Accuracy and efficiency of guided root-end resection using a dynamic navigation system: a human cadaver study.

AIM: To determine and compare the accuracy and efficiency of a dynamic navigation system (DNS) with a freehand (FH) technique when conducting root-end resection in a human cadaver model. METHODOLOGY: Forty roots in cadaver heads were included and divided into two groups: DNS (n = 20) and FH (n = 20). Cone beam computed tomography (CBCT) scans of all teeth were taken. The drilling path and depth were planned virtually to using the X-guide software (X-Nav Technologies, Lansdale, PA, USA). Osteotomy and root-end resection were done under navigation in the DNS group, and freehand under the dental operating microscope in the FH group. Post-operative CBCTs were taken. Linear deviations, angular deflection, time of operation and number of mishaps were compared with determine the accuracy and efficiency. Shapiro-Wilk, one-way ANOVA and Fisher exact tests were used (P < 0.05). RESULTS: Linear deviations, angular deflection and operation time were significantly less in the DNS group (P < 0.05). The number of mishaps was not different between the two groups (P > 0.05). Subgroup analyses revealed that the distance of >5 mm from buccal cortical plate was significantly associated with lower accuracy, increased operation time and greater incidence of mishaps in the FH group (P < 0.05), but not in the DNS group. CONCLUSIONS: The dynamic navigation system was more accurate and more efficient in root-end resection in a cadaver model than the freehand technique. The distance of the roots from the buccal cortical plate had a significant negative impact on the accuracy and efficacy of the root-end resection procedure when using the freehand technique. The dynamic navigation system has the potential to be a safe and reliable technological addition to endodontic microsurgery.

Clinical influence of calcium hydroxide and N-acetylcysteine on the levels of resolvins E1 and D2 in apical periodontitis.

AIM: To investigate the presence of resolvins E1 (RvE1) and D2 (RvD2) in teeth with primary endodontic infections and apical periodontitis, and to assess the influence of calcium hydroxide medication [Ca(OH)2 ], in association with 2% chlorhexidine gel (2% CHX gel), and N-acetylcysteine (NAC) on the levels of RvE1 and RvD2 in periapical tissues. METHODOLOGY: Thirty-six single-rooted teeth with primary endodontic infections and apical periodontitis were selected and randomly divided into three groups according to the medication: [Ca(OH)2 ] + saline solution (SSL) [Ca(OH)2  + SSL group] (n = 12), Ca(OH)2  + 2% chlorhexidine gel [Ca(OH)2  + 2% CHX gel group] (n = 12) and NAC [NAC group] (n = 12). Samples were collected from the periapical interstitial fluid at two different sampling times: before (S1) and after 14 days of intracanal medications (S2). Resolvins were measured using the enzyme-linked immunosorbent assay. Data were analysed using paired t-test, Wilcoxon test and Kruskal-Wallis test, followed by Dunn's post hoc test; all statistical tests were performed at a significance level of 5%. RESULTS: RvE1 and RvD2 were detected in 100% of the samples (36/36) at S1 and S2. Ca(OH)2 medication did not increase the levels of RvE1 or RvD2 (both P > 0.05); however, NAC significantly increased the levels of RvE1 and RvD2 after 14 days of treatment (P < 0.05). CONCLUSIONS: RvE1 and RvD2 were detected in periapical tissues from teeth with root canal infections. Moreover, calcium hydroxide medication did not increase the levels of resolvins in apical periodontitis. In contrast, the use of NAC intracanal medication significantly increased the levels of RvE1 and RvD2 after 14 days of treatment.

Comparison of cytotoxicity, genotoxicity and immunological inflammatory biomarker activity of several endodontic sealers against immortalized human pulp cells.

AIM: To establish an SV40 T-Ag-transfected cell line of human pulp-derived cells in order to compare the cytotoxicity, genotoxicity and to investigate the activities of immunological biomarkers of several endodontic sealers. METHODOLOGY: Primary human pulp cells and transfected cells were cultured. Cell morphology and proliferation were analysed, and the expression of cell-specific gene transcripts and proteins was detected by RT-PCR and immunohistochemistry. Transfection of human pulp-derived cells resulted in an immortalized cell line retaining phenotypic characteristics from the primarily cells tested. The SV40 T-Ag-transfected cells were cultured and stimulated by sealers (Apexit Plus, Real Seal, AH Plus, and EndoREZ) to evaluate the cytotoxicity and genotoxicity by MTT and MTN assays, respectively. Immunological inflammatory biomarkers (IL6, IL8 and TNF-α) were determined by ELISA assay. The differences between median values were statistically analysed using Kruskal-Wallis and Dunn's tests at 5% significance level. RESULTS: The cytotoxicity assay revealed that multimethacrylate (Real Seal) was the most cytotoxic sealer (P < 0.05) and exhibited the highest inflammatory potential against the SV40 T-Ag-transfected cells (P < 0.05). All root canal sealers tested were able to stimulate the immortalized pulp cells to produce IL-6, IL-8 and TNF-α, with differences in relation to the control group (P < 0.05). Higher levels of IL-6, IL-8 and TNF-α were found in cell supernatant after stimulation with multimethacrylate (Real Seal) compared to all other sealers tested (P < 0.05). No differences were found comparing epoxy resin-based sealer (AHPlus), single-methacrylate sealer (EndoREZ) and calcium hydroxide-based sealer (Apexit Plus), regardless of the cytokine investigated (all P > 0.05). CONCLUSIONS: A SV40 T-Ag-transfected cell line of human pulp-derived cells was established. The methacrylate resin-based sealer (Real Seal) exhibited the greatest cytoxicity and inflammatory potential against immortalized pulp cells compared to an epoxy resin-based sealer (AH Plus), a methacrylate-based sealer (EndoRez) and a calcium hydroxide-based sealer (Apexit).

