IRANIAN JOURNAL OF ORTHODONTICS
Year:2020 | Volume:15 | Issue:2|Papers Count:8

Objectives: This studied aimed to measure the yield strength and stress relaxation properties of three commercially available thermoplastic aligner materials. Methods: The three diff erent thermoplastics aligner materials Duran (Scheu, Iserlohn, Germany), Erkodur (Pfalzgrafenweiler, Erkodent, Germany) and Track (Forestadent, Germany) were selected. A three-point bending test was carried out via the universal testing machine to measure their yield strength and stress relaxation properties. An independent t-test was performed for intergroup comparison. P-value < 0. 05 was set as the level of signifi cance. Results: All the selected three polymers liberate a notable amount of stress during 24 hours. The highest stress release was observed in Duran i. e. 18. 96 N/cm2as compared to Erkodur, which was 13. 96 N/cm2and Track, which was 13. 18 N/cm2. The yield strength of Duran was the highest (75. 85 Mpa) compared to Track and Erkodur with the yield strength of 52. 75 Mpa and 55. 86 Mpa, respectively. Conclusions: Tooth movement is infl uenced by the composition of aligner material and its thickness. Duran had the highest stress release and yield strength. Stress released by diff erent aligners exceeds around half of the initial stress value, which directly aff ects the orthodontic force application and subsequent tooth movement.

Context: The nose and lips area play an important role in facial appearance and nasolabial angle (NLA) can be considered as a determinant factor for attractiveness. The perception of beauty and attractiveness is vastly infl uenced by media and thus, can change with trends over time. The aim of this study was to conduct a systematic review of literature on NLA in faces perceived as attractive over time and in diff erent ethnic groups. Evidence Acquisition: This study was performed following preferred reporting items for systematic reviews and meta-analyses extension for Scoping Reviews (PRISMA-ScR) guideline. We conducted an electronic search using PubMed, Scopus, and Embase databases with the employment of MeSH and free text terms "beauty"[MeSH], "esthetics"[MeSH], "soft tissue", "nasolabial angle", "attractive" and "cephalometric analysis". The inclusion criteria were studies that indicated facial attractiveness by a panel of at least 10 judges, evaluated the soft tissue profi le characteristics, and reported the preferred NLA. Results: The search results revealed 271 related articles, of which 21 studies investigated NLA as a conducive factor in profi le attractiveness and were included in the review. The range of preferred NLA was 86° to 107° for men and 84° to 123. 12° for women. Conclusions: The most pleasing lip position and subsequently NLA is infl uenced by variables including the observer and subject’ s gender, and their ethnic background as well as time. Over all, NLA in faces perceived as attractive is more obtuse in women than men. Compared to white norms, NLA is more acute among Chinese and African-Americans, while amongst Iranian women, it is not distinctly far from North American Caucasians. Over the course of time, preferred NLA has signifi cantly changed in women but has been unwavering in men.

Background: Iran lies in the world’ s thalassemia belt; accordingly, the beta-thalassemia gene is carried by 4% of the Iranian population. Due to the dearth of research and literature available on the prevalence of malocclusions in the Iranian population with beta-thalassemia major, this study was conducted to determine the prevalence and severity of facial abnormalities among patients who were referred to Bu-Ali Sina Hospital, Sari, Iran. Methods: This descriptive cross-sectional study was conducted on 200 patients with thalassemia major who were referred to the care unit of Bu-Ali Sina teaching and therapeutic Hospital, Sari, Iran, in 2018. The patients were then visited by a trained dentist who had been given the necessary theoretical and practical training. Malocclusion was classifi ed based on Angle’ s classifi cation. Spacing, overcrowding, overjet, and overbite were measured, and the distances were recorded based on a checklist. Results: The prevalence of malocclusions obtained was 87. 5%, which included malocclusions of Class I (34%), Class II (31%), and Classes III (22%) amongst patients. There was no signifi cant relationship between the type of malocclusion and gender (P = 0. 77). Moreover, no signifi cant diff erence was observed among patients with thalassemia major and diff erent classes of malocclusions in terms of age both in males (P = 0. 49) and females (P = 0. 58). Conclusions: Malocclusions are common among adolescents and adults with thalassemia, which is not associated with age or gender. Therefore, patients should be regularly visited and followed up by a dentist to manage and control their dental problems. In addition, eff ective and preventive measures, as well as health education should be seriously considered in these patients.

