Harmonizing color measurements in dentistry using translucent tooth-colored materials.

BACKGROUND: Since color measurements are relative, the discrepancy among different instruments is alarmingly high. This multicenter study evaluated the effectiveness of instrument calibration and inter-instrument harmonization of different spectrophotometers with the same optical geometry using tooth-colored, translucent dental materials. METHODS: The coordinating center (CC) spectrophotometer was calibrated using the NPL Ceram Series II set. Two sets of 10 specimens, labeled 1 to 10 and I to X (10 mm in diameter and 1 mm thick), were tested at CC and three research sites (RS1, RS2, and RS3) using the same d/8° optical geometry spectrophotometers. Calibration factors were calculated for each material and site to obtain the average calibration factors for sets 1-10, set I-X, and the combination of both. The differences among the non-corrected and corrected reflection values were calculated using CIEDE2000 (DeltaE00) and CIELAB (DeltaEab) color difference formulas and were submitted to ANOVA and Tukey test (α = 0.05). RESULTS: A significant decrease of color differences between non-corrected as compared to corrected measurements was recorded for all CC-RS and RS-RS comparisons. The reduction of DeltaE00 values between non-corrected and corrected for CC-RS1, CC-RS2, and CC-RS3 were 83.1%, 77.2%, and 73.6%, respectively. The corresponding DeltaE00 values for RS1-RS2, RS1-RS3, and RS2-RS3 comparisons, indirectly compared in the experiment, were 84.2%, 82.8%, and 68.5%, respectively. There was a significant reduction of DeltaE00 and DeltaEab color difference for all combined RS pairs and each of three RS pairs, corrected with one of two specimen sets calibration factors separately. CONCLUSIONS: Calibration and harmonization of color measurements in dentistry using tooth-colored, translucent restorative materials significantly decreased measurement discrepancies between the coordinating center and research sites and among pairs of research sites.

Development of Y-TZP/MWCNT-SiO2 nanocomposite for dental protheses.

Y-TZP/MWCNT-SiO2 nanocomposite was synthesized by co-precipitation and hydrothermal treatment methods. After the characterization of the MWCNT-SiO2 powder, specimens were obtained from the synthesized material Y-TZP/MWCNT-SiO2 by uniaxial pressing for a second characterization and later comparison of its optical and mechanical properties with the conventional Y-TZP. The MWCNT-SiO2 was presented in bundles of carbon nanotubes coated by silica (mean length: 5.10 ± 1.34 µm /D90: 6.9 µm). The composite manufactured was opaque (contrast ratio: 0.9929 ± 0.0012) and had a white color with a slightly difference from the conventional Y-TZP (ΔE00: 4.4 ± 2.2) color. The mechanical properties of Y-TZP/MWCNT-SiO2: vickers hardness (10.14 ± 1.27 GPa; p = 0.25) and fracture toughness (4.98 ± 0.30 MPa m1/2; p = 0.39), showed no significant difference from the conventional Y-TZP (hardness: 8.87 ± 0.89; fracture toughness: 4.98 ± 0.30 MPa m1/2). However, for flexural strength (p = 0.003), a lower value was obtained for Y-TZP/MWCNT-SiO2 (299.4 ± 30.5 MPa) when compared to the control Y-TZP (623.7 ± 108.8 MPa). The manufactured Y-TZP/MWCNT-SiO2 composite presented satisfactory optical properties, however the co-precipitation and hydrothermal treatment methods need to be optimized to avoid the formation of porosities and strong agglomerates, both from Y-TZP particles and MWCNT-SiO2 bundles, which lead to a significant decrease in the material flexural strength.

Evaluation of different teaching methodologies by assessing the performance of dentistry students / Avaliação de diferentes metodologias de aprendizagem aferindo o desempenho de estudantes de odontologia

Objective: The aim of this study was to compare the performance of day- and evening-class students in the first semester test of Dental Materials in the School of Dentistry at São José dos Campos - UNESP, who were exposed to traditional lectures (TRAD) and Team-Based Learning (TBL). Material and Methods: The results of Dental Materials first semester test of students, from day and evening classes of 2016 were tabulated and analyzed in this research. The groups formed for the execution of the methodology were randomized using the individual global average of the previous year of the students, and the groups were composed of 6 to 7 members, maintained throughout the course. During the correction of the tests, the subject of each question and the applied methodology (TBL and TRAD) were identified. Responses of each question were graded separately according to the subject for comparison between methodologies. A total of 88 tests were evaluated. The performance was evaluated through a comparison of the average grade of each question, related to a specific learning methodology. The data were submitted to t-test. Results: The students' overall performance was similar when both methodologies were compared. Students from day class presented higher grades with TBL whilst evening class students presented better performance in questions with traditional lectures. Conclusion: Active learning should be further implemented in Brazilian Dental Schools to change students' habits aiming to improve their personal and social skills besides of professional technical knowledge. (AU)

