Osseointegrated Implants Part 1 Flashcards
(42 cards)
What are indications of implant denture?
- Edentulous patient with history of difficulty in wearing removable dentures.
- When there is severe change in complete denture bearing tissues.
- Poor oral muscular coordination.
- Para-functional habits that compromise prosthesis stability.
- Unrealistic patient expectations for complete dentures.
- Hyperactive gag reflex.
- Low tissue tolerance of supporting mucosa.
What are contraindications of implant denture?
- High dose irradiated patients.
- Patient with psychiatric problems such as psychosis, dysthorphobia.
- Hematological systemic disorders.
- Pathology of hard and soft tissues.
- Patient with drug, alcohol or tobacco chewing abuse.
What are charesterstics of implants in relation to natural teeth?
• The most important characteristic of this osseointegrated implant is that the direct bone anchorage can support a freestanding fixed prosthesis.
Occlusal forces
masticatory functions
can be retrieved in case of failure and another fixture placed at a later time.
Categorize implants into primary and biodynamic classification
dental implants fall into one of the following three primary groups: (a) Metal (b) Ceramics (c) Polymers
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Biotolerant materials are those that are not necessarily rejected when implanted into living tissue, but are surrounded by a fibrous layer in the form of a capsule. Bioinert materials allow close apposition of bone on their surface, leading to osteogenesis. Bioactive materials also allow the formation of new bone on to their surface, but ion exchange with host tissue leads to the formation of a chemical bond along the interface
Which type is osseo conductive? And what are bio mimics?
Bioinert and bioactive materials are also called osteoconductive meaning that they can act as scaffolds allowing bone growth on their surfaces. Biomimetics are tissue integrated materials designed to mimic specific biologic processes and help optimize the healing/regenerative response of the host microenvironment.
Why metals are selected? Which type is most used?
biomechanical properties, previous experience with processing, treating, machining, finishing and suitability for common sterilization procedures. Titanium (Ti) and its alloys (mainly Ti-6Al4V) have become the metals of choice for endosseous parts of currently available implants. However abutment screws, abutments, cylinders, prosthetic screws and various attachments are still made from gold alloys
What’s the content of pure titanium? What are the uses of traces of contents of this implant?
Ti–99.75 percent , Fe–0.05 percent , O–0.10 percent , N–0.03 percent , C–0.01 percent and others 0.06 percent.Traces of other elements such as nitrogen, carbon, hydrogen and iron have also been detected and added for stability or improvement of the mechanical and physicochemical properties. Iron is added for corrosion resistance and aluminium is added for increased strength and decreased density, while vanadium acts as an aluminium scavenger to prevent corrosion.
Talk about dynamics of titanium with body. What is alternative to titanium?
titanium fixture must be kept sterile and contact with any other metal or protein substance should be strictly avoided. Titanium interacts with biologic fluids through its stable oxide layer, which forms the basis for its exceptional biocompatibility. Because of the high passivity, controlled thickness, rapid formation, ability to repair itself instantaneously if damaged, resistance to chemical attack, catalytic activity
niobium
Types of ceramics and why they’re used?
Hydroxyapatite [Ca 10 (PO4 )6 (OH)2 ] (HA), tricalcium phosphate [Ca3 (PO4 )2 ] and bioglass are some of the more commonly used bioactive ceramics, which possibly develop a chemical bond of a cohesive nature with bone. Ceramics can make up the entire implant, or they can be applied in the form of a coating onto a metallic core. Low flexural strength and various degrees of dissolution/solubility of an all ceramic implant make coating,
What type of ceramic is preferred? Wry? What’s the dis advantage of ceramics?
