MAXILLOFACIAL PROSTHESIS

INTRODUCTIONMaxillofacial prosthesis 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 because of surgical intervention, trauma, pathology, or developmental or congenital malformation.

Types of maxillofacial defectsA.Types of maxillary defectsMaxillary defects can be broadly classified as:- a) Congenital - Cleft Lip - Cleft Palate b) Acquired - Total Maxillectomy - Partial Maxillectomy

Congenital maxillary defectsMost common congenital maxillary defects include cleft lip and cleft palate.Other defects like sub-mucous cleft palate, pierre robin syndrome, hemifacial microsomia are treated using same principles followed in the management of cleft lip and cleft palate. Cleft Lip and Cleft palateCleft Lip occurs due to improper fusion between fronto-nasal and maxillary process.If occurs on one side leads to unilateral cleft and if occurs in both sides then bilateral cleft.

Aetiology includes infections, drugs (phenytoin, ethanol,and barbiturates), poor diet, harmonal imbalance in 1st trimester and genetic factors.Cleft lip with or without cleft palate occurs in ratio of 1:1000.Twice common in males as compared to female. Classification Of Cleftsclassification based: on extent of defect classified into three types:- CLASS 1: Cleft lip with alveolus (primary palate). CLASS 2: Cleft of hard and soft palate (secondary palate). CLASS 3: Combination of 1 and 2.

Classification of Cleftsa) Bilateral Cleft Lip b) Single Median Cleft Lip CLASS 1 CLASS 2 CLASS 3

Veaus Classification Of Cleft Palate. Veaus (1922) classified cleft palate into 4 types mainly:-CLASS 1: Cleft involving soft palate. Can also be sub-mucous Cleft, which appears normal.CLASS 2: Midline Cleft involving bone, present only on posterior part of palateCLASS 3: Unilateral Cleft extending along mid-palatine suture and a suture between pre maxilla and palatine shelf.CLASS 4: Unilateral Cleft extending along mid-palatine suture and both sutures between pre-maxilla and palatine shelf.

Veaus Classification Of Cleft Palate CLASS 1 CLASS 2 CLASS 3 CLASS 4

Acquired Maxillary DefectsMost acquired maxillary defects occur due to surgical resection of tumours.Benign lesions require smaller resection and are easy to restore.Malignant tumours require extensive resection, which are very difficult to restore. Types of Acquired Maxillary DefectsMaxillary defects are usually classified based on their extent.If both maxillae are resected, defect is considered as total maxillectomy.

Resection of one or a part of maxilla or palate is considered as partial maxillectomy. Aramany proposed a classification of partial maxillary defects based on their extent.CLASS 1: it is unilateral defect involving one half of the arch and adjacent palatine shelf. The defect extend to midline (all teeth in that side of the arch are missing).CLASS 2: it is a unilateral defect involving one side of the arch posterior to the canine (teeth posterior to canine are absent).CLASS 3: defect involving the centre of palatine shelves (all the teeth are present).

Types Of Acquired Maxillary DefectsCLASS 1CLASS 2 CLASS 3

CLASS 4: it is bilateral defect involving one side of the arch along with the entire pre-maxilla (all anteriors along with posteriors of one side are missing).CLASS 5: it is bilateral posterior defect (teeth anterior to second premolar are present).CLASS 6: it is bilateral anterior defect (teeth anterior to second premolar are absent).

CLASS 4 CLASS 5CLASS 6

B. Types Of Mandibular Defects Congenital Defects Of MandibleCongenital mandibular defects that require maxillofacial prosthesis are uncommon.Common congenital defects of mandible includes micrognathia, mandibulofacial dysostosis, ankylosis of tempromandibular joint.Acquired Defects Of MandibleNeoplastic resection is one of the most common causes for an acquired mandibular defect.Common neoplasia which advocate need for resection are squamous cell carcinoma of tongue, oropharynx and floor of the mouth.These tumours are usually treated by surgery, radiation or both.

