Influence of periodic polyphenol treatment on the anti-erosive potential of the acquired enamel pellicle-A qualitative exploratory study.

OBJECTIVE: The aim of the present study was to investigate the impact of periodic polyphenol treatment on the ultrastructure and anti-erosive potential of an in-situ formed pellicle. METHODS: Subjects wore intraoral appliances with buccally and palatally fixed bovine enamel specimens. During 6 h of intraoral pellicle formation, 100 ml black tea or tannic acid was applied ex-vivo every 25 min for 5 min. Untreated pellicles served as control. After the trial, specimens were immersed in 0.1% or 1% citric acid for 60 s and analysed for calcium release with atomic adsorption spectrometry and ultrastructure with transmission electron microscopy. RESULTS: Specimens covered by pellicles treated with black tea or tannic acid released less calcium than untreated pellicles. Ultrastructural analyses reveal an increase in pellicle's thickness and density after treatment with polyphenols. CONCLUSIONS: Periodic polyphenol treatment of the pellicle modify its ultrastructure and increase its anti-erosive potential. CLINICAL SIGNIFICANCE: Consumption of polyphenolic beverages can enhance the anti-erosive potential of the enamel pellicle.

Influence of periodic milk or cream treatment on the anti-erosive potential of the acquired enamel pellicle.

OBJECTIVE: The purpose of the present study was to assess the anti-erosive potential of the acquired enamel pellicle formed in situ under the influence of periodic milk or cream treatment. METHODS: The pellicle was formed on bovine enamel specimens in the oral cavity at buccal and palatal sites of upper molars in 6 subjects, using removable acrylic splints. During 6-h of intraoral exposure, splints were removed from the oral cavity every 25 min, treated with milk or cream for 5 min, and subsequently re-inserted into the oral cavity. After 6 h, pellicle covered specimens were immersed in citric acid (0.1 or 1.0 %) for 1 min, and processed for measurement of surface microhardness, determination of calcium release by atomic absorption spectroscopy, scanning and transmission electron microscopy. Statistical analysis was performed with SAS. RESULTS: Statistical analysis did not indicate major differences between erosive surface alterations on enamel specimens covered by pellicles treated with cream or milk, and those covered by control pellicles. In addition, TEM analysis did not reveal any differences concerning the ultrastructure of the different pellicle treatments during acid exposure. All pellicles were dissolved in part after exposure to 0.1 % citric acid and were nearly completely removed after treatment with 1.0% citric acid. CONCLUSIONS: It is concluded that periodic treatment with milk or cream during pellicle formation in situ does not improve the protective potential of the acquired enamel pellicle against erosion. CLINICAL SIGNIFICANCE: Modification of the pellicle by consumption of milk or cream prior to an acidic challenge cannot sufficiently protect enamel from erosion.

Long-term outcomes of psychological treatment for posttraumatic stress disorder: a systematic review and meta-analysis.

Several types of psychological treatment for posttraumatic stress disorder (PTSD) are considered well established and effective, but evidence of their long-term efficacy is limited. This systematic review and meta-analysis aimed to investigate the long-term outcomes across psychological treatments for PTSD. MEDLINE, Cochrane Library, PTSDpubs, PsycINFO, PSYNDEX, and related articles were searched for randomized controlled trials with at least 12 months of follow-up. Twenty-two studies (N = 2638) met inclusion criteria, and 43 comparisons of cognitive behavioral therapy (CBT) were available at follow-up. Active treatments for PTSD yielded large effect sizes from pretest to follow-up and a small controlled effect size compared with non-directive control groups at follow-up. Trauma-focused treatment (TFT) and non-TFT showed large improvements from pretest to follow-up, and effect sizes did not significantly differ from each other. Active treatments for comorbid depressive symptoms revealed small to medium effect sizes at follow-up, and improved PTSD and depressive symptoms remained stable from treatment end to follow-up. Military personnel, low proportion of female patients, and self-rated PTSD measures were associated with decreased effect sizes for PTSD at follow-up. The findings suggest that CBT for PTSD is efficacious in the long term. Future studies are needed to determine the lasting efficacy of other psychological treatments and to confirm benefits beyond 12-month follow-up.

