• Journal of Technologic Dentistry
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• v.42 no.1
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• pp.35-41
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• 2020

Purpose: The purpose of this study was to evaluate the accuracy of the DLP 3D printer by conducting 3-dimensional assesment of resin provisional restorations. Methods: The first premolar of the maxillary was prepared for the abutment. The abutment was scanned by using a scanner. The provisional restoration was designed by using CAD software. A total of 16 resin provisional restorations were produced using ZD200 and Veltz DLP 3D printer. Scanning was done of resin provisional restorations and 3-dimensional measurement was conducted for accuracy. The mean (SD) of RMS was reported for each group. Independent t-test was used to assess the statistical significance of the results. All analyses were done using SPSS 22.0. Results: The mean ± SD of RMS value for the accuracy of the resin provisional restorations that was fabricated by using ZD200 and Veltz DLP 3D printer were 50.85.±4.64㎛ and 70.33±6.31㎛. Independent t-test showed significant differences between groups(p<0.001). Conclusion: The resin provisional restorations made with DLP 3D printers showed clinically acceptable accuracy.

• The Journal of the Korean dental association
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• v.57 no.7
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• pp.380-391
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• 2019

In recent years, with the introduction of various restorative materials, restorations using CAD/CAM equipment have been increasing in the esthetic dentistry. The critical steps in the fabrication of indirect restorations with CAD/CAM equipment are proper cavity preparation and making accurate impressions. The process of tooth preparation for CAD/CAM restoration should include a mechanical understanding of milling. In addition, during tooth preparation, the clinician should be familiar with additional equipment and techniques for obtaining the convenience. In order to obtain an accurate oral scan, the clinician should understand the limitations of the oral scan and be skilled at techniques for obtaining a successful image when making oral scans. This article focused clinical guidelines for the preparation of CAD/CAM restorations and introduced clinical methods for making successful impression of oral scans in narrow and deep tooth cavity areas.

• Journal of Dental Rehabilitation and Applied Science
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• v.31 no.4
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• pp.371-377
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• 2015

Oral lichen planus (OLP) is a common mucocutaneous disease, which presents as bilateral or multiple lesions. The several factors are implicated in etiology of OLP such as dental restorations, systemic disease, drugs and stress. Especially the influence of dental restorations and plaque control for OLP has been the interest in dentistry. This case is about OLP patient having poor contoured and ill-fitting metal ceramic restorations. The patient in this study has suffered from OLP for a long time, particularly after restoration of metal ceramic restorations on both posterior teeth of maxilla and mandible. This study reported that OLP lesion recovered effectively by improving the contour and fitness of restorations with plaque control.

• The Journal of Advanced Prosthodontics
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• v.13 no.2
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• pp.71-78
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• 2021

Purpose. This study aims to compare the volumetric change, degree of conversion (DOC), and cytotoxicity of 3D-printed restorations post-cured under three different conditions. Materials and Methods. 3D-printed interim restorations were post-cured under three different conditions and systems: 5 min, 30 min, and 24 h. Three-unit and six-unit fixed dental prostheses (n = 30 for each case) were printed; ten specimens from each group were post-cured and then scanned to compare their volumetric changes. Root-mean-squared (RMS) values of the data were acquired by superimposing the scanned files with original files. Thirty disk-shaped specimens were printed to evaluate the DOC ratio. Fourier transform infrared spectroscopy was used to compare the DOCs of 10 specimens from each group. Human gingival fibroblasts were used to measure the cell viability of every specimen (n = 7). The data from this experiment were employed for one-way analysis of variance and Tukey's post-hoc comparisons. Results. Differences between the three-unit restorations were statistically insignificant, regardless of the post-curing conditions. However, for the six-unit restorations, a high RMS value was acquired when the post-curing duration was 30 min. The average DOC was approximately 56 - 62%; the difference between each group was statistically insignificant. All the groups exhibited cell viability greater than 70%, rendering them clinically acceptable. Conclusion. The post-curing conditions influenced the volume when the length of the restoration was increased. However, this deviation was found to be clinically acceptable. Additionally, post-curing did not significantly influence the DOC and cytotoxicity of the restorations.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.23 no.2
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• pp.86-94
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• 2014

In recent years, perhaps the biggest driver in new material development is the desire to improve crown and bridge esthetics compared to the traditional PFM or all-metal restorations. As such, zirconia, leucite-containing glass ceramic and lithium disilicate glass ceramic have become prominent in the dental practice. Each material type performs differently regarding strength, toughness, ease of machining and the final preparation of the material prior to placement. For example, glass ceramic are typically weaker materials which limits its use to single-unit restorations. On the other hand, zirconia has a high fracture toughness which enables multi-unit restorations. This material requires a long sintering procedure which excludes its use for fast chair side production. Developed hybrid material of CAD/CAM is contained nano ceramic elements. This new material, called a Resin Nano Ceramic is unique in durability and function. The material is not a resin or composite. It is also not a pure ceramic. The material is a mixture of both and consists of ceramic. Like a composite, the material is not brittle and is fracture resistant. Like a glass ceramic, the material has excellent polish retention for lasting esthetics. The material is easily machined chair side or in a dental lab, polishes quickly to an esthetic finish and if necessary, can be useful restoratives.

