Effect of ELVAX polymer subgingival implants with echistatin on extracted and reimplanted rats' teeth.

To investigate the effect of ELVAX polymer subgingival implants incorporated with echistatin peptide on incisor reimplanted tooth in rats. Forty-two male Wistars rats were divided into two groups: echistatin-treated rats (E) and control rats (C). The animals had their right maxillary incisors extracted and treated according to the International Association of Dental Traumatology replantation protocol. The extra-alveolar dry period was 30 and 60 min, and the post-surgical experimental periods were 15, 60, and 90 days. The samples were stained with H&E and analyzed for the presence of an inflammatory response, incidence of resorptions, and dental ankylosis. Results were statistically analyzed (p < 0.05). The presence of inflammatory resorption was significantly higher in group C at 30 and 60 min extra-alveolar time, in the 15-day postoperative period as compared with the E group (p < 0.05). Dental ankylosis was significantly more prevalent in group E in 30 min extra-alveolar time and 15 days postoperative period (p < 0.05). However, in 60 min extra-alveolar time and 60 days postoperative period, dental ankylosis was more prevalent in C group (p < 0.05). The use of ELVAX subgingival implants with echistatin demonstrated therapeutic potential in preventing the experimental resorption process after replantation of maxillary incisors in rats.

Ultrasonic agitation reduces the time of calcium hydroxide antimicrobial effect and enhances its penetrability.

OBJECTIVES: The objective of the present work was to evaluate the ultrasonic agitation, time and vehicle (propylene glycol or distilled water) on the antimicrobial potential and penetrability of calcium hydroxide pastes on infected dentin by means of Confocal Laser Scanning Microscopy (CLSM) and microbiological culture (MC). MATERIALS AND METHODS: Dentin specimens were infected with Enterococcus faecalis using a new contamination protocol of 5 days. The specimens were divided into eight groups and dressed with the pastes for 7 or 15 days: G1) calcium hydroxide (CH) + propylene glycol (prop)/7 days (d), G2) CH + prop/7d + ultrasonic agitation (U), G3) CH + distilled water (dw)/7d, G4) CH + dw/7d + U, G5) CH + prop/15d, G6) CH + prop/15d + U, G7) CH + dw/15d, G8) CH + dw/15d + U. The ultrasonic activation was made for 1 min in both directions with a plain point insert. After medications removal, the images obtained by CLSM showed the viable (green) and dead (red) bacteria with Live and Dead dye. By the MC, the dentinal wall debris obtained by burs were collected for colony counts. For the penetration test, the Rodamine B dye was added to the CH pastes and analyzed by CLSM. RESULTS: The 7 and 15-days CH + prop+U pastes performed better antimicrobial efficacy, followed by the CH + dw+U/15d paste. CONCLUSIONS: All pastes demonstrated better penetration and antimicrobial activity against E. faecalis when agitated with ultrasound, even in periods of up to seven days. The propylene glycol vehicle showed better results. CLINICAL RELEVANCE: Agitation of the dressing that remains for less time inside the root canal can optimize the decontamination of endodontic treatment.

The antimicrobial effect of new and conventional endodontic irrigants on intra-orally infected dentin.

OBJECTIVES: To evaluate if the incorporation of antimicrobial compounds to chelating agents or the use of chelating agents with antimicrobial activity as 7% maleic acid and peracetic acid show similar disinfection ability in comparison to conventional irrigants as sodium hypochlorite or iodine potassium iodide against biofilms developed on dentin. MATERIALS AND METHODS: The total bio-volume of live cells, the ratio of live cells and the substratum coverage of dentin infected intra-orally and treated with the irrigant solutions: MTAD, Qmix, Smear Clear, 7% maleic acid, 2% iodine potassium iodide, 4% peracetic acid, 2.5% and 5.25% sodium hypochlorite was measured by using confocal microscopy and the live/dead technique. Five samples were used for each irrigant solution. RESULTS: Several endodontic irrigants containing antimicrobials as clorhexidine (Qmix), cetrimide (Smear Clear), maleic acid, iodine compounds or antibiotics (MTAD) lacked an effective antibiofilm activity when the dentin was infected intra-orally. The irrigant solutions 4% peracetic acid and 2.5-5.25% sodium hypochlorite decrease significantly the number of live bacteria in biofilms, providing also cleaner dentin surfaces (p < 0.05). CONCLUSIONS: Several chelating agents containing antimicrobials could not remove nor kill significantly biofilms developed on intra-orally infected dentin, with the exception of sodium hypochlorite and 4% peracetic acid. Dissolution ability is mandatory for an appropriate eradication of biofilms attached to dentin.

