Changes of nasolabial angle from rest to smile in relation to cephalometric parameters.

INTRODUCTION: The nasolabial angle (NLA) plays an important role in evaluating a patient's profile and smile appearance. The purpose of this study was to evaluate the changes of the NLA during smile and to correlate those changes with other photographic and cephalometric parameters. METHODS: Fifty young adults ranging from 20 to 30 years of age who had been referred to a private dental clinic for orthodontic treatment for normal maxillary position were enrolled. For the purpose of this study, the angular measurements of the NLA and its compartments as well as changes in the vertical position of the nasal tip were collected from photographs taken at rest and during smile, while other parameters were measured from the lateral cephalograms taken with the head in a natural position. Changes in the NLA were then correlated with the cephalometric parameters in order to observe any potential relationships. RESULTS: The NLA and its upper compartment decreased during smile (with a mean of 5.42 and 0.77 degrees, respectively). The NLA and its lower compartment increased, with a mean of 3.97 degrees. The nasal tip significantly dropped down from rest to smile (mean = 1.6 mm, P = 0.002). Significant correlations were found between changes of the NLA and the maxilla projection as well as between changes of the lower part of the NLA and the upper lip curvature. CONCLUSIONS: Decreasing the NLA during smile is mainly related to the inherent properties of the soft tissues of the nasolabial area and not to the dental parameters under the control of the orthodontist. Patients should therefore be made aware of this from the beginning of the treatment.

Bleaching during orthodontic treatment and its effect on bracket bond strength.

BACKGROUND: This study investigated the effect of two different methods of bleaching during orthodontic treatment on bracket bond strength. MATERIALS AND METHODS: A total of 45 extracted premolar teeth were selected in this experimental study and divided into three groups (office bleaching with 35% hydrogen peroxide, home bleaching with 22% carbamide peroxide, and control). The color of the teeth was assessed initially before the application of bleaching agents and Thermocycling. Orthodontic brackets were subsequently bonded on the treated surfaces. Bleaching procedures were then performed. A final color measurement was performed at two points on the buccal surface both underneath and adjacent to the bracket base. The initial and final color measurements and the bond strengths were compared between the groups using the analysis of variance. P < 0.05 was considered as statistically significant. RESULTS: Bracket bond strength was significantly reduced in both bleaching groups compared with the control group (P < 0.01). The color difference before and after the bleaching procedures was significant in the office bleaching group (P < 0.01), while the control group did not demonstrate a statistical difference between initial and final color assessments (P > 0.05). CONCLUSION: Bleaching procedures performed during orthodontic treatment reduce bond strength. Enamel beneath the bracket base experiences a whitening effect though to a lesser degree compared with an uncovered surface.

Assessment of the effect of maxillary protraction appliance on pharyngeal airway dimensions in relation to changes in tongue posture.

BACKGROUND: Literature is controversial in regard with alterations in pharyngeal airway dimensions subsequent to maxillary protraction. The correlation between maxillary protraction and sagittal airway dimension was investigated in association with tongue and soft palate position in skeletal Class III children. The results were compared with those of an untreated Class III and a Class I malocclusion control group. MATERIALS AND METHODS: In this cross-sectional study pre- and post-treatment cephalometric radiographs of 19 Class III patients (6 males, 13 females; mean age, 7.93 ± 0.96 years) treated with facemask were analyzed. The correlation between treatment changes in craniofacial morphology and those in the upper airway, tongue, and soft palate was evaluated. These results were compared with those of a group of 16 Class I malocclusion patients (1 male, 15 females; mean age, 7.31 ± 0.7 years) and a group of 15 untreated Class III patients (4 males and 11 females; mean age, 7.46 ± 0.1 years). A paired t-test, the Shapiro-Wilk test and Mann-Whitney U-test was used. The level of significance was established as P < 0.05. RESULTS: Nasopharyngeal airway measurements PNS-ad1 and PNS-ad2 significantly increased by 2 mm and 2.1 mm, respectively. Statistical analysis revealed that maxillary protraction had a positive relationship with PNS-ad1 and PNS-ad2. CONCLUSION: Nasopharyngeal airway dimensions can be improved in the short term with maxillary protraction in skeletal Class III children.

Evaluating the clinical quality of departments as viewed by juniors and seniors of Shiraz dental school.

