Education
Saeedeh Mokhtari; Alireza Heidari; Milad Zarei
Abstract
Aim: Dentistry is a stressful profession, and dental students are susceptible to different forms of stress and psychological pressures. Investigating the amount of this stress and knowing the sources that cause it, can help in creating a supportive and stress-reducing educational environment.
Methods: ...
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Aim: Dentistry is a stressful profession, and dental students are susceptible to different forms of stress and psychological pressures. Investigating the amount of this stress and knowing the sources that cause it, can help in creating a supportive and stress-reducing educational environment.
Methods: Fifty-nine senior dental students of Tehran Faculty of Dentistry participated in this cross-sectional descriptive study. The data was collected by DASS-21 questionnaire using a 4-scale measure. The total stress scores of the students were calculated at the clinical departments of the Dental School. The severity of depression, anxiety, and stress was calculated for the students. The comparison of the total stress scores at different departments was made by ANOVA, and the effect of demographic factors on predicting the stress scores was determined by linear regression analysis. P-values <0.05 were considered as significant.
Results: Among the total participants, 72.9% (n=43) showed different levels of depression; 57.7% (n=34) had different levels of anxiety and 64.3% (n=38) exhibited different levels of stress. The total stress scores of the students were mostly reported in the endodontics (12.59, P<0.05) and oral medicine (9.2, P<0.05) departments, while the least total scores were found in the orthodontics (3.89, P<0.05) and oral and maxillofacial surgery (4.25, P<0.05) departments.
Conclusion: The senior dental students in Tehran University of Medical Sciences have high levels of depression, anxiety, and stress. The highest levels of stress were related to the departments of endodontics and oral medicine among the educational departments. It appears that dental students living away from their families and the students whose mothers have high educational levels require further support in this respect.
Yahya Baradaran Nakhjavan; Farid Baradaran Nakhjavan; Mina Sedarat
Abstract
Aim: Disorders of dentition and gums are highly common in contemporary societies and its prevalence is increasing gradually. All psychological and social problems due to dentofacial esthetics and oral function and periodontal disease deterioration and dental caries has made orthodontic treatments important ...
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Aim: Disorders of dentition and gums are highly common in contemporary societies and its prevalence is increasing gradually. All psychological and social problems due to dentofacial esthetics and oral function and periodontal disease deterioration and dental caries has made orthodontic treatments important and considering that the relationship of molars is the key to occlusion, this study examines the occlusion relationship (1st molar- canine). Materials and methods: 1800 students aged 9-10 from 20 regions of Tehran were randomly selected and studied using cross-sectional method. After excluding mentally retarded and aberrant ethnicities and those with previous orthodontic treatment from sample size, the remnants were examined as 5 groups (class I, class II, class III, different right and left, unidentifiable) based on Angel classification. Results: 48.4% of subjects were identified to have class I occlusion, 25.6% class II, 6.7% class III, 15.9% had different right and left, and 3.3% had unidentifiable occlusion. Conclusion: the prevalence of normal occlusion in this study was much lower compared with similar studies in other parts of the world and in Iranian literature as well. Malocclusion showed an ascending fashion; disagreement of class I and II malocclusions with similar Iranian and foreign studies seem to explain genetic background, type of diet, differences in instrument and measurements, and sample size and ethnicity and other factors.
Yasamin Farajzadeh Jalali; Maryam Nasiri; Farnaz Jabbari
Abstract
Background: Achieving esthetics is the most important objective of the modern orthodontics. The introduction of a standard, called the divine proportion for the evaluation of a profile, can lead orthodontic, orthopedic and surgical treatment to obtain maximum facial beauty.
Objectives: The aim of this ...
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Background: Achieving esthetics is the most important objective of the modern orthodontics. The introduction of a standard, called the divine proportion for the evaluation of a profile, can lead orthodontic, orthopedic and surgical treatment to obtain maximum facial beauty.
Objectives: The aim of this study is to analyze the divine proportion in the face of Iranian normal females and the ability of that using as a standard and index to analyze harmony in patient’s face before and after orthodontic treatment along with other common cephalometric analyses.
Patients and Methods: The selected samples included twenty 19 - 26 years old females. Full-face and profile photography and lateral cephalometric radiography were taken; initially the cephalometric radiography were used for conducting common cephalometric analyses in order to compare them with the results gained from the divine proportion measurements. Seven ratios in photography and twelve ratios in radiography calculated. Radiographic and photographic data were analyzed separately using multivariate analysis of variance (MANOVA) and one-sample t-test and compared with 1.618 (golden ratio).
Results: The average values vary from 1.4 to 1.7; the ratio R11 with the average value of 1.613 was the closest value to 1.618. Three cephalometric variables (R3, R8, R12) and two photographic ones (R6 and R7) had a significant difference with 1.618.
