Tooth movement alterations by different low level laser protocols: a literature review

Low-Level Laser Therapy [LLLT] provides several benefits for patients receiving orthodontic treatment. According to some literatures, Orthodontic Tooth Movement [OTM] can be enhanced but some investigators have reported contradictory results. This article reviews the literature regarding the different aspects of the use of LLLT on OTM and its alterations. The general data regarding the study design, sample size, wavelength [nm], power [mW], and duration were extracted and recorded independently. Electronic databases of PubMed and ScienceDirect from January 2009 to August 2014 were searched. Also Google Scholar and grey literature was searched for relevant references. Some investigators found that the amount of tooth movement in the Low-Energy Laser Irradiation [LELI] group was significantly greater than in the non-irradiation group by the end of the experimental period. Low-level laser irradiation accelerates the bone remodeling process by stimulating osteoblastic and osteoclastic cell proliferation and function during orthodontic tooth movement. But some researchers have reported that no statistical differences in the mean rate of tooth movement were noted between low energy and high energy experimental sides and their controls. Some evidence shows that low-level laser irradiation accelerates the bone remodeling process and some evidence shows that LLLT has not effect on OTM. In some investigations no statistical differences in the mean rate of tooth movement can be seen between low energy and high energy experimental sides and their controls. It has been shown by authors that laser irradiation can reduce the amount of OTM and a clinical usage for the inhibitory role of low level laser irradiation is enforcing the anchorage unit

808 nm laser-assisted surgery as an adjunct to orthodontic treatment of delayed tooth eruption

Failure of teeth to erupt from gingival tissues at usual developmental time is called delayed tooth eruption [DTE]. Delayed tooth eruption lead to prolonged fixed orthodontic treatment and its eventual complications. The purpose of the present study was to evaluate the effect of laser-assisted [808 nm] surgical uncovering, on the tooth emergence and orthodontic treatment of DTE. A total of 16 orthodontic patients were included in this study and were equally assigned to an experimental and a control group. Subjects for experiment consisted of eight patients [6 girls and 2 boys] with a mean age of 14 +/- 0.9 years. All patients exhibited delayed second premolar eruption. The laser wavelength was 810 nm and it was set in a continuous wave mode at a power output of 1.6 watt with a 0.3-mm diameter fiber tip. When the target tissue was sufficiently anesthetized, the tip was directed at an angle of 10 to 20 degrees to the tissue [light contact mode]; and was applied continuously for approximately 12 Seconds until an acceptable tooth exposure area was visible. The facial axis of the clinical crown [FACC] line represents the most prominent portion of the facial central lobe for premolars. All orthodontic brackets are aligned along this reference and are located on FA [Facial Axis] point. The standard for adequate tooth eruption was the accessibility of facial axis of the clinical crown [FACC] for bonding the brackets. Data gathered from the patients were statistically surveyed and compared by means of Tukey's Test and Analysis of Variance [ANOVA]. All patients showed good gingival status, no significant bleeding during or immediately after the surgery, and acceptable level of healing after laser surgery. The biologic width of the teeth was preserved and no violation of this important periodontal parameter was observed. The average time for accessing the FA point in experimental group was 11 +/- 1.1 weeks and the mentioned period was increased to 25 +/- 1.8 weeks in control group. The data analysis showed that in patients with DTE, laser intervention significantly accelerated tooth eruption [P < 0.05]. Laser-assisted surgical removal of the fibrous tissue over erupting premolars [DTE] with appropriate irradiation parameters appears to be a promising adjunct to orthodontic treatment for bringing the premolar to the aligned and leveled dental arch

[Alkaline phosphatase activity level of osteoblast cells on three-dimensional chitosan-gelatin/hydroxyapatite composite scaffolds]

In recent years, composite scaffolds made of polymers and bioactive ceramics have found numerous applications in bone tissue engineering due to their superior properties. Among various polymers, chitosan [Cs] and gelatin [Gel] gained more attention because of their desirable properties. In this study, by using these two polymers and hydroxyapatite [HA] which resembles inorganic phase of human bone, three-dimensional composite scaffolds were prepared by freeze-drying method and behavior of osteoblast cells on them was evaluated. This study aimed at preparing an appropriate bioactive scaffold for bone tissue engineering. In order to evaluate the effect of gelatin concentration on biological properties of scaffolds, three different concentrations of gelatin [0, 10, and 20%] were added to composite scaffolds. For assessment of the biological properties of scaffolds, osteoblast cells were cultured on the composite scaffolds and their behavior was monitored. Scanning electron microscopy [SEM] analysis and alkaline phosphatase activity [ALP] test were carried out to assess the mentioned factors. SEM analysis showed high cell attachment and proliferation on the scaffolds. Alkaline phosphatase activity of osteoblast cells indicated the suitability of composite scaffolds containing a higher concentration of gelatin compared to other concentrations as well as overall high activity of osteoblast cells on all scaffolds. Cs/Gel/HA bioactive composite scaffold is recommended for bone tissue regeneration purposes as a suitable scaffold