Objectives: This study aimed to assess the skeletal maturation by using salivary DHEAS levels and its correlation with existing skeletal maturity parameters represented by cervical vertebrae and MP3 region radiographs in adolescents in pre-pubertal and pubertal age groups. Methods: In this study, 80 children in the age range of 8-14 years were divided into two equal groups based on their chronological age as group I (pre-pubertal group) and group II (pubertal group). Pre-existing lateral cephalograms and medial phalanx of third fi nger (MP3) radiographs of their left hands were assessed. The levels of the DHEAS of each individual were analysed by ELISA kit. ANOVA with post-hoc Tukey’ s test and student t-test were used for statistical analysis. P-value < 0. 05 was considered signifi cant. Results: The mean level of DHEAS values shown in the present study was 4. 36 +/-0. 32 ng/mL in group I and 5. 73+/-0. 39 ng/mL in group II. This study showed that in group I, more subjects were in stage 1 of cervical vertebral maturation than stage 2 and there were signifi cant diff erences between the two stages (P-value = 0. 011); also, in group II, more subjects were in stage 3 than 4 and there were signifi cant diff erences between the two stages (P-value = 0. 017). This study revealed the highest salivary DHEAS levels to be in the F stage of pre-pubertal MP3 development in addition to the H stage of MP3 development in pubertal children. This study noted that there were signifi cant diff erences for salivary DHEAS levels between males and females not only in pre-pubertal (P-value = 0. 031), but also in pubertal stages (P-value < 0. 001). Conclusions: Salivary DHEAS, like cervical vertebra and MP3 radiographs, can be used for growth assessment in young adolescents.

Objectives: This study was aimed to assess salivary sodium and potassium concentrations in patients with fi xed orthodontic appliances. Methods: In this case-control study, saliva samples (5 cc) were collected from 13 patients with fi xed orthodontic appliances before, and 1 week, 1 month and 3 months after the beginning of the orthodontic treatment using the spitting method. Saliva samples were also collected from 10 healthy individuals as controls. The saliva samples were centrifuged at 3000 rpm for 10 minutes and the salivary sodium and potassium concentrations were measured by spectrophotometry. Data were analyzed using independent and paired t-tests. P-value < 0. 05 was considered as signifi cant. Results: The salivary sodium and potassium concentrations were almost the same in both groups at baseline (P > 0. 05). A signifi cant reduction in sodium and an increase in potassium levels were noted in the case group at 1 week compared with baseline (P < 0. 001). At 1 week, the potassium concentration was signifi cantly higher and the sodium concentration was signifi cantly lower in the case group (P < 0. 01). The salivary sodium signifi cantly increased while the salivary potassium signifi cantly decreased at 1 month compared with 1 week (P < 0. 001). The diff erences with the control group were also signifi cant (P < 0. 05). No signifi cant diff erences were noted between the two groups at 3 months (P > 0. 05). Conclusions: Time has a signifi cant eff ect on the release profi le of sodium and potassium ions from orthodontic appliances. The salivary sodium and potassium concentrations returned to their normal pretreatment values within 3 months after the start of fi xed orthodontic treatment.

