Low-Level Laser Action on Orthodontically Induced Root Resorption: Histological and Histomorphometric Evaluation

The influence of two photobiomodulation protocols on orthodontically induced inflammatory root resorption (a randomized controlled clinical trial)

Background

Controversial results have been reported regarding the impact of photobiomodulation (PBM) on orthodontically induced inflammatory root resorption (OIIRR). The aim of this study was to evaluate the influence of two PBM protocols, one of them requiring a high application frequency (on days 0, 3, 7, 14, then every 2 weeks), while the second requires less frequent applications (every 3 weeks), on OIIRR accompanying orthodontic treatment.

Methods

Twenty female patients were recruited for this randomized controlled trial, requiring the therapeutic extraction of maxillary first premolars, and they were randomly divided into 2 equal groups. In Group A, one side of the maxillary arch randomly received PBM on days 0, 3, 7, 14, and every 2 weeks thereafter, while in Group B, one side was randomly chosen to receive PBM every 3 weeks. The laser applied was a Diode laser with a wavelength of 980 nm, in a continuous mode. Canine retraction in both groups was carried out using closed-coil springs, delivering 150 g of force, and the force level was checked every 3 weeks, over a 12-week study period. Pre-retraction and post-retraction cone-beam computed tomography (CBCT) was done for the evaluation of OIIRR.

Results

No significant differences in the amount of OIIRR have been reported between the laser and control sides in both groups A and B. Also, no significant differences have been reported between the laser sides in both groups.

Conclusions

Photobiomodulation does not affect OIIRR, whether by increasing or decreasing its occurrence, with both laser application protocols. Therefore, it can be stated that PBM does not result in root resorption less than the commonly observed range elicited with conventional orthodontic treatment, and that it has no effect on OIIRR.

Trial registration Two Low-level Laser Irradiation Protocols on the Rate of Canine Retraction (NCT04926389), 15/06/2021—retrospectively registered. https://clinicaltrials.gov/ct2/show/NCT04926389.

Effect of photobiomodulation therapies on the root resorption associated with orthodontic forces: a pilot study using micro computed tomography

OBJECTIVES

The aim of this study is to investigate the effect of photobiomodulation therapies on root resorption compared with the placebo group.

MATERIALS AND METHODS

Thirty patients who were admitted to the Gaziantep University Faculty of Dentistry Orthodontics Department for treatment, with an indication of upper right first premolar tooth extraction were included. Before the individuals' orthodontic treatment, 0.022 slot MBT brackets and tubes were placed on the maxillary first premolar and molar. A 150-g buccal tipping force was applied to the first premolar. Cantilever spring with 0.017 × 0.025 Beta Titanium wire was used for force application. Individuals were then randomly divided into three groups. For the first group, laser application was performed with an 810-nm GaAlAs laser device at 0, 3, 7, 14, 21, and 28 days to 8 J/cm². For the second group, an LED application according to the manufacturer's instructions with an 850-nm wavelength and 20 mW/cm² output power for 10 min per day during the experiment. For the third group, a placebo therapy was completed whereby a laser device that did not make active pulses was used. At the end of 4 weeks, the amount of root surface resorption was compared using micro-CT imaging after the extraction of the teeth.

RESULTS

No significant difference was found between the groups in terms of regional and total crater volumes. It was observed that photobiomodulation therapies were not different from the control group in terms of forming root resorption.

CONCLUSIONS

It is seen that laser and LED photobiomodulation therapies used for accelerate orthodontic tooth movement do not differ from the control group in terms of forming root resorption.

CLINICAL RELEVANCE

According to the results of this pilot study on this subject, which needs to be clarified with new findings in the future, LED and laser applications may not increase the risk for root resorption.

Photobiomodulation therapy (PBMT) in bone repair: A systematic review

BACKGROUND

Photobiomodulation therapy (PBMT) using low-level laser influences the release of several growth factors involved in the formation of epithelial cells, fibroblasts, collagen and vascular proliferation, besides accelerating the synthesis of bone matrix due to the increased vascularization and lower inflammatory response, with significant increase of osteocytes in the irradiated bone. Considering its properties, beneficial effects and clinical relevance, the aim of this review was to analyze the scientific literature regarding the use of PBMT in the process of bone defect repair.

