Developmental Disturbance – Smart Notes
1. CORE DEFINITIONS
Craniofacial & Skeletal Syndromes
• Pierre Robin Syndrome: A syndrome consisting of the triad: Cleft palate, micrognathia, and glossoptosis [MAN-2K]. It is associated with Micrognathia and Cleft of the lip and palate [AIPG-05].
• Treacher Collins Syndrome: Features include poorly developed or absence of malar bones [PGI DEC-2013] and coloboma of the lower lid [AIIMS MAY-13].
• Crouzon Syndrome: Craniofacial dysostosis where the Coronal suture is closed first [AIPG-2019].
• Goldenhar Syndrome: Defined by Facial deformity, auricular abnormalities and vertebral deformity [PGI JUNE-2011].
• Osteogenesis Imperfecta: A disorder characterized by defective bone formation [AIIMS-89] caused by Improper synthesis of procollagen [KAR-2013].
• Cleidocranial Dysplasia: Involves CBFA1 (RUNX2) gene [AIPG-2019]. Features Supernumerary teeth [AIIMS-89] and delayed eruption [AIIMS-93, KAR -2K]. Hypodontia is found in all, except Cleidocranial dysostosis [ΝΕΕΤ-2013].
• Gardner Syndrome: Features Multiple osteomas, multiple polyposis, supernumerary teeth [AP-01, 03, 99]. Does not include Osteosarcoma [MAN-2002]. Involves all the 3 germ layers [AIPG-2022].
• Peutz-Jeghers Syndrome: Characterised by Multiple intestinal polyps [KCET-09] and mucocutaneous pigmentation.
• Ectodermal Dysplasia: Gene affected is EDA / EDAR [AIIMS NOV-2021].
• Dyskeratosis Congenita: Skin disease associated with a triad of abnormal nails, leukoplakia and reticular pigmentation of skin [AIIMS MAY 2021].
Oral Mucosal & Soft Tissue Conditions
• Fordyce’s Granules: Fat tissue (ectopic sebaceous glands) embedded in buccal mucosa [PGI JUNE-2017].
• Focal Epithelial Hyperplasia: Also known as Heck’s disease [AIPG-06, 10].
• Laugier-Hunziker Syndrome: Associated with Idiopathic macular oral hyperpigmentation [AIIMS-96].
• Melkersson-Rosenthal Syndrome: Characterized by facial edema, cheilitis granulomatosa and a fissured tongue [ΜΑΝ-97, AP-2013].
• Gingival Lesions:
◦ Epulis: A swelling of a single papilla of the gingiva [KERALA -2016].
◦ Parulis: An inflammatory enlargement seen in End of sinus tract [AP-06].
Tongue Anomalies
• Bifid Tongue: A congenital anomaly that occurs due to non-fusion of The two lateral lingual swellings [AIIMS-2K].
• Macroglossia: Smooth, diffuse enlargement of tongue is seen in Lymphangioma [PGI JUNE-2017].
• Ankyloglossia: Occurs as a result of Union between tongue and floor of mouth/ventral surface of tongue [MAN-2K].
• Median Rhomboid Glossitis: A well demarcated area of depapillation [ΜΑΝ-2001] associated with Fungal infection [AIIMS-99], [AIIMS -96, 97].
• Geographic Tongue: Filiform papillae are absent [MAN-97]. Red colour is due to Atrophy and inflammation [PGI-2011]. It is NOT a Precancerous condition [AIPG-2002].
• Hairy Tongue: Characterized by hypertrophy of filiform papillae [KAR-2002]. Results from Prolonged administration of broad spectrum antibiotics [KAR-2K].
• Lingual Tonsils: Arise As a result of hyperplasia [AIPG-94, 97].
• Lingual Thyroid: Failure of descent seen Near the base of tongue close to foramen caecum [AIIMS DEC-2020].
Tooth Anomalies
• Microdontia: True generalized microdontia is characterized by smaller teeth than the normal [PGI-2K]. Most commonly affects Maxillary lateral incisor [AIIMS-90, 2K].
• Dilaceration: Refers to a sharp bend or curve in the root [ΜΑΝ-94]. Radiographically, root may appear rounded & blunted at apex [AIPG 2020].
• Talon Cusp: Characteristic of Rubinstein-Taybi syndrome [COMEDK-04]. Presents as extra cusp on maxillary central incisor [AIIMS-09]. Radiographically identifiable [AIPG-2022].
• Dens Invaginatus: A deep pit lined by enamel [AIPG-92, AIIMS-90] caused by a deep invagination of the enamel organ [AIIMS-92]. Most commonly seen in Maxillary lateral incisors [AIPG-06], [AIPG-14].
