Differentially Expressed Genes in Dental Pulp Tissues of Individuals With Symptomatic Irreversible Pulpitis With and Without History of COVID-19.

INTRODUCTION: Increased levels of proinflammatory markers have been reported in tissues of individuals with Coronavirus Disease 2019 (COVID-19). We hypothesize that inflamed dental pulp tissues of individuals with previous history of COVID-19 may present a differential inflammatory gene expression profile in comparison with individuals who never had COVID-19. MATERIALS AND METHODS: Dental pulp tissues were collected from 27 individuals referred for endodontic treatment due to symptomatic irreversible pulpitis. Of these, 16 individuals had a history of COVID-19 (6 months to 1 year post infection) and 11 individuals had no previous history of COVID-19 (controls). Total RNA from pulp tissue samples was extracted and subjected to RNA sequencing for comparison of differentially expressed genes (DEGs) among groups. DEGs showing log2(fold change) > 1 or < -1, and P < .05 were considered significantly dysregulated. RESULTS: RNA sequencing identified 1461 genes as differentially expressed among the groups. Of these, 311 were protein coding genes, 252 (81%) that were upregulated and 59 (19%) that were downregulated in the COVID group compared with controls. The top upregulated genes in the COVID group were HSFX1 (4.12-fold change) and LINGO3 (2.06-fold change); significantly downregulated genes were LYZ (-1.52-fold change), CCL15 and IL8 (-1.45-fold change). CONCLUSIONS: Differential gene expression in dental pulp tissues of COVID and non-COVID groups suggests potential contribution of COVID-19 on dysregulating inflammatory gene expression in the inflamed dental pulp.

Calcium Silicate-based Sealer Extrusion into the Mandibular Canal: 3 Different Recovery Outcomes-A Report of 3 Cases.

The use of calcium silicate-based sealers (CSSs) is increasing in dentistry as a result of their favorable properties. The inadvertent extrusion of these sealers into the mandibular canal (MC) can result in temporary or permanent neurosensory alterations. Three different recovery outcomes of CSS extrusion into the MC after endodontic treatment of mandibular molars confirmed by cone-beam computed tomographic imaging are described. In Case 1, CSS from the mesiolingual canal of tooth #31 was extruded into the MC during obturation. The patient reported paresthesia. The symptoms of paresthesia were completely resolved by 9 months. In Case 2, CSS from the mesial canals of tooth #30 was extruded into the MC during obturation. A "plasmalike spreading pattern" of the extruded sealer was observed on the radiographs. The patient reported paresthesia and dysesthesia. In addition, the patient complained of hyperalgesia with heat and mechanical allodynia. The symptoms continued to persist during follow-up. At 22 months, the patient still reported persistent paresthesia, hyperalgesia, and mechanical allodynia, affecting the ability to eat. In Case 3, CSS from the distal canal of tooth #31 was extruded into the MC during obturation. The patient did not report any paresthesia or dysesthesia. All 3 patients elected a follow-up approach and monitoring rather than surgical intervention. These cases illustrate the need for the development of guidelines for the management of iatrogenic CSS extrusion into the MC because such an occurrence may result in permanent, temporary, or no neurosensory alterations.

Treating Nerve Injury after Endodontic Microsurgery Using Laser Photobiomodulation: A Report of 2 Cases.

The purpose of this case report was to inform dentists and dental specialists about a noninvasive, viable treatment option that could aid in the recovery of patients who have experienced iatrogenic nerve injuries. Nerve injury is an inherent risk of many dental procedures and a complication that can negatively impact a patient's quality of life and activities of daily living. Managing neural injuries presents a challenge for clinicians because there are no standard protocols reported in the literature. Although spontaneous healing of these injuries can occur, the duration and degree of healing can vary greatly between individuals. Photobiomodulation (PBM) therapy is used as an adjunct in medicine for functional nerve recovery. Once target tissues are illuminated with a low-level laser during PBM, the light energy is absorbed by the mitochondria causing adenosine triphosphate production, modulation of reactive oxygen species, and the release of nitric oxide. These cellular changes explain why PBM has been shown to aid in cell repair, vasodilation, a reduction in inflammation, accelerated healing, and an improvement in postoperative pain. This case report presents 2 patients with neurosensory alterations after endodontic microsurgery with a significant improvement in their condition after PBM treatment using a 940-nm diode laser.

