Influence of repositioning guides' color and usage on precision in tooth color measurement with a clinical spectrophotometer

Abstract Repositioning guides are commonly employed in clinical studies to ensure consistent tooth color measurements. Yet, their influence on measured color remains uncertain. Objective This study evaluated the impact of repositioning guides' color and usage on tooth color measurement using a clinical spectrophotometer. Methodology In total, 18 volunteers participated in this study, in which the color of their upper left central incisor and upper left canine was measured with or without repositioning guides (control). The guides were made from pink, blue, or translucent silicone, as well as an acetate-based bleaching tray. Tooth color was measured in triplicates using a clinical spectrophotometer based on the CIELAB system. The standard deviations of these readings were used to estimate reproducibility, and color differences (ΔE00) between the measurements with guides and the control were calculated. Results Repositioning guides had a minimal effect on L* values and no effect on b* values. The use of pink silicone increased a* values, whereas blue or translucent silicone reduced them. Irrespective of the evaluated tooth, the lowest ΔE00 values were observed for the translucent silicone and bleaching tray. The usage of guides only affected data variability for the L* color coordinate. Conclusion Using repositioning guides can significantly impact the precision of tooth color measurement with a clinical spectrophotometer.

Prevalence of lectures about dental esthetics and female speakers in three Brazilian conferences

Abstract This study analyzed the prevalence of lectures involving esthetics in the scientific program of Brazilian dental conferences and the gender distribution of speakers. All lectures presented in three dental conferences (Bahia, São Paulo, and Goiás states) held from 2016 to 2020 were evaluated. Three investigators individually divided the lectures according to the specialties recognized by the Brazilian Federal Council of Dentistry (FCD) based on their titles. The lectures were also classified as involving or not esthetics, and the speaker`s gender was recorded. Descriptive statistical analyses were performed, and Chi-square tests assessed possible associations between factors. The words most cited in the titles of the lectures were "esthetic" (13.6%), "dentistry" (9.9%), and "treatment" (8.1%). Oral diseases were barely mentioned in the titles (up to 1.3%). The highest number of lectures was observed for the specialty of Restorative Dentistry (22.3%), followed by Prosthodontics (18.5%). Approximately one-third of lectures involved some aesthetic aspect, but this percentage ranged from 71.9 to 78.6% for the two specialties with more lectures. Regarding the speaker`s gender, the inequity was higher for lectures involving esthetics (81.6% of males) than for topics unrelated to esthetics (66.7%). More male speakers than females were observed for all specialties. The highest gender gap was observed for Pediatric Dentistry with 62.4% male speakers, although only 10.6% of FCD registered specialists were men. In conclusion, the Brazilian dental conferences analyzed seemed to favor offering lectures dealing with esthetic topics and male speakers.

Resumo Este estudo analisou a prevalência de palestras envolvendo estética na programação científica de congressos de Odontologia brasileiros, e a distribuição do gênero dos palestrantes. Todas as palestras apresentadas em três congressos de Odontologia (CIOBA, CIOGO, and CIOSP) entre 2016 e 2020 foram avaliadas. Três avaliadores utilizaram os títulos das palestras para dividi-las entre as especialidades reconhecidas pelo Conselho Federal de Odontologia (CFO) do Brasil. As palestras foram também classificadas como envolvendo ou não estética, e o gênero do palestrante foi registrado. Análises estatísticas descritivas foram realizadas, e testes de Qui-quadrado avaliaram possíveis interações entre fatores. A palavra mais citada nos títulos das palestras foi "estética" (13,6%), seguido por "odontologia" (9,9%) e "tratamento" (8,1%). Doenças orais foram raramente mencionadas nos títulos (até 1,3%). O maior número de palestras foi observado para a especialidade de Dentística (22,3%), seguido por Prótese Dental (18,3%). Aproximadamente um terço das palestras envolviam algum aspecto estético, com porcentagens entre 71,9 a 78,6% para as duas especialidades com mais palestras. Em relação ao gênero do palestrante, a inequidade foi maior para palestras envolvendo estética (81,6% de homens) que para tópicos não relacionadas à estética (66,7%). Mais palestrantes do sexo masculino que feminino foram observados para todas as especialidades. A maior discrepância entre os gêneros foi observada para Odontopediatria, uma especialidade com 62,4% dos palestrantes do sexo masculino, embora apenas 10,6% dos especialistas registrados no CFO eram homens. Como conclusão, os congressos de Odontologia Brasileiros parecem preferir palestras abordando tópicos de estética e palestrantes do sexo masculino.

Background and surrounding colors affect the color blending of a single-shade composite

Abstract This study evaluated the background and effect of surrounding colors on the color blending of a single-shade composite used in a thin layer. Disc-shaped specimens (1.0 mm thickness) were built with the Vittra APS Unique composite surrounded (dual specimens) or not surrounded (simple specimens) by a control composite (shade A1, A2, or A3). Simple specimens were also built with only control composites. The specimen color was measured against white and black backgrounds with a spectrophotometer (CIELAB system). The whiteness index for dentistry (WID) was calculated for simple specimens. Differences (ΔE00) in color and translucency parameters (ΔTP00) between the simple/dual specimens and the controls were calculated. The translucency adjustment potential (TAP) and color adjustment potential (CAP) were estimated based on the ratios between data from simple and dual specimens. The Vittra APS Unique composite showed higher WID values than the controls. No differences between ΔTP00_SIMPLE and ΔTP00_DUAL were observed for any of the shades. The composite shade did not affect TAP values. The lowest values of ΔE00_SIMPLE and ΔE00_DUAL were observed for shade A1 regardless of the background color. For the white background, ΔE00_SIMPLE values did not differ from those of ΔE00_DUAL for all shades. Only A1 showed ΔE00_DUAL values lower than ΔE00_SIMPLE when the black background was used. The highest modulus of CAP (negative values for the white background) was observed when shade A1 surrounded the Vittra APS Unique composite. The color blending ability of the single-shade resin composite used in a thin layer was affected by both the surrounding shade and background color.

