Laser Applications in Orthodontics

Somayeh Heidari, Sepideh Torkan

Journal of Lasers in Medical Sciences, Vol. 4 No. 4 (2013), , Page 151-158

A laser is a collimated single wavelength of light which delivers a concentrated source of energy. Soon after different types of lasers were invented, investigators began to examine the effects of different wavelengths of laser energy on oral tissues, routine dental procedures and experimental applications. Orthodontists, along with other specialist in different fields of dentistry, can now benefit from several different advantages that lasers provide during the treatment process, from the beginning of the treatment, when separators are placed, to the time of resin residues removal from the tooth surface at the end of orthodontic treatment. This article outlines some of the most common usages of laser beam in orthodontics and also provides a comparison between laser and other conventional method that were the standard of care prior to the advent of laser in this field.

Evaluation of Accuracy of DIAGNOdent in Diagnosis of Primary and Secondary Caries in Comparison to Conventional Methods

Hanieh Nokhbatolfoghahaie, Marzieh AliKhasi, Nasim Chiniforush, Farzaneh Khoei, Nassimeh Safavi, Behnoush Yaghoub Zadeh

Journal of Lasers in Medical Sciences, Vol. 4 No. 4 (2013), , Page 159-167

Introduction: Today the prevalence of teeth decays has considerably decreased. Related organizations and institutions mention several reasons for it such as improvement of decay diagnostic equipment and tools which are even capable of detecting caries in their initial stages. This resulted in reduction of costs for patients and remarkable increase in teeth life span. There are many methods for decay diagnostic, like: visual and radiographic methods, devices with fluorescence such as Quantitative light-induced fluorescence (QLF), Vista proof, Laser fluorescence (LF or DIAGNOdent), Fluorescence Camera (FC) and Digital radiography. Although DIAGNOdent is considered a valuable device for decay diagnostic, there are concerns regarding its efficacy and accuracy. Considering the sensitivity of decay diagnosis and the exorbitant annual expenses supported by government and people for caries treatment, finding the best method for early caries detection is of the most importance. Numerous studies were performed to compare different diagnostic methods with conflicting results. The objective of this study is a comparative review of the efficiency of DIAGNOdent in comparison to visual methods and radiographic methods in the diagnostic of teeth occlusal surfaces.

Methods: Search of PubMed, Google Scholar electronic resources was performed in order to find clinical trials in English in the period between 1998 and 2013. Full texts of only 35 articles were available.

Conclusion: Considering the sensitivity and specificity reported in the different studies, it seems that DIAGNOdent is an appropriate modality for caries detection as a complementary method beside other methods and its use alone to obtain treatment plan is not enough.

In Vitro Evaluation of the Effect of Different Laser Irradiations on the Enamel Surfaces of Teeth Treated with Home Bleach Procedure

Mahshid Mohammadi Bassir, Mohammad Bagher Rezvani, Nasim Chiniforush, Zohreh Moradi

Journal of Lasers in Medical Sciences, Vol. 4 No. 4 (2013), , Page 168-174

Introduction:The aim of this study was to evaluate the effect of dental surface treatment with Erbium-Doped Yttrium Aluminum Garnet(Er: YAG), Neodymium-Doped Yttrium Aluminium Garnet(Nd: YAG) and Carbon Dioxide Laser  (CO2) lasers and sodium ascorbate to recently home bleached enamel by scanning electron microscope (SEM).

Methods: Thirty extracted human third molars were selected for this in vitro study. The teeth were randomly divided in two groups including home bleached group and control group (non-bleached). In group 1, the samples were bleached by home bleach technique. No bleaching procedure was done in second the group which served as control group. Then, the samples of two groups were divided to five subgroups as follow:  Subgroup 1: treated using Nd:YAG laser with output power of 1 W, Subgroup 2: treated using Er:YAG laser with output power of 0.5 W, Subgroup 3: treated using CO2 laser with output power of 0.5 W, Subgroup 4: sodium ascorbate 10%, Subgroup 5: no treatment. After treatments, the surfaces were evaluated using Scanning Electron Microscope (SEM) analysis.

