Stefano Pagano

Compressive and flexural behaviour of fibre reinforced endodontic posts

OBJECTIVES The aim of this study was to investigate the mechanical properties of five types of fibre-reinforced composite (FRC) posts and compare them with traditional metal post. METHODS Five FRC posts and a metallic post having different geometry and type of fibre (glass, carbon or quartz fibre) were loaded to failure in compression and bending. The transverse sections of FRC posts were observed using SEM to evaluate the fracture mode and the percentage of fibres (compared with burn-off test). Densities and voids content were also evaluated. RESULTS Mechanical results were subjected to a one-way ANOVA and Tukey test (p<0.05). In compression, quartz fibre posts exhibited the greater maximum load and ultimate strength, carbon fibre posts showed a poor compressive behaviour. All posts had similar compressive moduli. Carbon posts showed the highest flexural properties (p<0.0001) while glass posts the greater maximum load. The fracture load values correlated to the diameters of posts showed a parabolic behaviour. The flexural strengths of all posts were four and seven times higher than dentine. The elastic moduli of almost all posts were similar to dentine. The compressive strengths were lower than flexural strengths. The fibre diameters ranged from 5.2 to 26 μm, the volume percentage of fibres was about 64%. The content of voids of some posts lower their mechanical behaviour. CONCLUSIONS Compressive properties of FRC posts were lower than in bending. The flexural properties of FRC posts were higher than the metal post and similar to dentine. The mechanical behaviour is influenced by voids.

Methamphetamine abuse and "meth mouth" in Europe

With easy chemical synthesis from its precursor, methamphetamine (MA) is now widespread in many countries. The abuse of methamphetamine is associated with several negative effects on health, because MA is a neurotoxin and a dangerous central nervous system stimulant. It changes levels of neurotransmitters in the brain, releasing dopamine and inhibiting nor epinephrine uptake which increases sympathetic nervous system activity and can lead to cardiac arrhythmia, hypertension and tachypnea. The consequences of MA abuse are clearly manifested in oral diseases (like “meth mouth”) which is characterised by extensive caries, teeth grinding with ensuing dental wear and trismus. The present review was designed to fill the gap in knowledge about methamphetamine abuse in the European Union (EU) and to illustrate the main clinical effects of prolonged use. After describing the pharmacology and systemic effects of methamphetamine and concentrating on its effects on the mouth, the present review compares the epidemiology and incidence of abuse in the world, particularly the USA and the EU. Key words:Methamphetamine, “Meth mouth”, drug abuse, oral health.

Nanomaterials for Tissue Engineering In Dentistry

The tissue engineering (TE) of dental oral tissue is facing significant changes in clinical treatments in dentistry. TE is based on a stem cell, signaling molecule, and scaffold triad that must be known and calibrated with attention to specific sectors in dentistry. This review article shows a summary of micro- and nanomorphological characteristics of dental tissues, of stem cells available in the oral region, of signaling molecules usable in TE, and of scaffolds available to guide partial or total reconstruction of hard, soft, periodontal, and bone tissues. Some scaffoldless techniques used in TE are also presented. Then actual and future roles of nanotechnologies about TE in dentistry are presented.

Effect of fibre posts, bone losses and fibre content on the biomechanical behaviour of endodontically treated teeth: 3D-finite element analysis

The aim of this work was to evaluate the stress distribution inside endodontically treated teeth restored with different posts (glass fibre, carbon fibre and steel posts) under different loading conditions by using a 3D-finite element analysis. The effect of masticatory and impact forces on teeth with different degrees of bone loss was analysed. The model consists of: dentine, post, cement, gutta-percha, core and crown. Four simulations were conducted with two static forces (170N horizontal and 100N oblique) and two sections constrained: 1mm (alveolar bone position in a normal periodontium) and 6mm (middle of root) below the crown. Von Mises and the principal stresses were evaluated and analysed with a 3-way ANOVA and Tukey test (α=0.05) and the effect of fibre percentage analysed. Significant differences were found among the stress values for all conditions (p<0.05). Impact load was always responsible for the most critical situation especially when the bone loss was more evident. The system with steel posts showed the highest principal stresses at the post-cement interface with horizontal load and top constraints (compressive stress of 121MPa and tensile stress of 115MPa). The use of glass posts provides a more homogeneous behaviour of the system with lower stresses. Higher fibre percentages gave higher stress in the posts. Moreover, larger bone losses are responsible for important increase in stress. Thus, this work demonstrated that periodontal disease has an important role in the success of tooth restoration after endodontic therapy, influencing the choice of post material and depth.

