Alignment Efficiency of Two Thermal Activated Orthodontic Archwire Sequences

A parallel randomized clinical trial was conducted involving 42 patients ages 15 to 25 years (mean: 19.5 years) who required orthodontic treatment including the correction of mandibular anterior crowding. Eligibility criteria were no active caries, exemplary hygiene, non- extraction in the lower arch and no significant tooth size or shape abnormalities. Outcome: The primary outcome was the degree of crowding measured on plaster casts using Little's Irregularity Index. The secondary outcome was crowding survival time until the occurrence of correction in a six-month period. Randomization: The patients were randomly allocated to the different groups using sealed opaque envelopes. Blinding: The patients were blinded to the group to which they were allocated. Intervention: Patients were treatment with a pre-adjusted appliance (0.022 in- Roth prescription). Two nickel-titanium alignment and leveling sequences were employed - NiTi archwire: 0.012 in and 0.019 X 0.025 in; and thermal activated NiTi archwires: 0.018 in and 0.016 X 0.022 in with different austenite finish temperatures (37ºC and 35ºC), which formed the different study groups.

Inclusion criteria

• Moderate mandibular anterior crowding (crowding: 4 to 6 mm) according to Little's Irregularity Index
• Presence of all teeth in lower arch through to the second molars, no indication for extractions in the lower arch
• No need for therapeutic interventions (use of inter-maxillary elastic bands, inter-dental wear, open NiTi spine, active lip bumper)
• Absence of systemic conditions that could affect tooth movements
• Absence of significant tooth size or shape abnormalities
• No history of trauma and no history of root resorption or alveolar bone loss.

Exclusion criteria

• Severe mandibular anterior crowding (crowding: up to 7 mm) according to Little's Irregularity Index
• Absence of any teeth in lower arch through to the second molars
• Indication for extractions in the lower arch
• Need for therapeutic interventions (use of inter-maxillary elastic bands, inter-dental wear, open NiTi spine, active lip bumper)
• Presence of systemic conditions that could affect tooth movements
• Presence of significant tooth size or shape abnormalities
• History of trauma and history of root resorption or alveolar bone loss.