The Effect of Immediate Versus Delayed Addition of the Nasal Stent to the Nasoalveolar Molding Plate on Nostrils Shape and Cleft Width in Infants With Unilateral Cleft Lip and Palate.

OBJECTIVE: The main aim of this study was to evaluate the effect of immediate versus delayed addition of the nasal stent to the nasoalveolar molding plate on the nose shape and alveolar cleft area in unilateral cleft lip and palate infants. METHOD: Twenty nonsyndromic newborn infants with unilateral cleft lip and palate were scanned 3 dimensionally using Proface software. In the experimental group, the nasal stent was added on the day the molding plate arrived, and in the control group when the alveolar gap reached 5 mm. Two months after adding nasal stents in each group patients' faces were scanned again and some parameters were measured. In addition, immediately after treatment, 1 month later and at the end of investigation, impressions were taken, and stone casts were scanned by cone-beam computed tomography and the alveolar gap was measured. Fisher exact test, paired t test, and ANOVA were used for data analyses. P < 0.05 was considered as significant. RESULTS: In this study, changes in the parameters showed significant differences between the case and controls for the columellar angle, nostril width on the cleft side, nostril height on the cleft side, soft tissue cleft width, and nasal surface area. However, the nostril's width and height in the noncleft side, intercommissural distance, nasal surface area on the noncleft side, nostril area between the cleft and noncleft side after treatment, and the alveolar gap did not show significant differences between the groups (P > 0.05). CONCLUSION: Early use of nasal stents showed more desirable results in decreasing the width of the nostrils and increasing its height and correcting the angle of the columella without any adverse effects on the nostrils after treatment.

Nickel Ion Release from Three Types of Nickel-titanium-based Orthodontic Archwires in the As-received State and After Oral Simulation.

Background and aims. This study aimed to investigate release of nickel ion from three types of nickel-titanium-based wires in the as-received state and after immersion in a simulated oral environment. Materials and methods. Forty specimens from each of the single-strand NiTi (Rematitan "Lite"), multi-strand NiTi (SPEED Supercable) and Copper NiTi (Damon Copper NiTi) were selected. Twenty specimens from each type were used in the as-received state and the others were kept in deflected state at 37ºC for 2 months followed by autoclave sterilization. The as-received and recycled wire specimens were immersed in glass bottles containing 1.8 mL of artificial saliva for 28 days and the amount of nickel ion released into the electrolyte was determined using atomic absorption spectrophotometry. Results. The single-strand NiTi released the highest quantity of nickel ion in the as-received state and the multi-strand NiTi showed the highest ion release after oral simulation. The quantity of nickelion released from Damon Copper NiTi was the lowest in both conditions. Oral simulation followed by sterilization did not have a significant influence on nickel ion release from multi-strand NiTi and Damon Copper NiTi wires, but single-strand NiTi released statistically lower quantities of nickel ion after oral simulation. Conclusion. The multi-strand nature of Supercable did not enhance the potential of corrosion after immersion in the simulated oral environment. In vitro use of nickel-titanium-based archwires followed by sterilization did not significantly increase the amount of nickel ion released from these wires.

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.

In-vitro evaluation of an experimental method for bonding of orthodontic brackets with self-adhesive resin cements.

