Effect of temperature on nickel-titanium closed-coil springs
Espinar-Escalona E, Llamas-Carreras JM, Barrera-Mora JM, Abalos-Lasbrucci C, Gil-Mur FJ. Effect of temperature on the orthodontic clinical applications of niti closed-coil springs. Med Oral Patol Oral Cir Bucal 2013;18:e721-4
Nickel-titanium coil springs are used in orthodontic treatment because they produce light and continuous forces during tooth movement. Nickel-titanium coils are exposed to temperature changes produced by the hot and cold foods and beverages ingested by the patient. The aim of this study was to investigate the changes in the superelastic behavior and corrosion potential of 50 nickel-titanium closed-coil springs exposed to temperature changes similar to those in patients’ mouths. This was an in-vitro experiment to determine the effect of temperature variations on the level of orthodontic forces produced by the nickel-titanium coil springs. Tensile force was administered by the MTS-Adamel (100-N load cell) as the GAC Orthospain closed coils were immersed in a temperature-controlled water bath of artificial saliva. After initial loading and unloading at 37°C, the temperature was either increased to 55°C or lowered to 15°C, and the spring was then unloaded further. The corrosion potential was evaluated according to the ISO standard 10993-15:2000. The results show that the force from the spring increased by 30% with an increase in temperature of 18°C, and decreased when the temperature was lowered to 15°C. However, in both cases, the initial force was restored to its original level when the temperature returned to 37°C, thus producing no net change in the superelastic behavior of the coil. The corrosion potential of nickel-titanium coil springs decreases under higher temperatures. Based on these findings, it can be concluded that physiologic changes of temperature in the mouth do not affect the superelastic behavior of nickel-titanium closed-coil springs.
Reviewed by Chris Escott and Jeff Shao
Autotransplantation of mandibular premolars in patients with clefts
Aizenbud D, Zaks M, Abu-El-Naaj I, Rachmiel A, Hazan-Molina H. Mandibular premolar autotransplantation in cleft affected patients: the replacement of congenital missing teeth as part of the cleft patient’s treatment protocol. J Craniomaxillofac Surg 2013;41:371-81
Congenitally missing teeth are common in patients with cleft lip and palate; this can negatively affect their treatment results. Traditional options for restoring the edentulous areas include fixed dental prostheses, removable partial dentures, and dental implants. All of these options have disadvantages, including preparation of adjacent virgin teeth, clasps damaging abutment teeth, and limitations in placing implants in growing patients. Orthodontic space closure of the edentulous cleft sites is another treatment alternative, but it is not suitable for every patient. The authors of this study evaluated the long-term success of autotransplantation of mandibular premolars into edentulous cleft sites in 4 adolescent patients with complete unilateral or bilateral cleft lip and palate. A surgical autogenous bone graft procedure was performed during the early mixed dentition in the cleft site to obtain adequate alveolar ridge dimensions in preparation for future autotransplantation. Each final occlusion with the newly transplanted teeth was evaluated by interdisciplinary team members to assess the esthetic and functional outcomes. Bone in the grafted area was evaluated by using panoramic, posteroanterior, and cone-beam computed tomography scans. Only the mandibular second premolars with half to two thirds of root formation were used. Long-term follow-ups of the transplanted teeth showed no signs of progressive root pathology, gingival disease, or advanced tooth mobility. Complete root length was achieved along with preservation of alveolar graft height in all transplanted teeth. More studies are needed with a larger patient sample to evaluate the success and failure rates of autotransplantation in patients affected by clefts. Based on these results, autotransplantation of mandibular premolars could be considered a viable treatment modality in these patients.
Reviewed by Joshua Parker