Effect of violet LED light on in-office bleaching protocols: a randomized controlled clinical trial

Abstract Objective This study evaluated the clinical effect of violet LED light on in-office bleaching used alone or combined with 37% carbamide peroxide (CP) or 35% hydrogen peroxide (HP). Methodology A total of 100 patients were divided into five groups (n=20): LED, LED/CP, CP, LED/HP and HP. Colorimetric evaluation was performed using a spectrophotometer (ΔE, ΔL, Δa, Δb) and a visual shade guide (ΔSGU). Calcium (Ca)/phosphorous (P) ratio was quantified in the enamel microbiopsies. Measurements were performed at baseline (T 0 ), after bleaching (T B ) and in the 14-day follow-up (T 14 ). At each bleaching session, a visual scale determined the absolute risk (AR) and intensity of tooth sensitivity (TS). Data were evaluated by one-way (ΔE, Δa, ΔL, Δb), two-way repeated measures ANOVA (Ca/P ratio), and Tukey post-hoc tests. ΔSGU and TS were evaluated by Kruskal-Wallis and Mann-Whitney, and AR by Chi-Squared tests (a=5%). Results LED produced the lowest ΔE (p<0.05), but LED/HP promoted greater ΔE, ΔSGU and Δb (T 14 ) than HP (p<0.05). No differences were observed in ΔE and ΔSGU for LED/CP and HP groups (p>0.05). ΔL and Δa were not influenced by LED activation. After bleaching, LED/CP exhibited greater Δb than CP (p>0.05), but no differences were found between these groups at T 14 (p>0.05). LED treatment promoted the lowest risk of TS (16%), while HP promoted the highest (94.4%) (p<0.05). No statistical differences of risk of TS were found for CP (44%), LED/CP (61%) and LED/HP (88%) groups (p>0.05). No differences were found in enamel Ca/P ratio among treatments, regardless of evaluation times. Conclusions Violet LED alone produced the lowest bleaching effect, but enhanced HP bleaching results. Patients treated with LED/CP reached the same efficacy of HP, with reduced risk and intensity of tooth sensitivity and none of the bleaching protocols adversely affected enamel mineral content.

Conhecendo a terapia clareadora: efeito do local de aplicação e do volume de gel clareador na alteração cromática e sensibilidade pós-operatória: estudo clínico randomizado / Knowing the whitening therapy: effect of the application site and the volume of whitening gel on the chromatic alteration and postoperative sensitivity: randomized clinical trial