Objetivo: O objetivo deste estudo foi comparar o desempenho de alunos dos turnos diurno e noturno na prova do primeiro semestre da Disciplina Materiais Dentários da Faculdade de Odontologia de São José dos Campos - UNESP, expostos a aulas tradicionais (TRAD) e Aprendizagem Baseada em Equipe (TBL). Material e Métodos: Os resultados da prova dos alunos, dos turnos diurno e noturno de 2016, foram tabulados e analisados. As turmas utilizadas para a execução da pesquisa foram randomizadas utilizando-se a média global individual do ano anterior dos alunos, sendo as turmas compostas de 6 a 7 integrantes, mantidas ao longo do curso. Durante a correção das provas, foram identificados os assuntos de cada questão e a metodologia aplicada (TRAD e TBL). As respostas de cada questão foram graduadas separadamente de acordo com o assunto para comparação entre as metodologias. Um total de 88 testes foi avaliado. O desempenho dos alunos foi avaliado por meio da comparação da nota média de cada questão, relacionada a uma metodologia específica de aprendizagem. Os dados foram submetidos ao teste t. Resultados: O desempenho geral dos alunos foi semelhante quando comparadas as duas metodologias. Os alunos do período diurno apresentaram notas mais altas no tratamento TBL, enquanto os alunos do período noturno apresentaram melhor desempenho nas questões com aulas expositivas tradicionais. Conclusão: A aprendizagem ativa deve ser mais implementada nos cursos de graduação em Odontologia, no Brasil, para melhorar as habilidades pessoais e sociais dos alunos, além de aperfeiçoar o conhecimento técnico profissional dos discentes (AU).

Effect of radiotherapy on the differentiation and osteogenic activity of mesenchymal stem cells on dental implants / Efeito da radioterapia na diferenciação e atividade osteogênica de células-tronco mesenquimais em implantes dentários

Objective: to evaluate the differentiation and gene expression of transcripts related to osteogenesis in a primary culture of Mesenchymal Stem Cells (MSCs) derived from rat femurs submitted to radiotherapy and the installation of pure titanium implants. Material and Methods: fifty-four rats received titanium implants in both femurs and were divided into three groups: Control: implant surgery (C); Implant + immediate irradiation (IrI), and Implant + late irradiation (IrL). Euthanasia occurred 3, 14, and 49 days after surgery. The bone marrow MSCs from the femurs were isolated and cultivated. The cell viability, total protein content, alkaline phosphatase (ALP) activity, and the formation of mineralization nodules and cellular genotoxicity were analyzed. The gene expression of Alkaline Phosphatase (phoA), Collagen 1 (COL1), Runt-related transcription factor 2 (RUNX2), Osterix (OSX), Osteopontin (OPN), Integrin ß1(ITGB1), Bone Sialoprotein (BSP), Osteonectin (SPARC), Osteocalcin (Bglap), Transforming Growth Factor ß-type (TGF-ß), Granulocyte Macrophage Colony Stimulating Factor (GM-CSF), Interleukin-6 (IL-6), Apolipoprotein E (APOE) and Prostaglandin E2 synthase (PGE2) were evaluated by qRT- PCR. Results: ionizing radiation suppresses the gene expression of essential transcripts for bone regeneration, as well as cellular viability, as observed in the IrI and IrL groups. Conclusion: although this can lead to the loss of osseointegration and failure of the implant, the MSCs showed more activity at 49 days than at 3 and 14 days. (AU)

Objetivo: avaliar a diferenciação e expressão gênica de transcritos relacionados à osteogênese em cultura primária de MSCs derivadas de fêmures de ratos submetidos à radioterapia e instalação de implantes de titânio puro. Material e Métodos: cinquenta e quatro ratos receberam implantes de titânio em ambos os fêmures e foram divididos em três grupos: Controle: cirurgia de implante (C); Implante + irradiação imediata (IrI) e Implante + irradiação tardia (IrL). A eutanásia ocorreu 3, 14 e 49 dias após a cirurgia. As MSCs de medula óssea dos fêmures foram isoladas e cultivadas. Foram analisadas a viabilidade celular, teor de proteína total, atividade da fosfatase alcalina (ALP), formação de nódulos de mineralização e genotoxicidade celular. A expressão gênica de Fosfatase Alcalina (phoA), Colágeno 1 (COL1), fator de transcrição relacionado a Runt 2 (RUNX2), Osterix (OSX), Osteopontina (OPN), Integrina ß1 (ITGB1), Sialoproteína Óssea (BSP), Osteonectina (SPARC), Osteocalcina (Bglap), Fator de Crescimento Transformador tipo ß (TGF-ß), Fator Estimulante de Colônia de Granulócitos-Macrófagos (GM-CSF), Interleucina-6 (IL-6), Apolipoproteína E (APOE) e Prostaglandina E2 sintase (PGE2) foram avaliados por qRT-PCR. Resultados: a radiação ionizante suprime a expressão gênica de transcritos essenciais para a regeneração óssea, bem como a viabilidade celular, como observado nos grupos IrI e IrL. Conclusão:embora isso possa levar à perda da osseointegração e falha do implante, as MSCs apresentaram maior atividade aos 49 dias do que aos 3 e 14 dias (AU)

The Effect of a 10-MDP-Based Dentin Adhesive as Alternative for Bonding to Implant Abutment Materials.

