BIOMATERIALS AND
BIOCOMPATIBILITY F0R IMPLANTS
(PART – 2)
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www....
 INTRODUCTIONINTRODUCTION
 HISTORYHISTORY
 PHYSICAL AND MECHANICAL, AND CHEMICALPHYSICAL AND MECHANICAL, AND CHEMICAL
R...
 SURFACE CHARACTERIZATIONSURFACE CHARACTERIZATION
 TISSUE INTERACTIONTISSUE INTERACTION
 POROUS AND FEATURED COATINGSPO...
SURFACESURFACE
CHARACTERIZATION ANDCHARACTERIZATION AND
TISSUE INTERACTIONTISSUE INTERACTION
www.indiandentalacademy.comww...
Metal and Alloy SurfacesMetal and Alloy Surfaces
 Standard grades of alpha (unalloyed) titaniumStandard grades of alpha (...
 The type of oxide on surgical implants is primarily amorphous inThe type of oxide on surgical implants is primarily amor...
 The titanium alloys used for dental implantThe titanium alloys used for dental implant
components include micro structur...
Tissue InteractionsTissue Interactions
 Oxide modification during in vivo exposure has beenOxide modification during in v...
Integration with Titanium andIntegration with Titanium and
AlloysAlloys
 Titanium may interact with the recipient livingT...
Integration with Cobalt and IronIntegration with Cobalt and Iron
AlloysAlloys
 The alloys of cobalt (Vitallium) and ironT...
Integration with CeramicsIntegration with Ceramics
 Aluminum oxide (Al2O3) ceramics have beenAluminum oxide (Al2O3) ceram...
HydroxyapatiteHydroxyapatite
 In addition to the bulk aluminum oxideIn addition to the bulk aluminum oxide
biomaterials, ...
 The surface topography is characteristic of the preparationThe surface topography is characteristic of the preparation
p...
 Niznick used a titanium alloy Ti-6A1-4V toNiznick used a titanium alloy Ti-6A1-4V to
improve the mechanical properties a...
 Recently, concerns have been expressedRecently, concerns have been expressed
regardingregarding embedded media from glas...
Porous and Featured Coatings
 The implant surface may also be covered with a
porous coating. These may be obtained with
t...
Titanium Plasma Sprayed
 Porous or rough titanium surfaces have been fabricated by
plasma spraying a powder form of molte...
 Porous titanium surface increase the total surface
area and attachment by osteoformation,
enhance attachment by increasi...
Titanium Plasma Sprayed surfaces
result in increased TSA
www.indiandentalacademy.com
Hydroxyapatite Coating :
 Hydroxyapatite coating by plasma spraying was brought to
the dental profession by deGroot.
 Ka...
 Implants of solid sintered hydroxyapatite have
been shown to be susceptible to fatigue failure.
 This situation can be ...
 The concerns related to calcium phosphate
coatings have focused on
 (1) the biomechanical stability of the coatings and...
Other Surface Modifications
 Surface modification methods include controlled
chemical reactions with nitrogen or other el...
Surface Cleanliness
 A clean surface is an atomically clean surface with
no other elements than the biomaterial constitue...
 Lausmaa et al showed that titanium implants had large
variations in carbon contamination loads (20% to 60%) in
the 0.3 t...
Surface Energy:
 Surface property values of an implant’s ability to integrate within bone
can be measured by - contact an...
Passivation and Chemical
Cleaning
 The ASTM specifications for final surface treatment of
surgical titanium implants requ...
Titanium implant etched with a solution
of nitric and hydrofluoric acidswww.indiandentalacademy.com
Sterilization:
 Manipulation with bare fingers or powdered gloves,
tap water, and residual vapor-carried debris from
auto...
 Presently, proteinaceous deposits and their
action as films can be best eliminated by
radio-frequency glow discharge
tec...
 A modified ultraviolet (UV) light
sterilization protocol showed to enhance
bioreactivity, which was also effective for
e...
PLASMA SPRAYING
 In order to coat a metallic substrate with a bioactive
glass, loaded bioactive glass or ceramic layer, o...
PLASMA SPRAY COATINGS
 sandblasting treatment is performed on
the surface to be coated to remove any
residual trace of ox...