Effect of modeling liquids on resin composite roughness and color parameters after staining and toothbrushing

Abstract This study evaluated surface roughness, color stability, whitening index, and opacity of different types of modeling liquids for resin composite coating after exposure to staining and toothbrushing. Disc-shaped resin composite (Vittra APS, FGM) specimens were fabricated and divided into four groups (n = 10 each): control group, Composite Wetting resin (Ultradent Products), Adper Scotchbond Multipurpose adhesive (3M ESPE), and Adper Universal adhesive (3M ESPE). Surface roughness (Ra) was measured using a rugosimeter, while color stability (∆E00), whitening index (WI), and opacity (%) were measured using a spectrophotometer. Assessments were made at four time points: after polishing (baseline, T1), after immersion in red wine for 24 h (T2), and after 5,000 (T3) and 10,000 (T4) cycles of toothbrushing. Scanning electron microscopy images were captured to analyze the scratches created. The data were statistically analyzed by two-way repeated-measures analysis of variance and Tukey's honestly significant difference tests (α = .05). Modeling with the Wetting resin resulted in higher surface roughness (p < 0.05) and low color stability, which were attributable to porosities. Higher color change values were observed in the control group after staining. Both adhesives showed the lowest mean ΔE00 values (p < 0.005). WI decreased after staining, except with the use of the Universal adhesive (p < 0.005). The lowest opacity values were observed at baseline for all groups (p < 0.005). The Universal and Scotchbond adhesives had lower surface roughness, better color stability, higher WI, and the lowest opacity values after staining with red wine and toothbrushing.

Effect of surrounded shade and specimen`s thickness on color adjustment potential of a single-shade composite

Abstract This study evaluated the effect of surrounded shade and specimens` thickness on the color adjustment potential (CAP) of a single-shade composite. The composite Vittra APS Unique was surrounded (dual specimens) or not (simple specimens) by a control composite (shade A1, A2, or A3). Simple specimens of the control composite were also confectioned. Opacity and whiteness index for dentistry (WID) were calculated for simple specimens. Color differences between the simple (ΔE*SIMPLE)/ dual specimens (ΔE*DUAL) and the controls were calculated. CAP was calculated based on the ratio between ΔE* SIMPLE and ΔE* DUAL. The tested composite presented lower opacity (53 to 62% vs. 80 to 93%) and higher WID (≈ 42 vs. 18 to 32) than controls. Irrespective of the specimens' thickness (1.0/ 1.5 mm), the lowest values of ΔE* SIMPLE (11.1/ 10.8) and ΔE*DUAL (7.2/ 6.1) were observed using the surrounding shade A1. The shade A3 yielded higher ΔE*SIMPLE (16.4/ 17.1) and ΔE* DUAL (11.3/ 12.3) than the A2 (ΔE*SIMPLE = 13.4/ 14.6; and ΔE* DUAL = 9.7/ 10.3). The specimen`s thickness significantly affected the CAP (0.35 and 0.44 for 1.0 and 1.5 mm, respectively) only for shade A1, which had the highest CAP values. The shade A3 resulted in higher CAP values (0.31) than A2 (0.27) when 1.0-mm thick specimens were used, but similar values were observed for 1.5 thick specimens (≈ 0.29). In conclusion, both surrounding shade and specimen thickness can affect the CAP of a single-shade resin composite.

Resumo Este estudo avaliou o efeito da cor circundante e da espessura da amostra no potencial de ajuste de cor (PAC) de uma resina monocromática. O compósito Vittra APS Unique foi circundado (amostras duplas) ou não (amostras simples) com um compósito controle (cor A1, A2 ou A3). Amostras simples do compósito controle também foram confeccionadas. A opacidade e o índice de brancura para odontologia (IBO) foram calculados para as amostras simples. As diferenças de cor entre amostras simples (ΔE*SIMPLE) / duplas (ΔE*DUAL) e os controles foram calculados. PAC foi calculado baseado na razão entre ΔE* SIMPLE e ΔE* DUAL. O compósito testado apresentou menor opacidade (53 a 62% vs. 80 a 93%) e maior IBO (≈ 42 vs. 18 a 32) que os controles. Independente da espessura da amostra (1,0/ 1,5 mm), os valores mais baixos de ΔE* SIMPLE (11,1/ 10,8) e ΔE*DUAL (7,2/ 6,1) foram observadas quando a resina circundante era A1. A cor A3 resultou em maior ΔE*SIMPLE (16,4/ 17,1) e ΔE* DUAL (11,3/ 12,3) do que A2 (ΔE*SIMPLE = 13,4/ 14,6; e ΔE* DUAL = 9,7/ 10,3). A espessura das amostras afetou significativamente o PAC (0,35 e 0,44 para 1,0 e 1,5 mm, respectivamente) apenas para a cor A1, que teve os maiores valores de PAC. A cor A3 resultou nos maiores valores de PAC (0,31) que A2 (0,27) quando amostras de 1,0 mm de espessura foram usadas, mas valores similares foram observados para amostras de 1,5 mm (≈ 0,29). Como conclusão, tanto a cor circundante como a espessura das amostras podem afetar o PAC de um compósito resinoso monocromático.

