The Effect of the Ultrasonic Irrigant Activation Protocol on the Removal of a Dual-species Biofilm from Artificial Lateral Canals.

INTRODUCTION: Lateral canals are particularly challenging to clean and disinfect. The aim of this study was to compare the removal efficacy of a dual-species biofilm from a lateral canal model by different ultrasonic irrigant activation protocols in vitro. METHODS: Artificial root canal models with 270 simulated lateral canals were made of polydimethylsiloxane. A dual-species biofilm (Streptococcus oralis and Actinomyces naeslundi) was grown in vitro in the lateral canals using a constant depth film fermenter. Two percent NaOCl or demineralized water was delivered by a syringe and an open-ended needle for 30 seconds and subsequently activated by an ultrasonic file for a total activation time of 30, 60, or 90 seconds divided in 1 or 3 consecutive activation cycles. In the control groups, the irrigant was allowed to rest for 30, 60, or 90 seconds. The volume of the biofilm in the lateral canal was evaluated before and after the final irrigation protocol by optical coherence tomography. The results were analyzed by 3-way factorial analysis of variance (α = 0.05). RESULTS: Irrigation with NaOCl rather than demineralized water resulted in more effective biofilm removal from the lateral canal (P < .001). Three cycles of intermittent ultrasonic activation were significantly more effective than no activation (P = .029). The total irrigant contact time did not affect biofilm removal (P = .403). CONCLUSIONS: The type of the irrigant and the ultrasonic activation protocol affected biofilm removal from artificial lateral canals. None of the compared protocols was able to eradicate the biofilm.

Periodontal breakdown inter-tooth relationships in estimating periodontitis-related tooth loss.

OBJECTIVES: The reasons for tooth extraction are rarely recorded in epidemiological datasets. It poses a diagnostic challenge to determine if tooth loss is related to periodontal disease (TLPD). The present study aimed to assess the inter-tooth relationships based on the periodontal characteristics of existing teeth. METHODS: A cross-sectional dataset of 8,978 participants with complete periodontal examination (including probing pocket depth [PPD] and clinical attachment loss [CAL]) in the NHANES 2009-2014 was used in this study. Spearman rank correlation was applied to assess the inter-tooth correlations of PPD/CAL among 28 teeth after adjustment for relevant confounders. We further verify our findings in the Java Project on Periodontal Disease with TLPD information available (the number of TLPD = 12). RESULTS: Strong PPD/CAL correlations were observed in adjacent teeth (r for PPD = 0.652, r for CAL = 0.597; false discovery rate [FDR] <0.05) rather than those on non-adjacent teeth (r for PPD = 0.515, r for CAL = 0.476; FDR <0.05). The correlations increased among severe periodontitis cases (CAL ≥5 mm or PPD ≥6 mm). In line with this, we further observed that the teeth adjacent to the TLPD tooth had the most alveolar bone loss in the Java dataset. CONCLUSION: The periodontitis parameters (PPD/CAL) of adjacent teeth could be a potential indicator to estimate TLPD when actual reasons for tooth extraction are unknown. CLINICAL SIGNIFICANCE: Periodontally compromised teeth adjacent to a lost tooth may help estimate whether the loss could be related to periodontal disease when the actual extraction reasons are unknown.

Trends in socioeconomic inequality of periodontal health status among Dutch adults: a repeated cross-sectional analysis over two decades.

