Journal of Dentistry, Shiraz University of Medical Sciences
Volume:16 Issue: 2, Jun 2015

Low Grade Central Osteosarcoma (LGCO) is a rare subtype of osteosarcoma that is less aggressive than conventional osteosarcoma. The importance of LGCO lies in the fact that regarding microscopic and radiographic features, it occasionally simulates some benign jaw lesions and would consequently be misdiagnosed in many patients.The present study was conducted to collect the information and descriptive analyses related to ten cases reported between 1987 and 2010, including a sample reported by the authors emphasizing on diagnostic errors and the prevailing misdiagnosis. The aforementioned reports were gathered in full-texts through Google and PubMed search engines. The results of this study showed that the pathologists should exactly evaluate the clinical, radiographic, and histopathologic features in order to observe the evidence of invasion.

Statement of the Problem: Self-etch adhesives can activate matrix metalloproteinase (MMP) which hydrolyzes organic matrix of demineralized dentin. Epigallocatechin gallate (EGCG), especially found in green tea, could inhibit the activation of MMP. The aim of this study was to evaluate the effect of adding Epigallocatechin gallate (EGCG) into two types of adhesives on dentin bond strength. In this experimental study, 64 extracted third molars were randomly divided into 16 groups. Clearfil SE Bond and Filtek Silorane System with 0 µM, 25µM, 50µM, and 100µM concentration of 95% EGCG were used for bonding. Following the bonding and fabrication of beams (1±0.1 mm2) and storage in distilled water, the specimens were subjected to thermal cycles. Microtensile bond strengths of 8 groups were examined after 24 hours and others were tested after 6 months. The fracture modes of specimens were evaluated by stereomicroscope and SEM. Data were analyzed by three-way ANOVA and t-test (α = 0.05). The results of the three- way ANOVA test showed that types of bonding, storage time and interactive effect of EGCG concentration and bonding influenced the bond strength of specimens significantly (p<0.05). The results of the t-test indicated that storage time only had significant effect on bond strength of Clearfil SE Bond with no EGCG (p= 0.017). The most common failure modes in Filtek Silorane System groups and Clearfil SE Bond groups were adhesive and mixed/cohesive, respectively. The results of SEM at different magnifications showed that most fractures have occurred in the hybrid layer. Although adding 100 µM volume of EGCG to Clearfil SE Bond can preserve the dentin bond, incorporation of EGCG in the silorane system, especially in high concentrations, decreases the bond strength after 6 months.

Statement of the Problem: Tonsilloliths are relatively common clusters of dystrophic calcified material that form in the tonsillar crypts, mostly the palatine tonsils. Although they may be asymptomatic, some cause halitosis, cough, dysphagia, and foreign body sensation, as well as otalgia. Since tonsilloliths can be detected on panoramic views as radiopaque lesions, and misdiagnosis may lead to wasting time and cost, dentist should be familiar with radiographic characteristics of this type of calcification. This study was conducted to determine the prevalence and the pattern of distribution of tonsilloliths on panoramic radiographs. This cross-sectional study was based on 2000 panoramic radiographs from 1030 female and 970 male aged 6-75 years old evaluated for the presence and pattern of tonsillolithiasis, between 2011 and 2013 in Shiraz, Iran. Chi–square test and odds ratio were used to evaluate the relationship between tonsillolithiasis and gender. p< 0.05 was considered as statistically significant. Out of the 2000 individuals, 101 cases (5.05%) had tonsilloliths on panoramic radiographs out of which 61 were male (60.4%) and 40 were female (39.6%), with age range of 18 to 65. Forty patients (39.6%) had both left and right sides involved, 25 of tonsilloliths (24.75%) were located on the right and 36 on the left side (35.65%). Men were more likely to develop tonsilloliths (p= 0.014). Tonsilloliths are not very common finding and can be detected on nearly 5.05% of panoramic radiographs. Most of the cases are unilateral with a diameter less than 2mm.

Statement of the Problem: Dental caries is the most common disease of childhood. Using probiotics has recently been introduced to reduce the incidence of dental caries.It consists of live microbial food supplements that beneficially affect the host, and hence are considered an alternative way to eradicate the infections. The aim of this study is to evaluate the effect of consumption of probiotic yogurt on the children’s salivary cariogenic microflora. A double-blind randomized study was performed recruiting 2 parallel groups; 24 healthy children in the case and 25 children in the control group. All healthy children were followed- up over 4 periods. Periods 1 and 3 were wash-out periods with duration of 1 and 2 weeks, respectively. During periods 2 and 4 (2weeks duration each), the case group consumed 200g yogurt containing Bifidobacterium lactis (1×106 per gram) once daily and the control group consumed normal yogurt. Salivary Streptococci mutans and Lactobacilli were enumerated before and after the yogurt consumption periods. Pre- and post-treatment values within and between regimens were compared using the t-test and paired samples. There was a reduction in Streptococcus mutans and Lactobacillus counts in the control group, but for Streptococcus mutans, the count reduction between phases 1 and 4 was statistically significant (p= 0.009). In the case group, neither the Streptococcus mutans count nor the Lactobacilli count was significantly reduced. Based on the findings of this study, short-term daily consumption of probiotic yogurt containing Bifidobacterium lactis could not reduce the levels of salivary Streptococcus mutans and Lactobacilli in 6 to 12 year-old children, while normal yogurt could reduce the Streptococcus mutans counts significantly.

