IRANIAN JOURNAL OF ORTHODONTICS
Year:2020 | Volume:15 | Issue:1|Papers Count:8

Background: An attractive smile is often attributed to incisor alignment and proclined or retroclined incisors could contribute to a less aesthetic smile. Objectives: This study was aimed to evaluate the maxillary central incisor crown inclination, crown angulation and tooth size variation in aesthetic and unattractive smiles. Methods: The study was conducted among 100 females (equally divided into aesthetic and unaesthetic smile groups), aged between 15-25 years, with Angle’ s Class I normal occlusion and balanced profi les. Variations in maxillary central incisor crown inclination and angulation were measured on lateral cephalograms, photographs and the study models of the subjects. Variations in tooth morphology were also evaluated by measuring crown height and width in both groups. Mann-Whitney U test was performed to evaluate the diff erence between the aesthetic and unaesthetic smiles. P < 0. 05 was considered as signifi cant. Results: This study showed that incisor angulation was signifi cantly higher in the unaesthetic group compared to the aesthetic group (P < 0. 001). However, there was no statistically signifi cant diff erence for the incisor inclination relative to the Palatal Plane between the aesthetic and unaesthetic smile groups (P = 0. 086). In addition, there were signifi cant diff erences between the aesthetic and the non-aesthetic groups regarding the central incisor height (P < 0. 05). Conclusions: The fi ndings of this study indicate that the possible variations in aesthetics are related to the ethnic elements that are associated with diff erences in crown angulations, as well as tooth size.

Context: Maxillary defi ciency can lead to the reduction of airway space and increase the chances of development of obstructive airway disorders. Facemask therapy is one of the main treatment protocols in developing maxillary defi cient patients. Objectives: The purpose of this systematic review and meta-analysis was to assess the changes in the airway dimensions after facemask therapy in both cleft lip and palate and non-cleft patients. Methods: A systematic search in diff erent electronic databases (EMBASE, Pubmed, Cochrance Central register of controlled trials), IADR proceedings and a hand search by October 2020 were conducted and a meta-analysis and systematic review was performed. Results: In patients without cleft lip and palate, upper pharyngeal width was signifi cantly increased by mean of 2. 05 mm (CI = 95%, 0. 61-3. 50) following facemask therapy in comparison to patients who did not receive the treatment. Other upper pharyngeal (nasopharyngeal) measurements also showed a statistically signifi cant improvement after therapy: S-PNS by 4. 64 mm (CI = 95%, 3. 34-5. 94), AD1-PNS by 3. 81 mm (CI = 95%, 2. 40-5. 21), AD2-PNS by 2. 90 mm (CI = 95%, 0. 13-5. 67) and Pm’-SPL by 2. 53 (CI = 95%, 0. 54 4. 51). Lower pharyngeal measurments did not show any signifi cant changes after the treatment (P > 0. 05). In the analysis of studies with 3D imaging modalities, upper pharyngeal volume was also signifi cantly increased by 499. 29 mm (CI = 95%, 69. 58-929. 00) after the treatment. In addition, a review of articles that included cleft lip and palate patients also showed after the treatment, the upper pharyngeal measurements all showed a signifi cant improvement (P < 0. 05), whereas the oropharyngeal region was relatively stable. Conclusions: In maxillary defi cient patients with or without an orofacial cleft, facemask therapy can improve the nasopharyngeal area dimensions; however, this treatment protocol appears not to have an eff ect on the oropharyngeal area of the airway tract.