BACKGROUND: Studies exclusively focusing on trends in socioeconomic inequality of oral health status in industrialized countries are relatively sparse. This study aimed to assess possible differences in oral hygiene and periodontal status among people of different socioeconomic status (SES) in the Netherlands over two decades. METHODS: A repeated cross-sectional analysis of 3083 participants aged 25-54 years was conducted on the Dutch National Oral Health Surveys of 1995, 2002, 2007, and 2013. Plaque-free was defined according to the Simplified Oral Hygiene Index (OHI-S = 0). Periodontal status was classified in two different ways, either periodontal health/disease (probing pocket depth index [PDI] = 0/ ≥ 1) or with/without deep pockets (PDI = 2). We used the regression-based absolute and relative effect index to measure the absolute and relative socioeconomic inequalities. Multivariable logistic regressions were used to explore temporal trends in oral hygiene and periodontal status by low- and high-SES groups. RESULTS: Age-standardized percentages of individuals with plaque-free increased in the whole population from 1995 to 2013 (12.7% [95% CI 10.5-14.9] to 28.1% [24.8-31.5]). Plaque-free showed significant socioeconomic differences in absolute and relative inequalities in 2007 and 2013. Between 1995 and 2013, age-standardized percentage of periodontal health increased (from 51.4% [48.1-54.7] to 60.6% [57.0-64.1]). The significant absolute inequalities for periodontal health were seen in 2002 and 2013. The relative scale presented a similar pattern. Regarding deep pockets, there was little difference in the age-standardized overall prevalence in 1995 versus 2013 (from 6.5% [4.9-8.2] to 5.4% [3.7-7.0]). The significant absolute and relative inequalities in deep pockets prevalence were found in 1995. Yet, all interaction terms between survey year and SES did not reach significance (plaque-free: P = .198; periodontal health: P = .490; deep pockets: P = .678). CONCLUSIONS: Socioeconomic inequalities in oral hygiene and periodontal status were present in the Netherlands in the last two decades.

Dietary inflammatory potential is associated with poor periodontal health: A population-based study.

AIM: To investigate the association between dietary inflammatory potential and poor periodontal health. MATERIAL AND METHODS: A cross-sectional analysis of a nationally representative sample of participants was performed. NHANES 2011-2014 (n = 7081) and NHANES 2001-2004 (n = 5098) were used as discovery and validation datasets, respectively. The energy-adjusted dietary inflammatory index (E-DII) score was calculated for each participant based on 24-h dietary recalls to assess diet-associated inflammation. Periodontitis was defined by the CDC/AAP using clinical periodontal parameters. Natural cubic spline was applied to identify any non-linear associations of the E-DII score with moderate/severe periodontitis. Furthermore, interaction analyses were performed by age, gender, and race/ethnicity to explore the moderating roles of these factors. RESULTS: In the discovery dataset, a non-linear positive relationship with periodontitis was identified for the E-DII score (pnon-linearity  < .001) after adjustment for potential confounders. Compared with those individuals in the lowest tertile of E-DII, participants in the highest tertile who consumed a pro-inflammatory diet were 53% more likely to be periodontitis (OR tertile3vs1  = 1.53, 95% CI: 1.33-1.77). The validation dataset showed similar associations. Relatively stronger associations were seen in older adults and males. CONCLUSION: Consuming a pro-inflammatory diet indicated by the E-DII score is associated with periodontal disease in the U.S. general adult population.

White Blood Cell Count Mediates the Association Between Periodontal Inflammation and Cognitive Performance Measured by Digit Symbol Substitution Test Among Older U.S. Adults.

BACKGROUND: Systemic effects of periodontal infection may increase the risk of central neuroinflammation, aggravating impaired cognition. This study aims to examine whether systemic inflammatory factors mediate the possible association between periodontal inflammation and cognitive function. METHODS: We conducted a cross-sectional analysis of 766 participants aged ≥ 60 years and who had completed periodontal and cognitive examinations in the National Health and Nutrition Examination Survey (NHANES) 2001-2002. We used multivariable linear regression to investigate the overall association between periodontal health and cognitive function as measured by the digit symbol substitution test (DSST). Bleeding on probing (BOP) and periodontal inflamed surface area (PISA) were used to assess the periodontal inflammatory activity and burden, respectively. Mediation analyses were used to test the indirect effects of the BOP/PISA on DSST via C-reactive protein, white blood cell (WBC) count, and fibrinogen. RESULTS: Participants with superior periodontal health obtained higher DSST scores than those with poorer periodontal health, adjusting for demographic factors and chronic conditions. Concerning the inflammatory activity, WBC count acted as a full mediator in the association between BOP and DSST (ß = -0.091; 95% confidence interval [CI] = -0.174 to -0.008) and mediated 27.5% of the total association. Regarding the inflammatory burden, WBC count acted as a partial mediator in the association between PISA and DSST (ß = -0.059; 95% CI = -0.087 to -0.031) and mediated 20.3% of the total association. CONCLUSION: Our study indicated the potential role of systemic inflammatory factors as a mediator of associations between periodontal inflammation and cognitive function in the U.S. geriatric population.

