Ultrasonic activation of adhesive systems increases bond strength and intratubular penetration of resin cement in root dentin subjected to radiation therapy.

OBJECTIVE: This study aimed to evaluate the effect of ultrasonic activation of etch-and-rinse and self-etch adhesive systems on the bond strength of resin cement to irradiated root dentin. MATERIALS AND METHODS: Eighty human maxillary anterior teeth were distributed into 8 groups (n = 10), according to the type of adhesive system used (etch-and-rinse and self-etch), the ultrasonic activation of the adhesive systems, and the dentin condition (irradiated or non-irradiated - 70 Gy). Endodontic treatment was performed followed by fiberglass post-space preparation. After fiberglass posts' luting, the roots were transversely sectioned on dentin discs and submitted to the push-out bond strength test (0.5 mm/min). The fractured specimens were analyzed under a stereomicroscope and Scanning Electron Microscope (SEM) for failure mode classification. One of the dentin discs was analyzed under SEM to evaluate the characteristics of the adhesive interface. RESULTS: Irradiated specimens had lower bond strength than non-irradiated specimens (P < 0.0001). Ultrasonic activation of both adhesive systems increased the bond strength of the resin cement to irradiated dentin (P < 0.0001). Radiotherapy significantly affected the failure mode in the middle (P = 0.024) and apical thirds (P = 0.032) (adhesive failure). CONCLUSION: Non-irradiated specimens had a more homogeneous adhesive interface. When ultrasonically activated, both adhesive systems showed a greater number of resinous tags, regardless of the dentin condition. CLINICAL RELEVANCE: Ultrasonic activation of adhesive systems is a feasible strategy to enhance fiberglass posts retention in oncological patients.

Assessment of multispecies biofilm growth on root canal dentin under different radiation therapy regimens.

OBJECTIVES: To assess the growth of a multispecies biofilm on root canal dentin under different radiotherapy regimens. MATERIALS AND METHODS: Sixty-three human root dentin cylinders were distributed into six groups. In three groups, no biofilm was formed (n = 3): NoRT) non-irradiated dentin; RT55) 55 Gy; and RT70) 70 Gy. In the other three groups (n = 18), a 21-day multispecies biofilm (Enterococcus faecalis, Streptococcus mutans, and Candida albicans) was formed in the canal: NoRT + Bio) non-irradiated + biofilm; RT55 + Bio) 55 Gy + biofilm; and RT70 + Bio) 70 Gy + biofilm. The biofilm was quantified (CFUs/mL). Biofilm microstructure was assessed under SEM. Microbial penetration into dentinal tubules was assessed under CLSM. For the biofilm biomass and dentin microhardness pre- and after biofilm growth assessments, 45 bovine dentin specimens were distributed into three groups (n = 15): NoRT) non-irradiated + biofilm; RT55 + Bio) 55 Gy + biofilm; and RT70 + Bio) 70 Gy + biofilm. RESULTS: Irradiated specimens (70 Gy) had higher quantity of microorganisms than non-irradiated (p = .010). There was gradual increase in biofilm biomass from non-irradiated to 55 Gy and 70 Gy (p < .001). Irradiated specimens had greater reduction in microhardness after biofilm growth. Irradiated dentin led to the growth of a more complex and irregular biofilm. There was microbial penetration into the dentinal tubules, regardless of the radiation regimen. CONCLUSION: Radiotherapy increased the number of microorganisms and biofilm biomass and reduced dentin microhardness. Microbial penetration into dentinal tubules was noticeable. CLINICAL RELEVANCE: Cumulative and potentially irreversible side effects of radiotherapy affect biofilm growth on root dentin. These changes could compromise the success of endodontic treatment in oncological patients undergoing head and neck radiotherapy.

Evaluation of changes in root canal length and accuracy of the electronic apex locator during different stages of endodontic treatment and retreatment.