 These micro grains cannot be removed by
cleaning, either by the use of compressed
air or chemically or electro staticall...
 The reasons for inability of the coating material to
provide good adhesion when applied directly to the
substrate includ...
ALUMINA COATING
 One of the first substances used in prosthetic
surgery for coating metallic stems was alumina.
 This ma...
 All the plasma spray operations are carried
out on rotating and heated specimens in
order to produce layers of homogenou...
SELECTION, EVALUATION AND
PREPARATION OF BIOMATERIALS
www.indiandentalacademy.com
SELECTION OF MATERIALS FOR
IMPLANTS:
 Biomaterials regardless of use fall into four general categories:
metals and metal ...
 The choice of ceramics as implant materials for
hard tissue replacement or augmentation has
increased in recent years, p...
 In comparison to metals and ceramics, polymers
are “weak” and generally flexible.
 Examples of polymeric dental implant...
IMPLANT MATERIAL EVALUATION
 Evaluation of materials generally falls into two
categories:
bulk characterization and
surfa...
BULK CHARACTERISATION
 BULK MATERIAL PARAMETERS IMPORTANT TO THE
EVALUATION OF DENTAL MATERIALS
 Mechanical Aspects (Pri...
SURFACE CHARACTERISATION
The surface properties of an implant are fundamental to the
near term and long-term success of th...
FINAL MATERIAL PREPARATION:
 In addition to selection and evaluation of biomaterials for implantation,
the steps by which...
BIOCOMPATIBILITY TESTS
 1. Initial Tests
Cell culture methods:
 Cell attachment and growth tests – DNA
synthesis, protei...
2. Secondary or intermediate tests
3. Usage tests
* Intradental or pulp irritation tests.
* Dental implants into bone
4. M...
At present the best estimates of the
success and failure of implants are
gained from three tests.
 Penetration of pd’s pr...
CONCLUSION
 Dental implants are still predominantly constructed from
only a few historically accepted metals and alloy sy...
REFERENCES:
 Carl E. Misch – Contemporary Implant
Dentistry
 Charles M. Weiss – Principles and practice
of Implant Denti...
Thank you
For more details please visit
www.indiandentalacademy.com
www.indiandentalacademy.com
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Biomaterials / orthodontic pliers

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implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic

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Biomaterials / orthodontic pliers

  1. 1. BIOMATERIALS AND BIOCOMPATIBILITY F0R IMPLANTS (PART – 2) INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy. com
  2. 2.  INTRODUCTIONINTRODUCTION  HISTORYHISTORY  PHYSICAL AND MECHANICAL, AND CHEMICALPHYSICAL AND MECHANICAL, AND CHEMICAL REQUIREMENTS FOR IMPLANT MATERIALSREQUIREMENTS FOR IMPLANT MATERIALS  METALS AND ALLOYSMETALS AND ALLOYS  OTHER METALS AND ALLOYSOTHER METALS AND ALLOYS  OTHER MATERIALSOTHER MATERIALS  FUTURE AREAS OF APPLICATIONFUTURE AREAS OF APPLICATION  BIOACTIVE AND BIODEGRADABLE CERAMICS BASEDBIOACTIVE AND BIODEGRADABLE CERAMICS BASED ON CAL.PHOSPHATESON CAL.PHOSPHATES www.indiandentalacademy.comwww.indiandentalacademy.com
  3. 3.  SURFACE CHARACTERIZATIONSURFACE CHARACTERIZATION  TISSUE INTERACTIONTISSUE INTERACTION  POROUS AND FEATURED COATINGSPOROUS AND FEATURED COATINGS  OTHER SURFACE MODIFICATIONSOTHER SURFACE MODIFICATIONS  SURFACE CLEANLINESSSURFACE CLEANLINESS  SURFACE ENERGYSURFACE ENERGY  PASSIVATION AND CHEMICAL CLEANINGPASSIVATION AND CHEMICAL CLEANING  STERILIZATIONSTERILIZATION  SELECTION EVALUATION ANDSELECTION EVALUATION AND PREPARATION OF BIOMATERIALSPREPARATION OF BIOMATERIALS  FINAL MATERIAL PREPARATIONFINAL MATERIAL PREPARATION  BIOCOMPATIBILITY TESTSBIOCOMPATIBILITY TESTS  CONCLUSIONCONCLUSION www.indiandentalacademy.comwww.indiandentalacademy.com
  4. 4. SURFACESURFACE CHARACTERIZATION ANDCHARACTERIZATION AND TISSUE INTERACTIONTISSUE INTERACTION www.indiandentalacademy.comwww.indiandentalacademy.com
  5. 5. Metal and Alloy SurfacesMetal and Alloy Surfaces  Standard grades of alpha (unalloyed) titaniumStandard grades of alpha (unalloyed) titanium  Alpha-beta and beta-base alloys of titaniumAlpha-beta and beta-base alloys of titanium (Ti)(Ti)  Exist with an oxide surface at normalExist with an oxide surface at normal temperatures, with ambient air or normaltemperatures, with ambient air or normal physiologic environments that act as oxidizingphysiologic environments that act as oxidizing media.media.  Surface properties are due to this oxideSurface properties are due to this oxide layer and differ fundamentally from thelayer and differ fundamentally from the metallic substratemetallic substrate..www.indiandentalacademy.comwww.indiandentalacademy.com
