Effects of low-intensity laser therapy on periodontal tissue remodeling during relapse and retention of orthodontically moved teeth

Effects of low level laser on periodontal tissue remodeling in hPDLCs under tensile stress

This study aimed to investigate the effect of Low-Level Laser Therapy (LLLT) on human Periodontal Ligament Cells (hPDLCs) under tension stress. Primary hPDLCs were obtained using the tissue culture method, and P3 cells were utilized for the subsequent experiments. The study comprised four groups: a blank control group (Group B), a laser irradiation group (Group L), a tension stress group (Group T), and a laser + tension stress group (Group LT). Mechanical loading was applied using an in-vitro cell stress loading device at a frequency of 0.5 Hz and deformation of 2% for two hours per day for two days. Laser irradiation at 808 nm GaAlAs laser was administered 1 h after force loading. Cell samples were collected after the experiment. Bone and fiber remodeling factors were analyzed using PCR and Western blot. Flow cytometry was employed to assess the cell cycle, while ROS and Ca2+ levels were measured using a multifunctional enzyme labeling instrument. The results revealed that laser intervention under tension stress inhibited the expression of osteogenic differentiation factors, promoted the expression of osteoclast differentiation factors, and significantly increased the production of collagen factors, MMPs, and TIMPs. The LT group exhibited the most active cell cycle (P < 0.05). LLLT not only enhanced Ca2+ expression in hPDLCs under tension stress, but also stimulated the production of ROS. Overall, our findings demonstrate that LLLT effectively accelerated the proliferation of hPDLCs and the remodeling of periodontal tissue, possibly through the regulation of ROS and Ca2+ levels in hPDLCs.

Diode laser in management of loss of taste sensation in patients with post-COVID syndrome: a randomized clinical trial

OBJECTIVE

Loss of taste (ageusia) is a symptom observed following recovery from COVID-19 infection. The loss of taste and smell sensation may negatively affect patients' quality of life (QoL). The present study aimed to evaluate the effectiveness of the Diode Laser in managing loss of taste sensation in patients with post-COVID syndrome versus the placebo.

MATERIAL AND METHOD

The study sample was 36 patients who complained of persistent loss of taste sensation following COVID-19. The patients were randomly assigned to one of the two groups according to the received treatment: Group I (laser treatment) and Group II (light treatment), with each patient receiving a diode laser treatment or placebo from the same operator. Taste sensation was subjectively measured after treatment for four weeks.

RESULTS

The results demonstrated a significant difference between both groups regarding taste restoration after one month (p = 0.041), with Group II having a significantly higher percentage of cases 7 (38.9%) with partial taste restoration. In contrast, a significantly higher proportion of Group I 17 cases (94.4%) had complete taste restoration (p < 0.001).

CONCLUSION

The present study concluded that using a Diode laser 810 nm aided in a more rapid recovery from loss of taste dysfunction.

Three-dimensional imaging and molecular analysis of the effects of photobiomodulation and mechanical vibration on orthodontic retention treatment in rats : Effects of photobiomodulation and mechanical vibration on orthodontic retention treatment

PURPOSE

We aimed to evaluate and compare effects of photobiomodulation (PBM) and low-magnitude high-frequency mechanical vibration (HFMV) on orthodontic retention.

METHODS

Sixty-four female Wistar albino rats were divided into 9 groups (2 negative and positive controls each, 3 PBM and 2 HFMV groups) and studied for 25 days. In the experimental groups, closed nickel-titanium closed coil springs with a 50 cN force were placed for 10 days between the maxillary incisor and molar. PBM and HFMV were applied daily over long- (15 days) and short-term (7 days) retention periods. The PBM groups received PBM with a single wavelength (650 nm) or higher wavelengths (532, 650, 940 nm) for 9 min per day. HFMV groups received HFMV of 10, 20, and 30 Hz for 10 min per day. Right and left maxilla were assessed using micro-computed tomography imaging and real-time polymerase chain reaction. The amount of tooth movement during the retention period, expression levels of cyclooxygenase‑2 (COX-2), osteoprotegerin (OPG), and receptor activator of nuclear factor-kappa B ligand (RANKL) mRNA gene expression levels, OPG/RANKL ratios, alveolar bone trabecular thickness (Tb.Th), trabecular number (Tb.N), and structure model index were analyzed. Kruskal-Wallis and Mann-Whitney U tests were used for multiple comparisons of the nonparametric distributed data and binary comparisons, respectively.

