2Outline Embryonic Development of the Face, Oral Cavity, and Teeth Developmental Soft Tissue AbnormalitiesDevelopmental CystsDevelopmental Abnormalities of Teeth
3Developmental Disorders (pg. 156)A failure during the process of cell division and differentiation into various tissues and structuresSome may be identified clinically, by radiographic examination, biopsy, or histologic examination.
4Developmental Disorders (cont.) (pg. 156)Inherited disorderCaused by an abnormality in genetic makeupCongenital disorderPresent at birthMay be inherited or developmentalThe cause of most congenital abnormalities is unknown.
5Embryonic Development of the Face, Oral Cavity, and Teeth Oral and Nasal CavitiesTeeth
6Face(pgs )During the third week, ectoderm infolds to form the stomodeum, the primitive oral cavity.The frontal process is above and the first branchial arch is below.The first branchial arch divides into two maxillary processes and the mandibular process.
8Face (cont.) Two pits develop on the frontal process. They divide the frontal process into three parts.The median nasal processThe right lateral nasal processThe left lateral nasal processThe median nasal process grows downward between the maxillary processes to form the globular process.This will form the philtrum.
9Oral and Nasal Cavities (pg. 157)PremaxillaForms from the globular processLateral palatine processesForm from the maxillary processThe lateral palatine processes fuse with the premaxilla, creating a Y-shaped pattern.The body of the tongue develops from the first branchial arch.The base of the tongue forms from the second and third branchial arches.
10Teeth Odontogenesis (pgs. 157-158) Takes place in about the fifth week of lifeInvolves ectoderm and ectomesenchymeBegins with formation of a band of ectoderm in each jaw called the primary dental laminaTen small knoblike proliferations develop on the primary dental lamina in each jaw.Each extends into underlying mesenchyme.
12Teeth (cont.) The tooth germ has three parts. The enamel organ Produces enamelThe dental papillaForms the dental pulpThe dental sac or follicleThe follicle provides cells that form cementum, the periodontal ligament, and alveolar bone.Cementum is formed after the crown is complete.
14Ankyloglossia(pg. 158)An extensive adhesion of the tongue to the floor of the mouthDue to the complete or partial fusion of the lingual frenumSome patients may have no adverse effects, while others may have difficulty with speech.It may just involve mucosa, or it may be muscular and thick.TreatmentFrenectomyThis works nicely with a laser.
16Commissural Lip Pits(pgs )Epithelium-lined blind tracts located at the corners of the mouth (commissure)May be shallow or several millimeters deep.Congenital lip pits may also be observed near the midline of the vermilion border.TreatmentNone
18Lingual Thyroid A small mass of thyroid tissue located on the tongue (pg. 159)A small mass of thyroid tissue located on the tongueResults from the failure of the primitive thyroid tissue to migrate from its developmental location in the area of foramen cecum on the posterior portion of the tongue to its normal position in the neck
19Lingual Thyroid (cont.) Appears as a smooth nodular mass posterior to circumvallate papillae at the base of the tongue.TreatmentSIt may be removed if it is obstructive, providing the patient has other functioning thyroid tissue.
21Developmental Cysts (cont.) (pg. 159) (Box 5-1)An abnormal fluid-filled epithelium-lined sac or cavityFound throughout the body, including the head and neck region
22Developmental Cysts (cont.) Developmental cysts are classified as to whether they are odontogenic or nonodontogenic.They are also classified according to location, cause, origin of the epithelial cells, and histologic appearance.
23Developmental Cysts (cont.) They can cause expansion of bone.Intraosseous cystsOccur within boneExtraosseous cystsOccur in soft tissueCysts within bone generally appear as well-circumscribed radiolucencies.They may appear as unilocular or multilocular.
