Date of Award
Summer 2024
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Dentistry
First Advisor
Dawei Liu
Second Advisor
Marinho Del Santo
Third Advisor
Jeffrey Toth
Abstract
Objective: This study aimed to quantify the effects of different materials, sizes of the continuous archwires in leveling the exaggerated curve of Spee. We used an orthodontic force tester apparatus to measure the forces and moments delivered by the archwires to the brackets attached to the sensors of one quadrant of the arch (from 1st incisor to 2nd molar). The hypothesis is that there is no difference in the load and moments between the incisors when the curve of Spee is leveled with the three different mechanical designs being tested. Methods: An orthodontic force tester (OFT) was used to measure the forces and moments delivered by the archwires to brackets attached from the first incisor to the second molar. Dentoforms simulating an exaggerated curve of Spee were made from CBCT scans. Zero-prescription .022”x.028” brackets were used and the archwires were ligated using elastomeric ligatures. Archwires with 3 types of material, reverse curve of Spee nickel titanium [rNiTi], stainless steel step down [SSSD], and titanium molybdenum step down [TMASD]) in one size of .016”x.022” were tested (n=10). The NiTi archwire had a prefabricated reverse curve of Spee, and the SSSD and TMASD archwires had bilateral 1.0 mm stepdown bends between the canine and second incisor and the second incisor and first incisor, respectively. For statistical analysis, variance analysis (ANOVA) was used to examine the differences in the effects of different archwire materials and designs on the incisors and molars in relation to leveling the curve of Spee. A p-value less than 0.05 was considered statistically significant. Results: Comparing the archwires, the rNiTi design had the least force generation on the incisor and molar, followed by the TMASD, then the SSSD design had the greatest, while the TMASD design and SSSD were similar in forces. The rNiTi design had the greatest moment generation on the incisors, followed by the SSSD, then TMASD had the least; however, for the molar, all wires were similar in moment generation. Conclusion: The hypothesis is rejected. Force and moment distributions in a quadrant illustrate significant differences between the incisors and the premolars and molars. For archwire force comparisons on the incisors and molars, rNiTi displayed the least force, followed by TMA then SS. For archwire moment comparisons on the incisors, rNiTi displayed the greatest moment, followed by TMA then SS. For archwire moment comparisons on the molars, rNiTi, TMA, and SS had similar moment generation.