Radicular cysts are the most common inflammatory odontogenic cystic lesions of the oral cavity. They are most commonly found at the root apices of endodontically affected teeth at any age, affecting any gender1. Frequently they are symptomless and are direct sequel to chronic apical infections2. Since scant literature is available about natural history of radicular cysts, it’s not clear what proportion of it regresses and grows. Initial small size cysts can even extend up to 5-6cms, where larger lesions frequently require endodontic as well as surgical approach for complete resolution of lesion.
In presence of long standing large lesions that do not resolve after endodontic therapy, the teeth involved may undergo root resorption and displacement. Further progression of cysts may produce expansion of cortical plates either bucally or palatally 1,2, where palatal cortication often involve challenges in surgical management owing to poor accessibility. The main goal of apical surgery is to prevent bacterial leakage from the root canal system into the periradicular tissues by placing a tight root end filling material following root resection3.
It is usually achieved by removal of periapical tissue and by exclusion of any irritants within the physical confines of the affected roots followed by root resection and root end filling and simultaneously filling of the bone cavity with different biomaterials. Various biomaterials such as porous hydroxyapatite, demineralized cortical bone4, resorbable membrane5, exogenous growth factors etc6 have been successfully used to treat large lesions or situation where both cortical components are affected. However certain disadvantages are inherently associated with each of these biomaterials like suboptimal or delayed outcome resulting in recurrence and need for re-surgery3,7. Outcomes of regenerative therapy in large sized defects are affected by various factors such as age and gender of patient, teeth group, quality of orthograde root filling, time of root filling in relation to operation, retrograde root fill, periodontal status of the teeth involved, size of the periapical lesion and experience of the operator8,9. Recently, PRF has shown to act as suitable scaffold for breeding human periosteal cells in which may be suitable for bone tissue engineering applications10. The application of PRF in fields of plastic surgery11, oral and maxillofacial surgery12 and implant surgery13 has demonstrated successful and rapid results in terms of bone regeneration. The completely filled defect with autologous PRF is meant to stabilize the overlying flap and hasten the wound healing process. Due to limited information available in the literature, regarding use of PRF in management of periapical intrabony defects, aim of the present case series was to evaluate clinical and radiographic effectiveness of the application of PRF as a sole grafting material in the regenerative treatment of large sized (palatal) intrabony defects.Clinical reportFour systemically healthy patients were included in this present study (Table 1). Their chief complaint were persistent swelling and heaviness in the palatal region since 1 ” 2 months. On examination, tenderness was present in teeth involved with radiographic evidence of large periapical lesion more than 10 mm in size. Initial cause related therapy was performed to reduce the inflammation of periodontal tissues followed by endodontic treatment and restorations. The patients were reevaluated 3 months after the completion of endodontic procedure both clinically as well as radiographically. Surgical interventions were planned at these reevaluation sessions due to persistence of palatal swelling and associated large intrabony defect [Fig 1a &1b]. Clinical periodontal parameters recorded 3 months after completion of nonsurgical periodontal and endodontic therapy revealed no loss of periodontal support in the teeth involved. Final clinical and radiographic outcomes were recorded at 3 and 6 months of periapical surgery. Surgical techniqueBefore surgery, patients face was painted with povidone iodine solution (Troydine, Troikaa Pharmaceuticals Ltd.India). Presurgical mouth rinse with 0.2% chlorhexidine gluconate solution (Rexidine®, Indoco Remedies Ltd. India) was advocated for a minute. Local anesthesia was obtained by bilateral greater palatine nerve block and nasopalatine nerve block using 2% lignocaine with 1:80,000 concentration adrenaline (Ligno-AD Local Anesthetic, Proxim remedies, India). Using a surgical blade number 15 (Glassvan® Niraj Industries Pvt Ltd, India), which has small, curved cutting edge facilitating short and precise incisions, crevicular incision was placed palatally preserving the entire papillary inclusions in the flap. No labial or buccal flap was contemplated owing to non involvement of the said side. The full thickness flap reflection was advanced till the defect could be seen with all its extent and with all the possible visual acuity [Fig 2]. Debridement was performed to eliminate the entire cystic lining and the granulomatous content. Utmost care was taken for not leaving any granulomatous tissue especially in the undermined areas at periphery of intra-osseous defects. The surgical area was irrigated with sterile saline. Intra operative measurements were recorded using the University of North Carolina probe (UNC-15, Hu Friedy, Chicago, IL, USA). After complete debridement the diode laser of wavelength 980 nm (Doctor’s smile Laser wiser Doctor smile Italy 16 watts 980 nm) was used in noncontact mode for decontamination of the infected intrabony wound [Fig. 3]. This aided in resecting the apices of the offending teeth and accurate placement of suitable root end filling material like Mineral Trioxide Aggregate (MTA) (Proroot® MTA, Dentsply Tulsa Dental Specialities Johnson city, TN USA). For the resection of the root apices small round 1mm diamond bur (Strauss & Co. Haitech Medical Solutions, Mumbai India) was used along with the copious saline irrigation. Contra-angled handpiece was attached to the micro motor with medium speed for root cutting. Root end preparation was done obliquely which resected the apices of the involved teeth along with some lateral canals and also would allow the retention of root end filling material. The MTA was placed at root apices in isolation(Fig 4). After the placement and setting of MTA, the bleeding was induced into the walls of intra-osseous defect through micro-perforations using 1 mm round bur that would stimulate undifferentiated mesenchymal cells and help in regeneration through rapid acceleratory phenomenon (RAP) as bone tissue maintains a highly endogenous capacity for self-regeneration9. PRF was prepared according to the guidelines given by Choukroun et al12. 10 to 20ml of venous blood was withdrawn from the patients ante cubital fossa and then centrifuged at 3000 rpm for 12 minutes to obtain the buffy coat of PRF. The large sized intrabony defects were then filled with the PRF as a sole grafting material [Fig 5a]. Care was taken not to overfill the defect. Gentle pressure was applied to the surgical area with saline wetted gauze for one minute to readapt the mucoperiosteal flap. Lastly, the flap was approximated with 3-0 non resorbable silk sutures (Ethicon, Johnson and Johnson Ltd, Ethicon, US LLC) by simple interrupted suturing technique. [Fig 5b]Post-surgical care “After the surgery patients received cap. Amoxicillin 500 mg tid for 5 days to control bacterial contamination and tab. Ibuprofen 400 mg tid for 5 days. The patients were asked to refrain from mechanical oral hygiene measures post operatively until suture removal. During this period they were asked to rinse with 0.12 % chlorhexidine digluconate mouthrinse twice daily for 1 minute. The sutures were removed 10-14 days after surgery. The curetted specimen was sent for histopathological examination which confirmed the diagnosis of infected dental cyst with 3 of the 4 cases and radicular cyst with the remainder. [Fig. 6]Clinical outcomes – Primary wound healing was observed with good adaptation of flap margin, excellent continuity of interdental papillae and 100% wound closure in all the cases during early healing period. All treated sites healed uneventfully with no evidence of pain, sensitivity, swelling, pus discharge, redness or tenderness. Patients were enrolled in a stringent plaque control protocol with weekly recall for the first month followed by bimonthly professional teeth cleaning for subsequent 6 months.Baseline and 6 months post-operative clinical parameters of all 4 cases treated are presented in Table 2. All the four cases revealed uneventful healing and stable improvement in clinical periodontal parameters. Radiographs taken at 6 months follow up showed bone fill. Owing to the palatal defects occlusal radiographs taken with a standardized radiographic technique (XCP, Rinn, Dentsply Ltd, Surrey, UK) were independently evaluated by the three examiners. Radiographic periapical healing and clinical signs and symptoms was determined according to the criteria established by Rud et al14 and Molven et al15. It was classified as successful when the radiograph demonstrated complete healing of the former radiolucency or scar tissue formation, and no clinical signs or symptoms were present , doubtful when the radiographic healing was assessed as uncertain (some reduction of the former radiolucency) and no clinical signs or symptoms were present and failure when the radiographic presented with unsatisfactory healing (no reduction or even an enlargement of the former radiolucency), or clinical signs or symptoms were present14.It was further classified as- complete healing, incomplete healing (scar tissue), uncertain healing and unsatisfactory healing (failures)15. A specific healing category was chosen when at least two examiners agreed on same healing category. The final healing classification was based on the radiographic assessment as well as on the absence or presence of clinical signs or symptoms. (Table 3).Interestingly, on radiographic assessments all the comparative occlusal views taken at 3 and 6 months revealed marked radio opacity seen with intrabony region suggestive of almost complete bone fill. There was no evidence of recurrence of the lesion at 6 months follow up [Fig 7a, 7b]. Discussion Odontogenic cysts are the most common form of cystic lesions that affect the maxillofacial region. They are classified traditionally into two groups. Developmental group which are usually asymptomatic, but have the potential to become extremely large and cause cortical expansion and erosion e.g.: keratocyst and dentigerous cyst1. Second group includes inflammatory group like radicular cyst. Radicular cyst are the most common cystic lesions 1-3 and comprises about 52% to 68% of all the cyst affecting the human jaw2. Their prevalence is highest among male patients as compared to females, especially in their third decade of life. In the maxilla, the anterior region appears to be more prone to cyst development whereas in the mandible the radicular cysts occur more frequently in the premolar region1. Abramovitz et al9 discussed guidelines of case selection for apical surgery where they reported that treatment of 24.5% of the cases was impossible without surgical therapy. Success rate approaching 90% or above have been documented in several clinical studies8.Thorough evaluation is important to minimize surgical trauma and to create optimal conditions for debridement and subsequent root-end filling. Clinical