Effect of sputter-coating on cracking of root-end surfaces after ultrasonic retrograde preparation--a SEM study of resected root apices and their respective impressions.

The aim of this study was to evaluate in vitro the effect of sputter-coating for SEM analysis on the formation of cracks on root-end surfaces after retrograde cavity preparation with ultrasonic tips. Root-end cavities were prepared with either Satelec S12/90 degrees D diamond-coated or S12/90 degrees non-coated stainless steel retrotips. Impressions were taken before and after retrograde cavity preparation. The resected root apices and their respective impressions were examined using a scanning electron microscope, and the presence, extension and numbers of cracks were recorded after each procedure. The number of cracks observed directly on the ultrasonically prepared root-end surfaces was larger than that observed in their respective impressions taken after root-end cavity preparation, which suggests that cracking was mostly produced by the sputter-coating process required for SEM analysis. Impressions of the root-end cavities prepared with non-coated ultrasonic stainless steel retrotips showed a greater incidence of cracks (3/10 impressions) than those that replicated cavities prepared with diamond-coated retrotips (1/10 impressions). No statistical difference was found between the diamond and stainless steel retrotips.

CAMPANELLIProgrammed Death 1 (PD-1) and PD-1 Ligand (PD-L1) Expression in Chronic Apical Periodontitis.

OBJECTIVE: This study aimed to examine programmed death protein 1 (PD-1) and programmed death lig-and 1 (PD-L1) expression on leukocytes from chronic apical periodontitis, and to determine the levels of cytokines in the apical periodontitis lesions. METHODS: Leukocytes from healthy gingival tissue (n=16) and chronic apical periodontitis (n=10) were eval-uated using flow cytometry. The PD-1 and PDL-1 expressions were evaluated using flow cytometry. The cy-tokine levels were evaluated by enzyme-linked immunosorbent assay. Data were analyzed using one-way ANOVA. The statistical significance level was set at P<0.05. RESULTS: Results showed that the apical periodontitis lesions are more infiltrated by PD-1+ and PDL1+ lym-phocytes than the control samples. In addition, the PDL-1 expression was detected on macrophages in the apical periodontitis lesions, and was significantly higher compared to leukocytes from healthy gingival tis-sue. The IFN-γ, TGF-ß, IL-10, and TNF-α levels were significantly higher in the apical periodontitis lesions com-pared to control samples. CONCLUSION: The PD-1, PD-L1, and CTLA-4 molecules are evident in apical periodontitis, and can be an impor-tant immune checkpoint in chronic periapical periodontitis.

Mineral Trioxide Aggregate with or without Calcium Chloride in Pulpotomy.

The aim of this study was to evaluate the reaction of the pulp tissue against mineral trioxide aggregate (MTA) with or without 10% calcium chloride (CaCl(2)). Pulpotomies were performed in 4 canines and 8 premolars of two 8-month-old dogs. MTA with or without CaCl(2) was applied on the pulp tissue. The animals were killed after 90 days, and the specimens were processed for the microscopic analysis. Pulp tissue response was similar for MTA with and without CaCl(2). Pulp vitality was present in all specimens, along with pulp repair with formation of mineralized tissue bridging. The addition of CaCl(2) to MTA did not change its biologic properties in formation of mineralized barrier after pulpotomy.

Alveolar mucosa necrosis induced by utilisation of calcium hydroxide as root canal dressing.

This case demonstrates the ability of calcium hydroxide to cause connective tissue necrosis. A patient with a history of trauma exhibited a large area of external inflammatory root resorption affecting the cervical and middle thirds of tooth 12. After root canal cleaning, a calcium hydroxide root canal dressing was applied to control the resorption process. After three days when the patient attended for replacement of the dressing an irregular zone of necrosis was observed on the buccal aspect of the alveolar mucosa. Careful curettage and irrigation was then performed to remove the extruded calcium hydroxide and necrotic tissue. After curettage, the root canal was accessed and irrigated with saline solution for removal of remnants of the dressing. The dressing was than replaced taking care to avoid contact with soft tissue, which might induce further damage, minimising the overflow of material. Improvement in healing was observed at 15-day follow-up, with complete closure of the lesion by soft tissue. At the 120-day follow-up, no scar was detected. At 180-day follow-up, the root canal was filled only with mineral trioxide aggregate (MTA) with aid of K files #20 and #50. At two-year follow-up, there were no symptoms and the resorption process seemed to have ceased. It is important to emphasise the damage that may occur when calcium hydroxide is in close and extended contact with the soft tissues, which could happen when dressing material is extruded through a root resorption.

