Accuracy of models of partially edentulous arches obtained by three-dimensional printing: An in vitro study.

Aim: The aim of this study was to evaluate the accuracy of models of partially edentulous arches obtained by three-dimensional (3D) printing. Settings and Design: This was an in vitro study. Materials and Methods: Fifteen partially edentulous models were evaluated, using two methods of measuring dimensions: virtual, using the Standard Tessellation Language files of the models and software (control group), and physical, through printing the models and digital caliper (test group). For both methods, measurements were made regarding the dimensions of the teeth (width and length - buccal/lingual or palatal/occlusal) and distances between the teeth. Statistical Analysis Used: For the variable of linear measurements (width and length) and distances between teeth of the same hemiarch, the Wilcoxon test was used, while for the variable between opposite hemiarches, the paired t-test was used. Results: In the evaluation of the linear measurements, a significant difference was observed only when the width of the molar tooth was analyzed (P = 0.014). When the buccal length was measured, all teeth had linear measurements provided by the virtual method that was lower than the physical (P = 0.000), as well as the lingual/palatal length in incisors (P = 0.003) and molars (P = 0.009) and in total (P = 0.001). As for the analyses between teeth, no difference was identified between the measurements provided by the virtual method compared to the physical one. Conclusions: The 3D printer used to print partially edentulous models provided linear distortions in the teeth but without changes in the distances between teeth of the same hemiarch and between teeth of opposite hemiarches.

Factors that influence the accuracy of intraoral scanning of total edentulous arches rehabilitated with multiple implants: A systematic review.

STATEMENT OF PROBLEM: The direct digitalization of completely edentulous arches rehabilitated with multiple implants still represents a limitation regarding obtaining accurate images for prosthetic purposes. PURPOSE: The purpose of this systematic review was to present the factors that may influence the accuracy of intraoral scanning of completely edentulous arches. MATERIAL AND METHODS: This review was carried out according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria and registered with International Prospective Register of Systematic Reviews (PROSPERO) (CRD42020171021). Three examiners performed an electronic search in the Medline/PubMed, Cochrane Library, Scopus, and Web of Science databases for articles published up to January 2021. RESULTS: The electronic search resulted in 11 498 studies. After removing duplicates, 11 347 studies remained. Twelve studies were selected (10 in vitro and 2 in vivo) according to the eligibility criteria. Several factors were found to influence the performance of intraoral scanners (Carestream Dental and TRIOS, 3Shape presented the best results), the intraoral scanning technique (Promoting physical paths that join the digitization bodies can increase the accuracy of transferring the position of the implants), environmental conditions (temperature: 20 °C to 21 °C, air pressure: 750 to 760 ±5 mmHg, air humidity: 45%, angle and distance between the implants: up to 15 degrees and 16 to 22 mm, and the material of the scan body: PEEK more accurate). CONCLUSIONS: The accuracy of the intraoral scanning of completely edentulous arches is affected by factors such as the type of intraoral scanner, scanning technique, environmental conditions, angle and distance between implants, and material of the scan bodies.

Workflow for complete dentures fabrication in three appointments: A dental technique.

This technical report describes a novel workflow for complete denture fabrication designed to abbreviate the necessary steps for dental prostheses delivery by using a 3-appointment protocol in which preliminary impressions are made in the first session together with the registration of maxillary lip support, occlusal plane, and reference lines for tooth arrangement. A trial denture is fabricated with conventional or computer-aided design and computer-aided manufacturing procedures and is evaluated in the second appointment for esthetics, the definitive impression, and the maxillomandibular relationship record to provide precise references for definitive denture fabrication.

Partially digital workflow for making complete-arch implant-supported fixed prostheses: A dental technique.

This article describes a technique for making complete-arch implant-supported fixed prostheses by using intraoral scanning and computer-aided design and computer-aided manufacturing (CAD-CAM) technology for the fabrication of a metal substructure and conventional processing for the prosthesis base. For this, a device was designed to accurately capture the position of multiple implants and the associated digitalized surgical guide, and the metal substructure was planned and milled directly in cobalt-chromium. The color of the gingiva and artificial teeth was selected by using the intraoral scanner software program, and the prosthesis base was processed conventionally. The straightforward methods used to fabricate the prostheses eliminated possible errors associated with conventional substructure casting and occlusal registration.

CAD/CAM technology for fabrication of reduction guide for RPD parallel guiding planes preparation: A dental technique.

