Developmental Disorders

Developmental Disorders Human embryo at 7 weeks Figure from Ten Cate’s Oral Histology, Ed., Antonio Nanci, 6th edition Development of the Face The face begins to develop between the 24th and 38th days of gestation by fusion of various tissue processes Figures obtained from “Before We Were Born; Moore and Persaud, 6th edition, 2003”. Frontonasal process Figures obtained from “Before We Were Born; Moore and Persaud, 6th edition, 2003”. Figures obtained from “Before We Were Born; Moore and Persaud, 6th edition, 2003”. Figures obtained from “Before We Were Born; Moore and Persaud, 6th edition, 2003”. Formation of the Lips Middle portion of the upper lip: Formed by the fusion of the medial nasal process of both sides along with the frontonasal process Lateral portion of the upper lip: Fusion of the maxillary processes of each side and medial nasal process Lower lip: Formed by the fusion of the two mandibular processes Cleft Lip Formation of the palate (weeks 7 to 9) Palate develops from the primary palate and the secondary palate The primary palate develops at about 28 days of gestation Primary palate develops from the frontonasal and medial nasal processes and eventually forms the premaxillary portion of the maxilla The secondary palate develops between 7th and 8th week of gestation and completes in the 3rd month The critical period of palate development is from the end of 6th week till the beginning of 9th week Formation of the secondary palate Figure from Ten Cate’s Oral Histology, Ed., Antonio Nanci, 6th edition Figure from Ten Cate’s Oral Histology, Ed., Antonio Nanci, 6th edition Any defect in the development of these processes or their fusion may result in orofacial clefts Cleft Cleft Cleft lip- 25% palate – 30% lip and palate – 45% CL ± CP are related etiologically and Isolated CP is a separate entity ETIOLOGY of CL ± CP Isolated clefts (non-syndromic): Heterogeneous inheritance Syndrome-associated: 250 developmental syndromes (3% to 8% of total clefts) Single gene mutations; AD, AR or X-linked Chromosomal abnormalities Idiopathic Incidence of Orofacial Clefts Most common congenital abnormality in humans Racial variation of CL ± CP: White – 1 in 700 to 1000 Asian – 1.5 in 700 to 1000 Black – 0.4 per 1000 Native Americans – 3.6 per 1000 Isolated CP is much less common Isolated CL: Males > Females (1.5:1) CL + CP: Males > Females (2:1) Isolated CP: Females > Males 80% of isolated CL: Unilateral (70% occur on left side) Complete CL vs Incomplete CL Variation in CP Hard and soft palate or soft palate alone Most minimal involvement: Bifid Uvula Bifid Uvula: Most common (1 in 80 in Whites; 1 in 10 in Asians and Native Americans; 1 in 250 in Blacks) Submucous palatal cleft: Defect in underlying musculature alone; A notch in bone also noted Pierre Robin Sequence (Pierre Robin Anomalad) 1. Mandibular micrognathia: Prevents descending of the tongue causing CP 2. Cleft palate: Wider and U-shaped than regular CP 3. Glossoptosis: Causing airway obstruction Stigma of Orofacial clefts Clinical appearance: psychological problems Feeding and speech difficulties Malocclusion due to collapse of the maxillary arch Treatment: Multidisciplinary approach Genetic counseling: Risk for cleft development in a sibling or offspring is 3% to 5% Risk increases to 10% to 20% if there is are affected first degree relatives Lateral Facial Cleft: Caused by lack of fusion of the maxillary and mandibular process Isolated or associated with mandibulofacial dysostosis Oblique Facial Cleft: Failure of fusion of lateral nasal process and the maxillary process Extends from upper lip to eye Always associated with CP Median mandibular cleft: Failure of fusion of the mandibular processes Commissural Lip Pits Small mucosal invaginations occurring at the corners of the mouth on the vermillion border Represents failure of normal fusion of the maxillary and mandibular processes 12% to 20% (so common); Autosomal dominant where reported Associated with high incidence of preauricular pits No treatment necessary Paramedian Lip Pits Autosomal dominant Arise from persistent lateral sulci on the embryonic mandibular arch (these should normally disappear by 6 weeks of embryonic age) Van der Woude Syndrome: Paramedian lip pits associated with CL ± CP Double Lip Redundant fold of tissue on the mucosal side of the lip Mostly congenital but also acquired as a result of trauma, oral habits such as sucking on the lip or as part of Ascher syndrome Upper lip > lower lip Ascher syndrome: AD; Double lip; bleparochalasis and nontoxic goiter Fordyce Granules or