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Medical problems 4 4

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  • 1. Islam Kassem, BDS , MSc, MOMS RCPS Glasg,FFD RCSIConsultant Oral & Maxillofacial SurgeonMedical Topics inOrthodonticsikassem@dr.com
  • 2. Embryonic DevelopmentThe construction of an adultfrom a single cell, the fertilizedegg (zygote).ikassem@dr.com
  • 3. 1. DifferentiationA Single Cell, the FertilizedEgg, Gives Rise to Hundredsof Different Cell Types. ThisGeneration of Cellular DiversityIs Called Differentiation.ikassem@dr.com
  • 4. 2. Morphogenesis -- PatternFormationDifferentiation is carefully orchestrated. Therepertoire includes: Proliferation Cell migration Interactions (Induction) Epithelial-mesenchymal transformations Epithelial folding, movement, in- &evagination, fusion Apoptosis …ikassem@dr.com
  • 5. 3. Controlled Growthikassem@dr.com
  • 6. Dolly and Bonnie.ikassem@dr.com
  • 7. Homeotic mutation:Master Regulatory Genesikassem@dr.com
  • 8. DevelopmentalRegulatory genes areTranscription factorsTranscription factors or gene regulatory proteinsare involved in activating or repressing transcription.TFs act by binding to the control regions of genesor by interacting with other DNA-binding proteins.ikassem@dr.com
  • 9. Homeodomain Proteinsikassem@dr.com
  • 10. Hedgehogikassem@dr.com
  • 11. Congenital Malformations Causes– Genetic/chromosomal– Enviornmental Incidence– 2-3% of newborn (4-6% by age 5)– In 40-60% of all birth defects cause isunknown Genetic/chromosomal– 10%-15% Environmental– 10% Multifactorial (genetic & environmental)– 20%-25% ikassem@dr.com
  • 12. Teratology Teratology– Science that studies the causes of abnormaldevelopment– The term is derived from the Greek ―teratos‖which means monster– Birth defects is the number one cause ofinfant mortalityikassem@dr.com
  • 13. Terms used in Disease Sign  objective evidence of a disease Symptom  subjective evidence of adisease Syndrome  refers to a set of symptoms& signs which occur together in themorbid (disease) state Etiology  the study of the cause ofdiseaseikassem@dr.com
  • 14. Types of Anomalies Malformations– Occur during formation of structures Complete or partial absence Alterations of its normal configuration Disruptions– Morphological alterations of structures afterformation Due to destructive processesikassem@dr.com
  • 15.  Deformations– Due to mechanical forces that mold a part offetus over a prolonged period of time Clubfeet due to compression in the amniotic cavity Often involve the musculoskeletal system & maybe reversible postnatally Syndromes– Group of anomalies occuring together with aspecific common etiology Diagnosis made & risk of recurrence is knownikassem@dr.com
  • 16. Environmental factors Infectious agents Radiation Chemical Agents Hormones Maternal Disease Nutritional Deficiencies Hypoxiaikassem@dr.com
  • 17. Infectious Agents Rubella (German Measles)– Malformations of the eye Cataract (6th week) Microphthalmia– Malformations of the ear (9th week) Congenital deafness– Due to destruction of cochlea– Malformations of the heart (5th -10th week) Patent ductus arteriosis Atrial septal defects Ventricular septal defectsikassem@dr.com
  • 18.  Cytomegalovirus– Disease is often fatal early on– Malformations Microcephaly– Cerebral calcifications– Blindness Chorioretinitis– Kernicterus (a form of jaundice)– multiple petechiae of skin– Hepatosplenomegaly– Mother asymptomaticikassem@dr.com
  • 19.  Herpes Simplex Virus– Intrauterine infection of fetus occasionally occurs– Usually infection is transmitted close to time ofdelivery– Abnormalities (rare) Microcephaly Microphthalmos Retinal dysplasia Hepatosplenomegaly Mental retardation– Usually child infected by mother at birth Inflammatory reactions during first few weeksikassem@dr.com
  • 20.  Varicella (chickenpox)– Congenital anomalies 20% incidence following infection in 1st trimester Limb hypoplasia Mental retardation Muscle atrophy HIV/AIDS– Microcephaly– Growth retardation– Abnormal facies (expression or appearance ofthe face)ikassem@dr.com
  • 21.  Toxoplamosis– Protozoa parasite (Toxoplama gondii) Sources– Poorly cooked meat– Domestic animals (cats)– Contaminated soil with feces Syphilis– Congenital deafness– Mental retardation– Diffuse fibrosis of organs (eg. liver & lungs) In general most infections are pyrogenic– Hyperthemia can be teratogenic Fever Hot tubs & Saunasikassem@dr.com
  • 22. Radiation Teratogenic effect of ionizing radiationwell established– Microcephaly– Skull defects– Spina bifida– Blindness cleft palate– Extremity defects Direct effects on fetus or indirect effectson germ cells May effect succeeding generations Avoid X-raying pregnant womenikassem@dr.com
