The Effect of Different Soft Drinks on the Force Degradation of Conventional and Memory Orthodontic Elastic Chains: An In-Vitro Study.

Objectives: The aim of this study was to assess how different soft drinks affect the deterioration of conventional and memory orthodontic elastomeric chains. Materials and Methods: We used 500 five-loop segments of elastomeric chains, which were divided into two equal groups of conventional and memory chains. The samples were kept in artificial saliva during the study period. Each group was further divided into 5 subgroups consisting of artificial saliva (controls), Coca-Cola®, non-alcoholic beer (ISTAK®), and carbonated and non-carbonated yoghurt-based drinks (Alis®). Treatment with the soft drinks consisted of immersion in the test liquids twice a day for 3 minutes each time. Force measurements were taken on days 1, 7, 14, 21, and 28. Data were analyzed using One- and three-way ANOVA tests, and independent t-test, with a significance level of 5%. Results: The mean initial force for the conventional and memory elastomeric chains was 3.34±0.112N and 2.49±0.209N, respectively. Conventional chains showed significantly greater degradation than memory chains (P<0.01). Soft drinks had a significant impact on force degradation for both types of chains at all time points (P<0.01). Coca-Cola® had the highest level of force degradation, while non-carbonated yoghurt-based drinks had the lowest (P<0.01). Conclusion: Based on the findings of this study, it is recommended that orthodontic patients choose non-carbonated yoghurt-based drinks during their treatment. Memory elastomeric chains may be more suitable for patients who consume large amounts of carbonated soft drinks, due to their lower amount of force degradation compared to conventional chains.

Evaluating the Efficacy of a Modified Piezo-Puncture Method on the Rate of Tooth Movement in Orthodontic Patients: A Clinical Study.

OBJECTIVE: Owing to the increasing demand from orthodontic patients for a more rapid treatment, many studies have focused on accelerated tooth movement. Currently, one of the prevalent methods to achieve accelerated tooth movement is piezo-puncture. The aim of the present study was to evaluate the effect of a modified piezo-puncture method on tooth movement rate and type during canine retraction. METHODS: A total of 17 patients who required fixed orthodontic treatment with extraction of the maxillary first premolars were included in the study. Following a split-mouth design, upper canines were retracted with Ni-Ti coil spring that applied 150 g of force on each side (piezo-puncture on one side and contralateral side served as the control). Then, the rates of tooth movement, canine angulation and rotation, and anchorage loss were evaluated at T0 (before the intervention), T1 (1 month after the intervention), and T2 (2 months after the intervention). For calculating the canine movement rate, either the distance between the canine and the lateral incisor or the space between the second premolar and the canine was measured. In addition, pain perception was documented by Visual Analog Scale. Data were analyzed using the Kolmogorov-Smirnov normality test, Spearman correlation test, paired sample t-test, and Wilcoxon signed-rank test. RESULTS: No significant acceleration was observed in canine movement, canine tipping, rotation, or anchorage loss of molar in different times. CONCLUSION: Considering the limitations of the study, the application of piezo-puncture employing the protocol used in the present study failed to accelerate tooth movement and to decrease the unfavorable tipping, rotation, and molar anchorage loss.

Effect of Propolis mouthwash on plaque and gingival indices over fixed orthodontic patients.

BACKGROUND: In patients with fixed orthodontics, the presence of orthodontic appliances causes dental plaque accumulation and hygiene problems. The purpose of this study was to evaluate the effect of Propolis and chlorhexidine mouthwashes on plaque and gingival indices in patients who are undergoing orthodontic treatment. MATERIAL AND METHODS: In this triple blind study, in total, 37 patients aged from 15 to 35 years those who have been undergoing fixed orthodontic treatment were studied. After that, one of the mouthwashes that containing either Propolis or Chlorhexidine was randomly prescribed to patients. The patients were asked to use mouthwashes twice a day after brushing their teeth for three weeks consecutively. Indicators of plaque, gingival and periodontal status (PI, GI, CPI) were determined on Ramford teeth at the beginning and at the end of three weeks for each patient. Then the results were analyzed statistically. RESULTS: The difference between the values of plaque index (P<0.001), gingival index (P=0.006) and periodontal index (P= 0.005) before and after administration of Propolis were statistically significant. The difference was also statistically significant for all three indexes of plaque (P<0.001), gingival (P=0.001) and periodontal (P=0.003) before and after chlorhexidine mouthwash usage. The indices after using mouthwashes were not statistically significant different between two mouthwash groups. CONCLUSIONS: It seems that Propolis mouthwash can be used as a suitable alternative in patients with fixed orthodontic treatment without the side effects of chlorhexidine mouthwash. Key words:Mouthwash, antimicrobial, Oral hygiene, Propolis, Dental plaque.

