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1.
J Prosthet Dent ; 2021 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-33541819

RESUMEN

In studies that assessed the accuracy of implant surgical guides, evaluations were based on the placement position of the implant by using a manufactured surgical guide. However, such assessments could involve errors that may occur during implant placement. Therefore, evaluating the 3-dimensional accuracy of the fabrication of the implant surgical guide itself is not enough. In the evaluation method described in this article, location-related information is obtained by connecting a scan body to the sleeve of the surgical guide instead of directly placing the implant. This helps to evaluate the accuracy of the surgical guide without errors in the placement of an implant.

2.
Eur J Dent Educ ; 2021 Jan 29.
Artículo en Inglés | MEDLINE | ID: mdl-33512776

RESUMEN

PURPOSE/OBJECTIVES: Dental students experience difficulties during the transition from preclinical to clinical curriculum. In order to help the students to adapt to the clinical education program, a simulated practice using patient-based customized models was introduced in this study to prepare for their first clinical practice. METHODS: This study included 45 Third year predoctoral students (D3 students) who were about to perform the preparation of a single crown abutment on their first patient. After practicing abutment preparation using simulated models and providing the actual treatment to their own patient, the students were surveyed to investigate their perceptions on the simulated practice using the 3D-printed customized typodont model. The statistical analysis of the quantitative data and the thematic analysis of the qualitative data were conducted. RESULTS: Regarding this simulation, more than 80% of the students gave positive feedback on their practice of (a) operative positions and postures, (b) finger rest, (c) occlusal reduction, (d) axial reduction, and (e) proximal reduction. Student responses on the open-ended questions about how they perceived the usefulness of this simulation were categorized as 'First clinical case', 'Patient-based model', and 'Realistic simulation environment'. In addition, a number of improvements of the simulation was also suggested by the students including the typodont and the manikin. CONCLUSIONS: This study gives insights into the significance of simulated practice using patient-based customized typodonts as a transitional education tool and its direction of development in the field of restorative treatments accompanied by irreversible tooth preparations.

3.
Materials (Basel) ; 13(23)2020 Nov 26.
Artículo en Inglés | MEDLINE | ID: mdl-33255922

RESUMEN

Recent advances in three-dimensional (3D) printing have introduced new materials that can be utilized for dental restorations. Nonetheless, there are limited studies on the color stability of restorations using 3D-printed crowns and bridge resins. Herein, the color stability of conventional computer-aided design/computer-aided manufacturing (CAD/CAM) blocks and 3D-printing resins was evaluated and assessed for their degrees of discoloration based on material type, colorant types (grape juice, coffee, curry, and distilled water (control group)), and storage duration (2, 7, and 30 days) in the colorants. Water sorption, solubility, and scanning electron microscope (SEM) analyses were conducted. A three-way ANOVA analysis showed that all three factors significantly affected the color change of the materials. Notably, the discoloration (ΔE00) was significantly higher in all 3D printing resins (4.74-22.85 over the 30 days) than in CAD/CAM blocks (0.64-4.12 over the 30 days) following immersion in all colorants. 3D-printing resins showed color differences above the clinical limit (2.25) following storage for 7 days or longer in all experimental groups. Curry was the most prominent colorant, and discoloration increased in almost all groups as the storage duration increased. This study suggests that discoloration must be considered when using 3D printing resins for restorations.

4.
Materials (Basel) ; 13(23)2020 Nov 28.
Artículo en Inglés | MEDLINE | ID: mdl-33260676

RESUMEN

The amount of photopolymer material consumed during the three-dimensional (3D) printing of a dental model varies with the volume and internal structure of the modeling data. This study analyzed how the internal structure and the presence of a cross-arch plate influence the accuracy of a 3D printed dental model. The model was designed with a U-shaped arch and the palate removed (Group U) or a cross-arch plate attached to the palate area (Group P), and the internal structure was divided into five types. The trueness and precision were analyzed for accuracy comparisons of the 3D printed models. Two-way ANOVA of the trueness revealed that the accuracy was 135.2 ± 26.3 µm (mean ± SD) in Group U and 85.6 ± 13.1 µm in Group P. Regarding the internal structure, the accuracy was 143.1 ± 46.8 µm in the 1.5 mm-thick shell group, which improved to 111.1 ± 31.9 µm and 106.7 ± 26.3 µm in the roughly filled and fully filled models, respectively. The precision was 70.3 ± 19.1 µm in Group U and 65.0 ± 8.8 µm in Group P. The results of this study suggest that a cross-arch plate is necessary for the accurate production of a model using 3D printing regardless of its internal structure. In Group U, the error during the printing process was higher for the hollowed models.