Results:The surfaces treated by Nd:YAG laser showed some melting and recrystallized areas and in some area droplet pattern was observed. But the surface treated by Er:YAG laser showed irregular and micro porous surface with flake pattern. CO2 laser treatment of home-bleached surfaces resulted in melting area and cracks. Sodium ascorbate did not change the home-bleached surface.

Conclusion:Among different surface treatments used in this study, it seems that Er:YAG laser can best interact with home-bleached teeth.

Temperature Distribution Simulation of the Human Eye Exposed to Laser Radiation

Seyyed Abbas Mirnezami, Mahdi Rajaei Jafarabadi, Maryam Abrishami

Journal of Lasers in Medical Sciences, Vol. 4 No. 4 (2013), , Page 175-181

Introduction: Human eye is a sensitive part of human body with no direct protection and due to its lack of protection against the external heat waves, studying the temperature distribution of heat waves on the human eye is of utmost importance. Various lasers are widely used in medical applications such as eye surgeries. The most significant issue in the eye surgeries with laser is estimation of temperature distribution and its increase in eye tissues due to the laser radiation intensity. Experimental and invasive methods to measure the eye temperature usually have high risks.

Methods: In this paper, human eye has been modeled through studying the temperature distribution of three different laser radiations, using the finite element method. We simulated human eye under 1064 nm Neodymium-Doped Yttrium Aluminium Garnet (Nd: YAG) laser, 193 nm argon fluoride (ArF) excimer laser, and 1340 nm Neodymium doped Yttrium Aluminum Perovskite (Nd: YAP) laser radiation.

Results: The results show that these radiations cause temperature rise in retina, lens and cornea region, which will in turn causes serious damages to the eye tissues.

Conclusion: This simulation can be a useful tool to study and predict the temperature distribution in laser radiation on the human eye and evaluate the risk involved in using laser to perform surgery.

The Effects of Low Intensity Laser on Clinical and Electrophysiological Parameters of Carpal Tunnel Syndrome

Seyed Mansoor Rayegani, Mohammad Hasan Bahrami, Darisuh Eliaspour, Seyed Ahmad Raeissadat, Mostafa Shafi Tabar Samakoosh, Leyla Sedihgipour, Elham Kargozar

Journal of Lasers in Medical Sciences, Vol. 4 No. 4 (2013), , Page 182-189

Introduction: Carpal Tunnel Syndrome (CTS) is the most common type of entrapment neuropathy. Conservative therapy is usually considered as the first step in the management of CTS. Low Level Laser Therapy (LLLT) is among the new physical modalities, which has shown therapeutic effects in CTS. The aim of the present study was to compare the effects of applying LASER and splinting together with splinting alone in patients with CTS.

Methods: Fifty patients with mild and moderate CTS who met inclusion criteria were included in this study. The disease was confirmed by electrodiagnostic study (EDx) and clinical findings. Patients were randomly divided into 3 groups. Group A received LLLT and splinting. Group B received sham LLLT+ splinting and group C received only splints. Group A received LLLT (50 mw and 880nm with total dose of 6 joule/cm2). Clinical and EDx parameters were evaluated before and after treatment (3 weeks and 2 months later).

Results: Electrophysiologic parameters and clinical findings including CTS provocative tests, Symptoms severity score (SSS), Functional Severity Score (FSS) and Visual Analogue Score (VAS) were improved in all three groups  at 3 weeks and 2 months after treatment. No significant changes were noticed between the three groups regarding clinical and EDX parameters.

Conclusion: We found no superiority in applying Low Intensity Laser accompanying splinting to traditional treatment which means splinting alone in patients with CTS. However, future studies investigating LLLT with parameters other than the one used in this study may reveal different results in favor of LLLT.

Histological Evaluation of Retina after Photo Disruption for Vitreous Humor by Q-Switched Neodymium-Doped Yttrium Aluminium Garnet (Nd:YAG) Laser

Sally Kameel Ghaly, Dina Foad Ghoneim, Salwa Ahmed Abdelkawi, Ahmed Medhat Abdel-Salam

Journal of Lasers in Medical Sciences, Vol. 4 No. 4 (2013), , Page 190-198

Introduction: Rabbits’ eyes were exposed to vitreous humor liquefaction with Q - switched (sometimes called " giant pulses") Neodymium-Doped Yttrium Aluminium Garnet (Nd: YAG) laser using two different energy protocols (5 mJ X 100 pulse and 10 mJ X 50 pulse) with and without vitamin C administration . The histological changes in the retina were investigated to evaluate the protective role of vitamin C.

