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10 pages, 8081 KiB

Open AccessArticle

PEEK Retainers without CAD-CAM: Simple Solutions for Everyday Challenges

by Piero Antonio Zecca, Margherita Caccia, Lea Siani, Alberto Caprioglio and Rosamaria Fastuca

Appl. Sci. 2024, 14(17), 7806; https://doi.org/10.3390/app14177806 - 3 Sep 2024

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Abstract

Background: The need to perform occasional or continuous MRI exams and the interference with metal orthodontic appliances might be important and take a primary role during retention since the retention period is significantly longer than orthodontic treatment. Several non-metallic materials were proposed as [...] Read more.

Background: The need to perform occasional or continuous MRI exams and the interference with metal orthodontic appliances might be important and take a primary role during retention since the retention period is significantly longer than orthodontic treatment. Several non-metallic materials were proposed as potential alternatives to perform fixed retainers in orthodontics, but they showed internal limits. Methods: Polyetheretherketone (PEEK) was used in the present clinical report as a fixed orthodontic retainer in the lower arch in order to perform an appliance with mechanical properties comparable to metallic ones but with a higher biocompatibility material and without the need for removal in case of an MRI exam. The retainer wire was handmade in the studio and then shaped to fit the arch. Results: PEEK showed a good capability for constructing a lingual fixed retainer compared to other aesthetic non-metallic and metallic materials. Conclusions: To the best of our knowledge, this study proposes how to easily build a retainer in PEEK and provides a clinical example of how this material can be beneficial. Full article

(This article belongs to the Special Issue CAD & CAM Dentistry)

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14 pages, 2803 KiB

Open AccessArticle

Surface Roughness Evaluation of Pre- Versus Post-Crystallization Polish of Two High-Strength Silicate Ceramics for Chairside CAD/CAM Technology

by Felipe Tarosso Rea, Andre Valcanaia, Pilar Herrera-Fierro, Manish Verma and Gisele de Faria Neiva

Appl. Sci. 2024, 14(7), 2768; https://doi.org/10.3390/app14072768 - 26 Mar 2024

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Abstract

This in vitro study evaluated the surface roughness (Sa) of two high-strength silicate ceramics, lithium disilicate IPS e.max CAD, Ivoclar Vivadent (LDS group), and zirconia-reinforced lithium silicate Vita Suprinity, VITA Zahnfabrik (ZLS group). The surface roughness was investigated before and after milling using [...] Read more.

This in vitro study evaluated the surface roughness (Sa) of two high-strength silicate ceramics, lithium disilicate IPS e.max CAD, Ivoclar Vivadent (LDS group), and zirconia-reinforced lithium silicate Vita Suprinity, VITA Zahnfabrik (ZLS group). The surface roughness was investigated before and after milling using different polishing systems and timings relative to the final crystallization of the ceramics. Forty-eight samples per group were polished by a single calibrated operator using two polishing systems: Dialite LD (Brasseler) and Lithium Silicate Polishers (Meisinger) for the LDS group and Dialite LD (Brasseler) and Vita Suprinity Polishing Set Technical (VITA Zahnfabrik) for the ZLS group, both pre- and post-crystallization. Surface roughness was measured using a confocal laser microscope (OLS4000 LEXT/Olympus), with scanning electron microscopy (SEM) used to evaluate surface morphological changes. Significant differences in Sa values were found between baseline groups, with ZLS exhibiting lower values. All polishing methods significantly reduced surface roughness compared to baseline (p ≤ 0.05). No significant differences were found in LDS samples when polishing pre- or post-crystallization (p = 0.129), while for ZLS samples, post-crystallization polishing achieved significantly smoother surfaces (p < 0.001). The study concluded that the choice of polishing system and timing did not significantly affect surface roughness for LDS. However, it is recommended that post-crystallization polishing be performed for the optimal smoothness of ZLS. This study aimed to evaluate the post-milling polishing procedures of CAD/CAM high-strength restorations, emphasizing the importance of an optimal surface roughness to prevent issues such as increased risk of abrasion on opposing teeth, enhanced plaque adhesion, and mechanical failures. Investigating these polishing techniques enables clinicians to optimize clinical performance, thereby improving the quality and longevity of high-strength silicate ceramics. Full article

