Zinc phosphate • One of the oldest available luting agents
• Gold standard when compared with newer cements
• Compressive strength: 104 MPa
• Bonds with mechanical interlocking and has low water solubility
• At the time of cementation, pH of the cement is 2.0 and it increases rapidly to 5.5 after
• Pulpal irritation is likely because of the acidic pH
• Cavity varnish is used to reduce the irritation, but its application reduces retention
• First cement developed which bonds to tooth chemically
• It has higher tensile strength but lower compressive strength than zinc phosphate
• It shows pseudoplastic behaviour, i.e. increased thinning at increased shear rate
• It also has low pH (4.8), but is less irritant to the pulp because large-sized polyacrylic
acid molecules penetrate less into the dentinal tubules
• It can bond with stainless steel crowns but not with gold
• This has the least pulpal irritation amongst all available cements
• It has a low compressive strength range between 3 and 55 MPa
• Smaller particle size cement is more stronger
• Usually used as temporary cement
• Presence of eugenol interferes with the polymerization of the composites
• Modified cement can be used as a long-term provisional luting agent.
• o-Ethoxybenzoic acid (EBA) cements are reinforced with alumina oxide
• The compressive strength of improved cement was acceptable but was much low in
• This is the most commonly used luting agent
• It contains fluoride and has anticariogenic property
• Its compressive strength is 150 MPa and the tensile strength is 6.6 MPa
• Bonds chemically with both enamel and dentine
• Less soluble than zinc phosphate and releases fluorides at a higher rate than silicate
• Vulnerable to postcementation hypersensitivity
• Layer of calcium hydroxide is recommended when cement is applied close to the pulp
• Cement at the crown margin should be protected by applying varnish or petrolatum
• It is more translucent than zinc phosphate cement and chances of metal see through
Resin cements • These are flowable composites of low viscosity
• These have higher strength than conventional cements
• These have very low solubility
• These cements can be chemically activated or light-activated or dual-cured
• Application of dentine bonding agent is critical for its use, as it reduces the pulpal
• The cement bonds by micromechanical means (Fig. 30-1)
• The cement is useful when preparation is confined to enamel and has accessible finish
• These are the luting agents of choice to bond all ceramic inlays, crowns and bridges
• These are available in different shades and give good aesthetic results
• These are resin-modified polyalkenoate cements
• These have good strength and low in solubility and also contain fluoride
• These have anticariogenic property
Failures in fixed partial denture (FPD)
Classification of failures in FPD by Bernard G.
(ii) Mechanical failure of crown or bridge components: This is
• Occlusal wear and perforation
(iii) Changes in abutment tooth
• Fracture of the prepared natural crown or root
(iv) Design failures: This is subclassified as follows:
(v) Inadequate clinical or laboratory technique: This is subclassified as
Factors responsible for FPD failures
The factors can be of three types:
• Gingival recession and periodontal breakdown
• Failure to identify patient expectation
• Failure to communicate proper shade to laboratory
• Thick metal margin at incisal and cervical regions
• Failure to produce translucency
• Over- or undercontoured crown
• Exposed metal margin in connector, incisal or cervical region.
• In chronic xerostomic patient, cervical caries and periodontitis are
prime reasons for FPD failure.
• Beilby layer is a microscopic surface layer produced during
• Metamerism is a phenomenon of an object appearing of different
colours when viewed under different light source.
• The use of dissimilar metallic restorations in the same mouth may
result in the creation and flow of galvanic currents.
