In vitro evaluation of the efficacy of a new orthodontic primer in metallic brackets cementation

OBJECTIVE: To evaluate the efficacy of a new orthodontic primer (Ambar APS Ortho; FGM Dental Products, Joinville, SC, Brazil) on shear bond strength (SBS) and degree conversion (DC) of metallic brackets bonding. MATERIALS AND METHODS: 240 sound maxillary premolars were randomized into 24 experimental groups based on: (1) Orthodontic primer (Ambar APS Ortho, Orthoprimer and Transbond XT); (2) Light-curing time (3-seconds and 10-seconds); (3) Light-curing unit (Valo Cordless and Quazar); and (4) Storage condition (immediate time [IT] and after thermocycling [TC]). After each storage time, specimens were subjected to SBS testing at a crosshead speed of 1 mm/min until failure, and values were recorded in MPa. For DC (%) analysis, adhesive discs were prepared and evaluated using micro-Raman spectroscopy at IT only. SBS and DC data were analyzed using four and four-way ANOVA, respectively and Tukey's post hoc test (α = 0.05). RESULTS: Ambar APS Ortho showed significantly higher SBS values across both light-curing units compared to all other groups (p = 0.0001). For DC, Orthoprimer showed the lowest values, while Ambar APS Ortho achieved the highest. Across all primers, a 10 s light-curing exposure resulted in significantly higher DC values compared to 3 s (p < 0.0001). CONCLUSIONS: Ambar APS Ortho exhibited superior performance in both SBS and DC, for both 3 s and 10 s light-curing times as well as IT or AT, supporting its reliability for bonding metallic orthodontic brackets.