Background: Coronal restoration of endodontically treated teeth (ETT) with mesio-occluso-distal (MOD) cavities is of a great importance in long-term success of the treatment. This study evaluated the effect of fiber reinforcement on the fracture resistance (FR) of ETT restored with flowable or paste bulk (PB)-fill composite resin compared to conventional composite (CC) resin. Materials and Methods: In this in vitro experimental study, eighty maxillary premolars were divided into eight groups (n = 10). The first group was left intact (G₁) and the other groups received MOD cavities along with endodontic treatment. G₂: Remained unrestored while the other experimental groups were restored with three types of composite resin with or without fiber insertion. G₃: CC resin, G₄: PB fill, G₅: Flowable bulk fill (FB). G₆: Fiber + CC, G₇: Fiber + PB, and G₈: Fiber + FB. FR was tested at crosshead speed of 1 mm/min and recorded in Newton. Data were analyzed using one-way analysis of variance and Tukey's tests at significance level of P < 0.05. Results: G₁ and G2 revealed the highest and the lowest FR, respectively. The mean FR of the testing groups in Newton was as follows: G₁ = 1204.8 ^A, G₂ = 352.1 ^C, G₃ = 579.6 ^BD, G₄ = 596.7 ^BD, G₅ = 624.9 ^BDE, G₆ = 858.3 ^E, G₇ = 529.6 ^CB, and G₈ = 802.5^DE. Different uppercase letters indicate the significant difference between the groups. Conclusion: The effect of fiber insertion on FR depended on the type of composite resin; the highest reinforcing effect was obtained in the CC resin + fiber, followed by bulk-fill flowable + fiber, and flowable bulk (FB)-fill composite resin. The strength of the former was significantly higher than the conventional and PB fill with and without fiber.

Background: Mouthguard (MG) disinfectant sprays are available for maintaining MG hygiene. The effect of these sprays against Streptococcus sobrinus is still unknown. The purpose of this study was to evaluate the antibacterial effect of an MG disinfectant spray against S. sobrinus using the modified ISO 22196 standard. Materials and Methods: In this in vitro study, we used the following treatment groups for antibacterial testing: MG spray-1 (left in spray for 30 s), MG spray-2 (60 s), and control (n = 4). All analyses were performed at a statistically significant level (P = 0.05) using JMP^® 14. Results: The log colony-forming units of the MG spray-2 group were significantly lower than those of the other groups. The antibacterial activity of MG spray-2 against S. sobrinus was >2.1. Conclusion: We confirmed the antibacterial effect of the MG spray against S. sobrinus, and it was influenced by the treatment duration, with the optimum effect at a longer duration.

Background: The margin of crown is a significant area for plaque accumulations. Therefore, the ability of the cement to seal the margin is very important. The aim of the present study was to evaluate the bond (retentive) strength, microleakage, and failure mode of four different types of cements in stainless steel crown (SSC) of primary molar teeth. Materials and Methods: In this experimental study, eighty extracted primary molar teeth were divided into two groups of forty teeth to test the microleakage and bond strength. The crowns were cemented according to the manufacturer guidelines with four cement types including self-cure glass ionomer, resin-modified glass ionomer, polycarboxylate, and resin cements. Stereomicroscope and universal testing machine were used to measure the microleakage and bond strength, respectively. For calculating the surface area of crowns, three-dimensional scanning was used. Furthermore, the failure mode was examined after the bond strength test. The cements surfaces and the tooth–cement interfaces were evaluated using scanning electron microscopy (SEM). The obtained values were analyzed using SPSS-23 software through Shapiro–Wilk and one-way analysis of variance tests. Means, standard deviations, medians, and interquartile ranges were calculated. P < 0.05 was considered as statistically significant in all analyses. Results: Significant differences between microleakage (P = 0.001) and failure mode (P = 0.041) of the four types of cements were obtained. However, the mean bond strengths of the four groups did not differ significantly (P = 0.124). The obtained SEM images confirmed the results of bond strength and microleakage. Conclusion: Resin cement and resin-modified glass ionomer, respectively, showed superior properties and are recommended for use in SSCs of primary molar teeth.

