Are Asymptomatic wisdom teeth healthy?

What is the relationship between wisdom teeth and periodontal disease elsewhere in the mouth?

Periodontal probing depths have been used to detect disease. Deeper PDs (commonly designated as 4mm, or PD4) tend to be found around third molars as soon as the teeth are exposed-> they are associated with anaerobic pathogenic bacteria in a ‘non-sheddable biofilm’ (plaque) beneath the gum tissue. 

A greater amount of biofilm at this site increases the potential for anaerobic conditions, increases the colonization of anaerobic pathogens which can result in an immune response. Over time this chronic inflammatory process from the immune system’s response to the pathogens can cause destroy tissue which supports the teeth. 

Once established, it is difficult to eradicate pathogenic bacteria around third molars.
Pathogens in deeper pockets can serve as a reservoir for pathogens colonizing teeth more anterior in the mouth, particularly second molars.

Studies have shown patients with deeper PDs in the third molar region have increased level of pathogenic and higher clinical evidence of inflammation. The affects not just the wisdom teeth but also teeth more anterior in the mouth. Dental cleanings of the wisdom teeth shown to be ineffective in reducing the deeper PDs. Removal of the wisdom teeth has been shown to significantly decrease the subgingival microbial counts after removal. Elimination of the deeper periodontal pockets where pathogens reside helps decrease the elevated numbers of pathogens, reducing known risk factors that contribute to periodontal disease progression.  

Research has shown that removal of asymptomatic wisdom tooth (third molar) in young adults 

Reduced the prevalence and extent of deeper PD’s on other teeth in the mouth. This has been shown to be more effective in patients 25 yo and younger. 

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A 2009 paper examined the presence of visible third molars and periodontal pathology in 793 adults who were middle-aged and older (52 - 74 yo). (More than 3/4 had seen a dentist in the past year. 86% had never smoked or formerly smoked.)

The most important finding was that a PD of 5mm or more  on the second molars was significantly associated with the presence of an adjacent visible third molar. 

It concluded the findings of more severe periodontal conditions associated with visible this molars in middle-aged and older adults indicate that third molars may continue to negatively impact periodontal health well into later life.

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A 2012 JOMS study asked if there was pathology with asymptomatic third molars.

Found that periodontal pathology was associated with asymptomatic M3.

25% of 329 people with asymptomatic third molars had a PD of at least 5mm either distal to the second molars or on the third molars.

Increased PD’s and periodontal attachment loss (loss of support for teeth) coupled with the colonization of pathogens sport the concept that periodontitis can begin in the third molar region in young adults.

Absence of symptoms associated with retained wisdom teeth does not equal absence of disease or pathology.