Embora o sucesso do clareamento dental tenha sido considerado dependente da dosagem utilizada, este procedimento ainda é cercado de importantes lacunas no que se refere à posologia utilizada e a forma de aplicação dos produtos clareadores. O objetivo deste estudo foi avaliar clinicamente o efeito do posicionamento do gel clareador e a influência de seu volume na alteração cromática e sensibilidade pósoperatória. Para o estudo referente ao posicionamento do gel clareador, trinta pacientes foram selecionados e alocados em três grupos (n=10): GI-aplicação na metade cervical, GII- aplicação na metade incisal, GIII- aplicação em toda a face vestibular. A quantidade e o tempo de aplicação do gel Peróxido de Hidrogênio a 35% foram padronizados. A análise de cor foi realizada pelo ΔE e WID (índice de clareamento), utilizando os valores obtidos pelas leituras realizadas em espectrofotômetro digital. As leituras foram realizadas nas regiões cervical e incisal dos dentes. A sensibilidade espontânea foi avaliada por questionário e a sensibilidade provocada através da análise termosensorial (TSA). As análises foram realizadas em 5 tempos: baseline, após 1º sessão clareadora (S), 2ºS e 3ºS e 14 dias após o término do clareamento. Os dados foram analisados pelo modelo de regressão linear com efeitos mistos e pós-teste por contrastes ortogonais (p< 0,05). Pode-se observar que, em relação à alteração cromática, apesar da região incisal ser momentaneamente favorecida pela aplicação do gel, ao final do tratamento, a restrição do local de aplicação à região cervical ou incisal proporcionaram resultados semelhantes aos obtidos quando o gel foi aplicado em toda a face vestibular. Quanto à sensibilidade, apenas o grupo que recebeu gel clareador na porção cervical apresentou sensibilidade espontânea. Já na análise termosensorial, o grupo que recebeu gel na face vestibular exerceu menor influência no limiar de sensação térmica. Paralelamente, no segundo estudo, em que se avaliou a influência do volume de gel clareador, os trinta pacientes foram alocados em três grupos: GI- 0,025mL, GII-0,05mL, GIII-0,10mL, e receberam o produto apenas nos caninos inferiores (n=10). A análise da alteração cromática foi realizada utilizando um espectrofotômetro digital portátil, sendo calculados os valores de ΔE, ΔL*, Δa*, Δb*, bem como o índice de clareamento (WID). A sensibilidade espontânea foi avaliada por aplicação de questionário e a sensibilidade provocada através da análise termosensorial. As análises foram realizadas em 5 tempos: baseline, após 1º, 2º e 3º sessões clareadoras e 14 dias após o término. Os dados foram analisados pelos testes Anova dois fatores com medidas repetidas e pós-teste de Tukey (p< 0,05). Observouse que o ΔE e o ΔL* foram semelhantes entre os grupos ao final da terapia clareadora. Os valores de Δa*, Δb*, bem com o WID foram mais intensos no grupo que recebeu 0,10mL, que também apresentou a maior sensibilidade espontânea e estimulada. Assim, através dos dois estudos realizados, pode-se concluir que ao final do tratamento, a alteração cromática independe do local de aplicação do gel clareador, entretanto, a região incisal, apresenta saturação cromática mais rápida que a região cervical. Constatou-se também que quanto maior o volume, maior a resposta clareadora nas coordenadas especificas e no índice de clareamento, entretanto, não apresentando diferença na alteração cromática e na luminosidade analisada. Já a sensibilidade dental foi mais intensa quando a aplicação do gel foi concentrada na região cervical, sendo também marcadamente proporcional ao volume empregado. Com isso, em relação ao grupo dental analisado, a redução do posicionamento do gel clareador para a incisal e a utilização de um volume intermediário (0,05mL), proporcionaram efeitos positivos para a alteração cromática e redução da resposta de sensibilidade(AU)

