A comparative evaluation of photogrammetry software programs and conventional impression techniques for the fabrication of nasal maxillofacial prostheses.

STATEMENT OF PROBLEM: The fabrication of facial prostheses is complicated and time-consuming because of the need for accurate impressions of the facial defects and surrounding tissues. Inaccuracies can arise from soft-tissue compression, involuntary patient movements, and insufficient support for the impression material. Various 3-dimensional (3D) imaging and scanning techniques, including photogrammetry, have been introduced, but their accuracy remains insufficiently evaluated. PURPOSE: The purpose of this in vitro study was to evaluate and compare the accuracy of 3D digital casts generated by 4 photogrammetry software programs (Agisoft Metashape, 3DF Zephyr, Meshroom, and Polycam) and casts from 2 conventional impression materials (alginate and polyvinyl siloxane [PVS]) for the fabrication of nasal maxillofacial prostheses. MATERIAL AND METHODS: A stone cast of a patient's nose was used as the basis for generating a reference digital 3D cast and another 54 test 3D casts. The reference cast was created by scanning the stone cast using a FARO Optor Lab 3D scanner. The 54 test 3D casts were generated and divided into 6 test groups as follows: Agisoft group: 9 3D casts generated using Agisoft Metashape, a commercial personal computer (PC) software program; 3DF Zephyr group: 9 3D casts generated using 3DF Zephyr, a commercial PC software program; Meshroom group: 9 3D casts generated using Meshroom, a free PC software program; Polycam group: 9 3D casts generated using the Polycam, a commercial Android cloud application; PVS group: 9 3D casts generated indirectly by 3D scanning a gypsum cast made from a polyvinyl siloxane (PVS) impression of the stone nose cast; and Alginate group: 9 3D casts generated indirectly by scanning a master cast made using alginate impressions of the stone nose cast. Deviation measurements of the produced specimens were analyzed using the Geomagic Control X software program, and statistical comparisons were performed employing the Kruskal-Wallis test (α=.05). RESULTS: The results showed that the 3DF Zephyr group had the smallest deviation measurements (median: 0.057 mm ±0.012) among the 4 photogrammetry software programs, while the alginate impression group had the largest deviations (median: 0.151 mm ±0.094) of the 2 conventional impression materials. Significant differences were observed among the 4 photogrammetry software programs and the 2 conventional impression materials (H=39.41, df=5, P<.001). The casts generated by Agisoft Metashape were significantly more accurate than those produced by Meshroom, Polycam or the conventional impression materials (P=.024, P=.045, P<.001, respectively). The casts produced by 3DF Zephyr were significantly more precise than those created by Meshroom and the conventional impression materials (P=.037, P<.001, respectively). No significant differences were observed between the Agisoft Metashape and 3DF Zephyr groups (P>.05). CONCLUSIONS: Photogrammetry software programs, specifically Agisoft Metashape and 3DF Zephyr, demonstrated better accuracy than conventional impression materials in creating nasal digital casts. Photogrammetry has the potential to improve workflow and reduce patient discomfort during the fabrication of maxillofacial prostheses. Further research is needed to validate these findings in clinical settings.

Designing Of Occlusal Appliance Digital Protocol Using An Open Source 3D Modelling Software Program: a Technical Report.

Occlusal splint is a commonly prescribed dental appliance in the dental office for the management of bruxism or temporomandibular disorder. The use of digital dental technology facilitates fabrication of this therapeutic device. The digital technology improvement had helped in designing and producing occlusal splints that show better precision and accuracy, ease of manufacturing in terms of time-consuming and materials, in addition to the option of simple and straightforward duplication process. This technical report describes the digital workflow steps that need to be followed to design an occlusal device in a fully digital protocol. Maxillary and mandibular models' scans were acquired in centric relation, and a virtual 3D occlusal device was designed using a free, open-source 3D modelling software program.

First steps of a digital workflow to build up a virtual articulator using open-source Autodesk Meshmixer software.

Virtual planning has become part and parcel of digital dentistry to ensure more precise planning, better treatment outcomes, and more effective communication between dental practitioners, dental technicians, and patients. In dentistry, CAD software programs are one way to achieve virtual treatment planning. Among the most crucial and critical steps in treatment planning and execution are virtual articulation and occlusal analysis of the maxillary and mandibular arches. These steps have a great influence on the success of the final outcome. The present article proposes a detailed method for constructing a novel virtual articulator that can also be used for educational purposes to enable occlusal analysis and adjustment for a virtual tooth mock-up by simulating a virtual dynamic occlusion through the use of open-source Autodesk Meshmixer software.

Does HIV infection affect the survival of dental implants? A systematic review and meta-analysis.

