implants are broadly classified as indicious subperiosteal and trans-osteo endo means within so into osseous implants are the implants that are placed within the jaw bone some examples are blade implants and root form implants they are available as prefabricated in the shape of blades with an integrated abutment that emerges out of the soft tissues to support the prosthesis the industrial blade implant was introduced independently in 1967 by dr leonard linko root form implants are the most commonly used and they were first invented by dr brainmark in 1978 the root form implant usually has two parts one part which is inserted in the bone is called the fixture and the other part which is called the abutment is immediately or later fixed to the fixture and emerges out of the soft tissues to hold the prosthesis it has three parts crest module body and apex we will talk about its details in a while all right so subperiosteal implants are the implants that are placed under the periosteum and fixed over the jaw bones these are used when we can't use indices implants for example in severely resorbed mandible where the mandibular canal is close to the crest of the ridge the first subperiosteal implant was placed in 1949 by dr gustav dahl next is transostial implants these are also inserted in severely resorbed mandibles where placing the endoscious implant may lead to mandible fracture they are mostly used to stabilize loose dentures these implants are rarely used as their insertion requires major surgery under general anesthesia now we will learn about the most commonly used implants in detail root form implants this is a category of industrial implants designed to use a vertical column of bone similar to the root of a natural tooth that's why they are called root form implants based on their design there are three different types of root form implants cylinder screw or combination of both we can also call them threaded and non-threaded we can see the first one is the cylinder root form implant now you must be wondering how retention is achieved in this case these implants depend on a coating with a rough material like hydroxyapatite or surface condition to provide microscopic retention in bone these implants are usually pushed or tapped into a prepared bone site the advantage here is that it can be placed in difficult access locations for example in the posterior regions of maxilla or if the adjacent tooth has a tall clinical crown also they have more bone to implant contact percentage an example is indipore implants the second one is screw or threaded implant this is the most commonly used design these threads help in the retention of the implant in bone these are screwed into the prepared osteotomy site for example biohorizon implants and nobel biocare implants these are the names of the manufacturers this threaded design permits the implant removal at the time of surgery if placement is not ideal it also permits implant removal at the stage 2 surgery if angulation or crestal bony contours are not correct the threads are primarily designed to increase the bone to implant surface area and to decrease the stresses at the interface during occlusal loading compared with a cylinder implant body design this also increases the mechanical retention in the bone at the initial implant insertion they have different thread designs this is square or u-shaped or power thread design these threads are non-cutting these type of threads increase the surface area of the implant which increases its primary stability in the bone but the disadvantage is that you need a thread former also known as bone tap to make threads in the bone before placing implants then there is v-shaped thread design which has cutting threads so this is also called a self-tapping implants because here you don't need the thread former to make threads in the bone they are sharp so they are easily engaged in the bone this thread design has the longest history of clinical use the most common outer thread diameter is 3.75 millimeters with a 0.38 millimeters thread depth and a 0.6 millimeters thread pitch now to combine the benefits of the two thread designs there are variable thread implants at the apical third of these implants there are sharp self tapping deep threads with high pitch value pitch is the distance between the threads high pitch value means more space between the threads this apical third of the implant helps in preparing threads in the bone the middle third of these implants have shallow square type threads these get easily incorporated in the threads that are already prepared by the apical third of the implant these square threads give primary stability to the implant because they laterally condense the bone around them the crystal part of these implants have very shallow micro rings because the crystal bone has high density and low vascularity so you don't want to pressurize it with big threads that may cause pressure necrosis of the crystal bone based on the body design there is parallel body and tapered body implants as the name suggests these are parallel without any taper their advantage is that they have more surface area compared to tapered body implant but they are difficult to place if you accidentally widen the osteotomy then the primary stability of these implant is reduced also in this type of implant body you need to use more number of drills to prepare the osteotomy in case of tapered body implant you can get high primary stability with minimal drilling even in low density bone the only disadvantage is their smaller surface area compared to the parallel body implants on the basis of implant connection implants are classified as implants with external connection or external hex and implants with internal connection or internal hex which connection are we talking about it's the connection of the implant with the abutment and the healing screw external hex means this connection emerges above the implant platform as you can see here all the implant components like abutment healing screw extra get engaged over and around this connection and are fixed using a connection screw in internal hex the connection remains inside the implant body all the implant components go into the implant connection and get engaged the components are fixed using the connection screw root form implants are also classified on the basis of connection design there is triangular design which has three faces