Methods: The rabbits were divided into four main groups (n= 12 each). The first group was divided into three subgroups (n=4) and then treated with 5 mJ X 100 pulse (X means times) delivered to the anterior, middle and posterior vitreous humor respectively. The second group received a daily dose of 25 mg/Kg vitamin C for two weeks then was divided into three subgroups and treated with laser in the same manner as the first group. The third group was divided into three subgroups (n=4) and then treated with 10 mJ X 50 pulse delivered to the anterior, middle and posterior vitreous respectively. The fourth group received a daily dose of 25 mg/Kg vitamin C for two weeks then was divided into three subgroups and treated with laser in the same manner as the third group. After two weeks, rabbits were decapitated and histological examination for the retina was performed.

Results: The results showed that, the anterior vitreous group exposed to 5mJX100 pulse and supplemented with vitamin C, showed no obvious change. Furthermore, all other treated groups showed alteration in retina's tissues histology after laser.

Conclusion: Application of Q-switched Nd: YAG laser in vitreous humor liquefaction induces changes in retina's layers. Although there were some sorts of improvements in retinas supplemented with vitamin C, it cannot protect them against laser oxidative damage.

Introduction: Periodontal diseases are considered as some of the most common reasons of teeth loss, which occur due to the aggregation of microbial plaque and other precipitations on the dental surfaces. In this study, the scaling effect using manual tools, ultrasonic machine and Erbium-Doped Yttrium Aluminum Garnet (Er:YAG)laser on the connection of the human gums connective tissue cells on the root surface of the teeth suffering from severe periodontitis will be compared.  

Methods: After removal of the big precipitations with manual tools, Er:YAG laser light emission of Photona machine is used with respect to the following characteristics: wavelength: 2940μm, each pulse: 100mJ, frequency: 10 pulse/sec, optic fiber with cross section 0.5x1.65mm, fiber tip angle with root surface: 15-20 degrees with non-contact mode, 1.5mm farther than the root surface and pulse duration 230 very short. The gingival fibroblast cellular was incubated as a sample of the human gums connective tissue cells under 37C. These cells were departed from the culture medium after the cellular reproduction in the third passage.On the 3rd day after incubation, the gingival fibroblast cells morphology was studied by Scanning Electron Microscopy (SEM).

Results: The results of SEM images in the present study indicated the spread fibroblast cells with philopodia were found  in all of 5 groups; untreated healthy group (control), untreated group suffering from periodontitis, the scaling effect using manual tools (Scaled Gracey), ultrasonic machine and Er:YAG laser. There is a meaningful difference among the three treatment groups (P<0.001) in the numbers of the fibroblast cells, while all the four treated groups had a meaningful difference with the positive control group (P < 0.001).

Conclusion: The present study indicated that although various dental surfaces cleaning methods may be different in other aspects, but are similar concerning the fibroblasts morphology. Also in addition to power, laser emission time may also be effective in the cells morphology results.

Diode Laser Application in Soft Tissue Oral Surgery

Ehsan Azma, Nassimeh Safavi

Journal of Lasers in Medical Sciences, Vol. 4 No. 4 (2013), , Page 206-211

Introduction: Diode laser with wavelengths ranging from 810 to 980 nm in a continuous or pulsed mode was used as a possible instrument for soft tissue surgery in the oral cavity.

Discussion: Diode laser is one of laser systems in which photons are produced by electric current with wavelengths of 810, 940 and 980nm. The application of diode laser in soft tissue oral surgery has been evaluated from a safety point of  view, for facial pigmentation and vascular lesions and in oral surgery excision; for example frenectomy, epulis fissuratum and fibroma. The advantages of laser application are that it provides relatively bloodless surgical and post surgical courses with minimal swelling and scarring. We used diode laser for excisional biopsy of pyogenic granuloma and gingival pigmentation.

Conclusion: The diode laser can be used as a modality for oral soft tissue surgery