INTRODUCTION: Assessment of students' perspective is an essential element in effective educational quality evaluation. By identifying strengths and weaknesses, it leads to improvement in future performance. METHODS: This cross-sectional study was performed through a questionnaire comprising 23 questions. Reliability was assessed using α-Chronbach (α =0.87), and validity was confirmed by a group of five experts. Tukey test, Pearson correlation coefficient, and two sample t-tests were used for data analysis. METHODS: This cross-sectional study was performed through a questionnaire comprising 23 questions. Reliability was assessed using α-Chronbach (α =0.87), and validity was confirmed by a group of five experts. Tukey test, Pearson correlation coefficient, and two sample t-tests were used for data analysis. RESULTS: A total of 168 answered questionnaires were entered in our study. Maximum satisfaction in most items was shown in removable prosthodontics and orthodontics departments whereas oral surgery and comprehensive treatment departments acquired the least scores. In all departments, personnels' respectful attitude had the highest score whereas minimum grade was given to stressful workload and overall satisfaction in each department. In comparison with a similar study, conducted 3 years ago, level of satisfaction was raised for orthodontics and removable prosthodontics departments though it was declined for the pediatrics department. CONCLUSION: The special cadre of clinical instructors comprising both experienced and young members is considered as an important factor leading to high student satisfaction in the orthodontics department. Promotion of a removable prosthodontics department is related to the high relevance between the implemented educational program and the curriculum. The moderate performance of oral surgery and restorative departments is indicative of the need for more attention from ministry authorities to major dental departments such as oral surgery, endodontic, restorative and periodontics, in order to increase the students' scientific capability in these fields.

The effect of vertical bracket positioning on torque and the resultant stress in the periodontal ligament--a finite element study.

BACKGROUND: The ideal built-in tip and torque values of the straight wire appliance reduce the need for wire bending and hence reduce chair time. The vertical position of the bracket on the tooth surface can alter the torque exerted on the tooth. This is a result of the altered surface curvature observed at each vertical position. To further clarify the role of vertical bracket positioning on the applied torque and the resultant stresses in the periodontal ligament (PDL), we designed a mandibular first premolar using finite element modeling. METHODS: Cone beam computed tomography of 52 patients (83 lower first premolars) was selected to be included in the study. Curvature was measured for points along the labial surface with increasing distances (0.5 mm increments) from the cusp tip by calculating the angle between tangents drawn from these points and the axis joining the cusp tip and the root apex. The mean values for each distance were calculated, and a finite element model was designed incorporating these mean values. The resultant stress and hydrostatic pressure in the PDL were calculated using finite element analysis. RESULTS: The labial surface of the mandibular first premolar demonstrated a 26.39° change from 2.5 to 6 mm from the cusp tip. The maximum Von-Mises stress and hydrostatic pressure in the PDL were observed at the root apex for all of the bracket positions, and these values demonstrated, respectively, a change of up to 0.059 and 0.186 MPa between two successive points. CONCLUSIONS: It can be concluded that the variation in the vertical position of the bracket can have an important effect on the torque and subsequently on the stresses and pressures in the PDL.

Measuring agreement between cervical vertebrae and hand-wrist maturation in determining skeletal age: reassessing the theory in patients with short stature.

INTRODUCTION: The objective of this study was to determine the degree of agreement between hand-wrist radiography and cervical vertebral maturation analysis in patients diagnosed with short stature. METHODS: A cross-sectional study was designed; 178 patients (90 girls, 88 boys) diagnosed with short stature and seeking treatment were selected. The patients were divided into 2 groups (76 with familial short stature, 102 with nonfamilial short stature). Hand-wrist and lateral cephalometric radiographs were obtained from the patients. The hand-wrist radiographs were analyzed using the Fishman method, and the lateral cephalometric views were categorized according to the method of Hassel and Farman. The degree of agreement between the 2 methods of predicting skeletal maturation was measured by calculating the contingency coefficient and the weighted kappa statistic. RESULTS: A high degree of agreement was observed between the 2 methods of analyzing skeletal maturation. It was also observed that agreement was higher in girls in the familial short-stature group, whereas boys had higher agreement in the nonfamilial short-stature group. CONCLUSIONS: Cervical vertebral maturation can be a valuable substitute for hand-wrist radiography in patients with short stature.

Study skills and habits in Shiraz dental students; strengths and weaknesses.