25Dentigerous Cyst (Follicular Cyst) (pgs )Forms around the crown of an unerupted or developing toothThe epithelial lining originates from the reduced enamel epithelium after the crown has formed and calcified.Most commonly around the crown of an unerupted or impacted third molar
27Dentigerous Cyst Radiographic Histologic Treatment (pgs. 160-161) A well-defined, unilocular radiolucency around the crown of an unerupted or impacted toothHistologicThe lumen is most characteristically lined with cuboidal epithelium surrounded by a wall of connective tissue.TreatmentRemoval of the cystThere is some risk of cystic transformation into a neoplasm.
32Primordial Cyst (cont.) HistologicThe lumen is lined by stratified squamous epithelium surrounded by parallel bundles of collagen fibers.It may prove to be an odontogenic keratocyst or a lateral periodontal cyst.TreatmentSurgical removalThe risk of recurrence depends on the diagnosis.
33Odontogenic Keratocyst (OKC) (pgs )Characterized by histologic appearance and frequent recurrenceThe lumen of the cyst contains perakeratin.Most often seen in the mandibular third molar regionCan move teeth and cause resorption
34Odontogenic Keratocyst (pgs )HistologicThe lumen is lined by epithelium that is 8 to 10 cell layers thick and surfaced by parakeratin.RadiographicFrequently appears as a well-defined, multilocular, radiolucent lesion
35Odontogenic Keratocyst (cont.) (pgs )TreatmentDue to a high recurrence rate, surgical excision and osseous curettage are recommended.
36Calcifying Odontogenic Cyst (COC) (pg. 163)A nonaggressive, cystic lesion lined by odontogenic epitheliumClosely resembles an ameloblastomaHas a characteristic feature called ghost cells
37Lateral Periodontal Cyst and Gingival Cyst (pgs )Most often seen in the mandibular cuspid and premolar areaAn asymptomatic, unilocular or multilocular radiolucent lesion on the lateral surface of a tooth rootFound most often in males
38Lateral Periodontal Cyst and Gingival Cyst (cont.) (pgs )HistologicA gingival cyst has the same type of lining, but is located in the soft tissue.A thin band of stratified squamous epithelium lines the cystTreatmentSurgical excision
39Lateral Periodontal Cyst and Gingival Cyst (cont.)
41Nasopalatine Canal Cyst (Incisive Canal Cyst) (pg. 164)Located within the nasopalatine canal or the incisive papillaMost commonly seen in men between 40 and 60 years oldUsually asymptomaticMay see a small, pink bulge near the apices and between the roots of the maxillary central incisors on the lingual surface
42Nasopalatine Canal Cyst (pg. 164)RadiographicA well-defined, radiolucent lesionMay be oval or heart-shapedHistologicLined by epithelium varying from stratified squamous to pseudostratified ciliated columnar epitheliumTreatmentSurgical excision
44Median Palatine Cyst A well-defined, unilocular radiolucency (pgs )A well-defined, unilocular radiolucencyLocated in the midline of the hard palateHistologicLined with stratified, squamous epithelium surrounded by dense fibrous connective tissueTreatmentSurgical removal
46Globulomaxillary Cyst (pg. 165)A well-defined, pear-shaped radiolucency found between the roots of the maxillary lateral incisor and cuspidWas once thought to be a fissural cyst, now believed to be of odontogenic epithelial originTreatmentSurgical removal
48Median Mandibular Cyst (pg. 165)A rare lesion located in the midline of the mandibleLined with squamous epitheliumRadiographicA well-defined radiolucency below the apices of mandibular incisorsTreatmentSurgical removal
49Nasolabial Cyst A soft tissue cyst (pgs. 165-166) Thought to originate from the lower anterior portion of the nasolacrimal ductObserved in adults from 40 to 50 years of age4:1 ratio in favor of females
50Nasolabial Cyst (cont.) (pgs )ClinicalAn expansion or swelling in the mucobuccal fold in the area of the maxillary canine and the floor of the noseHistologicLined with pseudostratified, ciliated columnar epithelium and multiple goblet cellsTreatmentSurgical excisions
52Branchial Cleft Cyst (Lymphoepithelial Cyst) (pgs )Most commonly found in major salivary glandsA stratified squamous epithelial lining surrounded by a well-circumscribed component of lymphoid tissueAppears to arise from epithelium trapped in a lymph node during development