Although the success of tooth whitening was considered to be dependent on the dosage used, this procedure still has important gaps with regard to the dosage used and the form of application of the whitening products. The aim of this study was to evaluate clinically the effect of the positioning of the bleaching gel and the influence of its volume on the chromatic alteration and on the postoperative sensitivity. For the study of the positioning of the bleaching gel, thirty patients were selected and allocated into three groups (n = 10): GI- application on the cervical half, GII- application on the incisal half, GIII- application on the entire buccal surface. The amount and time of application of the 35% hydrogen peroxide gel were standardized. The color analysis was performed by ΔE and WID (lightening index), using the values obtained in the readings performed on a digital spectrophotometer. The readings were made in the cervical and incisal regions of the teeth. Spontaneous sensitivity was assessed using a questionnaire and the sensitivity caused by thermo-sensory analysis (TSA). The analyzes were carried out in 5 stages: baseline, after the 1st whitening session (S), 2ºS and 3ºS and 14 days after the end of the whitening. The data were analyzed using the linear regression model with mixed effects and post-test using orthogonal contrasts (p < 0.05). It can be seen that, regarding the chromatic alteration, although the incisal region is momentarily favored by the application of the gel, at the end of the treatment the restriction of the application site to the cervical or incisal region provided results similar to those obtained when the gel was applied throughout the vestibular face. As for sensitivity, only the group that received whitening gel in the cervical portion had spontaneous sensitivity. In the thermosensory analysis, the group that received gel on the vestibular face had less influence on the threshold of thermal sensation. In parallel, in the second study, in which the influence of the volume of the bleaching gel was evaluated, the thirty patients were allocated into three groups: GI-0.025mL, GII0.05mL, GIII-0.10mL, and received the product only in lower canines (n = 10). The chromatic alteration analysis was performed using a portable digital spectrophotometer, being calculated the values of ΔE, ΔL *, Δa *, Δb *, as well as the bleaching index (WID). Spontaneous sensitivity was assessed by applying a questionnaire and sensitivity by thermo-sensory analysis. The analyzes were carried out in 5 stages: baseline, after 1st, 2nd and 3rd whitening sessions and 14 days after the end. Data were analyzed using two-way ANOVA tests with repeated measures and Tukey's post-test (p < 0.05). It was observed that ΔE and ΔL * were similar between the groups at the end of the bleaching therapy. The values of Δa *, Δb *, as well as the WID were more intense in the group that received 0.10mL, which also showed the highest spontaneous and stimulated sensitivity. Thus, through the two studies carried out, it can be concluded that at the end of the treatment the chromatic alteration does not depend on the application site of the whitening gel, however, the incisal region, presents chromatic saturation faster than the cervical region. It was also found that the greater the volume, the greater the bleaching response in the specific coordinates and in the bleaching index, however, showing no difference in the chromatic alteration and in the analyzed luminosity. The tooth sensitivity was more intense when the application of the gel was concentrated in the cervical region, being also markedly proportional to the volume used. Thus, in relation to the analyzed dental group, the reduction of the positioning of the bleaching gel to the incisal and the use of an intermediate volume (0.05mL), provided positive effects for the chromatic alteration and reduction of the sensitivity response(AU)

In-office tooth bleaching with 38% hydrogen peroxide promotes moderate/severe pulp inflammation and production of ll-1ß, TNF-ß, GPX, FGF-2 and osteocalcin in rats

Abstract Objectives: To study the intensity of inflammatory infiltrate and production of interleukin-1β (ll-1β), tumor necrosis factor-β (TNF-β), fibroblast growth factor-2 (FGF-2), glutathione peroxidase (GPX), and osteocalcin in response to in-office tooth bleaching in rats. Material and Methods: Twenty male Wistar rats were randomized into four groups (n=5) according to the received treatment (tooth bleaching or no treatment - control) and the period of euthanasia after treatment (24 h or 10 days). We performed tooth bleaching using a 38% hydrogen peroxide gel on maxillary and mandibular incisors. After euthanasia, incisors (20 per group) were processed for histological analysis, immunohistochemistry staining of ll-1β, TNF-β, FGF-2 and GPX and osteocalcin by immunofluorescence. We analyzed data using the Mann-Whitney and Kruskal-Wallis/Dunn tests (p<0.05). Results: The bleached groups presented statistically significant differences regarding the pulp inflammation stage compared with the control groups. Bleached teeth showed moderate/severe inflammatory infiltrate and control groups presented absent inflammatory cells or a negligible number of mononuclear cells (p<0.001) at two times (24 h and 10 days). There was strong staining for ll-1β, TNF-β, and GPX in bleached groups at 24 h and strong staining for ll-1β, TNF-β, GPX and FGF-2 at 10 days. After 10 days of tooth bleaching, the bleached group showed a statistically superior amount of osteocalcin than the other groups (p<0.01). Conclusions: Tooth bleaching with 38% hydrogen peroxide causes severe pulp inflammation, but characteristics of tissue repair after 10 days.

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.

