Auricular prosthesis.pptx

Reconstruction of a facial defect is a complex modality either surgically or prosthetically, depending on the site, size, etiology, severity, age, and the patient’s expectation. The loss of an auricle, in the presence of an auditory canal, affects hearing, because the auricle gathers sound and directs it into the canal.

Surgical reconstruction is preferable but prosthetic approach may be necessary in some circumstances such as the presence of complex or large defects, requirement of the recurrence control, local or general contraindications of surgery, damaged neighboring tissues due to the radiotherapy, general poor health, failed reconstructive attempts previously made, refusal of the surgery by the patient, high esthetic demands, the desire for a quick recovery and palliatively operated patients.

Nowadays, craniofacial implants are used to support and retain such prostheses. Studies have shown successful retention and stability of auricular prostheses anchored to the temporal bone with titanium implants.

1. Implant Retained Auricular Prostheses Meryem Gu¨ lce Subas¸ı , Gamze Alnıac¸ık , Abdullah Kalaycı , Serhan Akman , Ercan Durmus ; J Indian Prosthodont Soc (Dec 2014) 14(Suppl. 1):S196–S201’ Nishu Priya 2 nd -year PGT Journal club 1

2. Introduction 2 Reconstruction of a facial defect is a complex modality either surgically or prosthetically, depending on the site, size, etiology, severity, age, and the patient’s expectation. The loss of an auricle, in the presence of an auditory canal, affects hearing, because the auricle gathers sound and directs it into the canal. Surgical reconstruction is preferable but prosthetic approach may be necessary in some circumstances such as the presence of complex or large defects, requirement of the recurrence control, local or general contraindications of surgery, damaged neighboring tissues due to the radiotherapy, general poor health, failed reconstructive attempts previously made, refusal of the surgery by the patient, high esthetic demands, the desire for a quick recovery and palliatively operated patients. Nowadays, craniofacial implants are used to support and retain such prostheses. Studies have shown successful retention and stability of auricular prostheses anchored to the temporal bone with titanium implants .

3. Fabrication The traditional method of fabricating an auricular prosthesis usually involves: 3

4. Retention Adhesives Medical adhesives are more often classified according to their use; double‑sided tape, glue, sprayers, pastes, and liquid systems are classified according to the silicone substrate. Double‑sided tape is the most highly preferred type of adhesive due to its ease of application, easy removal, and renewability. Facial prostheses are often used in adhesive systems such as acrylic resins, silicone adhesives, and pressure sensitive tapes. Adhesives and solvents may adversely affect the physical and optical properties of the maxillofacial elastomers They do not provide sufficient adhesion against gravity, sweating, and tissue movement. 4

5. Implant Implant retention is currently considered as the gold standard in prosthetic reconstruction of these structures. Bone thickness in the temporal and supraorbital regions, suitable places for implant placement, ranges between 2.5 and 6 mm; hence, extraoral implants were designed to be 3–4 mm long and 5 mm in diameter, unlike intraoral implants. 5 Extraoral implants have wing extensions and holes to provide mechanical stability and retention. Originally, craniofacial implants were introduced by Nobel Pharma, then transferred to Nobel Biocare , Göteburg in the Swedish market.

6. Implant systems used in extraoral prostheses Bar systems In bar systems, there is a bar that connects the implants to each other and a retentive lock that sits in this bar. The bars used in these systems are gold alloys and are about 2 mm in diameter. To hold the clips in the prosthesis, an acrylic plate is prepared. Leaving a distance of about 1.5 mm between the bar and the tissue is important to allow for the easy cleansing of this area. 6

7. Magnetic systems Magnet systems consist of individual implant supports that do not require superstructure preparation and are not interconnected. These systems are used in the retention of a facial prosthesis, in regions with high muscle activity adjacent to the prosthesis; in cases where the ability to use the hand is inadequate, the bone is thin, the bone. 7

8. Implant retained auricular prosthesis The location of the implants in the temporal region is very important for the aesthetics of auricular prosthesis. Implants should be placed at the anti‑helix level because retention systems must remain within the limits of the auricular prosthesis. In the literature, some researchers have recommended that 2 implants are enough for auricular function, because the episthesis is not heavy. ( Wazen et al., 1999). 8 Auricular prosthesis retained on ball shaped retentive caps of two implants Auricular prosthesis retained on ball shaped retentive caps of three implants

