Effects of diode laser (980 nm) on orthodontic tooth movement and interleukin 6 levels in gingival crevicular fluid in female subjects.

The aim of this study was to evaluate the effects of low-level laser irradiation on the rate of orthodontic tooth movement (OTM) and the interleukin-6 (IL-6) concentration in gingival crevicular fluid (GCF) during orthodontic treatment. In this randomized split-mouth double blind clinical trial, 11 female patients aged 14 to 25 years (mean 19 ± 4.21 year), who required canine retraction following four first premolars extraction, were selected. The GaAlAs laser diode laser (A.R.C. Laser GmbH, Nürnberg, Germany) (980 nm, 100 mW, 5.6 J/cm2, three points from the buccal side and three from lingual side of the tooth, 56 s, running in continuous mode) was used for canine retraction in only one maxillary quadrant (LG). The irradiation time for each cervical and middle third of the tooth was 10 s, and 8 s for the apical third of the tooth. The other maxillary quadrant served as the control group (CG) using the laser pseudo-application in this side. The laser irradiation was applied on days 0, 7, 14, 21, and 28 of each month during the canine retraction phase. Canine retraction was done using closed coil spring with 150 g force on rectangular wires after the alignment and leveling. This study was done in 11 months. Dental casts were made at different time points during the treatment, and the amount of tooth movement was measured. To evaluate the levels of IL-6, GCF samples were collected from the distal side of the maxillary canine teeth on both quadrants at the beginning of the trial, the end of aligning phase, and on day 21 of each month during canine retraction. Although the mean rate of canine retraction was higher in the LG (0.013) than the CG (0.012) and there was definitely a tendency for more canine retraction in the LLLI, but the results failed to show any significant difference between the mean rate of canine retraction of both groups (P = 0.068). A paired t test showed that there was no significant difference in the mean concentration of IL-6 at various stages of the treatment between the groups during canine distalization (P > 0.05). Therefore, conclusive evidence could not be provided to support the efficacy of the diode laser (980 nm) in accelerating OTM in female subject.

Comparison of shear bond strength of rebonded brackets with four methods of adhesive removal.

Rebonding of a dislodge bracket is considered as an economic saving option which can be done with use of in-office methods or by commercial recycling. The aim of this study was to compare the shear rebond strength (SRS) of brackets recycled with different resin removal methods. Eighty premolars were divided into four experimental groups. The teeth were bonded with metal brackets. The brackets were debonded and adhesive remnants were removed from bracket bases by means of Er:YAG laser, sandblasting, direct flame, and CO2 laser, respectively. Following adhesive removal from enamel surfaces with carbide bur, recycled brackets were rebonded. Finally, all brackets were debonded with a Dartec testing machine and the SRS values were determined. The SRS values of groups 3 and 4 were significantly lower compare to other groups (P value < 0.001). SEM examination showed complete adhesive removal from bracket base cleaned with Er:YAG laser irradiation. Microroughening of the base of sandblasted bracket was observed in the SEM image. Resin removal with direct flame and CO2 laser irradiation was incomplete. Er:YAG laser recycling of brackets is an efficient in-office method of reconditioning which caused minimum damage to the bracket base.

Prevalence of cleft lip and palate in births from 2003 - 2006 in Iran.

OBJECTIVE: To determine the prevalence of cleft lip and palate in births taking place in hospitals in the Yazd province, Iran. METHOD: The records of 65,236 live births delivered at 12 hospitals in Yazd province, including Yazd city and four cities of the states, over a four year period from 2003 to 2006 were examined. RESULTS: Fifty six cases of cleft lip and palate were found, a prevalence of 0.86 per 1,000. Among the fifty six cases, there were seventeen cases (30.4%) of isolated cleft palate; thirteen cases (23.2%) of cleft lip and twenty six cases (46.4%) of cleft lip and palate. No statistically significant difference in the occurrence of cleft lip and palate were observed by the season of the birth, gender of newborn or maternal age. In regard to type of cleft, the prevalence of isolated cleft palate was higher in females than in males (p = 0.04). The prevalence of cleft lip was higher in summer than other seasons (p = 0.01). CONCLUSION: The prevalence of cleft lip and palate among live births in Yazd is 0.86 per 1,000 births, that is 1 per 1,163 births.

Changes in hyoid position following treatment of Class II division1 malocclusions with a functional appliance.

OBJECTIVE: The aim of this study was to determine change of hyoid bone position following treatment with functional appliance in patients with class II division 1 malocclusion. DESIGN: This study performed on pre and post treatment lateral cephalograms of 28 patients with class II div I malocclusion treated with Farmand functional appliance on average of 11 months. The range of age of girls was 10-13 years and boys 11-14 years. To study the results, t test and Pearsons correlation coefficient were used. RESULTS: Hyoid bone shifted significantly (P value < 0.01) forward in horizontal dimension and non significantly upward in vertical dimension. There was no significant difference between three groups in facial growth patterns with respect to hyoid bone position alterations in horizontal dimension but was significant between horizontal and vertical growth pattern in vertical dimension. (P value < 0.05). There was significant correlation between decrease ofANB angle with forward movement of hyoid bone. CONCLUSION: Following treatment with Farmand functional appliance, significant changes occur in the position and anterior displacement of the hyoid bone.

