Journal of Dental School, Shahid Beheshti University of Medical Sciences

Objectives: This study aimed to compare the in vitro cytotoxic activity of propolis, a bioactive material made by the honeybee, and calcium hydroxide (CH) and their effect on formation of mineralized nodules by human dental pulp stem cells (HDPSCs).

Methods: In this in vitro study, HDPSCs were obtained from the Cellular and Molecular Oral Biology Laboratory of School of Dentistry, Shahid Beheshti University of Medical Sciences. In order to evaluate the proliferative effect of propolis and CH, HDPSCs were incubated with different concentrations of propolis (0-32mg/mL) and CH (0-4.8 mg/mL). Twenty-four and 48 hours later, the methylthiazolyl diphenyl-tetrazolium bromide (MTT) assay was carried out to evaluate the proliferation potential and viability of HDPSCs treated with propolis and CH. The effect of propolis and CH on mineralization of HDPSCs was assessed by alizarin red staining.

Results: The MTT assay revealed that propolis at its highest concentration caused the greatest proliferation after 24 and 48 hours. Alizarin test showed that the lowest concentrations of CH and propolis at 14 days induced the formation of calcium nodules but at 21 days, propolis was deposited on the cells and calcification was not well recognizable.

Conclusion: Propolis led to higher cell vitality at all concentrations in comparison to CH. However, due to its deposition on the cells, its effects on mineralization at 48 hours could not be determined.

Objectives: Metal-ceramic restorations are the standard by which all esthetic restorations are measured. Fracture of dental restorations is a multifactorial problem, which is serious and costly. Debonding of porcelain from the metal substructure and the bond strength depend on many factors. The purpose of this study was to determine whether the opaque porcelain thickness has a significant effect on metal ceramic bond strength utilizing the ISO 9663 standard crack initiation test.

Methods: Thirty rectangular Ni-Cr metal bars (25×5×0.3mm) were fabricated according to ISO9663 standards. The metal bars were divided into three groups of 10. Opaque, body and enamel Noritake porcelain were applied on the middle of the bar according to ISO9663 standards up to 1mm porcelain thickness. The opaque porcelain thicknesses were 0.1, 0.2, and 0.3 mm, respectively in the three groups. The 3-point bending test was applied according to the ISO9663 standards and fracture strength (F_fail) was measured using a universal testing machine with a crosshead speed of 1.5mm/minute.

Results: Analyses of the data by one-way ANOVA demonstrated no significant differences in bond strength among the three experimental groups (P=0.26).

Conclusion: Within the limitations of this study, it is concluded that 0.1mm opaque porcelain provides sufficient bond strength between metal and ceramic in metal-ceramic restorations.

Objective: The aim of this study was to assess the effect of condensation pressure on microleakage of mineral trioxide aggregate (MTA).

 Methods: This in vitro experimental study was conducted on 55 sound single-rooted straight-canal extracted human teeth. The teeth were sectioned at the cementoenamel junction (CEJ) and at 3 mm above the root apex. The roots were mounted in putty. Samples were then divided into three experimental groups (n=15) and positive and negative control groups (n=5). After filing of the root canals to file #50, white ProRoot MTA paste was prepared according to the manufacturer’s instruction and applied to the canals using condensation pressure of 0.44, 3.22 and 8.88 Mpa in groups one to three, respectively. After a 48-hour setting time, each root was connected to the fluid filtration system to measure microleakage. The mean microleakage rate of the groups was calculated and compared using one-way ANOVA and least significant difference test.

Results: The mean microleakage with condensation pressure of 0.44, 3.22 and 8.88 MPa was 1.70×10^-4, 1.17×10^-4  and 0.48×10^-4 µL/minute, respectively. One-way ANOVA showed that the mean microleakage rate was significantly different among the groups (P<0.05). The lowest microleakage was observed in condensation pressure of 8.88 MPa.

Conclusion: Within the limitations of this study, the results showed that increase in condensation pressure decreased the rate of microleakage.

Objectives: Presence/absence of cervical lymph node metastasis plays a critical role in prognosis and survival of patients with oral squamous cell carcinoma (SCC). This study was designed to assess the diagnostic accuracy of computed tomography (CT) scan for detection of cervical lymph node metastasis in oral SCC in comparison with histopathological analysis after neck dissection.

Methods: In this retrospective cross-sectional study, pathology and CT reports of 50 patients with oral SCC were retrieved from the archives of Taleghani and Shariati Hospitals and data regarding the site of involvement, lymph node metastasis, level of cervical involvement and size of involved lymph node were retrieved from patient files. The results of CT scan and pathology reports were compared and the accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of CT scan were calculated compared to the gold standard (pathology report). Basic statistics was meed for analyz the data.

Results: The sensitivity of CT scan for detection of metastatic cervical lymph nodes was 69.23% compared to the pathology report (gold standard). The specificity, PPV and NPV were 27.02%, 25% and 71.42%, respectively. The diagnostic accuracy of CT scan was 38%.

Conclusion: Based on the results, CT scan is not reliable for detection of metastatic cervical lymph nodes in oral SCC, and more advanced techniques may be indicated for assessment of cervical lymph node involvement and deciding on the most efficient surgical approach in patients with oral SCC.

