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.

Does the use of platelet-rich plasma in sinus augmentation improve the survival of dental implants? A systematic review and meta-analysis.

Background: Platelet-rich plasma is considered an effective modality to promote bone regeneration, improve hard and soft tissue healing in surgical procedures including sinus augmentation. However, the survival of dental implants in sinus augmented sites with platelet-rich plasma has shown equivocal results in recent studies. Purpose: In this systematic review, data on dental implants' survival in sinus augmentation sites with platelet-rich plasma were examined. Materials and methods: Randomized controlled trials on the topic with a minimum mean follow-up of 6 months with no language restriction were considered. Other study designs on the topic were excluded. Accordingly, relevant articles were searched in Clinicaltrials.gov, Cochrane databases, PubMed/Medline, and Scopus up to April 2021. Using the Cochrane risk of bias assessment tool, the listed studies' risk of bias was evaluated. From the included studies, the pertinent information was taken and pooled for qualitative and quantitative analysis using R software 4.1.1. Results: Six randomized controlled trials involving 188 patients who underwent sinus augmentation with and without platelet-rich plasma, and 781 implants were included for qualitative and quantitative analysis. Four hundred and eleven implants were placed in the intervention group (with platelet-rich plasma) and 370 implants were placed in the control group (without platelet-rich plasma). The pooled estimate (OR 0.84, 95% CI 0.37 to 1.91; I2 = 0%) indicated that there was no statistically significant difference observed between the groups. The test for subgroup differences showed no statistically significant differences between the subgroups (p = 0.45) with no heterogeneity (I2 = 0%). Conclusion: The bias associated with selective reporting of outcome data was considered as some concern for bias. This systematic review revealed that the effect of platelet-rich plasma is uncertain on the survival of dental implants.

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.

Do Highly Active Antiretroviral Therapy Drugs in the Management of HIV Patients Influence Success of Dental Implants?

HIV infection is a global pandemic that affects CD4 cells in the immune system and leads to lethal opportunistic infections. The advent of highly active antiretroviral therapy (HAART) has induced a marked reduction in the viral load and an increase in the CD4 cell count, thereby changing the course of the disease from an acute life-threatening condition to chronic disease. Accordingly, need and demand for oral rehabilitation in HIV positive population have increased in recent years. However, few drugs used in the HAART regimen have also known to be associated with osteopenia and osteoporosis. Although HAART reduces the morbidity in HIV patients, it remains unknown to what extent the therapy influences the implant healing. Few scientific literatures have identified osteoporosis and HIV infection as an unconducive milieu for dental implant placement and survival but demonstrated favorable outcomes in short-term assessments. The long-term impact of bone metabolic effects of HAART on implant success remains a conundrum.

Deviation of dental implants placed using a novel 3D-printed surgical guide: An in vitro study.

BACKGROUND: There is very little literature available on the reliability of the rapid prototyping technology in the production of three-dimension (3D)-printed surgical guides for accurate implant placement. OBJECTIVES: The aim of the study was to evaluate the deviation of implant placement performed with a surgical guide fabricated by means of the rapid prototyping technique (the PolyJet™ technology). MATERIAL AND METHODS: Twenty sheep mandibles were used in the study. Pre-surgical cone-beam computed tomography (CBCT) scans were acquired for the mandibles by using the Kodak 9000 3D cone-beam system. Two implants with dimensions of 4 mm in diameter and 10 mm in length were virtually planned on the 3D models of each mandible by using the Mimics software, v. 16.0. Twenty surgical guides were designed and printed using the PolyJet technology. A total of 40 implants were placed using the surgical guides, 1 on each side of the mandible (2 implants per mandible). The post-surgical CBCT scans of the mandibles were performed and superimposed on the pre-surgical CBCT scans. The amount of deviation between the virtually planned placement and the actual implant placement was measured, and a descriptive analysis was done. RESULTS: The results showed that the mean deviation at the implant coronal position was 1.82 ±0.74 mm, the mean deviation at the implant apex was 1.54 ±0.88 mm, the mean depth deviation was 0.44 ±0.32 mm, and the mean angular deviation was 3.01 ±1.98°. CONCLUSIONS: The deviation of dental implant placement performed with a 3D-printed surgical guide (the PolyJet technology) is within the acceptable 2-millimeter limit reported in the literature.

Accuracy of a new elastomeric impression material for complete-arch dental implant impressions.

