Analysis of the Early Stages and Evolution of Dental Enamel Erosion

Abstract The aim of this study was to evaluate by atomic force microscopy (AFM) the early phases and evolution of dental enamel erosion caused by hydrochloric acid exposure, simulating gastroesophageal reflux episodes. Polished bovine enamel slabs (4x4x2 mm) were selected and exposed to 0.1 mL of 0.01 M hydrochloric acid (pH=2) at 37 ?#61472;?#61616;C using five different exposure intervals (n=1): no acid exposure (control), 10 s, 20 s, 30 s and 40 s. The exposed area was analyzed by AFM in 3 regions to measure the roughness, surface area and morphological surface. The data were analyzed qualitatively. Roughness started as low as that of the control sample, Rrms=3.5 nm, and gradually increased at a rate of 0.3 nm/s, until reaching Rrms=12.5 nm at 30 s. After 40 s, the roughness presented increment of 0.40 nm only. Surface area (SA) increased until 20 s, and for longer exposures, the surface area was constant (at 30 s, SA=4.40 μm2 and at 40 s, SA=4.43 μm2). As regards surface morphology, the control sample presented smaller hydroxyapatite crystals (22 nm) and after 40 s the crystal size was approximately 60 nm. Short periods of exposure were sufficient to produce enamel demineralization in different patterns and the morphological structure was less affected by exposure to hydrochloric acid over 30 s.

Resumo O objetivo deste estudo foi avaliar os estágios iniciais e a evolução da erosão do esmalte dental causado pela exposição ao ácido clorídrico, simulando assim episódios de refluxo gastroesofágico, usando um microscópio de força atômica (AFM). Fragmentos de esmalte bovino planificados e polidos (4x4x2 mm) foram selecionados e exposto a 0,1 mL de ácido clorídrico 0,01 M (pH = 2) a 37 ?#61616;C, utilizando cinco intervalos diferentes de exposição: sem exposição ao ácido (controle) e 10 s, 20 s, 30 s e 40 s. Então, a área exposta foi analisada com AFM em 3 regiões diferentes para mensurar a rugosidade, a área da superfície e a morfologia superficial. Os dados foram analisados qualitativamente. Inicialmente, a rugosidade apresentou valor baixo como a amostra controle, Rrms=3,5 nm, e aumentou gradualmente a uma taxa de 0,3 nm/s, até Rrms= 12,5 nm a 30 s. Após 40 s, a rugosidade apresentou um incremento de apenas 0,40 nm. Área de superfície (SA) aumentou até 20 s, e para exposições mais longas, a área de superfície manteve-se constante (30 s, o SA=4,40 μm2, e em 40 s, a SA=4,43 μm2). Em relação à morfologia superficial, a amostra controle apresentou cristais de hidroxiapatita menores (22 nm), e após 40s o tamanho do cristal era de aproximadamente 60 nm. Períodos curtos de exposição foram suficientes para produzir a desmineralização do esmalte em diferentes padrões e a estrutura morfológica foi menos afetada pela exposição ao ácido clorídrico acima de 30 s.

Analysis of the Early Stages and Evolution of Dental Enamel Erosion.

The aim of this study was to evaluate by atomic force microscopy (AFM) the early phases and evolution of dental enamel erosion caused by hydrochloric acid exposure, simulating gastroesophageal reflux episodes. Polished bovine enamel slabs (4x4x2 mm) were selected and exposed to 0.1 mL of 0.01 M hydrochloric acid (pH=2) at 37 ?#61472;?#61616;C using five different exposure intervals (n=1): no acid exposure (control), 10 s, 20 s, 30 s and 40 s. The exposed area was analyzed by AFM in 3 regions to measure the roughness, surface area and morphological surface. The data were analyzed qualitatively. Roughness started as low as that of the control sample, Rrms=3.5 nm, and gradually increased at a rate of 0.3 nm/s, until reaching Rrms=12.5 nm at 30 s. After 40 s, the roughness presented increment of 0.40 nm only. Surface area (SA) increased until 20 s, and for longer exposures, the surface area was constant (at 30 s, SA=4.40 µm2 and at 40 s, SA=4.43 µm2). As regards surface morphology, the control sample presented smaller hydroxyapatite crystals (22 nm) and after 40 s the crystal size was approximately 60 nm. Short periods of exposure were sufficient to produce enamel demineralization in different patterns and the morphological structure was less affected by exposure to hydrochloric acid over 30 s.

