Development of a fiber-reinforced material for fiber posts: Evaluation of stress distribution, fracture load, and failure mode of restored roots.

STATEMENT OF PROBLEM: The biomechanical behavior of post-restored roots with an experimental fiber-reinforced composite resin is unknown. PURPOSE: The purpose of this in vitro study was to investigate the biomechanical behavior of an experimental composite resin (3-mm short glass fiber incorporated in methacrylate matrix with filler particles) used to produce the custom post itself or to reline fiber posts. MATERIAL AND METHODS: Four testing groups (n=10) were created according to the root restoration method: FG, commercially available fiber post; FG+RC, fiber post relined with conventional composite resin; FG+EXP, fiber post relined with the experimental composite resin; and EXP, a custom post made of experimental composite resin. A three-dimensional finite element linear elastic analysis was performed by using geometric representations of groups, and the results were analyzed by von Mises (σvM) and maximum principal stress criteria. In sequence, 40 bovine incisors were assigned to these groups and subjected to a fracture load test (Instron 5965; 0.5 mm/min), and the failure mode was determined. RESULTS: The EXP group showed more homogeneous stress distribution for σvM. ANOVA and the Tukey honestly significant difference (HSD) tests showed significant differences (P<.001) in fracture load (mean ±standard deviation; different superscript letters indicate statistical difference): FG+EXP (669.5 ±107.7)A; FG (620.7 ±59.2)A; EXP (506.5 ±27.0)B; FG+RC (452.7 ±81.6)B. No differences were found for failure mode (P=.595). CONCLUSIONS: The experimental composite resin significantly increases fracture load when used to reline commercially available fiber posts and, irrespective of its use, presented lower stress concentration.

Effect of dental bleaching on pulp oxygen saturation in maxillary central incisors - a randomized clinical trial.

OBJECTIVE: To assess pulp oxygen saturation levels (SaO2) in maxillary central incisors after dental bleaching. MATERIALS AND METHODS: 80 participants (160 teeth) were randomly allocated to four groups: G1 In-office bleaching with two applications of 35% hydrogen peroxide (HP) (20 minutes), followed by at-home bleaching with 10% carbamide peroxide (CP) (2 hours/day for 16 days); G2 - Same protocol as G1, plus desensitizing toothpaste; G3 - In-office bleaching with 35% HP and one application of placebo gel (20 minutes), followed by at-home bleaching with 10% CP (2 hours/day for 16 days); and G4 - Same protocol as G3, plus desensitizing toothpaste. Pulp SaO2 levels were measured before (T0) and immediately after (T1) in-office bleaching; on the 5th (T2), 8th (T3), 12th (T4), and 16th days of at-home bleaching (T5); and on the 7th (T6) and 30th (T7) days. Mean (SD) pulp SaO2 levels were compared within groups by generalized estimating equations (GEE) and Student's t-test (P<0.05). RESULTS: Mean pulp SaO2 at T0 was 84.29% in G1, 84.38% in G2, 84.79% in G3, and 85.83% in G4. At T1, these values decreased to 81.96%, 82.06%, 82.19%, and 81.15% in G1, G2, G3, and G4 respectively, with significant difference in G4 (P<0.05). During home bleaching, pulp SaO2 levels varied in all groups, with 86.55%, 86.60%, 85.71%, and 87.15% means at T7 for G1, G2, G3, and G4, respectively; G2 presented significant difference (P<0.05). CONCLUSIONS: Pulp SaO2 level in maxillary central incisors was similar at baseline, reducing immediately after in-office bleaching, regardless of using desensitizing toothpaste and increasing at 30 days after dental bleaching.

Effect of dental bleaching on pulp oxygen saturation in maxillary central incisors - a randomized clinical trial

Abstract Objective To assess pulp oxygen saturation levels (SaO2) in maxillary central incisors after dental bleaching. Materials and Methods 80 participants (160 teeth) were randomly allocated to four groups: G1 In-office bleaching with two applications of 35% hydrogen peroxide (HP) (20 minutes), followed by at-home bleaching with 10% carbamide peroxide (CP) (2 hours/day for 16 days); G2 - Same protocol as G1, plus desensitizing toothpaste; G3 - In-office bleaching with 35% HP and one application of placebo gel (20 minutes), followed by at-home bleaching with 10% CP (2 hours/day for 16 days); and G4 - Same protocol as G3, plus desensitizing toothpaste. Pulp SaO2 levels were measured before (T0) and immediately after (T1) in-office bleaching; on the 5th (T2), 8th (T3), 12th (T4), and 16th days of at-home bleaching (T5); and on the 7th (T6) and 30th (T7) days. Mean (SD) pulp SaO2 levels were compared within groups by generalized estimating equations (GEE) and Student's t-test (P<0.05). Results Mean pulp SaO2 at T0 was 84.29% in G1, 84.38% in G2, 84.79% in G3, and 85.83% in G4. At T1, these values decreased to 81.96%, 82.06%, 82.19%, and 81.15% in G1, G2, G3, and G4 respectively, with significant difference in G4 (P<0.05). During home bleaching, pulp SaO2 levels varied in all groups, with 86.55%, 86.60%, 85.71%, and 87.15% means at T7 for G1, G2, G3, and G4, respectively; G2 presented significant difference (P<0.05). Conclusions Pulp SaO2 level in maxillary central incisors was similar at baseline, reducing immediately after in-office bleaching, regardless of using desensitizing toothpaste and increasing at 30 days after dental bleaching.

