The findings indicate that delmopinol interacts with the salivary film of the upper labial mucosa and affects its polarity. It appears that delmopinol assists in the maintenance of the hydrophilicity of the mucosal pellicle and thereby also reinforcing hydration of the mucosa. The rat autoradiograms, showed that radioactivity remains in the oral mucosa after 24 h, but diffuses through the mucosal membranes into the systemic circulation.

Purpose: A pilot study was conducted to determine the 2-year clinical performance of a new bioactive dental cement (Ceramir C&B, formerly XeraCem) for permanent cementation. Materials and Methods: The cement used in this study is a new formulation class, a hybrid material comprising calcium aluminate and glass ionomer. Thirty-eight crowns and fixed partial denture (FPD) abutments were cemented in 17 patients. Thirty-one of the abutment teeth were vital, 7 nonvital. Six reconstructions were FPDs comprising 14 abutment teeth (12 vital/2 nonvital). A two-unit fixed splint was also included. Preparation parameters and cement characteristics (dispensing, working time, seating characteristics, ease of cement removal) were recorded. Baseline and postcementation data were recorded for marginal integrity, marginal discoloration, secondary caries, retention, and gingival inflammation. Tooth sensitivity was assessed at pre- and postcementation time points using categorical and visual analogue scale (VAS) assessment measures. Results: Mixing of the cement was reported as “easy.” Clinical working time for this cement was deemed acceptable. Assessment of seating characteristics indicated all restorations were seated completely after cementation. Cement removal was determined to be “easy.” Fifteen of 17 subjects were available for 1-year recall examination; 13 patients were available for the 2-year recall examination. Restorations at 2-year recall examination included 17 single-unit, full-coverage crown restorations, four 3-unit FPDs comprising 8 abutments, and one 2-unit splint. No retentive failures or sensitivity were recorded at 2-year recall. Marginal integrities of all restorations/abutments at 2 years were rated in the “alpha” category. Average VAS score for tooth sensitivity decreased from 7.63 mm at baseline to 0.44 mm at 6-month recall, 0.20 mm at 1-year recall, and 0.00 mm at 2-year recall. The average gingival index score for gingival inflammation decreased from 0.56 at baseline to 0.11 at 6-month recall, then 0.16 at 1-year recall, and 0.21 at 2-year recall. Conclusions: Two-year recall data yielded no loss of retention, no secondary caries, no marginal discolorations, and no subjective sensitivity. All restorations rated “alpha” for marginal integrity at the 2-year recall. After periodic recalls up to 2 years, the new bioactive cement tested thus far has performed favorably as a luting agent for permanent cementation.

The purpose of the present study was to characterise the structure dynamics of pure salivary secretions retained on controlled surfaces with different surface energies in the early stage of salivary film formation. Germanium prisms prepared to have either low surface energy of medium surface energy were incubated in fresh secretions of either human parotid saliva (HPS) or human submandibular/sublingual saliva (HSMSLS) for 15,90 and 180 min. After controlled rinsing with distilled water, the surfaces were air dried and thereafter imaged with atomic force microscopy (AFM). The amount of adsorbed material and the size of the structures detected increased with increased saliva exposure time. the film thicknesses varied from 10 to 160 nm, and both HPS and HSMSLS films contained structures with diameters varying from 40 nm to 2 microm. Some of these were clustered into special formations. The HPS films exhibited a more granular morphology than the HSMSLS films. Furthermore, branched lines were detected on the low surface energy germanium prisms incubated in saliva. the results indicate that exposure time, surface energy, and type of salivary secretion all are factors affecting the adsorption characteristics of salivary films.

OBJECTIVES: The clinical usefulness, accuracy and precision of a novel bite force sensor based on force sensing resistors were tested in six subjects wearing maxillary removable partial dentures retained by conical crowns. METHODS: The surfaces of the sensor were manufactured in a silicone material that had mechanical properties similar to those of tough foodstuffs. In two separate series of standardized bite force tests, submaximum force levels were recorded with the sensor and with a strain gaged bite fork. Subjects were assisted in the loading tests with visual feedback instrumentation. Reliability estimates for the bite force sensor were calculated in order to show their reproducibility. Strain gages attached to the prostheses were used to determine the pattern of force distribution during loading tests. The bite force results obtained with the new bite force sensor and with the bite fork were analyzed with ANOVA and Scheffes tests. The strain patterns registered with strain gages were analyzed with F-test. RE-SULTS: The bite force sensor and the bite fork transducer showed no statistically significant differences in respect of intra-individual bite force levels (range 50-300N). The bite forces registered with the new sensor were dependent on the loading position (p<0.05), sex (p<0.05) and test subject (p<0.05). The reliability of the new sensor for sub-maximum bite forces was calculated to be 93%. Strain gage results showed that the new sensor generated strain patterns of less variance (p<0.05) than the bite fork and therefore allowed for higher precision during biting tests. SIGNIFICANCE: The presented instrument has such clinical merits, as to favor its use in experimental clinical studies on the biomechanics of prosthetic appliances.

