| Odontogenic keratocyst, also known as keratocystic odontogenic tumor, is an aggressive benign neoplasm of the jaws with a high recurrence rate. The mandible is involved far more frequently than the maxilla, with a higher frequency in the mandibular molar-ramus area. It can be treated either by enucleation or marsupialization depending on their size, location and proximity to vital structures, such as the teeth, maxillary sinus, nasal cavity and mandibular canal, as well as the continuity of the bony margins. Large OKCs can be treated by partial resection of the jaws, enucleation or marsupialization, which possibly results in pathological fracture of the mandible, facial deformity, loss of teeth in the affected area, and damage of adjacent structures with decreased physiological function and life quality of patient. They are often managed by marsupialization, which relieved the pressure within the cystic cavity, to decrease slowly in size and allowed new bone to fill the defect. The lining epithelium is changed into non-kerating and the thickness of the cyst wall is increased. Contiguous structures such as tooth, the maxillary sinus, or the inferior alveolar canal can be saved from damage. The procedure was highly successful in decreasing the cyst size before enucleation, is useful to help avoid extensive surgery and considered as the first option for the treatment of large OKCs.It is necessary to keep the opening patent after operation. An acrylic resin denture-like cyst plug or obturator can maintain drainage, temporary restore the lost anterior or premolars, partially restore the facial deformity and improve defective labiodental and linguodental speech and masticatory function. However, a removable cyst plug is easily to be dislocated and difficult to perform negative pressure drainage. The development of new cyst drainage device implanted intraosseously will avoid these disadvantages mentioned above.The timing of enucleation following marsupialization usually is based on morphological changes within the cyst area. Radiography is the major nonsurgical method for detecting bone formation in the affected area. Bone formation is radiographically expressed as an increase in radiopacity, resulting in a higher optical density of the bone image. Thus it is more useful than histological examination in clinical situations because of its speed, continuity of measurements, and noninvasive nature. To determine the process or progression of bone formation, the radiopacity changes between radiographs should be compared with quantitative analyses and objective evaluation of radiographic images. However, reports specifically on the assessment of bone regeneration following marsupialization are rarely found in the literature. The study consists of two parts:Part 1, design and fabrication of new drainage device for management of jaw cysts and Part 2, evaluation of bone formation after surgery of mandibular cysts.Part One:The development and application of new drainage devices after marsupialization of jaw cystsApplication of a removable cyst plug in drainage after marsupialization of jaw cystsObjective: To introduce the design and making of two types of removable cyst plugs and their application in drainage following marsupialization of jaw cysts. Methods: The clasp retained cyst plugs were classified into two types:conventional and denture-like type according to their different function, and steps and procedures for making cyst plugs were described respectively. Results: Cyst plugs were used for 102 lesions in molar regions,27 in premolar and 26 in anterior regions. There were 63 conventional and 92 denture-like types, which kept cyst opening unobstructed in all patients without complications associated with application of this device. Conclusion: The clasp retained cyst plug is a better drainage device for marsupialized jaw cysts and denture-like type can temporarily replace the tooth lost operatively.The development of intraosseous drainage device for jaw cystsObjective: To develop an intraosseous drainage device for management of jaw cystic lesions and temporary restoration of lost teeth. Design and Fabrication:The new drainage device for jaw cysts is made of titanium and consists of an intraosseous drainage tube, abutment, connector and plastic cover cap. They are sequencely connected. The lower end of the drainage tube with screw threads is extended into the cyst cavity and the upper end is opened to the oral cavity via the abutment and connector. The connector is used to restore lost teeth or to connect a negative pressure drainage tube. Conclusion:The intraossous drainage device for jaw cyst can be suitable for negative pressure drainage and temporary prosthesis.Part Two:Clinical and radiographic study of the bone formation following surgery of mandibular cysts. Evaluation of the bone formation following marsupialization of mandibular odontogenic keratocysts.Objective: The purpose of this study was to evaluate the bone formation following marsupialization of odontogenic keratocysts of the mandible. Patients and Methods: Fifty three patients with mandibular odontogenic keratocysts underwent marsupialization at the Hospital of Stomatology, Wuhan University, between the years 1999-2008. In all of the cysts, drainage patency was kept by the cyst plug after operation. Clinical and radiographic examinations were made at postoperative 1,3, and 6 months. Bone density of the cyst site was measured with the Digora(?) (Soredex, Orion Corporation, Helsinki, Finland) on preoperative and postoperative panoramic radiographs. The volume of the cyst was measured by injection of saline solution into the cyst cavity at marsupialization, postoprative 1,3, and 6 months respectively. The data set was further analysed with the aid of the Statastical Package for the Social Sciences (SPSS) 13.0 package, and t test and Spearman’s rank correlation was used for statistical analysis. Results were considered significant at P< 0.05.Results: Healing was uneventful in all patients. The panoramic radiographs showed a continuous increase in bone density of the cystic area, with being 22.42% increase at postoperative 1 month,46.07% at 3 months and 64.69% at 6 monthes compared with preoperative values. The decrease of the cyst volume was 19.05% at postoperativel month,55.62% at 3 months and 79.67% at 6 months. The increase of bone density was inversely correlated with decrease of the volume of the cyst cavity (P<0.05). Conclusion:Bone regeneration can occur more rapidly in large mandibular keratocysts following marsupialization with drainage by a cyst plug. The marsupialization can be followed by secondary enucleation at postoperative 3 months when the bone density increased above 45% or the cyst volume decreased 50% in comparison with preoperative results.Evaluation of the bone formation after enucleation of mandibular odontogenic keratocystsObjective: To investigate bone formation after enucleation of mandibular odontogenic keratocysts by a computed assisted analysis of postoperative panoramic radiographs. Methods:Fifty-eight patients with mandibular keratocysts were treated by surgical enucleation and primarily closed without grafting, in the Hospital of Stomatology, Wuhan University. There were 36 cases of male and 22 cases of female, with a mean age of 41 (range 18-69). The largest diameter of cysts 3.5 cm to 7.1 cm. Post-operative clinical and radiographic examinations were performed at 1,3,6 and 12 months. Bone density of residual cavity was measured on the preoperative and postoperative panoramic radiographs with Digora(?) (Soredex, ORION Corporation, Helsinki, Finland) through a grayscale of 254 tonalities. The data set was further analysed with the aid of the Statastical Package for the Social Sciences (SPSS) 13.0 package, and t test compared between bone density values of different time periods. Results were considered significant at P<0.05. Results:Progressive bone formation in residual cavity was observed after enucleation of cysts. The increase in bone density was 6.85% at 1 month,22.61% at 3 months,49.45% at 6 months and 71.77% at 12 mouths in comparison with that of the preoperative radiograph. Although increase in bone density was not significant difference between first postoperative 3 months and second 3 months, this increase was higher in the first 6 months than that in the later 6 months(P< 0.05).No significant difference was found between male and female. Conclusion:Bone regeneration can progressively occur in the defected area without grafting materials after enucleation of mandibular keratocyst, with significant increase of bone density at postoperative 6 months. |
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