STATEMENT OF PROBLEM: Immunosuppression and coinfections associated with human immunodeficiency virus (HIV) infection pose a relative contraindication for dental implant therapy. However, although implants have been placed in patients with HIV with reasonable success, how HIV infection affects their survival is unclear. PURPOSE: The purpose of this systematic review of the literature and meta-analysis was to analyze the data on the survival of dental implants in patients with HIV. MATERIAL AND METHODS: A search for relevant articles published up to November 2019 was performed in PubMed/Medline and Cochrane databases, Clinicaltrials.gov, and Google Scholar. Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were adopted for the conduct of the systematic review. The most pertinent data were extracted and pooled for qualitative and quantitative analyses with 95% confidence intervals. Heterogeneity was analyzed by using I-squared statistics. RESULTS: A total of 8 studies involving 411 individuals with HIV and 1109 implants were included in the meta-analysis. The mean follow-up period was 2.8 years. A pooled estimate of 95% of implant survival rate with 95% confidence interval(92% to 96%) was noted. Heterogeneity across the 8 studies was found to be 41% with moderate true variability. CONCLUSIONS: This systematic review demonstrated that HIV infection does not pose a serious threat to implant survival on short-term evaluation, but the evidence is of low quality.

Digital workflow for articulating maxillary and mandibular 3D arch models using an open source 3D modeling software program.

Virtual planning in digital dentistry enables easier communication between technicians, clinicians, and patients, and faster performance. Dental computer-aided design (CAD) software programs have been used for this purpose. One of the most crucial steps in virtual planning is mounting and articulating the maxillary and mandibular arch 3D models to simulate and evaluate the occlusion as a part of the virtual mock-up. The aim of this article was to describe a more cost-effective digital technique utilizing a scanned interocclusal record for articulating the cast models virtually. For this purpose, the open source Autodesk Meshmixer software program was used.

A new approach for better anterior esthetic using platelet-rich fibrin as sole graft material combined with ovate design dental bridge.

Alveolar ridge deficiency is considered a major esthetic limitation, especially in the maxillary anterior region. Several approaches have been developed to enhance and increase the soft-tissue volume. Among those approaches are connective tissue grafts, platelet-rich fibrin (PRF) membrane and implying the guided bone regeneration concept. The PRF grafting technique was employed in this clinical case to improve and enhance the anterior esthetic without the need for the bone graft and augmentation. This article describes the use of PRF as a sole grafting material for both socket and soft-tissue augmentation for a 23-year-old male, who had an accident 8 years ago while he was playing a basketball, which caused his upper front teeth to be intruded and discolored. The upper left central tooth suffered a major external root resorption; hence, it was extracted. PRF was prepared and packed in and extruded out of the socket. This was combined with ovate design provisional bridge. Ten days, 1 month, 3 months, and 6 months postoperative review showed a significantly well-progressed healing. According to the encouraging result obtained in this clinical case in regard to tissue healing and esthetic, the PRF can be a potential sole graft material for small anterior deficient areas. This may reduce the need of bone augmentation and graft in such selected cases.

Virtual Treatment Planning for Implant-Retained Nasal Prosthesis: A Clinical Report.

Osseointegrated craniofacial implants have improved retention and patients' perceptions of implant-retained nasal prostheses; however, the determination of the available bone sites for implant placement post-rhinectomy is difficult. This case report describes the use of cone beam computed tomography scanning and computer-assisted virtual planning in conjunction with digital photographs for rehabilitation of a facial defect with an implant-retained silicon nasal prosthesis. Two implants were planned in the anatomical area with adequate bone volume to achieve favorable cosmetic outcomes and accessibility for hygiene maintenance. The implant-retained nasal prosthesis resulted in a meaningful improvement in the esthetics without the need for plastic surgery. In such cases, the post-rhinectomy reconstruction surgery should be limited to preparation of the surgical defect area for an implant-retained prosthesis. Silicone prostheses are reliable alternatives to surgery and should be considered in selected cases.

Passive Fit in Screw Retained Multi-unit Implant Prosthesis Understanding and Achieving: A Review of the Literature.

One of the considerable challenges for screw-retained multi-unit implant prosthesis is achieving a passive fit of the prosthesis' superstructure to the implants. This passive fit is supposed to be one of the most vital requirements for the maintenance of the osseointegration. On the other hand, the misfit of the implant supported superstructure may lead to unfavourable complications, which can be mechanical or biological in nature. The manifestations of these complications may range from fracture of various components in the implant system, pain, marginal bone loss, and even loss of osseointegration. Thus, minimizing the misfit and optimizing the passive fit should be a prerequisite for implant survival and success. The purpose of this article is to present and summarize some aspects of the passive fit achieving and improving methods. The literature review was performed through Science Direct, Pubmed, and Google database. They were searched in English using the following combinations of keywords: passive fit, implant misfit and framework misfit. Articles were selected on the basis of whether they had sufficient information related to framework misfit's related factors, passive fit and its achievement techniques, marginal bone changes relation with the misfit, implant impression techniques and splinting concept. The related references were selected in order to emphasize the importance of the passive fit achievement and the misfit minimizing. Despite the fact that the literature presents considerable information regarding the framework's misfit, there was not consistency in literature on a specified number or even a range to be the acceptable level of misfit. On the other hand, a review of the literature revealed that the complete passive fit still remains a tricky goal to be achieved by the prosthodontist.

A simple procedure for retrieval of a cement-retained implant-supported crown: a case report.

Retrieval of cement-retained implant prostheses can be more demanding than retrieval of screw-retained prostheses. This case report describes a simple and predictable procedure to locate the abutment screw access openings of cementretained implant-supported crowns in cases of fractured ceramic veneer. A conventional periapical radiography image was captured using a digital camera, transferred to a computer, and manipulated using Microsoft Word document software to estimate the location of the abutment screw access.