Relationship between 18F-FDG Uptake in the Oral Cavity, Recent Dental Treatments, and Oral Inflammation or Infection: A Retrospective Study of Patients with Suspected Endocarditis.

[18F]-fluorodeoxyglucose positron emission tomography ([18F]FDG PET/CT) has proven to be a useful diagnostic tool in patients with suspected infective endocarditis (IE), but is conflicting in relation to dental procedures. QUESTIONS: Is there a correlation between [18F]FDG PET/CT findings, recent dental treatment, and an affected oral cavity? (2) Is there a correlation between infective endocarditis (IE), oral health status, and (extra)cardiac findings on [18F]FDG PET/CT? METHODS: This retrospective study included 52 patients. All [18F]FDG PET/CT scans were examined visually by pattern recognition using a three-point scale and semi-quantified within the volume of interest (VOI) using SUVmax. RESULTS: 19 patients were diagnosed with IE (group 1), 14 with possible IE (group 2), and 19 without IE based on the modified Duke criteria (group 3). No correlation was found between visual PET and SUVmax and sites of oral inflammation and infection. The visual PET scores and SUVmax were not significantly different between all groups. A significant difference in the SUVmax of the valve between all groups was observed. CONCLUSIONS: This study suggests that no correlation exists between the PET findings in the oral cavity and dental treatments or inflammation/infection. No correlation between IE, actual oral health status, and extra-cardiac findings was demonstrated. Additional research is needed to conclude whether [18F]FDG PET/CT imaging is a reliable diagnostic modality for oral inflammation and infection sites.

Definitions used for a healthy periodontium-A systematic review.

OBJECTIVE: To investigate the explicitness and variability of the definition of periodontal health in the current scientific literature. MATERIAL AND METHODS: The authors conducted a systematic literature review using PubMed and CENTRAL (2013-01/2019-05) according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and the guidelines of the Meta-analysis Of Observational Studies in Epidemiology (MOOSE) statement. RESULTS: A total of 51 papers met the predefined inclusion criteria. Of these, 13 papers did not report any explicit definitions of periodontal health. Out of the 38 remaining articles, half of them used a reference to support their definition and half of them not. The studies published in periodontics-related journals or those that scored a low risk of bias for the methodical quality presented more explicit and valid definitions. Probing pocket depth was the most frequently used individual parameter for defining periodontal health. However, there were substantial variations in the methods of measurement and cut-off values. CONCLUSIONS: Given the diversity of periodontal health definitions, a cross-study comparison is difficult. The results of this review may be useful in making others aware of the significance of standardizing the definition of a healthy periodontium.

Effect of Dentin Matrix Components on the Mineralization of Human Mesenchymal Stromal Cells.

IMPACT STATEMENT: This research has been conducted with the aim to contribute to the development of treatment modalities for the reconstruction of lost/damaged mineralized tissues. Currently, determining the most appropriate stromal cell population and signaling cues stands at the core of developing effective treatments. We provide new insights into the effect of innate inductive cues found in human dentin matrix components, on the osteogenic differentiation of various human stromal cell types. The effects of dentin extracellular matrix components on umbilical cord mesenchymal stromal cells have not been investigated before. The findings of this study could underpin translational research based on the development of techniques for mineralized tissue engineering and will be of great interest for the readership of Tissue Engineering Part A.

Secreted products of oral bacteria and biofilms impede mineralization of apical papilla stem cells in TLR-, species-, and culture-dependent fashion.

Regenerative endodontics exploits the mineralization potential of stem cells from the apical papilla (SCAPs) in order to promote root maturation of permanent immature teeth. SCAPs may encounter post-disinfection residual bacteria either in planktonic or in biofilm growth mode. Bacterial components bind to Toll-like receptors (TLRs) and trigger pro-inflammatory responses. We hypothesized that biofilm-triggered TLR activation affects the mineralization potential of human SCAPs. SCAPs were challenged with conditioned media derived from standardized dual-species biofilms and planktonic bacterial cultures and their inflammatory status and mineralization capacity were studied. Bacterial products from both growth modes (planktonic vs. biofilm) compromised cell viability, proliferation and mineralization capacity of SCAPs, but in a species- and growth mode-dependent fashion. While TLR4 expression remained unaffected, TLR2 expression was upregulated coinciding with a pro-inflammatory activation of SCAPs. Moreover, TLR and its downstream TGF-ß-associated kinase (TAK1) appeared to be blocking mineralization, as inhibition of these factors restored it. In conclusion, bacterial products promoted the pro-inflammatory status and inhibited mineralization of human SCAPs in a TLR-, species-, and culture-dependent fashion. TLR2 emerged as the pivotal mediator of these responses and further research is warranted towards the judicious manipulation of SCAPs in order to modify the untoward events of TLR-priming and signaling.

