Maxillofacial Prosthetics - PowerPoint Presentation

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Maxillofacial Prosthetics

,

دم

د. نغم بهجة

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Maxillofacial Prosthetics

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“the art and science of

anatomic,

functional

,

or

cosmetic

reconstruction

by means of

nonliving substitutes of those regions in the maxilla, mandible, and face that are missing or defective because of surgical intervention, trauma, pathology, developmental or congenital malformations.”

Maxillofacial

prosthodontic

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is an artificial device

used to replace missing

facial or oral structures.

Maxillofacial prosthesis

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Reconstruct of missing parts in maxilla, mandible and face with prosthesis.

To achieve:

1- Preservation of residual structures.2- Reconstruction of function.

3-

Improvement in esthetic.

The Aim of Maxillofacial Prosthetic:

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Artificial facial parts found on Egyptian mummies. Ancient Chinese known to have made facial restorations.

ancient-artificial-eye

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1

-Congental2

-Traumatic3-Pathological with radical surgery

1-

Intra Oral (Maxilla and Mandible).

2-

Extra Oral (eye, nose, ear).

Causes of Facial and oral Tissues loss

These factors result to 2 types of defects either:

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-

Congenital

.Cleft lip..Cleft palate.-

Acquired

.Total maxillectomy

.Partial maxillectomy

Types of Maxillary Defects

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Cleft lip occurs due to improper fusion between the fronto-nasal and maxillary process .

Cleft lip

&

palate

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it is may be unilateral, bilateral and in Mohr's syndrome ,midline cleft lip is seen.

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Cleft lip and the

combination of cleft

lip and cleft palate occur

twice

as often

in

males

as in females,

while cleft palate

alone occurs more

often in females.

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Clefts occur most

often in children of

Asian, Latino or

Native American

These deformities

are known to occur

less frequently

in African, Americans

.

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As a result of the abnormalities in the upper arch of the mouth,

teeth may

not erupt properly or may be missing completely. In such cases, artificial teeth and orthodontics (braces

) are usually required. Routine oral hygiene,

tooth

brushing

and

flossing

are still required to maintain healthy teeth and gums and prevent gum disease (periodontitis) and tooth decay.

Dental Problems

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Treatments for Cleft Lip

and Cleft Palate

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Children with cleft lip and/or cleft palate are treated over the course of

18 or more years

. Treatment can involve a team of professionals beginning shortly after birth and continuing throughout adolescence.

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The treatment team includes

medical, dental and

other

healthcare specialists

who work together to address

the many different and

complicated needs specific

to the individual.

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Most acquired defect occur due to

surgical resection of tumors

or trauma .Acquired Maxillary Defect

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These are usually classified based on their extent

.

1.Total maxillectomy : both the maxillae are resected.

2

.Partial Maxillectomy

:

resection of one or a part of the maxilla or palate.

Types of Acquired

Maxillary defect

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Obturator

•

Restores oro-nasal

partition

•

At times can be

added to prior

dentures

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The

three types of prostheses are constructed for both edentulous and dentulous patients

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Surgical Obturator

Interim Obturator Definitive Obturator

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Materials Used in Maxillofacial

Reconstruction

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POLY(METHYL METHACRYLATE)

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it is the

most commonly used material for facial restoration but poor tear strength and life- less appearance have limited them from universal acceptance .

Silicones

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1-

HTV-Silicone : it requires

heat for vulcanization . It is highly viscous , white , opaque and has better physical properties .

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2-

RTV-Silicones : they are

room temperature polymerizing silicones . It is esear to process and allow intrinsic colouration .

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Metal :

metal implants are used to obtain bone anchorage for

a prosthesis . Implant metals used are Titanium alloys , base metal alloys are used for denture base fabrication

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Realistic coloration of extraoral prostheses is an

important feature

for patient

satisfaction

and

acceptability

.

Coloration

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Intrinsic coloration involves incorporating precise proportions of pigments by mixing (RTV) or milling (HTV) into the base elastomer before to packing in the mold and curing in a dry heat oven.

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In general, the extrinsic coloration uses a medical-grade adhesive combined with xylene and earth pigments, which are applied to the external surface of the prosthesis. The prosthesis is then postcured in a dry heat oven to evaporate the xylene.

