Systemic administration of propranolol reduces bone resorption and inflammation in apical periodontitis of chronically stressed rats.

AIM: To evaluate the effect of systemic administration of propranolol on the severity of apical periodontitis (AP) in chronically stressed rats. METHODOLOGY: Twenty-four 70-day-old male Wistar rats (Rattus norvegicus, albinus) were distributed into three groups (n = 8): rats with AP without stressful conditions (AP-Control), rats with AP and submitted to a chronic unpredictable stress (CUS) protocol (AP + S) and rats with AP and submitted to a CUS protocol treated with propranolol (AP + S + PRO). Stress procedures were applied daily until the end of the experiment. After 3 weeks of CUS, AP was induced in all groups by exposing the pulpal tissue of mandibular and maxillary first molars to the oral environment. Propranolol treatment was administered orally once a day for the entire period of the experiment. Rats were sacrificed at 42 days, and the blood was collected for stress biomarkers serum dosage by multiplex assay. Mandibles were removed and submitted to microtomography and histopathological analyses. Periapical tissue surrounding the upper first molar was homogenized and subjected to RT-PCR analysis to evaluate the mRNA expression of RANKL, TRAP and OPG. Parametric data were assessed using one-way ANOVA followed by Tukey's test while the nonparametric data were analysed by the Kruskal-Wallis followed by Dunn's test. Significance level was set at 5% (p < .05) for all assessed parameters. RESULTS: Micro-CT revealed statistically significant differences in bone resorption which was greater in the AP + S group (p < .05), but no differences were observed between the Control and AP + S + PRO groups (p > .05). The AP + S + PRO group had a lower intensity and extent of inflammatory infiltrate compared to the AP + S group with smaller areas of bone loss (p < 0.05). The gene expression of RANKL and TRAP was significantly higher in the stressed group AP + S compared to the control group (p < .05), and a significantly higher OPG expression was observed in AP + S + PRO compared to the AP + S group (p < .05). CONCLUSIONS: Oral administration of propranolol had a significant effect on the AP severity in stressed rats, suggesting an anti-inflammatory effect and a protective role on bone resorption of AP in stressed animals. Further research is necessary to fully comprehend the underlying mechanisms.

Clinical efficacy of endodontic protocols on reducing cultivable bacteria and endotoxin in infected root canal in patients submitted to head and neck radiotherapy: a randomised clinical trial.

OBJECTIVES: Assess the efficacy of biomechanical preparation using a reciprocating system followed by final irrigation protocols, then intracanal medication, on reducing endotoxins and cultivable bacteria of infected teeth in irradiated patients. MATERIALS AND METHODS: Twenty-two infected single-rooted canals in patients submitted to head and neck radiotherapy were prepared by reciprocating motion and 2.5% NaOCl. Patients were randomly divided into two groups of 11 patients before the final irrigation protocol: apical positive pressure (APP) or passive ultrasonic activation (PUA). Both groups were treated in two sessions, using Ca(OH)2 as intracanal medication for 14 days. Root canal content sampling was performed after canal access (S1), after biomechanical preparation plus the irrigation protocol (S2), and after intracanal medication (S3). Chromogenic limulus amoebocyte lysate assay measured endotoxin levels (EU/mL), and bacterial load was determined by culture techniques (CFU/mL). RESULTS: Treatment protocols reduced bacterial counts after S2 in both groups (p = 0.01). S3 differed from S1 (p = 0.01), but not from S2 (p = 0.4). Endotoxin levels were reduced in both groups after S2 (P = 0.03) and were lower in S3 than in S2, with significant differences in the APP group (p = 0.03). CONCLUSIONS: Biomechanical preparation using a reciprocating system and 2.5% NaOCl in irradiated teeth, followed by the irrigation protocol (APP or PUA), demonstrated efficacy in reducing endodontic contaminants. Ca(OH)2 as intracanal medication should be performed in irradiated patients with infected root canals. CLINICAL RELEVANCE: This clinical study demonstrated that endodontic treatment in irradiated patients is efficacious at reducing bacterial load and endotoxin levels.

