Dental Implants
Dental restoration
• Important factors:
– Performance, durability, longevity and cost of dental
restorations
– The patient's oral and general health
– The components used in the filling material
– Where and how the filling is placed
– The chewing load
Dental amalgam
• For the direct filling of decayed lesions or structural
defects in teeth
• Durable, easy to use, highly resistant to wear and
relatively inexpensive in comparison to other materials
• Supplied as a powder in bulk, tablet, or predosed capsule
form
• Combined of
– Mercury (supplied as a liquid in bulk, or predosed capsule
form), Silver, Tin, Copper
• Suppliers: Novo Nordisk, Dentsply International,
Lancer Orthodontics, Danaher, Kerr, …
Amalgam
Advantages.
– Used more than any other material to restore carious teeth
– Easy to insert into the cavity preparation and adapts readily to cavity walls
– In its initial set, or hardness, amalgam allows time for condensing
– Has an acceptable crushing strength
– Having a long life as a restoration
•
• Disadvantages
– Amalgam's color does not match the color of the teeth
– Can not be used on the visible surfaces of anterior teeth
– Amalgam will tarnish with time
• Highly polished a day or two after its insertion
– High thermal conductivity
• An intermediate base that will not conduct heat or cold as readily (low
thermal conductivity) is placed under the amalgam.
FDA Literature Review for Amalgam Safety
• In 1997, the U.S. Food and Drug Administration (FDA) and U.S.
Public Health Service concluded from a review of nearly 60
peer-reviewed studies that the “data does not support claims
that individuals with dental amalgam restorations will
experience adverse effects, including neurologic, renal or
developmental effects, except for rare allergic or
hypersensitivity reactions.”
Recently the FDA set out again to update its position on dental
amalgam based upon the literature that has been published
since the 1997 review.
In 2009 they concluded “that there is insufficient evidence to
support an association between exposure to mercury from
dental amalgams and adverse health effects in humans,
including sensitive subpopulations.”
http://www.fda.gov/MedicalDevices/ProductsandMedicalProcedures/DentalProducts/DentalAmalgam/ucm171117.html
• Low strength materials prepared by mixing a powder with a liquid
• Have lower heat conductivity than do metallic restorative
materials
• Advantages:
– More natural in appearance
– Easier and faster to use
• Types:
– Zinc phosphate cement
– Polycarboxylate cement
– Glass ionomer cement
– Zinc oxide
• Disadvantages :
– Relatively low strength, varying degrees of solubility in mouth
fluids, and setting shrinkage
• Clinical Uses:
– Zinc phosphate cement is used both as an intermediate base and as a
cementing medium.
• Intermediate base protects the pulp from sudden temperature changes
that may be transmitted by the metallic restoration.
• Cementing medium. Zinc phosphate cement is used to permanently
cement crowns, inlays, and fixed partial dentures upon the remaining
tooth structure.
– The cementing medium does not cement two objects together. Instead,
the cement fills the space between the irregularities
• Chemical Composition.
– Powder. The primary ingredients of zinc phosphate cement powder
are zinc oxide and magnesium oxide.
– Liquid. The liquid used with the powder is phosphoric acid and water
in the ratio of two parts acid to one part water. The solution may also
contain aluminum phosphate and zinc phosphate.
• Uses:
– Cementing medium
– Intermediate base
– Temporary restorative material
• Composition
– Powder. contains zinc oxide, 1 to 5 percent magnesium
oxide, and 10 to 40 percent aluminum oxide
– Liquid. Polycarboxylate cement liquid is approximately a 40
percent aqueous solution of polyacrylic acid copolymer with
other organic acids such as itaconic acid
• Properties
– Lower compressive strength than Zinc-Phosphate
– Setting reaction produces little heat Unlike zinc phosphate
cement
• Translucent, tooth-colored materials made of a mixture of
acrylic acids and fine glass powders
• Used to fill cavities, particularly those on the root surfaces of
teeth
• Can release a small amount of fluoride (in the case of decay)
• Less tooth structure can be removed
• Low resistance to fracture
– Used in areas not subject to heavy chewing pressure
– Used in small non-load bearing fillings
• Ionomers experience high wear when placed on chewing
surface
• Advantages
– Inherent adhesion to tooth structure
– High retention rate
– Little shrinkage and good marginal seal
– Fluoride release and hence caries inhibition
– Biocompatible
– Minimal cavity preparation required hence easy to use on children in
and
suitable for use even in absence of skilled dental manpower and
facilities
• Disadvantages
– Brittle
– Soluble
– Abrasive
– Water sensitive during setting phase.
