Protection Of Enamel Research Articles

Effect of Fluoridated Dentifrices on Microhardness of Enamel Surface: Invitro Study

, version 17. Result: There was a Decrease in the enamel microhardness of all the enamel blocks after demineralization phase. The greatest recovery in microhardness after treatment with dentifrices belonged to Stannous Fluoride group. Conclusion: Dentifrices can increase protection of dental enamel against erosive challenges and dental caries by increasing the surface microhardness of the enamel and providing a remineralizing effect.

Micro Energy-Dispersive X-Ray Fluoresence Mapping of Enamel and Dental Materials after Chemical Erosion

Energy-dispersive X-ray fluorescence was employed to test the hypothesis that beverage consumption or mouthwash utilization will change the chemical properties of dental materials and enamel mineral content. Bovine enamel samples (n = 45) each received two cavity preparations (n = 90), each pair filled with one of three dental materials (R: nanofilled composite resin; GIC: glass-ionomer cement; RMGIC: resin-modified GIC). Furthermore, they were treated with three different solutions (S: saliva; E: erosion/Pepsi Twist®; or EM: erosion+mouthwash/Colgate Plax®). It was found that mineral loss in enamel was greater in GICE samples than in RE > RMGICE > RMGICEM > REM > GICEM. An increased percentage of Zr was found in REM indicating organic matrix degradation. Dental materials tested (R, GIC, and RMGIC) were not able to protect adjacent enamel from acid erosion by the soft drink tested. The use of mouthwash promoted protection of enamel after erosion by the soft drink. To avoid chemical dissolution by mouthwashes, protection by resin composites with surface sealants is recommended.

Protection of sound enamel and artificial enamel lesions against demineralisation: Caries infiltrant versus adhesive

ObjectiveTo compare the protective potential of a conventional adhesive, a caries infiltrant and a combination of both against acidic challenge in vitro. MethodsOne-hundred-and-fifty discs from bovine lower central incisors were fabricated. Seventy-five samples remained untreated, whereas the other half was subjected to a demineralisation process (14 days, acidic buffer, and pH 5) to create artificial enamel lesions. Specimens were then radioactively irradiated, and each 15 sound and demineralised specimens were treated with a caries infiltrant (Icon, DMG), an unfilled adhesive (Heliobond, IvoclarVivadent) or a combination of infiltrant and adhesive. Specimens treated with the adhesive followed by a flowable composite (TetricEvoFlow, IvoclarVivadent) served as positive control, while untreated specimens served as negative control. All samples were then subjected to lactic acid for 3 weeks at pH 4. Loss of apatite was determined using the radiochemical method of liquid scintillation. Data were statistically analysed by Kruskal–Wallis-test, one-way ANOVA and Scheffe's post hoc tests (p≤.05). ResultsIn both sound enamel and artificial caries lesions, untreated specimens showed the highest rate of apatite loss, whereas enamel treated with the adhesive and the flowable composite showed almost complete protection surface against dissolution. The caries infiltrant, the adhesive and the combination of both were able to decrease enamel dissolution, but the adhesive and the combination of adhesive and infiltrant were more effective than the infiltrant alone. ConclusionWithin the limitations of this in vitro study, the application of an adhesive (alone or in combination with the caries infiltrant) is more effective to protect enamel dissolution than the infiltrant alone.

Collutorio a base di fitocomplessi ed estratti naturali per la protezione contro la demineralizzazione dello smalto

ObjectivesThe purpose of this study was to evaluate the enamel protection induced by a new mouthwash containing phytocomplexes and natural extracts against acid attacks. Materials and methodsSixteen pairs of enamel fragments obtained from healthy human teeth were used in this study and treated with mouthwash or with deionized water. Ultraviolet/visible (UV/vis) spectrophotometry and SEM ultra-morphological analyses were performed for the evaluation of the enamel protection by the mouthwash after citric and lactic acid challenge. ResultsThe ultraviolet/visible (UV/vis) spectrophotometry and the SEM ultra-morphological analysis showed that the specimens treated with the mouthwash containing Lapacho and Chios Mastic presented no sign of enamel demineralisation. ConclusionsDaily use of this innovative mouthwash may help protect against enamel demineralization caused by bacteria and food.

