dental implant supported maxillo facial prosthesis. /certified fixed orthodontic courses by...

OSSIOINTEGRATED IMPLANTSIN

MAXILLOFACIAL PROSTHODONTICS

www.indiandentalacademy.com

INDIAN DENTAL ACADEMY

Leader in continuing dental educationwww.indiandentalacademy.com


CONTENTSIntroduction to Maxillofacial Prosthodontics.

Etiology of Maxillofacial defects.

Introduction to Maxillofacial osseointegration.

History of Maxillofacial osseointegration.

Differences between oral and Maxillofacial osseointegration.

Advantages of Maxillofacial implants over conventional adhesives.

Cost effectiveness of Maxillofacial implants.

Criteria of success of Maxillofacial osseointegration

Success rates of Maxillofacial osseointegration.

Patient assessment and selection.www.indiandentalacademy.com

Treatment planning.

Surgical technique for placement of Maxillofacial implants.

Auricular prosthesis.

Ocular prosthesis.

Nasal prosthesis.

Midfacial prosthesis.

Oral prosthesis.

Skin response at abutment sites.

Osseointegration in irradiated patients.

Complications around percutaneous implants.

Fallow up and management.

Review of literature.

References.www.indiandentalacademy.com

INTRODUCTION TO MAXILLOFACIAL PROSTHODONTICS

Def : The branch of Prosthodontics concerned with the

restoration and/or replacement of the stomatognathic

and Maxillofacial structures with prostheses that may or

may not be removed on a regular or elective basis.


It can be expected that a facial deformity may have a

significant impact on a patient's self image and ability to

function and interact socially. The emotional insult and

consequent interference with quality of life may be far

greater than that might be suggested by either the quantity

or nature of the tissue defect. The rehabilitation of these

patients with a prosthesis that replaces the missing tissue

functionally and esthetically can bring back not just their

appearance but also the confidence which is needed to live

in a civilized society.www.indiandentalacademy.com

ETIOLOGY OF MAXILLOFACIAL DEFECTS

The etiology of Maxillofacial defects falls into two categories.

1. congenital defects:

The microtia and agenesis of ear are associated with several

congenital syndromes. Treacher collins, crouzon’s, and

Pierre robins are some of the syndromes that are associated

with facial deformities, palatal cleft and significant

malformation external ear. congenital abnormalities are

unlikely to result in complete absence of the eyes or nose.


2.Acquired defects :

Traumatic loss such as vehicle accidents, explosive

injuries and gun shot wounds can result in loss of

facial structures. The ear and nose are also frequently

lost in bite attacks.

Surgical removal as a result of oral and facial

carcinomas.


Introduction To Maxillofacial Osseointegration

For a facial prosthesis to be successful, it must meet criteria

of aesthetic acceptability, functional performance,

biocompatibility, and longevity. As a result of the problems

encountered with adhesive systems, advocacy of the use of

mechanical retention has been made. In the past, mechanical

retention has involved the engagement of divergent

undercuts within the defect or the use of external retention by

headbands, elasticized retention, spectacle frames, or other

methods.www.indiandentalacademy.com

Frequently, inherent retention within the defect is absent or

external forms of retention are unacceptable to the patient.

With these historically crude approaches to facial prosthesis

retention, it is not surprising that methods of retention

continued as a source of debate with little resolution and

remained the primary limiting factor to success with

prosthetic reconstruction. With the introduction of

osseointegrated implants to facial prosthetics, there is an

opportunity to provide secure retention of prostheses without

jeopardizing the integrity of the skin and underlying tissues

or the prosthesis.www.indiandentalacademy.com

History of Maxillofacial Osseointegration

• In 1975, Branemark postulated that a skin-penetrating

implant should be possible based on the principles of

dental Implants.

• Following the pioneering work by Branemark and his co-

workers, the first clinical trial on skin-penetrating

osseointegrated implants was conducted in 1977 at

Sahlgren's Hospital in Goteborg, Sweden, where

specifically designed implants were placed in the

mastoid region to support a bone conduction hearing aid.www.indiandentalacademy.com

• In 1979, the first implants were placed in the mastoid

region to retain an auricular prosthesis.

• In February 1988, the Bone Anchored Hearing Aid

(BAHA) was approved for use within the Swedish health

system by the Swedish National Social Welfare Board.


• A conference was held in Goteborg, Sweden, on

September 1,1988, to consider bone anchored implants in

the head and neck region. A report on this landmark

conference was compiled by the Swedish Council on

Technology Assessment in Health Care.

• This report was the founding document on the

introduction of Maxillofacial osseointegration in head and

neck reconstruction.


• On January 13, 1995, the food and drug administration

provided clearance to Nobel Biocare USA, to market the

branemark Maxillofacial implant system.

• Since 1986, international conferences on Maxillofacial

osseointegration have been convened and reports

published from that time have confirmed the efficacy and

predictability of Maxillofacial osseointegration.


Historical development of Maxillofacial osseointegration in relation

to the development of intraoral osseointegrated implants.


Differences Between Oral and Maxillofacial Rehabilitation

Oral cavity Extraoral environment

Saliva Air exposure

Oral Microflora Skin Microflora

Mucosal covering Skin covering

plaque Keratin, sebum, sweat,

More standardized anatomy Highly variable local anatomy

Longer implant lengths Shorter implant lengths

Higher loading forces Lesser loading forces

Lesser incidence of radiation therapy

Higher incidence of radiation therapy

Varying aesthetic demands of prosthesis With main emphasis on function

Highly dependent on Aesthetics.


Maxillofacial implant fixtures

are fabricated from pure

titanium. They are available in

either 3 mm or 4 mm lengths

and with a 5-6 mm diameter

flange. The flange facilitates

initial stabilization of the

implant and prevents undue

penetration into interior

compartments.


Advantage of Maxillofacial implants over conventional adhesives

• Improved retention and stability of prosthesis.