  6. 6.  The type of oxide on surgical implants is primarily amorphous inThe type of oxide on surgical implants is primarily amorphous in atomic structure (Brookite) and thin in thickness dimensionsatomic structure (Brookite) and thin in thickness dimensions (less than 20 nanometers).(less than 20 nanometers).  The grain structure of the metal and the oxidation conditionsThe grain structure of the metal and the oxidation conditions also condition the microstructure and morphology of the surfacealso condition the microstructure and morphology of the surface oxides. Porosity, density, and general homogeneity of theoxides. Porosity, density, and general homogeneity of the substrate are all related to this process.substrate are all related to this process.  Depending on the mechanical aspects of polishing and theDepending on the mechanical aspects of polishing and the chemical / electrochemical aspects of cleaning and passivating,chemical / electrochemical aspects of cleaning and passivating, these amorphous or crystalline oxides can exhibitthese amorphous or crystalline oxides can exhibit microscopically smooth or rough topographies at themicroscopically smooth or rough topographies at the micrometer level.micrometer level.  surface macroscopic roughness is normally introduced into thesurface macroscopic roughness is normally introduced into the substrate beneath the oxide zone by mechanical (Grinding),substrate beneath the oxide zone by mechanical (Grinding), particulate blasting (resorbable blast media or other), orparticulate blasting (resorbable blast media or other), or chemical (Acid etching) procedures.chemical (Acid etching) procedures.www.indiandentalacademy.comwww.indiandentalacademy.com
  7. 7.  The titanium alloys used for dental implantThe titanium alloys used for dental implant components include micro structural phases of alphacomponents include micro structural phases of alpha and beta or room temperature stabilized beta (only).and beta or room temperature stabilized beta (only).  Electrochemical investigations have shown that theElectrochemical investigations have shown that the alpha and beta phase oxides provide substratealpha and beta phase oxides provide substrate coverage and a high degree of chemical andcoverage and a high degree of chemical and biochemical inertness (resistance to corrosion and ionbiochemical inertness (resistance to corrosion and ion transfer) for titanium and alloys of titanium.transfer) for titanium and alloys of titanium.  Adequately processed and finished titanium alloysAdequately processed and finished titanium alloys have shown integration with bone and soft tissuehave shown integration with bone and soft tissue environments for a wide range of dental and medicalenvironments for a wide range of dental and medical implant devices.implant devices. www.indiandentalacademy.comwww.indiandentalacademy.com
  8. 8. Tissue InteractionsTissue Interactions  Oxide modification during in vivo exposure has beenOxide modification during in vivo exposure has been shown to result in increased titanium oxide layershown to result in increased titanium oxide layer thickness of up tothickness of up to 200 nm200 nm..  The highest oxide growth area corresponded to aThe highest oxide growth area corresponded to a bone marrow sitebone marrow site  while the lowest growth was associated with titaniumwhile the lowest growth was associated with titanium in contact with cortical regions of bone.in contact with cortical regions of bone.  Increased levels of calcium and phosphorus wereIncreased levels of calcium and phosphorus were found in the oxide surface layers and seemed tofound in the oxide surface layers and seemed to indicate an active exchange of ions at the interface.indicate an active exchange of ions at the interface. www.indiandentalacademy.comwww.indiandentalacademy.com
