Hydroxyapatite as a Substrate for Bone Reconstruction

Hydroxyapatite as a Substrate for Bone Reconstruction To combat the shortcomings of autografts and allografts associated with limited availability of tissue, morbidity of the donor site, risk of disease transmission and immunogenic rejection; clinicians have started centuries ago implanting artificial materials in the body to aid and restore functioning of organs or tissues.1-6 The high incidence of morbidity, skill required to harvest bone from donor, and so many factors have been the rationale for the increase in applications of bone substitute materials.7-9 Hydroxyapatite (HA) ceramics produced synthetically or by processing biological substrates and is used widely and successfully for bone reconstruction. There are many natural sources for HA which include human bone, bovine bone1,2 coral3,4 chitosan5,6fish bone7and egg shell8, and so. However a concern with natural HA is risk of transmission of diseases when proper preparation is not followed to remove all protein9. Synthetic HA is more commonly used, because of easily availability, and free from disease transmission risk. HA are available as granules and blocks with different pore sizes or as injectable material. HA is osteoconductive in nature and serves as a structural scaffold for the building of new bone tissues. Several authors have suggested HA is prone to intraoral degradation or dissolution10-25 but others have shown no resorption13-22 like our case. Here we report clinical cases which showed the radiological evidence of bone formation after more than 4 years of follow up. Clinical Report 1- In our study group the Male patient aged 65 yrs had recurrent OKC on lateral part of the mandible (Figure-1) which required partial hemi mandibulectomy with disarticulation. Patient was not ready for any other modalities of reconstruction except condylar stainless steel recon plate. Considering patient age and denial for distant or free flaps, our team of doctors inspired by orthopedic replacement strategies and indigenously designed hydroxyapatite block. Which has been prepared by Biograft (IFGL Ceramics Kolkota, India) on request. This has been used for reconstruction of lateral mandibular defect distal to canine. The block fixed to stainless steel condylar plate using 26 gauze wires. (Figure-2 Figure-3)After 5 years of evaluation the patient had no complications, absorption, dislocation but very little bone formation seen radiologically (Figure -4, Figure-5 Figure-6). Clinical Report 2- The Male Patient of 20 yrs, reported to our department with swelling in anterior mandible since 8 yrs which was small initially and progressively grown to the present size.( Figure-7) Under general anesthesia the lesion has been resected leading to a mid-line defect. The patient denied for any other reconstruction options including distant flaps and free flaps because of affordability. So it is decided to have reconstruction using SS recon plate with a block graft for support. (Figure-9) In this case we are expecting connective tissue and later bone formation as the graft block is in contact with the bony edges on both sides. Clinical report 3- Case of unicystic ameloblastoma in a patient aged 55 years male crossing the midline, undergone resection and reconstruction using BBHA and SS reconstruction plate. (Figure-9 Figure-10) In this case we are expecting bony bridging between interface of the bone fragment and graft end on both midline and ramus area of mandible. Surgical Considerations: The surgeon should change gloves before handling the BBHA material because oral flora and debris previously picked up on gloves during the pre-grafting stages of surgery could contaminate the BBHA, resulting in a subsequent infection. In its initial form, BBHA is brittle and must be handled and shaped carefully so it does not inadvertently fracture, although the material becomes very strong after healing. It is important to use irrigation when cutting the individual grafts from the larger blocks with a bur and when refining the contours. BBHA grafts can be used as interpositional (inlay) grafts placed between osteotomies or as facial augmentation (onlay) grafts or for mandibular reconstruction of lateral/midline defects. They can be applied to the maxilla, mandible, chin, orbit, zygoma, nose, forehead, and cranium. Onlay grafts may require stabilization by placing bone screws through the material, as in BBHA chin or cheek onlay grafts. A lag screw/wire technique should be used with m inimal tightening to prevent fracturing of the grafts. Rigid fixation is paramount to provide the necessary stability and stress protection for the BBHA grafts to heal properly. The grafts in the maxilla should be accurately contoured and wedged in position. If there is excessive mobility between the bone segments and BBHA grafts or a functional overload, the grafts may displace or fracture. Alternatively, a significant decrease in the amount of bone growth through the implants could occur, resulting in a nonunion. A soft diet is encouraged for 3 to 4 months during the initial post-surgery healing phase to minimize loading and micro movement, thus preventing displacement, fracture, or nonunion of the grafts. The use of 4 bone plates is recommended to stabilize the maxilla, with 2 bone screws above and 2 