Conclusions: The divine proportion on the soft ratio can be a good standard to assess an orthodontic treatment. Divine proportion covers a wide domain and there is a long way ahead of these studies; so it can be extended even more in future.
Mohammad Reza Jamalpour; Mohammad Moslem Imani; Atefe Saffar Shahroudi; Sina Oladzadeh
Abstract
Background: Facial trauma is a common sport-related injury and risk of this injury in contact sports is greater than non-contact sports. Facial trauma has been suggested as a possible etiologic factor of temporomandibular disorder (TMD).
Objectives: The purpose of this study was to investigate the frequency ...
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Background: Facial trauma is a common sport-related injury and risk of this injury in contact sports is greater than non-contact sports. Facial trauma has been suggested as a possible etiologic factor of temporomandibular disorder (TMD).
Objectives: The purpose of this study was to investigate the frequency of TMD and its clinical manifestation in boxers of Islamic Republic of Iran national team. Materials and Methods: In this study, thirty-two male players with average age of 23.75 ± 2.21 who were playing boxing more than 6 years were evaluated regarding TMD. After taking the history, a clinical examination was performed for each athlete. The presence of at least a sign or symptom was considered as TMD diagnosis. Data were collected and presented as descriptive findings. Results: Of 32 boxers, 28.1% (9 cases) had TMD and 71.9% (23 cases) were healthy. The most common symptom was ante-auricular pain (25%) followed by neck pain (21.87%) right ante-auricular tenderness (9.37%) muscle tenderness (9.37%), neck tenderness (9.37%) and headache (3.12%). The uppermost sign was right joint click (25%) followed by left joint click (12.5%) and jaw deviation during mouth opening (12.5%).average age of (25 ± 2 years) and boxing record (10.44 ± 2.29 years) of athletes with TMD were higher than average age of (23.26 ± 2.4 years) and boxing record (7.26 ± 1.76 years) of athletes without TMD.
Conclusions: This study showed that the prevalence of various sign and symptoms of TMD is relatively high in boxers which could result from boxing-related facial trauma.
Navid Naseri; Pedram Baghaeian; Maryam Javaherimahd; Fatemeh Gorjizadeh
Abstract
Background: It has been proved that, there's craniofacial asymmetry but much of this skeletal asymmetries are clinically ignorable. This asymmetry may exist in teeth size arranged in right and left sides of human mouth too. Orthodontists should pay attention to bilateral tooth asymmetry in treatment ...
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Background: It has been proved that, there's craniofacial asymmetry but much of this skeletal asymmetries are clinically ignorable. This asymmetry may exist in teeth size arranged in right and left sides of human mouth too. Orthodontists should pay attention to bilateral tooth asymmetry in treatment planning stage.
Objectives: This study was conducted to demonstrate whether the difference between size of left and right side teeth is actual. Materials and Methods: A total of 200 plaster dental molds were used which were collected from a private practice in Tehran. A caliper with accuracy of 0.01 mm was used for measuring teeth and most teeth were measured twice and the average value was considered as the teeth size. In all cases, the Vernier calipers jaws were moved along the teeth longitudinal axis and the biggest width was measured in the contact point area. Results: In average 83.16% of left and right teeth in upper jaw and 83.66% of left and right teeth in the lower jaw were not symmetrical and teeth in the upper and lower jaws were completely similar 16.84% and 16.34%, respectively.
Conclusions: The result of the study showed that nearly 83% of teeth in maxilla and mandible are asymmetric in mesiodistal width. Mandibular second molar and canine showed the highest and lowest bilateral asymmetry respectively.
Roya Naseh; Nima Rahnamoon; Maryam Afshari
Abstract
Background: Assure Universal Bonding Resin is capable of providing a strong bond between orthodontic attachments and amalgam surfaces.
Objectives: This study sought to assess the shear bond strength of orthodontic attachments to amalgam surfaces using Assure Universal Bonding Resin after different surface ...
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Background: Assure Universal Bonding Resin is capable of providing a strong bond between orthodontic attachments and amalgam surfaces.
Objectives: This study sought to assess the shear bond strength of orthodontic attachments to amalgam surfaces using Assure Universal Bonding Resin after different surface treatments.
Methods: This in-vitro experimental study was conducted on 120 amalgam samples in eight groups of surface roughening with diamond bur, sandblasting with aluminum oxide particles, Er, Cr: YSGG laser irradiation and polishing-only. Molar buccal tubes were bonded to amalgam surfaces using Assure primer and Transbond Plus light-cure composite. Half the samples were immediately subjected to shear bond strength testing while the remaining half were incubated at 37°C for one week, thermocycled (1000 cycles) and were then subjected to shear bond strength test. One-way ANOVA was applied to compare the bond strength of the groups and Tukey’s test was used for pairwise comparisons. The adhesive remnant index (ARI; 4 point-scale) was also determined in the groups and the results were analyzed using the Kruskal-Wallis test. Results: Significant differences were noted in shear bond strength of attachments following the application of Assure among different surface treatment modalities (P < 0.001); the highest bond strength was noted in sandblasted group followed by laser, bur and polishing, respectively. Aging had no significant effect on bond strength.