Influence of preheating and post-curing on a novel fiber-reinforced composite post material.

The aim of this study was to investigate the influence of preheating and post-curing methods on diametral tensile strength (DTS), flexural strength (FS), knoop microhardness (KHN), and degree of conversion (DC) of an experimental fiber-reinforced composite (FRC). Specimens (30 wt% of 3-mm-short E-glass fiber, 22.5 wt% of methacrylated-based resin and 47.5 wt% of filler particles) were subjected to: P - photocuring at 1500 mW/cm2 for 40 s (control); P/M - photocuring and microwave post-curing (540W/5 minutes); P/A - photocuring and autoclave post-curing (120°C/15 minutes); PH-P - preheating (60°C) and photocuring; PH-P/M - preheating, photocuring and microwave post-curing; and PH-P/A - preheating, photocuring and autoclave post-curing. Specimens for DTS (Ø 3 x 6 mm) and FS (25 x 2 x 2 mm) were tested at Instron 5965. KHN employed a 50g load for 30s. DC was measured using FTIR spectroscopy. Statistical analysis employed: factorial analysis, normality test, one-way ANOVA and Tukey's HSD test, independent T-test and the Dunnett test. Interaction between factors was not significant (P>0.05). Preheating promoted significantly higher values of FS and KHN (p = 0.0001). Post-curing promoted significantly higher values for KHN (p = 0.0001). For DTS (p = 0.066) and DC (p= 0.724) no statistical difference was found between groups. SEM images showed that preheating promoted better interaction between glass fibers and resin matrix. Preheating increased FS, KHN and DTS, and post-curing increased KHN. DC was not affected by both methods. Preheating and post-curing methods can be used to improve some mechanical properties of FRCs' but degree of conversion remains unaffected.

Influence of preheating and post-curing on a novel fiber-reinforced composite post material

Abstract The aim of this study was to investigate the influence of preheating and post-curing methods on diametral tensile strength (DTS), flexural strength (FS), knoop microhardness (KHN), and degree of conversion (DC) of an experimental fiber-reinforced composite (FRC). Specimens (30 wt% of 3-mm-short E-glass fiber, 22.5 wt% of methacrylated-based resin and 47.5 wt% of filler particles) were subjected to: P - photocuring at 1500 mW/cm2 for 40 s (control); P/M - photocuring and microwave post-curing (540W/5 minutes); P/A - photocuring and autoclave post-curing (120°C/15 minutes); PH-P - preheating (60°C) and photocuring; PH-P/M - preheating, photocuring and microwave post-curing; and PH-P/A - preheating, photocuring and autoclave post-curing. Specimens for DTS (Ø 3 x 6 mm) and FS (25 x 2 x 2 mm) were tested at Instron 5965. KHN employed a 50g load for 30s. DC was measured using FTIR spectroscopy. Statistical analysis employed: factorial analysis, normality test, one-way ANOVA and Tukey's HSD test, independent T-test and the Dunnett test. Interaction between factors was not significant (P>0.05). Preheating promoted significantly higher values of FS and KHN (p = 0.0001). Post-curing promoted significantly higher values for KHN (p = 0.0001). For DTS (p = 0.066) and DC (p= 0.724) no statistical difference was found between groups. SEM images showed that preheating promoted better interaction between glass fibers and resin matrix. Preheating increased FS, KHN and DTS, and post-curing increased KHN. DC was not affected by both methods. Preheating and post-curing methods can be used to improve some mechanical properties of FRCs' but degree of conversion remains unaffected.

Effect of short glass fiber/filler particle proportion on flexural and diametral tensile strength of a novel fiber-reinforced composite.