Endodontic treatment of dens in dente associated with a chronic periapical lesion using an apical plug of mineral trioxide aggregate.

Dens in dente is a developmental anomaly that predisposes the tooth to develop caries and pulp periapical pathologies. A chronic lesion can develop without any clinical symptoms of the pathology. The purpose of this case report is to describe the endodontic treatment of dens in dente associated with a periapical lesion using a mineral trioxide aggregate apical plug.

Sealing ability of MTA and radiopaque Portland cement with or without calcium chloride for root-end filling.

The aim of this study was to evaluate the influence of calcium chloride (CaCl(2)) on the sealing ability of three Mineral Trioxide Aggregate (MTA) cements, ProRoot MTA, MTA-Angelus, and radiopaque White Portland cement (WPC), for retrograde root filling. Seventy roots of extracted single-rooted teeth were instrumented and obturated. After sectioning the samples at 2 mm from the apex, they received one layer of Araldite and two coats of nail enamel, except for the apical dentinal surface submitted to apicectomy. Standardized retrograde cavities were prepared, filled with one of the materials, and immersed in 0.2% Rhodamine B solution for 72 hours. Dye leakage was analyzed on a light microscope with ocular micrometer. Kruskal-Wallis and Miller tests were used to compare groups arranged in increasing order of leakage, according to mean rank of scores: WPC+CaCl(2), MTA-Angelus+CaCl(2), ProRoot MTA+CaCl(2), MTA-Angelus, ProRoot MTA, and WPC. CaCl(2) improved the sealing ability of all three MTA cements.

Evaluation of the tissue response to MTA and MBPC: Microscopic analysis of implants in alveolar bone of rats.

The aim of this study was to evaluate and compare the quantitative and qualitative inflammatory responses and bone formation potential after implantation of polyethylene tubes filled with a new calcium hydroxide containing sealer (MBPc) and ProRoot mineral trioxide aggregate (MTA). There were 48 Wistar rats divided in three groups: Group I (control group) empty polyethylene tubes were implanted in the extraction site; group II and III, polyethylene tubes were implanted filled with ProRoot mineral trioxide aggregate (MTA) and MBPc, respectively. At 7, 15, and 30 days after tube implantation, the animals were killed, the hemi-maxillas were removed and prepared to light microscopic analyses. The scores obtained were submitted to Kruskal-Wallis statistical test (p < 0.05). Significant differences between the materials were not observed. The results showed that both materials had similar biological response.

Analysis of the reaction of subcutaneous tissues in rats and the antimicrobial activity of calcium hydroxide paste used in association with different substances.

The aim of this study was to evaluate the subcutaneous tissue response in rats and the antimicrobial activity of intracanal calcium hydroxide dressings mixed with different substances against E. faecalis. Fifty four rats were divided into three experimental groups according to the vehicle in the calcium hydroxide treatment: 0.4% chlorohexidine in propylene glycol (PG),Casearia sylvestris Sw in PG and calcium hydroxide+PG (control group). The pastes were placed into polyethylene tubes and implanted into the subcutaneous tissue. After 7, 14 and 30 days, the samples were processed and histologically evaluated (hematoxylin and eosin). The tissue surface in contact with the material was analyzed, and the quantitative analysis determined the volume density occupied by the inflammatory infiltrate (giant cells, polymorphonuclear cells and mononuclear cells), fibroblasts, collagen fibers and blood vessels. For the antimicrobial analysis, 20 dentin blocks infected with E. faecalis were treated with calcium hydroxide pastes in different vehicles; 0.4% chlorhexidine in PG, PG, extract from Casearia sylvestris Sw in PG and a positive control (infection and without medication) for 7 days. The efficiency of the pastes was evaluated by the live/dead technique and confocal microscopy. The results showed that 0.4% chlorhexidine induced a higher inflammatory response than the other groups. The Casearia sylvestris Sw extract showed satisfactory results in relation to the intensity of the inflammatory response. In the microbiological test, there were no statistical differences between the evaluated intracanal dressings and the percentage of bacterial viability was between 33 and 42%. The control group showed an 86% viability. Antimicrobial components such as chlorhexidine or Casearia sylvestris Sw did not improve the antimicrobial activity against E. faecalis in comparison to the calcium hydroxide+PG treatment. In addition, the incorporation of chlorhexidine in the calcium hydroxide paste promoted the highest inflammatory response.

