Lasers in Dental Science

Photobiomodulatory effect delivered by low-level laser on dental pulp stem cell differentiation for osteogenic lineage Abstract Background Photobiomodulation (PBM) therapy has attracted major interest in the field of tissue engineering as it can enhance stem cell differentiation. It has been shown that PBM therapy can stimulate differentiation of cells in culture by exerting biomodulatory effect. Recent evidences show that PBM therapy can positively modulate dental pulp stem cell (DPSC) properties. Combination of PBM therapy with growth factors and biomaterials can possibly accelerate osteogenic differentiation of dental pulp stem cells. Aims To evaluate the biomodulatory effect of low-level laser dose on dental pulp stem cells in the presence of hydroxyapatite-based scaffold particle for osteogenic differentiation. Materials and methods DPSCs were harvested from human premolar teeth and expanded using mesenchymal stem cell medium. Characterization of DPSCs was done using fluorescence-activated cell sorting with CD105, CD44, CD34, and CD45 markers. Cultured DPSCs along with the N-acetylcysteine-labeled hydroxyapatite (NAC-HA) particles and osteogenic differentiation media were exposed to gallium-aluminum-arsenide (Ga-Al-As) diode laser at 810 nm. Cells were divided into 3 groups: L1 (single exposure), L2 (double exposure), and control (no exposure). Osteodifferentiation after PBM therapy was assessed using Alizarin red S staining, Alkaline phosphatase activity (ALP), and by osteopontin expression. Differences between groups at each time point were analyzed using the Mann–Whitney U test. A level of significance of 5% was adopted (p < 0.05). Results DPSCs grown on NAC-HA polymers show increased cell adhesion and proliferation. Double irradiated groups were consistent with increased calcium (71%) and alkaline phosphatase activity (75%) when compared with single-irradiated groups. mRNA expression of osteopontin was relatively increased in a significant (p < 0.001) manner in L2 when compared with L1 group. Alizarin red S and ALP positive staining confirmed the presence of calcium deposition in the test samples. The osteopontin expression of L2 (216.681) as compared with L1 (123.276) group prove the efficacy of double exposures over a single dose of PBM therapy. Conclusion The result envisages the enhanced osteogenic potential of PBM therapy on the differentiation of DPSCs in NAC-HA scaffolds. Double exposure of PBM therapy expresses better biomodulatory effect on DPSCs as compared with the single dose.

Efficacy of adjunctive Er,Cr:YSGG laser application to scaling and root planing in periodontal maintenance patients with residual periodontal pockets Abstract Purpose The aim of this study was to evaluate the efficacy of using Er,Cr:YSGG laser in an adjunct to scaling and root planing (SRP + Er,Cr:YSGG) in periodontal maintenance patients with residual periodontal pockets. Materials and methods This study is a double-blind randomized controlled clinical trial and a split-mouth design. Fifteen periodontal maintenance patients with two single-rooted teeth with probing depth (PD) ≥ 5 mm in two different quadrants were randomly assigned to scaling and root planing (SRP) as a control group or SRP + Er,Cr:YSGG as test group. Plaque index (PI), bleeding on probing (BOP), PD, relative probing attachment level (RPAL), and relative gingival recession (RGR) were evaluated at baseline, 3 months and 6 months after treatment by one calibrated examiner. Results At 6 months after treatment, PDs were statistically significantly reduced in both SRP (0.9 ± 0.6 mm) and SRP + Er,Cr:YSGG (1.1 ± 0.7 mm) compared with pretreatment PD (p < 0.05). Only SRP + Er,Cr:YSGG demonstrated statistically significant probing attachment level (PAL) gained at 6 months after treatment (0.8 ± 0.6 mm; p < 0.05). Gingival recession (GR) statistically significantly increased in SRP + Er,Cr:YSGG 3 months after the treatment (0.5 ± 0.5 mm; p < 0.05). Nevertheless, there were no statistically significant differences between the 2 treatment modalities regarding PD reduction, PAL gain, or GR at 6 months after treatment. Conclusions Only SRP + Er,Cr:YSGG demonstrated statistically significant PAL gained at 6 months after treatment (0.8 ± 0.6 mm; p < 0.05); however, there were no statistically significant differences between the 2 treatment modalities regarding PD reduction, PAL gain, or GR at 6 months after treatment in maintenance patients with residual periodontal pockets.

