فهرست مطالب
Journal of Dental Research, Dental Clinics, Dental Prospects
Volume:8 Issue: 4, Autumn 2014
- تاریخ انتشار: 1393/11/21
- تعداد عناوین: 12
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Pages 189-196Background And AimsConnective tissue grafts with and without periosteum is used in regenerative treatments of bone and has demonstrated successful outcomes in previous investigations. The aim of present study was to evaluate the effectiveness of connective tissue graft with and without periosteum in regeneration of intrabony defects.Materials And MethodsIn this single-blind randomized split-mouth clinical trial, 15 pairs of intrabony defects in 15 patients with moderate to advanced periodontitis were treated by periosteal connective tissue graft + ABBM (test group) or non-periosteal connective tissue graft + ABBM (control group). Probing pocket depth, clinical attachment level, free gingival margin position, bone crestal position, crest defect depth and defect depth to stent were measured at baseline and after six months by surgical re-entry. Data was analyzed by Student’s t-test and paired t-tests (α=0.05).ResultsChanges in clinical parameters after 6 months in the test and control groups were as follows: mean of PPD reduction: 3.1±0.6 (P< 0.0001); 2.5±1.0 mm (P< 0.0001), CAL gain: 2.3±0.9 (P< 0.0001); 2.2±1.0 mm (P< 0.0001), bone fill: 2.2±0.7 mm (P< 0.0001); 2.2±0.7 mm (P< 0.0001), respectively. No significant differences in the position of free gingival margin were observed during 6 months compared to baseline in both groups.ConclusionCombinations of periosteal connective tissue graft + ABBM and non-periosteal connective tissue graft + ABBM were similarly effective in treating intrabony defects without any favor for any group. Connective tissue and periosteum can be equally effective in regeneration of intrabony defects.Keywords: Connective tissue, guided tissue regeneration, periosteum, periodontal pocket
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Pages 197-203Background And AimsAdding further fillers to dental resins may enhance their physical characteristics. The aim of this study was to evaluate the tensile strength of heat-curing acrylic resin reinforced by TiO2 nanoparticles added into the resin matrix.Materials And MethodsCommercially available TiO2 nanoparticles were obtained and characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) to determine their crystalline structure, particle size and morphology. TiO2-acrylic resin nanocomposite was prepared by mixing 0.5, 1 and 2 (wt%) of surface modified TiO2 nanoparticles in an amalgamator providing three groups of samples. Before curing, the obtained paste was packed into steel molds. After curing, the specimens were removed from the molds. The tensile strength test samples were prepared according to ISO 1567.ResultsTwo crystalline phases were found in TiO2 nanoparticles including: (i) anatase as the major one, and (ii) rutile. The average particle size calculated according to the Scherrer equation was 20.4 nm, showing a normal size distribution. According to SEM images, the nanocomposite with 1wt% TiO2 nanoparticles had a better distribution compared to other groups. In addition, the group by 1wt% TiO2 exhibited higher tensile strength with a significant difference compared to other groups. ANOVA showed significant differences between the contents of TiO2 particles in acrylic resin (F = 22.19; P < 0.001).ConclusionA considerable increase in tensile strength was observed with titania NPs reinforcement agents in 1wt% by weight. Further increase of TiO2 nanoparticles decreased the tensile strength.Keywords: Acrylic Resins, Materials Testing, Metal Nanoparticles, Tensile Strength
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Pages 204-209Background And AimsPolymethyl methacrylate, PMMA, is widely used in prosthodontics for fabrication of removable prostheses. This study was undertaken to investigate the effect of adding silver nanoparticles (AgNPs) to PMMA at 2% and 0.2% concentrations on compressive and tensile strengths of PMMA.Materials And MethodsThe silver nanoparticles were mixed with heat-cured acrylic resin in an amalgamator in two groups at 0.2 and 2 wt% of AgNPs. Eighteen 2×20×200-mm samples were prepared for tensile strength test, 12 samples containing silver nanoparticle and 6 samples for the control group. Another 18 cylindrical 25×38-mm samples were prepared for compressive strength test. Scanning electron microscopy was used to verify homogeneous distribution of particles. The powder was manually mixed with a resin monomer and then the mixture was properly blended. Before curing, the paste was packed into steel molds. After curing, the specimens were removed from the molds. One-way ANOVA was used for statistical analysis, followed by