The effect of polyphenol-containing solutions on in situ biofilm formation on enamel and dentin.

OBJECTIVES: To investigate the effects of Chinese gallnut extracts and pure tannic acid on in situ biofilm formation on enamel and dentin samples over 24 h. METHODS: Bovine enamel and dentin samples were buccally fixed on maxillary splints. Six volunteers wore the splints for 24 h, and rinsed their mouths with tap water (control), 1% tannic acid- and 1% Chinese gallnut extracts-containing solution twice a day, 3 min after the splints were placed in the mouth and before night sleep. Live/dead staining was used for fluorescence microscopic (FM) visualization and quantification of bacteria viability of biofilms formed on enamel and dentin samples. Biofilm coverage was evaluated and recorded by FM and scanning electron microscopy (SEM). In addition, biofilms were analyzed by transmission electron microscopy (TEM). The Kruskal-Wallis test was used to analyze biofilm data. RESULTS: Rinsing with tannic acid- and Chinese gallnut extracts-containing solutions significantly reduced in situ biofilm coverage on enamel and dentin samples (P < 0.05). The bacterial viability of biofilms formed on enamel samples was significantly reduced compared to the control (P < 0.05). TEM analysis revealed an increase in pellicle's electron density and thickness and only few or no bacteria adherent to the pellicle in the experimental samples. CONCLUSIONS: Rinsing with tannic acid- and Chinese gallnut extracts-containing solutions can effectively inhibit in situ biofilm formation, modify the ultrastructure of biofilms on enamel and dentin surfaces and significantly reduce the bacterial viability of biofilm on enamel surfaces. CLINICAL SIGNIFICANCE: Tannic acid- and Chinese gallnut extracts-containing solutions might be used for dental biofilm management.

Comprehensive measurements of salivary pellicle thickness formed at different intraoral sites on Si wafers and bovine enamel.

The salivary pellicle is a thin acellular film formed on orally exposed surfaces by adsorption of macromolecules from the oral fluids and serves as a protective layer in the maintenance of oral health. Pellicle thickness measurements are a central tool helping to understand how exogenous manipulations may influence pellicle formation. This is of particular importance for the investigation of new preventive and therapeutic approaches. In the present study we determined the kinetics of the in situ pellicle thickness formation at different intraoral sites and investigated how pellicle formation occurs in different individuals. To address the kinetic aspect, the thickness of the in situ pellicle was determined after formation periods of 3 min, 30 min and 120 min. The thickness of the pellicle was either measured on silicon wafers by ellipsometry or on bovine enamel by transmission electron microscopy. We found a physiologically important rapid pellicle formation phase within the first minutes and a slow pellicle formation phase between 30 min and 120 min. Furthermore, our results identify significant inter-individual differences both for the pellicle thickness and for the formation kinetics, indicating the consideration of individual-specific differences of the pellicle layer as an important aspect for future studies.

Patient's experience with blended video- and internet based cognitive behavioural therapy service in routine care.