Involvement of deep cervical lymph nodes is common and hence radical neck dissection is necessary.Resection of mandible may often lead to speech and swallowing dysfunction, which are very difficult to manage. Types Of Acquired Mandibular DefectsBased on amount of resection or bone loss (extent), mandibular defects can be classified as :-Continuity Defect: Here superior portion of mandible is resected and lower border is left intact. These defects do not show any deviation and are easy to restore.

Discontinuity Defect: here entire segment of mandible is resected. Since there is no connection between remaining parts of mandible, there will be midline deviation of mandible due to movement of bone.Deviation may also occur when remaining ends are surgically approximated in order to produce continuity. The amount of facial disfigurement of these defects is remarkable.

Types Of Acquired Mandibular Defects Continuity Defect Discontinuity Defect

Velo-Pharyngeal DefectsThey are basically defects of palate, which affects closure of naso-pharyngeal and oro-pharyngeal isthmus. This lack of closure affects speech. Causes Of Velo-Pharyngeal DefectsThese defects may result from:-Congenital malformation (cleft palate)Developmental aberrations (short hard or soft palate)Acquired neurological defectsSurgical resection of neoplasms leading to hyper-nasality and decrease in intelligibility of speech.

Types Of Volo-Pharyngeal DefectsThey can be classified into congenital and acquired defects. Congenital Velo-pharyngeal DefectsThey are further classified based on physiological and structural integerity of tissuesPhysiological Velo-Pharyngeal Defects (palatal Incompetence): The velo-pharyngeal structures are normal but mechanism of closure is absent. Examples includes patients with neurological diseases like myasthenia gravis, cerebovascular accidents like closed head injuries.

Velo-Pharyngeal defects due to poor structural integrity (palatal insufficiency): Movements of velo-pharyngeal structures are normal but length of soft palate is inadequate to ensure complete velo-pharyngeal closure. Examples are cleft palate and soft palate. Acquired Velo-Pharyngeal DefectsThey are broadly classified into defects due to surgical resection of neoplasms and defects due to trauma and neurological deficiencies.

Treatment Of Velo-Pharyngeal DefectsCongenital Velo-Pharyngeal defects due to palatal insuffiency can be restored by surgical reconstruction followed with insertion of an obturator to correct residual palatal insufficiencies.Congenital Velo-Pharyngeal defects due to poor structural integrity can be treated with palatal surgery.Acquired Velo-Pharyngeal defects due to surgical resection can be treated by surgical reconstruction and prosthodontic rehabilitation (E.g. obturator)Acquired Velo-Pharyngeal defects due to trauma and neurological deficiencies can be treated by prosthodontics rehabilitation using palatal lift prosthesis.

EXTRAORAL DEFECTSExtraoral defects occur due to trauma, neoplasms or congenital malformation. Extraoral defects that occur due to trauma are dealt separately under traumatic defects.The common neoplasia of head and neck include:-Epithelial tumorConnective tissue tumorExtraoral congenital malformation that required maxillofacial prosthesis include :Auricular defectNasal defectOcular defectLip and cheek defectCombination of above

TRAUMATIC DEFECTSTrauma can be classified as intentional and unintentional.Intentional include suicide and unintentional include falls, traffic accidents, burns, etc.Maxillofacial trauma grossly involves hard tissue fracture like cranial fracture and soft tissue injuries involving TMJ.Traumatic patient are usually managed in 4 phases:-First phase- In this there is initial stabilization of patient and lasts for two weeks.Early management phase, treatment like splintig, RCT, intermaxillary fixation are done, extend from 2 to 6 weeksPhase of intermediate management- In this treatment prosthesis is provided to bring tissue to normal contour, duration is 3monthsPhase of definitive management- Extends from six months to three years, permanent prosthesis like CD, FPD, Implant are fabricated.

