OBJECTIVE: A previous sham-controlled multinational study demonstrated the short-term efficacy and safety for xerostomia treatment of an intraoral device that delivers electrostimulation to the lingual nerve. The objective of this study was to test the hypothesis that those beneficial effects would be sustained over an 11-month period. STUDY DESIGN: The device was tested on a mixed sample of 94 patients with xerostomia in an open-label, uncontrolled, prospective multicenter trial. Statutory outcome assessments were done at 5th, 8th, and 11th months and analyzed by multiple comparisons. RESULTS: Improvements achieved at month 5 from baseline were sustained throughout the follow-up period for the primary outcome, xerostomia severity, and the secondary outcomes resting whole salivary flow rate, xerostomia frequency, oral discomfort, and difficulties in speech, swallowing, and sleeping. No significant side effects were detected. CONCLUSIONS: The beneficial effects of a removable intraoral electrostimulating device were sustained for an 11-month period.

Different physico-chemical properties (eg adsorption kinetics, thickness, viscoelasticity, and mechanical stability) of adsorbed salivary pellicles depend on different factors, including the properties (eg charge, roughness, wettability, and surface chemistry) of the substratum. Whether these differences in the physico-chemical properties are a result of differences in the composition or in the organization of the pellicles is not known. In this work, the influence of substratum wettability on the composition of the pellicle was studied. For this purpose, pellicles eluted from substrata of different but well-characterized wettabilities were examined by means of sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). The results showed that substratum hydrophobicity did not have a major impact on pellicle composition. In all substrata, the major pellicle components were found to be cystatins, amylases and large glycoproteins, presumably mucins. In turn, interpretation of previously reported data based on the present results suggests that variations in substratum wettability mostly affect the organization of the pellicle components.

The formation of salivary films onto different surfaces relevant in dental research like titania, hydroxyapatite, gold, zirconia, silica, and hydrophobized silica has been studied by means of QCM-D. Human whole saliva (HWS), and sterile filtered HWS (sHWS) both diluted in water to a final concentration of 25% (v/v) were used. Main differences between the salivary films formed from the two saliva types were observed with the help of ΔD vs Δf plots where sHWS samples showed an almost linear adsorption regime for most of the surfaces whereas most of the HWS samples had a marked multi-regime nature indicating that the former ones are homogenous and the later are heterogeneous supporting previous data on a multi-phase adsorption process. The films with highest shear elastic modulus, μ > 105 N m−2, shear viscosity, η ∼ 3 × 10−3 N s m−2, and lowest thickness (∼10 nm) were formed for both types of saliva onto hydroxyapatite and for sHWS on titania. Furthermore, the ratio between the loss, G″, and the storage modulus, G′, indicates that these films have a solid-like behavior (G″/G′ ≤ 0.5). In contrast, for the remaining surfaces the adsorbed films show higher d values and are also characterized by low μ ∼ 104 N m−2, η ∼ 10−3 N s m−2, and by high ratios, G″/G′ > 2, that indicate a fluid like behavior. These observations might be expected to have influence on the lubricating properties of the salivary films. The SDS induced elutability also indicates a different interaction strength and composition of the adsorbed films and is likely associated with the ease by which these surfaces can be cleaned. Our results suggest that, among the relevant materials, zirconia and titania would yield the more lubricious films whereas hydroxyapatite will be the most easily cleaned.

The aim of this study was to compare the clinical outcomes of implant-supported overdentures (ODs) with either bar-clip or ball attachments. The implant, prosthesis failure, and technical complications were the outcomes analyzed in this retrospective clinical study conducted in a specialty clinic. Seventy-five patients with 242 implants supported by 76 ODs (36 maxillary, 40 mandibular) were included in the study and followed up for 88.8 ± 82.9 months (mean ± standard deviation). Bar-clip and ball attachments were used in 78.9% and 21.1% of the cases, respectively. Forty-three implant failures (17.8%) in 17 prostheses (17/76; 22.4%) were observed in this study. The average period of implant failure was 43.3 ± 41.0 months, and most of them were maxillary turned implants. The bar-clip system demonstrated more complications in the attachment parts compared to the ball attachment system. Poor retention of the prosthesis was similar between the two systems. Loss of implants resulted in the failure of 10 ODs in this study. ODs opposed by natural dentition or fixed prostheses presented with more complications. The Cox proportional hazards model did not show a significant effect on prosthesis failure for any of the factors. These findings indicated that patients with ODs need constant maintenance follow-ups to address the technical complications and perform prosthodontic maintenance regardless of the attachment system used.

