Showing 8 results for Flow
E. Yasini , N Mohammadi ,
Volume 14, Issue 4 (1-2002)
Abstract
Posterior composite restorations, due to polymerization contraction, result in microleakage. Different methods have presented to reduce this phenomena. The aim of this study is to evaluate the effects of flowable and condensable composites to reduce microleakage. Seventy extracted human teeth were prepared with proximal class II cavities with gingival margin 1 mm below CEJ. The teeth randomly were divided into 7 groups. Groups I & II were restored with a dentin bonding (DB) agent plus a Prodigy condensable (Kerr Co.) composite, placing incremental or bulky, respectively.. In groups IK IV, V a dentin bonding agent was applied and then cavities were restored with Tetric flow composite resin as a base plus either a hybrid composite (Tetric ceram, Vivadent Co.) or a Prodigy condensable composite (Cond), placing bulky or incremental. Groups VI and VII were restored with a resin modified glass ionomer (GI) (Fuji II Lc Co.) as a base plus either Prodigy condensable or Tetric ceram. Restorations were polished, thermocycled, and immersed in 0.3% basic fushin. After that samples were sectioned and studied under a stereomicroscope to evaluate dye penetration. Results showed that all restorations showed some degree of microleakage and according to kruskall- wallis statistical analysis, there were not any significant differences between all groups (P-0.051). Then fore pair comparison, between groups. Mann-Whitney analysis was used and no statistical difference was observed. However. Gh DB- Tetric group showed the least microleakage and DB+ Cond (bulk) the most one. Due to lack of an" statistical difference among different materials methods, it is concluded that no method or restorative material have been able to eliminate microleakage in margins completely yet, and using a flowable composite resin, in place of resin modified glass ionomer or using a condensable composite, instead of conventional In brid composites, do not have any effect
A. Monzavi , S. Mir Mohammad Rezaei , H. Bajelan ,
Volume 15, Issue 2 (5-2002)
Abstract
Waxes have a lot of applications in dentistry. Such materials are of thermoplastic type that undergoes deformation in different temperatures. Two important properties of base plate waxes are flow and their coefficient of linear thermal expansion. Recently, different institutions, inside the country, produce dentistry waxes, while they have not been standardized. Consequently, consumers' dissatisfaction are observed. In this research, the two above- mentioned factors were compared between three kinds of Iranian waxes with Cavex that is foreign production, based on test number 24 of ADA. To measure the flow rate in the temperatures of 23, 37 and 45°c, Wilcoxon statistical analysis was used. The results showed that in 23°c, the flow rate of Cavex and Azardent waxes met ADA standards however, it was not true for two others types. In 37°c, the flow of none of the waxes was standardized and in 45°c their flow was acceptable, moreover, thermal expansion coefficient, for Cavex and Azardent types, was based on ADA standard.
F. Aghahosseini , Mh. Akhavan Karbasi ,
Volume 16, Issue 2 (5-2003)
Abstract
Statement of Problem: Menopause can exert extensive somatic and psychological effects on women at this stage including: oral complaints such as dry mouth, glossodynia, viscous saliva, although these findings should be studied further.
Purpose: The aim of this study was to investigate the stimulated salivary flow rate of 158 menopause and post menopause women.
Material and Methods: In this cross- sectional and analytic- descriptive study, 158 women, at post menopause stage, were selected as case group. The controls consisted of 83 same aged men. None of the subjects had any systemic disease and did not use any drugs. Age range, in both groups, was 50-69 years old. Psychical condition of two groups, were compared by HADSCALE test. Oral symptoms were also compared and evaluated. In order to analyze the results, "t" and "Mann- Whitney" tests were used.
Results: No significant difference was found between two groups regarding the quantity of stimulated saliva and psychological condition, but the incidence of oral symptoms in case group was significantly higher than the control group (P=0.002).
Conclusion: Based on this study, although oral symptoms have a significant relation with menopause, can not be attributed to the quantity of saliva or psychical condition. In order to find the underlying reasons, more investigations should be performed on quality changes of saliva or other factors.