Extrinsic coloration

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Fabrication Of

the Prostheses

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The method for fabricating a prosthesis is similar for most materials.

An impression is made of the affected area with alginate. A master cast is

poured, duplicating the defect on the patient.

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Step 1

- Seat patient comfortably, cover hair and coat eyebrows with cold cream to prevent entrapment of alignate.

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Step 2

- Alignate mixed. Patient learns hand signals protocol to communicate. Pouring of alignate on forehead to allow for flow down the face.

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Step 3

- Alignate poured taking care not to entrap air in anatomical undercut areas. Incase the patient is traumatized (children or burns victims with painful skins) by process anaesthesia is needed.

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Step 4

- Guaze stockinet is removed from patients hair.Impression is removed from patients face (allowing time for patients eyes to adjust to light in the room

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Step 5

- Impression disinfected. Air passage blocked in impression. Exposed plaster coated with petroleum jelly to prevent bonding with stone cast. Stone allowed to gently flow over the surface of the alignate.

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Step 6

- Stone cast may need trimming on model trimmer.

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Fabrication of a Maxillofacial Prosthesis Using a Computer-Aided Design and Manufacturing System

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Seat patient comfortably, Adjust receiver on patients head. Scanner imaging, Polhemus FastScan digital scanner

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Maxillofacial prostheses are usually fabricated on the basis of impressions made with dental-impression material.

The extent to which the prosthesis reproduces normal facial morphology depends on the clinical judgment of the individual fabricating the prosthesis.

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This new technique describes a

computer-aided design and manufacturing system

(CAD/CAM) for the fabrication of maxillofacial prostheses. This system will provide a more consistently accurate reproduction of facial morphology

.

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Facial measurements were taken using a non-contact three-dimensional laser morphological

measurement system.

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The measurements were sent to a computer numerical controlled

(

CNC) milling machine to generate

a cast of the patient's face for the

fabrication of prosthesis

.

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Facial contours were measured using a laser. This method minimizes

patient discomfort and avoids soft tissue

distortion by impression material. Moreover, the digital data obtained is easy to store and transmit, and

mirror-images can be readily generated by computer processing

.

Results

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This method offers an objective, quantified approach for fabricating maxillofacial prostheses

.

Conclusion

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Retention of

maxillofacial prostheses

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Retention of facial prostheses has been primarily by way of

medical adhesives. An ideal adhesive should be one that provides firm functional retention under flexure or extension during speech, facial expressions, and moisture or perspiration contact.

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Adhesives for extraoral maxillofacial prostheses require a substantial amount of supportive ingredients properly formulated to provide lasting viscoelasticity with a high degree of retention. Numerous brand names of adhesives have been introduced over the years in maxillofacial prosthetics.

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Other methods of retention include engagement of anatomic tissue undercuts, thereby minimizing dependence on adhesives.

The potential for tissue irritation exists with this technique, and therefore it must be used prudently.

Areas that have been irradiated contraindicate the use of this technique.

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Finally

, with the increaed use of

osseointegrated implants, dependence on adhesive and anatomic methods of retention has diminished.

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Magnets

can be used to minimize force transfer to the implant and supporting bone. The resultant decrease in dependence on chemical (adhesives) and anatomic (tissue undercuts) sources of retention is beneficial to both the patient and the prosthetic rehabilitation.

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Anterior view of the

anatomical defect

following maxillectomy

Oblique view of the anatomical

defect showing communication

with nasal cavity

.

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Location of magnet placement between

the facial prosthesis extension and the

palatal obturator denture.

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Positioning of the retention

magnets

Highligher paste on thesuperior aspect of the

palatal obturator prosthesis

.

B

.

Transfer of the paste to

the facial prosthesis

extension to demarcate the

location for the secondmagnet.

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Facial prosthesis in place after

one year of use.

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SURVEILLANCE

One of the biggest advantages in using removable prostheses in the head and neck cancer patient is the ability to provide tumor surveillance. As the overall survival of head and neck cancer approaches 52%, there is a window of time to monitor for local recurrent lesions. With use of prostheses, it becomes possible to directly visualize recurrent areas that may be apparent in the perioperative period to the third year of

follow-up. If these areas are reconstructed with tissue, the ability to provide surveillance is markedly reduced.

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Grateful

for

Patient Lestining