Primary versus post-treatment apical periodontitis: microbial composition, lipopolysaccharides and lipoteichoic acid levels, signs and symptoms.

OBJECTIVES: To compare the microbial load and composition and to determine the lipopolysaccharides (LPS) and lipoteichoic acid (LTA) concentrations found in primary apical periodontitis (PAP) and post-treatment apical periodontitis (PTAP), correlating these findings with clinical/tomographic features. MATERIAL AND METHODS: Sixty patients with PAP (31) and PTAP (29) were submitted to clinical and tomographic assessment. Samples were collected from each root canal using paper points for microbiological assessment (culture technique and Checkerboard DNA-DNA hybridization) and determination of LPS and LTA levels (limulus amebocyte lysate and enzyme-linked immunosorbent assays, respectively). Data were correlated with clinical/tomographic findings and statistically analyzed using the Mann-Whitney and Pearson correlation tests (α = 5%). RESULTS: A higher number of cultivable bacteria and LPS were found in PAP (p < 0.05). The median number of species per root canal found in PAP and PTAP was 9 and 22, respectively (p < 0.05). LPS was positively correlated with a larger periapical lesion volume (p < .05). LTA levels were similar in both infections and had no correlation with signs and symptoms. In PAP, gram-positive bacteria were correlated with spontaneous pain (p < .05) and exudate (p < .05). Tenderness to percussion and pain on palpation were correlated to the presence of both gram-positive and negative bacteria. In PTAP, a positive correlation was observed between both gram-positive and gram-negative bacteria with exudate and periapical lesion volume (p < .05). CONCLUSIONS: PAP had higher contents of microbial load and LPS compared with PTAP. However, PTAP presented a more diverse microbiota compared with PAP. Higher content of LPS was positively correlated with larger periapical bone destruction, whereas signs and symptoms with specific microorganisms. CLINICAL RELEVANCE: It was verified that PAP and PTAP are polymicrobial infections with predominance of gram-negative bacteria and a more diverse bacterial population found in PTAP. A wide interaction of specific microbial species resulted in different clinical features in both infections.

Anti-inflammatory and anti-resorptive efficacy of adrenergic blockers on late replanted rat incisors.

BACKGROUND/AIM: In addition to their anti-inflammatory and anti-osteoclastogenesis properties, adrenergic blockers may also have promising anti-resorptive effects that can prevent root resorption when teeth are replanted because of avulsion. The aim of this study was to investigate the effects of phentolamine (Ph) and propranolol (Pr) in gels on the repair process of late replanted rat incisors. A further aim was to evaluate the biocompatibility of both drugs to human periodontal ligament fibroblasts (HPDLFs). MATERIALS AND METHODS: Forty-eight maxillary right incisors were extracted from male Wistar rats, stored in paper napkins for 60 minutes, and randomly allocated to one of eight groups (n = 6). The root canal, root surface, and alveolus were treated with 0.75 µg/mL Ph gel (Ph0.75), 10 µg/mL Ph gel (Ph10), 100 µg/mL Ph gel (Ph100), 2.5 µg/mL Pr gel (Pr2.5), 10 µg/mL Pr gel (Pr10), 100 µg/mL Pr gel (Pr100), or sodium carboxymethylcellulose gel (CMC) before replantation. In the control group (CH), only the root canal was treated with calcium hydroxide paste. Thirty days following surgery, the animals were euthanized, and the right hemimaxilla was removed to perform micro-CT and histomorphometric analysis to determine osteoclastic activity. Ethanolic solutions of Ph10 and Pr10 were selected based on the in vivo study, and the viability of HPDLFs stimulated with lipopolysaccharide was determined by MTT assays. RESULTS: The micro-CT and histomorphometric analysis revealed no significant differences among the treatments (P > .05). The presence of active osteoclasts was significantly decreased in the Ph10 and Pr10 groups (P < .05). Ph10 and Pr10 produced statistically similar cell survival rates compared to the control group (P > .05). CONCLUSIONS: Ph10 and Pr10 significantly decreased osteoclastogenesis in delayed replanted rat teeth and were not cytotoxic toward HPDLFs.

