Effect of resin cement elastic modulus on the biaxial flexural strength and structural reliability of an ultra-thin lithium disilicate glass-ceramic material.

OBJECTIVES: Photo- and dual-polymerized resin-based luting agent was evaluated for elastic moduli effects on ultra-thin lithium disilicate (LD) glass-ceramic strengthening, structural reliability, and stress distribution. MATERIALS AND METHODS: One hundred-sixty LD discs (IPS e.max CAD, Ivoclar/Vivadent) were produced in ultra-thin thicknesses (half with 0.3 mm and the other half with 0.5 mm). The ultra-thin ceramic disks were coated with two different cement types (Variolink Veneer - V and Panavia F 2.0 - P). Two positive control groups were tested following hydrofluoric (HF) acid etching (LDt3, LDt5) and two negative control groups were tested for untreated ceramic (LD 3, LD 5). Biaxial flexural strength (BFS), characteristic strength (σ0) and Weibull modulus (m) were the response variables (n = 20) at the ceramic/resin cement interface (z = 0). Finite element analysis (FEA) was used to calculate maximum principal stress. Data were analyzed using two-way ANOVA, and Tukey's test. Scanning electron microscopy (SEM) was used to analyze the failed specimens using fractography and surface morphology. RESULTS: The BFS of LD at either thickness was not affected by cement types, as also demonstrated by FEA. Structural reliability significantly improved in the positive control group (LDt5). CONCLUSION: The cementation of ultra-thin LD with a resin-cement of varying elastic moduli did not influence BFS. LD surface modification by HF acid-etching increased the reliability. CLINICAL RELEVANCE: Ultra-thin anterior veneer designs made from lithium disilicate have been widely proposed and the apparent success of LD ultra-thin veneers was not influenced by the cement choice in the current studies albeit the elastic moduli luting agents used were of similar values.

Influence of indirect reinforcements on the flexural strength of a thermally activated acrylic resin used for complete dentures / Influência de reforços indiretos na resistência a flexão de uma resina acrílica ativada térmicamente utilizada na confecção de próteses totais

Objective: This research aimed to verify the performance of thermally activated acrylic resin (TAAR) combined with a mix of glass and aramid fibers and/or composite resin of indirect use by a tree point bending test. Material and Methods: Ten samples, with 65 x 10 x 2.5 mm, were prepared for each group (n = 10): CO, control of only TAAR; CR, in which an 60 mm indirect composite resin was polymerized together with the acrylic resin during the thermo-polymerization cycle; SS, in which ceramic glass mixed with aramid fibers cut 60 mm in length were incorporated into the samples; and SC, in which the same fibers were incorporated with addiction of the indirect composite resin. A three point flexural strength test was performed with a universal testing machine with a load of 50KgF at a speed of 5 mm/min in the center of the samples supported by a suitable device. The reinforced face was placed to the tensile side. The statistical one way ANOVA and Tukey tests were made with a significance level of 95%. Results: The mean value for the CO was 60,27 ± 24,18 MPa, for CR it was 38,39±12,75 MPa, for SS it was 79,97±12,75 Mpa and for CS it was 32,40±9,05 MPa. Conclusion: The use of glass and aramid fibers at the base of a TAAR increased the three-point flexural strength, however when indirect composite resin was incorporated, a significant drop of this mechanical property was observed. (AU)

Objetivo: Esta pesquisa teve como objetivo verificar o desempenho de uma resina acrílica ativada termicamente (RAAT) combinada com uma mistura de fibras de vidro e aramida e / ou resina composta de uso indireto por um teste de flexão de três pontos. Material e Métodos: Foram preparadas dez amostras, com 65 x 10 x 2,5 mm, para cada grupo (n = 10): CO, controle com apenas RAAT; CR, em que uma resina composta indireta de 60 mm com polimerizada em conjunto com a resina acrílica durante o ciclo de termopolimerização; SS, em que o vidro cerâmico misturado com fibras de aramida cortadas com 60 mm de comprimento foi incorporado nas amostras; e SC, nas quais as mesmas fibras foram incorporadas em conjunto com a resina composta indireta. O teste de resistência à flexão de três pontos foi realizado em uma máquina de teste universal com uma carga de 50 KgF a uma velocidade de 5 mm/min no centro das amostras suportadas por um dispositivo adequado. A face reforçado foi colocado no lado da tração. Os testes estatísticos one-way ANOVA e Tukey foram feitos com um nível de significância de 95%. Resultados: O valor para o CO foi de 60,27 ± 24,18 MPa, para CR foi de 38,39 ± 12,75 MPa, para SS foi de 79,97 ± 12,75 Mpa e para CS foi de 32, 40 ± 9,05 MPa. Conclusão: o uso de fibras de vidro e aramida na base de uma RAAT aumentou a resistência à flexão de três pontos, no entanto, quando a resina composta indireta foi incorporada, observou-se uma queda significativa dessa propriedade mecânica (AU)

Effect of shear bond strength of metallic orthodontic brackets bonded with and without dental adhesive / Efeito da resistência ao cisalhamento de braquetes ortodônticos unidos com e sem adesivo dentário