Bonding to different dental restorative materials is challenging. This study aimed to evaluate the effect of a 10-MDP-based dentin adhesive on the shear bond strength (SBS) of self-adhesive resin cement (RC) to implant abutment materials. One hundred and twenty specimens were obtained from zirconia (ZO), cobalt-chromium alloy (CoCr), and commercially pure titanium (Ti), which were treated as follows (n = 10): control group-non-treated (CG), 10-MDP-based dentin adhesive (SB), light-cured SB (SB-LC), and zirconia primer (ZP). Blocks of RC were buildup and, after 24 h, were tested for bond strength. Data of SBS (MPa) were submitted to two-way ANOVA and Tukey test (α = 0.05). There was no difference in SBS among materials for CG and ZP, higher SBS were recorded for Ti SB and Ti SB-LC compared to ZO upon the same surface treatments. For the comparisons among treatments, SB-LC showed the highest SBS for CoCr. For ZO and Ti, higher SBS were recorded with SB and SB-LC. No cohesive failures were observed. It was concluded that the surface treatment with 10-MDP-based materials increased the bond strength of the resin cement to abutment materials, which showed to be material dependent.

Effects of staining and artificial aging on optical properties of gingiva-colored resin-based restorative materials.

OBJECTIVES: To evaluate CIEDE2000/CIELAB differences in color (ΔE00/ΔEab), and translucency parameter (ΔTP00/ΔTPab), and gloss of gingiva-colored resin-based restorative materials upon staining/aging. MATERIALS AND METHODS: Disc-shaped, 10 mm in diameter, and 2-mm-thick samples (n = 5/group) were made from giomer (Beautifil II gingiva), oligomer-based (crea.lign GUM gel), CAD/CAM polymethyl-methacrylate-based (IvoBase CAD), PMMA-based (ProBase Hot), and dimethacrylate-based (SR Nexco Paste Gingiva). Color and gloss were recording using a benchtop spectrophotometer and gloss meter, respectively, at baseline (T0), and upon staining in coffee or red wine for 60 (T1) and 120 h (T2), or artificial aging of 150 kJ/m2 (T1) and 300 kJ/m2 (T2). Three-way analysis of variance (materials x staining conditions x time intervals), Tukey's test (α = 0.05), and Pearson's correlation test were used in analytical statistics. RESULTS: CIEDE2000 color differences ranged from 1.0 to 4.4 (coffee), 1.5 to 5.3 (wine), and 0.9 to 2.0 after artificial aging, with ΔE00 values being significantly higher for Beautifil than other materials (p < 0.05). ΔTP00 values ranged from 0.2 to 0.7 and were statistically higher upon staining in wine compared to artificial aging (p < 0.05). Gloss values at T0 were 76.7-87.0. Beautifil exhibited the lowest gloss retention (50.8-60.2%) after staining, compared to > 90% of other materials (p < 0.05). ΔE00/ΔEab and ΔTP00/ΔTPab were positively correlated (p < 0.0001). CONCLUSIONS: Color, translucency, and gloss changes of gingiva-colored restorative materials were material- and staining/aging-dependent. Generally, wine caused greatest changes in color (with IvoBase CAD being the most color stable) and translucency parameter. All materials except Beautifil gingiva II exhibited staining- and aging-dependent gloss retention greater than 90% for all compared time intervals. CLINICAL RELEVANCE: Optical properties of resin-based gingiva-colored restorative materials depend on material, staining/aging conditions, and exposure time. Certain materials should be avoided in individuals with high consumption of red wine and coffee.

New teaching strategies in dentistry: an experience in a Brazilian dental school / Novas estratégias de ensino em Odontologia: experiência em uma universidade brasileira

The need for new teaching-learning strategies stems from the great change society is going through. The so-called digital natives are part of a generation that lives in a hyperactive rhythm making it increasingly difficult to adapt to traditional classrooms. In Dentistry Courses, new strategies and pedagogical tools have been used, suchas active learning methodologies. In this context, the Discipline of Histology of the Dentistry Course has been proposing the use of some innovative pedagogical strategies. This work will present the experience with team-based learning (TBL), which articulates individual (iRAT) and group activities (gRAT), stimulates the application of concepts and can articulate with other methodologies such as flipped classroom, case study and problematization. This study alsoanalysedstudents' performance in iRAT and gRAT with the application of TBLand discussed the results achieved. Itwas conducted by analysingthe scoresof 240 first-year students of the Histology course in 2016, 2017 and 2018. Student scores, individually and in groups, were statistically analysedby the paired student t-test. Comparisons were made between the iRAT and gRAT activities about gender and the full-time and night classes by the one-way ANOVA and Kruskal-Wallis test. All students obtained higher group scores when compared to individual test results (p <0.001). There was no significant difference between sexes and study period. Group performanceexceeds individual performance. From this, it can be inferred that TBL can be a good strategy to use in dentistry, as an interaction between students leads to higher performance and problem-solving capacity (AU).