Detection of Legionella Anisa in Water from Hospital Dental Chair Units and Molecular Characterization by Whole-Genome Sequencing.

This study aims to assess contamination with Legionella spp. in water from dental chair units (DCUs) of a hospital dental ward and to perform its molecular characterization by whole-genome sequencing (WGS). We collect eight water samples (250 mL) from four DCUs (sink and water-syringe). Samples are tested for the presence of Legionella spp. (CFUs/mL) by culturing according to the Nederland Norm (NEN) 6265. Three DCUs are found positive for Legionella anisa, and four isolates are cultured (sink n = 2, water-syringe n = 1; two isolates from the same chair) with 1 × 10² CFU/mL. Whole-genome multi-locus sequence typing (wgMLST) results indicate that all strains belong to the same cluster with two to four allele differences. Classical culture combined with WGS allows the identification of a unique clone of L. anisa in several DCUs in the same hospital dental ward. This may indicate a common contamination source in the dental unit waterlines, which was fixed by replacing the chairs and main pipeline of the unit. Our results reveal tap water contamination in direct contact with patients and the usefulness of WGS to investigate bacterial molecular epidemiology.

Temperature evolution of preheated irrigant injected into a root canal ex vivo.

OBJECTIVES: The aim of this study is to test the influence of the temperature of the surrounding medium, flow rate, duration of irrigation, and apical patency on the evolution of the temperature of irrigants injected in a root canal. MATERIALS AND METHODS: Thermocouples were inserted into an incisor at different positions to monitor irrigant temperature during and after injection at 21, 45, or 60 °C. The tooth was immersed in a water bath at 21 and 37 °C. RESULTS: Preheated syringes were used for up to 2.5 min before being cooled down from 60 to below 45 °C. The irrigant temperature was higher apically than at coronal levels (P ≤ 0.028). The duration of irrigation had no influence on the average temperatures during delivery (P ≥ 0.337), but the apical patency lowered the intracanal temperature (P = 0.004). The highest temperature measured on the outside of the tooth was 39 °C. CONCLUSIONS: Preheating the irrigant at 60 °C resulted in temperatures higher than 45 °C throughout the root canal, during irrigant delivery. After completion, the temperature dropped rapidly. CLINICAL RELEVANCE: These results contribute to a better understanding of the optimum irrigant delivery time at given temperature, the cooling rate of irrigant in the syringe, and the influence of heated irrigant temperature in the periodontium, which should guide the preheated syringe turnover.

Management of Apical Periodontitis: Healing of Post-treatment Periapical Lesions Present 1 Year after Endodontic Treatment.

INTRODUCTION: Post-treatment periapical lesions present 1 year after treatment may heal during the second year or later. The aim of this study was to assess second-year volumetric changes in post-treatment periapical radiolucencies detected 1 year after treatment. METHODS: Post-treatment periapical radiolucencies were detected on cone-beam computed tomographic (CBCT) scans obtained from 93 single-rooted teeth 1 year after endodontic treatment. The outcome of these teeth was evaluated 2 years after treatment. Two examiners independently measured the volume of the radiolucencies on CBCT images twice. A Wilcoxon signed rank test was used to assess the 1- and 2-year post-treatment volumes. RESULTS: The intraclass correlation coefficients for the CBCT volumetric measurements were 0.971 and 0.998 for the 2 examiners, and the interexaminer correlation coefficient was 0.998. Of the 93 teeth with post-treatment radiolucencies at 1 year, 61were examined at the second-year evaluation. The overall size of the radiolucencies significantly decreased during the second year (P = .01); the volume decreased in 38 teeth (63%), remained unchanged in 20 (33%), and increased in 2 (3%). CONCLUSIONS: The volume of post-treatment periapical radiolucencies detected 1 year after treatment was significantly reduced after the second year in 63% of teeth.