Objective: The aim of this study was to evaluate the shear bond strength (SBS) of two materials for bonding orthodontic brackets on dental enamel before and after thermocycling. Material and Methods: Forty bovine incisors were divided into four groups (n=10). All teeth were etched with 35% phosphoric acid (3M Espe). For bonding of the brackets, G1 and G2 received orthodontic composite resin (Fill Magic Ortodôntico) and G3 and G4, an adhesive (ScotchBond) was used before the orthodontic resin Transbond XT (3M Unitek). G1 and G3 were kept at 37ºC for 24h and G2 and G4 were submitted to thermocycling (5000 cycles, at 5ºC - 55ºC) prior to SBS testing, performed by a universal machine (EMIC) at 1 mm/min, with a 50kgf load cell. Results were analyzed with two-way ANOVA, followed by Tukey's test (p=0.05). Adhesive surfaces were evaluated through stereomicroscopy and classified according to the type of failure presented. Results: Surface treatment with dental adhesive presented higher SBS values, regardless thermocycling (G3: 12.01 MPa; G4: 12.36 MPa) and the lowest values occurred in G2 (8.89 MPa). For groups without adhesive and with thermocycling, a higher number of completely adhesive failures between composite and enamel were present. For groups in which dental adhesive was used, regardless thermocycling, the failures were mainly adhesive between composite and the bracket. Conclusion: Surface etching of enamel with 35% phosphoric acid with or without adhesive showed a positive effect on SBS. The application of adhesive on enamel surface contributed to the maintenance of SBS values after thermocycling (AU)

Objetivo: O objetivo desse estudo foi avaliar a resistência ao cisalhamento de dois materiais para fixação de braquetes ortodônticos ao esmalte dentário antes e após a termociclagem. Material e Métodos: Quarenta incisivos bovinos foram divididos em quatro grupos (n=10). Todos os dentes foram condicionados com ácido fosfórico a 35% (3M Espe). Para a fixação dos braquetes, G1 e G2 receberam a resina composta ortodôntica (Fill Magic Ortodôntico) e G3 e G4, um adesivo dentário (ScotchBond) foi usado antes da resina ortodôntica Transbond XT (3M Unitek). G1 e G3 foram mantidos a 37ºC por 24h e G2 e G4 foram submetidos à ciclagem térmica (5000 ciclos, de 5ºC - 55ºC) anterior ao teste de resistência ao cisalhamento, realizado por máquina universal (EMIC) a 1 mm/min, com célula de carga de 50kgf. Os resultados foram analisados com ANOVA 2-fatores, seguida do teste de Tukey (p=0,05). As superfícies adesivas foram avaliadas através de estereomicroscopia e classificadas de acordo com o tipo de falha presente. Resultados: O tratamento de superfície com adesivo dentário apresentou maiores valores de resistência ao cisalhamento, independente da termociclagem (G3: 12,01 MPa; G4: 12,36 MPa) e os menores valores ocorreram para G2 (8,89 MPa). Para os grupos sem adesivo e com termociclagem, o maior número de falhas predominantemente adesivas entre resina composta e esmalte estava presente. Para os grupos em que o adesivo dentário foi utilizado, independente da termociclagem, as falhas foram principalmente adesivas entre resina composta e o braquete. Conclusão: O condicionamento superficial do esmalte com ácido fosfórico a 35% com ou sem adesivo mostrou um efeito positivo sobre a resistência ao cisalhamento. A aplicação de adesivo na superfície do esmalte contribuiu para a manutenção dos valores de resistência ao cisalhamento após a termociclagem. (AU)

Are non-carious cervical lesions more frequent in sleep bruxism patients? / Lesões cervicais não cariosas são mais frequentes em pacientes com bruxismo do sono?

Objective: to verify the frequency in non-carious lesions in patients with and without sleep bruxism and to try to list the occurrence of such lesions in patients with this parafunctional habit. Material and Methods: 67 patients ranging from 18 to 70 years of age, which all signed a free and consent form were evaluated. Patients with neurological diseases and/or partially or totally edentulous were excluded from the study. Bruxism diagnosis was performed using a validated questionnaire based on the combination of at least two positive confirmations of bruxism. Diagnosis of non-carious cervical lesions (NCCL) was performed by a single calibrated examiner, using #5 clinical probe, intraoral mirror and air flow, analyzing all surfaces of the teeth present in the mouth. The lesions were classified as abfraction, abrasion or erosion. Statistical analysis was performed by U MannWhitney test, at 5% level of significance. Results: sixty patients were diagnosed with bruxism (91.3%) and only seven patients (8.7%) did not present this parafuctional habit. Regardless the gender, five patients (10.1%) presented absence of lesions and 62 patients (89.9%) presented some NCCL. 70% presented abfraction, 41% abrasion and no patient presented erosion. Statistical analysis showed a p-value of 0.03, which demonstrated significant statistical difference of NCCL between the groups. Conclusion: a higher frequency of NCCL in patients with bruxism was observed when compared to patients without this parafuction. (AU)

