Influence of Manufacturing Methods of Implant-Supported Crowns on External and Internal Marginal Fit: A Micro-CT Analysis

Aim.To evaluate the influence of different manufacturing methods of single implant-supported metallic crowns on the internal and external marginal fit through computed microtomography.Methods.Forty external hexagon implants were divided into 4 groups(n=8), according to the manufacturing method: GC, conventional casting; GI, induction casting; GP, plasma casting; and GCAD, CAD/CAM machining. The crowns were attached to the implants with insertion torque of 30 N·cm. The external (vertical and horizontal) marginal fit and internal fit were assessed through computed microtomography. Internal and external marginal fit data (μm) were submitted to a one-way ANOVA and Tukey’s test(α=.05). Qualitative evaluation of the images was conducted by using micro-CT.Results.The statistical analysis revealed no significant difference between the groups for vertical misfit(P=0.721). There was no significant difference(P>0.05)for the internal and horizontal marginal misfit in the groups GC, GI, and GP, but it was found for the group GCAD(P≤0.05). Qualitative analysis revealed that most of the samples of cast groups exhibited crowns underextension while the group GCAD showed overextension.Conclusions.The manufacturing method of the crowns influenced the accuracy of marginal fit between the prosthesis and implant. The best results were found for the crowns fabricated through CAD/CAM machining.

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Digital Procedures Compared to Conventional Gypsum Casts in the Manufacturing of CAD/CAM Adhesive Restorations: 3D Surface Trueness and Interfacial Adaptation Analysis

Applied Sciences ◽

10.3390/app11115060 ◽

2021 ◽

Vol 11 (11) ◽

pp. 5060

Author(s):

Andrea Baldi ◽

Allegra Comba ◽

Edoardo Alberto Vergano ◽

Michail L. Vakalis ◽

Mario Alovisi ◽

...

Keyword(s):

Ct Scan ◽

Ex Vivo ◽

Micro Ct ◽

Marginal Fit ◽

Cad Cam ◽

Ct Analysis ◽

3D Printed ◽

Tooth Preparation ◽

Internal Fit ◽

Ex Vivo Study

Objective. The purpose of this ex vivo study was to compare the trueness of traditional and digital workflows and to analyze the interfacial fit of CAD/CAM restorations on gypsum and 3D-printed casts (3DC). Methods: Forty patients underwent indirect posterior adhesive restorations. After tooth preparation, both traditional and chairside procedures were followed. Obtained models were scanned to generate STL files of the intraoral impression (IOS), the conventional cast (RS), and the 3D-printed cast (3DCS). Superimposition of the casts was performed to evaluate trueness. Then, for each preparation, two identical CAD/CAM restorations were milled and luted on RS and 3DC. Micro-CT scan was performed to evaluate 3D interfacial fit. Results. Surface trueness analysis showed no significant differences among groups (p > 0.05), with average trueness ranging from 11.56 to 17.01 µm. Micro-CT analysis showed significant differences between gypsum casts (average ranging from 135.78 to 212.31 µm) and 3DC (average ranging from 57.63 to 144.55 µm) for both marginal and internal fit. Conclusions. In adhesive restorations manufacturing, digital and conventional procedures generate casts that are not significantly different. Marginal fit of adhesive restorations is similar to conventional crown design and clinically acceptable. It is assumable that a direct digital workflow could benefit from the usage of 3DC.

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Comparison of Mechanical Properties of PMMA Disks for Digitally Designed Dentures

Polymers ◽

10.3390/polym13111745 ◽

2021 ◽

Vol 13 (11) ◽

pp. 1745

Author(s):

Tamaki Hada ◽

Manabu Kanazawa ◽

Maiko Iwaki ◽

Awutsadaporn Katheng ◽

Shunsuke Minakuchi

Keyword(s):

Mechanical Properties ◽

Flexural Strength ◽

Water Sorption ◽

Water Solubility ◽

Flexural Modulus ◽

Manufacturing Method ◽

Heat Curing ◽

Significant Difference ◽

Cad Cam ◽

Curing Method

In this study, the physical properties of a custom block manufactured using a self-polymerizing resin (Custom-block), the commercially available CAD/CAM PMMA disk (PMMA-disk), and a heat-polymerizing resin (Conventional PMMA) were evaluated via three different tests. The Custom-block was polymerized by pouring the self-polymerizing resin into a special tray, and Conventional PMMA was polymerized with a heat-curing method, according to the manufacturer’s recommended procedure. The specimens of each group were subjected to three-point bending, water sorption and solubility, and staining tests. The results showed that the materials met the requirements of the ISO standards in all tests, except for the staining tests. The highest flexural strength was exhibited by the PMMA-disk, followed by the Custom-block and the Conventional PMMA, and a significant difference was observed in the flexural strengths of all the materials (p < 0.001). The Custom-block showed a significantly higher flexural modulus and water solubility. The water sorption and discoloration of the Custom-block were significantly higher than those of the PMMA-disk, but not significantly different from those of the Conventional PMMA. In conclusion, the mechanical properties of the three materials differed depending on the manufacturing method, which considerably affected their flexural strength, flexural modulus, water sorption and solubility, and discoloration.

