Jumat, 02 Desember 2011

Notes on Developmental defects of the oral and maxillofacial regions

Developmental defects of the jaws
  1. Orofacial clefts
  2. Coronoid hyperplasia
  3. Condylar hyperplasia
  4. Condylar hypoplasia
  5. Bifid condyle
  6. Exostoses
  7. Torus palatinus
  8. Torus mandibularis
  9. Eagle syndrome
  10. Stafne defect
  11. Hemihyperplasia
  12. Progressive hemifacial atrophy
  13. Segmental odontomaxillary dysplasia
  14. Crouzon syndrome
  15. Apert syndrome
  16. Mandibulofacial dysostosis
  17. Pierre Robin syndrome
Orofacial clefts
  • Most common major congenital defects in humans
  • Frequency of CL +/- CP : Native americans,Asians, Whites, Blacks
  • CL+CP 45%, CPO 30%, CLO 25%
  • More common in males than in females
  • CL: 80%-unilateral (70%-left side), 20%-bilateral
  • 70% of unilateral CLs are associated with CP
  • Minimal manifestation of CP is a bifid uvula
  • Submucosal palatal-the surface mucosa is intact, but a defect exists in the underlying musculature of the soft palate
Coronoid hyperplasia
  • Rare, unknown cause
  • Male-to-female ratio = 5:1
  • Endocrine influence, heredity
  • Bilateral CH is more common than unilateral CH*
  • Restricts mandibular opening and causes deviation toward affected side*
Condylar hyperplasia
  • Excessive growth of one of the condyles
  • Endocrine disturbances and trauma
  • Facial asymmetry, prognathism, crossbite and open bite
  • Most commonly found in adolescents and young adults
  • Self limiting condition

Condylar hypoplasia
  • Underdevelopment of the mandibular condyle
  • Congenital
  •    (mandibulofacial dysostosis, hemifacial microstomia)
  • Acquired
  •   (trauma to the condylar region during infancy or childhood, infection, radiation therapy, RA, OA)
Bifid condyle
  • Double-headed mandibular  condyle
  • Medial and lateral head divided by an anteroposterior groove
  • Trauma, abnormal muscle attachment, teratogenic agents, persistence of a fibrous septum within the condylar cartilage
  • Popping or clicking sound when opening the mouth

  • Localized bony protuberances that arise from the cortical plate
  • Adults
  • A bilateral row of bony hard nodules along the facial aspect of the maxillary and mandibular alveolar ridge

Torus palatinus/mandibularis
Torus palatinus
  • Common exostosis that occurs in the midline of the vault of the hard palate
  • Genetics vs environmental or both
  • Asian and Inuit
  • Female:Male = 2:1

Torus mandibularis
  • A bony protuberance along the lingual aspect of the mandible above the mylohyoid line in the region of the premolars
  • Bilateral
  • May appear on periapical radiographs as a radiopacity superimposed on the roots of the tooth

Eagle syndrome
  • Elongation of the styloid process or mineralization of the stylohyoid ligament complex
  • Adults, Most commonly unilateral
  • Vague, radiated facial pain while swallowing, turning the head or opening the mouth
  • Classic Eagle syndrome – After tonsillectomy
  • Stylohyoid syndrome – impinge on the internal or external carotid arteries and associated sympathetic nerve fibers

Stafne defect
  • An asymptomatic radiolucency below the mandibular canal in the posterior mandible, between the molar teeth and the angle of the mandible
  • Typically well-circumscribed with a sclerotic border
  • Mostly unilateral
  • Reported in middle-aged and older adults, children is rarely affected
  • Normal submandibular gland tissue
  • No treatment required

  • Asymmetric overgrowth of one or more body parts (right side)
  • 2:1 female-to-male predilection
  • Asymmetry may be noted at birth
  •  The enlargement becomes more accentuated with age especially at puberty
  • Skin on the affected side: thickened, increased pigmentation, hypertrichosis, telangiectasias or nevus flemmeus
  • Oral: Macroglossia, larger mandibular canal-crowns
  • Differentiated from Proteus syndrome, NF1
Progressive hemifacial atrophy
  • Atrophic changes affecting one side of the face
  • ?trophic malfunction of the cervical sympathetic nervous system, trauma, hereditary
  • Close relationship with localized scleroderma
  • Starts during the first 2 decades of life
  • Atrophy of the skin and subcut. Affecting the dermatome of CNV, osseous hypoplasia
  • Oral: mouth deviated toward the affected side, unilateral atrophy of the tongue, unilateral posterior open bite, deficient root formation or resorption

Segmental odontomaxillary dysplasia
  • Childhood
  • Painless, unilateral enlargement of the maxillary bone along with fibrous hyperplasia of the overlying gingival soft tissues
  • Missing developing maxillary premolars, hypoplastic primary teeth
  • X-Ray: thickened trabeculae-relatively radiopaque, granular appearance

Crouzon syndrome
  • Craniosynostosis : premature closing of the cranial sutures
  • FGFR2 gene mutation on chromosome 10q26
  • Brachy-scapho-trigonocephaly
  • Shallow orbit-visual impairment or total blindness
  • Headaches, beaten metal skull
  • Underdeveloped maxilla
Apert syndrome
  • Characterized by craniosynostosis
  • FGFR2 gene on chromosome 10q26
  • Autosomal dominant, paternal origin
  • Tower(clover leaf) skull, ocular proptosis with hypertelorism, visual loss, hypoplastic middle face – mandibular prognathism, open- mouth appearance, syndactyly*, mental retardation, cleft soft palate

Mandibulofacial dysostosis
  • Defects of structures derived from the first and second branchial arches
  • Autosomal dominant
  • TCOF1 gene mapped to chromosome 5q32-q33.1
  • Hypoplastic zygoma, narrow  face, depressed cheeks, coloboma, tongue-shaped sideburns, anomalies of ears, underdeveloped mandible

Pierre Robin syndrome
  • Triad: CP, mandibular micrognathia and glossoptosis
  • The retruded mandible results in: Posterior displacement of the tongue
                                Lack of support of the tongue    musculature
                                Airway obstruction
*             Respiratory difficulty in supine position noted from birth
*             The palatal cleft is often U0shaped and wider than isolated CP

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