Oral rehabilitation in a patient with special needs / Tratamento reabilitador em paciente especiaL

Cerebral palsy is a disorder caused by central nervous system injuries that can occur during the prenatal, perinatal, or postnatal periods. It is characterized by multiple abnormalities, including impairment of speech, body and motor coordination, balance, intelligence, mastication, and swallowing. Due to abnormal movements of the facial muscles, compounded by impairment of the self-cleansing mechanism of the oral cavity, patients with this condition can develop oral diseases such as caries, periodontal disease, and tooth loss. The aim of this paper is to report a case of a patient with cerebral palsy who presented with absence of the maxillary central incisors, removable prosthesis wear, and oral candidiasis. Impressions of the upper and lower arches and periapical radiographs were obtained. The lateral incisors were found to exhibit root resorption, which contraindicated their use as abutment teeth for fixed prosthodontics. In view of the patient's socioeconomic status and cerebral palsy-related limitations, a resin-bonded fixed partial denture was fabricated and nystatin solution was used for treatment of oral candidiasis. The patient had an esthetically and functionally adequate outcome.

A paralisia cerebral é uma anormalidade causada por lesões no sistema nervoso central que podem ocorrer durante o período pré, peri ou pós-natal. É caracterizada por alterações múltiplas como o comprometimento da fala, da coordenação motora e corporal, do equilíbrio, do intelecto e da mastigação e deglutição. Devido aos movimentos anormais da musculatura facial, juntamente com o comprometimento da função de autolimpeza, o paciente pode apresentar quadros de patologia bucal como a cárie, a doença periodontal e a perda dental. O objetivo deste trabalho foi relatar o caso clínico de um paciente portador de paralisia cerebral com ausência dos incisivos centrais superiores, portador de prótese removível e com um quadro de candidose bucal. Foi realizada a moldagem dos arcos superior e inferior e as radiografias periapicais. Pôde-se observar que os incisivos laterais apresentavam reabsorção radicular, o que contra indicava a sua utilização como pilares para prótese fixa. Devido às condições sócio-econômicas e limitações relacionadas a paralisia cerebral, foi confeccionada uma prótese adesiva e, para a candidose bucal foi instituído o tratamento com solução de Nistatina. O resultado do tratamento foi estética e funcionalmente adequado para o paciente.

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. .

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.

The use of an Er:YAG laser to remove demineralized dentin and its influence on dentin permeability.

The purpose of this study was to analyze, correlate, and compare the demineralization and permeability of dentin remaining after caries removal with either an Er:YAG laser, a bur, or a curette. Thirty human dentin fragments were immersed in a demineralizing solution for 20 days and were randomly divided into three groups (n = 10) for the removal of the demineralized lesion. The groups were G1-Er:YAG laser (200 mJ/6 Hz; noncontact at 12 mm; spot: 0.63 mm), G2-Bur, and G3-Curette. The specimens were then immersed in a 10% copper sulfate solution, then in a 1% dithiooxamide alcoholic solution for 30 min and kept in ammonia vapor for 7 days. Next, the specimens were examined with optical microscopy. The amount of demineralized dentin and the level of copper ion infiltration in the dentin were quantified in µm using Axion Vision software. Data were analyzed with the Kruskal-Wallis test (p < 0.05) and Pearson's Correlation test. The analysis revealed no significant differences between the three caries removal methods in terms of their capacity to remove demineralized tissue (G1: 10.6 µm; G2: 8.4 µm; G3: 11 µm), although the laser removal generated more tissue permeability than the others methods (G1: 17.6 µm; G2: 6.6 µm; G3: 5.5 µm). The correlation between the remaining demineralized dentin and the dentin permeability was moderate for the conventional methods and higher for the Er:YAG laser. It can therefore be concluded that the laser produced an increase in permeability that was directly proportional to the amount of demineralized tissue removal.

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'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.

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 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.

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’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.

