Motoo Niwa, a former examiner of the National Dentistry Examination, pleaded not guilty Monday before the Tokyo District Court to a charge of leaking examination questions to students last year.

Niwa, 56, a professor at Nippon Dental University, is accused of leaking 18 questions that were to be used in the national dental exam on March 15 and 16, 2000, by conspiring with two other defendants to have the questions put in a dentistry graduation exam of Ohu University on Feb. 17 and 18, 2000.

The other two defendants are Kenji Kusunoki, a former professor of Ohu University, and Itsuo Ueda, a former professor of Health Science University of Hokkaido.

Kusunoki allegedly briefed Ohu University students on 11 of the 18 questions in a lecture on Feb. 29, 2000, ahead of the national dentistry exam. However, the Health Ministry, having been informed of the leak, changed the national exam questions early in March last year.

Kusunoki, 54, and Ueda, 59, both pleaded guilty to conspiring to leak the examination questions in a separate court hearing.

Niwa, however, claimed he was merely exchanging information on themes of questions and had not violated any law.

Prosecutors told the court in an opening statement that Niwa agreed to take part in the leak scheme, apparently expecting to obtain some kind of reward from Kusunoki, who asked him for the questions.