Oxygen inhibition of surface composites and its correlation with degree of conversion and color stability

Abstract This study investigated the effects of oxygen inhibition and finishing/polishing procedures on the composite resin properties. One bulk-fill and two conventional composite resins (nanoparticle and microhybrid) were evaluated. Specimens were prepared using 4 surface treatments: control, no treatment; Gly, oxygen inhibition with glycerin; FP, finishing and polishing; Gly + FP, glycerin followed by finishing and polishing. The degree of conversion (DC) was measured using Fourier Transformed Infrared Spectroscopy (FTIR) immediately and after 15 days (n=5). Color stability (ΔEab, and ΔE00) and opacity were evaluated using a spectrophotometer after 15 days of immersion in coffee, using the CIELAB system (n=5). Data were analyzed by two-way ANOVA and Tukey tests (α=0.05) and opacity by two-way repeated-measures ANOVA. Glycerin usage increased significantly the DC however had no influence on the ΔEab, ΔE00 and, opacity values. Finishing and polishing reduced ΔEab and ΔE00 values, regardless of composite resins. Microhybrid showed higher opacity, followed by the nanoparticle and bulk fill, regardless of surface treatment. Post-polymerization polishing procedures resulted in lower conversion than using an oxygen inhibitor agent (Gly condition), but similar staining caused by coffee.

Resumo Este estudo investigou os efeitos da inibição de oxigênio e dos procedimentos de acabamento/polimento nas propriedades das resinas compostas. Foram avaliadas uma resina composta bulk fill e duas resinas convencionais (nanoparticulada e microhíbrida). Os espécimes foram confeccionados, variando o tratamento de superfície: controle, sem tratamento; glicerina (inibidor de oxigênio); acabamento e polimento; glicerina + acabamento e polimento. O grau de conversão (GC) foi medido pela Espectroscopia de Infravermelho Transformada de Fourier (FTIR) imediatamente e após 15 dias da confecção dos espécimes (n=5). Os índices de alteração de cor ΔEab, ΔE00 e opacidade foram avaliados por meio de espectrofotômetro, após 15 dias de imersão no café, utilizando o sistema CIELAB (n=5). Os dados da alteração da cor foram analisados pelos testes ANOVA de dois fatores e Tukey (α=0,05) e a opacidade por ANOVA de medidas repetidas. O uso de glicerina aumentou significativamente o GC, no entanto, não teve influência sobre os valores ΔEab e ΔE00. O acabamento e o polimento reduziram os valores de ΔEab e ΔE00, independentemente da resina composta. A resina microhíbrida apresentou maior opacidade, seguida pela nanoparticula e bulk-fill, independentemente do tratamento de superfície. O acabamento e polimento resultou em menor grau de conversão das resinas compostas se comparado ao uso de um agente inibidor de oxigênio (glicerina), porém apresenta resultados similares para a pigmentação pelo café.

Role of enamel and dentin on color changes after internal bleaching associated or not with external bleaching

Abstract Objective To evaluate the effect of the association between external and internal tooth bleaching on color changes in dentin and enamel, individually or recombined, previously stained with triple antibiotic paste (TAP). Methodology Forty enamel-dentin specimens from bovine incisors were separated into ten blocks according to similarity in their whiteness index (WID). Three specimens within each block were stained by dentin exposure to TAP, and the remaining specimen was used as control to estimate color changes. Specimens were sectioned to separate tissues, and dentin and enamel colors were measured individually and after being recombined. Alterations in color (CIEDE2000 - ΔE00) and translucency parameter (TP) resulting from staining were estimated by color difference between stained and control specimens. The contribution of each tissue to the color change (CTCC) was also calculated. Non-sectioned stained specimens were bleached by applying sodium perborate on dentin, associated or not with 35% hydrogen peroxide on enamel. Color changes caused by bleaching procedures were estimated and data were analyzed using the paired t-test or Two-way repeated measures ANOVA. Results TAP caused more pronounced changes in dentin, but enamel color was also affected. Both protocols presented a similar ΔE00, and dentin showed the greater color change. After exposure to TAP, we observed a reduction in WID; WID values were the same for bleached and control specimens regardless of protocol. We found no significant effect of substrate and bleaching technique on TP. Enamel played a more critical role in color changes caused by either staining or bleaching procedures. Conclusion Enamel color played a greater role on tooth color changes than dentin. External and internal bleaching association did not improve bleaching effect on specimens stained with TAP.

Fracture resistance of extensive bulk-fill composite restorations after selective caries removal

Abstract This study evaluated the effect of selective carious tissue removal on the fracture strength and failure mode of composite restorations in molars presenting only the buccal cusps. Deep cavities were prepared on the occlusal surface, and the lingual cusps were removed. Carious lesions in the middle of the pulpal wall were artificially induced with acetic acid (pH = 4.5) for 35 days. The demineralized dentin was left intact or was completely removed prior to restoration with a bulk-fill composite (n = 10). Images of the specimens were obtained by optical coherence tomography (OCT) before and after the caries induction/removal. The mechanical resistance to fracture by axial compressive loading and the failure type and extension were determined. The pulpal wall/composite interface of the fractured specimens was analyzed by OCT. The data were analyzed for significance with t-tests (α = 0.05). The deepest cavities and a more frequent occurrence of pulpal exposure were observed more often for non-selective carious tissue removal. The protocol of carious tissue removal did not affect the fracture strength (p = 0.554). An increased occurrence of catastrophic failures involving the roots was observed for non-selective carious tissue removal. Some occurrences of restoration displacement or cracks throughout the resin-dentin were observed only for the selective carious tissue approach. Selective carious tissue removal is a feasible approach to extensively damaged teeth since it reduced the occurrence of pulpal exposure and root fractures, without compromising the fracture strength.

