BIOMATERIALS
A substance, synthetic or natural in origin used for or suitable to use in prostheses that come into contact with living tissues.
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CLASSIFICATION OF BIOMATERIALS
Autograft Allograft Xenograft Alloplast
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Biological tissue implants
“Everything old is new again� rings true in the use of biological implants in facial plastic and reconstructive surgery
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TYPES BONE
DERMIS AND DERMAL FAT
CARTILAGE
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CARTILAGE
Most commonly used for nasal augmentation Source for orbital reconstruction are cartilagenous nasal septum and conchal cartilage Rib cartilage used for auricular reconstruction seventh and eigth considered as gold standard
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Infection and resorption of autogenous cartilage is rare They are too flexible and do not provide adequate support for orbital contents in larger defects Incidence of strabismus and enophthalmous was significantly greater for cartilagenous grafts
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Biomaterials for orbit-2004
BONE
Used for mandibular reconstruction,repair of traumatic midface defects,orthognathic and craniofacial surgery Iliac crest,tibia,rib and calvarium are common doner sites To correct cranial and orbital synostosis
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Advantages of autogenous bone are relative resistance to infection,lack of host response against graft and lack of concern for late extrusion Endochondral and membraneous bone sources are used in orbital reconstruction with major donor sites being illiac crest and calvarial bone Resorption of graft volume is a concern in long terrm reconstruction
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Endochondral – 75% Membraneous -20% Cortical maintain volume better than cancellous Primary choice – calvarial bone
Principles of facial and plastic reconstrucive surgery www.indiandentalacademy.com
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DERMAL FAT When defects are subcutaneous
Dermal fat grafts used in mandibular ankylosis,intraoral and pharyngeal cavity reconstruction and soft tissue deficits including hemifacial atrophy,gun shot trauma.
Harvested in areas of thick skin with dermatome www.indiandentalacademy.com
What is biocompatibility?
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Causing a harmful tissue reaction like pain, swelling, necrosis that could compromise function. Causing a systemic toxic reaction Having tumorogenic potential
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Ideal properties for generic biomaterial Potter and ellis.biomaterials-joms-2004
Chemically inert Biocompatible Nonallergenic Noncarcinogenic Cost effective Sterilizable Easy handling Ability to stabilize radioopque www.indiandentalacademy.com
Healing response to most biomaterials is the formation of fibroconnective tissue scar or fibrous encapsulation
Exception! Metallic plates for bone fixation
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FACTORS LEADING TO FAILURE OF BIOMATERIALS
host
F A I L U R E
chemical
mechanical
Potter and ellis biomaterials for orbit joms 2004
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Principles of alloplastic material selection and surgical placement
Tissue quality of recepient site Emphasis on vascularity and soft tissue coverage Size of the implant Implant mobility
Deeper the implant lesser the exposure
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Alloplastic implant types
Dimethylsiloxane Polytetrafluoroethylene Polyethylene Polyamides and acrylic Titanium and gold metals Calcium phosphate and cyanocrylate adhesives
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Dimethylsiloxane
Polymer from interlinking of silicon and oxygen with methyl groups Resistant to degradation due to si-o2 Onlay implant for zygomatic,maxillary,nasal and mandibular reconstruction Advantage of easy sterilisation with out degradation High degree of chemical inertness and hydrophobic Clinical toxicity and allergy reactions exist Extensive array used in every facial site The infection rate in the orbit is 1.2% ,displacement 20%
Not used in TMJ joint due to fragmentation of material- synovitis www.indiandentalacademy.com
Silicone (silastic) implants for a wide variety of facial contouring procedures
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polyamides
Organopolymersderivatives of nylon Known clinically as mesh material( supramid) Used for orbital reconstruction
Fibosis and resorption can occur with time
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METALS
Biocompatibility depends on surface properties and corrosion After implantation an oxide layer quickly forms on the metal surface which determines its resistance to corrosion Stainless steel ,vitallium and titanium used successfully in human implantation Stainless steel has higher corrosion potential,greater amount of metal ion release and more likely to require secondary removal Vitallium forms chromic oxide layer and is more resistant to corrosion www.indiandentalacademy.com
Used for skull reconstruction,repair and reconstruction of facial and skeletal injuries and as an adjunct to oral and craniofacial prosthetic rehabilitation
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Vitallium fossa implant used as TMJ prosthesis which are secured to articular eminence and lateral border of zygomatic arch with 2.0 mm screws.used with methylmethacrylate head
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Christensen condylar prosthesis
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Vitallium glenoid fossa implant
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Titanium
Available as pure or alloy with small amount of other metals like 6% aluminium and 4% vanadium Highly resistant to corrosion due to titanium oxide surface layer Lack of artefact on CT and MR images
These properties with strength makes it best metal currently availablefor requirments in craniomaxillofacial stabilisation
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Endosseous implant placed in mastoid for retension of ear prosthesis
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Acute internal orbital injury reconstruction can bo done with precontoured titanium mesh, which is stiff enough to provide to bridge large defects with out losing shape.it does not resorb and provide life long support of periorbital soft tissues
Use of nonresorbable alloplastic implants Joms-2004 www.indiandentalacademy.com
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Mandibular reconstruction using titanium functionally dynamic Bridging plate system: A retrospective study of 34 cases
A retrospective study of 34 patients who had mandibular reconstruction using titanium dynamic bridging system for after oncological reconstruction showed satisfying functional and aesthetic results.it provides a solution for a safe and rapid mandibular reconstruction for patients with a poor prognosis or poor general condition
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American association of omfs Joms-2004
Unique role of osseointegration Prosthetic reconstruction of edenjulous mandible and maxilla and single tooth replacement,extraoral retension of facial prosthesis and hearing aids even in irradiated bone
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Comparison of custom orbital floor titanium mesh with autologous bone grafts retained with screw fixation reported no complication when compared with placing of autologous bone grafts.
