Volume 23, Issue 3 (Autumn 2022)                   jrehab 2022, 23(3): 450-463 | Back to browse issues page


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Mardani M A, Zarezadeh F, Hashemi H. Implant-based Prosthetic Reconstruction In Patients With Congenital Ear Defects (Technical Note). jrehab 2022; 23 (3) :450-463
URL: http://rehabilitationj.uswr.ac.ir/article-1-3016-en.html
1- Department of Orthotics and Prosthetics, School of Rehabilitation Sciences, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran.
2- Department of Orthotics and Prosthetics, School of Rehabilitation Sciences, Iran University of Medical Sciences, Tehran, Iran. , hashemi_oandp@yahoo.com
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Introduction
Artificial replacement and manufacture of the jaw and facial prostheses is a combination of art and science related to anatomical, functional, and aesthetic reconstruction. These prostheses are used to reconstruct complete or partial defects of the head and neck. One of the most important and common defects of the jaw and face is the ear area. 
Ear defects may be congenital or acquired, and acquired defects arise from a secondary cause. The most common congenital ear defect is microtia. Microtia is a congenital deformity of the earlobe that can be unilateral or bilateral and occurs with a prevalence of 1 in 8000 to 10000 births [1]. Ear defects for any primary or secondary reason will make the patient a candidate for an ear prosthesis. Although silicone ear prostheses are one of the methods of non-invasive cosmetic reconstruction, they present various challenges to the patient and prosthetist. Among these challenges is matching the appearance and maintaining this prosthesis model on the face. Considering that ear defects, unlike finger and hand defects, hardly provide the possibility of suspension from the remaining stump [2], the choice of their suspension method is one of the concepts to consider in-ear prostheses [3]. The problem of suspending extra-oral maxillary prostheses such as ear prostheses causes patients’ dissatisfaction and decline, creating the necessity of using a reliable suspension method. The four main methods for suspending these prostheses are using adhesive, mechanical, anatomical, and implant [4]. The most reliable method is implant [2], which creates a suitable holder for the prosthesis and makes it easier to put on and take off. Also, implants make it possible to place large prostheses on movable tissue substrates [5]. As a result, prosthodontists devote all their efforts to the beauty of the prosthesis by ensuring proper suspension. The implant method has a high level of support and maintenance, which increases the patient’s confidence that the prosthesis will not fall. In this study, according to the patient’s request and preparation of the stump and the good condition of the soft tissue of the temporal region, this method was chosen. 
Methods and Results
 In this study, the patient was a 35-years-old man with a congenital ear defect (microtia) without a history of using a prosthesis, referred to the Faculty of Dentistry of Shahid Beheshti University to receive a prosthesis. Following the patient’s request to ensure the prosthesis on the face, the available suspension methods were evaluated. Due to not using glasses or having enough stamps, mechanical and anatomical options were rejected. Also, due to the limitation and the possibility of prosthesis tearing, using the adhesive method was rejected, and thus, the implant method was chosen among the methods of prosthesis suspension. 
In the initial evaluation stage, the patient was examined regarding his readiness to receive the implant. An assessment of the risk factors of implant suspension, including excessive skin fat, the presence of extra hair, and excessive sweating of the skin, was performed. After ensuring the absence of any harmful factors, the patient was referred to a surgeon. In the initial stage of the surgery, the excess soft tissues were first removed, and after the soft tissue recovery, the patient was ready for molding and implant placement (Figure 1).