RESULTS

When using the long-term retention protocol, PBM and HFMV treatment increased Tb.N (p < 0.05) and decreased COX‑2 mRNA gene expression levels (p < 0.05) and Tb.Th (p < 0.05) compared to controls. For short-term retention, PBM and HFMV decreased the amount of relapse tooth movement compared to controls. In addition, Tb.Th (p < 0.05) and the mRNA gene expression levels of COX‑2 and RANKL (p < 0.05) were decreased.

CONCLUSION

PBM and HFMV might be able to support retention after orthodontic tooth movement by reducing bone resorption and increasing bone quality.

Effect of photobiomodulation on external root resorption during orthodontic tooth movement - a randomized controlled trial

OBJECTIVE

The objective of the study was to compare external root resorption during orthodontic tooth movement between patients who were subjected to photobiomodulation and those who were not.

MATERIALS AND METHODS

The study was designed as a split-mouth, single-blind randomized controlled trial conducted on twenty-two orthodontic patients requiring extraction of maxillary first premolars (age group 13-30years). A buccal force was applied to all the premolars using a 0.019″×0.025″ beta-titanium cantilever spring for 28days. The test group premolars were irradiated by indium-gallium-arsenide (InGaAs) diode laser (980nm, 100mW) 0, 3, 7, 11, 15 and 28days after force application. Each premolar was irradiated at ten locations on the buccal and palatal gingiva resulting in a total energy of 10J delivered per tooth. After 28days, the root surface of all the premolars were studied for the number and volume of resorption craters using three-dimensional optical profilometry by a blinded assessor. One-sample Kolmogorov-Smirnov test was used to ascertain normality and Mann-Whitney U test was applied for data analysis.

RESULTS

All twenty-two patients enrolled completed the study. The root surface analysis showed formation of 32.78% less number of resorption craters (P<0.05) and 39.49% less volume of resorption craters (P<0.05) in the test group premolars relative to the control group premolars.

CONCLUSIONS

The results of the present study, therefore, suggest that photobiomodulation reduces external root resorption during orthodontic tooth movement.

TRIAL REGISTRATION/REGISTRATION NUMBER

CTRI/2018/04/013520.

Central Proteins of Plasma in Response to Low-Level Laser Therapy Involve in Body Hemostasis and Wound Repair

Introduction: Low-level laser therapy (LLLT) is accompanied by protein expression change in the body. There are many efforts to find a clear relationship between the differentially expressed proteins. This study aims to find the central differentiated expressed proteins of plasma after LLLT. Methods: Six proteins are extracted from a proteomics study and the network including these query proteins plus 100 first neighbors was constructed. The central proteins were determined based on degree value, betweenness centrality, closeness centrality (CC), and stress (The centrality parameters). Results: Among 106 nodes of the network, 10 proteins were characterized with the most values of degree, betweenness centrality, CC, and stress. These proteins were determined as central proteins in response to LLLT in plasma. Conclusion: Three query proteins, AHSG, FGG, and SERPINA1, plus 7 first neighbors, namely FGA, ALB, KNG1, FN1, APP, TIMP1, and F5, were identified as central proteins which were dysregulated.

Effect of Photobiomodulation on Relapse in an Experimental Rapid Maxillary Expansion Model in Rat

