engleski

The use of allogenic bone blocks in alveolar bone regeneration

BACKGROUND: Tooth loss, trauma or infection can lead to alveolar bone defects. Prosthetic driven implant placement can be prevented in clinical situations where inadequate bone volume is present.Thus, different bone augmentation procedures are indicated to correct lost bone volume. Onlay bone grafting is considered to be a safe technique for horizontal bone regeneration with a low complication rate of only 3.8%.. Autogenous bone was and is still considered asa gold standard because it possesosteoinductive, osteoconductive and osteogenttic potential. There is no other bone grafting biomaterials that posses all of these feauters. Despite these advantages, autogenous bone blocks have also some drawbacks: high morbidity as a consequence of two surgical sights, lower patient acceptance, limited amount of intraoral bone available for harvesting and slow and incomplete revascularization. In certain clinical situations, these disadvantages may reduce or even endangerbone regeneration. Alogenic bone blocks can be considered as a valuable alternative to autogenous bone block because surgical procedure is faster, with less demanding surgical technique and it requires only one surgical sight, better patient acceptance, unlimited amount of avaliable bone graft and faster and complete revascularization. AIM: The aim of this poster was to present two surgical techniques for horizontal bone regeneration using allogenic bone. In the first case an onlay bone block was used with an individualised and preshaped allogenic bone block. The bone block was trimmed, using a preoperative dental computed tomography and a CAD_CAM technique. In the second case, bone grafting was performed with the shell technique using a thin(0.9 mm) allogenic cortical plate and a particulate autogenous bone graft. Material and methods A 40 year old patient presented in the office with a partial tooth loss of the maxillary posterior quadrant. After the initial exam and CBCT analysis of the edentulous area, the following treatment plan was proposed to the patient: sinus lift using mixture of xenogenic and autologous particulate bone and horizontal bone regeneration in the premolar region using a shell technique with allogenic bone plate and a particulate mixture of autogenous bone graft. The sinus was grafted with a mixture of xenogenic and autogenous particulate bone. The inner surface of the allogenic bone plate was adapted at the level of the future buccal bone and secured using three ostehosynthsis screws. The gap created between the alveolar bone and the allogenic plate was grafted with autologous particulate bone harvested form the mandibular lateral edentulous area using a disposable bone scraper. A 38 year old systemically healthy and nonsmoker, female patient was referred to a private dental practice with the diagnose of partial edentulisam in the frontal maxillary region, combined with horizontal ridge resorption. After the initial exam and consultation the patient decide for horizontal bone augmentation by means of allogenic bone block preshaped with cad-cam system. A full thickness crestal incision was made continuing with two divergent vertical incisions, placed on the buccal aspect, two teeth away from the surgical site. Afterwards the block was fitted into the defect and stabilized with two osteosynthesis screws with lag screw technique. The grafted area was covered with a xenogenic particulate bone and resorbeable collagen membrane. RESULTS: Alveolar ridge defects were regenerated with allogenic bone using two different techniques. In the first technique the bone block was preshaped in advance avoiding the need for bone block harvesting and adaptation to the bone defect morphology.In the second technique thecortical allogenic bone plate are used for the reshaping of the alveolar crest providing a more stable morphology of the bone defect. The cortical plate prevents the resorption and dislocation of the particulate bone, while it's reduced thickness of only 0.9 mm, leavesenough space for the autogenous particulate bone. Using the allogenic cortical plate the surgical procedure is simplified eliminating the need for harvesting and extraoralthinning of the autologous cortical plate. The result that was obtainede from both regeneration techniques enables prtosthetic driven implant placement. CONCLUSION: Allogenic bone can be considered as a valid alternative to autogenous bone. With the use of allogenic bone blocks alveolar bone regeneration of complex defects can be performed with minimal morbidity, decreased technical difficulties and consistent outcomes.

alveolar bone regeneration ; allogenic bone blocks

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