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Technique to prevent fracture of a partial auricular prosthesis mold
DENTAL TECHNIQUE
Technique to prevent fracture of a partial auricular prosthesis mold Saumya Kapoor, MDS,a Saumyendra V. Singh, MDS,b Deeksha Arya, MDS,c and Pooran Chand, MDSd Partial auricular defects are a ABSTRACT result of certain congenital One of the difficulties faced during the essential and demanding step of fabricating a mold for a disorders, trauma, or tumors. partial auricular prosthesis is the fracture of its most elevated part, which engages the remnant The loss of an ear, an organ concha and triangular fossa region, because of the presence of excessive convolutions and aiding in acoustics and es- undercuts. This technique describes a 4-part mold for a partial auricular prosthesis in which the thetics, affects social behavior most elevated portion is poured separately, thereby preventing mold fracture. (J Prosthet Dent and psychology.1 Management 2019;-:---) of such defects can be either surgical or prosthetic, depending on the patient’s age, medical and financial circumstances, and the condition of the residual tissue. When surgical reconstruction is not indicated, a prosthesis is the best management option. The procedure for fabricating a complete silicone auricular prosthesis normally involves a 3-piece stone mold to facilitate characterization, prevent prosthesis tearing on retrieval, and prevent mold fracture.2 Direct printing of a virtually designed prosthesis by using a high-resolution 3D silicone printer has been described.3 The technique reproduces major and minor anatomic surfaces of the prosthesis and has also been applied to nasal prosthesis fabrication.4 However, the current scope of characterization is restricted with these techniques, limiting the esthetics of the prosthesis. The initial cost associated with digital equipment is another disadvantage, and the accuracy and applicability of digital technology for facial prosthesis fabrication is still unclear.5 One of the difficulties faced during fabrication of a partial auricular prosthesis with the 3-piece stone mold Figure 1. Partial auricular defect. technique is fracture of the elevated part of the mold, which fits into the natural concha and triangular fossa
a
Senior Resident, Department of Prosthodontics, Faculty of Dental Sciences, King George’s Medical University, Lucknow, India. Professor, Department of Prosthodontics, Faculty of Dental Sciences, King George’s Medical University, Lucknow, India. c Associate Professor, Department of Prosthodontics, Faculty of Dental Sciences, King George’s Medical University, Lucknow, India. d Professor, Department of Prosthodontics, Faculty of Dental Sciences, King George’s Medical University, Lucknow, India. b
THE JOURNAL OF PROSTHETIC DENTISTRY
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Figure 2. Partial auricular pattern.
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Issue
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Figure 3. First, second, and third parts of mold poured.
Figure 4. Four-part mold separated.
Figure 5. Separated acrylic resin third part of mold with dowel pin.
region. The region has extreme convolutions and undercuts that are susceptible to fracture. The technique developed provides a straightforward and rapid method of preventing mold fracture and uses materials available in a dental laboratory. TECHNIQUE 1. Make an impression of the residual auricle (Fig. 1) with the surrounding tissue by following conventional methods and pour it in die stone (Kaldent; Kalabhai Karson Pvt Ltd). Fabricate the pattern by following conventional steps (G-120; Factor II Inc) (Fig. 2). 2. Create the first 2 parts of the mold in the conventional manner using white die stone (Orthokal; Kalabhai Karson Pvt Ltd), involving the base and helix region of the wax pattern. 3. Apply a thin layer of separating medium on the first 2 parts of the mold and any portion of the partial ear model which is not to be covered by silicone. 4. Mix autopolymerizing resin (Rapid Repair Cold Cure; DPI) in the advised ratio and allow it to reach THE JOURNAL OF PROSTHETIC DENTISTRY
the doughy consistency. Pack this material into the concha and triangular fossa region to form the third part of the mold. 5. Place a double dowel pin with a single head (Dental Die Pin; Nebula Industries Co, Ltd) in the doughy acrylic resin such that only the head of the pin is in the resin (Fig. 3). 6. Make the fourth and final pour with white die stone (Orthokal; Kalabhai Karson Pvt Ltd), covering the protruding sleeve of the dowel pin, the remaining wax pattern, and the first, second, and third parts of the mold to the requisite thickness. 7. Follow the regular dewaxing protocol and separate the parts of the mold (Fig. 4). The acrylic resin third pour will have the dowel pin (Fig. 5), while the sleeve will be encased in the fourth part of the mold. This allows accurate duplication of the concha region in acrylic resin without the risk of fracture of a stone mold. The acrylic resin can be easily positioned in its designated place and indexed to the fourth pour by the dowel pin. Kapoor et al
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2019
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Limitations of this technique include an increase in the number of steps and the additional time and armamentarium required to fabricate the mold. SUMMARY The article describes a time-efficient and convenient method for preventing the fracture of a partial auricular prosthesis mold by pouring the conchal and triangular fossa portion in autopolymerizing resin, thereby converting the conventional 3-part auricular prosthesis mold into a 4-part mold. REFERENCES Figure 6. Prosthesis in place.