54Branchial Cleft Cyst (Lymphoepithelial Cyst) (cont.) Most commonly found intraorally on the floor of the mouth and the lateral borders of the tongueAppears as a pinkish, yellow raised noduleTreatmentSurgical excision
55Epidermal Cyst Treatment (pg. 166)A raised nodule on the skin of the face or neckMay be noted intraorally on occasionHistologicLined by keratinizing epithelium the resembles the epithelium of the skinThe lumen is usually filled with keratin scalesTreatmentSurgical excision
56Dermoid Cyst and Benign Cystic Teratoma (pg. 166)A developmental cyst often present at birth or noted in young childrenIt is usually found on the floor of the mouth when it is located in the oral cavity.May have a doughy consistency when palpated
57Dermoid Cyst Histologic Treatment Lined by orthokeratinized, stratified squamous epithelium surrounded by a connective tissue wallThe lumen is usually filled with keratinHair follicles, sebaceous glands, and sweat glands may be seen in the cyst wallBenign cystic teratomaResembles a dermoid cystTreatmentSurgical excision
58Thyroglossal Tract Cyst (pgs )Forms along the tract the thyroid gland follows in developmentMost often found in young individuals under 20 years of ageNo sex predilectionTreatmentExcision of the cyst and tract
60PseudocystsStatic Bone CystSimple Bone CystAneurysmal Bone Cyst
61Static Bone Cyst (Lingual Mandibular Bone Cavity) (Stafne Bone Cyst) (pgs. 166, 168)A pseudocyst (not a true cyst)A well-defined cystlike radiolucency may be observed on radiograph in the posterior region of the mandible inferior to the mandibular canal.Caused by a lingual depression in the mandibleTreatmentNone
62Static Bone Cyst (Lingual Mandibular Bone Cavity) (Stafne Bone Cyst) (cont.)
63Simple Bone Cyst (Traumatic Bone Cyst) (pg. 168)A pathologic cavity in bone that is not lined with epitheliumMay be associated with traumaRadiographicA well-defined unilocular or multilocular radiolucencyCharacteristically shows scalloping around roots of teethTreatmentCurettage on the wall lining the void
65Aneurysmal Bone Cyst A pseudocyst (pg. 168) Consists of blood filled spaces surrounded by multinucleated giant cells and fibrous connective tissue
66Aneurysmal Bone Cyst (cont.) RadiographicMultilocular appearance “honeycomb,” “soap bubble”Usually seen in persons less than 30 years oldSlight predilection for femalesTreatmentSurgical excision
67Developmental Abnormalities of Teeth Abnormalities in the Number of TeethAbnormalities in the Size of TeethAbnormalities in the Shape of TeethAbnormalities of Tooth StructureAbnormalities of Tooth Eruption
68Abnormalities in the Number of Teeth AnodontiaHypodontiaSupernumerary Teeth
69Anodontia The congenital lack of teeth (pgs. 168-169) Total anodontia is lack of all teeth.May be associated with ectodermal dysplasia
70Hypodontia The lack of one or more teeth (pg. 169)The lack of one or more teethMay affect either deciduous or permanent teethThe most common missing permanent teeth areMandibular and maxillary third molarsMaxillary lateral incisorsMandibular second premolarsThe most common missing deciduous tooth is the mandibular incisor.
72Hypodontia (cont.) Treatment Usually identified during clinical and radiographic examinationTends to be familialTreatmentMay require prosthetic replacementOrthodontic evaluation and treatment may be necessaryMay be a component of a syndrome
73Supernumerary Teeth Extra teeth found in the dental arches (pgs )Extra teeth found in the dental archesMay result from formation of extra tooth buds in the dental lamina or from the cleavage of already existing tooth budsMay occur in either deciduous or permanent dentitionMost often seen in the maxillaMost are found on radiographs
75Supernumerary Teeth (cont.) (pgs. 169, )MesiodensThe most common supernumerary toothLocated between maxillary incisorsMay be inverted when seen on radiographsDistomolarThe second most common supernumerary toothLocated distal to the third molar
77Supernumerary Teeth (cont.) TreatmentErupted teeth may require removal if they cause crowding, malposition of adjacent teeth, or noneruption of normal teeth.Nonerupted teeth “should be extracted because a risk exists for cyst development around the crown.”Multiple supernumerary teeth may be associated with cleidocranial dysplasia or Gardner syndrome.
