Enamel Pieces Research Articles

The effect of antibacterial photodynamic therapy with diode laser on chromogenic bacteria associated with dental black staining: An in-vitro study

BackgroundAggregatibacter actinomycetemcomitan (A.a) and Actinomyces naeslundii (A.n) are two gram-negative chromogenic bacteria involved in the formation of dental black stainings. Our study aimed to investigate the antibacterial effect of photodynamic therapy (aPDT) using two photosensitizers, Methylene Blue (MB) and Indocyanine Green (ICG). Materials and methodsIn this in-vitro study, two isolates of each selected bacterium were cultured and treated as follows; Negative control with no treatment; CHX as a positive control; ICG; MB; ICG with 808 nm laser activation; and MB with 660 nm laser activation. The number of colonies (CFU/mL) was determined to compare the groups. The qualitative evaluation of biofilm formation was done by scanning electron microscopy of treated enamel pieces. The logarithmic values of the colony counts were compared using One-way ANOVA and the Welch test Tukey HSD and Games-Howell tests were used for multiple comparisons. P-values of less than 0.05 were considered statistically significant. ResultsThe use of ICG alone or along with laser irradiation at the wavelength of 808 nm significantly reduced the number of colonies of A.a and A.n bacteria. Comparing the colony counts in the MB group with the positive control showed no significant decrease in bacterial load. On the contrary, activation of MB with 660 nm radiation of diode laser showed a significant antibacterial effect. The density of bacterial biofilm was significantly lower in the groups treated with MB and ICG without laser activation than in the control group; however, the reduction in bacteria biofilm density was more robust using photodynamic therapy with ICG. ConclusionaPDT using MB with 660 nm laser and ICG with 808 nm laser significantly reduced the number of chromogenic A.a and A.n bacteria, and photodynamic therapy with ICG was proven to be significantly more effective than MB with or without laser radiation.

Inhibitory Activity of Essential Oils of Mentha spicata and Eucalyptus globulus on Biofilms of Streptococcus mutans in an In Vitro Model.

The aim of this study was to evaluate the inhibitory activity of the commercially available essential oils of Mentha spicata (spearmint) and Eucalyptus globulus (eucalyptus) on Streptococcus mutans ATCC 25175 biofilms in vitro, emulating dental plaque conditions. The composition of the essential oils (EOs) was determined using gas chromatography coupled with mass spectrometry (GC-MS), with the main metabolites being Carvone (57.93%) and Limonene (12.91%) for Mentha spicata and 1,8-Cineole (Eucalyptol) (65.83%) for Eucalyptus globulus. The inhibitory activity was evaluated using the methods of agar-well diffusion and colorimetric microdilution. The inhibition halos were 18.3 ± 0.47 mm and 27.0 ± 0.82 mm, and the MICs were 1.8484 mg/mL and 1.9168 mg/mL for the EOs of Mentha spicata and Eucalyptus globulus, respectively. The activity against the biofilms was evaluated on a substrate of bovine enamel pieces using a basal mucin medium (BMM) in anaerobic conditions with daily sucrose exposition cycles in order to emulate oral cavity conditions. The EOs were applied in a concentration of 0.5% in a sterile saline vehicle with 1% polysorbate 20. After 72 h of cultivation, a significant reduction was observed (p < 0.001%) on the biofilm biomass, which was evaluated by its turbidity in suspension and using a count of the recoverable organisms with regards to the control. The effects of the Eos were not significantly distinct from each other. The EOs showed antimicrobial activity against both the Streptococcus mutans planktonic and biofilm cultures. Thus, EOs may have great potential for the development of pharmaceutical and sanitary products for oral health.

Comparison of the effect of fluoride gel and two toothpastes with different materials on remineralization of initial carious lesions in primary teeth.

