In astronauts and cosmonauts, exposure to microgravity has been associated with several physiological changes, including an osteoporosislike loss of bone mass. It has been reported that head-down tilt bed-rest studies mimic many of the observations seen in space flights. There has been no study of the effects of mandibular bone and alveolar bone loss in both sexes under conditions of simulated microgravity. This study was designed to investigate bone mineral density; bone mineral content; matrix metalloproteinase (MMP)-8, MMP-9, cathepsin K, and osteocalcin levels in gingival crevicular fluid (GCF); and salivary and serum osteocalcin levels in normal healthy men and women under conditions of simulated microgravity, namely, -6° head-down-tilt (HDT) bed rest. The subjects of this investigation were 10 male and 10 female volunteers who were exposed to 3 weeks of -6° HDT bed rest. Dual-energy X-ray absorptiometry was used to measure bone density and bone mineral content in alveolar bone from the mandibular canine to the third molar, as well as in the mandibular ramus, before, during, and after exposure to conditions of simulated microgravity. GCF (ie, MMP-8, MMP-9, cathepsin K, and osteocalcin) and salivary and serum osteocalcin levels were measured by enzyme-linked immunosorbent assays. Bone mineral density and bone mineral content were significantly lower under conditions of simulated microgravity in both sexes. The decreases were greater in women than in men, but the differences between sexes were not significant. Cathepsin, osteocalcin, MMP-8, and MMP-9 levels were significantly higher under conditions of simulated microgravity than under normal conditions; the increases were greater in women than in men, but the differences were not significant. Additional, more comprehensive, studies with larger sample sizes are now necessary for the investigation of simulated microgravity and microgravity. (J Oral Sci 52, 385-390, 2010)

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Oral and maxillofacial pathology has paramount importance in connecting basic science and clinical features; progress in this field will improve diagnosis and treatment. Although the prevalence of odontogenic tumors varies in different geographic sites, there are no reports in English on the relative frequency of odontogenic tumors in Iran. In the present 30-year retrospective study, the case records of all patients referred to the Mashhad Faculty of Dentistry during the period 1978-2008 were evaluated. Subsequently, all lesions diagnosed as odontogenic tumors were subjected to microscopic reevaluation. Data regarding sex, gender, location, and histopathology were gathered. Among 8,766 patients, only 165 odontogenic tumors (1.9%) were found, with a mean age of 26.3 years (range 6-81 years). One hundred and fifty-eight tumors were central with high frequency in the posterior region of both jaws especially in the mandible and seven were peripheral tumors, including five in the posterior mandible and two in anterior maxilla. Malignant transformation was seen in three cases as malignant ameloblastoma (1.8%). The most common tumor was ameloblastoma, followed by odontoma, odontogenic myxoma, and adenomatoid odontogenic tumor. Nevertheless, odontogenic tumors occurred more in females in the third decade with affinity for the posterior mandible in this study. (J Oral Sci 52, 391-396, 2010)

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Dental caries is the most common chronic childhood disease. Deep caries and dental trauma are the two main etiologic factors responsible for pulp involvement. Better knowledge of the morphology of the root canals of deciduous teeth can improve the outcome of pulp treatment. In this study, 90 deciduous molar teeth (27 first mandibular molars, 27 first maxillary molars, 22 second mandibular molars and 14 second maxillary molars) were prepared using the clearing technique, and then dye was injected into the pulp cavity of each tooth. The roots of the teeth were examined under a stereomicroscope at × 10 magnification from different aspects. Measurements of root length and angulation were also recorded, and the data were analyzed using SPSS-16 software. Deciduous molar teeth in all four classes showed variability in the number of roots and root canals, and also differed in mean root length and angulation. Type I and IV root canal configurations were observed in the samples, and different types of curvature were recorded for the root canals in all four classes. As deciduous molar teeth exhibit morphologic differences from permanent teeth, a thorough knowledge of the root canals in the former can improve the outcome of pulp treatment. (J Oral Sci 52, 397-403, 2010)