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The comparative Micro-CT analysis on trabecular bone density between hydroxyapatite gypsum puger scaffold application and bovine hydroxyapatite scaffold application

Dental Journal (Majalah Kedokteran Gigi) ◽

10.20473/j.djmkg.v54.i1.p11-15 ◽

2021 ◽

Vol 54 (1) ◽

pp. 11

Author(s):

Amiyatun Naini

Keyword(s):

Bone Density ◽

Trabecular Bone ◽

Wistar Rats ◽

Micro Ct ◽

Trabecular Bone Density ◽

Bone Damage ◽

Significant Difference ◽

Ct Analysis ◽

Bovine Hydroxyapatite ◽

Test Result

Background: Generally, after tooth extraction, trauma is caused by bone damage, which leads to a decreased bone density. Bone damage repair should be conducted using a bone graft containing hydroxyapatite (HA). HA can be synthesised from gypsum puger powder, which is abundant and easy to obtain. Hydroxyapatite gypsum puger (HAGP) was successful with 100% hydroxyapatite purity level. Purpose: To compare the ratio of trabecular bone density in Wistar rats between HAGP scaffold application and bovine hydroxyapatite (BHA) scaffold application. Methods: This study is a laboratory experiment using 6 treatment groups, namely K (-) polyethylene glycol (PEG) 7, K (-) PEG 28, HAGP + PEG 7, HAGP + PEG 28, BHA + PEG 7, and BHA + PEG 28. HAGP scaffold freeze-drying. The rats were anaesthetised intramuscularly, and their left mandibular incisor was removed. The scaffold was applied to the mouse socket, followed by tissue decapitation after 7 and 28 days. The examination was carried out with micro-computed tomography (Micro-CT). Next, statistical analysis using a one-way analysis of variance (ANOVA) test was conducted (p <0.05). Results: The ANOVA test result showed a difference in bone density between the treatment and control groups on days 7 and 28. The Least Significant Difference (LSD) test result revealed that there was no significant difference between K (-) PEG 28 and HAGP + PEG 7 (p=0.133). Nevertheless, there were significant differences between the other groups. Conclusion: Based on the Micro-CT analysis, the trabecular bone density in Wistar rats following HAGP scaffold application is higher than that of BHA scaffold application.

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In Vitro Comparison of Marginal and Internal Fit of Zirconia Copings Fabricated by One CAD/CAM System with Two Different Scanners

Frontiers in Dentistry ◽

10.18502/fid.v18i2.5432 ◽

2021 ◽

Author(s):

Zahra Khamverdi1 ◽

Elmira Najafrad ◽

Maryam Farhadian

Keyword(s):

T Test ◽

Marginal Fit ◽

Significant Difference ◽

Computer Aided ◽

Cad Cam ◽

Zirconia Crowns ◽

Monolithic Zirconia ◽

The Mean ◽

Internal Fit ◽

Paired T Test

Objectives: Marginal and internal fit of restorations are two important clinical factors for assessing the quality and durability of computer-aided design/computer-aided manufacturing (CAD/CAM)-fabricated monolithic zirconia restorations. The purpose of this study was to evaluate the marginal and internal fit of CAD/CAM zirconia crowns with two different scanners (i3D scanner and 3Shape D700). Materials and Methods: Twelve extracted sound human posterior teeth were prepared for full zirconia crowns. Two different extraoral scanners namely i3D scanner and 3Shape D700 were used to digitize type IV gypsum casts poured from impressions. The crowns were milled from presintered monolithic zirconia blocks by a 5-axis milling machine. The replica technique and MIP4 microscopic image analysis software were utilized to measure the marginal and internal fit by a stereomicroscope at ×40 magnification. The collected data were analyzed by paired t-test. Results: The mean marginal gap was 203.62 μm with 3Shape D700 scanner and 241.07 μm with i3D scanner. The mean internal gap was 192.30 μm with 3Shape D700 scanner and 196.06 μm with i3D scanner. The results of paired t-test indicated that there was a statistically significant difference between the two scanners in marginal fit (P=0.04); while, there was no statistically significant difference in internal fit (P=0.761). Conclusion: Within the limitations of this study, the results showed that type of extraoral scanner affected the marginal fit of CAD/CAM fabricated crowns; however, it did not have a significant effect on their internal fit.

