Alveolar Mandible Osteoplasty with Combined Bone Transplants

Introduction. There are various osteoplasty methods aimed at managing the challenge of jaw atrophy. When the scope of the osteoplasty is extensive it is not always possible to prepare an appropriate amount of bone tissue without additional surgeries. In some cases there is a lack of intraoral bone tissue sources for this kind of operations. Using extraoral sources of bone tissue is not always justified; it is invasive and patients take longer to recover and return to work. Using alternative sources of bone biomaterials might help establish a less invasive osteoplasty protocol.Goal. To demonstrate the efficiency of alveolar ridge osteoplasty with the application of laminar technique and using various combinations of autograft and allograft tissues.Materials and methods. To achieve the goal set we have examined and treated fourteen patients (N=14) surgically. All patients presented a clinical picture of severe atrophy in dentoalveolar segments 3 and 4, knife-edged ridge, Cawood and Howell class IV–V. Depending on the combination of autograft and allograft biomaterials patients were split into three study groups and one control group.Results and discussion. Positive outcomes for the treatment administered were observed in 13 out of 14 patients. Complications were determined by the lack of soft tissue, exposure of the graft or its suppuration. All the patients in all the groups underwent a control CT which confirmed the bone tissue growth at the area of the augmentation performed.Conclusion. Using the bone biomaterial allograft in combination with autograft bone makes it possible to get good clinical results in all the groups observed. This method may be a method of choice eliminating the additional invasive procedure of bone transplant harvesting; it does, however, require further, more detailed research.

How Cadaver Bone Transplants Mineralize and Sclerotic Bone Fails

Cadaver bone is possibly the most common transplant material used today. Common types of cadaver bone transplants are freeze dried bone allografts and xenografts. In the case of freeze dried bone allograft transplants, it was theorized that these materials mineralize by way of osteoinduction and stimulating osteogenesis. However, these theories have been proven false. It has been proposed that these materials mineralize via osteoconduction however, there are no studies to support this hypothesis. This study was undertaken to determine how these transplants mineralize and what type of bone they produce.  Materials and Methods: This study is a histological analysis of human cadaver bone graft healing from the incipient stages of mineralization through completed mineralization. All cadaver bone grafts used for evaluation in this study were particulate bone graft materials in the maxilla or mandible. No block grafts were evaluated. Results: The mineralization of cadaver bone transplants was produced by an inflammatory response to the transplanted tissue. The histologic findings of the mineralized bone produced by this process was sclerotic bone.  No resorption of cadaver bone graft particles was found. When loaded the sclerotic bone was found to fail through an accumulation of microfractures.Conclusions: Particulate freeze-dried bone allografts and xenografts do not heal via the normal processes of mineralization. Cadaver bone grafts produce significant inflammation and are hypothesized to mineralize by a process termed antigenic ossification. The process of antigenic ossification produces sclerotic bone that is not capable of self-repair which can ultimately lead to bone failure.

Fractal Geometry Rooted Incremental Toolpath for Incremental Sheet Forming

Single point incremental sheet forming (SPISF) technique is an emerging process for die less forming. It has wide applications in many industries viz. automobile and medical bone transplants. Among several key parameters, toolpath planning is one of the critical aspects of SPISF. Also, formability and geometric accuracy have been the two major limitations in SPISF. Spiral and constant incremental toolpaths and their variants have been investigated in detail by several researchers. Fractal-based toolpath planning is also an attempt to improve the process of SPISF. Formability is measured in terms of thickness distribution and maximum forming depth achieved. This paper investigates a fractal geometry-based incremental toolpath (FGBIT) strategy to form a square cup using incremental sheet forming (ISF). Fractal toolpath is a space-filling toolpath which is developed by the fractal geometry theory. A comparison-based study is conducted to observe the benefits of using FGBIT over traditional toolpaths (spiral and constant Z). Better formability, stress, and thickness distribution have been observed by adopting the proposed toolpath strategy. This toolpath strategy is new in its kind and has not been investigated in the metal forming domain. Experiments and simulations are conducted to validate the concept with reasonable accuracy.