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This study aimed to evaluate the effect of adhesive systems based on a thiouracil monomer on bonding to silver-palladium-copper-gold (Ag-Pd-Cu-Au) alloy (Castwell M.C.12). Disk specimens were cast from the alloy and then air-abraded with alumina. The disks were bonded using six bonding systems selected from four primers and three luting materials. Shear bond strengths were determined both before and after thermocycling. Bond strength varied from 2.7 MPa to 32.0 MPa. Three systems based on a thiouracil monomer (MTU-6) showed durable bonding to the alloy, with post-thermocycling bond strengths of 22.4 MPa for the Metaltite (MTU-6) primer and Super-Bond, a tri-n-butylborane (TBB) initiated resin, 9.0 MPa for the Multi-Bond II resin, and 8.1 MPa for the Metaltite and Bistite II system. It can be concluded that a combination of thiouracil-based primer and TBB initiated resin is effective for bonding Ag-Pd-Cu-Au alloy. (J Oral Sci 52, 405-410, 2010)

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This study evaluated the effectiveness of ultrasound, color Doppler imaging and conventional radiography in monitoring the post-surgical healing of periapical lesions of endodontic origin. Fifteen patients who underwent periapical surgery for endodontic pathology were randomly selected. In all patients, periapical lesions were evaluated preoperatively using ultrasound, color Doppler imaging and conventional radiography, to analyze characteristics such as size, shape and dimensions. On radiographic evaluation, dimensions were measured in the superoinferior and mesiodistal direction using image-analysis software. Ultrasound evaluation was used to measure the changes in shape and dimensions on the anteroposterior, superoinferior, and mesiodistal planes. Color Doppler imaging was used to detect the blood-flow velocity. Postoperative healing was monitored in all patients at 1 week and 6 months by using ultrasound and color Doppler imaging, together with conventional radiography. The findings were then analyzed to evaluate the effectiveness of the 3 imaging techniques. At 6 months, ultrasound and color Doppler imaging were significantly better than conventional radiography in detecting changes in the healing of hard tissue at the surgical site (P < 0.004). This study demonstrates that ultrasound and color Doppler imaging have the potential to supplement conventional radiography in monitoring the post-surgical healing of periapical lesions of endodontic origin. (J Oral Sci 52, 411-416, 2010)

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Cell proliferation markers play an important role in the biological behavior of neoplasms. This study investigated the immunohistochemical expression of PCNA, Ki-67 and Cyclin B1 proteins based on the pattern of cell invasion in oral squamous cell carcinoma (OSCC). A total of 39 OSCC specimens and 13 samples of normal oral mucosa (control) were immunohistochemically analyzed. Protein expression was evaluated according to World Health Organization – Histological Malignancy Grading (WHO-HMG) and a specific grading system for invasion, graded from 1 to 4, varying from a consistently well-defined “pushing” border to diffuse infiltration and cellular dissociation, and was then correlated with clinical features. We found higher expression of Ki-67 and Cyclin B1 in OSCC when compared with the control group. High Ki-67 expression levels were more commonly seen in the floor of the mouth than in the tongue (P = 0.009). Cyclin B1 showed a positive correlation with histological grade, according to WHO-HMG criteria (P = 0.01). Our results suggest that Cyclin B1 is a reliable proliferation marker for indicating degree of tumor proliferation. Correlations between PCNA, Ki-67, Cyclin B1 and invasive tumor front with overall survival were not observed. Further studies are needed in order to elucidate whether cell proliferation activity at the tumor invasion front is related to prognosis. (J Oral Sci 52, 417-424, 2010)

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The present study evaluated the durability of bond strength between zirconia and 3 different resin cements. Thirty stabilized tetragonal zirconium-dioxide blocks were duplicated in dual-curing resin core build-up material specimens. Resin blocks were randomly luted to zirconium surfaces using 1) Clearfil Esthetic Cement (CLF), 2) RelyX Unicem Aplicap (RELX), or 3) Multilink Automix (MLA). After 24 h, half of the specimens from each of the 3 groups were loaded in tension until fracture (0.5 mm/min). The remaining half were tested after 6,000 thermal cycles (5 to 55°C). Data were analyzed using 2-way ANOVA and the Tukey test (α = 0.05). Fractographic analysis was performed using a stereomicroscope. Tensile bond strength values were significantly affected by the luting agent system employed and by thermal aging (P < 0.001). The highest tensile bond strength values in non-thermal-aged groups were observed for specimens from the RELX and CLF groups. In contrast, in the thermal-aged groups, the highest tensile bond strength values were for the MLA and RELX groups. Moreover, while thermocycling significantly affected bond strengths in the RELX and CLF groups, the mean strength of the MLA group did not significantly change after aging. There was little difference in the distribution of failure modes in any group. (J Oral Sci 52, 425-430, 2010)