Objective: Cone beam computed tomography (CBCT) is applied for the imaging of the maxillofacial and dental structures, particularly for surgical treatments and dental implants. The aim of this study was to assess the effect of slice thickness on the accuracy of CBCT linear measurements.

 Methods: In this diagnostic accuracy study, forty-two titanium pins with the same dimensions were inserted into seven dry sheep mandibles. The length of the pins before the insertion was carefully measured by a digital caliper, (0.01mm accuracy). Imaging of the mandible performed using CBCT New Tom VGi. After image reconstruction by NNT Viewer, linear measurements were made on cross-sectional slices (thicknesses of 0.125, 0.5, 1 and 2mm) by three radiologists. The accuracy of measurements assessed using descriptive indices and compared between different slice thicknesses by repeated measures ANOVA.

Results: Repeated measures ANOVA showed a significant difference between different slice thicknesses (P=0.024). According to the least significant difference (LSD) test, the difference in absolute errors was significant in all thicknesses (P=0.024). Measurements at 0.125 mm thickness were significantly different from others, with a higher error rate (mean absolute error=0.17). Measurements at 0.5mm thickness showed a significant difference with those at 0.125 and 2mm (mean absolute error=0.15). Measurements at 2mm thickness were significantly different from those at 0.125 mm thickness (mean absolute error=0.13).The average error rate was lower in 2mm thickness and the measurements were more accurate.

Conclusion: A statistically significant difference was seam between CBCT measurements and actual sizes in different slice thicknesses. The differences were below 1mm, and clinically acceptable.

Objectives: Different chelators may be used during root canal treatment, offering various advantages including lubricant effect inside the canal and smear layer removal. However, chelator residues in narrow root canals can lead to apical microleakage. The aim of this in-vitro study was to compare apical microleakage following the use of three root canal chelators via fluid filtration method in root canals instrumented with ProTaper rotary system.

Methods: Sixty-eight distobuccal canals of maxillary first molars were randomly divided into six groups of four experimental (n=15) and a positive and a negative control group (n=4). In groups one to three, RC-Prep, 17% EDTA and Glyde File Prep were used as chelators, respectively and sodium hypochlorite (NaOCl) was used as irrigant in all groups except for group four. In group four, root canals were instrumented without chelators and only saline was used for irrigation. Root canals in all groups were prepared using ProTaper rotary system up to F₂ file and filled using cold lateral condensation technique with gutta-percha and AH26 sealer. Apical microleakage was assessed by fluid filtration method. The data were subjected to Kruskal-Wallis test.

Results No significant differences were noted among the experimental groups regarding apical microleakage (P>0.05). However, preparations with RC Prep+ NaOCl and Glyde File Prep+ NaOCl yielded the highest and the lowest values of apical microleakage, respectively.

Conclusion: Use of different chelators did not cause statistically significant difference in apical microleakage of root canals.

Objective: Leukocyte adhesion deficiency (LAD) is a rare, autosomal recessive inherited disorder; LAD-I which is the most common type, occurs due to mutations in the CD18 gene. This mutation down-regulates the expression of ß2 integrin leukocyte cell surface molecules, which are necessary for the adhesion of leukocytes to endothelial cells, transendothelial migration, and chemotaxis. The major symptoms are recurrent severe bacterial infections without pus formation, recurrent or progressive necrotizing soft tissue infections, marked leukocytosis and severe progressive periodontitis accompanied by alveolar bone loss, periodontal pockets, and partial or total early loss of primary and permanent teeth.

Cases: Herein, we report a case of moderate LAD-I in a nine year-old boy with severe alveolar bone loss and aggressive periodontitis. For several years, approximately every month, the patient was followed up to evaluate the status of primary and permanent dentition. During these visits, scaling and root planing were performed and severely mobile teeth were extracted. The patient is now under regular follow up.

Conclusion: This case confirms the need for interactions between the medical groups to identify and manage medically compromised children with rare diseases. It is important to include LAD in the differential diagnoses of children presenting with periodontal disease. Early correct diagnosis of LAD has various benefits for patients.

Objective: Cemento-ossifying fibroma defines as a relative rare osteogenic neoplasm of the jaw. This tumor includes fibrous and osseous components. Odontoma is the most common odontogenic tumor containing enamel ,dentin ,cementum and pulp tissue. in this paper we report a  rare case of ossifying fibroma associated with compound odontoma in the mandible.

Case: A 37-years-old woman was referred to Oral Medicine department , Shahid Beheshti Dental School with complaint of swelling in the anterior part of the mandible, over 6 years period. Clinical examination revealed mandibular enlargement in right –anterior region with labial and lingual expansion and canine missing . panoramic view showed a large mixed radiolucent -  radiopaque lesion associated with impacted canine.The differential diagnosis include calcifying odontogenic cyst (COC) and cemento-ossifying fibroma(COF). Histopathologic examination established diagnosis of COF with multiple compound odontoma .

Conclusion: The relationship between the occurrence of these two lesions is not clear and more studies are needed to establish the relationship between them.