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Marginal Fit Evaluation of CAD/CAM All Ceramic Crowns Obtained by Two Digital Workflows: An In Vitro Study Using Micro‐CT Technology

Journal of Prosthodontics ◽

10.1111/jopr.13115 ◽

2019 ◽

Vol 28 (9) ◽

pp. 1037-1043 ◽

Cited By ~ 3

Author(s):

Ibrahim Salim Duqum ◽

Christian Brenes ◽

Gustavo Mendonca ◽

Thiago Almedia Prado Naves Carneiro ◽

Lyndon F. Cooper

Keyword(s):

In Vitro Study ◽

Vitro Study ◽

Micro Ct ◽

Marginal Fit ◽

All Ceramic ◽

Cad Cam ◽

Ct Technology ◽

Ceramic Crowns

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Effectiveness of Different Mechanical Methods on Dentin Caries Removal: Micro-CT and Digital Image Evaluation

Operative Dentistry ◽

10.2341/13-278-l ◽

2015 ◽

Vol 40 (3) ◽

pp. 263-270 ◽

Cited By ~ 5

Author(s):

C Ferraz ◽

AR Freire ◽

JS Mendonça ◽

CAO Fernandes ◽

JC Cardona ◽

...

Keyword(s):

Digital Image ◽

Minimal Invasive ◽

Micro Ct ◽

Invasive Potential ◽

Occlusal Caries ◽

Mechanical Methods ◽

Computed Microtomography ◽

Ct Analysis ◽

Caries Removal ◽

Caries Excavation

SUMMARY Purpose To determine the caries removal effectiveness (CRE) and minimal invasive potential (MIP) of caries excavation methods using digital imaging and microtomography analyses. Methods Twelve human molars with occlusal caries lesions in dentin were randomly divided into three groups (carbide bur, exacavator, and polymer bur). They were sectioned mesiodistally, and standardized digital and computed microtomography x-ray (micro-CT) images were taken from each section before and after caries excavation. On each image, initial carious dentin (IC), prepared cavity (PC), and residual caries (RC) were defined according to visual criteria using ImageJ software. CRE was determined based on the RC/IC ratio, whereas MIP was determined by the PC/IC ratio. Data were analyzed using one-way analysis of variance and Student t-test or with Kruskal-Wallis and Student-Newman-Keuls test. The level of significance was set at 0.05. Results For both digital image and micro-CT analysis, the carbide bur showed higher CRE values than the excavator (p=0.0063 and p=0.0263, respectively) and the polymer bur (p=0.0028 and p=0.0005, respectively). The latter two presented similar results (p>0.05). Regarding MIP, for the digital image analysis, the polymer bur was different from the carbide bur (p=0.0030) but was not different from that of the excavator (p=0.1240). For micro-CT analysis, the MIP values of all the groups were significantly different, and the polymer bur was the most conservative method (p<0.05). Conclusions The carbide bur was the most effective method for caries removal but was not completely conservative. The polymer bur and excavator presented low invasive potential but were not able to remove all of the carious dentin.

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Evaluation of the Bond Strengths between Dental Porcelain and Cobalt-Chromium Metal Frameworks Manufactured with Different Techniques after the Thermal Aging Process

Scanning ◽

10.1155/2020/9315236 ◽

2020 ◽

Vol 2020 ◽

pp. 1-9

Author(s):

Elif Ece Yoldan ◽

Nurullah Türker ◽

Ulviye Ş. Büyükkaplan ◽

Mehmet M. Özarslan ◽

Recep Karalı ◽

...