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Recent studies have focused on genetic polymorphism of the interleukin-6 (IL-6) gene, which has led to a better understanding of the intricate interactions between host response, microorganisms, and genetics. Genotype prevalence appears to vary by the race and ethnicity of the population studied. We used a polymerase chain reaction technique to determine the prevalence of single nucleotide polymorphism in IL-6 at position -174 G>C in a population of 30 South Indians. Blood samples were collected from 15 chronic periodontitis patients and 15 healthy controls. The results showed that the G/G genotype was significantly more frequent in the chronic periodontitis group and that the C/C genotype was significantly more frequent in the control group (P = 0.0069 for both). The G allele was more frequent in chronic periodontitis patients (76.67%), whereas the C allele was more frequent in the control group (73.33%). Among chronic periodontitis patients, the odds ratio for having the G allele, as compared with the controls, was 9.04. In this population, the presence of the G/G genotype of IL-6 (-174) might increase susceptibility to chronic periodontitis, whereas the C/C genotype may have a protective effect. (J Oral Sci 52, 431-437, 2010)

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Odontomas represent the most common type of odontogenic jaw tumors among patients younger than 20 years of age. Clinically, they are often associated with eruption failure of adjacent permanent teeth, and are classified as compound and complex. The aim of the present retrospective study was to present the characteristics, treatment approach and outcome of odontomas in Greek children, over a ten-year period. Twenty six patients, 2 to 14 years of age (mean 9.3 years), with odontomas treated during the years 1999-2008 at the Department of Oral & Maxillofacial Surgery of a Children's Hospital, were included in the study. Data from patients' files were retrieved and they were recalled for review. Odontomas were equally distributed in the maxilla and mandible and 42.3% of them were located in the anterior maxilla. Of the odontomas, 80.7% were related to disturbances in tooth eruption. Bone expansion was observed in 65.3% of the cases. All odontomas were surgically removed, and related impacted permanent teeth were either left to erupt spontaneously, orthodontically guided into occlusion or were removed. Orthodontic intervention appeared to be necessary in older children, while in younger children spontaneous eruption was frequent. In the present study, odontomas were associated with unerupted or impacted teeth. Radiographic examination was essential to verify the presence of the tumor and early removal prevented tooth eruption failure and disturbances in a majority of the cases. (J Oral Sci 52, 439-447, 2010)

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Increasing evidence indicates that systemic conditions are risk factors of periodontitis. Pemphigus is a group of bullous diseases affecting the oral cavity. The aim of this study was to assess the periodontal status of pemphigus vulgaris (PV) patients. The periodontal status of 50 PV patients and 50 healthy subjects was assessed by a single examiner. PV patients were assessed based on the Clinical Severity Score (CSS). Periodontal clinical parameters such as plaque score, full mouth gingival bleeding score, probing depth (PD), clinical attachment level (CAL) and radiological bone loss were recorded. Effects of age, gender, daily tooth brushing habit, oral lesions and treatment duration on the periodontal status of PV patients were also determined. A statistically significant difference was found between the PV group and the healthy group with respect to the plaque score, PD and CAL (P < 0.05). Logistic regression analysis confirmed that age, gender, and treatment did not significantly influence clinical severity of the disease (P > 0.05). Increased PD and CAL were found with an increase in the CSS. The poor periodontal status in PV patients suggests that PV may be involved in the initiation or progression of periodontitis. (J Oral Sci 52, 449-454, 2010)