8. Proceed with packing and polymerization, separating and joining the third and fourth mold parts as required (Fig. 6). DISCUSSION This article details a technique for facilitating the fabrication of a 4-part partial auricular prosthesis mold. Part of the mold engaging the concha region is fabricated in autopolymerizing resin. The advantage of using autopolymerizing resin lies in providing rigidity and strength in the vulnerable concha region of the mold, thus preventing the fracture of the mold in this area and facilitating the retrieval of an intact prosthesis. Preservation of the mold is ensured for future prosthesis remakes. The dowel pins allow accurate positioning of the fourth part of the mold to the acrylic resin index.
Kapoor et al
1. Beumer J III, Reisberg DJ, Marunick MT, Powers J, Kiat-amnuay S, vanOort R. Rehabilitation of facial defects. In: Beumer J III, Marunick MT, Esposito SJ, editors. Maxillofacial rehabilitation: prosthodontic and surgical management of cancer-related, acquired, and congenital defects of the head and neck. 3rd ed. Hanover Park: Quintessence Publishing Co, Inc; 2011. p. 271-9. 2. Brown KE. Fabrication of ear prosthesis. J Prosthet Dent 1969;21:670-6. 3. Nuseir A, Hatamleh MM, Alnazzawi A, Al-Rabab’ah M, Kamel B, Jaradat E. Direct 3D printing of flexible nasal prosthesis: optimized digital workflow from scan to fit. J Prosthodont 2019;28:10-4. 4. Unkovskiy A, Spintzyk S, Brom J, Huettig F, Keutel C. Direct 3D printing of silicone facial prostheses: a preliminary experience in digital workflow. J Prosthet Dent 2018;120:303-8. 5. Ballo AM, Nguyen CT, Lee VS. Digital workflow of auricular rehabilitation: a technical report using an intraoral scanner. J Prosthodont 2019;28:596-600.
Corresponding author: Dr Saumyendra V. Singh 2/273 Viram Khand Gomtinagar Lucknow 226010 INDIA Email: [email protected] Copyright © 2019 by the Editorial Council for The Journal of Prosthetic Dentistry. https://doi.org/10.1016/j.prosdent.2019.07.009
THE JOURNAL OF PROSTHETIC DENTISTRY
Technique to prevent fracture of a partial auricular prosthesis mold Saumya Kapoor, MDS,a Saumyendra V. Singh, MDS,b Deeksha Arya, MDS,c and Pooran Chand, MDSd Partial auricular defects are a ABSTRACT result of certain congenital One of the difficulties faced during the essential and demanding step of fabricating a mold for a disorders, trauma, or tumors. partial auricular prosthesis is the fracture of its most elevated part, which engages the remnant The loss of an ear, an organ concha and triangular fossa region, because of the presence of excessive convolutions and aiding in acoustics and es- undercuts. This technique describes a 4-part mold for a partial auricular prosthesis in which the thetics, affects social behavior most elevated portion is poured separately, thereby preventing mold fracture. (J Prosthet Dent and psychology.1 Management 2019;-:---) of such defects can be either surgical or prosthetic, depending on the patient’s age, medical and financial circumstances, and the condition of the residual tissue. When surgical reconstruction is not indicated, a prosthesis is the best management option. The procedure for fabricating a complete silicone auricular prosthesis normally involves a 3-piece stone mold to facilitate characterization, prevent prosthesis tearing on retrieval, and prevent mold fracture.2 Direct printing of a virtually designed prosthesis by using a high-resolution 3D silicone printer has been described.3 The technique reproduces major and minor anatomic surfaces of the prosthesis and has also been applied to nasal prosthesis fabrication.4 However, the current scope of characterization is restricted with these techniques, limiting the esthetics of the prosthesis. The initial cost associated with digital equipment is another disadvantage, and the accuracy and applicability of digital technology for facial prosthesis fabrication is still unclear.5 One of the difficulties faced during fabrication of a partial auricular prosthesis with the 3-piece stone mold Figure 1. Partial auricular defect. technique is fracture of the elevated part of the mold, which fits into the natural concha and triangular fossa
a
Senior Resident, Department of Prosthodontics, Faculty of Dental Sciences, King George’s Medical University, Lucknow, India. Professor, Department of Prosthodontics, Faculty of Dental Sciences, King George’s Medical University, Lucknow, India. c Associate Professor, Department of Prosthodontics, Faculty of Dental Sciences, King George’s Medical University, Lucknow, India. d Professor, Department of Prosthodontics, Faculty of Dental Sciences, King George’s Medical University, Lucknow, India. b
THE JOURNAL OF PROSTHETIC DENTISTRY
1
2
Volume
Figure 2. Partial auricular pattern.
