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KMID : 0941120020020050110
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Journal of Implant Dentistry
2002 Volume.2 No. 5 p.110 ~ p.126
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An Experimental and Clinical Study of the malpositioned Block Bone Repositioning with a Preosseointegrated Implant
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Kwon Jong-Jin
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Abstract
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To make the existing fixed and removable partial dentures as the prosthetic treatment for the lost tooth or teeth, we have to reduce the adjacent teeth and some weak points such as poor position, instability of dentures and feeling like foreign bodies can occur. Many experimental studies and clinical experiences shows that endosseous implants can settle these problems successfully, and so the current implant dentistry including various techniques to serve the anatomical obstacles and inadequate quantity and quality of bone at the implant placement area.
But in clinical point of view, when we try to place implants in the position and angulation in which it can be covered with the remaining bone of the poor amount of residual ridge, though we try hard to correct the bad result by prosthetic compensation ultimately increased volume of prosthesis can give the difficulty of lip movement, poor esthetics, poor maintenance of oral hygiene, masticatory dysfunction. In sever cases, it is even impossible to compensate for these problems. As repositioning techniques to correct malaligned implant in the poor position and angulation, there are segmental osteotomy and trephination repositioning technique.
The repositioning technique can be used to trasplant the osseointegrated implant in the area of good bone quality to the area of poor bone quality and to correct the malaligned implant surgically.
The aim of this study was to observe the healing process of a block bone with an osseointegrated implant after repositioning it and to evaluate the efficiency of this technique in implant surgery.
Two weeks after extracting the mandibular P1s, P2s, P3s in both sides of five mongrel dogs, one implant was placed in each side of mandible. Three weeks after implant placement, the block bone with an osseointegrated implant was harvested by trephination and made reposition buccolingually from its own position by bone chips, which were harvested from adjacent bone. Each dog was sacrified at the 1st, 2nd, 3rd, 6th and 12th week after repositioning and clinical, radiological and histological observations were made.
The results were as follows:
1. Success group showing bone formation at the 1st and 12th week and failure group showing bone resorption and bone necrosis from 2nd week to 6th week appeared.
2. At the 1st week, after repostioning of a block bone with an osseointegrated implant, active new bone formation in the trephined area was seen.
3. At the 12th week, it was so good healing that it was difficult to differentiate the block bone from its surrounding bone even in comparison of both the trabecular bone patterns. Thickened trabe-cular bone at the trephined area was observed.
4. From the 2nd week to the 6th week, bone necrosis and bone resorption was shown.
5. At the 3rd and 6th week, because of active bone formation at the apical 1/2 and apical 1/4 area respectively, it was difficult to discriminate the trephined area.
From the above results like that after repositioning a block bone with an osseointegrated implant, bone formation at the 1st and 12th week and bone resorption from the 2nd week to the 6th week occurred, it was thought that the trephination repositioning technique was so tech-nically sensitive that it could call its efficiency as an implant surgical technique in question, but it would be necessary to reevaluate it after improving its problems through the surgical technique to reduce the deducible surgical traumas like the frictional heat by trephination and poor fixation.
So to prevent them, it is recommended that firstly, internal irrigation method or external irrigation method with chilled normal saline solution or combined method would be more efficient to reduce the frictional heat during trephination and secondly, the block bone of an osseointegrated implant could be more stabilized by densely packing the gaps with autogenous bone chips or putting it by friction into the repositioning hole which is prepared with the smaller diameter of the trephine or drill than that of the trephine used when harvesting it.
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