The role of the diet in tooth wear.

An acidic diet has been associated with erosive tooth wear. However, some people who consume dietary acids develop erosive tooth wear and some do not. This review paper provides an overview of the risk factors of dietary acid consumption which increase the likelihood of developing severe erosive tooth wear. Increased frequency of dietary acid consumption, particularly between meals appears to be the predominant risk factor. However, habitually drinking acidic drinks by sipping them slowly or swishing, rinsing or holding acidic drinks in the mouth before swallowing will also increase risk of progression. Consuming fruit over long time periods at a single sitting and dietary acids being served at increased temperatures have also been implicated. Additions of fruit or fruit flavourings to drinks and regular consumption of vinegars, pickles, acidic medications or acidic sugar-free sweets are potential hidden risk factors that should be discussed with patients at risk of erosive tooth wear progression. Behaviour change is difficult to achieve but specific, targeted behavioural interventions and offering alternatives may increase success.

Precision of 655nm Confocal Laser Profilometry for 3D surface texture characterisation of natural human enamel undergoing dietary acid mediated erosive wear.

OBJECTIVES: To assess the precision of optical profilometry for characterising the 3D surface roughness of natural and polished human enamel in order to reliably quantify acid mediated surface roughness changes in human enamel. METHODS: Forty-two enamel samples were prepared from extracted human molars and either polished flat or left unmodified. To investigate precision, the variability of thirty repeated measurements of five areas of one polished and one natural enamel sample was assessed using 655nm Confocal Laser Profilometry. Remaining samples were subjected to forty-five minutes orange juice erosion and microstructural changes were analysed using Sa roughness change (µm) and qualitatively using surface/subsurface confocal microscopy. RESULTS: Enamel surface profilometry from the selected areas revealed maximal precision of 5nm for polished enamel and 23nm for natural enamel. After erosion, the polished enamel revealed a 48% increase in mean (SD) Sa roughness of 0.10 (0.07)µm (P<0.05), whereas in contrast the natural enamel revealed a 45% decrease in mean (SD) roughness of -0.32 (0.42)µm (P<0.05). These data were supported by qualitative confocal images of the surface/subsurface enamel. SIGNIFICANCE: This study demonstrates a method for precise surface texture measurement of natural human enamel. Measurement precision was superior for polished flat enamel in contrast to natural enamel however, natural enamel responds very differently to polished enamel when exposed to erosion challenges. Therefore, thus future studies characterising enamel surface changes following erosion on natural enamel may provide more clinically relevant responses in comparison to polished enamel.

Measurement uncertainty associated with chromatic confocal profilometry for 3D surface texture characterization of natural human enamel.

OBJECTIVE: To investigate the measurement performance of a chromatic confocal profilometer for quantification of surface texture of natural human enamel in vitro. METHODS: Contributions to the measurement uncertainty from all potential sources of measurement error using a chromatic confocal profilometer and surface metrology software were quantified using a series of surface metrology calibration artifacts and pre-worn enamel samples. The 3D surface texture analysis protocol was optimized across 0.04mm2 of natural and unpolished enamel undergoing dietary acid erosion (pH 3.2, titratable acidity 41.3mmolOH/L). RESULTS: Flatness deviations due to the x, y stage mechanical movement were the major contribution to the measurement uncertainty; with maximum Sz flatness errors of 0.49µm. Whereas measurement noise; non-linearity's in x, y, z and enamel sample dimensional instability contributed minimal errors. The measurement errors were propagated into an uncertainty budget following a Type B uncertainty evaluation in order to calculate the Standard Combined Uncertainty (uc), which was ±0.28µm. Statistically significant increases in the median (IQR) roughness (Sa) of the polished samples occurred after 15 (+0.17 (0.13)µm), 30 (+0.12 (0.09)µm) and 45 (+0.18 (0.15)µm) min of erosion (P<0.001 vs. baseline). In contrast, natural unpolished enamel samples revealed a statistically significant decrease in Sa roughness of -0.14 (0.34) µm only after 45min erosion (P<0.05s vs. baseline). SIGNIFICANCE: The main contribution to measurement uncertainty using chromatic confocal profilometry was from flatness deviations however by optimizing measurement protocols the profilometer successfully characterized surface texture changes in enamel from erosive wear in vitro.

Effects of tooth-brushing force with a desensitising dentifrice on dentine tubule patency and surface roughness.