Hypo-salivation, related to medical remedies, is an increasing clinical problem. Studies report a weak correlation between subjective mouth dryness and objective sialometry. This indicates that both quantity and quality of saliva are important for the surface-associated functions of saliva, such as lubrication and hydration, to be expressed. Film-forming properties and viscosities of three saliva substitutes were compared to human saliva. Adsorption to surfaces was measured by ellipsometry, infrared spectroscopy and drop-volume technique. Viscosity measurements were carried out using an oscillating rheometer. Saliva, with the lowest viscosity value and the highest protein content, presented superior film retention on both hydrophilic and hydrophobic surfaces. The carboxymethylcellulose-based MAS 84 showed intermediate values of viscosity, poorest ability to reduce surface tension, and negligible film-forming capacity. The porcine mucin-based Saliva Orthana showed about twice the viscosity of saliva and film-forming capability on preferably hydrophobic substrates. Salinum, a linseed extract, possessed the highest viscosity value and an initial surface tension close to that of saliva. The film retention on hydrophilic surfaces was not as effective as for saliva. The results indicate that the film-forming capacity of saliva substitutes is a property also to be considered in the exploration of clinically effective artificial salivas.

This study evaluated the anti-biofilm activity of sphingosine, phytosphingosine (PHS), and sphinganine for: (i) anti-adherence activity on hydroxyapatite (HA) surfaces; and (ii) bactericidal activity on different Streptococcus mutans phenotypes (i.e. planktonic cells and cells from a disrupted biofilm). For this, HA discs treated with sphingolipids were incubated with S. mutans and the number of adherent cells was evaluated by both culture and confocal microscopy. Sphinganine strongly inhibited bacterial adherence by 1000-fold compared with an untreated surface. Phytosphingosine and sphingosine inhibited bacterial adherence by eight- and five-fold, respectively, compared with an untreated surface. On saliva-coated HA, sphinganine and PHS inhibited bacterial adherence by 10-fold. Bactericidal activity of sphingolipids was evaluated by culture. For biofilms, the strongest bactericidal activity was exhibited by sphingosine compared with PHS and sphinganine. At a concentration of 12.5 μg ml−1, PHS and sphingosine were profoundly effective against planktonic and disrupted biofilms; and sphinganine reduced the number of cells in planktonic form by 100-fold and those derived from a disrupted biofilm by 1000-fold. Atomic force microscopy studies suggested that mechanical stability does not appear to be a factor relevant for anti-fouling activity. The results suggest that sphingolipids may be used to control oral biofilms, especially those loaded with S. mutans.

Films formed from saliva on surfaces are important for maintenance of oral health and integrity by protection against chemical and/or biological agents. The aim of the present study was to investigate adsorbed amounts, thickness and the structure of films formed from human whole saliva on alumina surfaces by means of in situ ellipsometry, neutron reflectivity and atomic force microscopy. Alumina (Al2O3, synthetic sapphire) is a relevant and interesting substrate for saliva adsorption studies as it has an isoelectric point close to that of tooth enamel. The results showed that saliva adsorbs rapidly on alumina. The film could be modelled in two layers: an inner and dense thin region which forms a uniform layer, and an outer, more diffuse and thicker region that protrudes towards the bulk of the solution. The film morphology described a uniformly covering dense layer and a second outer layer containing polydisperse adsorbed macromolecules or aggregates.

This paper describes a combined investigation of the salivary and MUC5B films structure and topography in conditions similar to those found in the oral cavity in terms of ionic strength, pH, and protein concentration. AFM and ellipsometry were successfully used to give a detailed picture of the film structure and topography both on hydrophilic and on hydrophobic substrata. Regardless of the substrata, the salivary film can be described as having a two sublayer structure in which an inner dense layer is decorated by large aggregates. However, the shape and height of these larger aggregates largely depend on the type of substrata used. Additionally, we show that the adsorption of MUC5B is controlled by the type of substrata and the MUC5B film topography is similar to that of the larger aggregates present in the salivary films, especially on hydrophobic substrates. Therefore, we conclude that MUC5B is a major component in the salivary film when formed on hydrophobic substrates. Furthermore, we studied how resistant the salivary and MUC5B films are against elutability by buffer rinsing and addition of SDS solution. We conclude that the adsorbed proteins contain fractions with varying binding strengths to the two types of surfaces. Specifically, we have shown that the large MUC5B biomacromolecules on the hydrophobic substrates are especially resistant to both elution with buffer solution and SDS. Therefore, these large mucins can be responsible for the increased resistance of HWS films on hydrophobic substrates and can protect the intraoral surfaces against surface-active components present in oral health care products.

