8 and #9 are being intruded.
B. Teeth #8 and #9 are being extruded.
C. Tooth #8 is being intruded and #9 is being extruded.
D. Tooth #8 is being extruded and #9 is being intruded.
E. Teeth #8 and #9 are being rotated.
The correct answer is C. A step bend between two teeth produces intrusive force on tooth #8 and
extrusive force on tooth #9.
A 5-year-old girl has her molar occlusion in flush terminal plane. What is most likely to be
her occlusion at age 10 with proper adequate space management?
A. Class I
B. Class II division 1
C. Class II division 2
D. Class III
The correct answer is A. Flush terminal plane is the normal primary molar teeth relationship.This
causes edge-to-edge position of cusps of permanent maxillary and mandibular first molars.When
mandibular molars drift forward,the flush terminal plane becomes class I occlusion.The primary
molars have to be in distal step relationship to classify for class II occlusion.Deviation I and II are
determined by the anterior maxillary to mandibular teeth only.The primary molars have to be in
mesial step relationship to be classified as class III occlusion
Physiologic age of the patient can be determined by examining the ossification pattern of:
A. Carpal bones of the wrist
B. Metacarpals of the hands
C. Phalanges of the fingers
D. All of the above
The correct answer is D. All of the above statements are correct. Hand-wrist radiographs
are used by some investigators to judge the skeletal age and development of the patient
because physical maturity and skeletal development correlate well with jaw growth
, 4|Page
What type of tooth movement does the diagram below represent?
A. Rotation
B. Translation
C. Tipping
D. Intrusion
E. Extrusion
The correct answer is B. White circles indicate the center of resistance at the starting tooth position.
Shaded circles show the center of resistance moved in the direction of the force. A force through the
center of resistance causes all points of the tooth to move the same amount in the same direction.
This type of movement is called translation or bodily movement. Rotation is the movement of a tooth
around its
longitudinal axis. Tipping is the movement of a tooth in any direction while its apex remains in almost
the original position. Intrusion is the movement of the tooth in an inward direction. Extrusion is the
movement of teeth beyond the natural occlusal plane that may be accompanied by a similar
movement of investing tissues
What is the condition that may complicate molar uprighting?
A. Open bite
B. Presence of periodontal disease
C. Extruded maxillary and mandibular molars
D. Molar having short roots
E. All of the above
The correct answer is E. All of the above statements are correct. Slow progress in molar uprighting in
an adult patient is most likely due to occlusal interferences, such as extruded maxillary and
mandibular molar with an open bite already present. Presence of periodontal disease or short clinical
crown is not favorable for orthodontic treatment
Which of the following malocclusions is the easiest to maintain after orthodontic treatment?
A. Expansion
B. Rotation
C. Anterior crossbite
ORTHODONTICS NBDE PART 2 EXAMS
WITH ACTUAL CORRECT QUESTIONS
AND VERIFIED DETAILED RATIONALES
ANSWERS LATEST 2024 (NEWEST)
ALREADY GRADED A+
A 7-year-old boy was previously diagnosed with marked "bowing of the femurs" and decreased
radiographic bone opacity. What disease does this patient have? What would you notice upon the
examination of this patient's oral cavity and intraoral radiographs?
I. Hyperthyroidism
II. Rickets
III. Scurvy
IV. Missing or delayed tooth eruption
V. Premature exfoliation of primary teeth
VI. Normal eruption pattern
A. III and VI
B. III and V
C. I and VI
D. I and V
E. II and IV
F. II and V
The correct answer is E. The data presented in the question are indicative of rickets disease secondary
to vitaminDdeficiency, which presents with missing or delayed eruption. Scurvy results from dietary
deficiency of water-soluble vitamin C. There may be gingival involvement, which includes swelling,
friability, bleeding, secondary infection, and loosening of teeth.Hyperthyroidism is the result of
increased secretion of thyroxine (T4) by the thyroid gland and usually presents with premature
exfoliation of primary teeth
All these conditions are associated with supernumerary teeth except:
A. Gardner syndrome
B. Down syndrome
C. Ectodermal dysplasia
D. Cleidocranial dysplasia
E. Sturge-Weber syndrome
The correct answer is C. Ectodermal dysplasia is usually associated with oligodontia (congenitally
missing one or more teeth) and other missing ectodermal derivatives such as hair and nails.Although
supernumerary or extra teeth can incidentally be found in healthy children;they are much more
common in children with Gardner syndrome, Down syndrome, cleidocranial dysplasia, and Sturge-
Weber syndrome.The most common site for these is between central incisors (mesiodens)
,2|Page
A 10-year-old boy presents with severe crowding.The patient has a bilateral class I malocclusion and
discrepancy in all four quadrants of 5 mm. As a part of the comprehensive orthodontic treatment, this
patient needs several teeth extracted. Permanent incisors and the first permanent molars are the only
permanent teeth
erupted. Which teeth need to be extracted to correct the malocclusion?
