Laser Applications in Orthodontics

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

Evaluating the effect of low energy laser irradiation on the rate of mandibular molar protraction in orthodontic patients

Background: Low level laser is a type of laser with various bio stimulatory effects; Potential effects of laser in accelerating bone regeneration and consequently facilitating tooth movement have been considered widely in orthodontics. Aims & Objectives: Aim of this study was to assess the effects of Low level laser on the velocity of mandibular first molar protraction in orthodontic patients. Materials and Methods: Total 28 young adult patients (14 females and 14 males; age range 16-25) requiring extraction of mandibular second premolars were selected and molar protraction was carried out with T-loop on a rectangular Stainless Steel wire. In each patient one side was selected by random to irradiate with low level laser and other side with placebo. Laser regimen was applied at 0, 1 and 2 days and at the end of first, second and third months. Tooth movement was measured on prepared models at the end of first, second and third month. Results: We found 1.3 fold increases in rate of tooth movement in the irradiated group (p=0.000) than non-irradiated group. Conclusion: Based on our findings, Low level laser accelerates tooth movement and consequently reduces treatment time

The Edinburgh Postnatal Depression Scale (EPDS): translation and validation study of the Iranian version

BACKGROUND: The Edinburgh Postnatal Depression Scale (EPDS) is a widely used instrument to measure postnatal depression. This study aimed to translate and to test the reliability and validity of the EPDS in Iran. METHODS: The English language version of the EPDS was translated into Persian (Iranian language) and was used in this study. The questionnaire was administered to a consecutive sample of 100 women with normal (n = 50) and caesarean section (n = 50) deliveries at two points in time: 6 to 8 weeks and 12 to 14 weeks after delivery. Statistical analysis was performed to test the reliability and validity of the EPDS. RESULTS: Overall 22% of women at time 1 and 18% at time 2 reported experiencing postpartum depression. In general, the Iranian version of the EPDS was found to be acceptable to almost all women. Cronbach's alpha coefficient (to test reliability) was found to be 0.77 at time 1 and 0.86 at time 2. In addition, test-rest reliability was performed and the intraclass correlation coefficient was found to be 0.80. Validity as performed using known groups comparison showed satisfactory results. The questionnaire discriminated well between sub-groups of women differing in mode of delivery in the expected direction. The factor analysis indicated a three-factor structure that jointly accounted for 58% of the variance. CONCLUSION: This preliminary validation study of the Iranian version of the EPDS proved that it is an acceptable, reliable and valid measure of postnatal depression. It seems that the EPDS not only measures postpartum depression but also may be measuring something more

3-D Comparison of the shape and position of the condyle before and after Class II correction

Thesis (Master's)--University of Washington, 2018Introduction: The aims of this study were to assess the changes in the shape and position of the condyle in the fossa as well as its position relative to the cranial base before and after Class II correction with the Herbst appliance (HA) or headgear (HG), and to also compare any changes to matched Class I cases. Methods: Patients were divided into four groups, Class II treated with HA and their matched Class I cases, as well as Class II cases treated with HG and their matched Class I cases. CBCTs were obtained before and after treatment in all cases. A total of 122 condyles (left and right) from 61 patients were assessed. 242 landmarks were identified on the condyle and fossa, from which 3-D surface meshes were created. 7 relatively stable landmarks were recorded on the skull to assess the position of the condyle relative to cranial base. Length of the mandible was measured on laterals cephalograms rendered from CBCTs. Principal component, generalized Procrustes, and discriminant function analyses were used to assess shape and position changes. Results: There were no significant changes in the position of the condyle relative to the cranial base before and after treatment. No significant differences were reported in the anteroposterior or vertical position of the condyle relative to the fossa (P=0.71 and P=079 respectively). There were significant changes in the shape of the condyles when Class II untreated cases were compared to controls. Untreated Class II cases had more internal rotation of the mediolateral long axis of the condyles when compared to Class I cases. There were no significant differences in changes in the length of the mandible between Class II and control cases. Conclusion: The condyles of all untreated patients, whether they were Class I or Class II initially, did not change their position (within the fossa or relative to stable cranial base structures) when assessed at the end of orthodontic treatment

Fracture Resistance of Composite Fixed Partial Dentures Reinforced with Pre-impregnated and Non-impregnated Fibers

