Federico Foschi

Photodynamic treatment of endodontic polymicrobial infection in vitro

We investigated the photodynamic effects of methylene blue on multispecies root canal biofilms comprising Actinomyces israelii, Fusobacterium nucleatum subspecies nucleatum, Porphyromonas gingivalis, and Prevotella intermedia in experimentally infected root canals of extracted human teeth in vitro. The 4 test microorganisms were detected in root canals by using DNA probes. Scanning electron microscopy showed the presence of biofilms in root canals before therapy. Root canal systems were incubated with methylene blue (25 microg/mL) for 10 minutes followed by exposure to red light at 665 nm with an energy fluence of 30 J/cm(2). Light was delivered from a diode laser via a 250-microm diameter polymethyl methacrylate optical fiber that uniformly distributed light over 360 degrees. Photodynamic therapy (PDT) achieved up to 80% reduction of colony-forming unit counts. We concluded that PDT can be an effective adjunct to standard endodontic antimicrobial treatment when the PDT parameters are optimized.

Nanoparticle-based endodontic antimicrobial photodynamic therapy

OBJECTIVE To study the in vitro effects of poly(lactic-co-glycolic acid) (PLGA) nanoparticles loaded with the photosensitizer methylene blue (MB) and light against Enterococcus faecalis (ATCC 29212). MATERIALS AND METHODS The uptake and distribution of nanoparticles in E. faecalis in suspension was investigated by transmission electron microscopy (TEM) after incubation with PLGA complexed with colloidal gold particles for 2.5, 5, and 10 minutes. E. faecalis species were sensitized in planktonic phase and in experimentally infected root canals of human extracted teeth with MB-loaded nanoparticles for 10 minutes followed by exposure to red light at 665 nm. RESULTS The nanoparticles were found to be concentrated mainly on the cell walls of microorganisms at all three time points. The synergism of light and MB-loaded nanoparticles led to approximately 2 and 1 log10 reduction of colony-forming units (CFUs) in planktonic phase and root canals, respectively. In both cases, mean log10 CFU levels were significantly lower than controls and MB-loaded nanoparticles without light. CONCLUSION The utilization of PLGA nanoparticles encapsulated with photoactive drugs may be a promising adjunct in antimicrobial endodontic treatment.

Changes in centring and shaping ability using three nickel–titanium instrumentation techniques analysed by micro-computed tomography (μCT)

AIM To compare the centring ability and the shaping ability of ProTaper (PT) files used in reciprocating motion and PT and Twisted Files (TF) used in continuous rotary motion, and to compare the volume changes obtained with the different instrumentation techniques using micro-computed tomography. Methodology Sixty mesial canals of thirty mandibular molars were randomly assigned to three instrumentation techniques: group 1, canals prepared with the PT series (up to F2) (n = 20); group 2, canals prepared with the F2 PT in reciprocating motion (n = 20); group 3 canals prepared with the TF series (size 25) (n = 20). Teeth were scanned pre- and postoperatively using micro-computed tomography to measure volume and shaping changes, and the obtained results were statistically analysed using parametric tests. Results The increase in canal volume obtained with the three instrumentation techniques was not significantly different. Canals were transported mostly towards the mesial aspect in the apical- and mid-third of the roots, and towards the furcal aspect coronally. No difference in the transportation and centring ratio was found between the techniques. There was no significant difference between the times of instrumentation (TF: 62.5 ± 5.4 s; PT: 60.6 ± 3.9 s; and F2 PT file in reciprocating motion: 51.0 ± 3.3 s). Conclusions ProTaper files used in reciprocating motion and PT and TF used in continuous rotary motion were capable of producing centred preparations with no substantial procedural errors.

Diagnostic accuracy of limited-volume cone-beam computed tomography in the detection of periapical bone loss: 360° scans versus 180° scans

AIM To investigate the effect of reducing limited-volume cone-beam computed tomographs arc of rotation from 360° to 180° on the ability to diagnose small, artificially created apical lesions. METHODOLOGY Small, artificial apical bone lesions were prepared with a bur in the apical region of the distal root of ten mandibular first molars, in human dry mandibles. The jaws were scanned in a fixed position with limited-volume CBCT making a 360° and 180° arc of rotation, before and after each periapical lesion had been created. A 4 × 4 cm field of view was used at 90 kV, with a current of 4 mA. Ten examiners blinded to the scan parameters and controls scored the presence/absence of bone lesions. Intra-examiner reliability was determined after 2 weeks, reviewing half the data set. Statistical analyses with paired t-tests determined the diagnostic accuracy of the two modalities (360° vs. 180°) in terms of sensitivity, specificity, receiver operating characteristic area under the curve, positive predictive values and negative predictive values. RESULTS The mean values for sensitivity of the 360° and 180° scans were 0.91 and 0.89, respectively; their mean specificities were 0.73. No significant differences were reflected in the statistical analyses. CONCLUSIONS Both 360° and 180° cone-beam computed tomography scans yielded similar accuracy in the detection of artificial bone lesions. The use of 180° scans might be advisable to reduce the radiation dose to the patient in line with the ICRP guidance to use as low a dosage as reasonably achievable.