Evaluation of an experimental rat model for comparative studies of bleaching agents

ABSTRACT Dental materials in general are tested in different animal models prior to the clinical use in humans, except for bleaching agents. Objectives To evaluate an experimental rat model for comparative studies of bleaching agents, by investigating the influence of different concentrations and application times of H2O2 gel in the pulp tissue during in-office bleaching of rats’ vital teeth. Material and Methods The right and left maxillary molars of 50 Wistar rats were bleached with 20% and 35% H2O2 gels, respectively, for 5, 10, 15, 30, or 45 min (n=10 rats/group). Ten animals were untreated (control). The rats were killed after 2 or 30 days, and the maxillae were examined by light microscopy. Inflammation was evaluated through histomorphometric analysis with inflammatory cell count in the coronal and radicular thirds of the pulp. Fibroblasts were also counted. Scores were attributed to odontoblastic layer and vascular changes. Tertiary dentin area and pulp chamber central area were measured histomorphometrically. Data were compared by analysis of variance and Kruskal-Wallis test (p<0.05). Results After 2 days, the amount of inflammatory cells increased in the coronal pulp occlusal third up to the 15-min application groups of each bleaching gel. In the groups exposed to each concentration for 30 and 45 min, the number of inflammatory cells decreased along with the appearance of necrotic areas. After 30 days, reduction on the pulp chamber central area and enlargement of the tertiary dentin area were observed, without the detection of inflammation areas. Conclusion The rat model of extracoronal bleaching showed to be adequate for studies of bleaching protocols, as it was possible to observe alterations in the pulp tissues and tooth structure caused by different concentrations and application periods of bleaching agents.

Evaluation of an experimental rat model for comparative studies of bleaching agents

ABSTRACT Dental materials, in general, are tested in different animal models prior to their clinical use in humans, except for bleaching agents. Objectives To evaluate an experimental rat model for comparative studies of bleaching agents by investigating the influence of different concentrations and application times of H2O2 gel in the pulp tissue during in-office bleaching of rats’ vital teeth. Material and methods The right and left maxillary molars of 50 Wistar rats were bleached with 20% and 35% H2O2 gels, respectively, for 5, 10, 15, 30, or 45 min (n=10 rats/group). Ten animals (control) were untreated. The rats were killed after 2 or 30 days, and the maxillae were examined by light microscopy. Inflammation was evaluated by histomorphometric analysis with inflammatory cell counting in the coronal and radicular thirds of the pulp. The counting of fibroblasts was also performed. Scores were attributed to the odontoblastic layer and to vascular changes. The tertiary dentin area and the pulp chamber central area were histomorphometrically measured. Data were compared by the analysis of variance and the Kruskal-Wallis test (p<0.05). Results After 2 days, the amount of inflammatory cells increased in the occlusal third of the coronal pulp until the time of 15 min for both concentrations of bleaching gels. In 30 and 45 min groups of each concentration, the number of inflammatory cells decreased along with the appearance of necrotic areas. After 30 days, a reduction in the pulp chamber central area and an enlargement of tertiary dentin area were observed without the detection of inflammation areas. Conclusion The rat model of extra coronal bleaching showed to be adequate for bleaching protocols studies, as it was possible to observe alterations in the pulp tissues and in the tooth structure caused by different concentrations and periods of application of bleaching agents.

Effectiveness of nano-calcium phosphate paste on sensitivity during and after bleaching: a randomized clinical trial

The study aimed to evaluate the effectiveness of in-office bleaching and associated tooth sensitivity on application of nano-calcium phosphate paste as desensitizing agent. Bleaching was performed with 35% hydrogen peroxide gel in 40 patients who were randomly divided into placebo and nano-calcium phosphate paste groups. Bleaching efficacy (BE) was evaluated using a value-oriented Vita shade guide. Tooth sensitivity was recorded using a numeric rating scale (0–4) during bleaching and up to 48 h after each session. The primary outcome of absolute risk of tooth sensitivity was compared using the Fisher’s exact test (α = 0.05). The intensity of tooth sensitivity and the efficacy of in-office bleaching were also statistically evaluated. No significant differences in absolute risk and intensity of tooth sensitivity were detected between the groups (p = 1.0 and p = 0.53, respectively). BE was also found to be similar between the groups (p = 0.67). Although the use of a nano-calcium phosphate paste associated with fluoride and potassium nitrate did not influence the whitening outcome, but it also did not reduce bleaching-induced tooth sensitivity.

