Key Engineering Materials Vol. 587

Abstract: In this study we evaluate a new computer software developed for determining tooth color parameters obtained from digital images taken in a general practice working conditions. In order to evaluate the accuracy of the program, we used as samples dental shade tabs. The tabs were measured using a dental spectrophotometer, and then photographed and measured using our program (Toodent). L, a, b values of the CIE Lab color space were obtained. The results were also automatically expressed in dental shade tab code. The results analysis was made by comparing the L, a, b values obtained by the program, with spectrophotometer ones taken from the same shade tab. A statistical indicator was created in order to evaluate the accuracy of the program. Further evaluation of the program shall be made, in order to be used in routine clinical color selection.

Abstract: In this paper we have focused on the study of the thermal expansion coefficient of a dental alloy, WBC, and its compatibility with a ceramic mass ,VITA VM 13, following thermal treatment according to the technological stages of production of a metal-ceramic prosthetic restoration.

Abstract: An endosteal implant is an alloplastic material surgically inserted into a residual bony ridge primarily as a prosthodontic foundation. Root form implants are the design most often used. Although many names have been applied, the 1988 National Institutes of Health consensus, statement on dental implants and the American Academy of Implant Dentistry recognized the term root form. Misch developed a generic language for endosteal implants in 1992. This language is presented in an order following the chronology of insertion to restoration. In formulating the terminology, five commonly used implant systems in the United States were referenced. Ten years later, the dramatic evolution in the implant market led to reconsideration of the terminology. At the moment, over 3000 different implant systems are on the market, but the comparative evaluation is not done by objective means.

Abstract: The association of Micro Macroporous Biphasic Calcium Phosphate granules and t fibrin sealant has been developed to answer a challenging request of orthopaedic surgeons: a biocompatible, osteogenic, mouldable, and self-hardening bone substitute able to fill bone defects. The aim of this study was the evaluation of the performance and safety of the bioactive composite in regeneration of functional bone. A clinical study design was set up as an exploratory prospective French multicentric phase II study sponsored by INSERM. The application was the HTVO (Tibial Osteotomy of Valgisation) using osteosynthesis and bone substitute (BS) for filling the space created. The follow up was 12 months with safety checks, clinical assessments, high-sensitivity X-ray, and CT-scan imaging. A bone sample was collected from the reconstructed area at 12 months. 13 patients with stage I gonarthrosis have been included in the study. This clinical follow up revealed only one case of correction loss. X-ray and CT-scan imaging indicated a progressive disappearance of the peripheric radioluency and a decrease of the radiopacity of the implanted area due to bioceramic resorption and bone ingrowth at the expense of the implant. Histological analysis revealed BS large resorption and bone ingrowth both into the pores and at the expense of the bioceramic. X-Ray and micro CT scan revealed a well organised and mineralised structure in the newly-formed bone.

Abstract: the study tried to evaluate the advantages of mini-invasive prophylactic synthesis of controlateral hip fractures in osteoporotic patients. Material and method: 4 patients have been operated between 2009-2010 with hip fractures in osteoporotic patients. Neck fractures Garden IV in 2 patients and pertrochanteric fractures Kyle III and IV in two others patients. The fracture site was operated in dorsal decubitus under spinal anesthesia, we took adventage of this operation and anesthesia to performe a minimal invasive percutaneous synthesis for the nonfracture controlateral side. We used a simple implant, a quickly method during the same surgery time and anesthesia. The K wires with injected cement were percutaneously inserted. Through a 5 mm skin incision, a channel is created in the proximal femur bone and the implant, made of a fabric pouch hosting Titanium rods, is built percutaneously within the femur. A small amount of bone cement is then added, and interdigitates to the osteoporotic bone to further fixate the implant. Results: Rehabilitation was obtained and full weight bearing was allowed immediately. The potential benefits expected with the use of this minimally invasive method are: Quick procedure 15 min, No soft tissue or bone damage, No bleeding, short rehabilitation period, reduced morbidity and mortality, Low cost, same drape, single anesthesia. Conclusions: The method is simple, reproductible and economically. It can be made in emergency by the resident surgeon. The patient will be operated during the same anesthesia after the operation of fractured hip.

