Evaluation of the preventive effect of two concentrations of xylitol varnish versus fluoride varnish on enamel demineralization around orthodontic brackets: a randomized controlled trial.

BACKGROUND: The highly prevalent white spot lesions around orthodontic brackets necessitate introducing preventive materials without relying on patient compliance. OBJECTIVE: To evaluate the antidemineralizing effect of two concentrations of xylitol varnish. TRIAL DESIGN: Triple-blind, four-arm, parallel-group, single-center, randomized controlled clinical trial. METHODS: A total of 120 orthodontic patients were randomly assigned to four groups (n = 30), using a computer-generated randomized block list. The treatment groups were: 10% xylitol, 20% xylitol, 5% fluoride, and placebo. Tooth demineralization was measured with DIAGNOdent at T1 (before treatment), followed by varnish application. At T2 (third month), the varnish was re-applied, and at the third (T2) and sixth (T3) months, and after treatment (T4), the demineralization was measured. The white spot lesion frequency was assessed visually after treatment. The participants, the clinician, and data assessors were all blinded to group assignments. RESULTS: A total of 115 patients underwent per-protocol analyses. At T2, the mean DIAGNOdent numbers in the fluoride and 10% xylitol groups were significantly lower than the placebo group (P = 0.00), with a mean difference of 0.63 (95% CI, 0.15-1.10) and 0.5 (95% CI, 0.04-0.95), respectively. At T3, the fluoride and 10% xylitol groups had significantly lower mineral loss than the placebo group (P=0.046) with a mean difference of 0.52 (95% CI, 0.14-0.89) in the fluoride and 0.45 (95% CI, 0.03-0.86) in the 10% xylitol groups, respectively. However, at T4, only the mean for the 10% xylitol group was significantly different (P=0.049) from the placebo group, with a mean difference of 1.18 (95% CI, 0.42-1.93). Visual assessment showed that after treatment, the prevalence of white spot lesions in the fluoride (P=0.03) and 10% xylitol (P=0.00) groups was less than the placebo group with the odds ratio of 0.67 (95% CI, 0.46-0.96) and 0.43 (95% CI, 0.28-0.64), respectively. CONCLUSION: The 10% xylitol varnish short-term effects on caries control were significantly greater than 20% xylitol varnish and placebo but similar to fluoride varnish. However, the 10% xylitol long-term effect was almost better than fluoride varnish. TRIAL REGISTRATION: The protocol was registered at IRCT.ir under the code IRCT20180913041032N1.

The Application of Palatal Rugae for Sex Discrimination in Forensic Medicine in a Selected Iranian Population.

BACKGROUND: Palatal rugae have been shown to be associated with racial and geographical variations and are known to be useful in sex identification. The present study aimed to assess palatal rugae patterns in a sample Iranian population and to compare the results with those from other studied populations. METHODS: During summer 2017, 130 pre-orthodontic plaster casts from patients aged 17-25 years (65 males and 65 females) were obtained from the Department of Orthodontics, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran. The castes were evaluated using the classification given by Thomas and Kotze followed by recording the rugae lengths and shapes. The data were analyzed with the SPSS statistical software package (version 15.0) using the unpaired t test and Chi-square test. P<0.05 were considered statistically significant. Additionally, discriminant function analysis was applied to determine the applicability of palatal rugae patterns as a tool to aid sex identification. RESULTS: The rugae count showed an insignificant difference between the Iranian males and females. The primary rugae were most common in both sexes followed by the secondary and fragmentary. Significant differences were observed between the sexes and the number of primary rugae in males (P=0.03) and fragmentary rugae in females (P=0.04) on the left side of the palate. A significant difference in the straight and diverging unification types was observed, which was highest in males (P=0.01) and females (P=0.03), respectively. Discriminant function analysis enabled sex identification with an accuracy of 70%. CONCLUSION: Palatal rugae is shown to be an appropriate tool for sex identification in an Iranian population. Further studies with a larger sample size are required for a comprehensive outcome.

Computer Assisted Bone Age Estimation Using Dimensions of Metacarpal Bones and Metacarpophalangeal Joints Based on Neural Network.