Hyoid bone position in different facial skeletal patterns.

BACKGROUND: Hyoid bone plays a significant role in physiological functions of craniofacial region and it's position adapts to changes of the head. The purpose of this study was to determine the position of the hyoid bone among subjects with class I, class II and class III skeletal patterns and evaluate the gender differences. MATERIAL AND METHODS: One hundred and ten lateral cephalograms (59 females and 51 males) from different skeletal patterns (class I, II and III) were selected. The skeletal patterns were determined according to ANB angle. Using MicroDicom software, different linear and angular measurements (6 variables) was carried out to determine the position of hyoid bone. Intraclass correlation coefficient was used to verify reliability. Descriptive statistics of the variables were calculated and analyzed using two-way ANOVA and Bonferroni statistical methods. RESULTS: The mean distance from the hyoid bone (H) to mandibular plane (MP), to palatal plane (PP), as well as to a third cervical vertebra (C3) was more in males than females (p=0.023, p<0.001, p<0.001 respectively). The mean H to PP distance was significantly more in skeletal class I compared to class III (P=0.01). The mean H to C3 distance was significantly more in skeletal class I compared to class II (P=0.008). The mean angle between H-MP and H-PP did not show any statistical difference among three skeletal classes (p=0.102, P=0.213) and among male and female groups (P=0.172, P=0.904). CONCLUSIONS: The hyoid bone is positioned more superior and posterior in females than males and its location differs among different skeletal classes. It is placed more posterior in skeletal class II patterns and more inferior and anterior in skeletal class I patterns. Key words:Hyoid bone, Lateral cephalometry, Class III, Class II, skeletal pattern, Orthodontics.

Age estimation by canines' pulp/tooth ratio in an Iranian population using digital panoramic radiography.

OBJECTIVE: Age estimation in adults is an important issue in forensic science. This study aimed to estimate the chronological age of Iranians by means of pulp/tooth area ratio (AR) of canines in digital panoramic radiographs. MATERIALS AND METHODS: The sample consisted of panoramic radiographs of 271 male and female subjects aged 16-64 years. The pulp/tooth area ratio (AR) of upper and lower canines was calculated by AutoCAD software. Data were subjected to correlation and regression analysis. RESULTS: There was a significant and inverse correlation between age and pulp/tooth area ratio of upper and lower canines (r=-0.794 for upper canine and r=-0.282 for lower canine; p-value<0.001). Linear regression equations were derived separately for upper, lower and both canines. The mean difference between actual and estimated age using upper canine was 6.07±1.7. CONCLUSION: The results showed that the pulp/tooth area ratios of canines are a reliable method for age estimation in Iranians. The pulp/tooth area ratio of upper canine was better correlated with chronological age than that of lower canine.

Facial Anthropometric Evaluation of Unilateral Cleft Lip and Palate Patients: Infancy Through Adolescence.

INTRODUCTION: Craniofacial anthropometric studies measure the differences in humans' craniofacial dimensions. The aim of this study was to determine facial anthropometric dimensions of newborn to 12-year-old girls with nonsyndromic unilateral cleft lip and palate (UCLP). METHODS: In this cross-sectional analytical study, data was collected from 65 infant to 12-year old girls with UCLP. Digital frontal and profile facial photographs were transferred to a computer and desired anthropometric landmarks were traced on each image. Fifteen anthropometric parameters were measured which were the angles of facial, nasofacial, nasomental, Z, nasolabial, inclination of nasal base and labial fissure, nasal deviation, mentocervical, facial convexity and also ratios of nasal prominence relative to nasal height, middle to lower facial third, upper lip to lower lip height, columellar length relative to upper lip, and incisal show relative to incisal width. Pearson coefficient and linear regression were used for statistical analysis. RESULTS: Upper lip to lower lip height ratio and angles of nasofacial, nasolabial, and facial convexity decreased with the age of the patients. In contrast, nasomental angle and the ratios of columellar length to upper lip length, middle facial height to lower facial height, and incisal show relative to incisal width increased. Other parameters studied did not appear to have any significant correlation with age. CONCLUSION: In the girls with UCLP, various craniofacial dimensions have different growth rates with some parts growing slower than others. Some of the parameters studied were significantly correlated with age, thus growth-related curves and equations were obtained and presented.

