Efeito do ácido clorídrico gasoso no esmalte humano e bovino

Objetivo: Avaliar a ação do ácido clorídrico gasoso sobre o esmalte humano e bovino e comparar o padrão de desmineralização desses substratos expostos ao agente erosivo gasoso. Métodos: Oito espécimes de esmalte bovino e oito de esmalte humano foram obtidos (4 × 4 × 2 mm), metade da superfície foi protegida com resina composta e a outra metade exposta ao ácido clorídrico gasoso (gHCl), pH 2 a 37 °C, por 3 min, 8 vezes ao dia, durante 12 dias, e em intervalos os espécimes foram mantidos em saliva artificial. Os espécimes foram analisados quanto ao perfil de desgaste, rugosidade superficial e microdureza (antes e após a exposição ao ácido). Os dados foram analisados estatisticamente por ANOVA de uma via. Resultados: Os dados não mostraram diferença significativa entre o esmalte bovino e humano para todas as propriedades analisadas – microdureza (98,1 ± 5,2, 96,9 ± 4,8), perfil de desgaste (11,5 ± 2,8, 11,4 ± 3,6) e rugosidade (2,6 ± 0,3, 3,3 ± 0,3), respectivamente. Nas imagens, observou-se que gHCl pode causar erosão do esmalte em ambos os grupos. Conclusão: O ácido clorídrico gasoso causa erosão do esmalte de forma semelhante em bovinos e humanos.Objective: To evaluate the action of gaseous hydrochloric acid on human and bovine enamel and compare the demineralization pattern of these substrates exposed to the gaseous erosive agent. Methods: Eight bovine enamel and eight human enamel specimens were obtained (4 × 4 × 2 mm), half surface was protected with composite resin and the other half was exposed to gaseous hydrochloric acid (gHCl), pH 2 at 37 °C, for 3 min, 8 times a day, for 12 days, and in intervals the specimens were maintained in artificial saliva. The specimens were analyzed according to wear profile, surface roughness and microhardness (before and after acid exposition). Data were statistically analyzed by one-way ANOVA. Results: Data showed no significant difference between bovine and human enamel for all properties analyzed – microhardness (98.1 ± 5.2, 96.9 ± 4.8), wear profile (11.5 ± 2.8, 11.4 ± 3.6) and roughness (2.6 ± 0.3, 3.3 ± 0.3), respectively. In images, we observed that gHCl could cause enamel erosion in both groups. Conclusion: Gaseous hydrochloric acid causes similar enamel erosion on bovine and humans

Effect of Nd:YAG laser combined with fluoride on the prevention of primary tooth enamel demineralization

Most studies dealing with the caries preventive action of Nd:YAG laser have been done in permanent teeth and studies on primary teeth are still lacking. The aim of this study was to evaluate in vitro the effect of Nd:YAG laser combined or not with fluoride sources on the acid resistance of primary tooth enamel after artificial caries induction by assessing longitudinal microhardness and demineralization depth. Sixty enamel blocks obtained from the buccal/lingual surface of exfoliated human primary molars were coated with nail polish/wax, leaving only a 9 mm² area exposed on the outer enamel surface, and randomly assigned to 6 groups (n=10) according to the type of treatment: C-control (no treatment); APF: 1.23% acidulated phosphate fluoride gel; FV: 5% fluoride varnish; L: Nd:YAG laser 0.5 W/10 Hz in contact mode; APFL: fluoride gel + laser; FVL: fluoride varnish + laser. After treatment, the specimens were subjected to a des-remineralization cycle for induction of artificial caries lesions. Longitudinal microhardness data (%LMC) were analyzed by the Kruskal-Wallis test and demineralization depth data were analyzed by oneway ANOVA and Fisher&#8217;s LSD test (á=0.05). APFL and APF groups presented the lowest percentage of microhardness change (p<0.05). Demineralization depth was smaller in all treated groups compared with the untreated control. In conclusion, Nd:YAG laser combined or not with fluoride gel/varnish was not more effective than fluoride alone to prevent enamel demineralization within the experimental period

Evaluation of the association effect of the Er:YAG laser irradiation with fluoride on enamel submitted to the erosion

