Journal of Lasers in Medical Sciences

Introduction:  

Recently, a wide variety of procedures have been done by laser application in Orthodontics. Apart from the mentioned range of various treatments, laser has become a tool for many soft tissue surgeries as an alternative to conventional scalpel-based technique during orthodontic treatments in the management of soft tissue. Due to scarce information in the latter subject, this study was designed in order to include clinical trials that included soft tissue ablation by laser in orthodontics.

Methods: 

Literature was searched based on PubMed and Google Scholar databases in 5 years (2010-2015) with English Language restriction and clinical trial design. Studies that performed soft tissue application of laser during orthodontic treatment were extracted by the authors.

Results:

Only eight studies met the inclusion criteria. No significant difference were found between laser ablation and conventional scalpel technique in the matter of treatment outcome. However, few issues remained to clarify the differences in the mentioned procedures.

Conclusion:

Laser performance can be recommended in case of preceding less bleeding and discomfort during surgical procedure. There are still quandaries among clinical application of scalpel-based surgery in aesthetic region with bracket-bonded teeth.

Precaution and knowledge regarding the characteristics of laser beam such as wavelength, frequency, power and timing is extremely needed.

Introduction: Chronic periodontitis is the most common periodontal disease which is related to the chronic accumulation of bacterial plaque. Since mechanical methods are not sufficient in the treatment of this disease, administration of local/systemic antibiotic is recommended following mechanical debridement. However, side effects of antibiotics such as microbial resistance and patient allergy led to development of alternative methods. One of these suggested methods is the antimicrobial photodynamic therapy (aPDT). PDT is a local noninvasive treatment modality without the side effects caused by antibiotics. The aim of this study was to review the articles related to the application of PDT with laser in the treatment of chronic periodontitis.

Review of literature: In the present review of literature, the authors used key words such as Chronic Periodontitis, Laser and Photodynamic therapy, and conducted a literature search via Google Scholar and PubMed for the period of 1990 to 2015. A total of 47 articles in English were found. The articles that were not associated with the topic of research and review articles were deleted and only clinical trials were evaluated. After reviewing 23 articles’ abstracts, the full texts of 16 articles were analyzed.

Low Level Laser Therapy was introduced as an alternative non-invasive treatment for osteoarthritis, but its effectiveness is still controversial. The main objective of this article was to determine the safety and efficacy of LLLT in patients with knee osteoarthritis. In order to gather evidence, main medical databases as well as relevant websites were browsed without time limit. We searched with appropriate keywords and strategies. After quality assessment of studies, study data were extracted by two reviewers. Standard mean difference proposed through Inverse Variance was used in the meta-analysis using the random-effects model. Twelve values were used for the evaluation of heterogeneity. A total of 823 studies, 14 RCTs were selected after final review. There was a significant difference between LLLT and Placebo in pain at rest (p=0.02), pain at activity (p=0.01), total pain (p=0.03), WOMAC function (p=0.01), WOMAC stiffness (p=0.02) and WOMAC total (p<0.0001) in favor of the LLLT. There was no significant difference between LLLT and Placebo in WOMAC pain (p=0.09) and range of motion (p=0.1). In spite of some positive findings, this meta-analysis lacked data on how LLLT effectiveness is affected with important factors: wavelength, energy density, treatment duration, numbers of sessions the treatment, severity of KOA and site of application.

Introduction: Diabetic retinopathy (DR) is a serious microvascular complication of diabetes which can cause vision loss or blindness ultimately. Non enzymatic glycation of proteins leads to advanced glycation end products (AGEs) in DR. Since laser therapy is a well-established method, in this study, protein-protein interaction (PPI) network is applied for protein targets in DR disease in rats treated by laser.

Methods: In this study, we focused on articles that investigated and compared the proteome profiles of DR rats with healthy control and also DR rats before and after laser therapy. The networks of related differentially expressed proteins were explored using Cytoscape version 3.3.0, the PPI analysis methods and ClueGO.

Results: Analysis of PPI network of 37 related proteins to DR rats including 108 nodes, introduced 10 hub-bottleneck proteins and 5 concerned biochemical pathways. On the other hand, PPI analysis of related proteins to DR rats before and after laser therapy corresponded to 33 proteins and 2 biological pathways.