Rapid maxillary expansion (RME) is performed on transversely deficient maxilla. As all orthodontic treatments, retention is important in maintaining therapeutic outcomes. Fixed /removable retainers are used post-RME causing hygiene and compliance problems. Given photobiomodulation's positive effects on the quantity and quality of bone regeneration, its effect on post-RME relapse was studied. Thirty Sprague Dawley rats were randomly divided into group R, non-irradiated RME-treated (n = 12), group P, irradiated RME-treated (n = 12) and group C, non-RME non-irradiated (n = 6). A 1.5 mm metal ring inserted between maxillary incisors at days 0 and 15 was expanded until 1.5 mm space was obtained at day 30. In group P, Ga-Al-As diode laser (810 nm, 100 mW, 4J/cm² , 30 secs) was applied on days 0, 2, 4, 6, 8, 10, 12 and 14 as predictor variable. The relapse was measured as the space lost between incisors for 30 days after appliance removal (primary outcome variable) and compared with t-test. In week 2, space loss in group P was significantly lower (P < 0.05) than all other groups. The relapse during weeks 2 and 3 was significantly lower in group P than group R. However, no significant difference in relapse amount was found between groups during first and fourth week. There was a significant difference (P < 0.05) between groups in relapse rates (secondary outcome variable) but not in total relapse after 4 weeks. Photobiomodulation proved beneficial in resisting relapse in our study, and it is suggested to be continued until the end of expansion.

Antifibrotic effects of sulforaphane treatment on gingival elasticity reduces orthodontic relapse after rotational tooth movement in beagle dogs

Objective

Increased gingival elasticity has been implicated as the cause of relapse following orthodontic rotational tooth movement and approaches to reduce relapse are limited. This study aimed to investigate the effects of sulforaphane (SFN), an inhibitor of osteoclastogenesis, on gene expression in gingival fibroblasts and relapse after rotational tooth movement in beagle dogs.

Methods

The lower lateral incisors of five beagle dogs were rotated. SFN or dimethylsulfoxide (DMSO) were injected into the supra-alveolar gingiva of the experimental and control group, respectively, and the effect of SFN on relapse tendency was evaluated. Changes in mRNA expression of extracellular matrix components associated with gingival elasticity in beagles were investigated by real-time polymerase chain reaction. Morphology and arrangement of collagen fibers were observed on Masson's trichrome staining of buccal gingival tissues of experimental and control teeth.

Results

SFN reduced the amount and percentage of relapse of orthodontic rotation. It also decreased the gene expression of lysyl oxidase and increased the gene expression of matrix metalloproteinase (MMP) 1 and MMP 12, compared with DMSO control subjects. Histologically, collagen fiber bundles were arranged irregularly and were not well connected in the SFN-treated group, whereas the fibers extended in parallel and perpendicular directions toward the gingiva and alveolar bone in a more regular and well-ordered arrangement in the DMSO-treated group.

Conclusions

Our findings demonstrated that SFN treatment may be a promising pharmacologic approach to prevent orthodontic rotational relapse caused by increased gingival elasticity of rotated teeth in beagle dogs.

Photobiomodulation-Underlying Mechanism and Clinical Applications

The purpose of this study is to explore the possibilities for the application of laser therapy in medicine and dentistry by analyzing lasers' underlying mechanism of action on different cells, with a special focus on stem cells and mechanisms of repair. The interest in the application of laser therapy in medicine and dentistry has remarkably increased in the last decade. There are different types of lasers available and their usage is well defined by different parameters, such as: wavelength, energy density, power output, and duration of radiation. Laser irradiation can induce a photobiomodulatory (PBM) effect on cells and tissues, contributing to a directed modulation of cell behaviors, enhancing the processes of tissue repair. Photobiomodulation (PBM), also known as low-level laser therapy (LLLT), can induce cell proliferation and enhance stem cell differentiation. Laser therapy is a non-invasive method that contributes to pain relief and reduces inflammation, parallel to the enhanced healing and tissue repair processes. The application of these properties was employed and observed in the treatment of various diseases and conditions, such as diabetes, brain injury, spinal cord damage, dermatological conditions, oral irritation, and in different areas of dentistry.