A erosão dental é uma lesão causada pela dissolução mineral do esmalte, através da ação de ácidos oriundos do suco gástrico ou da alimentação. O objetivo deste estudo foi avaliar a eficácia do laser Er:YAG na prevenção da erosão do esmalte associado ou não ao flúor e avaliar alterações químicas e morfológicas do esmalte após os tratamentos preventivos. Para tanto, foram obtidos 95 espécimes a partir de esmalte bovino (4x4mm), os quais foram planificados, polidos e divididos aleatoriamente em 5 grupos de acordo com os tratamentos preventivos realizados (G1- laser Er:YAG; G2- laser + flúor; G3- flúor + laser; G4- laser simultaneamente flúor; G5- flúor). A metade da superfície do esmalte de cada espécime foi isolada com esmalte cosmético e cera utilidade (área controle) e a outra metade exposta ao tratamento superficial. O laser foi irradiado por 10 segundos, sem refrigeração, modo focado, não contato, 4 mm de distância focal e 60 mJ/cm2 e 2Hz, o gel fluoretado foi aplicado por 4 minutos. O desafio erosivo ocorreu em Coca-Cola à temperatura ambiente, 4x/dia, por 1 minuto, durante 5 dias. O grau de desmineralização do esmalte foi avaliado por meio da microscopia óptica, do desgaste e da microdureza, as alterações químicas e morfológicas através da MEV/EDS. Os dados da microscopia óptica e microdureza foram analisados por meio da Análise de Variância a 1 Critério, para o desgaste foi utilizado o método não-paramétrico Kruskal-Wallis e para a MEV/EDS foi realizada a análise descritiva dos dados. Nos resultados da microscopia óptica observou-se que os grupos 3 e 4, F+L e FeL respectivamente, apresentaram menor desmineralização em relação aos demais grupos, nos resultados do desgaste observou-se que os grupos 4 e 5, FeL e F respectivamente, apresentaram menor desgaste, os grupos 2 e 3 apresentaram maior desgaste e o grupo 1 foi semelhante ao grupo 4. Os resultados de dureza não demonstram diferença estatística entre os grupos, tendo ocorrido diminuição da dureza em relação ao grupo controle, exceto pelo o grupo L. Na análise da EDS o grupo 5 (FeL) apresentou maior retenção de flúor, cerca de 174%, seguido pelos grupos 4 (F) e 3 (F + L), os quais aumentaram o conteúdo de flúor em 27% e 10% respectivamente, os grupos 1 (L) e 2 (L+F) apresentaram diminuição do conteúdo de flúor de 39% e 7,5%, respectivamente. Todos os grupos apresentaram diminuição do conteúdo de Ca e P, exceto o grupo 2 (L+F). Na MEV observou-se áreas ablacionadas. Concluí-se a irradiação laser utilizada simultaneamente à aplicação tópica de flúor foi capaz de promover maior retenção de flúor ao esmalte dental, menor desmineralização e desgaste do esmalte dental, o emprego do flúor isoladamente e do flúor aplicado simultaneamente ao laser proporcionaram menor desgaste do esmalte, o laser Er:YAG promoveu ablação superficial do esmalte quando irradiado com fluência de 60mJ/cm2, 2Hz e sem refrigeração.The dental erosion is a lesion caused by loss of enamel mineral due to the acids action originated from gastric juice or dietary. The aim of this study was to evaluate the effectiveness of the Er:YAG laser on the prevention of enamel erosion associated or not to the fluoride, and to evaluate chemical and morphological changes of enamel after preventive treatments. Thus, 95 bovine enamel samples (4X4 mm) were ground flat, polished and randomly divided into 5 groups according to the preventive treatments: G1- Er:YAG laser; G2- laser + fluoride; G3- fluoride + laser; G4- laser simultaneously fluoride; G5- fluoride. Half of the enamel surface was covered with nail varnish and wax (control area) and the other half exposed to the treatments. The laser was irradiated (focused mode, without water cooling, 10 s, 60 mJ/2Hz and focal distance of 4mm) and the fluoride gel was applied for 4 min. Each specimen was individually exposed to soft drink Coca-Cola 4 times/day, during 1 minute, for 5 days. It was evaluated the enamel demineralization degree (optical microscopy), wear depth (perfilometer) and microhardness. Chemical and morphological alterations were evaluated by SEM/EDS. Optical microscopy and microhardness data were analyzed by one-way ANOVA, for wear depth was used Kruskal-Wallis non-parametric method and for SEM/EDS was performed descriptive data analysis. For optical microscopy, G3 and G4 presented lower demineralization than the other groups; for wear, G4 and G5 exhibited lower values, G2 and G3 presented higher values and G1 did not differ from G4. The microhardness results did not show statistical difference among the groups. Microhardness decreasead in relation to the control group, except for G1. In the EDS analysis, G5 presented higher fluoride retention, about 174%, followed by G4 and G3 which increased the fluoride content in 27% and 10% respectively, G1 and G2 presented decrease of the fluoride content of 39% and 7.5% respectively. All the groups presented decrease of the Ca and P content, except G2. In the MEV, ablated areas were observed. It can be concluded that laser irradiation used simultaneously to the fluoride was able to promote higher fluoride retention to enamel, lower demineralization and wear. The use of the fluoride alone and fluoride applied simultaneously to the laser provided lower wear. The Er:YAG laser caused enamel superficial ablation when irradiated with 60mJ/cm2 fluence, 2 Hz, and without refrigeration

