SUMMARYSelf-etching adhesive systems are a new generation of materials that possess acidic methacrylates that can generate self-adhesion. There is limited data reported on the marginal leakage of ceramic restorations bonded with self-etching adhesive materials. This study assessed and compared the amount of microleakage of bonded ceramic crowns using three different types of self-etching adhesive systems with and without a die spacer.Eighteen human molars were prepared for allceramic IPS Empress crowns and the teeth were randomly assigned to each experimental group. The buccal side had the preparation finish line 1.5 mm below the CEJ, and the lingual finish line was 1.5 mm above the CEJ, creating margins in enamel and dentin. Two die-spacing techniques were used (three layers or no layer of die spacer). Each crown restoration was cemented with one of three self-etching resin luting agents (Panavia F 2.0, Multilink and RelyX Unicem). The specimens were thermally cycled for 1000 cycles, then immersed in a 5% methylene blue dye solution for 24 hours. The teeth were then rinsed, embedded in clear epoxy resin and sectioned. A total of 60 sections were evaluated for each type of resin luting agent using digital image analysis at 70x magnification. A novel formula, using mean percentage of microleakage, was developed by dividing the extent of dye penetration along the tooth/resin luting cement interphase and the total perimeter of the tooth crown surface. The data were analyzed using three-way analysis of variance at the 0.05 level of significance. Fisher's PLSD intervals were calculated for comparing significant means. Panavia F 2.0 showed a lower degree of microleakage than RelyX Unicem and Multilink Clinical RelevanceAmong the self-adhesive resin cements, Panavia F 2.0 demonstrated less microleakage than RelyX Unicem or Multilink, whether or not a die spacer technique was used.at both the enamel and dentin margins. Interactions of the main effects (cement, margin and die spacer technique) were all highly significant (p≤0.004). The degree of microleakage was higher on the dentin margins than on the enamel margins (p<0.0001). The degree of microleakage for the die spacer group was not significantly different from the group with no die spacer technique (p>0.1).Overall, Panavia F 2.0 showed the least microleakage, followed by RelyX Unicem and Multilink, respectively.

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Background: This clinical study evaluated the effects of salivary flow rate, age, race, health status and medications on the incidence of caries. Methods:Cauca-sian and African-American men and women (n = 501), aged 22-93 years participated in the study. Stimulated (S) and unstimulated (U) parotid (P) and submandibular glands (SM) salivary secretions were collected. Stimulated whole saliva (SWS) was collected as control. Glandular stimulation was achieved using 2% citric acid at 30-second intervals to the dorsal surface of the tongue. Salivary flow rates (SFR) were calculated by total weight of saliva divided by 5 minutes and expressed in ml/minute. Coronal caries were scored using the NIDR DMFS index. Carious lesions were classified according to tooth surfaces by a calibrated single examiner. Spearman correlation coefficients were calculated to determine the association between SFR with age and percentage of carious teeth. Multiple regression analyses were calculated at (p < 0.05). Results: The variables gender, race, age, health status, medication usage and salivary function were not predictors for dental disease. Additionally, these risk factors were not risk factors for missing teeth. Conclusions: In conclusion, cross-sectional investigations are limited in their ability to identify the relevant variables for disease prediction. In addition, clinical and basic science investigations will be necessary to assess risk factors for dental caries.

173 Background: There is currently no simple test to identify patients with pancreatic ductal adenocarcinoma (PDAC). The goal of this research is to develop such a method. We hypothesized that the salivary proteome of patients with localized PDAC contains a protein set distinct from normal subjects. Methods: We collected, processed and stored stimulated whole salivary gland secretions from patients with Stage I-II PDAC and aged-matched healthy volunteers. Fluorescently-labeled proteins were separated using 2D DIGE. Overlay imaging techniques compared 2D DIGE results, and spots representing individual proteins were quantified by signal, isolated from the gels, processed and protein identified using MALDI-TOF Mass Spectrometry. The SWISS-PROT database was used to identify proteins, and the ratio of signal in cancer versus normal samples was quantified and compared using Student’s t-test. Results: Samples from 10 PDAC patients and 10 healthy subjects were compared. A total of 96 spots on the 2D-DIGE comparison were uniquely present or absent in PDAC patient saliva. MALDI-TOF Mass Spectrometry examination of these 96 characterized 53 unique proteins. After eliminating duplicates and proteins without significant differences (p-value <0.02), a total of 30 proteins were identified with levels higher (n=18) or lower (n=12) in saliva from PDAC patients versus normal subjects. Conclusions: Examination of saliva from pancreatic cancer patients identified a set of proteins unique from normal subjects. These proteins represent targets for the development of biomarkers that could be used in early detection of pancreatic cancer.