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1.
Compend Contin Educ Dent ; 41(3): 178-179, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32125171

RESUMO

Impression-making is a necessary part of providing restorative and rehabilitative dentistry to patients. The use of physical impression trays and materials dates back to at least the 19th century, which included the development of corrective and functional impression techniques.1 This method of acquiring and conveying information remained largely unchanged throughout the 20th century, although the development and subsequent improvement of elastomeric impression materials greatly enhanced the quality and predictability of impression results. Now with the digitization of the dental profession, the introduction and advancement of digital impressions represents the latest step forward in impression-making. This article reviews the current state of physical impression-making and the.


Assuntos
Técnica de Moldagem Odontológica , Modelos Dentários , Materiais para Moldagem Odontológica , Humanos
2.
Int J Comput Dent ; 23(1): 49-56, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32207461

RESUMO

AIM: Evaluation of appropriate models for computer-aided design/computer-aided manufacturing (CAD/CAM) in vitro studies by investigation of different model materials regarding suitability for intraoral scanners and dimensional stability. MATERIALS AND METHODS: A typodont model was prepared to accommodate a 10-unit prosthesis. The model was duplicated using six different materials: class IV die stone (DS), cobalt-chrome molybdenum (CoCrMo), epoxy resin (EPOX), polyurethane (PU), titanium (TI), and zirconia (ZI). An intraoral scanner was used to obtain three scans of each model. Reference datasets were generated using micro-computed tomography (micro-CT). The first scan was compared with the corresponding reference micro-CT dataset to assess its trueness. The precision was measured by comparing all scans within one test group. For the evaluation of dimensional stability, micro-CT was used to generate three-dimensional (3D) datasets of the models at different time intervals over a 6-week period. The models were kept under constant conditions during the study. All datasets were analyzed with software that determined the deviation of two datasets by alignment using a best-fit algorithm. RESULTS: The criterion of trueness was fulfilled by CoCrMo, EPOX, PU, and the typodont model. Scans of CoCrMo and ZI showed the best precision. PU and the typodont model did not meet the requirement of dimensional stability, whereas EPOX and gypsum were stable only for a period of 10 days. CONCLUSION: The CoCrMo model was the only one that met all the criteria for an appropriate model for CAD/CAM in vitro studies. The other investigated materials either lacked dimensional stability or could not be scanned accurately and reproducibly.


Assuntos
Projeto Auxiliado por Computador , Adaptação Marginal Dentária , Ligas de Cromo , Técnica de Moldagem Odontológica , Modelos Dentários , Humanos , Imagem Tridimensional , Titânio , Microtomografia por Raio-X
3.
Swiss Dent J ; 130(3): 229-235, 2020 Mar 09.
Artigo em Alemão | MEDLINE | ID: mdl-32162856

RESUMO

This case report presents the treatment of a partially edentulous patient with a clasp-retained removable dental prosthesis (RDP) using both, digital and conventional workflows. Differences were demonstrated in impression taking, bite registration, manufacturing of models, prosthetic set-up, framework design and production; the technical steps for the finish of the RDPs were identical and (currently) still dependent on manual skills. The digitally 3D-printed framework were favored by the patient and the dentist due to the precise fit. The number of manual steps will be continuously reduced applying digital technologies for the treatment with RDPs, resulting in shortened clinical and technical work time and higher precision of the final prosthetic restoration. In addition, the use of intraoral scanners is more patient-friendly than classic impressions with elastomers. Technological advancements are required to eliminate today's limitations and enable a complete digital workflow, even without any physical models. Removable Dental Prosthesis 2.0: yes ­ but not yet completely from A to Z.


Assuntos
Prótese Parcial Removível , Boca Edêntula , Projeto Auxiliado por Computador , Técnica de Moldagem Odontológica , Planejamento de Prótese Dentária , Humanos , Fluxo de Trabalho
4.
Compend Contin Educ Dent ; 41(2): 112-117, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32017588

RESUMO

The purpose of impression-taking is to attain the accurate transfer of intraoral information for extraoral use. It is a crucial step in performing a successful dental implant restorative procedure. To accurately replicate the implant position for adaptation of an abutment that will completely engage with the implant, a pick-up impression is taken with an impression coping. Several factors can affect seating of the impression coping, including soft-tissue interference, the size of the impression coping, angulation, proximity or contact with adjacent teeth, damage to the coping, misfit caused by use of other manufacturers' parts, and differences between seating in an external- versus internal-connection implant. This article presents use of a novel verification guide that is intended to ensure complete seating of the impression coping with the implant.