Conclusions: Sandblasting and irradiation of Er, Cr: YSGG laser provided sufficiently high bond strength between amalgam and attachments following the application of Assure. Diamond bur and polishing did not provide adequately high bond strength.
Sanaz Soheilifar; Mohammad Ali Momeni
Abstract
Background: According to the close proximity of hyoid bone with dentofacial structures and its muscular attachments, a probable relationship between it and different types of skeletal patterns is suspected.
Objectives: The aim of this study is compare the position of hyoid bone in skeletal class I and ...
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Background: According to the close proximity of hyoid bone with dentofacial structures and its muscular attachments, a probable relationship between it and different types of skeletal patterns is suspected.
Objectives: The aim of this study is compare the position of hyoid bone in skeletal class I and class II patients.
Methods: In this study 50 cephalograms were divided into two groups, skeletal class I (1 ≤ ANB ≤ 4) and skeletal class II (ANB > 4), with 24 and 26 patients in each group, respectively. Horizontal and vertical position of hyoid bone were evaluated. SPSS software and student t-test were used to analyze the data. Results: According to the results of our study, there is no statistically significant difference between the hyoid bone position in skeletal class I and skeletal class II patients.
Conclusions: Since the hyoid bone position is similar in skeletal class I and class II patients, the skeletal pattern is not the only determinant of the position of hyoid bone.
Mohsen Shirazi; Armin Soudi; Pedram Baghaeian; Yasamin Farajzadeh Jalali
Abstract
Background: The aim of this study was to investigate the crystal structure of mineral part in the Compact and Cancellous bones in different areas of alveolar bones.
Methods: In this study, 7 alveolar bone samples were prepared from buccal and distal plates of the jaws of three patients, and 4 samples ...
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Background: The aim of this study was to investigate the crystal structure of mineral part in the Compact and Cancellous bones in different areas of alveolar bones.
Methods: In this study, 7 alveolar bone samples were prepared from buccal and distal plates of the jaws of three patients, and 4 samples from Cortical and Cancellous bone of two other patients' palate. After converting all the samples into powder, the samples were examined by using the X-RD method. Diffractogram of 1-7 samples were compared with each other and Diffractogram of 8-11 samples also were compared with each other too. Results: Comparing two corresponding points in the jaws the crystallinity degree in the mandible is higher than the maxilla. In comparison of two corresponding points in the maxilla and mandible degree of crystallinity and the crystalline hydroxyapatite on the right has been more than on the left. The amount of crystalline hydroxyapatite phase in females is more than males and crystallinity degree of this phase in males is more than females, and in younger people, the hydroxyapatite crystalline phase is more than others and crystallinity of this phase in older subjects is higher than others.
Conclusions: Tooth movement, despite the influence of the same forces, is faster on left side than the right side and is faster on maxilla than mandible. Tooth movement is faster in younger people than in older subjects.
Vishal Bharadwaj; Gurkeerat Singh; Sridhar Kannan; Raj Kumar Singh; Ashish Gupta; Gaurav Gupta; Abhishek Goyal
Abstract
Background: Non-extraction treatment protocols are better accepted by patients as well as clinicians. Among the techniques and mechanics with the potential to facilitate non-extraction treatment includes headgears, fixed sagittal correctors, transverse expansion screws and self-ligating systems.Objectives: ...
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Background: Non-extraction treatment protocols are better accepted by patients as well as clinicians. Among the techniques and mechanics with the potential to facilitate non-extraction treatment includes headgears, fixed sagittal correctors, transverse expansion screws and self-ligating systems.Objectives: To evaluate the intra-arch dimensional changes in moderate crowding cases, treated non-extraction with a passive self-ligating (Damon 3MX) appliance using digitized models and lateral cephalograms.Methods: A total of 20 patients (age group of 15 - 18 years) who had undergone non extraction orthodontic treatment with the Damon 3MX appliance were selected. All the pre-treatment and post-treatment dental stone models of maxillary and mandibular arches were scanned using 3D digital scanner (Maestro 3D, Greatlakes, USA) and were converted into digital models. Various parameters undertaken were measured digitally on the computer in millimetres. Cephalometric tracings of pre and post treatment cephalograms were performed using digital cephalometrics (Nemo Ceph, version 6.0, Spain). Statistical analysis was performed using t-test. Results: More transverse expansion was observed in the region of 1st and 2nd premolars as compared to the inter-canine and inter molar region in maxillary and mandibular arch. However a decrease in arch depth was observed in maxillary arch but arch depth of mandibular arch was found to be increased. There was significant increase in anterior proclination in both maxillary and mandibular arches.Conclusions: Passive self-ligating system causes a significant increase in transverse width in both maxillary and mandibular dental arches.