• Elimination of occasional skin reactions to adhesives.

• Ease and enhanced accuracy of prosthesis placement.

• Improved skin hygiene and patient comfort.

• Decreased daily maintenance associated with removal and

reapplication of adhesives.

• Increased longevity of prosthesis.

• Enhanced esthetics at the lines of junction between the

prosthesis and skin.www.indiandentalacademy.com

Cost effectiveness of Maxillofacial implants

Time interval, (yrs) Adhesive

retained

Maxillofacial

osseointegrated

implant retained

1

5

10

20

Maintenance cost

Total Cost

3,056

8,418

15,278

28,518

2,910

31,428

6,419

7,946

12,748

19,077

2,565

21,642www.indiandentalacademy.com

Criteria of success of Maxillofacial implants

The Swedish Council on Technology assessment in

Health Care Jacobson et al.

1) The implants should be immobile, as verified by clinical examination.

1) Individual unattached implants should be immobile when tested clinically.

2) No prolonged symptoms, such as pain, infection, tactile disorders, or nerve damage, should be present in connection with the implants.

2) Individual implant performance should be characterized by the absence of persistent or irreversible signs and Symptoms such as pain, infections, neuropathies, or paresthesia.


3) Penetrated soft tissue

should be free from irritation in

at least 85% of the regular

outpatient postoperative check

ups.

3) Soft tissue reactions around

skin-penetrating abutments

should be of types 0 (reaction

free) or 1 (slight redness, not

demanding treatment) in more

than 95% of all observations.

4) At least 95% of the temporal

bone implants and at least

75% of other extra oral

implants should be functional

after 5 years.

4) A success rate of 95% in the

mastoid process and 90% in

the orbital region, in non-

irradiated bone tissue, at the

end of a 5-year observation

period should be a minimum

criterion for success.www.indiandentalacademy.com

Success rates of Maxillofacial implants (Non-irradiated)

Patients

treated, no.

Implants Inserted, no.

Implants

Integrated, no.

Success rate, %

Sweden 435 767 755 98.4

USA 84 268 253 94.4

Canada 84 186 182 97.8

Total 603 1,221 1,190 97.5


Success rates of Maxillofacial implants (Irradiated)

Patients

treated, no,

Implants Inserted, no.

Implants

Integrated, no.

Success rate, %

Sweden 16 57 33 57.9

USA 11 51 33 64.7

Canada 7 36 34 94.4

Total 34 144 100 69.4


Patient assessment and selection

Maxillofacial reconstruction based on the principles of

osseointegration is always an elective procedure.

Because of this, it must be done only under optimum

conditions on carefully selected patients for whom the

potential benefits have been weighed carefully against

the known possible complications and risks. Additionally,

patients should be kept fully informed about all aspects

of the nature of treatment and be given a realistic view of

the likely outcome.www.indiandentalacademy.com

In selecting a patient for a particular reconstructive

procedure, attention should be focused whether it

represents the optimum form of treatment for an

individual's physical, psychological, and personal

circumstances and perceived quality of life.

Many factors and variables need to be considered

carefully, including age, the presence of any disease

process, the significance of any previous therapy,

alternative available treatments and the patient's own

wishes.www.indiandentalacademy.com

Special care should be exercised in evaluating children.

In many situations all information regarding the effects of

the condition will be gained from the parents, with little or

no input from the child. Although the parents concerns

are of most important and indeed their whole hearted

support for all phases of the rehabilitation is essential, it

is vital in all cases to understand the problem from the

patient's viewpoint.


Uncontrolled Diabetes Mellitus:

Diabetes patients are predisposed to tissue degeneration and

compromised healing with increased risk of infection and

vascular complications.

Hyperthyroidism:

Patients are sensitive to epinephrine used in local

anesthetics. When exposed to such catecholamine

coupled with stress and tissue damage (implant surgery), an

exacerbation of the symptoms of hyperthyroidism may occur

(thyrotoxicosis). This is a life threatening condition. The

treatment is deferred until a medical and laboratory

evaluation confirms control of the disorder.

EVALUATION OF SYSTEMIC DISEASES.


Adrenal disorders:

Patients with a history of adrenal gland disease, whether

hyper functioning or hypo functioning, face similar problems

related to dentistry and stress. The body is unable to

produce increased levels of steroids during stressful

situations and cardiovascular collapse may occur. Therefore

for patients with known adrenal disorders the physician

should be consulted before any implant related treatment.

Recent Myocardial Infarction (MI):

If surgery is done within 3 months of MI, the risk of another

MI is 30%.If within 3 – 6 months, it is 15%. After 12 months

the incidence of recurrent MI stabilizes at about 5%.www.indiandentalacademy.com

Hypertension:

Essential hypertension is treated with medications, many of

which have an impact on implant therapy because of their

numerous side effects. These include hypotension,

dehydration, sedation, and xerostomia, gingival hyperplasia

around teeth and implants and depression. Anxiety greatly

affects the blood pressure.

Pregnancy:

Implant surgery procedures are contraindicated for the

pregnant patient. The radiographs or medications that may

be needed for implant therapy and the increased stress are

being reasons. The elective implant surgical procedure

should be postponed till childbirth.www.indiandentalacademy.com

Osteoporosis:

The most common disease of bone metabolism the implant

dentist will encounter is osteoporosis, an age related disorder

characterized by a decrease in bone mass, increased micro

architectural deterioration and susceptibility to fractures. This

condition is common in post menopausal women. The bone

density affects the treatment plan, surgical approach, length

of healing and the nature of loading.

Hyperparathyroidism:

It has been noted that when skeletal depletion occurs as a

result of stimulation by the parathyroid gland, alveolar bone

may be affected before that of the rib.www.indiandentalacademy.com

Fibrous Dysplasia:

A disorder in which fibrous connective tissue replaces areas

of normal bone. It is found twice more commonly in women

than men and may affect a single bone or multiple bones,

twice more commonly in the maxilla than mandible. Implant

dentistry is contraindicated in the regions of this disorder.

