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Oral Surgery

Authors: Dr. S. Bhuvaneshwari, Dr. Rahul Maheshwari, Dr. kartik Tank
 

Keratocystic odontogenic tumor ( according to the 2005 WHO classification of oral cysts and tumors) previously known as the Odontegenic keratocyst ( term coined by Phillipsen in 1956) is a well known odontogenic cyst of dental origin, but also notoriously behaves like a tumor. The Keratocystic odontogenic tumor [KCOT] behaves like a tumorin many ways, for e.g. involvement of large areas of the bone, high recurrence rate, distinctive histopathological features of the lesion, disregulation of the PTCH (patched) gene in both Nevoid basal cell carcinoma syndrome associated and sporadic odontogenic keratocysts , etc. On the other hand, successful treatment by marsupialization denies its tumor characteristics. [1] There are two histological variants of KCOT i.e., parakertinized and orthokeratinized variety. The cyst’s notoriety is credited more to the parakeratinized variant of KCOT which has high incidences of local recurrence.

The treatment options for KCOT are many. Eyre and Zakrzewska [2] in 1985, have stated the following treatment options for the KCOT -

1. Enucleation:
  • with primary closure
  • with packing
  • with chemical fixation
  • with cryosurgery
2. Marsupialization:
  • only
  • followed by enucleation
3. Resection Bramley [2], in 1971, proposed a treatment plan for the keratinising cystic odontogenic tumor due to its tendency to recurrence . He suggested:
  • Unilocular cysts to be treated by intraoral
  • resection.
  • In areas of difficult access, decompression and secondary enucleation is advocated.
  • Large multilocular cysts should be treated by resection and primary bone graft.

The conservative management of KCOT involves enucleation of the cyst in toto followed by local application of Carnoy’s solution into the cavity walls. This procedure has gained more accolades over the long period of time for its greater success in local chemical cauterization activity which efficiently destroys the daughter cysts and cystic lining if any. This article is an attempt towards providing a review on the use of Carnoy solution in the conservative management of KCOT.

DISCUSSION

Carnoy’s solution was first reported to be used as a fixative to study the nematodes with the aim to fix the tissue and preserve the nuclear detail. But the fixative nature is not what the Oral and Maxillofacial surgeons exploit while using it, but its chemical cauterization property. Carnoy’s solution was described in 1933 by Cutler and Zolinger as a sclerosing agent in the treatment of cysts and fistulae. 2 Carnoy’s solution is used in conservative management of KCOT and even the unicystic ameloblastoma. The use of Carnoy’s solution to reduce the morbidity and recurrence rate in relation to unicystic ameloblastoma was initially suggested by Stoelinga and Bronkhorst in 1987 4.

Carnoy’s Solution is composed of 1 g of ferric chloride (FeCl3) dissolved in 6 mL of absolute alcohol, 3 mL of chloroform, 1 mL of glacial acetic acid 5,6.

Recurrence of the KCOT ranges from 2.5% 7,8 to 62% [8,9]. The possible mechanisms of recurrence have been described by Voorsmit et al. 7 in 1981. These state that any lining epithelium left behind in the oral cavity may give rise to a new lesionformation. Daughter cysts, microcysts or epithelial islands can be found in the wallsof the original cysts. New KCOTs maydevelop from epithelial offshoots of thebasal layer of oral epithelium 8.

Recurrence of keratocystic odontogenic tumor has been attributed to several mechanisms, Woolgar et al. 19 described three different theories. The first involves incomplete removal of the original cyst lining. The second involves growth of a new OKC from small satellite cysts or odontogenic epithelial rests left behind by the surgical treatment. The third involves the development of an unrelated OKC in an adjacent region of the jaws that is interpreted as a recurrence. It has been suggested that recurrence is a consequence of microcysts in the mucosa overlying the recurrent lesions 20. Attempts have been made to reduce this high recurrence rate by improved surgical techniques, such as removal of adjacent mucosa, smoothening of the osseous wall of the cystic cavity, resection of neighbouring parts of the mandible, tanning of the epithelial lining of the cyst with Carnoy’s solution and marsupialization 21-23.

Both conservative approach as well asaggressive approach has been advocated forthe treatment of the KCOT. Conservativeapproach, however, has not gained muchpopularity, because complete removal ofthe KCOT can be difficult because of thethin friable lining, limited surgical access, skill and experience of the surgeon, anddesire to preserve adjacent vital structures.The goals of treatment should involveeliminating the potential for recurrencewhile also minimizing the surgicalmorbidity 10,11,12.

Enucleation followed by chemical cauterization using Carnoy’s solution along with excision of overlying attached mucosahas been used for the treatment of KCOT. Stoelinga [13] in 2001 has concluded in along term follow up study that this methodgave rise to a fairly low number ofrecurrences. Peripheral ostectomy combined with carnoy’s solution may givenil recurrence rate 12.

