Clinical Study Of Fenestration And Decompression Technique In The Treatment Of Large Jaw Odontogenic Cystic Lesions

Background:Jaw odontogenic cystic lesions include dentigerous cyst,odontogenic keratocyst(OKC),unicystic ameloblastoma and so on.Because of their hidden location and the character of slow growth,there are no obvious symptoms in the early stage.Most patients only when lesions involved a greater range and caused facial deformity to seek clinical treatment, at this time,treatment is more difficult.If just excising cysts or performing curettage,postoperative recurrence rate remains high,and because bone regeneration of repairing post-operative bone defect cavity is slow,there is the risk of pathological fracture.If the resection of jaw,a thorough treatment accompanied by larger surgical trauma and will bring some serious complications,such as changes in facial morphology,decline in masticatory function,lower lip numb and so on.Especially for adolescent patients and the patients with particular emphasis on their appearance,this surgery will result in their permanent psychological trauma.Therefore,the treatment of larger jaw odontogenic cystic lesions should be not only to ensure effect,but also to maximize the retention of jaw form and function.In order to achieve this treatment goal,clinicians have developed a variety of more practical methods of conservative treatment,include fenestration and decompression technique,marsupialization and suction drainage,and demonstrated their good clinical results. The theoretical basis of conservative treatment is the base and external conditions of the growth of jaw cystic lesions.In the confined environment the residual epithelial tissue of jaw bone develops to odontogenic cyst.Now widely recognized that cyst increases its areas depends primarily on three factors:capsule wall,hydrostatic pressure and bone resorption factors.According to these theories,as long as remove or destruct these factors,we can inhibit the growth of cysts, and narrow their scopes.The procedure of fenestration and decompression is:open the local bone and the partial wall in the surface of cyst as a window for draining fluid and keep this window open,the internal and external pressures of cyst can maintain a balance,then the absorption factors in the capsule wall are eliminated or reduced .The result is cyst reduction and bone reconstruction which is the purpose of fenestration technique.Usually the duration of decompression is 6 to 18 months after surgery,the desired result is cyst healing during this period;if not,Ⅱ-stage operation is necessary to excise cyst completely. Its time depends on the extent of cyst reduction and bone regeneration,it is generally believed that 4 to 6 months after fenestration when bone formation is obvious is the suitable time.Many research and practice proved that fenestration and decompression in the treatment had significant effect.Therefore this technique has gradually became the first choice of many clinicians to treat odontogenic cystic lesions,especially for large cystic lesions and adolescent patients.Objective:To clinically evaluate the effect and application value of fenestration and decompression technique in the treatment of large jaw odontogenic cystic lesions.And to explore the best time ofⅡ-stage operation.And evaluate the role of physical therapy in prompting healing of cystic lesions.Methods:27 cases with large jaw cystic lesions but not received any treatment before were performed fenestration and decompression.The pathological diagnosis of odontogenic keratocyst of the patients were randomly divided into tow groups,one group accept the three courses of laser therapy.All patients were told to wash their cyst cavities with warmer water or saline 2 times every day.Followed up these cases for 18 months.Clinical and radiological examinations were carried out regularly to evaluate the effect.Using Image-Pro Plus 6.0 software to measure the areas of lesions on panoramic X-ray films to compare the changes before and after operation,as well as the differences between the control group and physical therapy group,and then according to the reduction of lesions to identify the best time ofⅡ-stage operation.Results:1.After fenestration and decompression,the sizes of the cysts reduced gradually,bone regeneration was noticed on radiographs.After surgery for 3 months,cyst cavities of 27 patients shrank to varying degrees:dentigerous cyst 46.9%~65.6%,OKC 20.2%～42.2%,unicystic ameloblastoma 18.4%~21.3%.All these have statistical significance(P<0.01).2.The first 6 months after surgery,lesions in all cases reduced most significantly.The changes reached their maximum in different time:dentigerous cyst is in 3 months after surgery,OKC is in 4~6 months after surgery,UA is in 6 months after surgery.3.The degrees of reduction between physical therapy group and the control group have significant difference in the 1~6 months follow-up visit period after surgery(p<0.05 or P<0.01),the former significantly higher than the latter.And the best time ofⅡ-stage operation of physical therapy group is one or two-month earlier than the control group.4.During the follow up period,6 cases of dentigerous cyst faded away entirely,and cyst cavities of the 21 rests were reduced greater than 50% after surgery for 5~6 months.So special effective rate is 22.2%,effective rate is 100%.Conclusion:1.Fenestration and decompression technique is an useful treatment modality for the primary management of large jaw odontogenic cystic lesions,especially suitable for young patients.2.For odontogenic keratocyst and unicystic ameloblastoma,after operation of 6 months is the best choice for carring outⅡ-stage operation.3.Laser therapy in the treatment of odontogenic cysts has a positive effect.This method by accelerating the rate of bone regeneration makesⅡ-stage operation advance.