– Not inherently radiopaque though addition of radiodense additives
such as barium can alter radiodensity
Composite Fillings
• Mixture of glass or quartz filler in a resin medium that
produces a tooth-colored filling
• Provide good durability and resistance to fracture in small-to- mid
size restorations that need to withstand moderate chewing
pressure
• Less tooth structure is removed when the dentist prepares the
tooth, and this may result in a smaller filling than that of an
amalgam
• The cost is moderate and depends on the size of the filling and
the technique used by the dentist
• It generally takes longer to place a composite filling than what
is required for an amalgam filling
• The cavity must be kept clean and dry during filling
 Composite Resin Fillings (FDA)
• The most common alternative to dental amalgam
• Sometimes called “tooth-colored” or “white” fillings
because of their color
• Made of a type of plastic (an acrylic resin) reinforced
with powdered glass
• Advantages:
– Require minimal removal of healthy tooth structure for
Placement
• Disadvantages:
– May be less durable than dental amalgam and may
need to be replaced more frequently
--Discoloration over time
Indirect Restorative Dental Materials
• Porcelain-fused-to-metal
– Provides strength to a crown or bridge
– Very strong and durable
– More of the existing tooth must be removed to
accommodate the restoration
– Highly resistant to wear
– Allergic reaction may appear with by the using metals
Dental Implantation
• Dental extraction: The most frequent surgical procedure
performed upon humans
• Traumatic, congenital, or metabolic causes
So
• Denture: the most frequently employed prosthesis
– Complete or partial
– Fixed
• Most desirable
– Removable
• Most often, because of ease of production as well as economy
Complete, removable dentures are the prosthetic
replacement used by most edentulous people
 Alternative Solutions
 Partial and Full Dentures
 Crowns
 Bridges
Dental Crowns
• In a dental crown the tooth is restored with the
help of some material (porcelain) which is lined over
the top of a tooth
• Are used mostly to repair the look of the teeth
Dental Bridges
• Multiple crowns fused together
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Subperiosteal implants
– Typically lie on top of the jawbone, but under gum tissues
– Do not penetrate into the jawbone
– Cobalt based
• Endosseous implants
– Surgically inserted into the jawbone
– Titanium and titanium alloy, aluminum oxide, and surface coatings
of hydroxyapatite
• Transosseous implants
– Surgically inserted into the jawbone
– Penetrate the entire jaw
– Secured with a device similar to a nut and a pressure plate
Severely resorbed, toothless lower jaw bone,
which does not offer enough bone height to
accommodate Rootform Implants as anchoring
devices
Bone Grafting
• Bone grafting to rebuild reduced jawbone
• Fill in jawbone defects allowing the placement of
dental implants
• Autografts usually the hip
• Allografts are taken from human donors
• Xenografts are harvested from animals most
commonly bovine (cow)
• Alloplastic grafts are inert, man made synthetic
materials
A. Plate-form implant :
Made of pure titanium
• With one or two metal on one long side like
fork
• Placed in the jaw to support crowns or bridges
Designed for the toothless lower jaw only
• Surgically inserted into the jaw bone in three different
areas
– The left and right back area of the jaw
– The chin area in the front of the mouth
Endosteal or Endosseous implant
C.Root form implant
Since
the
introduction
of
the
Osseointegration concept and the Titanium
Screw by Dr. Branemark, these implants
have become the most popular implants in
the world today.
