Christine M. Sedgley

Are endodontically treated teeth more brittle

This study compared biomechanical properties (punch shear strength, toughness, hardness, and load to fracture) of 23 endodontically treated teeth (mean time since endodontic treatment: 10.1 yr) and their contralateral vital pairs. Analyses using paired t tests revealed no significant differences in punch shear strength, toughness, and load to fracture between the two groups. Vital dentin was 3.5% harder than dentin from contralateral endodontically treated teeth (p = 0.002). The similarity between the biomechanical properties of endodontically treated teeth and their contralateral vital pairs indicates that teeth do not become more brittle following endodontic treatment. Other factors may be more critical to failure of endodontically treated teeth.

Role of (p)ppGpp in Biofilm Formation by Enterococcus faecalis

ABSTRACT Enterococcus faecalis strain OG1RF and its (p)ppGpp-deficient ΔrelA, ΔrelQ, and ΔrelA ΔrelQ mutants were grown in biofilms and evaluated for growth profiles, biofilm morphology, cell viability, and proteolytic activity. E. faecalis lacking (p)ppGpp had a diminished capacity to sustain biofilm formation over an extended period of time and expressed abundant proteolytic activity.

Current Trends in Endodontic Treatment by General Dental Practitioners: Report of a United States National Survey

INTRODUCTION In the United States almost 70% of root canal treatment (RCT) is performed by general dentists (GPs), yet little is known about their treatment protocols. METHODS A paper survey was mailed to 2000 United States GPs with questions about the types of endodontic cases treated, routine treatment protocols, use of newer technologies, and endodontic continuing education (CE). RESULTS Completed surveys were returned by 479 respondents (24%). GPs who perform RCT (84%) reported providing anterior (99%), bicuspid (95%), and molar (62%) RCT and retreatment (18%). Rubber dam was used always (60%), usually (16%), sometimes (13%), and never (11%). Newer technologies used by GPs included digital radiography (72%), magnification (80%), electronic apex locator (70%), and nickel-titanium rotary instrumentation (74%). Compared with GPs with >20 years of experience, those in practice for ≤10 years were more likely to use rubber dam (P < .05), nickel-titanium rotary instrumentation (P < .001), apex locators (P < .001), and magnification (P < .01); in contradistinction, GPs in practice >20 years were more likely to perform retreatments (P < .05). Women were less likely to perform retreatment or molar RCT (both P < .05). GPs with >5 hours of CE were more likely to use rotary instrumentation (P < .001), irrigant activation devices (P < .01), and apex locators (P < .001) and perform molar RCT (P < .001) and retreatment (P < .05), but no more likely to use rubber dam. CONCLUSIONS Recent GP graduates (≤10 years) were more likely to adopt new technologies and use rubber dam than those who practiced for >20 years. More experienced GPs were more likely to take on complicated cases than those with fewer years of practice. There was no association between hours of CE and compliance with rubber dam usage.

Comparison of a Continuous Ultrasonic Irrigation Device and Conventional Needle Irrigation in the Removal of Root Canal Debris

INTRODUCTION The purpose of this in vitro study was to compare a continuous ultrasonic irrigation device (VPro StreamClean System [VSS], Vista Dental Products, Racine, WI) with conventional needle irrigation when used as a final irrigation procedure to debride the apical region of the root canal. The null hypothesis that there is no difference was tested. METHODS Root canals of matched pairs (N = 20) of extracted human teeth were prepared to an apical size of 36/.04 using Profile series 29/.04 rotary files (Dentsply Tulsa Dental, Tulsa, OK) with 6% sodium hypochlorite (NaOCl) irrigation. One tooth of each pair was randomly assigned to receive final irrigation with either VSS or conventional needle irrigation. The gauge of the needle (#30), the irrigation cycles (ie, 5 mL NaOCl, 5 mL 15% EDTA, and 5 mL NaOCl), the irrigant flow rate (5 mL/min), and needle depth placement (1 mm from the working length [WL]) were experimental constants. Serial sections were obtained at 1 and 3 mm from the WL, stained with hematoxylin-eosin, and viewed at 100× magnification for the presence of debris. The percentage of debris in the canal lumen after VSS or conventional needle irrigation was compared by using the Wilcoxon matched pairs test. RESULTS There was significantly less debris in the VSS group compared with the conventional needle irrigation group at the 1-mm level (1.50% [VSS] vs 9.90% [conventional needle irrigation], P = .0001) and the 3-mm level (0.45% [VSS] vs 5.16% [conventional needle irrigation], P = .0014). The null hypothesis was rejected. CONCLUSIONS Final irrigation with the VSS compared with conventional needle irrigation delivery resulted in significantly less debris present in root canals at 1 and 3 mm from the WL.