Clinical efficacy of EDTA ultrasonic activation in the reduction of endotoxins and cultivable bacteria.

AIM: This clinical study was conducted to investigate the influence of 17% ethylenediaminetetraacetic acid (EDTA) ultrasonic activation after chemomechanical preparation (CMP) on eliminating/reducing oral bacterial lipopolysaccharides (known as endotoxins) and cultivable bacteria in teeth with pulp necrosis and apical periodontitis. METHODOLOGY: Samples were taken from 24 root canals at several clinical periods: S1 - before CMP; S2 - after CMP; S3 - after EDTA: G1 - with ultrasonic activation (n = 12) and G2 - without ultrasonic activation (n = 12). Root canals were instrumented using Mtwo rotary files. Culture techniques were used to determine the number of colony-forming units (CFU). Limulus amebocyte lysate (LAL) was used to measure endotoxin levels. Friedman's and Wilcoxon signed-rank tests were used to compare the amount of bacteria and endotoxin levels in each period (P < 0.05). RESULTS: Endotoxins and cultivable bacteria were recovered in 100% of the initial samples (S1). CMP was effective in reducing endotoxins and bacterial load (all with P < 0.05). Higher values of endotoxin reduction were achieved with EDTA ultrasonic activation [G1, 0.02 EU mL-1 (range 0.01-0.75)] compared with the no activation group [G2, 1.13 EU mL-1 (range 0.01-8.34)] (P < 0.05). Regarding bacterial reduction, no statistically significant difference was found in S3, regardless of the group (G1, G2, P > 0.05). CONCLUSIONS: Chemomechanical preparation was effective in reducing bacteria and endotoxins, but could not completely eliminate them. The ultrasonic activation of EDTA was effective in further reducing endotoxin levels in the root canals of teeth with pulp necrosis and apical periodontitis.

Does the Reciproc file remove root canal bacteria and endotoxins as effectively as multifile rotary systems?

AIM: To evaluate the effectiveness of Reciproc for the removal of cultivable bacteria and endotoxins from root canals in comparison with multifile rotary systems. METHODOLOGY: The root canals of forty human single-rooted mandibular pre-molars were contaminated with an Escherichia coli suspension for 21 days and randomly assigned to four groups according to the instrumentation system: GI - Reciproc (VDW); GII - Mtwo (VDW); GIII - ProTaper Universal (Dentsply Maillefer); and GIV -FKG Race(™) (FKG Dentaire) (n = 10 per group). Bacterial and endotoxin samples were taken with a sterile/apyrogenic paper point before (s1) and after instrumentation (s2). Culture techniques determined the colony-forming units (CFU) and the Limulus Amebocyte Lysate assay was used for endotoxin quantification. Results were submitted to paired t-test and anova. RESULTS: At s1, bacteria and endotoxins were recovered in 100% of the root canals investigated (40/40). After instrumentation, all systems were associated with a highly significant reduction of the bacterial load and endotoxin levels, respectively: GI - Reciproc (99.34% and 91.69%); GII - Mtwo (99.86% and 83.11%); GIII - ProTaper (99.93% and 78.56%) and GIV - FKG Race(™) (99.99% and 82.52%) (P < 0.001). No statistical difference were found amongst the instrumentation systems regarding bacteria and endotoxin removal (P > 0.01). CONCLUSION: The reciprocating single file, Reciproc, was as effective as the multifile rotary systems for the removal of bacteria and endotoxins from root canals.

Quantification of cultivable bacteria and endotoxin in post-treatment apical periodontitis before and after chemo-mechanical preparation.

This clinical study was conducted to quantify cultivable bacteria and endotoxin in root canals with post-treatment apical periodontitis by correlating their levels with clinical features and to evaluate the effect of chemo-mechanical preparation (CMP) with 2 % chlorhexidine gel + 17 % EDTA on bacterial and endotoxin removal/elimination. Moreover, target strict Gram-negative anaerobic bacteria were investigated by polymerase chain reaction (PCR). Fifteen teeth with post-treatment apical periodontitis were sampled before (s1) and after (s2) CMP. Culture techniques determined the number of colony-forming units (CFU). PCR (16S rDNA) and limulus amebocyte lysate (LAL) assay were used for bacterial and endotoxin detection, respectively. Prevotella nigrescens (4/15), Prevotella intermedia (2/15), and Tannerella forsythia (2/15) were the most frequently detected species. Endotoxin was recovered in 100 % of the samples. At s1, bacteria and endotoxin were detected at a median value of 5.14 × 10(3) CFU/mL and 3.96 EU/mL, respectively. Higher levels of endotoxin were related to a larger size of radiolucent area (>5 mm) (p < 0.05). CMP was more effective in reducing bacteria (99.61 %) than endotoxin (60.6 %) (both p < 0.05). Our findings indicated that the levels of endotoxin found in infected root canals were related to a larger size of radiolucent area in the periapical region. Moreover, CMP was effective in reducing both bacterial and endotoxin contents in post-treatment apical periodontitis.