  • 23. Chemical agents/Drugs Role of chemical agents & drugs inproduction of anomalies is difficult to assess– Most studies are retrospective Relying on mother’s memory– Large # of pharmaceutical drugs used bypregnant women NIH study – 900 drugs taken by pregnant women– Average of 4/woman during pregnancy– Only 20% of women use no drugs during pregnancy– Very few drugs have been positively identifiedas being teratogenicikassem@dr.com
  • 24. Drugs Thalidomide– Antinauseant & sleeping pill– Found to cause amelia & meromelia Total or partial absence of the extremities– Intestinal atresia– Cardiac abnormalities– Many women had taken thalidomide early inpregnancy (in Germany in 1961)ikassem@dr.com
  • 25.  Anticonvulsants (to treat epilepsy)– Diphenylhydantoin (phenytoin) Craniofacial defects Nail & digital hypoplasia Growth abnormalities Mental deficiency The above pattern is know as ―fetal hydantoinsyndrome‖– Valproic acid Neural tube defects Heart defects Craniofacial & limb anomaliesikassem@dr.com
  • 26.  Antipsychotic drugs (major tranquilizers)– Phenothiazine & lithium Suspected teratogenic agents Antianxiety drugs (minor tranquilizers)– Meprobamate, chlordiazepoxide, Severe anomalies in 11-12% of offspring wheremothers were treated with the above compared to2.6% of controls– diazepam (valium) Fourfold  in cleft lip with or without cleft palateikassem@dr.com
  • 27.  Anticoagulants– Warfarin (A.K.A cumadin or cumarol) Teratogenic Hypoplasia of nasal cartilage Chondrodysplasia Central nervous system defects– Mental retardation– Atrophy of the optic nerves Antihypertensive agents– angiotensin converting enzyme (ACE) inhibitor Growth dysfunction, renal dysfunction,oliogohydramnios, fetal deathikassem@dr.com
  • 28.  Isotretinoin (13-cis-retinoic acid)– Analogue of vitamin A– Drug is prescribed for treatment of cystic acne& other chronic dermatoses– Highly tertogenic Reduced & abnormal ear development Flat nasal bridge Cleft palate Hydrocephaly Neural tube defects Heart anomaliesikassem@dr.com
  • 29. Recreational drugs PCP angel dust– Possible malformations & behavioraldisturbances Cocaine-vasoconstrictor  hypoxia– Spontaneous abortion– Growth retardation– Microcephaly– Behavioral problems– Urogenital anomalies– gastroschisisikassem@dr.com
  • 30. Alcohol Relationship between alcohol consumption& congenital abnormalities Fetal alcohol syndrome– Craniofacial abnormalities Short palpebral fissures Hypoplasia of the maxilla– Limb deformities Altered joint mobility & position– Cardiovascular defects Ventricular septal abnormalites– Mental retardation– Growth deficiencyikassem@dr.com
  • 31. Cigarette Smoking Has not been linked to major birth defects– Smoking does contribute to intrauterinegrowth retardation & premature delivery– Some evidence that is causes behavioraldisturbancesikassem@dr.com
  • 32. Maternal Disease Disturbances in CHO metabolism (diabeticmothers)– High incidence of stillbirth, neonatal deaths– Abnormally large infants– Congenital malformations  risk 3-4X Cardiac, Skeletal, CNS Anomalies Caudal dysgensis– Partial or complete agenesis of sacral vertebrae inconjuction with hindlimb hypoplasia– Hypoglycemic episodes teratogenic (why?)– Oral hypoglycemic agents  maybeteratogenicikassem@dr.com
  • 33. Hypoxia Associated with congenital malformationsin a great variety of experimental animals– In humans ??? Maybe smaller babies e.g. offspring at highaltitudeikassem@dr.com
  • 34. Environmental Chemicals Mercury– Fish, seed corn sprayed with mercurycontaining fungicide Multiple neurological symptoms Lead–  abortions– Growth retardation– Neurological disordersikassem@dr.com
  • 35. Prevention of birth defects Good prenatal care Iodine supplementation eliminates mentalretardation & bone deformities– Prevent cretinism Folate/Folic Acid supplementation–  incidence of neural tube defects Avoidance of alcohol & other drugs duringall stages of pregnancy–  incidence of birth defectsikassem@dr.com
  • 36. Chromosomal & Genetic Factors Numerical Abnormalities– Trisomy 21 (Down syndrome)– Trisomy 18– Trisomy 13– Klinefelter Syndrome– Turner Syndrome– Triple X Syndrome Structural Abnormalities Mutant Genesikassem@dr.com
  • 37. Chromosomal Abnormalities May be numerical or structural Important causes of congenitalmalformations & spontaneous abortions Estimated that 50% of all conceptions endin spontaneous abortion & 50% of thesehave major chromosome abnormalities Most common chromosome abnormalitiesin aborted fetuses is:– Turner syndrome (45,X)– triploidy– trisomy 16ikassem@dr.com
  • 38. Numerical Abnormalities Normal gametes are haploid (n =23) Normal human somatic cell contains 46chromosomes; Diploid (2n = 46) Euploid-Exact multiple of n Aneuploid-Any chromosome # that is noneuploid– Additional chromosome– Missing chromosome Most common cause is nondisjunction duringeither meiosis to mitosis– Risk of meiotic nondisjunction  with  maternal ageikassem@dr.com