multiple comparison test (Scheffé’s test).ResultsThis study showed that the mean compressive strength of PMMA reinforced with AgNPs was significantly higher than that of the unmodified PMMA (P< 0.05). It was not statistically different between the two groups reinforced with AgNPs. The tensile strength was not significantly different between the 0.2% group and unmodified PMMA and it decreased significantly after incorporation of 2% AgNPs (P< 0.05).ConclusionBased on the results and the desirable effect of nanoparticles of silver on improvement of compressive strength of PMMA, use of this material with proper concentration in the palatal area of maxillary acrylic resin dentures is recommended.Keywords: Polymethyl methacrylate, compressive strength, tensile strength, acrylic resin, silver nanoparticles
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Pages 210-217Background And AimsStudies have shown decreased bond strength of composite resin to human and bovine bleached enamel. This study evaluated the effect of sodium ascorbate and delayed bonding on the bond strength of two adhesive systems to bleached enamel.Materials And MethodsThe labial surfaces of 150 sound bovine incisor teeth were abraded with abrasive paper. The teeth were randomly divided into 8 groups: A: control; B: bleached with 35% hydrogen peroxide; C: bleached with 35% hydrogen peroxide + sodium ascorbate gel; and D: bleached with 35% hydrogen peroxide + delayed bonding. In groups A‒D, silorane adhesive system and Filtek silorane composite resin were used. In groups E‒H, the same preparation methods of groups A‒D were used. Two-step self-etch Clearfil SE Bond adhesive systems and AP-X composite resin were administered. Shear bond strength of each group was measured. Two samples were prepared for each surface preparation for ultra-structural evaluation. Two-way ANOVA and Tukey test were used for data analysis at P< 0.05.ResultsThe interaction between the adhesive system type and surface preparation protocol was significant (P=0.014), with significant differences in shear bond strengths in terms of the adhesive systems (P< 0.01). There were significant differences in shear bond strength in terms of surface preparation techniques irrespective of the adhesive system (P< 0.01).ConclusionThe results showed that bleaching with 35% hydrogen peroxide decreased the shear bond strength values with both adhesive systems, and a one-week delay in bonding and 10% sodium ascorbate for 10 minutes restored the bond strength in both adhesive systems.Keywords: Delayed bonding, enamel bleaching, shear bond strength, silorane, based adhesives, sodium ascorbate
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Pages 218-224Background And AimsHeat generated within tooth during clinical dentistry can cause thermally induced damage to hard and soft components of the tooth (enamel, dentin and pulp). Geometrical characteristics of immature teeth are different from those of mature teeth. The purpose of this experimental and theoretical study was to investigate thermal changes in immature permanent teeth during the use of LED light curing units (LCU).Materials And MethodsThis study was performed on the second mandibular premolars. Experimental investigation was carried out for recording temperature variations of different sites of tooth and two dimensional finite element models were used for heat transfer phenomenon in immature teeth. Sensitivity analysis and local tests were included in the model validation phase.ResultsOverall thermal stimulation for 30 seconds by using a low-intensity LED LCU increased the temperature from 28°C to 38°C (a 10°C increase) in IIT and PIT. When a high-intensity LED LCU was used, tooth temperature increased from 28°C to 48°C (a 20°C increase). The results of the experimental tests and mathematical modeling illustrated that using LED LCU on immature teeth did not have any detrimental effect on the pulp temperature.ConclusionUsing LED LCU in immature teeth had no effect on pulp temperature in this study. Sensitivity analysis showed that variations of heat conductivity might affect heat transfer in immature teeth; therefore, further studies are required to determine thermal conductivity of immature teeth.Keywords: Finite element analysis, polymerization, pulp, thermal conductivity