Physicochemical and Biological Properties of AH Plus Bioceramic.

INTRODUCTION: The purpose of this study was to evaluate the physicochemical and biological properties of AH Plus Bioceramic (AHPB; Dentsply Sirona, Charlotte, NC) in comparison to AH Plus (AHP, Dentsply Sirona) and EndoSequence BC Sealer (BC; Brasseler, Savannah, GA). METHODS: The setting time, radiopacity, flow, solubility, calcium ion release, and pH were evaluated following ISO guidelines. Surface characterization and chemical constitution were evaluated by scanning electron microscopy/energy-dispersive X-ray spectroscopy. The antibacterial effect was tested against Enterococcus faecalis. Sealer cytotoxicity was tested using the XTT cell viability assay. Analysis of variance, Tukey, and unpaired t tests were used with a significance level of 5%. RESULTS: The initial setting time of AHPB was shorter than AHP and BC (P ≤ .0001), whereas AHP showed a shorter final setting time (P ≤ .0001). AHPB was more radiopaque than BC (P = .0012) but less radiopaque than AHP (P = .0001). AHPB was more soluble than AHP (P ≤ .0001), whereas no difference was observed between AHPB and BC (P > .05). Immersion in phosphate-buffered saline decreased the solubility of AHPB and BC (P ≤ .005). AHPB calcium ion release was higher than AHP (P ≤ .05) but less than BC (P ≤ .0001). AHPB had the highest flow followed by AHP and BC (P > .05). All sealers were alkaline and able to eradicate E. faecalis. Surface morphology and chemical composition of all sealers changed after immersion in water and phosphate-buffered saline. Cell viability for AHPB and BC was higher than AHP (P ≤ .0001). CONCLUSIONS: AHPB presented adequate properties to be considered a good sealer, however, the high solubility may negatively impact the quality of the obturation.

Root Surface Changes in Endodontically Treated Teeth following Orthodontic Movement.

INTRODUCTION: Orthodontically induced external root resorption has been labeled an unavoidable consequence of orthodontic tooth movement (OTM). The objective of this study was to investigate the change in surface area (mm2) and volume (mm3) of endodontically treated teeth (ETT) compared with contralateral teeth with a vital pulp (VPT) after OTM. METHODS: Seventy-six teeth were included in this retrospective analysis: ETT (n = 38) and VPT (n = 38). All teeth were evaluated using cone-beam computed tomographic imaging at 2 time periods: before OTM (T1) and after OTM (T2). Study teeth were segmented to include all areas contained within the lamina dura and then were converted into a mesh model for data calculation. The surface area (mm2) and volume (mm3) of each tooth were calculated at T1 and T2 based on the number of cubic voxels present within the mesh model. Statistical analysis was performed using a linear mixed-effects model. RESULTS: The average change in surface area after OTM in ETT was 13.01 mm2 and 19.95 mm2 in VPT (P < .05). The average percent change in surface area after OTM in ETT was 2.09% and 3.38% in VPT (P < .05). The average change in volume after OTM in ETT was 22.48 mm3 and 32.44 mm3 in VPT (P < .05). The average percent change in volume after OTM in ETT was 2.62% and 4.10% in VPT (P < .05). CONCLUSIONS: The results from this study suggest that ETT are less susceptible to root resorption after OTM than their vital counterparts.

Dislodgement pushout resistance of five bioceramic root-end filling materials.