Influência do perborato de sódio na desadaptação marginal de tampões cervicais confeccionados com diferentes materiais / Influence of sodium perborate on marginal misfit in cervical barrier made by different materials

Frente aos efeitos deletérios da reabsorção cervical externa, é de grande importância a confecção do tampão cervical quando do clareamento de dentes despolpados. Objetivo: este estudo avaliou a influência do perborato de sódio (PS) e o número de aplicações na desadaptação marginal do tampão cervical. Metodologia: Vinte e quatro pré-molares inferiores foram divididos em três grupos (n=8), de acordo com o material utilizado na confecção do tampão: Cimento de Ionômero de Vidro (CIV), Bioplic (BP) e Agregado de Trióxido Mineral branco (MTA B). Após a aplicação dos materiais, os espécimes foram aplainados e registrados por uma câmera fotográfica acoplada ao Esteromicroscópio. O PS diluído em soro fisiológico foi acomodado sobre os tampões e em seguida selados por 15 dias. Em seguida, o PS foi removido e novas imagens realizadas no Estereomicroscópio. Este ciclo foi repetido, determinando três períodos de avaliação. A desadaptação marginal foi calculada por meio do Software Image J, e os dados submetidos ao teste estatístico de Kruskal-wallis com post-hoc de Dunn para comparação intergrupos (α menor ou igual a 0,05), e teste de Friedman para comparação intragrupos (α menor ou igual a 0,05). Resultados: Verificou-se um aumento significativo na desadaptação marginal do BP e CIV entre os períodos controle e 2ª sessão. Na comparação intergrupos, o MTA B apresentou maior desadaptação quando comparado ao BP em todos os períodos. Conclusão: o PS foi capaz de aumentar a desadaptação marginal de dois materiais após 30 dias, e o MTA B seria o material menos indicado para confecção do tampão cervical...

Due to the deleterious effects of the external cervical resorption, it is extremely important the use of an appropriate cervical barrier in non-vital bleaching. Objective: this study evaluated the influence of sodium perborate (SP) and the number of its application on cervical barrier marginal misfit. Methods: twenty- four human premolars were divided into 3 groups (n=8) according to the material used in manufacture of barrier: Glass Ionomer cement (GIC), Bioplic (BP) and white Mineral Trioxide aggregate (W MTA). After the application of the materials, specimens were planed and registered with a camera mounted in a stereomicroscope. SP diluted in saline was accommodated on the barrier and then sealed for 15 days. Afterwards SP was removed and images were again obtained with stereomicroscope. This cycle was repeated once more, determine three periods of evaluation. Marginal misfit was obtained through Image J software, and the data was subjected to two-way analysis of variance, followed by Tukey post-hoc test (α or less 0,05). Results: there was a significant increase in the marginal misfit of BP and CIV between periods control and 2nd session. In the intergroup comparison, the MTA B showed larger marginal misfit when compared to BP in all periods. Conclusion: the PS was able to increase marginal misfit of 2 materials after 30 days, and the MTA B would be less suitable for making the cervical barrier...

Dental bleaching with a 10% hydrogen peroxide product: A six-month clinical observation.

Context: The possibility of bleaching vital teeth with peroxide-based products considerably revolutionized esthetic dentistry. Aim: The aim of this clinical study was to evaluate tooth color change and dental sensitivity after exposure to preloaded film containing a 10% hydrogen peroxide whitening system (Opalescence Trθswhite Supreme). Materials and Methods: A total of 13 volunteers, aged 18 to 25 years, participated in this study. The patients used the whitening system once a day for 60 minutes during the 8-day study. For maxillary incisors and canines, the color change was visually evaluated with the Vita color scale before, immediately, and six months after the treatment. Tooth sensitivity was evaluated during the daily gel applications. All whitening applications were done in office and under the supervision of a dental professional. Statistical Analysis Used: The results were analyzed using the Friedman Test (nonparametric repeated measures ANOVA) at a level of 5%, and Dunn's Multiple Comparison Test at the level of 5%. Results: It was verified that the original mean color values observed at the baseline analysis differed significantly from those observed immediately after bleaching, as well as from those seen in the analysis at six months ( P = 0.001). There was no significant difference between the mean color values observed in the immediate time and in the analysis at six months ( P = 0.474). No tooth sensitivity was observed in any patients. Conclusion: It was concluded that the bleaching technique using the 10% hydrogen peroxide system was effective in a short period of time without tooth sensitivity during applications.