Sonic and ultrasonic oscillating devices for the management of pain and dental fear in children or adolescents that require caries removal: a systematic review

Objectives To evaluate the effectiveness and degree of acceptance by children and adolescents of the use of oscillating tips compared with rotating drills. Design Systematic review. Data sources PubMed, the Cochrane Central Register of Controlled Trials (CENTRAL), the Cochrane Library and Web of Science (October 2017). Eligibility criteria Controlled randomised or non-randomised trials that evaluated sonic and ultrasonic oscillating devices versus rotating drill. Data extraction Eligible studies were selected and data extracted independently by two reviewers. Risk of bias was assessed using the Cochrane Method. Results Two controlled clinical trials comprising 123 children aged 2–12 years old were identified. Both trials were at high risk of selection bias and unclear risk of detection bias. In one trial, pain due to the use of oscillating drill resulted lower than employing rotating drill (Verbal Hochman Scale: RR 0.64 (95% CI 0.41 to 1.00); Visual Facial Expression Scale: RR 0.64 (95% CI 0.44 to 0.94)). In another study, compared with traditional drill ultrasonic tip was associated with a lower level of patient’s discomfort (RR 0.40 (95% CI 0.20 to 0.79)) but not with dental anxiety (RR 1.29 (95% CI 0.97 to 1.71)). The effectiveness of the removal of caries as well as fillings durability were only considered in one study, but no statistically significant differences were found between the two interventions. Conclusions The evidence based on two low-quality studies was insufficient to conclude that the use of oscillating tips for the management of pain and dental fear in children or adolescents compared with rotating drills was more effective.

Scanning Electron Microscopy Evaluation of Dental Root Resorption Associated With Granuloma.

The inflammatory resorption of dental root apex (i.e., the process of removal of cementum and/or dentine through the activity of resorbing cells) may show different configurations and damage the apical root structure. As knowing the morphology of resorption areas of human teeth is essential for the success of endodontic treatments, we investigated the apical resorption by scanning electron microscopy, focusing on roots with granulomas. A total of 30 teeth (with penetrating carious lesions and chronic periapical lesions) were examined, the apical third of the roots were removed and analyzed to estimate periforaminal and foraminal resorption, shape and morphology of foramen resorption, centering of the periforaminal resorption area, and diameters of each apical foramen. Periforaminal resorption was present in all samples, whereas foraminal resorption was present in 92% of cases (mainly funnel shaped). Lacunae were observed in the foraminal resorption area with an average diameter of 35±14 μm. The major and minor diameters of the foramina in teeth with resorption were 443 and 313 μm, respectively (higher than in healthy teeth). This result indicates an expansion of the apical diameters caused by the pathology, which could encourage a different clinical instrumentation for these teeth.

Biological, thermal and mechanical characterization of modified glass ionomer cements: The role of nanohydroxyapatite, ciprofloxacin and zinc l-carnosine

