diff --git a/VolTriZmapGraphics.cpp b/VolTriZmapGraphics.cpp
index 39ac2b0..a2e95a4 100644
--- a/VolTriZmapGraphics.cpp
+++ b/VolTriZmapGraphics.cpp
@@ -712,7 +712,7 @@ VolZmap::ExtMarchingCubes( int nBlock, TRIA3DLIST& lstTria, TriHolder& triHold)
   // Ciclo su tutti i voxel dello Zmap
    for ( int i = nLimits[0] ; i < nLimits[1] ; ++ i) {
       for ( int j = nLimits[2] ; j < nLimits[3] ; ++ j) {
-         for ( int k = nLimits[4] ; k < nLimits[5] ; ++ k) { 
+         for ( int k = nLimits[4] ; k < nLimits[5] ; ++ k) {      
         
            // Riconoscimento dei voxel di frontiera
             int nVoxIndexes[3] = { i, j, k} ;
@@ -1720,6 +1720,10 @@ VolZmap::ExtMarchingCubes( int nBlock, TRIA3DLIST& lstTria, TriHolder& triHold)
                                    // vettore nello spazio genenrato dai due non appartenenti alla coppia
                                     Vector3d vtAv23 = 0.5 * ( CompoVert[nCompCount - 1][nCoupleIndex[2]].vtNorm + 
                                                               CompoVert[nCompCount - 1][nCoupleIndex[3]].vtNorm) ;
+
+                                    vtAv01.Normalize() ;
+                                    vtAv23.Normalize() ;
+                                    double dDAvAV = vtAv01 * vtAv23 ;
                                    // se angolo grande si esegue std MC
                                     if ( abs( vtAv01 * vtAv23) < EPS_SMALL) {
                                        for ( int ni = 0 ; ni < 4 ; ++ ni) {
@@ -1731,6 +1735,22 @@ VolZmap::ExtMarchingCubes( int nBlock, TRIA3DLIST& lstTria, TriHolder& triHold)
                                           }
                                        }
                                     }
+                                    else {
+                                            
+                                       double dD23 = CompoVert[nCompCount - 1][nCoupleIndex[2]].vtNorm * 
+                                                     CompoVert[nCompCount - 1][nCoupleIndex[3]].vtNorm ;
+                                       if ( dD23 > 0.7  &&  dDAvAV < 0.7) {
+                                       
+                                          for ( int ni = 0 ; ni < 4 ; ++ ni) {
+                                             int nj = ni == 3 ? 0 : ni + 1 ;
+                                             if ( triContainer[ni].GetN() * CompoVert[nCompCount - 1][ni].vtNorm < - 0.9 && 
+                                                  triContainer[ni].GetN() * CompoVert[nCompCount - 1][nj].vtNorm < - 0.9) {
+                                                bDangerInversion = true ;
+                                                break ;
+                                             }
+                                          }
+                                       }
+                                    }
                                  }
                               }
                            }