Vol 16, No 2 (2019)

Published: 2019-04-30

Original Article

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    Objectives: This study aimed to assess the effect of erbium-doped yttrium aluminum garnet (Er:YAG) and erbium, chromium: yttrium, scandium, gallium, garnet (Er,Cr:YSGG) lasers on the shear bond strength (SBS) of ceramic brackets debonding from the surface of composite blocks.
    Materials and Methods: Thirty-six composite blocks were fabricated using Filtek Z250 light-cure composite. The surface of blocks was etched with 37% phosphoric acid for 30 seconds and then rinsed with water for 20 seconds and dried. Maxillary right central incisor ceramic orthodontic brackets were bonded to the surfaces of composite blocks using Transbond XT adhesive and were cured for 40 seconds. Twelve samples were irradiated with Er:YAG laser, while 12 samples were irradiated with Er,Cr:YSGG laser, and the brackets were then debonded using a universal testing machine. Twelve samples served as controls (debonding using the universal testing machine without using a laser). The adhesive  index score and bracket or composite cracks were evaluated under a stereomicroscope. One-way analysis of variance (ANOVA) was used for the comparison of the three groups. Kruskal-Wallis test was used to compare the ARI scores.
    Results: The mean SBS was 17.01±5.22 MPa with Er:YAG laser, 18.03±6.46 MPa with Er,Cr:YSGG laser, and 16.61±6.73 MPa in the control group; the difference of the three groups was not significant (P=0.835). The difference in the ARI scores and enamel and composite cracks was not significant either (P>0.05).
    Conclusions: This study did not show any reduction in the bond strength of ceramic bracket to composite blocks after Er:YAG and Er,Cr:YSGG laser irradiation.

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    Objectives: The present study aimed to investigate the effects of propolis nanoparticles (prpNPs) on antimicrobial property and shear bond strength (SBS) of orthodontic composite bonded to bovine enamel.
    Materials and Methods: Sixty bovine teeth were randomly divided into five groups (n=12). PrpNPs were prepared at concentrations of 0% (control), 1%, 2%, 5%, and 10% in Transbond XT composite and were used to bond stainless steel brackets to the teeth. A universal testing machine was used to measure the SBS between brackets and teeth. After debonding of brackets, the adhesive remnant index (ARI) on bracket bases was measured. In the microbial test, composites with the aforementioned concentrations of prpNPs were cured in metal discs. The bacteria included Streptococcus mutans (S.mutans), Streptococcus sanguinis (S.sanguinis), and Lactobacillus acidophilus (L.acidophilus), and antimicrobial effects of prpNPs were investigated by anti-biofilm, disc agar diffusion (DAD), and eluted component tests.
    Results: The group with 10% of prpNPs showed the lowest SBS. The growth of colonies of S.mutans and S.sanguinis at all concentrations (except for 1%) was significantly lower than the control group. The growth of L.acidophilus colonies significantly reduced at 5% and 10% concentrations. Growth inhibition zone was developed at 2%, 5%, and 10% concentrations for S.mutans and S.sanguinis. The lowest numbers of S.mutans and S.sanguinis colonies at all concentrations were observed on the 15th day. L.acidophilus colonies decreased significantly at all concentrations (except for 1%) until the 30th day.
    Conclusions: Nano propolis has a significant antimicrobial effect at 2% and 5% concentrations, and the ...

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    Objectives: The purpose of the present study was to evaluate the antimicrobial effect of various sizes and concentrations of zinc oxide (ZnO) nanoparticles on Streptococcus mutans (SM), Enterococcus faecalis (EF), Lactobacillus fermentum (LF), and Candida albicans (CA).
    Materials and Methods: Solutions at the concentration of 10 µg/ml were prepared using 20-nm, 40-nm, and 140-nm nano ZnO (nZnO) powder.
    The antimicrobial effect of nZnO was determined using the disk diffusion method. The inhibition zone (mm) was measured using a ruler. Data were analyzed by analysis of variance (ANOVA) and the Bonferroni correction. The minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of nZnO were determined using the broth microdilution method in Mueller-Hinton Agar (MHA) for SM and EF, De Man, Rogosa, and Sharpe (MRS) agar, and Sabouraud Dextrose Agar (SDA).
    Results: The greatest inhibition zones were observed against SM with 20-nm and 40-nm nZnO, while 140-nm nZnO formed the greatest inhibition zones against SM and EF. The smallest inhibition zones were observed against CA with the three nZnO particle sizes. The MICs for CA with 40-nm and 140-nm particles and for LF with 140-nm particles were higher than 10 µg/ml. A significant correlation was found between the particle size and the antibacterial activity against SM (P=0.00), LF, and EF (P<0.02).
    Conclusions: The antimicrobial activity of nZnO increases with decreasing the particle size. The greatest antimicrobial effect was observed against SM and EF. SM is more sensitive to the changes in the particle size compared to other bacteria.