This study evaluated changes in the root canal length (RCL) and the accuracy of the electronic apex locator (EAL) during the different stages of endodontic treatment and retreatment. Fifty-six mesial root canals of mandibular molars were selected. The actual root canal length (AL) of the canals was obtained by inserting a size 15 hand file up to the apical foramen, under magnification. The electronic lengths were obtained at the "APEX" mark of Root ZX II, using an alginate model. Both measurements were performed at three different stages of the initial root canal treatment-unflared, flared, and concluded-and at two stages of retreatment, after achieving patency and repreparation. Data were statistically analyzed and the significance level established was 5%. All stages produced a significant reduction in the AL (p < 0.05). The greatest variation was observed between the unflared-flared stages (0.2 mm) and between concluded-patency stages (0.09 mm), with no difference between them (p > 0.05). The accuracy of Root ZX II was negatively affected after achieving patency, presenting statistically significant difference compared to the other stages (p < 0.05). A significant reduction in the RCL was observed along the different stages of endodontic treatment and retreatment. The EAL was accurate to measure the root canals in most stages, except after achieving patency for endodontic retreatment. Determining and monitoring the RCL is an essential step towards a favorable prognosis, since it reduced along the different stages evaluated. Root ZX II was not accurate for endodontic retreatment.

Effectiveness of different supplementary protocols for remaining filling material removal in endodontic reintervention: an integrative review.

The aim of this study was to perform an integrative review to identify the most effective supplementary protocols used after filling material (FM) removal and root canal reinstrumentation, during endodontic reintervention. The literature search was performed on the electronic databases PubMed and Latin American and Caribbean Health Sciences Literature (LILACS), using a combination of specific scientific descriptors. Selection criteria accepted articles published in English, Spanish and Portuguese languages, up to August 2021, involving in vitro and ex vivo studies. After applying the eligibility criteria, 46 articles were included for qualitative analysis. The tool for qualitative analysis of quasi-experimental studies of the Joanna Briggs Institute was used to determine the risk of bias of the included articles. The selected articles provided important data regarding the following supplementary protocols: sonic and ultrasonic activation of the irrigating solution; the use of ultrasonic inserts, XP-endo system instruments, and photon-induced photoacoustic streaming for mechanical debridement; and new devices as GentleWave system, and the self-adjusting file. Overall, all supplementary protocols demonstrated efficacy in removing the remaining FM. The implementation of various supplementary protocols can effectively remove the remaining FM from the root canal walls, although complete removal is not always achieved. However, it was not possible to determine the most effective protocol. Conversely, their association can enhance remaining FM removal. Remaining FM attached to root canal walls hinders proper chemical-mechanical preparation during endodontic reintervention. Supplementary protocols optimize the remaining FM removal, enhancing cleaning and disinfection of root canal.

Do the apical limit and diameter of the instrumentation influence the extrusion of sodium hypochlorite solution? A micro-CT study.

This study evaluated the influence of the apical limit and the diameter of the instrumentation on the extrusion of the irrigating solution. Sixty human lower premolars were distributed into 5 groups according to the apical limit and diameter of the root canal instrumentation (n = 12): (G-140) R40 instrument 1 mm above the tooth length (TL) (Control); (G-150) R50 instrument 1 mm above the TL; (GF25) R25 instrument at the TL; (GF40) R40 instrument at the root canal length and (GF50) R50 instrument at the TL. A space of 33.5 ± 1 mm3 was created for storage of the extruded solution. Omnipaque contrast was added to the NaOCl solution in a 1:2 ratio, totaling 15 mL of solution to allow its visualization when extruded in microcomputed tomography. Final irrigation was performed with a syringe and needle and activated with a passive ultrasonic irrigation (PUI). Three activation cycles were performed. Data were tabulated and statistically analyzed (one-way ANOVA) with a significance level set at 5%. It was observed irrigating solution extrusion after final irrigation in all groups. However, there were no statistically significant differences among experimental groups, regardless of the diameter or apical limit of root canal instrumentation (p > 0.05). The different apical limits and diameters of root canal instrumentation did not influence the volume of extruded irrigating solution using passive ultrasonic irrigation.

