Depending on the type of Sonicare toothbrush you have, brush heads either snap on or screw on. For example, the DiamondClean, FlexCare, Sonicare for Kids and HealthyWhite models have snap-on brush heads, and the EasyClean, Essence and Xtreme models have screw-on bush heads.
Snap On
Remove the old toothbrush head by snapping it off the brush handle. To do this, pull the brush upward until it snaps off. Snap the replacement head on by aligning it up with the metal rod and pushing down until you hear a loud click.
Screw On
Unscrew the old toothbrush head by holding the bottom of the handle tightly while unscrewing the brush head, using the grooves as a grip. The entire top portion of the toothbrush should detach from the handle -- including the top piece with the brush head and magnet, as well as the plastic dome covering. Screw the replacement brush on by aligning the brush head with the hole and turning the plastic dome to the left until the entire brush head is secured.
Related Articles

How to Remove the Bristle Head from a ...
How to Change the Battery on an Oral-B ...
How to Install New Heads in a Norelco ...

My Sonicare Flexcare Runs But Does Not ...

How to Repair a Rotadent Electric ...

How to Replace the Battery in a ...

How to Clean an Electric Self Shaver

How to Use Proxabrush
How to Fold a Graco Stroller

How to Replace the Battery in a Swiss ...
How to Disassemble Remington Shavers

How to Lubricate a Norelco Razor

How to Clean Out Acrylic Nail Brushes
How to Replace Bristles on a Hair Brush
How to Use the Norelco Jet Clean System

Proper Sanitizing of Electric Razors

How to Clean a Boar Bristle Hairbrush

How to Sharpen Your Dull Rotary Shaver ...

How to Bake With a Pizza Screen

How to Change the Battery for a Pulsar ...
References
Writer Bio
With 10 years of journalism experience, Alissa Marrapodi is the managing editor of Boardroom Journal and Food Product Design. Covering everything from health and nutrition to beauty and fashion, she holds a bachelor's degree in journalism from the Walter Cronkite School of Journalism and Mass Communication at Arizona State University.