Introduction:Various types of toothpastes are claimed to be able to improve initial enamel caries. This study compared the effect of fluoride gel and two toothpastes on remineralization of initial caries lesions in primary teeth.Materials and Methods:A total of sixty-four sound extracted primary canine were immersed in demineralizing solution at 37°C for 96 h to produce artificial caries in vitro. Enamel pieces (3 × 3 × 5 mm) were prepared from each tooth and mounted in self cure acrylic blocks. The specimens were randomly assigned to four groups (n = 16) based on treatment agent (fluoride gel, Chitodent toothpaste, ReminPro toothpaste, no treatment as control) and underwent a pH cycling model for 10 days. Vickers microhardness (VH) was measured before and after treatment. Data was analyzed using analysis of variance and paired t-test by SPSS 18 (P < 0.05).Results:No significant difference was found in VH between groups at baseline (fluoride group: 265.9 ± 44.8, Chitodent group: 282.6 ± 34.6, ReminPro group: 266.5 ± 26.6, control: 272.7 ± 32.5; P = 0.516). Microhardness significantly increased after exposure to ReminPro toothpaste (VH change: 24.1%, P < 0.001) and fluoride gel (VH change: 10.9%, P = 0.046), but no significant changes were observed in Chitodent (VH change: 2.8%, P = 0.635) and control (VH change: - 2.2%, P = 0.181) groups.Conclusion:ReminPro toothpaste might be effective in remineralizing initial carious lesions of primary teeth.

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.

Atomic force microscopy analysis of the surface alterations of enamel, dentin, composite and ceramic materials exposed to low oral pH in GERD.

Dental erosion is a significant topic in medical literature, both for gastroenterology and dental medicine. Dental structure loss has a psychosocial and functional significance. The pathogenesis of dental erosion in patients diagnosed with gastroesophageal reflux disease (GERD) characterized by the presence of an acidic oral environment after reflux episodes, is not well understood. The present study was designed to observe the effect of low oral pH in time on natural surfaces including enamel and dentine, but also on materials used in treating these dental destructions such as composites and ceramics. The acidic oral environment was estimated in relation to salivary pH. In the dental laboratory, 5-mm2 and 1-mm composite pieces of thick enamel, dentine, Emax Ceramic and Nexco Ivoclar were cut in order to be analyzed using atomic force microscopy (AFM) and to observe the surface alterations. Gastric acid was collected and mixed with saliva until a pH value of 6.0 was obtained, in which the pieces were immersed for 24, 120, 240 h. Roughness of each surface was calculated at a microstructure and nanostructure level. The results showed significant alterations in enamel and dentine exposed to a lower pH level beginning even at a short immersion time, in comparison with composites and ceramics which had no alterations. In conclusion, multidisciplinary attention should be given to detect and manage acidity of the oral cavity caused by GERD, in order to prevent dental erosion.

Kelarutan kalsiumemail pada saliva penderita tuna netra (Dissolution of enamel calcium in saliva of patients with visual impairment)

Patients with visual impairment experienced debris, calculus and a high index of oral hygiene. Low salivary flow anddifficulty in cleaning the oral cavity in patients with visual impairment caused high accumulation of plaque that causesa decrease in the pH of saliva. Low pH of saliva affects the balance of the composition of inorganic email. Calcium isthe largest inorganic content of the email, thus dissolving calcium email can be an indication of enameldemineralization. This study aimed to determine the solubility of calcium in saliva of blind patients, and salivary pHrelationship with the solubility of calcium. This experimental laboratory study used saliva taken from 8 blind patientsand artificial saliva as a medium of enamel pieces soaking for 24 hours. Dissolved calcium levels were measured byatomic absorption spectrophotometer. The results showed that the solubility of calcium in the saliva of blind patientsgreater than the control group (p&lt;0.05). Pearson correlation test demonstrate the relationship between salivary pHand solubility of calcium enamel, so the lower the pH the greater enamel calcium dissolution. It was concluded that themagnitude of the solubility of calcium enamel due to decreased of salivary pH.

