Pits and fissures: etch resistance in prismless enamel walls

The document attached has been archived with permission from the Australian Dental Association. An external link to the publisher’s copy is included.Background: In a previous study to examine the nature of etching on the walls of fissures, there was a consistent result of resistance to deep etching on parts of the walls and a zone of lesser etching on part of the walls as evidenced by the uptake of stain. The staining had been used to examine the nature of the etch pattern. The aims of this study were to define the nature of this etch resistant area. Methods: A sample of 55 teeth, both molars and premolars, were divided into three groups. In the first group the wetting of fissures by the etchant was examined; the second group tested for the effects of pellicle-cuticle-debris or air entrapment on the etching process. The final group looked at alternative mechanical treatments of the fissure prior to etching. Results: The specimens split along the fissures showed clearly that the etch resistant zone was not due to lack of contact with the etchant or the presence of a pellicle-cuticle-debris covering, but to the presence of a prismless enamel structure. This study showed that this zone inhibited tag development on the fissure walls. Conclusions: The mechanical removal of this prismless layer of enamel within the fissure system should result in an improved bonding of a fissure sealant through better tag development, in turn leading to a reduction in the failure rate of a sealant used to prevent caries.MF Burrow, JF Burrow and OF Makinso

Positive correlation between fluoride release and acid erosion of restorative glass-ionomer cements.

OBJECTIVE: The aim of this study was to determine whether there is a correlation between acid erosion and fluoride release of conventional glass ionomer cements. METHODS: Ten specimens for each material were prepared for fluoride release tests and five for acid erosion tests separately. After placed in pH cycling solution, concentration of fluoride was measured by a fluoride-ion selective electrode each day for 15 days. For the acid erosion test, specimens were immersed in a lactic acid solution and their depth measured with a spring-loaded dial gauge. The data were submitted to 3-way ANOVA, followed by Tukey's test (p0.05). The highest acid erosion values were registered for Magic Glass, Ion Z, VitroFil and Maxxion R, which exceeded the maximum stipulated by the relevant ISO test (ISO 9917-1). A positive linear correlation (r2=0.4886) was found for both properties, i.e., higher fluoride release is related to higher acid erosion. SIGNIFICANCE: Acid erosion and fluoride release are related properties of GICs, though factors such as pH and P/L ratio lead to differences between actual values for individual brands of these materials

Fluoride content and recharge ability of five glassionomer dental materials

<p>Abstract</p> <p>Background</p> <p>The relationship between fluoride content and fluoride release for glass-ionomer cements is not well understood. The aim of this laboratory study was: to determine the fluoride concentrations at the surfaces of glass-ionomer materials with respect to different storage media and different pH environments; to examine the recharge ability of the materials after NaF immersion; and to assess the morphological changes at the material surfaces using scanning electron microscope and energy dispersive spectroscopic techniques (SEM/EDS).</p> <p>Methods</p> <p>Five glass-ionomer materials, Fuji Triage (FT), Fuji II LC (FII), Fuji VIII (FVIII), Fuji IX GP (FIX), and Ketac N100 (KN), were analyzed in this study. Resin-based fluoride releasing material Helioseal F (HSF) was used as a comparison material. The sample consisted of 120 cured cement disks (n = 20 disks of each tested material, 10 × 1.5 mm). Five disks of each material were stored in 4 different storage media (I- saline, II- acidic solution ph = 2.5, III- acid solution ph = 5.5, IV- NaF solution (c = 500/106). After 7 days, two disks of each material were transferred from media I, II and III to the NaF solution for 3 min. EDS analysis was conducted in 3 randomly selected spots of each experimental disk. SEM was used to determine morphological characteristics of the material surface. Differences between the experimental groups have been analyzed using Student's t-test with the level of significance set at p < 0.001.</p> <p>Results</p> <p>FT showed the highest fluoride content at the surface of the material. The lowest amounts of fluoride ions were detected at the surfaces of the FT disks stored at low pH environments, and this difference was statistically significant (p < 0.001). Glass-ionomers showed significantly higher fluoride concentrations when compared to the HSF (p < 0.001). After immersion in the NaF solution, fluoride concentrations at the surfaces of the disks increased when compared with previous storage media (FT>FVIII>KN>FII>FIX). SEM analysis of the surface morphology revealed numerous voids, cracks and microporosities in all experimental groups, except for KN and HSF. More homogenous material structure with more discrete cracks was observed in samples stored at neutral pH environment, compared to disks stored in acidic solutions.</p> <p>Conclusion</p> <p>The tested materials could be considered as promising dental materials with potential prophylactic characteristics due to their relatively high fluoride content, but also the ability to extensively reabsorb fluoride ions, especially in acidic environments.</p

In vitro Evaluation of Magnification and LED Illumination for Detection of Occlusal Caries in Primary and Permanent Molars Using ICDAS Criteria