78Abnormalities in the Size of Teeths MicrodontiaMacrodontia
79Microdontia One or more teeth are smaller than normal. (pgs. 170, 172) (Fig. 5-24)One or more teeth are smaller than normal.True generalized microdontiaSeen in a pituitary dwarf; all teeth are smaller than normalGeneralized relative microdontiaNormal-sized teeth appear small in a large jaw.Microdontia involving a single toothMaxillary lateral incisor and maxillary third molar are the most commonly involved teeth.
81Macrodontia One or more teeth are larger than normal. (pg. 170) True generalized macrodontiaSeen in cases of pituitary giantismRelative generalized macrodontiaLarge teeth in a small jawMacrodontia affecting a single toothMay be seen in cases of facial hemihypertrophy
82Abnormalities in the Shape of Teeths GeminationFusionConcrescenceDilacerationEnamel PearlTalon CuspTaurodontismDens in DenteDens EvaginatusSupernumerary Rootsss
83Gemination Occurs when a single tooth germ attempts to divide in two (pgs , 173)Occurs when a single tooth germ attempts to divide in twoAppears as two crowns joined together by a notched incisal areaRadiographically, usually one single root and one common pulp canal existThe patient has a full complement of teeth.
85Fusion The union of two normally separate adjacent tooth germs (pgs )The union of two normally separate adjacent tooth germsAppears as a single large crown that occurs in place of two normal teethRadiographically, either separate or fused roots and root canals are seen.The patient is usually short one tooth.
87Concrescences Two adjacent teeth are united by cementum. (pgs. 172, 174)Two adjacent teeth are united by cementum.Usually discovered on radiographIf one of the teeth needs to be removed, both usually come out (two for the price of one).
89Dilaceration An abnormal curve or bend in the root of a tooth (pgs. 172, )An abnormal curve or bend in the root of a toothUsually discovered on radiographMay cause a problem if the tooth must be removed or a root canal performed
91Enamel Pearl A small, spherical enamel projection on a root surface (pgs. 174, 176)A small, spherical enamel projection on a root surfaceUsually found on maxillary molarsRadiographically, it appears as a small, spherical radiopacity.Difficult to instrument with curettes or scalersRemoval may be necessary if periodontal problems occur in the furcation.
95Taurodontism The teeth have elongated pulp chambers and short roots. (pgs. 174, 176)The teeth have elongated pulp chambers and short roots.May occur in both deciduous and permanent dentitionIdentified on radiographs
97Dens in Dente(pgs. 175, 177)Occurs when the enamel organ invaginates into the crown of a tooth before mineralizationRadiographically, it appears as a toothlike structure within a tooth.Vulnerable to caries, pulpal infection, and necrosisA restoration can be placed in the pit if the tooth is vital.
101Supernumerary Roots May involve any tooth (pgs. 176-177) Most commonly, maxillary and mandibular third molars if multirooted teeth are involved.May become clinically significant if removal or endodontia is necessary
103Abnormalities of Tooth Structure Enamel HypoplasiaEnamel HypocalcificationEndogenous Staining of TeethRegional Odontodysplasia
104Enamel Hypoplasia The incomplete or defective formation of enamel (pgs )The incomplete or defective formation of enamelCan affect either deciduous or permanent dentitionMay be due to many factorsAmelogenesis imperfectaFebrile illness (measles, chickenpox, scarlet fever)Vitamin deficiencyInfection of a deciduous toothIngestion of fluorideCongenital syphilisBirth injury, premature birthIdiopathic factors
105Enamel Hypoplasia Caused by Febrile Illness or Vitamin Deficiency (pgs )Ameloblasts are one of the most sensitive cell groups in the body.Any serious systemic disease or severe nutritional deficiency can produce enamel hypoplasia.One or more horizontal rows of tiny, deep pits are seen traversing the affected tooth surface.
