Computer-aided Manufacturing Technology Research Articles

A digital CAD/CAM configurator for the production of orthodontic appliances – Going new ways

Functional therapy in growing patients is a highly relevant area in orthodontics. With the increasing integration of computer-aided design and manufacturing technology (CAD/CAM) in orthodontics, we are witnessing significant advancements in the design of orthodontic appliances. Modern 3D printing technologies allow for the creation of complex, customized equipment in a cost-effective and time-efficient manner, using robust and durable resins. Additionally, the creative input of dental CAD design programs has led to the development of new designs.The aim of this report is to present a novel digital orthodontic prescription that aligns with the concept of a "full digital workflow". This prescription utilizes a digital virtual configurator, enabling effective communication between the clinician, the technician and the patient.Using this prescription system, clinicians can easily configurate an orthodontic appliance before sending it to a dental technician for individualisation. 3D printing of the final design can then be performed directly within the dental office or by the technician. This approach allows the clinician to explore different orthodontic equipment options and modules, without the requirement for a demanding and sophisticated design process and without any knowledge of CAD. The availability of the present configurator might represent a fundamental advancement in the field of the CAD/CAM production of removable appliance linked to economic and ecological benefits.

Repair of fractured metal-ceramic restoration using CAD/CAM technologies. Case report

Fractures in esthetic ceramic veneering are one of the potential failure modes during prosthetic treatment. Depending on the type of chipping fracture, there are three possible outcomes: replacement, restoration repair, or polishing of the fractured area. Computer-aided design and manufacturing (CAD/CAM) technologies provide new methods to the maintenance and repair of fixed metal-ceramic restorations. Here, we report the case of a 68-year-old patient who came to the dentist with comcerns about his appearance due to spontaneous gingival bleeding and a fracture in the ceramic veneering of a metal-ceramic restoration. The patient reported occurrences of bruxism. The proposed treatment plan included consultation with a cardiologist, periodontal treatment, polishing of the chipped areas, repair of the fractured zone with an exposed metal core, and fabrication of a mouth guard. Once the ceramic veneering on the palatal and buccal sides of the retainers had been completely removed, a digital impression was obtained and sent to the dental lab so that milled zirconium veneer could be manufactured. The veneering was cemented the next day using the standard prosthetic field preparation process and resin-modified glass ionomer cement. In conclusion, fixed metal-ceramic restorations that have fractured can be successfully repaired using CAD/CAM methods and materials.

3D printers and their use in prosthetic dentistry

In recent years, the use of computer-aided design and computer-aided manufacturing (CAD/CAM) has increased considerably in addition to the traditional methods used in routine. CAD/CAM technology has many advantages. However, despite these advantages, it has a very important disadvantage such as material waste. Today, the technology that overcomes this problem is the additive manufacturing method with three-dimensional printers. This method has recently replaced the traditional subtractive computer-aided design and manufacturing technology in prosthodontics. The use of 3D printers has been increasing in recent years due to its advantages such as ease of production, time saving and material saving, freedom of design, error-free and faster production. It is also predicted that the use of this technology will increase in the future and will be the main method for digital manufacturing. The aim of this review is to evaluate the production methods of 3D printers, the areas of use in prosthodontics, the advantages and disadvantages of 3D production methods, and to review the purposes of use, materials used and developments in prosthodontics.

Manufacturing of PEEK orthodontic baseplate and 3D-printed alloy components from an intraoral scan.

This paper demonstrates a digital manufacturing technique of a removable orthodontic appliance from an intraoral scan. An intraoral scan was made for the maxillary and mandibular arches. 3Shape Orthodontics Appliance Designer produced the virtual Hawley retainer, consisting of alloy components (Adam Clasps and Fitted Labial bow) and a base plate. The base plate design was modified to adapt to inserting the alloy components, which were combined using cold-cured acrylic. The finished Hawley retainer was assessed intraorally. The described technique emphasizes the design specifications of digitally designed and manufactured removable orthodontic appliances. A combination of additive and subtractive techniques was successfully employed to manufacture the alloy components and base plate. This novel method provides an alternative approach to manufacturing removable appliances with computer-aided design (CAD)/computer-aided manufacturing (CAM) technologies. The described process offers a precursor to digital manufacturing of other developed designs of dental appliances.