  • 39. Structural Abnormalities May involve one or more chromosomes Usually result from chromosome breakage– Broken piece may be lost Partial deletion of chromosome 5– Cri-du-chat (cry of the cat) Microcephaly Mental retardation Congenital heart disease Many other relatively rare syndromesresult from a partial chromosome lossikassem@dr.com
  • 40. Mutant Genes Many congenital malformations areinherited– Some show a clear mendelian pattern ofinheritance– In many cases abnormality is attributed to achange in the structure or function of a singlegene. ―single gene mutation‖– Estimated that this type of defect makes upabout 8% of all human malformations– Dominant vs. recessive vs. X-linked (alsorecessive)ikassem@dr.com
  • 41. Orofacial EmbryologyPrenatal Developmentikassem@dr.com
  • 42. Head formation rostral or head fold anterior portion of the neural tubeexpands as the forebrain, midbrainand hindbrain the neuroectoderm in this region willform the olfactory, orbital andotic placodes the hindbrain forms 8 bulges =rhombomeres the paraxial mesoderm in this regionalso segments into somites migration of neural crest cells intothis region provides the embryonicconnective tissue (mesenchyme)required for development of thecraniofacial structures these neural crest cells arise from themidbrain and the first tworhombomeres as two streamsikassem@dr.com
  • 43. Branchial arches also called pharyngeal arches figure 4-11 fourth week: development of afrontal prominence forms thestomatodeum below this is the formation of thefirst branchial arch(mandibular arch) 6 pairs – U shaped– core of mesenchymal tissueformed from neural crest cells thatmigrate in to form the arches– covered externally by ectodermand lined internally by endoderm– each has its own developingcartilage, nerve, vascular andmuscular components these arches separate thestomatodeum from the developingheartikassem@dr.com
  • 44. Branchial arches separated laterally by branchial grooves/clefts medially they are separated by pharyngeal pouches first arch (mandibular arch) – maxillary and mandibularprocesses second arch (hyoid arch) - hyoid bone, part of the temporal bone(VII nerve) cartilage = Reichert’s cartilage the mesoderm of this arch will form the muscles of facial expression, themiddle ear muscles third arch –tongue (IX nerve) fourth arch –tongue, most of the laryngeal cartilages (IX and Xnerves) fifth arch – becomes incorporated into the fourth sixth arch – most of the laryngeal cartilages (IX and X nerves)ikassem@dr.com
  • 45. Pharyngeal Pouches– four well-defined pairs of pharyngeal pouches develop fromthe lateral walls of the pharynx– first pouch (betwen the 1st and 2nd arches) - external acousticmeatus, tympanic membrane, and eustachian tube– second pouch – palatine tonsils– third pouch - thyroid and parathyroid glands,– fourth pouch – parathryoid gland– fifth pouch -becomes incorporated into the fourthikassem@dr.com
  • 46. Development of the Face forms from the fusion of 5 face primordiawhich develop during week 4 and fuseduring weeks 5 through 8– primordia = ectodermal swellings orprominences that are filled with mesodermaland neural crest cells frontonasal prominence mandibular prominences (2) – from branchialarch #1 maxillary prominences (2) – from branchialarch #1ikassem@dr.com
  • 47. Development ofthe Faceikassem@dr.com
  • 48. Stomatodeum primitivestomatodeum formsa wide shallowdepression in theface – limited in itsdepth by thebuccopharyngealmembraneikassem@dr.com
  • 49. Upper lip formation during the fourth week fusion of the maxillary processes witheach medial nasal process this contributes to the lateral sides ofthe upper lip – together with themedial nasal processes whichcontribute to the medial aspect of theupper lip the maxillary processes also fuse withthe lateral nasal processes – results ina nasolacrimal groove whichextends from the medial corner of theeye to the nasal cavityikassem@dr.com
  • 50. Development of the Palate involves the formation of aprimary palate, a secondary palateand fusion of their processes Primary palate– forms from an internal swelling of theintermaxillary/premaxillary process(fusion of medial nasal processes) Secondary palate– forms from the two lateral palatineshelves or processes– develop as internal projections of themaxillary prominencesikassem@dr.com
  • 51. Primary palate fusion of themedian nasalprocesses gives riseto the medianpalatine process –fuses to form theprimary palateikassem@dr.com
  • 52. Secondary Palate the common oronasal cavity is boundedanteriorly by the primary palate andoccupied by the developing tongue only after the development of thesecondary palate can oral and nasalcavities by distinguished three outgrowth appear in the oral cavity– nasal septum: grows downward through the oral cavity it encounters the primary and secondarypalates– two palatine shelves closure of the secondary palate is likelyto involve the hardening of the palatineshelves – mechanism remains unknown+ the withdrawl of the tongueikassem@dr.com
