Avicenna Journal of Dental Research
Volume:12 Issue: 1, Mar 2020

This study evaluated the effect of different mechanical surface preparation methods, as well as different adhesives including universal bonding agents, on the shear bond strength of composite repairs.

This study was experimentally performed on 64 Z250 composite discs (3M, ESPE) with 6 mm diameter and 2 mm height. A total of 60 samples were randomly divided into 6 groups as follows: Group A) diamond milling + Adper Single Bond 2, group B) diamond milling + Single Bond Universal, group C) diamond milling + All Bond Universal, group D) sandblast + Adper Single Bond 2, group E) sandblast + Single Bond Universal, group F) sandblast + All Bond Universal. Then, the new composite was placed on the bonding layer, cured, and underwent aging again. The samples were assessed for shear bond strength by universal testing machine and their failure mode was investigated under the light microscope (20x and 100x). Finally, 4 remaining samples, which were surface-prepared by diamond milling and sandblasting, were evaluated for qualitative analysis of surface roughness using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Data were analyzed by oneway ANOVA and Fisher’s exact tests.

There was no statistically significant difference in shear bond strength and failure mode among the groups (P> 0.05). However, diamond milling + Single Bond Universal group showed the highest and Adper Single Bond 2 had the lowest bond strength.

There was no significant difference in bond strength using different methods. Therefore, diamond milling + Single Bond Universal was suggested as the best and most available method compared to sandblasting.

Adhesion of composite resins to dentin is crucial in restorative dentistry. The aim of this study was to evaluate shear bond strength of composite restorations to dentin under different cycling conditions.

Ninety extracted premolar teeth were randomly divided into 9 groups (n=10). The samples were mounted in resin and sectioned to prepare dentin samples. Then the samples were polished with 600-grit silicon carbide sanding sheet, and adhesive types of bonding (5th generation/Ambar, 6th generation/Clearfil SE bond, 8th generation/G-Premio) were applied on them. Afterward, composite resin was bonded to the surface, and cycling was exerted (control: no cycling; thermal cycling: 3000 cycles, 5°C to 55°C; thermal/erosive cycling: thermal cycling and storage in hydrochloric acid, pH = 2.1, 5 minutes, 6 times a day, for 8 days). Shear bond test was done for the specimens. Finally, statistical analysis was done using a two-way analysis of variance (ANOVA) and Tukey test (P < 0.001).

G-Premio displayed the most bond strength. No significant differences were observed between Clearfil liner bond and Ambar bond. While significant differences were observed in different cycling conditions. Measured bond strength was reduced by thermal/erosive cycling.

Thermal cycling and thermal/erosive cycling could affect the shear bond strength of composite to dentin. Universal bonding systems can also increase the shear bond strength of composite resin to dentin.

Fixed orthodontic treatment has been associated with certain side effects such as white spot lesions (WSLs). Many studies showed the positive effect of sodium fluoride (NaF) varnish in remineralizing WSLs. Studies revealed that silver diamine fluoride (SDF) is effective in arresting dentin caries, but its potential for enamel remineralization has not been investigated clearly. The present study aimed to compare the effect of SDF and NaF on the microhardness of demineralized enamel.

A total of 60 intact premolar teeth were collected and divided into 4 equal groups. Group 1 remained intact (control). Groups 2 to 4 were exposed to artificial cariogenic solution to create enamel lesion. Then, groups 3 and 4 were treated with NaF 5% and SDF 38%, respectively. After one month of storage in artificial saliva, NaF and SDF were reapplied. One month later, the surface microhardness values (SMHs) of teeth were assessed.

The results of ANOVA showed a significant difference among the 4 groups (P<0.001). There was significantly higher enamel microhardness in the control group compared with groups 2 and 3 (P<0.001); however, it was not significant for the SDF group (P=0.160). There was significantly higher enamel surface microhardness in groups 3 and 4 compared with group 2 (P≤0.001) and significantly higher mean SMH values in the SDF group compared with the NaF group (P=0.004).

NaF varnish and SDF can both remineralize early enamel lesion but SDF has greater remineralizing potential.