5.
J Prosthet Dent ; 2020 Nov 19.
Artículo en Inglés | MEDLINE | ID: mdl-33223198

RESUMEN

This clinical report describes the treatment of a patient with a large defect area in the maxillary central incisor, left lateral incisor, canine, and first premolar area after a partial maxillectomy. Computer-aided design and computer-aided manufacturing (CAD-CAM) techniques including rapid prototyping and milling were applied together to fabricate a removable partial denture.

6.
Polymers (Basel) ; 12(11)2020 Nov 23.
Artículo en Inglés | MEDLINE | ID: mdl-33238528

RESUMEN

Three-dimensional (3D) printing is increasingly being utilized in the dental field. After fabricating a prosthesis using a 3D printed resin, a post-curing process is required to improve its mechanical properties, but there has been insufficient research on the optimal post-curing conditions. We used various 3D printed crown and bridge materials in this study, and evaluated the changes in their properties according to post-curing time by evaluating the flexural strength, Weibull modulus, Vickers hardness, color change, degree of conversion, and biocompatibility. The obtained results confirmed that the strength of the 3D printed resin increased when it was post-cured for 60-90 min. The Vickers hardness, the degree of conversion, and biocompatibility of the 3D printed resins increased significantly around the beginning of the post-curing time, and then increased more gradually as the post-curing time increased further. It was observed that the color tone also changed as the post-curing time increased, with some groups showing a ΔE00 value of ≥ 2.25, which can be recognized clinically. This study has confirmed that, after the printing process of a 3D printed resin was completed, a sufficient post-curing time of at least 60 min is required to improve the overall clinical performance of the produced material.

7.
Polymers (Basel) ; 12(6)2020 Jun 22.
Artículo en Inglés | MEDLINE | ID: mdl-32580368

RESUMEN

Esthetic dental computer-aided design/computer-aided manufacturing (CAD/CAM) polymers such as disperse-filled composites (DFC) and polymer-infiltrated ceramic networks (PICN) should be subjected to surface treatment before bonding. However, such treatment can lead to defect formation and a decrease in strength. Therefore, in this study, we compared the flexural strengths of DFC and PICN materials air-abraded with alumina particles of different sizes at different pressures. In addition to Weibull analysis, the samples (untreated and treated) were characterized by scanning electron microscopy and atomic force microscopy. Both DFC and PICN exhibited the lowest flexural strength at large particle sizes and high pressures. Therefore, we optimized the air abrasion parameters to maintain the flexural strength and significantly increase surface roughness. In the case of DFC, the optimal particle size and pressure conditions were 50 µm at 2 bar and 110 µm at 1 bar, while for PICN, the best performance was obtained using Al2O3 particles with a size of 50 µm at 1 bar. This study reveals that optimization of the surface treatment process is crucial in the fabrication of high-performance clinical materials for dental restorations.

8.
J Clin Med ; 9(4)2020 Apr 14.
Artículo en Inglés | MEDLINE | ID: mdl-32295304

RESUMEN

In the absence of accurate medical records, it is critical to correctly classify implant fixture systems using periapical radiographs to provide accurate diagnoses and treatments to patients or to respond to complications. The purpose of this study was to evaluate whether deep neural networks can identify four different types of implants on intraoral radiographs. In this study, images of 801 patients who underwent periapical radiographs between 2005 and 2019 at Yonsei University Dental Hospital were used. Images containing the following four types of implants were selected: Brånemark Mk TiUnite, Dentium Implantium, Straumann Bone Level, and Straumann Tissue Level. SqueezeNet, GoogLeNet, ResNet-18, MobileNet-v2, and ResNet-50 were tested to determine the optimal pre-trained network architecture. The accuracy, precision, recall, and F1 score were calculated for each network using a confusion matrix. All five models showed a test accuracy exceeding 90%. SqueezeNet and MobileNet-v2, which are small networks with less than four million parameters, showed an accuracy of approximately 96% and 97%, respectively. The results of this study confirmed that convolutional neural networks can classify the four implant fixtures with high accuracy even with a relatively small network and a small number of images. This may solve the inconveniences associated with unnecessary treatments and medical expenses caused by lack of knowledge about the exact type of implant.