Abstract: Different methods are available for fixation on the femoral side of a quadruple soft tissue autograft in anterior cruciate ligament reconstruction and the best method is still to be found. There are also a large number of polymers in current practice, with a trend towards ceramic composites, required for better bone formation around the implant. If ceramic – polymer composites have better bioactive properties can be demonstrated only by long term in vivo follow up. Several methods of trans-femoral fixation are currently in use in our clinic – two of them being compared in this study: Rigidfix (Mitek DePuy Westwood, MA) and Biosteon (Stryker). First system produces a very stiff fixation using two implant pins made of poly-L-lactic acid (PLLA); the second technique is using a large composite (25% hydroxyapatite and 75% PLLA) suspension system with the mechanical advantage of achieving a “ press-fit” graft fixation in the tunnel. We prospectively follow our cases with clinical visits at 1, 3, 6 and 12 months – for research purposes, in a series of 20 cases (10 from each group) MRI (Siemens, 1,5 Tesla) were performed at same time intervals. Volume loss of the implant, tunnel enlargement, presence of osteolysis, fluid lines, edema and postoperative pin replacement by bone tissue were evaluated. There was no edema or signs of inflammation around the bone tunnels at more than 24 months of folllow-up. Several of the Biosteon sites were surrounded by an area of increased signal on the fat-suppressed images. At 12 months, the femoral implants showed an average volume loss of 80% (±10%) P\0.05), respectively. At 3, 6, and 12 months volume losses range from 5 % (±2%), 29% (±19%) and 89% (±7%) for the composite implant. The femoral tunnel enlargement was less than 50% of the original bone tunnel volume after 12 months. Bone ingrowth was observed in all patients. Use of a composite ceramic – polymer bioabsorbable material (enhanced to form bone) will be easily incorporated by the body, retain strength for an adequate period of time, obviate the need for secondary procedures such as hardware removal, and facilitate revision surgery.

Abstract: Antibiotic delivery systems used in the past have consisted primarily of impregnated cement beads that required routine removal once the antibiotic had eluded completely. With the development of collagen scaffolds that could be used to fill bony defects the antibiotic cold be delivered from the scaffold used to sustain local bone growth. Over the course of two years antibiotic loaded collagen scaffolds were used in the local treatment of 21patients suffering of complicated fractures including bone defects, infections or pseudoarthrosis, all of them of traumatic nature. At the time of the initial surgical debridement or at subsequent second look procedures once local tissue viability was observed the antibiotic loaded collagen scaffold was inserted in the tissue defect and never removed. Excellent results were obtained and the infection was brought under control by use of both surgical and antibiotic modalities. Bone grafting was used in 6 cases where the defects were extensive. Where there was less extensive bone destruction the scaffold was a good adjuvant in new bone formation. Use of antibiotic loaded collagen scaffolds is a reliable and effective means of local antibiotic delivery system combining both the new bone formation capacity of the scaffold to hold osteoblasts with the ability to deliver high doses of antibiotic in the local tissue environment and thus avoiding the systemic toxicity.

Abstract: Sever acetabular defects can usually be addressed with a standard acetabular cage. The procedure is more complicated, as standard devices have to be adapted to different shapes of acetabular defects, especially when they are bigger and widespread. The proposed cage tries to fix problems that standard cages sometimes do not resolve for example insufficient fixation due to the fact that the inferior flange did not engage the ischium, graft resorption and at the same time tries to remain affordable. The implant is being built based on the 3D reconstruction of the patient hip from CT scans with the help of additive technologies and uses standard components (cup, screws). The particular implant was designed and produced and it is available for patient implantation. The proposed solution offers a better fit alternative for the patient but realization of the implant is very time consuming, although a systematized process was tried and achieved.

Abstract: Vertebroplasty is a minimally invasive surgical procedure, which requires efficacious percutaneous cement delivery via a cannulated needle to restore the strength and stiffness in osteoporotic vertebral bodies. Cement viscosity is understood to influence the injectability, cohesion and cement retention within the vertebral body. Altering the liquid to powder ratio modifies the viscosity of bone cement; however, the cement viscosity-response association between cement fill and augmentation of strength and stiffness is unknown. The aim of this study was to determine the relationship between viscosity, cement fill and the potential augmentation of strength and stiffness in an open pore foam structure that was representative of osteoporotic cancellous bone using an in vitro prophylactic vertebroplasty model. The results showed a strong linear correlation between compressive strength and stiffness augmentation with percentage cement fill, the extent of which was strongly dependent on the cement viscosity. Significant forces were required to ensure maximum delivery of the high viscosity cement using a proprietary screw-driven cement delivery technology. These forces could potentially exceed the normal human physical limit. Similar trends were observed when comparing the results from this study and previously reported cadaveric and animal based in vitro models.