106Enamel Hypoplasia Caused by Febrile Illness or Vitamin Deficiency (cont.)
107Enamel Hypoplasia Resulting from Local Infection or Trauma (pg. 178)Enamel hypoplasia of an adult tooth may result from infection of a deciduous tooth.A single tooth is usually affected; it is referred to as a Turner tooth.The color of the enamel may range from yellow to brown, or severe pitting and deformity may be involved.
108Enamel Hypoplasia Resulting from Fluoride Ingestion (pg. 178)Affected teeth exhibit a mottled discoloration of enamel.Ingestion of water with 2 to 3 times the recommended amount leads to white flecks and chalky opaque areas of enamel.Four times the recommended amount of fluoride causes brown or black staining.
109Enamel Hypoplasia Resulting from Fluoride Ingestion (cont.)
110Enamel Hypoplasia Resulting from Congenital Syphilis (pgs )Congenital syphilis is transmitted from an infected mother to her fetus via the placenta.This may result in enamel hypoplasia of adult incisors and first molars.Hutchinson incisors are shaped like screwdrivers.Mulberry molars have a berrylike appearance.
111Enamel Hypoplasia Resulting from Congenital Syphilis (cont.)
112Enamel Hypoplasia Resulting from Birth Injury, Premature Birth, or Idiopathic Factors (pg. 179)Enamel hypoplasia may occur due to trauma or injury at the time of birth.Even a mild illness or systemic problem can result in enamel hypoplasia.
113Enamel Hypocalcification (pg. 179)A developmental anomaly resulting in a disturbance or the maturation of the enamel matrixUsually appears as a chalky, white spot on the middle third of smooth crownsThe underlying enamel may be soft and susceptible to caries.
114Endogenous Staining of Teeth (pg. 179)The result of deposition of substances circulating systemically during tooth developmentMay be due toTetracycline stainErythroblastosis fetalis – Rh incompatibilityNeonatal liver diseaseCongenital porphyria – an inherited metabolic disease
115Regional Odontodysplasia (Ghost Teeth) (pgs )One or several teeth in the same quadrant exhibit a marked reduction in radiodensity and a characteristic ghostlike appearance.Very thin enamel and dentin are presentMay affect primary or adult dentitionUsually treated by extraction
117Abnormalities of Tooth Eruption (pgs )Impacted and embedded teethImpacted teeth cannot erupt due to an obstruction.Embedded teeth do not erupt due to lack of eruptive force.Ankylosed teeth
118Impacted and Embedded Teeth (pg. 180)Any tooth can be impacted.Third molar impactions are classified according to the position of the tooth.Teeth can be completely impacted in bone or they may be partially impacted.Partially impacted teeth are prone to infection.
120Impacted and Embedded Teeth (cont.) Impacted teeth may be surgically removed to prevent odontogenic cyst and tumor formation or damage to adjacent teeth.Partially impacted third molar teeth are removed to prevent infections.The optimal time is between 12 and 24 years of age.
121Ankylosed Teeth Tooth cementum fused to bone (pgs. 180-181) Prevents exfoliation of the deciduous tooth and eruption of the underlying adult toothThe ankylosed deciduous tooth appears submerged and has a different sound when percussed (kind of a dull thud).
123Ankylosed Teeth (cont.) The periodontal ligament space is lacking.Difficult to extractRemoval of deciduous teeth is necessary for eruption of the adult successor.Removal of adult teeth may be necessary to prevent malocclusion, caries, and periodontal disease.
124Discussion QuestionsWhat developmental soft tissue abnormalities may be observed within the oral cavity?What developmental cysts may be observed within the oral cavity?What developmental abnormalities of teeth may be observed within the oral cavity?