  9. 9. Integration with Titanium andIntegration with Titanium and AlloysAlloys  Titanium may interact with the recipient livingTitanium may interact with the recipient living tissues over several years results in the releasetissues over several years results in the release of small quantities of corrosion products evenof small quantities of corrosion products even though there is a thermodynamically stablethough there is a thermodynamically stable oxide film.oxide film.  The presence of the surface impurities such asThe presence of the surface impurities such as iron found on some implant parts, and otheriron found on some implant parts, and other contaminants related to the machining processcontaminants related to the machining process could result in loss of bone and integration incould result in loss of bone and integration in crestal areas exposed to corrosion products.crestal areas exposed to corrosion products.www.indiandentalacademy.comwww.indiandentalacademy.com
  10. 10. Integration with Cobalt and IronIntegration with Cobalt and Iron AlloysAlloys  The alloys of cobalt (Vitallium) and ironThe alloys of cobalt (Vitallium) and iron (surgical stainless steel-316L) exhibit oxides of(surgical stainless steel-316L) exhibit oxides of chromium (primarily Cr2O3 with some subchromium (primarily Cr2O3 with some sub oxides) under normal implant surface finishingoxides) under normal implant surface finishing conditions after acid or electrochemicalconditions after acid or electrochemical passivation.passivation.  These chromium oxides, result in a significantThese chromium oxides, result in a significant reduction in chemical activity andreduction in chemical activity and environmental ion transfers.environmental ion transfers. www.indiandentalacademy.comwww.indiandentalacademy.com
  11. 11. Integration with CeramicsIntegration with Ceramics  Aluminum oxide (Al2O3) ceramics have beenAluminum oxide (Al2O3) ceramics have been extensively investigated related to surface propertiesextensively investigated related to surface properties an d how these properties related to bone and softan d how these properties related to bone and soft tissue integrationtissue integration  The forms of the oxide structure are poly crystallineThe forms of the oxide structure are poly crystalline (alumina) and single crystalline (sapphire)(alumina) and single crystalline (sapphire)  Ceramic coatings (Al2O3) have been shown toCeramic coatings (Al2O3) have been shown to enhance the corrosion resistance and biocompatibilityenhance the corrosion resistance and biocompatibility of metal implants, in particular surgical stainless steelof metal implants, in particular surgical stainless steel and Ni-Cr, Co-Cr alloys.and Ni-Cr, Co-Cr alloys. www.indiandentalacademy.comwww.indiandentalacademy.com
  12. 12. HydroxyapatiteHydroxyapatite  In addition to the bulk aluminum oxideIn addition to the bulk aluminum oxide biomaterials, calcium phosphate-based ceramicbiomaterials, calcium phosphate-based ceramic or ceramic-like coatings have been added toor ceramic-like coatings have been added to titanium and cobalt alloy substrates to enhancetitanium and cobalt alloy substrates to enhance tissue integration and biocompatibility.tissue integration and biocompatibility.  These coatings, for the most part,These coatings, for the most part, are appliedare applied by plasma spraying small size particles ofby plasma spraying small size particles of crystalline hydroxyapatite ceramic powders.crystalline hydroxyapatite ceramic powders. www.indiandentalacademy.comwww.indiandentalacademy.com
  13. 13.  The surface topography is characteristic of the preparationThe surface topography is characteristic of the preparation process.process.  Surface roughening by particulate blasting can be achieved bySurface roughening by particulate blasting can be achieved by different media.different media.  SandblastingSandblasting provides irregular rough surfacing with < 10provides irregular rough surfacing with < 10 µµmm scales and a potential for impurity inclusions.scales and a potential for impurity inclusions. www.indiandentalacademy.comwww.indiandentalacademy.com
  14. 14.  Niznick used a titanium alloy Ti-6A1-4V toNiznick used a titanium alloy Ti-6A1-4V to improve the mechanical properties and electedimprove the mechanical properties and elected toto electro polishelectro polish the surface to reduce surfacethe surface to reduce surface roughness to be only in the 0.1roughness to be only in the 0.1 µµm scale bym scale by controlled removal of the surface layer bycontrolled removal of the surface layer by dissolution.dissolution.  Titanium implants may be etched with aTitanium implants may be etched with a solution of nitric and hydrofluoric acidssolution of nitric and hydrofluoric acids toto chemically alter the surface and eliminate somechemically alter the surface and eliminate some types of contaminant products.types of contaminant products.www.indiandentalacademy.comwww.indiandentalacademy.com