Rat subcutaneous tissue response to calcium silicate containing different arsenic concentrations.

OBJECTIVE: To evaluate the response of rat subcutaneous tissue in implanted polyethylene tubes that were filled with GMTA Angelus and Portland cements containing different arsenic concentrations. MATERIAL AND METHODS: Atomic absorption spectrophotometry was utilized to obtain the values of the arsenic concentration in the materials. Thirty-six rats were divided into 3 groups of 12 animals for each experimental period. Each animal received two implants of polyethylene tubes filled with different test cements and the lateral of the tubes was used as a control group. After 15, 30 and 60 days of implantation, the animals were killed and the specimens were prepared for descriptive and morphometric analysis considering: inflammatory cells, collagen fibers, fibroblasts, blood vessels and other components. The results were analyzed utilizing the Kuskal-Wallis test and the Dunn's Multiple test for comparison (p<0.05). RESULTS: The materials showed, according to atomic absorption spectrophotometry, the following doses of arsenic: GMTA Angelus: 5.01 mg/kg, WPC Irajazinho: 0.69 mg/kg, GPC Minetti: 18.46 mg/kg and GPC Votoran: 10.76 mg/kg. In a 60-day periods, all specimens displayed a neoformation of connective tissue with a structure of fibrocellular aspect (capsule). Control groups and MTA Angelus produced the lower amount of inflammatory reaction and GPC Minetti, the highest reaction. CONCLUSIONS: There was no direct relationship between the concentration of arsenic present in the composition of the materials and the intensity of the inflammatory reactions. Higher values, as 18.46 mg/kg of arsenic in the cement, produce characteristics of severe inflammation reaction at the 60-day period. The best results were found in MTA angelus.

Histologic evaluation of pulpotomies in dog using two types of mineral trioxide aggregate and regular and white Portland cements as wound dressings.

OBJECTIVE: The purpose of this study was to investigate the pulpal response of dogs' teeth after pulpotomy and direct pulp protection with MTA Angelus, ProRoot, Portland cement and white Portland cement. STUDY DESIGN: Seventy-six teeth were treated with these materials. One hundred twenty days after treatment, the animals were sacrificed and the specimens removed and prepared for histological analysis. RESULTS: All the materials demonstrated similar results when used as pulp-capping materials. Pulp vitality was maintained in all specimens and the pulp had healed with a hard tissue bridge. CONCLUSION: The materials used in this study were equally effective as pulp protection materials following pulpotomy.

Influence of bismuth oxide concentration on the pH level and biocompatibility of white Portland cement.

OBJECTIVES: To investigate if there is a relation between the increase of bismuth oxide and the decrease of pH levels and an intensification of toxicity in the Portland cement. MATERIAL AND METHODS: White Portland cement (WPC) was mixed with 0, 15, 20, 30 and 50% bismuth oxide, in weight. For the pH level test, polyethylene tubes were filled with the cements and immersed in Milli-Q water for 15, 30 and 60 days. After each period, the increase of the pH level was assessed. For the biocompatibility, two polyethylene tubes filled with the cements were implanted in ninety albino rats (n=6). The analysis of the intensity of the inflammatory infiltrate was performed after 15, 30 and 60 days. The statistical analysis was performed using the Kruskal-Wallis, Dunn and Friedman tests for the pH level and the Kruskal-Wallis and Dunn tests for the biological analysis (p<0.05). RESULTS: The results showed an increase of the pH level after 15 days, followed by a slight increase after 30 days and a decrease after 60 days. There were no significant statistical differences among the groups (p>0.05). For the inflammatory infiltrates, no significant statistical differences were found among the groups in each period (p>0.05). The 15% WPC showed a significant decrease of the inflammatory infiltrate from 15 to 30 and 60 days (p<0.05). CONCLUSIONS: The addition of bismuth oxide into Portland cement did not affect the pH level and the biological response. The concentration of 15% of bismuth oxide resulted in significant reduction in inflammatory response in comparison with the other concentrations evaluated.

Antimicrobial activity of triantibiotic paste, 2% chlorhexidine gel, and calcium hydroxide on an intraoral-infected dentin biofilm model.