Can different etching protocols change the properties of a hybrid ceramic?

The aim of this study was to evaluate the effects of different concentrations of hydrofluoric acid (HF) and etching times on the flexural strength, roughness, wettability, and type of failure of a hybrid ceramic (VITA ENAMIC). Blocks of the ceramic material were made according to the norms of International Organization for Standardization standard 6872:2015 and randomly divided into 7 groups (n = 13): control (no treatment); surface etching with 5% HF for 30 (HF5-30), 60 (HF5-60), or 90 (HF5-90) seconds; and surface etching with 10% HF for 30 (HF10-30), 60 (HF10-60), or 90 (HF10-90) seconds. The adhesive surface of 10 specimens in each group was cemented with dual-curing resin cement. The specimens were submitted to biaxial flexural tests and fractographic analysis. Surface analyses were carried out using 3 noncemented specimens from each group. The surface roughness was evaluated through optical profilometry and the surface wettability through goniometry (contact angle). The values obtained were analyzed by a Dunnett test followed by 2-way analysis of variance and Tukey test (α = 5%). The flexural test results indicated a statistically significant reduction in the resistance of the ceramic when conditioned with 10% acid (P < 0.01). Etching with HF, at any concentration used for any applied time, significantly modified the ceramic roughness of the experimental groups (P < 0.01). The wettability was also significantly altered in the HF5-90 group and in all HF10 groups (P < 0.01). The higher the concentration of the acid, the lower the wettability of the ceramic (P < 0.01). Based on these results, a 5% HF concentration is best indicated for the surface treatment of VITA ENAMIC.

Effect of ethylenediaminetetraacetic acid and hyaluronic acid on the viability and cytokine expression of periodontal ligament fibroblasts.

BACKGROUND/AIMS: Dental root cell proliferation following tooth avulsion has not been well researched. Understanding the effects of dry time and dentin treatment influences on cell proliferation is essential to provide evidence-based guidelines for tooth replantation. The study evaluated the viability of periodontal ligament fibroblasts (PLF) in contact with roots, submitted to surface treatments with ethylenediaminetetraacetic acid (EDTA) and hyaluronic acid (HA) at different times, including to quantify inflammatory cytokines interleukin (IL)-6, IL-8, IL-1ß and TNF-α expressed by PLF. The adhesion of fibroblasts to treated root surfaces was also evaluated. MATERIAL AND METHODS: One hundred and eight cementum discs from bovine teeth were randomly divided into groups according to time periods of being dry (n = 12) as follows: (i) fresh discs that were not kept dry, (WD); (ii) dry for 1 hour (1 hd); and (iii) dry for 24 hours (24 hd). The discs were subdivided into 3 subgroups (n = 12) according to surface treatments: (iv) no treatment, (v) treatment with EDTA, (vi) treatment with HA. The discs were placed in 96-well plates, and PLF were seeded and kept in contact with the discs for 48 hours. Cell viability on the surface of the discs was assessed by XTT, and PLF adhesion was evaluated using scanning electron microscopy (SEM). Quantification of cytokines was performed using enzyme-linked immunosorbent assay (ELISA). Data were submitted to ANOVA and Tukey's test (α = .05). RESULTS: Surface treatment had a statistically significant effect on the cell viability in groups WD (P = .03), 1 hd (P = .01) and 24 hd (P = .048). PLF in contact with dried root surfaces expressed more cytokines without treatment with IL-6 decreasing the expression when treated with HA for 24 hours. SEM also showed adhesion of PLF to the surface of all discs at all time periods. CONCLUSION: EDTA + HA is an alternative treatment for cases of avulsed teeth as it promoted adhesion and increased viability of PLF.