• Taurodontism: Characterized by Elongated wide pulp canals and short roots [AIPG-95]. Usually seen in Klinefelter’s syndrome [MAN-95].
• Enameloma: Tumor resembling enamel present on gingiva [AIIMS MAY-14].
• Natal/Neonatal Teeth: Teeth that erupt within 30 days of birth [AIPG-2002].
• Ankylosis: Submerged teeth are Ankylosed teeth [COMEDK-07]. Most commonly submerged tooth is Mandibular primary 2nd molar [AP-99].
——————————————————————————–
2. CORE MECHANISMS
Developmental Fusion & Union
• Gemination: Occurs due to Division of a single tooth bud [ΜΑΝ-2001].
• Fusion: Dentinal union of two embryologically developing teeth [COMEDK-05]. A child with one tooth less than normal and a large tooth with two crowns/roots has Fusion [AIIMS-2011]. More common in Primary dentition [KERALA-2015].
• Concrescence: A union of the roots of adjacent teeth through the cementum [AIPG-05, PGI-02].
Structural Defects (Enamel & Dentin)
• Amelogenesis Imperfecta: A disorder of Ectoderm [NEET-2013]. Feature not typically found is Condylar hypoplasia [PGI JUNE-2017].
• Dentinogenesis Imperfecta: Absence of pulp chambers [PGI-2K]. It is a hereditary disturbance characterized by calcification of pulp chambers [AIPG-2002]. Inheritance is Autosomal dominant [AIPG-95]. Related to DSPP gene [PGI JUNE-2017]. Mutation in DSPP gene is associated with Dentinogenesis imperfecta [AIPG-2019].
• Dentin Dysplasia: Histological appearance of “lava flowing around boulders” [AP-08].
• Regional Odontodysplasia: “Ghost teeth” [ΜΑΝ-2002]. Characterized by abnormally large pulp chambers [APPSC-99]. Histology shows marked reduction in amount of dentin, widening of predentin layer, and large area of interglobular dentin [AIIMS MAY 2012]. The gene that defines the localization of the tooth germs is Pax-9 [APPG-15].
Environmental & Local Factors
• Fluorosis: Developing Ameloblasts affected by high fluoride result in Mottled enamel [ΜΑΝ-98].
• Turner’s Hypoplasia: A permanent tooth with a local hypoplastic deformity [ΜΑΝ-2001]. Seen due to local infection or local trauma [KAR-98]. Most commonly affects Permanent mandibular premolars [AIPG-2003]. Can present as yellowish discoloured spot on incisor following injury to deciduous tooth [AIIMS MAY 2012] or hypoplasia of premolar following alveolar abscess of primary molar [AIIMS NOV-2021].
• Congenital Syphilis: Peg-shaped incisors tapering towards incisal edge [MAN-94, AIIMS-93] and Hutchinson’s incisors [AIIMS-01, KAR-01].
• Fetal Alcohol Syndrome: Lady consumed ethyl alcohol during pregnancy; young one shows Microcephaly / Midface deficiency [AIPG 2020].
——————————————————————————–
3. CLASSIFICATION SYSTEMS
| System | Topic | Key Classes/Groups | Verified Tags |
|---|---|---|---|
| Veau’s | Cleft Lip/Palate | Group II: Isolated Cleft Palate | [PGI-2011] |
| Witkop’s | Amelogenesis Imperfecta | Hypo-calcification and hypo-maturation | [KAR-06] |
| DI Types | Dentinogenesis Imperfecta | Shell teeth are more common in Type III.<br>Complete obliteration of pulp is seen in all EXCEPT Type III. | [AIPG-2003] |
| Shaw’s | Taurodontism | “Cynodont” is the name given to Normal tooth. | [KAR-03] |
——————————————————————————–
4. VALUE & CRITERIA SYSTEMS
Frequency & Prevalence
• Congenital Defects: The most common congenital defect of the face and jaws is Cleft lip and palate [COMEDK-07].
• Missing Teeth: Most common missing tooth in permanent dentition is Mandibular 2nd premolar [AIIMS-98, 01], [AIPG-05]. In children, most frequently missing permanent teeth are Second premolars [KAR-2001]. In hypodontia, most commonly affected is Permanent second premolar [COMEDK-14].
• Supernumerary Teeth:
◦ Most Common: Mesiodens [APPG-15].
◦ 2nd Most Common: Distomolar [AIPG-2010].
◦ Form: Conical is most common [AIIMS-95].
◦ Location: More common in mandible is FALSE (Maxilla is more common) [AIIMS-91]. Highest frequency in Maxillary permanent dentition [AIPG-06].
