Glossary entry
Supragingival vs Subgingival
Also called: Above and below the gumline
Supragingival refers to the clinical area above the gingival margin; subgingival refers to the area below, within the periodontal pocket.
What is supragingival vs subgingival?
The supragingival environment is the visible tooth surface above the free gingival margin — accessible, oxygen-rich, and dominated by early-colonizer bacteria. The subgingival environment lies within the gingival sulcus or periodontal pocket, is anoxic, has its own fluid flow (gingival crevicular fluid), and hosts pathogenic biofilm associated with periodontitis.
The distinction matters clinically because: (1) instrumentation technique differs — supragingival tools are not automatically appropriate subgingivally; (2) powder selection differs — sodium bicarbonate is supragingival only; (3) evidence for efficacy and safety is sampled separately.
When is it used?
This distinction governs:
- Powder selection for air polishing
- Choice of ultrasonic tip and power setting
- Use of dedicated subgingival nozzles for deep pockets
- Interpretation of clinical evidence