Maxillofacial defects in completely edentulous patients are usually restored with modified complete dentures. Since the size and extent of the defects are highly variable, there are no clearcut principles to govern the fabrication of the prosthesis.Complete Dentures for Cleft Lip and Cleft Palate Patients It is difficult to plan a complete denture for a cleft palate patient because the size of the maxilla will be very small compared to the mandible due to lack of downward and forward growth. The palatal vault will be shallow in these patients alongwith a decreased residual ridge height; this may lead to compromised stability.

Since the inter-arch distance is usually increased, a class three relationship is common. Sufficient support cannot be obtained due to the lack of bony palate. Scarring of the soft palate may indiscriminate the vibrating lines. The posterior palatal seal cannot be recorded for such cases. Scar tissues rebound under pressure. Hence relief should be provided.The patient should be warned about the compromises in treatment. While impression making, small fistulous openings should be blocked out using a gauze dipped in petroleum jelly.

Metallic oxide and plaster impression material should be avoided because they may get entangled into the fistulous openings. Light bodied elastomers are preferred. Conventional border moulding should be done using custom-made special trays. A light bodied rubber base impression should be made using the border-moulded tray.The posterior border of the denture base should end in the depression between the scars to avoid interference from the tongue.The maxillary occlusal rim should be contoured according to the scarred lip contour.For aesthetic reasons, the maxillary teeth should be placed in the maximum possible vertical dimension. Lower teeth are usually set first and consecutively used as a guide to set the maxillary anteriors.

Due to the presence of scars, it may be difficult to record the correct depth of the labial sulcus. The lips should be repeatedly moved downward, forward and laterally to record the depth properly. It may be difficult to fabricate a good temporary denture base. Hence a permanent denture base should be fabricated for better stability. It is advisable to have the patient present during teeth arrangement. The tooth adjacent to the labial scar usually lateral incisor should be set above the occlusal plane with a slight lingual rotation. This helps to make the scar less conspicuous.The labial flange of the denture should be reduced for aesthetic reasons.

After processing the denture, smalll acrylic projections and irregularities should be trimmed away prior to insertion. Over extension in the labial vestibule should be corrected only after trying the prosthesis using disclosing wax. An obturator bulb may be necessary to seal a posterior palatal cleft. The bulb can be fabricated over the denture few weeks after denture insertion.Complete dentures for total maxilectomy defects In these patients, a huge defect will be present in the upper jaw. One half of the residual ridge will be missing.Retention will be very poor because of air leakage, poor support and stability, reduced tissue bearing surface area and lack of a proper peripheral seal.

The contour of the defect and the remaining portion of the hard, palate should be used/ engaged to maximise the retention of the prosthesis. Similarly the height and contour of the remaining residual alveolar ridge will determine the stability of the denture. The portion of the complete denture that extends into the defect is denoted as the obturator of the denture.Patients with square or ovoid arch have better retention and stability than those with tapered arches. This is due to the increase in surface area. The junction between the skin graft lining placed on the defect and the oral mucosa will form a scar band. This scar band is flexible enough to allow the insertion of the prosthesis and taut enough to prevent sudden dislodgement of the prosthesis.

It acts like a 'purse string' providing emergency retention. Hence, it is important for the denture extension to engage this scar band for better retention. Additional-retention can be obtained by extending the denture into the nasal surface of the soft palate or into the nasal aperture. A flexible material should be used for these extensions to prevent irritation to the respiratory epithelium above.Impression is usually made using irreversible hydrocolloids. The surface of the defect should be cleaned free of mucous crusting prior to impression making.

Undercuts in the defect are loaded with syringe material prior to seating the tray material.Diagnostic casts are fabricated using dental plaster and the unfavourable undercuts are blocked out on the cast. Sectional border moulding is preferred. The peripheral areas are moulded first. Next the graft area in the defect is moulded followed by the scar band.Soft palate tracing is more important in these cases because it determines the functional stability of the prosthesis during speech and swallowing.