  • 53. Maxilla formation centers of ossification develop in the mesenchyme of the maxillaryprocesses of the first branchial arch spreads posteriorly below the orbit towards the developing zygoma andanteriorly toward the future incisor region and superiorly to form thefrontal process ossification also spreads into the palatine process to form the hard palate at the union between the palatal process and the main body of thedeveloping maxilla is the medial alveolar plate – together with thelateral plates – development of the maxillary teeth a zygomatic or malar cartilage appears in the developing zygomaticprocesses and contributes to the development of the maxillaikassem@dr.com
  • 54. Mandible formation the cartilage of the first branchial archassociated with the formation of themandible = Meckel’s cartilage 6 weeks: Meckel’s cartilage forms a rodsurrounded by a fibrocellular capsule the two cartilages do not meet at the midlinebut are separated by a thin line of cartilage =symphysis on the lateral aspect of this symphysis – acondensation of mesenchyme forms at 7 weeks intramembranous ossificationbegins in this mesenchyme and spreadsanteriorly and posteriorly to form the boneof the mandible the bone spreads anteriorly to the midline ofthe developing lower jaw – the bones do notfuse at the midline – mandibular symphysisforms (from meckel’s cartilage)– which fuses shortly after birth the ramus develops from rapid ossificationposteriorly into the mesenchyme of the firstarchikassem@dr.com
  • 55. Mandible formation-Meckel’s cartilage does NOT contribute directly to the ossification ofthe mandible-posterior extremity – malleolus of the inner ear-portion persists as the sphenomandibular ligament-significant portion is resorbed entirely-most anterior portion near the midline may contribute to the jawthrough endochondral ossification-growth of the mandible until birth is influences by the appearance ofthree secondary (growth) cartilages1. condylar – 12th week, developing ramus by endochondralossification, a thick layer persists at birth at the condylar head(mechanism for post-natal growth of the ramus = endochondral)2. coronoid – 4 months, disappears before birth3. symphyseal – appears in the connective tissue at the ends of theMeckel’s cartilage, gone after 1 year after birthikassem@dr.com
  • 56. Development of the Tongue begins to develop about 4 weeks localized proliferation of themesenchyme results in formation ofseveral swellings in the floor of the oralcavity the oral part (anterior two-thirds)develops from the fusion of two distaltongue buds or lateral lingualswellings and a median tonguebud (tuberculum impar) the pharyngeal part or root of thetongue (posterior one-third) developsfrom the copula and thehypobranchial eminence (formsfrom the 2nd, 3rd and 4th branchialarches) these parts fuse (adult = terminalsulcus) muscles of the tongue arise fromoccipital somites which migrate intothe tongue areahypobranchial archovergrows the 2nd archB.As #1,2 and 3ikassem@dr.com
  • 57.  There are many developmentalabnormalities that can affect the teeth andfacial skeleton. In most cases, cliniciansneed little more than to be able torecognize these abnormalitiesikassem@dr.com
  • 58. ikassem@dr.com
  • 59. ikassem@dr.com
  • 60. Classification of developmentalabnormalities1-Anomalies of the teeth2-Skeletal anomalies.ikassem@dr.com
  • 61. Anomalies of the teeth1-Number2-Structure3-Size4-Shape5-Position.ikassem@dr.com
  • 62. Anomalies of the teeth1-Number2-Structure3-Size4-Shape5-Position.ikassem@dr.com
  • 63. 1-Abnormalities in number Missing teeth Additional teeth (hyperdontia)ikassem@dr.com
  • 64. Missing teeth• Localized anodontia or hypodontia —usually third molars, upper lateral incisors orsecond premolars.• Anodontia or hypodontia associated withsystemic disease — e.g. Downs syndrome,ectodermal dysplasia.ikassem@dr.com
  • 65. Additional teeth (hyperdontia)• Localized hyperdontia — Supernumeraryteeth— Supplemental teeth• Hyperdontia associated with specificsyndromes, e.g. cleidocranial dysplasia,Gardeners syndrome.ikassem@dr.com
  • 66. Anomalies of the teeth1-Number2-Structure3-Size4-Shape5-Position.ikassem@dr.com
  • 67. 2-Abnormalities in structure Genetic defects Acquired defectsikassem@dr.com
  • 68. Genetic defects• Amelogenesis imperfecta — Hypoplastictype— Hypocalcified type— Hypomature type• Dentinogenesis imperfecta• Shell teeth• Regional odontodysplasia (ghost teeth)• Dentinal dysplasia (rootless teeth).ikassem@dr.com
  • 69. Acquired defects• Turner teeth — enamel defects caused byinfection from overlying deciduous predecessor• Congenital syphilis — enamel hypoplastic andaltered in shape (see below)• Severe childhood fevers, e.g. measles —linearenamel defectsFluorosis — discolouration or pitting of theenamel• Discolouration — e.g. tetracycline staining.ikassem@dr.com