Paget’s disease:

A slowly progressive chronic bone disorder where both

osteoblasts and osteoclasts are involved, but osteoblastic

activity is more predominant. The maxilla is more often

involved than the mandible. Oral implants are

contraindicated in the regions affected by this disorder.www.indiandentalacademy.com

Multiple myeloma:

Plasma cell neoplasm originating in the bone marrow.

Usually seen in patients between 40 – 70 years of age.

Pathologic fractures usually occur. Paresthesia, swelling,

tooth mobility and gingival enlargements are also seen.

Implants are contraindicated in these patients.

Smoking Habits:

Tobacco smoke decreases neutrophil count leading to

reduced phagocytic activity. Smoking is also associated

with decreased calcium absorption and delayed

secondary healing. It also contaminate a bone graft and

contribute to early bone loss during initial healing.www.indiandentalacademy.com

Radiation therapy:

Disruption of defense mechanisms, compromised

Endoosseous vascular system, and localized loss of

osseous vitality are the main insults to the tissues while

the patient undergoes radiation therapy. With regard to

bone, the osteogenic potential of the periosteum is most

severely affected. All these conditions can severely limit

the prognosis for reconstructive procedures. Such patients

may be subjected to osteoradionecrosis and should be

treated with caution only after the dentist consults the

radiotherapist.


TREATMENT PLANNINGTREATMENT PLANNING

Each case must be evaluated on the basis of its own

individual requirements; however, a number of fundamental

considerations are relevant to all cases.

On occasion, bone morphology will not permit ideal

configuration of fixtures, and as a result the retentive system

may take on a variation of geometric form.


The auricular prosthesis :

In congenital cases, developmental remnants in the line of

the prosthesis, or anterior to it, must be considered for

removal if they are counterproductive to the final result. If

practical, they can be reshaped to simulate a tragus to help

mask the anterior border of the prosthesis.


• Two flange fixtures are more than adequate to retain the

average size prosthetic ear.

• Implants are ideally positioned in a semilunar fashion

beneath the thickest parts of the ear to provide maximum

room for restorative materials with minimal over contouring

of the part.

• Ventilation slits can be positioned conveniently around the

distal periphery of the ear base.


The orbital prosthesis:

Preliminary data have indicated a higher failure rate of

fixtures in the orbital rim than elsewhere in the cranial

skeleton.

It is important that fixtures be placed 15 mm or more

apart because of the radial geometry of the orbital cavity.

Ventilation slits can be placed conveniently at the eyelid

conjunctival line angle to minimize condensation and

irritation within the defect.


The nasal prosthesis:

The state of the maxillary dentition and presence or

absence of anterior teeth can be important diagnostic

factors in selecting fixture type, length, and location.

Ventilation requirements for nasal prostheses are

facilitated via perforations within the artificial nares.

Fixture sites for large midfacial defects are dictated by the

residual anatomy. The residual zygomatic arches can also

be used for the horizontal placement of long fixtures which

offer excellent anchorage points.


The combination intraoral extraoral prosthesis:

Defects requiring this combination type prosthesis involve

loss of facial continuity combined with partial or total

maxillectomy. They are of surgical or traumatic origin.


Surgical technique for placement of Maxillofacial implants

The first patient treated with a Maxillofacial prosthesis

retained on skin-penetrating osseointegrated implants was

operated on in 1979. This was a patient who was missing

his right external ear as a result of tumor surgery. The

surgical technique was based on the intraoral procedure

developed by Branemark. Four implants were placed in the

mastoid process and allowed to integrate without any load

for 3 months. The second stage procedure was performed

and skin-penetrating abutments were connected to the

implants, and a silicone rubber prosthesis made. www.indiandentalacademy.com

When the technique was Introduced in 1979, four implants

were used for the retention of an auricular prosthesis. In

some cases there was not room for four, and only three and

in some cases only two implants were used for the retention.

The two-stage procedure was used until 1988, and one

stage procedure started in 1989.


“We noted no higher rate of implant losses in these cases.

We also noted some important advantages with the use

of only two implants. It was much easier for the patient to

clean the implant area, which is important to avoid

adverse skin reactions. The skin bridges between the

implants were, in cases with four implants, often too

narrow and more vulnerable, resulting in a risk of adverse

skin reactions”.


One-Stage Surgical Technique for Auricular Implant Placement

Implant Site Selection: This must be done before the

patient is taken to surgery. The external ear canal is a good

landmark. The ideal placement is 18 to 22 mm from the

center of the external auditory meatus, and on the left-hand

side it is between the 1-0’ and 2-0'clock positions for the

upper cranial implant and between the 3:30 and 4:30

positions for the caudal implant. The reason for this is that

the implants and the bar construction will then be located

underneath the antihelix ridge. This is important to be able to

achieve an adequate depth and contour of the prosthesis. www.indiandentalacademy.com

Marks are made with surgical ink where the implants

should be placed, and the area is cleaned and patient is

draped in the usual way. The incision line, usually 7 to

10 mm behind the intended implant sites is marked.

10ml of 2 % lidocaine with epinephrine is injected, and

the incision is made down to the periosteum. That flap is

folded anterior and kept in place with two self-retaining

retractors.


Implant Placement:

The positions of the implant sites are checked and marked

in the periosteum. In the mastoid tip area the air cells are

larger and the cortical shell sometimes is fairly thin. A

6 mm wide incision is made in the periosteum and the

drilling with a guide drill is started. During all drilling

procedures, generous cooling with saline solution is

important.


When the lower implant is in place, the position of the

upper implant is selected. The distance between the two

implants should be at least 15 to 20 mm. The position of

the cranial implant often will be in the temporal bone where

the bone in most cases is dense and thicker. The drilling in

the cranial site is started with a 3 mm guide drill. If bone is

still found in the bottom, a drill that will provide space for a

4mm implant is used.