Laser Photobiomodulation Over Teeth Subjected to Orthodontic Movement

Background: Orthodontics of the 21st century requires aesthetic, painless, predictable, and quick treatments. This demand for faster results generated orthodontic movement acceleration protocols (OMAPs); among other OMAPs we present low-level laser (LLL) as a candidate. Objective: To evaluate levels of interleukin (IL)-1, IL-10, and type 1 collagen in the periodontal ligament of first molars of rats subjected to orthodontic traction with and without LLL irradiation, compared with untreated controls (CO), and to evaluate whether the dose of LLL used in this work is eligible as an OMAP. Materials and methods: A total of 35 male Wistar rats were distributed into three groups: group 1 NI (nonirradiated) n = 15, group 2 IR (laser irradiated using 5 J, 177 J/cm², and 100 mW applied in contact to the vestibular mesial, vestibular distal, and palatal faces of gum tissue around molar region for 50 sec each point, for 3 consecutive days, immediately 24 and 48 h after orthodontic device placement.) n = 15, and group 3 CO n = 5; groups 1 and 2 were subjected to orthodontic force and each group was divided into three subgroups that were sacrificed after 3, 5, and 7 days, IL-1/10 and COL-1 levels were analyzed. Results: In the IR group, levels of IL-1/10 and COL-1 showed peak anticipation after LLL irradiation compared with those in the NI and CO groups. Conclusions: These results can also infer that this dose of LLL can be used as an OMAP.

Effectiveness of Low-Level Laser Therapy during Tooth Movement: A Randomized Clinical Trial

The present study evaluated the effects of low-level laser therapy (LLLT) by means of a diode laser in accelerating orthodontic tooth movement (OTM). After extraction of the first upper premolars for orthodontic purpose, 82 maxillary canines which needed distalization were analyzed in 41 enrolled patients (21 males, 20 females, mean age 13.4 ± 2.1 years). On all experimental sites, an orthodontic force of 50/N was applied by a nickel-titanium (NiTi) closed coil spring (G&H, Franklin, IN, USA) in order to obtain the space closure. Using a split mouth randomized design, the test side was treated using a diode laser (Wiser Laser Doctor Smile, Brendola, Italy) operating at 810 nm wavelength in continuous wave mode at both the buccal and palatal side on three points/side (distal, medial and mesial) (1 W output power, continuous wave of 66.7 J/cm², energy density of 8 J) at baseline and at 3, 7, and 14 days and every 15 days until the space closed. On the control side, the opposite selected canine was treated only using orthodontic traction. The primary outcome chosen was the overall time needed to complete the levelling and closing space, measured on a study cast. The secondary outcome chosen was the evaluation of pain levels related to tooth traction, using a Visual Analogue Scale (VAS), recorded at 3, 7, and 14 days after treatments. The mean space closures of the maxillary canines were comparable between groups [Test, 4.56 mm (95% CI 3.9-4.8); Control, 4.49 mm (95% CI 3.8-4.7), p = 0.456]. The laser group yielded less mean time [84.35 ± 12.34 days (95% CI 79.3-86)] to accomplish space closure compared to the control group [97.49 ± 11.44 days (91.7-102.3)] (p < 0.001). The test side showed a significant reduction in the average range of dental pain at 3 [Test, 5.41 (95% CI 5.1-5.6); Control, 7.23 (95% CI 6.9-7.6), p < 0.001], 7 [Test, 4.12 (95% CI 3.8-4.7); Control, 5.79 (95% CI 5.4-5.8), p < 0.001], and at 14 days [Test, 2.31 (95% CI 1.8-2.3); Control, 3.84 (95% CI 3.3-4.2), p < 0.001] after treatment (p < 0.001). This study demonstrates that the use of LLLT therapy was effective in accelerating tooth movement and reducing pain levels related to OTM.

Effects of Different Parameters of Diode Laser on Acceleration of Orthodontic Tooth Movement and Its Effect on Relapse: An Experimental Animal Study

AIM

Recent studies have demonstrated that low-level laser therapy (LLLT) can accelerate orthodontic tooth movement. However, there is still controversy about the optimum parameters that can cause acceleration. The present study was designed to examine two different doses of LLLT in the acceleration of orthodontic tooth movement and their effect on relapse.

METHODS

An orthodontic appliance was designed to induce tooth movement on lower incisors of rabbits. The in-al-as diode laser was used to radiate different groups of rabbits according to a specific protocol. The amount of tooth movement was measured for 21 days, and then the orthodontic appliance was removed, and the relapse was measured till day 28.

RESULTS

The amount of tooth movement was significantly greater in the group with irradiation of low dose in comparison with the high dose group and the control group. The relapse was greatest in the group of low dose irradiation and least in the control group.

CONCLUSION

The findings suggest that LLLT with a low dose accelerate the orthodontic tooth movement while LLLT with a high dose was not able to have the same effect. LLLT had a reverse effect on relapse tendency; an increase in the relapse tendency was seen with low dose irradiation.

