Octobert 2016 LITERATURE REVIEW

Compiled by Dr Igor Cernavin, Prosthodontist, Honorary Senior Fellow University of Melbourne School of Medicine, Dentistry and Health Sciences, Director and Cofounder of the Asia Pacific Institute of Dental Education and Research (AIDER), Australian representative of World Federation of Laser Dentistry (WFLD).

Roncati et al1 present an overview of a light emitting diode laser (835nm) and its effect on human gingival fibroblasts. The abstract is reproduced in full.

Since the laser and photomodulation were discovered over 50 years, they have been used for many applications in medicine and in dentistry also. In particular, light-emitting diodes therapy (LT) achieved a great success in medical treatment and photo-therapy. In the decades, LT has been used for several therapeutic purposes. Many beneficial effects have been demonstrated in vitro and in vivo, including antibacterial, antiviral, antitumor, cell differentiation, immune potentiating and tissue repair activities. Beneficial effects of LT have also been observed in clinical settings. Although there are lots of cell culture studies in low-level laser therapy, there are only a few cell culture studies in LT that have similar characteristics. The aim of this study was to investigate the effects of LT on primary human gingival fibroblast cells (HGF) on elastin (ELN) gene activation using Real Time PCR. ELN gene activation is directly connected with elastin protein production and HGF functionality. Human gingival tissue biopsies were obtained from three healthy patients during tooth extraction. The gingival specimens were fragmented with a scalpel and transferred in culture dishes containing Dulbeccos modified Eagle medium supplemented with 20% fetal calf serum (FBS) and antibiotics, i.e. penicillin 100U/ml and streptomycin 100mug/ml. Cells were incubated in a humidified atmosphere of 5% CO2 at 37C. The medium was changed the next day and twice a week. After 15 days, the samples of gingival tissue were removed from the culture dishes. Cells were harvested after an additional 24 h incubation. Human gingival fibroblasts at the second passage were seeded on multiple 6-well plates. The cells stimulation was performed with a light-emitting diodes (LEDs) medical device type E-Light. The LED irradiation seems to be directly correlated with the elastin (ELN) gene activation. Interestingly, ELN gene expression in the cultured human gingival fibroblasts seems to be inversely related to the patients age; in fact, its expressi on tends to decrease with aging. In summary, the result of the present study shows that LED irradiation promoted ELN gene expression more in elderly than in younger adults.

Moslemi and coworkers2 examined the effect of Er,Cr:YSGG laser on the microshear bond strength of self-adhesive flowable composite on permanent tooth dentin in vitro. They concluded that this composite had a lower microshear bond strength than conventional flowable composite and that laser irradiation as a surface treatment can improve it.

Blay et al3 investigated how a low-intensity laser affects the stability and reverse torque resistance of dental implants installed in the tibia of rabbits. They concluded that photobiomodulation using laser irradiation with wavelengths of 680 and 830 nm had a better degree of bone integration than the control group after 6 weeks of observation time.

Borzabadi-Farahani and Ali4 have published a systematic review of the effect of low-level laser irradiation on the proliferation of human dental mesenchymal stem cells.

Magaz et al5 evaluated the efficacy of adjunctive Er, Cr:YSGG laser application following conventional SRP. They concluded that adjunctive application of Er, Cr:YSGG laser following SRP did not improve probing pocket depth or attachment level compared with SRP alone.

Harris and coworkers6 used optical diffuse reflection spectroscopy to obtain absorption spectra for the periodontal pathogens, Porphyromonas gingivalis (Pg) and Prevotella intermedia. The abstract is reproduced in full.

It is commonly believed that pigmented pathogens are selectively targeted by dental lasers. To test this notion optical diffuse reflection spectroscopy (DRS) was used to obtain absorption spectra for the periodontal pathogens, Porphyromonas gingivalis (Pg) and Prevotella intermedia (Pi).MATERIALS AND METHODS: Spectra from 400 to 1,100nm wavelengths of Pg colonies cultured with different concentrations of hemin were obtained to test the hypothesis that “visual pigmentation” predicts absorption of near-infrared (IR) dental laser energy. Ablation threshold at 1,064nm [1] was measured for the pathogenic fungus, Candida albicans (Ca).RESULTS: The hypothesis was demonstrated to be true at 810nm, it was false at 1,064nm. Diode laser (810nm) efficacy and “depth of kill” is dependent on hemin availability from 400 to about 900nm. Pg and Pi absorption at 1,064nm (a =7.7±2.6cm(-1) ) is independent of hemin availability but is determined by another unknown chromophore. Ca is non-pigmented but very sensitive to 1,064nm irradiation.CONCLUSIONS: The amount of visual pigmentation does not necessarily predict sensitivity to dental laser irradiation. Spectra in visible and near-IR wavelengths demonstrate a large difference in absorption between soft tissue and Pg or Pi. This difference represents a host/pathogen differential sensitivity to laser irradiation, the basis for selective photoantisepsis.

Rios et al7 measured the temperature of the dental implant surface irradiated with high-power diode laser. The abstract is reproduced in full.