Efficiency and Duration of Orthodontic/Orthognathic Surgery Treatment.

INTRODUCTION: To investigate the combined orthodontic-orthognathic treatment times at an academic hospital in the UK and to consider the level of occlusal change in delivering this treatment by the way of comparing peer assessment rating (PAR) scores pre- and post-treatment. METHODS: It was a retrospective longitudinal study of orthognathic patients between 2010 and 2013 who had completed orthognathic treatment. Analysis of records of 50 patients was carried out. Age, gender malocclusion, and skeletal pattern, extraction/nonextraction of teeth, duration of active orthodontic treatment, number of appointments, transfer of patients between orthodontists mid-treatment, and PAR scores pre and post-treatment were recorded for each patient. RESULTS: The skeletal pattern was III in 70% of and II in 28% of patients. Mean duration of active orthodontic treatment was 27.9 months. Age, gender, malocclusion, and skeletal pattern did not seem to affect treatment times. Extraction of teeth and transfer of operators increased treatment times. The mean PAR reduction was 89% with the PAR efficiency factor (reduction in PAR scores divided by duration of treatment in months) of 1.61. Younger patients, those with class III malocclusions and patients starting with higher PAR scores, achieved greater PAR reductions. Gender, number of appointments, extractions, transfer of operators, and total duration of treatment were not shown to affect the PAR % reduction. CONCLUSIONS: Combined orthodontic-orthognathic treatment has been effective in treating patients with severe skeletal discrepancies. Transfer of operators and extractions protracted treatment times. Younger patients and those with class III malocclusions achieved higher PAR % reduction.

Do dental students have a neutral working posture?

BACKGROUND: Dentists are susceptible to Musculoskeletal Disorders (MSDs) due to prolonged static postures. To prevent MSDs, working postures of dental students should be assessed and corrected in early career life. OBJECTIVE: This study estimated the risk of developing musculoskeletal disorders in dental students using Rapid Upper Limb Assessment (RULA) tool. METHODS: A number of 103 undergraduate dental students from fourth and fifth academic years participated. Postures of these students were assessed using RULA tool while working in the dental clinic. They also answered a questionnaire regarding their knowledge about postural dental ergonomic principles. RESULTS: The majority of the students (66%) were at intermediate and high risk levels to develop MSDs and their postures needed to be corrected. There was no significant correlation between RULA score and gender, academic year and different wards of dental clinics. There was no significant correlation between knowledge and RULA scores. CONCLUSIONS: Dental students did not have favorable working postures. They were at an intermediate to high risk for developing MSDs which calls for a change in their working postures. Therefore students should be trained with ergonomic principles and to achieve the best results, ergonomic lessons should be accompanied by practice and periodical evaluations.

Combined chlorhexidine-sodiumfluoride mouthrinse for orthodontic patients: Clinical and microbiological study.