Gregory S Antonarakis; Stavros Kiliaridis
Abstract
Large variation exists amongst patients with regards to treatment outcomes following functional appliance treatment in growing children. Various factors have been assessed with regard to this variation, but evidence is scarce. Recent studies suggest that the initial condition of the masticatory muscles ...
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Large variation exists amongst patients with regards to treatment outcomes following functional appliance treatment in growing children. Various factors have been assessed with regard to this variation, but evidence is scarce. Recent studies suggest that the initial condition of the masticatory muscles may be one of the factors that influences treatment and post-treatment functional appliance outcomes. Children with weaker masticatory muscles show greater dentoalveolar change, as witnessed by incisor compensation and molar movement. Following functional appliance treatment, children who show greater dentoalveolar treatment change may also be those with a more likely post-treatment sagittal relapse. The gonial angle may also be a variable determining treatment outcomes with functional appliances in that more incisor compensation and a greater likelihood for relapse is evident in those with a more open gonial angle. The gonial process is the site of muscle attachment for the masseter and median pterygoid muscles, and the thickness and force of these muscles can have an effect on the process and its contribution to mandibular morphology. By extrapolation, cephalometric analysis of the gonial angle can perhaps provide insight into the amount of incisor proclination expected to be observed during and after functional appliance treatment.
Arman Mohammadi Shayan; Monireh Rassouli; Soodabeh Kimyai; Hadi Valizadeh; Mohammad Hossein Ahangar Atashi; Sahand Rikhtegaran
Abstract
Background: White spot lesion is considered as one of the main problems in the orthodontic treatment. Brackets used in fixed orthodontic treatment create an environment that provides enamel demineralization.Objectives: The objective of the current study was to perform an in vitro study to compare different ...
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Background: White spot lesion is considered as one of the main problems in the orthodontic treatment. Brackets used in fixed orthodontic treatment create an environment that provides enamel demineralization.Objectives: The objective of the current study was to perform an in vitro study to compare different applications of fluoride supplements on enamel demineralization adjacent to orthodontic brackets and finally to understand the best supplement to recommend the patients.Methods: One hundred and twenty extracted caries-free human premolar teeth were randomly assigned into six groups: group 1: Control group, group 2: Fluoride toothpaste, group 3: Fluoride toothpaste/mouth rinse, group 4: Fluoride toothpaste/vanish, group 5: Fluoride toothpaste/gel and group 6: Fluoride toothpaste/foam. After bonding the brackets to the teeth, the fluoride supplements were applied based on each group above, except the control group. Then all the specimens were cycled for 30 days in demineralization solution for 8 hours a day, rinsed, placed in artificial saliva for 4 hours a day, brushed (except the control group), and put back to artificial saliva for 12 hours. DIAGNOdent laser fluorescence was used to quantify the demineralization changes. Results: Significant differences existed between all fluoride-containing groups and control group. Analyses of the results showed a significant difference between control group and the rest 5 treatment groups (P < 0.001). Other significant differences were between groups 2/5, 3/5, 2/4 and 5/6 (P < 0.05). There was no significant difference among the other groups (P > 0.05).Conclusions: According to the results, all fluoride supplements could be used during orthodontic treatment to decrease the enamel demineralization. It has been illustrated that fluoride-containing toothpaste and mouth rinse is better than no fluoride treatment but is not effective as well as fluoride gel and varnish.
Nilesh Mote; Vishal Dhanjani; Somit Das; Kunal Pallan
Abstract
Friction is defined as the force that resists a movement when objects move tangentially against each another. Various forces arise, when two surfaces which are in contact slide against one another. An orthodontist has various difficulties related to friction specially with sliding mechanics and has to ...
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Friction is defined as the force that resists a movement when objects move tangentially against each another. Various forces arise, when two surfaces which are in contact slide against one another. An orthodontist has various difficulties related to friction specially with sliding mechanics and has to deals with it successfully to provide effective tooth movement. During Orthodontic treatment, sliding mechanics is used widely. Friction generated at the bracket/archwire interface is one of the disadvantages of this mechanics, which reduces the quality of desired orthodontic movement acquired. Both clinicians and scientists have an interest in the role of friction in Orthodontics, due to its application. As per clinical studies, the resistance to bodily tooth movement by sliding has far too less to do with friction. It is mainly a binding-and-release situation that is similar to conventional and self-ligating brackets.
Neda Eslami; Farid Sharifi; Athar Nasseri; Arezoo Jahanbin
Abstract
Background: There is great controversy regarding the effect of MBT and Damon bracket systems on dental arch dimensions and incisor position.