Keyword(s):

Bond Strength ◽

Thermal Aging ◽

Aging Process ◽

Bending Test ◽

Single Type ◽

Cobalt Chromium ◽

Dental Porcelain ◽

Manufacturing Method ◽

Significant Difference ◽

Cad Cam

Purpose. The present study is aimed at examining the bond strength of cobalt-chromium (Co-Cr) metal frameworks, prepared through different techniques, to a single type of low-temperature porcelain system after the thermal aging process. Methods. A hundred and twenty Co-Cr alloy framework specimens were prepared using conventional casting, CAD/CAM, and two commercially different laser sintering devices, and dental porcelain was applied to the specimens. A single type of dental porcelain (Kuraray Noritake Dental Inc., Tokyo, Japan) was applied to the specimens. After the subgroups were determined, half of the specimens were subjected to a thermal aging process. Bond strength of specimens was evaluated using a 3-point bending test. The surfaces of the fractured specimens were evaluated using a stereomicroscope. The metal-porcelain bonding area of samples randomly selected from 8 groups has been examined with SEM under ×1000 magnifications. Normality distribution of obtained data was examined using by a Kolmogorov-Smirnov test. The obtained data of the present study was statistically analyzed with a statistical package program (SPSS for Windows 22.0, Chicago, IL, USA). Results. There was a statistically significant difference between CAD/CAM and the other three methods, and the bonding value of the CAD/CAM group was the highest among the groups. Besides, the bond strength between dental porcelain and 4 differently produced metal frameworks was high enough to surpass the acceptable threshold (>25 MPa) according to the ISO 9693. There was no statistically significant difference between thermal aging applied and nonapplied groups. Conclusions. Based on this study, it could be shown that the metal-ceramic bond strength is dependent on the manufacturing method used, but it is independent of the thermal aging application. It was found that the bond strength values of all samples with and without thermal aging application exceeded the minimum acceptable value of 25 MPa recommended by the ISO 9693.

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Marginal Fit of Implant-Supported All-Ceramic Zirconia Frameworks

Journal of Oral Implantology ◽

10.1563/aaid-joi-d-11-00103 ◽

2013 ◽

Vol 39 (4) ◽

pp. 417-424 ◽

Cited By ~ 12

Author(s):

Hanaa Hassan Zaghloul ◽

Jihan Farouk Younis

Keyword(s):

Cyclic Loading ◽

Computer Aided Design ◽

Control Group ◽

Marginal Gap ◽

Marginal Fit ◽

Mean Values ◽

Significant Difference ◽

All Ceramic ◽

Computer Aided ◽

Cad Cam

This study evaluated the effect of fabrication techniques and cyclic loading on the vertical marginal fit of implant-supported fixed partial denture (FPD) frameworks. Thirty implant-supported 3-unit FPD frameworks were fabricated on a model system, divided into 3 equal groups (n = 10). The first group (control) was constructed from base metal alloy; the other 2 test groups were constructed from all-ceramic zirconia using a computer-aided design/computer-aided manufacturing (CAD/CAM) Cerec 3 system and a copy milling (Zirkonzahn) system. A cyclic load of 200 N was applied to each framework for up to 50,000 cycles. Linear measurements were made in micrometers of the vertical gap between the framework and the implant-supported abutment at 16 predetermined points before and after cyclic loading. The frameworks were viewed using scanning electron microscopy to inspect any fractographic features. One-way analysis of variance was performed to compare the marginal discrepancy values of the control and the 2 test groups and for each group; a t test was applied to determine whether significant changes in the fit were observed after cyclic loading (α = 0.05). The CAD/CAM group showed significantly higher marginal gap mean values (80.58 μm) than the Zirkonzahn and control groups (50.33 μm and 42.27 μm, respectively) with no significant difference. After cyclic loading, the CAD/CAM group recorded the highest marginal gap mean value (91.50 ± 4.260 μm) followed by control group (72.00 ± 2.795 μm); the Zirkonzahn group recorded the lowest marginal gap (65.37 ± 6.138 μm). Cyclic loading significantly increased the marginal gap mean values in the control group only. A marginal chip was observed in one of the CAD/CAM ceramic frameworks. Within the limitations of this study, the fabrication technique influenced the marginal fit of the implant-supported 3-unit FPD frameworks. Cyclic loading failed to change the fit of all-ceramic zirconia frameworks, whereas significant changes were found in the metal frameworks.

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In vitro Evaluation of the Marginal Fit and Internal Adaptation of Zirconia and Lithium Disilicate Single Crowns: Micro-CT Comparison Between Different Manufacturing Procedures

The Open Dentistry Journal ◽

10.2174/1874210601812010160 ◽

2018 ◽

Vol 12 (1) ◽

pp. 160-172 ◽

Cited By ~ 11

Author(s):

Francesco Riccitiello ◽

Massimo Amato ◽

Renato Leone ◽

Gianrico Spagnuolo ◽

Roberto Sorrentino

Keyword(s):