Effect of different types of enamel conditioners on the bond strength of orthodontic brackets.

AIM: A unique characteristic of some new bonding systems in operative dentistry is they combine conditioning and priming agents into a single acidic primer solution for simultaneous use on both enamel and dentin. Combining conditioning and priming into a single treatment step results in improvement in both time and cost-effectiveness to the clinician and, indirectly, to the patient. The purpose of this study was to determine the effects of the use of a self-etching primer on the bond strength of orthodontic brackets and on the bracket/adhesive failure mode. METHODS AND MATERIALS: Thirty-six fresh bovine incisors were collected and stored in a solution of 0.1% (weight/volume) thymol. The criteria for tooth selection included intact buccal enamel, no cracks caused by the presence of the extraction forceps, and no defects. The teeth were cleansed and polished with pumice and rubber prophylactic cups for ten seconds. Brackets were bonded to the teeth according to one of three protocols following the manufacturers' instructions--Group 1: Conventional multistep bonding system (control group) (n=12); Group 2: Self-etching primer system (n=12); and Group 3: Acid+self-etching primer system (n=12). Specimens were loaded to failure in a Zwick test machine (Zwick GmbH & Co, Ulm, Germany). Shear bond strengths were measured at a crosshead speed of 5 mm/min. RESULTS: The mean shear bond strength in megapascals (Mpa) (standard deviation) were 11.7 (4.2), 10.5 (4.4), and 10.9 (4.8) for Groups 1, 2, and 3, respectively. The analysis of variance (ANOVA) was used to compare the three groups. The results indicated no significant difference in the bond strength between the three groups (P=0.800). The results of the Chi square test, evaluating the residual adhesives on the enamel surfaces, revealed no significant difference between the three groups (P=0.554). CONCLUSION: Results of the present in vitro study indicate the use of self-etching primers may be an alternative to conventional phosphoric acid pre-treatment in orthodontic bonding.

Changes of tongue position and oropharynx following treatment with functional appliance.

The aim of this study was to determine changes of tongue position and oropharyngeal space following treatment with functional appliance in patients with class II div I malocclusion. In this before-after clinical trial, 28 patients with class II div I malocclusion were investigated. The range of age of females was 10-13 years and males 11-14 years. These samples were treated for II months. McNamara analysis and some linear variables were used to determine positional changes of tongue and oropharyngeal space. In this study, tongue moved significantly (P. value < 0.05) forwards in the horizontal dimension and non-significantly downwards in the vertical dimension. Treatment with functional appliance leads to significant alterations in tongue position and significantly increases the extent of oropharyngeal space.

Abnormal oral habits in the children of war veterans.

Any kind of stress has a negative effect on the mood of people and stress resulting from war is no exception. Stress from war has not only has effects on war veterans but also on the families. Children of these families have been more susceptible to abnormal oral habits. In this observational, analytical and historical research, attempts have been made to determine the prevalence of abnormal oral habits in the children of war veterans (martyrs, freed prisoners of war and war cripples) and compare them with a control group. In this study of 520 children aged between 7 and 11 years were (238 in the study group and 282 in the control group), information was gathered via a questionnaire completed by the mothers of the students. Analysis of the received information showed that the prevalence of para functional and abnormal oral habits was more in the study group (P = 0.005). The prevalence rate was highest in children, whose family members had been both crippled and freed prisoners of war, while the rate was lowest in children whose parents had been only prisoners of war without any lasting physical injury. Most of these children had acquired these habits at the age of seven and these abnormal habits were most prevalent in children aged eight and nine.

Predicting the actual length of premolar teeth on the basis of panoramic radiology.

BACKGROUND: Panoramic radiography is one of the most common techniques for evaluating the jaw bones and associated structures. AIM: The aim of the study was to predict the actual length of the premolar teeth, based on measurements taken on a panoramic radiograph. MATERIALS AND METHODS: This study was done in two stages. In the first stage, the actual and panoramic lengths of 102 teeth of orthodontic patients were measured and compared. In the next stage, the actual and radiographic vertical lengths of four metal balls placed in the molar and first premolar areas of 27 patients, referred to radiography clinic were also analyzed. Comparison of the mean magnification between the two methods was performed by one-sample T-test and P<0.05 was considered as statistically significant. RESULTS: The total magnification of the premolar region in the vertical plane in the tooth length measurement method was 17.39%, while the same in the metal markers method was 27.39%. The upper teeth showed larger magnification than the lower teeth in the vertical plane. Similarly, the magnification and distortion of the metal markers in the horizontal plane were significantly more than this in the vertical plane and also their magnification and distortion in the molar region were more than this in the premolar region. The actual length of the premolar teeth can be estimated by using a suitable regression formula. CONCLUSION: Panoramic radiography can be used for calculating the actual length of premolar teeth.