Apical root resorption during orthodontic treatment. A prospective study using cone beam CT

Abstract

Objective: To investigate the incidence and severity of root resorption during orthodontic treatment by means of cone beam computed tomography (CBCT) and to explore factors affecting orthodontically induced inflammatory root resorption (OIIRR).

Materials and methods: CBCT examinations were performed on 152 patients with Class I malocclusion. All roots from incisors to first molars were assessed on two or three occasions.

Results: At treatment end, 94% of patients had ≥1 root with shortening >1 mm, and 6.6% had ≥1 tooth where it exceeded 4 mm. Among teeth, 56.3% of upper lateral incisors had root shortening >1 mm. Of upper incisors and the palatal root of upper premolars, 2.6% showed root shortenings >4 mm. Slanted surface resorptions of buccal and palatal surfaces were found in 15.1% of upper central and 11.5% of lateral incisors. Monthly root shortening was greater after 6-month control than before. Upper jaw teeth and anterior teeth were significantly associated with the degree of root shortening. Gender, root length at baseline, and treatment duration were not.

Conclusion: Practically all patients and up to 91% of all teeth showed some degree of root shortening, but few patients and teeth had root shortenings >4 mm. Slanted root resorption was found on root surfaces that could be evaluated only by a tomographic technique. A CBCT technique can provide more valid and accurate information about root resorption.

Figures

Figure 1

Measurement procedure for assessment of root length by means of axial, coronal, and sagittal slices. Measurements were made (A) in the coronal view between two reference lines, (b) one at the cementoenamel junction, (c) and one at the root apex. D and E, Corresponding axial views and (F) sagittal view were used to ensure proper positioning of reference lines.

Figure 2

A, Example of an upper central incisor at baseline, with (B) palatal surface resorption at endpoint.

Figure 3

A case with severe root shortening during the course of treatment. Teeth are numbered according to FDI.