Modelling plastic is relieved to provide space for the impression material and impression making is done as usual. The vertical dimension of occlusion should be recorded in the conventional manner. Soft wax, registration paste or silicone can be used as the recording medium.Since the maxillary cast in these patients will usually be large (as it includes the defect), modified articulators like TMJ articulators can be used for articulation. Occlusion is set according to the contours of the wax rims and the anatomical landmarks. Denture try-in is done as usual. The master cast may have larger extensions than those in the trial base. Hence over-extensions are possible in the final prosthesis.

Soft silicone materials can be used for the obturator segment of the prosthesis. The silicone obturator can have a stud type connection with the denture so that the obturator component can be changed as required.

The tissue surface of the denture should be highly polished using pumice to reduce the frictional assault produced by the dentures to the tissues during function.

Pressure indicating paste or disclosing waxes can be used to check for overextension of the prosthesis.

Usually these dentures may require relining as the defect may remodel due to tissue organization.

Complete dentures for partial maxillectomy defects These patients have better prognosis than total maxillectomoy defects.The rotation of the denture may vary according to the location of the defect.The prognosis of the denture may vary according to the size of the defect. Fabrication procedure is as described for total maxillectomy defects

Complete dentures for lateral discontinuity defects of the mandible here only one half or two-thirds of the mandible is present. Hence, the retention and stability are compromised.Most patients with such defects would have been treated with therapeutic radiation and hence will have an atrophic and fragile mucosa, susceptible to soft tissue irritation and ulceration. Reduced salivary output and presence of thick mucinous saliva will impair retention. A-bnormal pathway of mandibular closure will induce lateral dislodging forces on the denture. Mandibular deviation with abnormal profile and jaw relation will affect the normal arrangement of artificial teeth.

The factors that determine the prognosis of these dentures are: The extent of bone and soft tissue resection (smaller resection has better prognosIs).The involvement of tongue, floor of mouth and buccal mucosa during resection.The motor and sensory control of the tongue.The mobility and bulk of the tongue. Mandibular deviation Position of the tongue (if the base of the tongue was resected it will have a retruded position). The nature of mandibular movements. Postsurgical lip closure and control (usually the lower lip on the resected side will be retracted posteriorly leading to lip and cheek biting). Post-radiation effects

While border moulding, the non-resected side should be traced to its full depth. The lingual flange of the resected and non-resected side should be recorded accurately to improve both the placement and retention of the denture.The support of the prosthesis can be obtained from the buccal shelf, crest of the ridge, retromolar pad and the soft tissue pad posterior to the bony resection.The lip and cheek on the resected side will be heavily scarred and can dislodge the prosthesis. The denture flange should be designed such that it repositions the lower lip on the resected side.This labial flange is referred to as the Lip plumper.While recording the jaw relation, the labial / fullness of the maxillary occlusal rim should be reduced in order to make the jaw discrepancy less conspicuous.

The vertical dimension of occlusion should be reduced or patients with Iimited tongue movement in order to facilitate speech. The posterior teeth on the non-resected side should be positioned more buccally in order to transmit more forces along the supporting areas. The posterior teeth on the resected side should be positioned lingual to the crest so that the occlusion is improved. The scars in the buccal mucosa may be unyielding and displace the denture. This is prevented by the lingual placement of the teeth.Occlusal ramps should be developed on the opposing maxillary denture according to the severity in the occlusal discrepancy. The occlusal ramp should be placed buccally in the resected side and palataly on the non-resected side.The mandibular teeth should be able to contact the ramp without any guidance. Tracing wax is added over the ramps and the mandibular movements should be earned out to check for positive contact.

Other steps in the fabrication of the prosthesis are carried out as ususal. The patient should be instructed to avoif uding denture during recall visits to improve oclusion.Lip plumpers may be added with auto-polymerising resin in order to reduce lip biting.Removable Partial Dentures for a Cleft Lip and Cleft Palate PatientFabrication is similar to that for a normal patient.Removable partial dentures with a palatal lift - prosthesis with/without an obturator should be provided for patients with cleft lip associated with soft palate defect (velopharyngeal deficiency).Tortuous fistula like openings may be present in patients where a bone graft was not provided to fill the cleft. In order to prevent the impression material from entangling into these defects, gauze dipped in petroleum jelly should be placed over the site during impression making.

