Statement of the problem: Delayed loading is one of the anxieties of implant patients. Immediate ... more Statement of the problem: Delayed loading is one of the anxieties of implant patients. Immediate loading can solve the problem and make patients more satisfied. Purpose: The present study was aimed to compare the marginal bone level in periapical radiographs of maxi implants under different loading (immediate and delayed) patterns. Materials and methods: This split mouth experimental study included 2 dogs. Impressions were made and then, all premolars were extracted under general anesthesia. After a three month healing period, 3 implants were inserted in each quadrant (24 implants). Anterior and posterior implants (case group) were splinted by an acrylic temporary bridge. In order to make middle implants (control group) off the occlusion, parallel long cone technique was used to assess the marginal bone level at base line and 42 days post loading. Data were analyzed using t- test (α=0.05). Results: Mean bone loss values for the case and the control groups were respectively -0.52±0.5...
Journal of Dentistry of Tehran University of Medical Sciences, 2017
Zirconia restorations have been suggested as a more durable and more appealing alternative to met... more Zirconia restorations have been suggested as a more durable and more appealing alternative to metal restorations. However, their mechanical properties may be negatively affected by fatigue due to superficial stresses or low temperature degradation. This study aimed to assess the fatigue fracture strength of three-unit implant-supported full contour zirconia and pre-sintered cobalt-chromium (Co-Cr) alloy posterior fixed partial dentures (FPDs). In this in-vitro experimental study, 28 posterior three-unit implant-supported FPDs were fabricated of full contour zirconia and pre-sintered Co-Cr alloy, and were cemented on implant abutments. To simulate the oral environment, FPDs were subjected to 10,000 thermal cycles between 5-55°C for 30 seconds, and were then transferred to a chewing simulator (100,000 cycles, 50 N, 0.5 Hz). Afterwards, fatigue fracture strength was measured using a universal testing machine. Data were analyzed by Mann-Whitney U test. The mean and standard deviation of...
Background and objectives: One of the simplest and cheapest attachments for overdentures, is the ... more Background and objectives: One of the simplest and cheapest attachments for overdentures, is the ball-type attachment, however, keeping it during the first year of prosthesis delivery and after that is one of the main concerns of dentists. The present study aimed to assess the wear of matrix in overdentures attachment supported by one, two and three implants in the mandible. Materials and methods: Thirty edentulous patients were randomly divided into three groups: the first group received a single implant in the midline of the lower mandible, the second group two implants in areas B and D, and the third group three implants in areas B, C, and D. The attachment used in patients’ prosthetic with single and two implants was O-ball/ring attachment and for patients with three implants, the treatment plan was ball bar-supported attachments. After placing the new matrix implant for each patient and obtaining their consent, the matrix wear was measured with CMM (Coordinate Measuring Machine...
Objectives: The aim of this study was to assess and compare the water sorption and flexural stren... more Objectives: The aim of this study was to assess and compare the water sorption and flexural strength of thermoplastic and conventional acrylic resins. Materials and Methods: Water sorption and flexural strength were compared between a thermoplastic modified polymethyl methacrylate (PMMA) denture base resin (group A) and a heat-polymerized PMMA acrylic resin (group B) as the control group (n=10). A three-point bending test was carried out for flexural strength testing. For water sorption test, 10 disc-shaped samples were prepared. After desiccating, the samples were weighed and immersed in distilled water for seven days. Then, they were weighed again, and desiccated for the second and third times. Differences between the mean values in the two groups were analyzed using Student’s t-test. Results: The mean value of water sorption was 14.74±1.36 μg/mm3 in group A, and 19.11±0.90 μg/mm3 in group B; this difference was statistically significant (P< 0.001). The mean value of flexural s...
Incontinentia pigmenti is a rare inherited disorder involving abnormalities of the skin, hair, ey... more Incontinentia pigmenti is a rare inherited disorder involving abnormalities of the skin, hair, eyes, musculoskeletal system, central nervous system, and the teeth. Dental abnormalities are the most common manifestations of this disorder. The purpose of this case report was to present the clinical and radiological findings of a seven-year-old girl as well as the results of her five-year follow up. The patient showed faded linear pigmented macular lesions on the trunk and on upper and lower limbs. Dental examination was notable for conical and peg-shaped anterior teeth as well as delayed eruption of primary and permanent teeth. In addition to conservative treatments, prosthetic treatments such as interim removable partial dentures were indicated for the patient.
