Enamel Surface Changes After Exposure to Bleaching Gels Containing Carbamide Peroxide or Hydrogen Peroxide.

OBJECTIVE This study evaluated the differences in enamel color change, surface hardness, elastic modulus, and surface roughness between treatments with four bleaching gels containing carbamide peroxide (two at 10% and one each at 35%, and 45%) and two bleaching gels containing hydrogen peroxide (two at 40%). METHODS Enamel specimens were bleached and color changes were measured. Color change was calculated using either ΔE or the Bleaching Index (BI). Then, surface hardness, elastic modulus, and surface roughness of the enamel specimens were evaluated. All measurements were performed at baseline and directly after the first bleaching treatment for all carbamide peroxide- and hydrogen peroxide-containing bleaching gels. In addition, final measurements were made 24 hours after each of a total of 10 bleaching treatments for carbamide peroxide bleaching gels, and 1 week after each of a total of three bleaching treatments for hydrogen peroxide bleaching gels. RESULTS After the last bleaching treatment, respective ΔE scores were 17.6 and 8.2 for the two 10% carbamide peroxide gels, 12.9 and 5.6 for the 45% and 35% carbamide peroxide gels, and 9.6 and 13.9 for the two 40% hydrogen peroxide gels. The respective BI scores were -2.0 and -2.0 for the two 10% carbamide peroxide gels, -3.5 and -1.5 for the 45% and 35% carbamide peroxide gels, and -2.0 and -3.0 for the two 40% hydrogen peroxide gels. Each bleaching gel treatment resulted in significant whitening; however, no significant difference was found among the gels after the last bleaching. Whitening occurred within the first bleaching treatments and did not increase significantly during the remaining treatments. Surface hardness significantly decreased after the last bleaching treatment, when 10% carbamide peroxide was used. Furthermore, significant changes in the elastic modulus or surface roughness occurred only after treatment with 10% carbamide peroxide. CONCLUSION All six bleaching gels effectively bleached the enamel specimens independent of their concentration of peroxide. Gels with low peroxide concentration and longer contact time negatively affected the enamel surface.

Comparison of the capacity of enamel matrix derivative gel and enamel matrix derivative in liquid formulation to adsorb to bone grafting materials.

BACKGROUND The use of an enamel matrix derivative (EMD) has been shown to enhance periodontal regeneration (e.g., formation of root cementum, periodontal ligament, and alveolar bone). However, in certain clinical situations, the use of EMD alone may not be sufficient to prevent flap collapse or provide sufficient stability of the blood clot. Data from clinical and preclinical studies have demonstrated controversial results after application of EMD combined with different types of bone grafting materials in periodontal regenerative procedures. The aim of the present study is to investigate the adsorption properties of enamel matrix proteins to bone grafts after surface coating with either EMD (as a liquid formulation) or EMD (as a gel formulation). METHODS Three different types of grafting materials, including a natural bone mineral (NBM), demineralized freeze-dried bone allograft (DFDBA), or a calcium phosphate (CaP), were coated with either EMD liquid or EMD gel. Samples were analyzed by scanning electron microscopy or transmission electron microscopy (TEM) using an immunostaining assay with gold-conjugated anti-EMD antibody. Total protein adsorption to bone grafting material was quantified using an enzyme-linked immunosorbent assay (ELISA) kit for amelogenin. RESULTS The adsorption of amelogenin to the surface of grafting material varied substantially based on the carrier system used. EMD gel adsorbed less protein to the surface of grafting particles, which easily dissociated from the graft surface after phosphate-buffered saline rinsing. Analyses by TEM revealed that adsorption of amelogenin proteins were significantly farther from the grafting material surface, likely a result of the thick polyglycolic acid gel carrier. ELISA protein quantification assay demonstrated that the combination of EMD liquid + NBM and EMD liquid + DFDBA adsorbed higher amounts of amelogenin than all other treatment modalities. Furthermore, amelogenin proteins delivered by EMD liquid were able to penetrate the porous surface structure of NBM and DFDBA and adsorb to the interior of bone grafting particles. Grafting materials coated with EMD gel adsorbed more frequently to the exterior of grafting particles with little interior penetration. CONCLUSIONS The present study demonstrates a large variability of adsorbed amelogenin to the surface of bone grafting materials when enamel matrix proteins were delivered in either a liquid formulation or gel carrier. Furthermore, differences in amelogenin adsorption were observed among NBM, DFDBA, and biphasic CaP particles. Thus, the potential for a liquid carrier system for EMD, used to coat EMD, may be advantageous for better surface coating.

The effect of enamel proteins on erosion.