Background: Orthodontics is defi ned as a branch of dentistry that concerns the correction of malocclusion. In this regard, determining the most appropriate time for orthodontic treatment is of utmost importance. General dental practitioners (GDPs) are normally the fi rst link of the treatment chain for patients requiring orthodontic treatment. Objectives: The present study aimed to determine the GDPs’ knowledge of the appropriate timing of orthodontic treatment in Sari, Iran. Methods: This descriptive, analytical and cross-sectional study was performed on GDPs working in Sari in 2019. The statistical population included 380 GDPs, 186 of whom were selected. Data was collected using a 24-item questionnaire aimed to evaluate the GDPs’ knowledge level of the appropriate timing of orthodontic treatment. Data analysis was performed using SPSS version 19. Results: In total, 142 out of 186 GDPs participated in the study with a mean age of 36. 12  10. 15 years. 86 subjects (59. 9%) had less than 10 years of work experience. Total mean ( SD) knowledge level of the GDPs was estimated at a moderate level (14. 13  3. 79). Percentage of the knowledge levels considered as poor, moderate and good was 12, 70, and 18, respectively. There was a signifi cant relationship between knowledge level and gender (P = 0. 013). Meanwhile, no association was observed between the work experience of the participants and their level of knowledge (P = 0. 393). Conclusions: According to the results of the present study, the total mean score of GDPs’ knowledge about the appropriate timing for orthodontic treatment in Sari was moderate, and only 12% of the participants had a poor knowledge level in this regard. It is notable that male subjects had a signifi cantly higher knowledge level, and another analysis demonstrated the lack of eff ectiveness of work experience on the knowledge level of individuals.

Background: Following the morphological features of diff erent races and ethnic groups, knowledge of standard dentofacial patterns of each ethnic group is essential. Therefore, this study aimed to explain cephalometric standards for the Zanjanian population according to Downs’ analysis and compare them to Caucasian individuals. Methods: Seventy lateral cephalometries of Zanjanian adults (17-29 years old) who had been referred to a private orthodontic offi ce in Zanjan, Iran with class I molar and canine relationship and normal overjet and overbite as well as minimum crowding/spacing/rotations were scanned and traced with the Novatech scanner and Dolphin software version 10. Next, statistical analyses were performed in order to compare the Zanjanian population to Caucasians. Results: We found a signifi cant diff erence between males and females in terms of interincisal angle, incisor-occlusal angle, incisormandibular plane angle, upper incisor proclination, facial angle, and angle of convexity. Discussion: The analysis of six statistically signifi cant parameters indicates that the upper and lower incisors in women of Zanjan were proclined and protruded compared with those of Caucasian subjects. Due to the statistical analysis on facial angle and angle of convexity, women also show more maxillary prognathism and skeletal class II pattern. Generally, a comparison of Zanjanian population cephalometrics based on Downs’ analysis showed an increase in maxillary prognathism, maxillary and mandibular incisal protrusion and posterior rotation of the mandible. Conclusions: In conclusion, the Zanjanian population tends to have more dental and skeletal class II patterns than the Caucasians. In addition, gender comparison indicates lower and upper-incisors protrusion in women of Zanjan.

Objectives: The objective of this research was to compare the orthodontic treatment need and demand using Dental Aesthetic Index (DAI) and Occlusal Index (OI) among dentistry students of Shiraz University of Medical Sciences. Methods: This descriptive cross-sectional study was performed on 113 dental students in Shiraz University of Medical Sciences. The demand for orthodontic treatment was assessed using a standardized questionnaire and 10 photographs of aesthetic component (AC) of IOTN for the self-assessment of subjects about their dental attractiveness. Occlusal Index (OI) and Dental Aesthetic Index (DAI), which were calculated by clinical examination and dental model analysis, were used to assess the orthodontic treatment need. Students with a history of orthodontic treatment were excluded. Results: Final analysis was done on 113 cases (48 men and 65 women). The study showed that there was a signifi cant relationship between the demand for orthodontic treatment and the self-assessment of subjects about their dental attractiveness (according to the photograph they had chosen) (P = 0. 015). There is also a signifi cant relationship between the self-assessment of subjects about their dental attractiveness (according to the photographs) and the orthodontic treatment need based on DAI (P = 0. 008). Furthermore, a signifi cant connection was found between the self-assessment of subjects about their dental attractiveness (according to the photographs) and the orthodontic treatment need based on OI (P < 0. 001). Conclusions: The results of our study revealed that both indices show that the need for orthodontic treatment is in line with the demand, which could be used for planning public orthodontic and dental services.