  • 70. Anomalies of the teeth1-Number2-Structure3-Size4-Shape5-Position.ikassem@dr.com
  • 71. 3-Abnormalities in size• Macrodontia — large teeth• Microdontia — small teeth, includingrudimentary teeth.ikassem@dr.com
  • 72. Anomalies of the teeth1-Number2-Structure3-Size4-Shape5-Position.ikassem@dr.com
  • 73. 4-Abnormalities in shape Anomalies affecting -whole teeth Anomalies affecting the crowns Anomalies affecting roots andlor pulpcanalsikassem@dr.com
  • 74. Anomalies affecting -wholeteeth• Fusion — two teeth joined together from thefusion of adjacent tooth germs• Gemination — two teeth joined together butarising from a single tooth germ• Concrescence — two teeth joined together bycementum• Dens-in-dente (invaginated odontome) — infolding of the outer surface of a tooth into theinterior usually in the cingulum pit region ofmaxillary lateral incisors.ikassem@dr.com
  • 75. Anomalies affecting thecrowns• Extra cusps• Congenital syphilis— Hutchinson s incisors — crowns small,screwdriver or barrel-shaped, and oftennotched— Moons/mulberry molars — dome-shaped ormodular• Tapering pointed incisors — ectodermaldysplasia.ikassem@dr.com
  • 76. Anomalies affecting roots andor pulp canals• Number — additional roots, e.g. two-rootedincisors, three-rooted premolars or four-rootedmolars• Morphology, including:— Bifid roots— Excessively curved roots— Dilaceration — sharp bend in the rootdirection— Taurodontism — short, stumpy roots andlongitudinally enlarged pulp chambersPulp stones — localized or associated withspecific syndromes, e.g. Ehlers-Danlos (floppyjoint syndrome).ikassem@dr.com
  • 77. Odontomes• Enameloma/enamel pearl• Cementoma (see fibro-cemento-osseousmesions in— Benign cementoblastoma (true cementoma)— Periapical cemento-osseous dysplasia— Focal cemento-osseous dysplasia— Florid cemento-osseous dysplasia(gigantiform cementoma)• Composite— Compound odontome — made up of one or moresmall tooth-like denticles— Complex odontome — complex mass of disorganizeddental tissue.ikassem@dr.com
  • 78. Anomalies of the teeth1-Number2-Structure3-Size4-Shape5-Position.ikassem@dr.com
  • 79. 5-Abnormalities in position Delayed eruption Other positional anomaliesikassem@dr.com
  • 80. Delayed eruption• Local causes— Loss of space— Abnormal crypt position — especially 8/8 and 3/3— Overcrowding— Additional teeth— Retention of deciduous predecessor— Dentigerous and eruption cysts• Systemic causes— Metabolic diseases, e.g. cretinism and rickets— Developmental disturbances, e.g. cleidocranial dysplasia— Hereditary conditions, e.g. gingival fibromatosis andcherubism.ikassem@dr.com
  • 81. Other positional anomalies• Transposition two teeth occupyingexchanged positions• Wandering teeth, movement of uneruptedteeth for no apparent reason (distal drift)• Submersion, second deciduous molarsapparently descend into the jaws. Since theseteeth do not in fact submerge, but ratherremain in their original position while theadjacent Other positional anomaliesikassem@dr.com
  • 82. Skeletal anomalies• Abnormalities of the mandible and/ormaxilla• Other rare developmental diseases andsyndromes.ikassem@dr.com
  • 83. Abnormalities of the mandibleor maxilla Micrognathia Macrognathia (prognathism) Other mandibular anomaliesikassem@dr.com
  • 84. Micrognathia• True micrognathia — usually caused by bilateralhypoplasia of the jaw or agenesis of the condyles• Acquired micrognathia — usually caused byunilateral early ankylosis of thetemporomandibular joint.ikassem@dr.com
  • 85. Macrognathia(prognathism)• Genetic• Relative prognathism — mandibular/maxillarydisparity• Acquired, e.g. acromegaly owing to excessivegrowth hormone from a pituitary tumour.ikassem@dr.com
  • 86. Other mandibular anomalies• Condylar hypoplasia• Condylar hyperplasia• Bifid condyle• Coronoid hyperplasia.ikassem@dr.com
  • 87. Cleft lip and palate• Cleft lip— Unilateral, with or without alveolar ridge— Bilateral, with or without alveolar ridge• Cleft palate— Bifid uvula— Soft palate only— Soft and hard palate• Clefts of lip and palate (combined defects)— Unilateral (left or right)— Cleft palate with bilateral cleft lip.ikassem@dr.com
  • 88. Alveolar cleftikassem@dr.com
  • 89. Localized bone defects• Exostoses— Torus palatinus— Torus mandibularis• Idiopathic bone cavities— Stafnes bone cavity.ikassem@dr.com
  • 90. Eagle’s syndromeikassem@dr.com
  • 91. Other rare developmentaldiseases and syndromes• Cleidocranial dysplasia• Gorlins syndrome (nevoid basal cellcarcinoma syndrome)• Eagle syndrome• Crouzon syndrome (craniofacial dysostosis)• Apert syndrome• Mandibular facial dysostosis (Treacher Collinssyndrome).ikassem@dr.com
  • 92. Tooth Developmentikassem@dr.com
