Odontogeniccysts OKC

Odontogenic keratocyst

1. Odontogenic Cyst (OKC) Dr. Maryam Arbab

2. INTRODUCTION CLASSIFICATION CAUSES HISTOPATHOLOGY CLINICAL FEATURES 6. RADIOGRAPHIC FEATURES 7. DIFFERENTIAL DIAGNOSIS 8. TREATMENT 9. PRINCIPLE OF TREATMENT Types of Flaps. Surgical removal the of the cyst . OUTLINE

3. A cyst is an epithelium-lined sac containing fluid or semisolid material . In the formation of a cyst, the epithelial cells first proliferate and later undergo degeneration and liquefaction. The liquefied material exerts equal pressure on the walls of the cyst from within. INTRODUCTION

4. Cysts grow by expansion and thus displace the adjacent teeth by pressure. May produce expansion of the cortical bone. On a radiograph, the radiolucency of a cyst is usually bordered by a radiopaque periphery of dense sclerotic bone. The radiolucency may be unilocular or multilocular .

5. Odontogenic cysts are those which arise from the epithelium associated with the development of teeth. The source of epithelium is from the enamel organ, the reduced enamel epithelium, the cell rests of Malassez or the remnants of the dental lamina.

6. Radicular cyst Residual cyst Dentigerous cyst (follicular) Primordial cyst Lateral periodontal cyst Odontogenic keratocyst Calcifying odontogenic cyst ( Gorlin cyst) CLASSIFICATION

7. ODONTOGENIC KERATOCYST

8. There is general agreement that OKCs develop from dental lamina remnants in the mandible and maxilla. However, an origin of this cyst from extension of basal cells of the overlying oral epithelium has also been suggested. Genetic CAUSES

9. The epithelial lining is uniformly thin, generally ranging from 8 to 10 cell layers thick . The basal layer exhibits a characteristic palisaded pattern with polarized and intensely stained nuclei of uniform diameter. The luminal epithelial cells are parakeratinized and produce an uneven or corrugated profile. HISTOPATHOLOGY

10. Additional histologic features that may occasionally be encountered include budding of the basal cells into the C.T wall and microcyst formation. The fibrous connective tissue component of the cyst wall is often free of inflammatory cell infiltrate and is relatively thin.

11. Age: Any age , especially adults. Location: Mandibular molar, ramus area favored; may be found dentigerous, in position of lateral root, periapical, or primordial cyst. OKCs are relatively common jaw cysts. They occur at any age and have a peak incidence within the second and third decades. CLINICAL FEATURES

12. Location: The most common is the posterior body of the mandible (90% posterior to the canines) and ramus (more than 50%). This type of cyst occasionally has the same pericoronal position as dentigerous cyst. Periphery and shape: Usually with a cortical border unless becomes secondarily infected. The cyst may have a smooth (round or oval shape), or it may have a scalloped outline. RADIOGRAPHIC FEATURES

13. Internal structure: M ost commonly is radiolucent. The cystic cavity contain keratin. In some cases curved internal septa may be present, giving the lesion a multilocular appearance.

14. The effects on surrounding structures: It grows along the internal aspect of the jaws, causing minimal expansion except for the upper ramus and coronoid process, where considerable expansion may occur. OKCs can displace and resorb teeth but to a slightly lesser degree than dentigerous cysts. The inferior alveolar nerve canal may be displaced inferiorly. In the maxilla this cyst can invaginate and occupy the entire maxillary antrum.

15. Dentigerous cyst OKC Ameloblastom a , AB has a greater propensity to expand. Odontogenic myxoma , multilocular with fine straight septa. A simple bone cyst often has a scalloped margin and minimal bone expansion. S everal OKCs are found. T hese cysts may constitute part of a basal cell nevus syndrome. DIFFERENTIAL DIAGNOSIS

16. Wide (local) surgical excision to prevent the recurrence or Marsupialization - the surgical opening of the (KCOT) cavity and a creation of a marsupial-like pouch, so that the cavity is in contact with outside for an extended period. TREATMENT

17. Local anesthesia. Types of Flaps. Surgical removal the of the cyst . PRINCIPLES OF TREATMENT

18. LOCAL ANESTHESIA

19. 1. Trapezoidal flap. Advantages: Provides excellent access. A llows surgery to be performed on more than two teeth. P roduces no tension in the tissues. A llows easy reapproximation of the flap to its original position. Disadvantages: Produces a defect in the attached gingiva. TYPES OF FLAPS

20. 2. Triangular Flap. Advantage : Ensures an adequate blood supply , satisfactory visualization , very good stability . Disadvantages: Limited access to long roots. T ension is created when the flap is held with a retractor, and it causes a defect in the attached gingiva.

21. 3. Envelope Flap. Advantages: Avoidance of vertical incision and easy reapproximation to original position. Disadvantages: Difficult reflection (mainly palatally ) . G reat tension with a risk of the ends tearing. L imited visualization in apicoectomies . L imited access. P ossibility of injury of palatal vessels and nerves. D efect of attached gingiva

22. 4. Semilunar Flap. Advantage: Small incision and easy reflection. N o recession of gingivae around the prosthetic restoration. Disadvantages: The incision being performed right over the bone lesion due to miscalculation. S carring in the anterior area. D ifficulty of reapproximation . L imited access and visualization . Tendency to tear.

23. Enucleation: This technique involves complete removal of the cystic sac and healing of the wound by primary intention. This is the most satisfactory method of treatment of a cyst and is indicated in all cases where cysts are involved, whose wall may be removed without damaging adjacent teeth and other anatomic structures. SURGICAL REMOVAL OF THE CYST

24. The surgical procedure for treatment of a cyst with enucleation includes the following steps: Reflection of a mucoperiosteal flap. Removal of bone and exposure of part of the cyst. Enucleation of the cystic sac. Care of the wound and suturing.

25. Panoramic radiograph showing an extensive radicular lesion at the region of teeth 22, 23, 24 Clinical photograph of case

26. Removal of maxillary cyst, with labial access. Incision for creating a trapezoidal flap. Reflection of flap and exposure of surgical field.

27. Removal of bone at the labial aspect respective to the lesion. Osseous window created to expose part of the lesion.

28. Removal of cyst from bony cavity, using hemostat and curette. Surgical field after removal of lesion.

29. Operation site after placement of sutures. Panoramic radiograph and clinical photograph taken 2 months after the surgical procedure.

30. Marsupialization: This method is usually employed for the removal of large cysts and entails opening a surgical window at an appropriate site above the lesion. In order to create the surgical window, initially a circular incision is made, which includes the mucoperiosteum, the underlying perforated (usually) bone, and the respective wall of the cystic sac.

31. Marsupialization : After this procedure, the contents of the cyst are evacuated, and interrupted sutures are placed around the periphery of the cyst, suturing the mucoperiosteum and the cystic wall together . Afterwards, the cystic cavity is irrigated with saline solution and packed with iodoform gauze, which is removed a week later together with the sutures. During that period, the wound margins will have healed, establishing permanent communication. Irrigation of the cystic cavity is performed several times daily, keeping it clean of food debris and averting a potential infection .

32. Marsupialization method. Circular incision includes mucosa and periosteum . Exposure of buccal cortical plate and removal of portion of bone with round bur Enlargement of osseous window with rongeur

33. Exposure of cyst after removal of bone Suturing of wound margins with cystic wall

34. Packing of cystic cavity with iodoform gauz Cystic cavity after insertion of gauze

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