It is important to make sure that the whole length of the

guide drill has gone down. The reason is that the next

drill, which is the spiral drill with a countersink edge,

does not cut at the tip. The drills are made of stainless

steel and 1,500 to 3,000 rpm is used. The next steps are

made at slow speed, 8 to 15 rpm, and with titanium tap.


The titanium tap is

picked up, with the

connector placed in

the low speed hand

piece. The tap is kept

over the entrance and

the direction is

checked carefully.

Adequate cooling is

used when the tap is

removed.www.indiandentalacademy.com

The implant mount is picked up with the fork shaped

instrument and the screwdriver. The implant mount is

screwed on top of the implant. The implant site is

cleaned of soft tissue and bone fragments by flushing

with saline and using a blunt dissecting instrument. The

implant mount with the implant is picked up with the

adapter on the hand piece of the drill and kept over the

hole. The direction is checked. With the drill at low

speed, the implant is allowed to find its way into the

threaded hole using slight pressure.


When the implant is all the way down, the hand piece is

turned slightly counterclockwise to release the implant

mount from the connector. It is Important not to tilt the

implant mount when disconnecting it from the hand

piece. The implant mount is then removed from the

implant. It is then covered with the thin skin and sutured

in place.


Soft Tissue Management :

1) The immobility of the skin close to the implants relative

to the underlying bone and the abutment is very important.

This is achieved by making a subcutaneous tissue

reduction at the implant site.

2) There should be no hair follicles present in the skin at

the Implant site.

These two goals can be achieved by reducing the

thickness of the flap or by using a split-thickness skin graft.


Abutment Connection :

With a 4mm disposable skin punch, a hole is made

immediately over the implant and the abutment is secured to

the implant with an internal screw. When the fit is

established, the abutment screw is tightened firmly. Healing

caps are then attached to the abutments to keep ointment

soaked gauze down toward the skin to avoid postoperative

hematoma and swelling. The surgical procedure is finished

by applying a firm mastoid dressing for 1 day. After this, only

a light dressing is needed.


Postoperative Care :

After 5 to 7 days, the packing and the healing caps are

removed and the surgical field is left open. A mild

antibiotic ointment is prescribed and the patient is told to

use that for a week or two and then just occasionally.

Three weeks after operation the patient may start to

clean the area with soap and water. The implants are left

without any load for 3 months.


Orbital prosthesis

Historically, different retentive methods have been used to

retain Orbital prostheses. Skin adhesives or double sided

tape is capable of adequate retention but may lead to the

complications of skin irritation, loss of prosthetic margin

integrity, discoloration, and misalignment. Mechanical devices

such as eyeglasses are useful, but they have limitations such

as having to wear the glasses, and movement of the facial

muscles independent of the eyeglass frames. The success

rate in orbital bone has ranged from 92% to 100% in

nonirradiated patients and 45% to 79% in irradiated ones. www.indiandentalacademy.com

Patient Selection :

The majority of patients who have undergone

exenteration were been treated for life threatening

neoplasms or aggressive infections involving fungus.

The exenteration procedure consists of removal of the

entire soft tissue contents of the orbit, extra ocular

muscles, fat, and periorbita. The remaining orbital

volume or depth of the socket, influences the options to

offer the patient.


Total exenteration allows adequate spacing for proper

positioning of a prosthesis. A subtotal exenteration or a

partially filled orbit restricts the facial prosthesis to being

thin, with a less natural appearance.

Because the orbital walls are thin, only the superior,

lateral, and inferior orbital rims are suitable for

osseointegration of titanium implants.


Surgical Procedure :

The osseointegration procedure is performed in two

stages. In the first stage the titanium implants are placed

into the orbital rim and the implants are allowed to bond

to bone through osseointegration. The second stage is

performed 3 to 4 months later when tissue penetrating

abutments are attached to the initial implants.


Stage 1

It can be performed under general or local anesthesia. A

skin incision is marked with gentian violet or a marking

pen along the orbital rim at the designated locations. The

skin incision is made just anterior to the rim, and a flap of

skin, muscle, and periosteum is elevated to expose the

bony rim. Typically, three to four sites are chosen for

implantation, with the superolateral and the inferolateral

rim the more frequent sites.


The initial drilling is done with an exploring cutting bur, which

produces a small hole. The orientation of this hole should be

directed toward the center of the orbit. This allows space for

any bridging apparatus used and the future prosthesis. If the

bone is adequate, a 3 - 4 mm spiral drill with a countersink

is used to form the final hole diameter. Next, the threading

of the hole is done with the threading tap. This step is

accomplished at the slow speed of 8 to15 rpm that allows

the precise cutting of bone needed for proper implant

setting.www.indiandentalacademy.com

• The titanium implant is selected for the hole depth (3 or 4

mm) and screwed into the threaded hole with an implant

mount on the drill.

• The implant has a cover screw placed that is screwed into

the internal threads of the implant.

• A topical antibiotic is applied with a pressure dressing. This

dressing is removed in 1 week.

• If the continuity of the orbital rim is disrupted, several

options are available for bony reconstruction to create a

bed for implant placement. Common sites for autogenous

bone grafts are the calvarial bone, iliac crest, and fibula. www.indiandentalacademy.com

Stage 2 :

This is done after 3 to 4 months. The second stage

involves the placement of Titanium abutments and the

proper thinning of the skin around them to prevent the

movement of skin adjacent to it. This step prevents skin

irritation and infection and allows integration of the skin

with the abutment. It is usually done under local

anesthesia.


A trephine is used to cut an opening over the implant. An

abutment is placed through the opening and attached to

the implant with an internal screw. The abutment can be

3 or 4 mm in height. The abutment is covered with a

healing cap. Antibiotic soaked gauze is wrapped around

the abutment to immobilize the skin.