INTRODUCTION: Internet-based guided self-help and face-to-face CBT have shown to be effective in the treatment of depression, but both approaches might not be an available treatment option for all patients. A treatment which blends internet-based guided self-help with video-based psychotherapy might reduce potential disadvantages of both approaches, while maintaining major advantages such as being location-independent. Additionally, it could provide a stronger focus on patient empowerment and lower resource use compared to traditional face-to-face treatment. AIM: The aim of this study is to evaluate patient's experiences with blended internet- and video-based CBT (blended iCBT) treatment and to derive suggestions for the improvement of such services. METHODS: Semi-structured interviews were conducted with 15 participants of the blended iCBT treatment as part of the European MasterMind trial. Participants included adults suffering from Major Depressive Disorder. The interview guide assessed patient's experiences regarding the four treatment components program, 1. face-to-face diagnostic interviews, 2. video-based synchronous therapy sessions (VTS), 3. online self-help treatment modules (OTM) as well as 4. behaviour diaries and symptom monitoring. Interviews were analyzed using the framework method and outcomes regarding connections within and between participants and categories were generated by counting the statements within relevant themes. RESULTS: Overall, patients indicated to have been satisfied with all components of the treatment, highlighting the option to independently work from home in their own pace. While the OTMs allowed for a deeper reflection of the content, the VTS with the therapist were mentioned to provide the personal character of the service. The working alliance with the therapist was experienced as fostering the individual fit of the treatment. Patients reported a high self-perceived treatment effectiveness. Negative effects included that some patients felt overwhelmed by the service, e.g. by working with the content of the OTM as they forced them to address their problems. Within the combination of OTM and VTS, both components were rated as equally important and patients felt that the combination depicted a treatment at least equal to regular face-to-face treatment regarding the perceived effectiveness. Other identified themes included patient's individual factors, reactions in their social environment and suggestions for improvement of the service. DISCUSSION: Predominantly, patients reported positive experiences with the blended iCBT service and rate the treatment as adequate and effective to treat their condition. The importance of the VTS is highlighted. Following this approach might be an option to make affordable and effective evidence-based CBT available independent from regional barriers.

Confirmatory factor analysis of the causal illness attribution scale in Chinese patients with multiple somatic symptoms.

Causal illness attributions influence how individuals cope with somatic symptoms and illnesses. Dimensions of causal symptom attributions have been examined in Western cultures with the subscale 'causes' of the revised Illness Perception Questionnaire (IPQ-R). Some previous studies have identified a stronger somatic attribution style in Asian patients. In this study it was examined if the factorial structure of causal attributions identified in Western populations can be identified in a large Chinese sample of patients presenting with somatic symptoms. We recruited 665 patients aged at least 18 who were visiting the hospital for reasons of treatment from departments of traditional Chinese medicine (TCM), neurology (Biomedicine), and psychosomatic medicine in six hospitals across China. All subjects completed the Patient Health Questionnaire (PHQ) and the causes subscale of the IPQ-R. We split the data-set by chance in two parts. On the first subsample, we conducted a confirmatory factor analysis (CFA) to check the fit of the originally proposed 4-factor structure and an exploratory factor analysis (EFA). The factor structure indentified in the EFA was rechecked with a CFA in the second subsample. The originally proposed 4-factor-model of the IPQ-R subscale causes showed no adequate fit in the first subsample. The EFA revealed two factors, psychological attributions and risk factors. The CFA in the second sample showed mediocre fit indices (RMSEA = .098, CFI = .923). For the Chinese sample we propose a two-factor structure for IPQ-R causes scale. As in other studies, we identified the relatively stable factor psychological attributions, indicating no fundamental differences in illness attributions between Western and Chinese samples.

Effect of Tannic Acid on the Protective Properties of the in situ Formed Pellicle.

OBJECTIVES: In the present in situ/ex vivo study the impact of tannic acid on the erosion-protective properties of the enamel pellicle was tested. Additionally, the antiadherent and antibacterial effects of tannic acid were evaluated. METHODS: The pellicle was formed in situ on bovine enamel samples fixed on individual splints worn by 6 subjects. Following 1 min of pellicle formation the volunteers rinsed for 10 min with tannic acid. After further oral exposure for 19 min, 109 min, and 8 h overnight, respectively, slabs were incubated in HCl ex vivo (pH 2.0, 2.3, 3.0) over 120 s. Subsequently, kinetics of calcium and phosphate release were measured photometrically. Samples after a 1-min fluoride mouth rinse as well as enamel samples with and without a 30-min in situ pellicle served as controls. Antiadherent effects were evaluated after a 1-min rinse with tannic acid and oral exposure of the slabs overnight. DAPI (4',6-diamidino-2-phenylindole) combined with concanavalin A staining and live/dead staining was used for fluorescence microscopic visualization and quantification of adherent bacteria and glucans. Modification of the pellicle's ultrastructure by tannic acid was evaluated by transmission electron microscopy (TEM). RESULTS: Tannic acid significantly improved the erosion-protective properties of the pellicle in a pH-dependent manner. Bacterial adherence and glucan formation on enamel were significantly reduced after rinses with tannic acid as investigated by fluorescence microscopy. TEM imaging indicated that rinsing with tannic acid yielded a sustainable modification of the pellicle; it was distinctly more electron dense. CONCLUSION: Tannic acid offers an effective and sustainable approach for the prevention of caries and erosion.