A necessidade de novas estratégias de ensino-aprendizagem decorre da grande mudança pela qual a sociedade está passando. Os chamados nativos digitais fazem parte de uma geração que vive em um ritmo hiperativo tornando cada vez mais difícil a adaptação às salas de aula tradicionais. Nos cursos de Odontologia, novas estratégias e ferramentas pedagógicas têm sido utilizadas, como metodologias ativas de aprendizagem. Nesse contexto, a Disciplina de Histologia do Curso de Odontologia tem proposto a utilização de algumas estratégias pedagógicas inovadoras. Este trabalho apresentará a experiência com a aprendizagem baseada em equipe (TBL), que articula atividades individuais (iRAT) e em grupo (gRAT), estimula a aplicação de conceitos e pode se articular com outras metodologias como aula invertida, estudo de caso e problematização. Este estudo também analisou o desempenho dos alunos no iRAT egRAT com a aplicação da TBL e discutiu os resultados alcançados. Foi realizado por meio da análise das notas de 240 alunos do primeiro ano do curso de Histologia em 2016, 2017 e 2018. As notas dos alunos, individualmente e em grupos, foram analisadas estatisticamente por meio do teste t-student pareado. As comparações foram feitas entre as atividades iRAT e gRAT sobre gênero e as aulas em período integral e noturno pelo teste ANOVA one waye teste de Kruskal-Wallis. Todos os alunos obtiveram pontuações mais altas do grupo quando comparados aos resultados dos testes individuais (p <0,001). Não houve diferença significativa entre os sexos e o período de estudo. O desempenho do grupo excede o desempenho individual. A partir disso, pode-se inferirque o TBL pode ser uma boa estratégia para uso em odontologia, pois uma interação entre os alunos leva a um maior desempenho e capacidade de resolução de problemas (AU).

Oral squamous cell carcinoma outcome in adolescent/young adult: Systematic review and meta-analysis.

To perform a systematic review focusing on the prognosis of oral cavity squamous cell carcinoma (OSCC) in young patients (≤40 years old) compared to older (>40 years old). Four databases were used in our search strategy. First, all titles were systematically organized using the Covidence platform online. In the second phase, 118 full texts of potentially eligible studies were analyzed by reviewers independently and in pairs. Twelve studies were considered eligible for data extraction. The relapse was higher in the young than in controls (pooled relative risk (RR) = 1.31; 95% CI [1.10-1.56]). The 5-year disease-free survival (DFS) was worse in young group (pooled hazard ratio (HR) = 0.73; 95% CI [0.63-0.85]) but the 5-year overall survival (OS) estimate was similar between the groups (pooled HR = 0.84; 95% CI [0.70-1.00]). While the 5-year OS was similar between groups, the number of relapses and 5-year DFS were worse in patients with OSCC ≤40 years old.

Analysis of bond strength between a nylon reinforcement structure and dental resins.

BACKGROUND: Nylon is a polymer that its use to reinforce dental resins has shown positive results such as increased flexural strength. The aim of this study was to evaluate the bond strength between dental resins and a nylon reinforcement. MATERIAL AND METHODS: Forty cylindrical nylon blocks with 13 x 23 mm with 0.5% by volume of silica and 40 without were made. Half of the samples of each nylon composition were sandblasted with aluminum oxide (50µm) for 3 s (2.8 bar pressure, distance: 20 mm, incidence angle: 90o). On the nylon blocks, cylinders of chemically activated acrylic resin and indirect composite resin were made, with a bonding area of 6,28 mm2. Eight different groups were obtained according to the material used and the surface treatment (n = 10): Acrylic Resin + Nylon; GAS: Acrylic Resin + Nylon with Silica; GAT: Acrylic Resin + Nylon (Al2O3); GAST: Acrylic Resin + Nylon with Silica (Al2O3); GC: Composite Resin + Nylon; GCS: Composite Resin + Nylon with Silica; GCT: Composite Resin + Nylon (Al2O3); GCST: Composite Resin + Nylon with Silica (Al2O3). The shear test was carried out. The Student's and the Kruskal-Wallis test was adopted. RESULTS: There was no statistically difference in the bond strength for nylon with silica for the acrylic resin group. For the composite groups, nylon with silica did not present a statistically difference without surface treatment (p = 0.10) and with surface treatment the bond strength decreased (p = 0.000). The GCT showed a higher bond strength (0.89 MPa). The surface treatment improved the bond strength for the both groups. CONCLUSIONS: The presence of silica in the nylon composition did not influence the bond strength between materials evaluated. However, the surface treatment with aluminum oxide proved to be favorable for this adhesion. Key words:Nylons - Resins, Synthetic - Structures Strengthening - Dental Research.