Four to five weeks after stage 2, the patient is ready for

prosthesis fitting.


Nasal prosthesisNasal prosthesis

• Throughout the history the nose has been described as

the object of beauty and symbol of strength. The

amputation of nose has been the bitter price of social

dishonor and even the reason for military conflict in the

history.

• The nasal reconstruction has been credited to Indians.

Sushruta in his book “Sushruta Samhita” (600 BC)

described the use of a cheek flap for the reconstruction

of nasal tip.


In the total nasal defect, there is usually sufficient amount

maxillary bone that creates the inferior border of the piriform

aperture.

If the nasal defect involves only the lower portion of the

nose, only two osseointegrated implants inferiorly in the

maxilla are enough or further resection of the remaining nose

in the upper area is done to expose the nasal bones.

For aesthetic reasons, glabella and lateral maxillary sites are

poor choices for implants, because framework will interfere

with the aesthetic formation of the nose.


Stage I

An incision is made and the periosteum and skin are

elevated together. The location of the implants is

marked, and a 4 mm implant is usually placed in the

lower piriform aperture and 4 mm or 3 mm implants in

the nasoethmoidal area. It is extremely important to use

minimally traumatic technique, low speed drilling, and

copious irrigation.


Stage II

Approximately 3 months after the first stage, It is preferred to

open the old incision and the flaps are thinned and the

wound is approximated with a few sutures. The holes for the

penetration of the abutments are created with a punch or a

scalpel. The cover screws are removed, abutments are

placed such that the abutment extends approximately 3 mm

above the skin. Healing caps are applied, and a moderately

compressive dressing is used to facilitate adherence of the

flaps and to limit edema formation. The wound is allowed for

2 weeks to heal before the prosthetic work is started. www.indiandentalacademy.com

Attachments :

The decision is made about using a metal bar to connect

the abutments for a clip on attachment or using

individual magnets. In general, metal bars work better in

the area of the nose. The bar has the additional

advantage that it limits rotational forces on the implants.

once the metal bars or magnets have been placed, the

work of attaching the prosthesis can be started.


Framework Design

Framework design must consider:

• Space available, including space allowance for

retention clip plate or magnet plate;

• Length of framework extension from abutments and

need for location of cross-bracing stabilization;

• Establishment of sufficient airway;

• Access for cleaning periabutment tissues and nasal

cavity;


• Amount of projection of the framework from the face in

the coronal plane;

• Facial tissue movement that might affect the fit or

retention of the nasal prosthesis;

• Ease of prosthesis application and patient capabilities;

and

• Anticipation of nasal prosthesis mold design.


For nasal prostheses, a midline clip and framework retention

is best in most cases. The framework is designed to be cast

in metal and is an inverted Y shape that has a cross brace

between the widest part of the Y near the abutments.

The advantages of this design are that it:

1) Allows maximum bilateral air flow.

2) Provides for vertical and horizontal clip orientation,

preventing the misapplication of the facial prosthesis; and

3) Provides adequate access to the nasal cavity and

periabutment tissues for hygiene maintenance. www.indiandentalacademy.com

As part of the wax framework model, plastic sprues 2 mm in

diameter are cut and positioned as the vertical stem and

transverse brace of the inverted Y. There should be enough

space below the cross brace, so that the periabutment

tissues can be accessed for hygiene maintenance.

Triangular segments of the Y should be as far away from the

walls of the nasal cavity as possible, so cleaning of septal

surfaces of the internal nose can be accomplished. The stem

on the inverted Y should be as short as possible but still

allow the attachment of a vertically oriented clip.


Disadvantages of adhesive retained prosthesis.

• Adhesive tapes will not stick to the silicone and require

daily trimming. They may cause inadvertent margin loss

and subsequent unaesthetic thick edges.

• The pastes and liquid aromatic cements require daily

removal which can cause frictional damage the extrinsic

colour of facial surface.

• Some patients will also develop allergic reactions to

these substances.www.indiandentalacademy.com

• The silicone base adhesives are extremely adhesive on

silicone prosthesis but they tend to damage fine margins

with daily prosthesis use.

• Adhesives may also limit the patients sense of security.

• Patients with altered skin sensation may be unaware of

loosening or fallen prosthesis.

• Some adhesives tend to loose the adhesive bond in

regions where perspiration can affect the interface.


MIDFACIAL PROSTHESIS.

A 63 year old man, was exposed to repeated surgical

procedures over several years, because of a basal cell

carcinoma of his face. After 10 years, tumor histology

changed into a squamous cell carcinoma.

A decision was made to provide him with not only a facial

prosthesis but also an implant supported fixed bridge in the

maxilla using osseointegrated fixtures.

Preoperative examination revealed that the quantity of

maxillary bone was not sufficient for a standard procedure,

so a bone graft had to be used.www.indiandentalacademy.com

Framework:

• The purpose of a fixed framework or substructure is to

retain the facial prosthesis.

• For retention in this particular case, a bar splint with clips

is one alternative to a bar splint with magnets.

• Two conventional bar constructions were made, one on

the three upper and the other on the three lower

maxillary abutments.


A third part of the framework connects the two bar

constructions. This part of the construction has an

exceptionally long span. Therefore, a Custom made

three dimensional framework was prepared. The goal

was to achieve stiffness with low weight. These fittings

were then soldered to the bar splints and enabled to

connect the three parts of the construction. The entire

framework was made out of a premachined gold alloy

clasp wire 2 mm in diameter, which was bent and

soldered to conventional 3 mm gold cylinders.


ORAL PROSTHESIS. Hemimaxillectomy:

In most defects with surgical resection of a minor or

major portion of the maxilla, adjacent bone tissue still

allows integration of anchoring fixtures. Careful

presurgical prosthetic planning is required, particularly in

major defects, in order to evaluate the correct positioning

of fixtures and adequate design of the retention

framework in relation to expected mechanical load.