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To investigate the prevalence, characteristics (ie, malocclusion, location, type), and sex distribution of hypodontia in an Iranian orthodontic population. A retrospective study was conducted using periapical and panoramic radiographs and study models of 1,751 subjects attending university orthodontic clinics (870 females, 881 males, age 9-27 years). The Chi-square test was used to analyze differences in the distribution of hypodontia, after stratification by sex and malocclusion type. A total of 197 congenitally missing teeth were observed in 160 patients (9.1%; 74 boys and 86 girls); there were no statistically significant differences between sexes (Chi-square = 0.832, P = 0.36). Hypodontia was more common in patients with Class III malocclusion (45.2%), and was more prevalent in the maxilla (71%) than in the mandible (29%). Maxillary lateral incisors (35.6%) and maxillary second premolars (13.0%) were the most commonly missing teeth, followed by mandibular lateral incisors (9.6%) and mandibular second premolars (8.2%). The prevalence of missing teeth was higher in the anterior segment (incisors and canines) than in the posterior segment (premolars and molars). The prevalence of oligodontia was 0.34%. The prevalence and characteristics of the most frequently missing teeth accorded with the findings of most studies conducted in other countries. (J Oral Sci 52, 455-461, 2010)

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The primary aim of this randomized clinical investigation was to evaluate gingival recession defects treated by a coronally advanced flap and sub-epithelial connective tissue graft (SCTG) with or without enamel matrix derivative (EMD). Twelve patients with Miller's class III buccal recession defects of ≥2.0 mm in similar contra lateral sites were included in this split-mouth randomized study. Test sites were treated with SCTG plus EMD while control sites received SCTG only. At baseline, 6 months and 12 months, clinical parameters such as recession level (RL), probing depth (PD), clinical attachment level (CAL), and apico-cervical width of keratinized tissue (KT) were determined. A P value <0.05 was considered significant. Compared to the baseline and based on paired t tests, both groups had significant improvement in all the clinical parameters. However, the test group showed better results in RL (P = 0.046) and CAL (P = 0.023) at 6 months. At 12 months, the test group demonstrated better results in RL (P = 0.01), PD (P = 0.017) and CAL (P = 0.001). Only the KT results were not significantly different between groups at both 6 and 12 months (P = 0.708) and (P = 0.570), respectively. The present study demonstrated the benefit of adding EMD to SCTG for root coverage in Miller's class III buccal gingival recession defects after 12 months. (J Oral Sci 52, 463-471, 2010)

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The aim of this study was to evaluate the antimicrobial activity of Uncaria tomentosa (Willd.) DC (cat's claw) against Enterococcus faecalis, Staphylococcus aureus, and Candida albicans. Suspensions with 10⁸ cells/ml of each microorganism were plated in triplicate on Mueller-Hinton agar. Wells in the agar were made and filled with 2% chlorhexidine (CHX) gel, 2% cat's claw (CC) gel, 2% CHX+CC, and 1% hydroxyethylcellulose (NAT) gel. Inhibition halos were measured after 24 h at 37°C and differences were analyzed using one-way ANOVA. The mean diameter of the microbial growth inhibition zones of 2% CHX+CC against the tested microbial strains ranged from 21.7 to 33.5 mm. This was the most effective substance against E. faecalis and C. albicans, followed by CHX and CC. Against S. aureus, CHX+CC, CHX, and CC showed similar antimicrobial activity (P > 0.05). The results indicate that all the investigated compounds had antimicrobial activity against microorganisms frequently found in infected root-filled teeth. (J Oral Sci 52, 473-476, 2010)

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Oral geotrichosis is an uncommon opportunistic infection caused by Geotrichum candidum, a habitual contaminant and component of the flora of various parts of the body. This communication reports both a 20-year retrospective study of clinically and mycologically proven cases of oral geotrichosis, and a prospective study of fungal oral flora in 200 individuals divided into two groups: normal individuals and individuals with associated conditions. Twelve patients with proven oral geotrichosis were included: 9 females and 3 males, with a mean age of 48.5 years; the associated conditions were diabetes mellitus (66.6%), leukemia, Hodgkin's lymphoma and HIV/AIDS infection. The oral geotrichoses showed three clinical varieties: pseudomembranous (75%), hyperplastic, and palatine ulcer. G. candidum was isolated in 11 cases and G. capitatum in one. Positive fungal cultures were obtained from the two groups, and 48% and 78% of cultures were positive, respectively, for Candida spp. In 2.8% and 6.33% of the cases, G. candidum was isolated, respectively, together with one strain of G. capitatum. Oral geotrichosis is an exceptional infection that clinically presents, and is treated, as oral candidiasis. G. candidum may be isolated from the oral flora of a small proportion of patients, either normal individuals or those with associated conditions. (J Oral Sci 52, 477-483, 2010)

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