Background: There is great controversy regarding the eff ect of MBT and Damon bracket systems on dental arch dimensions and incisor position. Objectives: We aimed to study the eff ects of two diff erent brackets (MBT and Damon) on dental arch dimensions and incisors position after orthodontic treatment. Methods: In this retrospective study, the records of 20 patients who underwent orthodontic treatment with MBT or Damon bracket systems were studied. All patients had class I skeletal and dental malocclusion and were treated without extraction. The patients were treated either with Damon or MBT bracket systems (n = 10). Lateral cephalograms were traced using the Dolphin software to determine the position of incisors. In addition, transverse dimensions of dental arches were measured on occlusal photographs. Fishers’ exact test, independent-test, Man-Whitney, paired t-test, and Wilcoxon were used for statistical analysis. P < 0. 05 was set as signifi cant. Results: There was no signifi cant diff erence between the two groups regarding age, sex, and initial values of the variables studied. U1-Apog (mm), upper inter-canine, lower inter-second premolar distance showed a signifi cant diff erence before and after treatment in the Damon system. However, no signifi cant diff erence was observed between initial and post-treatment values in the MBT group. L1-Apog (° ), IMPA (° ), maxillary inter-fi rst and second premolars, inter-canine, and mandibular inter-canine distance was higher in the Damon system after treatment compared to MBT. Changes of the upper and lower transverse dimensions of the dental arches and the incisor positional did not reveal a notable diff erence in the Damon and MBT systems (P > 0. 05). Conclusions: There was no signifi cant diff erence regarding changes in dental arches and incisor positions between the Damon and MBT systems.

Background: The spheno-occipital synchondrosis (SOS) is an important growth center which plays an important role in cranial base development and can defi ne the fi nal relation of SOS with the upper and lower jaws. The morphology and fusion degree of SOS varies in diff erent ages among diff erent populations. Objectives: Thus, the aim of this study was to evaluate the age and sex dependence of ossifi cation of the spheno-occipital synchondrosis in the Iranian population using CBCT. Methods: This cross-sectional retrospective study was performed on 517 CBCT images of 6-to 18-year-old patients in Mashhad, Iran. Patients with obvious pathology or fractures were excluded from the study. The SOS ossifi cation was classifi ed into four stages from 0 to 3. Two independent observers scored the images. The ossifi cation stage of the SOS was classifi ed according to the age and sex of the patients. Kruskal-Wallis and Kendall’ s tau-b used for statistical analysis. Results: In this study, 517 samples of 260 females (50. 3%) and 257 males (49. 7%) with a mean age of 12. 03  3. 74 years were examined. A signifi cant diff erence did not exist between males and females regarding their stage of SOS ossifi cation, although males were younger at the SOS transitional stages of 0 to 1, and 1 to 2 compared to females. Also, the SOS starts the ossifi cation process at the age of 11 in females and 10. 8 in males. Conclusions: The present study showed in the mean age of 16. 81  1. 12 years, most subjects were in developmental stage 3. Due to the fact that in developmental stage 3 SOS closes, there were no passive maxillary growth after this time. In none of the SOS stages, females and males diff ered signifi cantly in mean age (P > 0. 05). The age of the onset of SOS closure in females was 11 years and in males it was about 10. 8 years.

Background: With the emerging concept of aesthetics in orthodontics, ceramic brackets play a major role especially in the anterior region of the dental arch. However, the duration of the orthodontic treatment is one of the most important issues in treating patients with ceramic brackets. Objectives: This study is conducted to compare space closing rate between conventional MBT and Symetri Clear bracket systems. Methods: This study is comprised of 18 subjects who were equally separated into two groups. The fi rst group was treated with conventional MBT pre-adjusted bracket and the second group with Symetri Clear TM TM brackets. Space closure was performed via 0. 019  0. 025 inch stainless steel wires using 9-mm nickel-titanium Sentalloy coil springs with a constant force of 150 g. The distance between the distal of the fi rst molar buccal tube and the mesial of the canine bracket was measured by a digital caliper. The diff erence of the fi rst and last values was determined to assess the sheer quantity of space closure. The value was then divided by the number of months during which the space closure was carried out to examine the ratio of space closure in mm per month. For the statistical analysis we used paired t test as well as independent t test and the P-value > 0. 05 was deemed signifi cant. Results: The MBT group showed a 0. 85 mm/appointment retraction rate while the Symetri Clear bracket group had a 0. 83 mm/appointment retraction rate. The diff erence in space closing between MBT and Symetri Clear TM groups was not statistically and clinically signifi cant (P-value > 0. 05). Conclusions: As the rate of space closure was almost similar in the two types of brackets, we can use Symetri Clear TM brackets instead of MBT brackets without any concern about the duration of treatment and use the esthetic benefi ts of these brackets simultaneously.