-
Issue
-
Figure 3. First, second, and third parts of mold poured.
Figure 4. Four-part mold separated.
Figure 5. Separated acrylic resin third part of mold with dowel pin.
region. The region has extreme convolutions and undercuts that are susceptible to fracture. The technique developed provides a straightforward and rapid method of preventing mold fracture and uses materials available in a dental laboratory. TECHNIQUE 1. Make an impression of the residual auricle (Fig. 1) with the surrounding tissue by following conventional methods and pour it in die stone (Kaldent; Kalabhai Karson Pvt Ltd). Fabricate the pattern by following conventional steps (G-120; Factor II Inc) (Fig. 2). 2. Create the first 2 parts of the mold in the conventional manner using white die stone (Orthokal; Kalabhai Karson Pvt Ltd), involving the base and helix region of the wax pattern. 3. Apply a thin layer of separating medium on the first 2 parts of the mold and any portion of the partial ear model which is not to be covered by silicone. 4. Mix autopolymerizing resin (Rapid Repair Cold Cure; DPI) in the advised ratio and allow it to reach THE JOURNAL OF PROSTHETIC DENTISTRY
the doughy consistency. Pack this material into the concha and triangular fossa region to form the third part of the mold. 5. Place a double dowel pin with a single head (Dental Die Pin; Nebula Industries Co, Ltd) in the doughy acrylic resin such that only the head of the pin is in the resin (Fig. 3). 6. Make the fourth and final pour with white die stone (Orthokal; Kalabhai Karson Pvt Ltd), covering the protruding sleeve of the dowel pin, the remaining wax pattern, and the first, second, and third parts of the mold to the requisite thickness. 7. Follow the regular dewaxing protocol and separate the parts of the mold (Fig. 4). The acrylic resin third pour will have the dowel pin (Fig. 5), while the sleeve will be encased in the fourth part of the mold. This allows accurate duplication of the concha region in acrylic resin without the risk of fracture of a stone mold. The acrylic resin can be easily positioned in its designated place and indexed to the fourth pour by the dowel pin. Kapoor et al
-
2019
3
Limitations of this technique include an increase in the number of steps and the additional time and armamentarium required to fabricate the mold. SUMMARY The article describes a time-efficient and convenient method for preventing the fracture of a partial auricular prosthesis mold by pouring the conchal and triangular fossa portion in autopolymerizing resin, thereby converting the conventional 3-part auricular prosthesis mold into a 4-part mold. REFERENCES Figure 6. Prosthesis in place.
8. Proceed with packing and polymerization, separating and joining the third and fourth mold parts as required (Fig. 6). DISCUSSION This article details a technique for facilitating the fabrication of a 4-part partial auricular prosthesis mold. Part of the mold engaging the concha region is fabricated in autopolymerizing resin. The advantage of using autopolymerizing resin lies in providing rigidity and strength in the vulnerable concha region of the mold, thus preventing the fracture of the mold in this area and facilitating the retrieval of an intact prosthesis. Preservation of the mold is ensured for future prosthesis remakes. The dowel pins allow accurate positioning of the fourth part of the mold to the acrylic resin index.
Kapoor et al
1. Beumer J III, Reisberg DJ, Marunick MT, Powers J, Kiat-amnuay S, vanOort R. Rehabilitation of facial defects. In: Beumer J III, Marunick MT, Esposito SJ, editors. Maxillofacial rehabilitation: prosthodontic and surgical management of cancer-related, acquired, and congenital defects of the head and neck. 3rd ed. Hanover Park: Quintessence Publishing Co, Inc; 2011. p. 271-9. 2. Brown KE. Fabrication of ear prosthesis. J Prosthet Dent 1969;21:670-6. 3. Nuseir A, Hatamleh MM, Alnazzawi A, Al-Rabab’ah M, Kamel B, Jaradat E. Direct 3D printing of flexible nasal prosthesis: optimized digital workflow from scan to fit. J Prosthodont 2019;28:10-4. 4. Unkovskiy A, Spintzyk S, Brom J, Huettig F, Keutel C. Direct 3D printing of silicone facial prostheses: a preliminary experience in digital workflow. J Prosthet Dent 2018;120:303-8. 5. Ballo AM, Nguyen CT, Lee VS. Digital workflow of auricular rehabilitation: a technical report using an intraoral scanner. J Prosthodont 2019;28:596-600.
Corresponding author: Dr Saumyendra V. Singh 2/273 Viram Khand Gomtinagar Lucknow 226010 INDIA Email: [email protected] Copyright © 2019 by the Editorial Council for The Journal of Prosthetic Dentistry. https://doi.org/10.1016/j.prosdent.2019.07.009
THE JOURNAL OF PROSTHETIC DENTISTRY