Luciana Mayumi Hirakata

Maximum occlusal force and medial mandibular flexure in relation to vertical facial pattern: a cross-sectional study.

BackgroundVertical facial pattern may be related to the direction of pull of the masticatory muscles, yet its effect on occlusal force and elastic deformation of the mandible still is unclear. This study tested whether the variation in vertical facial pattern is related to the variation in maximum occlusal force (MOF) and medial mandibular flexure (MMF) in 51 fully-dentate adults.MethodsData from cephalometric analysis according to the method of Ricketts were used to divide the subjects into three groups: Dolichofacial (n = 6), Mesofacial (n = 10) and Brachyfacial (n = 35). Bilateral MOF was measured using a cross-arch force transducer placed in the first molar region. For MMF, impressions of the mandibular occlusal surface were made in rest (R) and in maximum opening (O) positions. The impressions were scanned, and reference points were selected on the occlusal surface of the contralateral first molars. MMF was calculated by subtracting the intermolar distance in O from the intermolar distance in R. Data were analysed by ANCOVA (fixed factors: facial pattern, sex; covariate: body mass index (BMI); alpha = 0.05).ResultsNo significant difference of MOF or MMF was found among the three facial patterns (P = 0.62 and P = 0.72, respectively). BMI was not a significant covariate for MOF or MMF (P > 0.05). Sex was a significant factor only for MOF (P = 0.007); males had higher MOF values than females.ConclusionThese results suggest that MOF and MMF did not vary as a function of vertical facial pattern in this Brazilian sample.

Surface changes in denture soft liners with and without sealer coating following abrasion with mechanical brushing.

AIM To evaluate the surface alterations of soft liners with or without sealer coating following abrasion with mechanical brushing. METHODS Thirty specimens were made of a methacrylate- (Coe-Soft) and a siloxane-based material (Ufi-Gel SC), and 15 received two coatings of surface sealer. The specimens were submitted to a mechanical brushing-dentifrice assay under 200g of force at 250 cycles/min. Mechanical brushing was simulated for a period of 1 (1250 cycles) and 6 months (5000 cycles). Surface roughness (Ra parameter) was measured, and scanning electron microscopy (SEM) images were obtained. Ra data were analysed by anova for repeated measures and Bonferronis test (alpha=0.05). RESULTS Ra increased from baseline to 6 months regardless of sealer coating. At baseline, only Coe-Soft without sealer had a higher Ra than the other groups. After 1 month, the Ra of Coe-Soft with sealer was three-fold higher than the Ra at baseline; the other groups showed no significant increase of Ra. SEM images showed degradation of the soft liners over time, except for the Ufi-Gel SC with sealer, which displayed minimum alteration of surface texture. CONCLUSION Sealer coating reduced the surface degradation of the tested soft liners, but the protective effect was more pronounced for the siloxane-based material.

Surface changes in denture soft liners with and without sealer coating after mechanical brushing abrasion

AIM To evaluate the surface alterations of soft liners with or without sealer coating following abrasion with mechanical brushing. METHODS Thirty specimens were made of a methacrylate- (Coe-Soft) and a siloxane-based material (Ufi-Gel SC), and 15 received two coatings of surface sealer. The specimens were submitted to a mechanical brushing-dentifrice assay under 200g of force at 250 cycles/min. Mechanical brushing was simulated for a period of 1 (1250 cycles) and 6 months (5000 cycles). Surface roughness (Ra parameter) was measured, and scanning electron microscopy (SEM) images were obtained. Ra data were analysed by anova for repeated measures and Bonferronis test (alpha=0.05). RESULTS Ra increased from baseline to 6 months regardless of sealer coating. At baseline, only Coe-Soft without sealer had a higher Ra than the other groups. After 1 month, the Ra of Coe-Soft with sealer was three-fold higher than the Ra at baseline; the other groups showed no significant increase of Ra. SEM images showed degradation of the soft liners over time, except for the Ufi-Gel SC with sealer, which displayed minimum alteration of surface texture. CONCLUSION Sealer coating reduced the surface degradation of the tested soft liners, but the protective effect was more pronounced for the siloxane-based material.