• The Journal of the Korean dental association
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• v.50 no.7
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• pp.368-376
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• 2012

The demand for tooth-colored restorations has grown considerably during the last decade. Posterior composite restorations have risen in popularity as a result of the development of improved resin composites, bonding systems and operating techniques. A major limitation of direct composite restoration is the difficulty of controlling the polymerization shrinkage. To overcome this limitation, the indirect fabrication of a composite restoration and cementation with resin cement has been advocated. Unfortunately, the current available resin cements with indirect restorations do not always bond to dentin as strongly as dentin adhesive systems bond with direct resin composite restorations. Several procedural strategies have been proposed for indirect composite restoration. In this regard, the rationale for the indication, characteristics and clinical application is described in this paper. As a result, we will try to suggest the evidence-based guidelines for indirect composite restorations by reviewing each available indirect composite products, technical procedure and pronosis.

• Restorative Dentistry and Endodontics
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• v.38 no.1
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• pp.11-20
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• 2013

Objectives: In most retrospective studies, the clinical performance of restorations had not been considered in survival analysis. This study investigated the effect of including the clinically unacceptable cases according to modified United States Public Health Service (USPHS) criteria into the failed data on the survival analysis of direct restorations as to the longevity and prognostic variables. Materials and Methods: Nine hundred and sixty-seven direct restorations were evaluated. The data of 204 retreated restorations were collected from the records, and clinical performance of 763 restorations in function was evaluated according to modified USPHS criteria by two observers. The longevity and prognostic variables of the restorations were compared with a factor of involving clinically unacceptable cases into the failures using Kaplan-Meier survival analysis and Cox proportional hazard model. Results: The median survival times of amalgam, composite resin and glass ionomer were 11.8, 11.0 and 6.8 years, respectively. Glass ionomer showed significantly lower longevity than composite resin and amalgam. When clinically unacceptable restorations were included into the failure, the median survival times of them decreased to 8.9, 9.7 and 6.4 years, respectively. Conclusions: After considering the clinical performance, composite resin was the only material that showed a difference in the longevity (p < 0.05) and the significantly higher relative risk of student group than professor group disappeared in operator groups. Even in the design of retrospective study, clinical evaluation needs to be included.

• The Journal of the Korean dental association
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• v.51 no.11
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• pp.595-603
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• 2013

The requirements for the successful treatment of all-ceramic restorations are not so different from the ones of conventional restorations. "The provisional restoration followed by an adequate tooth reduction and the accurately fitting prostheses with corresponding to final impression" can be the examples of them. Nevertheless, the one which all-ceramic restorations are distinguished from conventional restorations is the additional procedure of so called "bonding". In addition to the application of resin cement between "inner surface of restoration and outer surface of abutment", bonding technology can be also applied to the treatment process of "Post and Core" in particular if the abutments are non-vital teeth. Core build-up for all-ceramic crown is conducted with fiber post and tooth colored composite by considering the properties of the restorations transmitting light. We know well that a vital abutment is easier than a non-vital one to get the targeted goals for clinical success in connection with esthetics and structure. The creation of "Post and Core" with bonding technique is a decisive factor for a long-term success if the abutment is non-vital tooth with dentinal collapse. I would like to share my clinical experience about "post & core build-up and all-ceramic restoration bonding" out of several success strategies of all-ceramic crown with this presentation.

• Imaging Science in Dentistry
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• v.48 no.2
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• pp.87-96
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• 2018

Purpose: The present study aimed to evaluate which of the following imaging methods best assessed misfit at the tooth-restoration interface: (1) bitewing radiographs, both conventional and digital, performed using a photostimulable phosphor plate (PSP) and a charge-coupled device (CCD) system; (2) panoramic radiographs, both conventional and digital; and (3) cone-beam computed tomography (CBCT). Materials and Methods: Forty healthy human molars with class I cavities were selected and divided into 4 groups according to the restoration that was applied: composite resin, composite resin with liner material to simulate misfit, dental amalgam, and dental amalgam with liner material to simulate misfit. Radiography and tomography were performed using the various imaging methods, and the resulting images were analyzed by 2 calibrated radiologists. The true presence or absence of misfit corresponding to an area of radiolucency in regions subjacent to the esthetic and metal restorations was validated with microscopy. The data were analyzed using a receiver operating characteristic (ROC) curve, and the scores were compared using the Cohen kappa coefficient. Results: For bitewing images, the digital systems (CCD and PSP) showed a higher area under the ROC curve (AUROC) for the evaluation of resin restorations, while the conventional images exhibited a larger AUROC for the evaluation of amalgam restorations. Conventional and digital panoramic radiographs did not yield good results for the evaluation of resin and amalgam restorations (P<.05). CBCT images exhibited good results for resin restorations(P>.05), but showed no discriminatory ability for amalgam restorations(P<.05). Conclusion: Bitewing radiographs (conventional or digital) should be the method of choice when assessing dental restoration misfit.

• The korean journal of orthodontics
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• v.44 no.5
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• pp.229-235
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• 2014

Objective: The aim of this study was to assess artifacts induced by metallic restorations in three-dimensional (3D) dental surface models derived by cone-beam computed tomography (CBCT). Methods: Fifteen specimens, each with four extracted human premolars and molars embedded in a plaster block, were scanned by CBCT before and after the cavitated second premolars were restored with dental amalgam. Five consecutive surface models of each specimen were created according to increasing restoration size: no restoration (control) and small occlusal, large occlusal, disto-occlusal, and mesio-occluso-distal restorations. After registering each restored model with the control model, maximum linear discrepancy, area, and intensity of the artifacts were measured and compared. Results: Artifacts developed mostly on the buccal and lingual surfaces. They occurred not only on the second premolar but also on the first premolar and first molar. The parametric values increased significantly with increasing restoration size. Conclusions: Metallic restorations induce considerable artifacts in 3D dental surface models. Artifact reduction should be taken into consideration for a proper diagnosis and treatment planning when using 3D surface model derived by CBCT in dentofacial deformity patients.