Accuracy of implant placement using CAD-CAM tooth-supported surgical guides for an auricular prosthesis in vitro

PURPOSE

To evaluate the accuracy of tooth-supported surgical guides used to place implants in auricular prostheses. The accuracy (trueness and precision) of the implant positions was evaluated, and the difference between the surgical guide with and without retention of the external auditory canal (EAC) was compared.

MATERIALS AND METHODS

This study simulated implant placement in vitro for the treatment of right auricle malformation. Surgical guides and other casts were fabricated using additive manufacturing technology. The casts were divided into 2 groups according to the surgical guide, with 10 bone blocks in each group (with or without the EAC plug (Guides 1 and 2)). Three implant positions (Implants 1-3) were prepared for each bone block using surgical guides. Implant positions were registered using light-body silicone impressions combined with optical surface scans to measure the coronal, apical, depth, and angular deviations. Four deviations of trueness and precision were reported as the mean ± standard deviation, which was analyzed by Student's t-test.

RESULTS

Each group of 10 bone blocks with 30 implant positions was successfully prepared and digitally reproduced as implants. The accuracies of implant position with surgical guides were acceptable when compared with the preoperatively planned implant positions. Compared with the Guide 2 group, there was a significant difference in the apical, depth, and angular deviations of Guide 1 group in terms of precision (p = 0.001). There was a significant difference in the depth deviation of Implant 1 (p = 0.028) and apical deviation of Implant 2 (p < 0.001) compared two groups in terms of trueness. In terms of precision, there was a significant difference in the coronal (p = 0.002), apical (p = 0.001), and depth (p < 0.001) deviation of Implant 1; apical (p = 0.036) and angular (p < 0.001) deviation of Implant 2 also existed significant difference; the coronal deviation of Implant 3 (p = 0.018) also existed significant difference. Moreover, the group with the EAC plug showed lower deviation in precision and a smaller volume in the 95% confidence ellipsoid.

CONCLUSION

Both types of tooth-supported surgical guides can provide acceptable accuracy. A surgical guide with an EAC plug was considered to be more precise.

Applications of CAD/CAM Technology for Craniofacial Implants Placement and Manufacturing of Auricular Prostheses-Systematic Review

This systematic review was aimed at gathering the clinical and technical applications of CAD/CAM technology for craniofacial implant placement and processing of auricular prostheses based on clinical cases. According to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines, an electronic data search was performed. Human clinical studies utilizing digital planning, designing, and printing systems for craniofacial implant placement and processing of auricular prostheses for prosthetic rehabilitation of auricular defects were included. Following a data search, a total of 36 clinical human studies were included, which were digitally planned and executed through various virtual software to rehabilitate auricular defects. Preoperative data were collected mainly through computed tomography scans (CT scans) (55 cases); meanwhile, the most common laser scanners were the 3dMDface System (3dMD LLC, Atlanta, Georgia, USA) (6 cases) and the 3 Shape scanner (3 Shape, Copenhagen, Denmark) (6 cases). The most common digital design software are Mimics Software (Mimics Innovation Suite, Materialize, Leuven, Belgium) (18 cases), Freeform software (Freeform, NC, USA) (13 cases), and 3 Shape software (3 Shape, Copenhagen, Denmark) (12 cases). Surgical templates were designed and utilized in 35 cases to place 88 craniofacial implants in auricular defect areas. The most common craniofacial implants were Vistafix craniofacial implants (Entific Medical Systems, Goteborg, Sweden) in 22 cases. A surgical navigation system was used to place 20 craniofacial implants in the mastoid bone. Digital applications of CAD/CAM technology include, but are not limited to, study models, mirrored replicas of intact ears, molds, retentive attachments, customized implants, substructures, and silicone prostheses. The included studies demonstrated a predictable clinical outcome, reduced the patient's visits, and completed the prosthetic rehabilitation in reasonable time and at reasonable cost. However, equipment costs and trained technical staff were highlighted as possible limitations to the use of CAD/CAM systems.

Effect of cut-out rescan procedures on the accuracy of an intraoral scanner used for digitizing an ear model: An in vitro study

PURPOSE

The purpose of this study was to evaluate the impact of the rescanning of mesh holes of different diameters on the accuracy of an intraoral scanner (IOS) used to digitize an ear model.

MATERIALS AND METHODS

An ear model was digitized using an intraoral scanner (Medit i500) to obtain a reference mesh. A baseline experimental scan was created by editing a duplicate of the reference mesh using the cut-out tool of the IOS software. Three equal groups were created based on the diameter of the cut-out areas: 2-mm (G1), 5mm (G2), and 8-mm (G3) (n = 15). The cut-out areas were rescanned and a total of 45 digital files were exported. The discrepancy between the reference and the experimental digital scans was measured using the root mean square calculation (RMS). The data were analyzed by a Kruskal-Wallis test followed by a post hoc Dunn's test with Bonferroni correction.