Comparison of Different Irrigants in the Removal of Endotoxins and Cultivable Microorganisms from Infected Root Canals.

This study was conducted to compare the effectiveness of different irrigants used to remove endotoxins and cultivable microorganisms during endodontic therapy. Forty root canals were contaminated and divided into groups according to the irrigant: 2% NaOCl + surfactant, 2% CHX, 2.5% NaOCl, and pyrogen-free saline solution (control). Samples were collected after root canal contamination (S1), after instrumentation (S2), and 7 days after instrumentation (S3). Microorganisms and endotoxins were recovered from 100% of the contaminated root canals (S1). At S2, 2% NaOCl + surfactant, 2% CHX, and 2.5% NaOCl were able to completely eliminate cultivable microorganisms. At S3, both 2% CHX and 2.5% NaOCl were effective in preventing C. albicans and E. coli regrowth, but E. faecalis was still detected. No microorganism species was recovered from root canals instrumented with 2% NaOCl + surfactant. At S2, a higher percentage value of endotoxin reduction was found for 2% NaOCl + surfactant (99.3%) compared to 2% CHX (98.9%) and 2.5% NaOCl (97.18%) (p < 0.05). Moreover, at S3, 2% NaOCl + surfactant (100%) was the most effective irrigant against endotoxins. All irrigants tested were effective in reducing microorganisms and endotoxins from root canals. Moreover, 2% NaOCl + surfactant was the most effective irrigant against endotoxins and regrowth of microorganisms.

In vitro antimicrobial and anti-endotoxin action of Zingiber Officinale as auxiliary chemical and medicament combined to calcium hydroxide and chlorhexidine.

OBJECTIVE: This study was conducted in vitro to compare the effectiveness of Zingiber Officinale as an auxiliary chemical substance followed by placement of different intra-canal medication in removing endotoxins and cultivable micro-organisms from infected root canals. MATERIALS AND METHODS: Seventy-two root canals were contaminated with Enterococcus faecalis, Candida albicans and Escherichia coli for 28 days. After, the teeth were instrumented using Zingiber Officinale and divided into six groups according to the intra-canal medication: chlorhexidine gel; calcium hydroxide + chlorhexidine gel; glycolic ginger extract; calcium hydroxide + glycolic ginger extract; calcium hydroxide + saline solution and saline solution (control). Sample collections were performed after root canal contamination (Baseline; S1), after instrumentation (S2), 7 days after instrumentation (S3), after 14 days with intra-canal medication (S4) and 7 days after removal of intra-canal medication (S5). The results were analyzed by the Kruskal-Wallis and Dunn tests. RESULTS: It was observed that in S2 and S3 there was significant reduction of the micro-organisms and the quantity of endotoxins after instrumentation. In samples S4 and S5 there was complete elimination of micro-organisms and significant reduction of endotoxins. CONCLUSION: It was concluded that Zingiber Officinale as an auxiliary chemical substance was effective on the micro-organisms tested, yet was unable to eliminate the endotoxins. Similarly, the intra-canal medication were effective on micro-organisms, yet did not completely eliminate the endotoxins.

Fracture resistance of weakened bovine teeth after long-term use of calcium hydroxide.

BACKGROUND/AIM: In some parts of the world, revascularization may not be the most feasible treatment option for necrotic immature teeth. Therefore, apexification remains the most widely utilized treatment option for these cases. This study aimed to evaluate the fracture resistance of weakened bovine tooth roots treated with various irrigant solutions as well as long-term application of calcium hydroxide intracanal medication (ICM). MATERIAL AND METHODS: One hundred seventy bovine teeth were randomly divided into three experimental groups (n = 50) and two control groups (n = 10). Group SS was irrigated with physiologic solution; group CHX was treated with 2% chlorhexidine gel and group NaOCl was irrigated with 1% sodium hypochlorite. After instrumentation, root canals were dressed with calcium hydroxide and evaluated at different periods (15, 60, 90, 180, and 360 days). The specimens were loaded at a 45° angle to measure fracture resistance through the use of an EMIC test machine. RESULTS: A decrease in fracture resistance was observed during the time of ICM dressing. The highest values of fracture resistance were observed in group SS with 15 days of ICM, not differing from the control group. Irrigation with NaOCl associated with ICM for 15 days presented the lowest fracture resistance; however, a statistically significant difference was not observed when compared with SS and CHX in the same time period. In longer periods of exposure to ICM (180 and 360 days), root canals irrigated with NaOCl and CHX showed significantly lower fracture resistance than SS (P < 0.05). CONCLUSION: Apexification with periodic changes of calcium hydroxide medicament leads to weakness of the teeth independent of the irrigation solution used.