External cervical resorption: a three‐dimensional classification

This article describes a novel three-dimensional classification for external cervical resorption (ECR). The European Society of Endodontology and American Association of Endodontists & American Academy of Oral & Maxillofacial Radiology position statements advise that Cone beam computed tomography should be considered for the assessment and/or management of root resorption if it appears to be clinically amenable to treatment following clinical and conventional radiographic examination. The new classification takes into account the ECR lesion height (1: at CEJ level or coronal to the bone crest (supracrestal), 2: extends into the coronal third of the root and apical to the bone crest (subcrestal), 3: extends into the mid-third of the root, 4: extends into the apical third of the root), circumferential spread (A: ≤90° B: ≤180° C: ≤270° D: >270°) and proximity to the root canal (d: lesion confined to dentine, p: probable pulpal involvement), thus classifying ECR in three dimensions. At present, there is no classification to accurately describe ECR. This novel and clinically relevant three-dimensional classification should allow effective and accurate communication of ECR lesions between colleagues. It will also allow the effect of the nature of ECR on the outcome of treatment to be assessed objectively.

External Cervical Resorption: A Comparison of the Diagnostic Efficacy Using 2 Different Cone-beam Computed Tomographic Units and Periapical Radiographs

Introduction: The aim of this study was to compare the diagnostic efficacy of 2 cone‐beam computed tomographic (CBCT) units with parallax periapical (PA) radiographs for the detection and classification of simulated external cervical resorption (ECR) lesions. Methods: Simulated ECR lesions were created on 13 mandibular teeth from 3 human dry mandibles. PA and CBCT scans were taken using 2 different units, Kodak CS9300 (Carestream Health Inc, Rochester, NY) and Morita 3D Accuitomo 80 (J Morita, Kyoto, Japan), before and after the creation of the ECR lesions. The lesions were then classified according to Heithersays classification and their position on the root surface. Sensitivity, specificity, positive predictive values, negative predictive values, and receiver operator characteristic curves as well as the reproducibility of each technique were determined for diagnostic accuracy. Results: The area under the receiver operating characteristic value for diagnostic accuracy for PA radiography and Kodak and Morita CBCT scanners was 0.872, 0.99, and 0.994, respectively. The sensitivity and specificity for both CBCT scanners were significantly better than PA radiography (P < .001). There was no statistical difference between the sensitivity and specificity of the 2 scanners. The percentage of correct diagnoses according to the tooth type was 87.4% for the Kodak scanner, 88.3% for the Morita scanner, and 48.5% for PA radiography.The ECR lesions were correctly identified according to the tooth surface in 87.8% Kodak, 89.1% Morita and 49.4% PA cases. The ECR lesions were correctly classified according to Heithersay classification in 70.5% of Kodak, 69.2% of Morita, and 39.7% of PA cases. Conclusions: This study revealed that both CBCT scanners tested were equally accurate in diagnosing ECR and significantly better than PA radiography. CBCT scans were more likely to correctly categorize ECR according to the Heithersay classification compared with parallax PA radiographs. Highlights:The aim of this study was to compare the diagnostic efficacy of 2 cone‐beam computed tomographic (CBCT) units with parallax periapical radiographs for the detection and classification of simulated external cervical resorption (ECR) lesions.This study revealed that both CBCT scanners tested were equally accurate in diagnosing ECR and significantly better than periapical radiography. CBCT scans were more likely to correctly categorize ECR according to the Heithersay classification compared with parallax periapical radiographs

Graft Materials and Bone Marrow Stromal Cells in Bone Tissue Engineering

Bone augmentation procedures rely on osteogenic/osteoconductive properties of bone graft material (BGM). A further improvement is represented by use of autologous bone marrow stromal cells (BMSC), expanded in vitro and seeded on BGM before implantation in the bone defect. The effect of different BGMs on BMSC osteogenic differentiation was evaluated. BMSC were cultured in vitro in the presence of different BGM (natural, synthetic, and mixed origins). Cellular morphology was analyzed with scanning electron microscopy. The capability of BMSC to differentiate was determined in vitro by alkaline phosphatase gene expression and enzyme activity at different time points (7, 14, and 28 days) and in vivo by ectopic bone formation of implanted tissue constructs in an immunodeficient murine model. BGM supports the cell adhesion and osteogenic differentiation of BMSC developing a useful tool in the bone tissue engineering.