Background and aims. The mechanical properties of fiber-reinforced composite fixed partial dentures (FPDs) are affected by fiber impregnation. The aim of this in vitro study was to compare the fracture resistance of composite fixed partial dentures reinforced with pre-impregnated and non-impregnated fibers. Materials and methods. Groups (n=5) of three-unit fiber-reinforced composite FPDs (23 mm in length) from maxillary second premolar to maxillary second molar were fabricated on two abutments with pontic width of 12 mm. One group was fabricated as the control group with composite (Gradia) and the other two groups were fabricated with composite (Gradia) reinforced with pre-impregnated fiber (Fibrex ribbon) and non-impregnated fiber (Fiber braid), respectively. The specimens were stored in distilled water for one week at 37°C and then tested in a universal testing machine by means of a three-point bending test. Statistical analysis consisted of one-way ANOVA and a post hoc Scheffé’s test for the test groups (α=0.05). Results. Fracture resistance (N) differed significantly between the control group and the other two groups (P<0.001), but there were no statistically significant differences between the pre-impregnated and non-impregnated groups (P=0.565). The degree of deflection measured (mm) did not differ significantly between the three groups (P=0.397), yet the mean deflection measured in pre-impregnated group was twice as that in the other two groups. Conclusion. Reinforcement of composite with fiber might considerably increase the fracture resistance of FPDs; however, the type of the fiber used resulted in no significant difference in fracture resistance of FPD specimens

Changes in Cephalometric Variables after Orthognathic Surgery and Their Relationship to Patients’ Quality of Life and Satisfaction

Objectives: This study was designed to assess the relationship between postsurgical cephalometric changes and quality of life and satisfaction after orthognathic surgery. Material and Methods: Sample size consisted of 30 patients with class III and 25 patients with class II malocclusion treated with bilateral sagittal split osteotomy and Le Fort I osteotomy. Profile convexity, lower facial height proportion, lip position and length, nose, and chin position were measured on pre and post-treatment cephalograms. To assess the patients’ satisfaction and quality of life (QoL) after surgery, the questionnaire of the Rustemeyer’s study and Oral Health Impact Profile (OHIP) questionnaire were used, respectively. The paired-sample t-test, Spearman correlation analysis and Pearson correlation analysis was used in SPSS statistical software. Results: In class III malocclusion patients, decrease in facial angle, convexity angle, mentolabial angle, and increase in upper lip protrusion had the most positive impact on QoL. Decrease in facial angle and increase in upper lip protrusion were correlated positively with satisfaction questionnaires. In class II malocclusion patients, increase in convexity angle, facial angle and mentolabial angle had the most positive impact on satisfaction and QoL. Conclusions: Consideration both subjective and objective parameters affecting on the patients’ satisfaction and their quality of life is essential

The effect of different environmental factors on force degradation of three common systems of orthodontic space closure

Background: Different environmental conditions, such as high temperature or exposure to some chemical agents, may affect the force decay of different methods of space closure during orthodontic treatment. The aim of this in vitro study was to evaluate the force decay pattern in the presence of tea as a popular drink in some parts of the world and two mouthwashes that are usually prescribed by the orthodontist once the treatment is in progress. Materials and Methods: Elastic chain (EC), nickel-titanium (Ni-Ti) closed coil spring and tie-back (TB) method were used as the means of space closure. The specimens were placed in five different media: Hot tea, hot water (65°), chlorhexidine mouthwash, fluoride mouthwash and the control group (water at 37°). The specimens were stretched 25 mm and the elastic force of three systems was measured at the beginning of the study, after 24 h, after 1 week and after 3 weeks. One-way ANOVA was used to compare the results between the groups and Duncan test was carried out to compare the sets of means in different groups (P ≤ 0.05). Results: Tea increases the force decay in the EC and TB groups. Oral mouthwashes also resulted in more rapid force decay than the control group. EC and Ni-Ti groups were not much affected in the presence of oral mouthwashes. Conclusion: Regarding the immersion media, TB method showed the biggest variation in different media and Ni-Ti coil spring was least affected by the type of media

Recommendations for clear aligner therapy using digital or plaster study casts

Abstract Background Clear aligner therapy has evolved considerably since its introduction 20 years ago. Clinicians have become more experienced with aligner therapy, but little is known about the types of malocclusions that clinicians currently treat with aligners. Similarly, it is not known if viewing digital vs plaster models has any impact on the treatment planning process for aligners. The aim of this study was to assess which types of malocclusions are recommended for treatment with clear aligners, and also to determine if recommendations for aligner treatment differed when using digital versus plaster models. Methods Sixteen orthodontists treatment planned 20 cases at two time points with either the same or different model formats (digital versus plaster). As part of the treatment planning process, they were asked whether each patient was a good candidate for Invisalign® treatment, and if not, why. Generalized estimating equations regression (GEE), the permutation test, and a logistic regression model with GEE were used to analyze the data. Results No significant difference was found between the Invisalign® choices in the digital model group and those in the plaster model group at T1 (p = 0.59). There was no significant difference between the agreement rate of the different formats group and that of the same format group (p = 0.97). Cases with extractions had less Invisalign® recommendations (15%) compared to cases with no extractions (55%) (p = 0.0015). Cases with surgery had less Invisalign® recommendations (29%) compared to cases with no surgery (57%) (p = 0.035). Conclusions In this study, viewing orthodontic records with digital versus plaster models did not influence decisions about Invisalign® recommendations. Additionally, the orthodontists in this study tended to not recommend Invisalign® for extraction cases, surgical cases, or difficult cases