The prevalence of peri-implantitis and the absence of a standard approach for decontamination of the dental implant surface have led to searches for effective therapies. Since the source of diode lasers is portable, has reduced cost, and does not cause damage to the titanium surface of the implant, high-power diode lasers have been used for this purpose. The effect of laser irradiation on the implants is the elevation of the temperature surface. If this elevation exceeds 47 °C, the bone tissue is irreversibly damaged, so for a safety therapy, the laser parameters should be controlled. In this study, a diode laser of GaAsAl was used to irradiate titanium dental implants, for powers 1.32 to 2.64 W (real) or 2.00 to 4.00 W (nominal), in continuous/pulsed mode DC/AC, with exposure time of 5/10 s, with/without air flow for cooling. The elevation of the temperature was monitored in real time in two positions: cervical and apical. The best results for decontamination using a 968-nm diode laser were obtained for a power of 1.65 and 1.98 W (real) for 10 s, in DC or AC mode, with an air flow of 2.5 l/min. In our perspective in this article, we determine a suggested approach for decontamination of the dental implant surface using a 968-nm diode laser.

Park and coworkers8 published a report of an Osteonevus of Nanta, a melanocytic nevus displaying secondary ossification and carrying a potential for malignancy following laser ablation. The abstract is reproduced in full.

Osteonevus of Nanta is a melanocytic nevus displaying secondary ossification and carrying a potential for malignancy. A solitary occurrence is reported herein, presenting as a flesh-colored papule following laser ablation.A 56-year-old woman sought treatment for a minor papular growth of the cheek. This lesion had developed at the site of prior CO2 laser ablation done elsewhere to eradicate a pigmented nevus. The patient’s medical records and histopathology report were obtained after surgical excision.Histologically, a completely excised osteonevus of Nanta was evident, marked by an intradermal nevus with subjacent osseous metaplasia. Clinical presentations of these lesions may vary, but the potential for malignancy remains.

Alshehri et al9 published an the indexed literature review regarding the efficacy of laser therapy in the treatment of peri-implantitis and concluded that laser therapy can significantly reduce levels of clinical markers of peri-implant tissue inflammation.

Minamisako and coworkers10 concluded that low level laser therapy and photodynamic therapy are important tools in the treatment of MRONJ (formally called BRONJ).

References

1. Roncati, M; Lauritano, D; Cura, F; Carinci, F. Evaluation of light-emitting diode (LED-835 NM) application over human gingival fibroblast: an in vitro study. Journal of biological regulators and homeostatic agents, 30 (2 Suppl 1):161-7; 2016 Apr-Jun.
2. Moslemi, Masoumeh; Fotouhi Ardakani, Faezeh; Javadi, Fatemeh; Khalili Sadrabad, Zahra; Shadkar, Zahra; Shadkar, Mohammad Saeid.
Evaluation of Er,Cr:YSGG Laser Effect on Microshear Bond Strength of a Self-Adhesive Flowable Composite in the Dentin of Permanent Molar: An In Vitro Study. Scientifica, 2016 4856285; 10.1155/2016/4856285 2016.
3. Blay, Alberto; Blay, Claudia C; Tunchel, Samy; Gehrke, Sergio Alexandre; Shibli, Jamil Awad; Groth, Eduardo B; Zezell, Denise M.
Effects of a Low-Intensity Laser on Dental Implant Osseointegration: Removal Torque and Resonance Frequency Analysis in Rabbits. The Journal of oral implantology, 42 (4):316-20; 10.1563/aaid-joi-D-15-00064 2016-Aug.
4. Borzabadi-Farahani, Ali. Effect of low-level laser irradiation on proliferation of human dental mesenchymal stem cells; a systemic review. Journal of photochemistry and photobiology. B, Biology, 162 577-82; 10.1016/j.jphotobiol.2016.07.022 2016-Sep.
5. Magaz, Vanessa Ruiz; Alemany, Antonio Santos; Alfaro, Federico Hernandez; Molina, Jose Nart. Efficacy of Adjunctive Er, Cr:YSGG Laser Application Following Scaling and Root Planing in Periodontally Diseased Patients. The International journal of periodontics & restorative dentistry, 36 (5):715-21; 10.11607/prd.2660 2016 Sep-Oct.
6. Harris, David M; Jacques, Steven L; Darveau, Richard. The Black Bug Myth: Selective photodestruction of pigmented pathogens. Lasers in surgery and medicine, 48 (7):706-14; 10.1002/lsm.22545 2016-Sep.
7. Rios, F G; Viana, E R; Ribeiro, G M; Gonzalez, J C; Abelenda, A; Peruzzo, D C. Temperature evaluation of dental implant surface irradiated with high-power diode laser. Lasers in medical science, 31 (7):1309-16; 10.1007/s10103-016-1974-z 2016-Sep.
8. Park, Seong Hoon; Kim, Joo Hyun; Lee, Byeong Ho; Suh, In Suck; Kim, Jeong Won; Jeong, Hii Sun. Osteonevus of Nanta Presenting as Flesh-Colored Papule of Cheek Following Laser Ablation. The Journal of craniofacial surgery, 27 (6):e543-4; 10.1097/SCS.0000000000002859 2016-Sep.
9. Alshehri, Fahad Ali. The role of lasers in the treatment of peri-implant diseases: A review. The Saudi dental journal, 28 (3):103-8; 10.1016/j.sdentj.2015.12.005 2016-Jul.
10. Minamisako, Mariana Comparotto; Ribeiro, Guilherme Henrique; Lisboa, Mariah Luz; Mariela Rodriguez Cordeiro, Mabel; Grando, Liliane Janete. Medication-Related Osteonecrosis of Jaws: A Low-Level Laser Therapy and Antimicrobial Photodynamic Therapy Case Approach. Case reports in dentistry, 2016 6267406; 10.1155/2016/6267406 2016.

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