Practice based research in dentistry: an alternative to deal with clinical questions

Abstract Clinical interventions in dental practice should be determined based on the best scientific evidence available. Well-designed randomized clinical trials (RCTs) provide important evidence supporting the efficacy of interventions and are usually considered as the best primary evidence. However, the strict criteria adopted by most RCTs reduce their external validity since some findings from these studies might not work under usual conditions. On the other hand, practice-based research (PBR) studies have been designed to better define the effectiveness of clinical interventions under settings closer to "real-world" conditions. Therefore, this review aimed to describe different PBR designs discussing some advantages and limitations of such studies. The stimulus to organization PBR networks is discussed since the studies performed by these networks involve large number of clinicians and important conclusions can be drawn. Designs of observational studies including surveys and cohort studies based on practice are presented. Survey methods are important to know the behavior of practitioners regarding diagnostic and decision of treatment. Cohorts allow assessing different cofounders contributing to some outcome since large sample sizes and long follow-up periods can be observed in some of these studies. Pragmatic trials designed to take place in real-world clinical practice settings are also discussed as a useful design to assess the effectiveness of clinical interventions. In conclusion, this review sought to present PBR studies as alternative designs to answer clinical questions, but not replacing randomized clinical trials.

Preemptive use of piroxicam on tooth sensitivity caused by in-office bleaching: a randomized clinical trial

Abstract This clinical trial evaluated the effect of preemptive use of the non-steroidal anti-inflammatory drug piroxicam in a single dose 30 min prior to in-office bleaching on the prevention of tooth sensitivity (TS) reported by patients. Fifty patients were submitted to two sessions of in-office tooth bleaching with 35% hydrogen peroxide used for 2 sessions, each consisting of a single 45-min application, with an interval of 7 days between session. Thirty minutes prior to the procedure, the patient randomly received a single dose of piroxicam (200 mg) or placebo in a double-blind, randomized, crossover design. The TS was evaluated using verbal rate (VRS) and visual analog (VAS) scales during the bleaching procedure and at 24 h after each session. The color changes were assessed by the Vita Bleachedguide scale 1 week after each bleaching session. Risk of TS was calculated from the VRS and analyzed by the McNemar test, while the level of TS was analyzed by the Mann-Whitney test. For the VAS, t-tests were used to compare data from the treatments at each assessment time. Data regarding color changes were subjected to Wilcoxon and Mann-Whitney tests (α=0.05). The preemptive administration of piroxicam did not affect the risk and level of TS compared to placebo, irrespective of the assessment time. The treatment sequence did not affect bleaching effectiveness. In conclusion, the administration of a single dose of piroxicam prior to in-office tooth bleaching was unable to significantly reduce the risk and level of TS.

Resumo Este ensaio clínico avaliou o efeito do uso preemptivo do anti-inflamatório não-esteroidal piroxicam em dose única 30 minutos antes do clareamento de consultório na prevenção de sensibilidade dentária (SD) relatada pelos pacientes. Cinquenta pacientes foram submetidos a duas sessões de clareamento dental em consultório com peróxido de hidrogênio a 35% por 2 sessões, consistindo de aplicação única de 45 minutos, com um intervalo de 7 dias entres as sessões. Trinta minutos antes do procedimento, o paciente recebia aleatoriamente dose única de piroxicam (200 mg) ou do placebo em um desenho duplo-cego, randomizado e cruzado. A SD foi avaliada usando a escalas de gradação verbal (EGV) e visual analógica (EVA) durante o procedimento clareador e 24h após o procedimento. As mudanças de cor foram avaliadas usando a escala Vita Bleachedguide uma semana após cada sessão de clareamento. O risco de SD foi calculado a partir de EGV a analisado pelo teste de McNemar, enquanto o nível de SD foi analisada pelo teste de Mann-Whitney. Para EVA, testes T foram usados para comparar dados dos tratamentos em cada tempo de avaliação. Dados de mudança de cor foram submetidos aos testes de Wilcoxon e Mann-Whitney (α=0.05). A administração preemptiva de piroxicam não afetou o risco e nível de SD quando comparado ao placebo, independentemente do tempo de avaliação. A sequencia de tratamento não afetou a efetividade do clareamento. Como conclusão, a administração de dose única de piroxicam previamente ao clareamento dental de consultório não foi efetiva em reduzir significantemente o risco e nível de SD.

Polymicrobial Leakage and Retention of MTA and Portland Cement in a Model of Apexification

Abstract Objective: To evaluate the sealing capacity and retention of apical barriers made with mineral trioxide aggregate (MTA) and Portland cement (PC). Material and Methods: Fifty-six bovine incisors were sectioned 8 mm above and 12 mm below the cement-enamel junction. The root canal was enlarged with a diamond drill to create a standard 2.5 mm diameter opening. Apical sheets of 5 mm thickness were placed using white MTA-Angelus or white PC. Fifteen samples of each material were exposed to human saliva in a dual chamber apparatus and casting was evaluated at 30 days. Samples without apical barriers and fully sealed samples were used as positive and negative controls (n = 3), respectively. Data were analyzed by Fisher's exact test (p<0.05) after 3 periods: 1 to 10 days (P1); days 11 to 20 (P2); and days 21 to 30 (P3). Then, three 1 mm thick sections were obtained at the apical level of other root samples of each material (n = 10) and the push-out test was performed Results: The leakage rates in P1, P2 and P3 were 60%, 73.3% and 100% for the MTA; and 73.3%, 86.7% and 100% for CP, with no significant difference between materials, regardless of the period analyzed. There were no significant differences between the bond strengths for both cements (p>0.05) Conclusion: Mineral trioxide aggregate and Portland cement apical barriers presented similar sealing ability and bond strength values.

