Iranian Journal of Orthodontics
Volume:14 Issue: 2, Sep 2019

Context: 

Temporary anchorage devices (TADs) have been introduced to orthodontic treatment for enhancing anchorage control. It is claimed that they are not disposable and can be used several times after sterilization process. However, the question is whether this repeated sterilization has any effect on the properties of these devices. This study was done to review the available articles that had addressed various aspects of this issue.

Evidence Acquisition: 

The authors searched several electronic data bases including PubMed, Google Scholar, Scopus and Embase with several key words related to orthodontic temporary anchorage devices and sterilization. The relevant articles were reviewed and categorized in the following subjects: mechanical properties, primary stability and clinical success, and histologic and microscopic characteristics.

 Sterilizing the temporary anchorage devices seems not to affect the mechanical properties of these devices.

 In terms of primary stability, and clinical success, very few studies are available. Histologic and microscopic evaluations showed some alteration in the surface characteristics of TADs including some mineral precipitation.

 The objective of this clinical study was to assess the predicted treatment outcome and actual treatment outcome and compare the models of both the groups so as to evaluate the efficacy of tooth movement with clear aligner.

 The sample size included 10 cases with mild anterior crowding treated with aligner therapy. The predicted software models were superimposed on the Clinical STL models at various stages by using MeshLab software (Developed at the Visual Computing Lab at ISTI-CNR with the support of the 3D-co-form project).The predicted software models showing orthodontic tooth movement was compared with the actual movement achieved clinically.

 The results of this study have shown that when a comparison was made on the basis of irregularity scores in both the groups, it was seen that the irregularity score was more in Clinical STL group at each stage such as 2.55 at T4, 1.65 at T6 and 1.0 at T8 whereas 2.0 at T4. 0.90 at T6 and 0.25 at T8 in the Software model group. Also, on comparing mean accuracy these three stages, the analysis of data showed the mean accuracy at T4 is 62.5%, mean accuracy at T6 is 68.8% and the mean accuracy at T8 is 78.1%.

 The predicted software models do not accurately reflect the patient’s tooth position .There is an overestimation by predicted software as compared to the actual achieved tooth position. There is a need of overcorrection to be built in the treatment planning stage itself and execution of the anticipated end result.

 The aim of this study was to evaluate and compare antibacterial and antifungal effects of different concentrations of Zataria multiflora extract mouthrinse.

 In this lab trial study, 128 elastomeric ligatures were divided into 2 groups of 64. Before disinfection eight ligatures of each group were randomly selected to evaluate the microbial load. The remaining ligatures in each group (n = 58) were divided into 7 subgroups of 8. All samples in group 1 (G1) contaminated with Streptococcus mutans (S. mutans) and in group 2 (G2) contaminated with Candida albicans (C. albicans). Then, Zataria multiflora extract in 1%, 0.1%, 0.01%, 0.001%, 0.0001% concentrations as decontamination agent were used in 5 subgroups of each group. Positive control consisted of penicillin in G1 and nystatin in G2. For the negative control in both groups phosphate buffered saline was used. The average number of adhered viable bacterial cell after performing the disinfection protocols were calculated and compared. The collected data was statistically analyzed by Kruskal-wallis, Wilcoxon and Mann-Whitney test using SPSS software version 18 at a significant level of 0.05.

 Results showed that penicillin, nystatin, Zataria multiflora extract in 1% and 0.1% concentrations completely eliminated C. albicans and S. mutans on elastomeric ligatures. Statistically significant differences were found between the number of adhered S. mutans and C. albicans before and after performing the all five concentrations of disinfection solutions (P = 0.01). Also higher concentrations of Zataria multiflora showed more antibacterial effectse in both groups.

 Zataria multiflora extract mouthrinse showed antibacterial and antifungal characteristics and could be useful for patients under orthodontic treatment.

 A longitudinal analysis of arch dimension changes in late primary and early mixed dentition periods in children was designed and investigated the effect of eruption of precedence on the arch size in the samples under study.

 This longitudinal study was carried out on 32 children aged 5.5 - 6.5 years who had no erupted permanent dentition. Impression was taken and the arch perimeter, depth and width as well as tooth size were measured by a digital calliper and a brass wire on casts. After eruption of the first permanent tooth, the second impression was taken; the above-mentioned parameters were measured on the second casts. Data were analysed by ANOVA test.

