scholarly journals Does Resin Cement Type and Cement Preheating Influence the Marginal and Internal Fit of Lithium Disilicate Single Crowns?

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 424
Author(s):  
Nourhan Samy ◽  
Walid Al-Zordk ◽  
Ahmed Elsherbini ◽  
Mutlu Özcan ◽  
Amal Abdelsamad Sakrana
Keyword(s):  
Lithium Disilicate ◽  
Resin Cement ◽  
The Other ◽  
Cement Type ◽  
Finish Line ◽  
Marginal Fit ◽  
Single Crown ◽  
Significant Difference ◽  
Internal Fit ◽  
Single Crowns

This paper assesses the effect of cement type and cement preheating on the marginal and internal fit of lithium disilicate single crown. Methods: 40 maxillary premolars were selected, restored with lithium disilicate single crowns. Teeth were randomly assigned into four groups (n = 10) based on cement type (Panavia SA or LinkForce) and preheating temperature (25 °C or 54 °C). After fabrication of the restoration, cements were incubated at 25 °C or 54 °C for 24 h, and each crown was cemented to its corresponding tooth. After 24 h, all specimens were thermally aged to (10,000 thermal cycles between 5 °C and 55 °C), then load cycled for 240,000 cycles. Each specimen was then sectioned in bucco-palatal direction and inspected under a stereomicroscope at x45 magnification for marginal and internal fit evaluation. The data were statistically analyzed (significance at p ≤ 0.05 level). Results: At the mid-buccal finish line, mid-buccal wall, palatal cusp, mid-palatal wall, mid-palatal finish line, and palatal margin measuring points, there was a significant difference (p ≤ 0.05) between the lithium disilicate group cemented with Panavia SA at 25 °C and the group cemented with LinkForce at 25 °C, while there was no significant difference (p > 0.05) at the other points. At all measuring points, except at the palatal cusp tip (p = 0.948) and palatal margin (p = 0.103), there was a statistically significant difference (p ≤ 0.05) between the lithium disilicate group cemented with Panavia SA at 54 °C and the group cemented with LinkForce at 54 °C. Regardless of cement preheating, statistically significant differences were found in the buccal cusp tip, central groove, palatal cusp tip, and mid-palatal wall (p ≤ 0.05) in the lithium disilicate group cemented with Panavia SA at 25 °C and 54 °C, as well as the mid-palatal chamfer finish line and palatal margin in the LinkForce group cemented with Panavia SA at 25 °C and 54 °C. At the other measurement points, however, there was no significant difference (p > 0.05). Conclusions: The type of resin cement affects the internal and marginal fit of lithium disilicate crowns. At most measuring points, the cement preheating does not improve the internal and marginal fit of all lithium disilicate crowns.

scholarly journals Evaluation of Mechanical Properties and Marginal Fit of Crowns Fabricated Using Commercially Pure Titanium and FUS-Invest

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Jinshuang Wu ◽  
Xianli Wang ◽  
Helin Xing ◽  
Tianwen Guo ◽  
Chaofang Dong ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Testing Machine ◽  
Pure Titanium ◽  
Commercially Pure Titanium ◽  
Marginal Fit ◽  
Commercially Pure ◽  
Universal Testing ◽  
Single Crown ◽  
Significant Difference ◽  
Internal Fit

This study investigated the mechanical properties and single crown accuracy of the tailor-made Fourth University Stomatology investment (FUS-invest) for casting titanium. Background. Current investment for casting titanium is not optimal for obtaining high-quality castings, and the commercially available titanium investment is costly. Methods. Titanium specimens were cast using the tailor-made FUS-invest. The mechanical properties were tested using a universal testing machine. Fractured castings were characterized by energy-dispersive spectroscopy. 19 titanium crowns were produced using FUS-invest and another 19 by Symbion. The accuracy of crowns was evaluated. Results. The mechanical properties of the titanium cast by FUS-invest were elastic modulus 125.6 ± 8.8 GPa, yield strength 567.5 ± 11.1 MPa, tensile strength 671.2 ± 15.6 MPa, and elongation 4.6 ± 0.2%. For marginal fit, no significant difference (P>0.05) was found at four marker points of each group. For internal fit, no significant difference (P>0.05) was found between two groups, whereas significant difference (P<0.01) was found at different mark point of each group. Conclusions. The mechanical properties of titanium casted using FUS-invest fulfilled the ISO 9693 criteria. The marginal and internal fit of the titanium crowns using either the FUS-invest or Symbion were similar.

