development of a dlp 3d printer for orthodontic applications

Abstract Recent advances in Additive Manufacturing (AM) technologies have allowed a widespread diffusion of their use in different fields. 3D printing is becoming commonplace for biomedical applications requiring the custom fabrication of prostheses and appliances fitting patient-specific anatomies. In this work, the feasibility of a vat photopolymerization technology, based on Digital Light Processing (DLP), has been investigated for the manufacturing of polymeric orthodontic appliances. A custom DLP 3D printer has been developed by exploiting an off-the-shelf digital projector, with the aim at studying the influence of printing parameters on the surface roughness. The feasibility of using Dental LT Clear resin, a biocompatible photopolymer specifically designed for SLA technology, has been finally verified

A Digital Process for Manufacturing Customized Trays for Dental-Whitening Treatments

This study presents an alternative process for designing and manufacturing customized trays for dental-whitening treatments. The process is based on a digitized approach consisting of three main stages: design of a reference model, its manufacturing by AM, and thermoforming of the tray. The aim of the study was to develop a high-performance tray, able to guarantee comfort, safety, and efficacy for whitening treatments. To evaluate the patient’s experience, some tests under real operating conditions were performed. Twenty people carried out a nighttime treatment of 14 days. Each patient was asked to assess the overall level of satisfaction and the comfort of the tray and its ability to retain the gel. Tooth whitening was also determined according to the VITAPAN scale. All patients involved in the study were satisfied and provided positive feedback about comfort and tightness of the tray. At the end of the treatment, 15 out of 20 patients achieved shade A1 on the VITAPAN scale. The mean improvement in color shades was about 7. These results confirmed the great potential of the proposed dental tray. Its use was proven to guarantee a high level of quality, flexibility, and customization of dental-whitening treatments, improving comfort, safety, and efficacy

Integrating CBCT and virtual models for root movement with clear aligners

Clear aligners are not only a popular esthetic choice among patients, but they also facilitate better oral hygiene compared with conventional fixed orthodontic appliances. The two approaches are not yet equivalent, however, from a biomechanical point of view. While brackets and wires can provide precisely controlled tooth movements of all types in three dimensions, the ability of clear aligners to move roots to designated positions has not been confirmed. Most treatment planning for aligners considers only the crown data, not the root geometries. More complete information on tooth shapes, including both crown and root anatomies, would enhance treatment planning and provide more realistic simulations. We have developed a 3D data fusion method for creating multi-body orthodontic models from optical surface scans and CBCT images. The resulting 3D digital models combine dental structures and oral soft tissues, each from its most accurate representation: optical scanning for crowns and gingivae and CBCT imaging for roots and alveolar bone. The digital model thus provides a reliable virtual base for clinical diagnosis and 3D treatment planning

Properties Enhancement of Carbon PA 3D-Printed Parts by Post-processing Coating-Based Treatments

In recent years, Fused Deposition Modelling (FDM) has become one of the most attractive Additive Manufacturing (AM) techniques, due to the advantages in the production of complex shapes with a wide range of materials and low investment costs. The thermoplastic polymers used for FDM technology are characterized by low mechanical properties if compared to those of composites and metals. This issue is usually overcome by reinforcing the thermoplastic polymer with chopped fibres or particles. Moreover, a second issue arises, which is represented by the water absorption with a relevant impact on mechanical properties and dimensional stability of printed models. In this paper, an experimental study is presented with the aim at evaluating the water absorption influence on mechanical properties of Carbon PA (Polyamide matrix reinforced with Carbon Fiber at 20%) specimens fabricated with the FDM technique. Two post-processing treatments, based on the use of acrylic spray and photosensitive resin, have been also proposed to improve the behaviour of Carbon PA printed parts. Results of water absorption tests and tensile tests demonstrated a significant improvement in terms of weight stability and mechanical properties by adopting the proposed post-processing treatments

Optical Stereo-System for Full-Field High-Frequency 3D Vibration Measurements Based on Low-Frame-Rate Cameras

Dynamic characterization of vibrating targets represents a critical issue for many industrial fields. In this paper, a stereo-camera system integrated with a Digital Image Correlation (DIC) algorithm is proposed with the aim at performing 3D full-field vibration measurements in the range of kHz. The system exploits two industrial low-speed cameras, and the Nyquist-Shannon frequency limitation is overcome by a down-sampling approach under the hypothesis that the vibration signal is characterized by a single known frequency component. Experimental results obtained from the measurement of vibrational responses of a cantilever plate excited at three high-frequency resonance values (1121 Hz, 2956 Hz and 4010 Hz) are provided. A comparison with numerical analyses evidences the effectiveness of the proposed approach

A Digital Process for Manufacturing Customized Trays for Dental-Whitening Treatments

This study presents an alternative process for designing and manufacturing customized trays for dental-whitening treatments. The process is based on a digitized approach consisting of three main stages: design of a reference model, its manufacturing by AM, and thermoforming of the tray. The aim of the study was to develop a high-performance tray, able to guarantee comfort, safety, and efficacy for whitening treatments. To evaluate the patient’s experience, some tests under real operating conditions were performed. Twenty people carried out a nighttime treatment of 14 days. Each patient was asked to assess the overall level of satisfaction and the comfort of the tray and its ability to retain the gel. Tooth whitening was also determined according to the VITAPAN scale. All patients involved in the study were satisfied and provided positive feedback about comfort and tightness of the tray. At the end of the treatment, 15 out of 20 patients achieved shade A1 on the VITAPAN scale. The mean improvement in color shades was about 7. These results confirmed the great potential of the proposed dental tray. Its use was proven to guarantee a high level of quality, flexibility, and customization of dental-whitening treatments, improving comfort, safety, and efficacy

Biomechanics of the press-fit phenomenon in dental implantology: an image-based finite element analysis

<p>Abstract</p> <p>Background</p> <p>A fundamental pre-requisite for the clinical success in dental implant surgery is the fast and stable implant osseointegration. The press-fit phenomenon occurring at implant insertion induces biomechanical effects in the bone tissues, which ensure implant primary stability. In the field of dental surgery, the understanding of the key factors governing the osseointegration process still remains of utmost importance. A thorough analysis of the biomechanics of dental implantology requires a detailed knowledge of bone mechanical properties as well as an accurate definition of the jaw bone geometry.</p> <p>Methods</p> <p>In this work, a CT image-based approach, combined with the Finite Element Method (FEM), has been used to investigate the effect of the drill size on the biomechanics of the dental implant technique. A very accurate model of the human mandible bone segment has been created by processing high resolution micro-CT image data. The press-fit phenomenon has been simulated by FE analyses for different common drill diameters (D_A = 2.8 mm, D_B = 3.3 mm, and D_C = 3.8 mm) with depth L = 12 mm. A virtual implant model has been assumed with a cylindrical geometry having height L = 11 mm and diameter D = 4 mm.</p> <p>Results</p> <p>The maximum stresses calculated for drill diameters D_A, D_B and D_C have been 12.31 GPa, 7.74 GPa and 4.52 GPa, respectively. High strain values have been measured in the cortical area for the models of diameters D_A and D_B, while a uniform distribution has been observed for the model of diameter D_C . The maximum logarithmic strains, calculated in nonlinear analyses, have been ϵ = 2.46, 0.51 and 0.49 for the three models, respectively.</p> <p>Conclusions</p> <p>This study introduces a very powerful, accurate and non-destructive methodology for investigating the effect of the drill size on the biomechanics of the dental implant technique.</p> <p>Further studies could aim at understanding how different drill shapes can determine the optimal press-fit condition with an equally distributed preload on both the cortical and trabecular structure around the implant.</p