31. Introduction and materials
32. Maxillofacial defects and prosthesis
Effect of Radiation on the Oral Cavity, 423
Evolution of Maxillofacial Prosthesis, 424
Materials Used in Prosthetic Restoration of the Facial Defects, 425
Desirable Properties of Ideal Materials, 426
Definitive Materials Used in Maxillofacial
Stents and Splints Used in Maxillofacial Prosthesis, 431
Maxillofacial prosthodontics is a branch of prosthodontics involved in
treating congenital, developed and acquired maxillofacial defects with
variety of techniques and materials. This chapter outlines effects of
radiation on oral tissues and various materials used in maxillofacial
Maxillofacial prosthodontics is defined as ‘the branch of prosthodontics
concerned with the restoration and/or replacement of the stomatognathic and
craniofacial structures with prosthesis that may or may not be removed on a
regular or elective basis’. (GPT 8th Ed)
Maxillofacial prosthesis is defined as ‘any prosthesis used to replace
part or all of any stomatognathic and/or craniofacial structure’. (GPT 8th
The important objectives of maxillofacial prosthodontics are:
• Therapeutics and healing effect
• It is an alternative to plastic surgery but not a substitute to plastic
• Large defects which are not restored with plastic surgery are
rehabilitated by means of appliances or devices used for restoring
• It is beneficial to patients who refuse further surgery or are at poor
surgical risk for extensive plastic surgery.
• If anatomical part is not replaced with vital tissues
• When recurrence of malignancy is envisaged
• When radiation therapy is given
• When fragments of the facial bones are displaced in the fracture
• When surgery is not possible due to advanced age, reduced blood
supply, large defect requiring extensive surgery or when the patient
• To fabricate a temporary appliance to cover the defect when plastic
surgery repairs require many steps
• When the defect is small and can be restored with surgery.
• When the defect area has good blood supply.
• When prognosis after surgery is good.
Effect of radiation on the oral cavity
Radiation therapy is widely used for the management of malignant
lesions in the oral cavity and other parts of the body. It is used as an
adjunct to surgery or in combination with chemotherapy. The effects
of postradiation are well known and sometimes may result in needless
morbidity. The effects of radiation on the various areas of the oral
• Initially starts as erythema and leads to extensive ulceration with
• Severity of mucositis depends on the area of radiation and the
• It is most severe in the soft palate followed by mucosa of
hypopharynx, floor of the mouth, buccal mucosa, base of the tongue
• Healing is rapid after radiation therapy and usually completes by 2–
• Oral candidiasis is the most common complication.
• As the bone is 1.8 times denser than the soft tissues, it absorbs
considerable amount of radiation than the soft tissues.
• The mandible absorbs more radiation than the maxilla and since it
has reduced blood supply, there is a greater chance of mandibular
• The early effect of radiation leads to significant aberration of the fine
vasculature and to progressive occlusion and obliteration of the
• The late effect of radiation leads to acellularity and avascularity of
the marrow tissues along with its significant fibrosis and fatty
• Gross changes in the bone matrix can make the bone virtually
• Irradiation of the salivary glands can lead to changes in the
viscosity, pH and organic and inorganic constituents of the saliva.
• Changes in saliva can predispose the patient to caries and
• Deglutition becomes difficult and the patient complains of loss of
• With irradiation of the salivary glands, there is progressive
degeneration of the acinar epithelium with increased inter- and
• Ultimately, the glands shrink in size and adhere to the surrounding
• Retention of the removable prosthesis is compromised due to
• Taste buds are readily affected by the radiation therapy and show
signs of degeneration and atrophy.
• There is a partial or complete loss of taste sensation during and
• Reduction of saliva decreases the number of taste buds and alters
the form and function of the remaining buds.
• Irradiation leads to greater chance of teeth decalcification.
• It is believed that pulp undergoes fibrosis and atrophy accompanied
• The patient may complain of root sensitivity after irradiation.
• High doses of radiation can significantly affect the development of
the tooth leading to various anomalies.
• The network of fibres becomes disoriented and thickening of the
periodontal ligament is evident.
• There is decreased acellularity and vascularity to periodontal
ligament which predisposes it to infection.
• The cementum shows severely reduced capacity to repair and
• Periodontal procedures should be planned with caution, especially
Evolution of maxillofacial prosthesis
Maxillofacial prosthodontics has evolved many folds over the period
of time. A brief description about the evolution of various prostheses
and materials are given below.
Egyptian mummies: Auricular, nasal and ocular prostheses were
fabricated with various materials.
Before AD 1600, Chinese were known to fabricate nasal and auricular
prosthesis using natural waxes, resins and metals such as
1541: The first obturator was made by Ambroise Pare which consisted
of a simple disc attached to sponge.
First artificial eye was made of glass in 1579 in Venice.