The study evaluated the effects of 4 wt% nanohydroxyapatite (HA), 6 wt% zinc l-carnosine (MDA) and 1.5 wt% Ciprofloxacin (AB) on the mechanical, thermal and biological properties of glass ionomer cements (GIC). Filler and additive concentrations were selected after a previous study had tested single components and different percentages. Specimens included five silicon molds of each GIC cement for all tests. They were stored at room temperature for 24 h from specimen collection to analysis. Mechanical tests, calorimetric analysis, morphological investigation, antibacterial and cell viability assays were conducted. One-way analysis of variance (ANOVA) was used for data analysis with significance set at p < 0.05. Adding HA, MDA and AB to GICs modified their thermal, mechanical and microbiological properties. Polymerization increased. A slight decrease in the compressive strength of modified GICs was observed in dry condition (p < 0.05). Cement extracts affected cell viability in relation to extract dilution. Mechanical behavior improved in modified glass ionomer cements, especially with the powder formulated antibiotic. Overall cytotoxicity was reduced. Therefore adding nanohydroxyapatite, antibiotic and a mucosal defensive agent to conventional glass ionomer cement in special need patients could improve the clinical, preventive and therapeutic performance of the cements, without altering their mechanical properties.

I nuovi anticoagulanti orali e la loro gestione nella pratica clinica odontoiatrica

Riassunto Obiettivi Scopo dello studio e valutare le implicazioni dei nuovi anticoagulanti orali (Novel Oral Anticoagulants, NOA) nelle terapie odontoiatriche, alla luce della recente letteratura. Materiali e metodi E stata eseguita una valutazione comparativa degli studi condotti negli ultimi cinque anni per confrontare gli effetti dei NOA rispetto agli anticoagulanti tradizionali nelle procedure odontoiatriche. Risultati Rapidita d’azione, minori interazioni farmacologiche ed esigenza di monitoraggio non continuo renderebbero i NOA vantaggiosi rispetto agli anticoagulanti tradizionali. Ulteriori indagini sono tuttavia necessarie. Conclusioni La letteratura conferma la possibilita di mantenere la terapia con i NOA durante le principali procedure odontoiatriche. Importante e definire specifici criteri clinici.

Recenti acquisizioni in tema di irrigazione canalare: analisi al microscopio elettronico a scansione.

Riassunto Obiettivi Il presente lavoro intende valutare, utilizzando il microscopio elettronico a scansione (Field Emission Scanning Electron Microscope, FESEM), le proprieta detergenti di quattro diversi irriganti canalari in elementi dentari estratti. Materiali e metodi Venti elementi dentari monoradicolati, estratti per motivi parodontali, sono stati sottoposti ad alesaggio biomeccanico e irrigazione canalare con quattro diverse soluzioni testate, ovvero: irrigante 1, ipoclorito di sodio (NaOCl) al 5%; irrigante 2, cetrimide + clorexidina (Cetrexidin, Gaba Vebas, Roma); irrigante 3, acido etilendiamminotetracetico (EDTA); irrigante 4, doxiciclina + acido citrico + glicole di polipropilene (Tetraclean, Ogna Laboratori Farmaceutici, Muggio, MB). Tutti i campioni, dopo essere stati opportunamente disidratati e metallizzati, sono stati osservati al FESEM con catodo a emissione di campo (Supra™, Carl Zeiss Microscopy GmbH, Jena, DE) in modo da valutare il grado di detersione ottenuto in corrispondenza del terzo medio e apicale del canale. Risultati I risultati dello studio hanno mostrato un eccellente potere detergente, a livello del terzo medio del canale, da parte dell’irrigante 2, meno efficace invece a livello del terzo apicale. Buona, anche se inferiore rispetto a quella dell’irrigante 2, e risultata la capacita detergente dell’irrigante 1 e dell’irrigante 3 in corrispondenza del terzo medio del canale; limitata anche per loro la rimozione di smear-layer in corrispondenza del terzo apicale. L’irrigante 4 non ha evidenziato una buona capacita detergente ne a livello del terzo medio ne a livello del terzo apicale del canale. Conclusioni La procedura di irrigazione sembra svolgere un ruolo chiave nel successo della terapia canalare; tuttavia, durante un trattamento endodontico non e possibile utilizzare un’unica soluzione irrigante bensi diverse sostanze contemporaneamente, ciascuna con un ruolo specifico nella detersione dell’endodonto.