Assuntos
Implantes Dentários , Técnica de Moldagem Odontológica , Adaptação Psicológica , Materiais para Moldagem Odontológica , Modelos Dentários
5.
Eur J Prosthodont Restor Dent ; 28(1): 18-27, 2020 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-32036633

RESUMO

OBJECTIVES: Reports concerning the accuracy of intraoral digital impression systems are limited. This study aimed to assess the effects of scan body types and shapes on digital impression accuracy and scanning time in all-on-four restorations. METHODS: This in vitro study was conducted with two acrylic maxillary models. Two implant systems with different connection types (internal trilobe and external hexagon connection) were inserted according to the all-on-four design. Scanning was performed using Doowon, NT-Trading, and DESS scan bodies. Changes in implants' positions (ΔR) and angulation (ΔA), and the implants' distance from the reference pin (ΔD) compared with the actual model were determined. Scanning times were also measured and compared. RESULTS: The effects of implant connections and scan bodies on ΔR and ΔA were significant (p ⟨0.05). Implant angulation could also affect ΔA (p=0.019). ΔD was only affected by scan body (p ⟨0.001). The three scan bodies were significantly different in terms of scanning time (p=0.001). CONCLUSION: The results showed that scan body type and shape, and implant connection and angulation could affect digital impression accuracy in all-on-four restorations. For both internal and external connections, the NT-Trading and DESS scan bodies had the shortest and longest scanning times, respectively.


Assuntos
Implantes Dentários , Técnica de Moldagem Odontológica , Projeto Auxiliado por Computador , Materiais para Moldagem Odontológica , Modelos Dentários , Prótese Dentária Fixada por Implante
7.
J Biol Regul Homeost Agents ; 34(1 Suppl. 1): 89-97, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32064840

RESUMO

The aim of this review was to collect available evidence and evaluate accuracy outcomes of dental implant impression techniques, and to compare the accuracy of conventional implant impression versus digital implant impression. Inclusion and exclusion criteria were defined by the authors before the start of the study. The inclusion criteria were: all studies published in English language; studies no older than five years; analyzing the accuracy of digital vs conventional technique impression on implants. The exclusion criteria were: publications that reported the same data as later publications by the same authors and systematic reviews; commentaries and letters to the editor; case report and case series. The search resulted in 106 titles. Following the first stage of screening, after the records identification through database manual searching, 112 potentially relevant studies were identified. After the second stage screening, 33 full text publications were obtained and analyzed and 17 were excluded. Afterwards, 18 articles resulted eligible after full text reading and a cross search of the articles' references was accomplished; 3 articles were consequently added. At the end only 7 articles were included in the quantitative analysis. Within the limitations of this systematic review, digital impression on dental implants offers a comparable accuracy compared with conventional impressions technique. More clinical trials are recommended to investigate the accuracy of these scanners and their validity in clinical use.


Assuntos
Implantes Dentários , Técnica de Moldagem Odontológica , Processamento de Imagem Assistida por Computador , Humanos
8.
Int J Prosthodont ; 33(2): 192-201, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32069344

RESUMO

PURPOSE: To determine the accuracy of direct digital impressions in vivo and compare it to that of conventional impressions in order to assess whether intraoral scanners could be a legitimate alternative for the manufacturing of fixed prosthodontics. MATERIALS AND METHODS: An electronic systematic search was conducted in the PubMed, Web of Science, Embase, and Cochrane Library databases using query terms such as digital impression; intraoral digital impression; intraoral scanner; intraoral digital scanner; conventional impression; analogue impression; and accuracy. The outcomes were the trueness and precision of digital impressions in comparison to those of high-precision conventional impressions in vivo. RESULTS: Six studies matched the inclusion criteria. Four studies investigated the precision of digital impressions, while two studies focused on their trueness. Even if all the authors agreed that conventional impressions were more accurate than digital impressions in vivo, they gave different opinions on using intraoral scanners in a clinical context without causing misfit of the final restoration. CONCLUSION: According to the results of the present review, conventional impressions performed using high-precision impression materials showed greater accuracy than digital impressions. However, additional studies assessing the accuracy of digital impressions in a wider variety of clinical situations are highly recommended.