  • 93. Stages of toothdevelopment1. Bud stage2. Cap stage3. Bell stage4. Appositional stage (mineralization)5. Root formation6. Eruption(epithelial ingrowth into ectomesenchyme)(further epithelial growth)(histo- and morpho-differentiation)(formation of enamel and dentin of crown)(formation of dentin and cementum of root)ikassem@dr.com
  • 94. Bud stage123451. oral epithelium2. dental lamina3. tooth bud4. ectomesenchymal cells5. vestibular laminaikassem@dr.com
  • 95. Cap stage1. Enamel organ (=dental organ)2. Dental papilla3. Dental sac (=dental follicle)123ikassem@dr.com
  • 96. Enamel organ of cap stage2131) Inner enamel ep2) Outer enamel ep3) Cervical loop4) Stellate reticulum5) Enamel knot6) Enamel cord7) Enamel navel4567transient structureduring cap stageikassem@dr.com
  • 97. Bell stage1. outer enamel ep.2. inner enamel ep.3. stellate reticulum4. stratum intermedium3214ikassem@dr.com
  • 98. Appositional stage1. oral ep.2. outer enamel ep.3. stellate reticulum4. inner enamel ep.5. dental papilla6. cervical loop321546bloodvesselsikassem@dr.com
  • 99. a. predentinb. dentinc. enamel1. ameloblasts2. preameloblasts3. odontoblasts4. preodontoblasts5. dental papilla6. stratum intermedium426a31bc5Appositionalstageikassem@dr.com
  • 100. Appositional stage(alkaline phosphatase )dentino-enameljunction(collagen fibers of mantle dentin)AprismaticMantleodontoblasts(predentin)Reduced stellate reticulumikassem@dr.com
  • 101. Formation of rootsHertwig epithelial root sheath(HERS)- Apical extension of cervical loop- Inner+outer enamel ep.- Not making enamel- Framework of root formationroot sheath epithelial diaphragm(size/shape/number of roots)ikassem@dr.com
  • 102. Periodontal tissuesoral epPeriodontalligamentAlveolar boneikassem@dr.com
  • 103. Tooth eruption1 mm4123561. oral ep.2. connective tissue3. alveolar bone4. Enamel5. Dentin6. HERSikassem@dr.com
  • 104. Tooth eruption1 mm• Axial movement toward oral epitheliumbegin when the root formation begin.• Source of erupting force: contraction of fibroblasts generatingperiodontal ligaments?ikassem@dr.com
  • 105. Tooth eruptionreduced enamel ep.osteoclastsfused with oral ep.form junctional ep.Alveolar bone and connective tissueare resorbed as teeth erupt.ikassem@dr.com
  • 106. Periodontal tissuesJunctional eporal epPeriodontalligamentAlveolar boneikassem@dr.com
  • 107. Relationship of primary teeth andsuccedaneous permanent teethsopen apexresorption of rooterupting eruptingD : deciduous toothP or S : succedaneous toothikassem@dr.com
  • 108. Summary of tooth developmentOral epitheliumDental laminaameloblastsInner enamel epStellate reticulumStratum intermediumOuter enamel ep HERSEctomesenchymeDental sacDental papilla odontoblastscementoblastsfibroblastsfibroblastsosteoblastsdentincementumpulpperiodontal ligamentalveolar boneenamelguide root formationoral epitheliumreduced enamel ep junctional ep.ikassem@dr.com
  • 109. Most odontogenic epithelial cells degeneratefollowing the completion of tooth formationOral epitheliumDental laminaameloblastsInner enamel epStellate reticulumStratum intermediumOuter enamel ep HERSEctomesenchymeDental sacDental papilla odontoblastscementoblastsfibroblastsfibroblastsosteoblastsdentincementumpulpperiodontal ligamentalveolar boneenamelguide root formationoral epitheliumjunctional ep.reduced enamel ep.ikassem@dr.com
  • 110. Molecular mechanism of toothdevelopment Many genes control tooth development but notcompletely understood– shape, number of cusp (incisor vs molar)– size– number (2 vs 3 molars…..)– location (mesio-distal, maxillo-mandibular….)– timing of formation and eruption Future of dentistry?– Control the number and location of teeth– In vitro formation of toothikassem@dr.com
  • 111.  Most common craniofacial malformation Cleft lip with or without cleft palate (CL/P)or isolated cleft palate (CP). CL/P and CP differ with respect to– Embryology, etiology, candidate genes,associated abnormalities, and recurrence risk.ikassem@dr.com
  • 112. Unilateral incomplete Unilateral complete Bilateral completeIncomplete cleft palate Unilateral complete lip andpalateBilateral completeikassem@dr.com
  • 113. ikassem@dr.com
  • 114. Prevalence CL/P is more common than CP and varies byethnicity. CL/P– High in American Indians and Asians (1/500newborns)– Low in American blacks (1/2000 newborns)– Intermediate level in Caucasians (1/1000newborns) Isolated CP occurs in only 1/2500 newbornsand does not display variation by ethnicity.ikassem@dr.com
  • 115. Cleft Lip Complete closure at 35 dayspostconception:– 7 weeks from the LMP.– Lateral nasal, median nasal, and maxillarymesodermal processes merge. Failure of closure can produce unilateral,bilateral, or median lip clefting. Left side unilateral cleft is the mostcommon.ikassem@dr.com
  • 116. Cleft lip Severity Mild, involving only the lip Extend into the palate and midfacethereby affecting the nose, forehead,eyes, and brain.ikassem@dr.com
