Effects of Low-Level Laser Therapy and Orthodontic Tooth Movement on Dental Pulps in Rats

Abstract

Objectives:To describe the microscopic pulpal reactions resulting from orthodontically induced tooth movement associated with low-level laser therapy (LLLT) in rats. Materials and Methods: Forty-five young male Wistar rats were randomly assigned to three groups. In group I (n ϭ 20), the maxillary right first molars were submitted to orthodontic movement with placement of a coil spring. In group II (n ϭ 20), the teeth were submitted to orthodontic movement plus LLLT at 4 seconds per point (buccal, palatal, and mesial) with a GaAlAs diode laser source (830 nm, 100 mW, 18 J/cm 2 ). Group III (n ϭ 5) served as a control (no orthodontic movement or LLLT). Groups I and II were divided into four subgroups according to the time elapsed between the start of tooth movement and sacrifice (12 hours, 24 hours, 3 days, and 7 days). Results: Up until the 3-day period, the specimens in group I presented a thicker odontoblastic layer, no cell-free zone of Weil, pulp core with differentiated mesenchymal and defense cells, and a high concentration of blood vessels. In group II, at the 12-and 24-hour time points, the odontoblastic layer was disorganized and the cell-free zone of Weil was absent, presenting undifferentiated cells, intensive vascularization with congested capillaries, and scarce defense cells in the cell-rich zone. In groups I and II, pulpal responses to the stimuli were more intense in the area underneath the region of application of the force or force/laser. Conclusions: The orthodontic-induced tooth movement and LLLT association showed reversible hyperemia as a tissue response to the stimulus. LLLT leads to a faster repair of the pulpal tissue due to orthodontic movement. (Angle Orthod. 2010;80:116-122.)

Low-level laser therapy effects in traumatized permanent teeth with extrusive luxation in an orthodontic patient

“…In this case, orthodontic treatment was continued successfully after 6 months. Findings of acceleration of new vascularization, 30 changes in cell proliferation, 30 increases in cellular proliferation of periodontal ligament cells, 27 and higher expression of fibroblast growth factors in the periodontal tissue 25 as reported in studies regarding low-power laser irradiation-associated orthodontic tooth movement might have played a role in the findings of this current study.…”

“…However, the fast occurring healing observed in the patient caused a change of mind, and the authors decided not to perform endodontic treatment and to continue with only the LLLT treatment. Abi-Ramia et al, 30 who studied the effects of LLLT and orthodontic tooth movement on dental pulps in rats, reported that LLLT leads to a faster repair of the pulpal tissue due to orthodontic movement. Orthodontically induced tooth movement associated with LLLT produced an increase in the vascularization, and this factor could accelerate pulp tissue repair.…”

“…Orthodontically induced tooth movement associated with LLLT produced an increase in the vascularization, and this factor could accelerate pulp tissue repair. 30 Ozen et al 33 reported that LLLT appears to be more beneficial as it is noninvasive when reducing long-standing sensory nerve impairment. However, therapeutic and patient-related factors should be discussed using data from longitudinal clinical studies.…”

“…18 In examining the effects of LLLT on cell cultures in vitro, some articles report an increase in cell proliferation and collagen production. 19 Although there have been several studies that have addressed the action of LLLT on bone repair, osteogenesis, [20][21][22][23][24][25][26][27][28][29] pulpal tissue, 30,31 and the dentin repair process, 32 there are no reports on its effects on teeth displaying periodontal tissue injury during orthodontic treatment.…”

Characteristics of dental pulp in human upper first premolar teeth based on immunohistochemical and morphometric examinations

“…In the direction from dentin to tooth centre, pulp has four microscopic zones: odontoblast layer, cell-poor zone, cell-rich zone and pulp proper [2].…”