 Four pattern of eruption of precedence were as follows: maxillary 1st molar, mandibular incisors, Mandibular 1st molars and simultaneous eruption of maxillary and mandibular 1st molars. With eruption of mandibular central incisors, inter canine width and overjet increased by 0.81 and 0.27 mm, respectively. The mandibular arch perimeter increased by 2.25 mm with simultaneous eruption of maxillary and mandibular permanent first molars. The maxillary arch perimeter increased by 1.25 mm and 1.50 mm with eruption of maxillary first molars and simultaneous eruption of maxillary permanent first molars, respectively.

 Eruption precedence had a significant effect on changing mandibular inter canine width, maxillary arch perimeter, mandibular arch perimeter and overjet.

 Reverse chin cap appliance consists of a removable plate that is attached to a vertical projection hooks via elastics. This appliance is preferred for treatment of combination of maxillary retrognathia and mandibular prognathism malocclusion.

 The aim of this study was to assess the effects of the reverse chin cap appliance to hard and soft tissues.

 In this retrospective study 16 consecutive Class III patients (6 females, 10 males) with mean age of 9.3 ± 2 (Mean ± SD) years, who were treated with reverse chin cap appliance were selected. Pre- and post- treatment lateral cephalograms were analyzed. The overall changes were compared with growth changes in 20 control samples of Class I (10 females and 10 males) with Cl I occlusion and average age of 9.9 ± 3 (Mean ± SD) years. Independent Samples t-test was used to compare mean differences between the two of them. Differences were considered significant at P < 0.05.

 At the end of treatment in treatment group, SNB angle decreased 3.7º and ANB angle increased by 2.9º both (P = 0.005). Mandibular length decreased 0.18 mm (P = 0.009). Lower incisors retroclined 10.03º (P = 0.001). Linear distance of the upper lip and lower lip to the E-line significantly decreased 2.3 mm (P = 0.04) 1.1 mm (P = 0.05) respectively. Nasolabial angle decreased significantly 4.1º (P = 0.005).

 Reverse chin cap appliance therapy has a skeletal and dental effects. This treatment is effective in correction of the Cl III malocclusion by retroclination of the lower incisors, and retardation of mandibular growth. At the end of treatment, soft tissue profile

 This study aimed to evaluate gender dimorphism in anterior malar projections using clinical photographs and lateral cephalograms.

 Thirty subjects aged 18 - 25 years were taken for the study. Based on the gender they were divided into two groups group A (15 subjects) male and group B (15 subjects) female. On the profile photographs positive and negative vectors were labelled. Sella-nasion-orbitale (SNO) angle was delineated with the aid of NemocephTM software. The data was then statistically analysed.

 Skeletal differences between the positive and negative vector groups on basis of SNO angles were statistically significant (P < 0.001). The angulation value obtained for SNO was smaller in the negative vector when compared to the positive vector on an average by 5.9°. No difference in values between males and females was seen.

 The projections of anterior malar can be effectively categorized by mere visually assessing the vector relationship (by photographs). This method can be used to diagnose maxillary hypoplasia and can help plan different treatment alternatives.
 

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.

 Due to significant effect of joint orthodontic and surgical treatment planning on the patients’ facial appearances, precise prediction of surgical outcomes is of great importance.

 The aim of this study was to determine the maxillary and mandibular centers of rotation and its distance to center of condyle (CC) in patients who underwent maxillary impaction surgery concomitant with mandibular advancement or setback surgery and also to determine the correlation between maxillary center of rotation (MxCR) with that of mandible (MnCR) and also the direction of rotation in distal and proximal segments of the mandible.

 Preoperative and postoperative lateral cephalograms of 24 adult non-syndromic patients were studied. Using cephalometric tracings MxCR was located as the intersection of ANS-PNS (preoperative) and ANS’-PNS’ (postoperative) lines. MnCR was located using Reuleaux method, where perpendicular bisectors of B-B’ and Go-Go’ lines meet. Using statistical analysis of correlation and comparison, all the points’ coordinates and centers of rotation were compared.

 The average distance of MnCR to CC was 10.45 cm and the average distance of MxCR to CC was 8.39 cm. MxCR and MnCR had positive correlation in horizontal plane and they had negative correlation in vertical plane but the correlation was insignificant (P > 0.05). In addition, there seemed to be no specific pattern in the direction of mandibular proximal and distal segments’ rotations.

 The results showed that: (1) The center of rotation calculated for mandible after bimaxillary surgery was not located within the condylar area. But generally whenever MxCR was closer to ANS, MnCR was located more anteriorly. (2) In patients with decreased distance between MxCR and SN line, MnCR would be located more superiorly. Also, whenever MxCR had greater distance from condyle, the MnCR to condyle distance was greater too. (3) The direction of rotation in proximal and distal segments of mandible had no specific pattern.