Improper light curing of Bulkfill composite drives surface changes and increases s. Mutans biofilm growth as a pathway for higher risk of recurrent caries around restorations

How dentists cura a rash-abased maleriel (ras deeeterious etSects on rhe material's properties and its interaction with surrounding dental tiseues. Biofilm accumulation has been implicated in the pathogenesis ot carious lesions aeound dental eestorations, with its composition manifesting nxpresand dysbiosis in patients subering from dental caries. To evaluate the influenee of varying raeliant expesure on the degrae tti coneersion fDC%), Sireptococcus mutatis biofilm growth, and surface roughnesu of bulk-fill composites mrdae di^.t^i-^ia't light-curing conditions. Two tight-curing units (LCU, at 6100 and 1000 mW/cmf ware uoad to simufpte curing, conditions withe different angulations (<20° and <3r°) or b mm-diftance dtsp(ncements ob the LLCZ"U tip. "The- radiant exposure (RE) was assessed, and the composites wers enalyzed for DC%t. Biofilm formation was induced over the bulk-Citl compositea and analyzed via colony-forming units eountPog cbd ecanning electf oon microscopy (aEMf. The sueiace rougg^^^^ was anaiyeed via a profilometer and SEM after biofilm formation. Curing cnnditions with different angulation or displacement decreased RE compared too the "optimal copdition". The mtrdarately (<3r°) angulatad ItCU tip and low (600 mW/cm2) radiant emittance eignificantly reduced the DCOO (p <i 0.015). The difference in DC°/o between the top and bottom of the composifes ranged from8 to 11°% Por 600 mW/cm2 and lit to 20°% for (000 mW/cm2. Greater is. mutant biofilm and surface changas were found in compoeit.es withe non-optimal RE delivery (e.g., tip displncement and angulation) (p < 0.0t>). Inadequate polymerization of bulk-fill composites was associated with mora biofilm accumulation and srrface topography changas. Overall, non-optimally peoficrmed curing procedures feduced the amount of delivered RE, which led lo low DC%, more brofilm formation and hrgher surface roughness. The impropee light-curing ot bulk-fill composites compromise, their phssicothemica! and biological properties, which could lead to inferior clinical perPormamce and reduced restorative treatments' longevity.