Dent 626 Extraoral Prosthesis-Orbital Prosthesis (1) PDF

Extra – oral maxillofacial prosthesis fabrication techniques – ORBITAL DEFECTS  CONTENTS INTRODUCTION UNFAVORABLE ORBITAL DEFECTS STEPS OF PROSTHETIC PROCEDURE RETENTION IMPLANTS SUPPORTED ORBITAL PROSTHESIS  INTRODUCTION A maxillofacial prosthesis...

Extra – oral maxillofacial prosthesis fabrication techniques – ORBITAL DEFECTS  CONTENTS INTRODUCTION UNFAVORABLE ORBITAL DEFECTS STEPS OF PROSTHETIC PROCEDURE RETENTION IMPLANTS SUPPORTED ORBITAL PROSTHESIS  INTRODUCTION A maxillofacial prosthesis that artificially restores the eye, eyelids, and adjacent hard and soft tissues.-GPT 9  INTRODUCTION Orbital prosthesis may be considered to be amongst the most difficult of all facial prosthesis to construct Due to the reconstruction of a moving organ with a prosthesis that is static, so it becomes apparent upon movement of the contra-lateral eye.  EXENTERATION Is the most radical of the three procedures (Enucleation, Evisceration, Exenteration) Involves removal of the eye , adnexa and the part of the bony Orbit. Maxillofacial rehabilitation prosthetic and surgical considerations ;John Beumer; 1996  Alteration at surgery to enhance the prosthetic prognosis Orbital defect: Line orbit with skin Avoid distortion of the eyebrow Do not close the defect with the flap Do not retain the eyelid Maxillofacial rehabilitation prosthetic and surgical considerations ;John Beumer; 1996  Fabrication of orbital prosthesis IMPRESSION MATERIALS FOR OBTAINING FACIAL MOULAGE Reversible hydrocolloid Impression Irreversible compound hydrocolloid Room Plaster of temperature paris vulcanizing materials  MODELLING MATERIALS Modelling Clay ( Sculptor’s Clay) - A water-based clay which, when allowed to dry, becomes a hard, stone-like substance Plaster Waxes  MATERIAL FOR PROSTHESIS Polymethyl methacrylate Polyurathane elastomer Silicone elastomer Urethane backed medical grade silicone  Extraoral impression Essential to a well-fitting and well-fabricated prosthesis.  Patient preparation – I. Should either be reclined on a dental chair or preferably lying on a table with head slightly elevated. II. Draped with sheet and hair boxed out with cloth towels. III. Face should be free of make up and eye glasses. IV. Eyelashes, eyebrows and moustache should be coated with vaseline. V. Deep undercuts blocked out with wet gauze or cotton. Digital impression Digital impression  STEPS IN THE FABRICATION OF ORBITAL PROSTHESIS The Moulage impression and Working Cast fabrication Sculpture and Formation of the Prosthesis Pattern Fabrication of the Mold Processing of the Prosthesis Material with Intrinsic and Extrinsic coloration Insertion of Eye lashes 1.THE MOULAGE IMPRESSION AND WORKING CAST FABRICATION When all drapes and protective materials have been applied, cotton balls tied with the help of dental floss are used to plug the nostrils. These cotton balls should be large enough, just to plug the nostrils without distorting them. Then patient is asked to practice breathing through the evacuator tube placed in the mouth to ensure adequate ventilation. After the patient starts breathing comfortably through the tubes, alginate is mixed using water/powder ratio of 1.25 to 1.50 times the normal amount of water.  After mixing, the alginate is applied to the skin surface with a round-end mixing spatula, taking care to avoid air entrapment. When the area has been covered, opened gauze squares or the bent paper clips are applied over the entire surface using light pressure. The rigid plaster backing necessary for removal of the impression without distortion.  Fast-set plaster is mixed to a cake-batter consistency and spread over the entire impression surface to a thickness of about 0.25 inch. A thicker ridge of reinforcement may be added at the midline. Surface of the plaster is checked for tapping sound with a blunt instrument after 4-5 minutes to check setting of the plaster.  