This study evaluated the dislodgement push-out resistance of five bioceramic materials. One hundred single-rooted teeth with one canal had the apical 3 mm and crown resected to create a 14 mm standardized length. The canals were instrumented to an apical size 80 with a 3 mm root-end preparation made with ultrasonic diamonds. The prepared roots were randomly divided into 5 root-end restorative groups (n=20). ProRoot MTA, Biodentine, EndoSequence Root Repair Material, EndoSequence Fast Set Putty, and EndoSequence BC Sealer with each material placed following manufacturer's instructions and stored at 100% humidity for 2 weeks. An apical-to-coronal static testing load with the identified dislodgement force converted into MPa with mean results analyzed with Kruskal-Wallis and Dunn's post hoc tests (α=0.05). ProRoot MTA and Biodentine displayed similar push-out stress resistance and exhibited significantly greater stress resistance than the similar Endosequence materials. However, all materials failed cohesively and were not dislodged from the root canal surface.

Retrievability of Calcium Silicate-based Root Canal Sealers During Retreatment: An Ex Vivo Study.

INTRODUCTION: The retrievability of calcium silicate-based sealers (CSSs) during nonsurgical retreatment has been equivocal. This study compared the retrievability of 3 different CSSs using 1 of 3 different solutions or no solution. METHODS: A total of 130 extracted teeth with a straight canal were decoronated to a standardized root length. The canals were instrumented to 35/.04 and divided into 3 groups (BC: EndoSequence BC sealer; EBC: EdgeBioceramic; NEO: NeoSEALERFlo), and each group was further divided into 4 subgroups (6% sodium hypochlorite; 5% acetic acid; carbonated water; no solution). After sealer placement, each master gutta-percha cone was placed intentionally 2 mm short of the working length (WL) to ensure the apical 2 mm was filled only with sealer. After storage for 21 days at 37°C and 100% humidity, retreatment was performed until apical patency was obtained. The operator was blinded to the CSS and solution used. Data were analyzed using analysis of variance to compare apical patency rates and the mock chair-times. RESULTS: Overall success rates for apical patency in BC, EBC, and NEO were 63.64%, 69.77%, and 100%, respectively. There was significantly higher apical patency rate in NEO than BC and EBC. The chair-time for NEO was significantly shorter than BC (P < .05) and EBC sealer (P < .001). There was no significant difference in the chair-time between BC and EBC sealer groups. CONCLUSION: BC, EBC, and NEO sealers in a straight canal were consistently retrievable when no solution was used. Compared with no solution, the retrievability of BC, EBC, and NEO decreased when solutions were used.

Evaluation of the Physicochemical and Biological Properties of EndoSequence BC Sealer HiFlow.

INTRODUCTION: Understanding the physicochemical and biological properties of endodontic sealers is important for endodontic treatment planning. This study evaluated the properties of EndoSequence BC Sealer HiFlow (BCH; Brasseler USA, Savannah, GA), EndoSequence BC Sealer (BC, Brasseler USA), and AH Plus (AHP; Dentsply DeTrey, Konstanz, Germany). The effect of temperature on the setting time and flow of these sealers was also evaluated. METHODS: The setting time, flow, radiopacity, pH, solubility, and calcium release were investigated following ISO guidelines. The morphology and chemical composition of the sealers were evaluated by scanning electron microscopy and energy-dispersive spectroscopy. The antibacterial activity of sealers was tested against 2 strains of Enterococcus faecalis. Sealer cytotoxicity and the effects on messenger RNA expression of proinflammatory and mineralization genes were also investigated. Data analysis was performed using analysis of variance, Tukey, Kruskal-Wallis, and Dunn multiple comparison tests. P ≤ .05 was considered statistically significant. RESULTS: The setting time and flow rate of all sealers were affected by heat (P ≤ .05). The setting times and solubility of BCH and BC were significantly higher than AHP (P ≤ .0001). The radiopacity of AHP was higher than BCH and BC (P ≤ .0001). All sealers were alkaline and had antibacterial effects. Cell viability was higher for BCH and BC than AHP (P ≤ .0001). No significant differences in messenger RNA expression of proinflammatory and mineralization genes were observed. CONCLUSIONS: Overall, BCH and BC had similar physicochemical and biological properties. The observed high solubility of BCH and BC as well as the high cytotoxicity of AHP might negatively impact the clinical performance of these materials. The application of heat affected the setting time and flow of all sealers.