Objectives: We aimed to study the effects of two different brackets (MBT and Damon) on dental arch dimensions and incisors position after orthodontic treatment.
Methods: ...
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Background: There is great controversy regarding the effect of MBT and Damon bracket systems on dental arch dimensions and incisor position.
Objectives: We aimed to study the effects of two different 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 significant.
Results: There was no significant difference 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 significant difference before and after treatment in the Damon system. However, no significant difference was observed between initial and post-treatment values in the MBT group. L1-Apog (°), IMPA (°), maxillary inter-first 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 difference in the Damon and MBT systems (P > 0.05).
Conclusions: There was no significant difference regarding changes in dental arches and incisor positions between the Damon and MBT systems.
Alok Ranjan; Anil Kumar Biradar; Ankita Patel; Vanessa Varghese; Ankita Pawar; Rohit Kulshrestha
Abstract
Objectives: This studied aimed to measure the yield strength and stress relaxation properties of three commercially available thermoplastic aligner materials.
Methods: The three different thermoplastics aligner materials Duran (Scheu, Iserlohn, Germany), Erkodur (Pfalzgrafenweiler, Erkodent, Germany) ...
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Objectives: This studied aimed to measure the yield strength and stress relaxation properties of three commercially available thermoplastic aligner materials.
Methods: The three different 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 significance. 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/cm2 as compared to Erkodur, which was 13.96 N/cm2 and 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 influenced by the composition of aligner material and its thickness. Duran had the highest stress release and yield strength. Stress released by different aligners exceeds around half of the initial stress value, which directly affects the orthodontic force application and subsequent tooth movement.
Mahtab Nouri; Sohrab Asefi
Abstract
Introduction: The role of nasal septum in development of the maxilla after birth remains to be a question. Study of monozygotic twins may elucidate the role of epigenetic factors in growth and development of craniofacial structures.
Case Presentation: Herein, we report a case of 16 year-old male monozygotic ...
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Introduction: The role of nasal septum in development of the maxilla after birth remains to be a question. Study of monozygotic twins may elucidate the role of epigenetic factors in growth and development of craniofacial structures.
Case Presentation: Herein, we report a case of 16 year-old male monozygotic twins with Angle class III malocclusion and high angle facial pattern. One of them (patient M.H) had a history of mid-face trauma at the age of 6. Radiographic and clinical examinations revealed significant nasal septum deviation and the patient demonstrated nasal airway obstruction on the right side. The effects of this traumatic injury and the consequences of septal deviation were evident both clinically and radiographically at the age of 16. Increased airway resistance caused by septal deviation significantly affected the arch form and the configuration of the nose. The overall facial growth pattern is predetermined genetically but vertical dimension of the face may be more influenced by the environmental factors.
Conclusions: Patients should be carefully monitored after trauma to the nose and face and any deviation in the facial structure should be treated promptly in order to prevent asymmetries.
Orthodontics
Mahdjoube Goldani Moghadam; Hanieh Kazemi; Mohadese Bani Asadi
Abstract
Aim: This study aims to compare the shear bond strength (SBS) of different combinations of retainer wires and enamel preparation methods.Methods: A total of 180 extracted mandibular bovine incisors were randomly divided into nine groups of 20 paired teeth each. Three techniques were employed to prepare ...
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Aim: This study aims to compare the shear bond strength (SBS) of different combinations of retainer wires and enamel preparation methods.Methods: A total of 180 extracted mandibular bovine incisors were randomly divided into nine groups of 20 paired teeth each. Three techniques were employed to prepare the enamel: acid etches only, Er:YAG laser before acid etch, and sandblast before acid etch. The retainer wires, including Bond-A-Braid, GAC Wildcat Twistflex Wire, and TruForce coaxial wire, were bonded with the adhesive Transbond LR and SBS values were measured. The two-way ANOVA test was used to evaluate the effect of the conditioning method in combination with the retainer wire type and the interaction of two variables. Pairwise comparisons were done using the Tukey post hoc test. A value of P≤0.05 was considered to be significant for all statistical tests.Results: The highest shear bond strength value was found for sandblasted surface bonded with Bond-A-Braid wire. The combination of acid-etched enamel/GAC Wildcat Twistflex wire revealed the lowest value of the SBS. Statistically significant differences did not exist for the Adhesive Remnant Index (ARI) scores among the study groups.Conclusion: Sandblasting and laser irradiation before the acid etching significantly increased the SBS. Differences in the SBS values of different wires were insignificant.
Dental Materials
Seyed Mohammad Mousavi; Sara Mahboubi; Salmeh Kalbassi; Vahid Rakhshan
Abstract
Aim: The aim of this investigation was to assess the efficacy and force decay of elastomeric chains based on their morphology and elongation extent.Methods: Two-hundred-and-seventy elastics from three companies [Ortho Technology (OT), American Orthodontics (AO), G&H, 10 specimens ×27 subgroups] ...