Residents' journal review

Residents' journal review

Study on the Failure Mechanism of Enamel Coatings in HAZ

Because the enamel coatings has excellent ageing resistance and anti-corrosion performance, the service life of pipeline with enamel coatings as protective layer can be increased remarkably comparing with the ones with organic coatings. But when the pipeline is welded, the high temperature of welding arc will do harm to the bonding strength of the enamel coating and the base metal because of the differences of thermo-physical properties between them. In order to study the failure mechanism of enamel coating in the heat affected zone, the stress changing process of enamel/steel was studied through numerical simulation and the interface of enamel/steel was studied by welding thermal simulation technology. The results show that the weakness parts of the welded joints are the imperfect normalized zone and overheated zone. In the imperfect normalized zone, the micro-cracks generate at the interface of enamel/steel because high stress occurred and some coatings fused incompletely because of short staying time at high temperature that induced micro-cracks in the enamel coating under high welding stress, so it was one of the dangerous zones of HAZ. Because high tensile stress formed during cooling that was dangerous to the brittle enamel coating, the bond layer of enamel/steel was damaged by high temperature of welding and the pores generated at the interface of enamel/steel, the coatings of overheated zone could be pulled off from the base metal easily that caused the steel exposed to the corrosion medium directly without the protection of enamel coating, so it was another dangerous zone of HAZ. Keywords: enamel coating; numerical simulation; welding thermal simulation; failure mechanism; HAZ

In vivo effects of fluoride on enamel permeability

This in vivo study evaluated the effects of topical fluoride application on enamel by repeated scanning electron microscopy analysis of replicas. Baseline fluid droplets were employed as qualitative indication of enamel permeability. CaF(2)-like globules were detected in vivo after fluoride application and were not found after professional brushing, ultrasound action, or chemical extraction. Absence of water permeability of enamel was demonstrated even after removal of CaF(2)-like globules. Droplets reappeared within 1h in sodium fluoride-treated teeth, but they did not reappear even after 1week following topical enamel treatment with acidulated phosphate fluoride. Teeth treated with an acidulate fluoride-free solution showed lack of CaF(2)-like globules and no droplets for at least 1week as detected in acidulate phosphate fluoride-treated teeth. The caries-preventing action of fluoride may be due to its ability to decrease permeability and diffusion pathways. CaF(2)-like globules seem to be indirectly involved in enamel protection over time maintaining an impermeable barrier, and phosphoric acid seemed to play an unexpected fluoride-independent preventive role.

Redução de esmalte interproximal como alternativa no tratamento ortodôntico de casos limítrofes

INTRODUÇÃO: o plano de tratamento ortodôntico deve considerar fatores como apinhamento dentário, protrusão dentoalveolar, discrepâncias maxilares e necessidade de alteração do perfil facial. Também se deve ter em mente as características de normalidade conforme a raça do paciente. Assim, buscando uma abordagem individual do paciente, em casos limítrofes, a terapia ortodôntica pode ser realizada com ou sem extrações. OBJETIVO: realizar uma revisão da literatura sobre a terapia de redução de esmalte interproximal como uma alternativa de tratamento ortodôntico sem extrações para pacientes considerados limítrofes e exemplificar a técnica a partir do relato de um caso clínico. MÉTODOS: para a execução da redução, usou-se brocas Carbide em alta rotação para a remoção do esmalte, discos Sof-Lex para o acabamento e polimento das superfícies desgastadas e aplicação tópica de fluoretos, visando aumentar a proteção do esmalte. CONCLUSÃO: concluiu-se que a técnica é indicada na resolução de discrepâncias no comprimento do arco dentário de até 8,5mm, a fim de evitar as extrações dentárias em pacientes com bom perfil facial. Preferencialmente, os dentes submetidos à técnica devem ser largos, com forma triangular e paredes de esmalte espessas.