Objetivo: verificar a frequência de lesões não cariosas nos pacientes com e sem bruxismo do sono e tentar relacionar a ocorrência dessas lesões a esse hábito parafuncional. Material e Métodos: foram avaliados 67 pacientes com idade entre 18 e 70 anos, os quais assinaram um termo de consentimento livre e esclarecido. Foram excluídos da pesquisa pacientes com doenças neurológicas e/ou endêntulos parciais ou totais. O diagnóstico de bruxismo foi realizado através de um questionário validado que se baseiam na combinação de pelo menos duas constatações positivas de bruxismo. O diagnóstico das lesões cervicais não cariosas (LCNC) foi realizado por um único examinador calibrado, e observadas mediante utilização de sonda clínica n° 5, espelho clínico intraoral e jato de ar, analisando todas as faces de todos dos dentes presentes em boca. Essas foram classificadas em abfração, abrasão ou erosão. A análise estatística foi realizada pelo teste U de Mann-Whitney para tratamento estatístico com nível de significância de 5%. Resultados: sessenta pacientes foram diagnosticados com bruxismo (91,3%) e apenas sete pacientes (8,7%) não possuíam esse hábito parafuncional. Independente do gênero, cinco pacientes (10,1%) possuíam ausência e sessenta e dois pacientes (89,9%) possuíam presença de alguma LCNC. 70% possuíam abfração, 41% abrasão e nenhum paciente apresentou erosão. O teste estatístico obteve um p-valor igual a 0,03; demostrando uma diferença estatisticamente significativa da presença de LCNC entre os grupos. Conclusão: nota-se que houve uma maior frequência de LCNC em pacientes com bruxismo em comparação ao grupo que não apresentou essa parafunção. (AU)

Scanning Electron Microscopy in modern dentistry research / Microscopia Eletrônica de Varredura na pesquisa odontológica moderna

The purpose of this article was to review the usage of Scanning Electron Microscopy (SEM) in dentistry research nowadays, through a careful and updated literature review. By using the key-words Scanning Electron Microscopy and one of the following areas of research in dentistry (Endodontics, Periodontics and Implant), in international database (PubMed), in the year of 2012 (from January to September), a total of 112 articles were found. This data was tabled and the articles were classified according to the usage of SEM (magnification and type of detector) and if this information was obtained either in the summary or only in the full-text article. A critical review was also performed, with new guidelines regarding the usage of SEM in modern dentistry research

O objetivo deste artigo foi revisar a utilização de Microscopia Eletrônica de Varredura (MEV) na pesquisa odontológica atual, por meio de uma cuidadosa e atualizada revisão de literatura. Utilizando as palavras-chave Microscopia Eletrônica de Varredura e uma das seguintes áreas de pesquisa odontológica (Endodontia, Periodontia e Implante), em uma base de dados internacional (PubMed), no ano de 2012 (de Janeiro a Setembro), um total de 112 artigos foram encontrados. Este dado foi tabelado e os artigos foram classificados conforme a utilização de MEV (aumento e tipo de detector) e se esta informação foi obtida no resumo ou no artigo completo. Uma revisão crítica também foi realizada, com novos direcionamentos relacionados ao uso de MEV na pesquisa odontológica moderna

Effect of sodium bicarbonate on Candida albicans adherence to thermally activated acrylic resin.

The purpose of this study was to evaluate the effect of 5% sodium bicarbonate on the adherence of Candida albicans to thermally activated acrylic resin. Fifty 4 mm(2) specimens of acrylic resin were obtained using a metallic matrix. The specimens received chemical polishing, were sterilized and then immersed in Sabouraud broth, inoculated with Candida albicans standardized suspension. After 24 hours of incubation at 37 degrees Celsius, the specimens were divided into four groups according to the substance used for disinfection (5% sodium bicarbonate, 0.12% digluconate chlorhexidine, vinegar and Corega Tabs). A control group was included, in which distilled water was used. The adhered microorganisms were dispersed, diluted and plated onto culture media to determine the number of colony-forming units (cfu/mL). The results were analyzed through the Mann-Whitney statistical test at the 5% level of significance. Only 0.12% digluconate chlorhexidine and 5% sodium bicarbonate presented a statistically significant difference (p = 0.0010 and p = 0.0156, respectively) compared to the control group, decreasing the number of cfu/mL. However, when the different disinfecting solutions were compared with each other, only 0.12% digluconate chlorhexidine presented a statistically significant difference in the reduction of cfu/mL. It was concluded that although 0.12% digluconate chlorhexidine was more effective in the reduction of Candida albicans adherence values to thermally activated acrylic resin, 5% sodium bicarbonate also proved to be a viable alternative.

