Understanding Dental Developmental Disorders: A Comprehensive Guide

Developmental disorders Assoc. Professor Jan Laco, MD, PhD

Developmental disorders • 1. Teeth • 2. Jaws • 3. Clefts • 4. Oral soft tissue

Developmental disorders - teeth • 1a. Abnormalities of size and form • 1b. Abnormalities of number • 1c. Defects of structure • 1d. Disorders of eruption

1a. Abnormalities of size and form • microdontia …teeth < normal • permanent teeth • absolute x relative • generalized x single (upper I2, M3) • macrodontia …teeth > normal • absolute x relative • generalized x single

1a. Abnormalities of size and form • gemination (schizodontia, twinning) • incomplete division of tooth germ • 2 separated crowns on single root, upper I1 • fusion (synodontia) • concrescence • fusion after development of roots (injury) • teeth united by cementum

1a. Abnormalities of size and form • dilaceration • angulation at crown-root junction (injury) • difficult extraction • talon cusp • lingual or palatal aspect of permanent teeth • dens invaginatus (dens in dente) • invagination of enamel into pulp chamber • upper I2, bilateral, caries

1a. Abnormalities of size and form • taurodontism (bull tooth) • wide pulp chamber • molars • enamel pearl • displaced ameloblasts below amelocemental junction • mm nodule, upper M

1b. Abnormalities of number • Isolated hypodontia– common • hereditary • M3 + P2 + I2 • M3 + P2: NO effect • I2: false eruption of C to I1 • Anodontia – very rare

1b. Abnormalities of number • Anhidrotic ectodermal dysplasia • X-linked inheritance • hypodontia + hypotrichosis + anhidrosis • failure of development of alveolar process • Down´ s syndrome • no M3 (90% patients)

1b. Abnormalities of number • Hyperdontia (additional teeth) – common • supernumerary: conical • incisor + molar region + midline (mesiodens) • supplemental: normal • excessive growth of l. dentalis • M4 • Cleidocranial dysplasia • Gardner´s syndrome

1c. Defects of structure • deciduous teeth • neonatal jaudice  yellow • congenital porphyria  red • Tetracycline • permanent teeth • periapical infection of d. predeccesor – Turner tooth • systemic diseases

1c. Defects of structure – systemic diseases • genetic • amelogenesis imperfecta • dentinogenesis imperfecta • Ehlers-Danlos syndrome, Gardner´s syndrome • infective – congenital syphilis • metabolic – childhood infections, rickets • drugs – tetracycline, cytotoxic chemotherapy • fluorosis

1c. Defects of structure – systemic diseases • Amelogenesis imperfecta • all teeth + whole enamel x dentine normal • Hereditary enamel hypoplasia • AD inheritance • defect of matrix formation – pits, grooves, hard • Hereditary enamel hypocalcification • AD + AR inheritance • normal matrix poorly calcified – soft, chalky

1c. Defects of structure – systemic diseases • Chronological hypoplasia • transient impairment of enamel formation in case of severe illness • severe fever, gastroenteritis, measles in the past • horizontál bands of pits, grooves, defects • Molar-incisor hypomineralisation • all M1 a I1 a I2 • enamel - hard surface, but soft beneath • yellow brown discoloration, ↑ caries

1c. Defects of structure – systemic diseases • Dentinogenesis imperfecta • defect of collagen/sialoprotein, AD • normal teeth shape • brownish, translucent enamel  chip away • obliteration of pulp • dentine - few tubules + abnormal matrix + incomplete calcification • “shell teeth“ – thin mantle of dentine covers abnormal dentine, few odontoblasts, no roots Dentinal dysplasia • very short and conical roots, teeth are lost early Regional odontodysplasia (ghost teeth (radiolucent on RTG)) • hypoplastic / hypomineralised enamel + thin dentine

1c. Defects of structure – systemic diseases • Ehlers - Danlos syndrome (floppy joints) • collagen disorder • hypermobile joints + loose skin • small teeth + short roots + pulp stones • Gardner´s syndrome • multiple osteomas (jaws) + skin tumors + colonic polyps  malignant change • impacted teeth, supernumerary teeth