METHODS

Electronic search was carried out in PubMed/MEDLINE^Ⓡ and Web of Science databases with combination of the descriptors low-level laser therapy AND bone repair, considering the period of publication until the year 2018.

RESULTS

The literature search identified 254 references in PubMed/MEDLINE and 204 in Web of Science, of which 33 and 4 were selected, respectively, in accordance with the eligibility requirements. The analysis of researches showed articles using PBMT in several places of experimentation in the subjects, different types of associated biomaterials, stimulatory effects on cell proliferation, besides variations in the parameters of use of laser therapy, mainly in relation to the wavelength and density of energy. Only four articles reported that the laser did not improve the osteogenic properties of a biomaterial.

CONCLUSIONS

Many studies have shown that PBMT has positive photobiostimulatory effects on bone regeneration, accelerating its process regardless of parameters and the use of biomaterials. However, standardization of its use is still imperfect and should be better studied to allow correct application concerning the utilization protocols.

Phototherapy is unable to exert beneficial effects on orthodontic tooth movement in rat molars

OBJECTIVES

To investigate the effects of irradiation lasers and light-emitting diode (LED) light on root resorption in rat molars during orthodontic tooth movement (OTM).

MATERIALS AND METHODS

Twenty-one 12-week-old Wistar male rats were divided into three groups: OTM only (control [CG]), OTM and LED irradiation (DG), and OTM and low laser irradiation therapy (LG). The distance between the first and second molars was used to evaluate the amount of tooth movement. The mesial surfaces of the distopalatal roots were analyzed by scanning electron microscopy, and the area of the resorption was calculated.

RESULTS

Statistical analysis showed a decreased amount of tooth movement in the exposed DG or LG compared with CG, which was statistically significant (P = .031 and P = .004, respectively). However, when the DG and LG groups were compared, no statistically significant differences were found (P = .504). The root resorption areas were similar between CG and DG. However, statistically significant differences were found between LG and CG (P = .014) and LG and DG (P = .038).

CONCLUSIONS

Phototherapy did not enhance tooth movement, while infrared laser irradiation did increase root resorption.

Physical properties of root cementum: Part 27. Effect of low-level laser therapy on the repair of orthodontically induced inflammatory root resorption: A double-blind, split-mouth, randomized controlled clinical trial

INTRODUCTION

The purpose of this 2-arm-parallel split-mouth trial was to investigate the effect of low-level laser therapy (LLLT) on the repair of orthodontically induced inflammatory root resorption (OIIRR).

METHODS

Twenty patients were included in this study, with 1 side randomly assigned to receive LLLT, and the other side served as a sham. Eligibility criteria included need for bilateral maxillary first premolar extractions as part of fixed appliance treatment. OIIRR was generated by applying 150 g of buccal tipping force on the maxillary first premolars for 4 weeks. After the active force was removed, the teeth were retained for 6 weeks. LLLT commenced with weekly laser applications using a continuous beam 660-nm, 75-mW aluminum-gallium-indium-phosphorus laser with 1/e² spot size of 0.260 cm², power density of 0.245 W/cm², and fluence of 3.6 J/cm². Contact application was used at 8 points buccally and palatally above the mucosa over each tooth root for 15 seconds with a total treatment time of 2 minutes. After 6 weeks, the maxillary first premolars were extracted and scanned with microcomputed tomography for primary outcome OIIRR calculations. Subgroup analysis included assessment per root surface, per vertical third, and sites of heaviest compressive forces (buccal-cervical and palato-apical). Randomization was generated using www.randomization.com, and allocation was concealed in sequentially numbered, opaque, sealed envelopes. Blinding was used for treatment and outcome assessments. Two-tailed paired t tests were used to determine whether there were any statistically significant differences in total crater volumes of the laser vs the sham treated teeth.

RESULTS

Total crater volumes were 0.746 mm³ for the laser treated teeth and 0.779 mm³ for the sham. There was a mean difference of 0.033 ± 0.39 mm³ (95% CI, -0.21 to 0.148 mm³) greater resorption crater volume in the sham group compared with the laser group; this was not statistically significant (P = 0.705). No harm was observed.

CONCLUSIONS

No significant difference was found between LLLT and sham control groups in OIIRR repair.