  • XML | PDF | downloads: 81 | views: 1098 | pages: 113-120

    Objectives: The objective of this study was to evaluate the antimicrobial activity of the essential oil obtained from oleo-gum-resin and seeds of Ferula assa-foetida.
    Materials and Methods: Ferula assa-foetida plants were collected from Tabas, Yazd Province, Iran, during summer 2017. Then, essential oils were obtained from its seeds and oleo-gum-resin using hydrodistillation. Gas chromatography-mass spectrometry (GC-MS) test was performed to determine the contents of the essential oils. Four different doses of each oil were prepared (2.5, 5, 10, and 20 μg/ml), and the antimicrobial activity of each dose against four oral bacteria (Streptococcus mutans, Streptococcus sobrinus, Streptococcus sanguis, Streptococcus salivarius, and Lactobacillus rhamnosus) was evaluated using the disk diffusion method. The data were analyzed using analysis of variance (ANOVA) and Kruskal-Wallis test in SPSS 17 software.
    Results: The GC-MS findings exhibited that the main compounds found in essential oils yielded from the seeds and oleo gum resin were (Z) -1-propenyl sec-butyl disulfide and (E) -1-propenyl sec-butyl disulfide. Ferula assa-foetida plant showed a significant antimicrobial effect (P<0.05). The essential oil from Ferula assa-foetida oleo-gum-resin had significantly stronger antibacterial properties compared to the essential oil from Ferula assa-foetida seeds (P<0.001). Both essential oils showed antibacterial properties similar to that of Chlorhexidine. The growth inhibition zone was significantly dependent on the essential oil concentration for all bacteria (P<0.05).
    Conclusions: Our study revealed that essential oils from seeds and oleo-gum-resin of Ferula assa-foetida have antimicrobial properties. More laboratory studies are required to reach a definitive conclusion.

  • XML | PDF | downloads: 77 | views: 932 | pages: 121-129

    Objectives: This study aimed to assess the effect of 0.05% sodium fluoride (NaF) mouthwash on the surface roughness and friction between ceramic brackets and rhodium-coated (RC) and uncoated stainless steel (SS) wires.
    Materials and Methods: This experimental study was performed on 48 maxillary premolar ceramic brackets. Twenty-four pieces of RC-SS wires were used. Samples were divided into four groups. Groups 1 and 2 were immersed in artificial saliva, and groups 3 and 4 were immersed in a solution consisting of artificial saliva (9%) and mouthwash (91%). To assess surface roughness, images were obtained from the surface of wires and brackets with atomic force microscopy (AFM) and scanning electron microscopy (SEM) before and after the intervention. To assess friction, the wires were ligated into brackets, and friction was measured at a crosshead speed of 0.5 mm/minute using a universal testing machine. Data were analyzed using one-way analysis of variance (ANOVA) at the 0.05 significance level.
    Results: Friction during sliding in RC wires was significantly less than that in SS wires (P<0.05). Increase in the friction in SS wires by mouthwash was significantly greater compared to RC wires (P<0.05). Surface roughness coefficients of the wires before the intervention were not significantly different. The surface roughness of the wires significantly increased after the intervention and it was greater in SS wires than in RC wires (P<0.05).
    Conclusions: Considering the lower friction and surface roughness of SS-RC wires compared to SS wires, SS-RC wires may be a better alternative for use with ceramic brackets.