Effect of Inula viscosa on the pellicle's protective properties and initial bioadhesion in-situ.

OBJECTIVES: The present in situ study investigated the effect of Inula viscosa tea on the pellicle's acid protective properties and on initial oral biofilm formation. DESIGN: Biofilm formation was performed on bovine enamel slabs on individual maxillary splints. Following 1min of pellicle formation, eight subjects rinsed for 10min with Inula viscosa tea and the splints remained for 8h intraorally. Samples carried after 1-min rinsing with CHX (0.2%) or without rinse served as controls. BacLight™ staining, 4',6-diamidino-2-phenylindole (DAPI)-staining and fluorescence in situ hybridization (FISH) were used for fluorescence microscopic detection of adherent bacteria. For investigation of acid protective properties, three subjects rinsed for 10min with Inula viscosa tea after 1min pellicle formation and kept the splints intraorally for further 19min. Physiological 30-min pellicles and native enamel samples served as controls. After HCl incubation of the samples ex-vivo over 120s (pH 2.0, 2.3, 3.0) calcium- and phosphate release were quantified photometrically. Potential influences on the pellicle's ultrastructure by Inula viscosa tea were evaluated by transmission electron microscopy (TEM). RESULTS: Application of Inula viscosa tea yielded a significant reduction of adherent bacteria on all enamel samples as detected by fluorescence microscopy. For calcium- and phosphate release no significant effect was recorded. TEM investigation indicated a modification of the pellicle's ultrastructure, but no enhanced protection against erosive noxae. CONCLUSION: Rinsing with Inula viscosa tea influences the bacterial colonization on enamel in situ over 8h but has no impact on acid protective properties of the pellicle.

Enzymes in the in-situ pellicle of children with different caries activity.

The present study investigated, for the first time, enzymes in the in-situ pellicle of children. Furthermore, it was purposed to detect glucosyltransferase (GTF) isoforms in each child's pellicle. Twenty-four children (5-9 yr of age) participated in the study. Twelve were caries free with no decayed, missing, and filled teeth (dmft), whereas 12 had active caries (dmft ≥ 2, indicating at least two untreated carious lesions). Bovine enamel slabs, fixed on individual upper jaw splints, were utilized for pellicle formation in situ. After 3 and 30 min, samples were tested for amylase, lysozyme, and peroxidase activities; total GTF activity was examined only in the 30-min pellicle. Gold-immunolabelling was used to quantify the GTF B, C, and D isoforms in the pellicle by transmission electron microscopy (TEM). All enzymes tested were detected in the children's in-situ pellicle in an active conformation, and there were no significant differences in their levels of activity between caries-free and caries-active children. All GTF isoforms were found to be randomly distributed within all pellicle layers, althoug GTF B was only detected very sporadically. A significantly higher amount of GTF D was detected in the pellicle of caries-active children. Pellicle formation in children is characterized by uniformity and selectivity. Glucosyltransferase D might represent a possible biomarker for high caries risk in children.

Double trouble: does co-morbid chronic somatic illness increase risk for recurrence in depression? A systematic review.

