Osseointegrated Implants Part 1

Question 1

What are indications of implant denture?

Answer 1

1. Edentulous patient with history of difficulty in wearing removable dentures.
2. When there is severe change in complete denture bearing tissues.
3. Poor oral muscular coordination.
4. Para-functional habits that compromise prosthesis stability.
5. Unrealistic patient expectations for complete dentures.
6. Hyperactive gag reflex.
7. Low tissue tolerance of supporting mucosa.

Question 2

What are contraindications of implant denture?

Answer 2

1. High dose irradiated patients.
2. Patient with psychiatric problems such as psychosis, dysthorphobia.
3. Hematological systemic disorders.
4. Pathology of hard and soft tissues.
5. Patient with drug, alcohol or tobacco chewing abuse.

Question 3

What are charesterstics of implants in relation to natural teeth?

Answer 3

• 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.

Question 4

Categorize implants into primary and biodynamic classification

Answer 4

dental implants fall into one of the following three primary groups: (a) Metal (b) Ceramics (c) Polymers
———
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

Question 5

Which type is osseo conductive? And what are bio mimics?

Answer 5

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.

Question 6

Why metals are selected? Which type is most used?

Answer 6

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

Question 7

What’s the content of pure titanium? What are the uses of traces of contents of this implant?

Answer 7

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.

Question 8

Talk about dynamics of titanium with body. What is alternative to titanium?

Answer 8

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

Question 9

Types of ceramics and why they’re used?

Answer 9

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,

Question 10

What type of ceramic is preferred? Wry? What’s the dis advantage of ceramics?

Answer 10

Hydroxyapatite coated implants are preferred in cases where more rapid and enhanced bone implant contact is needed,

degradation of ceramic coatings

Question 11

What are types of polymers (3)? Why are they not used? What are their uses limited to?

Answer 11

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

Question 12

What’s ideal implant length and diameter?

Answer 12

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)

Question 13

What are most common implant shapes? Advantage of screw type? Also categorized into (4)?

Answer 13

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

Question 14

What’s the influence and type of surface charecherstics?

Answer 14

influences wound healing at the implantation

Smooth surface

Rough surface

Porous

Question 15

Describe smith surface in implants? What’s considered smooth and rough?

Answer 15

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.

Question 16

Describe rough surface? Enumerate methods of surface coating

Answer 16

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.

Question 17

What’s pours characteristic?

Answer 17

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.

Question 18

What’s prosthetic interface? Most common types

Answer 18

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.

Question 19

What’s internal hex?

Answer 19

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.

Question 20

What’s external spline?

Answer 20

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.

Question 21

What’s non hexed conical connection?

Answer 21

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.

Question 22

What’s non hexed Morse taper connection?

Answer 22

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.

Question 23

there are several potential esthetic and hygienic limitations with Non-hexed morse taper connection en numerate them (5)

Answer 23

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.

Question 24

In bone factors what’s the most favorable quality of bone? What’s success depend on?

Answer 24

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.

Question 25

What are factors compromising bone quality?

Answer 25

infection, irradiation and heavy smoking. The effects of the latter are results of a diminution of the vascular supply to the bone which compromises healing response, a feature that has been well described in the healing of fractures.

Question 26

Describe loading conditions in short

Answer 26

Following installation of an implant it is important that it is not loaded during the early healing phase. Movement of the implant within the bone at this stage results in fibrous tissue encapsulation rather than osseointegration. This has been compared to the healing of a fracture where stabilization prevents non-union. The Branemark system emphasizes on maintaining the fixtures unloaded for six months in the maxilla and three to four months in the mandible, mainly because of differences in bone quality.

No loading while healing is the basic guide to osseointegration.

Question 27

What’s the first stage in loading?

Answer 27

The surgical procedures are divided into two stages. The first stage is the installation of the fixtures into bone, allowing a 3 to 6 month healing period. The mucosa supported interim denture should not be worn for 1 to 2 weeks, which also helps to prevent breakdown of the soft tissue wound. Bone healing begins within first week after insertion of the fixture and reaches a peak at the third or fourth weeks. The initial healing tissues gradually become bony tissue after six to eight weeks. If fixtures are displaced or loaded during this interim healing period, fibrous tissue formation will occur.

Question 28

What’s second stage of loading?