Root form implant shape:
Other variations dwell on the shape of the Root
form implant. Some are screw-shaped,
others are cylindrical, or even cone-shaped
or any combination thereof.
The two attachments
The plate on the bottom is firmly
pressed against the bottom part
of the chin bone
• The long screw posts go
through the chin bone
• The two attachments that will
protrude through the gums can
be used to attach an
overdenturetypeprosthesis.
long screw posts
The plate
DENTAL IMPLANT
• An artificial titanium fixture
(similar to those used in orthopedics)
• Placed surgically into the jaw
bone to substitute for a missing
tooth and its root(s).
 Losing tooth/teeth is not new problem
 It is possible to replace teeth that look & function
like natural teeth
 Implants is one of the means of achieving this
through osseointegration (biological adhesion of
bone tissue & titanium)
 Pioneered by prof. Per-Ingvar Branemark in
1952 ( Swedish orthopedics' surgeon)
In 1952, Professor Per-Ingvar
Branemark, a Swedish surgeon,
while conducting research into
the healing patterns of bone
tissue, accidentally discovered
that when pure titanium comes
into direct contact with the
living bone tissue, the two grow
together to form a permanent
biological adhesion named as
"osseointegration".
 Implants do not involve preparation of the
adjacent teeth,
 they preserve the residual bone,
 and excellent aesthetics can be achieved.
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However, it is expensive,
the patient requires surgery,
time consuming,
and technically complex.
 Increasing the support, stability, and patient satisfaction
for a full lower denture
 Increasing the patient's comfort in chewing
 Increasing the patient's confidence in smiling and
speaking
 Increasing the patient's overall psychological health
 Replacing one or more teeth as single units with crowns
 Aesthetics
 Providing support for a partial denture
Biocompatibility of Dental Material
Desired Mechanical Properties
• High yield strength
• Modulus close to that of bone’s
• Changes in environment around implant
Surfaces
• Composition
• Ion release
• Surface modifications
• Problem:
– Dental implant surface change with time due to
oxidation, precipitation…
• Possible solutions:
– Oxide layers ( minimize ion release)
– Prosthetic component from noble alloys
– Phase stabilizers other than Al & V (eg. Ti13Nb-13Zr, Ti-15Mo-2.8Nb )
• Surface Modifications
Screw Implants
Left to Right:
•TPS screw,
•Ledermann screw,
•Branemark screw,
•ITI Bonefit screw
Cylinder Implants
Left to Right:
•Integral,
•Frialit-1 step-cylinder,
•Frialit-2 step-cylinder
First Surgical Phase (Implant Placement)
Under Local anesthetic the dentist places dental
implants into the jaw bone with a very precise surgical
procedure. The implant remains covered by gum tissue
while fusing to the jaw bone.
Second Surgical Phase (Implant Uncovery)
After approximately six months of healing. Under local
anesthetic, the implant is exposed and a healing post is
placed over top of it so that the gum tissue heals around
the post.
Prosthetic Phase (Teeth)
Once the gums have healed, an implant crown is
fabricated and screwed down to the implant.
Interface
geometry
•External – Internal
•Hexagonal –
Octagonal – Cone
•Rotational – non
rotational
•Height and Width
 The financial investment is greater. (Single implant costs
anywhere from $500 - $6000)
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Treatment can take up to 9 months.
There is a risk of infection and other complications.
An implant may loosen and require replacement.
Implant procedures may be challenging for some
patients.
 Bruxism is a significant component of failed implants.
 Patients with certain medical complications should not
have implants.
 Psychological evaluation
 The dentist assesses the patient's attitude, ability to
cooperate during complex procedures, and overall
outlook on dental treatment.
 Dental evaluation
 The dentist evaluates the condition of the teeth, soft
tissues, areas of attached and unattached tissue, and
the height and width of the edentulous alveolar bone
ridge.
(Cont’d)
(Cont’d)
 Medical evaluation
 The dentist assesses any existing medical conditions
that could worsen as a result of the stress of implant
surgery.
