The move comes after the fair lost a number of high-profile traditional dealers over the past few years.
In the last year alone, Hotspur, Jeremy and Norman Adams have all ceased trading entirely, while Johnny Van Haeften and Colnaghi/Bernheimer, who have both told ATG they remain fans of Grosvenor House, are devoting their attentions to Master Paintings Week this year.
Ms Vaissiere said the organisers were "incredibly sad" to lose them and thanked them for their contribution over the decades, but added: "Their departure, however, has given us the opportunity to invite a new generation of dealers to join the fair. It has also enabled us to include new disciplines, which were not previously offered, and which we feel we ought to be offering today's collectors."
And she added that the 75th anniversary was an "appropriate time to look back and celebrate the past but also a time to look forward and plan for the future".
"We aim to create an event that serves both the dealing and collecting communities of the 21st century, just as the original fair served those communities back in the 1930s," she said.
"In planning the future, our guiding principle is to try and achieve excellence in everything that we do. We are very mindful that when the fair was first launched in 1934, it was a ground-breaking event that created the blueprint for all subsequent art and antiques fairs."
The new blueprint includes more than 20 fresh faces dealing in a wide range of disciplines to add to the established roster of blue-chip names such as Agnew's and Apter-Fredericks.
But Ms Vaissiere said that, despite the initiative, none of this was new. "Over the past decade, there have been many changes, and new disciplines have come to the fore as demand has grown. Modern British painting and sculpture, for example, has become one of the great strengths of the fair in recent years. This is natural progression and the market at work."
She said she was "thrilled" to be welcoming so many young, new dealers in the fair's 75th anniversary year. "The pioneering spirit of Grosvenor House is alive and well," she told ATG.