BACKGROUND: Self-adhesive resin cements do not require the surface treatment of teeth and are said to release fluoride, which makes them suitable candidates for bonding of orthodontic brackets. The objectives of this study was to investigate the shear bond strength (SBS) of self-adhesive resin cements on etched on non-etched surfaces in vitro and to assess their fluoride release features. MATERIALS AND METHODS: Four fluoride-releasing dual-cure self-adhesive resin cements were investigated. For SBS experiment, 135 freshly extracted human maxillary premolars were used and divided into nine groups of 15 teeth. In the control group, brackets were cemented by Transbond XT (3M Unitek, USA), in four groups self-adhesive resin cements were used without acid-etching and in four groups self-adhesive cements were applied on acid-etched surfaces and the brackets were then deboned in shear with a testing machine. Adhesive remnant index (ARI) scores were also calculated. For fluoride release investigation, 6 discs were prepared for each self-adhesive cement. Transbond XT and Fuji Ortho LC (GC, Japan) served as negative and positive control groups, respectively. The fluoride release of each disc into 5 ml of deionized water was measured at days 1, 2, 3, 7, 14, 28, and 56 using a fluoride ion-selective electrode connected to an ion analyzer. To prevent cumulative measurements, the storage solutions were changed daily. RESULTS: The SBS of brackets cemented with Transbond XT were significantly higher compared to self-adhesives applied on non-etched surfaces (P<0.001). However, when the self-adhesive resin cements were used with enamel etching, no significant differences was found in the SBS compared to Transbond XT, except for Breeze. The comparisons of the ARI scores indicated that bracket failure modes were significantly different between the etched and non-etched groups. All self-adhesive cements released clinically sufficient amounts of fluoride for an extended period of time. CONCLUSION: For the tested cements, the strongest bonds were obtained by enamel acid-etching prior to bracket bonding. All the self-adhesive resin cements had significant long-term fluoride release and could be recommended as suitable fluoride-releasing orthodontic bonding materials.

Evaluation of tooth size in patients with congenitally-missing teeth.

BACKGROUND AND AIMS: Hypodontia is a common developmental abnormality of dentition. This study aimed to determine tooth width in patients affected with mild hypodontia and compare the results with a control group without tooth agenesis. MATERIALS AND METHODS: The orthodontic records of 25 patients with congenital missing of one or two teeth (hypodontia group), and 25 subjects with full dentition (control group) were selected. The greatest mesiodistal width of each tooth was measured on the study models by a digital caliper. Tooth width measurements were compared between the groups using a student t-test at p < 0.05 of significance. RESULTS: Patients with hypodontia showed narrower teeth than the control subjects. The differences in tooth size between the two groups were statistically significant for the first and second premolars and first molar in the maxillary right and for the second premolar in the maxillary left quadrants (p < 0.05). In the lower arch, the first and second premolars and also first molar in both sides of hypodontia patients demonstrated significant reduction in tooth size compared to the control group (p < 0.05). CONCLUSION: These findings suggest that patients with mild hypodontia have narrower teeth than normal subjects especially in posterior segments, which may have clinical implications during the orthodontic treatment process.

The effect of fluoride exposure on the load-deflection properties of superelastic nickel-titanium-based orthodontic archwires.

BACKGROUND: It has been demonstrated that fluoride prophylactic agents may cause hydrogen absorption in NiTi wires and degrade their mechanical properties. AIMS: To investigate the effect of a fluoride mouthwash on load-deflection characteristics of three types of nickel-titanium-based orthodontic archwires. METHODS: Twenty maxillary 0.016 inch round specimens from each of the single-strand NiTi (Rematitan 'Lite'), multi-strand NiTi (SPEED Supercable) and Copper NiTi (Damon Copper NiTi) wires were selected. The specimens were kept in either 0.2% NaF or artificial saliva solutions at 37 degrees C for 24 hours (N = 10). The wire load-deflection properties were measured by a Zwick testing machine, using a three-point bending test. An un-paired student's t-test, a one-way ANOVA and a Tukey post-hoc test were used to assess statistical significance. RESULTS: Immersion in NaF solution affected the load-deflection properties of NiTi wires. The unloading forces at 0.5 and 1.0 mm deflections were significantly lower in fluoride-treated specimens compared with the control groups (p < 0.05). Unloading forces at 1.5, 2.0 and 2.5 mm deflections were not statistically different between fluoride- and saliva-treated specimens (p > 0.05). CONCLUSIONS: The results suggested that subjecting NiTi wires to fluoride agents decreased associated unloading forces, especially at lower deflections, and may result in delayed tooth alignment.

Effects of a simulated oral environment and sterilization on load-deflection properties of superelastic nickel titanium-based orthodontic wires.

