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کاربرد نوع شرط:
- جایگاه : پژوهشی
- مجله: Journal of Dentistry, Shiraz University of Medical Sciences
- نوع مقاله: Journal Article
- کلمات کلیدی: Bond strength,Zirconia,Implant,Lithium disilicate
- چکیده:
- چکیده انگلیسی: Statement of the Problem: Hybrid abutments are made of a titanium implant insert and a ceramic component. The tensile bond strength between the titanium implant insert and the ceramic component is not still clearly known.Purpose: This in vitro study aimed to compare the tensile bond strength of the titanium insert to ceramic components made of milled lithium disilicate, milled zirconia, and pressable lithium disilicate.Materials and Method: To standardize the shape and dimension of the ceramic components, a single computer-aided design/computer assisted manufacturing (CAD/CAM) superstructure was designed with Dental Designer software. Based on this model, CAD milled zirconia (Zr), CAD milled Lithium disilicate (CAD-LD) and heat-pressed lithium-disilicate (H-LD) superstructures were fabricated (n=10 per group). They were bonded to the titanium inserts by using self-adhesive resin cement. The prepared superstructure-titanium insert complexes (hybrid abutments) were screwed into the implants with 35 Ncm torque. The tensile bond strength of the ceramic superstructures to the titanium inserts were recorded by the universal testing machine with a crosshead speed of 2 mm/min. The data were analyzed by using one-way ANOVA and Tamhane post-hoc test (p < 0.05).Results: The mean±SD of tensile bond strength was 328.50±30.4 N in CAD-LD, 257.30±23.8 N in H-LD, and 242.20±21.2 N in Zr groups. One-way ANOVA revealed the groups significantly different in terms of the tensile bond strength (p < 0.001). Tamhane post-hoc test showed a significant difference between the CAD-LD and the two other groups (p <0.001); however, no statistically significant difference was detected between the H-LD and Zr groups (p= 0.39).Conclusion: It can be concluded that the CAD-LD has higher bond strength to titanium insert compared with the H-LD and Zr groups. Therefore, they might be clinically more beneficial in high-esthetic areas.Key Words ● Bond strength ● Implant ● Lithium disilicate ● Zirconia
- انتشار مقاله: 22-10-1397
- نویسندگان: Mitra Zirak,Mahroo Vojdani,Amir Ali Reza Khaledi,Mitra Farzin
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Dentistry, Shiraz University of Medical Sciences
- نوع مقاله: Journal Article
- کلمات کلیدی: Esthetics,age groups,mandibular prognathism,Mandibular Retrognathism
- چکیده:
- چکیده انگلیسی: Statement of the problem: As an important determinant of social acceptability, facial attractiveness can be influenced by decisions of orthodontists through treatment. Purpose: The purpose of this study was to determine the difference in perception of facial attractiveness among male and female raters in different age groups through comparison of silhouettes.Materials and Method: 208 subjects (99 male, 109 female) aged between 18 to 70 years were assigned to three groups of young adults, middle-aged and senior and rated pre-designed silhouettes on a 7-level rating scale (1= the least esthetic, 7=the most esthetic). Two series of 7 silhouettes were prepared for men and women in which the mandible was protruded or retruded in 2-mm increments from the average. The evaluators were asked to grade the profiles separately for male and female. T-test and one-way ANOVA were used for the statistical analysis with α = 0.05.Results: The first and third age groups, favored female profile 2 among class II profiles. However, the second age group preferred the average profile. Male class II profiles were rated exactly as female ones among the three age groups. The average female class III silhouette was preferred in all age groups. The first and second age group preferred the average male profile in male class III silhouettes. The oldest group however, preferred profile 2. For both sexes, the least acceptable profile in each set of silhouettes was the most protruded or retruded.Conclusion: There were few differences in perception of facial attractiveness between different age groups. In all groups, even small mandibular protrusion was unacceptable and mild retrusion was considered attractive.