Ice-templated calcium silicate scaffolds for dental and maxillofacial surgery

Purpose: Protection of enamel-restorativemargin is important to prevent marginal leakage, plaque accumulation, and secondary caries. Due to differences of physical properties between enamel and glass ionomer restoratives, the margins can be damaged by toothbrush abrasion. The aim of this study was to evaluate the effect of resin-coatings for protection of enamel-restoration margins. Methods and materials: Small pieces of enamel (1.5mm× 1.5mm× 5mm) were made from the bovine tooth and embedded in acrylic mold. EQUIA system (EQU, GC; EQUIA Fil, Lot. 1401181, A2 and EQUIA Coat, 1312181), ChemFil Rock (CFR, Dentsply; Lot.1204000238, A2) and Riva selfcure (RSC, SDI; Lot. A1307182EG, A2) are filled into acrylic mold to fabricate enamel-GI restorative margin specimens. Margins were covered by EQUIA Coat in group of EQUIA system. Specimens were subjected to 25,000 and 50,000 cycles (200 g load) of toothbrush wear test against restoration-enamel margins in dentifrice diluted by distilled water (dentifrice:water = 1:3). Wear depth of glass ionomer restoratives from enamel surface were measured by KEYENCE laser microscope VK-X200 (n=8). Data were analyzed by student t-test (p<0.01). Results: The wear depth at the margins for each materials are shown in Table 1. It was suggested that the coatings is effective to protect enamel-GIC restorative margins by prevention wear gap formation.

Scanning Electron Microscopy of Growing Dental Plaque: A Quantitative Study with Different Mouth Rinses

The aim of this study was to quantify the influence of different mouth rinses on dental plaque. Wearing splints with enamel pieces 24 volunteers rinsed with essential oils, amine/stannous fluoride, or chlorhexidine digluconate (0.12%) mouth rinses. After 24, 48, 72, and 96 h the enamel pieces were analyzed by scanning electron microscopy. The counts of cocci and bacilli in different plaque layers and the plaque thickness were almost similar using essential oils and amine/stannous fluoride. These results differed significantly from those of chlorhexidine digluconate mouth rinses. The results for plaque thickness were without significant differences between the groups at any appointment.

Mechanisms and causes of wear in tooth enamel: implications for hominin diets

The wear of teeth is a major factor limiting mammalian lifespans in the wild. One method of describing worn surfaces, dental microwear texture analysis, has proved powerful for reconstructing the diets of extinct vertebrates, but has yielded unexpected results in early hominins. In particular, although australopiths exhibit derived craniodental features interpreted as adaptations for eating hard foods, most do not exhibit microwear signals indicative of this diet. However, no experiments have yet demonstrated the fundamental mechanisms and causes of this wear. Here, we report nanowear experiments where individual dust particles, phytoliths and enamel chips were slid across a flat enamel surface. Microwear features produced were influenced strongly by interacting mechanical properties and particle geometry. Quartz dust was a rigid abrasive, capable of fracturing and removing enamel pieces. By contrast, phytoliths and enamel chips deformed during sliding, forming U-shaped grooves or flat troughs in enamel, without tissue loss. Other plant tissues seem too soft to mark enamel, acting as particle transporters. We conclude that dust has overwhelming importance as a wear agent and that dietary signals preserved in dental microwear are indirect. Nanowear studies should resolve controversies over adaptive trends in mammals like enamel thickening or hypsodonty that delay functional dental loss.