Clinical performance of topical sodium fluoride when supplementing carbamide peroxide at-home bleaching gel.

This clinical study evaluated the use of 0.11% topical sodium fluoride (SF) desensitizing agent to treat tooth sensitivity during a nightguard tooth whitening procedure. Thirty-two subjects bleached their teeth with 10% carbamide peroxide (CP) gel using an at-home bleaching technique with custom trays. During bleaching treatment, subjects were divided into 2 groups (n = 16). The subjects in Group 1 received a topical gel containing 0.11% SF; the subjects in Group 2 received a placebo gel (PG). Each subject was instructed to place the gel in his/her bleaching tray for 30 min every day following bleaching treatment. Results showed the use of SF did not affect the whitening efficacy of the 10% CP gel. Subjects who received the PG had significantly higher tooth sensitivity when compared with subjects who received SF (P < 0.00). The use of daily 0.11% SF after 10% CP bleaching gel reduced tooth sensitivity during the bleaching treatment.

Evaluation of the bond strengths of 3 endodontic cements via push-out test.

In this study, the push-out method was used to evaluate the bond strengths of 3 types of endodontic cements according to their composite base: methacrylate, epoxy resin, and an experimental copaiba oil resin. The study hypothesis was that the methacrylate-based and experimental cements would have bond strengths equal to or greater than that of the epoxy resin-based cement. Thirty bovine tooth roots, 18 mm long, were divided into 3 groups (n = 10) based on the chosen cement treatment. After treatment, the specimens were sectioned and submitted to a push-out test. Results showed that there was no statistically significant difference (P < 0.05) between the cements used or between the middle and apical thirds of the roots. It could be concluded that the tested cements had satisfactory and similar bond strengths to dentin.

The effect of sodium hypochlorite and ginger extract on microorganisms and endotoxins in endodontic treatment of infected root canals.

This in vitro study sought to evaluate the biomechanical preparation action on microorganisms and endotoxins by using sodium hypochlorite (NaOCl) and an intracanal medication containing Zingiber officinale, with or without calcium hydroxide. Single-rooted teeth were contaminated, and root canal instrumentation (using 2.5% NaOCl) was performed. Samples were divided into 4 groups, according to the intracanal medication employed. The root canal content was gathered 28 days after contamination (baseline), immediately after biomechanical preparation, 7 days after biomechanical preparation, 14 days after intracanal medication, and 7 days after intracanal medication was removed. The results (submitted to Kruskal-Wallis and Dunn tests) showed that the NaOCl eliminated 100% of root canal microorganisms and reduced 88.8% of endotoxins immediately after biomechanical preparation, and 83.2% at 7 days after biomechanical preparation.

Influence of fiber post cementation length on coronal microleakage values in vitro and finite element analysis.

