**Abstract**

Today, both additive manufacturing (3D image technology and 3D printing) had been developed dramatically and involved virtually in all fields of medicine and surgery. It has been widely applied in surgical and prosthetic reconstruction of the craniofacial defects. The aim of this chapter is to characterize and assess the mechanical and optical properties of 3D colored printed soft tissue facial prostheses produced by Z-Corp-Z510 and infiltrated with Sil-25 maxillofacial silicone polymers. Mechanical properties assessed according to ASTM specifications for tensile strength, tear strength, hardness and percentage elongation. Furthermore depth of infiltration plus quality of infiltration was assessed. Scanning electron microscopy SEM was applied for this purpose to determine the characteristic of interaction and incorporation between the starch powder particles and the silicone polymers. Finally, method of color reproduction and evaluation for the printed prostheses are recommended.

**Keywords:** maxillofacial, anaplastology, rapid prototyping and facial prostheses, skin color

#### **1. Introduction**

Anaplastology is a multidisciplinary branch of medicine that deals with artificial reconstruction of a disfigured, absent or anatomically malformed part of the face or body by fabricating a customized facial or somatic prosthesis for the patient [1]. The prostheses provide descriptive evidence for steps of fabrication of these devices, including location, retention, support, time, materials, and form [2, 3]. Prostheses are artificial devices which either implanted or attached to the body to replace or restore a body part that might be congenitally missing or might have been lost due to tumor ablation or external trauma [4]. Facial disfiguration is considered a challenge for the patient; as it negatively interferes with the patient's self-image and ability coexist in a normal social life. Although the prosthesis is well appreciated by the patients, however, in many instances it does not restore function totally [1, 5]. Surgery can repair small defects, whereas, large defects could not be repaired surgically [6], Hence, prosthetic rehabilitation is frequently applied. This depends on a variety of factors including patient's age and systemic condition, size and site of the defect, patient's satisfaction and cost factors [7–9]. For example, an old patient with poor systemic health is not a good candidate for surgery, on the other hand, an impaired vision or a poor manual dexterity patient is not a good candidate for prosthesis as he will not be able to maintain the prosthesis properly.

Defects in the craniofacial region mostly lead to severe depression, even in some instances to self-isolation and rejection of life, hence, surgical reconstruction and/or prosthetic devises will be an insistent demand for a patient with facial disfiguration [10]. Esthetically appropriate Prosthetic rehabilitation of the patient is rather challenging requires multidisciplinary team for comprehensive care and optimal cost treatment functional and esthetic outcomes [11–14]. Oro-facial areas comprises a variety of vital and important structures, every so often surgical management of cancer in this region predominantly with widespread cancerous lesion require extensive removal of tissue—the cancerous lesion and part from the normal tissue around the lesion as a protective measure of surgical management of cancer. As a result of this aggressive surgical procedure many vital functions would be impaired such as esthetics, phonetics, mastication and vision. In these cases an extensive defect would be left behind that would most probably not be reconstructed surgically, alternatively prosthetic rehabilitation will be performed to improve patient's esthetics/function [15, 16]. Prosthetic rehabilitation of these patient provides comfort to the patients, improves their confidence and selfesteem. High level of satisfaction was recorded among patients wearing facial prostheses [17]. They experienced much better quality of life after wearing facial prostheses [16, 18].

The fabrication protocol of facial prostheses involves several intricate steps as described by many authors [19–21] including taking an impression or impressions, obtaining an accurate stone cast in order to carve an accurate wax model for the defect on that cast. The wax model then checked on the patient and transferred to the final material, which is mostly be a silicone polymers by process of flasking and deflasking after adding the basic skin color. Ultimate color matching is accomplished by adding extrinsic colors at the time of fitting and delivery.

Method of fabrication that is applied currently has shown several limitations. These are primarily related to the fabrication protocol, high technical expertise required, time, effort, cost plus retention and esthetic problems. These limitations make access to global patient's community almost denied, only a small number of these patients can get access to this sophisticated device, those who can afford the high cost of the prosthesis, whereas, people at the other poor global regions such as Africa and India they cannot easily obtain a good prosthesis.

In recent years, both additive manufacturing (also known as 3D printing) and 3D image technology had been developed dramatically and becomes more and more popular in medical science under the term of medical rapid prototyping (MRP). Medical Rapid prototyping was first described by Mankowich et al. in 1990 for imaging and producing anatomically accurate human parts models by rapid prototyping methods [22]. MRP then started to grow more and more to involve a wide range and fields in medicine including tissue engineering, dental implantology, craniofacial surgery and reconstruction and orthopedics.

Many aspects of this brilliant technology have still not been entirely functional for maxillofacial surgical/prosthetic rehabilitation. This technology has not been fully incorporated in producing maxillofacial soft tissue prostheses. However, some articles and few case reports applied this technology in the manufacturing process as producing accurate wax models for ear and other parts of the face using 3D printing machines to be replicated by the silicone polymers [23–27]. They were able to produce highly accurate anatomical models of the missing parts, nevertheless, the entire procedure found to become more time consuming and much costly than if the prosthesis made by hand alone.

In our previous studies, an innovated method of fabrication of soft tissue facial prostheses using 3D color printing technology have been developed using Z-Corp

**113**

following sections.

**Figure 1.**

technology [31].

