Orthodontics Flashcards
7 cards from real DMD practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Orthodontics flashcards as text
Which radiographic finding is the most reliable indicator of orthodontically induced external apical root resorption (EARR)?
Answer: Shortened root length with a blunted or pipette-shaped apex
EARR appears on periapical radiographs as a shortening of root length, often with a blunted, truncated, or pipette-shaped apex, confirming loss of root structure.
The Tweed analysis uses a triangle formed by three cephalometric measurements. Which set of angles comprises the Tweed triangle?
Answer: FMA, FMIA, IMPA
The Tweed triangle consists of FMA (Frankfort-mandibular plane angle), FMIA (Frankfort-mandibular incisor angle), and IMPA (incisor-mandibular plane angle), which together always sum to 180°.
Dental transposition is defined as which of the following tooth anomalies?
Answer: Positional interchange of two adjacent teeth occupying each other's normal position
Dental transposition is the positional interchange of two adjacent teeth, most commonly involving the maxillary canine and first premolar, so each tooth erupts in the other's normal position.
Anterior open bite malocclusion that develops during the mixed dentition is most commonly associated with which parafunctional habit?
Answer: Digit sucking (thumb/finger) or tongue thrusting
Digit sucking and tongue thrusting exert persistent forces on the dentition that tip the upper incisors labially, depress lower incisors, and prevent anterior vertical overlap, resulting in an open bite.
Which type of retainer provides the most stable long-term retention for lower anterior teeth after orthodontic alignment, reducing the risk of relapse?
Answer: Bonded fixed lingual retainer
A bonded fixed lingual retainer cemented to the lower canines or all six anterior teeth provides continuous, compliance-independent retention, which is most effective for preventing lower incisor relapse long-term.
In orthodontics, 'torque' most accurately refers to which type of tooth movement?
Answer: Root movement labially or lingually while controlling crown position
Torque is the labiolingual movement of the root apex while the crown is relatively controlled; it is produced by rectangular archwires engaging the bracket slot and creating a force couple.
For a skeletally mature adult patient with significant Class III malocclusion (mandibular prognathism), the most appropriate definitive surgical correction is:
Answer: Bilateral sagittal split osteotomy (BSSO) for mandibular setback
BSSO mandibular setback is the most commonly performed single-jaw surgery for Class III malocclusion due to mandibular prognathism, repositioning the mandible posteriorly to achieve proper occlusion.