In a match filled with twists and turns, the outcome hung in the balance until Santer smacked a six in the final over to get New Zealand home with four balls to spare.
Domination fluctuated throughout the match but when Ben Stokes celebrated his return to international cricket with the crucial wicket of Tom Latham, it appeared to put England in charge.
However, Santner's 45 off 27 balls swung the game back in New Zealand's favour as they chased down England's 284 for eight.
Taylor, with his 18th century, and Latham clawed the home side back into the game with a 178-run stand for the fourth wicket before Stokes stepped up to remove Latham for 79 and New Zealand were 205 for four in the 40th over.
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Latham's dismissal sparked a middle-order collapse with Henry Nicholls out for a duck and Colin de Grandhomme gone for two as three wickets fell for 10 runs.
As he started to run out of partners, Taylor tried to up the pace to get New Zealand home but with 25 balls remaining and New Zealand needing a further 45 runs, he was stumped on 113.
Stokes, returning for his first international since a nightclub incident five months ago, had an undistinguished turn at bat after New Zealand won the toss and elected to bowl.
The all-rounder lasted 22 balls and was gone for 12 while the foundation of the England innings was laid by Root, with 71 off 75 deliveries and Buttler who belted 79 off 65 before he was run out off the penultimate ball.
England were looking at a score of more than 300 until tight New Zealand bowling restricted them to just 31 runs between the 42nd and 48th overs.
Kane Williamson only managed eight off 23 balls and Martin Guptill went for 13.
Stokes, discarded by England for five months after a nightclub incident, had an economical four overs in his first bowling spell that only cost 15 runs.
When he was recalled with Taylor and Latham in full flight and New Zealand 187 for three, he went for 11 in his first over before having Latham caught by Root at mid-on.