Observations on the Effects of Scaling and Polishing Methods on Enamel

This study compared several techniques of manual and power instrument supragingival scaling and subsequent polishing with different methods. Observations were made to determine if there was an optimal method of enamel surface treatment based on the efficacy of the polishing and damage to the enamel. The maxillary fourth premolar and canine teeth were used as experimental teeth. These teeth were extracted after treatment and immersed in 10% buffered formalin solution for further processing and evaluation using electron microscopy. Our observations indicated that the most effective method for scaling and enamel protection during periodontal treatment was provided by power instrumentation followed by polishing using a soft polishing wheel with pumice paste.

Chlorhexidine Efficacy in Preventing Lesion Formation in Enamel and Dentine

Background: Clinical studies on the caries-preventive properties of chlorhexidine mouthrinses are limited and the results are inconclusive. Aim: The aim of this study was to elucidate the contribution of a 0.2% chlorhexidine mouthrinse to the protection of enamel and dentine against demineralization. Methods: In this randomized two-treatment, two-leg study 14 individuals wearing partial prostheses were enrolled. Sound enamel and dentine specimens were placed in situ for 4 weeks. Twice daily, a mouthrinse was performed with either chlorhexidine or saline (control) depending on the experimental group the participant was allocated to. After the experimental period, plaque samples were collected from the surface of the specimens and from natural tooth surfaces to assess the organic acid production upon a sucrose challenge. The specimens were analyzed for mineral loss by transversal microradiography. Results: This study could not demonstrate a significantly better protection of enamel and dentine against demineralization by the chlorhexidine treatment compared to saline. No differences in acid production of plaque samples from the chlorhexidine-treated and control groups were observed. This result was also found for plaque samples originating from the natural tooth surfaces. Conclusion: Mouth rinsing with 0.2% chlorhexidine did not prevent demineralization of dentine and enamel in situ.

Susceptibility of selected tooth‐coloured dental materials to damage by common erosive acids

Erosive substances such as gastric acids, lemon juice and even the less erosive cola drinks have been extensively investigated for their destructive effects on enamel. However, their effects on the tooth-coloured restoratives has not been widely analysed. The objective of this study was to assess their effects on the more commonly used glass containing restorative materials in vitro. Sixty-eight anterior and 24 molar tooth crowns had restorations placed of Fuji IX, Ketac Fil(+), Fuji II LC or Z100, and were painted with nail varnish to leave a 2 mm border around the restorations. Six ceramic crown surfaces were also included. The anterior crowns and porcelain samples were exposed to 0.113% HCl, 5.0% citric acid, 0.02% orthophosphoric acid or DDW for 2, 4, 8 or 16 hours at 37 degrees C. The molar restorations were exposed only for 16 hours. The surfaces of the anterior teeth were then examined by SEM to assess progressive stages of surface erosive etching. Depths of bulk loss of vulnerable restorative materials were measured in the remaining 24 molar teeth, and compared with depths of adjacent enamel loss, particularly at the margins, using Leika Microscope images of sections through these restorations. The traditional glass ionomer cements (GICs) were severely eroded by the HCl and citric acid solutions even following two hours of exposure, with only minor damage from phosphoric acid at the concentration tested. These materials experienced considerable bulk loss by 16 hours, comparable to or greater than that in adjacent enamel. The margins of the GIC restorations experienced greater dissolution than the body of the restorations, particularly in citric acid. Z100 Resin Composite and porcelain restorations showed no effects at all, and Fuji II LC only minor damage. The results demonstrate the effectiveness of porcelain and resin containing materials in providing protection of enamel in advanced cases of erosion. The traditional GIC materials are vulnerable to severe damage in patients experiencing strong citric acid or gastric acid induced erosion. However, there is evidence that protective benefits are still present and these materials should be used but only in closed sandwich restorations in such cases.

