Cognitive Access Policies under a Primary ARQ process via Forward-Backward Interference Cancellation

This paper introduces a novel technique for access by a cognitive Secondary User (SU) using best-effort transmission to a spectrum with an incumbent Primary User (PU), which uses Type-I Hybrid ARQ. The technique leverages the primary ARQ protocol to perform Interference Cancellation (IC) at the SU receiver (SUrx). Two IC mechanisms that work in concert are introduced: Forward IC, where SUrx, after decoding the PU message, cancels its interference in the (possible) following PU retransmissions of the same message, to improve the SU throughput; Backward IC, where SUrx performs IC on previous SU transmissions, whose decoding failed due to severe PU interference. Secondary access policies are designed that determine the secondary access probability in each state of the network so as to maximize the average long-term SU throughput by opportunistically leveraging IC, while causing bounded average long-term PU throughput degradation and SU power expenditure. It is proved that the optimal policy prescribes that the SU prioritizes its access in the states where SUrx knows the PU message, thus enabling IC. An algorithm is provided to optimally allocate additional secondary access opportunities in the states where the PU message is unknown. Numerical results are shown to assess the throughput gain provided by the proposed techniques.Comment: 16 pages, 11 figures, 2 table

Energy Harvesting Wireless Communications: A Review of Recent Advances

This article summarizes recent contributions in the broad area of energy harvesting wireless communications. In particular, we provide the current state of the art for wireless networks composed of energy harvesting nodes, starting from the information-theoretic performance limits to transmission scheduling policies and resource allocation, medium access and networking issues. The emerging related area of energy transfer for self-sustaining energy harvesting wireless networks is considered in detail covering both energy cooperation aspects and simultaneous energy and information transfer. Various potential models with energy harvesting nodes at different network scales are reviewed as well as models for energy consumption at the nodes.Comment: To appear in the IEEE Journal of Selected Areas in Communications (Special Issue: Wireless Communications Powered by Energy Harvesting and Wireless Energy Transfer

Modern technologies in Endodontics

AbstractAimIn Endodontics, a complete chemo-mechanical cleansing of the root canal system is essential to achieving success, which is gained through adequate tridimensional obturation of the endodontic space.Materials and methodsToday, thanks to modern technologies as Operative Microscope, ultrasonic tips, M-Wire Files, devices to activate irrigation and tridimensional obturation performed with thermo plasticized gutta-percha, satisfactory results can be obtained.ResultsThis study shows all the technologies that are available today to increase the chemo-mechanical cleansing and obturation of the entire and complicated endodontic system.ConclusionsThe positive results highlighted by these clinical cases demonstrate how the use of modern technologies are essential to avoid iatrogenic injury, and guarantee, on the other hand, safe and reproducible results

Modern technologies in Endodontics

Abstract Aim In Endodontics, a complete chemo-mechanical cleansing of the root canal system is essential to achieving success, which is gained through adequate tridimensional obturation of the endodontic space. Materials and methods Today, thanks to modern technologies as Operative Microscope, ultrasonic tips, M-Wire Files, devices to activate irrigation and tridimensional obturation performed with thermo plasticized gutta-percha, satisfactory results can be obtained. Results This study shows all the technologies that are available today to increase the chemo-mechanical cleansing and obturation of the entire and complicated endodontic system. Conclusions The positive results highlighted by these clinical cases demonstrate how the use of modern technologies are essential to avoid iatrogenic injury, and guarantee, on the other hand, safe and reproducible results

IG-File: un nuovo strumento per l’ottimizzazione della detersione canalare e per la misurazione del diametro apicale