  15. 15.  Recently, concerns have been expressedRecently, concerns have been expressed regardingregarding embedded media from glassembedded media from glass beadingbeading (satin finish)(satin finish) and grit blastingand grit blasting (alumina Al2O3)(alumina Al2O3) and a possible risk ofand a possible risk of associated osteolysis caused by foreign debris.associated osteolysis caused by foreign debris.  A relatively new process (resorbable blastA relatively new process (resorbable blast media) has been said to provide a comparablemedia) has been said to provide a comparable roughness to an alumina grit blast finish, whichroughness to an alumina grit blast finish, which can be a rougher surface than the machined,can be a rougher surface than the machined, glass beaded, or acid etched surfaces.glass beaded, or acid etched surfaces.www.indiandentalacademy.comwww.indiandentalacademy.com
  16. 16. Porous and Featured Coatings  The implant surface may also be covered with a porous coating. These may be obtained with titanium or hydroxyapatite particulate-related fabrication processes.  Examples of coatings include – Titanium Plasma Sprayed Hydroxyapatite Coating Other Surface Modifications www.indiandentalacademy.com
  17. 17. Titanium Plasma Sprayed  Porous or rough titanium surfaces have been fabricated by plasma spraying a powder form of molten droplets at high temperatures.  At temperatures in the order of 15,000°C, argon plasma is associated with a nozzle to provide very high velocity 600 m/sec partially molten particles of titanium powder (0.05 to 0.1 mm diameter) projected onto a metal or alloy substrate.  The plasma sprayed layer after solidification (fusion) is often provided with a 0.04 to 0.05 mm thickness. www.indiandentalacademy.com
  18. 18.  Porous titanium surface increase the total surface area and attachment by osteoformation, enhance attachment by increasing ionic interactions, introduce a dual physical and chemical anchor system, and increase the load-bearing capability 25% to 30%.  Proponents of porous surface preparations reported that there have been results showing faster initial healing compared with noncoated- porous titanium implants and that porosity allows bone formation within the porosities even in the presence of some micro movement during the healing phase. www.indiandentalacademy.com
  19. 19. Titanium Plasma Sprayed surfaces result in increased TSA www.indiandentalacademy.com
  20. 20. Hydroxyapatite Coating :  Hydroxyapatite coating by plasma spraying was brought to the dental profession by deGroot.  Kay et al showed with scanning electron microscopy (SEM) and spectrographic analyses that the plasma- sprayed HA coating could be crystalline and could offer chemical and mechanical properties compatible with dental implant applications.  Cook et al measured the HA coating thickness after retrieval from specimens inserted in animals for 32 weeks and showed a consistent thickness of 50 µm, which is in the range advocated for manufacturing.www.indiandentalacademy.com
  21. 21.  Implants of solid sintered hydroxyapatite have been shown to be susceptible to fatigue failure.  This situation can be altered by the use of a CPC coating along metallic substrates.  New biocompatible coatings based on tricalcium phosphate or titanium nitride.  One advantage of CPC coatings is that they can act as a protective shield to reduce potential slow ion release from the Ti-6A1-4V substrate. www.indiandentalacademy.com
  22. 22.  The concerns related to calcium phosphate coatings have focused on  (1) the biomechanical stability of the coatings and coating-to-substrate interface under in vivo conditions of cyclic loading, and  (2) the biochemical stability of these coatings and interfaces within the gingival sulcus (especially in the presence of inflammation or infection) and during enzymatic process associated with osteoclastic remodeling of the bone-to-coating interfacial zones. www.indiandentalacademy.com
  23. 23. Other Surface Modifications  Surface modification methods include controlled chemical reactions with nitrogen or other elements or surface ion implantation procedures.  The reaction of nitrogen with titanium alloys at elevated temperatures results in titanium nitride compounds being formed along the surface.  These nitride surface compounds are biochemically inert (like oxides) and alter the surface mechanical properties to increase hardness and abrasion resistance.  Increased hardness, abrasion, and wear resistance can also be provided by ion implantation of metallic substrates. www.indiandentalacademy.com