Disease Sebaceous glands occurring on oral mucosa considered “ectopic” Considered normal variation as reported in >80% of the population Buccal mucosa and vermillion zone of upper lip Occasionally they become hyperplastic or form keratin-filled cysts Leukoedema • • • • • • • Diffuse grayish-white appearance of mucosa Blacks > Whites Variation, not a disease More prominent in smokers Buccal mucosa extending to the lips Thick epithelium; intracellular edema No treatment Amyloidosis Macroglossia Enlargement of the tongue Refer to Box 1-1 in the text book for common causes of macroglossia Congenital or Hereditary: Vascular malformations: Hemangioma, lymphangioma Hemihyperplasia Metabolic diseases: Mucopolysaccharidoses Syndromes: Downs, Beckwith-Wiedemann Acquired: Edentulous patients Amyloidosis Myxedema Acromegaly Tumors Ankyloglossia (Tongue-Tie) Short thick lingual frenum resulting in limitation of tongue movement Speech defects Thyroid gland development (4 to 7 weeks) Figures obtained from “Before We Were Born; Moore and Persaud, 6th edition, 2003” Lingual Thyroid Small remnants of thyroid tissue seen in 10% of populations Actual lingual thyroid less common (Females > Males) Hypothyroidism reported in 30% of cases Rarely carcinomas develop (which is more common in males so prophylactic removal recommended for men > 30 years) Fissured Tongue • • • • • • Grooves and fissures 2% to 5% of population Entire tongue or part Usually asymptomatic Prevalence increases with age Strong association with geographic tongue and MelkerssonRosenthal syndrome • Tongue brushing • Melkersson-Rosenthal syndrome: Fissured tongue Orofacial granulomatosis Facial paralysis Hairy Tongue • • • • • • • Marked hyperkeratinization of filiform papillae Less than 1% Smokers, antibiotics, poor oral hygiene, radiation, general debilitation Staining (bacteria, coffee, tobacco) Asymptomatic Brushing DO NOT USE KERATOLYTIC AGENTS If you do not know how Varicosities • • • • • • • Dilated and tortuous vein Age-related Loss of connective tissue tone No association with hypertension or cardiopulmonary disease Sublingual area Multiple or solitary Phleboliths Exostoses Localized bony protuberances arising from the cortical plate Torus palatinus and Torus mandibularis Buccal exostoses: bilateral row of bony hard nodules along the facial aspect of maxillary and/or mandibular alveolar ridge Palatal exostoses: lingual aspect of tuberosity Solitary exostoses: Trauma; local irritation Reactive subpontine exostoses (subpontic osseous hyperplasia): develop From alveolar crestal bone beneath the pontic of a posterior bridge Radiograph: Radiopacity Histology: Mass of non-neoplastic bone with minimal marrow Treatment for painful/ulcerated cases or if diagnosis is uncertain Subpontic Osseous Hyperplasia Torus Palatinus • • • • • • Midline of palatal vault Multifactorial, genetic predisposition Flat, spindle, nodular, lobular Rarely show on PAs More women than men Surgical excision to accommodate prosthesis Torus Mandibularis • • • • • • • Lingual aspect of mandible Multifactorial Bilateral Single or multiple nodules PAs: Periapical opacities that can be confusing Not as common as torus palatinus Surgical excision to accommodate prosthesis Eagle Syndrome Elongation of the styloid process or mineralization of the stylohyoid process 18% to 40% incidence of the general population Mostly asymptomatic but some experience eagle syndrome caused by compression of the adjacent nerves or blood vessels Vague facial pain while swallowing, turning head or mouth opening Dysphagia, dizziness and transient syncope (fainting) PAN or lateral radiographs CLASSIC EAGLE SYNDROME OCCURS AFTER TONSILLECTOMY following development of scar tissue in the area of the mineralized stylohyoid ligament and cervicopharyngeal pain during swallowing Carotid artery syndrome or stylohyoid syndrome: Elongated mineralized complex impinges on the internal and external carotid artery and associated sympathetic nerves Traumatic eagle syndrome: Symptoms following fracture of the mineralized stylohyoid ligament Treatment: Mild cases: No surgery; corticosteroid injections Severe cases: Surgery Stafne Defect (Static bone cyst/defect) • Radiolucency with sclerotic border • Near angle of mandible (below the canal) Anterior and upper ramus rarely • Usually normal salivary glands Submandibular, sublingual, parotid • Asymptomatic • Striking male predilection • Developmental but not present from birth • Sialogram Hemihyperplasia (Hemihypertrophy) Asymmetric overgrowth of one or more body parts Actually hyperplasia of tissues