Assuntos
Técnica de Moldagem Odontológica , Modelos Dentários , Projeto Auxiliado por Computador , Materiais para Moldagem Odontológica , Humanos , Imagem Tridimensional , Prostodontia
9.
Beijing Da Xue Xue Bao Yi Xue Ban ; 52(1): 129-137, 2020 Feb 18.
Artigo em Chinês | MEDLINE | ID: mdl-32071476

RESUMO

OBJECTIVE: To provide a reference for using intraoral scanners for making clinical diagnostic dentures of edentulous jaws by comparing the accuracy of three intraoral scanners for primary impression and jaw relation record of edentulous jaws. METHODS: This study contained 6 primary impressions of the edentulous patients. Each of the impressions consisted of the maxillary primary impression, the mandibular primary impression and the jaw relation record. For each of them, a dental cast scanner (Dentscan Y500) was used to obtain stereolithography (STL) data as reference scan, and then three intraoral scanners including i500, Trios 3 and CEREC Primescan were used for three times to obtain STL data as experiment groups. In Geomagic Studio 2013 software, trueness was obtained by comparing experiment groups with the reference scan, and the precision was obtained from intragroup comparisons. Registered maxillary data of the intraoral scan with reference scan, the morphological error of jaw relation record was obtained by comparing jaw relation record of the intraoral scan with the reference scan. Registered mandibular data with jaw relation record of intraoral scan and the displacement of the jaw position were evaluated. Independent samples t test and Mann-Whitney U test in the SPSS 20.0 statistical software were used to statistically analyze the trueness, precision and morphological error of jaw relation record of three intraoral scanners. The Bland-Altman diagram was used to evaluate the consistency of the jaw relationship measured by the three intraoral scanners. RESULTS: The trueness of i500, Trios 3 and CEREC Primescan scanners was (182.34±101.21) µm, (145.21±71.73) µm, and (78.34±34.79) µm for maxilla; (106.42±21.63) µm, and 95.08 (63.08) µm, (78.45±42.77) µm for mandible. There was no significant difference in trueness of the three scanners when scanning the maxilla and mandible(P>0.05). The precision of the three scanners was 147.65 (156.30) µm, (147.54±83.33) µm, and 40.30 (32.80) µm for maxilla; (90.96±30.77) µm, (53.73±23.56) µm, and 37.60 (93.93) µm for mandible. The precision of CEREC Primescan scanner was significantly better than that of the other two scanners for maxilla (P<0.05). Trios 3 and CEREC Primescan scanners were significantly better than i500 scanner for mandible (P<0.05). The precision of the i500 and Trios 3 scanners for mandible was superior to maxilla (P<0.05). The upper limit of 95% confidence intervals of trueness and precision of three scanners for both maxilla and mandible were within ±300 µm which was clinically accepted. The morphological error of jaw relation record of the three scanners was (337.68±128.54) µm, (342.89±195.41) µm, and (168.62±88.35) µm. The 95% confidence intervals of i500 and Trios 3 scanners were over 300 µm. CEREC Primescan scanner was significantly superior to i500 scanner(P<0.05).The displacement of the jaw position of the three scanners was (0.83±0.56) mm, (0.80±0.45) mm, and (0.91±0.75) mm for vertical dimension; (0.79±0.58) mm, (0.62±0.18) mm, and (0.53±0.53) mm for anterior and posterior directions; (0.95±0.59) mm, (0.69±0.45) mm, and (0.60±0.22) mm for left and right directions. The displacement of the jaw position of the three scanners in vertical dimension, anterior and posterior directions and the left and right directions were within the 95% consistency limit. CONCLUSION: Three intraoral scanners showed good trueness and precision. The i500 and Trios 3 scanners had more errors in jaw relation record, but they were used as primary jaw relation record. It is suggested that three intraoral scanners can be used for obtaining digital data to make diagnostic dentures and individual trays, reducing possible deforming or crack when sending impressions from clinic to laboratory.