There will be severe scarring in the healed soft tissue. These tissue scars will appear as tortuous folds of firm mucosa. In such cases, the removable partial denture should be designed such that its margins follow the scars and do not cross the scars. The thickness of the beading along the margins of the major connector should be reduced for these patients. Removable Partial Dentures for Total Maxillectomy Defects The size of the defect influences the stability of the prosthesis. Bigger defects provide minimal support and the prosthesis will be heavy and bulky. The prosthesis will have maximal rotation on the defective side and the gravitational forces (downward pull) may aggravate the problem.

The prosthesis should be designed to distribute masticatory forces to the edentulous ridge and the remaining teeth in a balanced manner. The mucosal and bony support will be compromised due to surgical resection. Square or ovoid arch forms have a better prognosis than tapered arch forms. Tapered arch forms have reduced surface area. This can lead to rotation and movement of the prosthesis into the defect during mastication. Preservation of remaining teeth is a primary concern of treatment. The prosthesis should be designed such that the abutment teeth are protected from excessive forces. The occlusion on the defective side will determine the . occlusal forces acting on the abutment teeth.

Compromised abutment teeth may be treated endodontically and the crown can be amputated. The remaining root can be used as an over denture abutment.The fulcrum line of the prosthesis is influenced by the following factors: Position of the occlusal and cingulum rests. Size and configuration of the defect.Location and magnitude of the masticatory forces on part of the prosthesis that restores the defect. The patients may exhibit varying degrees of trismus. If the depth of the palate and the height of the artificial teeth or components of the partial denture is greater than the maximum opening distance between the incisor teeth, the prosthesis cannot be inserted or removed.

The patient usually tends to bite on the anterior teeth. The masticatory forces on the artificial anterior teeth can displace the denture. Hence, the patient should be instructed to masticate primarily on the non-defctive side.The finish lines of the cast metal framework should be on the palatal mucosa and 2 mm short of the palatal shelf.Removable Partial Dentures for Partial Maxillectomy Defects The prosthodontic considerations are similar to total maxillectomy cases. But these patients have a " better prognosis.The presence of a canine on the defective side enhances the stability and support. If there are remaining natural teeth on the defective side, the fulcrum line shifts posteriorly. The indirect retainers should be placed as anterior to the fulcrum line as possible.

Placement of a retainer adjacent to the defect increases the stability and retention.The fabrication is similar to that for total maxillectomy defects.If there are small defects, gauze pieces should be used to block the defects to prevent the impression material from entering the paranasal sinuses.If there are edematous turbinates extending onto the palate, it will interfere with the restoration of the palatal contour. These turbinates have to be surgically removed before impression making.

Removable Partial Dentures for Other Acquired Maxillary Defects

Small, localised defects can occur after excision of benign lesions. The alveolar ridge and the teeth are minimally involved in the resection. The obturotor must maintain contact with the soft palate as it lifts from the prosthesis during function. The obturator acts as a shield and directs the liquids and food into the oropharynx.A scar band is usually present at the junction of the oral and nasal mucosa. The prosthesis should extend as superiorly as possible without interfering with the nasal functions. Removal of large portions of the orbital floor can lead to misalignment of the eyeballs and diplopia. A flexible superior orbital extension can be attached with obturator to uplift the orbital contents. Care must betaken to avoid excessive contact and trauma to the fragile nasal mucosa.

Removable Partial Dentures for Continuity Maintained or Re-established Mandibular Defects Removable Partial Dentures foe Anterior Defects:-The anterior edentulous segment shows unusual soft tissue configurations and compromise bony support. Large defects show obliterated vestibules and lack of attached , mucosa. These cases may require vestibulop!asty and placement of skin grafts.A scar band is usually present across the residual anterior alveolar ridge between the lip and the tongue. These bands can displace the prosthesis and can be traumatised by the prosthesis.