Late Pleistocene Vertebrates from a Rockshelter in Cimarron County, Oklahoma

Abstract We studied fossils of late Pleistocene vertebrates that were excavated in 1940 from a small rockshelter in Cimarron County, Oklahoma. The assemblage consists of a Canada goose (Branta canadensis) and 14 mammals. Most of the mammals are large or medium-sized indicating a bias in the method of collecting. The assemblage includes Branta canadensis, Mammuthus cf. M. columbi, Cynomys, Neotoma, Lepus, Sylvilagus, Vulpes velox, Canis latrans, Canis lupus, cf. Lynx, Equus cf. conversidens, Equus cf. niobrarensis, Camelops hesternus, Antilocapridae, and Bison. Noteworthy among these is one of the few available late Pleistocene records of the swift fox, Vulpes velox. A piece of enamel from the mammoth at the locality yielded a radiocarbon age of 23,980 ± 130 years before present.

Protein content of molar–incisor hypomineralisation enamel

Objectives The aim of the study was to compare the relative amounts and nature of the proteinous content of sound and molar–incisor hypomineralisation (MIH) enamel. Methods TCA (20%) was used to dissolve the mineral phase and precipitate the proteins from enamel pieces sectioned from sound and MIH enamel. The protein content was estimated using a miniaturized version of the method of Lowry et al. Samples of the solubilised protein were separated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), stained with Coomassie Blue R250 and tryptic fingerprint/mass spectrometry (MS/MS) of bands in excised gel pieces used for protein identification. Results Compared to sound enamel, brown enamel showed a 15–21-fold higher protein content, and yellow and chalky enamel showed about 8-fold higher protein content. Tryptic fingerprint/MS performed on excised 50–70 kDa areas demonstrated serum albumin, type I collagen and antitrypsin to be common to all types of enamel. Yellow and brown enamel showed more abundant serum albumin and antitrypsin, and the presence of serum antithrombin. Albumin is reported to be an inhibitor of crystal growth, and antitrypsin and antithrombin inhibit kallikrein 4 proteolytic activity. Conclusions The combination of the effects of serum proteins on developing enamel may result in elevated proteinous content and reduced mineral content as seen in MIH enamel.

Oral bacterial biofilms – history in progress

Oral bacterial biofilms – history in progress

A comparison of fatigue crack growth in human enamel and hydroxyapatite

Cracks and craze lines are often observed in the enamel of human teeth, but they rarely cause tooth fracture. The present study evaluates fatigue crack growth in human enamel, and compares that to the fatigue response of sintered hydroxyapatite (HAp) with similar crystallinity, chemistry and density. Miniature inset compact tension (CT) specimens were prepared that embodied a small piece of enamel ( N = 8) or HAp ( N = 6). The specimens were subjected to mode I cyclic loads and the steady state crack growth responses were modeled using the Paris Law. Results showed that the fatigue crack growth exponent ( m) for enamel ( m = 7.7 ± 1.0) was similar to that for HAp ( m = 7.9 ± 1.4), whereas the crack growth coefficient ( C) for enamel ( C = 8.7E−04 (mm/cycle) × (MPa m 0.5) − m ) was significantly lower ( p < 0.0001) than that for HAp ( C = 2.0E+00 (mm/cycle) × (MPa m 0.5) − m ). Micrographs of the fracture surfaces showed that crack growth in the enamel occurred primarily along the prism boundaries. In regions of decussation, the microstructure promoted microcracking, crack bridging, crack deflection and crack bifurcation. Working in concert, these mechanisms increased the crack growth resistance and resulted in a sensitivity to crack growth ( m) similar to bone and lower than that of human dentin. These mechanisms of toughening were not observed in the crack growth response of the sintered HAp. While enamel is the most highly mineralized tissue of the human body, the microstructural arrangement of the prisms promotes exceptional resistance to crack growth.