Answer 28

The second stage is the connection of abutments to fixture. Due to these various sequences, the two stage surgical procedures are very important for successful osseointegration. Some systems employ a single stage approach in which the implant is installed so that it protrudes through the overlying mucosa, although avoidance of early loading is equally critical. Following the recommended healing period (3-6 months) abutments are connected to the implant to allow construction of prosthesis.

Question 29

Describe mechanisms of osteo integration? (7)

Answer 29

The healing process with Branemark system is the same as normal bone healing. The implant bone integration should ideally be like the primary healing where there is well-organized bone formation with minimal granulation tissue formation. To duplicate the primary bone healing, the surgery should be performed on healthy bone, free from infection and necrotic tissue.The healing process is sequenced as follows:

• Blood present between the bone and implant surfaces leads to blood clot.
• Phagocytic cells such as polymorphonuclear leukocytes, lymphoid cells and macrophages transform the blood clot. The phagocytic activity level peaks during the time between the first and third day after surgery. During this period formation of procallus occurs containing fibroblasts, fibrous tissue and phagocytes.
• The procallus becomes dense connective tissue and mesenchymal cells differentiate into osteoblasts and fibroblasts. This connective tissue is referred to as callus, including osteoblasts that appear on the fixture surface.
• The dense connective tissue then forms a fibrocartilagionous callus, usually forming between the fixture and bone.
• New bone penetrates and the new bone matrix is called the bone callus.
• This new bone matures, increasing in density and hardness.
• At this time, the prosthesis is attached to the fixtures and with stimulation or load by the prosthesis, bone remodeling occurs.

Question 30

Define implant dentistry and implant Prostho dontics

Answer 30

Oral Implantology (Implant Dentistry):It is the science and discipline concerned with the diagnosis, design, insertion, restoration and/or management of alloplastic or autogenous oral structures to restore the loss of contour, comfort, function, esthetics, speech and/ or health of the partially or completely edentulous patient (Carl E. Misch).

Implant Prosthodontics: It is the branch of implant dentistry concerning the restorative phase following implant placement and the overall treatment plan component before the placement of dental implants (

Question 31

What’s implant and implant prosthesis

Answer 31

Implant To graft or insert a material such as an alloplastic substance, an encapsulated drug or tissue into the body of a recipient

Implant Prosthesis: Any prosthesis (fixed, removable or maxillofacial) that utilizes dental implants in part or whole for retention, support and stability.

Question 32

What’s implant prosthesis, implant surgery and implant system?

Answer 32

Implant Prosthesis: Any prosthesis (fixed, removable or maxillofacial) that utilizes dental implants in part or whole for retention, support and stability.

Implant Surgery: The phase of implant dentistry concerning the selection, planning and placement of the implant body and abutment (GPT-7).

Implant System: Dental implant components that are designed to mate together. An implant system can represent a specific concept, inventor, or patent. It consists of the necessary parts and instruments to complete the implant body placement and abutment components.

Question 33

Define asseointegration- and endosteal implants

Answer 33

Osseointegration: The apparent direct attachment or connection of osseous tissue to an inert, alloplastic material without intervening connective tissue (GPT-7).

Endosseous Implant/Endosteal Implant: A device placed into the alveolar and/basal bone of the mandible or maxilla and transacting only on cortical plate (GPT7).

Question 34

What’s the difference between single stage and two stage implant surgery?

Answer 34

Single Stage Implant Surgery: Surgical placement of a dental implant, which is left, exposed to the oral cavity following insertion. This is the protocol used in non-submerged implant systems (Richard Palmer).

Two Stage Implant Surgery: Initial surgical placement of a dental implant, which is placed into the bone and then subsequently exposed with a second surgical procedure some months later.

Question 35

Describe implant body,

Answer 35

The portion of a dental implant that provides support for the abutment(s) through adaptation upon (eposteal), within (endosteal) or through (transosteal) the bone (GPT-7). The body is that portion of the implant designed to be surgically placed into the bone. It may extend slightly above the crest of the ridge.

Question 36

Describe healing l cover screw

Answer 36

The component of an endosteal dental implant system used to seal, usually on an interim basis, the dental implant body during the healing phase after surgical placement. The purpose of the healing screw is to maintain patency of the internal threaded section for subsequent attachment of the abutment during the second stage surgery (GPT-7).

Question 37

What’s Healing Abutment/Interim Endosteal Dental Implant Abutment

Answer 37

Any dental implant abutment used for a limited time to assist in healing or modification of the adjacent tissues (GPT-7).