Effect of sodium bicarbonate on Candida albicans adherence to thermally activated acrylic resin

The purpose of this study was to evaluate the effect of 5 percent sodium bicarbonate on the adherence of Candida albicans to thermally activated acrylic resin. Fifty 4 mm² specimens of acrylic resin were obtained using a metallic matrix. The specimens received chemical polishing, were sterilized and then immersed in Sabouraud broth, inoculated with Candida albicans standardized suspension. After 24 hours of incubation at 37ºC, the specimens were divided into four groups according to the substance used for disinfection (5 percent sodium bicarbonate, 0.12 percent digluconate chlorhexidine, vinegar and Corega Tabs). A control group was included, in which distilled water was used. The adhered microorganisms were dispersed, diluted and plated onto culture media to determine the number of colony-forming units (cfu/mL). The results were analyzed through the Mann-Whitney statistical test at the 5 percent level of significance. Only 0.12 percent digluconate chlorhexidine and 5 percent sodium bicarbonate presented a statistically significant difference (p = 0.0010 and p = 0.0156, respectively) compared to the control group, decreasing the number of cfu/mL. However, when the different disinfecting solutions were compared with each other, only 0.12 percent digluconate chlorhexidine presented a statistically significant difference in the reduction of cfu/mL. It was concluded that although 0.12 percent digluconate chlorhexidine was more effective in the reduction of Candida albicans adherence values to thermally activated acrylic resin, 5 percent sodium bicarbonate also proved to be a viable alternative.

Análise da rugosidade superficial de diferentes materiais restauradores estéticos após polimento com discos ou pastas abrasivas / Analysis of the superficial roughness of different esthetic restoration materials after burnishing with records or abrasive folders

O objetivo deste estudo foi avaliar a rugosidade superficial de diferentes materiais restauradores estéticos após polimento com discos ou pastas abrasivas. Foram confeccionados 20 espécimes para cada tipo de material restaurador utilizando uma matriz pré-fabricada, resultando nos grupos: PE (Palfique Estelite), DY (Dyract Extra), A1 (A110), QF (QuiXfil) e GR (Grandio). A rugosidade superficial dos espécimes foi padronizada utilizando discos Sof-Lex de granulação alta.Cada grupo foi dividido em dois subgrupos, de acordo com a técnica de polimento. No subgrupo S, foram empregados os discos de lixa Sof-Lex de granulação média, fina e ultrafina. No subgrupo D, foram empregados discos de feltro Diamond Flex associados às pastas de polimento Poli I, Poli II e FotoGloss. A rugosidade superficial foi mensurada com um rugosímetro Penthometer S8P. Os resultados foram analisados pelos testes estatísticos de ANOVA e Tukey (5%), obtendo-se p = 0,00. Os valores de média (± desvio-padrão) medidos em Ra (μm) para cada Grupo/Subgrupo foram: GR/D – 1,72 (± 0,11)a; A1/S – 1,62 (± 0,43)a; QF/D – 1,58 (± 0,09)a; QF/S – 1,01 (± 0,70)b; DY/D – 0,96 (±0,09)b; GR/S – 0,90 (± 0,79)b; DY/S – 0,82 (± 0,29)b; PE/D – 0,72 (± 0,15)b; A1/D – 0,58 (± 0,21)b; PE/S – 0,53 (±0,15)b. As médias acompanhadas das mesmas letras não apresentam diferenças significantes. Concluiu-se que para as resinas compostas PE, GR e QF, os discos Sof-Lex proporcionaram menor rugosidade. Para a resina composta A110, as pastas abrasivas proporcionaram menor rugosidade e para o compômero DY não houve diferença significante entre os métodos de polimento.

The aim of this study was to after evaluate the superficial roughness of different esthetic restoration materials burnishingwith records or abrasive folders. Twenty specimens for each type of resin had been confectioned using a matrixprefabricated, resulting in the groups: PE (Palfique Estelite), DY (Dyract Extra), A1 (A110), QF (QuiXfil) and GR(Grandio). The superficial roughness of specimens was standardized using Sof-Lex records thick granulation. Each groupwas divided in two sub-groups, in accordance with the burnishing technique. In sub-group S, the records of sandpaperSof-Lex of average granulation, fine and ultrafine had been used. In sub-group D, records of felt Diamond Flex had beenused associates to the burnishing folders Poli I, Poli II and FotoGloss. The superficial roughness was mensured with arugosimeter Penthometer S8P. The results had been analyzed by the statistical tests ANOVA and Tukey (5%), resultingin p = 0.00. The values of average (±standard-deviation) measured in Ra (μm) for each Group/Subgroup had been:GR/D – 1.72 (± 0.11)a; A1/S – 1.62 (± 0.43)a; QF/D – 1.58 (± 0.09)a; QF/S – 1.01 (± 0.70)b; DY/D – 0.96 (± 0.09)b;GR/S – 0.90 (± 0.79)b; DY/S – 0.82 (± 0.29)b; PE/D – 0.72 (± 0.15)b; A1/D – 0.58 (± 0.21)b; PE/S – 0.53 (± 0.15)b. Thefollowed averages of the same letters do not present significant differences. It’s concluded that for composite resins PE,GR and QF the Sof-Lex records had provided to minor roughness. For the A110 composite resin, the abrasive folders hadprovided to minor roughness and for compomer DY it did not have significant difference enters the burnishing methods.

Oral lichen planus versus epithelial dysplasia: difficulties in diagnosis.