Patient presentation 1

A 74 year old woman with a Hemimaxillectomy on left

side; there was enough remaining alveolar and basal

maxillary bone on the right side to accommodate

integrated fixtures. With a connecting bar extending into

the defect side, an overdenture obturator could be

adequately supported.



If the defect involves both sides, it is quite often difficult

to achieve anchorage in the anterior region. It is then

important to use not only any remaining posterior

portions of the maxilla in combination with bone grafts,

but also to install fixtures in the base of the zygomatic

bone. A carefully designed metallic framework can then

stabilize and retain a denture obturator prosthesis.



If, in addition to the bone defect, the upper lip has also

been removed, the soft tissue prosthesis can be retained

onto the denture obturator with magnets, as in this case

of a 72 year old woman. Bone grafts in both sinuses

were used to improve fixture anchorage.



This case shows the rehabilitation of a 20 year old man

presented with a major anterior maxillary defect with

inadequate bone anchorage of the teeth close to the

defect. These were removed, and after an adequate

healing time an autologous iliac bone graft was used to

substitute for the anterior maxillary segment. Special

long fixtures were used to anchor the graft. A long time

was allowed for incorporation and fixture integration. A

fixed bridge was then connected. www.indiandentalacademy.com

HEMIMANDIBULECTOMY

The Hemimandibulectomy is most commonly performed

as part of a tumor resection, for the treatment of

osteoradionecrosis or occasionally for osteomyelitis. It

leaves the patient with multiple problems, as regards to

esthetics and function. Because of the loss of bone and

teeth the patient cannot chew efficiently, speech is

adversely affected, and there is distortion of the facial

contours.


These problems are intensified by the displacement of

the mandibular fragments that remain, drifting under the

unopposed action of those muscles which are still

attached to the residual fragments. Shifting of the

remaining mandible toward the operated side and

malocclusion results.


Diagram showing restoration of

facial contour by bone graft but

persistent dental deficiency.

Diagram showing displacement of

mandibular fragments after partial

mandibulectomy.www.indiandentalacademy.com

The following are the advantages of reconstruction using

osseointegrated implants:

• They provide stability and retention for the prosthesis.

• They allow the use of a fixed or removable prosthesis.

• It avoids the preparation of remaining teeth as abutments.

• It avoids the problems of the tissue borne prosthesis.

• It compensates for a diminished denture bearing area.

• It provides the stimulus needed for preservation and

maintenance of the bone graft.

The principal disadvantages are only two. These are the

additional cost and the additional surgery. www.indiandentalacademy.com

The abutments need to rise 3 to 4 mm above the

surrounding soft tissue to allow for ease of hygiene

maintenance. The special problem of salivary

incontinence is most likely to appear when, in addition to

the resection of the mandible, there has been significant

disturbance of the associated soft tissues with loss of

sensation and loss of proper muscle control.

osseointegrated implants can provide predictable

rehabilitation for the hemimandibulectomy patient with

both cosmetic and functional success.


THE CLEFTPALATE

• Edentulous patients with persistent unilateral or bilateral

cleft palate defects may be provided with a bone

anchored prosthesis, which not only substitutes for the

teeth but also obturates the oronasal communication.

• In most cases the available alveolar and basal maxillary

bone tissue is adequate in volume and mechanical

capacity for fixture anchorage.



A 52 year old man had a cleft palate. When the final

remaining tooth was removed he had insufficient retention

for his denture obturator. Because of inadequate soft tissue

availability, no bone grafting was performed, but each

section of the maxilla was provided with three fixtures in the

alveolar and basal maxillary bone. After integration, a

metallic bar was used to connect the abutments on each

side, and a mechanical clip connection was used to anchor

the overdenture obturator.



This patient, who was the first cleft patient reconstructed

according to the osseointegration procedure, was treated

at the Mayo Clinic, Rochester, Minnesota, in

collaboration with D. Tolman, E. Keller, and W. Laney.

A 69 year old woman with a unilateral cleft which was

closed with an iliac bone graft. A bar connects the

anchoring elements and provides mechanical retention

of the overdenture.


SKIN RESPONSE AT ABUTMENT SITE

Skin response to Percutaneus abutments has also been

considered as an indicator of success, by rating it on a

five point scale.

This five point scale is a result of the work of Holgers et al

in 1987 and has been adopted widely.


Class Description

0 No irritation: epithelial debris removed if present.

1 Slight redness: temporary local treatment.

2 Red and slightly moist tissue; no granuloma formation:

local treatment; extra controls.

3 Reddish and moist; sometimes granulation tissue:

revision surgery is indicated.

4 Removal of skin-penetrating implant necessary

as a result of infection.

R Removal of implant for reasons not related to skin

problems. www.indiandentalacademy.com

Grade I – slight redness

Grade II - red and slightly moist

Grade III - Red and moist Grade IV - INFECTION www.indiandentalacademy.com

The following conditions at skin penetration sites are

advocated.

1) Subcutaneous skin reduction;

2) Fixed, Nonmobile skin; and

3) Absence of hair.

Brown et al stated: "Fastidious adherence to these

principles, will almost always guarantee a favorable skin

reaction, but contravention of them will almost as surely

result in an unfavorable reaction."


Osseointegration in irradiated patients

when the irradiated patients are to be rehabilitated with use

of the osseointegration concept, it is necessary to be aware

of different factors influencing osseointegration, healing of

the soft tissues, and the risk of severe side effects in the

compromised tissues.

Such side effects include decreased healing rate of the soft

tissue over the implants, fistulation, skin or mucosa

infections, loss of implants, denuded bone around the

implants, and even osteoradionecrosis. www.indiandentalacademy.com

Among the non-irradiated patients, most implants are found

non-integrated at the second stage surgery or are lost during

the first year. After this time, the remaining implants seem to

be relatively well integrated and remain in the bone.

