Pediatric Dentistry · patient case with 3 questions
Seven-Year-Old with Down Syndrome
Patient: 7-year-old male
Chief Complaint: Mother: “He seems to be missing a lot of teeth.”
Background: Trisomy 21. Atrioventricular septal defect repaired at 8 months of age with no residual defect and no prosthetic material. Generalized hypotonia. Cleared by cardiology; no antibiotic prophylaxis required.
Medications: None
Vital Signs: BP 96/60 mmHg · HR 92 bpm · RR 20 · T 98.2°F
Findings: Class III tendency with midface hypoplasia, macroglossia relative to arch size, fissured tongue. Panoramic radiograph shows numerous absent permanent tooth germs and an abrupt angulation of the root of a developing premolar. Cooperative and pleasant at the initial visit.
Question 1
The panoramic radiograph shows six permanent teeth congenitally absent, excluding third molars. Which term best describes this finding?
Show answer and explanation
Correct answer: D. Oligodontia
- A. Incorrect. Anodontia is the complete absence of all teeth in a dentition. It is exceedingly rare and is not what is described here, since numerous teeth are present.
- B. Incorrect. Hypodontia is the correct family of terms but refers to fewer than six missing teeth. With six absent, oligodontia is the precise designation.
- C. Incorrect. Taurodontism — an elongated pulp chamber with apically displaced furcation — is also strongly associated with Down syndrome, and may well be visible on this same film. But it describes tooth morphology, not tooth absence, so it does not answer the question asked.
- D. Correct. Oligodontia is the accepted term for six or more congenitally absent teeth excluding third molars. It is markedly more common in trisomy 21 than in the general population.
Note: Down syndrome dental profile: delayed and irregular eruption, oligodontia, microdontia, taurodontism, fissured tongue, Class III tendency, and early aggressive periodontitis.
Question 2
The same radiograph shows the root of a developing mandibular premolar bent at a sharp angle to its crown. What is this called?
Show answer and explanation
Correct answer: A. Dilaceration
- A. Correct. Dilaceration is an abrupt angular deviation between the crown and root, or within the root itself. It arises when the developing tooth germ is displaced — often after trauma to a predecessor — after part of the tooth has already mineralized.
- B. Incorrect. Dens invaginatus (dens in dente) is an infolding of enamel and dentin into the pulp space, seen radiographically as a tooth-within-a-tooth, most often in maxillary lateral incisors.
- C. Incorrect. Fusion is the union of two developing tooth germs involving dentin, producing a single large tooth and one fewer tooth in the arch. There is no crown union here.
- D. Incorrect. Concrescence is the union of two adjacent teeth by cementum only, after root formation is complete. The crowns remain separate and the roots are joined, which is not what is described.
Question 3
He is cooperative at the first visit but becomes progressively resistant during subsequent appointments, and basic behavior guidance no longer allows any treatment to be completed. Comprehensive restorative care is still required. What is the most appropriate approach?
Show answer and explanation
Correct answer: A. General anesthesia in a hospital or surgical center setting
- A. Correct. When less restrictive techniques have been genuinely attempted and failed, and the patient has substantial treatment needs, general anesthesia allows all care to be completed safely in one session. It is the standard route for a patient with an intellectual disability whose cooperation cannot be obtained.
- B. Incorrect. Behavior guidance techniques have already been tried without success. Continuing them indefinitely delays necessary care and risks disease progression.
- C. Incorrect. Protective stabilization always requires informed consent from the parent or guardian, and it is not a substitute for definitive management when extensive treatment is needed.
- D. Incorrect. Nitrous oxide is a minimal sedation technique that still requires the patient to accept the nasal hood and follow instruction. In a child who has become actively resistant, it will not provide adequate conditions.
Note: Moderate sedation is a legitimate intermediate step and some keys favor it. General anesthesia is the stronger answer here because the stem specifies comprehensive treatment needs and failure of behavior guidance. Down syndrome adds specific GA considerations: screen for atlantoaxial instability, cardiac status, and a potentially difficult airway from midface hypoplasia and macroglossia.