High-efficiency tooth bleaching using non-thermal atmospheric pressure plasma with low concentration of hydrogen peroxide

Light-activated tooth bleaching with a high hydrogen peroxide (HP; H2O2) concentration has risks and the actual role of the light source is doubtful. The use of conventional light might result in an increase in the temperature and cause thermal damage to the health of the tooth tissue. Objective This study investigated the efficacy of tooth bleaching using non-thermal atmospheric pressure plasma (NAPP) with 15% carbamide peroxide (CP; CH6N2O3) including 5.4% HP, as compared with conventional light sources. Material and Methods Forty human teeth were randomly divided into four groups: Group I (CP+NAPP), Group II (CP+plasma arc lamp; PAC), Group III (CP+diode laser), and Group IV (CP alone). Color changes (∆E) of the tooth and tooth surface temperatures were measured. Data were evaluated by one-way analysis of variance (ANOVA) and post-hoc Tukey's tests. Results Group I showed the highest bleaching efficacy, with a ∆E value of 1.92-, 2.61 and 2.97-fold greater than those of Groups II, III and IV, respectively (P<0.05). The tooth surface temperature was maintained around 37°C in Group I, but it reached 43°C in Groups II and III. Conclusions The NAPP has a greater capability for effective tooth bleaching than conventional light sources with a low concentration of HP without causing thermal damage. Tooth bleaching using NAPP can become a major technique for in-office bleaching in the near future. .

Resposta imune a agentes clareadores e reparadores dentais / Immune reponse to dental bleaching agents and repairers

Embora eficientes quanto ao aspecto estético, as técnicas de clareamento endógeno ainda apresentam graus variáveis de toxidade e muitas vezes podem levar ao desenvolvimento de reabsorção cervical inflamatória. Neste estudo, avaliou-se a resposta imune aos efeitos da aplicação de agentes clareadores tradicionalmente utilizados na clínica, assim como os de agentes reparadores utilizados no tratamento destas alterações. Inoculou-se, os agentes clareadores, perborato de sódio misturado ao peróxido de hidrogênio...

Ex-vivo evaluation of the intrapulpal temperature variation and fracture strength in teeth subjected to different external bleaching protocols

This study evaluated the influence of bleaching protocols on intrapulpal temperature and fracture strength of the bleached teeth. Ninety maxillary incisors were assigned to 9 groups (n=10): G1: 35 percent carbamide peroxide (35 percent CP), G2: 38 percent hydrogen peroxide (38 percent HP), G3: halogen light, G4: LED-laser, G5: 35 percent CP + halogen light, G6: 38 percent HP + halogen light, G7: 35 percent CP + LED-laser, G8: 38 percent HP + LED-laser, and G9: no treatment (control). Pulp space was widened, a thermocouple was introduced through the apex up to the pulp chamber and the temperature was recorded (°C). The fracture strength (kN) was determined using an Instron machine. Data were analyzed by ANOVA and Tukey's test (p<0.05). The halogen light alone (1.10 ± 0.24) (G3) and associated with 38 percent HP (1.15 ± 0.30) (G6) produced the highest temperature increase, statistically different (p<0.05) from the other groups. G1 (0.15 ± 0.06) and G6 (0.19 ± 0.07) produced the lowest values, statistically different (p<0.05) from G5 (0.65 ± 0.49). The bleaching protocols increased the temperature, but no increment exceeded the critical value of 5.6°C. Neither 35 percent CP nor 38 percent HP or the light sources alone altered the fracture strength of the teeth.