scholarly journals Clinical Evaluation of Time Efficiency and Fit Accuracy of Lithium Disilicate Single Crowns between Conventional and Digital Impression

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5467
Author(s):  
Ji-Su Park ◽  
Young-Jun Lim ◽  
Bongju Kim ◽  
Myung-Joo Kim ◽  
Ho-Beom Kwon
Keyword(s):  
Conventional Method ◽  
Statistical Tests ◽  
Statistical Significance ◽  
Lithium Disilicate ◽  
Digital Impression ◽  
Time Efficiency ◽  
Digital Dentistry ◽  
Single Crown ◽  
Significant Difference ◽  
Single Crowns

The purpose of this study was to demonstrate the time-efficiency and the clinical effectiveness of chairside-fabricated lithium disilicate single crowns by digital impressions compared to the conventional method. Thirteen patients requiring a single crown on the maxillary or mandibular premolar or first molar were assigned as study subjects. The impressions were obtained using the conventional method and two digital methods with intraoral scanners: AEGIS.PO (Digital Dentistry Solution, Seoul, Korea) and CEREC Omnicam (Sirona, Bensheim, Germany). Two types of lithium disilicate single crowns were obtained; a reference crown (by conventional workflow) and a chairside crown (by digital workflow). The total time taken for fabricating the chairside crown was recorded. The replica technique was performed to compare the marginal and internal fit of the two types of crowns. In addition, accuracy of the intraoral scanners was evaluated by the best-fit alignment method. The difference between the groups was analyzed using the two-tailed paired t-test or one-way ANOVA, followed by the Student–Newman–Keuls test for multiple comparisons. Statistical significance was accepted at p < 0.05 for all statistical tests. The time required to obtain the impressions by the AEGIS (7:16 ± 1:50 min:s) and CEREC (7:29 ± 2:03 min:s) intraoral scans was significantly lower than the conventional method (12:41 ± 1:16 min:s; p < 0.001). There was no significant difference between the intraoral scanners. The total working time to fabricate the chairside crown averaged 30:58 ± 4:40 min:s. The average marginal gap was not significantly different between the reference (107.86 ± 42.45 µm) and chairside (115.52 ± 38.22 µm) crowns (p > 0.05), based on results of replica measurement. The average internal gaps were not significantly different. The average value of the root mean square between the AEGIS (31.7 ± 12.3 µm) and CEREC (32.4 ± 9.7 µm) scans was not significantly different (p > 0.05). Intraoral scans required a significantly shorter impression time than the conventional method, and it was possible to fabricate a lithium disilicate crown in a single visit. There were no statistically significant differences in the fit of the restorations and accuracy of the intraoral scanners compared to the conventional workflow.

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

2018 ◽  
Vol 12 (1) ◽  
pp. 160-172 ◽  
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.

scholarly journals Does Preheating Resin Cements Affect Fracture Resistance of Lithium Disilicate and Zirconia Restorations?

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5603
Author(s):  
Amal Abdelsamad Sakrana ◽  
Walid Al-Zordk ◽  
Heba El-Sebaey ◽  
Ahmed Elsherbini ◽  
Mutlu Özcan
Keyword(s):  
Fracture Resistance ◽  
Lithium Disilicate ◽  
Resin Cement ◽  
Cement Type ◽  
Mean Values ◽  
Preheating Temperature ◽  
Significant Difference ◽  
Ceramic Restorations ◽  
The Impact ◽  
Adhesive Cement

This paper assesses the impact of preheating of adhesive cement on the fracture resistance of lithium disilicate and zirconia restorations. Methods: A total of 80 human maxillary premolar teeth were assigned into 8 groups (n = 10) according to material type (either lithium disilicate or zirconia) and type of resin cement (either LinkForce or Panavia SA) with preheating temperature at 54 °C or at room temperature (25 °C). Teeth were prepared and restored with either lithium disilicate or zirconia restorations. After cementation, specimens were thermal cycled (10,000 cycles, 5 °C̸55 °C), then load cycled for 240,000 cycles (50 N). Each specimen was statically loaded until fracture and the load (N) at fracture was recorded, then the failure mode was detected. Statistical analysis of data was performed (p ≤ 0.05). Results: There was no significant difference (p = 0.978) in fracture mean values between LinkForce and Panavia SA. Statistically significant difference (p = 0.001) was revealed between fracture resistance of lithium disilicate restorations cemented with LinkForce at 25 °C and at 54 °C; however there was no significant difference (p = 0.92) between the fracture resistance of lithium disilicate restorations cemented with Panavia SA used at 25 °C and at 54 °C. Regarding the interaction between ceramic material, cement type, and cement preheating, there was no significant effect (p > 0.05) in fracture resistance. The cement type does not influence the fracture resistance of ceramic restorations. Preheating of resin cement has negatively influenced the fracture resistance of all tested groups, except for lithium disilicate cemented using LinkForce cement.