UNLABELLED: Histopathological diagnosis of oral lichen planus is not easy since some cases of epithelial dysplasia may present traits which are very similar to those from lichen planus. AIM: to compare cell alterations which suggest malignancy present in oral lichen planus with those from epithelial dysplasia. MATERIAL AND METHODS: histological cross-sections of oral lichen planus and dysplasia, dyed by hematoxylin-eosin, were analyzed by means of light microscopy. RESULTS: variance analysis (alpha=5%) revealed a statistically significant difference between the average number of cell alterations in the lichen planus (5.83 + or - 1.61) and epithelial dysplasia (4.46 + or - 1.26). The chi-squared test did not show statistically significant differences between oral lichen planus and epithelial dysplasia in relation to the following cell alterations: increase in nucleus/cytoplasm ratio, nuclear hyperchromatism, irregular chromatin distribution and enlarged nuclei (p>0.05). CONCLUSION: Some cell alterations which suggest malignancy present in the oral lichen planus may also be found in epithelial dysplasia, impairing its diagnosis and, consequently, stressing the importance of following these patients in the long run.

Comparative analysis of cell proliferation ratio in oral lichen planus, epithelialdysplasia and oral squamous cell carcinoma

Background: Although oral lichen planus has been classified by the World Health Organization (WHO) as a potentiallymalignant disorder, such classification is still the target of much controversy. Aim: To evaluate the cellproliferation rate in oral lichen planus, comparing it to the rate observed in epithelial dysplasia and oral squamouscell carcinoma, aiming at indications which might indicate the potential for malignant transformation . Materialand Methods: Twenty-four cases of each lesion were submitted to the streptoavidin-biotin and AgNOR techniqueto evaluate the immunohistochemical expression of PCNA and the mean NORs/nucleus, respectively. Results:Positivity for PCNA was observed in 58.33% of oral lichen planus cases, 83.33% of epithelial dysplasia casesand 91.67% of oral squamous cell carcinoma cases. Chi-squared test showed that the number of positive cases forPCNA was significantly lower in oral lichen planus than in oral squamous cell carcinoma (p<0.05). No significantstatistical difference between oral lichen planus and epithelial dysplasia (p>0.05) and between the epithelial dysplasiaand oral squamous cell carcinoma (p>0.05) was observed. The mean NORs/nucleus in oral lichen planus,epithelial dysplasia and oral squamous cell carcinoma were 1.74±0.32, 2.42±0.62 e 2.41±0.61, respectively. Varianceanalysis (ANOVA) revealed significant statistical difference between oral lichen planus and the other studiedlesions (p<0.05). Conclusion: Oral lichen planus cell proliferation rate was less than in oral epithelial dysplasia andoral squamous cell carcinoma which might explain the lower malignant transformation rate (AU)

Oral lichen planus versus epithelial dysplasia: difficulties in diagnosis / Líquen plano bucal versus displasia epitelial: dificuldades diagnósticas

Histopathological diagnosis of oral lichen planus is not easy since some cases of epithelial dysplasia may present traits which are very similar to those from lichen planus. AIM: to compare cell alterations which suggest malignancy present in oral lichen planus with those from epithelial dysplasia. MATERIAL AND METHODS: histological cross-sections of oral lichen planus and dysplasia, dyed by hematoxylin-eosin, were analyzed by means of light microscopy. RESULTS: variance analysis (alpha=5 percent) revealed a statistically significant difference between the average number of cell alterations in the lichen planus (5.83±1.61) and epithelial dysplasia (4.46±1.26). The chi-squared test did not show statistically significant differences between oral lichen planus and epithelial dysplasia in relation to the following cell alterations: increase in nucleus/cytoplasm ratio, nuclear hyperchromatism, irregular chromatin distribution and enlarged nuclei (p>0.05). CONCLUSION: Some cell alterations which suggest malignancy present in the oral lichen planus may also be found in epithelial dysplasia, impairing its diagnosis and, consequently, stressing the importance of following these patients in the long run.

O diagnóstico histopatológico do líquen plano bucal não é fácil, pois alguns casos de displasia epitelial podem apresentar características bastante semelhantes às do líquen plano. OBJETIVO: Comparar as alterações celulares sugestivas de malignidade presentes no líquen plano bucal com as da displasia epitelial. MATERIAL E MÉTODOS: Cortes histológicos de líquen plano bucal e displasia, corados com hematoxilina-eosina, foram analisados por meio da microscopia de luz. RESULTADOS: A análise de variância (alfa=5 por cento) revelou haver diferença estatisticamente significante entre o número médio de alterações celulares no líquen plano bucal (5,83±1,61) e na displasia epitelial (4,46±1,26). O teste de qui-quadrado não mostrou diferença estatisticamente significante entre o líquen plano bucal e a displasia epitelial em relação às seguintes alterações celulares: aumento da relação núcleo/citoplasma, hipercromatismo nuclear, distribuição irregular da cromatina e núcleos aumentados (p>0,05). CONCLUSÃO: Algumas alterações celulares sugestivas de malignidade presentes no líquen plano bucal também podem ser encontradas na displasia epitelial, dificultando o seu diagnóstico e, consequentemente enfatizando a importância do acompanhamento a longo prazo dos pacientes com a doença.

