Prevalence, incidence and distribution of erosion

There is some evidence that the presence of erosion is growing steadily. Because of different scoring systems, samples and examiners, it is difficult to compare and judge the outcome of the studies. Preschool children aged between 2 and 5 years showed erosion on deciduous teeth in 6-50% of the subjects. Young schoolchildren (aged 5-9) already had erosive lesions on permanent teeth in 14% of the cases. In the adolescent group (aged between 9 and 17) 11-100% of the young people examined showed signs of erosion. Incidence data (= increase of subjects with erosion) evaluated in three of these studies were 12% over 2 years, 18% over 5 years and 27% over 1.5 years. In adults (aged between 18 and 88), prevalence data ranged between 4 and 82%. Incidence data are scarce; only one study was found and this showed an incidence of 5% for the younger and 18% for the older examined group (= increase of tooth surfaces with erosion). Prevalence data indicated that males had somewhat more erosive tooth wear than females. The distribution of erosion showed a predominance of occlusal surfaces (especially mandibular first molars), followed by facial surfaces (anterior maxillary teeth). Oral erosion was frequently found on maxillary incisors and canines. Overall, prevalence data are not homogeneous. Nevertheless, there is already a trend for more pronounced rate of erosion in younger age groups. Therefore, it is important to detect at-risk patients early to initiate adequate preventive measures.

Accuracy of Preoperative Endoscopic Ultrasound (EUS) to Distinguish Between Early and Locally Advanced Esophageal Cancer in Daily Clinical Practice

Introduction: Preoperative chemoradiotherapy is generally recommended for locally advanced esophageal cancer (clinical stage T3 or T4 or nodal positive disease) but not for early cancer (clinical stage T0 to T2, N0). EUS has been described as the most accurate method to distinguish between early and locally advanced stage in several studies. Recently however, the high accuracy of EUS (90% or higher) was questioned by some investigators. This raises the issue whether the results of studies focused on EUS accuracy may be directly translated into daily clinical practice. Aim & Methods: The aim of this retrospective analysis was to assess the accuracy of preoperative EUS to distinguish between early and locally advanced esophageal cancer in daily clinical practice outside a study setting. EUS was performed by several investigators, including trainees in one university hospital. For this purpose, EUS reports and patient files (medical and surgical) including histological reports of 300 consecutive pts with esophageal tumors were reviewed. In pts with adenocarcinoma or squamous cell cancer and surgical resection without previous radio-/chemotherapy, EUS tumor staging was compared with histological diagnosis. Results: Out of the 300 consecutive pts with esophageal tumor and EUS 102 pts had esophageal surgery after EUS-staging without any radio-/chemotherapy. In 93 pts oesophageal cancer was confirmed, whereas 9 had other tumors. The mean age was 65 years (range 27-89), sex ratio female:male was 1:3.2. To distinguish between early and late tumor stage, the accuracy was 85%. The sensitivity and specificity for early cancer was 59%, and 93%, respectively. The diagnostic accuracy for local tumor spread was 90%, 90%, 68%, 69%, 89% for pT0, pT1, pT2, pT3 and pT4 lesions, respectively. The overall accuracy for T-stage was 74%. For pN-positive staging the accuracy of EUS was 73%. Conclusion: In daily clinical practice, the accuracy of EUS in assessing esophageal tumor staging is lower than in specific studies focusing on EUS accuracy. Mainly early esophageal cancer stages were overstaged. Thus, the implementation of recommendations for diagnostic work-up of esophageal cancer patients resulting from highly specific studies should consider the appropriate clinical setting.

Understanding the chemistry of dental erosion

The mineral in our teeth is composed of a calcium-deficient carbonated hydroxyapatite (Ca10-xNax(PO4)6-y(CO3)z(OH)2-uFu). These substitutions in the mineral crystal lattice, especially carbonate, renders tooth mineral more acid soluble than hydroxyapatite. During erosion by acid and/or chelators, these agents interact with the surface of the mineral crystals, but only after they diffuse through the plaque, the pellicle, and the protein/lipid coating of the individual crystals themselves. The effect of direct attack by the hydrogen ion is to combine with the carbonate and/or phosphate releasing all of the ions from that region of the crystal surface leading to direct surface etching. Acids such as citric acid have a more complex interaction. In water they exist as a mixture of hydrogen ions, acid anions (e.g. citrate) and undissociated acid molecules, with the amounts of each determined by the acid dissociation constant (pKa) and the pH of the solution. Above the effect of the hydrogen ion, the citrate ion can complex with calcium also removing it from the crystal surface and/or from saliva. Values of the strength of acid (pKa) and for the anion-calcium interaction and the mechanisms of interaction with the tooth mineral on the surface and underneath are described in detail.