Age estimation is a critical issue in forensic medicine for identifying corpses and to determining fake identities. The present study aimed to estimate the age based on the pulp chamber volume of multi-rooted teeth using cone-beam computed tomography (CBCT) images.

CBCT of 142 patients, consisting of 77 males and 65 females with an age range of 10-70 years, were selected. The images of 84 maxillary first molars and 79 mandibular first molars were evaluated. All the CBCT images were taken using the CRANEX 3D system and saved in OnDemand software. The images were converted into the DICOM format and saved in a semi-automatic segmentation software (ITK-SMAP version 3.6.0-beta). Based on the results of logarithmic regression analysis, age, as a dependent variable, was correlated with the pulp chamber volume, as a predicting factor, which can be used in preparing a statistical model for estimating the human age.

The correlation coefficient between age and all the morphological variables was negative, indicating a decrease in the mean of all these variables with age. The results of ANOVA showed a significant difference in the means of all these variables between the different age groups. In addition, the means of all these variables decreased with age. There was a relatively high correlation between age and the pulp chamber volume of the first molars (R2 =0.513-0.543, depending on the tooth type and gender).

There was a linear correlation between the volume of maxillary and mandibular pulp chambers and the chronological age of the population studied. The regression models achieved in the present study could be used to predict the subjects’ age with 0.54% and 0.51% accuracy based on the maxilla and mandible, respectively. The mean pulpal volume of the maxilla was a little larger than that of the mandible. Furthermore, the mean volume of the pulp chamber decreased with age.

Medical emergencies are a series of clinical events that occur during/after dental procedures accidentally or due to patients’ systemic problems. In this case, basic life support measures are the first and most important step for controlling medical emergencies, which require the knowledge, skills, and equipment. Accordingly, this study aimed to investigate dentists’ awareness of emergency equipment and medicines in general dental clinics in Rasht in 2019.

To this end, 56 general dentists working in dental offices in Rasht in 2019 were included in this cross-sectional study by a census sampling method. The data were analysed by Kruskal-Wallis and Pearson correlation tests in SPSS software version 24, and the significance level was set at 5%.

Based on the obtained data, 94.6% (53 dentists) of the participants answered the questionnaire, and 26.4% (14 dentists) of dental offices reported facing with emergency cases during the previous year. In addition, the highest frequency (33.3%) was associated with unconsciousness. All (100%) dentists asked their patients about cardiovascular and respiratory diseases before treatment. From the dentists’ perspective, oxygen and dopamine were the most and the least important medications in the frequency distribution of emergency medicines, respectively. Eventually, the investigation of the medicines and emergency equipment showed that oxygen was the most frequent equipment while verapamil was the least frequent medicine in dental offices.

The mean score of dentists’ knowledge was moderate. Thus, there is a clear need for educating dentists regarding increasing their preparedness for emergency management. Therefore, it is recommended that dental students pass some courses in relation to a medical emergency in dentistry during their studies, and educational programs should be considered as the retraining classes and continuous short courses for graduated dentists.

Peripheral hemangioma is a benign congenital lesion and when involving the tongue, it does not appear on panoramic radiography.

This case report describes a 29-year-old male patient with peripheral hemangioma in his tongue and left side of the lower lip. In panoramic radiography, some calcifications are seen. In cone beam computed tomography (CBCT), more calcifications (phleboliths) and mandibular thinning are seen and if the lesion is not excised, it can result in mandibular fracture. As is known, biopsy or surgical excision of this lesion can result in severe hemorrhage, leading even to death. Therefore, accurate clinical and radiographic diagnosis is essential before starting any surgical intervention.

Exact evaluation of panoramic radiographs by dentists is important for the detection of silent lesions. With early detection of these lesions, many side effects can be prevented. On the other hand, sometimes peripheral lesions, such as peripheral hemangiomas, affect adjacent bone in a way that mimics a central lesion and are difficult to distinguish using only two-dimensional images such as panoramic radiographs. Therefore, using complementary imaging techniques such as CB