Effect of Staining and Aging on Translucency Parameter of CAD-CAM Materials.

OBJECTIVES: To evaluate different intervals of exposure to staining solutions and artificial aging on translucency parameter (TP00) of CAD-CAM materials. MATERIAL AND METHODS: One millimeter thick square-shaped specimens (N = 288) were cut from Cerasmart (CS), IPS e.max (IE), Lava Ultimate (LU), Shofu HC (SH), Vita Enamic (VE), and Vita Suprinity (VS) and were divided into laboratory and chairside polishing. Reflection wavelength spectra, CIE D65 standard illuminant, 2 ° standard observer, SCI, UV included, SAV aperture, 6 mm diameter, were recorded at 10 nm sensitivity against white and black calibration tiles using a benchtop spectrophotometer. Subsequently, they were converted into CIEDE 2000 TP00. After baseline measurements (T0), the specimens were divided as follows (n = 8): staining in coffee (C) and wine (W), for 60 (T1) and 120 hours (T2), and accelerated artificial aging (A). Artificial aging (ISO 4892-2 standard) was performed in two cycles of 150 KJ/m2, for T1 and T2, respectively. TP measurements were repeated at T1 and T2. Data of TP00 retention were submitted to analysis of variance and Fisher's PLSD multiple comparison test (α=0.05). RESULTS: Fisher's PLSD critical differences among materials, time intervals and staining/aging were 0.16, 0.11 and 0.11, respectively. SH showed the highest TP00 followed by LU > CS > IE = VS > VE. For all time intervals, the lowest TP00 retention was observed with C. W, and A presented similar values. CONCLUSIONS: Translucency Parameter was a time and staining/aging-dependent material. In majority of cases, it decreased upon staining/aging.

Staining and aging-dependent changes in color of CAD-CAM materials.

STATEMENT OF PROBLEM: Consumption of some beverages and aging may affect the color of dental materials used in fixed prosthodontics, but their effect on recently introduced materials is not well known. PURPOSE: The purpose of this in vitro study was to evaluate staining, aging, and the exposure interval on color changes of computer-aided design and computer-aided manufacturing (CAD-CAM) resin nanoceramics (RNC), polymer-infiltrated ceramic-network (PICN) materials, and lithium silicate and lithium disilicate ceramics. MATERIAL AND METHODS: A total of 288 square-shaped, 1-mm-thick specimens prepared from Cerasmart, IPS e.max, Lava Ultimate, Shofu HC, Vita Enamic, and Vita Suprinity were polished by using laboratory and chairside methods in accordance with the manufacturers' instructions. Color data were recorded with a benchtop spectrophotometer, and CIEDE2000 color differences (ΔE00) were calculated. After the baseline measurements (T0), the specimens were divided into 3 groups (n=8) and exposed to staining in coffee and wine and to accelerated artificial aging. The specimens were stored in staining solutions at 37 °C for 60 (T1) and 120 hours (T2). Accelerated aging was performed by using a xenon lamp weathering test chamber for a total exposure of 150 (T1) and 300 kJ/m2 (T2). The results were analyzed by using the t test, ANOVA, and the Tukey honestly significant difference test (α=.05). Color differences of ΔE00 ≤0.8 and ≤1.8 corresponding to the 50:50% perceptibility threshold and 50:50% acceptability threshold were used to interpret the results. RESULTS: As color differences (ΔE00) between laboratory and chairside polishing were not statistically significant (T=-0.81, P=.418), only the results for chairside polished specimens were presented. Color differences for the T0-T1 comparisons ranged from 0.2 to 4.2, T0-T2 from 0.3 to 6.5, and T1-T2 from 0.1 to 2.3. ANOVA showed significance of factors and for interactions (P<.05). Lithium silicate-based and lithium disilicate-based ceramic materials were more color stable than RCN and PICN materials on exposure to coffee and red wine. Color changes greater than acceptability threshold after immersion in coffee were recorded for 3 (T0-T1), 4 (T0-T2), and 2 (T1-T2) materials. Corresponding findings after immersion in wine were 1, 3, and 0 and after artificial aging 0, 2, and 0. ΔE00 and ΔEab values were highly correlated (R2=0.97). CONCLUSIONS: No difference was found in color stability among laboratory and chairside polished specimens. Coffee caused the greatest color changes for T0-T2 interval. Staining-dependent color differences increased with increased exposure, except for IPS e.max and Vita Suprinity. For artificial aging, color change appeared to be material dependent.