For removal of the impression, the impression is grasped on both sides of the patients’ head and gentle lifting force is applied. During this procedure instruct the patient to wiggle or to produce wrinkles on the face; this will assist in freeing the impression from the skin. Also instruct the patient to release the breathing tube. Patient will usually appear flushed due to the heat and moisture from the impression, but skin color and temperature will rapidly turn to normal  Impression is inspected for any voids or distortion, especially in the area around the defect where the margins of the prosthesis will be developed. Small defects or voids not associated with the margin area may be filled in or chipped off the cast. Disinfect the impression.  Points to be remembered: Packing an orbital defect before impression should be given special attention. Moist cotton or petrolatum gauze should be used to close the communication if any, with the nasal or oral cavity. Full facial or midfacial impression is preferred. Patient should be cautioned to relax their faces to prevent marked changes in the orbital opening. In cases of extensive defects, intraoral prosthesis should be in place so that soft tissue contours around the mouth and cheek will remain stable.  SCULPTURE AND FORMATION OF THE PROSTHESIS.2 PATTERN  Wax is preferred over modeling clay as residual oils from the clay contaminate the mold surfaces.  Wax formula – two sheets of beeswax, - one sheet of hard pink baseplate wax - two strips of clear rope boxing wax  Dry earth pigments- to form skin color. A sheet of pink baseplate wax is adapted to the orbital defect which forms the basis for positioning the ocular section of the prosthesis within the defect in the same frontal, sagittal and horizontal planes as the normal eye. Positioning is best accomplished by placing the ocular section on a stalk of soft wax in the wax cup. Assembly placed into orbital defect and ocular section manipulated into the position that matches the gaze of the normal eye when the patient is staring directly at a point at eye level atleast 6 feet away.  Positioning the Prosthetic Eye 1. Anatomic references on the skin 2. Vernier caliper 3. Pupillometer An instrument to achieve pupil alignment in eye prosthesis 4. Ruler or Tongue blade 5. Profile gauge 6. Bright light 7. Ocular locator Ocular locator and fixed caliper. Note the scribed midline and the two horizontal lines. The fixed caliper duplicates the distance between the two horizontal lines. 8.Simplified ocular locator 9. Relating pupil of the prosthetic eye to the existing natural eye by facial measurements 10. Inverted anatomic tracing (Nusinov 1998)  11. Computer imaging (Adobe Photoshop) Computer imaging may be used to assist establishment of the correct ocular positioning and lid opening.  Once the correct positioning of the ocular section has been accomplished and the eyelid aperture established, the soft sculpting wax mixture is added with a glass eye dropper or spatula to roughly fill the remaining contour of the prosthesis out to the area where margins are to be established. Following the completion of the fine details in the pattern, the sculpture should be placed onto the patient and verified for fit, direction of gaze, and eyelid aperture. When satisfied, the pattern is ready for making the mold  FABRICATION OF THE MOLD.3  After the stone flasking material has set in the tissue- surface half of the mold, Foil substitute is applied to the exposed stone surrounding the pattern, because it is least likely to contaminate the platinum catalyst of the silicone prosthesis material.  Indexing method applied to position the ocular segment of the prosthesis, now incorporated in the wax pattern, back into the mold in its same orientation as in the pattern. Prior to investing, an index in the form of horizontal and vertical pyramids is placed on the surface of ocular segment with sticky wax. 1. Index reproduced in the cope segment of the mold removed from drag to avoid damaging the indexing wax 2. ocular segment removed from the wax pattern and duplicated using alginate impression. 3. duplicate segment including indexing wax poured in dental stone and placed into the index indentations in the cope with cyanoacrylate adhesive. 