Discussion: Centrality and cluster screening identified hub-bottelneck genes, including Aldoa, HSPD1, Pgam2, Mapk3, SLC2A4, Ctnnb1, Ywhab, HSPA8, GAPDH and Actb for DR rats versus healthy control and ENO1, Aldoa, GAPDH for DR samples after laser therapy.
Conclusion: Gene expression analysis of the DR samples treated via laser therapy provides a molecular evidence in support of the therapeutic effect of laser.

Introduction: The objective of this study was to assess the efficacy of a combination of three wavelengths (including red, infra-red, and blue) of low-level laser (LLL) as a non-invasive therapeutic method to reduce abdominal girth. To achieve biochemical activity on adipocytes, a red laser was used in our selective laser combination. Near-infrared laser was used to increase depth of penetration. Nitrosyl complexes of hemoglobin (NO-Hb) are sensitive to blue light, thereby leading to increase in release of biologically active nitric oxide (NO), which can affect tissue perfusion. Thus, a blue LED was added to the laser combination.

Methods: [W1] Eighteen females participated in the study. Twelve sessions of laser therapy were performed, two sessions per week for each subject. Continuous wave diode lasers, including red (630nm), infra-red (808nm), and a blue LED (450nm) were applied and were all designed by the Canadian Optic and Laser Center.

Results: Statistical analyses revealed that upper abdomen size significantly decreased from pre- (91.86 ± 11.16) to post- (87.41 ± 10.52) low level laser therapy (LLLT) (p<0.001). Middle abdomen size showed significant reduction from pre- (97.02 ± 8.82) to post- (91.97 ± 8.49) LLLT (p<0.001). Lower abdomen size significantly decreased from pre- (100.36 ± 9.45) to post- (95.80 ± 8.52) LLLT (p<0.001).

Conclusion: Based on this case series pilot investigation, the combination of 3 different wavelengths of LLL was effective for abdominal girth reduction in 100% of our subjects (p<0.001), without any side effects. Future studies will assess the long-term benefits of this laser combination for reduction of subcutaneous fat deposits.

Background: Temporomandibular joint disorders are the most common source of pain on the face. There are multiple etiologies, and several types of treatment have been reported. The use of non-invasive and reversible therapies in the treatment of such problems is recommended. The present study evaluated the effect of low level laser (LLL) therapy and transcutaneous electric nerve stimulation (TENS) on temporomandibular joint disorders.

Methods: In this single-blind study, 40 patients with temporomandibular disorders were randomly divided into four groups: TENS (TENSTem dental), LLL (diode 810 nm CW), sham-TENS, and sham-LLL. All subjects were examined and data on pain and tenderness in the temporomandibular joint (TMJ) and masticatory muscles (using the visual analogue scale) and mouth-opening (distance between incisal edges before feeling pain; mm) were collected before baseline (T1), after each session (T2-T5) and one month after the end of the sessions (T6)), and analyzed using repeated measure ANOVA and Boneferronie statistical tests. A p-value < 0.05 was considered significant.

Results: The decrease in pain (p = 0.000), tenderness (p = 0.000) and increase in mouth-opening ability (p = 0.002) was greater in the TENS and LLL groups than in the placebo groups. At the one-month follow-up, significant decrease in pain and tenderness was recorded in the TENS and LLL groups (p = 0.000). There was no significant differences between TENS and LLL and the placebo groups for maximum mouth-opening at the end of the study (p = 0.692).

Introduction: Recent studies exhibited that low-level laser therapy (LLLT) accelerates regeneration process of injured peripheral nerve tissue. The objective  of  this study  was investigat the effect of LLLT (780 nm) on regeneration of the injured right sciatic nerve of male Wistar rat.