Student profile of a brazilian public Dental school / O perfil do aluno de uma faculdade de Odontologia pública brasileira

Objetive: The aim of this study was to assess the profile of dental students at the ICT/CSJC-UNESP School of Dentistry and their preferred studying style. Material and methods: Data on age, sex, place of residence, first-choice course, secondary education background and study method preference were collected from an online questionnaire given in the second year dental materials course (first class) of the day and evening courses of the years 2016 to 2019. All data were tabulated and submitted to one-way ANOVA and to t test, both with α= 0.05. Pearson correlation test was performed between demographic data and study method preference (α = 0.05). Results: Most of the students were women living in São José dos Campos city who had chosen Dentistry as their first-choice course. Many were originally from other cities and lived in shared accommodation with friends. The majority stated that private high school was their main educational background. The students' age and place of living showed to correlate with study method preference. Conclusion: Although ICT/CSJC-UNESP students were from millennial and post-millennial generations, students with public secondary education preferred studying alone, while those from private education preferred studying in group (AU).

Objetivo: O objetivo do estudo foi o de assessar o perfil de alunos do curso de Odontologia do ICT/CSJC-UNESP e seu método de estudo de preferência. Material e Métodos: Dados de idade, sexo, local de residência, primeira escolha de curso, formação escolar prévia e método de estudo de preferência foram coletados a partir de um questionário online aplicado no primeiro dia de aula aos alunos do segundo ano na disciplina de materiais odontológicos dos cursos integral e noturno entre 2016 e 2019. Os dados foram tabulados e submetidos a ANOVA um fator e ao teste t, ambos com α = 0,05. O teste de correlação de Pearson foi realizado para os dados demográficos e métodos de estudo de preferência (α= 0,05). Resultados: A maioria dos estudantes eram mulheres que moravam em São José dos Campos, quem tinham a Odontologia como a primeira escolha de curso. Muitos eram originariamente de outras cidades e compartilhavam moradia com amigos. A maioria relatou ter a escola particular como maior parte no ensino fundamental e médio. A idade do aluno e o local de residência mostraram estar correlacionadas ao método de estudo de preferência. Conclusão: Embora os estudantes do ICT/CSJC-UNESP sejam da geração "millennial" e "pós-millennial", aqueles com formação em escola secundária pública preferiram estudar sozinhos, enquanto que aqueles com formação em escola particular preferiram estudar em grupo (AU).

Effect of Air-Particle-Abrasion Protocols on Surface Roughness and Early Biofilm Formation of Zirconia.

PURPOSE: The air-particle-abrasion on zirconia in the gingival area of connectors and pontics in fixed partial dentures appears to increase fracture resistance. This study evaluated 'in situ' biofilm formation on the zirconia surface after different air-particle-abrasion protocols. MATERIALS AND METHODS: Ninety sintered blocks (5 × 5 × 2 mm) of yttrium partially stabilised zirconia (Y-TZP) were obtained and randomised among nine groups according to the factors 'type of particle' (Alumina 50 and 110 µm; Cojet and Rocatec) and 'pressure' (2.5 and 3.5 bar) used for sandblasting for 10 s. The surface roughness (Ra/Rz) was measured before and after sandblasting. For the in-situ analyses, custom-made removable intraoral devices n = 10 with one sample of each group attached to the buccal area were used by volunteers for 8 h at night. The specimens were analysed under confocal microscopy to quantify both biovolume and thickness of the initial biofilm formed. One-way analysis of variance (ANOVA) and Dunnett's tests were performed (5%). RESULTS: The roughness values ranged from 0.05 to 0.39 µm for Ra and from 0.35 to 2.11 µm for Rz, p = 0.00. Mean biofilm thickness ranged from 0.06 and 0.54 µm (p = 0.005), while the biovolume values were between 0.02 and 0.61 µm3/µm2 (p = 0.002). Values statistically significant for biofilm thickness and biovolume were found in groups sandblasted with Rocatec using 3.5 bar. CONCLUSION: In order to increase the fracture resistance of zirconia fixed partial dentures (FPDs), the air particle abrasion of zirconia with SiO2 (110 µm/3.5 bar), in the gingival area of connectors and pontics, should be avoided.

Systemic and local effects of radiotherapy: an experimental study on implants placed in rats.

OBJECTIVES: Evaluate the modulating effect of ionizing radiation, blood cytokine levels, and bone remodeling of the interface around the implant to understand the radiation mechanisms which can impair the implants receptor site. MATERIAL AND METHODS: Sixty rats were submitted to grade V titanium implants in the femurs and were divided into the following groups: no-irradiation (N-Ir): control group with implant only; early-irradiation (E-Ir): implant + irradiation after 24 h; late-irradiation (L-Ir): implant + irradiation after 4 weeks; and previous-irradiation (P-Ir): irradiation + implant after 4 weeks. The animals in the E-Ir, L-Ir, and P-Ir groups were irradiated in two fractional stages of 15 Gy. At 3 days, 2 weeks, and 7 weeks after the final procedure, five animals were randomly euthanized per group. Serum levels of TNF-ɑ, IL-1ß, TGF-ß, IL-6, M-CSF, and IL-10 were measured from blood collected prior to euthanasia using the ELISA test. The pieces containing the implants were subjected to immunohistochemical labeling using the tartrate acid resistant to phosphatase, osteocalcin, and caspase-3 markers and mCT. The ANOVA test was used for statistical analysis, and the Tukey multiple comparison test (p < 0.05) was applied. RESULTS: The results indicated that ionizing radiation modifies the production of pro- and anti-inflammatory serum cytokines, the expression of proteins involved in bone remodeling and cellular apoptosis, as well as changes in bone formation. CONCLUSIONS: The results suggests that a longer period between radiotherapy and implant placement surgery when irradiation occurs prior to implant installation would allow the recovery and renewal of bone cells and avoid future failures in osseointegration. CLINICAL RELEVANCE: The search for modifications caused by ionizing irradiation in bone tissue can indicate the ideal period for implant placement without affecting the osseointegration process.