Polymer-Infiltrated Ceramic Network Produced by Direct Ink Writing: The Effects of Manufacturing Design on Mechanical Properties

Polymer-infiltrated ceramic network (PICN) materials have gained considerable attention as tooth-restorative materials due to their mechanical compatibility with human teeth, especially with computer-aided design and computer-aided manufacturing (CAD/CAM) technologies. However, the designed geometry affects the mechanical properties of PICN materials. This study aims to study the relationship between manufacturing geometry and mechanical properties. In doing so, zirconia-based PICN materials with different geometries were fabricated using a direct ink-writing process, followed by copolymer infiltration. Comprehensive analyses of the microstructure and structural properties of zirconia scaffolds, as well as PICN materials, were performed. The mechanical properties were assessed through compression testing and digital image correlation analysis. The results revealed that the compression strength of PICN pieces was significantly higher than the respective zirconia scaffolds without polymer infiltration. In addition, two geometries (C-grid 0 and C-grid 45) have the highest mechanical performance.

Digitalization in Periodontics: Unlocking Potential and Possibilities

The field of periodontics has undergone a transformative evolution with the integration of digital technologies. This abstract explores the impact of digitalization on periodontics, focusing on key aspects such as diagnostics, treatment planning, and patient engagement. Digital imaging, including digital radiography and intraoral scanners, has revolutionized the precision and efficiency of periodontal diagnostics. Computer-Aided Design and Manufacturing (CAD/CAM) technologies have enhanced treatment planning, allowing for customized and accurate solutions in periodontal interventions. Teledentistry has emerged as a valuable tool, facilitating remote consultations and increasing accessibility to periodontal care. Electronic Health Records (EHRs) streamline patient management, improving communication among healthcare providers. Precision dentistry, guided by advanced software, ensures optimal outcomes in periodontal surgeries. The incorporation of augmented and virtual reality in periodontal education enhances the learning experience for students and professionals. Digital platforms, such as websites and mobile apps, play a pivotal role in patient engagement and education, empowering individuals to actively participate in their periodontal health. As digitalization continues to advance, periodontics stands at the forefront of innovation, offering a more efficient, precise, and patient-centric approach to the prevention and treatment of periodontal diseases. Keywords: Teledentistry, Electronic health records, Artificial Intelligence, 3D printing, Digital Imaging, Periodontal disease

Recent Developments in Bio-Ink Formulations Using Marine-Derived Biomaterials for Three-Dimensional (3D) Bioprinting.

3D bioprinting is a disruptive, computer-aided, and additive manufacturing technology that allows the obtention, layer-by-layer, of 3D complex structures. This technology is believed to offer tremendous opportunities in several fields including biomedical, pharmaceutical, and food industries. Several bioprinting processes and bio-ink materials have emerged recently. However, there is still a pressing need to develop low-cost sustainable bio-ink materials with superior qualities (excellent mechanical, viscoelastic and thermal properties, biocompatibility, and biodegradability). Marine-derived biomaterials, including polysaccharides and proteins, represent a viable and renewable source for bio-ink formulations. Therefore, the focus of this review centers around the use of marine-derived biomaterials in the formulations of bio-ink. It starts with a general overview of 3D bioprinting processes followed by a description of the most commonly used marine-derived biomaterials for 3D bioprinting, with a special attention paid to chitosan, glycosaminoglycans, alginate, carrageenan, collagen, and gelatin. The challenges facing the application of marine-derived biomaterials in 3D bioprinting within the biomedical and pharmaceutical fields along with future directions are also discussed.

Comparative Accuracy of Intraoral and Extraoral Digital Workflows for Short Span Implant Supported Fixed Partial Denture Fabrication: An In Vitro Study.

