It was a busy night of age-grade action as the U18s continued their campaign, while the U16s East and West sides returned to action for the first time in the New Year.
At Ystrad Mynach, the U18s were on their heels early against the Dragons, conceding a couple of tries before battling back to level 12-12 at the break.
Slick hands put wing Matthew Williams in at the corner, then a well-drilled line-out drive led to a penalty try being awarded.
But Dragons were back in front two minutes after the restart thanks to a try from No. 8 Ryan Jones and when wing Ioan Duggan intercepted and sped away for the bonus-point score, the home side were in firm control.
Replacement centre Wil Thomas showed good strength to cross after some powerful carries by the forwards to give the Scarlets some hope, but Dragons were able to see out the win without further concern.
At Parc y Scarlets, Scarlets East romped to a 50-17 win over Dragons Black, scoring seven tries in another impressive display.
The West Walians were 31-5 up at half-time thanks to tries from centre Jake Nottingham, wing Olly Lloyd and fly-half Math Jones. Full-back Cai Evans kicked four conversions and a penalty as the home side dominated.
It was more of a contest in the second period, but tries from replacement Osian Williams and two from skipper and No. 8 Alex Ridgeway ensured the East boys made it three wins from four in the championship to go top of the standings.
Scarlets West U16s took on Cardiff South at the Arms Park and were beaten 37-18.