A challenge for the next generation marine antifouling (AF) paints is to deliver minimum amounts of biocides to the environment. The candidate AF compound medetomidine is here shown to be released at very low concentrations, ie ng ml(-1) day(-1). Moreover, the release rate of medetomidine differs substantially depending on the formulation of the paint, while inhibition of barnacle settlement is independent of release to the ambient water, ie the paint with the lowest release rate was the most effective in impeding barnacle colonisation. This highlights the critical role of chemical interactions between biocide, paint carrier and the solid/aqueous interface for release rate and AF performance. The results are discussed in the light of differential affinity states of the biocide, predicting AF activity in terms of a high surface affinity and preserved bioavailability. This may offer a general framework for the design of low-release paint systems using biocides for protection against biofouling on marine surfaces.

The modification of acidic beverage formulations with food-approved, nonhazardous substances with antierosive properties has been identified as a key strategy for counteracting the prevalence of dental erosion, i.e., the acid-induced dissolution of hydroxyapatite (HA, the main mineral component of tooth surfaces). While many of such substances have been reported, very little is known on how they interact with teeth and inhibit their acid-induced dissolution. With the aim of filling this gap in knowledge, we have studied under acidic conditions the interaction between two polyelectrolytes of differing ionic character, carboxymethyl cellulose (CMC) and chitosan, and saliva-coated hydroxyapatite, i.e., a model for the outer surface of teeth. These studies were performed by means of ellipsometry, quartz crystal microbalance with dissipation monitoring, and atomic force microscopy. We also studied, by means of pH variations, how dissolution of saliva-coated HA is affected by including these polyelectrolytes in the erosive solutions. Our results confirm that salivary films protect HA from acid-induced dissolution, but only for a limited time. If the acid is modified with CMC, this polyelectrolyte incorporates into the salivary films prolonging in time their protective function. Eventually, the CMC-modified salivary films are removed from the HA surfaces. From this moment, HA is continuously coated with CMC, but this offers only a weak protection against erosion. When the acid is modified with the cationic chitosan, the polyelectrolyte adsorbs on top of the salivary films. Chitosan-modified salivary films are also eventually replaced by bare chitosan films. In this case both coatings offer a similar protection against HA dissolution, which is nevertheless notably higher than that offered by CMC.

We present data on operation of a miniature membrane-less, direct electron transfer based enzymatic fuel cell in human sweat and saliva. The enzymatic fuel cell was fabricated following our previous reports on miniature biofuel cells, utilizing gold nanoparticle modified gold microwires with immobilized cellobiose dehydrogenase and bilirubin oxidase. The following average characteristics of miniature glucose/oxygen biodevices operating in human sweat and saliva, respectively, were registered: 580 and 560 mV open-circuit voltage, 0.26 and 0.1 μW cm–2 power density at a cell voltage of 0.5 V, with up to ten times higher power output at 0.2 V. When saliva collected after meal ingestion was used, roughly a two-fold increase in power output was obtained, with a further two-fold increase by addition of 500 μM glucose. Likewise, the power generated in sweat at 0.5 V increased two-fold by addition of 500 μM glucose.

Lactoperoxidase (LPO) is an enzyme, which is used as an antimicrobial agent in a number of applications, e.g., food technology. In the majority of applications LPO is added to a homogeneous product phase or immobilised on product surface. In the latter case, however, the measurements of LPO activity are seldom reported. In this paper we have assessed LPO enzymatic activity on bare and protein modified gold surfaces by means of electrochemistry. It was found that LPO rapidly adsorbs to bare gold surfaces resulting in an amount of LPO adsorbed of 2.9 mg/m2. A lower amount of adsorbed LPO is obtained if the gold surface is exposed to bovine serum albumin, bovine or human mucin prior to LPO adsorption. The enzymatic activity of the adsorbed enzyme is in general preserved at the experimental conditions and varies only moderately when comparing bare gold and gold surface pretreated with the selected proteins. The measurement of LPO specific activity, however, indicate that it is about 1.5 times higher if LPO is adsorbed on gold surfaces containing a small amount of preadsorbed mucin in comparison to the LPO directly adsorbed on bare gold.

