فهرست مطالب

Dental Biomaterials - Volume:4 Issue: 3, 2017

Journal of Dental Biomaterials
Volume:4 Issue: 3, 2017

  • تاریخ انتشار: 1396/07/15
  • تعداد عناوین: 6
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  • Seyed Mohammad Javad Mortazavi, Ali Dehghani Nazhvani, Shoaleh Shahidi, Maoud Haghani, Maryam Paknahad Pages 419-423
    Statement of Problem: Previous studies have shown that exposure of dental amalgam fillings to MRI and mobile phones can increase microleakage of amalgam restorations.
    Objectives
    The aim of this study was to evaluate the effects of exposure to radiofrequency radiation emitted from indoor Wi-Fi access devices on microleakage of amalgam restorations.
    Materials And Methods
    Standard class V cavities were prepared on the buccal surfaces of 69 extracted human premolar teeth. The samples were divided into two exposure groups and one non-exposed control group of 23 teeth each. The specimens in the experimental groups were exposed to a radiofrequency (RF) radiation emitted from a commercial 2.4 GHz Wi Fi router. The distance between the Wi-Fi router and samples was 30 cm and the router was exchanging data with a laptop computer that was placed 20 m away from the router. Teeth samples in the first exposure group (group A) were exposed to RF for 3 days while the second exposure group (group B) was exposed for 6 days. Then the teeth were sectioned and scored for microleakage under a stereomicroscope.
    Results
    The score of microleakage was significantly higher in the exposure group A compared to that of the control group. However, the score of microleakage was not significantly different between the exposure group B and control group. Furthermore, the scores of microleakage was significantly higher in the exposure group A than that of the exposure group B.
    Conclusions
    Exposure of patients with amalgam restorations to radiofrequency waves emitted from commercial Wi-Fi routers can lead to increased microleakage of amalgam restorations.
    Keywords: Wi-Fi, Amalgam, Microleakage, Dental Amalgam, Radiofrequency (RF), Microwave
  • Mitra Farzin, Amin Golchin, Arash Badie, Janan Ghapanchi, Aisa Zamani, Fahimeh Rezazadeh, Mohammad Hassan Kalantari Pages 424-429
    Statement of Problem: Patient satisfaction is highly influenced by the retention of the denture. In some instances using denture adhesives may help the patient to achieve this goal.
    Objectives
    The purpose of this study was to evaluate the participants’ ’opinion concerning the effectiveness of two types of denture adhesives having the same composition (Fixative-powder, Protefix-cream).
    Materials And Methods
    Forty healthy patients (25 Males and 15 Females) who visited the Department of Prosthodontics of Shiraz Dentistry School were selected. The oral cavity was examined and patients with oral ulcers, history of allergic reaction, severe xerostomia, red, white and/or red and white lesions were excluded. The subjects were instructed to receive a sequence of treatment protocols. All patients applied Fixative-powder on the dentures for seven days. The Participants were asked to fill a questionnaire to include their opinion regarding the strength, biocompatibility, convenience and masticatory ability of the adhesive. On the next seven days, the patients were asked not to use the adhesives and they completed the same questionnaire again. Finally, all participants were asked to apply Protefix-cream on their dentures for a week followed by no cream application for another 7 days. These patients answered the same questionnaire and data were collected and analyzed using paired-samples t-test and Chi-square test.
    Result
    Denture adhesives significantly improved the overall satisfaction level of the patients (p =0.01). When testing the fixative powder, the satisfaction score of the participants during the first week (powder application) and the 2nd weak (no application) was 19.95±3.76 and 26.2±2.82, respectively. The overall satisfaction rate of the patients using the Protefix adhesive was 19.35±5.48 in the third week (adhesive application) and 25.85±4.35 in the fourth week (no application).
    Conclusions
    The study clarified that applying denture adhesives (both types) markedly improved the satisfaction rate in complete denture wearers without any complications. Further studies on a larger group is suggested to determine which kind of denture adhesive is more effective and if there is any possible side effects that restrict the use of such substances.
    Keywords: Retention, Dentured adhesive, Satisfaction
  • Farahnaz Sharafeddin, Atefeh Zareie, Zahra Jowkar Pages 430-436
    Statement of problem: One of the most important concerns in choosing a treatment plan for a fractured anterior teeth is their fracture pattern. Selecting the best restorative material is crucial in restoration of them.
    Objective(s)
    The present study was aimed to evaluate the effects of fracture pattern and the composite type on the fracture strength of fractured anterior maxillary teeth.
    Materials And Methods