Ultrasonic activation of the endodontic sealer enhances its intratubular penetration and bond strength to irradiated root dentin.

To evaluate the effect of ultrasonic activation of the endodontic sealer on its intratubular penetration and bond strength to irradiated root dentin. Forty human teeth were distributed into 4 groups (n = 10), according to the radiation therapy (RT) exposure-70 Gy-and ultrasonic activation (UA) of the endodontic sealer: RT/UA-irradiated teeth and sealer UA; RT/no-UA-irradiated teeth and no sealer UA; no-RT/UA-non-irradiated teeth and sealer UA and no-RT/no-UA-non-irradiated teeth and no sealer UA. Push-out bond strength test was performed in a Universal Testing Machine. Failure modes and adhesive interface were analyzed under Scanning Electron Microscopy. The data were statistically compared (two-way-ANOVA and posthoc Games-Howell test; Fisher's exact test - α = 5%). The different experimental conditions (radiation and UA) and the root third had a significant effect on push-out bond strength, and the interaction of these factors was significant (p < 0.05). UA of the sealer significantly increased its bond strength to both irradiated and non-irradiated dentin (p < 0.05). The irradiated groups mostly presented adhesive-type failure of the sealer (p < 0.01). Regardless of the irradiation, the ultrasonically activated groups showed a more homogeneous adhesive interface, with the presence of sealer tags in greater density and depth. Ultrasonic activation enhanced the intratubular penetration and the bond strength of the endodontic sealer to irradiated dentin. The impact of ultrasonic activation of the endodontic sealer on teeth undergoing radiotherapy is a gap in the scientific literature that needs to be bridged.

Effect of radiation therapy on fracture resistance of simulated immature teeth submitted to root reinforcement.

BACKGROUND: The literature is scanty regarding the effect of radiation therapy (RT) on the mechanical properties of immature permanent teeth. AIM: To evaluate the effect of RT on the fracture resistance of simulated immature teeth submitted to different types of root reinforcement. DESIGN: Sixty-four human teeth simulating the Cvek stage 3 of root development were distributed into eight groups (n = 8), according to exposure or not to RT (70 Gy) and the root reinforcement method: Group NR (control)-no reinforcement/no RT; Group NR + RT (control)-no reinforcement/RT; Group PO-tricalcium silicate-based cement (TS) apical plug/canal obturation/no RT; Group PO + RT-TS apical plug/canal obturation/RT; Group TS-canal filling with TS/no RT; Group TS + RT-canal filling with TS/RT; Group FP-TS apical plug/fibreglass post/no RT; and Group FP + RT-TS apical plug/fibreglass post/RT. Fracture resistance was determined using a universal testing machine (0.5 mm/min). RESULTS: In the intergroup comparison, nonirradiated teeth had higher fracture resistance (p < .05). Groups FP and FP + RT had higher fracture resistance (p < .001). CONCLUSION: Radiotherapy affected the fracture resistance of simulated immature teeth. Reinforcement with fibreglass posts increased the fracture resistance, regardless of the radiation.

Prevalence of postoperative pain after endodontic treatment using low and high concentrations of sodium hypochlorite: a systematic review and meta-analysis.

OBJECTIVES: To determine the prevalence of postoperative pain after endodontic treatment using low (LC) and high (HC) concentrations of sodium hypochlorite (NaOCl). MATERIALS AND METHODS: Six databases and the grey literature were searched to identify randomized clinical trials that evaluated postoperative pain after endodontic treatment using NaOCl. NaOCl concentrations were dichotomized into 'LC' (0.5% to 3%) and 'HC' (≥ 5%) and a proportion meta-analysis was applied to determine the postoperative pain prevalence: overall and according to pain intensity and postoperative time. The prevalence of patients using pain control medication was also determined. A significance level of 5% and a random effect model were applied for data analysis. Between-study heterogeneity was assessed by I2 index. Risk of bias (RoB) was assessed using the Cochrane Risk-of-Bias 2.0 tool. The certainty of evidence was assessed using the GRADE approach. RESULTS: Ten studies were included in the review and eight in the meta-analysis. The overall prevalence of postoperative pain was 45% in LC and 39% in HC. The prevalence of pain in LC and HC after 24 h was 25% and 40%, respectively. After 48 h, the prevalence decreased to 10% in LC and 25% in HC. 'Absent pain' was the most prevalent score. The prevalence of patients who used medication was 9% in LC and 15% in HC. Three studies were classified as 'high RoB', five as 'low RoB', and two as 'some concerns'. The certainty of evidence was very low. CONCLUSIONS: The overall prevalence of postoperative pain after endodontic treatment using LC and HC of NaOCl was 45% and 39%, respectively. CLINICAL RELEVANCE: Postoperative pain is common after endodontic treatment using NaOCl, but tends to decrease over time.