**2. Mechanical properties**

*Optimization of Maxillofacial Prosthesis DOI: http://dx.doi.org/10.5772/intechopen.85034*

printer, printing in starch as a powder and colored ink as a water based binder, printing process based on computer aided design and manufacture CAD/CAM [28–30]. **Figure 1** summarize the current project that starts with 3D Data acquisition instead of using a complicated multiple impression techniques, then processing these date in a 3D computer aided design—CAD package, building a virtual 3D model for the prosthesis, color mapping then the printing process accomplished using Z510-3D color printer. After printing the robot models infiltrated with

*An overview of rapid manufacturing technology applied to fabricate soft tissue facial prostheses.*

elastomeric silicone in order to achieve skin texture and softness. Furthermore, data

With above protocol, there is huge potential to replace the conventional technology by the rapid manufacturing technology with saving both time and cost. However, some more factors affect quality of prostheses significantly, including mechanical properties, infiltration and degree of skin color reproduction. In this study, these factors are investigated and further developed. Results are described in

The mechanical properties of facial prostheses is very important since it directly related to durability of the prostheses. For 3D printing technology we proposed, a starch powder were used to print soft tissue prostheses by a Z-Corp Z510 3D printer and infiltrated using silicone polymers as the post processing. The mechanical properties of the composite produced by Z-Corp printer is tested here by comparing its' mechanical properties with object produced by silicone polymer using conventional

Test models that were printed from starch by Z Corp 3D printer and infiltrated

Mechanical test for conventional technology is simulated using pure silicone

Pure silicone samples were designed according to ASTM specifications for tensile strength (Dumbbell-shaped specimens [32]), tear strength (Trouser-shaped specimens [33]), hardness test [34], and percentage elongation using solid work

with maxillofacial silicone polymer—Sil-25 are shown in **Figure 2**.

polymers and used as control samples (**Figure 3**).

can be saved for future printing of further copies on demand.

*Optimization of Maxillofacial Prosthesis DOI: http://dx.doi.org/10.5772/intechopen.85034*

#### **Figure 1.**

*Prosthesis*

prostheses [16, 18].

Defects in the craniofacial region mostly lead to severe depression, even in some instances to self-isolation and rejection of life, hence, surgical reconstruction and/or prosthetic devises will be an insistent demand for a patient with facial disfiguration [10]. Esthetically appropriate Prosthetic rehabilitation of the patient is rather challenging requires multidisciplinary team for comprehensive care and optimal cost treatment functional and esthetic outcomes [11–14]. Oro-facial areas comprises a variety of vital and important structures, every so often surgical management of cancer in this region predominantly with widespread cancerous lesion require extensive removal of tissue—the cancerous lesion and part from the normal tissue around the lesion as a protective measure of surgical management of cancer. As a result of this aggressive surgical procedure many vital functions would be impaired such as esthetics, phonetics, mastication and vision. In these cases an extensive defect would be left behind that would most probably not be reconstructed surgically, alternatively prosthetic rehabilitation will be performed to improve patient's esthetics/function [15, 16]. Prosthetic rehabilitation of these patient provides comfort to the patients, improves their confidence and selfesteem. High level of satisfaction was recorded among patients wearing facial prostheses [17]. They experienced much better quality of life after wearing facial

The fabrication protocol of facial prostheses involves several intricate steps as described by many authors [19–21] including taking an impression or impressions, obtaining an accurate stone cast in order to carve an accurate wax model for the defect on that cast. The wax model then checked on the patient and transferred to the final material, which is mostly be a silicone polymers by process of flasking and deflasking after adding the basic skin color. Ultimate color matching is accom-

Method of fabrication that is applied currently has shown several limitations. These are primarily related to the fabrication protocol, high technical expertise required, time, effort, cost plus retention and esthetic problems. These limitations make access to global patient's community almost denied, only a small number of these patients can get access to this sophisticated device, those who can afford the high cost of the prosthesis, whereas, people at the other poor global regions such as

In recent years, both additive manufacturing (also known as 3D printing) and 3D image technology had been developed dramatically and becomes more and more popular in medical science under the term of medical rapid prototyping (MRP). Medical Rapid prototyping was first described by Mankowich et al. in 1990 for imaging and producing anatomically accurate human parts models by rapid prototyping methods [22]. MRP then started to grow more and more to involve a wide range and fields in medicine including tissue engineering, dental implantology,

Many aspects of this brilliant technology have still not been entirely functional for maxillofacial surgical/prosthetic rehabilitation. This technology has not been fully incorporated in producing maxillofacial soft tissue prostheses. However, some articles and few case reports applied this technology in the manufacturing process as producing accurate wax models for ear and other parts of the face using 3D printing machines to be replicated by the silicone polymers [23–27]. They were able to produce highly accurate anatomical models of the missing parts, nevertheless, the entire procedure found to become more time consuming and much costly than

In our previous studies, an innovated method of fabrication of soft tissue facial prostheses using 3D color printing technology have been developed using Z-Corp

plished by adding extrinsic colors at the time of fitting and delivery.

Africa and India they cannot easily obtain a good prosthesis.

craniofacial surgery and reconstruction and orthopedics.

if the prosthesis made by hand alone.

**112**

*An overview of rapid manufacturing technology applied to fabricate soft tissue facial prostheses.*

printer, printing in starch as a powder and colored ink as a water based binder, printing process based on computer aided design and manufacture CAD/CAM [28–30]. **Figure 1** summarize the current project that starts with 3D Data acquisition instead of using a complicated multiple impression techniques, then processing these date in a 3D computer aided design—CAD package, building a virtual 3D model for the prosthesis, color mapping then the printing process accomplished using Z510-3D color printer. After printing the robot models infiltrated with elastomeric silicone in order to achieve skin texture and softness. Furthermore, data can be saved for future printing of further copies on demand.

With above protocol, there is huge potential to replace the conventional technology by the rapid manufacturing technology with saving both time and cost. However, some more factors affect quality of prostheses significantly, including mechanical properties, infiltration and degree of skin color reproduction. In this study, these factors are investigated and further developed. Results are described in following sections.