Color changes caused by reduction on the dentin shade composite thickness

Resumo Este estudo objetivou determinar o limiar de redução na espessura do compósito de cor da dentina necessário para resultar em mudanças de cor perceptíveis e aceitáveis em restaurações simuladas. Três sistemas de compósitos (Charisma Diamond, IPS Empress Direct e Filtek Z350 XT) foram avaliados utilizando corpos-de-prova cilíndricos construídos com cores de dentina e esmalte. A opacidade dos compósitos foi avaliada usando cilindros de 1,0 mm de espessura sobre fundo preto e branco. Uma cor inicial padrão foi estabelecida para cada sistema pela combinação de esmalte de 1,0 mm de espessura com 3,0 mm de cilindros de resina na cor de dentina sobre um fundo escuro (n = 9). Em seguida, foram calculadas as alterações de cor (∆E00) causadas por reduções sequenciais de 0,1 mm nos cilindros de resina na cor de dentina. Mudanças de opacidade em cilindros na cor de dentina e cilindros combinados de esmalte e dentina foram também avaliadas após cada redução de espessura. Regressão polinomial foi realizada com médias de ∆E00 em função da espessura dos cilindros na cor de dentina; e os limiares de aceitabilidade (∆E00 = 1,77) e perceptibilidade (∆E00 = 0,81) foram calculados. Regressões lineares também foram realizadas para ∆E00 em função da opacidade dos cilindros na cor de dentina e do par combinado de cilindros de esmalte-dentina. Com exceção da Charisma, os compósitos de esmalte apresentaram menor opacidade do que os de dentina. Alterações de cor perceptíveis e aceitáveis foram observadas quando os cilindros na cor de dentina foram mais finos que 2,0-2,4 mm e 1,1-1,4 mm, respectivamente. Nenhuma diferença entre os sistemas compostos foi observada. Em conclusão, reduções no compósito de dentina menor que 0,6 mm não produziu mudanças de cor perceptíveis, e mudanças de cor clinicamente significantes apenas foram observadas com reduções maiores que 1,6 mm.

Abstract This study determined the reduction threshold in thickness of the dentin shade composite necessary to result in perceptible and acceptable color changes on simulated restorations. Three composite systems (Charisma Diamond, IPS Empress Direct, and Filtek Z350 XT) were evaluated using cylinder-shaped specimens built-up with dentin and enamel shades. The opacity of the composites was assessed using 1.0 mm thick specimens over black and white backgrounds. A baseline color was established for each system by combining 1.0 mm thick enamel shade with 3.0 mm of dentin shade cylinders over a dark background (n = 9). Then, the color changes (∆E00) caused by sequential 0.1 mm reductions on dentin shade cylinders were calculated. Opacity changes on dentin shade cylinders and combined enamel-dentin pair cylinders were also assessed after each thickness reduction. Polynomial regression was performed with averages of ∆E00 as a function of thickness of dentin shade cylinders; and acceptability (∆E = 1.77) and perceptibility (∆E = 0.81) thresholds were calculated. Linear regressions were also performed for ∆E00 as function of opacity of dentin shade cylinders and combined enamel-dentin pair of cylinders. Except for Charisma, enamel shades presented the lowest opacity than dentin one. Perceptible and acceptable color changes were observed for dentin shade cylinders thinner than 2.0-2.4 mm and 1.1-1.4 mm, respectively, were used. No difference among the composite systems was observed. In conclusion, reductions on dentin shade composite lower than 0.6-mm did not yield perceptible color changes, and clinically significant color changes only were observed within reductions higher than 1.6-mm.

Association between in-office and at-home tooth bleaching: a single blind randomized clinical trial

Abstract This controlled randomized clinical trial evaluated the effect of associating at-home and in-office bleaching procedures on tooth sensitivity (TS) and bleaching effectiveness. Forty patients subjected to on session of in-office bleaching with 38% peroxide hydrogen. Subsequently, the patients were randomly allocated to receive a second session of in-office bleaching or to use a tray containing 10% carbamide peroxide delivered during 7 consecutive days. The worst TS score reported during or after each bleaching procedure was recorded using a verbal rating scale and TS risk (score different from 0) was calculated. Color changes were measured 7 days after each in-office session (for patients receiving in-office procedures only) or after the end of at-home bleaching (for the combined protocol), and 6 months after the last procedure for both bleaching protocols. Color was assessed by a spectrophotometer and by color match with the Vita Classical and Bleach guide scales. Statistical analyses were carried out to assess possible differences between the protocols regarding the outcomes and to analyze the effect of time of assessment on color changes. The bleaching protocol did not affect the risk for and the maximum level of TS reported, irrespective of the time of assessment. In the color evaluation, the bleaching protocol also did not affect the ultimate tooth color. In conclusion, after one in-office bleaching session, there was no difference in bleaching effectiveness and TS between performing a second in-office session and associating it with 1-week at-home bleaching.