Enamel and dentine protection

Enamel and dentine protection

Prevention of Erosion and Abrasion by a High Fluoride Concentration Gel Applied at High Frequencies

The aim of this study was to determine maximum attainable protection of enamel from erosion and erosion abrasion using a highly fluoridated gel with and without additional fluoride from toothpaste. Thirty-six bovine enamel specimens were subjected to six erosive attacks per day (1% citric acid with pH 2.3 for 30 s), while the rest of the day the specimens were in artificial saliva. There were four treatment groups (9 specimens in each group): fluoride-free toothpaste/saliva slurry twice daily (group T0), fluoride-containing toothpaste/saliva slurry twice daily using 1,250 ppm F toothpaste (group TF), fluoride-containing toothpaste/saliva slurry twice per day plus application of a highly fluoridated gel (12,500 ppm F) twice a day for 120 s (group 2F) and a group with gel application 8 times a day (group 8F). Additionally, half of each specimen in all groups was subjected to brushing abrasion during application of the toothpaste/saliva slurry. Brushing abrasion alone led to no observable enamel loss measured with profilometry. After 14 days of cycling of erosion without toothbrushing abrasion, high-fluoride gel application 2 or 8 times daily showed significantly less enamel loss (median 24/19 µm) than with toothpaste with or without fluoride (41/45 µm). After 14 days of cycling of erosion and toothbrushing abrasion, gel application 2 or 8 times daily (33/29 µm) showed significantly less enamel loss than toothpaste with or without fluoride (57/62 µm). We conclude that a highly fluoridated acidic gel is able to protect enamel from erosion and toothbrushing abrasion while fluoridated tooth paste provides little protection.

Análise quantitativa da desmineralização do esmalte dental submetido à ação de dentifrícios fluoretados

<span class="texto">A cárie dental é uma doença multifatorial, caracterizada como um processo dinâmico, originado pelo desequilíbrio nos fenômenos de desmineralização e remineralização. Diversos estudos têm demonstrado que a prevalência de cárie, na maioria dos países, diminuiu nas últimas duas décadas, devido à implementação de programas de saúde pública, ao uso do flúor através da fluoretação das águas de abastecimento e o uso de dentifrícios fluoretados. O flúor contido nos dentifrícios é capaz de reduzir a perda mineral do esmalte dos dentes hígidos e ativar a reposição iônica em unidades com lesões de manchas brancas e com lesões incipientes de cárie. Esses dados justificam o presente estudo, que teve por objetivo determinar, in vitro, o grau de proteção do esmalte dentário humano pelo flúor, nas formas de fluoreto de sódio (NaF) e monofluorfosfato de sódio (MFP), contidos em sete dentifrícios-teste (Colgate Proteção Anticáries (DT1), Trends (DT2), Prevent Antiplaca (DT3), Colgate Antitártaro (DT4), Phillips 2 com Flúor (DT5), Gessy Cristal Juá e Hortelã (DT6) e Colgate Proteção Anticáries Gel (DT7), comparativamente à ação do dentifrício-controle, sem fluoreto, Phillips (DC), frente à queda do pH aos níveis críticos. As taxas do cálcio e do fosfato liberados do esmalte, previamente tratado pelos dentifrícios, foram determinadas através da técnica de espectrometria de emissão atômica, com plasma indutivamente acoplado. Os resultados encontrados revelaram o poder protetor desses produtos, indicando o adequado controle da qualidade industrial. Constatou-se, também, maior proteção do esmalte pelos dentifrícios que contêm fluoreto de sódio, em relação àqueles que continham monofluorfosfato de sódio, e uma correlação negativa entre as taxas do cálcio e do fosfato liberados do esmalte dental humano.</span>

Application of Direct Laminate Veneer for Enamel Protection during Orthodontic Treatment: An In Vivo Evaluation

The aims of this study were to examine the enamel protective effect of a direct laminate veneer against acidic conditions, measure the amount of fluoride released from the veneer and which was taken up by the enamel, as well as evaluate the usefulness of the veneer for orthodontic treatment. First, a veneer was applied to rabbit incisors. Then, apart from using profile measurement microscope and electron probe microanalyzer to measure the roughness and fluoride concentration in the enamel of veneer-covered tooth surface, those of the uncovered adjacent tooth surface were measured too. It was found that the veneer protected the enamel surface from acidic conditions. Furthermore, fluoride ions were taken up by both the uncovered adjacent enamel area as well as by the covered area. These findings suggested that covering the enamel surface with a direct laminate veneer before bracket bonding might be a valuable means of tooth protection and caries prevention.

