Four developmental anomalies

Correct answer: C. An enamel pearl or cervical enamel projection

• A. Condensing osteitis is a sclerotic BONE reaction to low-grade pulpal inflammation. It is not a root-surface anomaly and does not produce a furcation pocket.
• B. Hypercementosis is excessive cementum deposition making the root bulbous, and the periodontal ligament space FOLLOWS the enlarged outline at normal width. It has no periodontal significance and does not cause localised pocketing.
• C. CORRECT. ENAMEL PEARLS are ectopic globules of enamel on the root surface, most often at the furcation of MAXILLARY molars, especially third molars. CERVICAL ENAMEL PROJECTIONS are tongues of enamel extending apically from the cementoenamel junction toward the furcation, most often on MANDIBULAR molars, graded I to III by how far they reach. Both matter for the same reason: PERIODONTAL LIGAMENT AND CONNECTIVE TISSUE CANNOT ATTACH TO ENAMEL — only a weak hemidesmosomal epithelial attachment forms — so these become sites of least resistance where an ISOLATED deep pocket and localised furcation involvement develop in an otherwise healthy periodontium. Localised disease grossly out of proportion to the rest of the mouth is the clinical signature. Management is odontoplasty to remove the projection where it is accessible.
• D. A pulp stone lies WITHIN the pulp chamber and has no relationship to the periodontal attachment at all.

Note: Keep the short list of LOCAL anatomical factors that produce isolated periodontal breakdown: enamel pearls and cervical enamel projections, palatogingival (palatal radicular) grooves on maxillary lateral incisors, root proximity and furcation entrance width, developmental root grooves, and overhanging restorations. When one site is far worse than the rest of the mouth, look for anatomy rather than blaming the patient's hygiene.

Correct answer: C. Regional odontodysplasia

• A. Amelogenesis imperfecta is GENERALISED, affecting all teeth in both dentitions. The ENAMEL is defective while the dentine is normal, so the contrast between the two on a radiograph is preserved or even exaggerated — the opposite of the poor contrast described here.
• B. Dentin dysplasia type I produces teeth with absent or extremely short roots and crescent-shaped pulpal remnants, with clinically normal crowns, and it too is generalised rather than confined to one quadrant.
• C. CORRECT. REGIONAL ODONTODYSPLASIA — the ‘GHOST TEETH’. The defining feature is that it is LOCALISED to a segment or quadrant, affecting several ADJACENT teeth with a characteristically abrupt cut-off at the midline, and involving both dentitions in the affected region. Enamel and dentine are both markedly thin and hypomineralised, so the teeth show poor radiographic contrast and appear faint or ghostly, with disproportionately large pulp chambers. Eruption is delayed or fails altogether, and affected teeth are prone to abscess formation even in the absence of caries. The cause is unknown and it is NOT inherited.
• D. Dentinogenesis imperfecta is also generalised, producing opalescent brown-blue teeth with bulbous crowns, cervical constriction and OBLITERATED pulp chambers. This patient has enlarged pulps, which is the reverse finding.

Note: The localisation IS the diagnosis. Anything GENERALISED and affecting both dentitions is a hereditary condition — amelogenesis imperfecta, dentinogenesis imperfecta, dentin dysplasia. Anything confined to one segment with a midline cut-off is regional odontodysplasia. Management is usually extraction of the affected teeth with prosthetic replacement, since they are neither restorable nor able to erupt reliably.

Correct answer: B. Transposition — usually accept the position and align the teeth as they lie, reshaping to mimic normal morphology

• A. TRANSMIGRATION is a genuinely different phenomenon and worth knowing separately: an unerupted tooth, almost always the MANDIBULAR CANINE, migrates across the MIDLINE within bone.
• B. CORRECT. TRANSPOSITION is the positional interchange of two ADJACENT teeth, or the development of a tooth in the position normally occupied by a non-adjacent tooth. The maxillary CANINE and FIRST PREMOLAR is by far the commonest pair, followed by the maxillary canine and lateral incisor, and it occurs more often in the maxilla. It is associated with other anomalies — hypodontia, peg-shaped lateral incisors and retained primary teeth — so finding one should prompt a look for the others. Management is usually to ACCEPT the transposition and align the teeth in their transposed positions, reshaping them to mimic the correct morphology, because attempting to move two fully formed roots past each other risks root resorption and bone loss.
• C. Migration is drifting from the normal position, typically following tooth loss or periodontal breakdown. It does not involve two teeth exchanging places. And correcting a complete transposition orthodontically is precisely what is usually NOT attempted.
• D. Ectopic eruption describes a tooth erupting along an abnormal path — most commonly a maxillary first molar resorbing the distal of the second primary molar. Extracting a sound premolar is not a first-line answer to anything here.

Note: Correction is only considered where the transposition is INCOMPLETE and identified early, while the roots are still developing and can be guided. In a complete transposition with formed roots, accepting and camouflaging is the standard approach — reshape the canine cusp tip and recontour the premolar, or restore both with composite or veneers.

Correct answer: A. Radix entomolaris — an additional distolingual root on the mandibular first molar, easily missed at access

• A. CORRECT. RADIX ENTOMOLARIS is an additional DISTOLINGUAL root on the mandibular first molar. Its prevalence varies markedly with ancestry — under 5% in white European populations but reaching 30% or more in people of East Asian and Native American descent, which is why the stem specifies it. It matters because the extra canal is easily MISSED during endodontic access, and because the root lies LINGUALLY it is superimposed on the others on a standard periapical, producing exactly the finding described: an unusually wide root outline whose periodontal ligament outlines do not resolve. Suspect it, then take a second film at an altered horizontal angle using the SLOB rule, or a CBCT. The mirror-image variant with an extra BUCCAL root is radix paramolaris.
• B. Maxillary central incisors are essentially always single-rooted. This is not a recognised variation.
• C. The maxillary third molar has highly variable and often fused root anatomy, but it is not the clinically significant variation being tested here.
• D. This is precisely the trap. An extra root superimposed lingually is what a single periapical FAILS to demonstrate — the reason the variation is missed so often is that the standard film does not show it.

Note: Other root-number variations worth carrying: mandibular CANINES have two roots in roughly 5% of cases; maxillary FIRST PREMOLARS have two roots in 60–70%; and the MB2 canal of the maxillary first molar is present in the majority of teeth and is the single most commonly missed canal in endodontics.