The problem is in the node rendering, not the page rendering. Its a lower/smaller level than the preprocess page. You can use node template overrides such as "node-fonts.tpl.php" where "fonts" is the name of the node type. You will copy "node.tpl.php" to make this then modify it to your liking. This template is found in "[SITE ROOT]/modules/node/". Copy this to your theme folder. When I do this I create a subfolder called "node" to help organize the theme overrides.
If you want an easier solution then I would use ConTemplate (otherwise known as Content Template). This will allow you to control this from the content type admin config (creates a template tab which has options for the teaser and the full node). This also provides details about the available variables and sample data from the last inserted node of the type you are looking at.