In vitro and in situ analysis of dental erosion and prevention in pacients with gastroesophageal reflux disease

O objetivo deste estudo foi avaliar in vitro o efeito do ácido clorídrico, na forma líquida e gasosa na superfície do esmalte, além de avaliar diferentes tratamentos preventivos e avaliar in situ a influência da Doença do Refluxo Gastroesofágico (DRGE) sobre o esmalte dental e avaliar a eficiência de tratamentos preventivos contra a erosão dental em ambiente bucal. A fase in situ do estudo foi totalmente dependente dos resultados da fase in vitro, ou seja, os tratamentos realizados in situ foram selecionados de acordo coma fase in vitro. Para a fase in vitro, foram obtidos 234 espécimes de esmalte (4X4 mm) a partir de incisivos bovinos, os mesmos foram isolados com resina composta, exceto pela metade da superfície de esmalte a qual foi exposta aos tratamentos preventivos e/ou desafios erosivos. Esta etapa do estudo foi fatorial 3 X 3, tendo como fatores de estudo: Tratamento superficial em 3 níveis: ausência de tratamento (C), laser de CO2 (CO) e laser Nd:YAG (Nd); e a associação à fluoretos em 3 níveis: sem associação (SA), associado ao flúor gel (AF) e associado ao verniz fluoretado (AVF). Os desafios erosivos foram realizados de duas formas, HCl líquido e HCl gasoso. Foram selecionados 180 espécimes tratados (n=10) e distribuídos aleatoriamente. O desafio erosivo com HCl líquido foi realizado sob pH=2, à 37 °C, 6 X ao dia, durante 20s e por 5 dias; o desafio com HCl gasoso foi realizado sob pH=2, à 37 °C, 8 X ao dia, durante 3 min e por 12 dias. A análise foi em função do perfil de desgaste, degrau, perda de volume e rugosidade de superfície. Para a análise das alterações químicas e morfológicas da superfície foram selecionados 54 espécimes divididos aleatoriamente de acordo os tratamentos preventivos propostos e de acordo com as seguintes análises (n=3): DRX e MEV-EDS. Os dados foram submetidos ao teste estatística de análise de variância (ANOVA) a dois critérios, os dados referentes ao DRX e EDS foi avaliado de forma descritiva, as imagens da MEV foram avaliadas qualitativamente. Resultados HCl líquido - observa-se que a associação VF aumentou o perfil de desgaste (médias e desvio padrão: 0,82±0,17) em relação ao C (0,66±0,14), na interação dos fatores C/AVF e Nd/AVF aumentou o perfil de desgaste (0,84±0,21; 0,86±0,12), C (0,70±0,10); a associação VF aumentou a rugosidade (0,26±0,06), C (0,22±0,07), entretanto na interação dos fatores os tratamentos CO e C/AF foram melhores (0,19±0,07; 0,18±0,03), C (0,21±0,07); para o degrau e perda de volume não houve diferença estatística. Resultados HCl gasoso - observou-se que o Nd (1,3±0,08) proporcionou menor perfil de desgaste e Nd/AF(1,8±0,51) maior desgaste, C (1,4±0,16); a associação F e VF proporcionou menor degrau (6,6±4,9; 8,9±3,8), rugosidade (0,35±0,07; 0,37±0,05) e perda de volume (6,0±3,3; 8,3±3,6), C (11,86±4,3; 0,41±0,04; 11,05±4,7; respectivamente). Na análise de EDS houve diminuição do conteúdo de flúor nos tratamentos C, C/AFC/AVF, CO/AVF, Nd/AF e Nd/AVF, proporção Ca/P não foi alterada; para o DRX não observou-se alteração no contudo de flúor. Não observou-se em MEV alteração morfológica. Conclui-se que o ácido clorídrico, na forma líquida e gasosa, causa erosão dental, com comportamentos distintos, para o HCl líquido o tratamento CO/AF produziu menor desgaste, para o HCl gasoso a associação ao F e VF diminuíram o desgaste, os tratamentos não levaram ao aumento do conteúdo de flúor na superfície. A fase in situ contou com a participação de 44 voluntários divididos nos seguintes grupos: Controle- saudável; Suspeita- com erosão dental e sintomas de DRGE; DRGE- diagnosticados com a doença. Foram obtidos 264 espécimes de esmalte bovino (2x2x2 mm), os quais foram impermeabilizados com resina composta, exceto pela metade da superfície de esmalte que foi submetida aos tratamentos preventivos e expostas ao meio bucal. O estudo foi fatorial de 3X2, sendo: Tratamento Superficial em 3 níveis: ausência de tratamento (C), laser de CO2 (CO) e laser Nd:YAG (Nd); e a associação à fluoretos em 2 níveis: sem associação (SA), associado ao flúor gel (AF), em 2 fases de 30 dias com intervalo de 7 dias entre cada fase. Os dados foram submetidos ao teste estatística de análise de