Sealing smooth enamel surfaces with a newly devised adhesive patch: a radiochemical in vitro analysis

To assess the enamel-protective potential of a newly devised adhesive patch when used as a smooth surface sealant. Eighty enamel discs were prepared from bovine lower central incisors and then irradiated. Twenty specimens were treated with one of three sealing options: enamel bond in a two-step application, the prototype of an adhesive patch, or a flowable resin. Unsealed enamel served as positive controls. Loss of apatite was determined using a radiochemical liquid scintillation method after immersion of the samples in saliva or lactic acid (n=10 per treatment group) each for up to 21 days, during which this experimental and control enamel surfaces were exposed to ten toothbrush strokes per day. Quantitative liquid scintillation data were verified by polarized light microscopy. With lactic acid exposure, a double layer of enamel bonding showed better enamel protection than untreated controls, but was significantly less effective than the adhesive patch or filled composite (P<0.05). No significant differences were noted between the latter two treatments. It was concluded that the adhesive patch under investigation merits further studies to assess its potential as an inter-proximal sealant.

Protective effect of the in situ formed short-term salivary pellicle

Salivary pellicle, as previously investigated, protects the enamel surface after certain processes of maturation against the influence of acidic agents. The aim of the present study was to investigate the protective effect of the short-term salivary pellicle formed in situ over periods of 3, 60 and 120 min. Six human volunteers used intraoral acrylic splints with bovine enamel samples fixed at the buccal and palatal sites of the maxillary first molars and second premolars. Enamel specimens ( n = 252) with and without pellicle were immersed for 60 s in 1.0% citric acid solution under agitation. Knoop surface hardness (KHN) of uneroded polished enamel was measured as a baseline and estimated immediately after erosive treatment reflecting the microhardness loss (ΔKHN). The amounts of calcium dissolved from the eroded enamel surface were analysed by atomic absorption spectroscopy and scored in mg/l per 10 mm 2 of enamel surface area. In addition, the scanning electron microscope was used for the micromorphological examination of the erosive alterations of the enamel surface. The average microhardness loss values after erosion of the enamel samples with buccally/palatally formed pellicle layers were measured as 139.1/144.9 ΔKHN for 3 min pellicle, 145.9/146.9 ΔKHN for 60 min pellicle and 141.7/138.6 ΔKHN for 120 min pellicle. Calcium release values from the specimens with buccal/palatal pellicles were amounted to 15.0/14.9, 16.5/15.9 and 15.3/17.4 mg/l per 10 mm 2 for 3, 60 and 120 min-old pellicles, respectively. No significant differences were related to the pellicle formation time and intraoral site (buccal or palatal) in all tested series (ANOVA, P < 0.05). However, significant protection of the enamel surface provided by the pellicle layer was observed on all pellicle-covered surfaces if compared to the non-covered enamel samples (calcium release: 25.6 mg/l per 10 mm 2; microhardness loss 187.0 ΔKHN). These data were in accordance with the morphologic alterations caused by citric acid on the pellicle-covered and pellicle non-covered specimens. It could be concluded that salivary pellicle formed in situ within a period of 3 min offers protection of enamel against citric acid. However, pellicle does not completely inhibit the erosive action of citric acid under the conditions of the present study.

Ação do fluoreto de dentifrícios sobre o esmalte dentário.