PURPOSE: To evaluate the effect of glass fiber/filler particles proportion on flexural strength and diametral tensile strength of an experimental fiber-reinforced composite. METHODS: Four experimental groups (N=10) were created using an experimental short fiber-reinforced composite, having as a factor under study the glass fiber (F) and filler particle (P) proportion: F22.5/P55 with 22.5 wt% of fiber and 55 wt% of filler particles; F25/P52.5 with 25 wt% of fiber and 52.5 wt% of filler particles; F27.5/P50 with 27.5 wt% of fiber and 50 wt% of filler particles; F30/P47.5 with 30 wt% of fiber and 47.5 wt% of filler particles. The experimental composite was made up by a methacrylate-based resin (50% Bis-GMA and 50% TEGDMA). Specimens were prepared for Flexural Strength (FS) (25 mm × 2 mm × 2 mm) and for Diametral Tensile Strength (DTS) (3×6 Ø mm) and tested at 0.5 mm/min in a universal testing machine. RESULTS: The results (in MPa) showed significance (different superscript letters mean statistical significant difference) for FS (p<0.009) and DTS (p<0.001)--FS results: F22.5/P55: 217.24±20.64(B); F25/P52.5: 245.77±26.80(AB); F27.5/P50: 246.88±32.28(AB); F30/P47.5: 259.91±26.01(A). DTS results: F22.5/P55: 21.82±4.42(B); F25/P52.5: 22.00±7.40(B); F27.5/P50: 18.63±4.41(B); F30/P47.5: 31.05±2.97(A). In SEM analysis, areas without fiber reinforcement demonstrated to be more prone to the presence of bubbles and crack development. The group F30/P47.5 showed areas with a great quantity of fibers without empty spaces for crack propagation. CONCLUSION: Increasing fiber content results in higher flexural and diametral tensile strength of an experimental composite reinforced with glass fibers.

The influence of polymerization type and reinforcement method on flexural strength of acrylic resin.

The aim of this study was to evaluate the flexural strength of acrylic resin bars by varying the types of resin polymerization and reinforcement methods. Fourteen groups (N=10) were created by the interaction of factors in study: type of resin (self-cured (SC) or heat-cured (HC)) and reinforcement method (industrialized glass fiber (Ind), unidirectional glass fiber (Uni), short glass fiber (Short), unidirectional and short glass fiber (Uni-Short), thermoplastic resin fiber (Tpl), and steel wire (SW)). Reinforced bars (25×2×2 mm) were tested in flexural strength (0.5 mm/min) and examined by scanning electron microscopy (SEM). Data (MPa) were submitted to factorial analysis, ANOVA, and Tukey and T-student tests (a=5%) showing significant interaction (P=0.008), for SC: Uni (241.71±67.77)a, Uni-Short (221.05±71.97)a, Ind (215.21±46.59)ab, SW (190.51±31.49)abc, Short (156.31±28.76)bcd, Tpl (132.51±20.21)cd, Control SC (101.47±19.79)d and for HC: Ind (268.93±105.65)a, Uni (215.14±67.60)ab, Short (198.44±95.27)abc, Uni-Short (189.56±92.27)abc, Tpl (161.32±62.51)cd, SW (106.69±28.70)cd, and Control HC (93.39±39.61)d. SEM analysis showed better fiber-resin interaction for HC. Nonimpregnated fibers, irrespective of their length, tend to improve fracture strength of acrylics.

Reinforcement of dental methacrylate with glass fiber after heated silane application.

This study evaluated the influence of silane heat treatment and glass fiber fabrication type, industrially treated (I) or pure (P), on flexural and compressive strength of methacrylate resin bars (BISGMA/TEGDMA, 50/50%). Six groups (n = 10) were created: I-sil: I/silanated; P-sil: P-silanated; I-sil/heat: I/silanated heated to 100°; P-sil/heat: P/silanated heated to 100°; (I: I/not silanated; and P: P/not silanated. Specimens were prepared for flexural strength (10 × 2 × 1 mm) and for compressive strength 9.5 × 5.5 × 3 mm) and tested at 0.5 mm/min. Statistical analysis demonstrated the following for flexural strength (P < 0.05): I-sil: 155.89 ± 45.27(BC); P-sil: 155.89 ± 45.27(BC); I-sil/heat: 130.20 ± 22.11(C); P-sil/heat: 169.86 ± 50.29(AB); I: 131.87 ± 15.86(C). For compressive strength, the following are demonstrated: I-sil: 1367.25 ± 188.77(ab); P-sil: 867.61 ± 102.76(d); I-sil/heat: 1162.98 ± 222.07(c); P-sil/heat: 1499.35 ± 339.06(a); and I: 1245.78 ± 211.16(bc). Due to the impossibility of incorporating the stipulated amount of fiber, P group was excluded. Glass fiber treatment with heated silane enhanced flexural and compressive strength of a reinforced dental methacrylate.