variância (ANOVA) a dois critérios. Os resultados foram nulos (0) para o perfil, degrau, perda de volume rugosidade, o grupo CO quando exposto na cavidade bucal levou à formação de trincas na superfície. Conclui-se que o período de 30 dias em meio bucal de pacientes portadores de DRGE são insuficientes para causar erosão no esmalte, os estudos in vitro e in situ apresentam resultados divergentes entre si, sendo necessário mais estudos na área.The aim of this in vitro study was to evaluated hydrochloric acid liquid and gaseous effect on enamel surface and preventive treatments, to evaluated in situ gatroesophageos reflux disease (GERD) effect on dental enamel and prevenvtive treatments. The in situ study was totally dependent on the in vitro results, ie the superficial treatments performed in situ were selected according to the in vitro results. To in vitro study 234 enamel samples (4x4 mm) were obtained from bovine incisors and isolated with the compound resin except half of the enamel surface which was exposed to preventative treatments and erosive challenges. This study was 3 X 3 factorial, study factor: Superficial treatment in 3 levels: no treatment (C), CO2 laser (CO) and Nd:YAG laser (Nd); and fluoride assiciation in 3 levels: swithout (WA), fluoride gel association (FA) and fluoride narnish association (FVA). Erosive challenges were performed using HCl liquid and gaseous. 180 treated specimens were selected (n=10) and randomized. Erosive challenge using HCl liquid - pH=2, 37 °C, 6 times/day, during 20s, for 5 days; erosive challenge using HCl gaseous - pH=2, 37 °C, 8 times/day, during 3 min, for 12 days. It was evaluated wear depth (perfilometer), degree, volume loss and roughness. Chemical and morphological surface analysis was performed, thus 54 specimens were selected randomly divided according preventive treatments (n=3): XRD and SEM-EDS. Data were analyzed by two-way ANOVA, XRD and EDS was performed descriptive data analysis, SEM was analyzed qualitatively. HCl liquid results - FV association presented higher wear depth (menos and standard deviation: 0.82±0.17) compared to C (0.66±0.14), in the interaction between factors C/FVA and Nd/FVA increased wear depth (0.84±0.21; 0.86±0.12), C (0.70±0.10); the association FV increased roughness (0.26±0.06), C (0.22±0.07), the interaction between factors CO and C/FA were better (0.19±0.07; 0.18±0,03), C (0.21±0.07); For degree and volume loss are not significantly different. HCl gaseous results - Nd presented less wear depth (1.3±0.08) and Nd/FA higher wear depth (1.8±0.51), C (1.4±0.16); F and VF association presented less degree (6.6±4.9; 8.9±3.8), roughness (0.35±0.07; 0.37±0.05) and volume loss (6.0±3.3; 8.3±3.6), C (11.86±4.3; 0.41±0.04; 11.05±4.7; respectively). For EDS analysis there was decrease fluoride content after the treatmentos C, C/FA, C/FVA, CO/FVA, Nd/FA e Nd/FVA, ratio Ca/P was not altered; For XRD was not observed fluoride content changes. Was not observed morphological change by SEM. It can be concluded that hydrochloric acid liquid and gaseous promoted dental erosion, for HCl liquid CO/FA promoted less wear depth, for HCl gaseous F and VF association decreased wear depth, the treatments do not alter fluoride contente on enamel surface. For in situ study, 44 volunteers were selectioned and divided into groups: Control- healthy; Suspect- dental erosion and GERD symptoms; GERD- with disease diagnosis. Were obtained 264 specimens from bovine incisors (2x2x2 mm), which were isolated with the compound resin except half of the enamel surface which was exposed to preventative treatments and oral cavity exposed. The study was factorial 3X2: Superficial treatments in 3 levels: no treatment (C), CO2 laser (CO) and Nd:YAG laser (Nd); and fluoride association in 2 evels: without association (WA) and fluoride gel association (FA),in 2 phases of 30 days and 7-day interval between each phase. Data were analyzed by two-way ANOVA. The results were null (0) foro wear depth, degree, volume loss and roughness, the CO group exposed to oral cavity promoted superficial cracks. It can be concluded that 30-day period in the oral environment are insufficient to cause enamel erosion in GERD patients, in vitro studies and in situ show divergent results among themselves, more studies are needed