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Aim: The aim of this investigation was to assess the efficacy and force decay of elastomeric chains based on their morphology and elongation extent.Methods: Two-hundred-and-seventy elastics from three companies [Ortho Technology (OT), American Orthodontics (AO), G&H, 10 specimens ×27 subgroups] were elongated to 40%, 60%, and 100% and the initial forces were measured. Then after four weeks of incubation in artificial saliva, the residual forces were measured. Forces and force decays were compared across brands, morphologies, and elongation extents (α=0.001).Results: Forces degraded significantly over time (repeated-measures ANOVA, P<0.001). Significant differences existed among the levels of all parameters, in terms of the initial forces, residual forces, and force degradation (3-way ANOVA, P<0.001). Results of most of the Tukey post hoc tests were significant (P<0.001). The longer the elongation extent, the higher the force waste (partial correlation coefficient, r=0.885, P< 0.001).Conclusion: Initial force was improved when using the OT brand and closed elastics, and by stretching the elastic to 100%. Force loss was minimized when using the G&H brand and open elastics, and by stretching to 40%. Using the OT brand and closed elastics, and 100% stretching caused the highest residual forces after a month. However, the initial forces provided by the 100% elongations were not sound. Force loss was increased by using the OT brand and closed elastics, and with 100% elongations. The lowest residual forces were seen in the AO brand, long elastics, and those elongated to 40%.
Dental Materials
Sherin Johnson; Sameena Begum; SM Laxmikanth; Raghunandan Chunduri; Khadeer Riyaz; Anju Varughese
Abstract
Aim: This study evaluated the effect of physical and chemical sterilization techniques on the fracture resistance of mini-implants.Methods: Thirty-two titanium mini-implants of 1.5 x 8 mm were randomly divided into four groups: control, steam sterilized, dry heat sterilized, and chemically sterilized. ...
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Aim: This study evaluated the effect of physical and chemical sterilization techniques on the fracture resistance of mini-implants.Methods: Thirty-two titanium mini-implants of 1.5 x 8 mm were randomly divided into four groups: control, steam sterilized, dry heat sterilized, and chemically sterilized. The samples were then tested in the air for fracture resistance using a universal testing machine. A tangential load was applied to the head of the mini-implant with a 1 mm/min crosshead speed after blocking each of them in the machine. Also, the maximum load was recorded previous to screw fracture. he Kruskal-Wallis test and Mann-Whitney post hoc test were used for data analysis.Results: The results of this study demonstrated the mean fracture resistance difference between the four groups was statistically significant at p<0.001. Moreover it was showed the control group had significantly higher mean fracture resistance compared to dry heat and chemically sterilized groups at p=0.001 and p=0.009 respectively. This was followed by the stem sterilized group demonstrating significantly higher mean fracture resistance as compared to dry heat and chemically sterilized groups at p=0.001 and p=0.01 respectively. Later, the chemically sterilized group also showed significantly higher mean fracture resistance as compared to the dry heat group at p=0.002. However, no significant difference was observed between the control and stem sterilized groups (p=0.29).Conclusion: The steam sterilized group demonstrated the highest fracture resistance that was followed by the chemically sterilized group, and the least with the dry heat sterilized group.
Nasrin Farhadian; Amirfarhang Miresmaeili; Loghman Rezaei Soufi; Fahimeh Baghaei; Ehsan Shahvali
Abstract
Aim: of this in vitro study was to evaluate the effects of Co2 laser irradiation on demineralization adjacent to orthodontic brackets and their shear bond strength in human premolar teeth. Enamel demineralization adjacent to orthodontic brackets is a major problem that requires new professional method ...
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Aim: of this in vitro study was to evaluate the effects of Co2 laser irradiation on demineralization adjacent to orthodontic brackets and their shear bond strength in human premolar teeth. Enamel demineralization adjacent to orthodontic brackets is a major problem that requires new professional method independent to patient cooperation.
Materials and methods: Sixty human premolars were randomly divided to two groups (n=30). Group1, enamel surface irradiated with Co2 laser. Group2 without any enamel surface treatment. In both groups, a bracket at buccal surface was bonded with Transbond XT and cured with conventional light cure. Demineralization in all sample induced with artificial caries solutions. A universal testing machine was used to determine shear bond strengths. The teeth were sectioned bucco-lingually and were evaluated under polarized light microscope. Average lesion depths were calculated from three depth measurements. The Two independent sample T- tests were used to compare the study type group in detail.
Results: The mean of shear bond strengths in the group1 and 2 were 13.90±5.01and 15.84 ±3.68 Mpa respectively, but not statistically significant (P=0.102).The mean lesion depth in group1and 2 was 72.29±58.09 µm 120.01±76.49µm respectively, which was significant (P=0.018). Conclusion: Co2 laser irradiation can reduce enamel demineralization while not affecting the shear bond strengths significantly.