  • XML | PDF | downloads: 95 | views: 1015 | pages: 130-135

    Objectives: The development of teeth is affected by genetic and environmental factors. Amoxicillin is a widely prescribed semi-synthetic antibiotic. Its most frequent side effects are gastrointestinal disorders and hypersensitivity reactions. The purpose of this study was to determine the effect produced by amoxicillin administration on dental enamel and dentin in Wistar rats.
    Materials and Methods: Twelve pregnant adult Wistar rats were equally divided into four different groups. Negative controls were prescribed with a saline solution. Positive controls were prescribed with tetracycline (130 mg/kg). The other two groups were treated with amoxicillin doses of 50 and 100 mg/kg (every 8 hours), respectively. The treatments were daily administered by oral gavage from the 13th gestation day to the end of gestation. After birth, the offspring also received the same treatment as their mothers from day one to day twelve. After 24 hours, the newborns were sacrificed, the jaws were dissected, and the first molar teeth were collected. The samples were fixed in 10% for¬maldehyde solution and were histomorphologically and histopathologically observed to determine enamel and dentin abnormalities.
    Results: The mean ameloblastic layer thickness, enamel thickness, odontoblastic layer thickness, and dentin thickness were significantly different in the tetracycline group and the amoxicillin 50 and 100 mg/kg groups compared to the control group. Also, dentin hypomineralization and vacuolization of the odontoblastic layer were observed in the tetracycline- and amoxicillin- treated groups.
    Conclusions: This study showed that amoxicillin interferes with amelogenesis and dentinogenesis and reduces enamel and dentin thickness.

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    Objectives: Microleakage is the most important factor responsible for the destruction of restoration margins. The aim of this study was to assess the effect of mechanical load cycling on microleakage of four types of glass ionomer cement (GIC) in comparison with a flowable composite resin.
    Materials and Methods: In this in-vitro experimental study, 100 Class V cavities were prepared on the buccal and lingual surfaces of 50 intact premolars. The prepared cavities were divided into five groups of (A) Z350, (B) Equia Forte, (C) encapsulated Fuji II LC, (D) hand-mixed Fuji II LC, and (E) Ketac Molar. All the samples were thermocycled (×2,000, 5-55°C), and half of the samples in each group were load cycled. All the teeth were then immersed in 0.5% basic fuchsine for 24 hours, sectioned, and observed under a stereomicroscope. Data were analyzed with Kruskal-Wallis and Mann-Whitney-U tests. Comparison between the incisal and gingival microleakage was made with Wilcoxon test. P<0.05 was considered statistically significant.
    Results: Load cycling and type of restorative material had a significant effect on microleakage. Gingival microleakage was significantly higher than occlusal microleakage with Equia Forte, encapsulated Fuji II LC, hand-mixed Fuji II LC, and Ketac Molar in the absence of loading, and with Z350 after loading.
    Conclusions: The sealing ability of Z350 under load cycling was better than that of Equia Forte, hand-mixed Fuji II LC, and Ketac Molar. The marginal integrity of encapsulated Fuji II LC was not significantly different than that of Z350.

Case Report

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    The aim of the present report was to discuss a unique case of gingival plasma cell granuloma (PCG) in a hypertensive patient on Amlodipine therapy. Also, we attempt to emphasize the importance of considering primary and advance investigations before making a definite diagnosis. PCG is an extremely rare, reactive, non-neoplastic lesion characterized by the predominance of polyclonal plasma cells. Drug-induced gingival overgrowth is a known side effect of Amlodipine. A hypertensive 60-year-old female patient reported with a chief complaint of swollen gums and discomfort in the upper front teeth region. A provisional diagnosis of Amlodipine-induced gingival overgrowth, combined gingival overgrowth, and fibroma was suggested. Surprisingly, histopathology revealed it to be a plasma cell lesion which was confirmed by advanced investigations, thereby establishing a confirmatory diagnosis of PCG.

  • XML | PDF | downloads: 71 | views: 993 | pages: 149-152

    Flabby ridge is an excessive movable fibrous tissue, usually affecting the maxillary and mandibular edentulous ridges. It is a typical finding frequently observed in the maxillary anterior region. It usually occurs when natural teeth oppose an edentulous ridge or in long-term denture wearers. The management of flabby ridges includes surgical intervention, implant-retained prostheses, and conventional dentures fabricated using the modified impression technique. This case report depicts a modified technique with the utilization of an aluminum mesh double tray and polyvinylsiloxane impression material for the management of a flabby ridge in the maxillary arch.

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    Dental implants are highly recommended to improve retention, stability, and support of prostheses in edentulous patients with large surgical defects. Depending on the size of the defect a bone graft procedure might be necessary. However, due to limitations of bone grafts some complications might negatively affect the prosthetic rehabilitation of the patient. This case presents some of these prosthetic problems following surgical resection and autogenous bone graft procedures.