INTRODUCTION: The preparation of parallel axial wall guide planes in abutment teeth is essential for providing a correct path of insertion and removal axis for removable partial dentures (RPDs). With the introduction of digital resources, new alternatives to the conventional method can be used to manufacture guide preparation for guide planes. AIMS: To describe the use of computer-aided design/computer-aided manufacturing (CAD/CAM) technology for the manufacture of guide planes to guide the reduction of the axial walls of abutment teeth according to the insertion and removal axis of the RPD. METHODS: This technique used the "bite splint" module of the Dental Wings software for the virtual planning of guide planes, to promote the construction of axial walls parallel to the abutment teeth. This was performed from the virtual design on a standard tessellation language (STL) file obtained by intraoral scanning, which determined the best trajectory for insertion and removal of the metallic structure. CONCLUSION: Digital technology allows the design and production of guide planes for the preparation of abutment teeth, simplifying the conventionally used technique, with precision and speed.

Impact of CAD-CAM materials and bonding protocol on the bond strength between denture base/artificial teeth: a systematic review and meta-analysis.

PURPOSE: To identify the most effective bonding protocol between the denture base and artificial teeth made with different CAD/CAM materials (milled and 3D printed) compared to conventional heat-cured materials. MATERIALS AND METHODS: This review was performed according to the Preferred Reporting Items for Systematic and Meta-Analysis (PRISMA) criteria and registered in PROSPERO (CRD42021276084). An electronic search was performed independently by two examiners in the MEDLINE/PubMed, Cochrane Library, Scopus, Web of Science, ProQuest, and OpenGrey databases for articles published up to and including December 2021. RESULTS: The electronic search returned 806 articles, and after duplicates were removed, the total was 589 articles. Four articles were selected according to the eligibility criteria. Evaluating the different combinations of denture base materials and artificial teeth, the IvoBase CAD Bond (Ivoclar Vivadent) was effective for bonding the CAD/CAM denture bases to prefabricated acrylic resin denture artificial teeth. There were no differences compared to heat-cured denture base bonding to prefabricated acrylic resin denture artificial teeth (χ2: 68.56; I2: 96%; P < .001). CONCLUSION: IvoBase CAD Bond as a bonding system can be an alternative for using new technologies in the fabrication of α CAD/CAM base with prefabricated acrylic resin denture artificial teeth.

Conventional and digital impressions for complete-arch implant-supported fixed prostheses: time, implant quantity effect and patient satisfaction.

PURPOSE: To evaluate and compare the effect of impression type (conventional vs digital) and the number of implants on the time from the impressions to the generation of working casts of mandibular implant-supported fixed complete-arch frameworks, as well as on patient satisfaction. MATERIALS AND METHODS: 17 participants, 3 or 4 implants, received 2 types of digital impression methods (DI) and conventional (CI). In DI, two techniques were performed: scanning with the scan bodies (SC) and scanning with a device attached to the scan bodies (SD) (BR 10 2019 026265 6). In CI, the making of a solid index (SI) and open-tray impression (OT) were used. The outcomes were used to evaluate the time and the participant satisfaction with conventional and digital impressions. The time was evaluated through the timing of the time obtained in the workflow in the conventional and digital impression. The effect of the number of implants on time was also assessed. Satisfaction was assessed through a questionnaire based on seven. The Wilcoxon test used to identify the statistical difference between the groups in terms of time. The Mann-Whitney test was used to analyze the relationship between the time and the number of implants. Fisher's test was used to assess the patient satisfaction (P < .05). RESULTS: The time with DI was shorter than with CI (DI, x̃=02:58; CI, x̃=31:48) (P < .0001). The arches rehabilitated with 3 implants required shorter digital impression time (3: x̃=05:36; 4: x̃=09:16) (P < .0001). Regarding satisfaction, the DI was more comfortable and pain-free than the CI (P < .005). CONCLUSION: Digital impressions required shorter chair time and had higher patient acceptance than conventional impressions.

Trueness of a device for intraoral scanning to capture the angle and distance between implants in edentulous mandibular arches.

STATEMENT OF PROBLEM: The digitalization of completely edentulous arches presents limitations because of the lack of anatomic structures for best-fit alignment during the image generation process of the scanner's software program. PURPOSE: The purpose of this clinical study was to evaluate a new device for intraoral scanning and to analyze its usefulness in capturing the 3-dimensional (3D) position of implants in edentulous mandibular arches. MATERIAL AND METHODS: The 3D positions of 40 implants in 10 participants with fixed interim mandibular prostheses were evaluated by comparing 3 scanning techniques. Images were generated in 2 experimental groups, with digital scan bodies (group SC) and with the scanning device (group SD) and in a control group (group CT) in which images were obtained by laboratory scanning of casts produced from splinted impression copings. The standard tessellation language (STL) files were superimposed by using a reverse engineering software program to measure the 3D coordinate system. Variations in implant linear displacements (Δx, Δy, and Δz), total 3D displacement (Δx2+Δy2+Δz2), and angle projections (ΔθXY, ΔθXZ, and ΔθYZ) were statistically analyzed (α=.05). The distances between the implants were also measured. The Spearman correlation coefficient (α=.05) was used to find the correlation between the 3D coordinates and the distances between the implants. RESULTS: Group SD had lower values for linear displacement than group SC; however, this difference was not statistically significant except for implant #2. The overall evaluation showed a significant difference with better accuracy for group SD. Concerning angular displacements, group SD showed lesser angular variation for the 3 projection planes. For the distances between the implants, significant differences were only observed for the "all" assessment in which group SD behaved similarly to group CT, while group SC showed the highest values (P<.05). No correlation was detected between the axes (x, y, and z) and the distances between the implants. CONCLUSIONS: The evaluated scanning device led to improved trueness for linear, angular displacements, and distances between implants in mandibular edentulous arches.