  24. 24. Surface Cleanliness  A clean surface is an atomically clean surface with no other elements than the biomaterial constituents.  Contaminants can be particulates, continuous films (oil, fingerprints), and atomic impurities or molecular layers (inevitable) caused by the thermodynamic instability of surfaces www.indiandentalacademy.com
  25. 25.  Lausmaa et al showed that titanium implants had large variations in carbon contamination loads (20% to 60%) in the 0.3 to 1 nm thickness range, attributed to air exposure and residues from cleaning solvents and lubricants used during fabrication.  Trace amounts of Ca, Si, Cl and Na were noted from other studies.  Residues of fluorine could be attributed to passivation and etching treatments; Ca, Na, and Cl to autoclaving; and Si to sand and glass beading processes.www.indiandentalacademy.com
  26. 26. Surface Energy:  Surface property values of an implant’s ability to integrate within bone can be measured by - contact angle with fluids, local pH, and surface topography.  High surface energy implants showed a threefold increase in fibroblast adhesion and higher energy surfaces such as metals, alloys, and ceramics are best suited to achieve cell adhesion.  Surface tension values of 40 dyne/cm and higher are characteristic of very clean surfaces and excellent biologic integration conditions.  Because a spontaneously deposited, host-dependent “conditioning film” is a prerequisite to the adhesion of any biologic element, it is suggested that the wetting of the surface by blood at the time of placement can be a good indication of the high surface energy of the implant. www.indiandentalacademy.com
  27. 27. Passivation and Chemical Cleaning  The ASTM specifications for final surface treatment of surgical titanium implants require pickling and descaling with molten alkaline base salts.  This is often followed by treatment with a solution of nitric or hydrofluoric acid to decrease and eliminate contaminants such as iron.  Ways to intentionally modify the surface of the implant include conventional mechanical treatment (sand blasting), wet or gas chemical reaction treatment, electroplating or vapor plating, and ion-beam processing, which leaves bulk properties intact and has been newly adapted to dentistry from thin film technology. www.indiandentalacademy.com
  28. 28. Titanium implant etched with a solution of nitric and hydrofluoric acidswww.indiandentalacademy.com
  29. 29. Sterilization:  Manipulation with bare fingers or powdered gloves, tap water, and residual vapor-carried debris from autoclaving can all contaminate implant surfaces.  If an implant needs to be resterilized, conventional sterilization techniques are not normally satisfactory.  Studies suggested that alteration of the Ti surface by sterilization methods might in turn affect the host response and adhesive properties of the implant. www.indiandentalacademy.com
  30. 30.  Presently, proteinaceous deposits and their action as films can be best eliminated by radio-frequency glow discharge technique (RFGDT), which seems to be a suitable final cleaning procedure.  The principal oxide at the surface is unchanged by the RFGDT process.  studies suggest that RFGDT may enhance calcium and / or phosphate affinity because of an increase in elemental zone at the surface resulting in the formation of amorphous calcium phosphate compounds.www.indiandentalacademy.com
  31. 31.  A modified ultraviolet (UV) light sterilization protocol showed to enhance bioreactivity, which was also effective for eliminating some biological contaminants.  Adequate sterilization of clean, prepackaged dental implants and related surgical components has resulted in an ever-expanding use of gamma radiation procedures.  The healing screws, transfer elements, wrenches, and implants are all exposed to the gamma sterilization, which reduces opportunities for contamination. www.indiandentalacademy.com
  32. 32. PLASMA SPRAYING  In order to coat a metallic substrate with a bioactive glass, loaded bioactive glass or ceramic layer, one of the most common techniques is that of plasma spraying, which is based on the existence of a particular state of matter that is stable even at very high temperature.  This state is defined by many as the fourth state, and exists in addition to the solid, liquid, and gaseous states.  The gaseous state acquires energy and thereby turns to plasma, which then returns to gas owing to loss of energy. www.indiandentalacademy.com
