Pathology · patient case with 2 questions
Child with widespread absence of permanent tooth buds
Patient: Male, 8 years old
Chief Complaint: Mother: “His teeth are coming out and nothing is growing back.”
Background: Healthy, normal growth and development. No syndromic features reported. Family history not known.
Vital Signs: BP 98/62 mmHg · HR 88 bpm · T 98.4°F
Findings: Panoramic radiograph shows no developing tooth buds in the mandible apart from #17. Teeth #19 and #30 are absent. In the maxilla, several primary teeth have exfoliated and no successor buds are present except for #3 and #4, both of which have erupted. Multiple primary teeth remain with normal crown form.
Question 1
What term describes this pattern of missing teeth?
Show answer and explanation
Correct answer: C. Hypodontia (oligodontia when six or more teeth are absent)
- A. Ankylosis is fusion of cementum to alveolar bone, producing an infra-occluded tooth that fails to exfoliate. It does not explain absent successors.
- B. PSEUDOANODONTIA describes teeth that are PRESENT but unerupted or impacted, so the mouth appears edentulous while the radiograph shows buds. Here the buds are genuinely absent, which is the opposite finding.
- C. CORRECT. HYPODONTIA is the congenital absence of one or more teeth, defined by the absence of the TOOTH BUD on radiographic examination. When SIX OR MORE teeth are missing excluding third molars, the term OLIGODONTIA is applied — this patient sits in that category. Extensive oligodontia should prompt evaluation for ectodermal dysplasia and for the WNT10A, PAX9, MSX1 and EDA gene pathways, and should be distinguished from acquired loss.
- D. ANODONTIA is the COMPLETE absence of teeth, meaning no tooth germs at all in either dentition. It is extremely rare and is not what this radiograph shows — several teeth are present and erupted.
Note: What this item adds is the TERMINOLOGY tier — anodontia versus hypodontia versus oligodontia versus pseudoanodontia — and the radiographic criterion, which is absence of the BUD rather than absence of the erupted tooth. Commonest congenitally missing teeth after third molars: mandibular second premolars, maxillary lateral incisors, maxillary second premolars.
Question 2
With #3 and #4 erupted and multiple primary teeth lost bilaterally in the MAXILLA, which appliance is most appropriate for space maintenance?
Show answer and explanation
Correct answer: C. Nance holding arch
- A. A band and loop maintains the space of a SINGLE tooth in ONE quadrant. It cannot hold bilateral spaces, and multiple band-and-loop appliances in one arch are unstable and prone to distortion.
- B. A lingual arch is the MANDIBULAR equivalent for bilateral maintenance. It cannot be used in the maxilla, where the tongue would displace it and where the palate provides the anchorage instead.
- C. CORRECT. A NANCE HOLDING ARCH is the maxillary appliance for BILATERAL space maintenance. Bands on the permanent first molars are joined by a palatal wire carrying an acrylic button that rests against the anterior palatal rugae, resisting mesial molar movement. It preserves arch length while the anterior segment is unrestrained, which is exactly what this arch needs.
- D. A distal shoe is used when the second primary molar is lost BEFORE the first permanent molar erupts, guiding it into position with a subgingival extension. In this patient #3 has already erupted, so the indication has passed.
Note: Match the appliance to the arch and to the number of spaces. Unilateral single space: band and loop. Bilateral MANDIBULAR: lingual arch — and only once the permanent incisors have erupted, or it interferes with their eruption path. Bilateral MAXILLARY: Nance holding arch, or a transpalatal arch where some rotational control is also wanted. Second primary molar lost before the first permanent molar erupts: distal shoe.