A three layer structure model of fluoridated enamel containing CaF 2, Ca(OH) 2 and FAp

Objectives The aim of this study was to develop a molecular-based structural model of human teeth after fluoridation with a commonly used amine fluoride, which is highly significant for understanding the effectiveness of topical fluoridation. Methods This multi method study used XPS, MAS-NMR and Raman-spectroscopy measurements in order to analyze powdered synthetic hydroxylapatite (HAp), powdered human enamel samples and human enamel pieces treated with amine fluoride (Elmex ® fluid) in vitro. Results The results lead to a complete structural characterization of the fluoridation products. A three layer composition of calcium hydroxide, calcium fluoride and an apatite species was identified. Significance The top surface CaF 2 layer acts as a fluoride reservoir and covers a layer of antimicrobial effective Ca(OH) 2. Ca(OH) 2 is a well-known therapeutic agent. However, up to now Ca(OH) 2 has not been described as a reaction product after topical fluoridation. Below the Ca(OH) 2 layer an acid resistant apatite species (FAp) was detected which reached directly into the bulk enamel HAp species. The three layer composition identified helps to understand the influence of fluoride application in the pathogenic mechanisms of tooth decay. Each component in this newly suggested structure model has a specific function, which explains how topical fluoridation of enamel reduces dental caries and influences its pathogenic mechanisms.

Confocal laser scanning microscopic analysis of early plaque formed on resin composite and human enamel.

The purpose of this study was to analyse quantitatively the early bacterial plaque formed on resin composite and human enamel in vivo, using a confocal laser scanning microscope. Test pieces of resin composite and human enamel were retained at the buccal surfaces of the upper first molars of three volunteers for 4, 8 and 24 h to allow plaque formation. Then, the specimens were immersed in propidium iodide in phosphate-buffered saline to stain adherent bacteria and observed with a confocal laser scanning microscope. The ratios of the area occupied by microorganisms to the whole area of the optical field were calculated using a photo-image analysis system. The thickness of the plaque was also measured. Quantitative analysis revealed that the resin composite showed significantly higher bacterial adherence than human enamel throughout the test period. A difference was noticed in the morphology of the bacteria between the two groups. Our findings suggest that resin composite shows higher bacteria adherence during early plaque formation compared with human enamel. In addition, the present findings may suggest a presence of the difference in bacterial composition of plaque in both specimens.

An investigation into fractured surfaces of enamel of modern human teeth: a combined SEM and computer visualisation study

It has long been recognised that the enamel microstructure may hold important information with regards to phylogeny and masticatory biomechanics. Further, the biophysical and adaptive processes involved in enamel formation and in the creation of different microstructures are poorly understood. This lack of understanding is in part due to technical difficulties when visualising the 3D structure of enamel. Using modern visualisation techniques, models of various regions of different modern human teeth were created. Underlying these models are consistent mathematical representations of the interplay between cell-to-cell adhesion, integrity of the advancing enamel front and (potentially decreasing) constraints on the prism course from the dentino-enamel junction (DEJ) to the outer surface. Seven modern human teeth (I 1, 1 lower C, 1 P 4, 1 M 2, 2 M 2 and 1 M 3) were fractured longitudinally and formed the basis for the creation of the models. For validation purposes the teeth were then fractured transversely, thus allowing quantitative comparisons between the prism pathways on the newly fractured transverse plane and the transverse pathways as predicted by the model. It was found that these predictions were fairly accurate provided that (a) the light position with respect to the model corresponds with the beam position with respect to the scanned surface and (b) the path of prisms was carefully reconstructed/extrapolated from SEM in cases where prisms were broken. Given that these predictions were based on the mechanisms governing enamel formation as applied to the model, it is suggested that such theories must be reasonable. In other words, biophysical processes, rather than complicated (genetic) positional information, suffice to create different enamel microstructures. In addition, systematic differences were found in prism deviation from their c-axis in different enamel pieces. Given the nature of these differences it is suggested that enamel formation is not only the result of biophysical processes (proximal causes), but could be due to the structures having been selected for in order to counteract masticatory stress exerted during the lifetime of the species (ultimate causes). As to whether and to what extent this may be the case is not yet clear but it is apparent that computer visualisation does have potential to quantify enamel microstructure and to address such questions. Given its non-destructive nature, computer modelling could have particular relevance for studying fragmented fossilised remains.