parameters like patient’s esthetic demands, periodontal condition, gingival biotype and width of keratinized tissues, level of a restoration margin, extent and condition of lesion needs to be evaluated prior to surgery. Radiographic parameters consist of location and extent of the periapical lesion and status of the marginal periodontium8. The incision and flap design should be chosen according to clinical and radiographic parameters. If a cystic lesion extends towards the alveolar crest, an intrasulcular incision is the flap design of choice to have access to periapical lesion. In the present case series, palatal intrabony defect could be seen immediately after flap reflection as a result of loss of cortical plate. It is known that the lytic products of the dying cells in the cyst lumen release a greater number of molecules resulting in increase in the osmotic pressure of the cyst fluid. When osmotic pressure of the cyst fluid rises to a higher level than that of the tissue fluid, the latter diffuses into the cyst cavity so as to raise the intraluminal hydrostatic pressure well above the capillary pressure. The increased intracyst pressure may lead to bone resorption and expansion of the cyst. Also, the T- lymphocytes and macrophages in the cyst wall may provide a continuous source of bone resorptive metabolites, cytokines and matrix metalloproteinase-1 and -2. This explain the possible mechanism that could have resulted in resorption of palatal bone1. Following flap reflection, thorough debridement of bony cavity was performed to remove all the granulation tissue. This also aided in better visualization of defect margins and tooth apices. After debridement intra-surgical measurements were made to correlate defect size with that of radiographic measurements. It was found that the measurements in both cases were almost similar. This aided in appreciating postsurgical bone fill. The debrided tissue was sent for histopathologic examination to determine type of cyst. This is considered as gold standard for diagnosis as it not only aids in providing final diagnosis but also helps to determine prognosis and recurrence4, 8. Diode laser of 810 nm was used in non-contact mode in the bone cavity to achieve hemostasis, minimize the risk of contamination and also for its indirect benefits in reduction of post-operative pain4. Oblique root amputation was carried out to facilitate surgical removal of apical delta (root canal ramification), enhancement of access to apex, creation of a working surface for retrograde preparation, facilitate debridement of periapical tissue and observation of resected root end for presence of vertical fractures8. Root end filling was done using mineral trioxide aggregate (MTA). For root-end filling, a variety of materials have been propagated in the past. However, MTA appears to have become the gold standard for a root-end filling material. Clinical (comparative) studies have reported excellent success rates for MTA ranging from 90% to 92% (follow-up periods from 1 to 5 years)8 as it has excellent biocompatibility16, ideal adherence to the cavity walls8, and low solubility17, and cementogenesis at the cut root face, with deposition of new cementum onto the exposed dentin and MTA surfaces16,17. Micro-perforations were made into the bony cavity to induce bleeding that could aid as source of stem cells during healing. The RAP thus induced makes bone tissue maintain a highly endogenous capacity for self regeneration9. In the present study, we have hypothesized that PRF may provide a scaffold material for periodontal tissue regeneration. The suitability of PRF as a biologically active scaffold has been illustrated in a number of studies revealing proliferation and differentiation of osteoblasts and gingival fibroblasts8, 9. Clinical studies have demonstrated that PRF promotes soft tissue and bone regeneration10, 11, as well as periodontal tissue regeneration12, 13. PRF is generated from centrifuged blood and is strictly autologous. PRF results from a natural and progressive polymerization occurring during centrifugation. It predominantly consists of a fibrin matrix rich in platelet and leukocyte cytokines such as IL-1?, -4, and -6, and growth factors such as TGF-?1, PDGF and VEGF5. Fibrin gels exploit the final stage of the coagulation cascade in which fibrinogen molecules form self-dimensional fiber network6. PRF consists of a fibrin matrix polymerized in a tetra molecular structure, with incorporation of cytokines, platelets, leukocytes and circulating stem cells.6, 12. The intrinsic incorporation of cytokines within the fibrin mesh allows for their progressive release over time (7‘11 days), as the network of fibrin disintegrates9. Such a configuration implies an increased lifespan for these cytokines, because they will be released and used only at the time of initial cicatricial matrix remodelling (long term effect). Therefore, the easily applied PRF membrane acts much like a fibrin bandage, serving as a matrix to accelerate the healing of wound edges and hence was used as sole grafting material. Patient in the present case series reported less discomfort. This could be attributed to prescription of antibiotics and analgesics post-surgery. With regard to healing outcome, the classification of healing should be based on defined clinical and radiographic healing criteria8. Interestingly, soft tissue healing following apical surgery has rarely been addressed in the literature, where the focus has always been on the periapical healing. In the present study soft tissue healing was satisfactory with no evidence of any pain, infection, swelling or postsurgical recession. The bone fill as adequate which was determined by radiographic evaluation at 3 and 6 months follow up.