auricular defects may be congenitally or occur secondary to trauma or surgical removal of a neoplasm . although plastic surgery is capable of restoring missing tissues it may not be the ideal choice of treatment because of the complex shape and structure . for restoration of complex organs such as ears , prosthetic restorations may be option to surgical restorations due to the aesthetical success of them.1,2 there are various methods for manufacturing an auricular prosthesis . these are ( a ) hand sculpturing method , ( b ) impression of a similar ear , and wax modeling with this impression and ( c ) rapid prototyping techniques.3,4 conventional prosthetic treatment is done by taking the impression with irreversible hydrocolloid or silicone and afterwards forming the model ( cast ) by using hard dental stone . wax model is prepared on this cast and final prosthesis is processed with silicone material . this method may discomfort the patient and underlying tissues may distort and cause difference between the cast and the patient s tissues . besides , the conventional method needs more experience and more time for laboratory work.5,6 achievements in computer technology in 1980 s made it possible to produce 3 dimensional ( 3d ) models in computer medium by using the images obtained by using computerized tomography , magnetic resonance imaging or laser surface scanners . computer aided manufacturing ( cam ) is production of this 3 dimensional ( 3d ) model by rapid prototyping technology.7 rp consists of two stages . these stages are virtual stage ( modelling and simulating ) and physical stage ( fabrication ) . this process allows the production of geometrically complex shaped models that would be impossible to produce . most important disadvantages of this system are requirement of equipments and high cost.8,9 recently , six rapid prototyping technologies can be used to produce anatomic models : ( 1 ) stereolithography which is a layer by layer 3-d model production system in which the model can be produced from various ultra - violet photo - polymerizing resins by laser - fusing , ( 2 ) laminated object manufacturing , which creates 3-d models by laminating adhesive coated sheets of paper in which the adhesive is heat - activated by a focused laser beam , ( 3 ) selective laser sintering , which selectively fuses thin layers of heat fusible powders such as polycarbonate or glass - filled composite nylon and enables the direct fabrication of wax prototypes for development of facial prostheses that can be sterilized by epoxyethane and recycled , ( 4 ) solid ground curing which laser - polymerizes successive layers of resin through a stencil , ( 5 ) 3-d ink - jet printing , which selectively deposits binding material through a print head to fuse a thin layer of metallic or ceramic powder to a previously fused layer and then fired in a furnace for sinterizing , and ( 6 ) fused deposition modeling , which builds models by depositing layers of molten thermoplastic materials.7,10,11 advantages of cad / cam technique are ; ( 1 ) elimination of disturbance due to the impression material because there is no need to take impression , ( 2 ) possibility to form the model by avoiding deformation of the tissue due to the use of techniques that do not require contact such as ct or laser surface scanner ( 3 ) possibility to obtain more realistic looking prosthesis because the model is formed from natural tissues , ( 4 ) ability to store the models in hard disks , thus requirement of less space for storage . prosthesis made from silicone lose characteristic properties and color by time , thus they only may be used maximum for two years . because of this storage of models are very important.7,1215 when compared to all these advantages , only disadvantage of cad / cam technique is high cost . although most of the procedure is performed by the computer , expertise of clinician for application and coloring affects the success of the prosthesis.14,15 these stages are virtual stage ( modelling and simulating ) and physical stage ( fabrication ) . this process allows the production of geometrically complex shaped models that would be impossible to produce . most important disadvantages of this system are requirement of equipments and high cost.8,9 recently , six rapid prototyping technologies can be used to produce anatomic models : ( 1 ) stereolithography which is a layer by layer 3-d model production system in which the model can be produced from various ultra - violet photo - polymerizing resins by laser - fusing , ( 2 ) laminated object manufacturing , which creates 3-d models by laminating adhesive coated sheets of paper in which the adhesive is heat - activated by a focused laser beam , ( 3 ) selective laser sintering , which selectively fuses thin layers of heat fusible powders such as polycarbonate or glass - filled composite nylon and enables the direct fabrication of wax prototypes for development of facial prostheses that can be sterilized by epoxyethane and recycled , ( 4 ) solid ground curing which laser - polymerizes successive layers of resin through a stencil , ( 5 ) 3-d ink - jet printing , which selectively deposits binding material through a print head to fuse a thin layer of metallic or ceramic powder to a previously fused layer and then fired in a furnace for sinterizing , and ( 6 ) fused deposition modeling , which builds models by depositing layers of molten thermoplastic materials.7,10,11 advantages of cad / cam technique are ; ( 1 ) elimination of disturbance due to the impression material because there is no need to take impression , ( 2 ) possibility to form the model by avoiding deformation of the tissue due to the use of techniques that do not require contact such as ct or laser surface scanner ( 3 ) possibility to obtain more realistic looking prosthesis because the model is formed from natural tissues , ( 4 ) ability to store the models in hard disks , thus requirement of less space for storage . prosthesis made from silicone lose characteristic properties and color by time , thus they only may be used maximum for two years . because of this storage of models are very important.7,1215 when compared to all these advantages , only disadvantage of cad / cam technique is high cost . although most of the procedure is performed by the computer , expertise of clinician for application and coloring affects the success of the prosthesis.14,15 at the first case , computerized tomography of the skull of a patient who has 2 implants at auricular region was obtained in order to have the model to produce the prosthesis ( figure 1 ) . adhesion was maximized by soldering bars to the implants used for retention of prosthesis ( figure 2 ) . for this patient iti ( straumann inc . ) afterwards , 3d model was obtained from the data of computerized tomography by the help of a software ( mimics , materialise inc . ) . by the same software reciprocal model of the ear at intact side following the saving of model in stl format , output of 3d model was taken by 3d ink - jet printer ( z printer ; z corp . inc . ) . this acrylic model was transformed into wax model by conventional methods , and tried on the patient ( figure 4 ) . no problems observed for the edge fitting for the model and then it is produced from silicone by conventional methods ( figure 5 ) . at the second case , also computerized tomography of the skull of a patient who has 2 implants at auricular region was obtained as the first case ( figure 6 ) . gold bars and matrixes in this patient ( figure 7 ) . as the first case reciprocal image of the intact ear was used to form defected ear , it was saved in stl format and three dimensional output is obtained by stereolithography ( perfactory standard sxga+ , envisiontec inc . ) ( figure 8) . following the transformation of this acrylic model into wax model and tried on , silicone prosthesis is finished by conventional methods ( figures 9 , 10 and 11 ) . design and fabrication of auricular prosthesis by cad / cam techniques are advantageous because a highly skilled technician is not necessary to sculpt the ear . procedure that allows impression without contact eliminates the errors likely to occur at impression taken by conventional methods . while impression materials used for taking the impression of face , dimensions may cause deformation of the underlying tissue due to their weight the prosthesis produced by cad / cam techniques will be more realistic and will maintain good facial harmony . despite computerized technique seems to be more complicated , finishing of prosthesis takes less time when compared to the conventional methods . also the digital images and molds can be preserved . this feature is quite important when the need for renewal of the prosthesis for every two years due to the deformation and hardening of the silicone is considered . the only disadvantage of this method is its requirement of expensive equipments and experienced computer software operator.4,5,14,16,17 although there are various rapid prototyping techniques , expensiveness of each promotes the investigators to find cheaper and that has wider field of usage.12,14 besides all , this technology is insufficient for the production of maxillofacial prosthesis . because taking the output of prosthesis directly from the silicone material is not yet possible and coloring is still a problem for clinicians .
maxillofacial prostheses are usually fabricated on the models obtained following the impression procedures . 
 disadvantages of conventional impression techniques used in production of facial prosthesis are deformation of soft tissues caused by impression material and disturbance of the patient due to . 
 additionally production of prosthesis by conventional methods takes longer time . recently 
 , rapid prototyping techniques have been developed for extraoral prosthesis in order to reduce these disadvantages of conventional methods . 
 rapid prototyping technique has the potential to simplify the procedure and decrease the laboratory work required . 
 it eliminates the need for measurement impression procedures and preparation of wax model to be performed by prosthodontists themselves in the near future this technology will become a standard for fabricating maxillofacial prostheses .