Comparative analysis of the expression of proliferating cell nuclear antigen, p53, bax, and bcl-2 in oral lichen planus and oral squamous cell carcinoma.

Several epidemiologic studies have shown the malignant transformation potential of oral lichen planus; however, this potential is subject of much controversy. To evaluate the expression of proteins related to the cell proliferation and apoptosis processes in oral lichen planus, we compared oral lichen planus with oral squamous cell carcinoma. Twenty-four cases of each lesion were submitted according to streptavidin-biotin technique to evaluate the immunohistochemical expression of proliferating cell nuclear antigen, p53, bax, and bcl-2 proteins. chi(2) test showed no statistically significant differences between the expression of p53, bax, and bcl-2 in oral lichen planus and oral squamous cell carcinoma (P > .05). However, the expression of proliferating cell nuclear antigen was significantly lower in oral lichen planus than in oral squamous cell carcinoma (P < .05). No statistically significant differences between the expression of p53, bax, and bcl-2 in oral lichen planus and oral squamous cell carcinoma were observed, which may be an evidence of the potential of malignant transformation of oral lichen planus.

Comparative analysis of cell proliferation ratio in oral lichen planus, epithelial dysplasia and oral squamous cell carcinoma.

BACKGROUND: Although oral lichen planus has been classified by the World Health Organization (WHO) as a potentially malignant disorder, such classification is still the target of much controversy. AIM: To evaluate the cell proliferation rate in oral lichen planus, comparing it to the rate observed in epithelial dysplasia and oral squamous cell carcinoma, aiming at indications which might indicate the potential for malignant transformation. MATERIAL AND METHODS: Twenty-four cases of each lesion were submitted to the streptoavidin-biotin and AgNOR technique to evaluate the immunohistochemical expression of PCNA and the mean NORs/nucleus, respectively. RESULTS: Positivity for PCNA was observed in 58.33% of oral lichen planus cases, 83.33% of epithelial dysplasia cases and 91.67% of oral squamous cell carcinoma cases. Chi-squared test showed that the number of positive cases for PCNA was significantly lower in oral lichen planus than in oral squamous cell carcinoma (p<0.05). No significant statistical difference between oral lichen planus and epithelial dysplasia (p>0.05) and between the epithelial dysplasia and oral squamous cell carcinoma (p>0.05) was observed. The mean NORs/nucleus in oral lichen planus, epithelial dysplasia and oral squamous cell carcinoma were 1.74+/-0.32, 2.42+/-0.62 e 2.41+/-0.61, respectively. Variance analysis (ANOVA) revealed significant statistical difference between oral lichen planus and the other studied lesions (p<0.05). CONCLUSION: Oral lichen planus cell proliferation rate was less than in oral epithelial dysplasia and oral squamous cell carcinoma which might explain the lower malignant transformation rate.

Comparative study of cell alterations in oral lichen planus and epidermoid carcinoma of the mouth mucosa.

UNLABELLED: Currently, much is discussed regarding the pre-malignant nature of mouth mucosa lichen planus. AIM: The present study aims at analyzing the alterations found in the epithelial cells present in the oral cavity lichen planus, comparing them to those found in epidermoid carcinoma. MATERIALS AND METHODS: Histological cross-sections of oral lichen planus and epidermoid carcinoma, dyed by hematoxylineosin, were analyzed through light microscopy. RESULT: The most frequently found alterations in oral lichen planus were: an increase in the nucleus/cytoplasm relation (93.33%), nucleus membrane thickness (86.67%) and bi-nucleus or multinucleous (86.67%). The Student t test (alpha=5%) revealed a statistically significant difference between the average number of cell alterations in oral lichen planus (5.87+/-1.57) and in epidermoid carcinoma (7.60+/-1.81). As to the types of alterations, the chi-squared test also revealed statistically significant differences among the lesions assessed in relation to the following cell alterations: nuclear excess chromatism, atypical mitoses, cellular pleomorphism and abnormal cell differentiation (p<0.05). CONCLUSION: Despite the fact that in some cases, some pathologists may make mistakes in the histopathological diagnosis of oral lichen planus, the results obtained in this study show that the alterations present in oral lichen planus differ considerably from those seen in epidermoid carcinoma, thus showing how distinct these two diseases are.

In vitro antibacterial activity of adhesive systems on Streptococcus mutans.