9.
J Prosthet Dent ; 2020 Feb 04.
Artículo en Inglés | MEDLINE | ID: mdl-32033790

RESUMEN

A facebow transfer is typically used for mounting a maxillary gypsum cast in an ideal location in a mechanical articulator. However, the facebow transfer procedure is difficult and may cause the patient discomfort. This proposed technique uses a patient's cone beam computed tomography (CBCT) data to reproduce the occlusal plane in relation to digital articulator scan data, align the patient's gypsum cast or intraoral scan data on the reproduced plane, and then transfer the data to a mechanical articulator.

10.
J Prosthet Dent ; 123(3): 531-534, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31307800

RESUMEN

To simulate the current oral status of patients, including maxillofacial defects, the digital method described uses a method based on multisource data. These include data recorded from scans made with and without wearing an obturator and data obtained by scanning the surgical or interim obturator. This method eliminates the need for preliminary impressions and complex border-molding steps during the process of creating a definitive obturator, thereby greatly simplifying the fabrication process.


Asunto(s)
Implantes Dentales , Obturadores Palatinos , Humanos , Boca
11.
J Prosthet Dent ; 123(3): 384-388, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31307802

RESUMEN

During production of an immediate interim implant-supported fixed restoration with interim cylinders, the formation of an access hole in the dentures is critical. Traditional access hole formation involves repeated prosthesis insertion and removal in the oral cavity, primarily through trial and error, to adjust the hole position and size. The presented technique simulates the interim cylinder position based on the healing abutment position, enabling confirmation of the access hole position and ensuring more precise seating of the interim implant-supported fixed restoration.


Asunto(s)
Implantes Dentales , Diseño de Prótesis Dental , Prótesis Dental de Soporte Implantado , Dentaduras
12.
Restor Dent Endod ; 44(3): e29, 2019 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-31485425

RESUMEN

Endodontic microsurgery is defined as the treatment performed on the root apices of an infected tooth, which was unresolved with conventional root canal therapy. Recently, the advanced technology in 3-dimensional model reconstruction based on computed tomography such as cone beam computed tomography has opened a new avenue in application of personalized, accurate diagnosis and has been increasingly used in the field of dentistry. Nevertheless, direct intra-oral localization of root apex based on the 3-dimensional information is extremely difficult and significant amount of bone removal is inevitable when freehand surgical procedure was employed. Moreover, gingival flap and alveolar bone fenestration are usually required, which leads to prolonged time of surgery, thereby increasing the chance of trauma as well as the risk of infection. The purpose of this case report is to present endodontic microsurgery using the guide template that can accurately target the position of apex for the treatment of an anterior tooth with calcified canal which was untreatable with conventional root canal therapy and unable to track the position of the apex due to the absence of fistula.

13.
J Prosthodont ; 28(7): 797-803, 2019 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-31250506

RESUMEN

PURPOSE: To determine the accuracy of a digital manufacturing method for dental implant restorations on stock abutments using intraoral scanners and prefabricated stock-abutment libraries. MATERIALS AND METHODS: Two dental implants with internal hexagonal connections were placed in the mandibular second premolar and second molar areas of a partially edentulous dentoform model; stock abutments with a diameter of 5 mm, abutment height of 5.5 mm, and gingival cuff height of 2 mm were connected. The study model was scanned 10 times using a reference tabletop scanner and 5 types of intraoral scanners (IOSs). The data collected by 5 types of IOSs were divided into 3 groups, based on the type and matching of stock abutment library data: no library, optical library, and contact library groups. A total of 160 data files were analyzed, including reference data. The resulting data were used to evaluate trueness and precision. RESULTS: Trueness and precision values in the group in which library data of the stock abutment were not used were 42.0 to 76.3 µm and 30.5 to 99.7 µm; corresponding values when the library data using an optical scanner were matched were 51.2 to 73.4 µm and 26.3 to 62.8 µm, and those when contact scanner library data were used were 30.1 to 62.4 µm and 15.5 to 55.9 µm. Thus, the accuracy of the contact library group was significantly higher than the accuracies of the no library (p < 0.001) and optical library groups (p < 0.001). CONCLUSION: The application of prefabricated library data of stock abutments using a contact scanner improved the accuracy of scan data. Scan accuracy of the stock abutments differed significantly based on the type of scanner.