  33. 33. PLASMA SPRAY COATINGS  sandblasting treatment is performed on the surface to be coated to remove any residual trace of oxides or mineral salts.  The great advantage of this treatment is that it makes the surface in question suitably rough.  Sandblasting however, which generally consists in the shooting of corundum sand, is in turn liable to leave residues in the form of micro grains.www.indiandentalacademy.com
  34. 34.  These micro grains cannot be removed by cleaning, either by the use of compressed air or chemically or electro statically.  Where there are such micro grains there is normally a poorer adhesion of the plasma sprayed layer, and precisely these areas are the locations of future cracking.  Since it was noticed that the amount of stuck grains is inversely proportional to their size, it is advisable to utilize sands with a sufficiently large grain size. www.indiandentalacademy.com
  35. 35.  The reasons for inability of the coating material to provide good adhesion when applied directly to the substrate include – 1.low wettability between the two materials 2.low chemical compatibility, and 3.a difference in thermal expansion coefficient.  With respect to the process mechanism, the effectiveness of plasma spray covering is based on the interaction that develops between the substrate surface and the hot material that is impacted on to it. www.indiandentalacademy.com
  36. 36. ALUMINA COATING  One of the first substances used in prosthetic surgery for coating metallic stems was alumina.  This material proved to possess reasonably bioinert characteristics and had already been applied as a substitute for the ball component of the hip endoprosthesis.  Alumina powder grain size must range between 20 and 40 micrometer.  Alumina coating formed by spraying leads to pore dimensions of between 0.02 and 0.4 micrometer, with a distribution peak centered on 0.18 micrometer. www.indiandentalacademy.com
  37. 37.  All the plasma spray operations are carried out on rotating and heated specimens in order to produce layers of homogenous thickness, and to give a certain margin of elasticity, thus avoiding cracking during the exercise  Experiments by either plasma spray or flame technique with alumina-coated metallic substrates proved that Alumina- based coverings are often unable to resist human body fluids  The best metallic pre-coating layers proved to be those made from molybdenum or titanium. www.indiandentalacademy.com
  38. 38. SELECTION, EVALUATION AND PREPARATION OF BIOMATERIALS www.indiandentalacademy.com
  39. 39. SELECTION OF MATERIALS FOR IMPLANTS:  Biomaterials regardless of use fall into four general categories: metals and metal alloys, ceramics (carbons are included in this group) Synthetic polymers and natural materials.  Metals and metal alloys utilized for oral implants have included titanium, tantalum and alloys of titanium aluminium, vanadium, cobalt/chromium / molybdenum and iron / chromium / nickel among others.  These materials are selected on the basis of their overall strengths; metals and metal alloys also bend themselves to shaping and machining and to a wide range of sterilization techniques. www.indiandentalacademy.com
  40. 40.  The choice of ceramics as implant materials for hard tissue replacement or augmentation has increased in recent years, primarily because of suggestions that bone, as well as soft tissue, must biochemically “accept” implants in order to promote rapid healing.  The use of synthetic “hydroxyapatite” is an example.  Other ceramic groups are aluminium oxides (such as aluminium and sapphire), tri calcium phosphate, and calcium aluminates. www.indiandentalacademy.com
  41. 41.  In comparison to metals and ceramics, polymers are “weak” and generally flexible.  Examples of polymeric dental implant materials include polymethyl methacrylate, silicone rubber, polyethylene, polysulfone and polytetra fluroethylene.  Like the ceramics, polymers are being chosen mainly as additives for beneficial secondary purposes, such as structural isolation or introduction of shock absorbing qualities in load bearing metallic implants. www.indiandentalacademy.com
