Dentistry practice questions

Answer: B) Persistent deciduous canine tooth

A deciduous tooth that is still present at the same site as its erupted permanent successor is a persistent (retained) deciduous tooth. It is usually extracted to prevent malocclusion.

• AIncorrect. A supernumerary tooth is an extra permanent tooth beyond the normal dental formula. In this case the second tooth is the deciduous predecessor that failed to exfoliate.
• BCorrect. When a deciduous tooth is still present after its permanent successor erupts at the same site, it is a persistent (retained) deciduous tooth. It is usually extracted to prevent malocclusion and crowding.
• CIncorrect. A deciduous tooth should exfoliate as its permanent successor erupts. Having both at the same site is abnormal and usually calls for extraction rather than waiting.
• DIncorrect. A dentigerous cyst forms around an unerupted tooth. In this case both teeth have erupted.

Answer: B) It temporarily dyes bacterial biofilm so areas missed during cleaning become visible

A disclosing solution is a temporary dye that stains dental plaque (biofilm) so that missed areas can be seen and cleaned. It does not remove calculus or protect the teeth.

• AIncorrect. Disclosing solutions do not dissolve or soften calculus. Calculus has to be removed mechanically by scaling.
• BCorrect. Disclosing agents are dyes that bind to dental biofilm (plaque) and make it visible against the tooth, showing any areas that still need cleaning.
• CIncorrect. That describes a desensitizing agent or sealant, not a disclosing dye.
• DIncorrect. That describes antiseptics such as chlorhexidine or barrier sealants. Disclosing solutions are stains used to show biofilm.

Answer: A) Their teeth are open-rooted and erupt throughout life, so they need wear from a high-fiber diet

Rabbit teeth are elodont and open-rooted, so they grow continuously. Without enough wear from a high-fiber diet, they overgrow and develop malocclusion.

• ACorrect. Rabbits have elodont (continuously erupting), open-rooted teeth. A low-fiber, high-carbohydrate diet reduces wear, which leads to overgrowth, spikes, and malocclusion.
• BIncorrect. Rabbit teeth are not rooted like dog or cat teeth. They keep erupting throughout life.
• CIncorrect. Hay provides the abrasion that rabbit teeth need. Problems come from too little wear, not too much.
• DIncorrect. Rabbits have two pairs of maxillary incisors (including the small peg teeth), and this is not the cause of malocclusion.

Answer: B) Endo or extraction

• AIncorrect. It needs treatment.
• BCorrect. Exposed pulp becomes infected.
• CIncorrect. It needs treatment.
• DIncorrect. It needs treatment.

Answer: A) Recession is added to probing depth to calculate total attachment loss for staging

Total attachment loss equals gingival recession plus probing depth. Recording recession lets the chart reflect the true attachment loss used to stage periodontal disease.

• ACorrect. Recession is measured from the cementoenamel junction to the gingival margin. Probing depth is measured from the gingival margin to the bottom of the pocket. Their sum is the total attachment loss, which is used to stage periodontitis. If the gums have receded, probing depth alone underestimates the loss.
• BIncorrect. Pseudopockets come from gingival enlargement (hyperplasia), where the gingival margin moves toward the crown. That is the opposite of recession, in which the margin moves toward the root.
• CIncorrect. Mobility is graded separately by how far the tooth moves when gently pushed with an instrument. Recession is a linear measurement of exposed root surface.
• DIncorrect. Furcation involvement is graded by how far a probe passes between the roots of a multirooted tooth. It is recorded as its own finding, separate from recession.

Answer: B) Gingivitis

• AIncorrect. That's trauma.
• BCorrect. It's reversible at this stage.
• CIncorrect. That's later disease.
• DIncorrect. That's advanced disease.

Answer: A) Furcation exposure, where a probe passes through and through between the roots

Furcation involvement on multirooted teeth is staged F1 (probe enters less than halfway), F2 (more than halfway but not through), and F3 (through-and-through exposure). Mobility is graded separately as M0–M3.

• ACorrect. F3 is the most advanced furcation stage. Bone loss lets a periodontal probe pass under the crown from one side of the furcation out the other.
• BIncorrect. Mobility has its own grading scale (M0–M3). It is not recorded with F codes.
• CIncorrect. Tooth fractures use different fracture abbreviations, not the F1–F3 furcation scale.
• DIncorrect. A probe entering less than halfway under the crown is F1, the earliest furcation stage.

Answer: B) 309

• AIncorrect. That's the right maxillary first molar.
• BCorrect. Quadrant 3 is the left mandible; 09 is the first molar.
• CIncorrect. That's the right mandibular first molar.
• DIncorrect. That's the left mandibular canine.

Answer: B) Stomatitis

• AIncorrect. That's bad breath.
• BCorrect. Extractions are often part of treatment.
• CIncorrect. That's misalignment.
• DIncorrect. That's normal development.

Answer: C) With the active side facing the tube

• AIncorrect. Intraoral placement is typical.
• BIncorrect. That gives a poor image.
• CCorrect. Placement affects image quality.
• DIncorrect. That distorts the image.