Hyperspectral imaging system associated with novel subtracting image processing algorithm for dental caries early detection Abstract Objective Early detection of caries is vital for demineralization reverse offering a less pain, as well as accurate and precise caries removal. Materials and Methods In this study, the difference in optical properties of normal tissue and human caries lesion has been used for early diagnosis, using laser induced fluorescence spectroscopy. The human tooth sample was illuminated with visible band sources (488, 514 and 633 nm) with power 5 mW. The reflected and emitted light of tested sample was collected using hyperspectral camera in an attempt to generate multispectral images (cubic image). The variation of reflected and emitted power as function in wavelength was employed to generate characteristic spectrum of each tooth tissue. Human teeth caries tissue lesion releases its excess power by emitting fluorescence light producing chemical footprint signature; this signature is dependent on the elemental composition of tooth elements and caries state. Results This non-invasive, non-contact and non-ionizing imaging system with associated novel pattern recognition algorithm was employed to diagnose and classify dental (enamel and dentin), caries, and white spot lesion. It was reported that the perceived fluorescence emission is function of the illuminating wavelength. While enamel and dentin caries were distinguished and characterized at 633 nm illuminating wavelength; white spot lesion cannot be detected. The enamel caries, dentin caries, and white spot lesion were contoured and recognized at 488 nm and 514 nm wavelengths. Therefore full recognition was achieved through generated cubic image after sample irradiation at 488 nm and 514 nm. Conclusions This non-invasive, non-contact, and non-ionizing imaging technique with customized image processing algorithm offered high sensitivity, high resolution, and early caries detection with optimum performance at 514 nm.

Comparison between the effect of low-level laser therapy and corticotomy-facilitated orthodontics on RANKL release during orthodontic tooth movement: a randomized controlled trial Abstract Objective Bone resorption is the cornerstone in bone remodeling affecting the rate of orthodontic tooth movement. RANKL has a direct effect on osteoclastogenesis. The aim of this study is to evaluate and compare the effect of low-level laser therapy (LLLT) and corticotomy-facilitated orthodontics (CFO) on RANKL release during orthodontic tooth movement. Materials and methods Twenty patients requiring orthodontic therapeutic extraction of the maxillary first premolar were randomly selected. A split-mouth study design was performed where corticotomy-facilitated orthodontics was randomly assigned to one side at the canine region (CG) before retraction, Laser group (LG) was assigned to the contralateral side using 940 nm diode laser irradiations (100 mW, 2.5 J, 3.9 J/cm2) at days 1, 3, 8, and 15. Canine retraction was done using nickel-titanium closed-coil spring applying a force of 150 g per side. Gingival crevicular fluid (GCF) samples were collected from distal surface of the canines on both sides, 1 day before the intervention treatment (T0), day 3 after the intervention (T1), and day 15 (T2). RANKL concentration levels were assessed using enzyme-linked immunosorbent assay. Results There was statistically significant increase in RANKL concentration levels in both groups (CG and LG) from T0 to T1, there was no statistically significant difference in concentration level from T1 o T2, but there was a statistically significant difference in RANKL concentration levels between T0 and T2 in both groups. CG and LG showed no statistically significant difference in RANKL concentration levels between them in T1 and T2. Conclusions Low-level laser therapy and corticotomy-facilitated orthodontics can increase the RANKL release during orthodontic tooth movement which directly affects bone remodeling and the rate of orthodontic tooth movement.

