Split-Mouth Design
A clinical trial design in which different interventions are applied to contralateral or otherwise comparable sites within the same patient, with each patient serving as their own control.
Full Definition
The split-mouth design is a within-subject crossover study design frequently used in periodontal and restorative dental research to reduce inter-subject variability. By allocating different treatments to different quadrants or sides of the same mouth, confounding from patient-level variables is minimised. Editors reviewing dental research manuscripts should verify that authors account for potential carryover effects and site-level correlation in the statistical analysis. The design is particularly common in studies comparing scaling protocols, adhesive materials, or local drug delivery agents. It must not be confused with a parallel-group design, where different subjects receive different interventions.
Usage
Usage note: Ensure authors specify the unit of randomisation (site, quadrant, or side) and address carryover effects explicitly; absence of this information is a common editorial flag.
In Context
- "A split-mouth design was employed to compare the efficacy of two scaling protocols, with each quadrant randomly assigned to a treatment arm." — Periodontal RCT methods section
- "The statistical model accounted for the within-subject correlation inherent in the split-mouth design." — Biostatistics review of a dental journal manuscript