AIM: This study aims to evaluate, the Influence of different fiber posts cementation lengths by finite element analysis (FEA) and coronal microleakage. MATERIALS AND METHODS: Fifty anterior bovine teeth were sectioned to obtain roots with 16 mm length. The coronal length of the post was 6 mm for all groups, while the radicular length were varied 6, 8, 10 or 12 mm. The fiber posts surfaces were cleaned with alcohol and silanized. Then the posts were cemented using a two steps total etch-and-rinse adhesive system + conventional resin cement. Forty teeth were submitted to mechanical cycling (45°; 2.000.000 cycles; 90N; 4Hz; 37°C) and ten teeth with radicular length of 12 mm was not submitted, ser ving as c ontrol. So, the experimental design was composed by different ratios of post coronal length/post radicular length and mechanical cycling (MC): Gr1- 1/1 + MC; Gr2- 3/4 + MC; Gr3- 3/5 + MC; Gr4- 1/2 + MC. All groups were immersed in a 1% toluidine blue solution. After 24 hours, the teeth were longitudinally sectioned and the microleakage scores was given by a blind operator. Data were submitted to Kruskal-Wallis test (p = 0.05). The experimental variables were simulated in two-dimensional finite element analysis (2D-FEA). The maximum principal stress distributions were compared. RESULTS: No difference was observed in microleakage values between the cycled groups, whilst the control groups showed the lowest values. FEA analysis showed similar maximum principal stress distribution between the groups. CONCLUSION: Mechanical cycling affected the values of coronal microleakage and different cementation length generated similar values of coronal microleakage and stress distribution. CLINICAL SIGNIFICANCE: These results showed that from the microleakage point of view, more conservative cementation lengths have the same effect as longer cementation lengths.

Effectiveness of castor oil extract on Escherichia coli and its endotoxins in root canals.

This in vitro study sought to evaluate the effectiveness of castor oil extract used as an irrigating solution on Escherichia coli and its endotoxins in root canals. Sixty single-rooted teeth were prepared (using castor oil extract as irrigating solution) and divided into five groups (n = 12): Group 1 samples were treated with calcium hydroxide (Ca(OH)2), Group 2 samples were treated with polymyxin B, Group 3 samples were treated with Ca(OH)2 and 2% chlorhexidine gel (CHX), and Group 4 samples were treated with castor oil extract. A control group used physiological saline solution as an irrigant. Canal content samples were collected at four different times: immediately after instrumentation, seven days after instrumentation, after 14 days of intracanal medication, and seven days after removal of intracanal medication. A plating method was used to assess antimicrobial activity and the quantification of endotoxins was evaluated by the chromogenic Limulus lysate assay. Data were submitted to ANOVA and a Dunn test (a = 5%). Irrigation with castor oil extract decreased E. coli counts but had no effect on the level of endotoxins. Samples taken seven days after removal of medication revealed a significant reduction in endotoxin levels in Groups 3 and 4. Compared to the saline solution irrigation, castor oil extract decreased microorganism counts in root canals immediately after canal preparation. None of the medications used completely eliminated endotoxins in the root canal.

Volumetric Evaluation of Voids and Gaps of Different Calcium-Silicate Based Materials Used in Furcal Perforations: A Micro-CT Study.

This study aimed at evaluating volumetrically gaps and voids of calcium-silicate based materials of different generations and handling properties (BC­Endosequence BC RRM-Fast Set Condensable Putty, MTA­ProRoot MTA, and BIO­Biodentine) in simulated furcal perforations in an ex vivo setup by microcomputed tomography (Micro-CT) analysis. Thirty-six extracted human mandibular molars with sound furcation areas were selected. Standardized perforations were created in the furcation area of the pulp chamber using #4 diamond burs. The specimens were randomly assigned to three groups (BC, MTA and BIO; n = 12). Samples were then scanned (SkyScan 1172; Bruker-microCT, Kontich, Belgium), and three-dimensional (3D) images reconstructed. The relative volume of gaps (VG%) and voids (VV%) present on each material was calculated. Data were analyzed using one-way analysis of variance (ANOVA) and Tukey's HSD test (p < 0.05). Mean VG% for BC, MTA, and BIO groups were, respectively, 0.513%, 1.128%, 1.460%, with BC presenting statistically (p < 0.05) fewer gaps formation than the other groups. Mean VV% were, respectively, 0.018%, 0.037%, and 0.065%. The was no statistical difference regarding VV%. There were no gap-free and void-free samples. BC group had the lowest VG% among the groups with a significant statistical difference (p < 0.05).