Effect of photobiomodulation on pain perception secondary to separator placement Abstract Purpose Pain associated with orthodontic treatment is often one of the reasons for dropout during fixed orthodontic treatment. The aim of the present study was to assess the effect of photobiomodulation on pain during the initial phase of orthodontic treatment. Methods A single blind study using a split mouth design was carried out on 24 subjects requiring fixed orthodontic treatment in the age group of 13 to 20 years. The subjects were randomly divided into two groups and elastomeric separators were placed on the mesial and distal aspects of upper and lower first molars. Further, they were subjected to laser irradiation (Photon plus diode laser®, Zolar Technology and Mfg. Co. Inc. Canada, InGaAs based diode laser 980 nm, 100 mW, continuous wave mode) and simulations at four points, i.e. the interdental papilla on the buccal and lingual/palatal aspect mesially and distally accordingly for 10 s each. The subjects were asked to score their pain intensity on a visual analogue scale (VAS) at 5 min, 24 and 48 h post separator placement. Results The mean score for pain perception for the lased group was significantly lower than the placebo group at both 24 and 48 h. However, no appreciable difference was seen at 5 min post placement. Conclusion Although a single dose of photobiomodulation subsequent to separator placement does not provide immediate relief, it is significantly effective in reducing pain at 24 and 48 h. However, there was no association of age with pain perception.

Evaluation of the bactericidal potential of 2780-nm ER,CR:YSGG and 940-nm diode lasers in the root canal system Abstract Purpose Successful endodontic therapy relies on chemomechanical debridement. Laser-assisted irrigation techniques are available for debridement. However, there are limited studies demonstrating the effectiveness of dual lasers for root canal disinfection. Hence, the aim of the present study is to determine if laser activation irrigation using the Er,Cr:YSGG and 940-nm diode laser is as effective as positive pressure needle irrigation using sodium hypochlorite (NaOCl) and ethylenediamine tetraacetic acid (EDTA). Methods Fifty-two caries-free premolars were divided into six groups: G1, sterile water via positive pressure irrigation; G2, EDTA and NaOCl via positive pressure irrigation; G3, sterile water and the Er,Cr:YSGG cleaning and disinfection step; G4, sterile water and the Er,Cr:YSGG cleaning and disinfection step followed by disinfection with the 940-nm diode; G5, sterile water and the Er,Cr:YSGG cleaning step followed by a disinfection step with the Er,Cr:YSGG and diode laser together; and G6, negative controls. S1 samples were validated in both negative and positive control groups via culturing. All teeth, except the negative controls, were inoculated with Enterococcus faecalis. S2 sampling after treatments was completed and tested for bacterial presence via culturing and SEM and CLSM analysis. Results The data demonstrated that the traditional irrigation group (G2) and the dual laser group (G5) showed the greatest percentage decrease in bacterial counts from the S1 to the S2 group. Conclusions The data demonstrates that the combination of the Er,Cr:YSGG and 940-nm diode laser wavelengths is safe and more effective than either laser alone and is comparable to needle irrigation with sodium hypochlorite and EDTA.

Effects of carbon dioxide lasers on preventing caries: a literature review Abstract Purpose This study aimed to review the effects of carbon dioxide lasers (λ = 10,600 nm) on preventing dental caries. Methods A systematic search was performed of articles published in English through 2018 and archived in the PubMed, Scopus, and Web of Science databases. The keywords used to identify the relevant publications were ((CO2laser) OR (carbon dioxide laser)) AND ((dental caries) OR (tooth remineralization)). The titles and abstracts of the initially identified publications were screened. Duplicate records, case reports, reviews, and irrelevant studies were removed. Full texts that focus on the effects of carbon dioxide lasers on preventing dental caries were retrieved from publications. Results The search identified 543 potentially relevant publications. A total of 285 duplicate records were removed. Twenty-two articles investigating the effect of carbon dioxide lasers on enamel and dentin were included. Results of the studies showed that carbon dioxide lasers could cause chemical and morphological changes to mineralized tissues, including reduction of carbonate content and recrystallization of mineral structure. All studies showed that carbon dioxide lasers increased the microhardness and decreased the mineral loss of enamel (nine studies) and dentin (three studies). Two out of eight studies showed increased resistance to demineralization of enamel after carbon dioxide laser and fluoride treatment. All studies revealed that carbon dioxide laser and fluoride treatment reduced mineral loss of dentin against acid challenge. Conclusions Carbon dioxide (10,600 nm) lasers can prevent demineralization of enamel and dentin. Furthermore, they have a synergistic effect with fluoride in preventing dentin caries.

