TORONTO, May 10 (Reuters) - Shares of Sun Life Financial slumped on Friday after the Canadian insurer missed quarterly profit estimates as weakness in its dental insurance business hurt its U.S. segment.

Sun Life's shares were down nearly 5% on Friday morning while those of bigger rival Manulife were up 1% after hitting a more than 15-year high on Thursday.

Sun Life posted its first profit miss in 12 quarters, affected by the sale of Sun Life UK, the end of the COVID-19 public health emergency in the United States, and lower earnings at its wealth and asset management business.

CEO Kevin Strain told analysts the U.S. dental business was hurt by Medicaid member disenrollment at the end of the public health emergency as well as higher costs from the remaining members.

He said he expects dental results to return to profitability and expects income levels for dental to be about $100 million for 2025.

Sun Life bought DentaQuest for $2.5 billion in 2022 as part of push to expand its U.S. footprint.

The U.S. business reported a 20% fall in earnings for the first quarter.

"Given the strong results reported by peers this quarter, we believe Sun Life stock could be under pressure in the near term," National Bank analyst Gabriel Dechaine said in a note.

(Reporting by Nivedita Balu in Toronto; Editing by Michael Erman)