CRISPR-Cas, a Prokaryotic Adaptive Immune System, in Endodontic, Oral, and Multidrug-resistant Hospital-acquired Enterococcus faecalis

INTRODUCTION Microorganisms are vulnerable to invasion by mobile genetic elements such as viruses, plasmids, and transposons. The recently discovered Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-associated system, or CRISPR-Cas, is an adaptive immunity system found in most archaea and many bacteria that targets and inactivates invading foreign genetic elements. Cells with CRISPR-cas are more likely to resist the invasion and uptake of foreign DNA such as viruses, plasmids, and transposons. The aims of this study were to (1) compare the occurrence of CRISPR-cas in collections of endodontic (n = 34), oral (n = 21), and multidrug-resistant hospital-acquired strains of Enterococcus faecalis (n = 23) and (2) evaluate the distribution of antibiotic resistance and virulence traits among strains without CRISPR-cas. METHODS E. faecalis strains were screened for CRISPR1-cas and CRISPR3-cas by using polymerase chain reaction, and products were verified by DNA sequencing. Associations were investigated between the occurrence of CRISPR-cas and the expression of phenotypic traits (antibiotic resistance, gelatinase activity, bacteriocin production, hemolysin activity, and clumping response to pheromone). RESULTS CRISPR-cas determinants were present in proportionally more endodontic (25 of 34) and oral (15 of 21) strains than hospital-acquired (9 of 23) strains (P = .01 and .04, respectively). Significant associations were found between the absence of CRISPR-cas and the presence of antibiotic resistance in strains overall (P = .04) and bacteriocin activity in endodontic strains (P = .01). CONCLUSIONS Evidence for the presence of CRISPR-cas in the majority of endodontic and oral E. faecalis strains raises intriguing questions as to how prokaryotic immune systems might modulate interactions within the polymicrobial endodontic biofilm environment.

Does Articaine Provide an Advantage over Lidocaine in Patients with Symptomatic Irreversible Pulpitis? A Systematic Review and Meta-analysis

INTRODUCTION Achieving profound pulpal anesthesia can be difficult in patients with symptomatic irreversible pulpitis. This study provides a systematic review and meta-analysis to address the population, intervention, comparison, outcome (PICO) question: in adults with symptomatic irreversible pulpitis who are undergoing endodontic treatment, what is the comparative efficacy of articaine compared with lidocaine in reducing pain and incidence of adverse events? METHODS A protocol was prepared and registered on PROSPERO. Electronic searches were conducted in MEDLINE, Scopus, Cochrane Library, and ClinicalTrials.gov by using strict inclusion and exclusion criteria. Two independent reviewers assessed eligibility for inclusion and quality. Weighted anesthesia success rates and 95% confidence intervals (CIs) were estimated and compared by using a random-effects model. RESULTS Two hundred seventy-five studies were initially identified from the search; 10 double-blind, randomized clinical trials met the inclusion criteria. For combined studies, articaine was more likely than lidocaine to achieve successful anesthesia (odds ratio [OR], 2.21; 95% CI, 1.41-3.47; P = .0006; I(2) = 40%). Maxillary infiltration subgroup analysis showed no significant difference between articaine and lidocaine (OR, 3.99; 95% CI, 0.50-31.62; P = .19; I(2) = 59%). For combined mandibular anesthesia studies articaine was superior to lidocaine (OR, 2.20; 95% CI, 1.40-3.44; P = .0006; I(2) = 30%), with further subgroup analysis showing no difference for mandibular block anesthesia (OR, 1.44; 95% CI, 0.87-2.38; P = .16; I(2) = 0%). When used for supplemental infiltration after successful mandibular block anesthesia, articaine was significantly more effective than lidocaine (OR, 3.55; 95% CI, 1.97-6.39; P < .0001; I(2) = 9%). There were no reports of adverse events. CONCLUSIONS This systematic review of double-blind, randomized clinical trials provides level 1 evidence to support the use of articaine for patients with symptomatic irreversible pulpitis. There is a significant advantage to using articaine over lidocaine for supplementary infiltration after mandibular block anesthesia but no advantage when used for mandibular block anesthesia alone or for maxillary infiltration.