Tycho Brahe (1546–1601) was famous Danish astronomer who made
an artificial nose of gold and silver.
1710: Pierre Fauchard fabricated a silver mask for a French soldier
named Alphonse Louis who was wounded by shell fragment,
which removed nearly all of the left side of the mandible and
maxilla. The soldier was called gunner with the silver mask.
1800s: William Morton fabricated nasal prosthesis using enamel
porcelain to match the complexion of the patient.
1823: J. Snell fabricated gold plate obturator.
1855: C. Goodyear developed vulcanite rubber used for improved
1880: N. Kinsley described a combination of nasal palatal prosthesis
1894: F.L.R. Tetamore fabricated a nasal prosthesis of light-weight
nonirritating material called cellulose nitrate developed by John
1900–1940: Upham fabricated nasal and auricular prosthesis from
1905: Ottofy, Baird and Baker reported the use of black vulcanized
rubber for fabricating maxillofacial prosthesis.
1913: Gelatine–glycerine compounds were introduced for use in
facial prosthesis in order to mimic softness and flexibility.
During the same period, V. Kazanjian used celluloid
prints for colouring vulcanized rubber facial
1937: Acrylic resin was introduced and replaced by vulcanite rubber.
1940–1960: Adolph Brown administered colours in facial prosthesis.
1942: A.H. Bulbian introduced the use of prevulcanized latex for
pliable facial prosthetic restoration.
1953: American Academy of Maxillofacial Prosthetics was formed.
1960–1970: The introduction of various kinds of elastomers resulted in
1965: G.W. Barnhart was the first to use silicone rubber for
construction and colouring of facial prosthesis.
1975: A. Koran and R.G. Craig investigated the properties of selected
silicone elastomers, polyvinyl chloride (PVC) and polyurethane.
1976: D.N. Firtell and C.R. Anderson introduced the concept of
combining materials to achieve improved properties.
1977: P.I. Branemark and associates first placed extraoral implant in
the mastoid region to support a bone conduction hearing aid.
1982: A. Udagama and J.B. Drane introduced a new silicone elastomer
(medical adhesive type A, or Dow Corning A-891).
1984: M. Abdelnnabi et al. compared a new material
polydimethylsiloxane (PDMS) with MDX 4-4210.
1987: A. Udagama presented a technique for bonding polyurethane
1970–1990: J.B. Gonzalez described the use of polyurethane
1988: BAHA, i.e. bone-anchored hearing aid, was approved by the
1990s: Rapid prototyping technology used in maxillofacial
prosthodontics is used to create three-dimensional models from a
three-dimensional representation (CT scan or MRI).
2008: 3D printing used to bioprint maxillofacial prosthesis (Fig. 31-1).
2014: 3D Bioplotter is used to create human body parts although it is
FIGURE 31-1 Bioprinting of ear prosthesis.
Materials used in prosthetic restoration
Classification of different materials used in fabrication of maxillofacial
On the basis of usage, maxillofacial materials can be broadly
• Condensation and addition silicones
(ii) Mouldable and sculpting materials
• Vinyl polymers and copolymers
• Silicone elastomers – heat temperature vulcanizing
(HTV) and room temperature vulcanizing (RTV)
Desirable properties of ideal materials
• Should have good aesthetic property; it should simulate the colour,
form, texture and translucency of the adjacent natural skin
• Should have suitable working time
• Should be dimensionally stable
• Should be soft, resilient, flexible and simulate the feeling of real
• Should be easily cleaned without damage or deterioration
• Should be easily available and inexpensive
• Should have sufficient edge strength even in thin margins
• Should have low thermal conductivity
• Should be stable during temperature variations
• Should be durable and resistant to stains
• Should be stable when exposed to ultraviolet (UV) rays, oxygen or
Definitive materials used in maxillofacial
Definitive materials used in the fabrication of the maxillofacial
• Vinyl polymers and copolymers
• Silicone elastomers – HTV and RTV
• These are used in cases where little movement of tissue bed occurs
• These are used in the fabrication of both intra- and extraoral
• These are derivatives of ethylene and contain a vinyl group in their
• The polymerization can be initiated by UV light or heat as well as by
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