The aim of this paper was to elucidate the mechanisms behind salivary lubrication with special emphasis on the lubricity of three key components of the pellicle, viz human acidic proline-rich protein 1 (PRP-1), human statherin and bovine submaxillary mucin (BSM). The lubricating properties of the proteins have been assessed by means of colloidal probe atomic force microscopy, and are discussed in relation to their adsorption behaviour. To various extents, the proteins investigated all showed a lubricating effect when adsorbed to silica surfaces. For comparable concentrations, PRP-1 was found to have a more pronounced lubricating effect than BSM, which in turn showed a higher lubricity than statherin. The relative lubricity is in accordance with previously reported relative adsorbed amounts of the three proteins, within the investigated concentration interval. It is concluded that PRP-1 has the highest lubricating capacity as a pure fraction among the preparations investigated, and that the lubricating effect of PRP-1 as a pure fraction is notably large as compared to the lubricity of human whole saliva.

The aims of the study were to characterize a nanostructured photoactive titanium dioxide (TiO(2)) coating and to compare the cellular response of human osteoblasts before and after ultraviolet (UV) irradiation of the coating. A specific nanostructured TiO(2) powder (Degussa P-25), which consists of approximately 80% anatase and 20% rutile, was spin-coated onto commercially pure titanium discs, and was heat-treated thereafter. After topographical, chemical and photocatalytic property characterizations, human osteoblasts were cultured on the coated discs before and after UV irradiation. Cell morphology was evaluated by scanning electron microscopy (SEM), and cell viability was analysed by 3-(4,5-dimethylthiazol)-2,5-diphenyltetrazolium bromide (MTT) assay. From the contact angle analysis, the wettability significantly improved after UV irradiation. The cultured cells were flattened with numerous elongated lammellipodia; however, no morphological differences were indicated between -UV and +UV surfaces. The MTT assay analysis showed that -UV surface presented significantly higher viability compared to the +UV surface except for one cell population group at 3h where there were no differences. The nanostructured photoactive TiO(2) surface improved its hydrophilicity by UV irradiation, however no enhancing effect in cell response was confirmed at the time tested compared to the non-irradiated surface.

The aim of this prospective clinical pilot study was to evaluate the pain alleviation effectiveness of two desensitizing agents (VivaSens® and Seal&Protect®) on 30 patients suffering from cervical dentine sensitivity (CDS) over a six month period. Analysis of possible differences in pain alleviation effect between the agents and over time was performed. Further, the experienced pain was registered in a questionnaire regarding to what extent the treatment improved oral health/life quality among the patients. The patients (23 female, 7 male) were randomly divided into two groups. Each group was treated with one of the two desensitizing agents. Sensitivity measurements were recorded before treatment (baseline) and after treatment at time points of one week and six months. The patients were asked to rate the sensitivity experienced in the area during air stimulation by marking on a Visual Analogue Scale (VAS). At six months, 27 patients (90 %) had completed the clinical trial. The results showed that a significant reduction of CDS was achieved by using VivaSens® or Seal&Protect® after both one week and six months. However, there were no differences found on treatment effects between the two desensitizing agents. The results from the questionnaire showed that the patients experienced improved oral health/life quality when comparing the status before and after treatment (0.000 < p < 0.021) and there were no statistically significant difference in treatment effects between the products. In conclusion, both desensitizing agents were effective in relieving cervical dentin hypersensitivity during the time course of the study as evaluated both by air stimulation and a questionnaire related to oral health/quality of life status.