Patient's perception on mini-screws used for molar distalization

OBJETIVO: O objetivo desse estudo foi avaliar e comparar a intensidade de dor, os efeitos colaterais e o desconforto sentido pelo paciente relacionado a colocacao do mini-implante, durante a mecânica e na remocao do mesmo, durante a distalizacao de molares no tratamento ortodontico. METODOS: A amostra foi composta por 30 pacientes adultos com uma media de idade de 30 anos, com maloclusao Classe II subdivisao direita ou esquerda. Um mini-implante foi instalado em cada paciente, no arco superior para conseguir a distalizacao de molar. Os pacientes receberam um questionario a respeito de sua opiniao sobre o tratamento. RESULTADOS: Noventa por cento dos pacientes escolheram colocar os mini-implantes ao inves de realizar extracao de molares (camuflagem ortodontica), fazer o uso de um aparelho extraoral (Aparelho extraoral de Kloehn) ou fazer uso de qualquer outro tratamento alternativo para classe II. A ulcera aftosa foi o efeito colateral com a maior incidencia apos a insercao do mini-implante (30%). O maior desconforto foi sentido durante a infiltracao anestesica (27%), embora 23% relataram nao ter sentido desconforto durante o tratamento. Um total de 83% dos pacientes nao relatou dor durante o tratamento, o que pode ser associado com o grau de satisfacao com o tratamento (100%) e a recomendacao desse procedimento a outros pacientes (100%). CONCLUSAO: Os mini-implantes foram bem aceitos pelos pacientes e foram eficientes para a distalizacao de molares quando utilizados em associacao com o tratamento ortodontico para correcao da maloclusao de Classe II.

Titanium alloy miniscrews for orthodontic anchorage: an in vivo study of metal ion release

PURPOSE: To examine and compare the levels of several metal ions released in the saliva of patients with orthodontic appliances, at different time points before and after insertion of a miniscrew. METHODS: Saliva of patients (n=20) was collected at four time points: before miniscrew placement (T1), 10 minutes (T2), 7 days (T3) and 30 days after miniscrew placement (T4). The salivary samples were analyzed by inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry (ICP-OES). The release of nine different metal ions was observed: titanium (Ti), zinc (Zn), chromium (Cr), nickel (Ni), iron (Fe), copper (Cu), aluminum (Al), Vanadium (V) and cobalt (Co). Data were analyzed by descriptive statistics. Salivary metal concentrations from different time points of miniscrew treatment were compared using Wilcoxon paired tests (a=5%). RESULTS: At time point T4, there was a quantitative increase in the salivary concentration of Cu, Ti, V, Zn, as well as a quantitative decrease in the salivary concentration of Al, Co, Cr, Fe, Ni, when compared with T1. CONCLUSION: It can be concluded that the placement of fixed orthodontic appliances associated with miniscrews does not lead to an increase of salivary metal ion concentrations.

Artificial teeth: evaluation of wear resistance, microhardness and composition

Objective: To evaluate the Knoop hardness, composition, and wear resistance of acrylic-resin artificial teeth exposed to mechanical toothbrushing.Methods: Artificial teeth from three commercial brands - Biotone, Trilux, and Soluut PX - were used. From each brand, 10 teeth were selected for wear evaluation after mechanical brushing, 10 for microhardness testing, and 5 for composition analysis. Specimens underwent 55,000 brushing cycles, under a 200-g load and at a frequency of 250 cycles per minute, using a soft-bristled toothbrush (IndicatorPlus 30, Oral-B) soaked in a 1:1 toothpaste/water slurry (Oral B Pro Saude). Microhardness testing was performed using a 25-g load for 15 seconds in an HMV-2 hardness tester (Shimadzu). The composition of teeth from different brands was determined by scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDS) (Jeol JSM 5800).Results: Wear results after mechanical brushing were compared by means of the paired t-test, whereas those obtained in microhardness testing were compared by ANOVA with Bonferroni correction. There was no statistically significant difference between brands in either trial.Conclusion: Composition analysis revealed that all of the artificial teeth analyzed contain carbon and oxygen. Trilux and Soluut PX brand teeth also contain silicon; however, the presence of filler particles did not result in increased resistance.

Diphosphonate immobilization on hydroxyapatite-coated titanium--method description.

Purpose:The aim of this study was to promote the immobilization of a bone activity biomodulator (diphosphonate) on titanium, commonly used in implant dentistry, to provide a local method of delivering this drug during the osseointegration process. Methods:The implant material used in this study was commercially wrought titanium (Ticp), 99.9 mass%, grade II. From this material, discs of 15 mm diameter and 1 mm thick were fabricated. These discs underwent 3 sequential surface modification processes: (a) acid-etching, (b) hydroxyapatite coating, and (c) immersion in disodium pamidronate solution. Scanning electron microscopy, X-ray fluorescence, and X-ray diffraction analyses were carried out to characterize the surface created. Results:The results of these analyses demonstrate that the acid-etching process, followed by the sintering of hydroxyapatite particles and immersion in a solution of disodium pamidronate were effective for diphosphonate immobilization on the titanium surface. Conclusions:The methodology used in this study allows us to conclude that immersion of hydroxyapatite-coated titanium in a solution of diphosphonate was efficient to promote the immobilization of this drug on the titanium surface.