9. The choices of retentive mechanisms to be applied on the implants depend on the patient, the number of the implants and the flexibility of the episthesis . The conventional retention techniques involve magnetic or clip retention provided by golden bars and ball clip or magnet retentive cap systems 9 Retention provided by golden bars Retention provided by ball clips Retention provided by magnet retentive caps

10. Magnets can be used with at least 3 bone-connected implants. In cases with three implants, a cantilever extension of the bars could be planned. If four bone connected implants were used, there is no need for a cantilever extension of the bars. Episthesis connected on bars between four implants by ball shaped caps are also used. 10 Bars connected to magnets used with 3 bone-connected implants a cantilever extension of the bars no need for a cantilever extension of the bars

11. Magnets offered the advantages of easier fabrication, shortened appointments, and access for peri-abutment hygiene procedures. Magnets also could maintain a longer, more predictable level of retention than clips, which tended to loosen in a shorter period of time. However, bar and clip systems were advantageous biomechanically in that they effectively splinted the implant sites together, and these systems could offer stronger immediate retention. ( Sencimen et al., 2008, Wright et al., 2008) 11

12. Planning The diagnostic step is an important point that must be clearly defined in construction of an auricular prosthesis. CT of the temporal bone and clinical photographs of the patient should be obtained preoperatively to plan the placement and appropriate size of the implants and to evaluate the thickness and spaces of mastoid cortical bone in order to preserve the duramater . ( Ciocca et al., 2009) 12 The arrows show the distances from the mastoid region to the adjacent anatomical structures such as external auditory canal, duramater and the orbita .

13. A new approach to the diagnosis of bone available for craniofacial implant positioning based on Computer-aided design and manufacturing (CAD–CAM) system was described by Ciocca et al. ( Ciocca et al., 2009) A mirrored volume of the healthy ear was rapidly prototyped for a clinical trial in an appropriate position relative to the patient’s face. 13

14. Radiotherapy In cases with aetiology of cancer, the surgeon should be aware of the risk of osseointegration failures and such patients who have undergone irradiation should be treated with caution. ( Gumieiro et al, 2009) Basically, the adverse biological changes that occur when osseous tissues are exposed to ionizing radiation results from alterations in the cellular components of bone, involving significant reductions in the numbers of viable osteoblasts and osteocytes, as well as the development of areas of fatty degeneration within the bone marrow spaces. In addition, regional ischemia could also be seen as results of the blood vessels undergo progressive endarteritis, hyalinization and fibrosis. As a conclusion, radiotherapy is not a contraindication for the use of osseointegrated implants in the maxillofacial region, but the loss of implants is higher in irradiated sites than in nonirradiated sites. ( Gumieiro et al, 2009) 14

15. Surgical technique It has been suggested that the mastoid region as a recipient site could offer the best results in implant retained auricular epistheses . Wright et al have stated that, the mastoid region in nonirradiated patients has provided a high degree of predictable individual implant survival. (Wright et al., 2008) First, during the facial observations, verify the distance between the outer canthus and the tragus, as well as whether the angle of the naso -auditory meatus line is symmetrical in relation to the bipupillar line. The location of the epithesis would be considered in such a way that the epithesis appears symmetrical in relation to the unaffected ear in both its placement and form. 15

16. the method of Tjellström et al. suggested a method that considers a safe implant site to be the site where the following is taken into consideration: the reference axis is set based on the straight line that connects the outer canthus and the tragus in the 3:00 to 9:00 direction of a clock, and a straight line that perpendicularly crosses the previous line centering the external auditory canal in the 0:00 to 6:00 direction also: if the right side is the affected side, the 7:30 to 8:30 and the 10:00 to 11:00 directions along with the location would form an antihelix. As the antihelix is located approximately 20 mm from the external auditory canal, during the operation, there will be a total of two implants: one implant in the 7:30 to 8:30 direction and the other in the 10:00 to 11:00 direction at a distance of approximately 20 mm away from the external auditory canal. 16 Safety area for implant placement described by Tjellström

