diff --git a/src/Extensions/ContentReviewCMSExtension.php b/src/Extensions/ContentReviewCMSExtension.php
index 2a90896..f288118 100644
--- a/src/Extensions/ContentReviewCMSExtension.php
+++ b/src/Extensions/ContentReviewCMSExtension.php
@@ -3,7 +3,6 @@
 namespace SilverStripe\ContentReview\Extensions;
 
 use SilverStripe\Admin\LeftAndMain;
-use SilverStripe\Admin\LeftAndMainExtension;
 use SilverStripe\CMS\Controllers\CMSMain;
 use SilverStripe\CMS\Model\SiteTree;
 use SilverStripe\ContentReview\Forms\ReviewContentHandler;
@@ -14,14 +13,15 @@ use SilverStripe\Control\HTTPResponse_Exception;
 use SilverStripe\Forms\Form;
 use SilverStripe\ORM\ValidationResult;
 use SilverStripe\Security\Security;
+use SilverStripe\Core\Extension;
 
 /**
  * CMSPageEditController extension to receive the additional action button from
  * SiteTreeContentReview::updateCMSActions()
  *
- * @extends LeftAndMainExtension<CMSMain>
+ * @extends Extension<CMSMain>
  */
-class ContentReviewCMSExtension extends LeftAndMainExtension
+class ContentReviewCMSExtension extends Extension
 {
     use PermissionChecker;
 
diff --git a/src/Extensions/ContentReviewDefaultSettings.php b/src/Extensions/ContentReviewDefaultSettings.php
index 1c8e155..ba64a4e 100644
--- a/src/Extensions/ContentReviewDefaultSettings.php
+++ b/src/Extensions/ContentReviewDefaultSettings.php
@@ -10,12 +10,12 @@ use SilverStripe\Forms\ListboxField;
 use SilverStripe\Forms\LiteralField;
 use SilverStripe\Forms\TextareaField;
 use SilverStripe\Forms\TextField;
-use SilverStripe\ORM\DataExtension;
 use SilverStripe\ORM\ManyManyList;
 use SilverStripe\Security\Group;
 use SilverStripe\Security\Member;
 use SilverStripe\Security\Permission;
 use SilverStripe\SiteConfig\SiteConfig;
+use SilverStripe\Core\Extension;
 
 /**
  * This extensions add a default schema for new pages and pages without a content
@@ -25,9 +25,9 @@ use SilverStripe\SiteConfig\SiteConfig;
  * @method ManyManyList<Group> ContentReviewGroups()
  * @method ManyManyList<Member> ContentReviewUsers()
  *
- * @extends DataExtension<SiteConfig>
+ * @extends Extension<SiteConfig>
  */
-class ContentReviewDefaultSettings extends DataExtension
+class ContentReviewDefaultSettings extends Extension
 {
     /**
      * @config
diff --git a/src/Extensions/ContentReviewLeftAndMainExtension.php b/src/Extensions/ContentReviewLeftAndMainExtension.php
index 9984eb8..49148ad 100644
--- a/src/Extensions/ContentReviewLeftAndMainExtension.php
+++ b/src/Extensions/ContentReviewLeftAndMainExtension.php
@@ -3,12 +3,12 @@
 namespace SilverStripe\ContentReview\Extensions;
 
 use SilverStripe\Admin\LeftAndMain;
-use SilverStripe\Admin\LeftAndMainExtension;
+use SilverStripe\Core\Extension;
 
 /**
- * @extends LeftAndMainExtension<LeftAndMain>
+ * @extends Extension<LeftAndMain>
  */
-class ContentReviewLeftAndMainExtension extends LeftAndMainExtension
+class ContentReviewLeftAndMainExtension extends Extension
 {
     /**
      * Append content review schema configuration
diff --git a/src/Extensions/ContentReviewOwner.php b/src/Extensions/ContentReviewOwner.php
index 260fd49..ec6708a 100644
--- a/src/Extensions/ContentReviewOwner.php
+++ b/src/Extensions/ContentReviewOwner.php
@@ -4,17 +4,17 @@ namespace SilverStripe\ContentReview\Extensions;
 
 use SilverStripe\CMS\Model\SiteTree;
 use SilverStripe\Forms\FieldList;
-use SilverStripe\ORM\DataExtension;
 use SilverStripe\ORM\ManyManyList;
 use SilverStripe\Security\Group;
 use SilverStripe\Security\Member;
+use SilverStripe\Core\Extension;
 
 /**
  * @method ManyManyList<SiteTree> SiteTreeContentReview()
  *
- * @extends DataExtension<Group|Member>
+ * @extends Extension<Group|Member>
  */
-class ContentReviewOwner extends DataExtension
+class ContentReviewOwner extends Extension
 {
     /**
      * @var array
diff --git a/src/Extensions/SiteTreeContentReview.php b/src/Extensions/SiteTreeContentReview.php
index 8bda5ce..3613c42 100644
--- a/src/Extensions/SiteTreeContentReview.php
+++ b/src/Extensions/SiteTreeContentReview.php
@@ -24,7 +24,6 @@ use SilverStripe\Forms\LiteralField;
 use SilverStripe\Forms\OptionsetField;
 use SilverStripe\Forms\ReadonlyField;
 use SilverStripe\ORM\ArrayList;
-use SilverStripe\ORM\DataExtension;
 use SilverStripe\ORM\DataObject;
 use SilverStripe\ORM\DB;
 use SilverStripe\ORM\HasManyList;
@@ -41,6 +40,7 @@ use SilverStripe\SiteConfig\SiteConfig;
 use SilverStripe\View\Requirements;
 use Symbiote\QueuedJobs\DataObjects\QueuedJobDescriptor;
 use Symbiote\QueuedJobs\Services\QueuedJobService;
+use SilverStripe\Core\Extension;
 
 /**
  * Set dates at which content needs to be reviewed and provide a report and emails to alert
@@ -56,9 +56,9 @@ use Symbiote\QueuedJobs\Services\QueuedJobService;
  * @method ManyManyList<Member> ContentReviewUsers()
  * @method HasManyList<ContentReviewLog> ReviewLogs()
  *
- * @extends DataExtension<SiteTree>
+ * @extends Extension<SiteTree>
  */
-class SiteTreeContentReview extends DataExtension implements PermissionProvider
+class SiteTreeContentReview extends Extension implements PermissionProvider
 {
     /**
      * @var array