In Sweden, the National Board of Health and Welfare forecasts a decrease in dentists with 26% and an increase in dental hygienists with 47% until the year of 2023. This, together with changes in both epidemiology, especially of dental caries, and political priorities, calls for an effective and well-developed cooperation between dentists and dental hygienists in future dentistry. Hence, the aim of this project was to investigate whether highlighting teamwork during the undergraduate studies of dental students and dental hygiene students could improve the students' holistic view on patients as well as their knowledge of and insight into each other's future professions. Thirty-four dental students and 24 dental hygiene students participated in the study. At the beginning of their final year in undergraduate education, a questionnaire testing the level of knowledge of the dental hygienists' clinical competences was completed by both groups of students. In addition, activities intending to improve teamwork quality included the following: (i) a seminar with a dentist representing the Public Dental Health Services in Sweden, (ii) dental students as supervisors for dental hygiene students, (iii) planning and treatment for shared patients and (iv) students' presentations of the treatments and their outcomes at a final seminar. The project was ended by the students answering the above-mentioned questionnaire for the second time, followed by an evaluation of the different activities included in the study. The knowledge of dental hygienists' competences showed higher scores in almost all questions. Both groups of students considered the following aspects important: seminars with external participants, dental students acting as supervisors and planning and treating shared patients. By initiating and encouraging teamwork between dental students and dental hygiene students, it is possible to increase knowledge on dental hygienists' competence and also to develop and strengthen a holistic view on patients and dental work, thereby preparing both groups of students for their professional life.

An effective and well developed cooperation between dentists and dental hygienists is crucial in future dentistry. In Sweden the National Board of Health and Welfare forecast of a decrease of dentists with 26% and an increase of dental hygienists with 47% until year 2023. Clinical teamwork is introduced and performed when the students start their last year at the dental school in Malmö. The aim of this project is to study if highlighting teamwork during these undergraduate studies will improve the holistic view on patients by development of the educational context as well as to improve quality of dental care and use of available recourses by knowledge of competence of the respective professionals.

Den 29 april 2002 försvarade legitimerade tandläkaren Liselott Lindh sin avhandling för odontologie doktorsexamen ”On the adsorption behaviour of saliva and purified salivary proteins at solid/liquid interfaces” vid avdelningen för oral protetik, odontologiska fakulteten, Malmö Högskola. Fakultetsopponent var George L. Grobe III, PhD, Director of Material & Surface Science, Bausch & Lomb Rochester, usa. Handledare under avhandlingsarbetet var professor Per-Olof Glantz, avdelningen för oral protetik, odontologiska fakulteten, Malmö Högskola. Syftet med avhandlingen var att öka kunskapen om de grundläggande processerna vid uppbyggnaden av en salivfilm. autoreferat

Salivary proteinaceous substances are known to play important roles in the formation of the salivary pellicle. The aim of this study was to investigate some aspects of the interfacial behaviour of selected purified salivary proteins, as well as human saliva secretions, using time resolved in situ ellipsometry. Hydrophobic methylated silica and hydrophilic pure silica were used as test substrates. Experiments were performed in vitro, preferentially in the low concentration range, with samples of fresh human whole resting saliva, parotid resting saliva and submandibular/sublingual resting saliva. The protein fractions investigated were human MUC5B, PRP-1, PRP-3 and statherin, as well as bovine submaxillary mucin (BSM). The results show that the adsorbed amount of material was found to be strongly related to the protein concentration in the range investigated for both pure proteins and secretions. Generally, for both pure proteins and secretions, higher amount of material was adsorbed on hydrophobic surfaces compared to hydrophilic ones. Comparison of the observed adsorption and calculated diffusion rates suggest initial adsorption of low molecular weight proteins/peptides. On hydrophilic surfaces the data indicate adsorption of proteins with diffusion rates corresponding to those of statherin, PRP-3 and PRP-1. MUC5B adsorbs in a later stage from both HWS and the individual secretions, due to its lower diffusion rate. On hydrophobic surfaces, adsorption rates were found to be faster than those calculated for any of the proteins, and thus smaller proteins/peptides appear to be involved. The similar adsorption rates and amounts of PRP-1 and parotid saliva (HPS) on hydrophilic surfaces may suggest that large aPRPs accounts for a substantial portion of the film forming capacity by HPS. Effects of added electrolyte could be explained by general screening effects and specific Ca2+ binding to serine phosphates in aqueous solutions, but were complex in phosphate buffer. Inter-individual differences in adsorbed amounts from HWS, HPS and HSMSLS were not found to be statistically significant.

