Dental gypsum and investments

Nejatian, Touraj; Firouzmanesh, Pegah; Syed, Azeem Ul Yaqin

doi:10.1016/b978-0-08-102476-8.00003-7

Cited by 3 publications

(4 citation statements)

References 22 publications

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“…Further analysis revealed that the misclassified casts exhibited no discernible pattern across the different age groups and dentition status, except that three out of the four misclassifications were associated with lower arches. This suggests that displacement of tongue position during impression-taking, which then manifests in the poured gypsum casts, could introduce minute discrepancies not typically encountered when directly scanning the patient's jaw [ 25 , 39 ]. It can, however, be argued that placement of impression trays, disparate to IOS, is technique sensitive, and uniform application of pressure could possibly yield even displacement of the buccal mucosa and result in similarly effective outcomes [ 40 ].…”

Section: Discussionmentioning

confidence: 99%

Influence of Intraoral Scanners, Operators, and Data Processing on Dimensional Accuracy of Dental Casts for Unsupervised Clinical Machine Learning: An In Vitro Comparative Study

Farook,

Ahmed,

Giri

et al. 2023

International Journal of Dentistry

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Purpose. This study assessed the impact of intraoral scanner type, operator, and data augmentation on the dimensional accuracy of in vitro dental cast digital scans. It also evaluated the validation accuracy of an unsupervised machine-learning model trained with these scans. Methods. Twenty-two dental casts were scanned using two handheld intraoral scanners and one laboratory scanner, resulting in 110 3D cast scans across five independent groups. The scans underwent uniform augmentation and were validated using Hausdorff’s distance (HD) and root mean squared error (RMSE), with the laboratory scanner as reference. A 3-factor analysis of variance examined interactions between scanners, operators, and augmentation methods. Scans were divided into training and validation sets and processed through a pretrained 3D visual transformer, and validation accuracy was assessed for each of the five groups. Results. No significant differences in HD and RMSE were found across handheld scanners and operators. However, significant changes in RMSE were observed between native and augmented scans with no specific interaction between scanner or operator. The 3D visual transformer achieved 96.2% validation accuracy for differentiating upper and lower scans in the augmented dataset. Native scans lacked volumetric depth, preventing their use for deep learning. Conclusion. Scanner, operator, and processing method did not significantly affect the dimensional accuracy of 3D scans for unsupervised deep learning. However, data augmentation was crucial for processing intraoral scans in deep learning algorithms, introducing structural differences in the 3D scans. Clinical Significance. The specific type of intraoral scanner or the operator has no substantial influence on the quality of the generated 3D scans, but controlled data augmentation of the native scans is necessary to obtain reliable results with unsupervised deep learning.

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Section: Discussionmentioning

confidence: 99%

Influence of Intraoral Scanners, Operators, and Data Processing on Dimensional Accuracy of Dental Casts for Unsupervised Clinical Machine Learning: An In Vitro Comparative Study

Farook,

Ahmed,

Giri

et al. 2023

International Journal of Dentistry

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“…It can be seen from Table 2 that the linear expansion coefficients of the blank control group, Heraeus, and Bowin were more than 0.20%, which were not suitable for the production of high-precision dental models [1]. The linear expansion value of Dentona increased from 0.13% to 0.20% within 72 h, which could not meet the occlusal requirements of precision dental castings for clinical applications because it was entirely higher than the 0.06% expansion value required by the application level.…”

Section: Discussionmentioning

confidence: 99%

“…Models of oral tissues are used in dentistry to assess, treat, and manufacture indirect restorations [1]. As an essential auxiliary material, dental gypsum has been used for simulating oral cavity models.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Different Additives on the Hydration and Gelation Properties of Composite Dental Gypsum

