Here is the instructions directly taken from AADSAS for writing personal statement
Personal Statement
You will not be able to revise this section after e-submitting your ADEA AADSAS application. Print and review your entries carefully before submitting. The personal essay provides an opportunity for you to explain why you desire to pursue dental education.
It is recommended to compose your essay in a text-only (e.g., Notepad, Microsoft Word), review your essay for errors, and cut and paste the final version into the text box. The essay is limited to approximately one page (4,500 characters, including spaces).
Note: To open Notepad, click Start, point to All Programs, point to Accessories, and then click Notepad. From Notepad, you can view how the text looks and edit it (such as adding or removing line feeds) before saving it as a .txt file in a known folder. You can then copy the text from Notepad and paste it into the textbox in the application.
Some formatting characters and indentation used in programs like Word will not display properly. Take the time to review the final document before you submit your application to ADEA AADSAS.
Your personal essay will be formatted and printed in standard paragraph form before being sent to your designated dental schools as a part of your ADEA AADSAS application. It will not be sent to your designated dental schools in the format you view in the online application.
What should you write?
The Admissions Committee members who read your essay are looking for individuals who are motivated, academically prepared, articulate, socially conscious, and knowledgeable about the profession. Write about your experiences and any qualities that will make you stand out. Check the
ADEA Official Guide to Dental Schools for ideas about essays.