bone screws below the level of osteotomy for each bone plate.47,48 Postsurgical displacement or fragmentation of the BHA grafts can occur as a result of the following:38 1. Inadequate rigid fixation and stress protection, 2. Improper contouring or placement of the implant into the osteotomy site, 3. Parafunctional habits (i.e., clenching, bruxism), 4. Poor patient compliance, 5. Trauma. Discussion: The use of bone graft material both particulate12,14,16,18,19,21,38-40,54and block graft13,15,17, 19,20,22,23,41 studied in humans and animals. The majority of animal studies found bone formation within graft material10,11,18,42-51 and others reported connective tissue formation.43,52,53 The human studies reported formation of bone 12-17,29-32,37-40,54 and others reported connective tissue surrounding HA particles.18,19,29 Long-term retention biocompatibility of BHA has been established fact in orthognathic and craniofacial surgery.50 Histologic studies29,30,35 and a long-term clinical study demonstrate good biologic acceptance of the grafts in association with the maxillary sinus. The immobility of HA is crucial factor for initial healing20 as mobile particles induce connective tissue formation and immobile foster bone formation. Wolford et al. introduced the use of porous BHA as a bone graft substitute in orthognathic and craniofacial surgery.30 Rosen and Ackerman reported complication rate of 4.3% after a follow-up period of 6 to 20 months in orthognathic surgical BHA grafting48,49 Ayers et al17 Holmes et al31 and Nunes et al.16 demonstrated an average composition of 48.5-53% hydroxyapatite matrix, 18-27% bone, and 33.5-21% soft tissue in BBHA grafts through histomorphometry after 4.7 to 16.4, mean 19.1 months respectively with biopsies of BBHA grafts which were used in corrective jaw surgery in patients. The composition of the adjacent normal maxillary and mandibular bone averaged 66.5% bone and 33.5% soft tissue, indicating that the ratio of hydroxyapatite/bone to soft tissue/vascular space is equivalent to normal bone.17 The study also demonstrated that bone growth through the BBHA grafts was essentially complete in 4 months, with further progression of the healing process resulting in maturation of the ingrown bone. The grafts had less soft tissue than the adjacent bone (30% soft tissue) and bone contact over 60% of their surfaces which is a near-balance between the BBHA grafts and surrounding bone.16 There was no significant difference in micro hardness values between the bone in the BHA grafts and the adjacent maxillary bone.17 Bone ingrowth appeared to plateau at around 20 months, reaching an equilibrium in which the relative amount of osseous tissue remained constant. 17 Different theories proposed on the mechanism of bone formation. Early vascularization followed by connective tissue formation16,43,44 bone gradually inserted around the HA particles21,43,44 and non-inducing creeping substitution21,22 also proposed. Very recently the bone induction has been seen with nano-crystalline HA. The use of BBHA as an alloplastic grafting material has several advantages over other types of grafts: no donor site morbidity is involved, adjacent bone will not be resorbed, there is no known hypersensitivity or immune response, the substance is easily manipulated, there are no working time constraints, surgical time is decreased, blood loss is decreased, the volume is unlimited, and healing is faster resulting in a shorter recovery time. Interpositional bone grafting is indicated in orthognathic surgery to provide bony continuity, improve healing, improve stability, decrease surgical relapse in traditionally unfavorable jaw repositioning movements during orthognath ic surgical procedures. This type of reconstruction options will increase the survival rate and lesser morbidity. The incorporation of autogeneous bone, platelet rich plasma, rhBMP-2 showed good bone formation.50 The studies have shown hydroxyapatite is osteoinductive.51,52 Recently studies have shown use of Platelet derived growth factor (PDGF), transforming growth factor ÃŽ ² (TGF-ÃŽ ²), BMP, and stem cells in bone regeneration.50 The BBHA will provide structural architecture for BMP to achieve better and earlier function. These laboratory concepts were regarded a visionary a few years ago, but now they reached clinical reality.53-59 Our report is milestone in reconstruction of continuity defects of mandible. Hydroxyapatite is a versatile biocompatible graft substitute that does not cause any chronic inflammatory, allergic, or toxic reaction. Results of both densitometric and radiographic studies suggested that the use of synthetic hydroxyapatite graft material has the potential to accelerate bone formation in an economical way.60-63 Conclusion: The primary aim of the reconstruction was to have a proper face form, aesthetics and structural balance for face which has been achieved in a very economical way. Our plan to have implant supported prosthesis in the HA blocks in near future for these patients is planned. This type of reconstruction with indigenously designed and prepared block graft can suffice the aim and objective of successful reconstruction which is a viable modality economical. No clinical signs of pathosis were identified around the graft, no infection or discomfort was elicited upon palpation.