The rates and plateau values of adsorption at the solid/ liquid interface from human whole resting saliva from three male donors were studied in vitro. The influence of saliva concentration, the total protein content and the wettability of the exposed solids was investigated. Ellipsometry was used to study the rate and plateau values of the adsorption process in situ. The solid surfaces used were hydrophilic, negatively charged, silica and hydrophobic methylated silica. Salivary films were formed by adsorption from solutions of 0.05%, 0.10%, 0.20%, 0.50%, 1.0% and 2.0% (v/v) saliva in phosphate buffered saline. The results revealed that adsorption onto both types of surfaces was a rapid and, as expected, a concentration dependent process. The adsorbed amounts were in the range of monomolecular layers and were found to be larger onto the hydrophobic than the hydrophilic surfaces (p≤0.0062). A strong concentration dependence was denoted in all cases (p< 0.0001). Inter-individual differences were found not to be significant (0.0636 ≤ p≤ 0.8508) at any of the saliva concentrations. However, an interaction was shown (p < 0.0001) between the protein concentrations and the donors, indicating qualitative differences in protein content and surface activity.

The salivary pellicle is a thin acellular organic film that forms on any type of surface upon exposure to saliva. The role of the pellicle is manifold, and it plays an important role in the maintenance of oral health. Its functions include not only substratum protection and lubrication, but also remineralization and hydration. It also functions as a diffusion barrier and possesses buffering ability. Not only the function, but also the formation, composition and stability of the pellicle are known to be highly influenced by the physicochemical properties of both substrata and ambient media. In this chapter, we discuss these aspects of salivary pellicles, an area where research has boomed in the past years partly because of the application of experimental techniques often reserved for more traditional surface science studies.

Films formed from saliva on surfaces are important for maintenance of oral health and integrity by serving as barriers against chemical and/or biological agents. OBJECTIVES: The aim of the present study was to investigate the structure of films formed from human whole saliva onto alumina surfaces. METHODS: In situ ellipsometry was used to investigate adsorbed amounts and thickness of the adsorbed layers. Neutron reflectivity and atomic force microscopy (AFM) were used to study the density profile within the adsorbed layer and morphology, respectively, of the adsorbed salivary film onto alumina (Al2O3). RESULTS: The results show that saliva adsorbed rapidly on alumina. First a thin and dense layer covered the surfaces. With time, a thicker and diffuser layer was developed. The film morphology described a uniformly covering dense layer and a second outer layer containing polydisperse adsorbed macromolecules or aggregates. CONCLUSION: The film was found to be composed of two layers: an inner and dense thin region, that forms a uniform layer, and an outer, more diffuse and thicker region that protrudes towards the bulk of the solution. This study was supported by research grants from the Knowledge Foundation, Malmö University, The Swedish Dental Society, The Swedish Patent Revenue Fund for Research in Preventive Dentistry, The Swedish Research Council and Uppsala University. We are grateful also to the Institute Laue Langevin, Grenoble for an allocation of neutron beam time.

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.

The influence of saliva concentration, saliva total protein content and the wetting characteristics of exposed solids on in vitro film formation was studied by the technique of in situ ellipsometry. The rates and plateau values of adsorption (45 min) at solid/liquid interfaces (hydrophilic silica and hydrophobic methylated silica surfaces) were determinated for human parotid (HPS) and submandibular/sublingual (HSMSLS) resting saliva solutions (0.1 and 1.0%, (v/v), saliva in phosphate buffered saline). Adsorption rates were related to a model assuming mass transport through an unstirred layer adjacent to the surface. The results showed that the adsorption was rapid, concentration dependent and higher on hydrophobic than on hydrophilic surfaces. Analysis of the influence of protein concentration on the adsorbed amounts demonstrated an interaction between protein concentration and the two surfaces for HPS and HSMSLS, respectively. This may indicate differences in binding mode. Inter-individual differences were found not to be significant at the 1% level of probability. Comparison of the observed adsorption and calculated diffusion rates suggest that on hydrophilic surfaces initial adsorption of proteins diffusing at rates corresponding to those of statherin and aPRPs takes place, whereas on hydrophobic surfaces lower molecular mass compounds appear to be involved.