A maioria dos estudos que utilizam o laser Nd:YAG com ação preventiva são em dentes permanentes, e são escassos os estudos em dentes decíduos. Desta forma, o objetivo do presente estudo foi avaliar in vitro o efeito do laser Nd: YAG combinado ou não com flúor na resistência ácida do esmalte decíduo após a indução de cárie artificial, através da avaliação de microdureza longitudinal e profundidade da desmineralização. Para tanto, foram selecionados 60 fragmentos de esmalte obtidos a partir da superfície bucal / lingual de molares decíduos irrompidos, os quais foram isolados com esmalte de unha e cera, deixando uma área exposta de 9 mm² na superfície do esmalte. Os espécimes foram divididos aleatoriamente em 6 grupos (n = 10) de acordo com o tipo de tratamento: C- Controle: sem tratamento; APF: aplicação de gel flúor fosfato acidulado 1,23%; FV: aplicação de verniz fluoretado 5%; L: aplicação do Laser Nd:YAG 0,5 W/10 Hz no modo contato; APFL: aplicação de gel flúor fosfato acidulado + Laser Nd:YAG; FVL: aplicação de verniz fluoretado 5% + Laser Nd:YAG. Após os tratamentos, os espécimes foram submetidos a um ciclo de desremineralização para a indução de lesão de cárie artificial. Os dados de microdureza longitudinal (%LMC) foram avaliados pelo teste de Kruskal-Wallis e os dados de profundidade da desmineralização foram avaliados pelos testes ANOVA e Fisher’s LSD (α=5%). Observou-se que os grupos APFL e APF apresentaram menor percentual de perda de dureza (p<0,05). A profundidade de desmineralização foi menor em todos os grupos tratados em comparação com o controle. Em conclusão, o laser Nd: YAG associado ou não com flúor/verniz não foi mais efetivo do que o flúor sozinho para prevenir a desmineralização do esmalte durante o período experimental.

Conhecimento odontológico e comportamento de retorno de escolares em função do tipo de instituição (pública ou privada) / Dental knowledge and attendance of schoolchildren according to the type of institution (public or private)

Objetivo: Avaliar o conhecimento odontologico e comportamento de retorno de escolares em funcao do tipo de instituicao (publica ou privada). Metodo: A amostra foi composta por 800 criancas matriculadas de 5¦ a 8¦ serie, do ensino fundamental. O instrumento de analise baseou-se em um questionario, composto por questoes abertas, tornando possivel a multiplicidade de informacoes, evitando o direcionamento das respostas e a distorcao dos resultados. O seu conteudo abordou questoes relativas ao ultimo retorno, tipo de retorno praticado, importancia do mesmo e conhecimento sobre a carie dental e doenca periodontal. Realizou-se analise estatistica descritiva. Para o estudo da associacao utilizou-se o teste Qui-quadrado (X2), com nivel de significancia de 5%. Resultados: Observou-se diferenca significativa entre os estudantes das diferentes instituicoes com relacao ao tempo (p=0,001) e principal motivo (p=0,001) da ultima visita ao dentista, conhecimento sobre a necessidade de visitar o dentista rotineiramente (p=0,001), sobre a importancia do retorno periodico (p=0,001) e frequencia dos mesmos (p=0,001), sobre a carie dental (p=0,001) e doenca periodontal (p=0,001). Conclusao: Os adolescentes apresentaram conhecimento odontologico e comportamento de retorno distintos, segundo o tipo de instituicao de ensino.

Objective: To evaluate the dental knowledge and attendance of elementary schoolchildren according to the type of institution (public or private). Method: The sample was composed of 800 children from the 5th to 8th grades of the elementary education. The research instrument was a questionnaire composed of open questions referring to the last recall visit, type and importance of the recall visit, and knowledge of dental caries and periodontal disease. Descriptive statistical analysis was done and the chisquared test was used with a significance level of 5%. Results: There was statistically significant difference between the students from the different institutions regarding the time (p=0.001) and main reason (p=0.001) of the last visit to the dentist, knowledge of the need of periodic visits to the dentist (p=0.001), importance (p=0.001) and frequency (p=0.001) of periodic recalls, and knowledge of dental caries (p=0.001) and periodontal disease (p=0.001). Conclusion: The adolescents presented different dental knowledge and attendance, according to the type of teaching institution.

Comparative study of the clinical and anti-microbial efficacy of tongue cleaners

Candida species have frequently been isolated from the oral cavities of a variety of patients, such as elderly people, dentures users,immunocompromised and health patients. Yeasts may be associated with immune response and local factors such as poor oral hygiene. It was evaluated effectiveness of tongue cleaner showing which types would be preferred by patients, changes in tongue coating and in saliva yeasts counting. Thirty patients were selected and randomly distributed into three groups. This crossover blind study evaluated the effect of tongue cleaning using: a plastic and a steel tongue scraper and a nylon soft-bristle toothbrush. All patients were instructed to use the cleaners twice a day for one week (fifteen-day wash-out period). Saliva and tongue coating samples were collected from each patient from each test period, the yeasts were counted by colony forming units per mL (CFU/mL) and the species were identified. The patients were questioned about cleaner preference. An increase in the percentage of patients with no tongue coating after scraping was observed. A reduction in the mean number of Candida species in tongue coating was observed only after nylon soft-bristle toothbrush cleaner. Candida albicans was the prevalent species. Volunteers preferred to the steel tongue scraper(60%). Tongue cleaners reduced the tongue coating and the mean number of salivaÆs yeasts. Degree of tongue coating favors the Candida species colonization.