BACKGROUND The advent of digital impressions using computer-aided design and manufacturing technology (CAD/CAM) has simplified and improved the fabrication of implant prostheses in dentistry. The conventional impression has several drawbacks, including tray selection, material type, impression technique, impression disinfection, and cast model storage. The inaccuracies caused by distortion and contraction of impression material can be minimized with digital impressions. This study aimed to compare digital dental impressions of 10 working casts made using the Pindex laser removable die system to fabricate parallel drill channels vs 10 working casts made using the Di-Lok plastic tray removable die system. MATERIAL AND METHODS An implant master die with 2 dental implant analogs was fabricated. Ten working casts using the Pindex laser removable die system with parallel drill channels and 10 working casts using the Di-Lok plastic tray removable die system were fabricated. The working casts were scanned using an extra-oral laboratory scanner and the implant master model was scanned with an intra-oral scanner. RESULTS The properties of the casts made using the 2 systems were evaluated and analyzed with ANOVA and post hoc Tukey test. The mean horizontal linear distances between A1B1 (P<0.021), A2B2 (P<0.018), C1D1 (P<0.026), C2D2 (P<0.03), B1C1 (P<0.01), and mean vertical distances between B1A2 (P<0.015), C1D2 (P<0.001), B1B2 (P<0.028), and C1C2 (P<0.001) were significantly different between the Pindex system and Di-Lok tray system as compared to intra-oral scans. CONCLUSIONS Complete digital workflow with intra-oral scans were more than the partial digital workflow with extra-oral scans for the Pindex system and Di-Lok tray systems.

Effect of build orientation on the fracture resistance and marginal quality of 3D-printed anatomic provisional crowns: An in-vitro study

IntroductionComputer-aided design and computer-aided manufacturing (CAD/CAM) technologies have been increasingly used to fabricate provisional restorations in recent years. This study assessed how build orientation influences the fracture resistance and marginal quality of 3D-printed crowns compared with milled provisional crowns. MethodsThe test group included 3D-printed crowns (Freeprint temp Shade A2, Detax, Ettlingen, Germany), which were further subdivided based on print orientation (0°, 45°, and 90°; n = 10 for each subgroup). The control group (n = 10) included milled crowns (Coratemp, White Peaks, Germany) with the same design as those of the test group. The margin quality of each crown was assessed at 60 × magnification using a digital stereomicroscope. A load-to-fracture test was performed by applying a force at a rate of 2 mm/min to assess fracture resistance. One sample from each subgroup was also subjected to scanning electron microscope (SEM) analysis. ResultsThe milled group exhibited the highest fracture resistance and marginal quality. Within the printed subgroups, the 0° group showed the best mean marginal quality, whereas the 90° group showed the lowest mean marginal quality (p < 0.05). Within the test groups, the 90° group had the highest mean fracture resistance (p < 0.05). In the SEM analysis, the milled group exhibited the most homogenous boundaries, whereas among the 3D-printed subgroups, the samples printed at 0° had the best margin quality. ConclusionThe manufacturing method significantly influences the marginal quality and fracture resistance. Milled crowns demonstrated superior marginal quality and fracture resistance compared to those of 3D printed crowns. Furthermore, the print orientation of 0° led to the best marginal quality, whereas printing at 90° led to the highest fracture resistance.

Digital design of open hollow obturator framework using existing dentures: A dental technique

Computer-aided design and computer-aided manufacturing technology has been applied to the fabrication of maxillary obturator frameworks, both directly and indirectly. However, with earlier techniques, it was not possible to accurately determine the position of the framework conforming to the palate, an issue that has been resolved in current fabrication methods. Using the patient’s existing denture, prosthodontists can determine where the framework should be positioned in the defect area. This allows the obturator bulb to be hollowed, thereby reducing weight and making adjustment easier. The most appropriate position for the finish line can be determined by accurately establishing the arrangement of the artificial teeth as well as the most appropriate polishing surface morphology. In maxillofacial prosthetics, restoring proper articulation and the swallowing function through rehabilitation is important, and determining the proper palatal morphology enables good tongue movement and facilitates the restoration of adequate function. The lighter weight contributes to protecting the remaining teeth and improves patient comfort.

Influence of fabrication method on the marginal fit of temporary restorations.

