Developmental Disorders Chapter 5 Developmental Disorders

Outline Embryonic Development of the Face, Oral Cavity, and Teeth Developmental Soft Tissue Abnormalities Developmental Cysts Developmental Abnormalities of Teeth

Developmental Disorders (pg. 156) A failure during the process of cell division and differentiation into various tissues and structures Some may be identified clinically, by radiographic examination, biopsy, or histologic examination.

Developmental Disorders (cont.) (pg. 156) Inherited disorder Caused by an abnormality in genetic makeup Congenital disorder Present at birth May be inherited or developmental The cause of most congenital abnormalities is unknown.

Embryonic Development of the Face, Oral Cavity, and Teeth Oral and Nasal Cavities Teeth

Face (pgs. 156-157) 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.

Face (cont.)

Face (cont.) Two pits develop on the frontal process. They divide the frontal process into three parts. The median nasal process The right lateral nasal process The left lateral nasal process The median nasal process grows downward between the maxillary processes to form the globular process. This will form the philtrum.

Oral and Nasal Cavities (pg. 157) Premaxilla Forms from the globular process Lateral palatine processes Form from the maxillary process The 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.

Teeth Odontogenesis (pgs. 157-158) Takes place in about the fifth week of life Involves ectoderm and ectomesenchyme Begins with formation of a band of ectoderm in each jaw called the primary dental lamina Ten small knoblike proliferations develop on the primary dental lamina in each jaw. Each extends into underlying mesenchyme.

Teeth (cont.)

Teeth (cont.) The tooth germ has three parts. The enamel organ Produces enamel The dental papilla Forms the dental pulp The dental sac or follicle The follicle provides cells that form cementum, the periodontal ligament, and alveolar bone. Cementum is formed after the crown is complete.

Developmental Soft Tissue Abnormalities (pgs. 158-159) Ankyloglossia Commissural Lip Pits Lingual Thyroid

Ankyloglossia (pg. 158) An extensive adhesion of the tongue to the floor of the mouth Due to the complete or partial fusion of the lingual frenum Some 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. Treatment Frenectomy This works nicely with a laser.

Ankyloglossia (cont.)

Commissural Lip Pits (pgs. 158-159) 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. Treatment None

Commissural Lip Pits (cont.)

Lingual Thyroid A small mass of thyroid tissue located on the tongue (pg. 159) A small mass of thyroid tissue located on the tongue Results 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

Lingual Thyroid (cont.) Appears as a smooth nodular mass posterior to circumvallate papillae at the base of the tongue. TreatmentS It may be removed if it is obstructive, providing the patient has other functioning thyroid tissue.

Developmental Cysts Odontogenic Cysts NonodontogenicS Cysts Pseudocysts

Developmental Cysts (cont.) (pg. 159) (Box 5-1) An abnormal fluid-filled epithelium-lined sac or cavity Found throughout the body, including the head and neck region

Developmental 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.

Developmental Cysts (cont.) They can cause expansion of bone. Intraosseous cysts Occur within bone Extraosseous cysts Occur in soft tissue Cysts within bone generally appear as well-circumscribed radiolucencies. They may appear as unilocular or multilocular.

Odontogenic Cysts Dentigerous Cyst Eruption Cyst Primordial Cyst Odontogenic Keratocyst Calcifying Odontogenic Cyst Lateral Periodontal Cyst and Gingival Cyst

Dentigerous Cyst (Follicular Cyst) (pgs. 159-160) Forms around the crown of an unerupted or developing tooth The 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

Dentigerous Cyst (Follicular Cyst) (cont.)

Dentigerous Cyst Radiographic Histologic Treatment (pgs. 160-161) A well-defined, unilocular radiolucency around the crown of an unerupted or impacted tooth Histologic The lumen is most characteristically lined with cuboidal epithelium surrounded by a wall of connective tissue. Treatment Removal of the cyst There is some risk of cystic transformation into a neoplasm.

Dentigerous Cyst (cont.)

Eruption Cyst Similar to a dentigerous cyst Treatment (pg. 160) Found in the soft tissue around the crown of an erupting tooth Treatment None

Primordial Cyst Develops in the place of a tooth (pgs. 160-161) Most commonly in place of a third molar Most often seen in young adults and discovered on radiographic examination

Primordial Cyst

Primordial Cyst (cont.) Histologic The 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. Treatment Surgical removal The risk of recurrence depends on the diagnosis.