(This article belongs to the Special Issue CAD & CAM Dentistry)

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11 pages, 1356 KiB

Open AccessArticle

Effect of Spindle Speed and Feed Rate on Surface Roughness and Milling Duration in the Fabrication of Milled Complete Dentures: An In Vitro Study

by Yo Akiyama, Maiko Iwaki, Yuriko Komagamine, Shunsuke Minakuchi and Manabu Kanazawa

Appl. Sci. 2023, 13(24), 13338; https://doi.org/10.3390/app132413338 - 18 Dec 2023

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Abstract

Milling machines have made denture fabrication possible with high accuracy in a short time. However, the relationship between the milling conditions, accuracy, and milling duration has not been clarified. This study aimed to clarify the effects of milling conditions on surface roughness and [...] Read more.

Milling machines have made denture fabrication possible with high accuracy in a short time. However, the relationship between the milling conditions, accuracy, and milling duration has not been clarified. This study aimed to clarify the effects of milling conditions on surface roughness and milling duration. The specimen was designed using CAD software and milled using PMMA disks. In milling, the parameters of finishing the specimen surface were adjusted. Three different spindle speeds and four different feed rates were set. Twelve combinations of each parameter were used for milling, and the surface roughness and milling duration were measured. Results showed that the surface roughness significantly increased with the feed rate on the slopes of the specimen. The surface roughness differed with the spindle speed on the left and right slopes. The spindle speed and feed rate did not affect the surface roughness on the flat surface. The milling duration was not affected by the spindle speed but decreased as the feed rate increased. In conclusion, by increasing both the spindle speed and feed rate, the milling duration could be shortened while maintaining a constant surface quality. The optimum milling conditions were a spindle speed of 40,000 rpm and feed rate of 3500 mm/min. Full article

(This article belongs to the Special Issue CAD & CAM Dentistry)

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11 pages, 1343 KiB

Open AccessArticle

Evaluation of Dimensional Stability and Occlusal Wear of Additively and Subtractively Manufactured Resin-Based Crowns after Thermomechanical Aging

by Mehmet Esad Güven, Gülce Çakmak, Mustafa Borga Dönmez and Burak Yilmaz

Appl. Sci. 2023, 13(21), 11849; https://doi.org/10.3390/app132111849 - 30 Oct 2023

Cited by 1 | Viewed by 1088

Abstract

The knowledge on the surface deviations and wear of recently introduced additively or subtractively manufactured materials indicated for definitive prosthesis is limited. The aim of this present study was to evaluate the external surface and mesiodistal width deviation and the occlusal surface wear [...] Read more.

The knowledge on the surface deviations and wear of recently introduced additively or subtractively manufactured materials indicated for definitive prosthesis is limited. The aim of this present study was to evaluate the external surface and mesiodistal width deviation and the occlusal surface wear of one additively manufactured composite resin (MS) and three subtractively manufactured resins (nanographene-reinforced polymethylmethacrylate (GR), conventional polymethylmethacrylate (PMMA), and reinforced composite resin (BC)) after thermomechanical aging. Molar-shaped crowns were fabricated in the tested materials and digitized with an intraoral scanner (CEREC Primescan; Dentsply Sirona, Bensheim, Germany). Each crown was subjected to thermomechanical aging and rescanned with the same scanner. A three-dimensional analysis software (Geomagic Control X v.2022.1; 3D Systems, Rock Hill, SC, USA) was used to calculate the deviations on the external surface, mesiodistal width, and wear on the occlusal surfaces of the tested crowns. Data were analyzed using one-way ANOVA and Tukey’s tests (α = 0.05). MS had higher external surface deviations than PMMA and GR (p ≤ 0.038) and higher mesiodistal width deviations than PMMA and BC (p = 0.004). BC and GR had higher volume loss than PMMA (p ≤ 0.002). The additively manufactured composite resin was more prone to deviations, while reinforced composite resin had lower wear resistance than most of the tested materials. Full article

(This article belongs to the Special Issue CAD & CAM Dentistry)