Computer-aided manufacturing (CAM) technology allows the use of different manufacturing techniques. This in vitro study aimed to evaluate the marginal fit of temporary restorations manufactured using conventional chairside methods, milling, and three-dimensional printing. Fifteen 3-element temporary restorations specimens were produced and categorized into three groups: non-digital, obtained using the conventional chairside method (GC); milled (GM); and three-dimensionally printed (GP). Marginal fit was assessed using scanning electron microscopy (SEM) performed under two conditions: one with only the central screw tightened, and the other with all three screws tightened. Horizontal misfit values were categorized as over-, equal-, and under-extended and qualitatively analyzed. Statistical analysis was performed using the Tukey-Kramer test (α=0.05). In the vertical assessment, three-dimensionally printed restorations demonstrated greater misfit than restorations obtained by milling and the conventional chairside method (P<0.05). In the horizontal assessment, the misfit in the GP group was significantly higher than that in the GM and GC groups. Restorations obtained using the conventional chairside method and milled provisional restorations showed more favorable results than three-dimensionally printed restorations.

Delayed reconstructive plastic surgery in patients with tumors of the maxillofacial region: literature review

Introduction. The main treatment option for malignant neoplasms of the head and neck is combined. However, survival rates are still relatively unchanged. The surgical stage of treatment leads to extensive defects that are eliminated through reconstructive technologies. Despite the priority of performing reconstruction at the same time, delayed reconstructions are still being discussed 6–12 months after surgical treatment; therefore, it is necessary to develop new methodological and practical approaches.Aim. To determine the features of the delayed reconstructive-plastic stage in patients with malignant tumors maxillofacial region, evaluation of possible solutions for optimizing the stage.Material and methods. The analysis of available literature sources was taken in the database Medline, Pubmed, eLibrary, etc. The 101 studies were found, 60 were used to write a systematic review.Results. Delayed reconstructive plastic surgery should take into the possibility more complex and larger defects of soft and bone tissues during the reconstructive stage, previous surgery and/or radiation therapy create significant difficulties for the identification of recipient vessels. Computer-aided design (CAD)/computer-aided manufacturing (CAM) technologies allow projecting the design and positioning of reconstructive material at the preoperative stage. Mandibular reconstruction is the most difficult, that isn’t achieve only an aesthetic result, but also to restore the biomechanics of the temporomandibular joint. The development of specific complications hinders the improvement of the patient’s quality of life. In the early postoperative period is may develop necrosis of the flap, thrombosis of vascular pedicle, hematoma; in the late postoperative period plate extrusion is still one of the common complications, planning delayed reconstruction an important aspect is prevention or treatment of osteoradionecrosis. The combination of precarbohydrate loading and dalargin will allow to reduce the frequency of perioperative complications and improve the long-term results of surgical treatment.Conclusion. Reconstructive treatment in patients with defects requiring postponed reconstructive surgeries is a complex problem which requires development of an integrated approach with detailed analysis of the existing defect and previous antitumor therapy.

Comparative analysis of endocrown fracture resistance and marginal adaptation: CAD/CAM technology using lithium disilicate vs. zirconia-reinforced lithium silicate ceramics

AimsThe present study aimed to compare the fracture resistance and marginal adaptation of endocrowns fabricated using lithium disilicate (LDS) and zirconia-reinforced lithium silicate 9ZLS) ceramics by the computer-aided design and computer-aided manufacturing (CAD/CAM) technology. Materials and MethodsIn this in vitro experimental study, 24 extracted mandibular first molars received standard endocrown preparation and were randomly assigned to two groups (n = 12) for the fabrication of endocrowns with ZLS (Suprinity) and LDS (IPS e.max CAD) ceramics. After scanning the teeth with a CAD scanner, endocrowns were designed by inLab Software version 15 (inLab SW 15) and prepared by an imes-icore 350i milling machine. The vertical marginal gap of endocrowns was measured under a stereomicroscope at three steps before and after cementation and after thermomechanical cycles. The fracture resistance of specimens was then measured by load application at a 45° angle. Mode of failure was also determined as reparable or irreparable. Data were analyzed using Pearson’s correlation test and t-test. ResultsThe mean fracture resistance of ZLS endocrowns was significantly higher than that of LDS endocrowns (P = 0.000). The reparability of ZLS endocrowns was zero, while that of LDS endocrowns was 83.33 %. The vertical marginal gap was significantly smaller in ZLS than in LDS endocrowns at all three time points (P < 0.05). Also, the marginal gap increased by cementation and thermomechanical cycles in both groups. ConclusionZLS and LDS endocrowns both showed acceptable vertical marginal adaptation. ZLS had superior marginal adaptation and higher fracture resistance.