Photobiomodulation alters matrix protein activity in stressed fibroblast cells in vitro

A balance is maintained between matrix synthesis and degradation, and a prolonged increase in matrix metalloproteinases (MMPs) affects healing. Photobiomodulation (PBM) speeds up healing and alters wound environment. The study aimed to determine changes in protein and gene expression of collagen type 1 (Col-I), MMP-3 and -9 and TIMP-1 in fibroblasts irradiated at 660 or 830 nm. Commercially purchased human skin fibroblast cells were modeled into five groups namely, normal, normal wounded, diabetic wounded, hypoxic wounded and diabetic hypoxic wounded. Control cells were sham irradiated. Laser irradiation was conducted at 660 or 830 nm (108/or 94 mW, 9.1 cm² , 420/or 483 s) with 5 J/cm² . Forty-eight hours post-irradiation, protein expression of TIMP-1, MMP-3, -9 and Col-I was determined by flow cytometry and immunofluorescence, and gene expression by real-time RT-PCR. There was an increase in TIMP-1 and Col-I, and a decrease in MMP-3 and -9, as well as an alteration in mRNA expression of MMP3, MMP9, TIMP1 and COL1A1 in irradiated cells. Due to the responsiveness of the diabetic hypoxic wounded model, the findings propose this model as appropriate for wound healing studies and suggest that PBM promotes the remodeling phase of wound healing by decreasing matrix degradation and upregulating synthesis.

Effect of 670 nm laser photobiomodulation on vascular density and fibroplasia in late stages of tissue repair

This study aimed to investigate the effects of gallium-aluminum-arsenium (GaAlAs) (670 nm) laser therapy on neoangiogenesis and fibroplasia during tissue remodelling. Forty male Wistar rats underwent cutaneous surgery and were divided into 2 experimental groups: the Control and Laser group (9 mW, 670 nm, 0.031 W/cm² , 4 J/cm² ). After 14, 21, 28, and 35 days, the animals were euthanised. Descriptive and quantitative analyses were performed in sections stained with haematoxylin-eosin and Sirius Red, respectively. The amounts of VEGF+ and CD31+ cells were evaluated by immunohistochemistry and histomorphometric analysis, respectively. Statistical analysis was performed using the Mann-Whitney, Friedman, and Spearman correlation test, P < 0.05. The collagen expression was significantly higher in the laser group compared with the control group on days 14 and 21 after the creation of the skin wound (P = 0.008; P = 0.016) and in the control group between 14 and 28 and 14 and 35 days (P = 0.001; P = 0.007). There were more blood vessels in three periods of the study only in the (Laser) treated group, with statistical significance at day 14 (P = 0.016). There was no statistically significant difference in VEGF+ cell count in the different experimental groups throughout the study, although a positive correlation was shown with the area of collagen on days 14 and 28 (P = 0.037). Laser treatment had a positive effect in the late course of healing, particularly with regards to collagen expression and the number of newly formed vessels. VEGF+ cells were present in both experimental groups, and VEGF appeared to influence fibroplasia in the treated group.

Influence of olive oil on alveolar bone response during orthodontic retention period: rabbit model study

OBJECTIVES

This study attempted to evaluate clinically and histologically the effects of olive oil (Ol) consumption on orthodontic relapse after the retention period.

DESIGN

Thirty apparently healthy female albino rabbits, weight more than 1000 g each was used in this study. The animals were grouped randomly into six groups of five animals each: two control and four experimental groups. In control groups, the relapse was estimated either at zero day, or at the end of the fourth week after orthodontic retention period. In the experimental groups, the animals' groups received Ol, 7.7, or 15.4 ml/kg b.w. per day during the orthodontic retention period. The relapse was estimated either at zero day, or at the end of the fourth week after orthodontic retention period for each concentration. Modified fixed orthodontic appliances were attached to the rabbits' lower central incisors. Each rabbit received orthodontic intervention for one week, followed by six weeks retention period. At the end of the experiments, the clinical and histological investigations were conducted. Data analyses were performed at the level of p < .05 for the statistically significant difference.