The effect of endodontic access preparation on the failure load resistance of a 3Y-TZP monolithic zirconia crown.

The effect of endodontic access preparation on the failure load resistance of 3Y-TZP zirconia crowns was accomplished by preparing human molars and luting monolithic zirconia crowns with a self-adhesive resin cement. Besides the intact control, teeth received endodontic access preparations and then grouped (n = 12) into a positive control (no access repair), dentin core replacement only and complete access repair groups. Specimens were axially tested until failure with results of no significant difference between the failure load of intact controls and the complete access repair group. However, the positive control and dentin replacement only groups failed at significantly lower loads. Under the conditions of this study, there was no significant failure load difference between 3Y-TZP monolithic zirconia crowns with repaired endodontic access preparations to that evidenced by an unprepared control. Although this evidence is encouraging, caution is advised and definitive recommendations cannot be made until verified by clinical studies.

Vascular Endothelial Growth Factor and/or Nerve Growth Factor Treatment Induces Expression of Dentinogenic, Neuronal, and Healing Markers in Stem Cells of the Apical Papilla.

INTRODUCTION: The goal of regenerative endodontic procedures is to preserve and stimulate stem cells from the apical papilla (SCAPs) to develop the pulp-dentin complex using various growth factors and scaffolds. We hypothesized that the treatment of SCAPs with vascular endothelial growth factor (VEGF) or nerve growth factor (NGF) may impact the expression of osteogenic and dentinogenic markers. METHODS: The optimum concentration of VEGF and NGF on SCAP viability was assessed and introduced to SCAPs for 6-24 hours. SCAPs were also challenged with Escherichia coli lipopolysaccharide (LPS). Messenger RNA (mRNA) expression of DSPP, DMP1, TGFB1, OCN, SP7, and TWIST1 was examined via quantitative reverse transcription polymerase chain reaction. Immunohistochemistry was used to verify protein expression. In addition, total RNA from NGF-treated SCAPs in the presence or absence of LPS was extracted for RNA sequencing. RESULTS: Compared with untreated cells, NGF-treated SCAPs showed markedly higher levels of DSPP, DMP1, and TGFB1 mRNAs (>9-fold change, P < .05), and SCAPs treated with both VEGF and NGF showed a significant increase of DSPP and TGFB1 mRNAs (P < .05). In addition, in LPS-challenged SCAPs, treatment with these growth factors also exhibited increased expression of DSPP, DMP1, and TGFB1 mRNAs, with the most significant change induced by VEGF (P < .05). Immunohistochemistry confirmed increased dentin sialophosphoprotein, dentin matrix acidic phosphoprotein 1, and transforming growth factor beta 1 protein expression in treated SCAPs. RNA sequencing revealed multiple pathways regulated by NGF, including TGF-ß and neurogenic pathways. CONCLUSIONS: VEGF- and NGF-induced dentinogenic/neuronal/healing marker expression in SCAPs indicates the potential value of applying these growth factors in regenerative endodontic procedures.

Evaluating the substantivity of silver diamine fluoride in a dentin model.