The irradiated group of patients has a different course.

Most of the implants are lost during the first 3 years, but

implants are lost throughout the follow up period; even up to

10 years or more after placement, osseointegration is lost.


Complication Patients, %

Loss of implant 35

Slow wound healing 18

Fistula 15

Wound dehiscence 12

Soft-tissue infection 10

Osteoradionecrosis 2

Rupture of major vessel 0

Flap necrosis 0

Complications In Irradiated Patients


In a study investigating the possible effects of different

irradiation procedures, it was found that radiation dose had a

negative effect on the osseointegration process in two ways.

First, in the high dose region above 120 Gy a high proportion

of implants were lost. Second, in the low dose region,

proportionally more implants were lost, whereas

osseointegration in the medium dose region showed minor

effects.

The high frequency of implant losses in the high radiation

dose region could be related to the irradiation effect per se,

whereas the high losses in the low radiation dose region are

more difficult to explain. www.indiandentalacademy.com

The irradiation process induces a progressive endarteritis that

becomes more evident with elapsing time. The very low dose

irradiation protocols (15-25 Gy) that produced higher implant

failures with time are not used in modern radiotherapy. The

extremely high dose radiotherapy is only attained in patients

with recurrent cancer or new tumor development;


The patients rehabilitated earliest after the radiotherapy

course show the highest implant survivals. This has

stimulated to perform implant related surgery as soon as

possible after tumor removal, and today actually most of the

implants are inserted at the time of tumor removal. This has

the advantages that the patient is rehabilitated early and

implant survival is higher. The negative aspects could be

that tumor recurrences might appear during the following

years, necessitating more radiotherapy and the removal of

the implants at a time of extended tumor removal and other

side effect could be the risk of inducing osteoradionecrosis

or other complications due to too early surgery in an

irradiation field. www.indiandentalacademy.com

Radiotherapy with a metal object in the radiation field induces

scattering effects from a radiation beam "bouncing" on the

metal framework. These scatter effects depend on the energy

and source of irradiation, the distance from the metal to the

tissue, and the atomic number of the metal.

Possible effects of the increased radiation dose in the delicate

interface zone between an implant and the bone or between

the abutment and the skin are not completely understood. In

certain patients it could be the cause of implant loss and skin

reactions, but in other patients it also could stimulate cell

turnover. www.indiandentalacademy.com

HYPERBARIC OXYGEN THERAPY

The protocol: 20 sessions at 2.5 atmospheric pressure preoperatively and 10 postoperative sessions.

The biologic effects that can be measured in an irradiated tissue that has undergone HBO treatment are improved vascularisation, improved bone turnover, and improved metal to bone contact. The target cells influenced by oxygen seem to be undifferentiated mesenchymal cells in the callus or granulation tissue that has the ability to differentiate into osteoblasts.

In a healing soft tissue wound, the granulation tissue exposed to hyperoxia will form angioblasts, leading to improved angiogenesis. Both of these factors are important for the osseointegration process, especially in compromised tissue.


COMPLICATIONS AROUND PERCUTANEUS IMPLANTS

A Percutaneus implant is a foreign body penetrating the skin

through a defect created during surgery. Because the skin

barrier is broken, exogenous agents more easily penetrate

into the tissue. The following may be important for the

function of epithelial penetrations:

• A tight contact between the epithelium and the penetrating

implant;.

No relative Motion in the interface area.

• The surface architecture of the implant material; and

• The status of the connective tissue.www.indiandentalacademy.com

Marsupialization:

The epithelium has a tendency to grow down along the

skin penetrating implant to a varying extent, and such an

epithelial down growth is a common finding. A total

epithelial down growth is one of the failure modes forming

a sinus tract along the implant and is due to the free edge

effect of the epithelial cells.


Avulsion:

The skin around a Percutaneus implant is subjected to

forces that lead to mechanical disruption of the interface,

with microhematomas and subsequent microfoci of acute

inflammation. This is considered to be a mechanically

induced failure mode.


Permigration:

The health and the maturity of the connective tissue are of

great importance for the epidermis. Immature connective

tissue cannot nourish the epidermis, which will permigrate

deeper down around the skin penetrating implant. This

failure mode is related to implants with a porous surface.

The soft connective tissue and the epidermis migrate into

the implant and continue throughout the entire porous

extent of the implant.


Infection:

When an infection is established around an implant, it

may have serious effects and usually leads to failure of

the implant. The major pathogen in infections around

metal implants is considered to be Staphylococcus

aureus. Coagulase negative staphylococci, in particular

Staphylococcus epidermidis, seem to be the most

common agent in infections related to implants of

polymers.


Delayed Hypersensitivity:

Another important reaction, especially for metal implants,

is delayed hypersensitivity or contact allergy. This is well

known for non skin penetrating implants of nickel,

chromium, and cobalt. Reports indicating hypersensitivity

to titanium are rare.


Implant Failure:

Failure of an implant is the most severe complication.

Depending on the number of implants remaining and the

design of the retentive mechanism, the prosthesis may need

to be modified. If two or more implants remain and the

retention design is not compromised, the prosthesis can be

stable and retentive.

If a bar clip system is used and implant loss means that

there is no inadequate support for the bar, then individual

magnets or ball or stud attachments need to be used.


FALLOW UP AND MANAGEMENT

Once a patient is treated, the osseointegration team has

to undertake a lifelong responsibility for the maintenance

of the bone anchored prosthesis. Much time and effort are

spent in the fabrication of a bone anchored prosthesis that

will provide a lifelike facial restoration.

For all of its advantages, the bone anchored facial

prosthesis does require more care on the patient's part

and closer professional follow up than one retained with

adhesive.www.indiandentalacademy.com

Follow up management actually begins once the abutments

have been placed. After the initial healing period and once a

surgical dressing is no longer needed, the patient should be

instructed to clean this area on a daily basis. The purpose is

to remove cellular material on the skin or abutment, which

can come from the interface of the epithelium and abutment.