Odontogenic Keratocyst (OKC) (pgs. 161-163) Characterized by histologic appearance and frequent recurrence The lumen of the cyst contains perakeratin. Most often seen in the mandibular third molar region Can move teeth and cause resorption

Odontogenic Keratocyst (pgs. 161-162) Histologic The lumen is lined by epithelium that is 8 to 10 cell layers thick and surfaced by parakeratin. Radiographic Frequently appears as a well-defined, multilocular, radiolucent lesion

Odontogenic Keratocyst (cont.) (pgs. 161-162) Treatment Due to a high recurrence rate, surgical excision and osseous curettage are recommended.

Calcifying Odontogenic Cyst (COC) (pg. 163) A nonaggressive, cystic lesion lined by odontogenic epithelium Closely resembles an ameloblastoma Has a characteristic feature called ghost cells

Lateral Periodontal Cyst and Gingival Cyst (pgs. 163-164) Most often seen in the mandibular cuspid and premolar area An asymptomatic, unilocular or multilocular radiolucent lesion on the lateral surface of a tooth root Found most often in males

Lateral Periodontal Cyst and Gingival Cyst (cont.) (pgs. 163-164) Histologic A gingival cyst has the same type of lining, but is located in the soft tissue. A thin band of stratified squamous epithelium lines the cyst Treatment Surgical excision

Lateral Periodontal Cyst and Gingival Cyst (cont.)

Nonodontogenic Cysts Nasopalatine Canal Cyst Median Palatine Cyst Globulomaxillary Cyst Median Mandibular Cyst Nasolabial Cyst Branchial Cleft Cyst (Lymphoepithelial Cyst) Epidermal Cyst Dermoid Cyst and Benign Cystic Teratoma Thyroglossal Tract Cyst

Nasopalatine Canal Cyst (Incisive Canal Cyst) (pg. 164) Located within the nasopalatine canal or the incisive papilla Most commonly seen in men between 40 and 60 years old Usually asymptomatic May see a small, pink bulge near the apices and between the roots of the maxillary central incisors on the lingual surface

Nasopalatine Canal Cyst (pg. 164) Radiographic A well-defined, radiolucent lesion May be oval or heart-shaped Histologic Lined by epithelium varying from stratified squamous to pseudostratified ciliated columnar epithelium Treatment Surgical excision

Nasopalatine Canal Cyst (cont.)

Median Palatine Cyst A well-defined, unilocular radiolucency (pgs. 164-165) A well-defined, unilocular radiolucency Located in the midline of the hard palate Histologic Lined with stratified, squamous epithelium surrounded by dense fibrous connective tissue Treatment Surgical removal

Median Palatine Cyst (cont.)

Globulomaxillary Cyst (pg. 165) A well-defined, pear-shaped radiolucency found between the roots of the maxillary lateral incisor and cuspid Was once thought to be a fissural cyst, now believed to be of odontogenic epithelial origin Treatment Surgical removal

Globulomaxillary Cyst (cont.)

Median Mandibular Cyst (pg. 165) A rare lesion located in the midline of the mandible Lined with squamous epithelium Radiographic A well-defined radiolucency below the apices of mandibular incisors Treatment Surgical removal

Nasolabial Cyst A soft tissue cyst (pgs. 165-166) Thought to originate from the lower anterior portion of the nasolacrimal duct Observed in adults from 40 to 50 years of age 4:1 ratio in favor of females

Nasolabial Cyst (cont.) (pgs. 165-166) Clinical An expansion or swelling in the mucobuccal fold in the area of the maxillary canine and the floor of the nose Histologic Lined with pseudostratified, ciliated columnar epithelium and multiple goblet cells Treatment Surgical excisions

Nasolabial Cyst (cont.)

Branchial Cleft Cyst (Lymphoepithelial Cyst) (pgs. 165-166) Most commonly found in major salivary glands A stratified squamous epithelial lining surrounded by a well-circumscribed component of lymphoid tissue Appears to arise from epithelium trapped in a lymph node during development

Branchial Cleft Cyst (Lymphoepithelial Cyst) (cont.)

Branchial Cleft Cyst (Lymphoepithelial Cyst) (cont.) Most commonly found intraorally on the floor of the mouth and the lateral borders of the tongue Appears as a pinkish, yellow raised nodule Treatment Surgical excision

Epidermal Cyst Treatment (pg. 166) A raised nodule on the skin of the face or neck May be noted intraorally on occasion Histologic Lined by keratinizing epithelium the resembles the epithelium of the skin The lumen is usually filled with keratin scales Treatment Surgical excision

Dermoid Cyst and Benign Cystic Teratoma (pg. 166) A developmental cyst often present at birth or noted in young children It is usually found on the floor of the mouth when it is located in the oral cavity. May have a doughy consistency when palpated

Dermoid Cyst Histologic Treatment Lined by orthokeratinized, stratified squamous epithelium surrounded by a connective tissue wall The lumen is usually filled with keratin Hair follicles, sebaceous glands, and sweat glands may be seen in the cyst wall Benign cystic teratoma Resembles a dermoid cyst Treatment Surgical excision

Thyroglossal Tract Cyst (pgs. 166-167) Forms along the tract the thyroid gland follows in development Most often found in young individuals under 20 years of age No sex predilection Treatment Excision of the cyst and tract

Thyroglossal Tract Cyst (cont.)