Background: Early detection of occlusal caries in children is challenging for the dentists, because of the morphology of pit and fissures. Aim: The aim of the present study was to investigate the use of low-powered magnification (×2.5) and its association with LED headlight illumination for occlusal caries detection in primary and permanent molars using International Caries Detection and Assessment System (ICDAS) criteria.Methods: The occlusal surfaces of 36 extracted teeth (n=18 primary molars, n=18 permanent molars) were examined using ICDAS criteria with unaided visual examination, low-powered magnification and low-powered magnification plus LED headlight illumination. Three examiners evaluated one occlusal site per tooth twice independently with one week interval, using all methods. The teeth (n = 36) were sectioned and examined under light microscopy using Downer’s histological criteria as the gold standard. Results: The weighted kappa values for inter- and intraexaminer reproducibility for the ICDAS examinations were almost perfect (Kappa values 0.72–0.96) in all three examination methods. The correlation with histology and overall AUC performance (0.96–0.98) of low-powered magnification plus LED headlight illumination was statistically significant in permanent molars. In primary molars, both low-powered magnification (0.82–0.90) and low-powered magnification plus LED headlight illumination (0.87–0.93) showed statistically significant correlation with histology and good to excellent AUC performance than unaided examination. Conclusion: Visual aids have the potential to improve the performance of early caries detection and clinical diagnostics in children

Fracture resistance of immature teeth filled with BioAggregate, mineral trioxide aggregate and calcium hydroxide

Background: The aim of this in vitro study was to assess the long-term fracture resistance of human immature permanent teeth filled with BioAggregate (BA), mineral trioxide aggregate (MTA) and calcium hydroxide (CH). Materials and methods: The study consisted of single rooted premolar teeth with immature root formation extracted for orthodontic reasons. A total of 28 immature premolars with average root length of 10.7 mm and apical diameter of 3 mm were included in the study. The pulps were extirpated and the canals were prepared using an apical approach. The teeth were randomly assigned to four groups: Group I: DiaRoot (R) BA (DiaDent, Burnaby, BC, Canada), Group II: Angelus MTA (MTA-A; Angelus, Londrina, Brazil), Group III: ProRoot (R) MTA (MTA-PR; Dentsply, Tulsa, OK, USA), Group IV: CH (Sultan Chemists Inc., Englewood, NJ, USA). The teeth were placed in saline solution at 4 degrees C for 1 year. The root of each tooth was then embedded in an acrylic resin block. All specimens were loaded at a crosshead speed of 1 mm min-1 in an Instron testing machine and the peak loads up to fracture were recorded. Data were analysed statistically by Kruskal-Wallis and Mann-Whitney U-tests. Results: Mean (+/- SD) failure loads (MPa) were: 37.69 +/- 14.43 for BA group, 32.94 +/- 8.15 for MTA-A group, 28.74 +/- 9.49 for MTA-PR group and 23.18 +/- 8.48 for CH group. The BA group exhibited the highest fracture resistance and the CH group showed the lowest resistance to fracture. Significant differences (P < 0.05) in fracture resistance were found between the DiaRoot-BA and CH groups, and also between the MTA-A and CH groups. Conclusion: Within the limitations of this study, data suggest that DiaRoot-BA-filled immature teeth demonstrate higher fracture resistance than other groups at 1 year. Considering the long-term risk of cervical root fracture associated with immature teeth, the use of DiaRoot-BA as a root canal filling material appears to be the most advantageous of the materials tested

Proteome and Peptidome of Human Acquired Enamel Pellicle on Deciduous Teeth

Understanding the composition and structure of the acquired enamel pellicle (AEP) has been a major goal in oral biology. Our lab has conducted studies on the composition of AEP formed on permanent enamel. The exhaustive exploration has provided a comprehensive identification of more than 100 proteins from AEP formed on permanent enamel. The AEP formed on deciduous enamel has not been subjected to the same biochemical characterization scrutiny as that of permanent enamel, despite the fact that deciduous enamel is structurally different from permanent enamel. We hypothesized that the AEP proteome and peptidome formed on deciduous enamel may also be composed of unique proteins, some of which may not be common with AEP of permanent enamel explored previously. Pellicle material was collected from 10 children (aged 18&amp;#8211;54 months) and subjected to mass spectrometry analysis. A total of 76 pellicle proteins were identified from the deciduous pellicle proteome. In addition, 38 natural occurring AEP peptides were identified from 10 proteins, suggesting that primary AEP proteome/peptidome presents a unique proteome composition. This is the first study to provide a comprehensive investigation of in vivo AEP formed on deciduous enamel

Proteomic evaluation of acquired enamel pellicle during in vivo formation.

Acquired enamel pellicle (AEP) is a protein film that forms on the enamel surface of teeth by selective adsorption of proteins and peptides present in the mouth. This protein film forms the interface between enamel and the damage oral biofilm, which modulates the attachment of bacteria found in oral biofilm. The overall goal of this study was to gain insight into the biological formation of the human in vivo AEP. This study hypothesized that AEP is created by the formation of successive protein layers, which consist of initial binding to enamel and subsequent protein-protein interactions. This hypothesis was examined by observing quantitative and qualitative changes in pellicle composition during the first two hours of AEP formation in the oral cavity. Quantitative mass spectrometry approaches were used to generate an AEP protein profile for each time-point studied. Relative proteomic quantification was carried out for the 50 proteins observed in all four time-points. Notably, the abundance of important salivary proteins, such as histatin 1, decrease with increasing of the AEP formation, while other essential proteins such as statherin showed constant relative abundance in all time-points. In summary, this is the first study that investigates the dynamic process to the AEP formation by using proteomic approaches. Our data demonstrated that there are significant qualitative and quantitative proteome changes during the AEP formation, which in turn will likely impact the development of oral biofilms