[Research on salivary proteins: from properties to functions]. / Onderzoek naar speekseleiwitten: van eigenschappen naar functies.

Saliva does more than merely contribute to the digestion of food. It is essential to the health of the oral cavity and with that, indirectly, of the entire body. In the 1970s and 1980s, the most important proteins and peptides in saliva were identified and characterised. For example, mucins MUC5B and MUC7, proline-rich proteins, cystatins and histatins are now known to the level of the amino acid sequence and molecular structure. The associated physical properties indicate how these proteins carry out their protective function. Sometimes, however, this information can mislead science because the relationship between property and function is not necessarily unambiguous. In addition, unexpected properties are sometimes discovered compelling scientists to re-evaluate critically the transition from physical property to physiological function. In certain cases, this has led to perceiving the (possible) function of these proteins in a completely different light.

Effects of environmental temperature on saliva flow rate and secretion of protein, amylase and mucin 5B.

OBJECTIVE: The aim of this study is to evaluate the short term effects of environmental temperature on saliva flow rate and composition. METHODS: In a cross-over study design 20 subjects (18-25 years old, 14 women, 6 men) were exposed in randomized order at different days to three temperatures (4 °C, 21 °C and 37 °C). Five minutes after a subject was exposed to the test temperature, collection of resting saliva was started for 5 min at the same temperature. Saliva flow rate, pH, viscosity, protein concentration, mucin 5B concentration and amylase activity were measured. RESULTS: Exposure to 4 °C resulted in an increase of the saliva flow rate (p < 0.01), protein output and amylase output (p < 0.001) compared to exposure to 21 °C or 37 °C. Although the figures for mucin 5B output at 4 °C were higher than at higher temperatures, this was not significant. There were no significant differences in the salivary mucin 5B concentration and viscosity between saliva samples collected at the indicated temperatures. CONCLUSIONS: Lowering of the temperature induces an increase in saliva flow rate, as well as protein and amylase output.

Histatin 1 Enhances Cell Adhesion to Titanium in an Implant Integration Model.

Cellular adhesion is essential for successful integration of dental implants. Rapid soft tissue integration is important to create a seal around the implant and prevent infections, which commonly cause implant failure and can result in bone loss. In addition, soft tissue management is important to obtain good dental aesthetics. We previously demonstrated that the salivary peptide histatin 1 (Hst1) causes a more than 2-fold increase in the ability of human adherent cells to attach and spread on a glass surface. Cells treated with Hst1 attached more rapidly and firmly to the substrate and to each other. In the current study, we examine the potential application of Hst1 for promotion of dental implant integration. Our results show that Hst1 enhances the attachment and spreading of soft tissue cell types (oral epithelial cells and fibroblasts) to titanium (Ti) and hydroxyapatite (HAP), biomaterials that have found wide applications as implant material in dentistry and orthopedics. For improved visualization of cell adhesion to Ti, we developed a novel technique that uses sputtering to deposit a thin, transparent layer of Ti onto glass slides. This approach allows detailed, high-resolution analysis of cell adherence to Ti in real time. Furthermore, our results suggest that Hst1 has no negative effects on cell survival. Given its natural occurrence in the oral cavity, Hst1 could be an attractive agent for clinical application. Importantly, even though Hst1 is specific for saliva of humans and higher primates, it stimulated the attachment and spreading of canine cells, paving the way for preclinical studies in canine models.

Salivary stones: symptoms, aetiology, biochemical composition and treatment.

Salivary stones, also known as sialoliths, are calcified concrements in the salivary glands. Sialoliths are more frequently located in the submandibular gland (84%), than in the parotid gland (13%). The majority of the submandibular stones are located in Wharton's duct (90%), whereas parotid stones are more often located in the gland itself. Salivary stones consist of an amorphous mineralised nucleus, surrounded by concentric laminated layers of organic and inorganic substances. The organic components of salivary stones include collagen, glycoproteins, amino acids and carbohydrates. The major inorganic components are hydroxyapatite, carbonate apatite, whitlockite and brushite. The management of salivary stones is focused on removing the salivary stones and preservation of salivary gland function which depends on the size and location of the stone. Conservative management of salivary stones consists of salivary gland massage and the use of sialogogues. Other therapeutic options include removal of the stone or in some cases surgical removal of the whole salivary gland.

Bacillus globigii cell size is influenced by variants of the quorum sensing peptide extracellular death factor.