OBJECTIVES: The goal of endodontic therapy is to prevent apical periodontitis. This is achieved by biomechanical preparation, microbial control using endodontic irrigants, and complete obturation of the canal space. In order to prevent possible post-obturation complications and for an added antimicrobial effect, substantivity is a desired characteristic of endodontic irrigants. Currently the most commonly used endodontic irrigant that produces an antibacterial substantivity effect is chlorohexidine (CHX). Silver diamine fluoride (SDF) is a topically applied agent for managing dental caries and has shown to stop caries lesion progression. The objective of this study was to compare the antimicrobial substantivity effect of 3.8% SDF against other commonly used endodontic irrigants such as 2% CHX and 6.25% Sodium hypochlorite (NaOCl). MATERIAL AND METHODS: Using a diffusion disc assay we determined the antimicrobial activities of 38%, 3.8%, 0.38%, and 0.038% of SDF against the bacterium Enterococcus faecalis OG1RF. Subsequently, we compared the levels of colonization of E. faecalis by scanning electron microscopy (SEM) at 1.5- and 3-week time intervals on dentin pretreated with 3.8% SDF, 6.25% NaOCl, 2% CHX or sterile phosphate buffered saline (PBS). RESULTS: The diffusion disc assay demonstrated that 38% and 3.8% of SDF inhibited the growth of E. faecalis. Moreover, the substantivity of 3.8% SDF (p < 0.01) was comparable to 2% CHX (p < 0.01) and it is significantly greater than 6.25% of NaOCl compared to the PBS treated samples after 1.5 and 3 weeks of incubation. CONCLUSIONS: In this study, we demonstrate that SDF possesses antimicrobial properties against the opportunistic pathogen E. faecalis. Moreover, using a dentin model we show the substantivity of 3.8% SDF is significantly greater than 6.25% NaOCl, but is comparable to 2% CHX.

Shear Bond Comparison between 4 Bioceramic Materials and Dual-cure Composite Resin.

INTRODUCTION: Bioceramic materials have shown biologic and physical properties favorable for regenerative treatment. A key to treatment success is an adequate restoration to prevent microleakage; however, research is limited regarding the bond strength between restorative and bioceramic materials used in regenerative procedures. This study compared the bond strength between 4 bioceramic materials and a dual-cure composite resin. METHODS: Eighty wells in Teflon (ePlastics, San Diego, CA) blocks were filled with bioceramic materials representing 4 groups: White ProRoot mineral trioxide aggregate (MTA) (Dentsply Tulsa Dental, Tulsa, OK), Biodentine (Septodont, Saint Maur des Fosses, France), EndoSequence Root Repair Material Fast Set Putty (Brasseler USA, Savannah, GA), and NeoMTA (Avalon Biomed Inc, Houston, TX). After allowing samples to set according to the manufacturers' instructions, exposed surfaces of the bioceramic materials were prepared using ClearFil SE Bond (Kuraray America, Inc., New York, NY) followed by restoration with ClearFil DC Core Plus (Kuraray America, Inc.). To test shear bond strength, each block was secured in a universal testing machine, and the crosshead was advanced at 0.5 mm/min until fracture. Newton peak force was recorded and megapascals calculated followed by data comparison. RESULTS: The mean shear bond strengths between ClearFil DC Core Plus and the bioceramic materials were as follows: White ProRoot MTA, 7.96 MPa; Biodentine, 9.18 MPa; EndoSequence Root Repair Material Fast Set Putty, 4.47 MPa; and NeoMTA, 5.72 MPa. White ProRoot MTA and Biodentine were statistically similar, with a higher stress bond strength than NeoMTA, which had a statistically greater bond strength than EndoSequence Root Repair Material. All these values were lower than typical bond strengths shown for dentin-composite resin bonding. CONCLUSIONS: The choice of which bioceramic material to use in regenerative procedures should be based on factors other than the bond between that material and the overlying coronal resin restoration.

The Effects of Irrigants on the Survival of Human Stem Cells of the Apical Papilla, Including Endocyn.