Statement of the Problem: The expression of minichromosome maintenance-3 (MCM3) proteins and their diagnostic value in oral mucosal dysplasia and squamous cell carcinoma (SCC) is not well known. This study was conducted to evaluate the usefulness of minichromosome maintenance 3 (MCM3) as a biomarker for diagnosis of oral premalignant lesions and SCC. In this study, 31 oral SCC, 20 dysplastic epithelium and 20 controls were selected and immunohistochemical staining was done for MCM3. ANOVA, Tukey HSD, Mann-Whitney and Kruskal-Wallis tests were used to compare the groups and the correlation between different grades. There was increasing trend of MCM3 from control to dysplastic epithelium and from dysplastic epithelium to SCC both in suprabasal layers and in total epithelial layers. MCM3 expression was elevated with increasing the grade of dysplasia, but there was no statistically significant difference (p= 0.93). The expression was also increased in high grades of SCC compared to lower grades. MCM3 can be used as a useful biomarker in the diagnosis of premalignant lesions and oral SCC.

Statement of the Problem: Cardiovascular disease and osteoporosis are major health dilemmas. Osteoporotic patients frequently display vascular calcification that consequently increases the cardiovascular morbidity and mortality. This study aimed to investigate the relation of osteoporosis, vascular calcification (atheroma, intima-media thickness (IMT)) and elongated styloid process (ESP) in a sample of osteoporotic and normal female individuals. This study recruited 78 women who were assessed for bone mass density (BMD). Sample included individuals with normal BMD (n=13, 17 %), osteopenia (n=36, 46 %), and osteoporosis (n=29, 37%). The presence of atheroma and IMT was examined using color Doppler ultrasonography (CD-US). In addition, digital panoramic radiographs (PRs) were obtained to assess ESP. In this study, 55 subjects (70%) with low BMD exhibited at least one side ESP. Femoral BMD decreased significantly in subjects with ESP (p= 0.03). Bilateral ESP was correlated with the presence of atheroma (p= 0.029). The CIMT was greater in patients with ESP, although the relation was not significant. The obtained data suggest referring the aged individuals with ESP for BMD assessment and individuals with low bone mass and ESP for more cardiovascular risk assessment.

Statement of the Problem: Enamel and dentin marginal sealing ability of the new adhesive materials could play an important role in successful restoration on fluorosed teeth. The aim of this in vitro study was to evaluate the marginal microleakage of low-shrinkage silorane-based composite, nano-ionomer, and methacrylate-based composite through self-etching approach or with enamel acid etching. Seventy-two extracted human molars with moderate fluorosed (according to Thylstrup and Fejerskov index, TFI= 4-6) were randomly divided into six groups (n=12). Class V cavities were prepared on the buccal surface at the cementoenamel junction and restored with Clearfil SE Bond/Clearfil AP-X (methacrylate composite), Silorane Adhesive System/Filtek P90, and nano primer/nano-ionomer according to the manufacturer’s instructions (self-etching approach) or with additional selective enamel acid etching before primer application for each adhesive. After water storage and thermocycling, microleakages of the samples were assessed using dye-penetration technique at the enamel and dentin margins. Data were analyzed using non-parametric tests (α = 0.05). There was a significant difference among the six groups at the enamel margin (p= 0.001), but not at the dentin margin (p= 0.7). For all the three adhesive materials, additional enamel etching resulted in significantly reduced microleakage at the enamel margin (p< 0.05). Methacrylate- and silorane-based composites and nano-ionomer revealed a similar and good performance in terms of dentin marginal sealing, but not at the enamel margin. The additional selective enamel etching might improve enamel sealing for the three materials.

Statement of the Problem: The stability of orthodontic treatment depends on preserving the patient’s pretreatment arch form and arch size during and after treatment. This investigation was aimed to study the size and shape of Iranian mandibular dental arch and evaluate the correlation of their average dental arch with commercially available preformed rectangular nickel-titanium arch wires. In this study, 148 subjects were selected among students of Shiraz University of Medical Sciences. The inclusion criteria were having Angle class I in molar and canine relationships, and normal growth pattern. Intercanine and intermolar widths were measured after scanning their mandibular dental casts. Three main arch form templates; square, ovoid and tapered (Orthoform TM; 3M, Unitek, CA, USA) and 12 commercially available preformed mandibular nickel-titanium arch wires were scanned. Intercanine and intermolar widths of arch wires were compared with dental arch widths of the study samples. Arch width, arch form and the most appropriate arch wire were determined for each cast. Student’s t-test was used to compare arch widths and arch depths of male and female subjects. Coefficient of variance was used to determine the variability of indices in the study samples. Most preformed arch wires were wider than the average width of the normal Iranian dental arch. The most frequent arch form in Iranian population was tapered. Inter molar width was the only statistically significant variable between males and females. Variation in available preformed arch wires does not entirely cover the range of diversity of the normal dental arch of our population. Narrow arch wires with a tapered shape are better consistent with the Iranian lower arch.