A castor oil-containing dental luting agent: effects of cyclic loading and storage time on flexural strength

Favorable results in the use of castor oil polyurethane (COP) as pulp capping, membrane material, sealer, mouthwash and in bone repair, associated with the fact that Ricinus communis is not derived from petroleum and it is abundant in Brazil, encourage researches in the development of luting agents. Objectives This study compared the flexural strength (FS) of a castor oil-containing dental luting agent with a weight percentage of 10% (wt%) of calcium carbonate (COP10) with RelyX ARC (RX) after mechanical cycling (MC) and distilled water storage. Material and Methods Sixty-four specimens (25x2x2 mm) were fabricated and divided into two groups, COP10 and RX (control). Each group was divided into 4 subgroups (n=8) according to the storage time, 24 hours (24 h) or 60 days (60 d), and the performance (MC+FS) or not (only FS) of the mechanical cycling test. The FS (10 kN; 0.5 mm/min) and MC tests (10,000 cycles, 5 Hz, 0.5 mm/min) were carried out using an MTS-810 machine. The data were analyzed using ANOVA (α=0.05). Results The obtained FS (MPa) values were: COP10 24h- 19.04±2.41; COP10 60d- 17.92±3.54; RX 24h- 75.19±3.43; RX 60d- 88.77±6.89. All the RX specimens submitted to MC fractured, while the values for COP10 after MC were as follows: COP10 24h- 17.90±1.87 and COP10 60d- 18.60±1.60. Conclusions A castor oil-containing dental luting agent with a weight percentage of 10% (wt%) of calcium carbonate is resistant to mechanical cycling without decreases in flexural strength. However, mean COP10 showed only about 25% of the RelyX ARC mean flexural strength

Musculoskeletal disorders in upper limbs in dental students: exposure level to risk factors