Effects of intracanal mineral trioxide aggregate and calcium hydroxide during four weeks on pH changes in simulated root surface resorption defects: an in vitro study using matched pairs of human teeth.

INTRODUCTION Diffusion of hydroxyl ions from intracanal calcium hydroxide (CH) through dentin is used to arrest external inflammatory root resorption. However, long-term and short-term CH placement has been associated with an increased risk of root fracture. Intracanal mineral trioxide aggregate (MTA) might provide an alternative to CH as a source of hydroxyl ions. This in vitro study compared the effects of intracanal MTA and CH on hydroxyl ion diffusion through dentin by measuring pH changes over time in simulated root surface resorption defects prepared in matched pairs of teeth; the null hypothesis tested was that there is no difference. METHODS Root surface cavities were prepared 5 mm from the apex in extracted human permanent anterior teeth (21 matched pairs) and 7 additional teeth (controls). Root canals were instrumented to size 50/.04 and filled with either tooth-colored MTA (ProRoot) or CH (UltraCal XS); control teeth were filled with saline. The pH in root surface cavities was measured at 3 hours, 24 hours, 1 week, 2 weeks, 3 weeks, and 4 weeks. RESULTS In controls, pH readings did not differ significantly during the 4 weeks (P > .05, repeated-measures analysis of variance [ANOVA]). For the experimental intragroup effects, significant pH changes occurred over time in the MTA group (P = .005, repeated-measures ANOVA) and the CH group (P < .0001). For the experimental intergroup effects, the overall mean pH was higher in the MTA group (8.66; standard error [SE], 0.07) compared with the CH group (8.46; SE, 0.07) (P = .014, paired t test). At 4 weeks pH was higher in the MTA group (8.30; SE, 0.16) compared with the CH group (7.90; SE, 0.11) (P = .011); at all other time points intergroup differences were insignificant. The null hypothesis was rejected. CONCLUSIONS Intracanal MTA and CH groups differed in their overall effect on pH measured in simulated root surface resorption defects. At 4 weeks intracanal placement of MTA compared with CH resulted in a small but significantly higher pH.

A Novel Strategy to Engineer Pre-Vascularized Full-Length Dental Pulp-like Tissue Constructs

The requirement for immediate vascularization of engineered dental pulp poses a major hurdle towards successful implementation of pulp regeneration as an effective therapeutic strategy for root canal therapy, especially in adult teeth. Here, we demonstrate a novel strategy to engineer pre-vascularized, cell-laden hydrogel pulp-like tissue constructs in full-length root canals for dental pulp regeneration. We utilized gelatin methacryloyl (GelMA) hydrogels with tunable physical and mechanical properties to determine the microenvironmental conditions (microstructure, degradation, swelling and elastic modulus) that enhanced viability, spreading and proliferation of encapsulated odontoblast-like cells (OD21), and the formation of endothelial monolayers by endothelial colony forming cells (ECFCs). GelMA hydrogels with higher polymer concentration (15% w/v) and stiffness enhanced OD21 cell viability, spreading and proliferation, as well as endothelial cell spreading and monolayer formation. We then fabricated pre-vascularized, full-length, dental pulp-like tissue constructs by dispensing OD21 cell-laden GelMA hydrogel prepolymer in root canals of extracted teeth and fabricating 500 µm channels throughout the root canals. ECFCs seeded into the microchannels successfully formed monolayers and underwent angiogenic sprouting within 7 days in culture. In summary, the proposed approach is a simple and effective strategy for engineering of pre-vascularized dental pulp constructs offering potentially beneficial translational outcomes.

