DMD Orthodontics

Question 1

According to Angle's classification, which occlusal relationship is present when the mesiobuccal cusp of the maxillary first molar occludes in the buccal groove of the mandibular first molar?

Accepted Answer

Class I

Answer

Class I is defined by the mesiobuccal cusp of the upper first molar occluding in the buccal groove of the lower first molar, representing the ideal molar relationship.

Question 2

Which cephalometric landmark is defined as the most anteroinferior point on the contour of the mandibular symphysis?

Accepted Answer

Gnathion (Gn)

Answer

Gnathion (Gn) is the most anteroinferior point on the mandibular symphysis, located midway between Pogonion and Menton on the bony chin.

Question 3

Which type of orthodontic force is most effective for producing physiologic tooth movement without causing hyalinization of the periodontal ligament?

Accepted Answer

Light continuous forces within the range of capillary blood pressure

Answer

Light continuous forces (approximately 20–26 g/cm²) maintain capillary blood flow in the PDL, allowing steady osteoblast and osteoclast activity without necrosis or hyalinization.

Question 4

The 'leeway space' (E-space) in the dental arch refers to the difference in mesiodistal width between which tooth groups?

Accepted Answer

Primary canines/molars and permanent canines/premolars

Answer

Leeway space is the difference between the combined mesiodistal widths of the primary canine, first molar, and second molar versus the permanent canine, first premolar, and second premolar — averaging about 1.5 mm per side in the mandible.

Question 5

Which orthodontic wire alloy exhibits the highest springback (range of action) and is most commonly used during the initial alignment phase of fixed appliance therapy?

Accepted Answer

Nickel-titanium (NiTi)

Answer

Nickel-titanium (NiTi) wires have the highest springback due to their superelastic or thermoelastic properties, delivering light, continuous forces ideal for initial leveling and alignment.

DMD - Doctor of Medicine in Dentistry Practice Test

DMD - Doctor of Medicine in Dentistry Practice Test

DMD Orthodontics