Biocompatibility and biofilm formation on conventional and CAD/CAM provisional implant restorations

Dental implant treatment is a complex and sophisticated process, and implant provisional restorations play a vital role in ensuring its success. The advent of computer-aided design and computer-aided manufacturing (CAD/CAM) technology has revolutionized the field of implant restorations by providing improved precision leading to a reduction in chair time and more predictable treatment outcomes. This technology offers a promising solution to the drawbacks of conventional methods and has the potential to transform the way implant procedures are approached. Despite the clear advantages of CAD/CAM over conventional provisional implant restorations including higher accuracy of fit and superior mechanical properties, little research has been conducted on the biological aspect of these novel restorations. This study aims to fill that gap, comprehensively assessing the biocompatibility, gingival tissue attachment and biofilm formation of a range of provisional implant restorations using CAD/CAM technology through milling and 3-D printing processes compared to conventional fabrication. The biocompatibility of the tested restorations was assessed by MTT assay, Calcein-AM assay as well as SEM analysis. The surface roughness of the tested samples was evaluated, alongside the attachment of Human Gingival Fibroblasts (HGF) cells as well as biofilm formation, and estimated Porphyromonas gingivalis (P. gingivalis) cell count from DNA detection.The results showed all tested provisional implant restorations were non-toxic and good HGF cell attachment but differed in their quantity of biofilm formation, with surface texture influenced by the material and fabrication technique, playing a role. Within the limitation of this study, the findings suggest that CAD/CAM-fabricated provisional implant restorations using a milling technique may be the most favourable among tested groups in terms of biocompatibility and periodontal-related biofilm formation.

New-designed 3D printed surgical guide promotes the accuracy of endodontic microsurgery: a study of 14 upper anterior teeth

We aimed to design a novel three-dimensional (3D) printed surgical guide and evaluate its accuracy in assisting endodontic microsurgeries. A new 3D printed surgical guide was designed by computer-aided design and computer-aided manufacturing (CAD/CAM) technology and applied to 7 patients who underwent endodontic microsurgeries of upper anterior teeth from 2020.01 to 2020.12 as the experimental group. 7 patients who suffered from endodontic microsurgeries operated by the same surgeon without using the surgical guide from 2019.01 to 2019.12 were selected as the control group. Cone beam computed tomography (CBCT) was performed more than 12 months after operation, and the accuracy of apical resection was compared between the two groups. The accuracy of the microsurgery focused on the length and angle of the root apical resection. In the study, CBCT data and oral digital scanning data were used to reconstruct 3D models of periapical lesions with soft and hard tissue information, based on which we designed the new 3D printed surgical guides. The guides were successfully applied to the apectomy in endodontic microsurgeries. The deviation of the apical resection length of the experimental group (0.467 ± 0.146 mm) was better than that of the control group (1.743 ± 0.122 mm) (P < 0.0001), and the deviation of the apical resection angle of the experimental group (9.711 ± 3.593°) was significantly less than that of the control group (22.400 ± 3.362°) (P < 0.0001). The 3D-printed surgical guide could effectively guide endodontic microsurgery and improve its accuracy by fixing both the position and the angle of apectomy. The new type of surgical guide could accurately localize the root apex and guide the apical resection.

Modeling and Simulation of 3D Food Printing Systems-Scope, Advances, and Challenges.

Food 3D printing is a computer-aided additive manufacturing technology that can transform foods into intricate customized forms. In the past decade, this field has phenomenally advanced and one pressing need is the development of strategies to support process optimization. Among different approaches, a range of modeling methods have been explored to simulate 3D printing processes. This review details the concepts of various modeling techniques considered for simulating 3D printing processes and their application range. Most modeling studies majorly focus on predicting the mechanical behavior of the material supply, modifying the internal texture of printed constructs, and assessing the post-printing stability. The approach can also be used to simulate the dynamics of 3D printing processes, in turn, assisting the design of 3D printers based on material composition, properties, and printing conditions. While most existing works are associated with extrusion-based 3D printing, this article presents scope for expanding avenues with prominent research and commercial interest. The article concludes with challenges and research needs, emphasizing opportunities for computational and data-driven dynamic simulation approaches for multi-faceted applications.