A. Pahlavan, M. Ghavam, S. Arami, E. Yasini, M. Mirzaie, H. M.kermanshah, M. Hasani Tabatabaie, M. Bayrami,
Volume 21, Issue 1 (10-2008)
Abstract
Background and Aim: Because of polymerization shrinkage and high viscosity of posterior composites, there are some difficulties in using them in posterior restorations. Several methods have been represented to reduce the effect of shrinkage. The aim of this study was to investigate the effect of curing flowable composites under condensable ones in adaptation and microleakage reduction of posterior composite restorations.
Materials and Methods: In this experimental in vitro study, forty class II MO cavities were prepared on extracted intact molar and premolar human teeth. Gingival margins were placed 1 mm apical to CEJ. The teeth were divided into two groups. In group 1, flowable composite (Filek Flow, 3M, ESPE, USA) with 0.5-1 mm thickness was applied and cured following application of bonding agent (Single Bond, 3M, ESPE, USA). The rest of the cavity was filled by condensable composite (p60, 3M, ESPE, USA). In group 2 the flowable composite was not cured, and the condensable composite was applied in two increments. After light curing of composites, all the specimens were thermocycled and then immersed in 0.3% basic fuschin. Specimens were sectioned and evaluated for degree of dye penetration under a stereomicroscope. Data were analyzed by Mann-Whitney test with p<0.05 as the level of significance.
Results:. There was no significant difference between the two studied groups regarding microleakage.
Conclusion: Based on the results of this study, neither cured nor uncured flowable composite under condensable composite can omit microleakage in posterior composite restorations.
F. Shirani, Mr. Malekipoor, P. Mirzakoochaki, M. Eravani,
Volume 21, Issue 2 (11-2008)
Abstract
Background and Aim: Microleakage has been always a major concern in restorative dentistry. The curing contraction of composites still presents a problem with controlling microleakage and postoperative sensitivity. The aim of this study was to investigate the effect of flowable and dual-cure resin composite liners on gingival microleakage of packable resin composite restorations.
Materials and Methods: Sixty Class II cavities with cervical margins 1 mm below the CEJ were prepared in 30 extracted human molars. The teeth were randomly divided into five groups of 12 each. In control group, each tooth was restored incrementally with Tetric Ceram composite without applying any liner. In the second and forth groups, flowable materials- Tetric Flow and dual-cure composite resin cement Relay X ARC were placed respectively as a 1-mm thick gingival increment and cured before the resin composite restoration, whereas, in the third and fifth groups liners were cured with the first increment of packable composite.The restored teeth were stored for one week in distilled water at 370C, and thermocycled between 50C and 550C, sealed with nail varnish except the tooth - composite interface in cervical restoration margins and immersed in 2% basic fuchsin for 24 hours. Dye penetration was evaluated using a stereomicroscope with 28x magnification. The data were analyzed by Kruskal-Wallis and Mann-Whitney U-tests with p<0.05 as the level of significance.
Results: The results of this study indicated that there were significant statistical differences between control - cured flowable liner, control-flowable liner without separately curing, control-cured dual cure composite resin cement groups.However there were no significant differences between dual-cure composite resin cement without separately curing-control,cured flowable liner-cured dual cure composite resin cement, flowable liner without separately curing-dual cure composite resin cement without separately curing groups.
Conclusion: The results of this study indicated that none of techniques could thoroughly eliminate microleakage in gingival floor, however the effect of flowable or a dual-cure liner on reducing the gingival microleakage was found to be statistically significant in tested restorative material.
F. Mashadi Abbas, S. Mojarrad, Z. Yadegary, B. Sharifi,
Volume 24, Issue 2 (4-2011)
Abstract
Background and Aims: In the last decade, several studies have reported the isolation of stem cell population from different dental sources, while their mesenchymal nature is still controversial. The aim of this study was to isolate stem cells from mature human dental pulp and follicle and to determine their mesenchymal nature before differentiation based on the ISCT (International Society for Cellular Therapy) criteria.
