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Calcium silicate-based cements in endodontic management of external root resorption

Objective: External root resorption is a pathologic process involving the permanent dentition, mainly due to the injury of root surface. Avulsion and reimplantation of a permanent tooth are strictly related to the occurrence and progression of tooth tissue loss and external root resorption. Therefore, the aim of the present study was to endodontically treated a traumatized tooth presenting root resorption using calcium silicate-based cements.

Materials and Methods: Two immature permanent teeth, 11 and 21, were subjected to trauma and reported uncomplicated crown fracture and avulsion and complicated crown fracture, respectively. Both elements were diagnosed with necrotic pulp and tooth 11 showed early external root resorption due to reimplantation. Endodontic treatment and root closure with apical plug using a calcium-silicate-based cement, namely mineral trioxide aggregate (MTA), was obtained in both dental elements.

Results: After 6 months, root resorption seemed to be arrested. Twenty-four months after trauma the clinical results were stable; however, clinical and radiographical signs and symptoms of ankylosis involving tooth 11 could be appreciated.

Conclusions: Apical plug obtained using a bioactive calcium silicate-based cement seemed to reduce the resorption rate when compared to the early stages, allowing a better clinical prognosis over time. Further studies with a larger sample size and a longer follow-up period are needed to establish the potential of calcium silicate-based cement to promote the deposition of a mineralized tissue and to contrast the progression of resorption process.

  • Open access
  • 139 Reads
Quantification of Losses in a Photovoltaic System: A Review

In this paper, we characterized and reviewed the emergence of fundamental and extended losses that limit the efficiency of the photovoltaic (PV) system. Although in a practical environment, there is an upper theoretical bound to the power conversion efficiency of the solar cell i.e. Schockly Queisser limit yet the consideration of inevitable losses in a whole PV system is worth imperative to optimally harvest the solar energy. In this regard, this study quantifies the losses from a PV cell level to the whole PV system. It was perceived that reported losses on a PV cell level including the low energy bandgap, thermalization, recombination (surface and bulk recombination), optical absorption, space charge region, finite thickness, metal contact loss, cutting techniques mainly constrained the power conversion efficiency of the solar cell. A step ahead, the detailed PV array losses were classified as mismatch power loss, dust accumulation losses, temperature effects, material quality loss, and ohmic loss of wiring. The unavoidable system losses were quantified as inverter losses, maximum power point tracking losses, battery losses, and polarization losses. The study also provides insights on potential approaches to combat these losses and can become a useful guide in better visualization of the overall phenomenology of a PV System.