OBJECTIVE: To perform a systematic review, and if possible a meta-analysis, to establish whether depressed patients with co-morbid chronic somatic illnesses are a high risk "double trouble" group for depressive recurrence. METHOD: The databases PubMed, EMbase and PsycINFO were systematically searched until the 4(th) of December 2012 by using MeSH and free text terms. Additionally, reference lists of retrieved publications and treatment guidelines were reviewed, and experts were consulted. Inclusion criteria were: depression had to be measured at least twice during the study with qualified instruments and the chronic somatic illness had to be assessed by self-report or by a medical professional. Information on depressive recurrence was extracted and additionally risk ratios of recurrence were calculated. RESULTS: The search generated four articles that fulfilled our inclusion criteria. These studies showed no differences in recurrence over one- two- three- and 6.5 years of follow-up for a total of 2010 depressed patients of which 694 patients with a co-morbid chronic somatic illness versus 1316 patients without (Study 1: RR = 0.49, 95% CI, 0.17-1.41 at one year follow-up and RR = 1.37, 95% CI, 0.78-2.41 at two year follow-up; Study 2: RR = 0.94, 95% CI, 0.65-1.36 at two year follow-up; Study 3: RR = 1.15, 95% CI, 0.40-3.27 at one year follow-up; RR = 1.07, 95% CI, 0.48-2.42 at two year follow-up and RR = 0.99, 95% CI,0.55-1.77 at 6.5 years follow-up; Study 4: RR = 1.16, 95% CI, 0.86-1.57 at three year follow-up). CONCLUSION: We found no association between a heightened risk for depressive recurrence and co-morbid chronic somatic illnesses. There is a need for more longitudinal studies to justify the current specific treatment advice such as long-term pharmacological maintenance treatment for this presumed "double trouble" group.

Protein adhesion on dental surfaces-a combined surface analytical approach.

Protein adsorption is a field of huge interest in a number of application fields. Information on protein adhesion is accessible by a variety of methods. However, the results obtained are significantly influenced by the applied technique. The objective of this work was to understand the role of adhesion forces (obtained by scanning force spectroscopy, SFS) in the process of protein adsorption and desorption. In SFS, the protein is forced to and retracted from the surface, even under unfavorable conditions, in contrast to the natural situation. Furthermore, adhesion forces are correlated with adhesion energies, neglecting the entropic part in the Gibbs enthalpy. In this context, dynamic contact angle (DCA) measurements were performed to identify the potential of this method to complement SFS data. In DCA measurements, the protein diffuses voluntarily to the surface and information on surface coverage and reversibility of adsorption is obtained, including entropic effects (conformational changes and hydrophobic effect). It could be shown that the surface coverage (by DCA) of bovine serum albumin on dental materials correlates well with the adhesion forces (by SFS) if no hydrophobic surface is involved. On those, the entropic hydrophobic effect plays a major role. As a second task, the reversibility of the protein adsorption, i.e., the voluntary desorption as studied by DCA, was compared to the adhesion forces. Here, a correlation between low adhesion forces and good reversibility could be found as long as no covalent bonds were involved. The comparative study of DCA and SFS, thus, leads to a more detailed picture of the complete adsorption/desorption cycle.

Targeted immobilisation of lysozyme in the enamel pellicle from different solutions.

Mouthwashes containing protective enzymes are required especially for patients suffering from xerostomia. The present study aimed to investigate the possibilities of modulating the immobilisation of lysozyme in the in situ pellicle layer. In situ formed pellicles were incubated in vitro for 10 min with various enzymatic buffer solutions containing lysozyme and additive enzymes such as transglutaminase or trypsin as well as polyphenolic compounds (cistus tea). After the rinses, the pellicle samples were incubated in collected whole saliva or in desorption solutions for 0, 20 and 40 min and the enzyme activities were measured. Furthermore, accumulation of lysozyme in the pellicle was visualised in ultrathin sections of the pellicle using the gold immunolabelling technique and transmission electron microscopy. Hen egg white lysozyme was accumulated in the in situ pellicle tenaciously. Up to 2.8-fold higher activities than in controls were observed. The addition of transglutaminase did not enhance the immobilisation of lysozyme activity, whereas the polyphenolic compound had no adverse effect. Accumulation of lysozyme in the acquired pellicle was confirmed by gold immunolabelling. Targeted and tenacious immobilisation of lysozyme in the acquired pellicle is possible. Poylphenolic compounds might be a relevant additive for mouthwashes containing lysozyme.

