⁠Maxillofacial Prothesis

Maxillofacial prosthetics is a specialized area of dentistry that focuses on the rehabilitation of patients with defects or disabilities¹ in the head and neck region. This often involves the fabrication of artificial replacements for missing facial structures, including the eyes, nose, and ears. These prostheses aim to restore aesthetics, function (such as speech and swallowing), and improve the patient’s quality of life.

Fabrication Process:

The fabrication of an artificial eye, nose, or ear (and other maxillofacial prostheses) typically involves a detailed and multi-step process:

1. Consultation and Assessment:

The maxillofacial prosthetist will conduct a thorough examination of the defect site and surrounding tissues.
They will discuss the patient’s needs and expectations regarding the prosthesis.
Impressions and measurements of the defect area and the corresponding healthy side (if available) are taken.
Photographs and sometimes 3D scans may be used to capture the patient’s facial features.

2. Impression and Cast Fabrication:

A precise impression of the defect area is made using specialized impression materials. Accuracy is crucial for a well-fitting prosthesis.
From this impression, a working cast (a positive replica) of the patient’s anatomy is created in the dental laboratory.

3. Wax Sculpting:

A wax pattern of the artificial eye, nose, or ear is meticulously sculpted on the working cast. The prosthetist uses the measurements, photographs, and the contralateral side as a guide to recreate the missing anatomy as accurately as possible.
For an artificial eye, a stock eye (an artificial eye blank) of the appropriate size and color is often used as a base and customized with wax

4. Try-in and Refinement:

The wax pattern is tried in on the patient to assess the fit, shape, size, and overall appearance.
Adjustments are made to the wax sculpting until the desired aesthetic and functional outcome is achieved.

5. Mold Fabrication:

Once the wax pattern is finalized, a mold is created around it using dental plaster or stone. This mold will be used to fabricate the final prosthesis.
The wax is then removed from the mold, leaving a space in the shape of the prosthesis.

6. Prosthesis Fabrication (Material Processing):

The space in the mold is filled with a biocompatible prosthetic material, most commonly silicone elastomers. Other materials like acrylic resins or polyurethanes may be used depending on the specific requirements of the prosthesis.
Silicone: Often preferred for extraoral prostheses due to its flexibility, lifelike texture, ease of coloration, and biocompatibility. Different types of silicones (heat-vulcanizing and room-temperature vulcanizing) are available with varying properties.
Acrylic Resins: May be used for ocular prostheses due to their durability and ease of modification.

7. Curing and Deflasking:

The mold containing the prosthetic material is processed according to the manufacturer’s instructions, which may involve heating (for heat-vulcanizing silicones or acrylics) or allowing it to set at room temperature.
Once cured, the mold is carefully opened, and the raw prosthesis is removed (deflasked).

8. Finishing and Characterization:

The prosthesis is trimmed and finished to remove any excess material and refine the edges.
Intrinsic and extrinsic coloring techniques are used to match the patient’s skin tone and the natural appearance of the missing feature. This is a crucial step for achieving a realistic look. For artificial eyes, the iris and sclera are meticulously painted.
Surface details, such as pores and wrinkles for skin or subtle textures for the eye, nose, or ear, may be added for a more lifelike appearance.

9. Delivery and Fitting:

The final prosthesis is delivered to the patient and carefully fitted.
Instructions on how to insert, remove, clean, and care for the prosthesis are provided.
Retention mechanisms, such as adhesives, osseointegrated implants, or anatomical undercuts, are utilized to secure the prosthesis.

10. Follow-up and Maintenance:

Regular follow-up appointments are necessary to monitor the fit and condition of the prosthesis and to make any necessary adjustments.
Prostheses may need to be replaced over time due to wear and tear or changes in the patient’s anatomy.

Materials Used:

Common materials used in the fabrication of artificial eyes, noses, and ears include:

Silicone Elastomers: These are the most widely used materials for facial prostheses due to their flexibility, biocompatibility, and ability to be colored and textured realistically. Different types exist, including heat-vulcanizing (HTV) and room-temperature vulcanizing (RTV) silicones.

Acrylic Resins (Polymethyl Methacrylate – PMMA): Primarily used for ocular prostheses due to their durability, ease of manipulation, and compatibility with coloring techniques. They can also be used as a rigid base for silicone facial prostheses.

Polyurethane Elastomers: Offer good strength and flexibility but can be more challenging to color.

Vinyl Polymers/Plastisols: Can be flexible and allow for intrinsic and extrinsic staining.

Types of Maxillofacial Prostheses:

Maxillofacial prostheses are broadly classified into extraoral and intraoral prostheses. Artificial eyes, noses, and ears fall under the category of extraoral prostheses:

Ocular Prosthesis (Artificial Eye): Replaces a missing eye after enucleation, evisceration, or exenteration. It typically consists of a scleral shell that fits over the orbital tissues and a painted iris and pupil that match the patient’s remaining eye.

Auricular Prosthesis (Artificial Ear): Replaces a missing ear or part of the ear, often due to congenital deformities, trauma, or cancer surgery. Similar to nasal prostheses, retention options include adhesives and osseointegrated implants.

Midfacial Prosthesis: Replaces a significant portion of the midface involving multiple structures.

Somatic Prosthesis: Replaces other external body parts like fingers or hands.