Combination instruments for probing caries and parodontium.
Most explorers and periodontal probes are available also in single-ended designs.
WHO probe was developed for CPITN method
0 = healthy
1 = bleeding during probing
2 = supra- and/or subgingival calculus, filling or crown excesses
3 = gingival pockets to 5 mm
4 = pockets deeper than 6 mm