Statement of the Problem: Bone age is a more accurate assessment for biologic development than chronological age. The most common method for bone age estimation is using Pyle and Greulich Atlas. Today, computer-based techniques are becoming more favorable among investigators. However, the morphological features in Greulich and Pyle method are difficult to be converted into quantitative measures. During recent years, metacarpal bones and metacarpophalangeal joints dimensions were shown to be highly correlated with skeletal age. Purpose: In this study, we have evaluated the accuracy and reliability of a trained neural network for bone age estimation with quantitative and recently introduced related data, including chronological age, height, trunk height, weight, metacarpal bones, and metacarpophalangeal joints dimensions. Materials and Method: In this cross sectional retrospective study, aneural network, using MATLAB, was utilized to determine bone age by employing quantitative features for 304 subjects. To evaluate the accuracy of age estimation software, paired t-test, and inter-class correlation was used. Results: The difference between the mean bone ages determined by the radiologists and the mean bone ages assessed by the age estimation software was not significant (p Value= 0.119 in male subjects and p= 0.922 in female subjects). The results from the software and radiologists showed a strong correlation -ICC=0.990 in male subjects and ICC=0.986 in female subjects (p< 0.001). Conclusion: The results have shown an acceptable accuracy in bone age estimation with training neural network and using dimensions of bones and joints.

Influence of a bleaching agent on surface and mechanical properties of orthodontic thermoplastic retainer materials : An in vitro study.

OBJECTIVE: To investigate the effect of a tooth whitening agent on surface roughness, surface hardness, and force delivery properties of polyethylene terephthalate glycol (PETG) thermoplastic retainer materials of two different thicknesses. METHODS: PETG sheets (1 mm and 1.5 mm) were thermoformed over a 30â€¯× 60â€¯× 10 mm3 rectangular stone model. Surface hardness, surface roughness, and results of a three-point bending test were evaluated before and after treatment (5 h daily for 14 days) with a 15% carbamide peroxide home bleaching agent. Data were analyzed using an independent sample t­test. RESULTS: Exposure of PETG specimens to the bleaching agent for 14 days significantly reduced surface hardness and increased surface roughness of samples of both thicknesses. The magnitude of force at different deflection points decreased significantly in the 1.5 mm thickness specimens treated with the bleaching agent, but no significant change was observed in the specimens with 1 mm thickness. CONCLUSION: Use of a home bleaching agent could have adverse effects on surface roughness and hardness of PETG materials leading to reduced survival time of thermoplastic orthodontic retainers.

A comparison of photographic, replication and direct clinical examination methods for detecting developmental defects of enamel.

BACKGROUND: Different methods have been used for detecting developmental defects of enamel (DDE). This study aimed to compare photographic and replication methods with the direct clinical examination method for detecting DDE in children's permanent incisors. METHODS: 110 8-10-year-old schoolchildren were randomly selected from an examined sample of 335 primary Shiraz school children. Modified DDE index was used in all three methods. Direct examinations were conducted by two calibrated examiners using flat oral mirrors and tongue blades. Photographs were taken using a digital SLR camera (Nikon D-80), macro lens, macro flashes, and matt flash filters. Impressions were taken using additional-curing silicon material and casts made in orthodontic stone. Impressions and models were both assessed using dental loupes (magnification=x3.5). Each photograph/impression/cast was assessed by two calibrated examiners. Reliability of methods was assessed using kappa agreement tests. Kappa agreement, McNemar's and two-sample proportion tests were used to compare results obtained by the photographic and replication methods with those obtained by the direct examination method. RESULTS: Of the 110 invited children, 90 were photographed and 73 had impressions taken. The photographic method had higher reliability levels than the other two methods, and compared to the direct clinical examination detected significantly more subjects with DDE (P = 0.002), 3.1 times more DDE (P < 0.001) and 6.6 times more hypoplastic DDE (P < 0.001). The number of subjects with hypoplastic DDE detected by the replication method was not significantly higher than that detected by direct clinical examination (P = 0.166), but the replication detected 2.3 times more hypoplastic DDE lesions than the direct examination (P < 0.001). CONCLUSION: The photographic method was much more sensitive than direct clinical examination in detecting DDE and was the best of the three methods for epidemiological studies. The replication method provided less information about DDE compared to photography. Results of this study have implications for both epidemiological and detailed clinical studies on DDE.

