1. Developmental disorders or anomalies
A failure or disturbance that occurs during the developmental processes causing a lack, excess or deformity of a body part.

2. Inherited or Congenital Disorders
Inherited – different from developmental in that they are caused by an abnormality in the genetic makeup - transmitted from parent to offspring
Congenital – present at birth
Can be inherited or developmental….congenital abnormalities usually have an unknown cause.

3. Developmental Soft Tissue Abnormalities
Ankyloglossia – “tongue-tied” – complete or partial fusion of the lingual frenum to the floor of the mouth or lingual attached gingiva
May have problems with speech
May need frenectomy

4. Commissural Lip Pits
Epithelium-lined blind tracts located at the corners of the mouth
Congenital lip pit – midline of the vermilion border of the lip

5. Lingual Thyroid
Ectopic lingual thyroid nodule – a mass of thyroid tissue located on the tongue away from the normal anatomic location of the thyroid gland.
Appears as a smooth nodular mass at the base of the tongue posterior to the circumvallate papillae on or near the midline.

6. Developmental Cysts
A cyst is an abnormal, pathologic sac or cavity lined by epithelium and enclosed in a connective tissue capsule
The most common cyst observed in the oral cavity is caused by pulpal inflammation and is called the radicular cyst
The residual cyst is a radicular cyst that remains after extraction of the offending tooth

7. Developmental Cysts Odontogenic – related to tooth development
Nonodontogenic – not related to tooth development
Intraosseous – occur within bone
Extraosseous – occur in soft tissue (out of bone)

8. Odontogenic Cysts
Dentigerous cyst – forms around the crown of an unerupted or developing tooth.
This radiograph features the typical example of a dentigerous cyst. The well-defined radiolucency surrounding the crown of the unerupted molar. Cysts of this size are generally asymptomatic and are discovered on routine radiographic examination

9. Primordial Cyst
The difference between primordial and dentigerous cysts is illustrated well in this case. A dentigerous cyst is associated with the unerupted lower molar while the large well-defined radiolucency extending from the midline to the opposite lower first molar proved to be a primordial cyst on biopsy examination.
Primordial cysts do not involve crowns of unerupted teeth.

10. Primordial Cyst

11. Primordial Cyst
This is a typical example of the primordial cyst occurring in the third molar area. No tooth had developed so we can assume the cyst originated from either the enamel organ prior to calcification or from rests of the dental lamina.

12. Odontogenic Keratocyst
Pre-Operative
This large odontogenic keratocyst involving the angle and ramus (#37) was curetted only to "recur" two years later as a lesion high in the ramus (#38)
Post-Operative
Because of the tendency to recur, all patients should be kept on long-term radiographic and clinical observation

13. Calcifying Odontogenic Cyst
The calcifying odontogenic cyst is less common than other odontogenic cysts but displays interesting radiographic and histopathologic features. It may or may not be associated with an unerupted tooth and possesses considerable growth potential so that many examples are large and somewhat destructive. Any area of the jaw may be involved.

14. Calcifying Odontogenic Cyst
"Ghost Cells"
These illustrations show the typical morphologic pattern of the calcifying odontogenic cyst. An odontogenic epithelial membrane lines it with columnar basal cells and areas of stellate reticulum. There are numerous keratin masses that are described as “ghost cells” . Dystrophic calcification is prominent and even melanin granules can be seen

15. Lateral Periodontal Cyst
The lateral periodontal cyst is generally small and well demarcated. It occurs most frequently in the premolar region and is adjacent to vital teeth.
Radiolucencies are generally ovoid.
Here are typical examples:

16. Gingival Cyst
This is a good illustration of a small slightly bluish gingival cyst on the mandibular gingiva between the lateral incisor and cuspid. Gingival cysts differ from lateral periodontal cysts only by the fact that no significant radiographic findings are present in association with the gingival cyst.

17. Nasopalatine Canal Cyst
Arise from remnants of the nasopalatine duct are divided into two varieties: incisive canal type and those originating in the papilla palatina. Almost all nasopalatine duct cysts occur within the incisive canal and are intraosseous. They may occur at any level between the nasal and the oral cavity and are always radiolucent. Cysts of the papilla palatina show no radiographic changes because they are entirely within soft tissue.
This incisive canal cyst is relatively small but of typical location and shape. It has a somewhat teardrop shape and shows a well-demarcated border.