OBJECTIVES: Comparative in vitro/in vivo studies show wide differences in functional strain magnitudes and patterns of functional strain distribution in prosthetic devices. The aim of this study was to evaluate the accuracy of three in vitro models for biomechanical studies of prosthetic devices. METHODS: Strain gages were attached to the test RPDs of six subjects. In vitro maxillary models with simple (model A), intermediate (model B) and advanced (model C) features for the anatomical simulation of supporting structures were manufactured for each subject. The dentures were subjected to two separate series of standardized functional and laboratorial loading tests. The principal maximum strain value (epsilon (1)) obtained for each gage and experiment was used to calculate the intra-experiment variance and inter-experiment variance for the in vivo and in vitro experiments. The integrated strain gage difference value between the in vitro and in vivo data (Sigma(diff)) was calculated for every loading test and compared to the in vivo inter-experiment variance with ANOVA and Scheffes test. RESULTS: The bite forces recorded were similar for each subject and loading position and between the two loading sessions. The inter- and intra-experiment variance was found to be higher for in vivo loadings than for in vitro. Results showed that the (Sigma(diff)) values for model B and model C were significantly different from the in vivo strain interexperiment variance (p<0.05). SIGNIFICANCE: This study showed that the anatomical simulation of in vitro models is insufficient to allow for accurate mechanical analyses of maxillary RPDs and that only simple verifications of the strain levels in prosthetic appliances can be attained in vitro.

OBJECTIVES: This research was conducted to demonstrate the effectiveness of reflective photoelasticity as an in vivo technique for monitoring the strain/stress distribution in prosthetic devices during function. METHODS: Seven subjects were selected for this study and divided into three groups according to the design of the prostheses. The buccal surfaces of the experimental prostheses were coated with a bi-refringent resin 2mm thick. Using a reflection polariscope, fringe patterns were documented on video tape during standardized in vivo loadings. Strain and stress levels (gamma(max) and tau(max)) were calculated from isochromatic fringe order determinations. The intra-observer variability in counting fringe orders and the accuracy level of reflective photoelasticity as compared to strain gauge results were also studied. The strain results of in vivo loading of the prostheses were analyzed with ANOVA and Scheffes tests. The intra-observer variability was analyzed with the Friedman nonparametric test. Comparisons of photoelastic data and strain gauges were tested with Pearson's correlation. RESULTS: Coated areas accessible to normally incident light, produced comprehensive maps of strain distribution. Significant differences were found in the in vivo gamma(max) values for the prostheses designs (p<0.05). The test for intra-observer variability showed that no significant differences occurred in counting fringe orders. Strain values obtained with reflective photoelasticity showed a high correlation r=0.98 and 0.99) with values obtained at the same areas using strain gauges. SIGNIFICANCE: Reflective photoelasticity is a valid, reliable and accurate technique to be used for in vivo studies on the biomechanical behavior of prosthetic devices.

Objectives: The aims of the present study were to investigate the adsorption from human whole saliva to solid surfaces in terms of dependence of adsorption time and surface wettability, to investigate pellicle elutability with buffer and sodium dodecyl sulphate (SDS) and finally to identify major components involved. Methods: Time resolved in situ ellipsometry was used to determine the adsorbed amounts and adsorption rates from human whole saliva onto pure (hydrophilic) and methylated (hydrophobized) silica surfaces. Two-dimensional gel electrophoresis was used to identify salivary components in the secretions as well as major components in pellicles. Results: The results demonstrated that on hydrophobic surfaces the initial adsorption was rapid and a plateau was reached, whereas on hydrophilic ones a continuous increase was observed during the time course of experiments. Contrary to what was expected, it was found that buffer rinsing removed less material after short adsorption times on hydrophobic surfaces, whereas less time dependence was observed on hydrophilic ones. After SDS exposure a minor fraction remained adsorbed after 15 minutes of adsorption, while a complete removal of the adsorbed film was observed after 2 hours of adsorption on hydrophobic surfaces. On hydrophilic surfaces a minor fraction remained adsorbed after both 15 minutes and 2 hours of adsorption. The two-dimensional gel electrophoresis revealed the presence of more than 50 proteins, with a molecular mass below 200 kDa present in whole saliva. Of these proteins only a few components were detected in the fraction eluted by SDS. Conclusions: We conclude that the different desorbability upon buffer rinsing and addition of SDS indicate that adsorbed proteins have varying binding strengths to the two types of surfaces. The time dependence observed and the compositional analysis show that the adsorbed pellicle undergoes conformational and/or compositional changes.

Salivary mucins are known to play important roles in the formation of oral salivary films. The aims of the present study were to investigate the behaviour of salivary mucins at solid surfaces with different wettabilities, as well as the influence of electrolyte on the adsorption behaviour. A pure preparation of human salivary MUC5B was used together with a commercial one of bovine submaxillary mucin (BSM). Amounts adsorbed from freshly prepared solutions onto hydrophilic and hydrophobic surfaces versus time were measured in situ by ellipsometry. At low concentrations, larger amounts were adsorbed onto hydrophobic than onto hydrophilic silica indicating a higher affinity for the former surfaces. Furthermore, on hydrophilic surfaces adsorbed amounts of MUC5B and BSM show good agreement at low concentrations (<0.10 mgml^-^1). However, at higher concentrations MUC5B adsorbed to a lower extent than BSM. At hydrophobic surfaces, isotherm shapes were similar for the two preparations, but the amounts were shifted to higher values for MUC5B. Finally, the presence of electrolyte increased adsorption and the increase was more pronounced on hydrophilic surfaces. The increased adsorption at a higher ionic strength indicates a more compact structure of the mucin due to electrostatic screening and the fact that the effect was more pronounced on the hydrophilic surfaces points to a higher relative importance of electrostatic interactions in this case. We conclude that the two mucins investigated behave in a qualitatively similar manner and show the highest affinity for hydrophobic surfaces.