This is performed with a soft end nylon bristle toothbrush, an

interproximal dental brush, or a cotton swab. To facilitate

cleaning, the area should be moistened first with an even

mixture of hydrogen peroxide and water to soften any dried

debris. www.indiandentalacademy.com

End tuft tooth brush Interproximal tooth brush Cotton swabwww.indiandentalacademy.com

The prosthodontist should monitor the stability of the

abutment and the health of the soft tissue during the regularly

scheduled visits for prosthesis fabrication. abutment tightness

can be checked using a abutment clamp. If the abutment

loosens, complete seating should be verified before

retightening. This is done with an abutment holder.

On the day that the prosthesis is given to the patient,

adequate time should be allotted for instructions on placing

and removing the prosthesis as well as proper maintenance

of the prosthesis, abutments, and surrounding skin areas.


Abutment clamp provides

counter torque for checking

abutment tightness.

Abutment holder ensures

complete seating of loose

abutment.www.indiandentalacademy.com

When placing the prosthesis, the patient should be

certain that the retentive elements are engaged

completely to ensure that the prosthesis is seated fully.

The retention elements (clips, magnets, or balls or studs)

within the acrylic resin plate ensure security of the

prosthesis.


The patient should be careful when removing the prosthesis

so that the thin margins do not tear and the silicone rubber

does not separate from the resin plate.

For an auricular or nasal prosthesis, proper removal by

grasping a thick portion of the prosthesis and slowly

disengaging the retentive elements should be demonstrated

and performed several times by the patient.

For an orbital prosthesis, an outer margin should be lifted

carefully until a thicker portion can be grasped to lift the

prosthesis.www.indiandentalacademy.com

Review of literature

George E. Anastassov and Eric S. Asher (JPD 2000;84:215-

16) stated that the soft tissues overlying the percutaneous

implants are usually thick and mobile, which requires longer

transcutaneous attachments. However these attachments

may compromise the stability of the implants and lead to the

implant loss. To avoid these complications skin and

subcutaneous debulking and split thickness skin grafts

should be performed. www.indiandentalacademy.com

Stephen M. Parel. P I Branemark et al states that the

application of osseointegrated fixtures to the cranial

skeleton for facial prostheses retention marks

revolutionary step in search for the perfect soft tissue

replacement. They along present Eastover technology to

be used to its greatest potential by protecting surface

color and allowing long term retention of fine but weak

peripheral margins.


Albertson et al conducted 951 clinical observations of

skin response around 389 abutments for BAHA(243

observations) and auricular prostheses (708

observations). Of these observations 92.1% showed no

skin response and 3.9% showed slight redness,

potentially serious skin responses occurred in only 2.8%

of observations.


Rubinstein reported that orbital prostheses were

fabricated with wider variety of attachments than any

other type bone anchored facial prostheses: bar clips,

magnets, ball studs, or a combination of these types.


In review of treatment centers Rubenstein found that

magnetic retention represented nearly half of the

attachments in united states and Canada compared with

only one third of those used in Sweden. Clips were used

only 20% of the time in united states, 33% of the time in

Canada and nearly 50% of the time in Sweden.

Approximately 20% of the orbital prostheses in the

united states and Sweden used a combination of

magnets and clips.


References

• Osseointegration in Maxillofacial reconstruction :

Per-ingvar branemark, Dan E. Tolman.

• Advanced Osseointegration Surgery – application in

maxillofacial region:

Philip Worthington, Per-ingvar Branemark.

• Maxillofacial rehabilitation:

Keith F. Thomas.


1. Craniofacial osseointegration .The canadian experience

– Int J Oral maxillofac Implants 1993;8:197-204.

2. Microflora associated with percutaneous craniofacial

implants used for the retention of facial prosthesis

-Int J Oral maxillofac Implants 1995;10:578-82

3. Console abutment loading in Craniofacial osseointegration

-Int J Oral maxillofac Implants 1998;13:245-52.

4. Craniofacial osseointegrated implant induced strain

distribution -Int J Oral maxillofac Implants 1997;12;200-10


5. Biomechanical considerations for implant supported orbital

prosthesis –J facial somato prosthet 1995;1:43-53

6. Rehabilitation of irradiated cancer patients with tissue

integrated prosthesis: Adjunctive use of hyperbaric oxygen

to improve osseointegration- J facial somato prosthet

1996;2:1-11.

7. Use of surgical positioner for bone anchored facial

prosthesis –Int .J oralmaxillofac implants 1997;12:376-79.


8. Use of frontal process of the maxillary bone for implant

placement to retain a nasal prosthesis .A clinical report.

Int J oral maxillofac implants 2004;19:901-05.

9. Osseointegration in maxillofacial prosthesis part II

Extraoral applications Prosthet dent 1986;55:600-06.

10. Bone anchored maxillofacial prosthesis.

Quintessence 1989;235

11. Surgical considerations for endoosseous implants in the

craniofacial region report.

Int J oral maxillofac surg 1993;22:272-77 www.indiandentalacademy.com

12. Diminishing dependence on adhesives for retention of

facial prosthesis. J Prosthet dent 1980;43:552

13. The use of magnets in maxillofacial prosthesis.

J Prosthet dent 1971;25:334

14. Osseointegrated implants for replacement of absent or

defective ear. Clin plast surg.1990;17:355-366.

15. Bone anchored craniofacial prosthesis study.

Int J oral maxillofac implants 1996;11:159-68.


THANQ


www.indiandentalacademy.comLeader in continuing dental education

dental implant supported maxillo facial prosthesis. /certified fixed orthodontic courses by...

Education

maxillofacial structures

facial prosthesis retention

percutaneous implants

ossiointegrated implants

oral prosthesis

auricular prosthesis

bone anchored implants

principles of dental