Automatic removal of soft tissue from 3D dental photo scans; an important step in automating future forensic odontology identification.

The potential of intraoral 3D photo scans in forensic odontology identification remains largely unexplored, even though the high degree of detail could allow automated comparison of ante mortem and post mortem dentitions. Differences in soft tissue conditions between ante- and post mortem intraoral 3D photo scans may cause ambiguous variation, burdening the potential automation of the matching process and underlining the need for limiting inclusion of soft tissue in dental comparison. The soft tissue removal must be able to handle dental arches with missing teeth, and intraoral 3D photo scans not originating from plaster models. To address these challenges, we have developed the grid-cutting method. The method is customisable, allowing fine-grained analysis using a small grid size and adaptation of how much of the soft tissues are excluded from the cropped dental scan. When tested on 66 dental scans, the grid-cutting method was able to limit the amount of soft tissue without removing any teeth in 63/66 dental scans. The remaining 3 dental scans had partly erupted third molars (wisdom teeth) which were removed by the grid-cutting method. Overall, the grid-cutting method represents an important step towards automating the matching process in forensic odontology identification using intraoral 3D photo scans.

Fluoride in Saliva and Oral Mucosa after Brushing with 1,450 or 5,000 ppm Fluoride Toothpaste.

The aim was to measure and compare fluoride concentrations in oral mucosa and saliva following a single brushing with either 1,450 or 5,000 ppm fluoride toothpaste. Fourteen healthy participants provided saliva and oral mucosa samples in the morning before tooth brushing. Then participants brushed their teeth with 1,450 ppm fluoride toothpaste, and saliva and mucosa samples were collected after 1, 2, 4, and 6 h. The experiment was repeated 3-7 days later with 5,000 ppm fluoride toothpaste. All samples were analyzed for fluoride using an ion-selective electrode adapted for microanalysis. Pre-brushing fluoride concentrations were higher in mucosa (mean1,450 0.26 ppm and mean5,000 0.20 ppm) than in saliva (mean1,450 0.08 ppm and mean5,000 0.07 ppm). The mean fluoride concentrations increased in both mucosa and saliva following a single brushing with both 1,450 ppm (meanmuc1,450 (1 h) 1.15 ppm, meansal1,450 (1 h) 0.33 ppm) and 5,000 ppm fluoride toothpaste (meanmuc5,000 (1 h) 3.21 ppm and meansal5,000 (1 h) 0.90 ppm). At 6 h, the fluoride concentrations had returned to pre-brushing levels. Across the 6-h sampling period the fluoride concentration in saliva was statistically significantly 1.4 times higher following brushing with 5,000 ppm compared with 1,450 ppm fluoride toothpaste. For mucosa, this ratio was only 1.1 and not statistically significant. In conclusion, the fluoride level in oral buccal mucosa is higher than in saliva and follows the same fluoride clearance pattern as in saliva. Over the initial 6-h period following a single tooth brushing, the ratio of the fluoride concentration in mucosa to that in saliva is independent of the fluoride concentrations in the toothpastes used.

Fluoride in saliva and dental biofilm after 1500 and 5000 ppm fluoride exposure.

OBJECTIVES: The aim of this randomized, double-blind, crossover study was to measure fluoride in saliva and 7-day-old biofilm fluid and biofilm solids after rinsing three times per day for 3 weeks with 0, 1500, or 5000 ppm fluoride (NaF). MATERIALS AND METHODS: Following the 3-week wash-in/wash-out period, including 1 week of biofilm accumulation, saliva and biofilm samples were collected from 12 participants immediately before (background fluoride), and 10, 30, and 60 min after a single rinse. Biofilm samples were separated into fluid and solids, and samples were analyzed using a fluoride electrode (microanalysis). RESULTS: The background fluoride concentration was statistically significantly higher in the 5000 compared to the 1500 ppm F rinse group in all three compartments (22.3 and 8.1 µM in saliva, 126.8 and 58.5 µM in biofilm fluid, and 10,940 and 4837 µmol/kg in biofilm solids). The 1-h fluoride accumulation for the 5000 ppm F rinse was higher than for the 1500 ppm F rinse in all three compartments, although not statistically significant for saliva and biofilm solids. CONCLUSION: Regular exposure to 5000 ppm fluoride elevates background fluoride concentrations in saliva, biofilm fluid, and biofilm solids compared to 1500 ppm fluoride. Increasing the fluoride concentration almost 3.5 times (from 1500 to 5000 ppm) only elevates the background fluoride concentrations in saliva, biofilm fluid, and biofilm solids twofold. CLINICAL RELEVANCE: Even though fluoride toothpaste may be diluted by saliva, the results of the present study indicate that use of 5000 ppm fluoride toothpaste might lead to improved caries control.

Fluoride in Dental Biofilm Varies across Intra-Oral Regions.

Information on differences in biofilm fluoride concentration across intra-oral regions may help explain the distribution of caries within the dentition. The aim of this cross-sectional study was to describe the fluoride concentration in saliva and in biofilm fluid and biofilm solids across 6 intra-oral regions. Unstimulated whole saliva was collected from 42 participants and biofilm harvested from the buccal sites in the 4 molar and 2 anterior regions. Samples were collected at least 1 h after use of fluoride dentifrice. No attempt was made to control the participants' food consumption or use of other topical agents. Centrifuged saliva, biofilm fluid, and biofilm solids were analysed for fluoride using a fluoride ion-selective electrode, adapted for microanalysis. Fluoride in biofilm varied across intra-oral regions. The mean biofilm fluid fluoride concentrations across the oral cavity ranged from 11.6 to 16.8 µM, being statistically significantly higher in the upper anterior region than in any other region. In all regions the fluoride concentration in biofilm fluid was higher than in saliva. For biofilm solids the fluoride concentration was highest in the lower anterior region (2,461 µmol/kg) and lowest in the lower molar regions (388 and 406 µmol/kg, respectively). Within biofilm, the solids contained most of the fluoride (81 to >99%). The biofilm fluid fluoride concentration was significantly positively associated with salivary fluoride and only marginally associated with that of biofilm solids. In conclusion, this study has shown pronounced differences in fluoride distribution across intra-oral regions and compartments. This shows that the sampling site is a crucial factor for studies of biofilm fluoride.