Alaska vs Florida

Alaska is different from Florida in several ways such as the time zones. In Alaska the time is four hours behind the time in Florida. Another way they are different is in the place that they are on a map. Alaska is in the North West and Florida is in the South East. These two places also differ in climate. In Alaska the climate is cold, while in Florida there is a tropical climate. Along with different climates come different temperatures.In Alaska the normal temperature in the summer is about fifty degrees Fahrenheit. In Florida the normal temperature is about ninety. In Alaska the sky has constant darkness for about three months, but in Florida there is normal daylight. Alaska is also different from Florida by the size. Alaska is larger that Florida in land mass. Florida has a greater population than Alaska, however. Alaska allows you to get your learner’s permit to drive when you turn fourteen.Florida allows you to get your learner’s permit at the age of fifteen. The last ways that these two states differ are the natural resources. In Alaska the natural resources are gold, fish, and fur. On the other hand, in Florida the natural recourses are oranges, sugar cane, seafood, cows, the ocean, and natural spring water. Although these states have many differences, they also have some similarities. Both Alaska and Florida are states in the United States.Florida and Alaska are also both peninsulas, a land that is almost completely surrounded by water but connected to the mainland. Both of these places have many fun things to do. In Alaska you can ski, ice skate, play ice hockey, snowboard, or go sledding because most of the year there is snow on the ground. In Florida you can go to the beach, go surfing, play volleyball, go to the boardwalk, or go to Disney World.

A Significant Person Essay

Significant Person Mother Teresa is one of the most admired women in the world. She dedicated every day of her adult life to caring for and loving the dying, the unwanted and the unloved. Her spirit of giving inspired many people. There were those who gave up their lives as she had to follow her and others who helped in different ways, for example, giving her the Kali Temple to be used as a home for the dying. The effect Mother Teresa had on the people she came in contact with and the world is one of the most intriguing things about her. But what was it about Mother Teresa that made people stop and listen? How did such a tiny women touch the hearts and lives of so many people? Mother Teresa’s dedication to God and the church is what I feel made her so great. Everything she did in her life was for God. One of the first instances that made me really stop for a second was Mother Teresa’s second calling. It was not the calling itself so much as how she handled herself in the following events. She was so dedicated to the church and her vows that she waited two years before she was able to be released from her vows to go off into the world to serve the poorest of the poor. She went through all the proper and necessary steps in the church to get what she believed was her calling. Mother Teresa did not leave the church for selfish reasons, nor did she just get up and leave one day. She had too much respect and devotion to the church to be able to do something like that. Mother Teresa put all her faith into God and believed that he would provide her with what she needed. All throughout her years on the streets of Calcutta, Mother Teresa never asked for money. She knew that all she needed was her faith. For me, I find that aspect of her remarkable. How someone can have so much faith that they would go out with nothing but 5 rupees amazes me. And the best part of the whole story is that God does come through and provide her with everything she needs. She called it â€Å"divine providence† because she never asked, however things like money, helpers and buildings became available to her. In her interview with Muggeridge she said, â€Å"Faith is a gift of God. Without it there would be no life. And our work, to be fruitful and to be all for God, and beautiful, has to be built on faith. † Her faith is why she always began each day with prayers, meditation and Mass. I see this as her time to be one on one with God and receive the strength she needed to serve the Lord each day. Many people go to church each week, however never truly experience God the way Mother Teresa did. She was truly able to see him in everything she did and everyone she came into contact with. While I personally would have a hard time seeing Christ in people I come into contact with, Mother Teresa did. I have never been a very religious person, but reading and learning about Mother Teresa’s life and accomplishments makes a total believer out of me that there is something greater and if we just have faith things will work out. With gods help, one small woman, in a simple white cotton sari, who did not bother with reports and theories, simply went out into the world and changed the lives of millions.