Quantitative Transmission Electron Microscopic Study of Dental Plaque - An In Vivo Study with Different Mouthrinses

Only a few studies of dental plaque in transmission electron microscopy (TEM) have been performed. The authors have applied TEM for morphometric analysis of dental plaque. Wearing acrylic splints with bovine enamel pieces on the buccal surface of teeth 36 and 46, 21 volunteers rinsed twice a day with a solution of chlorhexidine digluconate, amine/stannous fluoride, or sodium chloride. After 24, 48, and 72 h each a piece of enamel was taken and quantitatively analyzed by TEM for plaque thickness and composition. Similar results were obtained for plaque thickness after rinsing with chlorhexidine digluconate or amine/stannous fluoride. Numerical differences at the counts of cocci or bacilli after rinsing with chlorhexidine digluconate or amine/stannous fluoride did not always have statistical significance.

The Chernobyl accident: EPR dosimetry on dental enamel of children

The radiation dose on tooth enamel of children living close to Chernobyl has been evaluated by EPR. The sample preparation was reduced to a minimum of mechanical steps to remove a piece of enamel. A standard X-ray tube at low energy was used for additive irradiation. The filtration effect of facial soft tissue was taken into account. The radiation dose for a group of teeth slightly exceeds the annual dose, whereas for another group the dose very much exceeds the annual dose. Since the higher dose is found in teeth whose enamel have much lower EPR sensitivity to the radiation, it can be suggested that for these teeth the native signal could alter the evaluation of the smaller radiation signal.

Dose determination on tooth enamel fragments from two human fossils

The ESR dose values of two human tooth enamel fragments were measured in 10° steps with an automated goniometer. ESR spectra were deconvoluted using four Gaussian peaks. The central region of the spectra is interfered with by at least one additional line which yields significantly lower dose values than the central, apparently axial region. There is a clear relationship between dose and width of the deconvoluted axial peaks which is attributable to incomplete separation between the axial and interfering peaks. A simple model is presented that coherently explains all observations. We conclude that deconvolution is necessary for the estimation of the most likely dose value of enamel pieces.

Adherence, accumulation, and cell division of a natural adherent bacterial population.

Developing dental bacterial plaques formed in vivo on enamel surfaces were examined in specimens from 18 adult volunteers during the first day of plaque formation. An intraoral model placing enamel pieces onto teeth was used to study bacterial plaque populations developing naturally to various cell densities per square millimeter of surface area of the enamel (W. F. Liljemark, C. G. Bloomquist, C. L. Bandt, B. L. Philstrom, J. E. Hinrichs, and L. F. Wolff, Oral Microbiol. Immunol. 8:5-15, 1993). Radiolabeled nucleoside incorporation was used to measure DNA synthesis concurrent with the taking of standard viable cell counts of the plaque samples. Results showed that in vivo plaque formation began with the rapid adherence of bacteria until ca. 12 to 32% of the enamel's salivary pellicle was saturated (ca. 2.5 x 10(5) to 6.3 x 10(5) cells per mm2). The pioneer adherent species were predominantly those of the "sanguis streptococci." At the above-noted density, the bacteria present on the salivary pellicle incorporated low levels of radiolabeled nucleoside per viable cell. As bacterial numbers reached densities between 8.0 x 10(5) and 2.0 x 10(6) cells per mm2, there was a small increase in the incorporation of radiolabeled nucleosides per cell. At 2.5 x 10(6) to 4.0 x 10(6) cells per mm2 of enamel surface, there was a marked increase in the incorporation of radiolabeled nucleosides per cell which appeared to be cell-density dependent. The predominant species group in developing dental plaque films during density-dependent growth was the sanguis streptococci; however, most other species present showed similar patterns of increased DNA synthesis as the density noted above approached 2.5 x 10(6) to 4.0 x 10(6) cells per mm2.