PURPOSE: To evaluate the antibacterial activity of three adhesive systems -- Prime & Bond 2.1 (PB), Clearfil SE Bond (CS) and One Up Bond F (OU) -- on Streptococcus mutans in vitro. MATERIALS AND METHODS: Adherence and agar disk-diffusion tests were performed. For the adherence testing, 40 human enamel specimens (4 mm2) were sterilized and the adhesive sytems were applied (n = 10). The control group did not receive the application of any adhesive system. Specimens were immersed in brain heart infusion broth (BHI) inoculated with S. mutans standardized suspension (10(6) cells/ml) for 48 h at 37 degrees C and 5% CO2. The number of S. mutans cells adhered to each specimen was evaluated by the plating method on BHI agar. For agar disk-diffusion testing, adhesive disks and disks soaked in distilled water (negative control) or 0.2% chlorexidine (positive control) were incubated with S. mutans for 48 h. The diameters of the zones of bacterial inhibition were measured. Adherence data were transformed in logarithms of base 10 (log10). Data were submitted to Kruskal-Wallis and Student-Neuman-Keuls tests at the 5% level of significance. RESULTS: The results of the adherence test showed that One Up Bond F (OU) and Clearfil SE Bond (CS) did not differ significantly from one another, but allowed significantly less adherence than Prime & Bond 2.1 (PB) and control [mean log10 (standard deviation) values: PB 6.10 (0.19); CS primer 4.55 (0.98); OU 4.65 (0.54); control group 6.34 (0.27)]. The disk-diffusion test showed no significant difference between OU (diameter in mm: 3.02 +/- 0.13) and CS (3.0 +/- 0.12), but both were significantly more effective in inhibiting bacterial growth than PB (1.0 +/- 0.10). CONCLUSION: The self-etching systems Clearfil SE Bond and One Up Bond F presented a greater inhibitory effect against S. mutans, also in terms of adherence, than did the conventional system, Prime & Bond 2.1.

alignant potential of oral lichen planus: a meta-analysis: [review] / Potencial de transformação maligna do líquen plano bucal: uma meta-análise: [revisão]

Purpose: Several studies have pointed out the malignant transformation potential of oral lichen planus, yet the findings are controversial. The aim of this study was to evaluate the malignant transformation rate of oral lichen planus. Methods: An electronic search of the literature was performed in the PubMed MEDLINE database using the descriptors "oral lichen planus" and "malignant transformation" from January 1988 to September 2008. Ninety-five articles were retrieved and assessed for inclusion. Only prospective and retrospective studies that reported the oral lichen planus malignant transformation rates were considered, as well as studies that included the number of cases with clear criteria for diagnosis of the disease. From the 24 selected studies, information on clinical presentation and location of the lesions, and subjects' gender and age were recorded. Results: From the total of 11,225 cases of oral lichen planus, 183 (1.63%) developed malignant transformation approximately 6 years after the initial diagnosis. The reticular form was the most common clinical presentation, and the jugal mucosa and tongue were the most frequent locations. However, only the clinical presentation of the disease (atypical forms: atrophic, erosive, "in plaque") and the location of the lesion (tongue) were associated with a higher malignant transformation risk. Conclusion: Epidemiological studies from the last 20 years revealed a malignant transformation rate of 0.27% per year, emphasizing the importance of the clinical follow-up of oral lichen planus patients.

Objetivo: Diversos estudos relatam o potencial de transformação maligna do líquen plano bucal, mas os achados são controversos. O objetivo deste estudo foi avaliar a taxa de transformação maligna do líquen plano bucal. Metodologia: Realizou-se uma busca eletrônica da literatura na base de dados PubMed MEDLINE usando os descritores "oral lichen planus" e "malignant transformation", de janeiro de 1988 a setembro de 2008. Um total de 95 artigos foi obtido, os quais foram avaliados para inclusão. Foram incluídos somente estudos prospectivos e retrospectivos com relato de taxa de transformação maligna de líquen plano bucal, bem como estudos com o número de casos com critérios de diagnóstico para a doença. Dos 24 estudos selecionados, os dados coletados incluíram apresentação clínica e localização anatômica das lesões e idade e gênero dos sujeitos. Resultados: De um total de 11.225 casos de líquen plano bucal, 183 (1,63%) desenvolveram transformação maligna aproximadamente seis anos após o diagnóstico inicial. A forma reticular foi a apresentação clínica mais frequente e a mucosa jugal e lingual as localização mais freqüentes das lesões. Entretanto, somente a apresentação clínica (formas atípicas: atrófica, erosiva, "em placa") e a localização da lesão (língua) foram associados a maior risco de transformação maligna.

Estudo comparativo das alterações celulares no líquen plano e no carcinoma epidermóide bucal / Comparative study of cell alterations in oral lichen planus and epidermoid carcinoma of the mouth mucosa

Atualmente, muito se discute a respeito da natureza pré-maligna do líquen plano bucal. OBJETIVO: O presente trabalho tem como objetivo analisar as alterações das células epiteliais presentes no líquen plano bucal, comparando-as com aquelas observadas no carcinoma epidermóide. MATERIAL E MÉTODO: Cortes histológicos de líquen plano bucal e carcinoma epidermóide, corados com hematoxilina-eosina, foram analisados por meio da microscopia de luz. RESULTADO: As alterações mais frequentemente observadas no líquen plano bucal foram aumento da relação núcleo/citoplasma (93,33 por cento), espessamento da membrana nuclear (86,67 por cento) e bi-ou multinucleação (86,67 por cento). O teste t de Student (alfa=5 por cento) revelou haver diferença estatisticamente significante entre o número médio de alterações celulares no líquen plano bucal (5,87±1,57) e no carcinoma epidermóide (7,60±1,81). Quanto aos tipos de alterações, o teste de qui-quadrado também revelou haver diferença estatisticamente significante entre as lesões avaliadas em relação às seguintes alterações celulares: hipercromatismo nuclear, mitoses atípicas, pleomorfismo celular e diferenciação celular anormal (p<0,05). CONCLUSÃO: Apesar de que, em alguns casos, alguns patologistas possam fazer confusão no diagnóstico histopatológico do líquen plano bucal, os resultados obtidos neste estudo mostram que as alterações presentes no líquen plano bucal diferem consideravelmente daquelas observadas no carcinoma epidermóide, evidenciando o quão distintas são estas duas doenças.

