Randomisation
CAVITY
Permuted block randomisation with block sizes 4 and 8 was used. Blocks were randomly allocated using a random table of numbers. An operator who was otherwise not participating in the study assigned participants to one of the groups. The allocation ratio was 1:1. The group to be assigned was marked on cards enclosed in sequentially numbered, opaque, sealed envelopes. After the cavity preparation and before the commencement of the restorative treatment, the assigned group was disclosed to the lead investigator who conducted the restorative treatment. Each participant was a unit of randomisation. For a given participant, all eligible permanent molars were restored with the same restorative material, as per group allocation as follows:Group 1: Nanofilled resin composite material Filtek™ Z350XT (3 M ESPE, St. Paul, MN, USA, A2 shade).Group 2: Alkasite resin composite material Cention NThe composition of the materials used for the study is given in Table Composition of principal materials used in the studyFiller: Barrium–aluminium silicate glass (20–30%)Calcium fluorosilicate glass (25–35%), Isofiller (15–25%)Ytterbium fluoride (5–10%)Monomer: Di-methacrylate (95–97%)Stabilizer (< 1%), Initiator (< 1%), Pigment (< 0.1%), Additive (1–2%)Organic phase: UDMA, BisGMA, BisEMA, TEGDMAInorganic matrix: Silica (20 nm non-agglomerated and/or aggregated), zirconia (4–11 nm non-agglomerated and/or aggregated and agglomerated), clusters (size of the cluster ranging from 0.6 to 1.4 μm, 59.5 in volume percentage), zirconia/silica aggregated particles (20 nm particles of silica along-with with 4–11 nm sized zirconia