To start the process of making the prosthesis, the patient’s evaluation stage was done first. At this stage, the investigations included the examination of sensitivity, hardness, and softness of the tissue, healthiness or unhealthiness of the tissue, and the presence of bleeding, wound, or injury in the ear. One of the important things in this stage was to evaluate the mental readiness of the patient to receive the prosthesis. 
After completing the evaluation process, the patient’s molding stage was done. It should be noted that the molding of the temporal area and the remaining tissues were done before implant placement. Then, after being placed on the temporal on the plaster mold, the fixture, abutment, and load were checked many times in terms of position, direction, and shape. In case of final approval, we allocated some time to improve the soft tissue and control any possible infections due to the fixture and the embedded base. To continue the process of prosthesis construction, the prosthetist was given the mold on which all the implant components (fixture, abutment, and load) were placed. To mold from the temporal area, we placed a circular box made of cardboard or wax on the temporal so that during molding, the material did not spread on the head and neck. The thickness of the molding material in the desired area was maintained at an acceptable level.
To prevent substances from entering the ear cavity, we dipped a cotton ball in Vaseline and placed it in the ear cavity. Also, we put the patient’s head in a horizontal position to prevent the material from moving downwards. It should be noted that alginate was used for all moldings in this study. Alginate is a substance in the form of a powder that is mixed with water. We used cold water to combine with alginate to increase the setting time of alginate and to allocate enough time to the prosthodontist for more precise molding. After obtaining a smooth paste of alginate and water, we poured it into the molding place and waited for the material to form well and harden. After the alginate hardened, we slowly removed it from the ear and filled the obtained mold with dental plaster. Because skin color is different in various pathological and physiological conditions, the important point in the stage of making the primary or background color is the replication of the prosthesis and the skin according to the texture of the surrounding lines and the color. Also, factors such as blood vessels and pigments such as melanin and carotene affect skin color. To prepare the background color, we separated some RTV silicone and mixed it with derma color, cosmetic color, and oil painting according to the patient’s skin color. In the three stages, we tried to make the primary color in an environment with moderate temperature so that the patient does not feel too hot or cold. Also, to match the color of the prosthesis with the patient’s skin as much as possible, we compared the color in the natural morning light. At the end of this stage, the background color was slightly lighter than the patient’s skin. Finally, we achieved the desired match in the secondary color stage. 
Before taking a mold from a similar ear (donor), to replicate the dimensions and sizes of the prosthesis with the healthy ear as much as possible, we first took an alginate mold from the healthy side of the patient and filled it with plaster. Then, taking into consideration the dimensions and appearance of this mold, we tried to choose a person with similar ears among the patient’s relatives or other available individuals. Molding of the donor was done using alginate and the same method of stamp molding. Nevertheless, at this stage, we coated the donor mold with a thin wax layer covering the entire inner surface. In the stage of wax correction, we placed the implant components under the donor wax and placed its protrusion in the posterior part of the temporal area so that it looks beautiful and natural from the anterior view (Figure 2).

The other components of the implant, including the clip and the substructure, were placed completely under the wax so that they could be placed between the silicone during the silicone casting stage and connect the prosthesis to the load attached to the temporal. To make the final mold, we used plaster and made a three-piece mold in the muffle. The purpose of dividing the mold into several pieces was that the silicone would not be torn or damaged during the removal of the prosthesis and that the prosthesis could be easily removed from the mold. To drain the wax, we put the plaster mold in boiling water and separated its three pieces (Figure 3).

Then we mixed the painted silicone in the previous steps with a hardener, poured it into the mold, and closed the mold with a tight clip. It should be noted that the implant parts (fixture, abutment, and load) are isolated, and only the clip and substructure are placed between the silicone (Figure 4).

After 24 hours, we separated the three pieces from each other. We removed the prosthesis from the mold and trimmed the extra edges (Figures 5 and 6).

We used oil paint for secondary coloring. In this way, in the presence of the patient and following his skin color, we mixed the appropriate color with silicone glue, and with the help of a sponge or brush, we drew a very delicate painting on the prosthesis. Finally, we considered 24 hours as resting time for the prosthesis to dry and better blend the colors (Figure 7).