17. 17

18. After marking the implant sites with surgical pen, a curved incision is used in the skin over the mastoid process approximately 30 mm posterior to the opening of the expected position of the external auditory canal. Skin and subcutaneous tissue are reflected until the periost was seen. Then the periost is incised and bone surface is exposed. The implants placed are inserted at the sites that were marked with surgical pen parallel to each other under minimum trauma to prevent heat injury to the surrounding bone and to ensure a stable osseointegration. (Sencimen et al., 2008) 18

19. After forming the initial pilot hole, a round-tipped probe should be used to check the bottom of the drill hole for bone-like hardness. Once it is verified that the hole does not extend to the inside of the cranium, the width of the hole could be increased. Once the final drilling is completed, the bottom of the hole should be checked with a probe once again.  19 Implantation surgery: Primary surgery

20. Implant Fenestration Surgery :Secondary Surgery The secondary surgery for implant fenestration is performed three to four months after the initial surgery. The cover screw is exposed, and the healing abutment is attached . 20

21. Prosthetic procedure At the end of the recommended period of 3-4 months for osteointegration, the recovery screws are removed and titanium bone graft retentive anchors or bars are placed. 21 loosening of abutment loosening of prosthetic bar screws broken bar or extensions broken or lost clips loss of clip retention Loss of magnet retention fractured acrylic resin substructure loss of bonding between substructure and silicone deposits on tissue surface of the prosthesis tear or rupture of the prosthesis Complications

22. 22 Conclusion Osseointegrated titanium implants may provide patients with a safe and reliable method for anchoring auricular prostheses that enables restoration of their normal appearance and offer an improvement in their quality of life. The use of osseointegrated prostheses should be considered to be a simple and viable alternative to surgical reconstruction and as a gold standard in the management of individuals with massive auricular defects.

23. Multimaterial 3D printing of a de fi nitive silicone auricular prosthesis: An improved technique (J Prosthet Dent 2020) 2

24. Additive manufacturing continuously advances the field of maxillofacial rehabilitation. In the past decade, various additive manufacturing approaches have been described to produce facial prostheses, either directly or indirectly. Since early 2010, the additive manufacturing of silicone structures has become possible. Clinical trials have demonstrated the direct silicone printing of a custom nasal prosthesis, which, however, was considered as an interim solution because of poor marginal adaptation. Recently printable rubber-like flexible materials have enabled the manufacturing of a nasal prosthesis and an ear model. However, these materials are not genuine silicones, and their biocompatibility has not been established. 24 Introduction

25. TECHNIQUE 1. Scan the patient with a stationery 3D photogrammetry system to obtain an image of the whole face; then, with an intraoral scanner (IOS) (TRIOS; 3Shape), render the anatomy of the intact ear and capture the position of the retention magnets (X-line and T-line; steco-systemtechnik GmbH & Co KG) on the defect side. Implant position transfer with intraoral scanner. A, Virtual image of 2 X-line and 1 T-line ( steco -system- technik GmbH & Co KG) abutments obtained by intraoral scanner. B, Matching of corresponding abutments in STL fi le format with their scans. C, STL fi les of prosthesis magnets put in presaved position on top of corresponding abutment. STL, standard tessellation language.

26. 26 A, Extensive 3D image consisting of matched facial scan obtained by 3D photogrammetry, scans of intact ear and defect obtained by IOS; aligned IOS scan of intact ear mirrored on defect side and adjusted for shape and position. B, C, Virtual design of prosthesis bulk and retention bar inside; tissue fi tting surface adjusted by subtracting face scan from prosthesis design with Boolean-out function. IOS, intraoral scanner.

27. 27 A, Virtual design of retention bar and negative form over it for further manufacturing process. B, Printed cast with prosthesis magnets put on top of abutments and printed negative form for formation process. C, Retention bar in negative mold, manufactured from autopolymerizing resin.

28. 28 De fi nitive design of auricular prosthesis divided into 3 parts. A, Concha (blue e 40 A Shore) and lobe (green e 20 A Shore). B, Bulk ( lila e 60 A Shore hardness).

29. 29 A, Directly printed silicone prosthesis without postprocessing. B, Ground with polishing paper. C, Sealed with conventional silicone material only on areas not reached by polishing instrument. D, Individualized by extrinsic coloring and with aligned frontal margin.