Statement of the Problem: The mechanisms of operation of dental scanners are based on different t... more Statement of the Problem: The mechanisms of operation of dental scanners are based on different technologies. Considering these differences, there are many types of scanners available in the market. Purpose: This in vitro study aimed to compare the accuracy (precision and trueness) of seven commonly used dental scanners. Materials and Method: In this in vitro experimental study, the accuracy of 7 common extra oral scanners (Sirona ineos inLab, Sirona X5, Dentium, Imes Icore 350I, Amann Girrbach, 3shape D700, and 3Shape E3) were evaluated. Each of scanners performed 7 scans of implant abutment of SIC (SIC MAX.GH1). Data from each scanner were then compared to data received from 3Shape Trios intra oral scanner as a reference. For evaluating the accuracy of each scanner, trueness and precision was evaluated. Collected data were analyzed using Kruskal Wallis and Bonferroni tests via SPSS version 22. Results: Descriptive statistics showed the best trueness was for 3Shape E3 scanner with ...
Objectives: Obtaining an adequate ceramic thickness to mask the substructure color is not always ... more Objectives: Obtaining an adequate ceramic thickness to mask the substructure color is not always feasible, and appropriate use of a cement may be the only solution. This study aimed to evaluate the effect of the color of Variolink II resin cement on the final color of lithium disilicate glass ceramic restorations. Materials and Methods: In this in-vitro study, 90 discs of IPS e.max Press ceramic were evaluated. The ceramic discs were cemented to composite and amalgam blocks. The effect of the cement color and substructure on the final color of ceramic was analyzed by calculating the color change (ΔE) value using a spectrophotometer. Data were analyzed via three-way analysis of variance (ANOVA) and Tukey’s test. Results: The cement color had a statistically significant effect on the final color of ceramic (P≤0.001). The white, yellow, and translucent cements caused the highest color change (ΔE=4.558, 3.308, and 2.649, respectively). The effect of composite substructure and the yellow...
Open Access Macedonian Journal of Medical Sciences, 2020
BACKGROUND: Metal-ceramics restorations were considered a preferable option for fabrication fixed... more BACKGROUND: Metal-ceramics restorations were considered a preferable option for fabrication fixed partial dentures (FPDs) that have an acceptable durability, but they are not able to provide the same beauty as the entire ceramic material. Full-contour zirconia, such as Zolid, does not have problems with chipping of layered zirconia, along with translucency and staining capabilities. AIM: This study aimed to assess the fatigue fracture strength of three-unit implant-supported full-contour zirconia and metal-ceramics posterior FPDs. MATERIALS AND METHODS: In this in vitro study, 24 posterior three-unit implant-supported FPDs were fabricated of full-contour zirconia and metal-ceramics and were cemented on implant abutments. To simulate the oral environment, FPDs were subjected to 10,000 thermal cycles between 5 and 55°C for 30 s and were then transferred to a chewing simulator (100,000 cycles, 50 N, 0.5 Hz). Afterward, fatigue fracture strength was measured using a universal testing ma...
Introduction: The purpose of this study was to investigate the effect of flask investment materia... more Introduction: The purpose of this study was to investigate the effect of flask investment materials on the color changes of different brands of resin denture teeth. Methods: Resin denture teeth (560) were divided into 2 groups according to the materials used for flask investment (silicone or gypsum). All the specimens were thermocycled between 4°C and 60°C with 60-s dwell times for 1,000 cycles. Subsequently, the specimens of each group were divided into 4 subgroups based on the immersion media: coffee, tea, cola, and distilled water. Digital images of the teeth were taken before immersion and 30 days after immersion. The color samples were measured using the CIE L*a*b* system, and color differences (∆E) were calculated. The data were evaluated by three ways ANOVA and the Tukey HSD test. Results: There was not a significant difference in ∆E using three-way ANOVA, while the results showed considerable statistical differences with two factor ANOVA interaction. The ∆E values in the sil...