RESULTS

The trueness values ranged from 19.53 to 27.13 μm. There were significant differences in the RMS error values among the groups tested (p<.001) and post hoc multiple comparisons showed significant differences between the G1 and G2 groups (p = .04), G1 and G3 groups (p<.001), and G2 and G3 groups (p = .004). Overall, the precision values ranged from 4.93 to 7.73 μm and significant differences in the RMS values were only found between the G1 and G2 groups (p = .014).

CONCLUSIONS

Mesh hole rescanning affected the scanning accuracy (trueness and precision) of the IOS tested. The larger the diameter of the mesh holes, the less the trueness of the IOS tested. The precision values seemed to be less affected compared with the trueness by the cut-out and rescanning procedures. This article is protected by copyright. All rights reserved.

Osseointegrated implant-retained auricular prosthesis constructed using cone-beam computed tomography and a prosthetically driven digital workflow: a case report

Prosthetically driven workflows using CBCT, digital optical scanning, 3D-printed molds and frameworks, and dental implant component attachments to osseointegrated fixtures can produce anatomically accurate, esthetic, durable silicone ear replacements.

Digital surgical planning and placement of osseointegrated implants to retain an auricular prosthesis using implant software with cone-beam computed tomography and 3D-printed surgical guides: A case report

Integration of CBCT imaging with dental implant treatment planning software and 3D-printed surgical guides can facilitate surgical planning for extraoral implant placement. In the current case, this combined planning strategy enabled navigation of challenging osseous anatomy, avoided critical structures, and optimized osseointegration for prosthesis retention.

Osseointegrated implants for auricular prostheses: An alternative to autologous repair

OBJECTIVES/HYPOTHESIS

This study compares the hospital cost of osseointegrated implants for retention of an auricular prosthesis to autologous ear reconstruction.

STUDY DESIGN

Retrospective review.

METHODS

This study includes patients who underwent reconstruction for either congenital or acquired ear defects at Duke University Medical Center during 2009 to 2015.

RESULTS

A total of nine patients had autologous repair representing nine operative ears, and 16 patients had an osseointegrated implant representing 18 operative ears (two bilateral). The average age for the autologous repair was 11.6 years with 56% male versus 40.7 years with 56% male for the osseointegrated implant patients. For autologous patients, indications for surgery were anotia/microtia in 8/9 (89%) and trauma in 1/9 (11%) versus 6/16 (387.5%) anotia/microtia, 8/16 (50%) cancer, and 2/16 (132.5%) trauma in the osseointegrated implant group. The mean number of surgeries was 3.1 for autologous repairs and 1.0 for osseointegrated repairs (mean difference confidence interval [CI]: -2.4 to -1.8, P < .001). The average cost to the hospital for an osseointegrated repair was $6,491.39 versus $10,047.93 for autologous repairs (CI: $6,496.38 to $-616.68, P = .02) CONCLUSIONS: Osseointegrated implants for retaining an auricular prosthesis has a similar cost to autologous repair of ear defects, but patients underwent an average of two more surgeries with autologous repair. Patients should be able to choose the reconstruction option that best suits their condition and preferences.

LEVEL OF EVIDENCE

4. Laryngoscope, 128:2153-2156, 2018.

Identifying position, visibility, dimensions, and angulation of the ear

We selected 254 subjects between the ages of 18 and 30 yr to assess the ear position, angulations of the ear in relation to the nose, visibility from the frontal view, and dimensions of the ear by using various anthropometric points of the face. Subjects were divided into four groups based on facial form. A reference plane indicator, facial topographical measurements, metal ruler, and digital photography were used. While considering the position of the ear, in all facial forms except square tapering, the most samples showed a tendency for the subaurale being in line with subnasale. Regression analysis showed a tendency to gnathion distance is the most dependent variable with length of the ear kept as a constant predictor, while both interalar distance and exocanthion to endocanthion distance correlate highly significantly to the width of the ear. In all subjects, the visibility of the ear when viewed from the front was an average of 1.5 mm. Regardless of facial form, ear angulation was generally less than nose angulation.

Prosthetic rehabilitation of auricular defect: a clinical report

BACKGROUND

The absence of external ear may be due to congenital, traumatic, or surgical causes. Many case reports only describe impression techniques to record details of the defect side and the natural ear. The purpose of this case report is to explain in detail simple clinical and laboratory procedures involved in fabrication of ear prosthesis.

CASE DESCRIPTION AND METHODS

The use of three-part mold helps in the application of pigmented silicone in specific areas. The use of direct adhesive fixation provides the best esthetic result and if properly used the most satisfactory form of treatment.

FINDINGS AND OUTCOMES

The patient was satisfied with the life-like appearance of the prosthesis. The use of direct adhesive fixation gave the patient a sense of security and improved his confidence.

CONCLUSION

The technique described is economical, and additional steps of implant placement are avoided. The esthetics of the prosthesis made by hand carved clay pattern provides good details.

CLINICAL RELEVANCE

The technique describes the method of direct adhesive fixation of the prosthesis giving it a life-like appearance. The confidence of the patient is also restored.