scholarly journals Marginal and internal fit and intaglio surface trueness of interim crowns fabricated from tooth preparation of four finish line locations

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Keunbada Son ◽  
Young-Tak Son ◽  
Ji-Min Lee ◽  
Kyu-Bok Lee
Keyword(s):  
Three Dimensional ◽  
Clinical Situation ◽  
Intraoral Scanner ◽  
Replica Technique ◽  
Finish Line ◽  
Marginal Fit ◽  
Tooth Preparation ◽  
The Right ◽  
Internal Fit ◽  
Marginal Region

AbstractThis study evaluated the marginal and internal fit and intaglio surface trueness of interim crowns fabricated from tooth preparation scanned at four finish line locations. The right maxillary first molar tooth preparation model was fabricated using a ceramic material and placed in four finish line locations (supragingival, equigingival, subgingival, and subgingival with a cord). Intraoral scanning was performed. Crowns were designed based on the scanned area. Interim crowns were fabricated using a stereolithography three-dimensional (3D) printer (N = 16 per location). Marginal and internal fit were evaluated with a silicone replica technique. Intaglio surface trueness was evaluated using a 3D inspection software. One-way analysis of variance and Tukey HSD test were performed for comparisons (α = 0.05). The marginal and internal fit showed significant differences according to locations (P < 0.05); the marginal fit showed the best results in the supragingival finish line (P < 0.05). Intaglio surface trueness was significantly different in the marginal region, with the highest value in the subgingival location (P < 0.05). Crowns fabricated on the subgingival finish line caused inaccurate marginal fit due to poor fabrication reproducibility of the marginal region. The use of an intraoral scanner should be decided on the clinical situation and needs.

scholarly journals Effect of ceramic thicknesses and opacities on water sorption and solubility of a light-curing resin cement by different units

2021 ◽  
Vol 20 ◽  
pp. e211656
Author(s):  
Gabriela Alves de Cerqueira ◽  
Lais Sampaio Souza ◽  
Rafael Soares Gomes ◽  
Giselle Maria Marchi ◽  
Paula Mathias
Keyword(s):  
Water Sorption ◽  
Light Emitting Diode ◽  
Lithium Disilicate ◽  
Resin Cement ◽  
The Other ◽  
Experimental Conditions ◽  
Light Emitting ◽  
Light Curing

Aim: This study evaluated the water sorption and solubility of a light-cured resin cement, under four thicknesses and four opacities of a lithium disilicate ceramic, also considering three light-emitting diode (LED) units. Methods: A total of 288 specimens of a resin cement (AllCem Veneer Trans – FGM) were prepared, 96 samples were light-cured by each of the three light curing units (Valo – Ultradent / Radii-Cal – SDI / Bluephase II – Ivoclar Vivadent), divided into 16 experimental conditions, according to the opacities of the ceramic: High Opacity (HO), Medium Opacity (MO), Low Translucency (LT), High Translucency (HT), and thicknesses (0.3, 0.8, 1.5, and 2.0 mm) (n = 6). The specimens were weighed at three different times: Mass M1 (after making the specimens), M2 (after 7 days of storage in water), and M3 (after dissection cycle), for calculating water sorption and solubility. Results: The higher thickness of the ceramic (2.0 mm) significantly increased the values of water sorption (44.0± 4.0) and solubility (7.8±0.6), compared to lower thicknesses. Also, the ceramic of higher opacity (HO) generated the highest values of sorption and solubility when compared to the other opacities, regardless of the thickness tested (ANOVA-3 factors / Tukey’s test, α = 0.05). There was no influence of light curing units. Conclusion: Higher thicknesses and opacities of the ceramic increased the water sorption and solubility of the tested light-cured resin cement.

scholarly journals Effect of Different Thicknesses of Pressable Ceramic Veneers on Polymerization of Light-cured and Dual-cured Resin Cements