Development and validation of a method for creating incomplete vertical root fracture in extracted teeth.

The present study reported a method for inducing incomplete root fracture in human extracted teeth for the purpose of evaluating the merits of different diagnostic imaging techniques. Thirty-five single-rooted teeth were inspected under magnification and transillumination to exclude previously fractured teeth. Tooth crowns were removed, and the root canals were prepared up to the ProTaper Next X4 (40.06) file. Each root was lined with wax and embedded in a polystyrene resin block. The setup was attached to a universal testing machine for pressing a customized conical wedge (diameter at tip: 0.6 mm; taper: 0.2 mm/mm) into the instrumented canal with a 2 kN load at 5 mm/min. The machine was programmed to stop after a sudden 10% drop in loading force. Each specimen was removed from the resin block and inspected under × 20 magnification and transillumination to identify the fracture characteristics (pattern, surfaces and root-third affected). The gap width of each specimen was measured at different locations along the fracture line. The protocol induced incomplete vertical root fractures in all specimens. Fracture widths were < 100 µm in all specimens (mean gap width: 34.9 µm). The proposed methodology was successful in inducing incomplete vertical root fractures with characteristics that resemble the clinical presentation of these conditions. The method is easy to execute, highly reproducible and helps to minimize bias in laboratory studies that aims to mimic vertical root fractures.

Are electronic apex locators accurate in determining working length in primary teeth pulpectomies? A systematic review and meta-analysis of clinical studies.

BACKGROUND: The lack of a well-defined apical constriction in primary teeth raises concerns regarding the accuracy of electronic apex locators (EALs) for measuring working length. OBJECTIVES: To evaluate the accuracy of EALs in determining working length in primary teeth pulpectomies. METHODS: Two reviewers searched ten databases up to September 2021. Clinical studies evaluating the accuracy of the electronic measurement of working length in primary teeth pulpectomies were included. Studies without a comparison group, with samples smaller than ten root canals, and that did not use a multiple frequency EAL were excluded. A meta-analysis was conducted to assess the paired differences in mean lengths between measurements obtained by electronic and comparative methods. In addition, a meta-analysis of proportion was applied according to the level of difference between the measures. The risk of bias and applicability of the studies were assessed using the QUADAS-2 tool. The certainty of evidence was assessed with the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach. RESULTS: Twenty-nine studies were included in the qualitative analysis and twenty-three in the quantitative analysis. The methods of comparison for the electronic measurement were the radiographic method, radiovisiographic, scanning electron microscopy, and direct visualization. The meta-analysis showed that the electronic measurement tends to be shorter than radiographic measurement, while the other methods showed no difference. The proportion analysis showed a higher pooled proportion of difference values between electronic and comparative measurements within -0.5 to +0.5 mm (69.31%). The certainty of the evidence suggested very low confidence in estimating the outcome. DISCUSSION: The results of this review denote a good performance of the EALs in determining working length in primary teeth pulpectomies. However, these results are based on clinical studies with low methodological quality and high heterogeneity, which require careful interpretation for clinical practice. CONCLUSIONS: Although the results suggest acceptable accuracy of EALs in determining working length in primary teeth pulpectomies, the low quality of the included studies and the very low certainty of the evidence require clinicians to interpret these results with caution. More robust evidence is required to support that these devices are accurate for primary teeth. REGISTRATION: CRD42021277414 (PROSPERO).