rather than hypertrophy Complex hemihyperplasia (whole side of the body) Simple hemihyperplasia (single limb) Hemifacial hyperplasia (one side of the face) 2:1 female:male; Right side of the body Enlargement more pronounced at puberty Involves all tissues of affected side including bone UNILATERAL MACROGLOSSIA; INCREASED CROWN OF TEETH Crouzon Syndrome (Craniofacial Dysostosis) Craniosynostosis: Premature closure of sutures Mutation in FGFR2; 1 in 65,000 births; AD Wide variation in clinical presentation: Brachycephaly; scaphocephaly; trigonocephaly; “cloverleaf” skull (kleeblattschädel) Ocular proptosis: blindness and hearing deficit Headaches; normal intelligence Underdeveloped maxilla: Midface hypoplasia; crowding of maxillary teeth; bifid uvula “Beaten metal” skull in radiographs Surgical treatment Aperts Syndrome (Acrocephalosyndactyly) Craniosynostosis syndrome Mutation in FGFR2; 1 in 65,000 to 160,000 births, AD Acrobrachycephaly (tower skull); kleeblattschädel (severe cases) Ocular proptosis; hypertelorism; vision loss; “beaten metal” radiographs Midface hypoplasia; ‘V”-shaped arch “open-mouth” feature; hearing loss SYNDACTYLY of the 2nd, 3rd and 4th digits; MENTAL RETARDATION Pseudo cleft palate due to swellings (accumulation of glycosaminoglycans) of the lateral hard palate and crowding of maxillary teeth; bifid uvula Surgery Treacher-Collins Syndrome (Mandibulofacial Dysostosis) Defects of 1st and 2nd BA AD; 1 in 25,000 to 50,000 births; 60% new mutations Mutations in the TCOF1 gene Characteristic face: Hypoplastic zygoma causing narrow face with depressed cheeks and downward slanting palpebral fissures Coloboma (notch) at the outer portion of lower eyelid Ears anomalies: Deformed pinnae, extra ear tags, middle ear ossicle defects cause hearing loss Underdeveloped mandible; condyle and coronoid hypoplasia Lateral facial clefting and cleft palate No treatment required in most cases; Cosmetic surgery in severe cases Osteogenesis Imperfecta Heterogeneous group of disorders characterized by impairment of collagen maturation Mutations in type I collagen gene Most common type of inherited bone disease Collagen forms a major portion of bone, dentin, sclerae, ligaments, and skin Autosomal dominant, autosomal recessive hereditary; sporadic Severity varies Osteogenesis Imperfecta Weak bones, blue sclera, altered teeth, hearing loss, long bone and spine deformity and joint hyperextension Radiographic features include osteopenia, bowing, deformity of long bones and multiple fractures Oral manifestations are clinically similar to dentinogenesis imperfecta – premature pulpal obliteration Shell teeth can also be noted However the two are different processes caused by different mutations Opalescent teeth if associated with OI Maxillary hypoplasia Osteogenesis Imperfecta Four major types of OI Type Type Type Type I: Most common and mildest form II: Most severe; patients die before 4 weeks of age III: Most severe form beyond the perinatal age IV: Mild to moderate form Treatment: No treatment of OI Varied prognosis Cleidocranial Dysplasia Caused by a defect in Cbfa1/Runx2 gene Autosomal dominant and sporadic pattern Bone defects involve the clavicle and skull Clavicles are absent (unilateral or bilateral) – 10% of cases Short stature with large heads; ocular hypertelorism; broad base of nose and depressed nasal bridge Large heads and parietal bossing Skull sutures show delayed closure and may remain open Dental manifestations include narrow, high-arched palate with increased prevalence of cleft palate Cleidocranial Dysplasia Presence of numerous unerupted permanent and supernumery teeth with many distorted crown and root shapes Prolonged retention of deciduous teeth and delay or complete failure of eruption of permanent teeth Histology: Unerupted permanent teeth lack secondary cementum Treatment: No treatment; full-mouth extractions with denture construction; removal of primary and supernumery teeth followed by exposure and orthodontic treatment of permanent teeth Osteopetrosis Marked increase in bone density due to defect in osteoclast function- bone resorption along with continued bone formation Infantile and Adult forms Infantile: Severe disease-malignant osteopetrosis; AR Anemia, infections, delayed tooth eruption, narrowing of skull foramina Fractures and osteomyelitis following tooth extraction Adult: Less severe; AD; benign-osteopetrosis Frequently diagnosed on routine X-rays; bone pain Cranial nerve compression and fractures Histology: Osteoclasts and bone Adult form: less severe Infant form: Bone marrow transplantation