Prevalence of caries and developmental defects of enamel in 9-10 year old children living in areas in Brazil differing water fluoride histories

Aims To assess the prevalences of caries, of developmental defects of enamel and their interrelationship in Brazilian 9-10-year-olds from areas of contrasting fluoridation histories.Methods systematic random sampling procedures were used to select children from an area where water had been fluoridated in 1963 and from a second area where water had been fluoridated since 1998. Clinical examinations for caries were carried out using the DMFT index and WHO diagnostic criteria. Developmental defects of enamel on upper incisors were diagnosed using the DDE index.Results A difference of 40% in DMFT was observed, with a lower prevalence of disease in the area fluoridated since 1963. Diffuse opacities affected 14.3% of the children from the area fluoridated since 1963 compared with only 2.4% in the area fluoridated in 1998. Children living in the area fluoridated in 1963 who had diffuse defects had twice the chance of being free from caries compared with those living in the same area who had no defects or who had only demarcated or hypoplastic defects.Conclusions This study confirms previous ones in showing the benefits of water fluoridation. Diffuse opacities of upper incisors affected relatively few subjects in either of the two areas.

Different methods of finishing and polishing enamel

Statement of problem. Highly polished enamel surfaces arc recommended for axial tooth surfaces that will serve as guiding planes and be contacted by component parts of a removable partial denture. There is little evidence to support the assumption that this tooth modification will provide accurate adaptation of the framework and prevent build-up of plaque.Purpose. The aim of this investigation was to evaluate the surface roughness of the tooth enamel, prepared to serve as guiding planes, with different polishing systems.Material and methods. Four different methods (designated A, B, C, and D) for finishing and polishing the prepared enamel surfaces of 20 freshly extracted third molar teeth were studied. Each method involved 3, 4, or 5 different steps. The roughness of each specimen was measured at the start of each method before recontouring, after recontouring, and after each step of the 4 finishing and polishing procedures. The 4 experimental finishing methods were applied after recontouring the axial surfaces (buccal, lingual, and proxinial) of each tooth. Thus the 20 teeth (60 surfaces) were finished and polished by use of 1 of the experimental methods. Surface roughness was measured with a profilometer (mum); the readings of the unpolished enamel Surfaces were recorded as control measurements. Results were statistically analyzed with one-way analysis of variance followed by Tukey's test at the 95% level of confidence.Results. The highest roughness mean values (14.41 mum to 16.44 mum) were found when the diamond bur was used at a high speed for tooth preparation. A significant decrease in roughness values was observed with the diamond bur at a low speed (P<.05). Analysis of the roughness values revealed that all polishing methods produced surface roughness similar to that of the corresponding control teeth.Conclusion. Within the limitations of this study, all finishing procedures tested effectively promoted an enamel surface similar to the original unpolished enamel.

In vitro evaluation of acidified toothpastes with low fluoride content

Fluoride toothpastes are a risk factor for the development of dental fluorosis. Products with low fluoride content offer a higher security, but their effectiveness must be proven. The aim of this in vitro study was to compare two acidified toothpastes with low fluoride concentration (412 and 550 mu g F/g) with neutral toothpastes. Bovine enamel blocks were selected by surface microhardness (SMH) and randomized to twelve groups of 13, according to the fluoride concentration in toothpaste (placebo, 275, 412, 550 or 1,100 jig F/g) and pH (7.0 or 5.5). Two commercially available toothpastes were also studied: a 1,100-mu g F/g, pH 7.0 paste (positive control) and a children's paste (500 mu g F/g, pH 7.0). The blocks were subjected to pH cycling for 7 days. The toothpaste treatment was done twice daily. Surface and cross-sectional microhardnesses were assessed to calculate the percentage change of SMH (%SMH) and the mineral loss (Delta Z). The amount of fluoride, calcium and phosphorus in the solutions after the pH cycling was also analyzed. Compared to neutral toothpastes, the acidified toothpastes reduced the %SMH in all F concentrations. Higher F and lower Ca and P concentrations were found in solutions for the acidified toothpastes. Regarding AZ, only the positive control, 1,100-mu g F/g (acidified and neutral) groups were not statistically different. The acidified toothpastes showed a dose-response relationship with all variables. For the low-fluoride toothpastes evaluated, only the 550-mu g F/g acidified paste had the same anticariogenic action as the 1,100-mu g F/g neutral paste.

Comparative ablation rate from a Er : YAG laser on enamel and dentin of primary and permanent teeth

This study was conducted to analyze the ablation rate and micromorphological aspects of microcavities in enamel and dentin of primary and permanent teeth using a Er:YAG laser system. Micromorphological evaluation has been performed in terms of permanent teeth; however, little information about Er: YAG laser interaction with primary teeth can be found in the literature. Because children have been the most beneficiary patients with laser therapy in our offices, it is extremely necessary to compare the effects of this kind of laser system on the enamel and dentin of permanent and primary teeth. In this study, we used eleven intact primary anterior exfoliated teeth and six extracted permanent molar teeth. We used a commercial laser system: a Er: YAG Twin Light laser system (Fotona Medical Lasers, Slovenia) at 2940 nm, changing average energy levels per pulse ( 100, 200, 300, and 400 mJ) producing 48 microcavities in enamel and dentin of primary and permanent teeth. Primary teeth are more easily ablated than are permanent teeth, when related to enamel or dentin. However, while this laser system is capable of slowly revealing the enamel's microstructure, in dentin only the lowest laser energies permit this kind of observation, more easily decomposing the original tissue aspect, when related to primary or permanent teeth. Statistically, the only different factor at the 5% level was an energy per pulse of 400 mJ, confirming the results found in SEM. Our results showed that dentin in both primary and permanent teeth is less resistant to Er: YAG laser ablation; this fact is easily observed under SEM observation and through the ablation rate evaluation.

Evaluation of subsurface dentin microhardness after Er : yttrium-aluminum-garnet and Nd : yttrium-aluminum-garnet laser irradiation

Background and objectives: To assess the microhardness of dentin subsurface after Er:yttrium-aluminum-garnet (YAG) and Nd:YAG laser irradiation. Study design/materials and methods: Twenty-four bovine incisors, without pulp, were used. The vestibular surface was worn out until the dentin was reached and divided in mesial and distal regions. The samples were divided into two groups: GI-distal, irradiated by Er: YAG laser, and GII-distal, irradiated by Nd: YAG laser. The mesial area was protected so as to not receive the laser irradiation. The measurements were made on Vickers digital microhardmeter. Results: For GI-there was no significant statistical difference, Cl(-4.59 to 0.78), between the values of irradiated (55.61 +/- 4.38) and unirradiated (57.51 +/- 4.00) areas. For GII-the values were higher for the irradiated (62.21 +/- 6.48) compared to the unirradiated (57.82 +/- 5.42) area, CI(1.65 +/- to 7.13). Conclusions: There was an increase of dentin microhardness when the Nd: YAG was used, but the Er: YAG did not cause significant alterations in dentin microhardness. (c) 2007 Laser Institute of America.