Assessment of mandibular characteristics in patients affected with ß-thalassaemia major: A retrospective case-control study.

OBJECTIVE: Thalassemia is the most common hereditary blood disorder across the world. This study aimed to identify some mandibular features of thalassaemic patients and compare them with unaffected counterparts. MATERIAL AND METHODS: This retrospective case-control study was carried out on lateral cephalograms of 60 subjects (26 males, 34 females) with class II malocclusion and age range of 11 to 15 years. The control group consisted of 60 non-thalassaemic subjects with class II malocclusion and similar chronological age, gender and vertical facial dimension. Based on the Jarabak index, the case and control subjects were classified into hyperdivergent, normodivergent and hypodivergent growth patterns. Four linear (ramus height, ramus width, mandibular depth, and antegonial notch depth) and 3 angular (symphyseal angle, gonial angle, and mandibular arc angle) cephalometric parameters were measured to represent mandibular morphology. The data were analysed using Chi-square test and Student's t-test. RESULTS: No significant difference was found in linear measurements between thalassaemic patients and controls. The symphysis angle was significantly greater and the mandibular arc angle was significantly smaller in the total thalassaemic sample than the control individuals (P<0.001 and P=0.004, respectively). The difference in symphysis angle was significant in both hyperdivergent and normodivergent subjects (P=0.004 and P=0.002, respectively), whereas the difference in mandibular arc angle was only significant in the normodivergent subgroup P=0.001). CONCLUSIONS: The smaller mandibular arc angle in the thalassaemic sample suggests a more superior than posterior growth direction of condyles compared with healthy individuals. The difference in symphyseal angle represents inherent differences in chin morphology between thalassaemic subjects and controls.

Characteristics of Palatal Rugae Patterns as a Potential Tool for Sex Discrimination in a Sample of Iranian Children.

STATEMENT OF THE PROBLEM: Palatal rugae have been considered equivalent to fingerprints, as they are unique to each individual. It has been shown that palatal rugae are associated with specific racial groups and are known to aid sex identification. Due to the lack of any published data on palatal rugae morphology on Iranian children, the present study was performed. PURPOSE: The present study aimed to investigate differences in the morphology of individual palatal in a sample of Iranian children. Additionally, it is intended to develop discriminant function to identify sex, based on rugae morphology. MATERIALS AND METHOD: A total of 120 pre-orthodontic casts were evaluated for different rugae patterns using the Thomas and Kotze classification. The casts were equally distributed between sexes with an age range of 6-12 years. Rugae length, shape, and associated morphology were recorded and the independent t-test and Chi-square test were used to compare the mean and relationship between the attributes. The discriminant function analysis was applied to the data in order to determine the applicability of palatal rugae patterns as an aid for sex identification. RESULTS: While the total rugae count showed an insignificant difference between the males and females, the rugae count on the right side of the palates showed a significant difference (p= 0.046). The primary rugae were most common in both sexes, followed by the secondary and fragmentary rugae. The most prevalent rugae shape between both sexes was the wavy rugae followed by the curve and straight shapes in males and the straight and curve shapes in females. A significant difference was observed in the number of the curve rugae between the sexes. Discriminant function analysis allowed sex differentiation with an accuracy of 60.8%. CONCLUSION: Palatal rugae shapes are unique to each individual and could be used as a potential tool for sex identification. Further research on a larger sample is required to fully confirm the application of this method (e.g. in forensic medicine) as a complementary technique for sex identification.

Ergonomic Assessment of Exposure to Musculoskeletal Disorders Risk Factors among Dentists of Shiraz, Iran.

