[Prevalence of Mandibulur Retromolar Canal on Cone Beam Computed Tomography Scans]

Background. and Aim: The retromolar canal is an anatomical structure of the mandible and a type of bifid inferior alveolar canal. The retromolar canal might conduct accessory innervation to the mandibular molars or contain an aberrant buccal nerve; thus, this canal is of clinical significance. The aim of this study was to evaluate the prevaleirce of retromolar canal on cone-beam computed tomography [CBCT] scans.

Materiols and Methods: In this descriptive-analytical study, 151 retromolar canalsin 102 patients [102 unilateral and 49 bilateral] with third molar teethrequiring CBCT were evaluated. The scans were evaluated for presence of the retromolar canal and linear measurements [distance to second molar, height and width] were made. The data were analyzedby independent t-test and chi square test.

Resultsz The prevalence of retromolar canal was 7 .3% [n=11].With regard to linear measurements, the mean distance from the retromolar canal to the second molar was 12.76 +/- 4.3mm. The mean height of the canal was 6.66 +/- 2.18mm, and the'mean width was 1.7 +/- 0.6mm. The presence of retromolar canal was not statistically correlated withsex, side of the jaw or age [P:0.146].

Conclusion: The prevalence of retromolar canal on CBCT scans was 7.3%.

[Comparison of permanent teeth maturation in subjects with vertical and horizontal growth patterns]

Dental age is used for dental maturation description. Knowledge about dental maturation is useful for determination of the plan, time and retention period of orthodontic treatments. The purpose of this research was to compare the dental age in subjects with vertical and horizontal growth patterns. This analytic cross-sectional study was conducted on the panoramic and lateral cephalometric radiographs of 53 patients referred for orthodontic treatment including 26 boys and 27 girls, aged 8-12 years, with a mean chronological age of 9.5 years. The patients were selected according to their lower anterior facial height as a percentage of the total facial height on the cephalometric radiographs. Then the two groups, one with long and the other with short anterior facial height, were compared based on their dental ages. Dental age was determined for each subject on the panoramic view by two observers, using Demirjian's dental maturity score. The data were analyzed by independent and paired T-test, using SPSS. The mean dental age an the mean chronological age in the subjects with long anterior facial height were 9.08 +/- 1.8 and 8.6 +/- 0.87 years, respectively [p =0.06]. The patients with short anterior facial height demonstrated the mean dental age of 10.54 +/- 1.31 years and the mean chronological age of 10.25 +/- 1.09 years [p =0.32]. There was no statistically significant difference in the dental age score between the two extreme groups. Also, there was no statistically significant difference in the dental and chronological age between girls and boys in patients with long and short faces [p =0.71, p= 0.73]. The difference in the dental age between long and short facial types in subjects aged 8-12 years is not clinically relevant. Boys with short anterior facial height demonstrated a tendency toward more advanced dental age [8 months], revealing no significant different; however, it should be considered important in the clinical study

Biosorption of iron from aqueous solution by dried biomass of activated sludge

This study was conducted to investigate the removal of iron by dried biomass of activated sludge. Dried activated sludge, prepared as a powder, was tested as a sorbent for the removal of iron from aqueous solutions. The effects of various experimental parameters including initial iron concentration, mass of biomass and contact time were examined and optimal experimental conditions were obtained. The equilibrium time for iron adsorption onto biomass was determined as 150 min. The rate of iron removal was directly correlated to biomass amount and contact time. Increasing contact time from 0.5h to 2.5h resulted in 25% improvement in iron removal efficiency. When the weight of the biomass increased from 0.1g to 0.9 g, the iron removal efficiency increased from 62% to 95%. High initial iron concentration had an adverse effect on iron removal efficiency. Increasing initial iron concentration from 2 to 10 [mg/L] caused declining the iron removal efficiency from 70% to 56%. Freundlich, Langmuir, Dubinin-Radushkevich and Temkin isotherm models could describe the adsorption equilibrium of the iron onto the activated sludge. Meanwhile, Freundlich isotherm represented a better correlation compared to other isotherms [R2 > 0.999]. Also Elovich kinetic models fits well with experimental data [R2>0.997]

[Removal of excess fluoride from water plants by poly aluminum chloride as a new coagulant]

The fluoride ions are commonly found in water resources. These ions should be in optimum levels for prevention of dental caries. However, the excess value can cause such health problems as fluorosis. The aim of the present study was to investigate the removal of excess fluoride ions by using poly aluminum chloride as a new coagulant that is used in water treatment plants. All experiments were conducted in batch system. Several combinations of parameters such as initial fluoride concentration [1.4, 2 and 2.4 mg/L], pH of solution [3, 7, 9], poly aluminum concentration [10, 20, 30, 40 mg/L], and exposure time [30, 60, 90 minute] were investigated. Various concentrations of poly aluminum chloride solution at different pH levels were added into 200 ml of fluoride solution, and samples were taken in predetermined time intervals and the final concentration of fluoride was determined by spectrophotometer at 570 nm. The results showed that, the highest removal was obtained at pH=7. In addition, it was observed that fluoride removal efficiency was higher in pH=5 than in pH=9. Also the results showed that, removal efficacy can be increased by increasing the poly aluminum chloride and the exposure-time. This study denoted that removal of high levels of fluoride ions can effectively be done by using poly aluminum chloride as a new coagulant. Its use is possible in water treatment facilities without any need for modification in water treatment plans