RiassuntoObiettivoLo scopo del lavoro è la descrizione di un nuovo tipo di file, con design innovativo, ideato sia per l’attivazione sonica degli irriganti durante la fase di detersione sia per la misurazione del diametro apicale.Materiali e metodiPer valutare l’efficacia delle Sonic-Tip è stato condotto un test alla MicroCT. È stata selezionata una radice di un premolare superiore che presentava canali laterali; dopo la preparazione chemio-meccanica del canale radicolare sono stati effettuati due lavaggi endocanalari con una soluzione radiopaca: il primo lavaggio è avvenuto erogando passivamente la soluzione radiopaca nel canale con un ago di piccolo calibro a 2mm dalla lunghezza di lavoro; il secondo lavaggio è avvenuto erogando passivamente la soluzione radiopaca all’interno del canale a 2mm dalla lunghezza di lavoro, la quale poi è stata attivata con la Sonic-Tip numero 20. Dopo ogni lavaggio la radice è stata osservata alla MicroCT.RisultatiI risultati dimostrano come sia stato possibile, grazie all’attivazione sonica dell’irrigante all’interno dello spazio endodontico, far penetrare la soluzione nei canali laterali.Discussione e conclusioniDetersione, sagomatura e otturazione tridimensionale dello spazio endodontico sono le tre fasi principali della terapia endodontica. La detersione è raggiunta congiuntamente tramite l’azione meccanica degli strumenti e l’azione chimica delle soluzioni irriganti. Quindi, le soluzioni irriganti devono avere azioni differenziate: dovrebbero rimuovere il substrato organico, avere un effetto battericida e infine rimuovere lo strato di materiale inorganico prodotto dalla limatura degli strumenti (smear layer). A tutt’oggi non vi sono soluzioni irriganti che ottengono tutti e tre questi risultati. Da molti studi si evince come l’attivazione sonica o ultrasonica degli irriganti, all’interno di canali radicolari ben sagomati, assuma un ruolo strategico nella detersione di tutte le complessità dello spazio endodontico. Altra fase fondamentale della terapia endodontica è l’otturazione tridimensionale del sistema dei canali radicolari con guttaperca termoplasticizzata. Prima di procedere alla fase di otturazione è fondamentale conoscere il diametro apicale del canale preparato, in modo da scegliere i materiali da otturazione più idonei (coni di guttaperca, portatori di calore, otturatori thermafil), ottimizzare le forze di condensazione ed evitare fenomeni di overfilling.SummaryObjectiveThe purpose of this article is to describe a new file featuring a unique design created for both the sonic activation of irrigants during cleaning and measuring the apical diameter.Materials and methodsTo assess the effectiveness of Sonic-Tips, a MicroCT scan was performed on an upper premolar root with lateral canals. After a chemio-mechanical (cleaning and shaping process) preparation of the root canal, the same root canal was irrigated twice with a radiopaque solution. The first irrigation was done by injecting the radiopaque solution passively in the root canal through a small gauge needle, 2mm from working length. The second irrigation again was done by delivering the radiopaque solution passively in the root canal through a small gauge needle, 2mm from working length, but in the latter case a Sonic-Tip number 20 was activated. After each cleaning (irrigation) the root was observed under MicroCT scan.ResultsThe results demonstrate how Sonic-Tips enabled flushing and made it possible for the irrigant to penetrate into lateral canals.Discussion and conclusionsCleaning, shaping and three-dimensional obturation are the three main phases of the endodontic treatement. The goal of proper cleaning of a complex root canal is not easily achieved. From previous studies, it is clearly evident how “Sonic and Ultrasonic activation of irrigants” plays a strategic role in the cleaning of a well-shaped complex root canal. Another key stage of the endodontic treatment is the “three-dimensional filling” of root canals with thermoplastic guttapercha cones. Before the filling phase, it is essential to know the accurate apical diameter of the canal, in order to choose the suitable filling material (gutta percha points, Thermafil obturators or heat carriers), followed by applying optimal condensation pressure in order to prevent overfilling

Nonsurgical management of complex endodontic cases with several periapical lesions: a case series

Abstract Aim Today, thanks to modern technologies as operative microscope, ultrasonic tips, devices to activate irrigation and tridimensional obturation performed with thermo plasticized gutta-percha, excellent results could be obtained. Materials and methods In this study, we present 5 patients with the presence of periapical lesions in molars and incisors with history of pain. Modern endodontic technologies were used. The rationale of using these technologies was to obtain a chemo-mechanical cleansing and obturation of the entire endodontic system and to gain the lesion resolution with a non-surgical approach. Results A success rate of 100% was obtained. Radiographs and clinical examinations were done until 10 years. All the cases highlighted the success achieved in the short and long term through the complete resolution of the lesions and therefore the reconstitution of the lamina dura. Conclusions The positive results highlighted by these clinical cases demonstrate how the use of modern technologies is essential to avoid iatrogenic damage and to gain safe and reproducible results