Influence of the dentinal wall on the pH of sodium hypochlorite during root canal irrigation.

INTRODUCTION: The purpose of this study was to evaluate the influence of dentin on the pH levels of different concentrations of sodium hypochlorite (NaOCl) solutions over time and to evaluate if preconditioning of dentin with 17% EDTA or agitation of the NaOCl solution influences these pH levels. METHODS: A novel clinically representative model that scales with the ratio of the irrigant volume to the dentin surface area of a human root canal was used. Three standardized bovine dentin bars (2 × 2 × 10 mm) were placed in a plastic test tube. A total of 150 tubes were distributed in 29 groups. In the first experiment, the pH of various NaOCl solutions, with different concentrations (3%, 6%, and 9%) and starting pH levels (5 and 12), was monitored during exposure to dentin between 10 and 300 seconds. In a second experiment, the effect of agitation (45 Hz) and pretreatment of dentin with 17% EDTA on the pH levels of various NaOCl solutions was studied after 30 seconds of exposure to dentin. The short-term chemical stability of the tested solutions was assessed for both the concentration and the pH. RESULTS: The exposure time (P < .001) and concentration of the NaOCl solution (P < .011) significantly influence the pH level after exposure to dentin. However, the change in pH is too small to induce a change in the irrigant antimicrobial/tissue dissolution capacity. CONCLUSIONS: Agitation of the irrigant and preconditioning of the dentin did not alter the pH (P > .05). Both the pH 5 and pH 12 solutions were chemically stable for 1 hour.

Cavitation measurement during sonic and ultrasonic activated irrigation.

INTRODUCTION: The aims of this study were to quantify and to visualize the possible occurrence of transient cavitation (bubble formation and implosion) during sonic and ultrasonic (UAI) activated irrigation. METHODS: The amount of cavitation generated around several endodontic instruments was measured by sonochemiluminescence dosimetry inside 4 root canal models of human dimensions and varying complexity. Furthermore, the spatial distribution of the sonochemiluminescence in the root canal was visualized with long-exposure photography. RESULTS: Instrument oscillation frequency, ultrasonic power, and file taper influenced the occurrence and amount of cavitation. In UAI, cavitation was distributed between the file and the wall extending beyond the file and inside lateral canals/isthmuses. In sonic activated irrigation, no cavitation was detected. CONCLUSIONS: Cavitation was shown to occur in UAI at clinically relevant ultrasonic power settings in both straight and curved canals but not around sonically oscillating instruments, driven at their highest frequency.

Radiographic healing after a root canal treatment performed in single-rooted teeth with and without ultrasonic activation of the irrigant: a randomized controlled trial.

INTRODUCTION: The aim of this study was to compare the outcome of a root canal treatment with and without additional ultrasonic activation of the irrigant. METHODS: Single-rooted teeth with radiographic evidence of periapical bone loss were randomly assigned to 2 treatment groups. In both groups syringe irrigation was performed, and in one group the irrigant was also activated by ultrasound. Ten to 19 months after treatment, the teeth were examined by using periapical radiography (PA) and cone-beam computed tomography (CBCT). Area and volume of the periapical lesions were measured, and the outcome was presented in 4 categories: absence, reduction or enlargement of the radiolucency, or uncertain. Lesions were classified as reduced or enlarged when the change in size of the radiolucency was 20% or more. RESULTS: The recall rate was 82%, and 84 teeth were analyzed. CBCT detected significantly more post-treatment lesions than PA (P = .038), but the percentages of absence and reduction of the radiolucency together revealed by CBCT and PA were similar (P = .383). The CBCT results showed that absence of the radiolucency was observed in 16 of 84 teeth (19%) and reduction of the radiolucency in 61 of 84 teeth (72.6%), but there was no significant difference between the results of the 2 groups (P = .470). Absence and reduction of the radiolucency together were observed in the ultrasonic group in 39 of 41 teeth (95.1%) and in the syringe group in 38 of 43 teeth (88.4%). CONCLUSIONS: Root canal treatments with and without additional ultrasonic activation of the irrigant contributed equally to periapical healing.

Histological responses of the periodontium to MTA: a systematic review.