in this case the abutment can be fixed at any of the three position next there is hexagonal design which has six faces so the abutment can be fixed at any of the six positions the octagonal design has eight faces so the abutment can be fixed at any of the eight positions there is a design which does not have any faces it is a smooth surface tubing tube connection this is called a smooth surface or non-hex design or cold well design here we don't need a connection screw but the abutment gets firmly engaged and cold welded into the implant connection it is claimed that this connection forms a tight seal at the implant abutment connection interface and prevents microbial growth in the connection now we will see another type of connection morse taper connection this is a combination of both hexed and non-hexed connections it has the hex in the deepest half of the internal connection this gives us the anti-rotational feature whereas the smooth non-hexed surface in the crystal half of the connection makes a tight seal to prevent bacterial growth on the basis of implant material we have the titanium alloy implants and zirconium implants most of the root form implants being currently used are made of pure titanium or titanium alloys now let's see why titanium is used titanium has high strength low weight high corrosion resistance biocompatibility low modulus of elasticity and easy shaping and finishing capability the titanium alloy most frequently used for implant has ninety percent titanium six percent aluminium which decreases the specific weight and improves the elastic modulus and four percent vanadium which decreases thermal conductivity and increases hardness now when exposed to air titanium or its alloy immediately forms an oxide layer that is titanium dioxide over its surface this layer comes in contact with the bone and plays an important role in corrosion resistance biocompatibility and osseointegration zirconium also osteointegrates with bone like titanium additional advantages of zirconium are high aesthetics and the ability to be used in patients with titanium allergy on the basis of implant pieces we have two piece implants and one piece implants most implants come with two pieces one is the implant body or fixture and the other part is the abutment which is screwed over the implant body to support the prosthesis the one piece implant comes with the abutment attached to the implant these implants are used for immediate functional or non-functional restoration after implant placement now let's talk about implant surface treatments they are basically done to make the implant surface rough because roughened surfaces increase the bone implant contact percentage during the initial healing phase the rough surface helps the migration of osteogenic meaning the bone forming cells to the implant surface for contact osteogenesis so implant surfaces are either machined or modified machined means they are not modified with different surface treatments it was most commonly used in the past but not anymore because the modified surfaces have greater surface area the machined implant surfaces can be modified with either additive methods or subtractive methods additive means something is added to the surface to make it rough and subtractive means something is removed like etching the surface so additive methods are coating the surface with hydroxyapatite or spraying it with plasma hydroxyapatite coated implant surface shows accelerated interfacial bone formation and maturation there is direct bonding between the hydroxyapatite coating and the bone sometimes there can be a gap between the implant surface and the bone this gap healing can be enhanced by the hydroxyapatite coating the hydroxyapatite coating also reduces the corrosion rate of the metal some advantages of hydroxyapatite coated implants are increased roughness and surface area enhanced initial implant stability increased gap healing between bone and hydroxyapatite coating less corrosion of metal faster healing at the bone interface and stronger bone to implant interface the disadvantages of coating are flaking cracking or scaling of the coating at implant insertion especially in high density bone increased plaque retention when left exposed to the oral environment or after the crystal bone resorption and marginal soft tissue recession this coating also increases the cost of the implant titanium plasma sprayed surface that is tps is prepared by spraying molten metal on the titanium base which results in a surface with irregularly sized and shaped valleys pores and crevices this increases the microscopic surface area by approximately 10 times subtractive methods are sandblasting and acid etching sand blasting is done using agents such as aluminium oxide titanium dioxide and calcium phosphate this increases surface roughness sand blasting not only improves bone to implant contact percentage but also improves contact osteogenesis by allowing the addition proliferation and differentiation of the osteoblasts over the implant surface the disadvantage is that there could be residues of the materials that are used for sandblasting also it could be non-uniform and result in loss of metallic substance from the implant to eliminate these problems calcium phosphate is used it's a resorbable blast material this calcium phosphate is removed from the implant surface which means that the blast medium is resorbed and a surface of pure titanium dioxide is produced that is free of contaminants acid etching of titanium implants is performed using baths of hydrochloric acid nitric acid and sulfuric acid in specific combinations you can combine these two and have implants that are first sandblasted to produce macro texture followed by acid etching to produce a final micro textured surface these implants have many advantages like high bone to implant contact percentage higher rate and degree of osseointegration better osteoconductive properties and higher capability to induce cell proliferation research has shown that these implants if inserted in bone with adequate volume and density can be restored after six weeks now let's see what an anodized surface means so this surface is prepared by applying voltage on titanium implants immersed in an electrolyte which results in a surface with variable diameter micropores the advantages are improved cell proliferation and attachment and lack of cytotoxicity [Music] foreign [Music]
