Content Reviewers:Yifan Xiao, MD
Periodontal disease refers to a group of inflammatory conditions that affect the tissues around the teeth.
The mildest form of periodontal disease is gingivitis.
If left untreated, gingivitis can progress to periodontitis, which can lead to destruction of the supporting structures around the teeth.
Now, etiologic factors in periodontal disease are subdivided into two main groups, primary and secondary etiologic factors.
The primary, or initiating etiologic factor is the dental plaque or dental biofilm, which is a sticky collection of bacteria, salivary proteins, and dead cells from the oral mucosa.
On the other hand, secondary, also known as contributing etiologic factors, enhance the ability of dental plaque to cause periodontitis.
Secondary etiologic factors are further subdivided into local factors, which make the dental plaque more resistant and difficult to remove; and systemic factors, which include conditions like diabetes that could impair the host’s immune response and increase the risk of periodontitis.
First, let’s focus on calculus, which is defined as a calcified dental plaque.
Supragingival calculus is located above the gingiva while subgingival is below the gingiva.
Supragingival calculus is visible upon oral examination and it’s composed of organic and inorganic components.
Organic components include bacterial cells, salivary proteins, and lipids.
The inorganic component mainly consists of calcium phosphate.
In contrast to supragingival calculus, subgingival calculus is not visible upon oral examination and it’s harder to remove.
Additionally, subgingival calculus is associated with a higher calcium to phosphate ratio and more serum derived proteins.
Moreover, caries along the gingival margin can cause dental plaque retention, thereby increasing the risk of periodontal disease.
The next local factor is the tooth position.
Overcrowded teeth, or dental crowding, occurs when there’s an insufficient amount of space for all teeth to properly erupt.
Ultimately, this results in misalignment of the teeth.
The next one is root proximity, where the tooth roots are too close to each other and it leads to poorly shaped gingival embrasures.
The last one is tipping.
When a tooth is extracted, the tooth distal to it will often tip mesially into the space and create a difficult area to access.
All three factors can cause dental plaque-retentive areas and therefore increased risk of periodontitis.
Let’s move on to anatomical factors that make biofilm difficult to remove.
Enamel pearls are accumulation of the enamel in locations where it’s not normally found.
Next up are developmental grooves, which are sharp depressions of the tooth surface.
In some individuals, these depressions can extend to the root and this is especially common in maxillary lateral and central incisors.
Finally, we have concavities which are linear depressions of the root surface that are typically located on the mesial surface of maxillary first premolars.
On the other hand, there are also anatomical features of the soft tissue that can increase the risk of periodontitis, such as inadequate attached gingiva, gingival clefts, enlargements, and craters.
These deformities create a favorable environment for bacterial growth and eventual plaque formation.
Moving on to iatrogenic factors.
These contributing factors occur due to inadequate dental procedures and restorations.
Open margins of restorations occur when the restoration material, such as a crown, does not reach the natural tooth margin, leaving a small gap where dental plaque can accumulate.
On the other hand, overhanging margins of restorations occur when the material extends beyond the tooth structure, creating an overhang.
In addition to being extremely hard to clean, the newly formed environment also promotes the growth of Gram negative bacteria that can eventually cause periodontal disease.
You should not confuse overhanging margins with over contoured crowns and restorations, which are associated with biofilm retention and poor self-cleaning mechanisms of the teeth by surrounding tissues, such as cheeks, lips, and tongue.
Finally, we have open contacts or spaces between adjacent teeth that are commonly associated with food impaction.
Food impaction can lead to direct trauma to the interdental tissue and it also creates a favorable environment for bacterial growth and the formation of dental plaque.
The last main local factor associated with increased risk of periodontitis are traumas, such as occlusal trauma or soft tissue trauma.
Occlusal trauma occurs when the maxillary and mandibular teeth exert force on each other, resulting in the injury of the periodontium.
In combination with inflammation, occlusal trauma can result in periodontal damage.
On the other hand, soft tissue trauma is typically associated with inappropriate oral hygiene techniques such as vigorous brushing and flossing.
Now, moving on to systemic conditions associated with periodontal disease.
First, let’s focus on endocrine disorders, starting with diabetes mellitus.