The Effect of Resection Angle on Stress Distribution after Root-End Surgery.

INTRODUCTION: This study aimed to investigate the influence of the resection angle on the stress distribution of retrograde endodontic treated maxillary incisors under oblique-load application. METHODS AND MATERIALS: A maxillary central incisor which was endodontically treated and restored with a fiber glass post was obtained in a 3-dimensional numerical model and distributed into three groups according to type of resection: control; restored with fiber post without retrograde obturation, R45 and R90 with 45º and 90º resection from tooth axial axis, respectively and restored with Fuji II LC (GC America). The numerical models received a 45º occlusal load of 200 N/cm2 on the middle of lingual surface. All materials and structures were considered linear elastic, homogeneous and isotropic. Numerical models were plotted and meshed with isoparametric elements, and the results were analyzed using maximum principal stress (MPS). RESULTS: MPS showed greater stress values in the bone tissue for control group than the other groups. Groups with apicectomy showed acceptable stress distribution on the fiber post, cement layer and root dentin, presenting more improved values than control group. CONCLUSION: Apicectomy at 90º promotes more homogeneity on stress distribution on the fiber post, cement layer and root dentin, which suggests less probability of failure. However, due to its facility and stress distribution also being better than control group, apicectomy at 45° could be a good choice for clinicians.

The Role of New Removable Complete Dentures in Stimulated Salivary Flow and Taste Perception.

PURPOSE: To evaluate the effect of replacement of inadequate complete dentures on salivary flow and taste perception in geriatric patients. MATERIALS AND METHODS: Thirty-three patients, 13 males and 20 females, with a mean age of 64.4 years were submitted to stimulated and unstimulated salivary flow rate and salivary pH measurements, and sense of taste evaluation. Tests were performed 3 months before complete denture substitution and 3 weeks after denture insertion. RESULTS: The mean for unstimulated saliva (USS) was 2.1 ml before and 2.7 ml after replacement (p = 0.003). The mean volume of stimulated saliva was 6.3 ml before and 8.2 ml after replacement (p = 0.004). The pH mean of USS was 7.8 ± 0.44 before and 8.02 ± 0.41 after replacement (p = 0.005). No statistically significant difference was determined in the sense of taste before and 3 weeks after complete denture replacement. CONCLUSIONS: The replacement of inadequate complete dentures increases saliva flow; however, it does not improve taste perception.

Effect of the mixing method on the dimensional stability of dental stones / Efeito do método de mistura na estabilidade dimensional de gessos odontológicos

Objective: The aim of this study was to evaluate the influence of mixing method and the empiric water/powder ratio on the dimensional change of two types of dental stones (type III and type IV) at different setting times: baseline, loss of brightness, initial and final setting (1/4 and 1pound Gilmore´s needle, respectively) and, after 48 hours at 37°C. Material and Methods: Five mixing methods were used: Gc ­ manufacturer´s recommendation, G1 ­ weighed powder/ empiric water volume and powder on water, G2 - weighed powder/ empiric water volume and water on powder, G3 ­ empiric powder volume, graduated water and powder on water, G4 - empiric powder volume, graduated water and water on powder. The linear expansion was measured according to ISO 6873. The expansion values (x10-2mm) were analyzed by Two-way ANOVA and Tukey HSD test (α=0.05). Results: For type III, the results showed significance for both factors and for interaction; for type IV, only the time were significant ( p<0.05). Limited by methodology, it could be concluded that both dental stones expanded more than the recommended by ISO. Conclusion: The expansion of type III was dependent on the mixing method, and once correct consistency is reached with type IV, there is no influence of mixing method on dimensional stability. (AU)