Effect of root perforation repair with mineral aggregate-based cements on the retention of customized fiberglass posts.

The purpose of this study was to investigate whether the root perforation repair with mineral aggregate-based cements affects the retention of customized fiberglass posts to bovine intraradicular dentin. Sixty-four bovine mandibular incisors had their root canals endodontically treated and prepared for fiberglass posts luting. Teeth were randomly distributed into four groups (n = 16), according to the cement used for the perforations repair (MTA HP; calcium aluminate cement-CAC; and CAC + calcium carbonate nanoparticles-nano-CaCO3) and control group (no perforation). The groups were redistributed according to the fiberglass posts luting protocol (n = 8): total-etching (TE) (MTA HP/TE; CAC/TE; CAC + CaCO3/TE and control/TE) and self-etching (SE) (MTA HP/SE; CAC/SE; CAC + CaCO3/SE and control/SE). Roots were sectioned into 1.3 mm-thick dentin slices obtaining samples that were submitted to the push-out test in Universal Testing Machine (Instron, Model 4444-0.5 mm/min). The fractured samples were analyzed under stereomicroscope and Scanning Electron Microscope (SEM). CAC/TE and CAC/SE groups had significant difference between the cervical and middle thirds (p < 0.05). When the root thirds were not considered, CAC/SE had the lowest bond strength and differed statistically from CAC/TE and CAC + CaCO3/TE groups, which had the highest mean bond strength values (p < 0.05). The root perforations repair did not affect the bond strength of resin cement/customized fiberglass posts to bovine dentin. The increase in bond strength is luting protocol dependent.

Effectiveness of different anesthetic methods for mandibular posterior teeth with symptomatic irreversible pulpitis: a systematic review and meta-analysis.

OBJECTIVE: This systematic review aimed to assess the effectiveness of anesthetic methods for mandibular posterior teeth with symptomatic irreversible pulpitis, comparing to the inferior alveolar nerve block (IANB) by meta-analysis. MATERIALS AND METHODS: Studies were identified from Cochrane Library, Embase, Lilacs, PubMed, Scopus, and Web of Science databases up to May 2021. Randomized clinical trials comparing the anesthetic success rate of IANB and any other alternative anesthetic method were included. The quality of the selected studies was assessed by the Cochrane Risk of Bias 2.0 tool. Meta-analyses using Mantel-Haenszel method and random-effect models were performed to find the pooled estimates of risk ratio (RR) with 95% confidence interval (CI). The quality of evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluation approach. RESULTS: Twenty-two studies were selected, which included fourteen anesthetic methods. Two studies were classified as high risk of bias, five as uncertain risk and fifteen as low risk. Vazirani-Akinosi nerve block (VANB) [RR = 1.27; p = 0.007; 95% CI, 1.07-1.52; I2 = 0%] and intraosseous injection (IOI) [RR = 1.48; p = 0.04; 95% CI, 1.02-2.15; I2 = 46%] had superior effectiveness compared to IANB, with low certainty of evidence, as well as buccal infiltrations associated with IANB (BI + IANB) [RR = 1.84; p = 0.004; 95% CI, 1.22-2.79; I2 = 52%], with very low certainty. CONCLUSION: Evidence suggests that buccal infiltrations associated with IANB, VANB, and IOI are more effective than IANB at anesthetizing posterior mandibular teeth with symptomatic irreversible pulpitis. CLINICAL SIGNIFICANCE: Alternative primary methods of anesthesia might be indicated for mandibular posterior teeth presenting symptomatic irreversible pulpitis.

Tooth discoloration induced by the different phases of a calcium aluminate cement: One-year assessment.