Aim: This study assessed the risk factors of undergraduate students to develop musculoskeletal disorders (MSD) in the upper limbs, regarding gender, type of dental clinical procedure, mouth region treated, and the four-handed dentistry practice. Methods: Dental students enrolled in the 8th semester in the Araraquara School of Dentistry, UNESP, Brazil, were photographed while practicing 283 dental procedures. The Rapid Upper Limb Assessment (RULA) method was used to evaluate the working postures of each student. The photographs were evaluated and a final risk score was attributed to each analyzed procedure. The prevalence of risk factors of developing MSD was estimated by point and by 95% confidence interval. The association between the risk factor of developing disorders and variables of interest were assessed by the chi-square test with a significance level of 5%. Results: The risk factors of developing MSD were high, regarding most dental procedures performed by the undergraduate students (score 5: 7.07%, CI95%: 4.08- 10.06%; score 6: 62.54%, CI95%: 56.90-68.18%). There was no significant association between the RULA final score and gender (p=0.559), and type of dental procedure (p=0.205), and mouth regions by arch (p=0.110) or hemi-arch (p=0.560), and the use of four-handed dentistry (p=0.366). Conclusions: It can be concluded that gender, type of dental clinical procedure, mouth region treated, and practice of four-handed dentistry did not influence the risk of developing MSD in the upper limbs among the dental students evaluated; however, they are at a high risk of developing such disorders

Musculoskeletal disorders in upper limbs in dental students: exposure level to risk factors

Aim: This study assessed the risk factors of undergraduate students to develop musculoskeletal disorders (MSD) in the upper limbs, regarding gender, type of dental clinical procedure, mouth region treated, and the four-handed dentistry practice. Methods: Dental students enrolled in the 8th semester in the Araraquara School of Dentistry, UNESP, Brazil, were photographed while practicing 283 dental procedures. The Rapid Upper Limb Assessment (RULA) method was used to evaluate the working postures of each student. The photographs were evaluated and a final risk score was attributed to each analyzed procedure. The prevalence of risk factors of developing MSD was estimated by point and by 95% confidence interval. The association between the risk factor of developing disorders and variables of interest were assessed by the chi-square test with a significance level of 5%. Results: The risk factors of developing MSD were high, regarding most dental procedures performed by the undergraduate students (score 5: 7.07%, CI95%: 4.08-10.06%; score 6: 62.54%, CI95%: 56.90-68.18%). There was no significant association between the RULA final score and gender (p=0.559), and type of dental procedure (p=0.205), and mouth regions by arch (p=0.110) or hemi-arch (p=0.560), and the use of four-handed dentistry (p=0.366). Conclusions: It can be concluded that gender, type of dental clinical procedure, mouth region treated, and practice of four-handed dentistry did not influence the risk of developing MSD in the upper limbs among the dental students evaluated; however, they are at a high risk of developing such disorders

Muskuloskeletal disorders in upper limbs in dental students: exposure level to risk factors

Aim: This study assessed the risk factors of undergraduate students to develop musculoskeletaldisorders (MSD) in the upper limbs, regarding gender, type of dental clinical procedure, mouthregion treated, and the four-handed dentistry practice. Methods: Dental students enrolled in the8th semester in the Araraquara School of Dentistry, UNESP, Brazil, were photographed whilepracticing 283 dental procedures. The Rapid Upper Limb Assessment (RULA) method was usedto evaluate the working postures of each student. The photographs were evaluated and a finalrisk score was attributed to each analyzed procedure. The prevalence of risk factors of developingMSD was estimated by point and by 95% confidence interval. The association between the riskfactor of developing disorders and variables of interest were assessed by the chi-square test witha significance level of 5%. Results: The risk factors of developing MSD were high, regardingmost dental procedures performed by the undergraduate students (score 5: 7.07%, CI95%: 4.08-10.06%; score 6: 62.54%, CI95%: 56.90-68.18%). There was no significant association betweenthe RULA final score and gender (p=0.559), and type of dental procedure (p=0.205), and mouthregions by arch (p=0.110) or hemi-arch (p=0.560), and the use of four-handed dentistry (p=0.366).Conclusions: It can be concluded that gender, type of dental clinical procedure, mouth regiontreated, and practice of four-handed dentistry did not influence the risk of developing MSD in theupper limbs among the dental students evaluated; however, they are at a high risk of developingsuch disorders.(AU)