Statement of the Problem: Although all-ceramic restorations are broadly used, there is a lack of information concerning how their fit is affected by fabrication procedure and marginal configuration. The purpose of this study was to evaluate the marginal fit of zirconia CAD/CAM ceramic crowns before and after porcelain firing. The influence of finish line configuration on the marginal fit was also evaluated. Twenty standardized zirconia CAD/CAM copings were fabricated for chamfer and shoulder finish line designs (n=10). The marginal fit of specimens was measured on 18 points, marked on the master metal die by using a digital microscope. After the crowns were finalized by porcelain veneering, the measurements of marginal fit were performed again. The means and standard deviations were calculated and data were analyzed using student’s t-test and paired t-test (α=0.05). There were significant differences between marginal fit of chamfer and shoulder finish line groups before and after porcelain firing (p= 0.014 and p= 0.000, respectively). The marginal gap of copings with shoulder finish line was significantly smaller than those with chamfer configuration (p= 0.000), but there were no significant differences between the two marginal designs, after porcelain firing (p= 0.341). Porcelain veneering was found to have a statistically significant influence on the marginal fit of zirconia CAD/CAM crowns. Both margin configurations showed marginal gaps that were within a reported clinically acceptable range of marginal discrepancy.

Statement of the Problem: The survival of pulpless teeth restored with different post and core systems is still a controversial issue. This study compared the retention of two different post and core systems and also the fracture resistance of teeth restored with these systems. Eighty endodontically treated maxillary central incisors were sectioned perpendicular to the long axis at a point 2mm incisal to the cemento-enamel junction (CEJ) and then the root canals were obturated.The restored teeth were randomly divided into two equal groups of 40. One group was restored with Nickel-Chromium (Ni-Cr) post and core system and the other group with Non-Precious Gold alloy (NPG) system. For evaluation of fracture resistance of the restored teeth, the specimens (n=20 per each group) were mounted in acrylic resin blocks and a layer of polyvinyl siloxane was applied to cover the roots. Loads were applied at an angle of 45 degrees to the long axis of the teeth and measured with a universal testing machine.The axial retention values of the studied groups (no=20) were measured on an Instron testing machine at a crosshead speed of 0.5 mm/min. Statistical analyses were performed using SPSS version 19.00 and student’s t-test (α=0.05). Although retention failure load for Ni-Cr system was lower than NPG system, there was no significant difference between the two systems (p= 0.7). However, fracture resistance of the teeth restored with Ni-Cr post and core system was significantly higher than NPG group (p= 0.000). There was no significant difference between the retention of the studied post and core systems. Although significantly higher fracture thresholds were recorded for Ni-Cr post and core group, the failure loads of both systems may rarely occur clinically.

Statement of the Problem: By introducing the coloring liquids, it is claimed that it is possible to make the color of frameworks fabricated from zirconium oxide extremely close to the natural tooth color. The purpose of this research was to evaluate the effect of two staining techniques on value changing in zirconia crowns. Three groups A, B, and C, each containing ten zirconia crowns, were used. The zirconium cores samples were fabricated by a CAD/CAM device. Group A was left uncolored, Groups B was submerged for two minutes in A2 coloring liquid and Group C was stained with brush. Then all cores were sintered and the porcelain was applied by using the layering technique. Ultimately, the crowns color was determined using a spectrophotometer. Their color changing (∆E) and value changing (∆L) in relation to A2 color were also assessed. The data were analyzed with one-sample t-test, post-hoc Tukey, and one-way ANOVA tests with significant level set at 0.05. The mean value in all groups was higher than the value obtained from A2 color samples (p= 0.001). The highest mean value was 78.31±1.22 belonging to group C (staining with brush) and the lowest mean value was 76.99±0.65 belonging to group B (submerging). The results of post-hoc Tukey regarding both ∆E and ∆L variables showed a significant difference between groups A (uncolored) and C (staining with brush) with P∆E=0.006 and P∆L=0.039, respectively. A significant difference between group B (submerging technique) and C (staining with brush) were shown when these two variables were compared (P∆E=0.001, P∆L=0.015). Due to the higher value increase in surface staining (brush), it is recommended to use the submerging technique for staining zirconia cores.

Actinomycosis is an anaerobic infection that involves the craniofacial region and its colonization has rarely been reported in the developmental odontogenic cysts. In the present report, a case of odontogenic keratocyst (which is now called keratocystic odontogenic tumor) with the colonization of actinomyces is introduced and its significance is discussed.