Extrinsic causes of erosion. Biological factors

Biological factors such as saliva, acquired dental pellicle, tooth structure and positioning in relation to soft tissues and tongue are related to dental erosion development. Saliva has been shown to be the most important biological factor in the prevention of dental erosion. It starts acting even before the acid attack, with the increase of the salivary flow rate as a response to the acidic stimuli. This creates a favorable scenario, increasing the buffering system of saliva and effectively diluting and clearing acids on dental surfaces during the erosive challenge. Saliva plays a role in the formation of the acquired dental pellicle, which acts as a perm-selective membrane preventing contact of the acid with the tooth surf aces. The protective level of the pellicle seems to be regulated by its composition, thickness and maturation time. Due to its mineral content, saliva can also prevent demineralization as well as enhance remineralization. However, these preventive and reparative factors of saliva may not be enough against highly erosive challenges, leading to erosion development. The progress rate of erosion can be significantly influenced by the type of dental substrate, occurrence of mechanical and chemical attacks, fluoride exposure, and also by contact with the oral soft tissues and tongue.

Extrinsic causes of erosion. Oral hygiene products and acidic medicines

Acidic or EDTA-containing oral hygiene products and acidic medicines have the potential to soften dental hard tissues. The low pH of oral care products increases the chemical stability of some fluoride compounds, favors the incorporation of fluoride ions in the lattice of hydroxyapatite and the precipitation of calcium fluoride on the tooth surface. This layer has some protective effect against an erosive attack. However, when the pH is too low or when no fluoride is present these protecting effects are replaced by direct softening of the tooth surface. Xerostomia or oral dryness can occur as a consequence of medication such as tranquilizers, anti-histamines, anti-emetics and anti-parkinsonian medicaments or of salivary gland dysfunction e.g. due to radiotherapy of the oral cavity and the head and neck region. Above all, these patients should be aware of the potential demineralization effects of oral hygiene products with low pH and high titratable acids. Acetyl salicylic acid taken regularly in the form of multiple chewable tablets or in the form of headache powder as well chewing hydrochloric acids tablets for treatment of stomach disorders can cause erosion. There is most probably no direct association between asthmatic drugs and erosion on the population level. Consumers, patients and health professionals should be aware of the potential of tooth damage not only by oral hygiene products and salivary substitutes but also by chewable and effervescent tablets. Additionally, it can be assumed that patients suffering from xerostomia should be aware of the potential effects of oral hygiene products with low pH and high titratable acids.

Extrinsic causes of erosion. Behavioral factors

During and after an erosive challenge, behavioral factors play a role in modifying the extent of erosive tooth wear. The manner that dietary acids are introduced into the mouth (gulping, sipping, use of a straw) will affect how long the teeth are in contact with the erosive challenge. The frequency and duration of exposure to an erosive agent is of paramount importance. Night-time exposure (e.g. baby bottle-feeding) to erosive agents may be particularly destructive because of the absence of salivary flow. Health-conscious individuals tend to ingest acidic drinks and juices more frequently and tend to have higher than average oral hygiene. While good oral hygiene is of proven value in the prevention of periodontal disease and dental caries, frequent toothbrushing with abrasive oral hygiene products may enhance erosive tooth wear. Unhealthy lifestyles such as consumption of designer drugs, alcopops and alcohol abuse are other important behavioral factors.

Spatial Assessment of Erosion and its Impact on Soil Fertility in the Tajik Foothills