Materials and Methods: In this experimental study, intact human third molars extracted due to prophylactic or orthodontic reasons were collected from patients aged 18-25. After tooth extraction, dental pulp and follicle were stored at 4°C in RPMI 1640 medium containing antibiotics. Dental pulp and follicle were prepared in a sterile condition and digested using an enzyme solution containing 4mg/ml collagenase I and dispase (ratio: 1:1). The cells were then cultivated in α-MEM medium. Passage-3 cells were analyzed by flow cytometry for the expression of CD34, CD45, CD 73, CD90 and CD105 surface markers.
Results: Dental pulp and follicle were observed to grow in colony forming units, mainly composed of a fibroblast-like cell population. Flow cytometry results showed that dental pulp and follicle are highly positive for CD73, CD90 and CD105 (mesenchymal stem cell markers) and are negative for hematopoietic markers such as CD34 and CD 45.
Conclusion: In this study we were able to successfully confirm that dental pulp and follicle stem cells isolated from permanent third molars have a mesenchymal nature before differentiation. Therefore, these two sources can be considered as an easy accessible source of mesenchymal stem cells for stem cell research and tissue engineering.
Mitra Tabari, Hengame Saffarcherati, Vahid Soltankarimi, Zahra Bani Ameri, Arash Poorsattar Bejeh Mir,
Volume 24, Issue 4 (1-2012)
Abstract
Background and Aims: A large number of investigations have revealed that physical and chemical alterations and weight loss could occur in composite materials exposed to acidic phosphate fluoride (APF) gel. The purpose of this study was to assess the microleakage of a fissure sealant and a flow composite exposed to acidulated phosphate fluoride (APF) gel.
Materials and Methods: In this in vitro study, 60 intact human extracted premolar teeth were used. After preparing the occlusal groove, the teeth were divided into two groups (n=30). Teeth were filled with either Helioseal fissure sealant (Vivadent, Germany) or Tetric flow composite (Vivadent, Germany). After that, each group was divided into two subgroups (n=15): 1.23% APF gel (Sultan, U.S.A) was applied in the case subgroups, while control subgroups were preserved in normal saline solution. All of teeth were covered with 2 layers of nail varnish except for the filling zone and 1mm around the border of filling. After submerging in 0.5% fushin solution, specimens were sectioned bucco-lingually. Then dye penetration through the filling and fissure sealant was assessed by means of a stereo-microscope. The depth of dye penetration was scored. The data were analyzed using One-way ANOVA and Levene test.
Results: The mean values of dye penetration were 1.26±1.09, 1.4±1.05, 1.2±1.37, and 1.4±1.35 for fissure sealant+gel, composite+gel, composite+normal saline, and normal saline groups, respectively. No significant difference was found in inter-groups (P=0.96).
Conclusion: Considering the result of the present research, APF gel had no significant effect on the microleakage of Tetric flow composite filling and Helioseal fissure sealant and thus, it can be applied for routine usage.
Siavash Valizadeh, Omid Fatahi Valilai, Alireza Valizadeh, Mahmoud Houshmand, Zahra Vasegh,
Volume 31, Issue 2 (9-2018)
Abstract
Background and Aims: In recent years, the dentistry workflow has developed considerably. By the introduction of computers and their various applications, the effectiveness and efficiency of treatment has increased enormously. Considering engineering concepts in the workflow, it is necessary for participants to assess different steps and data transferring between various software and hardware devices. This research investigated the interaction between dentists, laboratories and production centers through the required steps for accomplishing treatment by different applications of software and digital hardware devices.
Materials and Methods: Review in this article was based on searching Google scholar database considering key words: digital dentistry, workflow, computer aided design and manufacturing, dental CAD/CAM. This search was limited to the English articles published after the year 2000.
Conclusion: It is necessary in dentistry to use digital technologies to improve the efficiency of treatments. Thus, the participants in this field must have appropriate knowledge to choose and apply these tools. Moreover, the participant should help providers of digital solutions for better development of software packages and related hardwares.a