Assuntos
Técnica de Moldagem Odontológica , Arcada Edêntula , Projeto Auxiliado por Computador , Modelos Dentários , Humanos , Imagem Tridimensional
10.
Am J Orthod Dentofacial Orthop ; 157(2): 148-155.e1, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32005465

RESUMO

INTRODUCTION: A prospective randomized study was undertaken to compare conventional study model-based manual Peer Assessment Rating (PAR) scoring with computer-based automated scoring using scanned study models or intraoral scanning. METHODS: The sample consisted of 67 patients, mean age 15.03 (range 11-37) years. Sixty-seven patients underwent alginate impression-taking and intraoral scanning (CS 3600; Carestream Dental, Stuttgart, Germany) at a single appointment in a randomized order. For each patient, a weighted PAR score was calculated manually by a calibrated examiner using study models and a PAR ruler (conventional group), and automatically using Carestream Dental CS Model+ software and data from scanned study models (indirect digital group) or intraoral scans (direct digital group). All procedures were timed, and each patient completed a binary questionnaire relating to their experience. RESULTS: There were no significant differences between methods for calculated mean weighted PAR score (P = 0.68). Mean (standard deviation) chairside time for impression-taking was 5.35 (± 1.16) minutes and for intraoral scanning, 7.76 (± 2.76) minutes (P <0.05). Mean (standard deviation) times taken to calculate weighted PAR scores were 2.86 (± 0.96), 5.58 (± 2.33), and 4.58 (± 2.18) minutes for conventional, indirect digital, and direct digital groups, respectively (P >0.05). A total of 61 patients (91%) preferred intraoral scanning to impression-taking. CONCLUSIONS: Automated PAR scoring using cast study models or intraoral scanning is valid, though both methods take longer than conventional scoring. Patients prefer intraoral scanning to impression-taking. REGISTRATION: ClinicalTrials.gov (NCT03405961). PROTOCOL: The protocol was not published before study commencement.


Assuntos
Projeto Auxiliado por Computador , Técnica de Moldagem Odontológica , Adolescente , Adulto , Criança , Modelos Dentários , Humanos , Imagem Tridimensional , Estudos Prospectivos , Software , Adulto Jovem
11.
J Prosthodont ; 29(2): 114-123, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31893566

RESUMO

PURPOSE: In-laboratory assessment by laboratory technicians may offer insight to increase clinical success of dental crowns, and research in this area is lacking. MATERIALS AND METHODS: Dentists in the National Dental Practice-Based Research Network enrolled patients in a study about single-unit crowns; laboratory technicians evaluated the quality of tooth preparations and impressions. The primary outcome for each crown was clinical acceptability (CAC), as judged by the treating dentist. A secondary outcome was "Goodness of Fit (GOF)," a composite score of several aspects of clinical fit, also judged by the study dentist. A mixed-effects logistic regression was used to analyze associations between laboratory technician ratings and the CAC and GOF. RESULTS: Dentists (n = 205) evaluated 3731 crowns. Technicians ranked the marginal detail of impressions as good or excellent in 92% of cases; other aspects of the impression were ranked good or excellent 88% of the time. Regarding tooth preparation, about 90% of preparations were considered adequate (neither excessive nor inadequate reduction). Factors associated with higher CAC were more preparation taper, and use of optical imaging. Factors associated with better GOF were higher impression quality, greater occlusal reduction, more preparation taper, and optical imaging. CONCLUSIONS: Overall quality of preparations and impressions was very high, as evaluated by laboratory technicians. Several clinical parameters were associated with higher CAC and GOF. Clinicians who struggle with crown remakes might consider less conservative tooth preparation, as well as using digital impression technology.