STATEMENT OF THE PROBLEM: In dental profession, exposure to risk factors of musculoskeletal disorders raises the probability of musculoskeletal injuries in different parts of the body. PURPOSE: This study aimed to determine the prevalence of musculoskeletal disorders (MSDs), assess the risk of MSDs, and determine the risk factors of musculoskeletal injuries among dentists of Shiraz city. MATERIALS AND METHOD: In this cross-sectional study, 136 dentists of Shiraz city were randomly selected. The data were collected by Nordic musculoskeletal questionnaire (NMQ). Ergonomic assessment of exposure to MSDs risk factors was carried out by assessment of repetitive tasks (ART) technique. In order to assess dentists' exposure to MSDS risk factors, the method of ART (ART) was adopted. This method has been designed to assess the risk of those tasks that required repetitive motion of upper limb, especially hands and arms. The collected data were analyzed through SPSS software (version. 22). The study regarded p value of <0.05 as significance level. RESULTS: Mean age of the participants was 35.6±8.7 years. The 12-month prevalence of MSDs among dentists was 91.9%. The results suggested that risk of MSDs among dentists was high. The results of logistic regression analyses indicated that female gender (p< 0.001) and exercise for less than 3 hours per week (p= 0.001) played significant roles in occurrence of MSDs among the study population. Additionally, the results of ART assessment revealed that risk of MSDs in the right side of the subjects' bodies was higher. CONCLUSION: The findings showed that risk of MSDs and their prevalence in the study population was high with significant association. Based on the results of regression modeling, it seems necessary to pay proper attention to factors associated with MSDs to develop ergonomic solutions to reduce or eliminate musculoskeletal injuries.

Effect of different surface treatment on the shear bond strength of metal brackets to bleached and desensitized enamel.

INTRODUCTION: The aim of this study was to determine the effect of bleaching and desensitizing on shear bond strength (SBS) of metal brackets to enamel. METHODS: One hundred extracted human premolar were randomly assigned to 5 groups of 20. In the first group (control), no bleaching or desensitizing agent was used. Groups 2 to 5 were bleached with 37.5% hydrogen peroxide and desensitized with 6.0% potassium nitrate. Surface treatment comprised of etching for 15seconds in groups 1, 2 and 3, Er:yag laser irradiation and etching in group 4 and sandblasting and etching in group 5. Premolar brackets were bonded with Transbond XT and cured for 20seconds and the SBS was tested using a universal testing machine. Adhesive remnant index (ARI) score was used to record the mode of bond failure. RESULTS: No significant difference was found between the mean SBS (MPa) in groups 1(15.22), 4(14.02), and 5(12.62). SBS in group 4 was significantly higher than group 2 (8.15) (P<0.001). Also, SBS in groups 2 (P<0.001) and 3(11.74) (P=0.012) were significantly lower than group 1. An increased frequency of ARI score of 2 and 3 was observed in groups 1, 4 and 5. CONCLUSIONS: Bleaching plus desensitizing significantly decreased the SBS of orthodontic brackets. Delaying the bonding procedure for at least 2 weeks or alternative surface treatment methods such as combined laser and acid etching or combined sand blasting and acid etching can improve the SBS.

Impact of nanohydroxyapatite on enamel surface roughness and color change after orthodontic debonding.

BACKGROUND: The aim of this prospective in vitro study was to evaluate the effect of nanohydroxyapatite (nanoHAP) serum on the enamel surface roughness and tooth color stability after orthodontic debonding procedure. METHODS: The crowns of 30 premolars were embedded in acrylic blocks with a 4 mm × 5-mm-sized window on the middle third of buccal surfaces. Primary roughness values were evaluated by an atomic force microscope (AFM). After bracket debonding, and polishing procedures, the second roughness parameters were recorded. Specimens were then randomly assigned to two equal groups. NanoHAP serum and HAP toothpaste were applied for 10 days in the first and second groups, respectively. Then, after the third AFM, initial color parameters were measured. Following 1-week immersion in the coffee solution, second color assessment was performed. The fourth AFM was registered after 2 months of aging process. RESULTS: All roughness parameters were elevated following debonding procedure. There was no statistically significant reduction in roughness parameters after 10 days of nanoHAP serum or HAP toothpaste application. Both groups showed significant color change after immersion in the coffee solution. CONCLUSIONS: NanoHAP serum with the protocols used in this study could not restore enamel surfaces to their original condition.