[Comparison between radioactivity of porcelain powders and artificial teeth with background radiation]

Introduction: A lot of industrial products and consumer resources have important role in human exposure and receiving yearly radiation dose limit. Radioactive products have been used in denture teeth and Porcelain powders for flourescence properties for long time in dentistry. Because of the most of the people used Porcelain powder and denture, this became an emotion to survey the rate of relative reactivity of powders and inform the laboratory personals

Objective: Determine the relative radioactivity of artificial teeth used in dentures and in porcelain powders

Materials and Methods: In this laboratovary-experimental study six samples of porcelain powders [ceramco III opaque, ceramco III dentin, ceramco II opaque, ceramco II dentin, noritake dentin EX3 and noritake incisal]and two samples of anterior and posterior artificial teeth with polymer base[marjan and shanghy]were used and about 3gr of each sample was placed in front of the scintillator detector NaI[ti]s' window. The number of emission in one houre was measured during each stage. Back ground radiation was measured in several stages. Samples and background radiations ratio were measured by means of paired t test. Data were analyzed by SPSS soft ware

Results: Radioactive properties of different porcelain powders and mentioned denture teeth were significantly lower than back ground radiation. Ceramco III opaque porcelain powder showed the most radioactive properties and marjan denture teeth showed the least

Conclusion: This study confirmed previous studies about low rate of radioactivity properties of samples relative to back ground radiation and indicated if safety precautionse are observed no problem should rise for dental technicians

[ association between vitamin D and bone mineral density in postmenopausal women]

There are inconsistent data regarding the role of vitamin-D in determining bone mineral density [BMD] especially in less severe vitamin-D deficiency. The aim of this study was to investigate the possible association between 25[OH]D and BMD in healthy free-living postmenopausal women in a population-based study. We enrolled 245 postmenopausal women, aged between 40 to 80 years, randomly selected from the Tehran Lipid and Glucose Study. Measurements of BMD were taken at the lumbar spine and upper femur by dual X-ray absorptiometry; additional to demographic and anthropometric data, serum 25[OH]D, PTH, calcium, phosphorus and alkaline phosphatase were measured according to the currently used laboratory methods. Bivariate and multivariate analyses were used to explore the association between 25[OH]D, BMD and other clinical and biochemical variables. Mean age and duration of menopause were 58 +/- 7 and 9.4 +/- 6.8 years, respectively; 25[OH]D [29.3 +/- 24.9 ng/ml] was <10 ng/ml and 11-20 ng/ml in 5.2% [n=13] and 37.6% [n=92] of women, respectively; 25[OH]D correlated inversely with LnPTH [r=-0.25, p<0.01]. However no association was found between 25[OH]D level and BMD at any of the skeletal scanning sites in bivariate analysis or multiple linear regression analyses, after adjusting for age, years since menopause, body mass index [BMI], calcium and LnPTH. In the multivariate analyses, BMD correlated inversely with LnPTH, in addition to age and BMI [R2=20%, p=0.03] only in femoral neck, but not at any other sites. This study showed no association between 25[OH]D and BMD in postmenopausal women

[Determination of sexual dimorphism from maxillary premolars thickness in bitewing radiography]

Sexual dimorphism plays an important role in forensic medicine. Sexual differences in the human skeleton have been well studied in many populations but odontometric analysis of the human sexual variation has been less investigated. This study was designed to determine the sexual dimorphism by enamel and dentin thickness in radiography of maxillary premolars in an Iranian sample.For this descriptive and analytic study, 100 individuals, [so males and so females] aged 20 to 35 years old, from an Iranian population were selected. The bitewing radiographs of the right permanent maxillary premolars were taken under standard conditions using a film holder. The radiographs were digitally scanned, and after calculation of image magnification, maximum mesiodistal diameter of dentin, and mesial and distal enamel margins were measured. Data were analysed by SPSS statistical software using T- test and Step function. Mesiodistal dentin dimension was significantly greater in males, but there was no sexual dimorphism in the maximum mesiodistal diameter of crown, and distal margin of enamel. Enamel was significantly thicker on the mesial margin in females. First premolar displayed greater sexual dimorphism than second premolar. According to the study results, for determining sexual dimorphism in forensic medicin, the mesiodistal dentin dimension as well as the width of the enamel mesial margin of upper premolar teeth are acceptable parameters in Iranian population