Background: The progressive destruction of nerve cells in nervous system will induce neurodegenerative diseases. Recently, cell-based therapies have attracted the attention of researchers in the treatment of these abnormal conditions. Thus, the aim of this study was to provide a simple and efficient way to differentiate human dental pulp stem cells into neural cell-like to achieve a homogeneous population of these cells for transplantation in neurodegenerative diseases. Materials and Methods: In this basic research, human dental pulp stem cells were isolated and characterized by immunocytochemistry and flow cytometry techniques. In the following, the cells were cultured using hanging drop as three-dimensional (3D) and tissue culture plate as 2D techniques. Subsequently, cultured cells were differentiated into neuron cell-like in the presence of FGF and Sonic hedgehog (SHH) factors. Finally, the percentage of cells expressing Neu N and β tubulin III markers was determined using immunocytochemistry technique. Finally, all data were analyzed using the SPSS software. Results: Flow cytometry and immunocytochemistry results indicated that human dental pulp-derived stem cells were CD90, CD106-positive, but were negative for CD34, CD45 markers (P ≤ 0.001). In addition, the mean percentage of β tubulin positive cells in different groups did not differ significantly from each other (P ≥ 0.05). Nevertheless, the mean percentage of Neu N-positive cells was significantly higher in differentiated cells with embryoid bodies' source, especially in the presence of SHH than other groups (P ≤ 0.05). Conclusion: It is concluded that due to the wide range of SHH functions and the facilitation of intercellular connections in the hanging droop method, it is recommended that the use of hanging drop method and SHH factor can be effective in increasing the efficiency of cell differentiation.

Background: Several techniques such as sand blast, silicoating, and laser irradiation have been introduced for reliable bond between zirconia and resin cement. This study aimed to assess and compare the effect of three types of lasers on the shear bond strength (SBS) of zirconia to resin cement. Materials and Methods: In this in vitro study, 55 zirconia disks (6 mm diameter × 3 mm thickness) were randomly divided into five groups: control (1), sandblast (2), carbon dioxide (CO₂) (3), erbium-doped yttrium aluminum garnet (Er: YAG) (4), and neodymium-doped yttrium aluminum garnet (Nd: YAG) (5) laser irradiation. The surface morphology of one specimen from each group was evaluated by a scanning electron microscope. Zirconia disks were cemented to composite using Panavia F2. SBS test was performed at a crosshead speed of 1 mm/min after 24 h storage in distilled water and thermocycling. The data were analyzed by one-way analysis of variance and post hoc Tukey's HSD tests (α = 0.05). Results: The mean SBS values of the groups such as sandblast, Er: YAG, Nd: YAG, and CO₂ lasers and control were 6.64 MPa, 6.63 MPa, 4.98 MPa, 4.39 MPa, and 2.32 MPa, respectively. No significant difference was observed between sandblast and Er: YAG laser and between Nd: YAG and CO₂ lasers. Conclusion: All lasers increased SBS values of zirconia to resin cement in comparison to the untreated surface. Er: YAG laser was the most effective laser treatment on the bond strength equal to that of sandblast.

Background: The collagen membrane which obtained from bovine pericardium and human skin in Guided Bone Regeneration (GBR) is costly and may even cause transmission of diseases. Replacing conventional collagen membranes with a more easily accessible and cheaper ones will have economic benefits. The aim was to determine the osteogenic effect of collagen-membrane derived from Rutilus kutum swim bladder on rat calvaria. Materials and Methods: The study was experimental. Thirty-six male albino rats of the Wistar strain were included in the study. The 5 mm surgical defects were created on calvarias and filled with allograft bone material and covered by R. kutum swim bladder (Group I), bovine derived pericardial membrane (Group II) and without membrane cover (Group III).The specimen were euthanized after 3, 5 and 8 weeks. The surrounding connective tissue was evaluated in term of osseous formation. Kruskal–Wallis, Univariant analysis of variance, and post hoc tests were used for statistical analysis. The P < 0.05 was considered statistically significant. Results: A significant differences between groups in terms of osseous formation (P = 0.001) was noted. The difference of osseous formation was significantly higher in 5 and 8 weeks than 3 weeks after operation in all groups (P = 0.03 and P = 0.006, respectively). The osseous formation in Group I and II were significantly higher than Group III (P = 0.023 and P = 0.001). Conclusion: The R. kutum swim bladder had osteogenic effect on rat calvaria. R. kutum swim bladder can be a new source in natural derived collagen membrane in GBR.

Background: The aim of the study was to evaluate the effect of 10% alpha-tocopherol and 5% grape seed extract on the microhardness and shear bond strength (SBS) to bleached human dentin. Materials and Methods: This in vitro study was done on 200 extracted premolars which were decoronated and grinded to get flat dentin surface occlusaly. They were divided into four groups: (a) bleaching, (b) bleaching and application of alpha-tocopherol, (c) bleaching and application of grape seed extract, and (d) control. Groups were further subdivided into Subgroups I and II (n = 30) based on storage period before building with composite and were then tested for microhardness and SBS determination. The data thus obtained was subjected to statistical analysis which was performed using ANOVA test and post hoc Tukey's test. The significance for the entire statistical test was predetermined at P < 0.05. Results: The results showed that the microhardness values were minimum in Group A (immediately after bleaching) and maximum in control group. Comparison of data using one-way ANOVA showed that the P value was highly significant (P < 0.001) among the groups. The intergroup comparison of SBS using post hoc Tukey's tests revealed that the P value was significant (P < 0.05) when the comparison was done between the Group A and Group C and Group B with Group D immediately after bleaching. Conclusion: Adverse effects of bleaching can be reversed with the application of 10% alpha-tocopherol and 5% grape seed extract over the dentinal surface microhardness and SBS.

