Effects of low-level laser therapy on orthodontic tooth movement and root resorption after artifi cial socket preservation

Abstract

Background: Low- level laser therapy has been used to stimulate the orthodontic tooth movements

(OTM) previously. Furthermore, in the orthodontic treatments accompanying tooth extractions,

the adjacent teeth move towards the extraction sites and close the space in some cases. Then, the

adjacent tooth movements must be prevented in the treatments requiring space. Laser stimulates

and at some doses decelerates tooth movement; it also improves healing process and enhances

osteogenesis. Hence, it can prevent movement by osteogenesis adjacent to the tooth. The present

study investigated the effects of low-level laser therapy on the OTM and root resorption following

artifi cial socket preservation.

Materials and Methods: In this experimental animal trial, 16 male albino rabbits were selected

with similar characteristics and randomly divided in two groups. Under general anesthesia, an

artifi cial socket, 8 mm in height, was created in the mesial aspect of the fi rst premolars of the

rabbits and fi lled with demineralized freeze dried bone allograft (DFDBA). The fi rst premolars

were connected to the incisors using nickel titanium coil springs. In experimental group, galliumaluminum-

arsenide (GaAlAs) laser was irritated mesial to fi rst premolar where artifi cial socket

was created continuously (808 nm). The cycle was 10 days irritation, 14 days rest, 10 days irritation,

14 days rest (Biostimulation mode). Control group was not laser irradiated. All animals were

sacrifi ced after 48 days and the distance between the distal aspect of the fi rst premolars, and the

mesial surface of the second premolars was measured with leaf gauge. The specimens underwent

histological assessments. Integrity of root and its resorption was observed under microscope

calibration. The size of resorption lacunae was calculated in mm2. Normality of data was proved

according to Kolmogorov-Smirnov analysis, and Student’s t-test was done. P value less than 0.05 was

considered as signifi cant.

Results: The mean OTM were 5.68 ± 1.21 mm in the control group and 6.0 ± 0.99 mm in the laser

irradiated teeth with no statistically signifi cant differences(P > 0.75). The mean root resorption was

1.61 ± 0.43 mm2 and 0.18 ± 0.07 mm2 in the control and experimental groups respectively being

signifi cantly lower in the laser irradiated teeth (P < 0.0001).

Conclusion: The fi ndings of the present study show that GaAlAs irradiation together with the

application of DFDBA led to limited amount of the stimulated OTM. The laser beam irradiation

in combination with alloplastic materials used for socket preservation could reduce the degree of

root resorption signifi cantly.

Key Words: Low-level laser, orthodontic tooth movements, root resorption