doi:10.1007/s13398-014-0179-1engLozano Rojo, ÁlvaroVigara Benito, RubénOn the subadditivity of Montesinos complexity of closed orientable 3-manifoldsART-2015-89963A filling Dehn sphere S in a closed 3-manifold M is a sphere transversely immersed in M that defines a cell decomposition of M . Every closed 3-manifold has a filling Dehn sphere Montesinos-Amilibia (Contribuciones Matemáticas: Homenaje a Joaquín Arregui Fernández, Editorial Complutense, pp 239–247, 2000). The Montesinos complexity of a 3 -manifold M is defined as the minimal number of triple points among all the filling Dehn spheres of M . A sharp upper bound for the Montesinos complexity of the connected sum of two 3-manifolds is given.2015http://zaguan.unizar.es/record/13126510.1007/s13398-014-0179-1http://zaguan.unizar.es/record/131265oai:zaguan.unizar.es:131265Revista de la Real Academia de Ciencias Exactas, Fisicas y Naturales - Serie A: Matematicas 109, 2 (2015), 267-279All rights reservedhttp://www.europeana.eu/rights/rr-f/info:eu-repo/semantics/openAccess