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11 pages, 2686 KiB

Open AccessArticle

Marginal Discrepancy and Internal Fit of Bi-Layered and Monolithic Zirconia Fixed Dental Prostheses: An In Vitro Study

by Majed M. Alsarani, Amin S. Rizkalla, Joseph Fava, Thomas W. Coyle and Omar El-Mowafy

Appl. Sci. 2023, 13(20), 11461; https://doi.org/10.3390/app132011461 - 19 Oct 2023

Cited by 1 | Viewed by 1239

Abstract

This in vitro study evaluated the influence of restoration design (bi-layered vs. monolithic) and manufacturing technique on the marginal discrepancy and internal fit of 3-unit zirconia fixed dental prostheses (FDPs). Mandibular second premolars and second molars were prepared as abutments in a 3-unit [...] Read more.

This in vitro study evaluated the influence of restoration design (bi-layered vs. monolithic) and manufacturing technique on the marginal discrepancy and internal fit of 3-unit zirconia fixed dental prostheses (FDPs). Mandibular second premolars and second molars were prepared as abutments in a 3-unit zirconia bridge to develop four groups (n = 10 FDPs): MZ: Monolithic zirconia FDPs, ZL: zirconia framework veneered by the hand-layering technique, ZP: zirconia framework veneered by the heat-pressed technique, and CAD-on: zirconia framework veneered by CAD/CAM lithium-disilicate glass–ceramic. All the zirconia FDPs were cemented to their corresponding die replicas using dual-cure resin cement and were subjected to compressive cyclic loading at a load range for half a million cycles using a universal testing machine. FDPs were sectioned mesiodistally to measure the marginal gap and internal fit using scanning electron microscopy. The measurements were taken at pre-assigned points of each abutment. Data were statistically analyzed via a Kruskal–Wallis test (α = 0.05). No significant differences were found between the monolithic and bi-layered zirconia groups in terms of the marginal discrepancy. However, there was a significant difference in the marginal gap between the zirconia groups. The marginal gap between monolithic and bi-layered zirconia FDPs was within the clinically acceptable range (<100 μm). Comparable mean values of the marginal gaps of 3-unit monolithic and veneered zirconia FDPs were found. Therefore, the FDP design and veneering methods did not affect the marginal discrepancy. However, the mean internal gap varied among the experimental groups. As the current in vitro investigation demonstrated equivalent mean values of marginal gaps of both 3-unit monolithic and bi-layered zirconia FPDs, the use of monolithic 3-unit zirconia FPDs would be a viable alternative fabrication technique. Full article

(This article belongs to the Special Issue CAD & CAM Dentistry)

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11 pages, 2911 KiB

Open AccessArticle

The Use of a 3D Image Comparison Program for Dental Identification

by Daijiro Kubo, Tomoki Itamiya, Norishige Kawanishi, Noriyuki Hoshi and Katsuhiko Kimoto

Appl. Sci. 2023, 13(13), 7517; https://doi.org/10.3390/app13137517 - 26 Jun 2023

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Abstract

Dental identification involves compiling a prescribed dental chart of a deceased person’s oral findings which is then compared with antemortem dental information. However, this process is complicated, and a comparison can be difficult. In this study, the authors evaluated whether it is possible [...] Read more.

Dental identification involves compiling a prescribed dental chart of a deceased person’s oral findings which is then compared with antemortem dental information. However, this process is complicated, and a comparison can be difficult. In this study, the authors evaluated whether it is possible to identify images from antemortem dental information images using an image comparison program (AKAZE) with one-sided cross-sectional images generated from the STL (Standard Triangle Language) data of upper and lower jaw models acquired with an intraoral scanner. From the STL data of 20 patients, 120 cross-sectional images were generated by three practitioners and compared with the cross-sectional images of 20 patients generated later, and the degree of agreement calculated by AKAZE was analyzed. Statistically significant differences were found between images of the same and different models, and statistically significant differences were obtained when comparing one-sided images with limited information, suggesting that partial dentition information can be used to identify the same dentition. Full article

(This article belongs to the Special Issue CAD & CAM Dentistry)