Statement of the problem: Delayed loading is one of the anxieties of implant patients. Immediate ... more Statement of the problem: Delayed loading is one of the anxieties of implant patients. Immediate loading can solve the problem and make patients more satisfied. Purpose: The present study was aimed to compare the marginal bone level in periapical radiographs of maxi implants under different loading (immediate and delayed) patterns. Materials and methods: This split mouth experimental study included 2 dogs. Impressions were made and then, all premolars were extracted under general anesthesia. After a three month healing period, 3 implants were inserted in each quadrant (24 implants). Anterior and posterior implants (case group) were splinted by an acrylic temporary bridge. In order to make middle implants (control group) off the occlusion, parallel long cone technique was used to assess the marginal bone level at base line and 42 days post loading. Data were analyzed using t- test (α=0.05). Results: Mean bone loss values for the case and the control groups were respectively -0.52±0.5...
Journal of Dentistry of Tehran University of Medical Sciences, 2017
Zirconia restorations have been suggested as a more durable and more appealing alternative to met... more Zirconia restorations have been suggested as a more durable and more appealing alternative to metal restorations. However, their mechanical properties may be negatively affected by fatigue due to superficial stresses or low temperature degradation. This study aimed to assess the fatigue fracture strength of three-unit implant-supported full contour zirconia and pre-sintered cobalt-chromium (Co-Cr) alloy posterior fixed partial dentures (FPDs). In this in-vitro experimental study, 28 posterior three-unit implant-supported FPDs were fabricated of full contour zirconia and pre-sintered Co-Cr alloy, and were cemented on implant abutments. To simulate the oral environment, FPDs were subjected to 10,000 thermal cycles between 5-55°C for 30 seconds, and were then transferred to a chewing simulator (100,000 cycles, 50 N, 0.5 Hz). Afterwards, fatigue fracture strength was measured using a universal testing machine. Data were analyzed by Mann-Whitney U test. The mean and standard deviation of...
Background and objectives: One of the simplest and cheapest attachments for overdentures, is the ... more Background and objectives: One of the simplest and cheapest attachments for overdentures, is the ball-type attachment, however, keeping it during the first year of prosthesis delivery and after that is one of the main concerns of dentists. The present study aimed to assess the wear of matrix in overdentures attachment supported by one, two and three implants in the mandible. Materials and methods: Thirty edentulous patients were randomly divided into three groups: the first group received a single implant in the midline of the lower mandible, the second group two implants in areas B and D, and the third group three implants in areas B, C, and D. The attachment used in patients’ prosthetic with single and two implants was O-ball/ring attachment and for patients with three implants, the treatment plan was ball bar-supported attachments. After placing the new matrix implant for each patient and obtaining their consent, the matrix wear was measured with CMM (Coordinate Measuring Machine...
Objectives: The aim of this study was to assess and compare the water sorption and flexural stren... more Objectives: The aim of this study was to assess and compare the water sorption and flexural strength of thermoplastic and conventional acrylic resins. Materials and Methods: Water sorption and flexural strength were compared between a thermoplastic modified polymethyl methacrylate (PMMA) denture base resin (group A) and a heat-polymerized PMMA acrylic resin (group B) as the control group (n=10). A three-point bending test was carried out for flexural strength testing. For water sorption test, 10 disc-shaped samples were prepared. After desiccating, the samples were weighed and immersed in distilled water for seven days. Then, they were weighed again, and desiccated for the second and third times. Differences between the mean values in the two groups were analyzed using Student’s t-test. Results: The mean value of water sorption was 14.74±1.36 μg/mm3 in group A, and 19.11±0.90 μg/mm3 in group B; this difference was statistically significant (P< 0.001). The mean value of flexural s...
Incontinentia pigmenti is a rare inherited disorder involving abnormalities of the skin, hair, ey... more Incontinentia pigmenti is a rare inherited disorder involving abnormalities of the skin, hair, eyes, musculoskeletal system, central nervous system, and the teeth. Dental abnormalities are the most common manifestations of this disorder. The purpose of this case report was to present the clinical and radiological findings of a seven-year-old girl as well as the results of her five-year follow up. The patient showed faded linear pigmented macular lesions on the trunk and on upper and lower limbs. Dental examination was notable for conical and peg-shaped anterior teeth as well as delayed eruption of primary and permanent teeth. In addition to conservative treatments, prosthetic treatments such as interim removable partial dentures were indicated for the patient.