Evaluating the Stability of Open Bite Treatments and Its Predictive Factors in the Retention Phase during Permanent Dentition.

STATEMENT OF THE PROBLEM: Orthodontists often find challenges in treating the anterior open bite and maintaining the results. PURPOSE: This retrospective study was aimed to evaluate the stability of corrected open bite in the retention phase during permanent dentition. MATERIALS AND METHOD: A total number of 37 patients, including 20 males and 17 females, with the mean age of 18±2.1 years at the beginning of the treatment were studied after correction of the anterior open bite. Overbites of the patients were measured from their lateral cephalograms before (T1), at the end (T2) and at least 3 years after the end of the treatment in the presence of their fixed retainers (T3).The mean overbite changes and the number of patients with open bite, due to treatment relapse, at T3 were calculated. The relationship between the pre-treatment factors and the treatment relapse was assessed at T1 and T2. Also the effects of treatment methods, extraction and adjunctive use of removable appliances on the post-treatment relapse were evaluated. RESULTS: The mean overbite change during the post-treatment period was -0.46±0.7 mm and six patients (16.2%) had relapse in the follow-up recall. Cephalometric Jaraback index showed statistically significant, but weak correlation with overbite changes after the treatment (p= 0.035; r= -0.353). No significant difference was found between the extraction and non-extraction groups (p= 0.117) the use and the type of the removable appliances (p= 0.801). CONCLUSION: Fixed retainers alone are insufficient for stabilizing the results of corrected open bite. The change of overbite in the retention phase could not be predicted from cephalometric measurements. Extraction and use of adjunctive removable appliance did not have any effect on the treatment relapse.

An Analytical Study on an Orthodontic Index: Index of Complexity, Outcome and Need (ICON).

STATEMENT OF THE PROBLEM: The validity of the Index of Complexity, Outcome and Need (ICON) which is an orthodontic index developed and introduced in 2000 should be studied in different ethnic groups. PURPOSE: The aim of this study was to perform an analysis on the ICON and to verify whether this index is valid for assessing both the need and complexity of orthodontic treatment in Iran. MATERIALS AND METHOD: Five orthodontists were asked to score pre-treatment diagnostic records of 100 patients with a uniform distribution of different types of malocclusions determined by Dental Health Component of the Index of Treatment Need. A calibrated examiner also assessed the need for orthodontic treatment and complexity of the cases based on the ICON index as well as the Index of Orthodontic Treatment Need (IOTN). 10 days later, 25% of the cases were re-scored by the panel of experts and the calibrated orthodontist. RESULTS: The weighted kappa revealed the inter-examiner reliability of the experts to be 0.63 and 0.51 for the need and complexity components, respectively. ROC curve was used to assess the validity of the index. A new cut-off point was adjusted at 35 in lieu of 43 as the suggested cut-off point. This cut-off point showed the highest level of sensitivity and specificity in our society for orthodontic treatment need (0.77 and 0.78, respectively), but it failed to define definite ranges for the complexity of treatment. CONCLUSION: ICON is a valid index in assessing the need for treatment in Iran when the cut-off point is adjusted to 35. As for complexity of treatment, the index is not validated for our society. It seems that ICON is a well-suited substitute for the IOTN index.

Oral health in Iran.

The health network in the Islamic Republic (I.R.) of Iran is an integrated public health system with a four-level Dental Health Care System integrated into it by 1997. The first level is one of primary prevention at 'health houses', at the next, oral hygienists and dentists in health centres perform basic oral health care services such as fillings, scaling and extractions. At the third level, dentists manage and treat oral diseases in 'urban health centres, while the last level is for advanced treatment by specialists in university health centres in the big cities. There are about 13,000 dentists nationwide (1 dentist: 5,500 population) and nearly 1,200 specialists in universities and private practices. Data from surveys in the past two decades, show a marked decline in dental caries from DMFT of 4 to 1.5 in 12-year-old children. However, the general level of oral health is still not satisfactory, particularly among children. The percentage of caries-free children (deciduous and permanent teeth) among 6- and 9-year-olds is 13.8 and 11.5 respectively and more than 50% of 12-year-old children have caries experience, with the decayed component being the greatest component. The main objective would be to cope with the dental caries problem in primary teeth and, in this respect, the national oral health plan should be aimed at developing oral hygiene skills, reducing the frequency of sugar intake, instituting water fluoridation, improving access to fissure sealants and regular dental care, and finally promoting dental health services toward minimum treatment intervention and effective preventive strategies and health promotion.