2015 ◽  
Vol 16 (5) ◽  
pp. 347-352 ◽  
Author(s):  
Seok-Hwan Cho ◽  
Arnaldo Lopez ◽  
David W Berzins ◽  
Soni Prasad ◽  
Kwang Woo Ahn
Keyword(s):  
Light Intensity ◽  
Vickers Microhardness ◽  
Storage Period ◽  
Degree Of Conversion ◽  
Resin Cement ◽  
Cement Type ◽  
Resin Cements ◽  
Significant Difference ◽  
Ceramic Disk ◽  
Ceramic Thickness

ABSTRACT Aim This study evaluated the effects of ceramic veneer thicknesses on the polymerization of two different resin cements. Materials and methods A total of 80 ceramic veneer disks were fabricated by using a pressable ceramic material (e.max Press; Ivoclar Vivadent) from a Low Translucency (LT) ingot (A1 shade). These disks were divided into light-cured (LC; NX3 Nexus LC; Kerr) and dual-cured (DC; NX3 Nexus DC; Kerr) and each group was further divided into four subgroups, based on ceramic disk thickness (0.3, 0.6, 0.9, and 1.2 mm). The values of Vickers microhardness (MH) and degree of conversion (DOC) were obtained for each specimen after a 24-hour storage period. Association between ceramic thickness, resin cement type, and light intensity readings (mW/cm2) with respect to microhardness and degree of conversion was statistically evaluated by using analysis of variance (ANOVA). Results For the DOC values, there was no significant difference observed among the LC resin cement subgroups, except in the 1.2 mm subgroup; only the DOC value (14.0 ± 7.4%) of 1.2 mm DC resin cement had significantly difference from that value (28.9 ± 7.5%) of 1.2 mm LC resin cement (p < 0.05). For the MH values between LC and DC resin cement groups, there was statistically significant difference (p < 0.05); overall, the MH values of LC resin cement groups demonstrated higher values than DC resin cement groups. On the other hands, among the DC resin cement subgroups, the MH values of 1.2 mm DC subgroup was significantly lower than the 0.3 mm and 0.6 mm subgroups (p < 0.05). However, among the LC subgroups, there was no statistically significant difference among them (p > 0.05). Conclusion The degree of conversion and hardness of the resin cement was unaffected with veneering thicknesses between 0.3 and 0.9 mm. However, the DC resin cement group resulted in a significantly lower DOC and MH values for the 1.2 mm subgroup. Clinical Significance While clinically adequate polymerization of LC resin cement can be achieved with a maximum 1.2 mm of porcelain veneer restoration, the increase of curing time or light intensity is clinically needed for DC resin cements at the thickness of more than 0.9 mm. How to cite this article Cho S-H, Lopez A, Berzins DW, Prasad S, Ahn KW. Effect of Different Thicknesses of Pressable Ceramic Veneers on Polymerization of Lightcured and Dual-cured Resin Cements. J Contemp Dent Pract 2015;16(5):347-352.

scholarly journals Evaluation of Internal Adaptation and Degree of Porosity of Total Crowns After Cementation

2020 ◽  
Vol 22 (4) ◽  
pp. 237-241
Author(s):  
Larissa Dolfini Alexandrino ◽  
Edwin Fernando Ruiz Contreras ◽  
Avacir Casanova Andrello ◽  
Giovani De Oliveira Corrêa
Keyword(s):  
Zinc Phosphate ◽  
Resin Cement ◽  
Marginal Fit ◽  
Partial Denture ◽  
Filling Volume ◽  
Fixed Partial Denture ◽  
Significant Difference ◽  
Lower Porosity ◽  
Internal Adaptation ◽  
Cementing Agent