OBJECTIVES: To assess the discoloration of teeth treated with the different phases of calcium aluminate cement (CAC), in comparison with the conventional CAC and mineral trioxide aggregate (MTA). MATERIALS AND METHODS: Fifty bovine incisors were prepared and filled. Two millimeters of the filling was removed to fabricate a cervical plug with the following cements (n=10): CA(CaO.Al2 O3 ); CA2 (CaO.2Al2 O3 ); C12 A7 (12CaO.7Al2 O3 ); CAC and MTA. The initial color measurement was performed and after 7, 15, 30, 45, 90, 180, and 365 days new color measurements were performed to determine the color (ΔE00 ), lightness (ΔL'), chroma (ΔC'), hue differences (ΔH'), and the whiteness index (WID ). RESULTS: ΔE00 was significant for groups (p = 0.036) and periods (p < 0.05). The greater ΔE00 was observed after 365 days for CAC (12.8). C12 A7 (7.2) had the smallest ΔE00 . ΔL' and ΔC' were significant for groups and periods (p < 0.05). ΔH' was significant for periods (p < 0.05). After 365 days, significant reduction in lightness was observed for all groups. For CA, CA2 , CAC, and MTA groups, the WID values decreased over time (p < 0.05). CONCLUSIONS: The tested cements changed the color behavior of the samples, resulting in greater teeth darkening over time. CLINICAL SIGNIFICANCE: There is no long-term study assessing the discoloration induced by the different phases of CAC.

Effect of different periods of calcium hydroxide dressing on the fracture resistance of root dentin.

The aim of this in vitro study was to evaluate the effect of different periods of intracanal calcium hydroxide (Ca[OH]2) dressing application on the compressive strength of root dentin. The roots of 80 human mandibular premolars were prepared via the crown-down technique and randomly distributed into 1 control group (Gc) and 4 experimental groups (n = 16). The experimental groups were based on the length of intracanal Ca(OH)2 dressing use: 7 (G7d), 14 (G14d), 30 (G30d), or 90 (G90d) days. The prepared roots in the control group were left unfilled. The root canals in the experimental groups were dried, filled with the Ca(OH)2 dressing, and radiographed, and then the root canal entrance was sealed. All of the specimens were stored in saline solution at 37°C for the duration of their experimental period. After storage, the roots were sectioned with 2 cuts. The first cut was 1 mm below the cementoenamel junction, and the second was 6 mm apical to the first cut, creating 6-mm-long × 3-mm-diameter cylinders. At each test period, 4 specimens from Gc and all 16 specimens from the appropriate experimental group were submitted to compressive strength testing (1 mm/min). The groups demonstrated the following mean (SD) values of compressive strength: Gc, 174.41 (56.10) MPa; G7d, 161.29 (39.10) MPa; G14d, 130.27 (57.53) MPa; G30d, 167.88 (34.24) MPa; and G90d, 129.62 (31.46) MPa. Statistically significant differences among the groups were found (P = 0.007; analysis of variance and Tukey test, α = 5%), with a significant difference between Gc and both G14d and G90d (P < 0.05). There were no statistically significant differences (P > 0.05) among the mean compressive strength values of the experimental groups (7, 14, 30, and 90 days). The results indicated that the use of Ca(OH)2 as an intracanal medication for periods of 14 and 90 days reduced the fracture resistance of root dentin.

Incidence of root resorption after concussion, subluxation, lateral luxation, intrusion, and extrusion: a systematic review.

OBJECTIVE: Traumatic dental injuries often affect the dental hard tissues, periodontal tissues, and dental pulp. Root resorption (RR) is a significantly concerning phenomenon that could lead to loss of the traumatized tooth. The purpose of this systematic review was to analyze the incidences of different types of RR after concussion, subluxation, lateral luxation, intrusive luxation, and extrusive luxation. MATERIAL AND METHODS: Seven databases were electronically and manually searched for the identification of observational studies that evaluated the incidence of RR after luxation injuries. Following study selection, data extraction, and risk of bias assessment through MAStARI checklist, the GRADE quality of available evidence was assessed. RESULTS: In total, 14 studies were included in the present systematic review. Ten and four studies presented a moderate and low RoB, respectively, and the overall GRADE quality of evidence was "very low" for all outcomes. The highest incidence rates of RR were observed for teeth with intrusive luxation, followed by those with extrusive luxation, lateral luxation, subluxation, and concussion. In general, the most common type of RR documented for all injuries was inflammatory RR, followed by replacement RR, surface RR, and internal RR. CONCLUSIONS: Our findings suggest that RR most commonly occurs in association with intrusive luxation and by inflammatory RR. Awareness regarding the incidence of RR after injuries is useful for clinicians to minimize the risk and severity of its occurrence, because a late diagnosis of RR may limit treatment alternatives and result in tooth loss. CLINICAL RELEVANCE: Knowledge about the incidence of RR in teeth with concussion and different types of luxation injuries can ensure appropriate follow-up protocols and favorable outcomes.

