aligner

An aligner is a device or tool used to bring components into proper alignment. The term is applied across multiple fields, including dentistry, manufacturing, and optical assemblies. Aligners can be passive fixtures such as jigs and shims that position parts during assembly or inspection, or active devices that apply controlled forces to move or adjust a target toward a desired position.

In dentistry, clear aligners are removable trays made of transparent thermoplastic polymers designed to straighten teeth. A digital treatment plan guides a sequence of aligners, each worn for about one to two weeks before advancing to the next. The process typically starts with digital scans or impressions, followed by computer modeling and custom fabrication. Benefits include esthetics and removability; limitations include restrictions on complex movements and reliance on patient compliance. They are regulated as medical devices in many regions.

In manufacturing and engineering, aligners include fixtures, jigs, gauges, and alignment systems that ensure precise positioning of parts during assembly, machining, or metrology. Methods range from mechanical references and shims to optical or laser-based alignment, often with feedback from indicators or measurement systems. Proper use reduces run-out, tooling wear, and assembly error, and is essential in high-precision sectors such as automotive, aerospace, electronics, and semiconductor fabrication.

Other uses include alignment devices in optical assemblies and more general applications where processes or data sets are brought into proper correspondence. The concept underpins accuracy across disciplines by providing reference points and controlled movement or positioning.