AbstractThe present study evaluated the marginal fit, the internal filling volume and the degree of porosity in cemented metallic total crowns. Then, 12 metal crowns cast in titanium (Ti) were made on bovine teeth with total preparations and 90° shoulder terminal line. The samples were divided into 4 groups according to the type of cement used and the cementation techniques, 2 groups were used Zinc phosphate (SS White) with the partial insertion of the cementing agent filling the inner crown surface (FP) and total filling (FT), and in the other 2 groups, dual resin cement (RelyX ARC 3M) with the partial insertion of cement (RP) and total insertion (RT) were used. The results showed that cervical marginal fit after cementation was clinically adequate in all groups (<100μm), and for the internal filling volume and porosity were: FP - 99.14% / 0.86%; FT = 98.82% / 1.18%; RP - 97.06% / 2.94% and RT - 97.76% / 2.24%. The statistical analysis was performed by Mann-Whitney test. In conclusion, the two types of cements obtained acceptable values of marginal fit, however, the zinc phosphate cement had better internal fill and lower porosity than the resin cement. Regarding the insertion technique, only the FP and FT groups had a statistically significant difference (p < 0.05) compared to the RP group. Keywords: Fixed Partial Denture. X-Ray Microtomography. Dental Cements. ResumoO presente trabalho avaliou o desajuste marginal, o volume de preenchimento interno e o grau de porosidade em cimentações de coroas totais metálicas. A partir de dentes bovinos com preparos periféricos totais e términos cervicais do tipo ombro de 90º, foram confeccionadas 12 coroas metálicas fundidas em titânio (Ti). As amostras foram divididas em 4 grupos de acordo com o tipo de cimento utilizado e as técnicas de cimentação, dentre estes, em 2 grupos foram usados Fosfato de zinco (SS White) com inserção parcial do agente cimentante preenchendo a superfície interna da coroa (FP) e preenchimento total (FT), e nos outros 2 grupos foram usados Cimento resinoso dual (RelyX ARC 3M) com inserção parcial do cimento (RP) e total (RT). As análises foram feitas por microtomografia computadorizada por raios X. Os resultados mostraram que o desajuste marginal cervical após a cimentação estava adequado clinicamente em todos os grupos (<100µm), e para o volume de preenchimento interno e porosidade foram respectivamente: FP – 99,14%/0,86%; FT – 98,82%/1,18%; RP – 97,06%/2,94% e RT – 97,76%/2,24%. Na análise estatística utilizou-se o teste de Mann-Whitney para amostras independentes. Concluiu-se que os dois tipos de cimentos obtiveram valores aceitáveis de desajuste marginal, contudo o cimento de fosfato de zinco apresentou melhor preenchimento interno e menor porosidade que o cimento resinoso. Em relação à técnica de inserção, apenas os grupos FP e FT tiveram diferença estatística significativa (p<0,05) comparado ao grupo RP. Palavras-chave: Prótese Parcial Fixa. Microtomografia por Raio-X. Cimentos Dentários.  

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

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.

scholarly journals Fracture Resistance and Strain Analysis of Zirconia Copings With Vertical Knife Edge and Three Horizontal Finish Line Designs; Chamfer, Deep Chamfer and Shoulder With Two Cementation Techniques

2021 ◽  
Vol 24 (4) ◽  
Author(s):  
Marwa Emam ◽  
Amr El-Etreby ◽  
Jihan Farouk Younis
Keyword(s):  
Fracture Resistance ◽  
Testing Machine ◽  
Tetragonal Zirconia ◽  
Resin Cement ◽  
Knife Edge ◽  
Glass Ionomer ◽  
Finish Line ◽  
Promising Alternative ◽  
Significant Difference ◽  
Mean Strain

Objective: The purpose of this in vitro study is to evaluate the effect of four finish line configurations and two cement types on the fracture resistance of zirconia copings. Material and Methods: Forty yttrium tetragonal zirconia polycrystals copings were manufactured on epoxy resin dies with four preparation designs: knife edge, chamfer, deep chamfer 0.5, 1 mm and shoulder 1 mm. The copings were cemented with two cement types (glass ionomer and resin cement); (n = 5). Two strain gauges were attached on each coping before they were vertically loaded till fracture with a universal testing machine. Data were analyzed by 2-way analysis of variance ANOVA (p < .05). Fractured specimens were examined for mode of failure with digital microscope. Results: Knife edge showed the highest mean fracture resistance (987.04 ± 94.18) followed by Chamfer (883.28 ± 205.42) followed by Shoulder (828.64 ± 227.79) and finally Deep chamfer finish line (767.66 ± 207.09) with no statistically significant difference. Resin cemented copings had higher mean Fracture resistance (911.76 ± 167.95) than glass ionomer cemented copings (821.55 ± 224.24) with no statistically significant difference. Knife edge had the highest strain mean values on the buccal (374.04 ± 195.43) and lingual (235.80 ± 103.46) surface. Shoulder finish line showed the lowest mean strain values on the buccal (127.47 ± 40.32) and lingual (68.35 ± 80.68) with no statistically significant difference. Resin cemented copings had higher buccal (295.05 ± 167.92) and lingual (197.38 ± 99.85) mean strain values  than glass ionomer copings (149.14 ± 60.94) and (90.27 ± 55.62) with no statistically significant difference. Conclusion: Vertical knife edge finish line is a promising alternative and either adhesive or conventional cementation can be used with zirconia copings.   KEYWORDS Cementation; Flexural strength; Prosthodontics; Tooth preparation; Zirconium.

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