Objetivo: O objetivo deste estudo foi avaliar a influência do método de mistura e da relação empírica de água/pó na alteração dimensional de dois tipos de gessos odontológicos (tipo III e tipo IV) em diferentes tempos de trabalho: baseline, perda de brilho, inicial e final (agulha de Gilmore de 1/4 e 1 libra, respectivamente) e, após 48 horas a 37 ° C. Material e Métodos: Cinco métodos de mistura foram utilizados: Gc - recomendação do fabricante, G1 - pó pesado / volume empírico de água e pó na água, G2 - pó pesado / volume empírico de água e água no pó, G3 - volume empírico de pó, água graduada e pó na água, G4 - volume de pó empírico, água graduada e água no pó. A expansão linear foi medida de acordo com a norma ISO 6873 (1998). Os valores de expansão (x10-2mm) foram analisados pelo teste ANOVA dois fatores e teste de Tukey HSD (α = 0,05). Resultados: Para o tipo III, os resultados mostraram significância para ambos os fatores e para interação; para o tipo IV, apenas o tempo foi significativo (p < 0,05). Limitado pela metodologia, pode-se concluir que ambos os gessos odontológicos expandiram mais do que o recomendado pela ISO. Conclusão: A expansão do tipo III foi dependente do método de mistura e, uma vez atingida a consistência correta com o tipo IV, não há influência do método de mistura na estabilidade dimensional. (AU)

Influence of implantoplasty on stress distribution of exposed implants at different bone insertion levels.

This study evaluated the effect of implantoplasty on different bone insertion levels of exposed implants. A model of the Bone Level Tapered implant (Straumann Institute, Waldenburg, Switzerland) was created through the Rhinoceros software (version 5.0 SR8, McNeel North America, Seattle, WA, USA). The abutment was fixed to the implant through a retention screw and a monolithic crown was modeled over a cementation line. Six models were created with increasing portions of the implant threads exposed: C1 (1 mm), C2 (2 mm), C3 (3 mm), C4 (4 mm), C5 (5 mm) and C6 (6 mm). The models were made in duplicates and one of each pair was used to simulate implantoplasty, by removing the threads (I1, I2, I3, I4, I5 and I6). The final geometry was exported in STEP format to ANSYS (ANSYS 15.0, ANSYS Inc., Houston, USA) and all materials were considered homogeneous, isotropic and linearly elastic. To assess distribution of stress forces, an axial load (300 N) was applied on the cusp. For the periodontal insert, the strains increased in the peri-implant region according to the size of the exposed portion and independent of the threads' presence. The difference between groups with and without implantoplasty was less than 10%. Critical values were found when the inserted portion was smaller than the exposed portion. In the exposed implants, the stress generated on the implant and retention screw was higher in the models that received implantoplasty. For the bone tissue, exposure of the implant's thread was a damaging factor, independent of implantoplasty. Implantoplasty treatment can be safely used to control peri-implantitis if at least half of the implant is still inserted in bone.

Influence of implantoplasty on stress distribution of exposed implants at different bone insertion levels

Abstract This study evaluated the effect of implantoplasty on different bone insertion levels of exposed implants. A model of the Bone Level Tapered implant (Straumann Institute, Waldenburg, Switzerland) was created through the Rhinoceros software (version 5.0 SR8, McNeel North America, Seattle, WA, USA). The abutment was fixed to the implant through a retention screw and a monolithic crown was modeled over a cementation line. Six models were created with increasing portions of the implant threads exposed: C1 (1 mm), C2 (2 mm), C3 (3 mm), C4 (4 mm), C5 (5 mm) and C6 (6 mm). The models were made in duplicates and one of each pair was used to simulate implantoplasty, by removing the threads (I1, I2, I3, I4, I5 and I6). The final geometry was exported in STEP format to ANSYS (ANSYS 15.0, ANSYS Inc., Houston, USA) and all materials were considered homogeneous, isotropic and linearly elastic. To assess distribution of stress forces, an axial load (300 N) was applied on the cusp. For the periodontal insert, the strains increased in the peri-implant region according to the size of the exposed portion and independent of the threads' presence. The difference between groups with and without implantoplasty was less than 10%. Critical values were found when the inserted portion was smaller than the exposed portion. In the exposed implants, the stress generated on the implant and retention screw was higher in the models that received implantoplasty. For the bone tissue, exposure of the implant's thread was a damaging factor, independent of implantoplasty. Implantoplasty treatment can be safely used to control peri-implantitis if at least half of the implant is still inserted in bone.

FEA and microstructure characterization of a one-piece Y-TZP abutment.

OBJECTIVES: The most important drawback of dental implant/abutment assemblies is the need for a fixing screw. This study aimed to develop an esthetic one-piece Y-TZP abutment to suppress the use of the screw. METHODS: Material characterization was performed using a bar-shaped specimen obtained by slip-casting to validate the method prior to prototype abutment fabrication by the same process. The mechanical behavior of the prototype abutment was verified and compared with a conventional abutment by finite element analysis (FEA). The abutment was evaluated by micro-CT analysis and its density was measured. RESULTS: FEA showed stress concentration at the first thread pitch during installation and in the cervical region during oblique loading for both abutments. However, stress concentration was observed at the base of the screw head and stem in the conventional abutment. The relative density for the fabricated abutment was 95.68%. Micro-CT analysis revealed the presence of elongated cracks with sharp edges over the surface and porosity in the central region. SIGNIFICANCE: In the light of these findings, the behavior of a one-piece abutment is expected to be better than that of the conventional model. New studies should be conducted to clarify the performance and longevity of this one-piece Y-TZP abutment.