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Antibacterial effect of all-in-one self-etch adhesives on Enterococcus faecalisPages 225-229Background And AimsThe aim of this study was to evaluate the antibacterial activity of one-step self-etch adhesives on Enterococcus faecalis on days 1, 7 and 14 with the use of modified direct contact test.Materials And MethodsThe modified direct contact test was used to evaluate the antibacterial effect of Adper Easy One, Bond Force, Clearfil S3 Bond, Futurabond M, G-Bond, iBond and OptiBond All-in-one adhesives on Enterococcus faecalis after aging the samples in phosphate-buffered saline for one, seven and fourteen days. Data were analyzed using one-way ANOVA and post hoc Tukey tests. Aging effect of each adhesive was evaluated by paired-sample test. In this study, P< 0.05 was considered significant.ResultsAll the tested adhesives exhibited antibacterial activity after one day and had significant differences with the positive control group (P< 0.05). After one week, OptiBond All-in-one, iBond and Futurabond M exhibited significant differences in bacterial growth from other groups (P< 0.05). There were no significant differences between the groups in two weeks (P >0.05).ConclusioniBond exhibited the highest antibacterial effect on E. faecalis after one week. Futurabond and OptiBond All-in-one exhibited antibacterial effects against E. faecalis for one week.Keywords: Adhesives, antibacterial agent, Enterococcus faecalis
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Pages 230-234Background And AimsDiabetic patients display an increased risk of oral disorders, and oral health related quality of life (OHRQL) might affect their management and treatment modalities. The aim of the present study was to determine OHRQL and associated parameters in patients with diabetes.Materials And MethodsIn this study two hundred patients were recruited from the diabetes clinic in Mustafa Khomeini Hospital in Tehran, Iran. OHRQL was assessed using Oral Health Impact Profile Questionnaire (OHIP-20). Also, another questionnaire was designed which contained questions regarding participants’ knowledge about oral complications of diabetes and oral health behavior. OHRQL was categorized as low and good. Data were analyzed using logistic regression at P = 0.05.ResultsOf the diabetic patients assessed, 77.5% were in good and 22.5% were in low categories of OHRQL. This quality was significantly associated with age (OR = 4.03, 95% CI = 1.63‒11.29), knowledge about diabetes oral complications (OR = 18.17 95% CI = 4.42‒158.6), educational level (OR = 26.31 95% CI = 4.2‒1080.3), referred for dental visit by physician (OR = 3.16 95% CI = 1.48‒6.69), frequency of brushing (OR = 10.29 95% CI = 3.96‒31.2) and length of time diagnosed with diabetes (OR = 6.21 95% CI = 2.86‒13.63).ConclusionOral health related quality of life was not negatively affected by diabetes mellitus in the assessed sample.Keywords: Diabetes, diabetics, oral health related quality of life
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Pages 235-239Background And AimsThe antioxidant and anti-inflammatory properties of propolis were studied. Since saliva contains antioxidants and radiotherapy of the head and neck mainly affects the saliva, salivary antioxidant defensive mechanism is compromised with oxidative stress produced by radiation therapy. Therefore, the aim of the present study was to investigate the effect of propolis on salivary total antioxidant capacity in irradiated rats.Materials And MethodsThe study was conducted on 28 rats, 7‒11 weeks of age (160±20 g), divided into four groups: saline with no radiation (S), saline and radiation (SR), propolis with no radiation (P) [400 mg/kg IP], propolis and radiation (PR) [400 mg/kg IP]. SP and PR were exposed to 15 Gy of gamma irradiation for 7 minutes and 39 seconds. The rats received intraperitoneal injections each day for 10 days, and their tongues and lips were daily examined for mucositis; saliva sample were also taken three times on days 0, 6, and 10.ResultsMucositis incidence appeared to be delayed in the PR compared to the SR, and the severity was significantly higher in the SR compared to the PR. No significant alterations were observed in salivary antioxidant levels during the experiment, except the SR group in which a significant reduction was found.ConclusionPropolis might reduce and delay radiation-induced mucositis in animal models; it might be able to prevent the reduction in salivary antioxidant levels in irradiated rats as well.Keywords: Antioxidant activity, propolis, saliva, radiation therapy
