Free NBDE Dental Anatomy and Occlusion Questions and Answers — Questions and Answers
Question 1: A patient presents with a malocclusion where the mesiobuccal cusp of the maxillary first molar is positioned anterior to the buccal groove of the mandibular first molar. Additionally, their maxillary central incisors are retroclined and there is a deep overbite. According to Angle's classification, which of the following best describes this presentation?
- Class I Malocclusion
- Class II, Division 1 Malocclusion
- Class II, Division 2 Malocclusion (Correct answer)
- Class III Malocclusion
Correct answer: Class II, Division 2 Malocclusion
Angle's Class II malocclusion is defined by the mesiobuccal cusp of the maxillary first molar occluding anterior to the buccal groove of the mandibular first molar. This class is further divided into two divisions. Division 2 is specifically characterized by retroclined (lingually inclined) maxillary central incisors and often presents with a deep overbite, which matches the patient's description. Class II, Division 1 involves proclined maxillary incisors, leading to a large overjet.
Question 2: Which of the following represents the most common eruption sequence for the permanent maxillary teeth?
- First Molar, Central Incisor, Lateral Incisor, First Premolar, Second Premolar, Canine, Second Molar (Correct answer)
- Central Incisor, Lateral Incisor, First Molar, Canine, First Premolar, Second Premolar, Second Molar
- First Molar, Central Incisor, Lateral Incisor, Canine, First Premolar, Second Premolar, Second Molar
- Central Incisor, First Molar, Lateral Incisor, First Premolar, Canine, Second Premolar, Second Molar
Correct answer: First Molar, Central Incisor, Lateral Incisor, First Premolar, Second Premolar, Canine, Second Molar
The typical eruption sequence for permanent maxillary teeth begins with the first molar (around age 6), followed by the central incisor (age 7-8), lateral incisor (age 8-9), first premolar (age 10-11), second premolar (age 10-12), canine (age 11-12), and finally the second molar (age 12-13). While slight variations exist, the eruption of the first molar before the incisors is a key characteristic of the maxillary arch sequence.
Question 3: During a lateral excursive movement to the right, a patient's right canine is the only tooth that contacts its opposing tooth, causing all posterior teeth on both the right (working) and left (non-working) sides to separate. This type of occlusal scheme is known as:
- Bilateral Balanced Occlusion
- Group Function
- Canine Guidance (Canine Protected Articulation) (Correct answer)
- Centric Relation
Correct answer: Canine Guidance (Canine Protected Articulation)
Canine guidance, also known as canine protected articulation, is an occlusal scheme where, during lateral movements of the mandible, the maxillary and mandibular canines on the working side contact and guide the movement, causing the disocclusion (separation) of all posterior teeth. This is considered a protective mechanism for the posterior teeth from potentially damaging lateral forces. Group function would involve multiple posterior teeth on the working side contacting simultaneously.
Question 4: The oblique ridge on a permanent maxillary first molar is a prominent feature formed by the union of which two ridges?
- Mesiobuccal cusp's triangular ridge and the Mesiolingual cusp's triangular ridge
- Distobuccal cusp's triangular ridge and the Mesiolingual cusp's triangular ridge (Correct answer)
- Mesiobuccal cusp's triangular ridge and the Distolingual cusp's triangular ridge
- Distobuccal cusp's triangular ridge and the Distolingual cusp's triangular ridge
Correct answer: Distobuccal cusp's triangular ridge and the Mesiolingual cusp's triangular ridge
The oblique ridge is a unique and defining characteristic of maxillary molars. It traverses the occlusal surface diagonally and is formed by the union of the triangular ridge of the distobuccal cusp and the distal ridge of the mesiolingual cusp. This ridge separates the central fossa from the distal fossa.
Question 5: A dental student is examining a patient's study models and notes an anteroposterior curve of the occlusal plane when viewed from the buccal aspect. This curve, which begins at the tip of the mandibular canine and follows the buccal cusp tips of the premolars and molars, is known as the:
- Curve of Wilson
- Sphere of Monson
- Curve of Spee (Correct answer)
- Compensating Curve
Correct answer: Curve of Spee
The Curve of Spee is the anatomical curvature of the mandibular occlusal plane viewed in the sagittal plane (from the side). It extends from the canine tip posteriorly along the buccal cusp tips of the posterior teeth. The Curve of Wilson is the mediolateral curve viewed in the coronal plane (from the front). The Sphere of Monson is a three-dimensional concept combining both curves.
Question 6: Which of the following anatomical features is frequently present on the mesiolingual cusp of a permanent maxillary first molar and is considered a non-functional, supplemental cusp?
- Oblique Ridge
- Transverse Ridge
- Cusp of Carabelli (Correct answer)
- Central Fossa
Correct answer: Cusp of Carabelli
The Cusp of Carabelli is a supplemental, or fifth, cusp that is often found on the lingual surface of the mesiolingual cusp of the maxillary first molar. Its presence and size can vary among individuals and populations. It is not considered a functional cusp. The oblique ridge is a primary functional feature, not a supplemental cusp.
Free NBDE Dental Anatomy and Occlusion Questions and Answers
A patient presents with a malocclusion where the mesiobuccal cusp of the maxillary first molar is positioned anterior to the buccal groove of the mandibular first molar.
Additionally, their maxillary central incisors are retroclined and there is a deep overbite.
According to Angle's classification, which of the following best describes this presentation?