Background: Recognizing and reviewing the educational curricula of the specialized fi elds of dentistry and comparing it with the curricula of the top universities in the world will help to provide the necessary changes and corrections in postgraduate dental education, leading to more skilled specialists. Objectives: The aim of this study was to compare the orthodontics post graduate curriculum of Mashhad dental school with the top 10 international dental schools. Methods: Twenty-two of the world’ s top universities (10 main and 12 reserve) that off er orthodontics postgraduate programs were selected. A checklist including eight key factors and some secondary variables was prepared. These factors were classifi ed as quantitative and qualitative. The checklist was fi lled with information provided by university websites and contacting program directors using email. A sample t-test and descriptive-analytic approach were respectively used to analyze the quantitative and qualitative data. Results: Among the quantitative factors that were evaluated, only the “ percentage of completely treated patients” was signifi cantly lower in Mashhad dental school compared with that of the top 10 international dental schools. There was no signifi cant diff erence regarding the length of study, the number of professors, and the number of patients visited by each resident. Among the qualitative factors, the most diversity was seen in certifi cates awarded to graduates. Conclusions: No signifi cant diff erence was observed in didactic education, clinical training, and research project conduction between the orthodontics post graduate program of Mashhad dental school and top-tier international universities.

Background: Nano-fl uorohydroxyapatite (nano-FHA) is a caries preventive agent that is applied in many fi elds of dentistry and has the potential of being added to Essix retainers to create antibacterial properties. Objectives: The purpose of this study was to investigate the eff ect of nano-fl uorohydroxyapatite addition on the tensile strength and modulus of elasticity of an Essix plate. Methods: The nano-fl uorohydroxyapatite was synthesized and added to an Essix plate in various weight percentages: 0% (group 1), 0. 1% (group 2) and 0. 5% (group 3). We performed the measuring of fl exural strength and modulus of elasticity for the experimented three groups using a universal testing machine. The data were analyzed through one-way ANOVA and Tukey’ s test at the signifi cance level of 0. 05. Results: Accordingly, the obtained results were indicative of signifi cant diff erences between the groups (P-value = 0. 003); however, the diff erence between group 2 and control group was not statistically notable (P-value = 0. 427). Furthermore, the tensile strength of group 3 signifi cantly decreased (P-value = 0. 04). In regards to the modulus of elasticity, the data were suggestive of signifi cant differences between the groups (P-value = 0. 002). Apparently, the modulus of elasticity of group 2 and group 3 decreased signifi cantly compared to that of the control group (group 1). Conclusions: We can conclude that nano-FHA can be incorporated into Essix plates in concentrations of up to 0. 1 wt% in order to create some caries preventing eff ects with no negative eff ects on tensile strength; however, adding nano-FHA to Essix plate will decrease modulus of elasticity.

Context: The labial cortical bone may infl uence the outcomes of several treatments including fresh socket implant placement and orthodontic treatments. A thin labial plate may contribute to increased risks of periodontal consequences during dental procedures. Acknowledgment of the average values may guide clinicians to take particular considerations in making treatment decisions. Therefore, this study aimed to systematically review the labial cortical bone thickness (LBT) in the anterior maxillary teeth. Objective: The primary purpose of this study was to review the LBT in the anterior maxillary teeth to present the range of average LBT in the global population. Evidence Acquisition: An electronic search was conducted in PubMed, Embase, ProQuest, Web of Science, and Scopus databases. English studies that measured the LBT in the maxillary anterior teeth using CT or CBCT scans were deemed relevant. Only studies performed on adult patients with a lack of periodontal disease were included. Results: A total of 49 studies were included. Mean LBT ranged 0. 13-3. 08, 0. 29-4. 2, and 0. 36-4. 5 mm in maxillary central incisor, lateral incisor, and canine, respectively. Expectedly, LBT was aff ected by the vertical level of the measurement point and increased toward the apex. In total, the LBT in the anterior maxilla ranged from 0. 13 to 4. 5 mm. In comparison with other populations, a relatively thin labial plate was evidenced in the Iranian populations. Conclusions: This study showed a wide range of LBT in the esthetic zone. A thin plate in the esthetic area necessitates caution in orthodontic treatments, particularly when tooth expansion or proclination is required. Additionally, wide ranges of reported values which are mostly under 2 mm, highlight the importance of CBCT acquisition before any fresh socket implant placement.