Flexural Strength, Elastic Modulus and Remineralizing Abilities of Bioactive Resin-Based Dental Sealants

Objective: To assess the remineralizing abilities and compare the flexural strength and elastic modulus of different bioactive pit and fissure sealants. Materials and Methods: Human enamel samples were randomly and blindly sealed with one of the following bioactive materials: BioCoat (Bc), ACTIVA KIDS (Av) and BeautiSealant (Bu). Seal-it (Si) was used as a non-bioactive sealant beside a control blank (B) group with no sealant. The sealed samples were subjected to a pH-cycling model (7 days of demineralization–remineralization cycles). The enamel surface hardness change (SHC), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) and polarized light microscopy were used to assess the remineralizing abilities of the studied sealants. Flexural strength and elastic modulus were also assessed following the ISO 4049 protocols. One-way analysis of variance (ANOVA) was used to analyze the results. Results: Bc sealant showed the highest FS and EM (p < 0.05). The contact with Bc and Bu sealants showed significantly lower %SHL (p < 0.05) in comparison to the other. These findings were supported by the results of SEM-EDX and polarized imaging by showing higher percentages of calcium and phosphate ions with the former sealants and thinner demineralized enamel bands. Conclusion: In this study, Bc showed the highest flexural strength. Bc and Bu sealants outperformed the other studied sealants in terms of their remineralization abilities.

The translucency of human teeth and its relation to esthetic restorative materials

The main factor that can determine the harmonization and depth of color restorations for the adjacent other restorations or other teeth is the translucency of these restorations. Many factors can affect the translucency and color of the restoration material, including translucency parameter, lighting conditions, opacity, gloss, light scattering, and overall perception by the naked eye. Previous investigations have indicated that translucency is the main factor that can significantly contribute to the esthetic characteristics of the different dental restoration materials. In the present literature review, we have discussed the translucency of human teeth and its relation to esthetic restorative materials. Comparing the translucency of the different restoration materials with the naturally occurring human enamel is essential for adequate validation of their clinical application. It has been demonstrated that for 1 mm thick human enamel, a mean value for the translucency parameter of 15-19 should be considered. We have also highlighted the differences between the different types of resin composites and different shade groups, and findings indicate the superiority of some types and shade groups over others, as previously discussed. However, it should be noted that further research is still needed to unify the variously estimated values for the translucency parameter among the different restoration materials. This can help clinicians adequately interpret these data and obtain satisfactory clinical and patient-related outcomes.

Abrasion Behaviour of Different Charcoal Toothpastes When Using Electric Toothbrushes

Objectives: The purpose of this in vitro study was to compare the abrasion behaviour of different charcoal toothpastes when brushing with electric toothbrushes on human enamel. Materials and Methods: A self-designed brushing machine was built using six commercially available electric toothbrushes in abrasion chambers. Each chamber was constantly supplied with a toothpaste–water mix. Pieces of human enamel, which were embedded in PMMA, were brushed for 4 h. Before and after brushing, profilometer measurements were performed in order to determine the substance loss due to brushing. Results: The following calculated mean removal values (mean ± SD) were found: (4.6 ± 0.6) µm (Group C: Splat Blackwood), (3.2 ± 0.9) µm (Group D: Curaprox Black is White), (2.3 ± 0.7) µm (Group B: Sensodyne Pro Schmelz), (1.7 ± 0.6) µm (Group A: Water), (1.4 ± 0.6) µm (Group E: Prokudent Black Brilliant). A post hoc Tukey HSD test (p = 0.05) showed that the results for Group A/B/E, Group B/D and Group C each lie within subsets that differ statistically significantly from the other subsets. Conclusions: Within the limitations of this in vitro study, it can be stated that some charcoal toothpastes lead to significantly higher abrasion on human enamel, when brushing with electric brushes. Clinical Relevance: As low-abrasion toothpaste is generally advisable, and some charcoal toothpastes should be viewed critically with regard to their abrasive properties.