Accuracy of CAD-CAM systems for removable partial denture framework fabrication: A systematic review.

STATEMENT OF PROBLEM: Removable partial dentures (RPDs) are traditionally made by casting, a complex, error-prone, and time-consuming process. Computer-aided design and computer-aided manufacturing (CAD-CAM) RPD systems may simplify the clinical steps and minimize errors; however, the accuracy of CAD-CAM RPD systems is unclear. PURPOSE: The purpose of this systematic review was to determine whether CAD-CAM systems are accurate for the manufacturing of RPD frameworks. MATERIAL AND METHODS: A literature search was conducted through Medline-PubMed, Scopus, Lilacs, Web of Science, and Cochrane Library databases using specific keywords for articles published up to November 2019. Three reviewers obtained data and compared the results. All studies evaluated the framework accuracy or fit of prostheses fabricated with conventional and digital techniques. RESULTS: A total of 7 articles, 2 clinical studies, and 5 in vitro studies that complied with the inclusion criteria were evaluated. One in vitro study compared indirect (extraoral) and direct (intraoral) scanning for partially edentulous ridges and shows that digital scans were better than conventional impressions in terms of trueness. In the other studies included, although the frameworks analyzed had clinically acceptable discrepancies (<311 µm), the material influenced the fit. Polyetheretherketone (PEEK) showed better fit than traditional metal cast RPDs. Co-Cr alloy RPDs produced by rapid prototyping exhibited the highest discrepancies when produced by sintering laser melting. CONCLUSIONS: The results show that the digital technique for RPD frameworks is accurate. In the studies included, the analyzed frameworks had clinically acceptable gaps, but the results were heterogeneous among studies because the articles used different measurement methods with small sample sizes. Few studies discussed the long-term clinical performance. The digital technique for RPD frameworks was accurate because the misfits and mismatches found in in vitro and clinical studies were within the acceptable clinical limit for RPDs.

Influence of implant position on the accuracy of intraoral scanning in fully edentulous arches: A systematic review.

STATEMENT OF PROBLEM: Parallel dental implants improve prosthesis longevity and facilitate the impression making steps when compared with angled implants. The effect of implant angulation on the accuracy of casts generated by using intraoral scanners has not been fully investigated. PURPOSE: The present systematic review addressed following the patient, intervention, control, and outcome (PICO) question: Does implant position affect the intraoral scanning accuracy of arches that will receive complete-arch implant-supported fixed dental prostheses? MATERIAL AND METHODS: A bibliographic search was performed in the Medline-PubMed, Scopus, Web of Science, and Cochrane Library databases by using specific descriptors for studies published until July 2020. All studies evaluated the intraoral scanning accuracy of arches rehabilitated with multiple implants through implant linear and/or angular deviation. RESULTS: Eight in vitro studies that met the eligibility criteria were evaluated. Five publications showed lower linear and angular displacements for the digital scans compared with the conventional technique. Two studies showed that the digital scan presented higher angular and linear distortions than the conventional technique. Only 1 study did not find differences between the 2 recording methods. CONCLUSIONS: Digital scanning is reliable. However, caution is needed concerning its indication, especially in patients where the angles between implants are greater than 15 degrees. The association of the implant angulation with the clinical factors needs to be further investigated. The absence of clinical evidence and methodological heterogeneity limited the results of this study.

CAD/CAM-fabricated removable partial dentures: a case report.

AIM: The objective of this case study is to present the manufacturing process and delivery of a removable partial denture (RPD) using computer-aided design/computer-aided manufacturing (CAD/CAM) technology. MATERIALS AND METHODS: A 46-year-old female patient presented at the Federal University of Rio Grande do Norte complaining of the lack of retention in her mandibular RPD. After the design and preparation of the abutment teeth, further appointments were made. In the first appointment, intraoral scanning (IOS) with a Trios scanner was performed, followed by virtual planning of the framework. The RPD was then printed, invested, cast by induction, and polished. In the second appointment, the RPD was delivered. CONCLUSION: The technique proved to be efficient in terms of clinical time and sufficient for patient comfort and satisfaction.