Mohsen Shirazi; Homa Farhadifard; Meisam Moradi; Hamid Golshahi
Abstract
Introduction: Cleft lip and palate (CLP) is the most common congenital facial anomaly. Its incidence varies according to epidemiologic studies but is usually between 1 and 1.82 for each 1000 births. The etiology of this malformation is complex and includes both genetic and environmental factors.
Case ...
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Introduction: Cleft lip and palate (CLP) is the most common congenital facial anomaly. Its incidence varies according to epidemiologic studies but is usually between 1 and 1.82 for each 1000 births. The etiology of this malformation is complex and includes both genetic and environmental factors.
Case Presentation: In this article a 13-year-old girl with CLP is presented. She was treated with expansion of maxillary arch form, bone grafting, pre surgical orthodontics, orthognathic surgery and minor esthetic surgical procedure.
Conclusions: Satisfactory results regarding functional occlusion, dental esthetics, and facial esthetics were achieved in the patient.
Zahra Dalili Kajan; Navid Karimi Nasab; Jalil Khademi; Faegheh Gholinia; Zeinab Taheri; Mona Hajighadimi
Abstract
Background: Proper defining of normal landmarks in lateral cephalograms is important for establishing proper orthodontic treatment plan.
Objectives: To evaluate the agreement of dental students to identify normal landmarks (NLs) in digital lateral cephalograms and cone beam computed tomography (CBCT) ...
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Background: Proper defining of normal landmarks in lateral cephalograms is important for establishing proper orthodontic treatment plan.
Objectives: To evaluate the agreement of dental students to identify normal landmarks (NLs) in digital lateral cephalograms and cone beam computed tomography (CBCT) images.
Patients and Methods: In this study, lateral cephalograms and CBCT images of 11 orthodontic patients were selected. Three fourth-year dental students were asked to identify 19 NLs after calibrating digital lateral cephalograms and 3D CBCT images. Then, the distances of each landmark from the superior and anterior edges of the images were measured for each observer.
Results: The observers’ errors fell within a range of -1.03 to 2.74 in two-dimensional cephalometry and a range of -0.88 to 2.31 in 3D CBCT, showing a 95% limit of agreement. According to the intraclass correlation coefficient (ICC) comparison made by our student observers, only 5% of interobserver assessment in CBCT and 20% in lateral cephalometry showed poor reliability. These same observers showed more agreement when identifying NLs on soft tissue as compared to hard tissue structures and also in detecting NLs located in the midsagittal region rather than on lateral sides in both modalities. Their differences in agreement in detecting midsagittal NLs rather than on lateral sides were statistically significant (P = 0.0001).
Conclusions: The training of cephalometric tracing in orthodontic course based on 3D skull models and imaginary methods was deemed successful in increasing the ability of dental students to determine the precise location of NLs, even on CBCT images.
Mohammad Hossein Toodehzaeim; Seyed Morteza Saadat Mostafavi
Abstract
Background: The aim of this study was to verify the prevalence of three different morphologies of the mandibular and maxillary dental arch in natural normal occlusions and that may help guiding orthodontists customizing shape of orthodontic archwires. The orthodontist should know the mean of inter-canine ...
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Background: The aim of this study was to verify the prevalence of three different morphologies of the mandibular and maxillary dental arch in natural normal occlusions and that may help guiding orthodontists customizing shape of orthodontic archwires. The orthodontist should know the mean of inter-canine and inter-molar width of Iranian population to help as a guide of treatment.
Methods: We examined 132 study models including 66 maxillary and 66 mandibular arches. Three square, ovoid, and tapered templates were overlaid on arches using special software. Samples were categorized according to the adaptability of templates on images. Inter canine and inter molar widths were also measured on casts and recorded. Results: Ovoid was the most frequent form (54%) in Iranian population. Tapered (36%) and square (10%) forms were on second and third steps, respectively. The relative frequencies of tapered and ovoid forms were equal in the mandibular arch while in the maxillary arch, the frequency of ovoid (63%) was significantly higher than tapered (27%).
Conclusions: Ovoid is the most common dental arch form in Iranian population.
Tahereh Hosseinzadeh Nik; Toktam Jalayer; Amine Beymouri; Atefe Saffar Shahroudi; Armin Eftekhari
Abstract
Background: Third molar impaction is a major problem facing the dental profession and its impacts on the dentition has long been a major concern. Third molar is the most frequently impacted tooth. The prevalence of mandibular third molar impaction has been reported from 18 to 32 percent which varies ...
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Background: Third molar impaction is a major problem facing the dental profession and its impacts on the dentition has long been a major concern. Third molar is the most frequently impacted tooth. The prevalence of mandibular third molar impaction has been reported from 18 to 32 percent which varies between populations and races.