INTRODUCTION: Endocyn, a pH-neutral solution of hypochlorous acid and hypochlorite has been developed for use as an endodontic irrigant. The purpose of this study was to evaluate the effect of Endocyn on human periodontal ligament (PDL) fibroblasts, rat osteosarcoma cells (UMR-106), and stem cells of the apical papilla (SCAP) compared with other commonly used endodontic irrigants. METHODS: To determine cytotoxicity, cells were exposed to various concentrations of Endocyn, 6% sodium hypochlorite (NaOCl), 17% EDTA, and 2% chlorhexidine for 10 minutes, 1 hour, or 24 hours. Cell survival was measured fluorescently using calcein AM. Endocyn also was tested for its ability to inhibit SCAP proliferation and alkaline phosphatase activity. Finally, SCAP transcript expression was examined via reverse-transcriptase polymerase chain reaction. RESULTS: Endocyn was no more toxic to PDL and UMR cells than water for up to 24 hours. Endocyn concentrations of 50% were toxic to SCAP after 1 hour of exposure. Endocyn concentrations of >20% inhibited SCAP proliferation, whereas concentrations of ≥10% inhibited alkaline phosphatase activity. Exposure of SCAP to 10% Endocyn for 3 days did not alter most transcript expression, but did significantly reduce the expression of alkaline phosphatase, fibromodulin, and osteomodulin. CONCLUSION: Endocyn was significantly less cytotoxic to PDL, UMR-106, and SCAP cells compared with other commonly used endodontic irrigants. High concentrations of Endocyn did inhibit some transcript expression and alkaline phosphatase activity, indicating a potential reduction in the osteogenic potential of stems cells exposed to Endocyn.

A Comparison of Coronal Tooth Discoloration Elicited by Various Endodontic Reparative Materials.

INTRODUCTION: The purpose of this study was to evaluate coronal tooth discoloration of ProRoot MTA (Dentsply Tulsa Dental, Johnson City, TN), white ProRoot MTA, EndoSequence Root Repair Material (Brasseler USA, Savannah, GA), MTA Angelus (Angelus Solucoes Odontologicas, Londrina, Brazil), and Biodentine (Septodont, Saint Maur des Fosses, France) when used in an ex vivo pulpotomy model. METHODS: Freshly extracted mandibular third molars were collected and stored in 1% chloramine-T solution. Teeth were randomly assigned into 6 groups (n = 15) and stored individually in phosphate buffered saline at 37 °C in 100% humidity. A standardized endodontic access was made in 5 groups. A 3-mm-thick increment of reparative material was placed on the pulpal floor, covered by glass ionomer, and the access opening restored with composite. Color (Commission Internationale de l'eclairage L*a*b*) was recorded with the Vita Easy Shade spectrophotometer (VITA Zahnfabrik, Bad Säckingen, Germany) on the midbuccal surface at baseline; after access preparation; after material placement; and then after 1, 7, 30, and 60 days. Changes in Commission Internationale de l'eclairage L*a*b* were measured for each experimental group and compared with ProRoot MTA (positive control) and no treatment (negative control) using the following equation: ΔE = ([Li - L0*]2 + [ai - a0*]2 + [bi - b0*]2)(1/2). The mean results were analyzed within each group and between groups using the Friedman 2-way analysis post hoc test (P < .05). RESULTS: There were no significant differences between white ProRoot MTA, MTA Angelus, and the positive control group. EndoSequence Root Repair Material and Biodentine produced significantly less discoloration than white ProRoot MTA, MTA Angelus, and ProRoot MTA. CONCLUSIONS: Under the conditions of this study, EndoSequence and Biodentine had significantly less discoloration compared with white ProRoot MTA, MTA Angelus, and ProRoot MTA. The potential for discoloration may or may not correlate when materials are used clinically.

Evaluation of 4 Different Irrigating Systems for Apical Extrusion of Sodium Hypochlorite.