Enamel proteins form a scaffold for growing hydroxyapatite crystals during enamel formation. They are then almost completely degraded during enamel maturation, resulting in a protein content of only 1% (w/v) in mature enamel. Nevertheless, this small amount of remaining proteins has important effects on the mechanical and structural properties of enamel and on the electrostatic properties of its surface. To analyze how enamel proteins affect tooth erosion, human enamel specimens were deproteinated. Surface microhardness (SMH), surface reflection intensity (SRI) and calcium release of both deproteinated and control specimens were monitored while continuously eroding them. The deproteination itself already reduced the initial SMH and SRI of the enamel significantly (p < 0.001 and p < 0.01). During the course of erosion, the progression of all three evaluated parameters differed significantly between the two groups (p < 0.001 for each). The deproteinated enamel lost its SMH and SRI faster, and released more calcium than the control group, but these differences were only significant at later stages of erosion, where not only surface softening but surface loss can be observed. We conclude that enamel proteins have a significant effect on erosion, protecting the enamel and slowing down the progression of erosion when irreversible surface loss starts to occur.

Effect of bone graft density on in vitro cell behavior with enamel matrix derivative

OBJECTIVES Bone replacement grafting materials play an important role in regenerative dentistry. Despite a large array of tested bone-grafting materials, little information is available comparing the effects of bone graft density on in vitro cell behavior. Therefore, the aim of the present study is to compare the effects of cells seeded on bone grafts at low and high density in vitro for osteoblast adhesion, proliferation, and differentiation. MATERIALS AND METHODS The response of osteoblasts to the presence of a growth factor (enamel matrix derivative, (EMD)) in combination with low (8 mg per well) or high (100 mg per well) bone grafts (BG; natural bone mineral, Bio-Oss®) density, was studied and compared for osteoblast cell adhesion, proliferation, and differentiation as assessed by real-time PCR. Standard tissue culture plastic was used as a control with and without EMD. RESULTS The present study demonstrates that in vitro testing of bone-grafting materials is largely influenced by bone graft seeding density. Osteoblast adhesion was up to 50 % lower when cells were seeded on high-density BG when compared to low-density BG and control tissue culture plastic. Furthermore, proliferation was affected in a similar manner whereby cell proliferation on high-density BG (100 mg/well) was significantly increased when compared to that on low-density BG (8 mg/well). In contrast, cell differentiation was significantly increased on high-density BG as assessed by real-time PCR for markers collagen 1 (Col 1), alkaline phosphatase (ALP), and osteocalcin (OC) as well as alizarin red staining. The effects of EMD on osteoblast adhesion, proliferation, and differentiation further demonstrated that the bone graft seeding density largely controls in vitro results. EMD significantly increased cell attachment only on high-density BG, whereas EMD was able to further stimulate cell proliferation and differentiation of osteoblasts on control culture plastic and low-density BG when compared to high-density BG. CONCLUSION The results from the present study demonstrate that the in vitro conditions largely influence cell behavior of osteoblasts seeded on bone grafts and in vitro testing. CLINICAL RELEVANCE These results also illustrate the necessity for careful selection of bone graft seeding density to optimize in vitro testing and provide the clinician with a more accurate description of the osteopromotive potential of bone grafts.

Enamel matrix derivative and bone grafts for periodontal regeneration of intrabony defects. A systematic review and meta-analysis

OBJECTIVE The aim of the present systematic review and meta-analysis was to assess the clinical efficacy of regenerative periodontal surgery of intrabony defects using a combination of enamel matrix derivative (EMD) and bone graft compared with that of EMD alone. MATERIALS AND METHODS The Cochrane Oral Health Group specialist trials, MEDLINE, and EMBASE databases were searched for entries up to February 2014. The primary outcome was gain of clinical attachment (CAL). Weighted means and forest plots were calculated for CAL gain, probing depth (PD), and gingival recession (REC). RESULTS Twelve studies reporting on 434 patients and 548 intrabony defects were selected for the analysis. Mean CAL gain amounted to 3.76 ± 1.07 mm (median 3.63 95 % CI 3.51-3.75) following treatment with a combination of EMD and bone graft and to 3.32 ± 1.04 mm (median 3.40; 95 % CI 3.28-3.52) following treatment with EMD alone. Mean PD reduction measured 4.22 ± 1.20 mm (median 4.10; 95 % CI 3.96-4.24) at sites treated with EMD and bone graft and yielded 4.12 ± 1.07 mm (median 4.00; 95 % CI 3.88-4.12) at sites treated with EMD alone. Mean REC increase amounted to 0.76 ± 0.42 mm (median 0.63; 95 % CI 0.58-0.68) at sites treated with EMD and bone graft and to 0.91 ± 0.26 mm (median 0.90; 95 % CI 0.87-0.93) at sites treated with EMD alone. CONCLUSIONS Within their limits, the present results indicate that the combination of EMD and bone grafts may result in additional clinical improvements in terms of CAL gain and PD reduction compared with those obtained with EMD alone. The potential influence of the chosen graft material or of the surgical procedure (i.e., flap design) on the clinical outcomes is unclear. CLINICAL RELEVANCE The present findings support the use of EMD and bone grafts for the treatment of intrabony periodontal defects.