Técnica de estratificação e texturização superficial de resinas compostas em dentes anteriores: seis meses de acompanhamento / Layering technique and surface texturization of composite resins in anterior teeth: six month follow-up

Este relato de caso apresenta uma alternativa conservadora para reanatomização de dentes conóides e fechamento de diastemas. O método escolhido foi uma técnica restauradora adesiva direta com resinas compostas, estratificada com diferentes camadas e cores, e posterior texturização superficial durante as fases de acabamento e polimento finais. As restaurações resultaram em dentes reanatomizados, reproduzindo naturalidade de forma, textura e cor, mantidas pelos seis meses em que a paciente foi acompanhada. Com planejamento adequado, enceramento diagnóstico e estratificação-texturização com resinas compostas, foi possível restabelecer o sorriso com proporções, forma e naturalidade satisfatórias.

This report presents an alternative, conservative treatment for reshaping conoid teeth and diastema closure. The chosen method was a direct restorative technique with composite resins, stratified with different masses and shades, and subsequent surface texturization during the final stages of finishing and polishing. The final restorations reproduced naturally the form, texture and shade, followed-up for 6 months. After proper planning, diagnostic wax-up and stratification/surface texturization of composite resins reestablished the smile with pleasant proportions, shape and life-like appearance of the smile

Longevidade de clareamento em dente não vital com associação de técnicas: relato de caso / Longevity of nonvital tooth bleaching with a combination of techniques. Case report

O clareamento dentário, por ser um tratamento não invasivo e de baixo custo, representa uma excelente opção de tratamento para dentes com alteração cromática. O propósito desse artigo é relatar um caso clínico com associação de técnicas de clareamento para dentes não vitais e discutir as implicações clínicas imediatas e mediatas. Paciente do sexo masculino, 30 anos de idade, procurou o serviço odontológico da Universidade Estadual de Londrina para tratamento estético do dente 21, diagnosticado com escurecimento após traumatismo e tratamento endodôntico. Diante do exame radiográfco, que não mostrou alterações da normalidade, foi instituído o clareamento dentário intracoronário com pasta clareadora de perborato de sódio e peróxido de hidrogênio a 20% (6 sessões, com intervalo de 7 dias), seguido por clareamento intra- e extracoronário com peróxido de hidrogênio a 35% (3 sessões de 20 minutos ininterruptos, com intervalo de 7 dias). Passados 10 dias da última sessão de clareamento, foi confeccionada restauração da face palatina com resina composta. Também foi feito controle clínico e radiográfco após 18 meses. O resultado obtido demonstrou a longevidade do procedimento realizado. Assim,conclui-se que o clareamento de dentes não vitais é seguro,efcaz e, quando necessário, pode ser realizado com diferentes produtos, aplicados por diferentes técnicas.

Tooth bleaching, as a non-invasive and low cost treatment,provides an excellent option for teeth with color change. The purpose of this study is to report a case with a combination of techniques for nonvital teeth bleaching and discuss the immediate and mediate clinical implications. Male patient,30 year-old, came to the dental service at the State University of Londrina for esthetic treatment of tooth #21, diagnosed with severe darkening after trauma accentuated by endodontic treatment. Radiographic examination showed no alterations of normality. It was established a treatment with intracoronal bleaching techniques, using sodium perborate with 20% hydrogen peroxide (6 sessions every 7 days), followed by intra- and extracoronal bleaching with 35% hydrogen peroxide (3 sessions of 20 minutes every 7 days). Restoration with composite resin for the fnal sealing of the cavity was made 10 days after the end of bleaching. Clinical and radiographic control after 18 months also were performed.The result showed the longevity of the procedure. Therefore it can be conclude that the nonvital bleaching is safe, effective and can be performed with different products, applied by different techniques

Pinos de fibra anatômicos: técnica clínica e benefícios mecânicos — relato de caso

Introdução: o emprego de pinos estéticos compostos por fibra de vidro tem sido cada vez mais estudado e os benefícios biomecânicos, além da possibilidade adesiva,tornam viável seu uso em várias situações clínicas. Estudos mostram que a perfeita adaptação às paredes do canal radicular é importante para melhorar as propriedades do conjunto dente-pino. Objetivo: apresentar a sequência técnica de um reembasamento de pino de fibra de vidro em canal amplo de um incisivo central fraturado coronalmente. Relato do caso: paciente do sexo masculino,12 anos de idade, apresentou-se com fratura oblíqua no dente 11 após acidente, atingindo a câmara pulpar.Após tratamento endodôntico, a obturação do canal radicular foi removida em preparo mecânico, resultando em necessidade de reembasamento do pino de fibra (Exacto#3, Angelus), que foi realizado com resina composta microhíbrida (Natural Look, DFL). O pino foi cimentado com adesivo convencional de três passos quimicamente polimerizado (Fusion Duralink, Angelus) e cimento resinoso autopolimeriável (Cement Post, Angelus), sendo posteriormente reconstruída a restauração da fratura dentária. Resultados: alcançou-se ótima resolução funcional e estética, com previsão de grande durabilidade clínica