Assuntos
Pessoal de Laboratório , Dente , Coroas , Técnica de Moldagem Odontológica , Planejamento de Prótese Dentária , Odontólogos , Humanos
12.
J Prosthodont ; 29(3): 201-206, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31994818

RESUMO

PURPOSE: To evaluate the accuracy of two intraoral scanners (IOS) in terms of different preparation designs and scan angulation limitation due to the presence of adjacent teeth. MATERIALS AND METHODS: Eight different complete coverage (CC) and partial coverage (PC) tooth preparations were scanned by two IOS, the 3Shape TRIOS (TRI) and the 3M True Definition (TRU). All teeth preparations were scanned in the presence and absence of adjacent teeth. Four groups were established for each IOS; Group 1: PC preparations with adjacent teeth. Group 2: CC preparations with adjacent teeth. Group 3: PC preparations without adjacent teeth. Group 4: CC preparations without adjacent teeth. 3D analysis was performed to examine average absolute discrepancy (AAD) and maximum absolute discrepancy (MAD). A Two-way ANOVA was performed followed by a post-hoc Tukey's test HSD to evaluate the effect of adjacent teeth, preparation design, and the type of IOS used. RESULTS: For TRI, AAD for groups 1, 2, 3, and 4 were 20 ± 1.8 µm, 19.6 ± 2.4 µm, 15.5 ± 2.7 µm, and 12.9 ± 1.4 µm, respectively, whereas MAD for groups 1, 2, 3, and 4 were 109.7 ± 13.5 µm, 93.2 ± 28.9 µm, 85.6 ± 16.1 µm, and 66 ± 20.1 µm, respectively. For TRU IOS, AAD for groups 1, 2, 3, and 4 were 22.0 ± 3.6 µm, 17.9 ± 2 µm, 20 ± 5.9 µm, and 14.9 ± 1.7 µm, respectively, whereas the MAD for groups 1, 2, 3, and 4 were 151.4 ± 38.4 µm, 92.2 ± 17. µm, 92.6 ± 23.6 µm, and 71.4 ± 11.9 µm, respectively. Two-way ANOVA showed statistically significant differences between the AAD and MAD of TRI and TRU (p < 0.001). There were also statistically significant differences for presence or absence of adjacent teeth (p < 0.001), and preparation design (p < 0.001). CONCLUSIONS: PC preparation scans revealed lower accuracy than CC. The presence of adjacent teeth decreased the accuracy of both IOS. TRI gave higher accuracy than TRU for PC, but both IOS showed comparable accuracy for CC groups.


Assuntos
Técnica de Moldagem Odontológica , Modelos Dentários , Projeto Auxiliado por Computador , Arco Dental , Imagem Tridimensional , Preparo do Dente
13.
Int J Oral Maxillofac Implants ; 35(1): 135-140, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31923297

RESUMO

PURPOSE: Capturing implant position in impression-making procedures commonly involves transfer devices, such as implant impression copings and laboratory analogs. These components are intricately machined, including the lumen, and often include additional features for prevention of screw dislodgment. The Centers for Disease Control and Prevention recommends all surfaces in contact with human bodily fluid be disinfected with hospital-grade disinfectant. The ability of these components to harbor biologic contaminant material has not yet been determined, especially with regard to internal configuration, combined with the knowledge that many clinicians and laboratories use a spray disinfectant, which may limit disinfectant contact. The aim of this study was to determine the site and extent of contamination occurring on implant components following clinical impressions and laboratory procedures. MATERIALS AND METHODS: The study design included forensic staining and subsequent analysis of 60 used impression copings, 10 used laboratory analogs, and 10 new components as controls. RESULTS: Staining was found on 100% of impression copings used in vivo, indicating that biologic material had reached multiple sites on both internal and external surfaces of the components. Staining was also found on the internal aspect of used implant analogs, indicating transfer of biologic material from the impression coping and screw. None of the new control components presented staining at any site. Staining highlighted difficult areas to debride, particularly components with difficult or impossible access for cleaning and disinfection. CONCLUSION: Phloxine B staining indicated the ability of biologic material to reach all areas of the implant components. Having demonstrated the difficulty, sometimes impossibility, of accessing areas of these implant components, there is a need to develop protocols to reduce risk of potential transmission of infective material via implant components. Further study is warranted to determine the potential for transmission of infective material due to inadequate disinfection processes of implant componentry.