Resumo Este ensaio clínico controlado e randomizado avaliou o efeito da associação de procedimentos de clareamento caseiro e de consultório na sensibilidade dental (SD) e efetividade clareadora. Quarenta pacientes receberam uma sessão de clareamento de consultório com peróxido de hidrogênio a 38%. Em seguida, os pacientes foram aleatoriamente alocados para receberem uma segunda sessão de clareamento de consultório ou para usar uma moldeira com peróxido de carbamida a 10% por 7 dias consecutivos. O pior score de SD relatada durante ou após cada procedimento clareador foi mensurado usando uma escala verbal, e o risco a SD (escore diferente de 0) foi calculado. Mudança de cor foi mensurada 7 dias após cada sessão de clareamento de consultório (para paciente submetidos a apenas procedimentos de consultório) ou após o fim do clareamento de caseiro (para o protocolo combinado) e 6 meses após o último procedimento clareador para os dois protocolos de clareamento. A cor foi mensurada através de um espectrofotômetro e pelo uso das escalas Vita Clássica e Bleach guide. As análises estatísticas foram realizadas para verificar possíveis diferenças em relação aos desfechos e para analisar o efeito do momento da mensuração nas mudanças de cor. O protocolo clareador não afetou o risco e o nível máximo de SD relatado, independentemente do tempo de avaliação. Na avaliação de cor, o protocolo clareador também não afetou a cor final dos dentes. Como conclusão, após uma sessão de clareamento de consultório, não há diferença na efetividade clareadora e na SD em realizar uma segunda sessão de consultório ou associá-la com uma semana de clareamento caseiro.

Impact of 35% Hydrogen Peroxide on Color and Translucency Changes in Enamel and Dentin

Abstract This study evaluated the effects of tooth bleaching with high-concentration of hydrogen peroxide on alterations of translucency parameter (TP) and color of dentin and enamel. The crown of five human molars was sectioned into four slices parallel to buccal surface. The dentin of external slices containing buccal/ lingual enamel was fully removed with diamond bur; while these slices were used to assess alterations on enamel. Alterations on dentin were assessed into the center of internal slices. The color of specimens was measured over white and black backgrounds using a spectrophotometer (CieL*a*b) at baseline, allowing to calculate the TP by difference between the color measured over each background. Specimens were submitted to three 15-min applications of 35% hydrogen peroxide followed by their storage in water for one-week. Afterwards, the color measurements were repeated at both backgrounds. Color (∆L, ∆a, ∆b and ∆E) and translucency (∆TP) changes were calculated and data individually analyzed by T-test (α = 0.05). Influence of hard tissue and assessment time on each color parameter was also analyzed by 2-way repeated measure ANOVA (α = 0.05). Tooth bleaching resulted in increased lightness for the enamel, whereas no alteration on this parameter occurred for dentin. No difference between the tooth hard tissues was observed regards the other color parameters and ∆E. A slightly reduction on TP was observed only for the enamel. In conclusion, 35% hydrogen peroxide caused similar color and translucency changes on dentin and enamel.

Resumo Este estudo avaliou os efeitos do clareamento dental com peróxido de hidrogênio em alta concentração nas alterações do parâmetro de translucidez (PT) e cor da dentina e esmalte. A coroa de cinco molares humanos foi seccionada em quatro fatias paralelas à superfície vestibular. A dentina das fatias externas contendo esmalte vestibular/ lingual foi totalmente removida com ponta diamantada, sendo estas fatias usadas para verificar as alterações no esmalte. Alterações na dentina foram verificadas no centro das fatias internas. A cor das amostras foi mensurada sobre fundos preto e branco usando um espectrofotômetro (CieL*a*b) no início, permitindo calcular o PT pela diferença de cor medida sobre cada fundo. As amostras foram submetidas a três aplicações de 15 minutos de peróxido de hidrogênio a 35% seguido pelo seu armazenamento em água por uma semana. Após isto, as mensurações de cor foram repetidas em ambos os fundos. Mudanças de cor (∆L, ∆a, ∆b e ∆E) e translucidez (∆PT) foram calculadas e os dados analisados pelo Teste T (α = 0,05). A influência do tecido duro e do momento de avaliação em cada parâmetro de cor foi também analisado através de ANOVA de duas vias para medidas repetidas (α = 0,05). O clareamento dental resultou em maior luminosidade (∆L) para o esmalte, enquanto que nenhuma alteração neste parâmetro ocorreu para a dentina. Nenhuma diferença entre os tecidos duros dentais foi observada em relação aos outros parâmetros de cor e ∆E. Uma leve redução na PT foi observada apenas para o esmalte. Como conclusão, peróxido de hidrogênio a 35% causou similar alteração de cor e translucidez no esmalte e na dentina.

High-concentration carbamide peroxide can reduce the sensitivity caused by in-office tooth bleaching: a single-blinded randomized controlled trial

Abstract Objectives A single-blinded, randomized, parallel clinical trial evaluated the use of 37% carbamide peroxide (CP) on bleaching effectiveness and tooth sensitivity reported by patients undergoing in-office tooth bleaching, in comparison with the results of using 35% hydrogen peroxide. Material and Methods Forty patients were allocated to receive two sessions of in-office tooth bleaching using either 35% hydrogen peroxide (HP) or 37% CP. Each patient's sensitivity level was evaluated during and up to 24 h after bleaching. The effectiveness of the bleaching procedures was evaluated with a spectrophotometer one week after each session and 30 days after the last session. The impact of tooth bleaching on the patients' perceptions regarding smile changes, in addition to the bleaching procedures and their results, were also recorded. Absolute and relative sensitivity risks were calculated. Data on sensitivity level were analyzed using the Mann-Whitney or T-test, and data from the color evaluation were subjected to 2-way repeated measures ANOVA. Results The use of CP reduced the risk and level of tooth sensitivity to values close to zero, whereas the difference between the bleaching agents disappeared after 24 h. An increased bleaching effect was observed for HP, mainly due to an improved reduction of redness and yellowness. Participants perceived improved tooth bleaching for HP and reduced sensitivity for CP, but no differences regarding the comfort of the techniques were noted. Conclusions In our study, 37% CP resulted in reduced tooth sensitivity but decreased the tooth bleaching effectiveness. However, both bleaching agents resulted in high levels of patient satisfaction.

