The National Guideline Clearinghouse is an initiative of the Agency for Healthcare Research and Quality (AHRQ) , U.S. Department of Health and Human Services. NGC was originally created by AHRQ in partnership with the American Medical Association and the American Association of Health Plans (now America's Health Insurance Plans [AHIP]).
The NGC mission is to provide physicians and other health professionals, health care providers, health plans, integrated delivery systems, purchasers, and others an accessible mechanism for obtaining objective, detailed information on clinical practice guidelines and to further their dissemination, implementation, and use.
A quick search using the keywords Oral Health will lead you to the following set of resources. Remember to look at dates of guideline publication as well as institutes and organizations producing guides as these might affect their applicability to your particular clinical experience.