RESULTS

Clinically, Ol high concentration four weeks group showed a significantly lower relapse tendency than control four weeks group. Histologically, Ol low concentration zero time group showed significantly higher osteoblasts numbers than control zero time group. Olive oil low and high concentrations four weeks group showed significantly lower fibroblasts count. Moreover, Ol high concentration four weeks group revealed significantly higher bone mineralization, osteoblasts and osteocytes counts than control four weeks study group.

CONCLUSIONS

Supplementation with Ol during an orthodontic retention period, especially at 15.4 ml/kg b.w. per day concentration, clinically reduced orthodontic relapse on rabbit model. Histologically, Ol increased osteoblasts and osteocytes counts and the relative amount of bone mineralization of connective tissue layer forming alveolar bone (AB) at the end of four weeks after the orthodontic retention period.

Effect of Low-Level Laser Therapy on Relapse of Rotated Teeth: A Systematic Review of Human and Animal Study

OBJECTIVE AND BACKGROUND

Low-level laser therapy (LLLT) has been used to reduce the relapse of orthodontically rotated teeth. However, controversial conclusions have been drawn by different authors. This review aimed to evaluate the efficacy of LLLT on relapse of corrected tooth rotations systematically by overall search of available studies and scientific assessment.

METHODS

A comprehensive electronic search was performed through PubMed, MEDLINE, EMBASE, Web of Science, CENTRAL, PRL, and WHO ICTRP up to November 2015 with no language limitation. This systematic review was carried out according to Cochrane Handbook and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Risk of bias assessment was undertaken according to Cochrane Handbook for Systematic Reviews of Interventions. Two review authors conducted the work of search, selection, and quality assessment independently in duplicate.

RESULTS

Out of 112 studies, two animal experiments and one human study were included. Degree and percentage of relapse of rotated teeth were compared between control and LLLT group.

CONCLUSIONS

According to the results of our systematic review, the effect of LLLT on relapse of corrected tooth rotations is related to energy density. Namely, low energy density seems to promote relapse, while high energy density might alleviate the relapse. Since available investigations are limited, more well-designed randomized controlled trials involving humans are needed to get more clinically significant conclusions.

The Role of Matrix Metalloproteinases in Diabetic Wound Healing in relation to Photobiomodulation

The integration of several cellular responses initiates the process of wound healing. Matrix Metalloproteinases (MMPs) play an integral role in wound healing. Their main function is degradation, by removal of damaged extracellular matrix (ECM) during the inflammatory phase, breakdown of the capillary basement membrane for angiogenesis and cell migration during the proliferation phase, and contraction and remodelling of tissue in the remodelling phase. For effective healing to occur, all wounds require a certain amount of these enzymes, which on the contrary could be very damaging at high concentrations causing excessive degradation and impaired wound healing. The imbalance in MMPs may increase the chronicity of a wound, a familiar problem seen in diabetic patients. The association of diabetes with impaired wound healing and other vascular complications is a serious public health issue. These may eventually lead to chronic foot ulcers and amputation. Low intensity laser irradiation (LILI) or photobiomodulation (PBM) is known to stimulate several wound healing processes; however, its role in matrix proteins and diabetic wound healing has not been fully investigated. This review focuses on the role of MMPs in diabetic wound healing and their interaction in PBM.

The management of perioperative nutrition in patients with end stage liver disease undergoing liver transplantation

Malnutrition is found in almost 100% of patients with end stage liver disease (ESLD) awaiting transplantation and malnutrition before transplantation leads to higher rates of post-transplant complications and worse graft survival outcomes. Reasons for protein energy malnutrition include several metabolic alterations such as inadequate intake, malabsorption, and overloaded expenditure. And also, stress from surgery, gastrointestinal reperfusion injury, immunosuppressive therapy and corticosteriods use lead to delayed bowl function recovery and disorder of nutrients absorption. In the pretransplant phase, nutritional goals include optimization of nutritional status and treatment of nutrition-related symptoms induced by hepatic decompensation. During the acute post-transplant phase, adequate nutrition is required to help support metabolic demands, replenish lost stores, prevent infection, arrive at a new immunologic balance, and promote overall recovery. In a word, it is extremely important to identify and correct nutritional deficiencies in this population and provide an adequate nutritional support during all phases of liver transplantation (LT). This study review focuses on prevalence, nutrition support, evaluation, and management of perioperative nutrition disorder in patients with ESLD undergoing LT.