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Pages 240-245Background And AimsOdontogenic cysts and tumors have a wide spectrum of clinical characteristics that lead to the different management strategies. Since definite diagnosis is difficult in some cases, it has been suggested that CD56 may be a candidate marker for definitive diagnosis of some odontogenic tumors. The present study was designed to examine CD56 expression in lesions with histopathological similarities.Materials And MethodsIn this cross-sectional, analytical study the subjects were 22 ameloblastomas, 13 dentigerous cysts, 10 keratocystic odontogenic tumors (KCOT), 4 adenomatoid odontogenic tumors (AOT), 3 orthokeratinized odontogenic cysts, 3 calcifying odontogenic cysts (COC) and one glandular odontogenic cyst (GOC). All the samples were examined for CD56 immunoreactivity. Data were analyzed using chi-square test.ResultsTwenty cases (91%) of ameloblastomas, 3 (75%) AOT, 4 (40%) KCOT and one case of GOC were positive for CD56. None of the dentigerous cysts, COC and orthokeratinized odontogenic cysts was CD56-positive. There was a significant difference in the CD56 expression between ameloblastoma and dentigerous cyst, as well as COC. Also, KCOT showed significantly higher expression than orthokeratinized odontogenic cyst.ConclusionIn this study CD56 expression was limited to the odontogenic tumors and more aggressive cystic lesions. This marker can be a useful aid for distinguishing cysts and tumors from similar lesions.Keywords: Ameloblastoma, CD56, immunohistochemistry, odontogenic cysts, odontogenic tumors
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Pages 246-251Background And AimsAlthough salivary gland tumors are not very common, early diagnosis and treatment is crucial because of their proximity to vital organs, and therefore, determining the efficacy of new imaging procedures becomes important. This study aimed to evaluate the efficacy of magnetic resonance imaging (MRI) and color doppler ultrasonography parameters in the diagnosis and differentiation of benign and malignant salivary gland tumors.Materials And MethodsIn this cross-sectional study, color doppler ultrasonography and MRI were performed for 22 patients with salivary gland tumor. Demographic data as well as MRI, color doppler ultrasonography, and surgical parameters including tumor site, signal in MRI images, ultrasound echo, tumor border, lymphadenopathy, invasion, perfusion, vascular resistance index (RI), vascular pulse index (PI) were analyzed using Chi-square test, Fisher’s exact test, and independent t-test.ResultsThe mean age of patients was 46.59±13.97 years (8 males and 14 females). Patients with malignant tumors were older (P < 0.01). The most common tumors were pleomorphic adenoma (36.4%), metastasis (36.4%), and mucoepidermoid carcinoma (9%). Nine tumors (40.9%) were benign and 13 (59.1%) were malignant. The overall accuracy of MRI and color doppler ultrasonography in determining tumor site was 100% and 95%, respectively. No significant difference observed between RI and PI and the diagnosis of tumor.ConclusionBoth MRI and ultrasonography have high accuracy in the localization of tumors. Well-identified border was a sign of benign tumors. Also, invasion to adjacent structures was a predictive factor for malignancy.Keywords: Color, doppler, magnetic resonance imaging, salivary gland neoplasms, ultrasonography
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Pages 252-255Background And AimsNewer curing units such as plasma arc can polymerize the sealants in much shorter curing times. The aim of this study was to compare the effect of two different curing units on the micro-leakage of a fissure sealant material.Materials And MethodsSixty two extracted premolars without caries were randomly divided into two groups of 31 samples. Occlusal surfaces of all teeth were cleansed. Then, teeth surfaces were etched by 37% phosphoric acid. After rinsing and drying, occlusal surfaces of teeth were sealed by a fissure sealant. The sealant was then cured using either a halogen light curing unit or a plasma arc curing light. After sealing, the teeth were thermocycled for 500 cycles. The teeth were then sectioned and examined for micro-leakage. Statistical analyses were performed with Mann-Whitney test.ResultsThere was no significant difference between two groups regarding micro-leakage (P = 0.42).ConclusionResults showed that there was no significant difference between two different curing units. Therefore, plasma arc unit might be a useful alternative for sealant polymerization.Keywords: Dental leakage, fissure sealants, polymerization
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Pages 256-259Malignancies of the midface result in cosmetic deformities that make maxillofacial prosthesis as an integral part of the treatment plan. Facial defects can be devastating in their impact on physical structure and function of the affected individual, leading to potentional compromises in quality of life. Reconstruction of nasal defects is a challenge for the prosthodontist because of esthetic and retention problems associated with the facial prosthesis. This paper reports the rehabilitation of a partial nasal defect caused by basal cell carcinoma treatment using a nasal prosthesis made with silicone elastomers and mechanical and anatomical retentive aids. The patient had no problem with the prosthesis, except for a partial loss of extrinsic coloration in the two-year follow-up.