Este estudo avaliou a influência de protocolos de clareamento na temperatura intrapulpar e resistência à fratura de dentes clareados. Noventa incisivos superiores foram divididos em 9 grupos (n=10): G1: peróxido de carbamida a 35 por cento (PC 35 por cento), G2: peróxido de hidrogênio a 38 por cento (PH 38 por cento), G3: luz halógena, G4: LED-laser, G5: PC 35 por cento + luz halógena, G6: PH 38 por cento + luz halógena, G7: PC 35 por cento + LED-laser, G8: PH 38 por cento + LED-laser e G9: sem tratamento (controle). O canal radicular foi alargado, um termopar foi introduzido no ápice até a câmara pulpar e a temperatura foi calculada (°C). A resistência à fratura (kN) foi determinada em máquina Instron. Os dados foram analisados por análise de variância e teste de Tukey (p>0,05). A luz halógena utilizada isoladamente (1,10 ± 0,24) (G3) e associada ao PH 38 por cento (1,15 ± 0,30) (G6) proporcionaram os maiores valores de temperatura, sendo estatisticamente diferentes dos demais grupos (p<0,05). O G1 (0,15 ± 0,06) e o G6 (0,19 ± 0,07) produziram os menores valores de resistência à fratura, sendo estatisticamente diferentes (p<0,05) do G5 (0,65 ± 0,49). Os protocolos de clareamento aumentaram a temperatura, mas nenhum incremento excedeu o valor crítico de 5,6oC. O PC 35 por cento, PH 38 por cento e as fontes de luz utilizadas isoladamente não alteraram a resistência à fratura dos dentes.

Fracture resistance of teeth subjected to internal bleaching and restored with different procedures

This study evaluated the fracture resistance of teeth submitted to internal bleaching and restored with different procedures. Forty maxillary incisors were endodontically treated and assigned to 4 groups (n=10): G1- restored with composite resin (CR), G2- bleached with hydrogen peroxide (HP) and restored with CR, G3- restored with CR and fiberglass posts (CR + posts) and G4- bleached and restored with CR + posts. HP was applied in the buccal surface and pulp chamber 3 times at each one of 2 sessions with an interval of 7 days between them. Additional 10 sound incisors were subjected to fracture strength test (gold standard). The fracture strength (kN) was determined in an Instron machine. Data were analyzed by ANOVA and Tukey-Kramer test (α=0.05). The untreated teeth (gold standard) showed the highest (p<0.05) fracture strength (0.43 ± 0.16). Teeth restored with CR (G1) without internal bleaching had the lowest (p<0.05) fracture strength (0.23 ± 0.11). Teeth bleached and restored with CR (G2) (0.26 ± 0.10), restored with CR + posts ithout internal bleaching (G3) (0.31 ± 0.17) and, bleached and restored with CR + posts (G4) (0.33 ± 0.12) had intermediate values, sometimes similar to the group with the highest value, sometimes similar to the group with the lowest value. In conclusion, as far as the fracture strength is concerned, teeth subjected to internal bleaching can be restored with composite resin alone, as the use of posts in these teeth did not increase their resistance.

Este estudo avaliou a resistência à fratura de dentes submetidos ao clareamento interno restaurados com diferentes procedimentos. Quarenta incisivos superiores foram tratados endodonticamente e divididos em 4 grupos (n = 10): G1- restaurados com resina composta (RC), G2- clareados com peróxido de hidrogênio (PH) e restaurados com o RC, G3- restaurado com RC e pinos de fibra de vidro (RC + pinos) e G4- clareados e restaurados com RC + pinos. O PH foi aplicado na superfície vestibular e câmara pulpar 3 vezes por sessão, por 2 sessões com intervalo de 7 dias entre elas. Dez dentes hígidos adicionais foram submetidos a teste fratura (padrão ouro). A resistência à fratura (kN) foi determinada em máquina Instron. Os dados foram analisados por Análise de Variânica e teste de Tukey-Krammer (α= 0,05). Os dentes não tratados (padrão ouro) apresentaram a maior resistência à fratura (0,43 ± 0,16) (p <0,05). Os dentes restaurados com RC (G1) apresentaram a menor resistência à fratura (0,23 ± 0,11) (p <0,05). Os dentes clareados e restaurados com RC (G2) (0,26 ± 0,10), restaurado com RC + pinos (G3) (0,31 ± 0,17) e os clareados e restaurados com RC + pinos (G4) (0,33 ± 0,12) apresentaram valores intermediários, ora semelhantes ao do grupo com o maior valor, ora similares ao grupo de valores mais baixos. Pode-se concluir que os dentes submetidos ao clareamento interno podem ser restaurados com apenas resina composta.

