Oasis Healthcare and IDH are among five suitors considering a bid for cosmetic dentistry chain James Hull Associates.
As reported by www.telegraph.co.uk, private equity firms Candover and GI Partners are also believed to have submitted successful first-round bids, alongside one other private equity group.
James Hull (JHA), which is jointly owned by finance house Hutton Collins, was recently put up for sale with a £200million price tag.
JHA, which has been on a major acquisition spree over the last 18 months, made pre-tax profits of around £7million in the year to April.
Dr Hull, who is still a practising dentist, is keen to drive further consolidation in the fragmented market for cosmetic treatment.
The deadline for second-round bids in the auction, which is being run by Hawkpoint, is 15 July.
The successful first-round bidders are all understood to have made offers of more than £160million.
Oasis, backed by Duke Street Capital, is being advised by NM Rothschild.