[Comparison of shear bond strength of composite to primary and permanent enamel using dentin bonding and enamel bonding agents]

Dentin bonding agents are gradually replacing enamel bonding agents in the clinical setting. Considering the different properties of these two materials, their bonding strength to enamel may be different. The aim of this study was to compare the shear bond strength of composite restorations to enamel using dentin bonding and enamel bonding agents. In this experimental study, buccal surfaces of 24 freshly extracted primary and permanent teeth were polished by the polishing papers in order to obtain a piece of flat enamel 3 mm in diameter. After etching, rinsing and drying the surfaces, the specimens were divided into 4 groups. Enamel bonding [Margin Bond] was applied to the surfaces of 6 primary and 6 permanent teeth and Single Bond was applied to the surfaces of the remaining teeth. All teeth were cured. Composite resin [3mm in diameter and 4 mm in height] was applied to the prepared surfaces. Then, the specimens were thermocycled for 2000 cycles and the shear bond strength was determined using an Instron universal testing machine. The findings were analyzed by SPSS and two-way ANOVA. There was no significant difference in the mean shear bond strength of the two groups of primary and permanent teeth [P=0.518]. Also, no significant difference was found between enamel and dentin bonding agents in primary and permanent teeth [P =0.17]. The shear bond strength of composite to enamel was not significantly different between the primary and permanent teeth following the use of enamel or dentin bonding agents

Evaluation of intelligence quotient in children with early first permanent molar eruption

There are many unknown systemic and local factors influencing tooth growth and development. Likely, tooth eruption may be under such influence as well. Despite delayed tooth eruption, studies on early tooth eruption are very scarce. Therefore, this study was conducted in order to evaluate the relationship between intelligence quotient [IQ] and early tooth eruption in normal children [with no disease or disorder]. By using study criteria, 44 children were recruited after oral examination of 652 children [337 boys and 315 girls]. Oral examination was conducted by one dentist using plastic disposable mirror, under day light. The Raven's test was taken blindly under standard conditions for all subjects by a psychologist. [Case] subjects were defined as individuals who had partially or fully erupted molars earlier than the expected normal time. [Control] subjects were similar to [cases] but without erupted molars. Statistical analysis was conducted using student T-test. The intelligence test was performed on 44 subjects consisted of 22 boys [IT'case] and 1 T'control]] and 22 girls [11 [case] and 11 [control]]. IQ in two sexes did not have significant difference [P<0.05]. But the mean IQ difference between [case] and [control] groups was about 11 points that was statically significance [P<0.01]. Healthy children with early first permanent molar eruptions, have higher IQ compared to their peers [P<0.01]. This criterion may be used to identify high IQ children for provision of special care and training for faster advancement of individual and society

No evidence for association between Amelogenesis imperefecta and candidate genes

Amelogenesis imperfecta [AI] is an inherited tooth disorder. Despite the fact that up to now, several gene mutations in MMP20, ENAM, AMELX and KLK4 genes have been reported to be associated with AI, many other genes suggested to be involved. The main objective of this study was to find the mutations in three major candidate genes including MMP20, ENAM and KLK4 responsible for AI from three Iranian families with generalized hypoplastic phenotype in all teeth. All exon/intron boundaries of subjected genes were amplified by polymerase chain reaction and subjected to direct sequencing. One polymorphisms was identified in KLK4 exon 2, in one family a homozygous mutation was found in the third base of codon 22 for serine [TCG>TCT], but not in other families. Although these base substitutions have been occurred in the signaling domain, they do not seem to influence the activity of KLK4 protein. Our results might support the further evidence for genetic heterogeneity; at least, in some AI cases are not caused by a gene in these reported candidate genes

[Prevalence of missing and supernumerary teeth in 3-5 years-old, kindergarten children of Tehran]

Missing and supernumerary teeth are considered as dental developmental anomalies. These anomalies may lead to problems and complications such as dental asymmetry, poor esthetics, midline shift, dental crowding, malocclusions, caries, diastema, ectopic eruption, impactions, delayed eruption, external root resorption as well as loss of adjacent tooth's vitality in some cases. The aim of this study was to investigate the prevalence of missing and supernumerary teeth in 3 to 5 years old kindergarten children of Tehran in 2005. This cross-sectional study was conducted by oral examination of 1000 children. Kindergartens were randomly selected in three major areas of Tehran province, namely Rey, Tehran-city and Shemiranat regions. Oral examination was carried out by counting the teeth under adequate lighting. The prevalence of supernumerary and missing teeth in this study was 0.3% and all the anomalies were observed in boys. All cases of supernumerary teeth were in maxilla. From the three cases with missing teeth, two cases were in the maxilla [83%] and one case in the mandible. The anomalies observed in two samples occurred unilaterally in the lateral incisors [67%].Since missing and supernumerary primary teeth may lead to problems in the permanent dentition, early diagnosis and continuous monitoring of successors seem to be necessary to avoid further problems and therefore complicated treatments

