Wesleyan has acquired DPAS, which provides practice-branded dental plans.
The deal is still subject to regulatory approval.
The Wesleyan Group includes Practice Plan, a provider of practice branded dental membership plans, and is currently the second largest provider of such plans in the UK.
Earlier in 2015 Wesleyan acquired Syscap Holdings Ltd, which provides short term business loans, IT leasing and asset finance.
Gary Anders, managing director of DPAS, said: "Wesleyan is an established player in the dental market and has a deep understanding of it.
"We are pleased to become part of a Group that understands our business and our customers."
Craig Errington, group chief executive of Wesleyan, said: "Our vision is to be the best in our chosen markets and we have been growing the Wesleyan Group to increase the range of services we can offer our customers.
"The acquisition of DPAS will enable Wesleyan to strengthen its commercial offering in the dental market where we have a strong presence through other parts of the Group including Practice Plan.
"We can now take the best of both Practice Plan and DPAS to deliver a first class customer service.
"We have been offering personal financial advice to dentists for over 100 years. It's a market we understand well and we're pleased to have this opportunity to expand our presence within it."
Wesleyan Chairman Bryan Jackson CBE commented: "DPAS is a strong and successful business and well established within the dental market.
"It has a strong affinity with the Wesleyan brand and an excellent reputation within the dental profession.
Jackson added: "This acquisition is a clear indication of our commitment to be the provider of choice for dental professionals."
Due to challenges obtaining medical evidence
'Work together, be prepared and where possible be flexible'
‘To focus on other priorities’
Virtual GP most popular service
At Scottish Widows recognition event