Journal of Dental School
Volume:33 Issue: 4, Fall 2015

Bulk-fill composites are a group of composite resins designed for easy and fast filling of large cavities. This study aimed to assess the color stability of bulk-fill composites subjected to xenon radiation and evaluate their color change (&DeltaE) following polymerization. In this in vitro experimental study, 30 specimens (4mm in height and 8mm in diameter) were fabricated of x-traFil and Tetric N-Ceram universal color bulk-fill composites and A2 shade of Grandio composite (as control). Bulk-fill composites were placed in the mold in 4mm thickness according to the manufacturers’ instructions. In the control group, composite was applied to the mold in two layers each with 2mm thickness. Tetric and Grandio composites were cured for 20 seconds and x-traFil was cured for 10 seconds with a LED light-curing unit. A total of 15 specimens (five of each composite) were used for each test. For assessment of color change due to polymerization, L*, a* and b* color parameters were measured before and immediately after polymerization and also 30 days after immersion in distilled water in an incubator at 37°C and 70% humidity using a spectroradiometer. For xenon test, the specimens were subjected to color analysis after 48 hours of storage in distilled water. Next, they were subjected to xenon lamp radiation in xenon environment chamber for 122 hours at 22°C and 25% humidity and then the color parameters were measured again. The mean and standard deviation (SD) of all values were calculated. One-way and repeated measures ANOVA were used to compare &DeltaE and &DeltaL among the groups. Tukey’s HSD test was used for pairwise comparisons. The value of &DeltaE immediately after polymerization was the lowest for Grandio (4.91) and the highest for Tetric (9.44). Thirty days after the polymerization, &DeltaE was the lowest in Grandio (3.07) and the highest in Tetric (9.27) &DeltaE showed a decreasing trend over time in all specimens. Under xenon light radiation, Grandio showed the lowest (1.50) and Tetric showed the highest &DeltaE (11.15). Following polymerization and under xenon lamp radiation, &DeltaE of conventional composite was less than that of bulk-fill composites.

When none of digital systems and scanners is accessible and it is essential to have digitized images of conventional radiographs, digital cameras can be used. The Aim of this study was to investigate whether digital images obtained by different resolutions of a digital camera are matched to the original radiographs in evaluation of caries. In this diagnostic accuracy in vitro study the conventional radiographs of168 proximal surfaces of 84 teeth were produced, Then they were digitized with digital camera in three different resolutions high (2048x1536), medium (1600x1200) and low resolution (480x460). Images were stored in Photoshop7.0 software, and were evaluated by5 observers to show the presence and depth of the caries. Cronbach’s &alpha calculated inter-observers agreement and in order to calculate the agreement with original conventional radiographs Kappa index was used. In assessing the presence of caries, the agreement between low, medium and high resolutions with original radiographs were 0.286, 0.235 and 0 respectively. Also, assessing the depth of the caries agreement was reported0.21, 0.338 and 0.412 respectively. In most instances, there was a fair agreement between the different resolutions and original radiographs. The highest inter-observer’s agreement was reported in diagnosis of the presence of the caries with using high resolution (&alpha=0.837) and the lowest inter-observer’s agreement was reported in diagnosis of the depth of the caries with medium resolution(&alpha=0.762).There was no significant difference reported in observations of different resolutions and original images. Using of high-resolution cameras did not show a significant difference with medium and low resolutions in caries evaluations. Therefore, considering the increase in the file size and difficulties in cameras selection, using of high-resolution digital cameras is not necessary in order to increase the diagnostic accuracy of digitized images.