Methods: In this research work, the effect of LLLT (780nm) on the regeneration process and reconstruction of peripheral in injured right side sciatic nerve was investigated. Twelve adult male Wistar rats underwent surgery in aseptic condition under general anesthesia to induce a lesion to their right side sciatic nerve. Only the experimental group was treated by laser, before suturing the location. The damaged nerve was directly irradiated with (2J, 100 mW, 40 s). Irradiation procedure terminated on 21 days with little improvement (4 J, 200 mW, 40 s) across the skin surface of experimental group. Rats were selected randomly from each group to be sacrificed on different periods and histopathological examination was carried out on the extracted   nerves.

Results:  Significant acceleration of revascularization and angiogenesis of the injury site was observed in the experimental group. Furthermore, a reduction of hemorrhages and increase in blood supply was observed. Also, Wallerian degeneration decreased while higher axonal density compared to the control rats was  observed. Moreover, the cross-section analysis of the injured area on the 14th and 21st days as  post-surgery showed that the nerve sheath diameter in the lesion area of the experimental group was reduced.  While the ratio between thicknesses increased in the control group.

Conclusion: The current study suggests that laser phototherapy at 780 nm could accelerate the regeneration process of injured peripheral nerves tissue.

Introduction: Tinnitus is the phantom auditory perception of sound in the absence of an external or internal acoustic stimulus. The treatment is difficult due to multiple etiologies and great psychological influence. The purpose of this study was to determine alterations in auditory physiological and electrophysiological responses associated with temporary suppression of tinnitus induced by low-level laser (LLL) irradiation.
Methods: This study was conducted on 20 subjects with subjective tinnitus. All subjects signed the informed consent form and satisfied all the study eligibility criteria. Visual analog scale (VAS) for loudness, loudness matching of tinnitus (LMT), pitch matching of tinnitus (PMT), Persian-tinnitus questionnaire (P-TQ) and Persian-tinnitus handicap inventory (P-THI) were conducted pre- and post-low level laser therapy (LLLT) for all the subjects. Electrocochleography (ECochG) and distortion product otoacoustic emissions (DPOAEs) were recorded in 11 subjects. Continuous wave diode lasers, including red (630 nm) and infra-red (808 nm) were applied, and were both designed by the Canadian Optic and Laser (COL) Center. Twelve sessions of laser therapy were performed, 2 sessions per week for each subject. Total dose was 120 Joule/ear/session.
Results: LLL irradiation could cause a significant decrease in subjective tests scores consisting of VAS for loudness, PMT, P-TQ, P-THI, but did not result in a significant improvement of objective evaluating parameters except for compound action potential (CAP) amplitude.
Conclusion: LLLT might be a subjectively effective treatment for short-term improvement of tinnitus. Defining a new protocol for optimizing LLLT parameters may be an option to improve parameters of objective tests.

Background: In recent years the use of low-power lasers has been widely used in medicine. With the introduction of affordable LED light, clinical application of LED light has become more and more popular. However, some researchers believe that because of the lack of coherence of the LED light, it can be different   in biological effects in comparison to laser. In this study, we compared the biological effects of low level laser to those of LED light. 

Methods: Human skin fibroblast cell line Hu02 was irradiated with low level laser and LED light with a wavelength of 660 nm, power output of 35 mW and in continuous mode and the control group was not irradiated.  The biological effects were compared through the analyzing of cell proliferation, production of reactive oxygen species within the cell and the rate of cell division.

Results: Our findings showed that production of reactive oxygen species within the cell was linearly increased both in the LED and laser light irradiated cells. However, laser light is more increment in comparison the LED light. The MTT results showed that laser light at low energy density (less than 5 joules per square centimeter) was increased the rate of cell proliferation after 24 hours. Although, the rate of cell division was increased in energy density of 1 J/cm2 compared to the control group, but this increasing was not statistically significant.

Discussion: The findings indicated that the coherence properties of laser light provided more energy for the cells, and in a constant energy density, laser light created more oxidative stresses in compared with LED light.

Background

The present study compared the effects of Er:YAG laser and hand instrumentation on the attachment of human gingival fibroblast (HGF) cells to periodontally involved root surfaces.

Methods

A total of 40 tooth specimens were collected and treated in four distinct groups: scaled and root planed with hand instruments, treated with Er:YAG laser, treated with combination of hand instruments and Er:YAG laser and non-treated control group. The attachment and proliferation rate of HGF were assessed using MTT assay and the Scanning Electron Microscope (SEM) Examination was used for cell morphological evaluation.