54 patients patients with titanium mesh showed excellent results with out the need for removal of implant due to infection
Biomaterials for orbit Joms-2004 www.indiandentalacademy.com
Calcium phosphate
Capable of osteoconduction Commercially available as hydroxyapatite Ceramic hydroxyapetite made from crystals Ceramic hydroxyapetite is made from crystals which are sintered at high temp in to hard nonresorbable solids used for maxillofacial reconstruction,alveolar and craniofacial augmentation Block form used as interpositonal graft in facial skeletal osteotomies Should not be used in load bearing facial areas Non ceramic used as powder-liquid mixture mixed intraoperatively and filled or contoured ti the bony defect www.indiandentalacademy.com
Liquid and powder composite used to reconstruct traumatic frontal bone www.indiandentalacademy.com
Porous hydroxyapatite outer defect of calvarium
Granules for partial thickness cranial defect
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Highly compatible ,minimal inflammatory reaction,strong mechanical bond and allows ingrowth of host tissue providing a scaffold for bone repair has limited resorption Good results for simple orbital reconstruction Limited adaptability and incompatibility with rigid fixation
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polytetrafluoroethylene
It is a very biocompatible group of carbon based biomaterials. Bonding of highly reactive fluorine to carbon creates extremely stable biomaterial which is not biodegradable PTFE in facial surgery as a skeletal augmentation material known as proplast which was either combined with graphite ( proplast I) ,alumina (proplast II) or hydroxyapatite. The fibrillar composition results in non-interconnected surface opening of pore size 10-30um which allows soft tissue ingrowth and less fibrous encapsulation and little tendency for migration. Subdermal implantation in lip,nasolabialfold ,glabella, nasaldorsum,and other subcutaneous facial defects as slings for ptotic tissues of eye lid and face and bony augmentation mid face,malar,mandibular areas www.indiandentalacademy.com
Implants as strands and cords for subdermal implantation
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Advanta ePTFE facial implants in cosmetic facial surgery
Expanded polytetrafluoroethylene implants can be used to augment lips,lines and wrinkles such as nasolabial folds, mentolabialfolds,glabellar lines or defects from hypoplastic scars and traumatic defects.these implants have been used successfully in subperiosteal placement or in dermal placement of the upper face
American association of omfs Joms-2006 www.indiandentalacademy.com
Tendon passer through middle of upper lip
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Plane of implant placement for facial tissues
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Passing awl in the subdermal plane to pull ePTFE implant through the incision
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polyethylene
Differentiates from PTFE by a lack of fluorination of ethylene monomer Comercially available as low,high and ultrahigh molecular weight PTFE Non resorbable and highly compatible HDPE has been used for facial augmentation with a variety of preformed facial,ear,orbital and cranial implants (Medpor,porex Medical) Fibrous ingrowth has clinical manifestation of stabilisation,difficulty with secondary removal and minimal settling of the implant Porous polyethylene Implant is not radiopaque www.indiandentalacademy.com
HDPE IS USED FOR SECONDARY RECONSTRUCTION OF INTERNAL ORBITAL DEFECTS OR THE CORRECTION OF ENOPHTHALMOUS
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polyethylene
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Use of temporal polyethylene implant after temporalis myofascial flap transposition
The transposition of temporalis muscle results in large hollowing of temporal fossa that leaves the patient with cosmetic impairement . Use of prefabricated porous high density polyethylene temporal implant provide sufficient cosmeiic result
American association of omfs Joms-2006
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cyanoacrylate
Cyanoacrylate derivatives(dermabond ,Ethicon)has been used for skin closure 5-0,6-0 skin sutures in esthetic facial surgery Superficial skin must be held as the adhesive is applied to prevent deposition of polymer in to the wound potentially delaying wound healing
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ACRYLIC
Acrylic biomaterials are polymerized esters of either acrylic or methacrylic acids Impervious,non –biodegradable and is tolerated by development of avascular fibrous capsule Used in cranioplasty and filling full thickness cranial defects Acrylic mixtures has very low cost,intraoperative fabricationand adaptation Can be loaded with antibiotics by mixing antibiotic powder in acrylic resin www.indiandentalacademy.com PMMA used in infected cranial fractures and reconstruction