  • 117. Cleft Palate Lack of fusion of the palatal shelves. Abnormalities in programmed cell deathmay contribute to lack of palatal fusion(?). Isolated disruption of palate shelves canoccur after closure of the lip Palatal closure is not completed until 9weeks post-conception.ikassem@dr.com
  • 118. Environmental agents Several agents that are associated with anincreased frequency of midfacialmalformation. Medications —phenytoin, sodiumvalproate, methotrexate. With corticosteroids there is no evidenceof an increase in malformations.– Possible association could not be excludedikassem@dr.com
  • 119. Prenatal Diagnosis Diagnosed until the soft tissues of thefetal face can be clearly visualizedsonographically (13 to 14 weeks). The majority of infants with cleft lip alsohave palatal involvement:– 85% of bilateral cleft lips– 70% associated with cleft palate.– Cleft palate with an intact lip comprises 27%of isolated CL/Pikassem@dr.com
  • 120. Prenatal Diagnosisikassem@dr.com
  • 121. Syndrome ? A thorough examination of the newborn orstillbirth is always warranted. Orofacial clefting is noted in over 300syndromes. 3 deserve additional comment.– frequency, variable presentations, and modesof inheritanceikassem@dr.com
  • 122. Deletion of chromosome 22q11 DeGeorge syndrome. Spectrum in addition to cleft palate:– Conotruncal cardiac defects, thymichypoplasia, and velopharyngeal webs. Majority of cases represent a newmicrodeletion In families with conotruncal malformationsand/or CP, further evaluation isappropriate.ikassem@dr.com
  • 123. Oral-facial-digital syndrome, type I X-linked dominant syndromes. Manifestations in affected females arevariable and subtle:– hyperplastic frenula– cleft tongue– cleft lip/palate– digital anomaliesikassem@dr.com
  • 124. Treacher-Collins syndrome Autosomal dominant disorder Downward slanting palpebral fissures,micrognathia, dysplastic ears, anddeafness.– Mental development is normal. The mutations appear to increase celldeath in the prefusion neural folds. A family history with deafness, earabnormalities, or CP.ikassem@dr.com
  • 125. Obstetrical Management Amniocentesis for karyotype should beoffered.– high rate of chromosomal defects Difficulty in prenatal sonographic diagnosissupports chromosomal evaluation As of January 2002, "in utero" correctionhad been attempted only once in Mexico– The child delivered prematurely and died attwo months of lifeikassem@dr.com
  • 126. Feedings Infants with CL/P have few feedingproblems. If the cleft involves the hard palate, theinfant is usually not able to suckefficiently.– Experiment (special nipples or alternatefeeding positions) The infant should be held in a nearlysitting position during feeding– Prevents flowing to the back into the nose.ikassem@dr.com
  • 127. Feedings It is important tokeep the cleft clean Breastfeeding isextremelychallenging.ikassem@dr.com
  • 128. Haberman Feeder Activated by tongue andgum pressure. Milk cannot flow back. Replenished continuouslyas the baby feeds. Prevents the baby frombeing overwhelmed withmilk. A gentle pumping actionto the body of the nipplewill increase flow.ikassem@dr.com
  • 129.  More than 3,000 syndromes classified Optimal growth, development, and learning requiresearly recognition and intervention Team Approach:– Parents– Pediatrician– Otolaryngologist– Cardiologist– Nephrologist– Geneticist– Speech Therapist– Teachers– OthersThe SydromalChildikassem@dr.com
  • 130. The SydromalChild History– Parental factors (age)– Consanguinity– Abortions– Teratogen exposure– Medical Pedigreeikassem@dr.com
  • 131.  Physical Exam– Major and Minor Anomalies Airway Skull Ears Facial skeleton– Comparison to Family Members– Reference MaterialThe SydromalChildikassem@dr.com
  • 132. Down Syndromeikassem@dr.com
  • 133.  Described by John Landon Down in1866 Etiology: nondisjuction mutationresulting in Trisomy 21 Prevalence 1:700– Most common chromosomal anomaly Associated with Maternal age > 35DownSyndromeikassem@dr.com
  • 134.  Facial Characteristics– Macroglossia– Micrognathia– Midface hypoplasia– Flat occiput– Flat nasal bridge– Epicanthal folds– Up-slanting palpebral fissures– Progressive enlargement of lipsDownSyndromeikassem@dr.com
  • 135. DownSyndromeikassem@dr.com
  • 136.  Airway Concerns– Due to midface hypoplasia, thenasopharynx and oropharynx dimensionsare smaller Slight adenoid hypertrophy can cause upperairway obstruction– Congenital mild-moderate subglotticnarrowing not uncommon Post-extubation stridorDownSyndromeikassem@dr.com
  • 137.  Obstructive Sleep Apnea– Prevalence 54-100% in DS patients– Combination of anatomic and functionalmechanisms Midface hypoplasia, macroglossia, etc Hypotonia of pharyngeal musclesDownSyndromeikassem@dr.com
  • 138.  Obstructive Sleep Apnea– Management: Polysomnography to confirm Medical interventions:– CPAP– Weight Loss– Medications to stimulate respiratory driveDownSyndromeikassem@dr.com