INTRODUCTION: The dental students, the same as other students, during their academic courses are required to learn a wide range of scientific subjects. Obviously, choosing the inappropriate method of study leads to confuse and disenchantment of students and it causes wasting of their energy. The purpose of this study was to assess the existing strengths and weaknesses of the skills and study habits in Dental Students of Shiraz University of Medical Sciences in 2009-10. MATERIALS AND METHODS: In this cross-sectional study, all of the dental students (n = 274), who studied at the time of study at all levels in the academic year of 2009-10, were selected by the census. Data were collected by using the Huston University questionnaire consisted of two parts of demographic questions and 64 specific areas of study skills in eight domains of time management, concentration/memory, study aids/note taking, test strategies, information processing, motivation, self-assessment/reading, and writing skills. Following the retranslation of the questionnaire, the validity was confirmed by using the content validity method. The reliability was obtained by using the Cronbach's Alpha of 0.92. The data were analyzed with SPSS software version 17 and using analytical statistic tests. RESULTS: Students who have previously participated in the study skills workshops had stronger skills in comparison with the students who had not participated in these workshops. Time management skills (P = 0.04), motivation (P = 0.0001) and information processing (P = 0.03) in students with professional status were in a more favorable position and showed significant differences in terms of educational levels. The study skills mean score of the students living in student housings in comparison with the other students were significantly higher (P = 0.04). Marital status showed no significant differences in reading skills. CONCLUSION AND RECOMMENDATIONS: The review of study skills in the undergraduate and post-graduate dental students indicated that the residents had higher reading skills. By recognizing the existing strengths and weaknesses and holding programs through counseling centers can develop the study skills in the students.

Ion release from orthodontic brackets in 3 mouthwashes: an in-vitro study.

INTRODUCTION: Stainless steel orthodontic brackets can release metal ions into the saliva. Fluoridated mouthwashes are often recommended to orthodontic patients to reduce the risk of white-spot lesions around their brackets. However, little information is available regarding the effect of different mouthwashes in ion release of orthodontic brackets. The purpose of this study was to measure the amount of metal ion release from orthodontic brackets when kept in different mouthwashes. METHODS: One hundred sixty stainless steel brackets (0.022-in, 3M Unitek, Monrovia, Calif) were divided randomly into 4 equal groups and immersed in Oral B (Procter & Gamble, Weybridge, United Kingdom), chlorhexidine (Shahdaru Labratories, Tehran, Iran), and Persica (Poursina Pharmaceutical Laboratories, Tehran, Iran) mouthwashes and distilled deionized water and incubated at 37°C for 45 days. Nickel, chromium, iron, copper, and manganese released from the orthodontic brackets were measured with an inductively coupled plasma spectrometer. For statistical analysis, 1-way analysis of variance (ANOVA) and the Duncan multiple-range tests were used. RESULTS: The results showed that ion release in deionized water was significantly (P <0.05) higher than in the 3 mouthwashes. Higher ion release was found with chlorhexidine compared with the other 2 mouthwashes. There was no significant difference (P >0.05) in nickel, chromium, iron, and copper ion release in the Oral B and Persica mouthwashes. The level of manganese release was significantly different in all 4 groups. CONCLUSIONS: If ion release is a concern, Oral B and Persica mouthwashes might be better options than chlorhexidine for orthodontic patients with stainless steel brackets.

Orthodontic treatment needs assessment of 14- to 18-year-old students in Shiraz, Iran.

AIM: Orthodontic need assessment is instrumental for dental treatment planning. The objective of this examination was to evaluate the orthodontic treatment need of students in Shiraz, Iran, using the Dental Aesthetic Index (DAI) and to assess the relationship between DAI and sociodemographic variables. METHODS: Using random cluster sampling, 1,818 pupils (965 male and 853 female) 14 to 18 years of age without any history of orthodontic treatment were selected. Information was gathered using a questionnaire, including demographics such as sex, family size, and parents' education. Orthodontic assessments were performed by two orthodontists over 2 months. The data were analyzed with chi-square and t tests. RESULTS: Many of the subjects (48.3%) had no need for orthodontic treatment. About one-fifth of the population (21%) had intense-to-disabling malocclusions, and 8.4% had disabling malocclusion with compulsory treatment needs. The study showed a close relationship between sex and malocclusion. CONCLUSION: The study showed that Iranian youth in Shiraz had better dental appearances and less orthodontic treatment need than some populations (Japanese, Caucasian and Native Americans, and Caucasian Australians) but worse than Chinese, Spanish, and Nigerian populations. It might be possible to relate the difference to genetics, cultural differences, and growth.