The effects of forehead and neck position on esthetics of class I, II and III profiles.

INTRODUCTION: All parts of the face, other than jaw relationships, should be considered in orthodontic treatment planning. The role of forehead and neck in facial esthetics is well known; however, the majority of conventional facial analysis methods have not considered them. Neck and forehead may confer mutual effects on equilibrium and on esthetics of other facial components, and may change the overall convexity/concavity view of the profile. Therefore, the aim of this study was to assess the effect of anteroposterior position of the forehead and neck on the esthetics of skeletal class I, II and III jaw relationships using profile silhouettes. METHODS: Class II and III jaw relationships were constructed on the silhouette of a class I normal profile by altering the mandibular position. Retruded, normal and protruded positions were also applied for the forehead and neck. Three hundred Iranian laypeople (150 men, 150 women) scored the esthetics of profile silhouettes from 1 to 7. Half of the participants were told to consider the profiles as a man, and the other half were told to consider them as a woman. Data were analyzed using non-parametric methods. RESULTS: Class I jaw relation was found to be the most beautiful profile followed by class II and III respectively. Esthetics of different positions of the neck and forehead were significantly different (P < 0.05). In subjects with a normal neck and forehead position, and those with a retruded neck, the best esthetic relationship was class I, and the worst was class III. For protruded foreheads, the best jaw relationship was class II for females and class I for males, and the worst was class III for both. In a retruded forehead position, the most preferred jaw relationship was class I, and the worst was class II. For profiles with a protruded neck, the best esthetics was found to be in class III jaw relationship, and the worst was in class II. There was a small difference in scoring for male and female profiles (P < 0.05); there were also small differences in scoring trends of men and women (P < 0.05). CONCLUSION: This study showed that the anteroposterior position of the forehead and neck affects the esthetics of jaw relationships in profile view. In laypeople's opinions, in a normal profile, the overall appearance is more important compared to the independent position of the neck and forehead; however, having jaw abnormalities, the neck plays an important independent role. The preferred jaw relation for profiles with each forehead or neck position was introduced.

Comparison of the shear bond strength of orthodontic brackets in bonding and rebonding: preparation with laser versus conventional acid etch technique.

OBJECTIVE: The purpose of this study was to compare the bond strength of orthodontic brackets using laser versus acid etching. BACKGROUND DATA: Debonding of brackets is a common problem in orthodontic treatments. MATERIALS AND METHODS: Eighty extracted premolar teeth were divided into two groups. The enamel of the teeth in group A and B were etched using CO2 laser and phosphoric acid, respectively. The brackets were bonded to the teeth using Transbond XT and then debonded from the teeth by Instron machine. The remaining composite on the tooth surface was removed by a tungsten carbide polishing bur. Both groups were divided into two subgroups (A1, A2 and B1, B2). The teeth were prepared again with laser in A1, B1 subgroups and with acid in A2, B2 subgroups. At each stage, the shear bond strength and residual adhesive index were measured. One way ANOVA and χ(2) tests were used to analyze data. RESULTS: The mean shear bond strength was significantly lower in group A and higher in group B compared with all other groups (p < 0.05). Most of the bond failures were degree 0 and 1 in groups A, A1, and B1, and degree 2 and 3 in groups B, A2, and B2. CONCLUSIONS: Primary preparation with acid has a higher bond strength value than does CO2 laser. Less adhesive residue remained on enamel after tooth preparation with laser following debonding. Secondary preparation of the enamel using laser has higher bond strength value than does primary preparation with laser, which can rationalize use of laser in rebonding of brackets.