INTRODUCTION: The purpose of this study was to evaluate the antimicrobial activity of calcium hydroxide, 2% chlorhexidine gel, and triantibiotic paste (ie, metronidazole, minocycline, and ciprofloxacin) by using an intraorally infected dentin biofilm model. METHODS: Forty bovine dentin specimens were infected intraorally using a removable orthodontic device in order to induce the biofilm colonization of the dentin. Then, the samples were treated with the medications for 7 days. Saline solution was used as the control. Two evaluations were performed: immediately after the elimination of the medication and after incubation in brain-heart infusion medium for 24 hours. The Live/Dead technique (Invitrogen, Eugene, OR) and a confocal microscope were used to obtain the percentage of live cells. Nonparametric statistical tests were performed to show differences in the percentage of live cells among the groups (P < .05). RESULTS: Calcium hydroxide and 2% chlorhexidine gel did not show statistical differences in the immediate evaluation. However, after application of the brain-heart infusion medium for 24 hours, 2% gel chlorhexidine showed a statistically lesser percentage of live cells in comparison with calcium hydroxide. The triantibiotic paste significantly showed a lower percentage of live cells in comparison with the 2% chlorhexidine gel and calcium hydroxide groups in the immediate and secondary (after 24 hours) evaluations. CONCLUSIONS: The triantibiotic paste was most effective at killing the bacteria in the biofilms on the intraorally infected dentin model in comparison with 2% chlorhexidine gel and calcium hydroxide.

Biocompatibility and setting time of CPM-MTA and white Portland cement clinker with or without calcium sulfate.

OBJECTIVE: To evaluate the biocompatibility and the setting time of Portland cement clinker with or without 2% or 5% calcium sulfate and MTA-CPM. MATERIAL AND METHODS: Twenty-four mice (Rattus norvegicus) received subcutaneously polyethylene tubes filled with Portland cement clinker with or without 2% or 5% calcium sulfate and MTA. After 15, 30 and 60 days of implantation, the animals were killed and specimens were prepared for microscopic analysis. For evaluation of the setting time, each material was analyzed using Gilmore needles weighing 113.5 g and 456.5 g, according to the ASTM specification Number C266-08 guideline. Data were analyzed by ANOVA and Tukey's test for setting time and Kruskal-Wallis and Dunn test for biocompatibility at 5% significance level. RESULTS: Histologic observation showed no statistically significant difference of biocompatibility (p>0.05) among the materials in the subcutaneous tissues. For the setting time, clinker without calcium sulfate showed the shortest initial and final setting times (6.18 s/21.48 s), followed by clinker with 2% calcium sulfate (9.22 s/25.33 s), clinker with 5% calcium sulfate (10.06 s/42.46 s) and MTA (15.01 s/42.46 s). CONCLUSIONS: All the tested materials showed biocompatibility and the calcium sulfate absence shortened the initial and final setting times of the white Portland cement clinker.

Antimicrobial activity of calcium hydroxide and chlorhexidine on intratubular Candida albicans.

This study investigated the efficacy of calcium hydroxide and chlorhexidine gel for the elimination of intratubular Candida albicans (C. albicans). Human single-rooted teeth contaminated with C. albicans were treated with calcium hydroxide, 2% chlorhexidine gel, calcium hydroxide plus 2% chlorhexidine gel, or saline (0.9% sodium chloride) as a positive control. The samples obtained at depths of 0-100 and 100-200 µm from the root canal system were analyzed for C. albicans load by counting the number of colony forming units and for the percentage of viable C. albicans using fluorescence microscopy. First, the antimicrobial activity of calcium hydroxide and the 2% chlorhexidine gel was evaluated by counting the number of colony forming units. After 14 days of intracanal medication, there was a significant decrease in the number of C. albicans colony forming units at a depth of 0-100 µm with chlorhexidine treatment either with or without calcium hydroxide compared with the calcium hydroxide only treatment. However, there were no differences in the number of colony forming units at the 100-200 µm depth for any of the medications investigated. C. albicans viability was also evaluated by vital staining techniques and fluorescence microscopy analysis. Antifungal activity against C. albicans significantly increased at both depths in the chlorhexidine groups with and without calcium hydroxide compared with the groups treated with calcium hydroxide only. Treatments with only chlorhexidine or chlorhexidine in combination with calcium hydroxide were effective for elimination of C. albicans.

Influence of root canal sealer on the radiographic appearance of filling voids in maxillary single-rooted teeth.

