The Navy Plaque Index (NPI) was developed as part of the Navy Periodontal Screening Examination, along with the Navy Periodontal Disease Index. It reflects the plaque control status of the patient and emphasizes plaque in the cervical portion of the tooth which is in contact with the gingiva margins. Comparison of scores over time can help guide intervention to prevent periodontal disease.
Teeth examined (US designation):
(1) 3
(2) 9
(3) 12
(4) 19
(5) 25
(6) 28
Substitutions:
(1) If 3, 12, 19 or 28 is missing, then substitute the next most posterior tooth.
(2) If 9 or 25 is missing, then substitute the nearest incisor in the arch. If all of the incisors are missing from the arch. If all incisors are missing from the arch, then substitute a cuspid.
Surfaces examined on each tooth:
(1) facial
(2) lingual
|
Plaque Status
|
Designated
|
Points
|
|
plaque in contact with gingival tissue on mesial proximal surface
|
M
|
3
|
|
plaque in contact with gingival tissue on facial or lingual surface
|
G
|
2
|
|
plaque in contact with gingival tissue on distal proximal surface
|
D
|
3
|
|
plaque on facial or lingual surface of tooth surface but not in contact with gingival tissue
|
R
|
1
|
For each tooth
facial points =
= (M points on facial aspect) + (G points on facial aspect) + (D points on facial aspect) + (R points on facial aspect)
lingual points =
= (M points on lingual aspect) + (G points on lingual aspect) + (D points on lingual aspect) + (R points on lingual aspect)
Generating the NPI
tooth score =
= (facial points) + (lingual points)
NPI score =
= MAX(all 6 tooth scores)
NPI total =
= SUM(all 6 tooth scores)
Interpretation:
• minimum score for a surface: 0
• maximum score for a surface: 9
• minimum tooth score: 0
• maximum tooth score: 18
• maximum NPI score: 18
• minimum NPI total: 0
• maximum NPI total: 108