AIM: The aim of the present study was to assess the accuracy of multi-unit dental implant casts obtained from two elastomeric impression materials, vinyl polyether silicone (VPES) and polyether (PE), and to test the effect of splinting of impression copings on the accuracy of implant casts. METHODS: Forty direct impressions of a mandibular reference model fitted with six dental implants and multibase abutments were made using VPES and PE, and implant casts were poured (N = 20). The VPES and PE groups were split into four subgroups of five each, based on splinting type: (a) no splinting; (b) bite registration polyether; (c) bite registration addition silicone; and (d) autopolymerizing acrylic resin. The accuracy of implant-abutment replica positions was calculated on the experimental casts, in terms of interimplant distances in the x, y, and z-axes, using a coordinate measuring machine; values were compared with those measured on the reference model. Data were analyzed using non-parametrical Kruskal-Wallis and Mann-Whitney tests at α = .05. RESULTS: The differences between the two impression materials, VPES and PE, regardless of splinting type, were not statistically significant (P>.05). Non-splinting and splinting groups were also not significantly different for both PE and VPES (P>.05). CONCLUSIONS: The accuracy of VPES impression material seemed comparable with PE for multi-implant abutment-level impressions. Splinting had no effect on the accuracy of implant impressions.

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.

Ocular Defect Rehabilitation Using Photography and Digital Imaging: A Clinical Report.

Ocular disorders occasionally necessitate surgical intervention that may lead to eye defects. The primary objective in restoring and rehabilitating such defects with an ocular prosthesis is to enable patients to cope better with associated psychological stress and to return to their accustomed lifestyle. A series of detailed steps for custom-made ocular prosthesis fabrication using the advantages of digital photography to replace the conventional oil paint and monopoly iris painting technique are presented in this article. In the present case, a digital photograph of the patient's iris was captured using a digital camera and manipulated on a computer using graphic software to produce a replica of the natural iris. The described technique reduces treatment time, increases simplicity, and permits the patient's natural iris to be replicated without the need for iris painting and special artistic skills.

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.

Prosthetic management of mid-facial defect with magnet-retained silicone prosthesis.

BACKGROUND AND AIM: Mid-facial defect is one of the most disfiguring and impairing defects. A design of prosthesis that is aesthetic and stable can be precious to a patient who has lost part of his face due to surgical excision. Prosthesis can restore the patients' self-esteem and confidence, which affects the patients and their life style. The aim of this case report is to describe a technique of mid-facial silicone prosthesis fabrication. TECHNIQUE: To provide an aesthetic and stable facial prosthesis, the extra-oral prosthesis was fabricated using silicone material, while the intra-oral defect was restored with obturator prosthesis, and then both prostheses were connected and attached to each other using magnets. DISCUSSION: This clinical report describes the rehabilitation of a large mid-facial defect with a two-piece prosthesis. The silicone facial prosthesis was made hollow and lighter by using an acrylic framework. Two acrylic channels were included within the facial prosthesis to provide the patient with clean and patent airways. CLINICAL RELEVANCE: A sectional mid-facial prosthesis was made and retained in place by using magnets, which resulted in a significant improvement in the aesthetical and functional outcome without the need for plastic surgery. Silicone prostheses are reliable alternatives to surgery and should be considered in selected cases.

Evaluation of accuracy of complete-arch multiple-unit abutment-level dental implant impressions using different impression and splinting materials.

PURPOSE: This in vitro study evaluated the accuracy of multiple-unit dental implant casts obtained from splinted or nonsplinted direct impression techniques using various splinting materials by comparing the casts to the reference models. The effect of two different impression materials on the accuracy of the implant casts was also evaluated for abutment-level impressions. MATERIALS AND METHODS: A reference model with six internal-connection implant replicas placed in the completely edentulous mandibular arch and connected to multi-base abutments was fabricated from heat-curing acrylic resin. Forty impressions of the reference model were made, 20 each with polyether (PE) and polyvinylsiloxane (PVS) impression materials using the open tray technique. The PE and PVS groups were further subdivided into four subgroups of five each on the bases of splinting type: no splinting, bite registration PE, bite registration addition silicone, or autopolymerizing acrylic resin. The positional accuracy of the implant replica heads was measured on the poured casts using a coordinate measuring machine to assess linear differences in interimplant distances in all three axes. The collected data (linear and three-dimensional [3D] displacement values) were compared with the measurements calculated on the reference resin model and analyzed with nonparametric tests (Kruskal-Wallis and Mann-Whitney). RESULTS: No significant differences were found between the various splinting groups for both PE and PVS impression materials in terms of linear and 3D distortions. However, small but significant differences were found between the two impression materials (PVS, 91 µm; PE, 103 µm) in terms of 3D discrepancies, irrespective of the splinting technique employed. CONCLUSIONS: Casts obtained from both impression materials exhibited differences from the reference model. The impression material influenced impression inaccuracy more than the splinting material for multiple-unit abutment-level impressions.

Closed hollow bulb obturator--one-step fabrication: a clinical report.

A method is described for the fabrication of a closed hollow bulb obturator prosthesis using a hard thermoforming splint material and heat-cured acrylic resin. The technique allowed the thickness of the thermoformed bulb to be optimized for weight reduction, while the autopolymerized seal area was covered in heat-cured acrylic resin, thus eliminating potential leakage and discoloration. This technique permits the obturator prosthesis to be processed to completion from the wax trial denture without additional laboratory investing, flasking, and processing.