The Erosive Potential of Acidic Candies: An Ex Vivo Study

Aim: The aim of this study was to evaluate the erosive potential of saliva on dental enamel sucking the acidic candies, and their effects on the pH, titratable acidity (TA) and buffering capacity (β) of saliva. Methodology: Human enamel specimens (n = 216) were randomly in 17 acidic candy groups and one negative control (paraffin wax) group. Three human volunteers sucked each candy for 5 min while spitting into a covered and chilled vial. The pH, TA and β were measured immediately after the saliva collection. For erosive challenge, each specimen was immersed in saliva at room temperature for 120 min without agitation. The erosion was measured by surface microhardness (SMH) tester and with 3D non-contact optical profilometer for depth of surface loos (DSL). Percentage of SMH change (%SMHC) was calculated. ANOVA followed by Tukey test and Pearson correlation were performed (α=0.05). Results: All candies lowered saliva pH below 5.5, and produced significant DSL (P<0.05) and %SMHC (P<0.01) on enamel, when compared to negative control. The Baby bottle Pop candy presented the lowest erosive potential. No significant differences were observed in DSL between all candies and the negative control, except for the PicoSitos candy. However, for the %SMHC almost all the candies were significantly different from negative control. Correlations were observed between the pH and TA and β, between TA and β, and between the %SMHC and DSL variables (P<0.05). Conclusion: Acidic candies can lower the saliva pH, hindering its buffering effect. The DSL and %SMHC analysis showed enamel dissolution with all candies investigated.

Assessing the predictability of existing water-to-enamel geolocation models against known human teeth

Stable isotope analysis of human tissues has become a valuable tool for mapping human geolocation. This study adds to the existing knowledge of the relationship between oxygen stable isotopes in human enamel and drinking water by presenting enamel oxygen values in clinic-extracted human dental enamel with known provenance. The results from this study indicate that the theoretical isotopic relationship between enamel and drinking water oxygen is weak at the city and country-level. Differences of up to 15‰ were observed between predicted drinking water oxygen values using existing models and observed values, highlighting the complexity of using water/enamel conversion equations. The lower isotopic boundary of enamel oxygen values is now understood for Metro Vancouver at δ18Oc(VPDB) = – 11.0‰ and presents the possibility of using stable isotope analysis as an exclusionary tool where individuals falling below threshold value can be identified as non-local. Overall, this study’s results support the development of geographical reference maps for human enamel oxygen.

A Chitosan–Agarose Polysaccharide-Based Hydrogel for Biomimetic Remineralization of Dental Enamel

Developing multifunctional systems for the biomimetic remineralization of human enamel is a challenging task, since hydroxyapatite (HAP) rod structures of tooth enamel are difficult to replicate artificially. The paper presents the first report on the simultaneous use of chitosan (CS) and agarose (A) in a biopolymer-based hydrogel for the biomimetic remineralization of an acid-etched native enamel surface during 4–10-day immersion in artificial saliva with or without (control group) fluoride. Scanning electron microscopy coupled with energy-dispersive X-ray spectrometry, Fourier transform infrared and Raman spectroscopies, X-ray diffraction, and microhardness tests were applied to investigate the properties of the acid-etched and remineralized dental enamel layers under A and CS-A hydrogels. The results show that all biomimetic epitaxial reconstructed layers consist mostly of a similar hierarchical HAP structure to the native enamel from nano- to microscale. An analogous Ca/P ratio (1.64) to natural tooth enamel and microhardness recovery of 77.4% of the enamel-like layer are obtained by a 7-day remineralization process in artificial saliva under CS-A hydrogels. The CS component reduced carbonation and moderated the formation of HAP nanorods in addition to providing an extracellular matrix to support growing enamel-like structures. Such activity lacked in samples exposed to A-hydrogel only. These data suggest the potential of the CS-A hydrogel in guiding the formation of hard tissues as dental enamel.