1c. Defects of structure – systemic diseases • Congenital syphilis – Hutchinson (1858) • later fetal infection • dental follicle infection by T. pallidum • chronic inflammation  fibrosis of tooth sac  compression of developing tooth  distortion of ameloblasts • permanent teeth • upper I1 (Hutchinson´s incisors) – barrel-shaped, fissure on incisal edge • M1 (Moon´s molars) – dome-shaped, pitted occlusal surface (“mulbery molar“)

1c. Defects of structure – systemic diseases • Tetracycline (TTC) • taken up calcifying tissues • yellow fluorescence (UV light) • during teeth development – fetus x infancy • dentine • bright yellow  brown  grey • permanent teeth • Avoid TTC under 12 years

1c. Defects of structure – systemic diseases • Fluorosis (mottled enamel) •  fluoride in drinking water, India • during dental development • paper-white patches  brown • permanent teeth • hydroxyapatite  calcium fluoroapatite • patches of incomplete calcification with high organic and water content • enamel matrix usualy normal

1d. Disorders of eruption • deciduous teeth: 6th – 30th month • at birth: natal teeth • 1st month: neonatal teeth (lower I1) • permanent teeth: 6th – 13th y (M3: 18th – 30th y) • loss of space, retention of a dec. predecessor • cretenism, rickets

2. Developmental disorders - jaws • micrognathia x macrognathia • hereditary prognathism • craniofacial anomalies • cherubism • Gardner´s syndrome • osteogenesis imperfecta

3. Developmental disorders - clefts • NOT clefts  non-fusion !!! • ? ethiology - genetic component (40%) • cleft lip -  males, inc. 1/1000 • cleft palate -  females, inc. 1/2000 • lip : lip + palate : palate …22% : 58% : 20% • + Down´s syndrome (1 in 200 pts.) • van der Woude syndrome (AD, IRF6 gene) • clefts + pits on lower lips + hypodontia

3. Developmental disorders - clefts • cleft lip – cheiloschisis • lateral: unilateral (left side) x bilateral • medial • alveolar ridge cleft – gnathoschisis • hard palate cleft – palatoschisis • soft palate cleft - uranoschisis • uvula cleft - staphyloschisis

3. Developmental disorders - clefts • complications • malformation or absence of teeth in defect • + other congenital defects • feeding disorder • breathing disorder • middle ear infections • speech defect • cosmetic defect

4. Developmental disorders – oral soft tissues • 4a. oral mucosa • 4b. gingiva and periodontium • 4c. tongue

4a. Developmental disorders – oral mucosa • white sponge nevus – AD inheritance • white, soft, thickened area of oral mucosa • Mi: acantosis + hyperkeratosis + intracellular edema • Fordyce´s granules • heterotopic sebaceous glands • 80% adults • soft yellowish spots or papules • symmetrical, buccal location

4b. Developmental disorders – gingiva and periodontium • hereditary gingival fibromatosis • AD inheritance • grossly enlarged gingivae - preceding of teeth eruption • Mi: collagen bundles • gingivectomy after puberty • Ehlers-Danlos syndrome

4c. Developmental disorders – tongue • macroglossia • muscle hypertrophy • congenital hemangioma or lymphangioma • Down´s syndrome • lingual thyroid • incidence 10% • nodule, foramen caecum • cleft tongue • ankyloglossia

4c. Tongue Lingua plicata • cerebelli-, cerebriformis, fissurata, gyrata, scrotalis • fissured dorsal aspect of tongue • children x adults • asymptomatic x pain during eating, hygiene • + geographical tongue • + Cowden syndrome • + Melkersson-Rosenthal syndrome

4c. Jazyk Lingua geographica • geographical tongue, glossitis migrans • + lingua plicata; ± psoriasis • asymptomatic x pain during eating • irregular smooth red area  healing (hours / days)  another red area appears • centre – epithelium thinning; periphery – hyperplasia + keratinization; mild inflammation

Understanding Dental Developmental Disorders: A Comprehensive Guide