INTRODUCTION: The aim of this study was to evaluate NaOCl apical extrusion by using negative apical pressure (EndoVac), sonic agitation (EndoActivator), side-vented needle (Max-i-Probe), and photon induced photoacoustic streaming (PIPS 10 mJ and PIPS 20 mJ) laser irrigation in an in vitro gel model. METHODS: Extracted mandibular and maxillary central incisors (n = 18) were prepared to size 35/.04 and 55/.04, respectively. Teeth were mounted in transparent containers with clear acrylic and suspended in a color-changing pH-sensitive gel, creating a closed system. By using a crossover design, each tooth was sequentially irrigated by using 6% NaOCl with each device following manufacturers' recommendations. Each tooth served as its own control. Pre-irrigation and post-irrigation buccal and proximal view photographs served to measure the longest distance of extrusion and were analyzed with ImageJ software. Mean results were analyzed by using Kruskal-Wallis and Dunn post hoc test (P < .05). RESULTS: There were no significant differences between EndoVac, EndoActivator, and the passive extrusion groups. The EndoVac and EndoActivator groups produced significantly less extrusion than PIPS irrigation. Max-i-Probe extrusion results were more variable than those of EndoActivator but had no significant difference. Across all irrigation systems, there were no significant differences with respect to apical preparation size. CONCLUSIONS: Under the in vitro conditions of this study, no difference was found between the 10 mJ and 20 mJ PIPS laser groups. EndoVac demonstrated significantly less potential for apical extrusion than PIPS and Max-i-Probe, whereas apical preparation size did not significantly affect extrusion of irrigant. The potential for apical extrusion of endodontic irrigants should be a consideration when selecting a system for final irrigation.

The effect of 8.25% sodium hypochlorite on dental pulp dissolution and dentin flexural strength and modulus.

INTRODUCTION: The purpose of this study was to evaluate the effect of various concentrations of sodium hypochlorite (NaOCl), including 8.25%, on dental pulp dissolution and dentin flexural strength and modulus. METHODS: Sixty dental pulp samples and 55 plane parallel dentin bars were retrieved from extracted human teeth. Five test groups (n = 10) were formed consisting of a pulp sample and dentin bar immersed in various NaOCl solutions. The negative control group (n = 5) consisted of pulp samples and dentin bars immersed in saline. The positive control group (n = 5) consisted of pulp samples immersed in 8.25% NaOCl without a dentin bar. Every 6 minutes for 1 hour, the solutions were refreshed. The dentin bars were tested for flexural strength and modulus with a 3-point bend test. The time until total pulp dissolution and any changes in dentin bar flexural strength and modulus for the different NaOCl solutions were statistically analyzed. RESULTS: An increase in NaOCl concentration showed a highly significant decrease in pulp dissolution time. The pulp dissolution property of 8.25% NaOCl was significantly faster than any other tested concentration of NaOCl. The presence of dentin did not have a significant effect on the dissolution capacity of NaOCl if the solutions were refreshed. NaOCl concentration did not have a statistically significant effect on dentin flexural strength or modulus. CONCLUSIONS: Dilution of NaOCl decreases its pulp dissolution capacity. Refreshing the solution is essential to counteract the effects of dentin. In this study, NaOCl did not have a significant effect on dentin flexural strength or modulus.

Effect of repeated simulated clinical use and sterilization on the cutting efficiency and flexibility of Hyflex CM nickel-titanium rotary files.

INTRODUCTION: Recent nickel-titanium manufacturing processes have resulted in an alloy that remains in a twinned martensitic phase at operating temperature. This alloy has been shown to have increased flexibility with added tolerance to cyclic and torsional fatigue. The aim of this study was to assess the effect of repeated simulated clinical use and sterilization on cutting efficiency and flexibility of Hyflex CM rotary files. METHODS: Cutting efficiency was determined by measuring the load required to maintain a constant feed rate while instrumenting simulated canals. Flexibility was determined by using a 3-point bending test. Files were autoclaved after each use according to the manufacturer's recommendations. Files were tested through 10 simulated clinical uses. For cutting efficiency, mean data were analyzed by using multiple factor analysis of variance and the Dunnett post hoc test (P < .05). For flexibility, mean data were analyzed by using Levene's Test of Equality of Error and a general linear model (P < .05). RESULTS: No statistically significant decrease in cutting efficiency was noted in groups 2, 5, 6, and 7. A statistically significant decrease in cutting efficiency was noted in groups 3, 4, 8, 9, and 10. No statistically significant decrease in flexibility was noted in groups 2, 3, and 7. A statistically significant decrease in flexibility was noted in groups 4, 5, 6, 8, 9, 10, and 11. CONCLUSIONS: Repeated simulated clinical use and sterilization showed no effect on cutting efficiency through 1 use and no effect on flexibility through 2 uses.