• Cysts: The most common developmental cyst is Nasopalatine cyst [AIIMS-08].
• Tumors: Most common site for melanotic neuroectodermal tumour of infancy is Maxilla [AIIMS-2011].
Chronology & Incidence
• Enamel Hypoplasia: Defects in permanent central/lateral incisors result from factors during First year of life [AIPG-95]. Generalized growth failure in first 6 months causes Enamel hypoplasia [AIPG-91]. Developmental enamel defects are most commonly seen in Permanent incisors [PGI-2011].
• Developmental Defects: Maximum incidence is seen in Permanent first molar / Permanent incisors [PGI DEC-2011].
——————————————————————————–
5. COMPARISON FRAMEWORKS
Cystic Lesions
• Gingival Cysts of Newborn: Bohn’s nodules are cysts of gingiva in growing children [KAR-98, COMEDK-05]. Epstein pearls are Gingival cyst of newborn [AIIMS-95], arising from Epithelial rests [PGI-95]. Identified as white nodules [AIPG-2021].
• Nasopalatine Duct Cyst: Also known as Premaxilla-premaxillary cyst [AIPG-2012]. Classified as a Fissural cyst [AP-2K].
• Globulomaxillary Cyst: Inverted pear shaped radiolucency between maxillary lateral incisor and cuspid [ΜΑΝ-97, 98], [AI-05, AIIMS-07]. Teeth are normal [AIPG-2001]. Cysts associated with vital teeth include Globulomaxillary, Dentigerous, lateral periodontal [COMED-2012].
• Nasolabial Cyst: Soft tissue cyst [ΜΑΝ-97, 98] which do not produce any radiographic changes [MAN-97, AIIMS-94]. Arises from Remnants of embryonic lacrimal duct [KAR-03]. Presents with fullness of upper lip, elevation of nostril [MHCET-15].
• Thyroglossal Duct Cyst: Moves downwards on tongue protrusion is FALSE (moves upwards) [AIPG-2002].
• Dermoid Cyst: A form of Cystic Teratoma [PGI JUNE-2017].
• Pseudocysts:
◦ Stafne Bone Cyst: Does not give blood on aspiration [MAN-2002]. Develops from Salivary gland inclusion [KAR-2013].
◦ Primordial Cyst: Derived from stellate reticulum [AIPG-2012].
◦ Radiographic Defect: Multilocular defect could be Nevoid Basal Cell Carcinoma / Cherubism [AIPG-2022].
Dentin Anomalies
• Dentinogenesis Imperfecta: Obliterated pulp.
• Dentin Dysplasia (Coronal): Thistle-tube appearance of pulp chamber [COMEDK-06].
• Regional Odontodysplasia: Large pulp chambers [APPSC-99]. Large pulp chambers are characteristic of all EXCEPT Dentinogenesis imperfecta [COMEDK-06].
Facial Asymmetry
• Facial Hemiatrophy: Differentiated from fibrous dysplasia by Shape, size and difference in eruption pattern of teeth [AIPG-14].
——————————————————————————–
6. TRAP PATTERNS
Tooth Counting
• Fusion: Results in one tooth less than normal dentition [PGI-2K].
• Anodontia: In false anodontia tooth doesn’t undergo full development (False statement) [AIIMS-95]. Anodontia affects growth of Alveolar bone [KAR-90].
Eruption Traps
• Delayed Eruption: NOT seen in Congenital hyperthyroidism [AIIMS-93, KAR -2K] or Neuralgia [AIIMS MAY 2021].
• Primary Failure: Due to mutation in PTHR1 gene [AIIMS DEC-2020].
Hereditary vs Non-Hereditary
• Regional Odontodysplasia: Is not hereditary [AIIMS-92, 99, 03].
• Amelogenesis Imperfecta: In hereditary hypoplasia, All deciduous and permanent teeth would be affected [AIPG-2022].
Systemic Associations
• Hypophosphatasia: Premature exfoliation of primary teeth, large pulp chamber [PGI JUNE-2017]. Exfoliation due to incomplete root formation (lack of cementum) [AIPG-2021].
• Cleidocranial Dysostosis: Unlikely to cause enamel hypoplasia [KAR-01].
• Apertognathia: Defined as Open bite [AIIMS MAY 2021].
• Thistle-Tube Pulp: Feature of Coronal dentin dysplasia [COMEDK-06].
Radiographic Identification
• Torus Palatinus: Bony hard asymptomatic swelling on midline of hard palate appearing radiopaque [AIPG-04].
• Supernumerary: Anomaly above apices [AIPG-2022] or Supernumerary teeth [AIPG-2021].
• Mesiodens: Highlighted by arrow in occlusal radiograph [APPG-15].