The Giver, By Lois Lowry - 1628 Words

Elvis Presley once said, â€Å"Truth is like the sun. You can shut it out for a time, but it ain t goin away.† Plato’s The Allegory of the Cave relates to this quote by focusing on the truths of reality that humans do not comprehend. We think that we understand what we are seeing in our world, but we really just perceive shadows of the true forms of the things that make up the world. We are ignorant about the true nature of reality. The novel, The Giver, by Lois Lowry also involves these concepts. The main character, Jonas, lives in a community of conformity and conflict. When he begins to spend time and train with The Giver, an old man who is the only keeper of the community s memories, Jonas discovers the unsafe truths of his community s secret past. Once Jonas discovers the reality about his community, it constantly pesters him until he makes an important decision. Jonas realizes that he must escape from his world in order to make a long needed change for his commun ity. As the prisoner from The Allegory of the Cave seeks knowledge outside of the cave, Jonas from The Giver discovers dark and deadly truths of his community’s secret past that will change his life forever. The corrupt community from The Giver parallels the ignorant prisoners’ experience trapped in the shadows of their cave. In Plato’s theory, the cave represents people who have a false understanding of reality in society. The cave shows that believers of purely first-hand evidence are trapped in a â€Å"cave† ofShow MoreRelatedThe Giver by Lois Lowry869 Words   |  3 Pagesbeing ourselves and expressing who each of us are to the world. However, in the book The Giver by Lois Lowry, everyone is raised to count on one another and everyone must look and act the same. Our society differs from Jonas’s in many ways, such as the family units, birthdays, and the way we each learn about our past. In the book The Giver, our society and Jonas’s differ in terms of the family units. 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It is scientific fiction because Lois Lowry made a setting where everything is unusual than the things we do now. There are birthmothers, rarely Receivers of Memory ( which Jonas turns out to be ), and other special jobs in the community center. Point of View: The point of view in the story is third person because if there was a first person, the narrator ( which is a person that isRead MoreThe Giver By Lois Lowry884 Words   |  4 PagesGiver Essay Agustin Fitipaldi Bervejillo In the book The Giver, by Lois Lowry. The main character Jonas is not like others in his utopian community. He is a normal 12 year old boy and is living in the same old community of sameness. Until one day he gets selected to be the Receiver of Memory and begins to experience things on a different way because of the memories being transmitted to him. 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As the book goes on, you are slowly let in on details, like the characters can not see color, and that the parents are not biological parents, and everything is organized and decided for the characters in the book. The author did a great job of slowly bringingRead MoreThe Giver By Lois Lowry1554 Words   |  7 PagesBlock 6 Second Independent Project: Book Report 10/5/14 The Giver In this essay, I am going to report about the book The Giver by Lois Lowry. Jonas, a twelve-year-old boy, is the main character of the book. The book describes a seemingly indestructible society, with absolute order and rules. Jonas happens to be chosen as the next Receiver of Memory on his twelve year old ceremony. After receiving part of the memories from the The Giver and discovering the truth behind this â€Å"perfect† community, heRead MoreThe Giver By Lois Lowry1313 Words   |  6 Pagesis no pain, no prejudice, no emotion, and no detestation. Lois Lowry gives a vivid description of a community where everything is equal, everyone is just as important as another, and life choices are made by only one individual. In the book The giver by Lois Lowry, it expresses the exact opposite of Marx’s most important ideas which is a prime example of what people will do if they were forced to live a certain way. In the book The Giver, it tells the story of a perfect world. Everyone there is happy