Study motives and career choices of Iranian medical and dental students

To compare the study motives and career choices of senior undergraduate medical and dental students in Iran. A cross-sectional questionnaire-based survey study involving final year medical and dental students from 4 dental and medical schools was conducted in 2010. The questionnaire was designed in three sections [Demographic details, motivational items and career choice items] and after confirming the validity and reliability of the questions, it was distributed among the students. Data were entered into SPSS; statistical analysis included logistic regression and multiple linear regression. The response rate was 62% [n=219] for medical and 64% [n=300] for dental students. The factor analysis identified six motivational items: "Social and professional status", "Health care and people", "Others' recommendation", "personal interest and nature of occupation", "Occupational experience" and "Personal life". Medical students were more influenced by "Playing a role in community health" and "Personal interest". "Work independence" and "Social factors" however were two major influential factors among dental students. There were significant differences in important influences by age [Social and professional status, Others' recommendation], Parents' education [Social and professional status, Health care and people, Personal life] and marital status [single >married: Occupational experience, married > single: Personal life]. Engaging in postgraduate studies was the first career preference among 90.9% and 89.8% of dental and medical students respectively. Medical and dental students report a wide range of motivational factors in studying medicine/dentistry and future career plans which is affected by age, parents' education and marital status

Effect of vitamin C on salivary total antioxidant capacity in smokers

This study was designed to elucidate the effect of ascorbic acid on salivary total antioxidant capacity in smokers. In this single blind crossover clinical trial, the whole unstimulated saliva of 30 smokers, who were randomly divided into two groups, was collected. In the first phase after the saliva collection, one group of patients took 500 mg of vitamin C powder, for 3 weeks. Then, saliva of all patients was collected. After a one-week wash-out period, vitamin C was given to the other group. The collection of saliva was done after 3 weeks. Total antioxidant capacity was measured. Statistic evaluation was performed by Repeated Measured ANOVA, Independent sample t-test and Covariate test. The mean of total antioxidant capacity with and without using vitamin C was 0.511 +/- 0.155 [U/mL] and 0.555 +/- 0.171 [U/mL], respectively. This variability was not significant [p = 0.605]. Oxidative stress from cigarette smoke was not decreased significantly with using vitamin C

Accuracy of the methodology section of graduate and post-graduate theses in Shahid Beheshti medical university, school of dentistry from March 2009 to October 2011

The purpose of this study was to investigate the histologic interaction Theses are among the most important research sources of the universities and should be authored according to the international standards of scientific writing. The present study aimed at determining the accuracy of the methodology section of graduate and post-graduate theses conducted in Shahid Beheshti Medical University, School of Dentistry from March 2009 to October 2011. In this descriptive cross-sectional study all approved theses of the Shahid Beheshti Medical University, School of Dentistry from March 2009 to October 2011 were evaluated according to the international check lists. For data analysis, SPSS version 16.0 software, ANOVA and independent ttest were used. A total of 101 theses with observational design and 72 with experimental design were evaluated. The mean conformity of observational theses with STROBE check list was 75%. The highest conformity was observed in the complete description of inclusion and exclusion criteria [95%] while the lowest conformity was observed in the bias control [48%]. The mean conformity of the interventional theses with all the items of CONSORT checklist was 62%. The highest conformity was found in complete description of the type and process of intervention [90.3%] whereas the lowest conformity was found in allocation concealment mechanism [88%]. No significant correlation was found between the presence of a consulting professor and academic ranking of the thesis instructor and the mean score of thesis. In observational theses, the lowest conformity was observed in the description of the bias control; whereas, in interventional theses the lowest conformity was detected to be in allocation concealment mechanism

Lack of interleukin 1-beta expression following orthodontic induced root resorption

To determine the effect of orthodontic tooth movement on the expression of interleukin-1beta mRNAin rats using RT-PCR. Sample consisted of eighteen 8-week-old male Wistar rats. The right maxillary first molar of each animal was protracted using an orthodontic protraction appliance. The left maxillary first molar received no treatment and was assigned as the control group. On day 21, all rats were sacrifice and divided in two equal groups. The first group, group [A], was histologically evaluated for the presence and size of potential resorptive lacunae. The second group, group [B], was investigated using RT-PCR in order to determine IL-1beta mRNA expression. Measurements revealed that the mean tooth movement was 0.23 mm in group A and 0.24 mm in group B. The mean depth of the resorptive lacunae was 0.17*10[-11] mm[2] in the control group and 4.9x10[-11] mm[2] in the intervention group [control group: left maxillary first molars; right maxillary first molars were divided to group A and B, histologic study of group A assures the existence of resorptive lacunae and its extent relative to control group]. The difference between the two groups was statistically significant [p<0.05]. The RT-PCR evaluation showed no significant differences in IL-1beta mRNA expressions of resorptive lacunae between the treated and untreated groups. Although interleukinl-beta is the most potent stimulator of bone resorption and mediator of inflammatory response, the present study showed that the IL-1 beta mRNA was not expressed more significantly in root resorption lacunae of the treated molars relative to the control group

Immediate relief of TMJ clicking following low level laser therapy after orthodontic treatment a case report

To determine efficacy of low level laser therapy for clicking temporomandibular joint [TMJ] with a diode laser following orthodontic treatment. Performance of LLLT with a diode laser for temporomandibular clicking and postoperative findings were evaluated in a case of an orthodontic patient following the termination of treatment. Patient had a history of severe clicking before initiation of treatment protocol. Low level diode laser [wave length 808 nm, power 0.7 watt, Time 60 seconds], applied for the purpose of relieving the signs. During the process of intervention and establishing the proper dental occlusion sign of temporomandibular joint dysfunction i.e. clicking reduced significantly [p<0.05] but remained at the lowest level from the perspective of frequency and severity index. Patient had no sign and symptom at the end of treatment. Clicking was reemerged in the retention period, i.e. after six months. Clinical signs disappeared immediately after the application of laser once [p<0.05] with no recurrence after four months follow up. Low level laser therapy serves as an adjuvant to orthodontic treatment while establishing the proper occlusion of stomatognathic system has pivotal role in function and stability of outcome