&lt;span class="texto"&gt;A possibilidade de intervir na dissolução do esmalte dentário, diminuindo significativamente a perda de minerais, e de reverter o progresso de lesões cariosas iniciais torna o fluoreto um elemento indispensável à saúde dental. Enquanto recurso preventivo, o fluoreto é uma alternativa de saúde pública bucal extremamente eficaz e de baixo custo. Visando subsidiar a literatura que trata da eficácia do fluoreto de sódio (NaF), do monofluorfosfato de sódio (MFP) e da associação entre o fluoreto de sódio e o monofluorfosfato de sódio (NaF/MFP) que integram os dentifrícios, o presente trabalho teve por objetivo determinar, in vitro, o grau de proteção do esmalte dentário humano, assegurado por estas formas de fluoreto, frente à queda do pH. As taxas do cálcio liberado do esmalte previamente tratado, expressas em mg/dl/20min, revelaram o poder protetor destes fármacos. Os resultados experimentais comprovam que o fluoreto de sódio contido no dentifrício teste revelou maior proteção do esmalte, apesar da menor concentração deste fármaco em relação ao monofluorfosfato de sódio e à associação fluoreto de sódio/ monofluorfosfato de sódio, contidos nos demais. Tais conclusões sugerem a continuidade das experimentações, em face da importância de se obterem respostas eficazes, utilizando-se baixas concentrações da forma de fluoreto, comprovadamente mais efetiva, e de se realizar o controle de qualidade dos mais diversos produtos que são lançados no mercado freqüentemente.&lt;/span&gt;

In situ Fluoride Retention in Enamel and Dentine after the Use of an Amine Fluoride Dentifrice and Amine Fluoride/Sodium Fluoride Mouthrinse

The aim of this in situ investigation was to study the effect of an amine fluoride/sodium fluoride mouthrinse (total F = 250 ppm) in addition to an amine fluoride dentifrice (F = 1,250 ppm) on the amount of acquired fluoride in enamel and dentine. In the partial prosthesis of 12 participants a combined specimen of slightly demineralized enamel and dentine was placed. During two consecutive experiments, each lasting 3 weeks, the participants used an amine fluoride dentifrice alone or in combination with a fluoride mouthrinse. After the in situ period the specimens were retrieved and both the enamel and the dentine specimens were analysed for the amount of KOH–soluble fluoride and structurally bound fluoride. The results showed a significant increase in both KOH–soluble and structurally bound fluoride in enamel and dentine when a fluoride mouthrinse was used. Whether the rinsing procedure was performed immediately after toothbrushing or with a delay of 2 h did not influence the results. Furthermore it was shown that dentine acquired substantially more fluoride than enamel during the experimental period. The results indicate that a fluoride mouthrinse used in addition to a fluoride dentifrice may have a beneficial effect on the protection of enamel and dentine against caries.

Enamel dissolution in relation to fluoride concentrations in the fluid of dental plaque-like layers of precultured Streptococcus sobrinus

Two experiments were conducted to find out what concentration of fluoride (F), when added as NaF to the fluid of an in vitro caries model, would be sufficient for full protection of the underlying enamel during a long (20 or 40 h) fall in ‘plaque’ pH. An existing caries model with bovine enamel and Streptococcus sobrinus ‘plaque’ was employed, while the fluid phase was initially either fully or partially saturated with tricalcium phosphate. In the model with fully saturated and more strongly buffered fluid, a 10 parts/10 6 addition of F to the fluid phase caused no inhibition of the pH fall. In the model with partially saturated and weakly buffered fluid, prevention of the pH fall increased along with increase of added F from 2 to 20 parts/10 6. In each model, the 10 parts/10 6 addition of F was associated with complete prevention of the increase of calcium (Ca) in the fluid phase. In the partially saturated, weakly buffered model, findings on the inorganic P of the fluid phase agreed with findings on Ca. The findings for microhardness of the enamel surface indicated a complete prevention of the enamel softening through the 10 parts/10 6 F additive. Enamel F content was elevated by the fermentation, and even more so when F was added with sugar to the fluid phase. The Ca content of Strep. sobrinus cells was reduced when incubated with sucrose for 40 h and, especially, with sucrose and F. Thus in the second experiment, prevention of the pH fall, the saturation factors, the release of bacterial Ca and the increase of enamel F, all caused or promoted by the 10 parts/10 6 F additive, could jointly contribute to the full enamel protection.