BACKGROUND: Orthodontic appliances impede good dental plaque control by brushing. Antimicrobial mouth rinses were suggested to improve this performance. We therefore aimed to investigate the effects of combined mouthrinse containing chlorhexidine (CHX) and sodium fluoride (NaF) on clinical oral hygiene parameters,and plaque bacterial level. MATERIAL AND METHODS: In this double-blind clinical study, 60 fixed orthodontic patients aged 14-25 years were randomly assigned to one of four mouthrinses groups: 1- combined CHX /NaF 2- CHX 0.06% 3- NaF0.05% 4-placebo. Following baseline examination patients were instructed to use the assigned mouthrinse twice daily for 21 days. Bleeding index (BI), modified gingival index (MGI) and plaque index (PI) were determined at the baselineand after three weeks of rinsing. Samples from supragingival plaque were obtained for the assessment of total bacterial, Streptococcus mutans and Lactobacilli colony counts. Data were analyzed by Wilcoxon, Kruskal-Wallis, and Mann-Whitney tests. RESULTS: Clinical parameters; All three active mouth rinses induced significant improvements of BI, MGI, and PI (P<0.05). Results of CHX/NaF were slightly, but not significantly, better than CHX. CHX/NaF and CHX induced significantly more changes than NaF and placebo. Microbiological measurements; Except placebo, other mouthrinses reduced total bacterial, Streptococcus mutans, and Lactobacilli counts significantly (P<0.05). CHX/NaF acted against Lactobacilli significantly more than others. CONCLUSIONS: Adding CHX0.06%/NaF0.05% combined mouth rinse to daily oral hygiene regimen of orthodontic patients significantly improved oral hygiene status. Effect of this combined mouth rinse on dental plaque Lactobacilli was remarkable. However, large controlled trials could provide more definitive evidence. KEY WORDS: Mouthrinse, fluoride, chlorhexidine, plaque.

Social Determinants of Tooth Loss among a Group of Iranian Female Heads of Household.

Background and aims. Tooth loss may lead to mastication disability, which in turn has important impact on individual's quality of life. Social and psychological factors have been shown to be associated with tooth loss. This study aimed to investigate the social determinants and prevalence of tooth loss, and presence of functional dentition among female heads of household under support of Welfare Organization in Mashhad, Iran. Materials and methods. In current study 556 participants aged 16-76 years were recruited. Sociodemographic characteristics (age, level of education, family size, and monthly income) were collected using interviewer-led questionnaire. Data about number of teeth and functional dentition were obtained by oral examination. The data were analyzed using Chi-square, Kruskal-Wallis, T-test and binary logistic regression analysis. Results. Four percent of participants were edentulous. Tooth loss was significantly associated with level of education, age and family size (P < 0.001). There was no significant association between level of income and tooth loss (P = 0.88). Only 37.5% of dentate subjects had functional dentition (anterior and premolar teeth). Women older than 40 years were 0.63 times less likely to have functional dentition than those younger than 40 years. Females with at least a high-school diploma were six times more likely to have functional dentition than their illiterate counterparts. Conclusion. Social determinants of functional dentition should be taken into account when planning oral health promoting programs for female heads of household. For reducing oral health inequalities access to dental services should be facilitated.

Effect of healing time on bone-implant contact of orthodontic micro-implants: a histologic study.

Objectives. This study aimed to evaluate the effect of immediate and delayed loading of orthodontic micro-implants on bone-implant contact. Materials and Methods. Sixty four micro-implants were implanted in dog's jaw bone. The micro-implants were divided into loaded and unloaded (control) groups. The control group had two subgroups: four and eight weeks being implanted. The loaded group had two subgroups of immediate loading and delayed (after four weeks healing) loading. Loaded samples were subjected to 200g load for four weeks. After sacrificing the animals micro-implants and surrounding tissues were observed histologically. Bone-implant contact ratios (BIC) were calculated and different groups' results were compared by three-way ANOVA. Results. Mean survival rate was 96.7% in general. Survival rates were 96.7%, 94.4% and 100% for control, immediate and delayed loaded groups, respectively. BIC values were not significantly different in loaded and control groups, immediate and delayed loading groups, and pressure and tension sides. Mandibular micro-implants had significantly higher BIC than maxillary ones in immediate loading, 4-weeks control, and 8-weeks control groups (P = 0.021, P = 0.009, P = 0.003, resp.). Conclusion Immediate or delayed loading of micro-implants in dog did not cause significant difference in Bone-implant contact which could be concluded that healing time had not significant effect on micro-implant stability.

The effect of surface treatment with Er: YAG laser on shear bond strength of orthodontic brackets to fiber-reinforced composite.