30. 30 Printed and individualized silicone prosthesis on printed cast of defect for further adjustment of frontal margin by adding conventional silicone material. The fi nished prosthesis had adequate marginal adaptation and fi tted well to the patient ’ s facial anatomy. The patient was satis fi ed with the soft ear lobe, as she had had the same feature on her previous conventionally fabricated prosthesis. The patient was pleased with the treatment outcome in terms of general esthetics and appreciated that the prosthesis design was copied from her intact ear. The patient also liked the color in general but requested more yellow in the painting scheme.

31. 31 A, Intact ear. B, Individualized and adjusted printed silicone prosthesis with acceptable marginal adaptation

32. 32

33. 33 The virtual design and integration of retention elements has become possible since the manufacturers provided the STL fi les of their products (abutments, magnets, copings) with a proper virtual orientation. In the present example, an IOS was used to capture the implant position and to scan the intact ear anatomy with numerous undercuts. The prosthesis magnets fi tted well on the implants, but this was not challenging because of the plain geometry of the X-line magnets. Although the constructed prosthesis was considered de fi nitive, the esthetic outcome was poorer than that of conventional processing. The printed prosthesis was devoid of skin structure, which was impossible to apply because of the limited printing resolution. The grinding with abrasive paper did not alter the prosthesis shape but made the surface even smoother. As the present technique did not use a clinical evaluation appointment, a functional impression to re fl ect facial mimics was not performed. Furthermore, as multicolor printing in a medical-grade silicone is not feasible, no intrinsic coloring could be applied, which compromised the esthetics. However, because of the mirror-imaging technique, a digital work fl ow allows for an excellent size, shape, and position match of the prosthesis to the contralateral side. Discussion

34. The outcome of auricular defect rehabilitation by means of a directly printed silicone prosthesis in various Shore hardness grades is presented. The application of additional silicone on the prosthesis frontal ridge helped achieve a more precise marginal fit and a smooth transition to the adjacent tissues. The virtual integration of retention elements on the CAD stage aided a more predictable rehabilitation outcome and is the next step on the way to a fully digital workflow. Further technical advancements in the printing hardware are needed to enable multicolor printing with greater resolution in order to minimize the number of analog steps . Summary

35. Prosthetic rehabilitation of unilateral congenital microtia with an implant-retained auricular prosthesis – a case report Journal of the Irish Dental Association | Feb/March 2022: Vol 68 (1) 3

36. Case report 36 A 24-year-old male with unilateral microtia of the left ear presented to the Dublin Dental University Hospital with an existing implant-retained auricular prosthesis. The patient was unhappy with this prosthesis, as it had become poorly retentive, noticeably discoloured , and displayed poor adaptation to the underlying tissues. The patient had undergone surgery 14 years previously for removal of auricular remnants at the defect site and placement of two craniofacial implants in the temporal bone.

37. 37 His current auricular prosthesis was fabricated in the immediate aftermath of this surgical procedure.

38. Removal of the prosthesis revealed a cast gold dolder bar screwed to two standard abutments splinting the implant fixtures. Two gold rider clips were set in an acrylic sleeve embedded in the silicone prosthesis as the interface between the prosthesis and the implant bar. On removal of the gold bar, granular tissue and erythema of the peri-implant soft tissues was evident, particularly surrounding the superior implant abutment 38

39. The superior abutment displayed some mobility and, on removal, it was noted that the abutment was not fully seated on the implant fixture. The stability of both implant fixtures was assessed, and no movement was evident. Both abutments were reattached, ensuring that they were fully seated on their respective implants. When reattaching the implant bar, the single screw test was employed to assess its passivity of fit on the implant abutments and revealed a misfit of the superstructure. The mobility displayed by the superior implant abutment was attributed to torque generated by the ill-fitting bar. 39 The single screw test revealed that the cast gold bar was not seating passively on the implant abutments.

40. Clinical and laboratory procedures With the patient sitting in an upright position and looking directly ahead, transfer of following landmarks from the unaffected ear to the corresponding location on the defect side: the superior margin of the tragus; the junction of the lobe with the side of the face; the junction of the anterior aspect of the helix with the side of the face; and, a line indicating the vertical angulation of the ear 40

41. Two open tray impression copings were splinted with resin to stabilise them within the impression before a polyether impression material was applied over the defect site. 41 A layer of thick gauze was then adapted over the polyether material before it set to provide retention for an impression plaster backing, added to support the impression and minimise distortion. An alginate impression of the contralateral ear was also made for reference when carving the prosthetic pattern in wax.