The objective of the present study was to investigate the adsorption of PRP-1, PRP-3 and statherin to solid surfaces in terms of dependence on concentration, the presence of electrolyte and surface wettability. Time resolved in situ ellipsometry was used to determine the adsorbed amounts and adsorption rates of pure PRP-1, PRP-3 and statherin onto pure (hydrophilic) and methylated (hydrophobized) silica surfaces. The initial film build-up was fast and plateaus were reached within 10 min at all concentrations for both types of surfaces and all proteins. The observed adsorption and calculated diffusion rates of PRP-1, PRP-3 and statherin, respectively, indicated that the initial adsorption was mass transport controlled at low concentrations. At hydrophobic surfaces, isotherm shapes and adsorbed amounts were similar for PRP-1 and PRP-3, while statherin adsorbed to a higher extent. At hydrophilic surfaces only PRP-1 adsorbed substantially, while for PRP-3 and statherin adsorbed amounts were low. The presence of Ca 2+ ions in the phosphate buffer solution increased the adsorption of statherin and PRP-3 on hydrophobic surfaces, while PRP-1 was unaffected. On hydrophilic surfaces, all three proteins adsorbed in higher amounts in NaCl, compared to CaCl 2 at similar ionic strength. It is concluded that acidic PRPs (PRP-1 and PRP-3) and statherin readily form films on a variety of materials and solution conditions, showing that their functions may be fulfilled under a wide range of conditions.

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.

Abstract In situ ellipsometry was used to study layer-by-layer film formation on hydrophilic and hydrophobized silica surfaces by alternating sequential adsorption of human mucin MUC5B and cationic proteins lysozyme, lactoferrin, lactoperoxidase or histatin 5, respectively. The stability of the multilayers was investigated by addition of sodium dodecyl sulfate solution (SDS). Atomic force microscopy was employed to investigate morphological structures on the surfaces during the layer-by-layer film build-up. It was clearly shown that, on both hydrophilic and hydrophobized silica, only MUC5B and lactoperoxidase showed the ability for multilayer formation, resulting in an approximately linear increase in adsorbed amount and film thickness with each deposition cycle. The net increase in amounts per cycle was larger on the hydrophilic silica. Further, MUC5B needs to be adsorbed first on the hydrophilic substrates to obtain this fast build-up behavior. Generally, addition of SDS solution showed that a large fraction of the adsorbed film could be desorbed. However, films on the hydrophobized silica were more resistant to surfactant elution. In conclusion, MUC5B–cationic protein multilayers can be formed on hydrophilic and hydrophobized silica, depending on the choice of the cationic protein as well as in which order the build-up is started on hydrophilic silica. Additionally, SDS disrupts the layer-by-layer film formed by MUC5B and lactoperoxidase.

STATEMENT OF PROBLEM: The second most common biological complication in fixed prosthodontics is loss of pulp vitality, which may lead to restoration loss. While reasons for loss of pulp vitality are unclear, 2 potential contributing factors, duration of the interim restoration and operator experience, have not been fully investigated.

PURPOSE: The purpose of this retrospective study was to investigate whether the duration of the interim restoration or the experience of the dentist was correlated with loss of pulp vitality.

MATERIAL AND METHODS: Fixed prosthetic restorations placed between 2005 and 2012 were retrospectively analyzed. Abutment teeth supporting single-unti or multiunit restorations were evaluated regarding loss of pulp vitality. The Mann-Whitney U test and simple logistic regression were used, with α=.05 for the subsequent multiple logistic regression. The experience of dental professionals was defined by the number of treatments performed and coupled with failure rate by using an analysis of variance.

RESULTS: One hundred seventy-four dentists made 15 879 restorations, of which 1136 failed during the observation period, a failure rate of 7.2%. Two hundred fifty restorations were randomly selected from the failed restorations, and a corresponding 250 restorations were randomly selected from nonfailed restorations for the control group. Increased duration with interim replacement was linked to a higher risk of loss of pulp vitality (P<.001). Failure rate in the dentist group varied from 0% to 100%. No significant differences in failure rate were found among dentists who did few restorations and those who performed larger numbers of restorations.

CONCLUSIONS: The results of the present study suggest that operator experience does not affect failure rate. However, extended time with an interim restoration was a contributing factor to the loss of pulp vitality.