Objectives: This study was designed to determine the best retromolar space analysis from available methods with the highest correlation with mesio-distal width of mandibular third molar (MTM) in order to predict its eruption or impaction.
Patients and Methods: Measurements were carried out on digital panoramic radiographs of 98 Iranian patients. One hundred and seventy mandibular third molars were divided into 4 groups: impacted females, impacted males, erupted females and erupted males. Twenty eight points and 24 planes were marked on the radiographs: 11 points in relation to retromolar space analysis and the mesio-distal width of MTM; and 17 points in relation to some anatomic variables assumed to be related to MTM eruption or impaction. Using these landmarks, different methods were tested for analyzing the retromolar space and its relation to the width of the MTM. Student’s t-test was applied for comparison between erupted and impacted groups and ROC curve was drawn to determine the method with the highest specificity and sensitivity.
Results: Among the performed retromolar space analysis, the method that measured the distance between distal surface of second molar and the anterior border of ramus parallel to functional occlusal plane had the highest correlation with the MTM width. Also, the impact of some anatomic factors including posterior ramus height, upper body length, etc. on MTM eruption or impaction was observed.
Conclusions: Retromolar space analysis on panoramic radiographs can be a relatively precise predictor for mandibular third molar eruption or impaction. This study also supports the multifactorial concept about third molar impaction.
Soosan Sadeghian; Farzad Yahyapour; Roshanak Ghafari; Sina Jafari
Abstract
Background: Because of the special anatomy and esthetic considerations, orthodontic and implant treatments are somehow fine and difficult in mandibular anterior zone. The aim of this study was to evaluate anthropometric analysis of the buccal and lingual bone thickness of mandibular anterior zone using ...
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Background: Because of the special anatomy and esthetic considerations, orthodontic and implant treatments are somehow fine and difficult in mandibular anterior zone. The aim of this study was to evaluate anthropometric analysis of the buccal and lingual bone thickness of mandibular anterior zone using CBCT.
Methods: In this descriptive- analytic study CBCT images of 20 (18 - 40 years old) patients (10 men, 10 women) were obtained. Four reference lines were designed for every anterior tooth of mandible. 3D program were used for measuring.
Results: Mean thickness of buccal alveolar plate was 1.44 ± 0.34 mm for central incisor, 1.35 ± 0.25 mm for lateral incisor, 1.46 ± 0.25 mm for canine. Mean thickness of lingual alveolar plate was 1.61 ± 0.33 mm for central incisor, 1.73 ± 0.43 mm for lateral incisor, 1.99 ± 0.48 mm for canine. Buccal bony curvature angle below root apex was 151.1 ± 7.7° at central incisor, 145.14 ± 6.71° at lateral incisor, 155.08±8.16° at canine. Distance between root apex and the deepest point of buccal bony curvature was 2.2 ± 0.54 mm for central incisor, 2.31 ± 0.62 mm for lateral incisor, 2.55 ± 0.59 for canine. However; the comparison of all findings between men and women did not show significant difference (P > 0.05).
Conclusions: The thickness of lingual bony plate of mandibular anterior zone in Iranian adult is more than the thickness of labial plate; also the labial bony plate thickness will increase from coronal to apical zone of the teeth. The labial bony curvature below root apex of mandibular central incisor was higher than that of lateral incisor and canine and it seems that the labial bony plate below root apex of central incisor is most curved.
Javad Chalipa; Mehrnoush Momeni Roochi; Mahsa Mortazavi; Elahe Soltanmohamadi Borujeni; Sarvin Sarmadi; Maryam Khodabakhshi; Mohammad Hashem Hosseini
Abstract
Background: Severe skeletal class III malocclusions usually need a combined treatment of orthodontics and orthognathic surgery. Knowing about changes occurred following such treatments lead to improve facial esthetics and better treatment results.
Objectives: This study was done to determine cephalometric ...
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Background: Severe skeletal class III malocclusions usually need a combined treatment of orthodontics and orthognathic surgery. Knowing about changes occurred following such treatments lead to improve facial esthetics and better treatment results.
Objectives: This study was done to determine cephalometric changes of facial soft tissue after combined treatment in patients with skeletal class III problem.
Methods: 25 patients with skeletal class III discrepancy who needed a combined treatment, were selected. Changes in nasolabial angle , upper lip and lower lip to E-line distance, angle of convexity , lip-chin-throat angle and lower anterior facial height were measured before and 6 - 12 months after surgery. Changes in parameters were analyzed with Paired t-test. Results: Upper lip to E-line distance (P < 0.0001) and angle of convexity (P < 0.001) changed significantly following surgical procedures while changes of other parameters were not significant.
Conclusions: Clinical changes in the soft tissue following a combination of orthodontic treatment and orthognathic surgery in patients with skeletal class III discrepancy are significant while these changes mostly improves esthetics of patient’s facial profile.