Visualization of initial bacterial colonization on dentine and enamel in situ.

Bacterial colonization of dentine is of high relevance in cariology, endodontology and periodontology. The aim of the present in situ study was to establish recent methods for visualization and quantification of initial bacterial adherence to dentine in comparison to enamel. For this purpose, bovine enamel and dentine slabs were fixed on buccal sites of individual upper jaw splints worn by 6 subjects for 30min, 120min and 360min, respectively. Adherent bacteria on the slabs were visualized and quantified with DAPI-staining (4',6-diamidino-2-phenylindole) and fluorescence in situ hybridization (FISH) of streptococci and eubacteria using the CLSM (confocal laser scanning microscopy) as well as an epifluorescence microscope. In addition, the number of colony forming units was quantified after desorption. Representative samples were processed for SEM (scanning electron microscopy) and TEM (transmission electron microscopy). All methods clearly indicated that a significantly higher number of bacteria adhered to dentine than to enamel. Furthermore, the amount of bacteria on the dentine increased with increasing oral exposure time, but remained rather constant on the enamel. The CLSM allowed visualization of bacteria in the dentinal tubules. Bacteria were found preferentially at the openings of the dentine tubules, but were distributed randomly on the enamel. In conclusion, the adopted methods are suitable for visualization and quantification of bacterial adhesion to dentine. Even the initial bacterial colonization of dentine is much more pronounced than bacterial adherence to the enamel.

Initial bioadhesion on dental materials as a function of contact time, pH, surface wettability, and isoelectric point.

The adsorption of bovine serum albumin (BSA) on surfaces of dental enamel and of dental materials was investigated by scanning force spectroscopy. This method provides adhesion forces which can be measured as a function of contact time between protein and surface, pH, wettability, and isoelectric point of the surface. Whereas the chosen ceramic and composite materials resemble very well the adhesion on natural enamel, a much stronger adhesion was found for the more hydrophobic surfaces, that is, gold, titanium, poly(methyl methacrylate) (PMMA), and poly(tetrafluoroethylene) (PTFE). On hydrophilic surfaces, adhesion is mainly influenced by the electrostatic forces between protein and surface. However, the conformational change of BSA at pH values above pH 8 has to be taken into account. On the very hydrophobic PTFE surface, the special interface structure between PTFE and water plays an important role which governs BSA adhesion.

Detection and activity of peroxidase in the in situ formed enamel pellicle.

AIM: Peroxidase is the main salivary antioxidant. The aim of the present study was to detect and to characterise peroxidase in the in situ enamel pellicle. METHODS: Bovine enamel slabs were fixed on maxillary splints and carried by six subjects for different times (3, 30 and 120 min) on buccal and palatal sites. Pellicle bound peroxidase activity was determined fluorimetrically using 2',7'-dichlorofluorescin as a substrate. The peroxidase molecules present in the pellicle were visualised with the gold-immunolabelling technique and evaluated by TEM. Furthermore, effects of polyphenols and hydrogen peroxide on peroxidase and its enzymatic activity were examined. RESULTS: All pellicles which were tested revealed peroxidase activity and labelled peroxidase molecules were detected in all samples. The numbers of gold-labelled peroxidase molecules detectable in cross-sections of the pellicles were correlated significantly with the pellicle formation time. After 3 min, 0.50+/-1.01 labelled molecules were detected (30 min: 1.42+/-1.98; 120 min: 4.15+/-4.13, ANOVA, p<0.001). The mean immobilised peroxidase activity exposed at the surface amounted to 24.4+/-27.7 mU/cm2; no continuous increase of activity with formation time was found. Hydrogen peroxide and polyphenolic beverages inactivated peroxidase activity of the pellicle. Despite these inhibiting effects, considerable amounts of peroxidase molecules were still detectable by gold-immunolabelling. After contact with the inhibiting agents in situ, peroxidase activity of the pellicle reconstituted slowly. CONCLUSION: Peroxidase activity is present in the pellicle already after 3 min of formation time, but is inhibited by the substrate and polyphenolic beverages.

