Copy of biomaterials new presentation /certified fixed orthodontic courses by Indian dental academy

INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

BIOMATERIALS

A substance, synthetic or natural in origin used for or suitable to use in
prostheses that come into contact with living tissues.


CLASSIFICATION OF BIOMATERIALS

Autograft
Allograft
Xenograft
Alloplast


Biological tissue implants

“Everything old is new again” rings true in the use
of biological implants in facial plastic and
reconstructive surgery


TYPES
BONE

DERMIS AND DERMAL FAT

CARTILAGE


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


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


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


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


Endochondral – 75%
Membraneous -20%
Cortical maintain volume better than cancellous
Primary choice – calvarial bone

Principles of facial and plastic reconstrucive surgery

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

What is biocompatibility?


Causing a harmful tissue reaction like pain, swelling, necrosis that could compromise function.
Causing a systemic toxic reaction
Having tumorogenic potential


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

Healing response to most biomaterials is the formation of fibroconnective tissue
scar or fibrous encapsulation

Exception! Metallic plates for bone fixation


FACTORS LEADING TO FAILURE OF BIOMATERIALS

host

F
A
I
L
U
R
E

chemical

mechanical

Potter and ellis biomaterials for orbit joms 2004


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


Alloplastic implant types

Dimethylsiloxane
Polytetrafluoroethylene
Polyethylene
Polyamides and acrylic
Titanium and gold metals
Calcium phosphate and cyanocrylate adhesives


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

Silicone (silastic) implants for a wide variety of facial contouring procedures


polyamides

Organopolymersderivatives of nylon
Known clinically as mesh material( supramid)
Used for orbital reconstruction

Fibosis and resorption can occur with time


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

Used for skull reconstruction,repair and reconstruction of facial and skeletal injuries and
as an adjunct to oral and craniofacial prosthetic rehabilitation


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


Christensen condylar prosthesis


Vitallium glenoid fossa implant


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


Endosseous implant placed in mastoid for retension of ear prosthesis


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

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


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


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

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

Liquid and powder composite used to reconstruct traumatic frontal bone

Porous hydroxyapatite outer defect of calvarium

Granules for partial thickness cranial
defect


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


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

Implants as strands and cords for subdermal implantation


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

Joms-2006

Tendon passer through middle of upper lip

Measurement of implant length

Plane of implant placement for facial tissues


Passing awl in the subdermal plane to pull ePTFE implant through the incision


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

HDPE IS USED FOR SECONDARY RECONSTRUCTION OF INTERNAL
ORBITAL DEFECTS OR THE CORRECTION OF ENOPHTHALMOUS


polyethylene


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

Joms-2006


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


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
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


Liquid monomer and powdered PMMA polymer which is mixed and cured for frontal cranioplasty


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


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)


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


Joms-2006

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.

Jomfs -2006

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


Water bath system

wound closure materials

Non absorbableSutures-nylon,polypopylene (tensile strength more than 60
days)
Absorbable –catgut,polyglactin,polycolicacid,polydioxanone
Staples
Adhesive tapes


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

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.


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


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


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

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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