Pseudocysts Static Bone Cyst Simple Bone Cyst Aneurysmal Bone Cyst

Static 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 mandible Treatment None

Static Bone Cyst (Lingual Mandibular Bone Cavity) (Stafne Bone Cyst) (cont.)

Simple Bone Cyst (Traumatic Bone Cyst) (pg. 168) A pathologic cavity in bone that is not lined with epithelium May be associated with trauma Radiographic A well-defined unilocular or multilocular radiolucency Characteristically shows scalloping around roots of teeth Treatment Curettage on the wall lining the void

Simple Bone Cyst (Traumatic Bone Cyst) (cont.)

Aneurysmal Bone Cyst A pseudocyst (pg. 168) Consists of blood filled spaces surrounded by multinucleated giant cells and fibrous connective tissue

Aneurysmal Bone Cyst (cont.) Radiographic Multilocular appearance “honeycomb,” “soap bubble” Usually seen in persons less than 30 years old Slight predilection for females Treatment Surgical excision

Developmental Abnormalities of Teeth Abnormalities in the Number of Teeth Abnormalities in the Size of Teeth Abnormalities in the Shape of Teeth Abnormalities of Tooth Structure Abnormalities of Tooth Eruption

Abnormalities in the Number of Teeth Anodontia Hypodontia Supernumerary Teeth

Anodontia The congenital lack of teeth (pgs. 168-169) Total anodontia is lack of all teeth. May be associated with ectodermal dysplasia

Hypodontia The lack of one or more teeth (pg. 169) The lack of one or more teeth May affect either deciduous or permanent teeth The most common missing permanent teeth are Mandibular and maxillary third molars Maxillary lateral incisors Mandibular second premolars The most common missing deciduous tooth is the mandibular incisor.

Hypodontia (cont.)

Hypodontia (cont.) Treatment Usually identified during clinical and radiographic examination Tends to be familial Treatment May require prosthetic replacement Orthodontic evaluation and treatment may be necessary May be a component of a syndrome

Supernumerary Teeth Extra teeth found in the dental arches (pgs. 169-170) Extra teeth found in the dental arches May result from formation of extra tooth buds in the dental lamina or from the cleavage of already existing tooth buds May occur in either deciduous or permanent dentition Most often seen in the maxilla Most are found on radiographs

Supernumerary Teeth (cont.)

Supernumerary Teeth (cont.) (pgs. 169, 171-172) Mesiodens The most common supernumerary tooth Located between maxillary incisors May be inverted when seen on radiographs Distomolar The second most common supernumerary tooth Located distal to the third molar

Supernumerary Teeth (cont.)

Supernumerary Teeth (cont.) Treatment Erupted 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.

Abnormalities in the Size of Teeths Microdontia Macrodontia

Microdontia One or more teeth are smaller than normal. (pgs. 170, 172) (Fig. 5-24) One or more teeth are smaller than normal. True generalized microdontia Seen in a pituitary dwarf; all teeth are smaller than normal Generalized relative microdontia Normal-sized teeth appear small in a large jaw. Microdontia involving a single tooth Maxillary lateral incisor and maxillary third molar are the most commonly involved teeth.

Microdontia (Cont.)

Macrodontia One or more teeth are larger than normal. (pg. 170) True generalized macrodontia Seen in cases of pituitary giantism Relative generalized macrodontia Large teeth in a small jaw Macrodontia affecting a single tooth May be seen in cases of facial hemihypertrophy

Abnormalities in the Shape of Teeths Gemination Fusion Concrescence Dilaceration Enamel Pearl Talon Cusp Taurodontism Dens in Dente Dens Evaginatus Supernumerary Rootsss

Gemination Occurs when a single tooth germ attempts to divide in two (pgs. 170-171, 173) Occurs when a single tooth germ attempts to divide in two Appears as two crowns joined together by a notched incisal area Radiographically, usually one single root and one common pulp canal exist The patient has a full complement of teeth.