Clinical Success ◽

Lithium Disilicate ◽

Resin Cement ◽

Micro Ct ◽

Marginal Fit ◽

Restorative Materials ◽

Cad Cam ◽

Internal Adaptation ◽

Single Crowns

Background:Prosthetic precision can be affected by several variables, such as restorative materials, manufacturing procedures, framework design, cementation techniques and aging. Marginal adaptation is critical for long-term longevity and clinical success of dental restorations. Marginal misfit may lead to cement exposure to oral fluids, resulting in microleakage and cement dissolution. As a consequence, marginal discrepancies enhance percolation of bacteria, food and oral debris, potentially causing secondary caries, endodontic inflammation and periodontal disease.Objective:The aim of the presentin vitrostudy was to evaluate the marginal and internal adaptation of zirconia and lithium disilicate single crowns, produced with different manufacturing procedures.Methods:Forty-five intact human maxillary premolars were prepared for single crowns by means of standardized preparations. All-ceramic crowns were fabricated with either CAD-CAM or heat-pressing procedures (CAD-CAM zirconia, CAD-CAM lithium disilicate, heat-pressed lithium disilicate) and cemented onto the teeth with a universal resin cement. Non-destructive micro-CT scanning was used to achieve the marginal and internal gaps in the coronal and sagittal planes; then, precision of fit measurements were calculated in a dedicated software and the results were statistically analyzed.Results:The heat-pressed lithium disilicate crowns were significantly less accurate at the prosthetic margins (p<0.05) while they performed better at the occlusal surface (p<0.05). No significant differences were noticed between CAD-CAM zirconia and lithium disilicate crowns (p>0.05); nevertheless CAD-CAM zirconia copings presented the best marginal fit among the experimental groups. As to the thickness of the cement layer, reduced amounts of luting agent were noticed at the finishing line, whereas a thicker layer was reported at the occlusal level.Conclusion:Within the limitations of the presentin vitroinvestigation, the following conclusions can be drawn: the recorded marginal gaps were within the clinical acceptability irrespective of both the restorative material and the manufacturing procedures; the CAD-CAM processing techniques for both zirconia and lithium disilicate produced more consistent marginal gaps than the heat-pressing procedures; the tested universal resin cement can be safely used with both restorative materials.

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Evaluation of Marginal Gap / Fit of Zirconia Copings & Full Contoured Monolith Zirconia Crowns (CAD / CAM) - A Comparative In-Vitro Study

Journal of Evolution of Medical and Dental Sciences ◽

10.14260/jemds/2021/311 ◽

2021 ◽

Vol 10 (20) ◽

pp. 1483-1488

Author(s):

Liya Zacharias

Keyword(s):

Experimental Study ◽

P Value ◽

Marginal Gap ◽

Marginal Fit ◽

Type Iv ◽

Significant Difference ◽

Cad Cam ◽

Zirconia Crowns ◽

Group 2

BACKGROUND Inadequate marginal fit of fixed restorations leads to plaque accumulation, recurrent caries and periodontal problems. The purpose of this experimental study is to evaluate and compare the marginal fit/gap of computer-aided design and computeraided manufacturing (CAD/CAM) fabricated zirconia copings and zirconia full contoured monolith crowns fabricated on type IV gypsum die having a definite cement spacer thickness of 0.05mm. METHODS This is an in-vitro experimental study carried out from November 2018 to November 2019. A master stainless steel die was used to make 52 type IV die stone models which were randomly divided into 2 groups of 26 samples each. Group 1: zirconia copings and group 2: zirconia monolith full contoured crowns. These restotations were fabricated using CAD/CAM. The marginal gap of each zirconia copings and zirconia full contoured crowns was assessed using scanning electron microscopic analysis on four different pre-marked points (GEMINI SEM 500; ZEISS). Observations were tabulated and analyzed statistically. Independent t-test was used to compare the measurements between zirconia copings & zirconia monolith crowns. RESULTS The least marginal gap observed was for group 2 (zirconia full contoured crown) with a mean value of 29.88 ± 9.16 μm while that of group1 (zirconia coping) was 73.64 ± 28.13 μm. There was a statistically significant difference in the measurements between zirconia copings and zirconia full contoured monolith crowns (P - value < 0.001). There was statistically significant difference in each side of zirconia monolith crowns when compared to the corresponding side of zirconia copings (P - Value < 0.001). CONCLUSIONS CAD/CAM milled full contoured zirconia crowns showed least marginal discrepancy when compared to zirconia copings. All samples had marginal gap within the clinically acceptable range of 120 μm. KEY WORDS Monolith, Zirconia Crowns, Zirconia Copings, Full Contoured Crowns, CAD-CAM

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