Results

The MTT assay showed significantly decrease in HGF cell viability in both hand instruments only and combination treated teeth specimens compared to control specimens (p<0.05), 24 hours after cell seeding. However, at time 48, the cell viability of attached cells in these two treated groups was almost similar to control.  In contrast, at 24 and 48 hours after cell seeding, viability of attached cells was higher than control in Er:YAG laser treated only specimens (p<0.05). According to SEM study, the laser treated specimens showed more surface roughness.

Conclusions

Er:YAG laser increased attachment and proliferation of HGF cells in comparison with hand instruments method.

Background: In recent years, the use of Ceramic base zirconia is considered because of chemical stability, biocompatibility, good compressive and flexural strength in dentistry for all ceramic restorations. However, due to its chemical stability, there is a challenge with dental bonding. Several studies have done to improving zirconia bonding but they are not reliable. Purpose of this research is a study of effect of plasma on bonding strength Zirconia.

 Methods: In this research zirconia blocks' surfaces polished with 1200grit sandpaper. Samples were processed with plasma of oxygen, argon, air and oxygen-argon combination with 90-10 and 80-20 ratio.  Surface modifications were evaluated by contact angle, surface roughness, and topographical assessments. Cylindrical Panavia f2 resin-cement and Diafill were used for micro shear strength bond measurements. The data analysis was performed by SPSS 20.0 software and one-way analysis of variance.

 Results: The results showed that plasma can increase micro cutting bond strength, decrease surface roughness, increase surface activation energy. Maximum cutting bond strength by using Panavia f2 cement, is for air and argon plasma, and by using margin bond and Diafill composition cement, is for air and combination of oxygen and argon with 20-80 ratio.

 Conclusion: According to this research plasmatic processing with dielectric barrier method in atmospheric pressure can increase Zirconia bonding strength.

Introduction: Today bleaching is a routine noninvasive alternative for treatment of discolored teeth. The concern has been raised whether or not oxidizing reaction during this process, might endanger integrity of the teeth and raise the risk of caries formation. The aim of this study was to determine whether conventional or laser activated bleaching predispose teeth to develop caries or not.

Methods:

Sixty human molars were mounted on acrylic cylinders and Knoop microhardness (KHN) and DIAGNOdent (DD) values of them were recorded. They were divided into four experimental groups; G1)conventional bleaching with 40% Hydrogen peroxide gel G2) Diode laser assisted bleaching with same gel. G3)Nd;YAG laser assisted bleaching with the same gel. G4)control group. After bleaching, all samples were subjected to a three day pH cycling regimen and then, KHN and DD values were measured.

Results:

All groups had significant reduction in KHN values. . It seems that there is no statistically meaningful difference between changes in enamel microhardness of sample groups and all groups have changed in a similar amount. Reduction of DD scores were significant in Diode laser and conventional groups, however changes in Nd:YAG laser and control groups were not significant. Changes in DD values have followed a similar pattern among groups, except in G1-G4 and G2-G4 couples. Conventional and Diode laser group had a meaningful difference in reduction of DD values in comparison with control group.

Conclusion:

It can be concluded that bleaching whether conventional or laser activated method, does not make teeth vulnerable to develop carious lesions.

Introduction: Sinus tracts (or fistulas) are a common manifestation of pulpal necrosis that requires conventional or rarely surgical- endodontic treatment in order to heal. They are mainly identified intraorally and in rare cases they manifest extraorally which may frequently be misdiagnosed and incorrectly treated. New technologies such as lasers have been developed as adjuncts to standard endodontic antimicrobial procedures in order to increase the success rate of endodontic therapy and complying the desire of saving a natural tooth.

Case presentation: Herein, we present a clinical case of extra oral sinus tract with Periodic pus drainage that was successfully treated by combining   conventional endodontic therapy, intra canal PDT and extra oral low level laser therapy.

Results and conclusion: Treatment of the odontogenic lesion among with the extra oral lesion was an ingenious and successful technique which was achieved by laser technology and winded up to patient’s consent and satisfactory results of treatment.