Different bacterial models for in vitro induction of non-cavitated enamel caries-like lesions: Microhardness and polarized light miscroscopy analyses

The aim of this study was to compare different bacterial models for in vitro induction of non-cavitated enamel caries-like lesions by microhardness and polarized light microscopy analyses. One hundred blocks of bovine enamel were randomly divided into four groups (n = 25) according to the bacterial model for caries induction: (A) Streptococcus mutans, (B) S. mutans and Lactobacillus acidophilus, (C) S. mutans and L. casei, and (D) S. mutans, L. acidophilus, and L. casei. Within each group, the blocks were randomly divided into five subgroups according to the duration of the period of caries induction (4-20 days). The enamel blocks were immersed in cariogenic solution containing the microorganisms, which was changed every 48 h. Groups C and D presented lower surface hardness values (SMH) and higher area of hardness loss (ΔS) after the cariogenic challenge than groups A and B (P < 0.05). As regards lesion depth, under polarized light microscopy, group A presented significantly lower values, and groups C and D the highest values. Group B showed a higher value than group A (P < 0.05). Groups A and B exhibited subsurface caries lesions after all treatment durations, while groups C and D presented erosion-type lesions with surface softening. The model using S. mutans, whether or not it was associated with L. acidophilus, was less aggressive and may be used for the induction of non-cavitated enamel caries-like lesions. The optimal period for inducing caries-like lesions was 8 days.

Evaluation of different types of enamel conditioning before application of a fissure sealant

The aim of the study was to compare fissure sealant quality after mechanical conditioning of erbium-doped yttrium aluminium garnet (Er:YAG) laser or air abrasion prior to chemical conditioning of phosphoric acid etching or of a self-etch adhesive. Twenty-five permanent molars were initially divided into three groups: control group (n = 5), phosphoric acid etching; test group 1 (n = 10), air abrasion; and test group 2, (n = 10) Er:YAG laser. After mechanical conditioning, the test group teeth were sectioned buccolingually and the occlusal surface of one half tooth (equal to one sample) was acid etched, while a self-etch adhesive was applied on the other half. The fissure system of each sample was sealed, thermo-cycled and immersed in 5% methylene dye for 24 h. Each sample was sectioned buccolingually, and one slice was analysed microscopically. Using specialized software microleakage, unfilled margin, sealant failure and unfilled area proportions were calculated. A nonparametric ANOVA model was applied to compare the Er:YAG treatment with that of air abrasion and the self-etch adhesive with phosphoric acid (α = 0.05). Test groups were compared to the control group using Wilcoxon rank sum tests (α = 0.05). The control group displayed significantly lower microleakage but higher unfilled area proportions than the Er:YAG laser + self-etch adhesive group and displayed significantly higher unfilled margin and unfilled area proportions than the air-abrasion + self-etch adhesive group. There was no statistically significant difference in the quality of sealants applied in fissures treated with either Er:YAG laser or air abrasion prior to phosphoric acid etching, nor in the quality of sealants applied in fissures treated with either self-etch adhesive or phosphoric acid following Er:YAG or air-abrasion treatment.

Effect of Enamel Matrix Derivative Liquid on Osteoblast and Periodontal Ligament Cell Proliferation and Differentiation.

BACKGROUND Enamel matrix derivatives (EMDs) have been used clinically for more than a decade for the regeneration of periodontal tissues. The aim of the present study is to analyze the effect on cell growth of EMDs in a gel carrier in comparison to EMDs in a liquid carrier. EMDs in a liquid carrier have been shown to adsorb better to bone graft materials. METHODS Primary human osteoblasts and periodontal ligament (PDL) cells were exposed to EMDs in both gel and liquid carriers and compared for their ability to induce cell proliferation and differentiation. Alizarin red staining and real-time polymerase chain reaction for expression of genes encoding collagen 1, osteocalcin, and runt-related transcription factor 2, as well as bone morphogenetic protein 2 (BMP2), transforming growth factor (TGF)-β1, and interleukin (IL)-1β, were assessed. RESULTS EMDs in both carriers significantly increased cell proliferation of both osteoblasts and PDL cells in a similar manner. Both formulations also significantly upregulated the expression of genes encoding BMP2 and TGF-β1 as well as decreased the expression of IL-1β. EMDs in the liquid carrier further retained similar differentiation potential of both osteoblasts and PDL cells by demonstrating increased collagen and osteocalcin gene expression and significantly higher alizarin red staining. CONCLUSIONS The results from the present study indicate that the new formulation of EMDs in a liquid carrier is equally as potent as EMDs in a gel carrier in inducing osteoblast and PDL activity. Future study combining EMDs in a liquid carrier with bone grafting materials is required to further evaluate its potential for combination therapies.

How to enamel : being a treatise on the practical enameling of jewelry with hard enamels /

Mode of access: Internet.

Handbook of decorative art in gold, silver, enamel on metal, porcelain and earthenware.

Mode of access: Internet.

Catalogue of a collection of books on old English silver, precious stones, gems, medals, armour, jewellery, enamel, pottery, costume, furniture, and other antiquities, American and foreign /

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