The activation of irrigation solutions in Endodontics: a perfected technique

AbstractAimIn endodontics a complete chemo mechanical cleansing of the complex root canal system is essential in order to achieve a theraupetic success.MethodologySodium hypoclorite due to its antimicrobial and proteolytic characteristic, is an efficient endodontic irrigant and it is the most commonly used.The following article introduces a refined technique in order to increase the degree of cleansing during endodontic treatment.The technique involves intracanal heating of the irrigants through a heat source.ResultsThe described technique is able to enhance simply and considerably the use of sodium hypochlorite, making it easily accessible even to generic operators.ConclusionsTo confirm the validity of this improved technique, further research and scientific studies are needed, although at the clinical level, the results by using it are very satisfactory

Cyst-like periapical lesion healing in an orthodontic patient: A case report with five-year follow-up

Abstract Aim To report the orthodontic movement of two central incisors through the healing site of a maxillary cyst-like lesion of endodontic origin after nonsurgical treatment. Case summary This report shows the treatment of a 18-year old patient, male, with a Class II division 2 malocclusion. He came to our attention seeking for orthodontic treatment. Radiographic examinations revealed a large cyst-like lesion in the maxillary anterior area, extending from the mesial surface of tooth 12 to the distal surface of tooth 21. The two upper incisors were nonresponsive to pulp sensitivity tests. Endodontic treatment was performed first. One week after root canal treatment had been completed with gutta-percha fillings, orthodontic treatment was started while the bone lesion healing was still underway. At the end of the orthodontic treatment, incisor retroclination was corrected, periapical lesion healing was completed and there were no signs of root resorption. The five-year follow-up revealed that occlusal relationship and dental alignment were kept stable and excellent radiographic resolution of the periapical lesion was obtained

The Efficacy of Selected Sodium Hypochlorite Heating Methods for Increasing and Maintaining Its Intracanal Temperature—An Ex Vivo Study

Background: Enhancement of the temperature of sodium hypochlorite (NaOCl) solution would increase its cleaning potential and decontamination of the root canal system. Therefore, the aim of the present in vitro investigation was to compare the efficacy of different methods of NaOCl heating by evaluating the temperature profiles developed at different levels of the root canal system. Methods: Five thermocouples were applied at different levels of the root canal system of extracted human premolars. NaOCl solution was heated according to two methods: extraoral heating (50 °C, 60 °C, and 70 °C) using a magnetic hotplate heater and intracanal heating by F-06, XF-30/04, and ML-12 pluggers at 100 °C, 150 °C, and 180 °C. Results: The extraoral heating method was ineffective to produce a significant temperature increase at the root apex. Comparable results were obtained using the intracanal heating method through the ML-12 plugger that showed slightly better results only when set at 180 °C. On the other hand, negligible differences were observed in terms of temperature maintenance at several levels of the root between the F-06 and XF-30/04 pluggers, even though the time intervals were higher in case of XF-30/04. Conclusions: The intracanal heating method provided a better temperature persistence in the middle third of the root canal system. Conversely, extraoral heating was ineffective to produce a significant temperature increase at the apex of the root. Comparable results were obtained even using the ML-12 plugger

Temperature Profiles Along the Root with Gutta-percha Warmed through Different Heat Sources

To evaluate temperature profiles developing in the root during warm compaction of gutta-percha with the heat sources System B and System MB Obtura (Analityc Technology, Redmond, WA, USA). Thirty extracted human incisor teeth were used. Root canals were cleaned and shaped by means of Protaper rotary files (Dentsply-Maillefer, Belgium), and imaging was performed by micro-CT (Skyscan 1072, Aartselaar, Belgium)