- انتشار مقاله: 28-06-1396
- نویسندگان: Parisa Salehi,Niloofar Azadeh,Negin Beigi,Mitra Farzin
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Dentistry, Shiraz University of Medical Sciences
- نوع مقاله: Journal Article
- کلمات کلیدی:
- چکیده:
- چکیده انگلیسی: Statement of the Problem: Considering the limitations of conventional sintering of zirconium oxide (ZrO2) copings, shortening the sintering time can be proposed as an alternative method for making the copings.Purpose: This study aimed to assess the effects of sintering time on compressive strength of Yttria Tetragonal Zirconia Polycrystal (Y-TZP) copings.Materials and Method: Thirty copings of pre-sintered 3Y-TZP blanks were milled and sintered in a special furnace for three different durations (n=10 per group). The sintering time was 1 h 15 min for IPS e.max ZirCAD, 4 h 20 min for Speed ZrO2, and 7 h 20 min for the conventional ZrO2 group. The specimens were cemented on the brass dies by using conventional glass ionomer cement. The copings were vertically loaded until fracture by using a universal testing machine. The data were analyzed through one-way analysis of variance (ANOVA) and post hoc test to compare the mean differences of compressive strength yielded in three study groups (α=0.05).Results: The mean ± SD of compressive strength value was (3617 ± 543.54) N for IPS-e.maxZirCAD group, (2663 ± 508.11) N for Speed ZrO2 group, and (1662± 466.71 N) for conventional ZrO2 group. There were statistically significant differences among compressive strength values of the tested groups (p< 0.05). The highest compressive strength values were obtained from the IPS e.max ZirCAD group.Conclusion: Within the limitations of this in vitro study, it can be concluded that compressive strength of the zirconia copings is affected by the sintering time. High compressive strength of zirconia copings can be obtained by shortening the sintering time. Key Words Compressive strength; Zirconia; Sintering;
- انتشار مقاله: 11-04-1396
- نویسندگان: Amir Ali Reza Khaledi,Mahroo Vojdani,Mitra Farzin,Soudabeh Pirouzi
- مشاهده
- جایگاه : پژوهشی
- مجله: Asian Pacific Journal of Cancer Prevention
- نوع مقاله: Journal Article
- کلمات کلیدی: Single Nucleotide Polymorphism,Oral lichen planus,programmed cell death protein,Autoimmune Disease
- چکیده:
- چکیده انگلیسی: Background: The association between programmed cell death protein 1 (PD-1) variations and susceptibility to
autoimmune diseases has been recurrently reported. However, there is no report about its relationship with oral lichen
planus (OLP) as one of autoimmune diseases. Methods: We investigated the association between genetic predisposition
to OLP and two single nucleotide polymorphisms in PD-1. Results: GG, GA, and AA genotypes at position +7146
were found in 59 (80.8 %), 10 (13.7 %), and 4 (5.5 %) patients, and in 132 (77 %), 34 (20 %), and 5 (3 %) healthy
participants. CC, CT, and TT genotypes at position +7785 were found in 32 (43.8 %), 35 (47.9 %), and 6 (8.2 %) patients
and in 99 (58 %), 66 (39 %), and 6 (3 %) controls. Analysis indicated that patients’ genotypes were not statistically
different from controls’ genotypes at both positions +7146 (P = 0.35 and P = 0.98) and +7785 (P = 0.07 and P = 0.06).
Conclusion: The findings indicated that PD-1 SNPs at +7146 [PD-1.3] G/A and +7785 [PD-1.5] C/T was not associated
with susceptibility to OLP. However, further research with higher sample size and in different geographical regions is
needed in order to achieve the generalizability of the findings.- انتشار مقاله: 30-10-1396
- نویسندگان: Janan Ghapanchi,Hamid Ghaderi,Mohammad Reza Haghshenas,Samira Jamshidi,Fahimeh Rezazadeh,Azita Azad,Mitra Farzin,Reza Derafshi,Ahmad Hasan Kalantari
- مشاهده