Removal of enamel superficial layer during microabrasion treatments may adversely affect sealing ability of the restorative materials. The aim of this study was to measure the effect of different periods of enamel microabrasion on the microleakage of class V glass-ionomer restorations. This in vitro experimental study was conducted on 96 Class V cavities which had been prepared on the buccal and lingual surfaces of 48 sound human premolars. After conditioning with 10% polyacrylic acid (GC, Tokyo, Japan) one half of the cavities were restored with the conventional glass-ionomer (Fuji II GC, Tokyo, Japan) and another half with resin-modified glass-ionomer (Fuji II LC GC, Tokyo, Japan). Finishing and polishing were performed after 24 hours and the teeth incubated for 2 weeks (37°C and 100% humidity).Then the teeth were classified into eight groups (n=12). Microabrasion treatment was performed with Opulster (Ultradent product Inc, South Jordan, UT, USA) in 0(control no treatment), 60, 120 and 180 seconds. Then teeth were thermocycled between 5°C-55°C (×1000), immersed in 0.5% basic-fushin solution (24h) and sectioned longitudinally in bucco-lingual direction (n=192). Dye penetration was examined with stereomicroscope (×40). Microleakage scores were statistically analyzed by Kruskal-Wallis test while the paired comparisons were done using Mann-Whitney U test. The mean microleakage scores were significantly increased following increased microabrasion times in occlusal margin in FU II (p<0.009) and FU II LC (p<0.02) and in gingival margin in resin-modified glass-ionomer (p<0.04). In Fuji II restorations after microabrasion in occlusal margins, microleakage increased up to 120s but in gingival margins no significant difference were seen. In Fuji II LC restorations after microabrasion in occlusal margin, microleakage from 60s up to 180s was significantly increased. In gingival margin with increasing the time up to 180s microleakage increased.

Dental solid wastes often contain hazardous substances. The first step of management of dental solid wastes includes detection and classification of these substances. This study aimed to qualitatively and quantitatively assess the management of solid wastes by dental offices in Urmia city in 2013. This descriptive study was conducted on all private dental offices in Urmia city and six samples were collected of the wastes of each office per season. Samples were manually searched, divided into 16 different categories and weighed by a digital scale. In the next step, the weighed components were classified according to their characteristics and hazardous potential. The total amount of solid wastes produced by dental offices in Urmia city was 81 kg/day consisting of 28.3% infectious wastes, 59% domestic-like wastes, 9.6% chemical and pharmaceutical wastes and 2.7% toxic wastes. Waste reduction and recycling programs were not performed in any office. Considering the type and quantity of generated dental solid wastes, especially the infectious wastes and their adverse effects on public health and the environment, a specific strategy must be designed for management of dental solid wastes.

This study aimed to compare the effect of using Casein phosphopeptide – amorphous calcium phosphate (CPP-ACP) paste, Remin-Pro and Fluoride Varnish on remineralization of enamel lesions. In this experimental-in vitro study, 60 intact premolars and molars were used and flat enamel surfaces were prepared. The specimens were divided into 6 groups (N=10). After primary DIAGNOdent value measurement and a four-day immersion in demineralizing solution, the DIAGNOdent value were measured. Groups 1, 2 and 3 were treated by Fluoride varnish, CPP-ACP and Remin-Pro respectively, according to the manufacturer instruction and their DIAGNOdent value was read. Groups 4, 5, and 6 were treated by Fluoride varnish, CPP-ACP and Remin-Pro for 1 month (8 hours a day), respectively, and their DIAGNOdent value was measured. Then the specimens of these three groups were demineralized and pH cycled and their DIAGNOdent values were recorded. The data were analyzed by One-way analysis of variance (ANOVA) and repeated measures ANOVA. After a one-month treatment, the DIAGNOdent value significantly decreased in groups 4, 5, and 6 in comparison to the manufacturer instruction (p<0.001). ANOVA test indicated that decrease mean value of DIAGNOdent value was significantly higher for Remin-Pro and CPP-ACP groups than Fluoride varnish group, from entrance time to the study to re-demineralization stage (p<0.001). All the three materials showed a statistically significant amount of remineralization after repeated application but the CPP-ACP and Remin pro were more resistant to redemineralization and pH cycling.