Radical and conservative methods of treating KCOT can becombined with the use of Carnoy’s solution, which acts as ancauterizing agent, causing denaturation of organic molecules. Its penetration into the tissue results in rapid local fixation and hemostatic action 14. Carnoy’s solution has been thoroughly studied in relation to keratocysts and was shown in an animal model to penetrate cancellous bone to a depth of 1.54 mm. So it is likely to penetrate cancellous bone and thus devitalize and fix the remaining tumor cells. 17,18

Some authors suggest that the major disadvantages of Carnoy's solution are its systemic toxicity and local caustic effect resulting in a damage of vital anatomical elements (especially nerves) [15]. However, Blanaset al. 16 state that application of Carnoy’s solution to cyst cavity for 3 min after enucleation should not damage the inferior alveolar nerve.

Carnoy’s solution for cysts in the maxillashould be used very selectively, since the delicate bony walls around the sinus may become necrotic.

But Ferich et al. suggested that the application of Carnoy’s solution should not exceed 3 min. They showed that the critical time to nerve impairment of the rabbit inferior alveolar nerve was 3 min and it should not be directly applied over the nerve.Though there remains a need for human studies, the use of Carnoy’s solution to reduce the recurrence rate should be balanced against the risk of nerve morbidity 17,18.

Certainly, the use of Carnoy’s solution as an adjunct measure in surgical treatment of OKC and its correct application is of non-questionable importance. This is corroborated by the studies in which comparisons were performedwith the recurrence rate of application of certain surgical method with and without Carnoy’s solution. A recent evidence reveals that most of epithelial islands and/or microcysts, as the most crucial factors for recurrence, are in the overlying mucosa that contacts a cyst, especially in the mandibular retromolar area. Therefore, the essence of Carnoy’s solution use lies in its influence on epithelial islands and microcystic formations; a consequent peripheral ostectomy with excision of the overlying attached mucosa completely eliminates the presence of epithelial changes. The results of studies that compared the incidence of recurrence of different surgical techniques in OKC showed that in cases of peripheral ostectomy combined with Carnoy’s solution no recurrences were noted in ten years and more postoperatively.24

Carnoy’s solution has also been used adjunctivelt to treat ameoloblastoma. In the literature, recurrence after conservative (non-resection) treatment of conventional ameloblastoma ranges from 50 to 90%. Recurrence after conservative treatment of unicystic ameloblastoma is reported to be between 10 and 25 % 25,26. Complete resection of the tumor followed with treatment of cavity with Carnoy’s solution is an accepted treatment with low rate of recurrences post-operatively.

CONCLUSION

The preferred treatment for both KCOT and unicystic ameloblastoma, Ackerman type 1 and 2 in the mandible, is complete enucleation and treatment of the bony defect with Carnoy’s solution. A cochrane study review has been able to present with the finding ‘‘In two large reviews comparing enucleation alone versus enucleation and adjunctive treatment with Carnoy’s solution an overall benefit of the use of Carnoy became apparent, although not all the reviewed studies were consistent in this respect’’.27 Thus, Carnoy’s solution stands to be a valuable ammo against Keratocystic Odontogenic tumor even in present times.

BIBLIOGRAPHY
  1. Suhas SG, Pankaj K (2009) Keratocystic odontogenic tumor : a review. J Maxillofac Oral Surg 8(2):127–131
  2. Eyre J, Zakrzewska JM (1985) The conservative management of large odontogenic keratocysts. Br J Oral MaxillofacSurg 23(3): 195–203
  3. Bramley PA (1971) Treatment of the cysts of the Jaws. Proc R Soc Med 64(5): 547–550
  4. Lee PK, Samman N, Ng IO (2004) Unicystic ameloblastoma- useof Carnoy’s solution after enucleation. Int J Oral MaxillofacSurg33:263–267
  5. Cutler EC, Zollinger R (1933) Sclerosing solution in the treatmentof cysts and fistulae. Am J Surg 19:411–418
  6. Voorsmit RACA, Stoelinga PJW, van Haelst UJGM (1981) The management of keratocysts. J MaxillofacSurg 9:228–236
  7. Voorsmit RA, Stoelinga PJ, Van Haelst UJ (1981) The management of keratocyst. J MaxillofacSurg 9(4): 228–236
  8. Irvene GH, Bowerman JE (1985) Mandibular keratocyst: Surgical Management. Br J Oral Maxillofac Surg 23(3): 204–209
  9. Pindborg JJ, Hansen J (1963) Studies onodontogenic cyst epithelium 2. Clinical and roentgenologic aspects of Odontogenic keratocyst. ActaPathol MicrobiolScand 58: 283–294
  10. Meiselman F (1994) Surgical management of the odontogenic keratocyst: Conservative approach. J Oral MaxillofacSurg 52(9): 960–963