Toxin-antitoxin modules are necessary for the mode of action of several antibiotics. One of the most studied toxin-antitoxin modules is the quorum sensing-dependent MazEF system in Escherichia coli. The quorum sensing factor in this system is called the extracellular death factor (EDF), a linear pentapeptide with the sequence NNWNN. In spite of the extensive research on the mazEF system and the involvement of the quorum sensing factor EDF, the effect of EDF itself on bacteria has not yet been studied. In this research, we determined the effect of EDF and variants on cell growth in the Gram-negative bacterium E. coli and the Gram-positive Bacillus globigii. By aligning the zwf gene (from where EDF originates) of different bacterial species, we found 27 new theoretical variants of the peptide. By evaluating growth curves and light microscopy we found that three EDF variants reduced bacterial cell size in B. globigii, but not in E. coli. The D-peptides did not affect cell size, indicating that the effect is stereospecific. Peptides wherein tryptophan was substituted by alanine also did not affect cell size, which indicates that the effect seen is mediated by an intracellular target.

[Salivary stones: aetiology, composition and treatment]. / Speekselstenen: etiologie, samenstelling en behandeling.

Salivary stones or sialoliths, are calcified concrements which are most frequently located in the submandibular glands and their ducts. Their size and weight show considerable variation. The aetiology is unknown. It has been suggested that salivary stones could be related to an altered saliva composition, the anatomy of the ducts of the salivary gland and/or the fusion of microsialoliths. Salivary stones consist mainly of anorganic material such as hydroxyapatite, whitlockite and calciumphosphate, but they also contain organic components such as proteins and lipids. Treatment can consist of salivary gland massage combined with an acid diet, ultrasonic pulverisation, and surgical or sialendoscopical removal.

[Dextrorotary protease substrates could be suitable for oral microbiological diagnostics]. / Rechtsdraaiende proteasesubstraten lijken bruikbaar voor orale microbiologische diagnostiek.

The currently available methods for the identification of micro-organisms in a clinical sample are time consuming, complex or lack sensitivity and specificity. Consequently, no tests are available for rapid microbiological diagnostics in dental clinics so far. Based on the fact that bacteria posess unique enzymes for processing dextrorotary amino acids, a rapid method has been developed to detect metabolically active bacteria. Using dextrorotary amino acid containing substrates, Porphyromonas gingivalis could be detected in clinical samples with a specificity of 96-100% within 10 minutes. This new method opens the door for the development of a rapid oral diagnostic microbiological test.

Dental erosion in the 21st century: what is happening to nutritional habits and lifestyle in our society?

Several developments in Western Europe may have contributed to the increased prevalence of dental erosion during the last decades. Exposing children to sour taste at an early age increases the preference for acidic food and drinks later in life. Acidic fruits and beverages became widely available due to economic prosperity. New types of acidic candies were developed, some of which are kept in the mouth for very long times. Children are exposed to intense marketing of these acidic products, which are widely available in supermarkets and school canteens. In the meantime, much less attention has been paid to the development and marketing of less erosive food products.

Comparing culture, real-time PCR and fluorescence resonance energy transfer technology for detection of Porphyromonas gingivalis in patients with or without peri-implant infections.

BACKGROUND AND OBJECTIVE: The aim of the study was to compare the detection of Porphyromonas gingivalis using a fluorescence resonance energy transfer (FRET) technology with commonly used diagnostic methods in salivary and subgingival plaque samples from subjects with dental implants. P. gingivalis was considered as a marker for a pathogenic microbiota. MATERIAL AND METHODS: Ninety-seven adult subjects were recruited, including periodontally healthy controls with no dental implants, implant controls with no peri-implant disease and patients with peri-implant disease. Saliva and subgingival/submucosal plaque samples were collected from all subjects and were analyzed using culture, real-time PCR and FRET technology employing P. gingivalis-specific substrates. RESULTS: It was found that the P. gingivalis-specific substrates were highly suitable for detecting the presence of P. gingivalis in saliva and in subgingival plaque samples, showing comparable specificity to culture and real-time PCR. CONCLUSION: We applied the FRET technology to detect P. gingivalis in implant patients with or without an implant condition and in controls without implants. The technique seems suitable for detection of P. gingivalis in both plaque and saliva samples. However, with all three techniques, P. gingivalis was not very specific for peri-implantitis cases. Future work includes fine-tuning the FRET technology and also includes the development of a chair-side application.

[Risks associated with erosive beverages in secondary school canteens in the Netherlands]. / Risico van erosie door dranken in schoolkantines.

The consumption of acidic beverages may cause dental erosion. The consumption of such beverages during school hours may contribute to the development of erosion. In order to study the extent to which children of secondary schools are exposed to potentially erosive beverages, 43 locations in 37 schools in the Netherlands were visited. In each school, all available types of beverages were registered and classified as non-erosive or potentially erosive. In addition, the number of students, type of school, opening times of the canteens and the number of vending machines were recorded. It was revealed that a wide variety of beverages is available in school canteens, of which a large number are potentially erosive (71.8 +/- 12.9%). The number of different products available, the number of different beverages available and the number of potentially erosive drinks all correlated with the number of students per school, but not with the type of education. The number of drinks available and the number of potentially erosive drinks correlated with the opening hours of the canteens and the number of vending machines.