Hydroxyapatite coated implants are preferred in cases where more rapid and enhanced bone implant contact is needed,
degradation of ceramic coatings
What are types of polymers (3)? Why are they not used? What are their uses limited to?
ultra high molecular weight polyurethane, polyamide fibers, polymethylmethacrylate resin, polytetra fluoroethylene and polyurethane
Inferior mechanical properties, lack of adhesion to living tissues and adverse immunologic reactions
limited to manufacturing of shock absorbing components
What’s ideal implant length and diameter?
between 8 and 15 mm, which correspond quite closely to normal root length.
minimum diameter of 3.25 mm is required to ensure adequate implant strength more important)
What are most common implant shapes? Advantage of screw type? Also categorized into (4)?
Hollow cylinders, solid cylinders, hollow screws or solid screws are commonly employed shapes, which are designed to maximize the potential area for osseointegration and provide good initial stability. Screw shaped implants also offer good load distribution characteristics
threaded and non-threaded, cylindrical or press fit. The threaded screw implants are threaded into a bone site and have obvious macroscopic retentive elements for initial bone fixation. The press fit implants depend on microscopic retention and or bonding to the bone, and usually are pushed or tapped into a prepared bone site.
The fixture with threaded surface has larger surface area and the threads also help to balance the force distribution into the surrounding bone tissue. The threads created in the bone site play an important role in initial implant fixation. Precision fit of the fixture called primary stability is an essential element for osseointegration, the failure of which leads to soft tissue proliferation between the fixture and bone rather than direct bone interface
What’s the influence and type of surface charecherstics?
influences wound healing at the implantation
Smooth surface
Rough surface
Porous
Describe smith surface in implants? What’s considered smooth and rough?
Smooth surface: Wennerberg and Coworkers suggested that smooth be used to describe abutments, whereas the terms minimally rough (0.5 to 1 µm), intermediately rough (1 to 2 µm) and rough (2 to 3 µm) be used for implant surfaces. However other literature reports that average surface roughness (Sa), surfaces with Sa<1 µm are considered smooth and those with Sa>1 µm are considered as rough.
Describe rough surface? Enumerate methods of surface coating
Plasma spray coating is one of the most common methods for surface modification. Plasma spraying is used for the application of both Ti and HA on metallic cores with a coating thickness of 10 to 40 µm for Ti. Thickness depends on particle size, speed and time of impact, temperature and distance from the nozzle tip to the implant surface area. The surface roughness value (Ra) for Ti plasma spray is 1.82 µm and for HA plasma spray Ra=1.59 to 2.94 µm. Another method used in surface alteration is by blasting with particles. In this approach, the implant surface is bombarded with particles of aluminium oxide (Al2 O3 ) or titanium oxide (TiO2 ) and by abrasion; a rough surface is produced with irregular pits and depressions. Roughness depends on particle size, time of blasting, pressure and distance from the source of particles to the implant surface. Chemical etching is another process by which surface roughness can be increased. The metallic implant is immersed into an acidic solution, which erodes its surface, creating pits of specific dimensions and shape. Concentration of the acidic solution, time and temperature are factors determining the result of chemical attack and microstructure of the surface. Another mode of surface treatment is sandblasting with large grit and acid etch. This surface is produced by a large grit (250 to 500 µm) blasting process followed by etching with hydrochloric sulfuric acid. The average Ra for acid etched surface is 1.3 mm and for sandblasted and acid etched surface, Ra=2.0 µm.
What’s pours characteristic?
Porous: Porous sintered surfaces are produced when spherical powders of metallic or ceramic material become a coherent mass with the metallic core of the implant body. Lack of sharp edges is what distinguishes these from rough surfaces. Porous surfaces are characterized by pore size, pore shape, pore volume and pore depth, which is affected by the size of spherical particles, temperature and pressure conditions of the sintering chamber.
What’s prosthetic interface? Most common types
It is the level at which the superstructure or the abutment connects to the implant body. It can be either external or internal. The most common external connection is the hexagonal (“hex”) type. The 0.7 mm high, 2.7 mm wide, straight external hex on a 4.1 mm diameter platform is considered the industry’s standard. Due to its strength and stability limitations, however, variations in the hex and platform have evolved. The standard external hex allows 4.0° to 6.7° of rotational wobble with 3°-5° of tipping depending on the type of hex. Full seating of abutment over fixture can only be verified by taking additional radiographs. Without intimate contact between the walls of the mating hexes, cyclic loading transmits forces directly to the fixation screw, which may cause it to repeatedly loosen.