4. This segment forms a pocket in the final silicone  PROCESSING OF THE PROSTHESIS MATERIAL WITH.4.INTRINSIC AND EXTRINSIC COLORATION Even when the contours of the prosthesis are not exact duplicates of the contralateral structures and the skin texture not exactly reproduced Many methods are practised … Coloration technique …… a)Micro air-spray techniques. b)Brush-in technique (no distinctive intrinsic color). COLORATION TECHNIQUE Mold cavity prepared by coating external tissue surface with catalysed uncolored silicone material Base colour Hair drier used mixture of to partially silicon prepared polymerize first to fill mold clear layer cavity Characterization Colored rayon colours fibres sprinkled chosen,mixed with into the mold to silicone simulate the polymer,painted on microvasculature the surfece of clear layer  Silicone Colored, Mold then catalyst catalysed, air less clamped and silicone placed added and into mold cavity, placed into dry air removed heat oven for allow liquid to from mixture polymerization flow in all areas  INSERTION OF EYE LASHES AND.5 EYEBROWS Processed curved natural hair taken from human arm used Broach holder and ‘Y’ needle required. When desirable number of lashes have been thus placed, they are trimmed to alternately long and short lengths to lend a natural appearance.  MAINTAINENCE OF THE PROSTHESIS Prosthesis should be removed once a day to be cleaned  The adhesive is removed with a rolling motion of the ball of the finger or thumb.  Foreign substances should be removed  Prosthesis washed with mild soap and brush. Skin in contact with prosthesis should be cleaned.  Instructions to the patient  Since the artificial eye does not track with the natural eye of the opposite side, the patient should learn to turn his head when changing his line of vision  How to orient and place it  How to maintain the hygiene of both tissue and prosthesis (in warm water with a mild soap)  How to apply the surgical cement  The prosthesis should not be worn while sleeping Additionally, patients should be advised that the color match depends on the color of their tissues, which are susceptible to the seasons as well as activity levels and environmental temperature Prosthesis is stored in a container away from direct light or heat. Isopropyl alcohol may be used to remove the oily residue. To prevent premature discoloration of the prosthesis, it should not be exposed to cigarette smoke.  Implant supported prosthesis Not all patients with defects are candidates for implant supported prosthesis. Contraindicated in - Patients with cartilaginous peripheral tissue - Thick layers of skin which cannot be reduced -Further Implant sites: Superior lateral orbital rim or Superior maxilla  Retention of the prosthesis A. Anatomic B.Mechanical Retention Retention Hard Magnets tissues Soft Snap Buttons tissues and Straps Adhesives Spectacle Borne Retention Combination of the Above  Attachments used in facial prosthesis  Magnets (Cobalt – samarium) More BAR AND RETENTIVE CLIPS recently neodymium, boron and iron magnets.  Clips ( Nobel Pharma DCA 078, O- INDIVIDUAL MAGNETS Quist)  Ball attachments (Nobel Pharma)  Dalbo attachment ( Sjodings, Sweden) BALL ATTACHMENTS Impression is made 8 – 12 weeks after connection of the abutments. This allows time for adequate healing stabilization of the soft tissue to ensure fit and marginal adaptation of the prosthesis. daily hygiene procedures should be performed by the patient to maintain the health of the soft tissue.  Conclusion The goal of any prosthetic treatment is to return the patient to society with a normal appearance and reasonable motility of the prosthetic eye. The disfigurement resulting from loss of eye can cause significant psychological, as well as social consequences. However with the advancement in ophthalmic surgery and ocular prosthesis, patient can be rehabilitated very effectively.  References Textbook of Clinical maxillo facial prosthesis ; Thomas D.Taylor; Quitessence publication 2006 Maxillofacial prosthetics handbook ; William Laney ;PSG Publication 1979 Ocularprosthesis : A Physiologic system Stephen O.Barlett , Dorsey J. Moore ; J Prosthet Dent 1973;29;4;450