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Dental caries is the most common childhood disease worldwide.Between 60 and 90% of children are affected, but the majority of dental decay remain untreated [1]. Childhood dental caries has been reported to be the most prevalent infectious disease in our nation. It is 5 times more common than asthma and 7 times more common than hay fever among 5 to 17 year old American children [2]. In 1996, oral disease resulted in 1.6 million days of school lost; an average of 3.1 day per 100 students in the United States [3]. In 2009 -2010, the prevalence of untreated decay and decay Background experience among 6 -8 year old children examined by National Health and Nutrition Examination Survey (NHANES) throughout the United States was 17% and 45% respectively [4]. Data from National Health and Nutrition Examination survey for 2011 -2012 reported that approximately 37% of children aged 2 -8 years in the US had experienced dental caries, and 14% of the same age group had untreated tooth decay in primary teeth. While 21% of children aged 6 -11 had experienced dental caries in permanent teeth and 6% had untreated decay in permanent teeth [5].Background: Significant Caries Index (SCI) was proposed by WHO to draw attention to those individuals with the highest caries score in each population. The aim of the study was to evaluate the prevalence of dental caries and untreated caries, using combined decay, filling for primary teeth (dft) and permanent teeth (DFT) and SCI indices.Methods: 144 School children aged 4-13 years old were examined in a mobile dental clinic as part of the school-based dental services program. Combined dft/DFT and Significant Caries Index were used to evaluate dental caries prevalence. Dental caries were recorded when cavitation was observed clinically or radiographically. The services provided to children included comprehensive diagnostic, preventive and restorative treatment. Results:The mean combined dft/DFT for all groups was 3.18. As the age increased, the mean decreased with no significant differences. The SCI for all age groups was significantly higher than combined dft/DFT. The caries prevalence for this school was 63. 9%. About 77% of children had untreated caries. Conclusion:The study reported high prevalence of caries experience and untreated caries. The SCI is designed to focus attention to high caries risk group; it is useful indicator and helps in targeting the preventive program for this group. IRB # 1819-49.

Technical limitations are associated with conducting successful in situ hybridization. In this study, three cell types including a tumor neuroblastoma cell line (Neuro-2a), an oligodendrocyte primary culture, and a nonneuronal acute lymphoblastic leukemia cell line (Reh) were used to conduct successful nonradioactive in situ hybridization. Two cDNA probes were used. A 1 kb probe was used to identify the expression of proteolipid protein (PLP) mRNA in a primary culture of oligodendrocytes. A 760 bp cDNA was used to identify the expression of ubiquitin C-terminal hydrolase (UCH-L1) mRNA in Neuro-2a and Reh cells. The probes were labeled with digoxigenin-11-dUTP, denatured, and hybridized with cells fixed on coverslips. The efficiency of the labeling was tested using dot blot analysis by comparing the intensity of our labeled probes with known concentration of the probe labeled by the provider. The nonspecific signals were washed off, followed by detection of a signal specific to the gene. The specificity of the probes was determined by treating the cells with RNase A, hybridizing with bacterial Dig-labeled cDNA (pBR322) and hybridizing the tissues in the absence of labeled probe. During the labeling step, we found that addition of co-precipitants, such as tRNA or glycogen, during precipitation of the labeled probe followed by overnight incubation at -20 C is essential for good recovery of labeled cDNA. Dissolving the labeled probe in a buffer solution containing sodium dodecyl sulfate improves the quantity of the labeling. At the cellular level, prehybridization treatments optimize the permeability of the cell and allow efficient penetration of the labeled probe. Fixing with paraformaldehyde or an ethanol-acetic acid mixture can preserve the structure of cultured cells. To increase the signal to noise ratio, cells were treated with 0.2 N HCl followed by extensive washes using a solution with a high salt concentration and containing dextran sulfate. This treatment significantly improves the signal and reduces the background in cell cultures, but not in tissue sections. The ability to reuse the labeled probe-hybridization mixture is another advantage for using nonradioactive in situ hybridization.

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