Detoxification of LTA by intracanal medication: analysis by macrophages proinflammatory cytokines production.

The aim of this study was to evaluate in vitro the effect of calcium hydroxide [Ca(OH)2], 2% chlorhexidine gel (CHX) on macrophages (RAW 264.7) to produce pro-inflammatory cytokines and nitric oxide after pretreatment with lipoteichoic acid (LTA) of Enterococcus faecalis. Forty-eight human single-rooted teeth were instrumented with R25.08 (RECIPROC) and sterilized by gamma irradiation. LTA was inoculated in the root canal of each specimen for 96 hours. Specimens were instrumented with 40.06 and 50.05 (RECIPROC) and medicated with: I) Pyrogen-free saline solution (SS); II) 2% CHX gel; III) Ca(OH)2 + SS; or IV) Ca(OH)2 + CHX for 14 days. Three samples (S) were performed of the root canal of each specimen at: S1) immediately after instrumentation; S2) after Ethylenediaminetetraacetic acid (EDTA); S3) after intracanal medication removal. Subsequent quantification of cytokines (IL-1ß, TNF-α, MIP-1α, IP-10, G-CSF and IL-6) by immunosorbent assay (ELISA) and nitric oxide by the Griess method was carried-out. Data were submitted to a normality test and then analyzed with one-way ANOVA and Tukey test with a significance level of 5% using GraphPad Prism 6. Ca(OH)2 + SS and Ca(OH)2 + CHX presented lower levels of TNF-α, TNF-α, IL-6, G-CSF and nitric oxide. Ca(OH)2 + SS was the most effective in reducing MIP-1α. CHX was effective in reducing IL-6 and G-CSF. Therefore, the combined intracanal medication of calcium hydroxide and chlorhexidine is effective in reducing the cytokines TNF-α, IL-1ß, IL-6, G-CSF and nitric oxide.

Effectiveness of 1-Visit and 2-Visit Endodontic Retreatment of Teeth with Persistent/Secondary Endodontic Infection: A Randomized Clinical Trial with 18 Months of Follow-up.

INTRODUCTION: This randomized clinical trial aimed to compare the effectiveness of endodontic retreatment of teeth with posttreatment apical periodontitis (PTAP) performed in 1 visit versus 2 visits on the reduction of cultivable bacteria (colony-forming units [CFUs]), lipopolysaccharides (LPSs), lipoteichoic acid (LTA), and the periapical lesion volume (mm3) after 18 months of follow-up. METHODS: Forty patients diagnosed with PTAP were selected and randomly divided into the following 2 groups: 1-visit retreatment and 2-visit retreatment with the placement of calcium hydroxide medication for 14 days. Cone-beam computed tomographic scans were performed at 2 stages: preoperatively and after 18 months of follow-up. Samples were collected before and after root canal procedures. A chromogenic limulus amebocyte lysate assay test was used to quantify endotoxins (EU/mL). LTA levels were measured using the enzyme-linked immunosorbent assay (pg/mL). Culture techniques were used to determine cultivable bacteria by counting the CFU (CFU/mL). The volume of the periapical lesions at the onset of the trial and at the 18-month posttreatment follow-up was obtained by the ITK-SNAP program (Cognitica, Philadelphia, PA). RESULTS: All samples showed baseline values greater than those collected after the retreatment protocol for all investigated parameters. A higher bacterial load and lower LTA level were found in the 2-visit group after the retreatment protocol (P < .05), with no statistical differences between the groups regarding endotoxin levels and periapical lesion volume (mm³) at the 18-month follow-up analyzed by cone-beam computed tomographic imaging (P > .05). CONCLUSIONS: Endodontic retreatment in 1 or 2 visits exhibited equally favorable periapical healing at 18 months, with no statistically significant differences between groups.