Infection control is one of the important aspects in dentistry. Oral and maxillofacial surgery is one of the most sensitive fields in dentistry in which infection control is important a sterile surgical set is imperative. Manufacturers only guarantee the sterility of the anesthetic not the sterility of its outer surface. They recommend alcohol to sterile the outer surface (especially the diaphragm) of the cartridge. On the other hand, studies showed contamination of external surfaces in anesthetic cartridges in various amounts. Evaluation of possible microbial contamination of anesthetic cartridge surfaces was the intent of this study. During this descriptive experimental study, random sampling was performed and 1,200 Iranian and imported cartridges were transferred to different culture media (aerobic, anaerobic and fungal). After 24-48 hours of incubation, samples were transferred to specific culture media. Cultured bacteria were stained, using the Gram staining method. The study was carried out in a 6-month period. We found 6.3 percent of aerobic cultures, 1.8 percent of anaerobic cultures and 0.7 percent of fungal cultures were contaminated by different types of microorganisms sampled from cartridges. The contamination of cartridges is not ignorable and placing them directly in the sterile surgical set is not recommended.

Adaptation of the pharyngeal airway space does occur after different surgical strategies of class III patients including mandibular setback, maxillary advancement and bimaxillary surgery. The aim of this study is to conduct a detailed cephalometric evaluation of the alterations taking place in the morphology of the pharyngeal airway space after treatment of class III skeletal deformity via different surgical procedures (i.e.­­ mandibular setback, maxillary advancement, bimaxillary surgery) in both males and females. This study is a before-after cross sectional retrospective research. One hundred and twenty consecutive patients who were diagnosed as having skeletal class III deformity. All patients included in this study were adults who had completed their growth and had cephalograms within a month prior to operation (T1) and 1 month to 9 months post-surgery (T2) taken in the natural head position. Patients were divided according to the type of surgery undertaken in three groups: group 1 (bimaxillary), group 2 (mandibular setback) and group 3 (maxillary advancement) surgeries. Posterior airway size was evaluated at both T1 and T2 in each group. The results were compared by paired t and one-way ANOVA tests. Airway size decreased significantly in group 1 and 2 (p<0.05) but increased in group 3(p<0.05). Airway dimension and morphology as well as head and neck posture changed significantly in different surgical treatments of class III deformity,

Diagnosis of vertical root fractures (VRFs) is critical in endodontics. Cone Beam Computed Tomography (CBCT) has significantly enhanced image quality compared to digital radiography (DR) and greatly aids the diagnosis of VRFs but, metal artifacts has remained as a problem in VRF detection. This study evaluated the effect of intra canal posts on the diagnostic accuracy of CBCT and DR for detection of VRFs. In this experimental in vitro study eighty extracted human premolar teeth were cut at the cement-enamel junction. After root canal preparation, the casting posts were made. Samples were randomly divided into 2 groups of 40 group one with induced fracture and group 2 as the control group. Radiographs were taken for all specimens with and without posts with both imaging systems. Three observers assessed the presence or absence of VRF. Accuracy of the two imaging systems and the effect of post on VRF detection were assessed, using two-way ANOVA test and inter observer coefficient agreement was calculated. Absolute diagnostic sensitivity and specificity of CBCT and absolute sensitivity of DR in the group with intracanal posts were significantly lower than those in the group without posts (p=0.023, p=0.034 and p=0.034 respectively). Absolute specificity of DR in the group with posts was significantly higher than that of the CBCT (p=0.014). The absolute and complete specificity of CBCT in the group without posts was significantly higher than those of DR (p=0.024, p=0.04). No statistically significant difference was found in inter observer agreement coefficient in presence or absence of posts or between the two imaging systems (p=0.119). Intra canal posts decreased the diagnostic accuracy of CBCT and DR for detection of VRFs and this reduction was greater in CBCT. However, absolute specificity of DR in the group with posts was significantly higher than that of the CBCT, where as CBCT images of teeth without posts still had higher diagnostic accuracy than DR.