In the last stage, the final prosthesis was evaluated in terms of shape, color, size, placement, placement angle, and appropriate suspension on the patient’s face. For this purpose, the distance of the helix to the ear canal, to the tragus, and to the temporal bone were compared on both the healthy and prosthetic sides of the patient. Finally, the angle between the line passing through the ear canal and the line that connects the helix to the ear canal was also compared on both healthy and prosthetic sides. After correcting the defects, the silicone prosthesis was delivered to the patient for use.
Discussion 
The replacement of extra-oral tissues is very challenging due to the many effects on beauty and appearance, and the reconstruction of the external ear prosthesis as an extra-oral tissue is one of the most valuable results in this profession. Prosthetic rehabilitation offers one of the fastest ways to restore the appearance of the face to normal or close to normal, and compared to other methods, it will take the least amount of time and money for the patient; in addition to the fact that this method does not involve the risk of surgery. However, for a better fit of the prosthesis on the face, an initial surgery should be performed on the damaged area in some people. 
While providing jaw and facial prostheses, a prosthetist should pay attention to the fact that every patient comes to medical centers with special and unique problems having different characteristics, advantages, and disadvantages that can be done in their special ways. Therefore, specialists should always search for new treatment methods acceptable to patients and prosthetists. One of the common needs and challenges faced by this group of patients is to achieve the desired appearance while using the prosthesis comfortably. As Dahl pointed out in his article, achieving an ideal facial prosthesis depends on stability, support, and suspension [3]. Suspension is one of the most important concepts in extraoral facial prostheses. 
There are different types of suspension methods that are traditionally used to keep ear prostheses in place. One of the common methods is the adhesive method, with certain disadvantages because removing the glue from the surface of the skin can damage the edges of the prosthesis. In addition, the adhesive method may lead to the accumulation of microbes and possible subsequent infection. The use of implants for extra-oral prostheses such as ears is considered one of the best suspension methods with a high retention ability that improves the appearance [6]. Osseointegration is a phenomenon in which, after inserting a titanium implant screw into the bone, the bone grows on it and fuses to the implant. Implant placement surgery for prosthesis suspension is one of the low-risk methods with minimal risk of failure and very few complications after the operation. Of course, surgeons prescribe implants when it is difficult to place the prosthesis on the face [7]. The use of implants can have advantages such as easiness and safety, suspension, eliminating the problems of using glue, and easiness in probing the wax sample. 
One of the most important advantages of implant suspension is maintaining a thin edge around the prosthesis. Since the need to use adhesives is eliminated with the help of implant suspension, the edges of the prosthesis are not damaged due to repeated gluing and cutting. This issue allows the prosthodontist to make the edges of the prosthesis thinner; but also increases the prosthesis’s lifespan despite the delicacy and thinness of the edges. Also, the skin and mucous membranes are less exposed to abrasion damage caused by mechanical suspension and chemical damage caused by glue suspension. As mentioned, using old suspension methods such as adhesives can cause allergic and inflammatory reactions to the skin and tissue of the stamp. Although implant suspension does not cause allergic and inflammatory reactions in patients’ skin, the patient’s stump skin needs daily examination and care in implant suspension, like other suspension methods [8]. It should be noted that despite the clear advantages of this suspension method, its use is difficult for people who have lost a part of their ear because prosthodontists must remove the rest of a person’s ear with the help of surgery first and then place the implant to make the prosthesis suspended. This problem can make the surgical procedure more difficult and reduce the probability of success after the surgery. When the lesion area, the place where the prosthesis should be placed, is hairy or the patient’s skin is very oily with high skin perspiration, the implant method will not work efficiently [6]. Also, one of the differences in the use of implants is related to people who use radiation therapy to complete their treatment. Because after radiation therapy, the bone is exposed to damage due to demineralization, decreased vascularity, and fibrosis, the suspension of the implant can increase the risk of bone fracture in these people [9].
In summary, choosing a suspension method to fix a pink maxillary prosthesis requires examining the patient’s medical history, current medical care, and preferences and expectations regarding the final prosthesis. If, after the necessary investigations, the patient is a candidate for using the implant method, the smart choice of this method by the prosthodontist can meet many of the patient’s expectations in terms of appearance and ease of wearing and removing. 
Conclusion 
The problem of suspending large prostheses and the decline of the prosthesis in extra-oral maxillofacial prostheses by the patient necessitates the use of implants. In prosthetic suspension, the implant allows the placing of large prostheses on movable tissue substrates. As a result, prosthodontists spend all their efforts on the beauty of the prosthesis. In this study, after using the prosthesis, the patient expressed his satisfaction with the shape, color, size, placement, placement angle, ease of wearing and removing the prosthesis, and good grip. The use of prostheses with implant suspension can be considered a simple and appropriate alternative to surgical reconstruction and a gold standard in rehabilitating people with large ear defects.

Ethical Considerations
Compliance with ethical guidelines

Ethical principles were fully observed in this article. The person reported in this research could stop cooperation at any time and be fully aware of the process of this report. The participant’s identity remained completely confidential.

Funding
This research did not receive any financial assistance from funding organizations in the public, commercial, or non-profit sectors.

Authors' contributions
Conceptualization, methodology, sources, writing, original draft preparation, writing review, and editing: all authors; Supervision: Mohammad Ali Mardani and Fateme Zarezadeh.

Conflict of interest
All authors declared no conflict of interest. 

Acknowledgments
We are grateful for the efforts of Fayaz and Ajali, the distinguished professors of the Faculty of Dentistry of Shahid Beheshti University, and the patient.
 
References
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Type of Study: Case report | Subject: Orthotics & Prosthetics
Received: 12/10/2021 | Accepted: 15/05/2022 | Published: 23/09/2022

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