Assuntos
Implantes Dentários , Planejamento de Prótese Dentária , Adaptação Psicológica , Produtos Biológicos , Materiais para Moldagem Odontológica , Técnica de Moldagem Odontológica , Modelos Dentários , Humanos
14.
Dent Mater J ; 39(1): 52-56, 2020 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-31723066

RESUMO

An optical-impression by an intraoral scanner (IOS) involves optically measuring the surface shape of the target teeth or gums directly in the patient's mouth. IOSs have many advantages, such as reduce patients pain and discomfort, the operator's burden and the risk on infection, real-time impression scanning and visualization, simple replication and selective scanning, reduction of cost and waste of materials and detection of dental caries and crack . IOSs have become one of the most valuable dental-treatment devices for patients, dentists, dental technicians, and dental hygienists. The IOS accuracy matches or supersedes the accuracy of the conventional-impression and indirect method with working models. IOS is clinically applicable in restoration up to four units. IOS's high reproducibility, information-processing ability, multimedia capability, and simplicity and speed in communication can apply to group examination and identification of disaster victims or dementia patients.


Assuntos
Cárie Dentária , Técnica de Moldagem Odontológica , Projeto Auxiliado por Computador , Modelos Dentários , Odontologia , Humanos , Imagem Tridimensional , Reprodutibilidade dos Testes
15.
Dent Mater J ; 39(1): 57-61, 2020 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-31723067

RESUMO

Optical technology has provided a paradigm shift in implant dentistry. However, there is little information about the use of optical technology in implant dentistry, since this technology is relatively new and has been evolving under the current conditions. In the present narrative literature review, the effects of intraoral scanners (IOSs) use on accuracy and the operating time, as well as safety and patient perception, in implant dentistry were evaluated from the clinical perspective. The accuracy of digital scans with IOSs was comparable to the conventional impression techniques for single or partial prostheses, and the digital scans with IOSs are time efficient when taking impressions for single- or double-abutments. However, the accuracy and time efficiency are decreased for multiple implant scans or large-area scans with IOSs use. Patient satisfaction with and preference for IOSs scans are generally superior to those with conventional impression procedures.


Assuntos
Implantes Dentários , Técnica de Moldagem Odontológica , Projeto Auxiliado por Computador , Modelos Dentários , Odontologia , Humanos , Imagem Tridimensional
16.
Clin Oral Implants Res ; 31(1): 74-83, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31608509

RESUMO

OBJECTIVE: This study aimed to evaluate the precision of digital implant impressions in comparison with conventional impressions and assess the impact of the scanning range on precision. MATERIALS AND METHODS: An edentulous maxilla model with six implants was scanned with four intraoral scanners (IOSs) and a dental laboratory scanner five times each, and stereolithography (STL) data were generated. A conventional silicone impression was made, and a model was fabricated, which was scanned using the laboratory scanner. This procedure was also repeated five times. Nine different ranges of interest (ROIs) were defined, and the average discrepancies of the measurement points between each pair of STL images out of five for each ROI were calculated. The effects of "impression method" and "ROI" on precision, as evaluated by the averaged discrepancy, were tested by two-way analysis of variance (p < .05). RESULTS: The effects of "impression methods" and "ROI" and their interactions were statistically significant. The discrepancies in the scanned datasets of the dental laboratory scanner were significantly lower than those in the other impression methods. The discrepancies of the IOSs were comparable with those of the laboratory scanner when the ROI was limited, however; the discrepancies deteriorated when the ROI expanded across the arch, while those of the laboratory scanner remained stable irrespective of the ROI. CONCLUSIONS: Within the limitation of this in vitro study, digital implant impressions by IOSs may show clinically acceptable precision when the scan range is limited, such as in 3-unit superstructure supported by two implants.