Asunto(s)
Implantes Dentales , Boca Edéntula , Diseño Asistido por Computadora , Pilares Dentales , Técnica de Impresión Dental , Humanos
14.
J Vis Exp ; (147)2019 05 30.
Artículo en Inglés | MEDLINE | ID: mdl-31205295

RESUMEN

Digital workflows have actively been used to produce dental restorations or oral appliances since dentists started to make digital impressions by acquiring 3D images with an intraoral scanner. Because of the nature of scanning the oral cavity in the patient's mouth, the intraoral scanner is a handheld device with a small optical window, stitching together small data to complete the entire image. During the complete-arch impression procedure, a deformation of the impression body can occur and affect the fit of the restoration or appliance. In order to measure these distortions, a master specimen was designed and produced with a metal 3D printer. Designed reference geometries allow setting independent coordinate systems for each impression and measure x, y, and z displacements of the cylinder top circle center where the distortion of the impression can be evaluated. In order to evaluate the reliability of this method, the coordinate values of the cylinder are calculated and compared between the original computer-aided design (CAD) data and the reference data acquired with the industrial scanner. The coordinate differences between the two groups were mostly less than 50 µm, but the deviations were high due to the tolerance of 3D printing in the z coordinates of the obliquely designed cylinder on the molar. However, since the printed model sets a new standard, it does not affect the results of the test evaluation. The reproducibility of the reference scanner is 11.0 ± 1.8 µm. This test method can be used to identify and improve upon the intrinsic problems of an intraoral scanner or to establish a scanning strategy by measuring the degree of distortion at each part of the complete-arch digital impression.


Asunto(s)
Arco Dental/fisiología , Técnica de Impresión Dental/normas , Modelos Dentales/normas , Imagenología Tridimensional/métodos , Humanos
16.
Int J Oral Maxillofac Implants ; 34(3): 585­594, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-30716144

RESUMEN

PURPOSE: To evaluate differences in implant placement accuracy depending upon the presence or absence of metal restorations, as well as between distal extension and tooth-end cases. MATERIALS AND METHODS: Five experimental groups were designed with mandibular models exhibiting the following dental statuses: six anterior teeth and bilateral second molars, with bilaterally edentulous sites between them (group NN); six anterior teeth (group NDE); identical to group NN, with the six anterior teeth restored with metal crowns (group MN); identical to group NDE, with the six anterior teeth restored with metal crowns (group MDE); identical to group NN, with all remaining teeth restored with metal crowns (group MM). Six implants were placed on the bilateral first and second premolars and first molars; the linear and angular deviations between the preoperatively planned and actually placed implant positions were computed. RESULTS: Implant position errors were 0.55 to 0.87 mm and 0.53 to 0.80 mm at the entry point and apex, respectively, and were 0.35 to 0.71 mm and 2.02 to 3.12 degrees in depth and angular deviations, respectively. Significant differences were observed between groups NN and MM in overall deviations at the entry point (P = .009) and apex (P = .026), as well as in depth deviation (P = .008). CONCLUSION: The presence of metal restorations on all anterior and posterior remaining teeth resulted in significant differences in linear deviation at the entry point and apex between preoperatively planned and actually placed implant positions, compared with natural teeth without restorations. No significant differences were observed in placement accuracy between distal extension and tooth-end cases.


Asunto(s)
Tomografía Computarizada de Haz Cónico , Implantes Dentales , Artefactos , Implantación Dental Endoósea , Cirugía Asistida por Computador
17.
Dent Mater ; 35(3): 468-476, 2019 03.
Artículo en Inglés | MEDLINE | ID: mdl-30685109

RESUMEN

OBJECTIVES: The aim of the present study was to investigate the adaptation and guide hole tolerance of metal sleeve-free computer-assisted implant surgical guides fabricated with 3D printers. METHODS: An implant surgical guide for full-guided implant placement was designed with a total of eight different guide holes. Ten implant surgical guides (n=10) were fabricated from the same design with each of five in-office 3D printers (D1, FOR, ONE, PER, and ZEN) using compatible printing materials. Ten surgical guides fabricated by the manufacturer of the implant company were used as the control group (CON). The adaptation of the surgical guides was evaluated by the replica technique. The tolerance of the guide holes was evaluated by measuring the degree of diversion with guide drills. RESULTS: CON and D1 showed superior internal adaptation with a gap distance of less than 1mm. The mean degree of diversion of the guide holes ranged from 3.45° for ZEN to 6.55° for PER. The tolerances of CON (4.70°) and D1 (4.50°) did not differ at the level of statistical significance at α=0.05. SIGNIFICANCE: The characteristics of implant surgical guides were evaluated per se. None of the 3D printers fabricated superior implant surgical guides to those produced by the manufacturer with regard to the internal fit and guide tolerance. However, the potential for the routine clinical use of in-office 3D printers was demonstrated. Further studies are required to determine how the guide hole tolerance and the angular deviation between the preplanned and actual implant positions are related.