[Unhealthy weight loss. Erosion by apple cider vinegar]. / Ongezond afslanken. Erosie door appelazijn.

Erosive tooth wear was diagnosed in the dentition of a 15-year-old girl with a Moroccan background. After an anamnesis, extensive analysis of possible risk factors and a study of the pattern of erosion, it was concluded that the erosive tooth wear was induced by daily consumption of a glass of apple cider vinegar Further investigation revealed that in North-African culture, women have used apple cider vinegar to achieve weight loss for generations. Bodybuilders are also known to make use of this method of weight reduction.

[Saliva and wound healing]. / Speeksel en wondgenezing.

The oral mucosa is frequently exposed to mechanical forces, which may result in tissue damage. Saliva contributes to the repair of the oral mucosa in several ways. In the first place, it creates a humid environment to improve the function of inflammatory cells. During the last few years, it has been shown that saliva also contains a large number of proteins with a role in wound healing. Saliva contains growth factors, especially Epidermal Growth FACTOR, which promotes the proliferation of epithelial cells. Trefoil factor 3 and histatin promote the process of wound closure. The importance of Secretory Leucocyte Protease Inhibitor is demonstrated by the fact that in the absence of this salivary protein, oral wound healing is considerably delayed. Understanding these salivary proteins opens the way for the development of new wound healing medications.

The erosive potential of jawbreakers, a type of hard candy.

OBJECTIVES: To explore the consumption pattern of a specific type of acidic solid candy, the so-called jawbreakers, by primary school children and determine the erosive potential of this type of candy in vivo. METHODS: A questionnaire about jawbreaker consumption was distributed among 10-12 year-old-children (n = 302). Subsequently, 19 healthy volunteers tested four different jawbreakers in vivo. Whole saliva was collected 5 min before, 3 min during and 11 min after consumption. Salivary flow rate and pH were determined. RESULTS: Two-thirds of the children reported a history of jawbreaker consumption, 18% during the last week. More than half of the children estimated their average time for consumption of one jawbreaker to be more than 15 min. In vivo, the jawbreakers induced 8.6-13.9-fold increase in salivary flow rate. Sucking on sour, jumbo and strawberry jawbreakers induced a drop in salivary pH to values below pH 5.5. During consumption of fireball jawbreakers, the intra-oral pH hardly changed. CONCLUSIONS: Jawbreakers are frequently used by children, who keep this candy in their mouth for a long time. Jawbreakers differ considerable in erosive potential, with sour and jumbo jawbreakers > strawberry jawbreaker >> fireball jawbreaker. This information is of use for dental hygienists counselling juvenile patients with dental erosion.

[Heroin and oral health]. / Heroïnegebruik en mondgezondheid.

Heroin is a half synthetic opiate with. It is used by a relatively small number of the general population, but relatively frequently by homeless people and prisoners. Since heroin has an inhibitory effect on the nervous system and on breathing, an overdose of heroin can have fatal consequences. Sudden abstinence of heroin results in general discomfort, restlessness, muscle cramps, perspiration, nausea, shivers and goose bumps. Oral effects of heroin include increased risks of caries, periodontitis and bruxism. Saliva has the potential of detecting heroin abuse.

Histatins enhance wound closure with oral and non-oral cells.

The role of human saliva in oral wound-healing has never been fully elucidated. We previously demonstrated that parotid-salivary histatins enhance in vitro wound closure. The question remains whether other salivary-gland secretions enhance wound closure, and also the effects of histatins on primary and non-oral cells. Since the presence of histatins is not limited to parotid saliva, we expected to observe wound-closure activity of other salivary-gland secretions. However, here we show that non-parotid saliva does not stimulate wound closure, most probably due to the presence of mucins, since the addition of MUC5B to parotid saliva abolished its effect. Furthermore, we found that histatins stimulated wound closure of (primary) cells of both oral and non-oral origin. This suggests that the cellular receptor of histatins is widely expressed and not confined to cells derived from the oral cavity. These findings encourage the future therapeutic application of histatins in the treatment of all kinds of wounds.

The effects of saliva on the erosive potential of three different wines.