Effect of carbamide peroxide bleaching gel concentration on the bond strength of dental substrates and resin composite.

PURPOSE: This study evaluated the effect of bleaching gel containing 10%, 15% and 20% carbamide peroxide (CP) on the bond strength of dental enamel or dentin and resin composite restorations. METHODS: The buccal surfaces of 12 bovine tooth crowns were conditioned with 37% phosphoric acid, and the adhesive resin Single Bond 2 and the resin composite Filtek Z350 were used to perform the restorations. The blocks were sectioned to obtain bar specimens. Each specimen group (enamel-E, dentin-D) was divided into four subgroups (n=15): S-artificial saliva; 10-10% CP bleaching; 15-15% CP bleaching; 20-20% CP bleaching. CP was applied for six hours daily for two weeks. The specimens were submitted to the sigma test in a universal testing machine. The data were analyzed by one-way ANOVA and the Tukey post-hoc test and a correlation analysis (r) was performed. RESULTS: For Group E, the mean value (+/- standard-deviation) was 21.86 (+/- 6.03)a, 18.91 (+/- 8.31)ab, 15.43 (+/- 7.44)b and 10.6 (+/- 4.94)c for ES, E10, E15 and E20, respectively. For Group D, the a values were 34.73 (+/- 4.68)a, 35.12 (+/- 13.43)a, 29.67 (+/- 6.84)ab and 24.56 (+/- 6.54)b for DS, D10, D15 and D20, respectively. A negative correlation between the CP concentration and mean values was observed for both the enamel (r=-0.95) and dentin (r=-0.85) groups. CONCLUSION: In the current study, the bond strength of the restoration to enamel and the restoration to dentin were influenced by the application of CP and was dependent on the CP concentration in the bleaching gel.

Peroxide penetration from the pulp chamber to the external root surface after internal bleaching.

PURPOSE: To quantify the amount of peroxide penetration from the pulp chamber to the external surface of teeth during the walking bleaching technique. METHODS: Seventy-two bovine lateral incisors were randomly divided over five experimental groups and one control (n = 12 per group): (1) 35% hydrogen peroxide (HP); (2) 35% carbamide peroxide (CP); (3) sodium perborate (SP); (4) (HP+SP); (5) (CP+SP) and (6) Control (CG), deionized water. All groups were treated according to the walking bleach technique. After 7 days at 37 degrees C in an acetate buffer solution, 100 microl violet leukocrystal coloring and 50 microl peroxidase was added, producing a blue stain that could be measured in a spectrophotometer and then converted into peroxide microg/ml. RESULTS: G5 exhibited the greatest penetration, while G2 and G3 produced the lowest values. All bleaching agents penetrated from the pulp chamber to the external root surface. There was a direct correlation between the presence of oxidative agents and penetration potential. Sodium perborate in distilled water was less oxidative and appeared to be the least aggressive bleaching agent.

Filling ability of three bioceramic root-end filling materials: A micro-computed tomography analysis.

This study aimed at evaluating the volume of gaps and voids, and the total porosity percentage of three calcium-silicate-based materials in mandibular molars apicoectomy by Micro-CT analysis. Thirty-three mesial roots of extracted human mandibular molars were instrumented and obturated. The apical 3mm of each root was resected and prepared. Root-end cavities were filled with EndoSequence BC Putty (BC); ProRoot MTA (MTA) and Biodentine (BIO). Samples were scanned using a Micro-CT scanner and the tridimensional images reconstructed. Percentage of gaps (VG%) and of voids (VV%) were obtained. Porosity percentage (Po%) was also assessed. Data were analysed using Student's t-test (P < 0.05). All materials presented gaps and voids. VG% was 2.006 (BC), 1.882 (MTA) and 1.450 (BIO), and VV% was 0.039 (BC), 0.021 (MTA) and 0.024 (BIO) with no statistical difference. Po% were 56.73 (BC), 51.94 (MTA) and 50.45 (BIO), with BC being statistically (P > 0.05) more porous.