OBJECTIVE: This study compared the influence of three epoxy resin-based sealers with distinct radiopacities on the observers' ability to detect root canal filling voids during radiographic analysis. MATERIAL AND METHODS: The root canals of 48 extracted maxillary canines were prepared and divided into three groups. Each group was laterally condensed with one sealer (AH Plus®, Acroseal® or a non-radiopaque sealer), and a longitudinal void was simulated in half of the specimens from each group (n=8). Buccolingual radiographs were obtained and randomly interpreted for voids by a radiologist and an endodontist in a blinded fashion. Teeth were cut and inspected under a microscope to confirm the position of void. Differences in sensitivity and specificity between groups and examiners were compared using the Fisher's Exact and McNemar tests, respectively (α=0.05). RESULTS: Significantly lower sensitivity levels (p<0.05) were observed in the coronal portion of fillings performed with both radiopaque sealers. Specificity values for Acroseal® were significantly higher (p<0.05) in the coronal and apical portions of fillings. CONCLUSIONS: The type of root canal sealer can affect the observers' ability to detect root canal filling voids during radiographic analysis of upper single-rooted teeth.

In vivo accuracy of conventional and digital radiographic methods in confirming root canal working length determination by Root ZX.

OBJECTIVES: To compare, in vivo, the accuracy of conventional and digital radiographic methods in determining root canal working length. MATERIAL AND METHODS: Twenty-five maxillary incisor or canine teeth from 22 patients were used in this study. Considering the preoperative radiographs as the baseline, a 25 K file was inserted into the root canal to the point where the Root ZX electronic apex locator indicated the APEX measurement in the screen. From this measurement, 1 mm was subtracted for positioning the file. The radiographic measurements were made using a digital sensor (Digora 1.51) or conventional type-E films, size 2, following the paralleling technique, to determine the distance of the file tip and the radiographic apex. RESULTS: The Student "t" test indicated mean distances of 1.11 mm to conventional and 1.20 mm for the digital method and indicated a significant statistical difference (p<0.05). CONCLUSIONS: The conventional radiographic method was found to be superior to the digital one in determining the working length of the root canal.

Low-concentrated nonvital bleaching effect on bond strength of composite resin restorations / Efeito de clareadores não-vitais pouco concentrados sobre a força de cisalhamento de restaurações de resina composta

Objective: To investigate if short-term dentin bleaching with low-concentrated substances affects the bond strength of immediate resin composite restorations. Material and Methods: The buccal surfaces of fifty molar crowns were ground for dentin exposure and randomly assigned into 5 groups (n=10), according to the following treatments: sodium perborate + water; sodium perborate + 6% hydrogen peroxide; 6% hydrogen peroxide; 35% hydrogen peroxide (positive control), or no bleaching agent (negative control). The specimens were immediately restored with resin composite. Seven days after treatments, the shear bond test was performed in a universal test machine at a crosshead speed of 0.5 mm/min. Data were analyzed using ANOVA and Tukey’s HSD test (α = 0.05). Results: The shear bond strength mean values for the negative control group were higher than all experimental and positive control groups (p < 0.000), whose differences were not statistically significant (p > 0.05). Conclusion: Short-term dentin bleaching with sodium perborate+water, 6% hydrogen peroxide, or sodium perborate mixed with 6% hydrogen peroxide reduced the shear bond strength of immediate resin composite restorations.

Objetivo: Investigar se o clareamento rápido da dentina com substâncias de baixa concentração afeta a resistência de união ao cisalhamento de restaurações imediatas de resina composta. Material e Métodos: As superfícies vestibulares de cinquenta molares foram desgastadas para exposição da dentina e então aleatoriamente alocadas em 5 grupos (n = 10), de acordo com as substâncias clareadoras: perborato de sódio + água; perborato de sódio + peróxido de hidrogênio a 6%; peróxido de hidrogênio a 6%; peróxido de hidrogênio a 35% (controle positivo); ou nenhum agente clareador (controle negativo). Os espécimes foram imediatamente restaurados com resina composta. Sete dias após os tratamentos, testes de resistência ao cisalhamento foram realizados em uma máquina de ensaios universal a uma velocidade de cruzeta de 0,5 mm/min. Os dados foram analisados com os testes ANOVA e Tukey HSD (α = 0,05). Resultados: Os valores de resistência ao cisalhamento do grupo controle negativo foram maiores do que os dos grupos experimentais e controle positivo (p < 0,001), cujas diferenças não foram estatisticamente significativa (p > 0,05). Conclusão: Clareamentos dentinários rápidos com perborato de sódio, peróxido de hidrogênio 6% ou perborato de sódio misturado com peróxido de hidrogênio 6% reduziram a força de resistência ao cisalhamento de restaurações imediatas de resina composta.