This study evaluated the effectiveness of one electric toothbrush and oral irrigation system in comparison with manual toothbrushing in 20 orthodontic patients. Twenty patients performed four oral hygiene routines for at least 4 weeks each. The routines included manual toothbrushing alone, electric toothbrushing alone, manual toothbrushing plus irrigation, and electric toothbrushing plus irrigation. Baseline plaque and gingival scores were recorded, and both indices were again recorded after each routine. The index used to evaluate gingival health was a slight modification of the Silness and Löe gingival index, while the plaque index was similar to the patient hygiene performance (PHP) index developed by Podshadley and Haley. The average overall scores for plaque and gingival condition for all patients who used each of the four oral hygiene routines were compared with a repeated-measures, analysis-of-variance statistical evaluation. The values obtained from the analysis showed that there were no significant differences between the means for plaque and gingival health in each group. The probabilities that these conclusions are incorrect are 18% for plaque and 2% for gingival health. Testing for validity of the data was done by more than one researcher, with consistent results.