Background: Children undergoing dental rehabilitations by general anesthesia (GA) commonly experience postoperative symptoms such as pain, fever, sore throat, and sleepiness. The aim of the present study was to investigate the specific complications of pediatric dental GA procedure. Materials and Methods: In this observational study sample included 72 children attending GA for dental treatment at the School of Dentistry, Isfahan University of Medical Sciences. Children with American Society of Anesthesiologists physical status I and without any communication or mental health problems were included. GA protocol was standardized. A number of complications were recorded by parents via filling a questionnaire for 2 days postoperatively. Data were analyzed using SPSS statistical software by Wilcoxon and Chi-squared test. P < 0.05 considered as significant level. Results: The most postoperative nonpsychological complications were dental pain (59.7 and 47.2% on days 1 and 2, respectively), followed by inability to eat normal (55.6 and 41.7% on days 1 and 2, respectively). All the patients' nonpsychological complaints had significantly decreased from day one to day two (P < 0.05). The most postoperative psychological complications were Attachments to parents (70.8 and 65.2% on days 1 and 2, respectively) followed by excessive crying (56.9 and 45.8% on days 1 and 2, respectively). All psychological complaints reduced by day two nonsignificantly except excessive crying which decreased significantly after 48 h (P = 0.004). Conclusion: The most postoperative complications after dental rehabilitation under GA were attachments to parents, dental pain, and inability to eat normal and excessive crying, respectively.

Background: The aim of this study was to compare dentinal crack formation in root canal walls following 3 single file systems with continuous rotation under a scanning electron microscope (SEM). Materials and Methods: In this SEM study, seventy mandibular premolars were randomly divided into 5 groups. 3 experimental groups (n = 20) and 2 control groups (n = 5) as follows: Group I: Neolix NiTi file system, Group II: OneShape systems, Group III: OneCurve file system, positive control: conventional Hand File system, negative control: unprepared. After root canal preparations, the roots were sectioned at 3, 6, and 9 mm from the apex with water irrigation. The sections were inspected in all directions under SEM at × 100 magnification to determine the presence of cracks. The Chi-square test was used to analyze the data. There is a statistically significant difference in the crack formation between the apical third (P = 0.012) and coronal third (P = 0.002) when comparing all the 5 groups. No significant difference is found in the middle third (P = 0.46). P < 0.05 is considered statistically significant. Results: Maximum cracks in the apical third were seen with One Shape file 11 (55%) and in the coronal third with Neolix NiTi 14 (70%). There is a statistically significant difference in the crack formation only in OneCurve when comparing the apical, middle, and coronal third for the individual group (P = 0.042). Conclusion: There was a significant difference in crack formation in apical and coronal third. OneCurve caused the least incidence of cracks when compared to other file systems. OneCurve file system can be a choice for canal preparation over Neolix Niti and OneShape.

Background: Charcoal toothpastes can whiten teeth through abrasion. The purpose of this study was to determine the level of whitening and abrasiveness of charcoal toothpastes in permanent teeth. Materials and Methods: In this in vitro study, 30 premolars were polished, sectioned, mounted, and stored for 5 days in a coffee solution at 37°C. The color and surface profile of the teeth were measured by spectrophotometry and a profilometric device, respectively. The specimens were divided into 3 groups of 10 and were brushed 2000 times (equivalent to 3 times a day for 1.5 months) in a brushing machine using 20 g of each toothpaste (Bencer, Beverly, and Colgate) mixed with 40 ml of distilled water. The color and surface profile were remeasured. Bonferroni test and repeated measures analysis of variance (ANOVA) were used to examine the abrasion. One-way ANOVA was used to assess the whitening. Results: The three toothpastes caused changes in the surface profile (P = 0.0001). ΔE was equal to 3.3 (within the acceptable range) in all groups (95% confidence interval). There was no significant difference in abrasion (P > 0.05) and color change (P = 0.884) among toothpastes. Conclusion: The results of this study showed that all the three used toothpastes have the abrasive and whitening effect on the samples significantly. The differences between the toothpastes were not significant.