Ronald Lowe1, Steven Makowka2, Kevin Manzella3, Stephen Warunek4, Thikriat Al-Jewair5. 1. Dental Student, School of Dental Medicine, State University of New York at Buffalo, Buffalo, NY, USA. 2. Research Specialist, University at Buffalo, School of Dental Medicine, State University of New York at Buffalo, Buffalo, NY, USA. 3. Private Practice, West Seneca, NY, USA. 4. Clinical Assistant Professor, Department of Orthodontics, School of Dental Medicine, State University of New York at Buffalo, Buffalo, NY, USA. 5. Associate Professor and Graduate Program Director Department of Orthodontics, School of Dental Medicine, State University of New York at Buffalo, Buffalo, NY, USA.
Abstract
BACKGROUND: To determine the mechanical properties of the NiTi Memoria® Leaf Spring Activated Expander (NiTi MLSAE) in two forms, unaltered (unbent) and altered (bent) to mimic clinical use. MATERIAL AND METHODS: This in-vitro pilot study was conducted using eight NiTi MLSAE expanders (American Tooth Industries, Oxnard, California) representing four force magnitudes: 10mm 500g, 10mm 900g, 6mm 450g and 6mm 900g models. Two experiments were performed: the first tested the expanders in their unbent form and the second tested them after they were bent by one experienced technician. All expanders were adapted to a standard three dimensional printed maxillary study model. A Dillion Quantrol 500N (110lbf) load cell and a custom-made fixturing apparatus was used to determine the amount of expansive forces delivered. Prior to testing, the ligation compressing the NiTi MLSAE leaves was cut to allow the appliances to expand to their original form. Emperor™ (force) Software was used to measure the expansion forces. RESULTS: The average expansion forces generated by the expanders were: unaltered = 897.4g (8.8N) and bent = 877.0g (8.6N) for the 10mm 900g model, unaltered = 489.5g (4.8N) and bent = 479.3g (4.7N) for the 10mm 500g model, unaltered = 458.9g (4.5N) and bent = 438.5g (4.3N) for the 6mm 450g model, and unaltered = 805.6g (7.9N) and bent = 785.2g (7.7N) for the 6mm 900g model. CONCLUSIONS: Regardless of whether the expander was straight or bent, the forces generated by the 10mm 900g, 10mm 500g and 6mm 450g Ni-Ti MLSAEs correlated with the benchmark study conducted by the manufacturer. However, the forces generated by the 6mm 900g Ni-Ti MLSAE were less than the data published by the manufacturer. Binding was observed when the expanders were manipulated to mimic clinical use, and this may account for the reported lower expansion force. Key words:Maxillary expansion, NiTi, posterior crossbite, malocclusion, maxillary transverse discrepancy. Copyright:
BACKGROUND: To determine the mechanical properties of the NiTi Memoria® Leaf Spring Activated Expander (NiTi MLSAE) in two forms, unaltered (unbent) and altered (bent) to mimic clinical use. MATERIAL AND METHODS: This in-vitro pilot study was conducted using eight NiTi MLSAE expanders (American Tooth Industries, Oxnard, California) representing four force magnitudes: 10mm 500g, 10mm 900g, 6mm 450g and 6mm 900g models. Two experiments were performed: the first tested the expanders in their unbent form and the second tested them after they were bent by one experienced technician. All expanders were adapted to a standard three dimensional printed maxillary study model. A Dillion Quantrol 500N (110lbf) load cell and a custom-made fixturing apparatus was used to determine the amount of expansive forces delivered. Prior to testing, the ligation compressing the NiTi MLSAE leaves was cut to allow the appliances to expand to their original form. Emperor™ (force) Software was used to measure the expansion forces. RESULTS: The average expansion forces generated by the expanders were: unaltered = 897.4g (8.8N) and bent = 877.0g (8.6N) for the 10mm 900g model, unaltered = 489.5g (4.8N) and bent = 479.3g (4.7N) for the 10mm 500g model, unaltered = 458.9g (4.5N) and bent = 438.5g (4.3N) for the 6mm 450g model, and unaltered = 805.6g (7.9N) and bent = 785.2g (7.7N) for the 6mm 900g model. CONCLUSIONS: Regardless of whether the expander was straight or bent, the forces generated by the 10mm 900g, 10mm 500g and 6mm 450g Ni-Ti MLSAEs correlated with the benchmark study conducted by the manufacturer. However, the forces generated by the 6mm 900g Ni-Ti MLSAE were less than the data published by the manufacturer. Binding was observed when the expanders were manipulated to mimic clinical use, and this may account for the reported lower expansion force. Key words:Maxillary expansion, NiTi, posterior crossbite, malocclusion, maxillary transverse discrepancy. Copyright:
Authors: Thuylinh Huynh; David B Kennedy; Donald R Joondeph; Anne-Marie Bollen Journal: Am J Orthod Dentofacial Orthop Date: 2009-09 Impact factor: 2.650