18. Median Palatal Cyst
Median palatal cysts occur at the midline of the palate posterior to the incisive canal and are thought to originate from remnants of epithelium remaining after fusion of the palatine processes of the maxilla.
This radiograph is from a 43 year-old female who presented with swelling of the midline of the palate for two weeks. The radiograph displays an ovoid radiolucency at the midline that extends quite a distance posteriorly. Note the nasal septum that is clearly visible. This lesion must be differentiated from the incisive canal cyst and from cysts of inflammatory origin associated with adjacent teeth. At surgery it was found that this lesion did not involve the incisive canal and that teeth were vital.

19. “Globulomaxillary” Cyst
Often misdiagnosed as a globulomaxillary cyst when in reality it is a periapical cyst.

20. Lymphoepithelial Cyst
Branchial Cleft Cyst
There is some controversy as to the exact origin of this cyst that occurs at various levels in the lateral neck. Some believe the lesion arises from remnants of pharyngeal pouches or branchial arches while others think the lesion originates from cystic alteration of salivary gland type epithelium often found within lymph nodes of the neck.
This large branchial cleft cyst was moveable, asymptomatic and slightly fluctuant.

21. Thyroglossal Duct Cyst
This asymptomatic swelling near the midline is a good example of the thyroglossal duct cyst which is an epithelial lined structure originating from remnants of the thyroglossal duct.
The thyroid gland originates from the area of the foramen cecum at the base of the tongue. The thyroid tissues then migrate to programmed location. Remnants of epithelium remain along this tract and these may become cystic or even tumorous.

22. Static Bone Cavity Static Bone Cavity
Developmental mandibular lingual salivary gland depression (static bone cavity, lingual salivary gland depression, and Stafne bone cavity) represent cortical depressions or defects on the lingual aspect of the posterior body of the mandible.
These are often bilateral, are asymptomatic and are discovered on routine radiographic examination.
In most cases the radiolucency is in continuity with the inferior border of the mandible and is below the mandibular canal.

23. Developmental Dental Abnormalities
Anodontia - congenital lack of teeth
Hypodontia - lack of one or more teeth
Microdontia – smaller (“peg lateral”)
Macrodontia – larger
Supernumerary- extra tooth …usually smaller (mesiodens, distomolar)
*familial tendency

24. Developmental Dental Abnormalities
Gemination
Fusion
Ectopic Cusp
Concresence
Dilaceration
Enamel Pearl
Taurodont
Dens in Dente
Dens Evaginatus

25. Abnormalities in the shape of teeth
Gemination-a single tooth bud divides and results in the incomplete formation of two teeth

26. Fusion
Union of two normally separated adjacent tooth germs.

27. More abnormalities in the shape of teeth
Concrescence - two adjacent teeth are united by cementum only
Dilaceration - abnormal root morphology
Enamel Pearl - small enamel projection located on a root surface…thought to occur as a result of the abnormal displacement of ameloblasts during tooth formation.

28. Concrescence

29. Ectopic Cusp
Talon Cusp - a supernumerary cusp which arises from the cingulum portion of an incisor and extends to the incisal edge as a prominent projection of enamel.

30. Taurodont
A malformed multirooted tooth characterized by an altered crown-to-root ratio; the crown being of normal length, the roots being abnormally short and the pulp chamber being abnormally large.

31. Dilaceration

32. Enamel Pearl

33. Dens in Dente
"A tooth within a tooth“…a malformation caused by an invagination of the crown before it is calcified.

34. Dens Evaginatus
A developmental anomaly in which a focal area of the crown projects outward and produces what appears as an extra cusp or an abnormal shape to existing cuspal arrangements (e.g.,talon cusp)
Primarily premolar
*usually bilateral
…conical, tuberculated projection from the central fissure of the occlusal surface
…can interfere with tooth eruption causing malalignment
…often in individuals of Mongolian origin

35. Abnormalities of tooth structure
Enamel hypoplasia-incomplete or defective formation of enamel, resulting in the alteration of tooth form or color
Results from a disturbance of or damage to ameloblasts during enamel matrix formation

36. Enamel Hypoplasia A defect in tooth enamel that results in less quantity of enamel than normally formed
*pits, grooves, lines or larger areas of missing enamel surface  - reduction in enamel thickness  - possible occlusal distortion, aesthetic problems, sensitivity --  yellowish or brownish discoloration…may be localized or present on numerous teeth and all or part of the surfaces of each affected tooth may be involved

37. Regional Odontodysplasia
A developmental disturbance of several adjacent teeth in which the enamel and dentin are thin and irregular and fail to adequately mineralize; surrounding soft tissue may be hyperplastic and contain focal accumulations of spherical calcifications and odontogenic rests.
“Ghost
Teeth”

38. Abnormalities of tooth eruption
Impacted teeth

39. Ankylosed Teeth Roots are “fused” to the alveolar bone
Especially common with retained deciduous molars