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Journal of Oral Science & Rehabilitation Volume 2 | Issue 2/2016 51 S p o n t a n e o u s b o n e r e g e n e r a t i o n : A n a l y s i s o f 3 3 6 c a s e s Introduction The gold standard forthe treatment of most jaw cysts is enucleation ofthe lesions. The cavity re- mainingafterenucleationmayhealspontaneous- ly by the physiological appositional mechanism ofbone growth. However, in largerbonydefects, the use of bone grafting materials is still contro- versial.1–13 Many studies have concluded that bone grafts should be used to reduce the risk of jaw weakness.14–18 Some researchers have sup- ported that the remaining cystic cavities should be filled with biointegrative materials to prepare the site for implant placement.19 However, other authors have reported that spontaneous bone healingoccurredwithouttheuseofbonegrafts.20 According to this last study, bone density can increase by 48% after 12 months and by 91% after 24 months, as seen after marsupialization of large jaw cysts. The success of spontaneous regenerationshouldbedirectlyrelatedtothesize ofthe bonydefect, anatomicalfeatures, patient’s age and other parameters, such as monocortical or bicortical defect type.19 The objective of this retrospective clinical studywasto evaluate spontaneous bone regen- eration after enucleation of large jaw cysts, achievedwith a conservative surgicaltechnique, without using any filling material. Materials and methods This study was conducted at the Department of Oral Surgery of the San Giovanni Calibita, Fate- benefratelli Hospital, Rome, Italy, from January 2000 to July 2012. All consecutive patients re- quiring a Partch II surgical intervention for cyst removal were enrolled. Each patient was com- pletely informed about the possible risks of the intervention and the surgical procedure. P r e o p e r a t i v e a n a l y s i s Panoramic radiographs were obtained for all of the patients subjected to surgical enucleation (Fig. 1). The dimensions of the cysts were evalu- ated on panoramic radiographstaken just before surgical treatment. A preoperative computed tomography(CT) scanwas required onlyin cases of very large jaw cysts with erosion of cortical plates, in order to evaluate more precisely the extent of the lesions (Fig. 2). S u r g i c a l p r o t o c o l The surgery was conducted by one surgeon (MDD) in a single session for each patient, with standardized techniques. All of the patients re- ceived antibiotics before surgery. Local antimi- crobial treatment was performed with 0.12% chlorhexidine digluconate mouth rinses t.i.d. for two weeks, starting three days before surgery, interrupted only on the first postoperative day. The majority of the surgeries (93.5%) were per- formed under local anesthesia with 2% mepi- vacaine.Only22(6.5%)surgicalprocedureswere conducted under general anesthesia (in cases of cysts entering into the nasal cavity), depending on the general conditions, compliance, local and anatomical characteristics (such as the lesion extent), the site accessibility and the expected duration of the surgery. When the cysts were placed into the anterior region of the mandible, bilateral local anesthesia at Spix’s spine with 2% mepivacaine and infiltrative anesthesia with 2% mepivacaine and 1:100,000 epinephrine was administered. After the elevation of a full- thicknessflap ofadequate dimensions,withtwo lateralreleasingincisionsonthevestibularaspect (to preserve the lingual nerve in the mandible; Figs.3&4),conservativeaccesstothelesionwas obtained using a round burin a low-speed hand- piece under irrigation with sterile saline (Fig. 5). In all of the cases, there was very little bone de- bris, owing to the minimally invasive surgical approach. Particular care was taken to preserve the maximum amount of bone in order to allow postoperative regeneration of the defect and to provide adequate support to the soft tissue duringthe healing period (bone bridging).When- ever possible, the cysts were enucleated in one piece with minimal invasion. The remaining cyst cavity was curetted to remove all residual frag- ments and to reduce the risk of recurrence (Fig. 6). The hopeless teeth were either extract- ed orendodonticallytreated,followed byapicec- tomy.Inallofthecases,afterthecarefulcleaning ofthe residual cavity, a primary closure was per- formed with a nonresorbable thread and inter- rupted sutures. No grafting material was placed into the residual bone sites. In all of the cases, a histological examination was performed, after fixation in a 4% formalin solution (Fig. 7). The patients were advised to refrain from drinking and eating for 2 h afterthe surgical pro- cedure andtothen eat onlycold and softfoodfor 24h.Afterten days, upon removalofthe sutures, the wound was examined and controlled. Volume 2 | Issue 2/201651 S p o n t a n e o u s b o n e r e g e n e r a t i o n : A n a l y s i s o f 336 c a s e s