Statement of the Problem: The mechanisms of operation of dental scanners are based on different t... more Statement of the Problem: The mechanisms of operation of dental scanners are based on different technologies. Considering these differences, there are many types of scanners available in the market. Purpose: This in vitro study aimed to compare the accuracy (precision and trueness) of seven commonly used dental scanners. Materials and Method: In this in vitro experimental study, the accuracy of 7 common extra oral scanners (Sirona ineos inLab, Sirona X5, Dentium, Imes Icore 350I, Amann Girrbach, 3shape D700, and 3Shape E3) were evaluated. Each of scanners performed 7 scans of implant abutment of SIC (SIC MAX.GH1). Data from each scanner were then compared to data received from 3Shape Trios intra oral scanner as a reference. For evaluating the accuracy of each scanner, trueness and precision was evaluated. Collected data were analyzed using Kruskal Wallis and Bonferroni tests via SPSS version 22. Results: Descriptive statistics showed the best trueness was for 3Shape E3 scanner with ...
Objectives: Obtaining an adequate ceramic thickness to mask the substructure color is not always ... more Objectives: Obtaining an adequate ceramic thickness to mask the substructure color is not always feasible, and appropriate use of a cement may be the only solution. This study aimed to evaluate the effect of the color of Variolink II resin cement on the final color of lithium disilicate glass ceramic restorations. Materials and Methods: In this in-vitro study, 90 discs of IPS e.max Press ceramic were evaluated. The ceramic discs were cemented to composite and amalgam blocks. The effect of the cement color and substructure on the final color of ceramic was analyzed by calculating the color change (ΔE) value using a spectrophotometer. Data were analyzed via three-way analysis of variance (ANOVA) and Tukey’s test. Results: The cement color had a statistically significant effect on the final color of ceramic (P≤0.001). The white, yellow, and translucent cements caused the highest color change (ΔE=4.558, 3.308, and 2.649, respectively). The effect of composite substructure and the yellow...
Open Access Macedonian Journal of Medical Sciences, 2020
BACKGROUND: Metal-ceramics restorations were considered a preferable option for fabrication fixed... more BACKGROUND: Metal-ceramics restorations were considered a preferable option for fabrication fixed partial dentures (FPDs) that have an acceptable durability, but they are not able to provide the same beauty as the entire ceramic material. Full-contour zirconia, such as Zolid, does not have problems with chipping of layered zirconia, along with translucency and staining capabilities. AIM: This study aimed to assess the fatigue fracture strength of three-unit implant-supported full-contour zirconia and metal-ceramics posterior FPDs. MATERIALS AND METHODS: In this in vitro study, 24 posterior three-unit implant-supported FPDs were fabricated of full-contour zirconia and metal-ceramics and were cemented on implant abutments. To simulate the oral environment, FPDs were subjected to 10,000 thermal cycles between 5 and 55°C for 30 s and were then transferred to a chewing simulator (100,000 cycles, 50 N, 0.5 Hz). Afterward, fatigue fracture strength was measured using a universal testing ma...
Introduction: The purpose of this study was to investigate the effect of flask investment materia... more Introduction: The purpose of this study was to investigate the effect of flask investment materials on the color changes of different brands of resin denture teeth. Methods: Resin denture teeth (560) were divided into 2 groups according to the materials used for flask investment (silicone or gypsum). All the specimens were thermocycled between 4°C and 60°C with 60-s dwell times for 1,000 cycles. Subsequently, the specimens of each group were divided into 4 subgroups based on the immersion media: coffee, tea, cola, and distilled water. Digital images of the teeth were taken before immersion and 30 days after immersion. The color samples were measured using the CIE L*a*b* system, and color differences (∆E) were calculated. The data were evaluated by three ways ANOVA and the Tukey HSD test. Results: There was not a significant difference in ∆E using three-way ANOVA, while the results showed considerable statistical differences with two factor ANOVA interaction. The ∆E values in the sil...
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