The Cooperative Patent Classification (CPC) system assigns at least one classification to a patent. You may see one ore more of classifications bolded; these refer to an 'Inventive' class and address the disclosed invention portion (or dislosure) of the patent.
The CPC system is hierarchical and uses a series of letter and numerical codes to denote each patent's grouping within the larger hierarchy. These codes or symbols work as follows:
|CPC Classification Codes
|Example: A61K 39/0011
|Section: A-H, Y
|A: Human Necessities
|Class: 2-digit number
|61: Medical or Veterinary Science; Hygiene
|K: Preparations for Medical, Dental or Toilet Purposes
|Main Group: 1-, 2- or 3-digit number, followed by /00
|39/00 Medicinal preparations containing antigens or antibodies
Sub-Group: 2-digit number
|11 Cancer antigens
To see this example, begin at: http://worldwide.espacenet.com/classification?locale=en_EP#!/CPC=A
Use Espacenet's CPC look-up tool to see which code(s) might apply to chin implants.
What did you find? Did the patents you find associated with these codes look relevant? Were the results better than those you found using just keywords?
Go back to your earlier search results and see if you can find a relevant patent. Do a classification search using a bolded CPC code. Are the results any better?