What’s internal hex?
An internal hex in the implant is designed to prevent rotation of the abutments. Compared to an external hex, an internal hex allows a better protection against rotation of abutments and against gap formation at the implant abutment interface.
What’s external spline?
External spline by Calcitek acknowledges that its 0.4 mm spline connection allows 3° tipping thereby transferring forces to the abutment screw under lateral loading. However the butt joint shoulder of the spline connection can also trap soft tissue during abutment seating. Furthermore the 1.0 mm height of the spline connection can interfere with occlusal clearance and hinder establishment of anatomical contours on angled abutments.
What’s non hexed conical connection?
an ITI implant design which has a conical opening to an internally threaded shaft. Tightening an abutment with a matching conical surface provides lateral stability. It provides no interdigitation to resist rotation, which is of some significance in single tooth restorations. In order to assure contact with the mating conical surface, the abutment cannot be designed to seat on the top surface or ‘shoulder’ of the implant. This limitation prevents the use of abutments wider than the diameter of the conical opening and leaves the shoulder exposed to support the restoration. Without flush fitting abutments, there is no opportunity to prepare the margins to follow the natural contour of the tissue.
What’s non hexed Morse taper connection?
is provided by the Bicon Implant. A 1°-2° tapered abutment post frictionally fits into the non-threaded shaft of the implant, which has a matching taper. The body is designed with a series of fins for a press fit insertion procedure. This surgical protocol is dictated in part, by the implant’s prosthetic connection, which lacks a wrench-engaging surface. The connection also dictates how abutments are attached and stabilized and the type of emergence profile they can provide.
there are several potential esthetic and hygienic limitations with Non-hexed morse taper connection en numerate them (5)
I. The tapered mating surfaces of the implant and abutment must contact each other in order to create the frictional fit. This creates an undercut at the implant to abutment transition, which prevents extension of the restoration margin below the abutment’s height of contour. If the gingiva recedes or the implant is not adequately countersunk, the margin of the restoration can become exposed which will create an irresolvable esthetic problem.
II. Without an internal or external hex or other wrench-engaging surface, it is not possible to make a transfer impression and modify abutments for parallelism or contour on a working cast. Therefore, the dentist must modify the appropriate straight and angled abutment directly in the mouth, which is not an easy task with cross arch splinting of multiple implants.
III. Claims of Bicon’s frictional fit stability must be questioned, since the manufacturer’s recommended method of removing the abutment is simply to twist it with forceps.
IV. Striking the abutment with a sharp blow in the long axis of the implant completes seating the Biocon implant. This method of attachment cannot be repeated as easily as tightening a screw with a torque wrench, and will not work if the abutment hits the bone crest before the taper interlocks. V. In order to initially ensure a subgingival margin, the manufacturer recommends that the implant be placed 3 to 5 mm below the crest of bone to lower the height of the abutment contour for contact with the crest of ridge. This surgical procedure sacrifices important cortical bone support and requires bone contouring at the time of abutment seating to match the base of the abutment.
In bone factors what’s the most favorable quality of bone? What’s success depend on?
The most favorable quality of jawbone for implant treatment is that which has a well-formed cortex and densely trabeculated medullary spaces with good blood supply. Bone, which is predominantly cortical, may offer good initial stability at implant placement but is more easily damaged by overheating during the drilling process,. Success is highly dependent upon a surgical technique, which avoids heating the bone. Bone should not be heated beyond 43°C, since alkaline phosphate begins to breakdown. Gentle surgical technique with the speed of drilling equipment not to exceed 2000 rpm and copious amount of sterile irrigation with internally irrigated drills should be used. The tapping procedure for threading and fixture installation into bone requires a drilling speed between 15 to 20 rpm.