Combined effect of photobiomodulation with a matrix metalloproteinase inhibitor on the rate of relapse in rats

OBJECTIVE

To investigate combined effect of photobiomodulation with a matrix metalloproteinase (MMP) inhibitor on the relapse rate in relation to MMP expression in rats.

MATERIALS AND METHODS

Fifty-two rats were divided into four groups according to the treatment modality: control group, irradiation group, doxycycline group, and irradiation with doxycycline group. During a relapse period of 5 days after orthodontic movement, maxillary central incisors were treated by low-level laser therapy (LLLT) as a photobiomodulation and/or doxycycline as a synthetic MMP inhibitor. Relapse rate was evaluated in association with MMP expression at the gene and protein levels.

RESULTS

Relapse rates were increased by LLLT (1.57-fold) and decreased by doxycycline (0.83-fold) compared with the control, showing positive correlation with the levels of expression for all MMPs in the periodontal ligament (PDL). LLLT concomitant with doxycycline administration resulted in no significant differences of relapse rate and MMP expression from the control.

CONCLUSIONS

The combined effect of photobiomodulation with an MMP inhibitor around the relapsing teeth proved to be antagonistic to PDL remodeling activity during relapse. This study suggests a basis for developing a novel biologic procedure targeting the MMP-dependent PDL remodeling to control the relapse rate.

The influence of low-level laser on orthodontic relapse in rats

SUMMARY OBJECTIVES

This study evaluated the effect of low-level laser therapy (LLLT) on the tendency of rat molars to relapse following orthodontic tooth movement (OTM).

MATERIAL AND METHODS

Maxillary rat molars were moved mesially for 10 days. Animals were randomly assigned to group I (non-irradiated) or II (irradiation with LLLT). Appliances were removed, and the molars allowed to relapse for 1, 3, 5, 7, 14, or 21 days; rats in group II received LLLT according to a protocol. Bone density of periapical alveolar bone was measured using radiographs and Digora software. Dental supporting structures were examined histologically with haematoxylin and eosin and tartrate-resistant acid phosphatase.

RESULTS

In both groups, first molar relapse was rapid 1 day after the end of active treatment; by 21 days percentage relapse was measured as 86.11 per cent in group I, and 72.22 per cent in group II. Osteoclast number was highest at the end of active OTM, and thereafter successively decreased during the relapse phase in both groups. Decrease in number, and redistribution of osteoclasts occurred more rapidly in the non-irradiated than the LLLT group. Whilst molar relapse was generally less and osteoclast numbers generally higher in group II compared to group I, the differences were not significant. There was no significant difference in bone density between the two groups.

CONCLUSIONS

These results indicate that LLLT may reduce the relapse tendency, possibly due in part to bone formation in previous tension areas, and to redistribution of osteoclasts following removal of orthodontic force. The role of LLLT in the prevention of orthodontic relapse requires further study.

Effects of medications and laser on induced tooth movement and associated root resorption: four key points

The following four fundamental points on the use of experimental models will be described to ensure an accurate evaluation of the effects of medication and laser therapy on induced tooth movement and associated root resorption: (1) If the objective is to check the effect on root resorption, the forces experimentally applied must produce a lesion on the cementoblast layer in all specimens; (2) If the objective is to optimize induced tooth movement and reduce treatment time without side effects, the forces experimentally applied should not produce a lesion in the cementoblast layer in any specimen; (3) The laser therapy operator, the person administering medication and the person that places appliances should not know which animals will effectively receive the test treatment, and the control groups should receive placebo treatments; (4) CT and microscopic analysis of the specimens should be random, and the group to which the specimen belongs should not be identified, to ensure that the person reading images and the pathologists are not influenced in their evaluation of phenomena. These measures will ensure that results are more reliable and easier to extrapolate to orthodontic clinical practice.