Comparison of two observational methods, scanning electron and confocal laser scanning microscopies, in the adhesive interface analysis of endodontic sealers to root dentine.

OBJECTIVES: To compare the accuracy of confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) during the analysis of the adhesive interface integrity and intratubular penetration of root canal sealers to radicular dentine. MATERIALS AND METHODS: Twenty roots of human maxillary incisors were prepared and distributed into two groups (n = 10), followed by filling with gutta-percha and Endofill (G1) or AH Plus (G2). After 7 days, roots were sectioned and analyzed under CLSM and SEM. Score systems were used to evaluate the adhesive interface integrity (0-4) and sealer intratubular penetration (0-3). Data were submitted to Wilcoxon-Mann-Whitney and Kendall correlation statistical tests (α = 5%). RESULTS: In the adhesive interface analysis, CLSM was similar (P = 0.157) to SEM for Endofill; however, the results were different for AH Plus (P = 0.029). Intratubular penetration had significant difference between observational methods for both sealers (P < 0.0001). Correlation analysis between SEM and CLSM for adhesive interface was moderate for Endofill and low for AH Plus. Intratubular penetration was low for both sealers. CONCLUSION: SEM and CLSM analysis had similar results when sealers were compared, with a more homogeneous adhesive interface, and greater intratubular penetration for AH Plus. Comparison between observational methods demonstrated low positive correlation for adhesive interface and intratubular penetration analysis. CLINICAL RELEVANCE: A proper interface formed between sealer and dentine is very important for final quality of root canal filling. Observational methods which allow an accurate analysis of this interface must be selected to assess such features.

Bacterial penetration into filled root canals exposed to different pressures and to the oral environment-in vivo analysis.

OBJECTIVES: The study aims to correlate the depth of bacterial penetration into filled root canals with the time of exposure to the oral environment and different pressures. MATERIALS AND METHODS: One-hundred and twenty-two root canals of male Beagle dog teeth were prepared and filled. The root canals were distributed into three groups, according to the pressure applied: (A) no pressure, (B) 30 kPa, and (C) 60 kPa. Then, the root canals were exposed to the oral environment, establishing sub-groups considering the time intervals of exposure: (1) 45 days and (2) 120 days (n = 17). Sub-groups had positive and negative controls (n = 5). The animals were sacrificed, and the specimens were prepared for histological analysis. RESULTS: There was no significant difference in the bacterial penetration among groups A, B, and C at 45 days (P = 0.903) and 120 days (P = 0.211). No statistically significant difference was found (P = 0.608) between the exposure time intervals. Most of the specimens from experimental groups exposed for 120 days presented moderate inflammatory infiltrate. CONCLUSIONS: Pressures of 30 and 60 kPa did not affect sealing ability of root canal filling. The time of exposure did not influence bacterial penetration, which was limited to the first 4 mm of the root canals exposed for 120 days. CLINICAL RELEVANCE: This animal study demonstrated that disinfection of the first millimeters of root canals could be considered before retreatment of their entire length. However, clinical studies in humans should be conducted before validation of this protocol.

Effect of temperature and seven storage media on human periodontal ligament fibroblast viability.