Different laser approaches in treatment of peri-implantitis: a review Abstract Introduction Peri-implantitis (PI) is one of the peri-implant diseases that causes destructive inflammatory process of the hard and soft tissues surrounding the implant. Recently, several types of lasers have been proven to be effective in PI. Despite the increase of scientific publications on laser treatment in PI, the best type of laser treatment is not evaluated until now. The primary aim of our systematic review is to provide a comprehensive review on the effect of different types of lasers that were used as a treatment modality for patients with peri-implantitis concerning the most effective type of laser in this field. Material and methods We used databases from scientific websites such as PubMed/Medline, Scopus, and Google Scholar to get related articles about this subject. The research process involved specific key words "peri-implantitis"-laser treatment"-peri-implantitis treatments". We were more concerned about English human published studies including clinical trials, case-control, and case series of laser therapy in peri-implantitis. Results Our initial research yielded 174 articles. After scanning and screening the published articles, we excluded 152 articles; in total, 22 articles were included in this review. Conclusion We concluded that the determination of the optimal laser treatment for peri-implantitis is recondite due to the disharmony of results that have been documented. However, if lasers are not used according to proper protocols with proper temperatures, a damage can occur to the implant and peri-implant tissues.

Intraoral versus extraoral single-session photobiomodulation therapy after lower third molar surgery: a pilot study Abstract Purpose To compare the effects of intraoral or extraoral single-session photobiomodulation therapy (PBMT) in maximum incisal opening (MIO), edema, and pain after lower impacted third molar surgery. Study design A randomized crossover clinical trial was performed in healthy patients with bilateral lower third molar extraction need. Randomization defined the surgery side (right or left), group [intraoral (IL) or extraoral (EL)], and treatment (actual or placebo) by using a computer program. IL actual group received GaAlAs red laser irradiations at four intraoral points. EL actual group received infrared laser at four extraoral points. For the placebo groups, the laser equipment was kept off. The washout period was 30 days. Before and after each surgery, facial point distances evaluated maximum incisal distance (MIO) and edema. A visual analogical scale assessed pain at 4, 8, 24, and 48 h after surgery. Results Postoperative pain levels and edema were similar between the groups. MIO was significantly higher in the actual EL at 7 days after surgery. Conclusions Intraoral and extraoral single sessions of PBMT after lower third molar surgery are equally able to control pain and edema. Moreover, a single session of extraoral PBMT is more efficient in improving postoperative mouth opening.

Clinical evaluation of a fluoride gel, a low-level laser, and a resin varnish at the treatment of dentin hypersensitivity Abstract Purpose This clinical trial aims to evaluate in vivo the efficacy of a fluoride gel, a low-level laser (LLL), and a resin varnish at the treatment of dentin hypersensitivity (DH). Treatments assessed for their effectiveness, immediate analgesia, and duration of desensitization. Material and methods A total of 78 patients (one tooth per patient) with a clinical diagnosis of dentin hypersensitivity were included in this clinical trial. Dentin sensitivity in response to an air blast stimulus was assessed, and a Numeric Rating Scale (NRS) for pain from 0 to 10 was chosen to quantify pain at baseline and 15 min, 1 month, and 3 months after the first application. Patients were randomly divided into three groups. In the first group (treatment A, 26 patients), a fluoride gel (Calmodent Professional, Intermed, Greece) was applied. In the second group (treatment B, 26 patients), teeth were irradiated by a 670-nm InGaAlP continuous wave, red diode laser (MED-701, Lasotronic, Switzerland) with an output power of 180 mW, energy of 5.4 J, and irradiation time of 30 s. In the third group (treatment C, 26 patients), a resin varnish with giomer technology (PRG Barrier Coat, Shofu, Japan) was applied. Results The main analysis of the results was done with a linear mixed model (algorithm MIXED, IBM Statistics SPSS 21.0), while pairwise comparisons were conducted with the Bonferroni method. The statistical significance for all tests was set at p < 0.05. The main effects of time and group were found to be statistically significant. The time × group interaction effect was also statistically significant, and finally, a significant reduction (p < 0.05) of DH was recorded in all groups, compared with baseline. Conclusion All three treatments offered satisfactory and prolonged results.

Alexandros Sfakianakis
Anapafseos 5 . Agios Nikolaos
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alsfakia@gmail.com