Hughes (…) also did Roberto Firmino’s teeth. He says the Brazilian former Liverpool player pointed to a space beyond the whitest end of a porcelain colour chart and asked for “maximo”.

This article I stumbled across in the Guardian includes some quotes from the dentist that did Klopp's and Firmino's teeth:

"Robbie Hughes, a dentist and the principal director of Dental Excellence UK, a clinic in Liverpool that has become popular with Premier League footballers (he’s responsible for ex-Liverpool manager Jürgen Klopp’s dazzling smile), says veneers for 20 teeth cost from about £7,000 using composites to £20,000 for porcelain veneers. His patients tend to be aged 20 to 40, and 40% are men.

Demand has increased for ever-whiter veneers as patients want to show off teeth that are obviously the result of expensive work. Sood says this has further skewed perception of what “perfect” teeth should look like. Hughes, who has noticed a recent trend for more natural shades, also did Roberto Firmino’s teeth. He says the Brazilian former Liverpool player pointed to a space beyond the whitest end of a porcelain colour chart and asked for “maximo”."