BACKGROUND/AIM: Natural resources, such as coconut water, propolis, and egg whites, have been examined as possible storage media for avulsed teeth. However, there is a lack of research focused on the efficacy of these three products together compared with Hank's balanced salt solution and milk. The aim of this study was to evaluate the capacity of seven storage media to maintain the viability of human periodontal ligament fibroblasts (PDLFs). MATERIAL AND METHODS: PDLFs were kept at 5°C and 20°C, in skimmed milk (SMilk), whole milk (WMilk), recently prepared Hank's balanced salt solution (HBSS), Save-A-Tooth® system's HBSS (Save), natural coconut water (Coconut), Propolis, and egg white (Egg) for 3, 6, 24, 48, 72, 96, and 120 h, through the analysis of tetrazolium salt-based colorimetric (MTT) assay. RESULTS: At 5°C, SMilk and WMilk were better than HBSS in maintaining cell viability, from 24 h onward. At 20°C, HBSS was the best storage medium at 96 and 120 h. At both temperatures, from 6 h onward, Coconut, Propolis and Egg were less effective than SMilk, WMilk, and HBSS. In general, the performance of Coconut, Propolis and Egg were not influenced by storage temperature. However, the lowest temperature undermined the effectiveness of HBSS from 24 h and favored SMilk and WMilk, from 96 and 48 h onward, respectively. Save and water were the worst storage media. CONCLUSION: SMilk was the best storage medium, followed by WMilk and HBSS. Coconut, Propolis, and Egg can be indicated for the conservation of PDLF up to 3 h. The lower temperature (5°C) undermined the effectiveness of HBSS and favored SMilk and WMilk.

Effect of passive ultrasonic irrigation on diffusion of hydroxyl ion through radicular dentine.

OBJECTIVE: This study investigated the effect of passive ultrasonic irrigation (PUI) on diffusion of hydroxyl ions through radicular dentine. MATERIALS AND METHODS: After chemomechanical preparation of root canals in 60 human teeth, the cementoenamel junction and the apical 3 mm of each root were covered with fast-setting adhesive. Four final irrigation protocols were applied (n = 10): group (G)1: irrigation with EDTA + NaOCl; G2: EDTA + PUI + NaOCl; G3: EDTA+(NaOCl + PUI); G4: (EDTA + PUI) + (NaOCl + PUI). Ten teeth irrigated with distilled water followed by PUI (G5) served as the negative control. After drying, the canals were filled with calcium hydroxide paste (CH), sealed and kept in individual vials containing 10 mL of distilled water with known pH values. At 7, 14, and 21 days, the pH of the water in the vials was measured. The pH values in various groups were analyzed with two-way ANOVA (irrigation protocol and time period as factors) and Holm-Sidak multiple comparison test (α = 0.05). RESULTS: Changes in pH was not significantly different among groups (P = 0.651) but was significant different among different time periods (P < 0.0001). For all groups, ion diffusion was higher at 14 and 21 days than at 7 days. CONCLUSIONS: PUI has no effect on diffusion of hydroxyl ions through radicular dentine. When CH is used as temporary filling material, a waiting period of at least 14 days is required to create an alkaline environment within the radicular dentine. CLINICAL RELEVANCE: The use of PUI during final irrigation phase does not improve the action of CH when it is used as temporary filling material.

Longer light-curing time decreases the effect of ageing on composite resin hardness used in root reinforcement.

This study evaluated the hardness of a composite resin used for root reinforcement, considering the light-curing time, root canal region and ageing due to long-term storage. Twenty incisor roots were reinforced using composite resin, varying the photopolymerisation time (40 or 120 s). Following fibre post cementation, the roots were transversely sectioned into coronal, middle and apical regions. Composite hardness was measured initially and after 18 months of water storage. Data underwent repeated measures analysis of variance and Tukey's post hoc tests. The factors 'light-curing time', 'root region' and 'ageing' affected the hardness. Significant interactions were observed between 'light-curing time × root region' and 'ageing × light-curing time'. Regardless of time, resin hardness in the apical region was lower. After ageing, hardness in the coronal and middle regions decreased when the light-curing time was 40 s, while no significant effect on hardness was noted with a light-curing time of 120 s.