Developments in low level light therapy (LLLT) for dentistry

OBJECTIVES

Low level light/laser therapy (LLLT) is the direct application of light to stimulate cell responses (photobiomodulation) in order to promote tissue healing, reduce inflammation and induce analgesia. There have been significant studies demonstrating its application and efficacy at many sites within the body and for treatment of a range of musculoskeletal injuries, degenerative diseases and dysfunction, however, its use on oral tissues has, to date, been limited. The purpose of this review is to consider the potential for LLLT in dental and oral applications by providing background information on its mechanism of action and delivery parameters and by drawing parallels with its treatment use in analogous cells and tissues from other sites of the body.

METHODS

A literature search on Medline was performed on laser and light treatments in a range of dental/orofacial applications from 2010 to March 2013. The search results were filtered for LLLT relevance. The clinical papers were then arranged to eight broad dental/orofacial categories and reviewed.

RESULTS

The initial search returned 2778 results, when filtered this was reduced to 153. 41 were review papers or editorials, 65 clinical and 47 laboratory studies. Of all the publications, 130 reported a positive effect in terms of pain relief, fast healing or other improvement in symptoms or appearance and 23 reported inconclusive or negative outcomes. Direct application of light as a therapeutic intervention within the oral cavity (rather than photodynamic therapies, which utilize photosensitizing solutions) has thus far received minimal attention. Data from the limited studies that have been performed which relate to the oral cavity indicate that LLLT may be a reliable, safe and novel approach to treating a range of oral and dental disorders and in particular for those which there is an unmet clinical need.

SIGNIFICANCE

The potential benefits of LLLT that have been demonstrated in many healthcare fields and include improved healing, reduced inflammation and pain control, which suggest considerable potential for its use in oral tissues.

Acceleration of tooth movement during orthodontic treatment--a frontier in orthodontics

Nowadays, there is an increased tendency for researches to focus on accelerating methods for tooth movement due to the huge demand for adults for a shorter orthodontic treatment time. Unfortunately, long orthodontic treatment time poses several disadvantages like higher predisposition to caries, gingival recession, and root resorption. This increases the demand to find the best method to increase tooth movement with the least possible disadvantages. The purpose of this study is to view the successful approaches in tooth movement and to highlight the newest technique in tooth movement. A total of 74 articles were reviewed in tooth movement and related discipline from 1959 to 2013. There is a high amount of researches done on the biological method for tooth movement; unfortunately, the majority of them were done on animals. Cytokine, PTH, vitamin D, and RANKL/RANK/OPG show promising results; on the other hand, relaxin does not accelerate tooth movement, but increases the tooth mobility. Low-level laser therapy has shown positive outcome, but further investigation should be done for the best energy and duration to achieve the highest success rate. Surgical approach has the most predictable outcomes but with limited application due to its aggressiveness. Piezocision technique is considered one of the best surgical approaches because it poses good periodontal tissue response and excellent aesthetic outcome. Due to the advantages and disadvantages of each approach, further investigations should be done to determine the best method to accelerate tooth movement.

Tissue laser biostimulation promotes post-extraction neoangiogenesis in HIV-infected patients

The aim of the study was to assess the rate of neoangiogenesis in extraction wound healing following exposure to biostimulating laser therapy and to analyze the correlation between parameters of neoangiogenesis as reflected by the number and surface area of newly formed blood vessels and clinical parameters such as gender, position of a tooth in the oral cavity, and CD4 lymphocyte count. Twenty-seven patients with confirmed HIV infection were enrolled in the study (6 women, 21 men). Eighty-nine teeth were extracted; 45 sockets were exposed to 6 J laser radiation (laser parameters were set as follows: wavelength, 820 nm; output, 200 mW; dose, 6 J/cm²; spot size, 38 mm²; continuous radiation) for five consecutive days following tooth extraction, and the remaining extraction wounds were left to heal spontaneously without laser irradiation. Antigen CD34 was assessed by immunohistochemistry as a marker of angiogenesis, and its expression was examined by computer-assisted histomorphometric image analysis. As a result, we report that biostimulating laser therapy in HIV-infected patients of varying degrees of immunodeficiency greatly accelerated post-extraction neoangiogenesis, regardless of the patient's gender, tooth position, number of roots, or number of CD4 lymphocytes in the blood. Application of low-level laser therapy for the treatment of tooth extraction wounds in HIV(+) patients greatly enhanced the formation of new blood vessels, which in turn promoted wound healing.