Iranian Journal of Orthodontics
Volume:11 Issue: 2, Sep 2016

Context: One of the most important aims in orthodontic treatment is to apply a light continuous force to achieve maximum effective tooth movement with minimal side effects (optimal tooth movement). It is obvious that elastomeric chains are the most popular method of space closure, but they undergo force decay during time. Force decay behavior of elastomeric chains is influenced by various factors. It is crucial for every practitioner to know about these products and factors affecting them.
Evidence Acquisition: So we searched English articles published in Pubmed between 2005 - 2016 with keyword “orthodontics, elastomeric chain”.
25 articles were selected for comprehensive reading according to the inclusion criteria. Some factors such as aging process, production technique, pre-stretching effect, design and type of chains, in-vivo effects and microbial contamination were discussed.
By reviewing these articles, we know more about force decay pattern of elastomeric chains. Most of articles said the same force decay pattern for these elastomeric products. We know more about environmental conditions affect their features. This can help practitioners to use chains , in a better way.

Interclinoid ligament calcification and dimensional changes in Sella Turcica seen on cephalometric radiographs are associated with some bone abnormalities as well as normal variations. Merging of anterior and posterior clinoid processes, known as Sella Turcica bridging or roofing and other changes in this area may occur as a part of large skeletal growth changes in body and may have association with craniofacial skeletal patterns development.
The aim of the present study was to compare Sella Turcica bridging and dimensions of patients with various skeletal patterns to investigate whether there is a correlation between Sella Turcica region changes with skeletal patterns or not, and on the other hand, to know if these changes could be used as predictive indices for growing patients skeletal patterns.
A total of 108 cephalometric radiographs (36 Class I, 36 Class II, and 36 Class III) were randomly selected for evaluation. Sella Turcica was traced on acetate paper and scanned to produce digital images. The dimensions of Sella Turcica were measured with computer software using the Silverman, Kisling, and Axelsson method. To determine bridging, Leonardi’s method was employed. To determine the association of Sella Turcica bridging and dimensions with different malocclusions, chi-squared test and one-way ANOVA were used.
The means of Sella Turcica lengths in three groups were significantly different (P = 0.01). Mean depth and diameter, however, were not significantly different between malocclusions. In addition, bridging was not significantly different among three malocclusions evaluated.
According to the results, mean length of Sella Turcica, rather than depth and diameter, was significantly associated with the type of malocclusion. Sella Turcica cavity length is larger in Cl III patients in comparison with Cl I ones and may have predictive value in some instances.

Assure Universal Bonding Resin is capable of providing a strong bond between orthodontic attachments and amalgam surfaces.
This study sought to assess the shear bond strength of orthodontic attachments to amalgam surfaces using Assure Universal Bonding Resin after different surface treatments.
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.
Significant differences were noted in shear bond strength of attachments following the application of Assure among different surface treatment modalities (P 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.

Increase in the number of adult patients seeking orthodontic treatment for aesthetics, demand for a more aesthetic orthodontic appliance has become inevitable.
This prospective study was undertaken to evaluate torque expression of 0.019” × 0.025” fiber composite wire and 0.019” × 0.025” NiTi wire in a similar prescription bracket systems (MBT, 0.022” slot) using CBCT.
Twenty arches each (ten maxillary and ten mandibular), of 15 - 25 year old patients, were bonded with metal brackets and ceramic brackets having MBT prescription and 0.022”slot. Two CBCT images were recorded at T0 and Tx. T0 point represented the stage of transition from a 0.017” × 0.025” NiTi wire to a 0.019” × 0.025” fiber composite or NiTi archwire. The Tx time point represented the end of treatment phase using 0.019” × 0.025” dimension wire, i.e. after 3 months of T0 scan.
The mean angulation change from T0 to Tx in fiber composite wire group and NiTi wire group was tested using Wilcoxon signed rank test and showed that the difference was statistically non-significant (P > 0.05).
It was concluded that fiber reinforced composite wires were comparable to NiTi wires in their ability to deliver consistent forces and bring about comparable torque in individual teeth.

Different indices have been used to determine orthodontic treatment needs such as the Dental Aesthetic Index (DAI) and the index of orthodontic treatment needs (IOTN).
The present study was carried on to compare the dental aesthetic index (DAI) and the IOTN’s dental health component (DHC) in assessment of orthodontic treatment needs of 11 - 14 year old schoolchildren in Qazvin.
In a cross-sectional descriptive study, 250 of 11 - 14 year old schoolchildren from two school districts of Qazvin were selected by a two-stage stratified cluster sampling method and their AC scores were determined according to the orthodontist and child’s own idea. Also the subjects’ DHC and DAI scores were determined according to the existing standards. The patients’ demographic data were recorded by means of a questionnaire and correlations between AC’s as determined by the subject and by the orthodontist, as well as scores of the DHC and the DAI, were analyzed using Spearman correlation ratio.
The mean of AC score as determined by the subject was 2.556, while the scores by the orthodontist were 4.308; while DHC score was 2.60 and DAI score was 26.86. The coefficient of correlation between students and specialist AC, students AC and DAI, specialist AC and DHC, specialist AC and the DAI,DHC and the DAI, students AC and DHC was respectively 0.269, 0.262, 0.549, 0.506,0.794(In all cases P Existence of a positive and significant relationship between the AC, the DHC and the DAI indicates their potential for determining the need for orthodontic treatment. The highest need for orthodontic treatment was determined by the AC of the specialist and the lowest need by that of the patient. Only gender of the student had a significant effect on the values of the DHC and the DAI as determined by the specialist.

During mixed dentition period, one can make accurate estimation of future dental development and can assess whether there will be enough space in the dental arch. In orthodontics treatment planning, it is vital to predict space required for unerupted canine and premolars in the arch.
The main goal of this study is to compare different teeth combinations in predicting needed space for unerupted canine and premolars on Bayesian approach and introduce the most reliable one.
Patients and The sample for this study consists of 47 dental casts (19 males, 28 females) with complete erupted dental arches. The meisodistal width of all teeth was measured using a dental caliper. We consider different combinations of teeth size and compare them to find the best predictor. In order to do that, quantile regression and Bayesian approach are applied using “R software”.
Combination of first maxillary molars with sum of central and lateral mandibular incisors has the smallest standard deviation. This is true for male and female samples. The regression formula based on this teeth combination has been introduced.
In our sample, combination of Mandibular incisors and maxillary first molar is found to be better than the other predictors for female and female model in both arches.

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.
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.
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%).
Ovoid is the most common dental arch form in Iranian population.

The objective of this study was to report the correction of a maxillary transverse discrepancy in an adult patient using Le Fort I osteotomy procedure associated with a bone-borne maxillary distractor device. Both the indications, advantages of the procedure and the use protocol were highlighted.
The results showed that the bone-borne distractor promoted the correction of maxillary transverse discrepancy with minimal side effects on the maxillary posterior teeth.
The bone-borne maxillary distractor device is a good alternative for correcting the maxillary transverse discrepancy in patients undergoing Le Fort I surgery, especially in cases presenting either periodontal disease or gingival recession of maxillary posterior teeth.