Effect of bleaching agent on dental ceramics roughness

The aim of this study was to assess the effect of bleaching agents (10% and 16% carbamide peroxide) on the roughness of two dental ceramics in vitro, and to analyze the surface by scanning electronic microscopy (SEM). Two bleaching agents (10% and 16% / Whiteness, FGM Gel) and two microparticle feldspathic ceramics (Vita VM7 and Vita VM13) were used. Forty disks of Vita VM7 and Vita VM13 ceramic were manufactured, measuring 4mm in diameter and 4mm high, in accordance with the manufacturers’ recommendations, and were divided into 4 groups (n=10): (1) VM7 + Whiteness 10%; (2) VM7 + Whiteness 16%; (3) VM13 + Whiteness 10%; (4) VM13 + Whiteness 16%. The bleaching agent was applied for 8 hours a day for 15 days and during the intervals the test specimens were stored in distilled water at 37°C. The roughness (Ra) of the test specimens was evaluated before and after exposure to the bleaching agents using a laser roughness meter and the topographic description was analyzed by SEM. The statistical analysis of roughness data showed significant differences in the VM7 groups, using paired t-test, p=0.05 (VM7 + Whiteness 10%: p=0.002; VM7 + Whiteness 16%: p=0.001) and two-sample t-test (VM7 p=0,047), and no significant difference was found among VM13 groups. The qualitative SEM analysis showed different degrees of surface changes. The results suggest that the roughness of the tested ceramic surfaces increased after exposure to the bleaching agents.

O objetivo do estudo foi avaliar o efeito de agente clareador (10% e 16% de peroxido de carbamida) na rugosidade de duas ceramicas dentais in vitro e analisar a superficie atraves da microscopia eletronica de varredura (SEM). Foram utilizados dois agentes clareadores (10% e 16% / Whiteness, FGM Gel) e duas ceramicas feldspaticas microparticuladas (Vita VM7 e Vita VM13). Foram confeccionados quarenta discos de ceramica Vita VM7 e Vita VM13, com 4mm de diametro e 4mm de altura, de acordo com as recomendacoes do fabricante, sendo divididos em 4 grupos (n=10): G1- VM7 + Whiteness 10%, G2- VM7 + Whiteness 16%, G3- VM13 + Whiteness 10% e G4- VM13 + Whiteness 16%. O agente clareador foi aplicado por 8 horas durante 15 dias e durante os intervalos os corpos de prova (cp) ficavam armazenados em agua destilada a 37°C. A rugosidade (Ra) dos cp foi avaliada antes e apos a exposicao aos agentes clareadores utilizando o rugosimetro a laser Perthomether S8P, e a descricao topografica foi analisada no MEV. A analise estatistica na rugosidade mostrou diferenca significante entre os grupos da VM7, usando o teste pareado, p=0.05 (VM7 + Whiteness 10%: p=0.002; VM7 + Whiteness 16%: p=0.001) e nao foi encontrado diferenca estatistica para os grupos da VM13. A descricao qualitativa no SEM evidenciou alteracao nas superficies em diferentes graus. Os resultados sugeriram que as superficies das ceramicas testadas aumentaram a rugosidade apos a exposicao ao agente clareador.