OBJECTIVES: To investigate the effects of a 5% NovaMin containing dentifrice on dentine tubule patency and surface roughness at 100g and 400g tooth brush abrasion forces. METHODS: 75 polished human dentine samples were prepared and randomly allocated into one of five groups; control (1), Na2PFO3 100g abrasion force (2), NovaMin 100g (3), Na2PFO3 400g (4) and NovaMin 400g (5). The control group underwent two 2-min cycles of artificial saliva (AS), one 2-min erosion cycle; the rest underwent two toothbrush abrasion cycles in an AS/dentifrice slurry and one 2-min erosion cycle. All samples were imaged at baseline and post intervention using Tandem Scanning Microscopy and Profilometry to analyse tubule patency and roughness. RESULTS: Mean tubule patency increased significantly between baseline and post intervention in groups 1,2 and 4 and decreased significantly post intervention in groups 3 and 5 (p<0.01). Post intervention, there were statistically significant differences in mean patent tubules between NovaMin and the Na2PFO3 and control groups (p<0.001). Surface roughness increased for all groups between baseline and post interventions (P<0.001); mean (SD) roughness increases for groups 1, 2, 3, 4 and 5 were 0.14 (0.05) µm, 0.18 (0.04) µm, 0.16 (0.06) µm, 0.19 (0.07) µm and 0.21 (0.02) µm respectively. Differences between group 1 and 5 were significant (p<0.01). CONCLUSIONS: Brushing with NovaMin resulted in significant dentine tubule occlusion at 100g and 400g, but brushing with Na2PFO3 resulted in increased tubule patency. Surface roughness increased significantly at 400g brushing with NovaMin. There was no correlation between tubule patency and surface roughness. CLINICAL SIGNIFICANCE: A NovaMin desensitising dentifrice resulted in tubule occlusion even at high brushing forces. There was minimal increase in surface roughness at the lower (100g) brushing force.

Solitary fibrous tumour of the falciform ligament containing multiple foci of malignant transformation.

Solitary fibrous tumour is an uncommon soft tissue tumour initially described in the pleural cavity. In the past decade, it has been described in various extrapleural sites, including the abdomen. Traditionally regarded as benign, cases of histologically or clinically malignant solitary fibrous tumours are rare. This report describes such a case, although the patient is still disease free five years after excisional surgery, without adjuvant treatment. The acute clinical presentation may be related to malignant transformation occurring in a long standing solitary fibrous tumour.

Detection of replicative integrity in small colonic biopsies using the BrdUrd comet assay.

The alkaline single-cell gel electrophoresis or comet assay is a relatively simple method of measuring DNA single-strand breaks and alkali-labile sites in individual cells. Previously, we have used a combination of this with bromodeoxyuridine labelling of DNA and immunolocalisation of the BrdUrd to show that DNA replicative integrity can be assessed in single cultured cells. This study demonstrates the application of the technique to single cells derived from small human colonic biopsies isolated at routine endoscopy. A high level of reproducibility within replicate comet slides and between comet slides prepared from various colonic sites within a single patient is shown. Preliminary results demonstrate that defects in replication can be detected in tumour and premalignant colonic tissue adjacent to the tumour, suggesting that alterations in replicative integrity are an early event in neoplasia, appearing in premalignant mucosal cells. This development deems the BrdUrd comet assay suitable as an ex vivo molecular end point that can be measured easily in tissue collected by biopsy at routine colonic endoscopy. Thus, the BrdUrd comet assay has the potential to facilitate trial investigations of diet- or environment-related factors that may affect replicative integrity in the colon and provides a novel biomarker for colon carcinogenesis.

Don Quixote, Machiavelli, and Robin Hood: public health practice, past and present.

Since the mid-19th century, when the first formal health departments were established in the United States, commissioners, directors, and secretaries of public health have functioned as senior members of the staffs of public executives, mayors, governors, and presidents. They have provided important political, managerial, and scientific leadership to agencies of government that have played increasingly important roles in national life, from the sanitary revolution of the 19th century to the prevention of HIV/AIDS and the control of tobacco use today. Although public health officials come from a variety of backgrounds and oversee agencies of varied size and composition, there are philosophical themes that describe and define the commonality of their work. These themes are captured metaphorically by 3 celebrated figures: Don Quixote, Machiavelli, and Robin Hood. By turns, the public health official functions as a determined idealist (Don Quixote), a cunning political strategist (Machiavelli), and an agent who redistributes resources from the wealthier sectors of society to the less well off (Robin Hood.) All 3 personae are important, but, it is argued, Robin Hood is the most endangered.