Assuntos
Técnica de Moldagem Odontológica , Maxila , Projeto Auxiliado por Computador , Modelos Dentários , Imagem Tridimensional
17.
J Prosthodont Res ; 64(1): 6-11, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31227447

RESUMO

PURPOSE: Intraoral scanners may offer an alternative to traditional impressions. That intraoral scanners produce precise scans is essential. Popular methods used to evaluate precision tend to rely on mean distance deviation between repeated scans. Mean value measurements may underestimate errors resulting in misleading conclusions and clinical decisions. This study investigated the precision of six intraoral scanners using the traditional method of measuring mean error, and a proposed method considering only the most extreme and clinically relevant aspects of a scan. METHODS: An edentulous model was scanned five times using six intraoral scanners. The repeated scans were aligned, uniformly trimmed and mean surface deviation measured across all 20 scan combinations within each scanner group. All scan combinations were then measured by arranging scan vertices from greatest to smallest unsigned distance from its compared scan and measuring the median value within the 1% of most greatly deviating points. Traditional mean deviation results and upper-bound deviations were compared. RESULTS: The upper-bound deviation within a scan reported errors up to two times greater than those found when measuring global mean distances. Results revealed clinically relevant errors of more than 0.3mm in scans produced by the Planmeca and Dentalwings scanners, findings not seen when measuring mean distance error of the complete scan. CONCLUSIONS: Upper-bound deviation of a cropped scan may provide a clinically useful metric for scanner precision. The Aadva, 3Shape, CEREC and TDS produced scans potentially appropriate for clinical use while Planmeca and Dentalwings produced deviations greater than 0.3mm when measuring the upper-bound deviation.


Assuntos
Técnica de Moldagem Odontológica , Boca Edêntula , Projeto Auxiliado por Computador , Modelos Dentários , Humanos , Imagem Tridimensional
18.
J Prosthodont Res ; 64(1): 12-19, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31213364

RESUMO

PURPOSE: To characterize the effect of two processing techniques (pressing and CAD/CAM - Computer Aided Design/Computer Aided Machining) of lithium-disilicate (LD) based crowns on the microstructure, topography, roughness, fractal dimension, internal and marginal adaptation. METHODS: One-hundred identical preparations for monolithic crowns were made with dentin analogue material (G10 epoxy resin). One of the preparations was scanned and a monolithic crown in lithium-disilicate was planned in the CAD system. Fifty crowns were milled in a wax pattern and subjected to pressing (IPS e.max Press), while 50 crowns were machined at CAD/CAM (IPS e.max CAD) and posteriorly crystallized. Internal and marginal adaptation were assessed via replica technique at four manufacturing moments (Milled wax pattern; LDPRESS; Milled LDCAD; Crystallized LDCAD) and considering 5 regions (margin, cervico-axial angle, axial wall, axial-occlusal angle and occlusal wall). Complementary analysis considering microstructure and topography, roughness and fractal dimension were performed in Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). RESULTS: The processing technique resulted in different ceramic microstructure, topography, roughness and fractal dimension, whereas CAD/CAM lead to smoother, more homogeneous but more complex topography features (higher fractal dimension) in comparison to the pressing technique (P<0.05). Regarding marginal and internal fit, LDPRESS crowns showed to be more adapted at the margin, while LDCAD were more adapted at the occluso-axial angle; other regions were not statistically different (α=0.05). CONCLUSIONS: CAD/CAM and the pressing techniques for manufacturing LD crowns lead to completely different ceramic surface characteristics and affect crown adaptation at the margin and at occluso-axial angle.


Assuntos
Adaptação Marginal Dentária , Lítio , Cerâmica , Projeto Auxiliado por Computador , Coroas , Técnica de Fundição Odontológica , Técnica de Moldagem Odontológica , Porcelana Dentária , Planejamento de Prótese Dentária , Fractais , Propriedades de Superfície
20.
J Prosthet Dent ; 123(2): 210-214, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31202553

RESUMO

The accurate transfer of the subgingival contours of implant-supported restorations and pontics is essential for providing the dental technician with the necessary information to fabricate an optimal definitive fixed dental prosthesis. However, once the interim restoration is removed to make an impression, the subgingival tissue, which is no longer physically supported, tends to collapse. This digital intraoral and extraoral scanning technique offers a way to transfer the subgingival contours and intaglio surface of the interim restoration to the definitive restoration. In addition, this technique can reduce clinical and laboratory time, as well as the necessity of storing gypsum casts.


Assuntos
Implantes Dentários , Técnica de Moldagem Odontológica , Materiais para Moldagem Odontológica , Planejamento de Prótese Dentária , Prótese Dentária Fixada por Implante , Prótese Parcial Fixa
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