Digitally-driven optimization of intraoral water jet parameters for plaque removal: a personalized 3D-guided orthogonal study

BACKGROUND: Effective plaque biofilm control is essential for preventing caries and periodontal diseases. Although oral irrigation devices (water flossers) are widely used as an adjunct to toothbrushing, the specific influence of their core engineering parameters-nozzle diameter, working distance, and water pressure-on plaque removal efficacy remains poorly characterized in vivo, leaving both clinical recommendations and device design without robust evidence. This study aimed to systematically optimize these parameters using a digitally guided orthogonal experimental design. METHODS: A three-factor, three-level orthogonal design (L9 array) was employed, testing nozzle diameters of 0.4, 0.5, 0.6 mm, working distances of 1.0, 1.5, 2.0 mm, and water pressures of 70, 80, 90 psi. For each of the nine parameter sets, personalized titanium alloy guides were digitally designed using intraoral scan data and fabricated via 3D printing to ensure precise application on six test teeth per participant (n = 12). The guide featured a retention device and a water outlet assembly with calibrated nozzles. Plaque was disclosed before and after a standardized 30-second irrigation. Plaque removal rates within the defined Target Zone (T-Zone) were calculated using a 3D quantitative analysis method based on intraoral scans. RESULTS: Intuitive analysis and analysis of variance (ANOVA) of the orthogonal data revealed the influence rank: water pressure > working distance > nozzle diameter. The optimal parameter combination was determined to be a 0.5 mm nozzle diameter, 1.5 mm working distance, and 90 psi water pressure. Validation with this combination achieved a plaque removal rate of 90.21% ± 2.34% in the T-Zone. CONCLUSIONS: This study identifies water pressure as a primary determinant of water jet efficacy, with optimal results achieved at specific intermediate settings for nozzle diameter and working distance. The methodology combining personalized 3D-printed guides with orthogonal design presents a practical digital framework for the in-vivo optimization of dental therapeutic parameters.