Maxillofacial Prosthetics

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WHAT HAS MAXILLOFACIAL PROSTHETICS GOT TO DO WITH DENTISTRY?

Maxillofacial prosthodontics is the branch of dentistry that provides prostheses to treat or restore tissues of the stomatognathic system and associated facial structures, that have been affected by disease, injury, surgery, or congenital defect, providing all possible function and esthetics.

It is the art and science of functional, or cosmetic reconstruction by means of non-living substitutes for those regions in the maxilla, mandible, and
face that are missing or defective. The defects can be congenital or acquired (surgical or traumatic).

 

Objectives of maxillofacial prosthetics

  • Restoration of esthetics or cosmetic appearance of the patient
  • Restoration of function
  • Protection of tissues
  • Therapeutic or healing effect
  • Psychological therapy

 

Requirements of a maxillofacial prosthesis

  • The appliance must be easily and swiftly placed and held in position, both
    comfortably and securely
  • Must be durable and easily cleaned
  • Retain color quality
  • Material should be non irritating to the surrounding tissues, strong enough
    around the periphery to endure.
  • Physically resistant to sunlight, heat or cold, subject to little change in volume
    during extremes of temperatures during processing, and easily washable.

 

Types of maxillofacial defects

A. Congenital: e.g. Cleft palate , Cleft lip, Facial cleft , Missing ear

B. Acquired: e.g. Accidental injuries , Surgical resection, Pathology lesions

C. Developmental: e.g. Prognathism and Retrognathism

 


 

WHAT IS THE CLASSIFICATION OF MAXILLOFACIAL PROSTHESIS?

1. Intraoral prosthesis

The intraoral prosthetic appliances are usually combined to the conventional
prosthesis (RPD, CD, FPD) that may be required for the patient.

Examples :
a. Obturators: to close a congenital or acquired defect

b. Stents: to control bleeding and promote healing, stabilize grafts, assist radiation therapy

c. Splinting appliance: to fix fractured segments until healing

d. Resection appliance: restores mandibular defects to guide mandibular closure

e. Speech aid prosthesis : Speech bulbs, Palatal lifts, Metal obturator

 

2. Extra-oral prosthesis:

Reconstructing missing parts of the facial structure

  • Auricular prosthesis
  • Ocular prosthesis
  • Orbital prosthesis
  • Nasal prosthesis
  • Composite prosthesis
  • Lip and cheek prosthesis

3. Combination of intra-oral and extra-oral prosthesis
4. Cranial prosthesis: Cranial onlays and inlays in cranioplasty

 


Members of a maxillofacial team may consist of:

  1. Plastic surgeon
  2. Speech therapist
  3. Radiotherapist
  4. Dental specialist: Prosthodontist, Orthodontist, Oral surgeon, Dental Technician, Pathologist, Periodontist, Pedodontist
  5. E.N.T. (Ear, Nose & Throat) Specialist
  6. Psychiatrist

 


 

Maxillary defects

Patients with maxillary defects will have difficulties in mastication, speech and  deglutition. The aim of a maxillofacial prosthesis should be to restore the normal physiological function in these patients. Maxillary defects can be broadly classified as follows:
A) Congenital
Cleft lip
• Cleft palate
B) Acquired
Total maxillectomy
• Partial maxillectomy

 

Congenital Maxillary Defects

Cleft lip and cleft palate

Cleft lip occurs due to improper fusion between the fronto-nasal and maxillary process. If this occurs on one side it leads to a unilateral cleft. If it occurs on both sides, it leads to a bilateral cleft.
Veau’s Classification of Cleft Palate:
Veau (1922) classified cleft palate into four types mainly,

Class I: Cleft involving the soft palate.

Class II: Cleft involving the soft palate and the hard palate.

Class III: Cleft involving the soft palate up to the alveolus on one side, usually involving the lip.

Class IV: Cleft involving the soft palate up to the alveolus on both sides.

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Prosthetic considerations:
For young patients, a permanent prosthesis should not be provided, instead, a well fitting interim prosthesis should be provided. This interim prosthesis is replaced with a permanent one at around 25 years of age. A removable interim partial denture is preferred over a fixed prosthesis because it is more aesthetic in reproducing gingival contour, and it also helps to cover an unaesthetic residual alveolar cleft. The most important concern in the restoration of these cases is establishment of aesthetics.
Posterior cleft palate cases are usually treated using speech bulbs and palatal lift prosthesis.

 

Speech bulbs and palatal lifts

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Speech bulbs and palatal lifts aid in velopharyngeal closure, which helps in raising the palate and separating the nasal cavity from the oral cavity.

A speech bulb contains a pharyngeal section, which goes behind the soft palate region, in case of a deficient soft palate.

A palatal lift prosthesis consists of an oral component that stabilizes and secures the prosthesis and an oropharyngeal extension that superiorly and posteriorly displaces the impaired soft palate. These appliances help the patient is both speech and swallowing.

 

Acquired Maxillary Defects

Acquired maxillary defects are usually classified based on their extent. If both the maxillae are resected, the defect is considered as total maxillectomy. Resection of one or a part of the maxilla or palate is considered as Partial Maxillectomy.

Aramany proposed a classification of partial maxillary defects based on their
extent.

Class I: It is a unilateral defect involving one half of the arch, extending to the
midline. It is the most common maxillary defect seen.

Class II: It is a unilateral defect involving one side of the arch posterior to the
canine (teeth posterior to the canine are absent)

Class III: It is a defect involving the central portion of the hard palate and may
also involve the soft palate (all the teeth are present) .

Class IV: It is a bilateral defect that crosses the midline and involves both sides of
the maxilla (Few posterior teeth remaining on one side)

Class V: It is a bilateral posterior defect (teeth anterior to the second premolar
are present)

Class VI: It is a bilateral anterior defect (teeth anterior to the second premolar are
absent).