42. With the aid of the orientation marks and the stone cast of the contralateral ear, a model of the left ear was shaped in modelling wax. 42

43. 3D scans of the implant model and wax pattern were made , and CAD software was used to design a fixture-level implant bar to fit within the confines of the wax pattern, with 3mm clearance from the skin surface. CAD/CAM technology made it possible to cantilever the bar from the inferior implant so that the retentive clips could be ideally positioned beneath the antihelix of the prosthesis, providing maximum stability and resistance to dislodgement. 43

44. The finalised digital design was manufactured in titanium using computer numerical control (CNC) milling technology. 44 3D scans of the implant model and wax pattern were obtained and CAD/CAM technology was used to produce a milled titanium superstructure

45. The milled titanium bar was assessed for fit on the master cast before three gold rider clips were fixed to the bar and a clear acrylic housing to retain the clips was processed in self-cure acrylic resin. 45 The wax pattern was then modified to incorporate the acrylic clip assembly

46. The new titanium bar and wax pattern were tried on the patient and assessed for shape, orientation and fit. 46

47. Required adjustments to the wax pattern were made chair side before it was invested in a three-part mould with type III dental stone. 47

48. At the next clinical appointment, a two-part vinyl addition silicone was mixed on a glass pallet with intrinsic pigments and coloured flocking to produce multiple coloured swatches, replicating the skin tones of the surrounding tissues and the patient’s unaffected ear. 48

49. A thin coat of primer was applied to the outer surface of the acrylic clip assembly before the various silicone swatches were packed into their respective positions within the mould and cured in an oven to the manufacturer’s specifications. 49 The cured silicone prosthesis was processed to incorporate the acrylic clip assembly.

50. 50 The prosthesis was tried on the patient to assess the fit before excess silicone was trimmed from the edges as appropriate. Extrinsic stains were applied and sealed with a silicone sealant.

51. Discussion During the treatment planning process, a number of options were considered for the rehabilitation of this case. Fabrication of a new auricular prosthesis to attach to the existing implant bar was ruled out once it was determined that the cast gold bar did not seat passively on the implant abutments. Dispensing of the bar and clip interface in favour of magnetic connections was also considered. It is reported, however, that bar-clip attachment provides better retention than magnetic systems for auricular prostheses. In addition, placement of three implants in a non-linear alignment is recommended to achieve optimum retention for magnetically retained auricular prostheses, whereas two implants are considered sufficient for bar-clip retention systems. 51

52. Considering the patient’s age, active lifestyle and the presence of only two craniofacial implants, it was decided that the most appropriate available treatment option was the fabrication of a new, passively fitting implant bar to retain, support and stabilise a new silicone auricular prosthesis. CAD/CAM fabrication technologies were employed in the design and manufacture of the new implant bar as they are less labour intensive and allow for more versatility in relation to the bar design when compared with traditional casting techniques. 52

53. 53 Conclusion CAD/CAM technology is now routinely used in the fabrication of dental restorations;however , there is a gap in the literature regarding the use of milled titanium substructures for use with implant-retained maxillofacial prostheses. Further technical advancements in the printing hardware are needed to enable a multicolor printing with greater resolution in order to minimize the number of analog steps.

54. References Meryem Gu¨ lce Subas¸ı , Gamze Alnıac¸ık , Abdullah Kalaycı , Serhan Akman , Ercan Durmus ; J Indian Prosthodont Soc (Dec 2014) 14(Suppl. 1):S196–S201 Auricular Osseointegrated Implant Treatment: Basic Technique and Application of Computer Technology; Appl. Sci. 2020, 10, 4922; doi:10.3390/app10144922 Multimaterial 3D printing of a definitive silicone auricular prosthesis: An improved technique ; J Prosthet Dent 2020 Prosthetic rehabilitation of unilateral congenital microtia with an implant-retained auricular prosthesis – a case report ; Journal of the Irish Dental Association | Feb/March 2022: Vol 68 (1)