The salivary protein statherin is known to adsorb selectively onto hydroxyapatite (HA), which constitutes the main mineral of the tooth enamel. This adsorption is believed to be crucial for its function as an inhibitor of primary (spontaneous) and secondary (crystal growth) precipitation of calcium phosphate salts present in saliva. A fragment corresponding to the first 21 N-terminus amino acids of statherin (StN21) was previously found to reduce the rate of demineralization of HA. Therefore, the interfacial properties of this peptide and statherin onto silica, hydrophobized silica and HA discs was studied by in situ ellipsometry. Their reversibility induced by dilution and elutability induced by buffer and sodium dodecyl sulfate (SDS) was also determined. The results revealed that statherin adsorbed at a greater extent onto the HA as compared to StN21, suggesting that the hydrogen bonding between the uncharged polar residues at the C-terminal region of statherin and HA contributes to its adsorption. However, on both silica surfaces the peptide adsorption appeared to proceed in a similar way. Onto the hydrophobized silica the adsorption of both peptides was suggested to occur either via multilayer formation or adsorption of aggregates from solution, while onto the hydrophilic silica adsorption of peptide aggregates from solution was the suggested mechanism. Further, both peptides were observed to be strongly adsorbed onto HA, even after SDS treatment, in comparison to the layers adsorbed onto hydrophobized silica. Both peptide layers were found to be weakly adsorbed onto the hydrophilic silica surface as they were totally removed by buffer dilution.

The adsorption of human whole saliva (HWS) onto silica and hydroxyapatite surfaces (HA) was followed by quartz crystal microbalance with dissipation (QCM-D) and ellipsometry. The influence of different surface properties and adsorption media (water and PBS) on the HWS adsorption was studied. The viscoelastic properties of the saliva films formed onto the solid surfaces were estimated by the use of the Voigt-based viscoelastic film model. Furthermore, the efficiency of SDS and delmopinol to elute the adsorbed saliva film from the surfaces was investigated at different surfactant concentrations. It was observed a biphasic kinetic regime for the adsorption of saliva on the silica and HA surfaces, indicating the formation of a rigidly coupled first layer corresponding to an initial adsorption of small proteins and a more loosely bound second layer. The results further showed a higher adsorption of HWS onto the HA surfaces compared to the silica surfaces in both adsorption media (PBS and water). The adsorption in PBS led to higher adsorbed amounts on both surfaces as compared to water. SDS was found to be more efficient in removing the saliva film from both surfaces than delmopinol. The salivary film was found to be less tightly bound on to the silica surfaces since more saliva film could be removed with both SDS and delmopinol compared to from the HA surface. When saliva was adsorbed from PBS a higher energy dissipation was determined implying that a softer saliva layer is build up in PBS as opposed to in water. In the same media (water) a softer saliva layer was formed onto the HA surfaces, while in PBS the saliva layer formed at both surfaces seems to have similar structure.

This study investigated the effect of glow discharge treatment of titania surfaces on plasma protein adsorption, by means of ellipsometry and mechanically assisted SDS elution. The adsorption and film elution of three plasma proteins, viz. human serum albumin (HSA), human immunoglobulin G (IgG) and laminin-1, as well as competitive adsorption from a mixture of the three proteins, showed that the adsorbed amount of the individual proteins after 1 h increased in the order HSA

The structural properties of the salivary proteins, acidic proline rich PRP-1 and statherin, adsorbed onto negatively charged surfaces have been studied by Monte Carlo simulations and ellipsometry. It is shown that both proteins adsorb to negatively charged surfaces, although their net charges are negative. Experimentally, an initial fast mass-controlled film build-up was detected for both proteins, and plateaus were reached within 10 minutes. The isotherm shape and the adsorbed amounts were similar for PRP-1 to hydrophilic and hydrophobic surfaces, while statherin adsorbs to a greater extent to the hydrophobic surface. These results could be explained from the simulation results by considering the proteins as diblock polyampholytes. It has also been shown that the adsorption of PRP-1 to a negatively charged surface may be purely electrostatically driven, while pure electrostatic interaction is not sufficient to drive adsorption of statherin, i.e., an extra short-ranged attractive interaction is necessary to account for the experimental observations.

We show in this work how systems formed by phosphoproteins on calcium phosphate surfaces can be directly characterized, in real time, in liquid medium, without the need for elution or labeling. Specifically, we show how this is possible by applying three different techniques: ellipsometry, quartz crystal microbalance with dissipation, and atomic force microscopy-based friction force spectroscopy. We apply these techniques to study two different model systems, i.e. those formed upon the adsorption of two model phosphoproteins (κ- and β-casein) on hydroxyapatite (HA) surfaces. Information on the kinetics of adsorption, surface excess, viscoelasticity, water content, thickness of the layers, and protein-surface interaction is provided. Results indicate that both phosphoproteins form homogeneous elastic highly hydrated monolayers on the HA surfaces, the strength of β-casein layers being higher by approximately a factor of 4. Based on the experimental results, models for the conformation of κ- and β-casein molecules adsorbed on HA surfaces are proposed.