    40 sound maxillary anterior teeth were randomly divided into four groups of ten teeth (H1, H2, O1, and O2). In H1 and H2, the incisal edges were cut horizontally by 3mm below the incisal edge and in O1 and O2 the incisal edges were cut obliquely from the middle of incisal edge to 6mm below the incisal edge on the proximal side. A nanohybrid composite (Z350) was used for restoring the samples of H1 and O1 whilst a silorane-based composite (P90) was used in H2 and O2. Fracture strength was measured and the failure mode was recorded. Data were analyzed using one way analysis of variance (ANOVA) and Tamhane’s post hoc tests. The level of significance was p ˂0.05.
    Results
    Restoration with composite resin Z350 showed a higher strength in both cutting patterns (p
    Conclusions
    Fracture resistance of the fractured anterior teeth restored with Z350 is higher than that achieved with P90 for both fracture patterns.
    Keywords: Anterior teeth, Fracture pattern, Fracture strength, Nanohybrid composite, Silorane-based composite
  • Ali Reza Danesh Kazemi, Farnaz Farahat, Maryam Hajimokhtari Pages 437-443
    Statement of Problem: Bulk-fill composites have recently been introduced. There are few studies conducted on them.
    Objectives
    Therefore, the aim of this study is to ascertain the effect of C-factor and the method of bulk-fill and nanohybrid composites placement on their microtensile bond strength to dentin.
    Materials And Method
    In this study, 40 extracted third human molars with no caries were collected. The specimens were disinfected and mounted on plaster blocks. Some rectangular cavities (5*3 mm2) were carved on the occlusal level of teeth in the depths of 2 and 4 millimeters. The molars were equally divided into eight study groups at random. After the carving was done, cavities were restored with universal (Tetric N-ceram/Ivoclar vivdent) and bulk-fill (Tetric N-ceram BulkFill/Ivoclar vivdent) composites with incremental and bulky techniques. Then they were stored in distilled water for one week. After that, they were cut into halves from the middle of the restoration spot at the buccolingual direction to turn them into rectangles. Then the microtensile bond strength test was carried out on them to record the failure resistance. The data were analyzed by conducting an ANOVA, a post hoc test, and a T-test. The failure mode was evaluated with a stereomicroscope.
    Results
    Using bulk-fill and nanohybrid composites in cavities filled massively in a 4-mm depth showed a significantly lower level of microtensile bond strength compared with other groups (p= 0.000). Failure was often adhesive in these groups.
    Conclusion
    Considering the research constraints of this laboratory study, bulk-fill composites can be cured well in a 4-mm depth. However, it is advised to use the incremental method in cavities with high C-factors due to the high stress caused by the polymerization shrinkage.
    Keywords: Microtensile bond strength, Bulk-fill composite, Nanohybrid composite, Dentin
  • Alireza Adl, Fereshteh Sobhnamayan, Sahar Ghanbaran, Shamseddin Ahzan Pages 444-448
    Statement of Problem: During root canal preparation, organic pulpal materials, bacteria and blood cells in combination with inorganic dentinal debris accumulate on the canal wall, producing an amorphous irregular smear layer. The effect of smear layer on the bond strength of endodontic sealers is controversial.
    Objective
    The aim of this in vitro study was to evaluate the bond strength of two resin-based root canal sealers to dentin, with or without the presence of smear layer.
    Materials And Methods
    The root canal of Sixty human single rooted teeth were prepared and irrigated by saline, NaOCl, or NaOClဴ. In each group, the root canals were obturated using AH Plus or EndoRez sealers. After 7 days, two horizontal slices of approximately 1.5mm thickness were obtained from the middle third of each root and the push-out bond strength of root canal fillings was assessed using the universal testing machine. Data were analysed using two-way ANOVA and Tukey tests. The significance level was set at p
    Results
    Regardless of sealer type, the highest bond strength was observed in group 2 (NaOCl) which was significantly different from those of group 3 (NaOCl EDTA) (p =0.003). Regardless of irrigation protocol, AH Plus showed higher bond strength compared to EndoRez (p =0.001).
    Conclusion
    Within the limitations of this study, it was concluded that the experimental sealers bonded better to dentine in presence of smear layer.
    Keywords: AH Plus, Bond strength, Endo Rez, EDTA, Smear layer, Sodium Hypochlorite
  • Ali Dehghani Nazhvani, Pardis Haddadi, Najmeh Sarafraz, Fatemeh Faghihi Pages 499-452
    A relatively rare subtype of squamous cell carcinoma (SCC) is spindle cell carcinoma (SPCC). It is composed of epithelium-derived spindle cells arranged in sheets with mesenchymal properties and small, hardly detectable regions of SCC, challenging its definite diagnosis. We encountered five cases of SPCC. In case one, chronic inflammation and subepithelial blister with leukoplakia was found 5 years before our examination. And later, exophytic features, keratotic papules and scar with elevated margins was seen on lateral border of the tongue. In case two, three and four, an abnormal soft tissue elevations were examined, and in the fifth case we examined the soft and bony specimen from the posterior aspect of maxillary ridge. We evaluated all of them histologically and immunohistochemically for cytokeratin to reach final diagnosis.
    Keywords: Cytokeratin, Spindle cell carcinoma, Squamous cell carcinoma, Immunohistochemistry