Preemptive use of etodolac on tooth sensitivity after in-office bleaching: a randomized clinical trial

Abstract Purpose: This study determined the effectiveness of the preemptive administration of etodolac on risk and intensity of tooth sensitivity and the bleaching effect caused by in-office bleaching using 35% hydrogen peroxide. Material and methods: Fifty patients were selected for this tripleblind, randomized, crossover, and placebo-controlled clinical trial. Etodolac (400 mg) or placebo was administrated in a single-dose 1 hour prior to the bleaching procedure. The whitening treatment with 35% hydrogen peroxide was carried out in two sessions with a 7-day interval. Tooth sensitivity was assessed before, during, and 24 hours after the procedure using the analog visual scale and the verbal rating scale. Color alteration was assessed by a bleach guide scale, 7 days after each session. Relative risk of sensitivity was calculated and adjusted by session, while overall risk was compared by the McNemar's test. Data on the sensitivity level of both scales and color shade were subjected to Friedman, Wilcoxon, and Mann-Whitney tests, respectively (α=0.05). Results: The preemptive administration of etodolac did not affect the risk of tooth sensitivity and the level of sensitivity reported, regardless of the time of evaluation and scale used. The sequence of treatment allocation did not affect bleaching effectiveness, while the second session resulted in additional color modification. The preemptive administration of etodolac in a single dose 1 hour prior to in-office tooth bleaching did not alter tooth color, and the risk and intensity of tooth sensitivity reported by patients. Conclusion: A single-dose preemptive administration of 400 mg of etodolac did not affect either risk of tooth sensitivity or level of sensitivity reported by patients, during or after the in-office tooth bleaching procedure.

Changes in dental esthetic perceptions of patients subjected to inoffice tooth bleaching / Mudanças nas percepções estéticas odontológicas de pacientes submetidos a clareamento dental de consultório

Objective: This study evaluated changes in the esthetic perceptions of patients subjected to inoffice tooth bleaching. Material and Methods: Fifty participants included in a clinical trial evaluating the in-office tooth bleaching answered two questionnaires about their dental esthetic perceptions. The participants answered the Orofacial Esthetic Scale (OES) questionnaire and the Psychosocial Impact of Dental Aesthetics Questionnaire (PIDAQ) before and after treatment. The average scores observed at baseline were compared with those recorded after tooth bleaching using the paired t-test or the Wilcoxon signed rank test (α = 0.05). Results: Improvement in tooth color (reduction of 5.1 shade guide units) had a positive impact on patients' perceptions. According to PIDAQ, tooth bleaching significantly increased the psychological impact and dental selfconfidence; and reduced esthetic concerns. The OES demonstrated improvements in participants' satisfaction for all questions, except for the one on "facial appearance". However, higher effect size was observed for the question related to tooth color, as expected. Conclusion: Tooth bleaching was associated with an overall improvement in dental esthetic perception, even when only tooth color was affected. (AU)

Objetivo: Este estudo avaliou mudanças nas percepções estéticas de pacientes submetidos a clareamento dental de consultório. Material e Métodos: Cinquenta pacientes incluídos em um ensaio clínico avaliando clareamento dental de consultório responderam a dois questionários sobre suas percepções estética odontológicas. Os participantes responderam ao questionário de escala estética orofacial (EEO) e o questionário de impacto psicossocial da estética orofacial (PIDAQ) antes e após o tratamento. As médias dos escores no início do tratamento foram comparados com aqueles mensurados após o clareamento usando o teste-T pareado ou de Wilcoxon (α = 0,05). Resultados: Melhora na cor dental (redução de 5,1 unidades da escala de cor) teve um impacto positivo nas percepções dos pacientes. De acordo com PIDAQ, o clareamento dental significativamente aumentou o impacto psicossocial e autoconfiança dental, e reduziu as preocupações estéticas. O EEO demonstrou melhora na satisfação dos participantes para todas as questões, exceto para a de "aparência facial". Entretanto, maior efeito foi observado para a questão relacionada à cor dos dentes, como esperado. Conclusão: O clareamento dental foi associado com um aumento geral na percepção estética odontológica, mesmo que apenas a cor dos dentes foi afetada. (AU)

Impact of Microabrasion on the Effectiveness of Tooth Bleaching

Abstract The aim of the present study was to evaluate the effect of prior microabrasion on the teeth color change and tooth bleaching effectiveness. Eight sound molars were mesio-distally sectioned and the halves were randomly allocated to receive enamel microabrasion or non-abrasion (control) in one of surfaces (buccal or lingual), while the remaining surface received the other treatment. The tooth color on baseline was evaluated by spectrophotometer (CieL*a*b system). After the microabrasion procedure, the tooth color was measured again. Following, the specimens were bleached with 35% hydrogen peroxide for two sessions with one-week interval. The color was re-evaluated 7 days after each section and 30 days after the second session. The effect of enamel microabrasion on color changes was evaluated by paired T-test. Deltas L*, a*, b*, and E were calculated and data submitted to 2-way repeated measure ANOVA followed by Tukey`s test. Paired T-test was also used to assess possible differences on the ultimate color achieved after tooth bleaching. Enamel microabrasion reduced the lightness and increased the redness of specimens. Specimens that received microabrasion presented higher values of ∆L* than control after each bleaching procedure; and higher ∆a* after the 2nd bleaching session. However, the prior enamel microabrasion did not affect the ultimate values of color parameters. Despite enamel microabrasion have modified the tooth color, this procedure did not affect the ultimate results achieved with tooth bleaching using a high-concentrated hydrogen peroxide.

