خلاصه مقالات انگلیسی
 

The effect of bonding agents on the microleakage of sealant following contamination with saliva. Askarizadeh N, Norouzi N, Nemati S

 

Abstract AIMS: An issue of concern in dentistry is the inadequacy of adhesion and proper sealing following restoration of a tooth, which can lead to marginal leakage. The aim of this study was to evaluate the effect of a bonding agent on the microleakage of a sealant material following contamination with saliva. MATERIALS AND METHODS: In this experimental research, 48 sound premolars were divided into two groups. The first group received sealant without bonding and the other group was given sealant with bonding. After prophylaxis, the occlusal surfaces were etched with 37% phosphoric acid gel and the teeth were then placed in fresh human saliva for l0 s. Following this, in the first group fissure sealant (Kerr) was applied directly and cured; for the second group sealant was placed and cured after bonding (Single Bond; 3M). All samples were thermocycled (500 cycles; between 5 degrees C and 55 degrees C; dwell time of 30 s). Silver nitrate was used as the leakage tracer. The teeth were sectioned. Microleakage evaluation was made by stereomicroscope at 40x magnification and the results were evaluated with the Mann-Whitney U test. RESULTS: In the group that received sealant without bonding extensive microleakage was seen; placement of sealant with bonding significantly reduced microleakage. CONCLUSION: In the presence of contamination with saliva, use of bonding under the fissure sealant can reduce microleakage. PMID: 18603730 [PubMed - indexed for MEDLINE] Free full text


 

Effects of laser-assisted fluoride therapy with a CO2 laser and Er, Cr:YSGG laser on enamel demineralization. Anaraki SN, Serajzadeh M, Fekrazad R

 

Abstract PURPOSE: The purpose of this in vitro study was to evaluate the irradiation efficacy of the CO(2) laser and the Er, Cr:YSGG laser-either unassisted or assisted by acidulated phosphate fluoride (APF) treatment-on enamel's acid resistance. METHODS: One hundred twenty enamel samples, obtained from 20 extracted human molars, were randomly assigned to 6 groups as follows: (1) control (C); (2) exposed to acidulated phosphate fluoride (APF) gel (F); (3) Er, Cr:YSGG laser (EL); (4) irradiated with Er, Cr:YSGG laser through APF gel (EL/F); (5) CO(2) laser (CL); and (6) irradiated with CO(2) laser through APF gel (CL/F). The specimens were individually demineralized in an acidified hydroxyethylcellulose system, and the acid resistance was evaluated by determining the calcium ion using atomic absorption spectrometry. RESULTS: The average concentration of the calcium ion determined in groups C, F, EL, EL/F, CL, and CL/F was, respectively, 3.36, 2.63, 2.26, 2.32, 2.24, and 1.51 ppm. The results showed that demineralization in the: CL/F group was significantly less than the other groups; and the control group was significantly more than the other groups (P<.001). CONCLUSION: The effect of CO(2) laser irradiation, used with acidulated phosphate fluoride, in decreasing the enamel demineralization was more than all the other groups


 

Evaluation of the effects of conventional versus laser bleaching techniques on enamel microroughness

 

Abstract Nowadays, bleaching of the teeth within the dental office is one of the most widespread techniques to correct tooth discoloration. Variability of the materials and techniques accompanied with the trend toward esthetic restorations with minimally invasive approaches are increasing. The use of laser in this regard has also been taken into consideration. The aim of this study was to evaluate the effects of in-office versus laser bleaching on surface roughness of enamel. Fifteen freshly extracted human molars were sectioned mesiodistally to produce 30 lingual and buccal enamel blocks. Samples were mounted in transparent acrylic resin blocks and polished before treatment. Samples were randomly assigned to laser bleaching (LB) and office bleaching (OB) groups (n = 15 each). Pretreatment evaluation of microroughness was carried out for all samples using profilometer. Samples were treated twice in the OB group with Opalescent Xtra Boost and in the LB group using a laser-activated gel. Microroughness was evaluated after bleaching in both groups. Data were analyzed using repeated measure ANOVA. Both methods increased enamel surface roughness. Microroughness changes were significantly different between the two groups (p < 0.05). Microroughness significantly increased in the OB group (p > 0.05), but there was no significant difference in pre- and post-treatment roughness evaluation in the LB group (p < 0.05). Laser was considered a safer technique because it demonstrated a less surface roughness increase in comparison with the conventional office bleaching procedure