Using the foundation restoration as a blueprint: An uncomplicated approach to retrofitting crowns to existing removable partial dentures using CAD-CAM technology

Removable partial dentures have been used to rehabilitate partially edentulous patients for decades. A challenging but commonly encountered procedure is retrofitting a crown to an existing removable partial denture. Several techniques have been proposed for fabricating these complex prostheses, some involving the intraoral application of polymers to the abutment tooth or making impressions of the preparation with the removable prosthesis seated. The present technique presents an approach that simplifies the design and fabrication of retrofitted crowns for fractured abutment teeth needing foundation restorations. This approach involves the implementation of computer-aided design and computer-aided manufacturing technology to record and utilize the contours of the foundation restoration established intraorally as a blueprint for the retrofitted crown.

Effect of CAD/CAM Position and Thickness of Ultra-Translucent Multilayered Zirconia on Color Aspects.

Ultra-translucent multilayered zirconia restorations fabricated using computer-aided design and computer-aided manufacturing (CAD/CAM) technology have recently gained popularity. Their esthetic appeal is crucially dependent on the color accuracy, influenced by prosthesis thickness and multilayer composition due to CAD/CAM milling positions. This study comprehensively investigated how these two factors impacted color accuracy, thereby enhancing our understanding of color outcomes. One hundred monolithic multilayer zirconia specimens with 10 × 10 mm square shape were milled in four different positions and five different thicknesses (1.0, 1.5, 2.0, 2.5, and 3.0 mm). The specimens were placed on an A3 shade resin composite substrate, and CIELAB values (L ∗, a ∗, and b ∗) were measured using a spectrophotometer. Delta E (ΔE) values were calculated to quantify the color differences between the specimens and the A3 VITA classical shade tab and compared with the perceptibility and acceptability thresholds of ΔE = 1.2 and 2.7, respectively. Pearson correlation, two-way ANOVA, and Tukey multiple comparisons (α = 0.05) were performed. The proportion of the dentin layer was positively correlated with the a ∗ and b ∗ values, while specimen thickness was positively correlated with the a ∗ value and negatively correlated with the L ∗ and b ∗ values. Significant difference in ΔE value due to different CAD/CAM positions was not observed within the same specimen thickness. Perceptible color differences were observed in specimens with thicknesses greater than 1 mm, while specimens with 1 mm thickness fell within the clinically acceptable range. Highest ΔE value was found in the specimen with 1 mm thickness. Different compositions of multilayers in the final restoration due to different CAD/CAM positions do not significantly affect the color appearance of ultra-translucent multilayer zirconia, with color only influenced by specimen thickness.

A digital chairside repair protocol for removable partial dentures with polyetheretherketone frameworks

Polyetheretherketone (PEEK) has become popular for removable partial denture (RPD) frameworks but reports on their clinical follow-up and repair are lacking. Two defective PEEK-framework RPDs were repaired with computer-aided design and manufacturing technology, saving costs and time and simplifying the treatment process.

The Fracture Resistance of Full Contour Monolithic-Zirconia Dental Crowns from Cyclic Loading: A Function of Lifetime Extension of Dental Restorations

An ex-vivo study aimed to investigate the fracture resistance of monolith- single layer zirconia of 1.5 mm thickness for dental molar crowns concerning simulating failure behavior under simulated cyclic loading with an extended lifetime of up to 5 million cycles. Sixteen molar crowns were scanned after preparation through computer-aided manufacturing (CAD/CAM) technology to recreate the zirconia crowns, which have a uniform occlusal surface thickness of 1.5 mm. All the samples went through thermal aging by putting them through 6000 thermo-cycles for 3 minutes with the use of distilled water at a temperature range between 5 ˚C and 55 ˚C. All samples were placed under cyclic fatigue loading using the SD Mechatronik chewing simulator and afterward subjected to two-dimensional movements for almost five million cycles. Tests were carried out in distilled water at room temperature. The sample was observed, tested, and photographed every five hundred thousand cycles. The surface cracks were observed within the vicinity of the contact area only and extended with increasing cycles. Minor wear depth was observed in the crowns relative to the damage observed in the Ni‑Cr alloy steel flat indenter. No chipping or complete failure was observed in all tested samples which suggested that full-contour zirconia crowns are good for extending the long life service of dental restorations.