INDIANAPOLIS -- A cheating scandal at the Indiana University School of Dentistry involves nearly half of the school's second-year dental students.

Several students in the program, which is at Indiana University-Purdue University Indianapolis, were expelled and others knew about it, officials said.

School officials said several students got an early sneak peek at a test that was given over the Internet, 6News' Ericka Flye reported.

A student tipped off a professor about the cheating, and that led to the investigation.

Dr. Lawrence Goldblatt, the Dean of the IU School of Dentistry, said students gained access to an Internet password that allowed them to see and study X-rays from their home computers.

"It's a blow to all of us, everybody in the school of dentistry family," Goldblatt said.

Officials said they think an Internet-savvy student cracked the computer code and spread the word. They also think other students experimented by entering old passwords used to open the exam and that some got lucky.

After a two-month investigation, nine students were dismissed, six were suspended and 21 received letters of reprimand.

Mike Pinter, an IU dental student, said patients put a lot of trust in their dentist and that the cheaters tarnished the image of hard-working students.

"They kind of got what was going to come to them," Pinter said. "Many are punished by the crimes of a few, and I'm sure we are going to have to try to earn back the trust."

University officials said they have a plan to make sure the same scenario doesn't happen again.

"We will continue to hold the students to that level of integrity, but we'll also make sure that our system is very difficult to break into," Goldblatt said.

The accused students can appeal.