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Background: Laser-activated fluoride (LAF) therapy with 488 nm laser energy has been shown previously to increase the resistance of human enamel and dentine to acid dissolution in laboratory models of dental caries. The aims of this study were to examine whether LAF therapy, conducted using a range of wavelengths in the visible and near infrared regions, can protect human dental enamel from an artificial cariogenic challenge., Materials and Methods: Buccal and lingual surfaces of extracted sound, molar and premolar teeth were used to prepare matched pairs of enamel slabs (N=10 per group). After application of neutral sodium fluoride gel (12300 ppm F ion), slab surfaces were lased (energy density 15 J/cm2; spot size 5mm, wavelength 532, 633, 670, 830 or 1064nm), then exposed to an artificial cariogenic challenge for a period of seven days. The Vicker's hardness number (VHN) was recorded before and after laser treatment and again following the cariogenic challenge. Negative controls did not receive laser exposure., Results: All wavelengths of laser light examined provided an effective LAF effect, compared with the unlased negative control surfaces., Conclusion: Using this in vitro model, we conclude that the action spectrum of the LAF effect extends across the visible and near-infrared regions of the spectrum.

Background: Patients with cleft lip and/or palate (CL&/P) experience a higher caries prevalence. This study aimed to determine if patients with CL&/P, undergoing and not undergoing orthodontic treatment, have a different salivary biochemical profile and different salivary levels of Mutans Streptococci (MS) and Lactobacilli (LB) compared to patients undergoing and not undergoing orthodontic treatment without CL&/P. Methods: One hundred and ten subjects aged between 12 and 17 years were recruited into one of four different groups comprising two control groups and two treatment groups. The control groups comprised of subjects with and without CL&/P who were not undergoing orthodontic treatment. The treatment groups comprised of subjects with and without CL&/P undergoing orthodontic treatment. Regular reinforcement of oral hygiene instructions, dietary counselling and debridement, when necessary, were offered to subjects in the treatment groups following their orthodontic adjustment appointments. The salivary secretion time, pH of resting and stimulated saliva, salivary flow rate, buffering capacity, quantity of salivary MS and LB were measured. Results: Subjects with CL&/P undergoing orthodontic treatment at the Children's Oral Health Service tended to present with microbiological and salivary profiles that were less favourable for caries development. There was a significant difference in the percentage of subjects with ≥ 105 colony forming units (CFU)/mL of MS between the cleft treatment and non-cleft treatment groups. Subjects in the noncleft treatment group had the highest percentage of subjects (86.7 per cent) with ≥ 105 CFU/mL of MS whereas subjects in the cleft treatment group had the lowest percentage of subjects (60 per cent) with ≥ 105 CFU/mL of MS. For LB, there were significantly higher percentages of subjects with ≥ 105 CFU/mL of LB in the non-cleft treatment (76.7 per cent) and cleft treatment (73.3 per cent) groups compared to the non-cleft control (46.7 per cent) and cleft control (40.0 per cent) groups. Conclusions: Regular oral hygiene reinforcement and dental health education appears to have a positive effect in reducing the percentage of subjects with ≥ 105 CFU/mL of MS. [ABSTRACT FROM AUTHOR]