HTR is a composite of PMMA and PHEMA used for large full thickness defects involving cranial,frontal,orbital where sufficient autologous material available or there is sufficient morbidity with size of doner defect
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Liquid monomer and powdered PMMA polymer which is mixed and cured for frontal cranioplasty
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polyesters
Diverse group of surgical devices that have a wide range of shapes like suture,mesh,plates and screws and sites of tissue implantation with physical properties that extend from resorbable to permanent implants
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Resorbable polymers
Material used in surgery as braided resorbable suture material Non suture application is bone fixation devices plates and screws with 82% PLA and 18% PGA (lactosorb)
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Bioresorbable poly-L/ DL-Lactide plates are reliable for repairing Large Inferior orbital wall bony defects:
Bioresorbable poly-L/DL-lactide implants are used to repair,large inferior orbital wall defects which adequately support the orbital soft tissue contents via subconjuctival approach
First material in the literature to pramote bone healing along bone fragments of the inferior orbital wall
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Joms-2006
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The use of biodegradable plates and screws to stabilize facial fractures
Out of 291patients,59 patients were identified as having received biodegradable plates( polylactide)for various fractures like Le Fort I ,II, III ,zygomatico complex,orbit,frontal sinus,mandible by ORIF. Favourable healing can be observed through the use of biodegradable PL plates and screws to stabilize selected midface fractures in patients of all ages,as well as mandible fractures in early childhood.
American association of omfs Jomfs -2006 www.indiandentalacademy.com
Used in mild to moderate midface fractures resulting from low velocity injuries and midface fractures in growing patients were stabilised with 1.5mm or 2.0mm biodegradable plates and screws. Patients in the primary or mixed dentition presenting with mandibular fractures were all stabilised with biodegradable plates
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Water bath system www.indiandentalacademy.com
wound closure materials
Non absorbableSutures-nylon,polypopylene (tensile strength more than 60 days) Absorbable 窶田atgut,polyglactin,polycolicacid,polydioxanone Staples Adhesive tapes
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Management of alloplastic infection
When a purulent infection occurs antibiotics and drainage is not a permanant solution,bacterial biofilim is impenetrable by antibiotics.drainage and removal of material is adviced Reimplantation should not be done for atleast 3-6 months to allow complete resolution of infection and inflammation in the adjacent structures Material charecteristics S .epidermidis – polymer S.aureus- metal Surface roughness, surface configuration,surface hydrophobicity www.indiandentalacademy.com
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Role of tissue engineering in oral and maxillofacial reconstruction Joms - 2005
Novel field that draws support from multiple disciplinary ,including cell culture and extracellular matrix. It offers our speciality a new opinion to supplement existing treatment for reconstruction of oral and maxillofacial complex.
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A human trial using a human tissue engineered oral mucosa was recently done
Autogenous keratinocytes were harvested from a punch biopsy 4 weeeks prior to oral surgery,placed in a serum free culture and seeded in to a human cadaveric dermal equivalent. 30 patients with precancerous lesion with this(EVPOME) graft showed 100% intake WITH CLINICAL EVIDENCE OF VASCULAR GROWTH
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Engineering scaffolds for craniofacial application
Scaffold must fit complex maxillofacial defects and be able to be stabilised.the state of art is to create the gross external shape based ion 3 dimensional (CT) images of the patient. Combination of base scaffold material is used for best results
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Tissue engineering mandibular condyle a combination of several biomaterials.polymer on the top For cartilage regeneration, and a calcium phosphate,ceramic,hydroxyapatite on the bottom for bone formation www.indiandentalacademy.com
In future the surgeon will be able to order a 3-D reconstruction on a monitor in the office.with appropriate soft ware can constuct a custom made implant.the computer engineered implant would be forwaded to a work station that would fabricate the implant to the exact specification for the area of the face to be constructed
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