Comparison of tooth size discrepancies among different malocclusion groups.

This retrospective investigation was designed to compare tooth size discrepancies among subjects with different skeletal malocclusions in an orthodontic population. The study employed the pre-treatment models of 200 patients (100 males, 100 females, aged from 14 to 20 years) selected from the records of the Orthodontic Department, Shiraz Dental School. The subjects were from four malocclusion groups, Class I, Class II division 1, Class II division 2, and Class III, with the corresponding skeletal characteristics. Each group comprised 50 healthy individuals (25 males, 25 females). The mesio-distal dimensions of teeth were measured using digital electronic callipers (accurate to 0.01 mm) and the Bolton indices were determined. The data were statistically analysed using analysis of variance and Duncan's multiple range test, with the level of significance set at P < 0.05. The results revealed that the mean anterior ratio (79.01) for the whole sample was statistically significantly different from Bolton's (77.2) but no significant difference was found for the overall ratio. The posterior and overall ratios of the Class III malocclusion group were statistically greater than the other malocclusion groups (P < 0.05). The mean anterior ratio of the Class III group was greater than that of the Class II group. However, there was no difference when compared with the Class I malocclusion group. For the two types of Class II malocclusion, no significant ratio differences were observed.

Dental education and dentistry system in Iran.

Before 1979, there were only 5 undergraduate dental schools in Iran with a total admission of 200 students per year, and only 2,000 dentists and about 50 specialists practicing in the country. Currently, there are 18 dental schools with a total admission of 750 undergraduate students, 5 postgraduate programs in 10 disciplines with a total of 100 students, more than 11,000 dentists (1 dentist per 5,500 population) and nearly 1,000 specialists in the country. Two new schools have recently begun offering specialty training courses in 2 disciplines. The length of the dentistry curriculum is 6 years. Students take general and basic science courses during the first 2 years, then continue on the predental and dental courses for the remaining 4 years. The curriculum has been revised over the past 20 years to establish intership and specialty programs and introduce courses reflecting current trends in the dental profession. Dental services in Iran are provided by both public and private sectors. Oral health care was integrated into the Public Health Care network by 1997, and 4 levels of a Dental Health Care Delivery System were established. The first level is concerned with primary prevention at 'health houses', where auxiliary health workers called 'behvarzes' provide periodic examinations, referrals, and oral health education. At the next level, oral hygienists and dentists in 'health centers' perform basic oral health care services such as fillings, scaling, and extraction. At the third level, dentists manage and treat oral diseases in 'urban health centers', while the last level is for advanced treatment by specialists in university health centers in the cities.

Effect of misoprostol, a prostaglandin E1 analog, on orthodontic tooth movement in rats.

The purpose of this study was to investigate the effects of oral administration of misoprostol, a prostaglandin E1 analog, on orthodontic tooth movement and root resorption in rats. Sixty-four male Sprague-Dawley rats that initially weighed 250 +/- 20 g were used in this study. The animals were randomly assigned to 1 of 6 experimental and 2 control (nonappliance and appliance) groups. The experimental groups received 2.5, 5.0, 10.0, 25.0, 50.0, and 100.0 microg/kg misoprostol by gastric lavage every 24 hours for 2 weeks. A fixed orthodontic appliance consisting of a nickel-titanium closed-coil spring, 5.0 mm long was ligated between the maxillary right incisor and the maxillary right first molar. The initial activating force was 60 g. For analysis of root resorption, 99 maxillary right and left first molars from 61 animals were chosen. Serial histologic sections of the mesial root of the maxillary first molars were made, and histologic analysis of root resorption on the mesial and distal surfaces was performed. The results showed that oral misoprostol did increase the amount of orthodontic tooth movement in all the experimental groups compared with the appliance control group. This increase was statistically significant in doses of 10.0, 25.0, 50.0, and 100.0 microg/kg (P <.001). However, there were no statistically significant differences among these 4 different doses. There were no statistically significant differences in the amount of root resorption among the groups. However, a trend toward more root resorption was registered. On the basis of these findings, oral misoprostol can be used to enhance orthodontic tooth movement with minimal root resorption.