 Radiographs
 Panoramic and cephalometric radiographs, as well as
tomograms, are needed to evaluate the height, width,
and quality of bone.
 Definition:
A time-dependant healing process where
by clinically symptomatic rigid fixation of
alloplastic
materials
is
achieved,
and
maintained, in bone during functional loading.
(Zarb & Albrektson,1991)
1.
2.
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5.
6.
Implant biocompatibility
Implant design
Implant surface
Implant bed
Surgical technique
Loading condition
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Materials used are:
Cp titanium (commercially pure titanium)
Titanium alloy (titanium-6aluminum-4vanadium)
Zirconium
Hydroxyapatite (HA), one type of calcium
phosphate ceramic material
 Osseointegration interface:
 Osseointegration
 Biointegration
 Cylindrical Implant
Some investigators explain the lack of bone steady
state by overload due to micromovement
of the
cylindrical design, whereas others incriminates an
inflammation/infection caused particularly by the very
rough surfaces typical for these types of implant.
 Threaded Implant
In contrast, Threaded implants have demonstrated
maintenance of a clear steady state bone response.
To enhance initial stability and increase surface contact,
most implant forms have been developed as a serrated
thread.
Pitch, the number of threads per unit length,
is an important factor in implant osseointegration.
Increased pitch and increased depth between
individual threads allows for improved contact area
between bone and implant.
Moderately rough surfaces with 1.5µm also,
improved contact area between bone and implant
surface.
Reactive implant surface by anodizing (Oxide
layer), acid etching or HA coating enhanced
osseointegration
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Minimal tissue violence at surgery is essential for
proper osseointegration.
Careful cooling while surgical drilling is performed
at low rotatory rates
Use of sharp drills
Use of graded series of drills
Proper drill geometry is important, as intermittent
drilling.
The insertion torque should be of a moderate level
because strong insertion torques may result in
stress concentrations around the implant, with
subsequent bone resorption.
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Delayed loading:
1. A tow-stage surgical protocol
2. One-stage surgical protocol
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Immediate loading:
1. Immediate occlusal loading (placed within 48
hours postsurgery)
2. Immediate non-occlusal Loading (in single-tooth
or short-span applications)
3. Early loading (prosthetic function within two
months)
 How many teeth are missing?
 What is the degree of bone loss?
 Are the remaining teeth in a good position and
do they have a long-term prognosis?
 What does the patient expect for an end
result?
 What treatment will result in the best cosmetic
outcome?
 What is the patient's budget?
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I.
II.
III.
The evaluation of a patient as a suitable
candidate for implants should follow the same
basic format as the standard patient
evaluation, although some areas require
additional emphasis and attention:
Medical History.
Psychological Status.
Dental History.
The greater the surface area of the implant-bone system,
the less concentrated the force transmitted to the crest of
bone at the implant interface. Similarly, the greater the
surface area of the implant-bone system, the better the
prognosis for the implant.
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For each 0.25 mm increase in diameter, the surface area of a
cylinder increases by more than 10 per cent;
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For each 3.0 mm increase in length , the surface area of a
cylinder increases by more than 10 per cent.
 Ideally, occlusal forces should be directed along the
long axis of the implants. Therefore ,The angle of
the osseous ridge crest is a key determinant of
implant angulation.
 the distance between an implant and any adjacent
"landmark" (natural tooth or another implant), which
should be not less than 2.0 mm.
 The number of implants, their respective lengths
and locations, the quality of bone support, the
posterior ridge anatomy, occlusal forces, and the
opposing dentition are of greater importance in
determining the appropriate cantilever than a
suggested formula.
 One method is to draw a line through the most
anterior implant, and another through the two
most posterior implants. The distance between the
two lines can then be measured. A suggested
maximum cantilever would be 1.5 times this
distance.
Dr,salah hegazy
Dr,salah hegazy
Dr,salah hegazy
Dr,salah hegazy