  42. 42. IMPLANT MATERIAL EVALUATION  Evaluation of materials generally falls into two categories: bulk characterization and surface characterization.  In the course of device manufacture, storage, sterilization and implantation, a material is exposed to a myriad of conditions that are more than likely to change it in one way to another.  It is imperative to confirm that the range of manufacturing, storage and surgical procedures to which the materials is subjected to does not produce defects within or on the devices that diminish its safety and effectiveness.www.indiandentalacademy.com
  43. 43. BULK CHARACTERISATION  BULK MATERIAL PARAMETERS IMPORTANT TO THE EVALUATION OF DENTAL MATERIALS  Mechanical Aspects (Primarily obtained via stress / strain analysis)  Elastic Modules  Plastic Deformation  Tensile strength  Fatigue  Physical aspects (obtained via several different analysis)  Hardness  Thermal Properties  Wear properties  Density  Chemical stability  Toxicity  Conductivity www.indiandentalacademy.com
  44. 44. SURFACE CHARACTERISATION The surface properties of an implant are fundamental to the near term and long-term success of the device. KEY PARAMETERS FOR EVALUATION OF MATERIAL AND IMPLANT SURFACES  Surface energy, critical surface tension, chemical composition and stability.  Morphology and texture.  Thickness of surface coating or oxide layer surface electrical properties.  Corrosion resistancewww.indiandentalacademy.com
  45. 45. FINAL MATERIAL PREPARATION:  In addition to selection and evaluation of biomaterials for implantation, the steps by which the implant is produced must be carefully considered for their potential impacts on implant safety and efficacy (Baar in 1988.)  PASSIVATION  The use of acid passivation for cobalt-chromium implant has been recommended by the (ASTM).  This technique generally is used for conventionally polished implants to establish and stabilize the protective surface oxide layers that protect against electrochemical corruption of the material in saline environments.  STERILISATION  Conventional sterilization methods applicable to most oral implants include steam autoclaving, dry heat, glass bead sterilization, and ethylene oxide treatment.  Sterilization by radiation techniques by electron beam, gamma rays, ultraviolet radiation convoluted geometries of many types of oral implants.  Other approaches to sterilization such as radio frequency glow discharge treatment and recent developments in liquid solution techniqueswww.indiandentalacademy.com
  46. 46. BIOCOMPATIBILITY TESTS  1. Initial Tests Cell culture methods:  Cell attachment and growth tests – DNA synthesis, protein synthesis, anyone histochemical analysis.  Chemo taxis assays  Mutagenesis assays  Other assays www.indiandentalacademy.com
  47. 47. 2. Secondary or intermediate tests 3. Usage tests * Intradental or pulp irritation tests. * Dental implants into bone 4. Materials – ceramic, carbon, metals, polymers * Ceramic – combination of metal oxides * Sio2, Al2O3 and MgO and MgAl2O3 and HA * Carbon – Vitreous carbon, LTI or pyrolytic www.indiandentalacademy.com
  48. 48. At present the best estimates of the success and failure of implants are gained from three tests.  Penetration of pd’s probe along the side of the implant.  Mobility of the implant  Radiographs www.indiandentalacademy.com
  49. 49. CONCLUSION  Dental implants are still predominantly constructed from only a few historically accepted metals and alloy systems and even these are criticized in some quarters, where as ceramics, polymers and some natural materials are again receiving interest for their special properties.  A variety of new or improved bone and tooth implant products have been developed using HA ceramics and thus this system has lead to overall improvements in dental hard tissue repair and replacement.  Unquestionably, the trend for conservative treatment of oral diseases will continue to accelerate. Thus, it can be anticipated that dental implants will frequently be a first- treatment optionwww.indiandentalacademy.com
  50. 50. REFERENCES:  Carl E. Misch – Contemporary Implant Dentistry  Charles M. Weiss – Principles and practice of Implant Dentistry  Babbush – Dental Implants The art and Science  Benner – Implants and Restorative Dentistry.  JPD 1983, vol -49,832-837  DCNA Jan92, vol -36,19-25www.indiandentalacademy.com
  51. 51. Thank you For more details please visit www.indiandentalacademy.com www.indiandentalacademy.com

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