A Survey for Endodontists in Today's Economy: Exploring the Current State of Endodontics as a Profession and the Relationship between Endodontists and Their Referral Base

INTRODUCTION The purpose of this study was to assess the perceptions, referral trends, and practice patterns of practicing endodontists in the United States and any effect the recent economy may have had on these. METHODS A 24-question survey was formulated and sent via www.surveymonkey.com to 3255 active members of the American Association of Endodontists. Overall, 875 participants completed the survey, a response rate of 26.9%. RESULTS The average number of treatment cases per day was 5.7. Average work hours per week were 34.3 for men and 30.7 for women (P < .05). Among all treatment cases, 46% were nonsurgical retreatment, and 7.2% were apical surgical procedures. Procedural misadventure accounted for 10.8% of all treatment cases, with the most common referral reason being unable to locate canals (75.0%) followed by separated instruments (15.3%). Of all respondents, 49.9% performed regenerative endodontic procedures, and 7.7% placed implants. Among endodontists who practice in urban areas, 69.7% believed there were too many endodontists, and 50% have delayed their retirement plans because of recent economic impact, compared with their suburban and rural counterparts at 66.1% and 38%, 25.9% and 33.1%, respectively (P < .05). Fifty-nine percent of respondents were optimistic about the future of endodontics as a specialty, but those who have practiced more than 20 years were more pessimistic than those with less experience (P < .05). CONCLUSIONS Recent economic impacts appear to have had an effect on the perceptions of active endodontists regarding practice success, the future of the specialty, and their retirement plans. Those who have been in practice longest (>20 years), practice in urban settings, and practice in a solo environment are most significantly affected.

Oral microbiota species in acute apical endodontic abscesses.

Background and objectives Acute apical abscesses are serious endodontic diseases resulting from pulpal infection with opportunistic oral microorganisms. The objective of this study was to identify and compare the oral microbiota in patients (N=18) exhibiting acute apical abscesses, originating from the demographic region in Portland, Oregon. The study hypothesis is that abscesses obtained from this demographic region may contain unique microorganisms not identified in specimens from other regions. Design Endodontic abscesses were sampled from patients at the Oregon Health & Science University (OHSU) School of Dentistry. DNA from abscess specimens was subjected to polymerase chain reaction amplification using 16S rRNA gene-specific primers and Cy3-dCTP labeling. Labeled DNA was then applied to microbial microarrays (280 species) generated by the Human Oral Microbial Identification Microarray Laboratory (Forsyth Institute, Cambridge, MA). Results The most prevalent microorganisms, found across multiple abscess specimens, include Fusobacterium nucleatum, Parvimonas micra, Megasphaera species clone CS025, Prevotella multisaccharivorax, Atopobium rimae, and Porphyromonas endodontalis. The most abundant microorganisms, found in highest numbers within individual abscesses, include F. nucleatum, P. micra, Streptococcus Cluster III, Solobacterium moorei, Streptococcus constellatus, and Porphyromonas endodontalis. Strong bacterial associations were identified between Prevotella multisaccharivorax, Acidaminococcaceae species clone DM071, Megasphaera species clone CS025, Actinomyces species clone EP053, and Streptococcus cristatus (all with Spearman coefficients >0.9). Conclusions Cultivable and uncultivable bacterial species have been identified in endodontic abscesses obtained from the Portland, Oregon demographic region, and taxa identifications correlated well with other published studies, with the exception of Treponema and Streptococcus cristae, which were not commonly identified in endodontic abscesses between the demographic region in Portland, Oregon and other regions.