BACKGROUND: The erosive potential of wine on teeth may be modified by the buffering capacity of saliva. This potential effect was studied for three different wines in vitro and in vivo. METHODS: The buffering capacity was studied in vitro by stepwise addition of small volumes of a dry white wine, a medium sweet white wine and a red wine to collected stimulated saliva. In vivo, this was studied by six volunteers vigorously rinsing 5 mL of each wine in their mouth for 15 to 45 seconds. Changes in salivary flow rate and pH were measured during a period of 10 minutes after rinsing with 5 mL wine. RESULTS: pH values < 5.5 were observed in vitro after addition of 0.2 mL dry white wine and medium sweet wine and after 0.3 mL red wine to 1 mL saliva. During rinsing with all wines, the intra-oral pH decreased to below 4 within 15 seconds and remained below this value for at least 45 seconds. After expectoration, the salivary pH remained significantly low for two to six minutes, despite a doubling of the flow rate observed during the first two minutes. CONCLUSIONS: Vigorously rinsing wine induced a decrease in intra-oral pH of significant degree and duration, which increases the risk of developing dental erosion.

The erosive potential of lollipops.

AIM: To determine the erosive potential of several commercially available lollipops and the protective effect of saliva. METHODS: The erosive potential of lollipops was determined in vitro by measuring the pH and neutralisable acidity. Subsequently, 10 healthy volunteers tested different types of lollipops. Whole saliva was collected 5 minutes before, 15 minutes during and 10 minutes after consumption. Salivary flow rate and pH were determined. RESULTS: Fruit flavoured and cola flavoured lollipops have a very low pH (2.3 - 2.4). Yogurt-containing and salmiak (salty liquorice) flavoured lollipops have much higher pH values (3.8-4.7). The neutralisable acidity of 1g of lollipop showed a large variation from < 200 microl to > 1700 microl 0.1 M NaOH. In vivo, lollipops induced 2.5 to 4.7-fold increase in salivary flow rate with a concomitant drop in salivary pH. For fruit flavoured and cola flavoured lollipops the salivary pH dropped below pH 5.5. For strawberry yogurt and salmiak lollipops, the salivary pH remained above this critical value. The volunteers did not report significant differences in preferences for the lollipops. CONCLUSIONS: Lollipops differ considerable in erosive potential, with fruit flavoured and cola flavoured lollipops having the highest risk for inducing dental erosion. This information is of use for clinicians counselling juvenile patients with dental erosion.

[Influence of sports on saliva]. / Invloed van sport op speeksel.

Physical exertion, such as practicing sports, may have an influence on the secretion and composition of saliva. As a result of intensive physical exertion, the saliva immunoglobulin concentration decreases and the concentration of protein--the output of protein (mg/min), however, remains constant--and the viscosity of the saliva increase, while the watery secretion decreases. Moreover, saliva testosterone levels decrease and salivary cortisol levels increase. The saliva Na+, K+, Ca2+ and PO4(3-) concentrations increase slightly or remain unchanged. After a single physical exertion, the alterations are reversible and the values return to baseline within a few hours. In the case of long lasting intensive physical exertions, for instance lasting several months, particularly the decrease in the concentration of the most prevalent immunoglobulins in saliva (s-IgA) seems to have a more permanent character. This has a detrimental effect on the immunological defence, which may reduce oral as well as upper respiratory tract health. Complaints about this are not uncommon among serious athletes who are active at a high competitive level. Among these athletes, the combination of changes in the composition and secretion of saliva, together with intense mouth-breathing and an adjusted diet and drinking habits carry a higher risk of developing caries and erosion. However, in case of decent oral health selfcare, the detrimental effects on oral health can be prevented.

Acute effects of hemodialysis on salivary flow rate and composition.

AIMS: To evaluate acute effects of hemodialysis (HD) on the salivary flow rate, pH and biochemical composition before, during and after completion of a dialysis session. MATERIAL AND METHODS: Unstimulated whole saliva (UWS) and chewing-stimulated whole saliva (CH-SWS) were collected in 94 HD patients. Salivary flow rate, pH, concentrations of total protein, albumin, cystatin C, secretory immunoglobulin A (S-IgA) and of sodium, potassium and urea were measured. RESULTS: HD had an acute stimulating effect on the salivary flow rate (UWSbefore = 0.30+/-0.22 ml/min, UWSduring = 0.39+/-0.25 ml/min, p < 0.005). The mean pH of UWS showed a small but significant increase during HD mainly due to an increased watery secretion from the salivary glands. The salivary biochemical constituents changed markedly, but no significant difference in output was found. The electrolyte concentration did not change significantly during dialysis. The level of urea in CH-SWS declined to 40% (Ureabefore = 25.+/-6.4 mmol/l, Ureaduring = 15.3+/-4.5 mmol/1). CONCLUSIONS: This study shows that HD has significant acute effects on both salivary secretion rate and protein concentrations in saliva. We conclude that the observed changes in salivary concentrations and proteins are mainly due to an increased watery secretion from the salivary glands.