Superimposition of sequential scans to measure erosion on unpolished and curved human enamel.

OBJECTIVES: To determine if superimposition of sequential scans can discriminate between different fluorides at step heights less than 5 µm on natural human enamel surfaces. MATERIALS AND METHODS: Natural, unpolished, human enamel specimens (n = 60) were randomly assigned to one of three pre-treatment toothpaste slurries with a calcium silicate/fluoride, fluoride-only and a control. Baseline and post treatment scans, from a non-contacting profilometer with a 0.01 µm z-axis and <1 µm lateral scanning resolution were imported into superimposition software to define change in mean 3D step height and surface roughness following erosion in 0.3% citric acid for 15 min. Statistical analysis conducted with two-way repeated measures ANOVA and post-hoc Tukey's multiple comparisons. RESULTS: Confidence and resolution of superimposition and subtraction of repeated profiles from unpolished enamel revealed accuracy within 1-2 µm. The technique was able to discriminate between the fluorides demonstrating statistical differences in mean (SD) 3D step height (µm) of 1.96 (0.40) and 2.75 (0.49) (p = 0.0024). There was a statistically significant increase in surface roughness for all groups after 15 min erosion compared to baseline. But no statistically significant difference between the interventions after 15 min erosion but there was compared to no fluoride (p = 0.006). CONCLUSION: Superimposition and subtraction of profiles could discriminate between fluoride interventions, which showed statistical differences in enamel loss differences less than 3 µm. CLINICAL SIGNIFICANCE: This erosion model and data analysis workflow was able to distinguish differences between scans of 3 µm on unpolished enamel following the interaction with fluoride.

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.

In vitro evaluation of the early erosive lesion in polished and natural human enamel.

OBJECTIVE: This study evaluated the capability of profilometry, microhardness, Optical Coherence Tomography (OCT) and Tandem Scanning Confocal Microscopy (TSM) in characterising the early erosive lesion in polished and natural human enamel in vitro. METHODS: Polished (n=60) and natural (n=60) human enamel surfaces, were immersed and agitated in 0.3% citric acid erosion at 0s, 10s, 30s, 60s, 120s, and 300s (n=10). Changes in the surface were measured with 3D-step height change (µm), surface roughness (µm), surface microhardness (KHN), and images were assessed qualitatively with OCT and TSM. RESULTS: Mean (SD) 3D-step height change (µm) was measurable for polished enamel at: 60s (0.24±0.1), 120s (1.16±0.71), 300s (2.01±0.47; p<0.05); a step height change was not detectable on acid challenged natural enamel surfaces. Mean (SD) surface roughness (µm) of polished enamel was detected at 10s (0.270±0.013; p<0.05) and all erosion periods; and in natural enamel detected after 120s (0.830±0.125) and 300s (0.800±0.140; p<0.005). Polished enamel Mean (SD) microhardness (KHN) statistically significantly decreased at all time points (p<0.001); this was unmeasurable for natural enamel. Qualitative image analysis of both surface types indicated erosive change at the surface level, with progression after increasing erosion time. SIGNIFICANCE: The early erosive lesion in polished enamel could be characterised quantitatively surface roughness and microhardness and qualitatively using OCT and TSM; whilst in natural enamel only surface roughness could be utilised. Further investigation of early erosion in natural enamel is required to develop new more clinically relevant models.

Evaluating denture cleanliness of patients in a regional dental hospital.

Aims To evaluate the quality of clinical record keeping and determine quality of denture cleanliness; record baseline denture cleanliness for 60 patients; introduce denture hygiene instruction (DHI); and then re-assess the patients for improvement and enhanced record keeping.Methods Analysis of patients' denture hygiene instruction record keeping (n = 60) was undertaken retrospectively. The Denture Cleanliness Index (DCI) was utilised to assess denture cleanliness (best score 0, worst score 4). Baseline DCI scores were taken and individual DHI was delivered. After one month, patients were reviewed and scored, with record keeping quality analysed.Results At baseline, 11.7% (n = 7) of patients had DCI scores of ≤2, improving to 93.8% (n = 45) after one month, demonstrating short-term improvement in denture cleanliness. Only 63% (n = 38) of patients had evidence of a record of DHI within their notes at baseline, improving to 100% at recall.Conclusions New patient information leaflet and clinical guidelines on denture hygiene have been written and implemented. The results of this study suggest that this may be a relatively straightforward method to achieve a short-term improvement in denture cleanliness. The implementation of a DCI score is helpful in allowing patients to improve denture hygiene and its wider use is supported.

Growth hormone and insulin-like growth factor I protect intestinal cells from radiation induced apoptosis.

We studied whether programmed cell death (or apoptosis) is the predominant mechanism in radiation-induced cell damage to rat intestinal mucosa and investigated the mechanism of the protective effect of GH and IGF-I in the same model. Male albino Wistar rats were divided into four groups: controls, radiation, radiation plus GH and radiation plus IGF-I. Radiation was administered on the first day and on day 4. All animals were sacrificed and segments of the terminal ileum were stained with hematoxylin-eosin. Apoptosis of the epithelial cells was identified at the cellular level by the TUNEL stain and was distinguished from necrosis by the characteristic morphology of the cells (cytoplasmic shrinkage, marginal chromatin condensation and generation of nuclear apoptotic bodies). Apoptotic cells in the control animals were few and detected only at the tips of the villi while in the irradiated animals almost all the epithelial cells were apoptotic, distributed from the crypts to the tips of the villi and the mucosa showed severe epithelial atrophy and ulceration. The histologic picture of the mucosa in the GH and IGF-I treated animals was similar to normal controls and apoptotic cells were restricted only at the tips of the villi. DNA and RNA from the mucosa cells were isolated and analyzed by electrophoresis. DNA fragmentation and RNA 28s band ribonuclease cleavage was observed only in the irradiated animals. We have shown that abdominal radiation causes intestinal epithelial cell damage mainly through the induction of apoptosis and the treatment with GH and IGF-I inhibits apoptosis of the cells and preserves the mucosal integrity.

A clinical audit of denture cleanliness in general dental practice undertaken in the West Midlands.

The aims of the study were to develop a method of quantifying denture cleanliness and evaluate the quality of clinical record keeping; record baseline denture cleanliness for 30 patients; introduce denture hygiene instruction (DHI); and then re-assess the patients for improvement and enhanced record keeping. A retrospective analysis of denture hygiene instruction record keeping was undertaken (n = 30). A bespoke denture cleanliness index (DCI) was developed for assessing denture cleanliness (best score 0, worst score 4). Baseline DCI scores were taken and individual DHI was delivered. Patients were reviewed and scored after 1 month, together with a further analysis of record keeping. At baseline, 16% (n = 5) of patients had DCI scores of ≤2, improving to 90% (n = 27) after 1 month, demonstrating short term improvement in denture cleanliness. Only 20% (n = 6) of patients had evidence of a record of DHI within their notes at baseline, improving to 100% at recall. The bespoke denture cleanliness index (DCI) worked well as a simple objective clinical measurement and patient education tool. Provision of tailored DHI resulted in the general improvement of denture cleanliness after 1 month. The authors recommend that where denture hygiene has been issued, this should be recorded in the records as 'DHI' within the clinical notes, in a manner analogous to the recording of oral hygiene.