Xie

Evelina

et al. 2021

Gels

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Dental mold gypsum materials require fine powder, appropriate liquidity, fast curing, and easy-to-perform clinical operations. They require low linear expansion coefficient and high strength, reflecting the master model and facilitating demolding. In this article, the suitable accelerators and reinforcing agents were selected as additives to modify dental gypsum. The main experimental methods used were to compare the trends of linear expansion coefficients of several commercially available dental gypsum products over 72 h and to observe the cross-sectional microstructure of cured bodies before and after dental gypsum modification using scanning electron microscopy. By adjusting the application of additives, the linear expansion coefficient of dental gypsum decreased from 0.26% to 0.06%, while the flexural strength increased from 6.7 MPa to 7.4 MPa at 2 h. Formulated samples showed good stability and gelation properties with linear expansion completed within 12 h. It is indicated that the performance of dental gypsum materials can be improved by adding additives and nanomaterials, which provided a good reference for clinical preparation of high-precision dental prosthesis.

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“… 7 8 PC, the nucleus of modern construction industry, is usually manufactured by mixing and heating limestone and sand to produce clinker followed by grinding with gypsum. 9 10 PC is being studied as a viable alternative to MTA due to its availability, low cost, and similar properties to commercially available contemporary endodontic cements. 11 However, the raw materials and the manufacturing process of PC might result in the inclusion of contaminants which might come in the form of heavy metals.…”

Section: Introductionmentioning

confidence: 99%

The Hormetic Effect of Arsenic Trioxide on Rat Pulpal Cells: An In Vitro Preliminary Study

et al. 2020

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Objectives Despite the agreement that there is no longer any indication for arsenic use in modern endodontics, some concerns are surfacing about the minute amount of arsenic trioxide (As2O3) released from Portland cement-based materials. The present study investigated the effect of different concentrations of As2O3 on rat pulpal cells and the efficacy of N-acetylcysteine (NAC) in preventing As2O3-mediated toxicity. Materials and Methods Cytotoxicities of 50, 10, or 5 µm As2O3 and the effect of cells co-treatment with 50 µm As2O3 and 5,000 µm NAC or 500 µm NAC were tested at 24 hours or 3 days. Cell viability was assessed by means of MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and cellular morphological changes were observed under phase contrast microscope. Statistical Analysis Two-way analysis of variance with Tukey’s post-hoc test was used to evaluate differences between the groups (α = 0.05). Results At both exposure times, 50 µm As2O3 resulted in lower optical density (OD) values when compared with 10 or 5 µm As2O3. At 24 hours, 10 µm As2O3 resulted in a higher OD value compared with the control; however, at 3 days the difference was statistically insignificant. At each exposure time, the OD value of 5 µm As2O3 group was comparable to the control and 10 µm As2O3 group. There were no significant differences between 50 µm As2O3 group and 500 NAC+50 µm As2O3 group; however, these two groups had lower OD values when compared with 5,000 NAC + 50 µm As2O3 group at 24 hours and 3 days. The latter group showed significantly lower OD value in comparison with the control at 24 hours and 3 days. Control cells were polygonal-shaped while 50 µm As2O3-treated cells exhibited contracted and spherical morphology with increased intercellular spaces. At 24 hours, 10 μm and 5 µm As2O3-treated cells were slightly hypertrophic. Cells co-treated with NAC and As2O3 showed increased intercellular spaces and lower cellular density compared with the control. Conclusions As2O3 displayed a hormetic effect on pulpal cells; however, the proliferative effect induced by low As2O3 concentrations should be interpreted with caution. NAC did not prevent As2O3-mediated toxicity; however, it demonstrated potential for ameliorating this toxicity.

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Dental gypsum and investments

Cited by 3 publications

References 22 publications

Influence of Intraoral Scanners, Operators, and Data Processing on Dimensional Accuracy of Dental Casts for Unsupervised Clinical Machine Learning: An In Vitro Comparative Study

Influence of Intraoral Scanners, Operators, and Data Processing on Dimensional Accuracy of Dental Casts for Unsupervised Clinical Machine Learning: An In Vitro Comparative Study

The Effect of Different Additives on the Hydration and Gelation Properties of Composite Dental Gypsum

The Hormetic Effect of Arsenic Trioxide on Rat Pulpal Cells: An In Vitro Preliminary Study

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