UNLABELLED: The aim of this study was to evaluate the load-deflection characteristics of three types of nickel-titanium wires and investigate the effects of recycling on superelastic properties of them. MATERIALS AND METHODS: Thirty specimens for any of the single-strand Ni-Ti (Rematitan "Lite'), multi-strand Ni-Ti (SPEED Supercable) and Copper Ni-Ti (Damon Copper Ni-Ti) were tested. Ten specimens of each wire were subjected to three point bending test in the as-received condition (T0). The remaining wires were kept in a simulated oral environment for 2 months. Then, half of these specimens were tested for their load-deflection properties (T1), while the others were autoclave sterilized before testing (T2). Statistical analysis was performed by one-way ANOVA and Tukey test. RESULTS: Rematitan "Lite"showed significantly greater force than Damon Copper Ni- Ti and Damon Copper Ni-Ti, demonstrated significantly greater force than Supercable (p < 0.05). The effect of recycling on bending properties of nickel-titanium wires was significant (p < 0.05). T1 wires were generally associated with significantly lower forces than T0 specimens in deflections less than 2.0 mm, while load-deflection characteristics of T2 wires were not considerably different from those of T0 specimens. CONCLUSIONS: Supercable is useful when very light force is needed during orthodontic treatment, for example in severe crowding cases and traumatized teeth. Damon Copper Ni-Ti may be suitable for routine orthodontic treatment in adolescent and adult patients. It is suggested that clinicians who want to recycle nickel-titanium wires use autoclave sterilization.

Comparison between the external gonial angle in panoramic radiographs and lateral cephalograms of adult patients with Class I malocclusion.

The external gonial angle is an important angle of the craniofacial complex. It is significant for the diagnosis of craniofacial disorders. Lateral cephalogram and orthopantomograms can be used to determine this angle. In this study, we compared the external gonial angle determined from the two mentioned radiographs in Class I patients. We collected the radiographs of 70 patients with Angle's Class I (22 men and 48 women). The patients' age ranged from 15-30 years with a mean age of 18.24 years. The data gained were statistically evaluated by t-test. The following results were obtained. The mean value of the gonial angle in the lateral cephalogram was 125.00 degrees (men, 124.9 degrees and women, 125.04 degrees ) and in the orthopantomogram was 124.17 degrees (men 123.68 degrees , women 124.39 degrees ). The difference between these rates was 0.83 degrees (men 1.22 degrees , women 0.64 degrees ) and not significant (P = 0.406). Based on the obtained results, we can conclude that panoramic radiography can be used to determine the gonial angle as accurately as a lateral cephalogram. In addition, we can determine the right and left gonial angles of a patient in the orthopantomogram without interferences due to superimposed images of anatomical structures in a lateral cephalogram. For determination of the gonial angle, an orthopantomogram may be a better choice than a lateral cephalogram.

Effect of sodium fluoride mouth rinse on elastic properties of elastomeric chains.

OBJECTIVE: This study evaluated Sodium Fluoride mouth rinse effects on elastic properties of different elastomeric chains. STUDY DESIGN: In this in vitro experiment, two orthodontic chains were tested. In the first group, they were stored in artificial saliva for the entire duration, and in the second group they were immersed daily in 0.05% NaF mouth rinse for 1 minute, artificial saliva-NaF mixture for 30 minutes, and then in artificial saliva for the rest of the day. Specimens were tested at baseline, 1 hour 24 hours, 1, 2 and 3 weeks and then the displacement of specimens to obtain 150 g and 300 g, also the applied force after stretching them to 100% of their original length were evaluated. RESULTS: In contrast to force degradation, chains of both companies required more displacement to achieve both forces in the saliva-NaF mixture than saliva itself however the difference was only significant for the 300g force (P = 0.020). American Orthodontics chains required more displacement than Dentaurum chains to obtain both forces, also they had more load relaxation (P < 0.001). CONCLUSIONS: Daily use of NaF mouth rinse does not affect force degradation and the displacement of both chains to achieve conventional orthodontic forces, but for higher force levels the displacement increase is statistically significant.