Resumo O objetivo deste estudo foi avaliar o efeito da microabrasão prévia na alteração de cor dos dentes e na efetividade do clareamento dental. Oito molares hígidos foram mesio-distalmente seccionados e as metades foram aleatoriamente alocadas para receberem microabrasão do esmalte ou nenhuma abrasão (controle) em uma das faces (vestibular ou lingual), enquanto que a face remanescente recebeu o outro tratamento. A cor inicial dos dentes foi avaliada com um espectrofotômetro (sistema CieL*a*b). Após o procedimento de microabrasão, a cor do dente foi reavaliada. Em seguida, as amostras foram clareadas com peróxido de hidrogênio a 35% por duas sessões com uma semana de intervalo. A cor foi reavaliada 7 dias após cada sessão e 30 dias após a segunda sessão. O efeito da microabrasão do esmalte na mudança de cor foi avaliado pelo teste T pareado. Deltas L*, a*, b* e E foram calculados e os dados submetidos a ANOVA de duas vias para medidas repetidas e teste de Tukey. Teste T pareado também foi usado para verificar possíveis diferenças na cor final alcançada com o clareamento dental. A microabrasão do esmalte reduziu a luminosidade e aumentou a tonalidade vermelha nas amostras. Amostras submetidas a microabrasão apresentaram maiores valores de ∆L* que o controle após cada procedimento clareador, e maior ∆a* após a 2ª sessão de clareamento. Entretanto, a microabrasão prévia do esmalte não afetou os valores finais dos parâmetros de cor. Apesar da microabraão do esmalte ter alterado a cor dental, este procedimento não afetou os resultados finais alcançados com o clareamento dental usando alta concentração de peróxido de hidrogênio.

Polymerization shrinkage stress of composite resins and resin cements - What do we need to know?

Abstract Polymerization shrinkage stress of resin-based materials have been related to several unwanted clinical consequences, such as enamel crack propagation, cusp deflection, marginal and internal gaps, and decreased bond strength. Despite the absence of strong evidence relating polymerization shrinkage to secondary caries or fracture of posterior teeth, shrinkage stress has been associated with post-operative sensitivity and marginal stain. The latter is often erroneously used as a criterion for replacement of composite restorations. Therefore, an indirect correlation can emerge between shrinkage stress and the longevity of composite restorations or resin-bonded ceramic restorations. The relationship between shrinkage and stress can be best studied in laboratory experiments and a combination of various methodologies. The objective of this review article is to discuss the concept and consequences of polymerization shrinkage and shrinkage stress of composite resins and resin cements. Literature relating to polymerization shrinkage and shrinkage stress generation, research methodologies, and contributing factors are selected and reviewed. Clinical techniques that could reduce shrinkage stress and new developments on low-shrink dental materials are also discussed.

An alternative specimen preparation technique for 3-point bending tests on dual-cured dental resin cements / Técnica alternativa de confecção de espécimes para testes de flexão de 3 pontos em cimentos de resina dentária de dupla ativação

The proper mechanical properties of resin cements are essential to the longevity of indirect restoration, whereas the 3-point bending test is recommended for measuring the flexural strength. The ISO 4049 specification requires light-curing of specimens in three consecutive points; however, this approach cannot be used for dual-cured resin cements. The aim of this study was to investigate the effect of two different specimen preparation techniques on the flexural strength and elastic modulus of experimental dual-cured resin cements immediately or 5 after minutes light curing. Experimental dual-cured resin cements were formulated, and the specimens of these cements were confectioned with the dimension of ISO 4049 specification. Light-activation was performed at one or three points immediately or 5 minutes after the insertion of cement into the matrix (n=7), resulting in four experimental conditions (2 methods × 2 moments of light-activation). The three-point bending test was performed and the values of the flexural strength and elastic modulus were recorded. Data were individually analyzed using 2-way ANOVA followed by the Tukey's post hoc test (P<0.05). Regardless of the points of light-activation, the specimens that were light-cured at 3 points showed the highest values of flexural strength. Only for light-activation at 1 point did the time before the light-activation affect the elastic modulus, whereas delayed light-activation had the highest values. In conclusion, the number of lightcuring points on specimen preparation for the 3-point bending test seems to affect the mechanical properties of dual-cured resin cements.

Cimentos resinosos com propriedades mecânicas adequadas são essenciais para a longevidade de restaurações indiretas, sendo que o ensaio de flexão de 3 pontos é recomendado para mensurar a resistência flexural. A especificação ISO 4049 requer a fotoativação das amostras em três pontos consecutivos, entretanto, esta abordagem não pode ser usada para cimentos resinosos duais. O objetivo deste estudo foi investigar o efeito e duas diferentes técnicas de preparo de amostras na resistência flexural e módulo de elasticidade de cimentos resinosos duais experimentais fotoativados imediatamente ou após 5 minutos. Cimentos resinosos duais experimentais foram formulados, e amostras destes cimentos foram confeccionadas com as dimensões da especificação ISO 4049. A fotoativação foi realizada em um ou três pontos imediatamente ou após 5 minutos da inserção do cimento na matriz (n=7), resultando em quatro condições experimentais (2 métodos × 2 tempos antes da fotoativação). O teste de flexão de três pontos foi realizado e os valores de resistência flexural e módulo de elasticidade mensurados. Os dados foram individualmente analisados por ANOVA de dois fatores seguido pelo teste de Tukey (P<0,05). Em relação aos pontos de fotoativação, as amostras que foram fotoativadas em três pontos mostraram os maiores valores de resistência flexural. Apenas para a fotoativação em um ponto, o tempo antes da fotoativação afetou o módulo de elasticidade, sendo que a fotoativação tardia apresentou maiores valores. Em conclusão, o número de pontos de fotoativação no preparo das amostras para teste de flexão de 3 pontos parece afetar as propriedades mecânicas dos cimentos resinosos.