The simple plastic goniometer is a fundamental instrument in the clinical evaluation of a joint’s range of motion. Made of transparent plastic, it consists of an angular scale printed in degrees and centimeters. It allows for the precise and direct measurement of joint amplitude in different planes of the body.

In medicine, its use is common in physiotherapy, rehabilitation, and orthopedics. The simple plastic goniometer allows for the assessment of joint mobility before, during, and after treatment.

In dentistry, although its use is more limited, the simple plastic goniometer is also applied to measure mandibular movements. It is especially useful in cases of temporomandibular joint (TMJ) dysfunction. The plastic goniometer allows for the determination of mouth opening and lateral mandibular displacements, which is useful in diagnoses and treatment planning.

In orthodontics, the goniometer is mainly used to measure craniofacial and mandibular angles. It allows for the precise evaluation of the relationship between bone, dental, and joint structures. Although the traditional goniometer is not as common as digital software in this area, it remains useful in some clinical procedures and in taking manual or cephalometric records.

One of the most relevant uses of the goniometer in orthodontics is the measurement of mouth opening and mandibular movements, especially in patients with temporomandibular joint dysfunction (TMD). Measuring the maximum opening angle, lateral deviations, and mandibular protrusion helps to detect functional limitations that could influence orthodontic treatment.

Furthermore, in cephalometric studies, orthodontists use goniometers (in physical or digital format) to calculate angles such as SNA, SNB, and ANB, which serve to determine the anteroposterior position of the maxilla and mandible relative to the skull. This data is key for planning treatments with functional or corrective appliances, especially in patients with skeletal malocclusions.

In veterinary medicine, this instrument is adapted to evaluate animals with joint injuries or mobility problems. Although it requires training for its use in non-cooperative patients, such as dogs or cats, its application helps to assess the range of motion in hips, elbows, and other joints, both in healthy animals and in post-surgical recovery.