A. Permanent lateral incisor → primary canine→primary first molars
B. Primary first molars→permanent first premolars→permanent second premolars
C. Primary canines→primary first molars→primary second molars
D. Primary first molars → primary second molars→permanent first premolars
E. Primary canines→primary first molars→permanent first premolars
The correct answer is E. Serial extraction is the orderly removal of selected primary and permanent
teeth in a predetermined sequence, which is as follows: primary canines → primary first
molars→permanent first premolars.
Interarch elastics are sometimes used as an aid tool in treatment of malocclusions. What malocclusion is
being treated with the help of the interarch elastic mentioned below?
A. Anterior open bite
B. Class I
C. Class II
D. Unilateral crossbite
The correct answer is D. Interarch forces have side effects, such as widening or constriction of the
dental arches and alteration of the occlusion;therefore, it is best used in treatment of unilateral
crossbite
What is the most efficient way to move teeth, reinforce anchorage, and avoid friction in the appliance
system?
A. Apply gentle constant force.
B. Incorporate springs into archwire.
C. Incorporate interarch elastic.
D. Bond magnets to individual teeth.
E. All of the above
The correct answer is E. All of the above statements are correct. Gentle constant force
must be applied for the survival of cells in the periodontal ligament (PDL). Incorporation of springs
into the archwire eliminates the difficulty in anchorage control caused by frictional resistance.
Reinforcement of anchorage can be produced by using interarch elastic. Magnets in attraction or
repulsion could generate forces of the magnitude needed to move teeth and would have the
advantage of providing predictable force levels without direct contact or friction.
,3|Page
There are multiple forces being applied to teeth #8 and #9 by the step bend between two teeth. What
type of force is being applied to each tooth?
A. Teeth #8 and #9 are being intruded.
B. Teeth #8 and #9 are being extruded.
C. Tooth #8 is being intruded and #9 is being extruded.
D. Tooth #8 is being extruded and #9 is being intruded.
E. Teeth #8 and #9 are being rotated.
The correct answer is C. A step bend between two teeth produces intrusive force on tooth #8 and
extrusive force on tooth #9.
A 5-year-old girl has her molar occlusion in flush terminal plane. What is most likely to be
her occlusion at age 10 with proper adequate space management?
A. Class I
B. Class II division 1
C. Class II division 2
D. Class III
The correct answer is A. Flush terminal plane is the normal primary molar teeth relationship.This
causes edge-to-edge position of cusps of permanent maxillary and mandibular first molars.When
mandibular molars drift forward,the flush terminal plane becomes class I occlusion.The primary
molars have to be in distal step relationship to classify for class II occlusion.Deviation I and II are
determined by the anterior maxillary to mandibular teeth only.The primary molars have to be in
mesial step relationship to be classified as class III occlusion
Physiologic age of the patient can be determined by examining the ossification pattern of:
A. Carpal bones of the wrist
B. Metacarpals of the hands
C. Phalanges of the fingers
D. All of the above
The correct answer is D. All of the above statements are correct. Hand-wrist radiographs
are used by some investigators to judge the skeletal age and development of the patient
because physical maturity and skeletal development correlate well with jaw growth
, 4|Page
What type of tooth movement does the diagram below represent?
A. Rotation
B. Translation
C. Tipping
D. Intrusion
E. Extrusion
The correct answer is B. White circles indicate the center of resistance at the starting tooth position.
Shaded circles show the center of resistance moved in the direction of the force. A force through the
center of resistance causes all points of the tooth to move the same amount in the same direction.
This type of movement is called translation or bodily movement. Rotation is the movement of a tooth
around its
longitudinal axis. Tipping is the movement of a tooth in any direction while its apex remains in almost
the original position. Intrusion is the movement of the tooth in an inward direction. Extrusion is the
movement of teeth beyond the natural occlusal plane that may be accompanied by a similar
movement of investing tissues
What is the condition that may complicate molar uprighting?
A. Open bite
B. Presence of periodontal disease
C. Extruded maxillary and mandibular molars
D. Molar having short roots
E. All of the above
The correct answer is E. All of the above statements are correct. Slow progress in molar uprighting in
an adult patient is most likely due to occlusal interferences, such as extruded maxillary and
mandibular molar with an open bite already present. Presence of periodontal disease or short clinical
crown is not favorable for orthodontic treatment
Which of the following malocclusions is the easiest to maintain after orthodontic treatment?
A. Expansion
B. Rotation
C. Anterior crossbite
