Claims have been made that electric toothbrushes are more effective than manual toothbrushes. The electric toothbrush leaves less room for patients to brush incorrectly. Other research indicates that most electric toothbrushes are no more effective that the manual variety. "Rotation-oscillation" electric brushes did marginally out-perform manual brushing, removing around 7% more plaque and leading to 17% less gum disease than manual brushes. However, this research does not exclude the possibility that people who purchase electric toothbrushes significantly improve their dental hygiene. Additionally, someone who has begun to take cleaning their teeth more seriously could improve their technique and simultaneously decide to purchase an electric toothbrush.