Occlusal abnormalities will occur in cases with anterior discontinuity defects, which were improperly restored with poorly positioned segments. The occlusion is rarely altered in - cases with continuity defects and the pattern of mandibular movement is normal.Masticatory efficiency may be compromised when there is a large anterior defect. Implants may be needed for additional support. Removable Partial Dentures for Lateral Defects These patients will have posterior teeth only - on one side of the arch. Presence of long lever arms and compromised supporting tissues may complicate the situation. During mastication, the anterior and posterior proximal plates move freely during function. The labial retainer on the cuspid disengages under occlusal load. This excess load on the abutments is avoided.The posterior retainer and lingual plating aid in retention and bracing.

Maximum coverage of the edentulous area is needed.The patient is instructed to bite on the non defective side with the remaining mandibular teeth.FIXED PARTIAL DENTURES IN MAXILLOFACIAL PROSTHETICS Fixed Partial Denture for a Cleft Lip and Cleft Palate Patient If bone raft was done to complete an alveolar cleft, an implant supported single tooth replacement or a regular three-unit bridge can be fabricated.If bone graft was not provided to fill the alveolar cleft, a fixed partial denture with additional secondary abutments on either side of the defect should be involved. Discoloured natural teeth should be restored with composite or porcelain veneers.

OBRURATORS AND VELO-PHARYNGEAL PROSTHESIS OBRURATORS"A prosthesis used to close a congenital or acquired tissue opening primarily of the hard palate and/or contiguous alveolar structures. Prosthetic restoration of the defect often includes use of a surgical obturat.Rehabilitation of maxillary resection is done in three phases. During the first phase, a surgical obturator is placed. An interim obturator is placed in the second phase and a definitive obturator is placed during the third or final phase.

Types of Obturators Obturators can be classified: Based on the phase of treatment Based on the material used Based on the area of restoration Based on the Phase of Treatment Surgical obturatorsIt is defined as, "A temporary prosthesis used to restore the continuity of the hard palate immediately after surgery or traumatic loss of a portion or all of the hard palate and or continuous alveolar structures (i.e., gingival tissue, teeth)".

It is of two types namely:- Immediate surgical obturator: It is inserted at the time of surgery. Delayed surgical obturator: It is inserted 7 to 10 days after surgery. Interim obturators:- It is defined as, "A prosthesis that is made several weeks or months following the surgical resection of a portion of one or both maxillae. It frequently includes replacement of teeth in the defect area, This prosthesis, when used, replaces the surgical obturator that is placed immediately following the resection and may be subsequently replaced with a definitive obturator" . Definitive obturators:-It is defined as, "A prosthesis that artificially replaces part or all of the maxilla and the associated teeth lost due to surgery or trauma.

Based on the Material Used :-Based on the material used, obturators can be classifie in to:Metal obturators Resin obturators SIlIcone obturators Based on the Area of Restoration Palatal obturator Meatal obturator

Clinical Considerations Surgical obturator is inserted on the day of the surgery.A preliminary cast is obtained before surgery on which a mock surgery is performed.A clear acrylic plate is fabricated and inserted after surgery.If the patient is dentulous, retention is obtained with simple clasps. If the patient is edentulous, the obturator is wired into the alveolar ridge and the zygomatic arch.The immediate surgical obturator is retained for 7 to 10 days after surgery. A delayed surgical obturator is inserted 7 to 10 days after surgery.

This may be converted into an interim obturator by the addition of a lining material.This obturator is retained for 3 to 4 months post surgically. It is replaced with an interim or definitive obturator after complete healing of the surgical wound.Uses Provides a stable matrix for surgical packing.Reduces oral contamination.Speech will be effective post-operatively. Permits deglutition Reduces the psychological impact of the surgeryMay reduce the period of hospitalisation.