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10 pages, 5373 KiB

Open AccessArticle

Rescanning of Digital Impressions’ Mesh Holes: In Vivo and In Vitro Accuracy Evaluation of Three Different Scanning Protocols

by Andrei B. Faur, Raul N. Rotar, Dragoș Adam and Anca Jivănescu

Appl. Sci. 2023, 13(5), 2867; https://doi.org/10.3390/app13052867 - 23 Feb 2023

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Abstract

Several factors have been identified to have an influence over the accuracy of a digital impression: ambient lighting conditions, the presence of liquid on the intraoral structures, and the scanning patterns. The purpose of this study was to identify which protocol produced the [...] Read more.

Several factors have been identified to have an influence over the accuracy of a digital impression: ambient lighting conditions, the presence of liquid on the intraoral structures, and the scanning patterns. The purpose of this study was to identify which protocol produced the most accurate digital impression regarding a one-preparation scenario in which data were acquired from a single uninterrupted scan, a rescanning of the area of interest in order to obtain more data, or the deletion of the area of interest followed by a rescan. An in vitro scenario using a typodont involving a single full-crown restoration was conceived alongside the selection of an in vivo case of a patient presenting an unrestored right mandibular first molar. The STL (standard tessellation language) reference models for each group were obtained using a high-resolution scanner (Freedom, HD; DOS). With the use of a Medit I700 (Medit, Seoul, South Korea) intraoral scanner, three different scanning protocols were conducted on the typodont and on the clinical case. The measured data (IOS scans) were sorted and further analyzed with the help of Geomagic Control X (Version:16.0.2.16496, 3D Systems, Wilsonville, OR, USA). The Kolmogorov–Smirnov test for normality was conducted on the whole set of data. The nonparametric data set underwent Kruskal–Wallis test analysis while the parametric data set underwent a one-way ANOVA test (the level of significance was set to α = 0.05). For the in vitro case, the “SINGLESCAN” group displayed the best trueness; the “DELETE&RESCAN” group displayed the best precision. Regarding the in vivo case, the “SINGLESCAN” group also displayed the best trueness; the “RESCAN” group displayed the best precision. Statistical differences were found in the trueness and precision of the IOS scans captured with the three different scanning protocols, but the differences were so small that they could be considered clinically negligible. Full article

(This article belongs to the Special Issue CAD & CAM Dentistry)

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18 pages, 894 KiB

Open AccessSystematic Review

Thermal Influence on the Mechanical Properties of CAD/CAM Ceramics: A Systematic Review

by Andrea Ordoñez Balladares, Cristian Abad-Coronel, Patrícia Pauletto and Benjamín José Martín Biedma

Appl. Sci. 2024, 14(12), 5188; https://doi.org/10.3390/app14125188 - 14 Jun 2024

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Abstract

Aim: The influence of different heat treatments on the mechanical properties of CAD/CAM ceramics was assessed. Methodology: A systematic search in five databases and gray literature was performed. In vitro studies providing data about the influence of various thermal treatments on the mechanical [...] Read more.

Aim: The influence of different heat treatments on the mechanical properties of CAD/CAM ceramics was assessed. Methodology: A systematic search in five databases and gray literature was performed. In vitro studies providing data about the influence of various thermal treatments on the mechanical properties of CAD/CAM ceramics were included. Results: Out of 6500 articles found, 15 were included for results analysis. In the disilicate group, e.max CAD showed the best results in flexural strength (FS) and Vita Suprinity in microhardness (MH) and fracture toughness (FT). In the zirconium oxide group, Incoris exhibited better performance in FS while Razor Zirconia demonstrated superior MH and FT. Eleven studies had low and four had a moderate risk of bias (RoB). Conclusions: Both reinforced vitreous ceramics and zirconia ceramics, when subjected to high temperatures for short periods of time, significantly improve their mechanical properties. Favoring the biomechanical behavior of restorations present in the oral cavity, they are always subjected to constant changes in temperature, forces of different nature, intensity, or direction, changes in acidity, presence of moisture, etc., which make this a difficult environment for their clinical survival. Full article

(This article belongs to the Special Issue CAD & CAM Dentistry)

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