Asunto(s)
Implantación Dental Endoósea , Cirugía Asistida por Computador , Diseño Asistido por Computadora , Imagenología Tridimensional , Metales , Impresión Tridimensional
18.
J Prosthodont Res ; 63(1): 120-124, 2019 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-30446410

RESUMEN

PURPOSE: To introduce a new and simple digital workflow to record dynamic occlusion, and apply it to occlusal analysis and prosthetic treatment in a virtual environment. METHODS: A table-top scanner (Identica hybrid) was used to transfer fabricated casts into a virtual environment. A facial scanner (Rexcan CS2) was used for facial scanning and target tracking. Four targets were attached to each of the four incisors in the maxilla and mandible to track jaw movement. Target position data were recorded in real time during eccentric movement. The targets were replaced with maxilla and mandible cast scan data, and mandibular movement relative to the maxilla was reconstructed. Four types of antagonist meshes were reconstructed in computer-aided design (CAD) software (EzScan8). The CAD software (Exocad) enabled checking of occlusal contacts in the maximal intercuspation position during eccentric movement. CONCLUSIONS: Target tracking data were transformed into video clips of dental cast scan data, which showed jaw movements in real time. Occlusal contact information was produced by the CAD software. Both dynamic and static occlusion analyses were performed with reconstructed eccentric movement antagonist meshes. Our new method for reconstructing eccentric movements of the mandible can reveal the occlusal dynamics of a patient within a virtual environment.


Asunto(s)
Articuladores Dentales , Oclusión Dental , Imagenología Tridimensional/métodos , Registro de la Relación Maxilomandibular/métodos , Mandíbula/fisiología , Movimiento , Diseño Asistido por Computadora , Modelos Dentales , Humanos , Prostodoncia , Realidad Virtual
19.
J Prosthet Dent ; 121(3): 394-397, 2019 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-30391055

RESUMEN

This article describes a digital technique that combines intraoral digital scans with a 3-dimensional facial scan to predict the outcome of prosthodontic treatment of anterior teeth at the treatment planning phase. This approach may increase patient acceptance of the definitive treatment, as the altered facial appearance is visualized with definitive prosthodontic restorations, thereby improving communication before treatment begins.


Asunto(s)
Diente , Cara , Humanos , Prostodoncia
20.
J Prosthet Dent ; 121(3): 417-425, 2019 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-30391060

RESUMEN

STATEMENT OF PROBLEM: Zirconia is a widely used restorative material. However, phase transformation on clinical application of zirconia has not yet been studied. PURPOSE: The purpose of this study was to evaluate the wear, surface roughness, and aging associated with polished translucent zirconia in both in vitro and clinical experiments. MATERIAL AND METHODS: In vitro experiments were performed with Rainbow and Katana zirconia blocks and natural tooth enamel as the control. They were subjected to 100 000 loading cycles with a maxillary premolar antagonist. All specimens were analyzed for wear, and the zirconia specimens were evaluated for surface roughness and monoclinic phase (m-phase) transformation by X-ray diffractometry before and after cyclic loading. The clinical study included participants who required single-crown implant-supported restorations replacing the first or second molar. The participants received Rainbow or Katana zirconia prostheses (n=15, each). For wear analysis, impressions of each prosthesis, antagonist, and adjacent tooth were made at 1 week and 6 months after crown delivery. The occlusal relationship of the crowns in maximum intercuspation was evaluated by using the T-Scan 8 occlusal diagnostic system. The degree of transformation of zirconia to the m-phase was measured by using X-ray diffractometry of the crowns after 6 months of use. RESULTS: Zirconia induced significantly greater enamel wear than the natural tooth control. Katana specimens exhibited significantly greater wear and surface roughness than the Rainbow specimens. The degrees of antagonistic wear and zirconia phase transformation in the clinical experiment were significantly greater than those in the in vitro experiment. The Katana groups showed significantly higher m-phase levels than the Rainbow groups. CONCLUSIONS: Phase transformation of zirconia occurs within 6 months of clinical use, and the wear and degrees of phase transformation varied according to the zirconia product used.


Asunto(s)
Alisadura de la Restauración Dental , Circonio , Esmalte Dental , Ensayo de Materiales , Propiedades de Superficie
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