  • 139.  Obstructive Sleep Apnea– Management: Surgical– Adenoidectomy and Tonsillectomy Controversial– UPPP– Partial tongue resection– TracheotomyDownSyndromeikassem@dr.com
  • 140.  Otologic Concerns– Small pinna, Stenotic EAC Cerumen impaction– CHL ETD: PE tubes Ossicular fixation: surgical correction– SNHL Progressive ossification along outflow pathwayof basal spiral tractDownSyndromeikassem@dr.com
  • 141.  Cardiovascular anomalies (40%)– ASD, VSD, Tetralogy of Fallot, PDA GI anomalies (10-18%)– Pyloric stenosis, duodenal atresia, TEfistula Malignancy– 20 fold higher incidence of ALL– Gonadal tumorsDownSyndromeikassem@dr.com
  • 142. TreacherCollinsSyndromeikassem@dr.com
  • 143. TCS First described by Thomson and Toynbee in1846-7– Later, essential components described by TreacherCollins in 1960 Autosomal dominant inheritance– TCOF1, mapped to 5q32-33.1 60% are from new mutation– Associated with increased paternal age Prevalence of 1 in 50,000 a.k.a. Mandibulofacial dysostosisikassem@dr.com
  • 144. TCS Characteristics– Likely due to abnormal migration of neural crest cells intofirst and second branchial arch structures– Usually bilateral and symmetric– Malar and supraorbital hypoplasia– Non-fused zygomatic arches– Cleft palate in 35%– Hypoplastic paranasal sinuses– Downward slanting palpebral fissures– Mandibular hypoplasia with increased angulation– Coloboma of lower eyelid with absent cilia– Malformed pinna– Normal intelligenceikassem@dr.com
  • 145. TCS OP/Airway concerns– Cleft palate– Choanal atresia may be present Respiratory distress in newborn Oral airway, McGovern nipple– Obstructive sleep apnea is the most commonairway dysfunction Mandibular hypoplasia results in retrodisplacement oftongue into oropharynx Oral airway, tracheotomy Distraction osteogenesis vs. free fibular transferikassem@dr.com
  • 146. TCS Otologic concerns– Malpositioned auricles– Malformed pinna– EAC atresia– Ossicular abnormalities– Conductive hearing loss is common Hearing aids are effective– Normal intelligenceikassem@dr.com
  • 147. TCSikassem@dr.com
  • 148. TCSikassem@dr.com
  • 149. Apert andCrouzonSyndromesikassem@dr.com
  • 150. Apert andCrouzon Belong to family of Craniosynostoses Apert Syndrome (Acrocephalosyndactyly)– First described by Wheaton in 1894– Apert further expanded in 1906 Crouzon Syndrome (Craniofacial Dysostosis)– Described by Crouzon in 1912 Autosomal dominant inheritance– Most are sporadic in Apert Syndrome– 1/3 are sporadic in Crouzon Sydrome Prevalence: 15 - 16 per 1,000,000ikassem@dr.com
  • 151. Apert andCrouzon Typical characteristics– Craniosynostosis Coronal sutures fused at birth Larger than average head circumference atbirth– Midfacial malformation and hypoplasia– Shallow orbits with exophthalmos– Apert Syndrome: symmetric syndactyly ofhands and feetikassem@dr.com
  • 152. Apert andCrouzon Crouzon and Apert Syndromes facialfeatures– Shallow orbits with exophthalmos– Retruded midface with relativeprognathism– Beaked nose– Hypertelorism– Downward slanting palpebral fissuresikassem@dr.com
  • 153. Apert andCrouzon Airway concerns– Reduced nasopharyngeal dimensions and choanalstenosis– OSA– Cor pulmonale Polysomnography Treatment– Adenoidectomy– Endotracheal intubation– Tracheotomyikassem@dr.com
  • 154. Apert andCrouzon Otologic concerns– CHL resulting from ETD– Congenital fixation of stapes footplate in Apert syndrome Treatment– Ventilation tubes– Stapedectomy or OCR Fronto-Orbital advancement– Brain growth and expansion of cranial vault, orbital depth Orthodontics– Maxillary teeth abnormalities– Crossbiteikassem@dr.com
  • 155. Pierre RobinSequenceikassem@dr.com
  • 156. PRS Triad of micrognathia, glossoptosis and cleftpalate– First described by St. Hilaire in 1822– Pierre Robin first recognized the association ofmicrognathia and glossoptosis in 1923 Prevalence: 1 of every 8,500 newborns– Syndromic 80% Treacher Collins Syndrome Velocardiofacial Syndrome Fetal Alcohol Syndrome– Nonsyndromic 20%ikassem@dr.com
  • 157. PRSMandibular DeficiencyHypoplastic andRetruded Mandible(Micrognathia)Tongue RemainsRetruded and High inOropharynx(Glossoptosis)Failure of Fusion ofLateral Palatal ShelvesCleft Palateikassem@dr.com
  • 158. PRS Airway Obstruction– Anatomic and Neuromuscular Components Micrognathia, Retruded Mandible Glossoptosis Impaired Genioglossus and ParapharyngealMusclesikassem@dr.com
  • 159. PRS Airway Management– Temporizing Modalities Prone Positioning Nasopharyngeal Airway– NG tube and gavage feeds Mandibular Traction Devices Tongue Lip Adhesion– Tracheotomy– Distraction Osteogenesisikassem@dr.com
  • 160. My Contact ikassem@dr.com You can ge thelectures form http://www.slideshare.net/islamkassem/newsfeedikassem@dr.com

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