A panoramic survey of air force basic trainees: how research translates into clinical practice.

INTRODUCTION: The purposes of this study were to examine the following in young adults residing in the United States: (1) the prevalence of teeth with root canal therapy (RCT) and teeth in need of RCT, (2) how frequently treatment practices associated with success as cited in the literature are found in posterior teeth with RCT, and (3) which treatment practices are associated with periradicular pathology. METHODS: Panoramic radiographs taken of all basic trainees entering the US Air Force in 2011 were evaluated in a 2-part review. A general survey of all radiographs was performed to determine the prevalence of teeth with and teeth in need of RCT. All panoramic radiographs that showed a posterior tooth with RCT were evaluated in detail to consider the presence and quality of cuspal coverage restorations, the quality of RCT, and the presence of periradicular pathology. RESULTS: A total of 35,811 panoramic images were evaluated. Ten percent of basic trainees had existing RCT, whereas 5% showed a need for RCT. The total number of posterior teeth with RCT was 3,455. Nearly half of these teeth had either no cuspal coverage or an unacceptable cuspal coverage restoration. Almost one third of the existing RCT was considered inadequate based on best treatment practices. Approximately 25% of teeth with RCT had periradicular pathology present. A strong correlation was found between the quality of RCT and the absence of periradicular pathology. Of RCT teeth deemed hopeless, 97.5% had no cuspal coverage restoration present. CONCLUSIONS: Factors cited in the literature as being associated with success are lacking in the dental treatment of young adults residing in the United States.

Healing of apical periodontitis through modern endodontic retreatment techniques.

The presence of apical periodontitis in teeth which have undergone initial root canal treatment is largely attributed to bacteria residing in or invading from the apical root canal space. Bacteria-associated apical periodontitis will not heal spontaneously, nor will systemic antibiotics eradicate the infection. Only endodontic retreatment, endodontic surgery, or extraction will control the bacterial etiology. Modern retreatment is an effective means of addressing apical periodontitis. A mandibular premolar with apical periodontitis, apical root resorption, and overfilled gutta percha was retreated with post removal, retrieval of gutta percha from beyond the apex, ultrasonic irrigation and disinfection, and placement of a collagen internal matrix to facilitate a well-controlled MTA apical fill. The magnification and illumination imparted by the operating microscope was integral to achievement of treatment objectives. The patient's symptoms were resolved and complete osseous healing occurred. During treatment planning, clinicians should consider the capability of modern endodontic techniques to overcome technical challenges, often allowing the natural dentition to be preserved and restored to function days after retreatment.

Comparação da resistência à fadiga por torção das limas de níquel-titânio PathFile com outras limas pequenas de conicidade de 0, 02mm / Comparison of the torsional fatigue resistance of PathFile nickel-titanium files with other small 0.02 mm taper files

Esse estudo teve por objetivo comparar a resistência à fadiga por torção das seguintes limas de conicidade de 0,02mm: PathFile #13, #16 e #19; ProFile #15 e #20; K3 #15 e #20; Quantec LX #15 e #20; e Liberator #15 e #20. Métodos: foram testados 11 grupos, com 20 limas cada. As limas foram fixadas a um torcímetro e submetidas a rotação até fraturar. O torque máximo e o grau de rotação antes da fratura foram registrados. Limas com tamanhos de ponta semelhante foram comparadas entre si para identificar diferenças significativas. O teste ANOVA de uma via e o teste post hoc de Tukey foram usados para identificar diferenças estatisticamente significativas (p < 0,05) entre os grupos. Resultados: as limas Liberator #15 e #20 tiveram fraturas ao torque significativamente mais baixas do que todas as outras limas semelhantes, enquanto a PathFile #16 teve fratura ao torque significativamente mais alta do que as limas #15 com as quais foi comparada. Conclusão: os resultados do teste de resistência à fadiga por torção das limas Path File foram comparativamente melhores do que os de outras limas pequenas com conicidade de 0,02mm.