Periodontal Disease

Periodontal Probes

The periodontal probe continues to be one of the more useful diagnostic tools to determine the presence and severity of periodontal lesions. An ideal periodontal probe should possess specific characteristics:

1. It should be tissue-friendly and not traumatize periodontal tissues during probing.

2. It should be suitable as a measuring instrument.

3. It should be standardized to ensure reproducibility, particularly with respect to recommended pressure.

4. It should be suitable both for use in the clinical setting where precise data documentation is required on an individual patient basis, and for screening purposes, as in epidemiology.

5. It should be easy and simple to use and read.

Over the years, the shape, design, and function of probes have changed to enhance accuracy and reproducibility. Three generations of probes have been suggested by Philström¹⁹: first generation—conventional handheld instruments; second generation—force application during measurement; third generation—force application using automated measurement and computerized data capture. The conventional handheld probes most commonly are preferred for their ease and simplicity in application. However, the use of second- and third-generation probes also is common, especially in the field of research where variables such as pressure or force on probing, reproducibility, and accuracy are investigated. Various studies considering these different probes and their characteristics also are found in the literature. Samuel et al²⁰ have published an in vitro study testing the accuracy and reproducibility of automated and conventional probes. In that study automated probes were reported to offer increased accuracy over conventional probes, and the reproducibility of both Florida pocket-depth and disk probes was found to be comparable with that of the conventional probes. Buduneli et al²¹ in an in vitro model investigated the accuracy and reproducibility of two manual probes and concluded that overall accuracy was higher with the WHO probe compared with the Williams probe. This study also revealed better reproducibility percentages for the WHO probe in comparison with the Williams probe.

Probe Characteristics

Characteristics of the probe, such as its diameter at the tip and the calibration, can influence PPD measurement. Different probes, such as Michigan, Williams, Marquis, Goldman-Fox, and Nabers probes, have different dimensions and a different diameter at the tip. The tip diameters range from 0.28 mm for the Michigan “O” probe to 0.7 mm for the Williams probe. Moreover, the widths of probe markings in the painted bands differ by as much as 0.7 mm between probes because of manufacturing errors. Figure 3 illustrates different manual probes. Van der Zee et al⁵ evaluated the accuracy of probe markings in a variety of probes and noted that probes from the same batch from the same production line could differ by more than 0.5 mm in calibration and the mean tip diameter ranged from 0.28 mm to 0.7 mm. They concluded that probe-tip diameter and calibration should be considered in addition to other variables of periodontal probing. Standardization of tine characteristics and avoidance of the use of different types or batches in a single study should enhance the accuracy and reproducibility of periodontal probe-dependent measurements.

Atassi et al²² compared a parallel-sided probe to a tapered probe (Figure 4). Results indicated that the parallel-sided tine tended to yield a deeper reading when a difference occurred. Garnick and Silverstein²³reviewed the effect of the probe-tip diameter on accurate probe placement and recommended a probe-tip diameter of 0.6 mm and a 20-g force to measure a reduction in the clinical probing depth after therapy. Quirynen et al²⁴ found interexaminer variability was dependent upon probe type. The study compared a conventional periodontal probe with an automatic, computerized, constant-force, electronic probe in vivo and found that PPD measurements recorded with the manual probe were consistently deeper than those recorded with the electronic probe. Wang et al⁴ evaluated intra- and interexaminer reproducibility for conventional and electronic probes and found that reproducibility may not necessarily be higher with an electronic, force-controlled periodontal probe than with a conventional manual probe. In an attempt to overcome some of the technical challenges associated with conventional manual periodontal probes, numerous electronic periodontal probes have been developed that permit probe insertion with a controlled force.⁹

The controlled-force probe that has achieved the most widespread use is the Florida Probe^® (Florida Probe Corp, Gainesville, FL) (Figure 5A and Figure 5B). This computer-linked device has in vitro resolution of 0.1 mm and is capable of recording probing depths and relative attachment levels.^25-31 Clinical measurements obtained with conventional manual probes are consistently greater than those obtained with controlled-force probes.^24,32-37 One of the possible reasons for this is reduced tactile sensitivity associated with the use of controlled-force probes. This is especially true in patients with untreated periodontitis for whom the presence of subgingival calculus can interfere with probe insertion. With conventional probes, it generally is easier for the operator to manipulate the probe tip past subgingival calculus deposits. A definite advantage of computer-linked probes is that they can record probe readings automatically. Some systems allow voice-activated data entry.³⁸ The usefulness of controlled-force probes in day-to-day clinical practice has not yet been demonstrated.⁹

One possible reason for the lack of widespread acceptance of controlled-force electronic probes by practitioners might be increased patient discomfort when these devices are used, particularly around the anterior teeth. During probing with conventional manual probes, the operator can decrease the insertion force rapidly if the patient shows any early signs of discomfort. With controlled-force probes, this patient–dentist feedback is not possible because the probe is inserted into the pocket in one motion and with fixed or predetermined force