[General dental practitioners and management of traumatic dental injuries in children]

Usually, traumatic dental injuries are considered a bad experience to children. It is important to treat these conditions as soon as possible. The aim of the present study was to evaluate the knowledge of general dentists practicing in Tehran regarding the management of such injuries. This cross sectional survey was carried out in Tehran. A total of 165 general private dentists were included in this study. A questionnaire was used to collect information from the study participants. The SPSS statistical software package [Version 11.5] and Mann-Whitney, Kruskal-Wallis, Independent sample t-test and Pearson correlation coefficient were used for statistical analyses. Knowledge of dentists regarding traumatic injuries to children's teeth was 64% and the amount of their Knowledge had inverse relation with their age and direct relationship with the time of graduation from dental school. Based on the results of this study, general dentists practicing in Tehran have relatively adequate knowledge of dental trauma. However, it is necessary to further expand their knowledge through continuing medical educations

[Assessing DMFT index in 12 years old students attending hearing impaired schools in Tehran]

Extensive studies on the epidemiology of teeth and oral diseases are an important part of health care programs specially for hearing impaired groups. For adequate programming in this field, proper situation analysis is mandatory. The aim of this study was to assess the DMFT [decayed missed filled teeth] of 12 years old students attending hearing impaired schools in Tehran and exploring the relation between sex, hygiene and hearing threshold with the index. This cross sectional descriptive study was based on examining 12 years old [ +/- 6 month] students [117 cases] attending hearing impaired schools in Tehran. A questionnaire was filled for each case. T, Chi-square and Kruskall-Wallis tests were used to analyze the results with p<0.05 as the limit of significance. The mean DMFT in these students was 3.07. Mean DMFT in students with very severe hearing loss was 2.99. Mean ranked DMFT in girls and boys was similar [56.09 in boys and 61.96 in girls]. Mean ranked DMFT in students who didn't use floss [66.40] was higher than those who used floss [46.71]. Mean ranked DMFT in students who seldom brushed, was the highest [72.82] and in students who brushed once a day was the lowest [51.26]. The DMFT index in hearing disabled children was 3.07. Regular brushing and flossing reduced the index

[Comparison of salivary calcium, phosphate and alkaline phosphatase in children with severe, moderate caries and caries free in Tehran's kindergarthens]

The most common dental disease in childhood is dental caries. This study was carried out to recognize the components of saliva which are protective factors in children in order to evaluate and predict caries susceptible and caries resistant individuals. A total of 75 subjects of either sex aged 3-5 years old from kindergartens in Tehran were selected and divided into 3 groups [case group: dmft>6, control group 1: 10.05]. However, the results showed that salivary phosphate and alkaline phosphatase in caries free group and calcium in the group with severe caries was somewhat more than those in other groups. Despite the results of the present study, the relationship between salivary components and caries rate in children remainslcontroversial. So, more and wide studies are necessary to achieve some practical criteria for predicting dental caries, recognition of susceptible persons and finally prevention of caries in children

Effect of high fluoride concentration in drinking water on children's intelligence

Human and animal studies linking fluoride with diminished intelligence have been published. Although adverse effects of high intake of fluoride on intelligence and mental acuity continue to be reported, they are still controversial. The aim of this research was to investigate the relationship between fluoride in drinking water and children's intelligence. In this cross sectional study, 41 children were selected from the high fluoride area with 2.5mg/l [ppm] fluoride in the drinking water and 85 children were selected from low fluoride area with 0.4mg/l [ppm] fluoride in the drinking water. The intelligence quotient [10] of each child was measured by the Raven's test. The history of illnesses affecting the nervous system, head trauma, birth weight [>2.5kg or < 2.5kg], residental history, age and sex of children were investigated by questionnaires completed by the children's parents. Data were analyzed by Chi-Square test with p<0.05 as the limit of significance. In the high fluoride area the mean 10 of children [87.9 +/- 11] was significantly lower than in the low fluoride area [98.9 +/- 12.9] [P=0.025]. Based on the findings of this study, exposure of children to high levels of fluoride may carry the risk of impaired development of intelligence