Efficient planning of soil conservation measures requires, first, to understand the impact of soil erosion on soil fertility with regard to local land cover classes; and second, to identify hot spots of soil erosion and bright spots of soil conservation in a spatially explicit manner. Soil organic carbon (SOC) is an important indicator of soil fertility. The aim of this study was to conduct a spatial assessment of erosion and its impact on SOC for specific land cover classes. Input data consisted of extensive ground truth, a digital elevation model and Landsat 7 imagery from two different seasons. Soil spectral reflectance readings were taken from soil samples in the laboratory and calibrated with results of SOC chemical analysis using regression tree modelling. The resulting model statistics for soil degradation assessments are promising (R2=0.71, RMSEV=0.32). Since the area includes rugged terrain and small agricultural plots, the decision tree models allowed mapping of land cover classes, soil erosion incidence and SOC content classes at an acceptable level of accuracy for preliminary studies. The various datasets were linked in the hot-bright spot matrix, which was developed to combine soil erosion incidence information and SOC content levels (for uniform land cover classes) in a scatter plot. The quarters of the plot show different stages of degradation, from well conserved land to hot spots of soil degradation. The approach helps to gain a better understanding of the impact of soil erosion on soil fertility and to identify hot and bright spots in a spatially explicit manner. The results show distinctly lower SOC content levels on large parts of the test areas, where annual crop cultivation was dominant in the 1990s and where cultivation has now been abandoned. On the other hand, there are strong indications that afforestations and fruit orchards established in the 1980s have been successful in conserving soil resources.

Thermodilution and esophageal Doppler ultrasound in the assessment of blood flow changes induced by endotoxin and dobutamine

BACKGROUND: Intermittent (IT) and continuous (CT) thermodilution and esophageal Doppler (ED), are all used for hemodynamic monitoring. The aim of this study was to test the agreement between these methods during endotoxin (ET) and dobutamine infusion. METHODS: Twenty-two pigs (39 +/- 1.8 kg body weight) were randomized to general anesthesia and either continuous ET (n = 9) or placebo (PL, n = 13) infusion. After 18 hours of ET or PL infusion, the animals were further randomized to receive dobutamine (n = 3 in ET, n = 5 in PL) or PL. A set of measurements using the three methods were obtained every hour, and the relative blood flow changes between two subsequent measurements were calculated. RESULTS: Bias or limits of agreement for flows were 0.73 L/min or 1.80 L/min for IT and CT, -0.33 L/min or 4.29 L/min for IT and ED, and -1.06 or 3.94 for CT and ED (n = 515, each). For flow changes they were 1% or 44%, 2% or 59%, and 3% or 45%, respectively. Bias and limits of agreement did not differ in ET- and PL-treated animals or in animals with or without dobutamine. Despite significant correlation between any two methods, the respective correlation coefficients (r) were small (IT vs. CT: 0.452; IT vs. ED: 0.042; CT vs. ED: 0.069; all p < 0.001). The same directional changes were measured by any two methods in 49%, 40%, and 50%. When IT flows >5 L/min were compared with IT flows 5 L/min.

Erosion--diagnosis and risk factors

Dental erosion is a multifactorial condition: The interplay of chemical, biological and behavioural factors is crucial and helps explain why some individuals exhibit more erosion than others. The erosive potential of erosive agents like acidic drinks or foodstuffs depends on chemical factors, e.g. pH, titratable acidity, mineral content, clearance on tooth surface and on its calcium-chelation properties. Biological factors such as saliva, acquired pellicle, tooth structure and positioning in relation to soft tissues and tongue are related to the pathogenesis of dental erosion. Furthermore, behavioural factors like eating and drinking habits, regular exercise with dehydration and decrease of salivary flow, excessive oral hygiene and, on the other side, an unhealthy lifestyle, e.g. chronic alcoholism, are predisposing factors for dental erosion. There is some evidence that dental erosion is growing steadily. To prevent further progression, it is important to detect this condition as early as possible. Dentists have to know the clinical appearance and possible signs of progression of erosive lesions and their causes such that adequate preventive and, if necessary, therapeutic measures can be initiated. The clinical examination has to be done systematically, and a comprehensive case history should be undertaken such that all risk factors will be revealed.

Current erosion indices--flawed or valid? Summary

The problem of erosive tooth wear appears increasingly to be encountered by clinicians and researchers. An adequate way of defining and recording erosive tooth wear is essential in order to assess the extent of this clinical phenomenon, both on an individual level and in the population, and for the adequate provision of preventive and therapeutic measures. Well-established erosion indices have been used in most of these studies, although in many cases modifications have been made to suit the different research aims. This use of different indices is one reason why it still cannot be claimed that there is enough current knowledge on this clinical phenomenon. This article summarises the proceedings of a workshop to discuss the topic of dental erosion indices. The result of the workshop is the proposal for a new scoring system (Basic Erosive Wear Examination, BEWE) designed for use both within the research field and for dental clinicians, with the aims of standardising assessment of erosion for international comparisons, raising awareness and providing guidelines for treatment of erosive tooth wear in dental practice.