Currently, much is discussed regarding the pre-malignant nature of mouth mucosa lichen planus. AIM: The present study aims at analyzing the alterations found in the epithelial cells present in the oral cavity lichen planus, comparing them to those found in epidermoid carcinoma. MATERIALS AND METHODS: Histological cross-sections of oral lichen planus and epidermoid carcinoma, dyed by hematoxylineosin, were analyzed through light microscopy. RESULT: the most frequently found alterations in oral lichen planus were: an increase in the nucleus/cytoplasm relation (93.33 percent), nucleus membrane thickness (86.67 percent) and bi-nucleus or multinucleous (86.67 percent). The Student t test (alpha=5 percent) revealed a statistically significant difference between the average number of cell alterations in oral lichen planus (5.87±1.57) and in epidermoid carcinoma (7.60±1.81). As to the types of alterations, the chi-squared test also revealed statistically significant differences among the lesions assessed in relation to the following cell alterations: nuclear excess chromatism, atypical mitoses, cellular pleomorphism and abnormal cell differentiation (p<0.05). CONCLUSION: Despite the fact that in some cases, some pathologists may make mistakes in the histopathological diagnosis of oral lichen planus, the results obtained in this study show that the alterations present in oral lichen planus differ considerably from those seen in epidermoid carcinoma, thus showing how distinct these two diseases are.

Microbiological or chemical models of enamel secondary caries compared by polarized-light microscopy and energy dispersive X-ray spectroscopy.

Different secondary caries models may present different results. The purpose of this study was to compare different in vitro secondary caries models, evaluating the obtained results by polarized-light microscopy (PLM), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). Standardized human enamel specimens (n = 12) restored with different materials (Z250 conventional composite resin-CRZ, Freedom polyacid-modified composite resin-CRF, Vitremer resin-modified glass-ionomer-GIV, and Fuji IX conventional glass-ionomer cement-GIF) were submitted to microbiological (MM) or chemical caries models (CM). The control group was not submitted to any caries model. For MM, specimens were immersed firstly in sucrose broth inoculated with Streptococcus mutans ATCC 35688, incubated at 37 degrees C/5% CO(2) for 14 days and then in remineralizing solution for 14 days. For CM, specimens were submitted to chemical pH-cycling. Specimens were ground, submitted to PLM and then were dehydrated, gold-sputtered and submitted to SEM and EDS. Results were statistically analyzed by Kruskall-Wallis and Student-Newman-Keuls tests (alpha = 0.05). No differences between in vitro caries models were found. Morphological differences in enamel demineralization were found between composite resin and polyacid-modified composite resin (CRZ and CRF) and between the resin-modified glass-ionomer and the glass-ionomer cement (GIF and GIV). GIF showed higher calcium concentration and less demineralization, differing from the other materials. In conclusion, the glass-ionomer cement showed less caries formation under both in vitro caries models evaluated.

Influência de agentes desinfetantes sobre a aderência de Staphylococcus aureus em aço inoxidável / Influence of disinfecting agents on the adherence of Staphylococcus aureus on stainless steel

A desinfecção de instrumentais odontológicos pré-lavagem é um procedimento de extrema importância na clínica diária. No entanto, a utilização de soluções desinfetantes não pode alterar a superfície do instrumental odontológico, favorecendo posterior aderência bacteriana. O objetivo deste trabalho foi analisar a aderência de Staphylococcus aureus antes e apósa ciclagem por 28 dias com diferentes soluções desinfetantes: glutaraldeído a 2%, vinagre a 100% e ácido peracéticoa 0,2%. O grupo controle sofreu ciclagem com água destilada pelo mesmo período. Cinqüenta corpos-de-prova foram esterilizados e submetidos ao teste de aderência antes e após a ciclagem, sendo imersos em caldo infusão cérebro coração e 0,1 mL de suspensão padronizada (106 células/mL) de S. aureus. A seguir, os microrganismos aderidos aos corposde-prova foram dispersos, diluídos e semeados em meio de cultura para determinar o número de unidades formadoras de colônias (UFC/mL). Os dados foram transformados em logarítmo de base 10 e submetidos ao teste estatístico t de Student. Os resultados demonstraram diferenças significantes entre o grupo controle e as soluções desinfetantes, porémo ácido peracético foi o que demonstrou menor aderência de S. aureus pós-ciclagem, seguido do glutaraldeído e vinagre, sem diferenças entre eles, demonstrando que estes desinfetantes podem ser utilizados sem efeitos deletérios na aderência deste microrganismo ao aço inoxidável.