Effects of dental bleaching on micro- and nano-morphological alterations of the enamel surface.

PURPOSE: To investigate the effects of dental bleaching on the enamel surface micromorphology using SEM and TEM. METHODS: Fine-polished enamel slabs were randomly divided into eight groups (n = 3). Unbleached specimens served as control (1). The enamel slabs were bleached either with home Illuminé 15% for 8 hours per day, over 7 days (2), 14 days (3), 28 days (4), and 42 days (5) or with Whitestrips for 30 minutes each time, for 14 times (6), 28 times (7) and 42 times (8). The micromorphological surface pattern of the specimens was analyzed by SEM. In addition, two specimens per group (1, 2 and 6) were embedded and analyzed by TEM. RESULTS: SEM and TEM findings revealed that dental bleaching with carbamide peroxide or H2O2 over short periods of time (Groups 2, 6) caused nanomorphological alterations of the enamel surface, whereas prolonged exposure to the bleaching agents resulted in micromorphological changes of the enamel surface. Due to the bleaching process, the thickness of the enamel smear layer was significantly reduced.

Non-destructive visualisation of protective proteins in the in situ pellicle.

Several salivary anti-microbial and buffering components are part of the acquired in vivo pellicle. The purpose of the present in situ study was to visualise these proteins within the in situ formed pellicle and to investigate their distribution with respect to pellicle formation time and intra-oral localisation. Bovine enamel slabs were fixed on individual splints. They were carried by 6 subjects buccally and palatally in the region of the upper first molar teeth over 30 and 120 min, respectively, for in situ pellicle formation. After intra-oral exposure, enamel specimens were processed for transmission electron microscopy. Secretory immunoglobulin A (sIgA), lactoferrin, lysozyme, carbonic anhydrase (CA) I and II were visualised successfully in the in situ pellicle layer by gold immuno-labelling. All components were found to be distributed randomly within all layers of the pellicle. Significantly higher amounts of the proteins were detected after 120 min of formation time. Furthermore, significantly more labelled lactoferrin and lysozyme were found on buccal surfaces compared with palatal sites. For CA I, CA II and sIgA, no significant influence of the localisation was detected. All investigated anti-bacterial and buffering proteins are distributed randomly in the in situ formed pellicle layer and thus could contribute to its protective properties as an early defence barrier.

Protective effect of the in situ pellicle on dentin erosion - an ex vivo pilot study.

AIM: The acquired pellicle is well known as an anti-erosive proteinaceous layer on enamel, but its protective properties on dentin have not been investigated in detail until now. The aim of the present ex vivo study was to evaluate the erosive effects on pellicle coated dentin. METHODS: Bovine dentin slabs were exposed to the oral cavity of one subject for 120 min for in situ pellicle formation. Subsequently, the slabs were incubated with HCl (pH 2.3) in vitro for 5 min and erosive calcium-release was measured photometrically. In addition, the acid treated specimens were evaluated by transmission electron microscopy (TEM). Pellicle free samples served as controls. RESULTS: Calcium erosion from the pellicle coated dentin slabs amounted to 23.5+/-2.9 microg Ca/min (pellicle free samples: 32.2+/-4.2 microg Ca/min). The difference was statistically significant (p < or = 0.05). In pellicle coated as well as in uncoated dentin samples, TEM-evaluation showed a demineralised dentinal surface layer which thickness ranged between 3 and 6 microm. The pellicle itself was partially dissolved but not removed by hydrochloric acid treatment. CONCLUSION: The protective properties of the acquired pellicle against an erosive challenge of the dentinal surface are limited. The dentinal pellicle functions like an ion permeable network rather than a barrier.