Professor Chester W. Douglass’ seven-figure donation to the Harvard School of Dental Medicine came four years before the school launched an investigation into his academic conduct, and had no effect on the review’s conclusion, the school’s spokesman, John Lacey, said yesterday.

Douglass donated around $1 million to the dental school in 2001, Lacey confirmed, four years before the Washington-based Environmental Working Group filed a complaint alleging that Douglass had committed “serious misrepresentations of research results.”

The Environmental Working Group accused Douglass in 2005 of ignoring one of his students’ research when he published a study that found no increased risk of bone cancer in young boys who drink fluoridated water.

The investigation was launched in 2005 and was conducted by two separate committees made up largely of faculty members not affiliated with the dental school, Lacey said in a statement.

Lacey said that each committee determined independently that Douglass had not intentionally suppressed his student’s findings, and that his position as editor of a Colgate-sponsored dental newsletter was not a conflict of interest.

“The committees came to the conclusion after a year of thoughtful and detailed work and were influenced only by the facts of the review,” Lacey said.

He also said that the review had been conducted with appropriate transparency.

“The complete misconduct review record was sent to the Office for Research Integrity, the federal office with oversight in these matters,” Lacey said. “[They] determined independently that no further investigation was warranted.”

—Staff writer Laurence H. M. Holland can be reached at lholland@fas.harvard.edu.