Objectives:

To evaluate the correlation between: (i) force levels applied to anterior teeth in the initial stages of orthodontic treatment; (ii) pain perception, and (iii) pulp sensitivity. Setting and Sample Population: Orthodontics and Maxillofacial Orthopedics Clinic at San Sebastián University in Santiago, Chile from 2012 to 2014. A non-probabilistic convenience sample was obtained of 136 teeth in 37 patients with braces and 0.014-inch heat-activated (35ºC) Nitinol™ arch wires.

Material and Method:

Prospective observational study. Teeth were evaluated with a dynamometer. Forces were classified into four categories: mild, optimal, high, and extreme. Pain was measured with the Visual Analog Scale (VAS) on the first, second, and seventh day after the force application, and thermal tests were applied on the seventh day.

Results:

A few hours after the beginning of the force application, the pain began to diminish. The pain did not vary in intensity with increasing force magnitude. 39.1% of the teeth which received “optimal” forces and 22.4% of those which received “extreme” forces exhibited an increased response to cold. 1% of the teeth subjected to “extreme” forces exhibited an increased response to heat.

Conclusions:

In the first seven days, no irreversible pulpal damage was observed regardless of the magnitude of the applied force.

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