diff --git a/VolZmapGraphics.cpp b/VolZmapGraphics.cpp
index e6c130c..cc1d006 100644
--- a/VolZmapGraphics.cpp
+++ b/VolZmapGraphics.cpp
@@ -1993,8 +1993,30 @@ VolZmap::ExtMarchingCubes( int nBlock, VoxelContainer& vVox) const
                                     ptSol += ( dNewU2 + EPS_SMALL * ( dNewU1 - dNewU2)) * vtNullSpace ;
                                  }
                               }
-                              else 
-                                 bExtConfirmed = nVertComp[nComp] < 6 ? false : true ;
+                              else {
+                           
+                                 if ( nVertComp[nComp] == 5) {                                    
+                                    double dDotAvarage = 0.;
+                                    for (int m = 0; m < nVertComp[nComp] - 1; ++m) {
+                                       for (int l = m + 1 ; l < nVertComp[nComp]; ++l) {
+                                          dDotAvarage += CompoVert[nComp][m].vtVec * CompoVert[nComp][l].vtVec;
+                                       }
+                                    }
+                                    dDotAvarage /= (( nVertComp[nComp] * ( nVertComp[nComp] - 1)) / 2) ;
+                                    
+                                    int nNumPar = 0 ;
+                                    for ( int m = 0 ; m < nVertComp[nComp] - 1 ; ++ m) {
+                                       for ( int l = m + 1 ; l < nVertComp[nComp] ; ++ l) {
+                                          if ( AreSameVectorExact( CompoVert[nComp][m].vtVec, CompoVert[nComp][l].vtVec))
+                                             ++ nNumPar ;
+                                       }
+                                    }
+                                    bExtConfirmed = nNumPar == 3 ;
+                                 }
+                                 else if (nVertComp[nComp] < 5) {
+                                    bExtConfirmed = false ;
+                                 }
+                              }
                            }
                         }
                      }