One third of the population have a genetic tendancy to develop periodontal disease.  Many people are born with a "sensitivity" to plaque bacteria. One could describe it as an "allergy". For these individuals, plaque causes inflammation on contact and triggers their immune system to go into hyperdrive, creating an overproduction of harmful enzymes, thus periodontal destruction ensues.   

For more information on genetics and periodontal disease go to these sites:

http://www.perio.org/consumer/geneticbasis.htm  http://www.dentistry.com/articles/Genetic_Marker_Discovered_for_Periodontal_Disease.aspx  http://www.umm.edu/patiented/articles/who_gets_periodontal_disease_000024_4.htm 

The good news is that advanced technologies will now allow us to alter the usually predictably poor outcome of genetic periodontal disease. Host factors, such as genetics, must be addressed to effectively put periodontal disease into remission. No longer will only cutting the pockets out with surgery, or only doing perioscopy, be the entire "cure".

Individuals with a genetic predisposition must be identified before anything we do clinically will be successful long term. These individuals over-produce destructive enzymes four fold, which causes severe destruction of the periodontium. The chronic nature of this disease can fool even the most astute clinician. Damage to the periodontium can occur quickly or slowly, therefore, preventative care becomes crucial.

Utilizing a safe and effective "Host Modulated Therapy" (low dose Doxycycline 20mg -LDD), or PerioStat(TM), will considerably change the course of chronic periodontal disease.