AIM: The purpose of this systematic review was to investigate whether a mineral trioxide aggregate (MTA) restoration of an endodontic-periodontal communication leads to regeneration of the adjacent periodontal tissues. METHODOLOGY: The databases MEDLINE-PubMed, Cochrane-CENTRAL, and EMBASE were searched, up to July 2012. In vivo studies that reported on the histological response of the periodontium to MTA were selected. RESULTS: The screening of 98 title-abstracts, full-text reading, and hand searches in literature lists yielded 24 papers. All of them involved animals. There were no studies reporting on human histology. Study protocols presented heterogeneity regarding treated lesions, intervention, and reported outcomes. The histological results of the animal studies showed minimal inflammatory reactions, bone healing, periodontal ligament presence, and consistent cementum formation. Time lapse after mixing, bacterial contamination, root canal disinfection, and inflammation influenced MTA's cementoconductive properties. CONCLUSIONS: Within the limitations of the selected papers concerning inhomogeneous study protocols and low methodological quality scores, their findings were consistent with regard to MTA's biocompatibility and cementogenic ability. Experimental animal studies show that MTA can promote healing towards regeneration. There is now a distinct need to examine the clinical performance of MTA in well-controlled prospective human cohort studies.

Oscillation characteristics of endodontic files: numerical model and its validation.

During a root canal treatment, an antimicrobial fluid is injected into the root canal to eradicate all bacteria from the root canal system. Agitation of the fluid using an ultrasonically vibrating miniature file results in a significant improvement in the cleaning efficacy over conventional syringe irrigation. Numerical analysis of the oscillation characteristics of the file, modeled as a tapered, driven rod, shows a sinusoidal wave pattern with an increase in amplitude and decrease in wavelength toward the free end of the file. Measurements of the file oscillation with a scanning laser vibrometer show good agreement with the numerical simulation. The numerical model of endodontic file oscillation has the potential for predicting the oscillation pattern and fracture likeliness of various file types and the acoustic streaming they induce during passive ultrasonic irrigation.

Localized removal of layers of metal, polymer, or biomaterial by ultrasound cavitation bubbles.

We present an ultrasonic device with the ability to locally remove deposited layers from a glass slide in a controlled and rapid manner. The cleaning takes place as the result of cavitating bubbles near the deposited layers and not due to acoustic streaming. The bubbles are ejected from air-filled cavities micromachined in a silicon surface, which, when vibrated ultrasonically at a frequency of 200 kHz, generate a stream of bubbles that travel to the layer deposited on an opposing glass slide. Depending on the pressure amplitude, the bubble clouds ejected from the micropits attain different shapes as a result of complex bubble interaction forces, leading to distinct shapes of the cleaned areas. We have determined the removal rates for several inorganic and organic materials and obtained an improved efficiency in cleaning when compared to conventional cleaning equipment. We also provide values of the force the bubbles are able to exert on an atomic force microscope tip.

A 1-year follow-up study on leakage of single-cone fillings with RoekoRSA sealer.

OBJECTIVE: The aim of this study was to measure long-term leakage along single cone (SC) fillings. STUDY DESIGN: Two groups of canines (n = 30) were prepared and a size 55 file was the apical master file. Step-back was performed using files of sizes 60, 70, and 80. The canals were filled by the single cone technique using RoekoRSA as sealer. To place sealer into each canal, a bidirectional spiral was used in 1 group, whereas a gutta-percha cone was used in the other group. Immediately after root filling, the coronal portion of root filling was removed by postspace preparation. Leakage along the 4 mm remaining apical root filling was measured after 1 week and again after 1 year using a fluid transport model. Ten additional canine roots were prepared and filled with gutta-percha cones without sealer, serving as positive controls. Occurrence of apical extrusion of materials was recorded. RESULTS: The apical root filling in all 60 canine roots did not show leakage either at 1 week or at 1 year. All 10 positive controls showed gross leakage (>20 muL/h). In no case gutta-percha extruded through the apical foramen. Sealer extruded apically in 88% of the roots where a gutta-percha cone was used to introduce sealer, whereas in 28% of the roots where a bidirectional spiral was used to introduce sealer (by chi-square test, P < .05). CONCLUSION: In wide and straight canals, SC fillings with RoekoRSA sealer prevented fluid transport for 1 year. Using bidirectional spiral to place sealer reduced sealer extrusion under the conditions of this experiment.