Gemination (cont.)

Fusion The union of two normally separate adjacent tooth germs (pgs. 171-173) The union of two normally separate adjacent tooth germs Appears as a single large crown that occurs in place of two normal teeth Radiographically, either separate or fused roots and root canals are seen. The patient is usually short one tooth.

Fusion (cont.)

Concrescences Two adjacent teeth are united by cementum. (pgs. 172, 174) Two adjacent teeth are united by cementum. Usually discovered on radiograph If one of the teeth needs to be removed, both usually come out (two for the price of one).

Concrescences (cont.)

Dilaceration An abnormal curve or bend in the root of a tooth (pgs. 172, 174-175) An abnormal curve or bend in the root of a tooth Usually discovered on radiograph May cause a problem if the tooth must be removed or a root canal performed

Dilaceration (cont.)

Enamel Pearl A small, spherical enamel projection on a root surface (pgs. 174, 176) A small, spherical enamel projection on a root surface Usually found on maxillary molars Radiographically, it appears as a small, spherical radiopacity. Difficult to instrument with curettes or scalers Removal may be necessary if periodontal problems occur in the furcation.

Enamel Pearl (cont.)

Talon Cusp (pgs. 174, 176) An accessory cusp located in the cingulum area of a maxillary or mandibular permanent incisor Contains a pulp horn May interfere with occlusion

Talon Cusp (cont.)

Taurodontism 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 dentition Identified on radiographs

Taurodontism (cont.)

Dens in Dente (pgs. 175, 177) Occurs when the enamel organ invaginates into the crown of a tooth before mineralization Radiographically, it appears as a toothlike structure within a tooth. Vulnerable to caries, pulpal infection, and necrosis A restoration can be placed in the pit if the tooth is vital.

Dens in Dente (cont.)

Dens Evaginatus (pgs. 176-177) An accessory enamel cusp found on the occlusal tooth surface Most often seen on mandibular premolars May cause occlusal problems

Dens Evaginatus (cont.)

Supernumerary 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

Supernumerary Roots

Abnormalities of Tooth Structure Enamel Hypoplasia Enamel Hypocalcification Endogenous Staining of Teeth Regional Odontodysplasia

Enamel Hypoplasia The incomplete or defective formation of enamel (pgs. 177-179) The incomplete or defective formation of enamel Can affect either deciduous or permanent dentition May be due to many factors Amelogenesis imperfecta Febrile illness (measles, chickenpox, scarlet fever) Vitamin deficiency Infection of a deciduous tooth Ingestion of fluoride Congenital syphilis Birth injury, premature birth Idiopathic factors

Enamel Hypoplasia Caused by Febrile Illness or Vitamin Deficiency (pgs. 177-178) 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.

Enamel Hypoplasia Caused by Febrile Illness or Vitamin Deficiency (cont.)

Enamel 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.

Enamel 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.

Enamel Hypoplasia Resulting from Fluoride Ingestion (cont.)

Enamel Hypoplasia Resulting from Congenital Syphilis (pgs. 178-179) 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.

Enamel Hypoplasia Resulting from Congenital Syphilis (cont.)

Enamel 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.

Enamel Hypocalcification (pg. 179) A developmental anomaly resulting in a disturbance or the maturation of the enamel matrix Usually appears as a chalky, white spot on the middle third of smooth crowns The underlying enamel may be soft and susceptible to caries.

Endogenous Staining of Teeth (pg. 179) The result of deposition of substances circulating systemically during tooth development May be due to Tetracycline stain Erythroblastosis fetalis – Rh incompatibility Neonatal liver disease Congenital porphyria – an inherited metabolic disease

Regional Odontodysplasia (Ghost Teeth) (pgs. 179-180) 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 present May affect primary or adult dentition Usually treated by extraction

Regional Odontodysplasia (Ghost Teeth) (cont.)

Abnormalities of Tooth Eruption (pgs. 180-181) Impacted and embedded teeth Impacted teeth cannot erupt due to an obstruction. Embedded teeth do not erupt due to lack of eruptive force. Ankylosed teeth

Impacted 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.

Impacted and Embedded Teeth (cont.)

Impacted 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.

Ankylosed Teeth Tooth cementum fused to bone (pgs. 180-181) Prevents exfoliation of the deciduous tooth and eruption of the underlying adult tooth The ankylosed deciduous tooth appears submerged and has a different sound when percussed (kind of a dull thud).

Ankylosed Teeth (cont.)

Ankylosed Teeth (cont.) The periodontal ligament space is lacking. Difficult to extract Removal 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.

Discussion Questions What 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?