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Obturators

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The name obturator is derived from the Latin verb “obturare”, which means close or to shut off.

According to the glossary of prosthodontics , obturator is defined as prosthesis used to close a congenital or an acquired tissue opening, primarily of hard palate and or contiguous alveolar structures.

An Obturator is usually fabricated as an extension of a complete denture or a
removable partial denture.

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Functions of obturator

  1. Helps in separating the oral cavity from the nasal and sinus cavities, thus helping
    in speech, mastication and deglutition.
  2. Can be used to keep the wound area clean and to enhance healing
  3. To reshape or reconstruct the palatal contour/or soft palate
  4. Can be used to correct lip and cheek position
  5. Reduces the flow of exudates in the mouth
  6. Can be used as a stent to hold surgical packs, post surgery.
  7. Psychological benefits to the patient.
  8. It also contributes to the retention and stability of the denture, by extending far
    enough into the defect and engaging some small undercuts.

 

Types of Obturators

A patient who undergoes maxillary resection is rehabilitated in 3 phases. Based on this, obturators are of 3 types :

1. Immediate Surgical Obturator
2. Interim Obturator
3. Definitive obturator

 

Surgical obturator
• Constructed from a pre operative impression cast and placed immediately after surgery.
• Enables the patient to speak, take nutrition and swallow effectively, after surgery.
• Restores the continuity of the palate
• Supports the surgical packing placed in the resection cavity.
• Usually placed until 5 to 10 days after surgery.
• They are either sutured or screwed into the edentulous arch.

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Interim Obturator

After 5 to 10 days ,the prosthesis is removed , relined in the mouth and reprocessed with new acrylic resin and delivered on the same day.

• This serves for 4 to 6 months of the healing period.
• Periodic modifications are done as the wound heals.
• Multiple wrought wire clasps or denture adhesives can be used for retention.
• Mastication on the surgical side are avoided .
• Prosthetic teeth may be added to enhance esthetics.

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Definitive Obturator

• It is fabricated when tissue healing and contraction are complete, usually 4 to 6 months postoperatively.
• Primary impressions using alginate and secondary impressions using a special tray using silicone are made.
• The undercuts within the defect and the lateral scar band on the side of the defect,  should be recorded well, as they contribute to the retention of the prosthesis.
• The obturator is made hollow to decrease the weight of the prosthesis.
• Dental implants and overdentures held with precision attachments can significantly improve the retention.

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Mandibular Defects

Congenital Defects of the Mandible

Congenital mandibular defects that require a maxillofacial prosthesis are uncommon. Common congenital defects of the mandible include micrognathia, mandibulofacial dysostosis, ankylosis of the temporomandibular joint etc.

Acquired Defects of the Mandible

As mentioned for the maxilla, neoplastic resection is one of the most common causes for an acquired mandibular defect. The common neoplasia which advocate the need for resection are squamous cell carcinoma of the tongue, oropharynx and floor of the mouth.

 

Types of Acquired Mandibular Defects
Based on the amount of resection or extent of bone loss, mandibular defects can be classified as follows:

1. Marginal or Continuity defect:

• Here, only the superior margin of the mandible is resected and the lower border is
left intact. So the continuity of the mandible is maintained.

• These defects do not show any deviation and are easy to restore. Reconstructed
with a split-thickness skin graft, which can behave like gingiva., over which
dentures can be made.

 

2. Discontinuity defect:

• Here, a significant segment of the mandible is resected and a condyle to condyle continuity is disrupted. Midline deviation of the mandible is commonly seen.

• These defects can be successfully reconstructed using microvascular free flaps, which makes fabrication of dentures easier.

• Because of the deviation present, a flat occlusal platform is made palatal to the existing maxillary teeth on the non resected side. This helps in guiding the mandible into the desired normal occlusion. It is known as the maxillary ramp.

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WHAT ARE EXTRAORAL DEFECTS?

•Defects occur due to trauma, neoplasm or congenital malformation.

•Aesthetics is the major principle behind the placement of these prosthetic appliances. Hence, most of these prostheses are non-functional.

  • Auricular prosthesis
  • Ocular prosthesis
  • Orbital prosthesis
  • Nasal prosthesis
  • Composite prosthesis
  • Lip and cheek prosthesis

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Materials used for maxillofacial prosthesis

A) Impression phase: Alginate, Silicone, Plaster of Paris

B) Modelling phase: Modelling Clay, Plaster, Plastolene, Waxes

C) Fabrication Phase:

  • Extraoral materials – Acrylic resin, Vinyl chloride polymers, Polyurethane, Silicone
  • Intraoral materials — Silicone, Poly (methyl methacrylate)

 

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Summary:

Maxillofacial prosthodontics deals with the restoration of the appearance and function of patients with defects in maxilla or mandible, due to congenital, traumatic or surgical reasons.

Defects of the maxilla are more common and more complicated because of the associated anatomy and function.

Complete or partial dentures can be modified and designed to restore the intra oral defects , which helps the patients to function optimally, giving them psychological benefits.

Extra oral defects are more concerned with the appearance and a variety of biocompatible materials can be used for the same.

Dentists, together with the multidisciplinary team, can contribute significantly in the restoration of esthetics and function of patients with maxillofacial defects.

 

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References
Clinical maxillofacial prosthetics – Thomas D. Taylor
Essentials of complete denture prosthodontics. Sheldon Winkler. Second edition
Prosthodontic treatment for edentulous patients. Zarb-Bolender. Thirteenth edition
Maxillofacial rehabilitation – John Beumer
Maxillofacial prosthetics – Chalian

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