Cytotoxicity evaluation of orthodontic miniscrews

The aim of this study was to determine the cytotoxicity induced by orthodontic miniscrews as received from manufacturer, after exposure to fluorides, and after exposure to the oral environment. Eighty-four miniscrews from Brazilian manufacturers (SIN, INP, and NEODENT) were divided into seven groups (n=12): G1 – SIN as received from manufacturer; G2 – SIN immersed for fifteen days in NaF 0.05%; G3 – SIN exposed to oral environment; G4 – INP as received from manufacturer; G5 – INP immersed for fifteen days in NaF 0.05%; G6 – Neodent as received from manufacturer; G7 – Neodent immersed for fifteen days in NaF 0.05%. Their cytotoxicity was evaluated by direct and indirect exposure tests using the wild S. cerevisiae. Oxidative stress was also evaluated through colony color assay. The results showed non-significant reduction in cell viability on direct or indirect exposure to miniscrews.

Resistência ao desgaste e rugosidade superficial de dentes artificiais submetidos ao ensaio de atrição

Este estudo avaliou a rugosidade superficial e a resistencia ao desgaste de dentes artificiais de resina acrilica submetidos ao ensaio de atricao. Foram selecionados 10 incisivos centrais superiores e 10 incisivos centrais inferiores de cada marca comercial: Biotone (Dentsply), Trilux (Vipi) e Soluut PX (Kota). As amostras foram submetidas a afericao da rugosidade superficial em rugosimetro (Mitutoyo SJ-201), com velocidade de 0,5 mm/s, por 30 segundos e comprimento de leitura de 0,25 mm; e a mensuracao da altura cervico-incisal utilizando paquimetro digital (MitutoyoDigimaticCaliper); assim como a afericao da massa de cada par de amostras (incisivo superior e inferior) em balanca de precisao (Shimadzu AUW220D), antes e apos o ensaio. Foi utilizada maquina de escovacao mecânica, simulando movimento de atricao entre a superficie vestibular do incisivo superior e a incisal do incisivo inferior. As amostras foram submetidas a 40.000 ciclos, imersas em agua destilada. Nao houve diferenca estatisticamente significante com relacao a rugosidade superficial antes e apos o ensaio de atricao. Todas as marcas comerciais estudadas apresentaram reducao significativa na altura cervico-incisal, mas nao apresentaram reducao de suas massas, exceto Soluut PX. Tambem constatou-se que nao houve diferenca nos valores de rugosidade entre as marcas comerciais.

Impacto do uso de próteses dentárias totais na qualidade de vida de idosos

OBJETIVO: Este trabalho teve como objetivo avaliar as dimensoes psicologicas, fisicas e sociais do impacto do uso de proteses dentarias totais na qualidade de vida de idosos. METODOS: A amostra consistiu de 50 pacientes usuarios de protese total, com idade acima de 60 anos, moradores da cidade de Santa Maria - RS, Brasil. A contribuicao dos pacientes deu-se atraves do preenchimento do Oral Health Impact Profile contendo 14 questoes (OHIP-14 – versao na lingua protuguesa), o qual investiga sete dimensoes relacionadas ao impacto da condicao de saude bucal na qualidade de vida: limitacao funcional, dor fisica, desconforto psicologico, inabilidade fisica, inabilidade psicologica, inabilidade social e incapacidade. Para cada uma das 14 questoes foi utilizada uma escala de 5 pontos, onde a resposta determina o escore de cada questao – quanto mais alto o valor gerado, maior o impacto do aspecto questionado. Os dados coletados foram analisados atraves de estatistica descritiva e comparados atraves do teste de Mann-Whitney (α=0.05). RESULTADOS: Observou-se que dor fisica e o aspecto relacionado ao uso de proteses totais que teve estatisticamente maior impacto na qualidade de vida de idosos, enquanto a inabilidade social e a incapacidade tiveram estatisticamente menor influencia. CONCLUSOES: Conclui-se que o uso de proteses totais tem influencia na qualidade de vida de idosos.