A 45 year old female patient comes to your clinic for routine dental check up. Intraoral examination proximal restoration with 15, 16; amalgam restoration with 26; composite restoration with 35 and deep pit and fissures with 36, 37 ,46, 47. PRR was adviced with lower molars. Which of the following steps can be done to make this restoration more retentive?
The tooth is isolated by using a rubber dam (or another effective isolation method such astton rolls or Isolite). Isolation of the area is crucial to the success of the sealant. If proper isolation cannot be obtained, the bond of the sealant material to the tooth surface can be compromised, resulting in either loss  of  the  sealant  or  caries  under  the  sealant.  The  area  is cleaned with a slurry of pumice on a bristle brush. Bristles reach into faulty areas better than a rubber prophy cup can, which tends to burnish debris and pumice  into the pits and fissures. The tooth is rinsed thoroughly, while the explorer tip is used carefully to remove residual pumice or additional debris. The tooth surface is dried, and etched with 35% to 40% phosphoric acid for 15 to 30 seconds. Liquid acid etchants  were  used  in  the  past,  but  gel  etchants  are  more popular now because they are easier to apply and to control. However, only gels that are sufficiently fluid to penetrate the grooves and fissures should be used. 
 
Ref: Sturdevant 6th edition pg 256
Reinforce them with bulk formed composite
Cleaning of fissure and prevent moisture
Etching
Increased depth with burs