OBJECTIVES: This study aimed to investigate the effect of surface treatment with Er:YAG laser on shear bond strength (SBS) of orthodontic brackets to fiber-reinforced composite (FRC). STUDY DESIGN: Ninety human premolars were randomly divided into six groups of 15. FRC bars were bonded to the teeth with a flowable composite (FC) and then underwent following treatments. In group 1 no further treatment was performed. In group 2 the FRC surfaces were covered by FC. An Er:YAG laser was employed to treat FRCs in groups 3 ( 200 mJ/10 Hz) and 4 (300 mJ/15 Hz). The FRC strips in groups 5 and 6 were first covered by FC and then irradiated with Er:YAG laser at 200 mJ/10 Hz (group 5) or 300 mJ/15 Hz (group 6). Stainless steel brackets were bonded to FRCs using a light-cure adhesive system. After 24 hours, the samples were tested for SBS and the adhesive remnant index (ARI) scores were determined. RESULTS: There was a significant difference in SBS among the study groups (P <0.001). Pairwise comparisons indicated that SBS was significantly lower in group 1 compared to all other groups (p<0.05) except group 2. Bond strength in group 6 was significantly greater than all the study groups (p<0.05) except group 5. No significant difference was found in ARI scores among the groups. CONCLUSIONS: Covering the FRC surface by a layer of flowable composite and then application of Er:YAG laser at 300 mJ/15 Hz could be recommended to increase bond strength of orthodontic attachments to FRC. Key words:Fiber-reinforced composite, orthodontics, Sshear bond strength, laser, Er:YAG, surface treatment, bracket, FRC.

Musculoskeletal pain reports among Mashhad dental students, Iran.

Dental practitioners are susceptible to Musculoskeletal Disorders (MSDs). The symptoms may begin from education courses. The aim of this study was to assess prevalence of musculoskeletal pain reports and correlated factors among the Mashhad Dental School students, Iran. A total of 177 undergraduate and postgraduate dental students, who were involved in educational clinical training, completed a questionnaire focusing on pain reports of different body anatomical regions. Variables such as gender, academic grade, academic year, clinical working hour, regular exercise times and also pain characteristics including pain duration intensity and frequency were evaluated. As results 82% of undergraduate students and 90% of postgraduate students reported body pain in at least one region. The most prevalent pain locations were: chest/shoulder (46.9%), head/neck (41.8%), middle back (33.9%) and right hand (25.4%). Severity of reported pain was increased due to performing dental work, increased working stress and working fatigue. Regular exercise was associated with alleviated some pain characteristics. As conclusions musculoskeletal pain reports were highly prevalent among dental students. Attention to prevention of musculoskeletal disorders should be considered as priority in dental schools. For dental students exercise training courses for strengthening muscles of shoulder/chest, neck and back are necessary.

New regression equations for mixed dentition space analysis in an Iranian population.

AIMS: Prediction of the mesiodistal crown width of unerupted canines and premolars is an important aspect of mixed dentition analysis. The accuracy of Tanaka-Johnston equations, the most commonly method, is questionable when it is applied to different ethnic groups. In this study, we aimed to develop a new regression equation for this prediction in an Iranian population. MATERIALS AND METHODS: The dental casts of 120 Iranian subjects with complete permanent dentition were selected. Mesiodistal crown widths of teeth were measured with digital caliper. In the first part of the study, the correlation and linear regression equations between four mandibular incisors and the canine-premolars segments of both arches were developed (modified Tanaka-Johnston equation). In the second part, as a new method, correlation and linear regression equations were developed between the sum of mandibular central incisors-maxillary first molars and the canine-premolars segments. RESULTS: It was found that the correlation coefficients between the sum of mandibular central incisors-maxillary first molars and the maxillary and mandibular canine-premolars segments were higher (r = 0.66, 0.68 respectively) than the one between the four mandibular incisors and the canine-premolars segments (r = 0.58. 0.64). CONCLUSION: New linear regression equations were derived. In this study, the sum of mandibular central incisors and maxillary first molars was better predictor for unerupted canines and premolars. This novel approach allows the prediction of width of unerupted canines and premolars to take place at earlier age. CLINICAL SIGNIFICANCE: Using the new method, orthodontists could take advantage of mixed dentition analysis at earlier age. Moreover, to test the derived equations on a larger sample size and in other ethnicities is highly recommended.

Effects of different surface preparations on shear bond strength of orthodontic brackets to porcelain.

The aim of this study was to assess bonding of orthodontic metal brackets to porcelain surfaces using various surface treatment methods. Etching the porcelain with 9.6 percent HF followed by a bonding agent or silane application provided high and acceptable shear bond strengths.