Meatal Obturator It is a special type of obturator that extends upto the nasal meatus.It establishes closure with the nasal structures at a level posterior and superior to the posterior border of hard palate. The closure is established against the conchae and the roof of the nasal cavity. It separates the oral and the nasal cavities. It is indicated in patients with extensive soft palate defects. Disadvantages Nasal air emission cannot be controlled because it is in an area where there is no muscle function. Nasal resonance will be altered.

Palatal Lift Prosthesis It is a special type of obturator, which is a definitive prosthesis with a posterior extension.It is helpful in restoring palato-pharyngeal incompetence where the soft palate musculature is compromised, E.g. myasthenia gravis, bulbar poliomyelitis. cerebral palsy. It can be clubbed with an obturator if needed.Advantages:- Minimised gag response Tongue physiology swallowing, mastication and speech are not compromised.Access to the nasopharynx for the obturator is facilitated.The palatal lift portion can be added later as desired. Contraindications If adequate retention is not available for the basic prosthesis.If the palate is not displacable. Un-cooperative patients.

EXTRA-ORAL PROSTHESIS Auricular Prosthesis It is an ear prosthesis.It is fabricated from impressions made with silicone or irreversible hydrocolloids. During impression making, the patient is made to lie in a supine position. The defect area should be confined with wax. 50% additional water can be added while mixing irreversible hydrocolloids to increase the flow. A plaster with gauze backing can be used to support the impression. The shape of the ear can be formed with reference to a pre-surgical cast or using the healthy ear. This procedure of shaping the ear is known as sculpting.Stippling is done to match the texture of the prosthesis with the adjacent skin. It also facilitates extrinsic tinting. It provides mechanical retention for extrinsic colorants.Feathering is done on the margins of the wax pattern.

Extra-Oral Prosthesis

The prosthesis is flasked in a three part mould and the material (acrylic or silicone) is processed as usuaI.The retention of the prosthesis is through ear-glass frames or tissue adhesives or extensIon of prosthesis into ear canal. Nowadays osseointegrated implant retained prosthesis are given.Nasal Prosthesis It is fabricated for rhinectomy patients.There are two types of nasal prosthesis namely temporary and permanent. The temporary prosthesis is placed 3 to 4 weeks after surgery. It is usually made of heat cure acrylic as it can be relined. Most of the' temporary prosthesis are retained with adhesives. It can be used for a maximum of 3 to 4 months.The permanent prosthesis is fabricated as described for auricular prosthesis. During impression making, care should be taken to block the nasal passages and prevent the entry of impression material.

Nasal Prosthesis

Ocular Prosthesis It is used to replace enucleated eyes. One should remember that the lacrimal aparatus (eyelids and associated glands) is intact in these patients. Hence the prosthesis only replaces eyeball. The impression is made with irreversible hydrocolloids.A special tray is fabricated. The secondary impression is made with irreversible hydrocolloids. Casts are poured in two sections with two keyways in the first pour and separating medium. Sclera is fabricated with wax. It is tried in the eye socket and evaluated for Iid contours. Following which, it is flasked and de-waxed.Special scleral white acrylic resin is available for such procedures.

Scleral resin is packed, processed, trimmed and polished as usual. Next the ocular barf prosthesis is tried in the patient's defect. The position of the iris is determined during the trial procedure. The patient is made to relax. The dentist should mark the location of the iris by comparing it with the unaffected eye on the other side. The iris is placed and fused to the scleral prosthesis. A cut back is created in the sclera to seat the iris button.Characteristic pigmentations on the iris can be apprhended according to the shade of the other ' eye. This procedure is known as Iris painting. Patient's Instructions The patient is asked to remove the prosthesis atleast once a day for cleaning. The prosthesis should never be exposed to alcohol as it may discolour the prosthesis and the painting.

TREATMENT PROSTHESIS A treatment prosthesis can be defined as, "A prosthetic appliance used for the purpose of treating or conditioning the tissues that are called on to support and retain it" Commonly used treatment appliances include surgical obturators, mandibular training flanges and radiation appliances.