After a prescribed healing period that allows a supporting interface to develop, second stage surgery is performed to uncover or expose the implant and attach the transepithelial portion or abutment. This transepithelial portion is termed a second stage permucosal extension, because it extends the implant above the soft tissue and results in the development of a permucosal seal around the implant.

Question 38

What’s implant abutment? And classification?

Answer 38

The portion of a dental implant that serves to support and/or retain any prosthesis (GPT-7).

Three main categories of implant abutments are described according to the method by which the prosthesis or superstructure is retained to the abutment: (i) an abutment for screw uses a screw to retain the prosthesis or superstructure; (ii) an abutment for cement uses dental cement to retain the prosthesis or superstructure; (iii) an abutment for attachment uses an attachment device to retain the removable prosthesis. Many manufacturers classify abutments as fixed whenever cement retains the prosthesis and removable when they are screw retained. Each of the three types of abutments is further classified into straight and angled abutments, describing the axial relationship between the implant body and abutment.

Question 39

What’s impression coping? Difference between indirect transfer and direct transfer?

Answer 39

Any device that registers the position of the dental implant body or dental implant abutment relative to adjacent structures (GPT-7).

Two basic techniques are used to make a master impression, and each use a different transfer coping based on the transfer technique performed in the mouth or on a mastercast. An indirect transfer coping utilizes an impression material requiring elastic properties. The indirect transfer coping is screwed into the abutment or implant body and remains in place when the set impression is removed from the mouth. The indirect transfer coping is parallel sided or slightly tapered to allow ease in removal of the impression and often has flat sides or smooth undercuts to facilitate reorientation into the impression. A direct transfer coping usually consists of a hollow transfer component, often square and a long screw to secure it to the abutment or implant body. After the impression material is set the direct transfer coping screw is unthreaded to allow removal of the impression from the mouth. The direct transfer coping takes advantage of impression materials having rigid properties or eliminates the error of permanent deformation because it remains within the impression on its removal.

Question 40

What’s implant analog?

Answer 40

An analog is something that is analogous or similar to something else. Implant analog is used in the fabrication of the master cast to replicate the retentive portion of the implant body or abutment. After the master impression is secured the corresponding analog (implant body, abutment for screw or other portion) is attached to the transfer coping and the assembly is poured in stone to fabricate the master cast.

Question 41

What’s healing and coping screw? And coping cylinder?

Answer 41

Hygiene Screw

It is placed over the abutment between prosthetic appointments to prevent debris and calculus from entering the internally threaded portion of the implant.

Coping/Gold Cylinder

It is a thin covering usually designed to fit the implant abutment and serve as the connection between the abutment and the prosthesis or superstructure. A prefabricated coping usually is a plastic pattern cast into the metal superstructure or prosthesis.

Coping Screw

The screw retained prosthesis or superstructure is secured to the implant body or abutment with a coping screw.

Question 42

What’s management of buccal canine displacement?

Answer 42

NB: the width of the maxillary canine is greater than that of the first premolar which in turn is greater than that of the deciduous canine.

Buccal displacement is usually associated with crowding, and therefore relief of crowding prior to eruption of the canine will usually effect some spontaneous improvement (Fig. 14.7). Buccal displacements are more likely to erupt than palatal displacements because of the thinner buccal mucosa and bone. Erupted, buccally displaced canines are managed by relief of crowding, if indicated, and alignment—usually with a fixed appliance.

In severely crowded cases where the upper lateral incisor and first premolar are in contact and no additional space exists to accommodate the wider canine tooth, extraction of the canine itself may be indicated. In some patients, the canine is so severely displaced that a good result is

unlikely, necessitating removal of the canine tooth and the use of fixed appliances to close any residual spacing.

More rarely, a buccally displaced canine tooth does not erupt or its eruption is so delayed that treatment for other aspects of the malocclusion is compromised. In these situations, exposure of the impacted tooth may be indicated. If the crown is located below the mucogingival junction, an open procedure to expose the crown is sufficient. However, if the crown is above the mucogingival junction, then a different approach is required. To ensure an adequate width of attached gingiva either an apically repositioned or, preferably, a replaced flap should be used. In the latter case, in order to be able to apply traction to align the canine, an attachment can be bonded to the tooth at the time of surgery. A gold chain or a stainless steel ligature can be attached to the bond and used to apply traction.