Self-Limiting versus Conventional Caries Removal: A Randomized Clinical Trial

A single-blind randomized controlled clinical trial in patients with deep caries and symptoms of reversible pulpitis compared outcomes from a self-limiting excavation protocol using chemomechanical Carisolv gel/operating microscope (self-limiting) versus selective removal to leathery dentin using rotary burs (control). This was followed by pulp protection with mineral trioxide aggregate (MTA) and restoration with glass ionomer cement and resin composite, all in a single visit. The pulp sensibility and periapical health of teeth were assessed after 12 mo, in addition to the differences in bacterial tissue concentration postexcavation. Apical radiolucencies were assessed using cone beam computed tomography/periapical radiographs (CBCT/PAs) taken at baseline 0 mo (M0) and 12 mo (M12). In total, 101 restorations in 86 patients were placed and paired subsurface, and deep (postexcavation) dentin samples were obtained. DNA was extracted and bacteria-specific 16S ribosomal RNA gene quantitative polymerase chain reaction was performed. No significant difference was found in bacterial copy numbers normalized to mass of dentin (“bacterial tissue concentration”) between the self-limiting (96.3% reduction) and control protocols (97.1%, P = 0.33). The probability of 12-mo success was 4 times (odds ratio [OR] = 4.33; confidence interval [CI], 1.2–15.6; P = 0.025) higher in the self-limiting protocol compared to the control (conventional excavation technique), with pulp survival rates of 73.3% and 90%, respectively (P = 0.049). Molars had a 4 times higher probability of success compared to premolars (OR, 4.17; CI, 1.17–14.9; P = 0.028), and symptom severity did not statistically predict outcome (OR, 0.41; CI, 0.12–13.9, P = 0.153). CBCT detected significantly more periapical (PA) lesions than PA radiographs at the baseline visit (P < 0.001). In conclusion, the self-limiting caries excavation protocol under magnification increased pulp survival rate compared to rotary bur excavation (ClinicalTrials.gov NCT03071588).

External cervical resorption: part 2 – management

Effective management of external cervical resorption (ECR) depends on accurate assessment of the true nature and accessibility of ECR; this has been discussed in part 1 of this 2 part article. This aim of this article was firstly, to review the literature in relation to the management of ECR and secondly, based on the available evidence, describe different strategies for the management of ECR. In cases where ECR is supracrestal, superficial and with limited circumferential spread, a surgical repair without root canal treatment is the preferred approach. With more extensive ECR lesions, vital pulp therapy or root canal treatment may also be indicated. Internal repair is indicated where there is limited resorptive damage to the external aspect of the tooth and/or where an external (surgical) approach is not possible due to the inaccessible nature of subcrestal ECR. In these cases, root canal treatment will also need to be carried out. Intentional reimplantation is indicated in cases where a surgical or internal approach is not practical. An atraumatic extraction technique and short extraoral period followed by 2-week splinting are important prognostic factors. Periodic reviews may be indicated in cases where active management is not pragmatic. Finally, extraction of the affected tooth may be the only option in untreatable cases where there are aesthetic, functional and/or symptomatic issues.

Bacterial Contamination of Endodontic Materials before and after Clinical Storage

Introduction The aim of this study was to evaluate the bacterial contamination in endodontic consumables (gutta‐percha points, rubber dams, paper mixing pads, caulking agents, and endodontic instrument sponges [EISs]) before and after clinical use and storage. Methods Materials were randomly sampled in triplicates at 3 time points (t0, at package opening; t1, at 7 days; and t2, at 14 days) during their clinical usage. The gutta‐percha points and caulking agent (25 mg) were added to 1 mL phosphate‐buffered saline (PBS). The rubber dam, paper mixing pad, and EIS were added to 25 mL PBS. After vortexing, centrifuging, and removing the supernatant, the pellet was resuspended in 1 mL PBS, plated on fastidious anaerobic agar, and incubated aerobically and anaerobically. The grown colonies were identified by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF MS). The total bacterial load was calculated in the remaining volume (800 &mgr;L) from each sample by quantitative polymerase chain reaction after DNA extraction. Results All tested materials showed a varied number of contaminated samples at the 3 time points (except EIS at t0) using MALDI‐TOF MS. The most isolated genera were Propionibacterium (42%) and Staphylococcus (32%). By using non–culture‐based approaches, all tested materials at the 3 time points (except gutta‐percha at t0 and the caulking agent at t0, t1, and t2) carried bacterial DNA. Conclusions The majority of the tested materials harbored bacteria in their samples before and after clinical storage. Nosocomial infection derived from commonly used consumables could have an impact on the outcome of endodontic treatment. HighlightsConsumables commonly used in endodontics are often in nonsterile packaging.Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectroscopy is a valid technique to identify the contaminants of endodontic materials.Clinical storage can induce environmental contamination.The presence of bacteria in endodontic materials may induce nosocomial infection.Nosocomial infections may induce failure in de novo root canal treatments