variability and errors can affect the readings of the markings.
In order to overcome these disadvantages of conventional probes, new generations of probes have been developed. These include but are not limited to the following4:
Constant-pressure probes: Designed to be pressure sensitive, therefore allowing for standardization of the force applied during PD measurements.
Computer-assisted/automated probes: This generation of probes was developed based on constant-pressure probes. Added features include automated detection of the measurement and computer-assisted data capture into a storage system. This minimizes possible errors from probe reading and data recording.
3D probes: This instrument aims to develop a method to record the PD in a serial matter instead of linear measurements.
Noninvasive probes: Probing into periodontal pockets can often be uncomfortable and/or painful to patients. This probe system is still under development, and it aims to identify the periodontal pocket and attachment level without the need to physically penetrate the tissues.
The usage of these newer probe systems is still very limited due to various considerations such as cost (more expensive), less tactile sensitivity, and less accessibility for most dentists. To date, the conventional periodontal probe is still the most popular system that is used in dental offices when a periodontal examination is performed.4
It is very important to bear in mind that, when measuring PDs with a conventional probe, there are a number of factors that can affect these measurements and their accuracy. The variables are summarized in Table 2-1.5–14
TABLE 2-1 Variables affecting probing measurements
| Reproducibility | Operators’ experience and skills would affect the inter- and intraexaminer reproducibility. | |
| Probing force | Probing force affects how deep the periodontal probes penetrate into the pocket and the connective tissue; greater probing force usually results in deeper PDs.5 It has been recommended that 30 g (0.3 N) of probing force be used during periodontal examination to allow the probe tip to remain within the junctional epithelium.6,7 Probing forces up to 50 g (0.5 N) would penetrate deeper, and the probe tip could reach closer to the alveolar bone.6,7 | |
| Probe angulation | Mean PDs could be 1 mm greater with midproximal compared to line-angle measurements.8 | |
| Gingiva inflammation | Periodontal probes tend to penetrate deeper into the gingival tissue when inflammation is present9–14: | |
| Healthy dentition | Apical one-third of junctional epithelium | |
| Gingivitis | Apical one-third of junctional epithelium | |
| Periodontitis | Coronal one-third of connective tissue | |
| Posttreatment periodontitis | Apical one-third of junctional epithelium | |
| Site and local anatomy | Crown contours, defective restorations and margins, tipped or rotated teeth, osseous ledges, and subgingival calculus can all affect probing accuracy. | |
| Type of probe | Different types of conventional probes, pressure-sensitive probes, and computer-assisted data recording probes could yield different measurements. | |
| Natural dentition versus dental implants | Probing at an implant site usually results in deeper depths compared with probing at a natural tooth9–14: | |
| Healthy implant | Apical one-third of junctional epithelium to coronal one-third of connective tissue | |
| Peri-implant mucositis | Apical two-thirds of connective tissue | |
| Peri-implantitis | Apical one-third of connective tissue and close proximity to bone | |
| Posttreatment peri-implantitis | Apical two-thirds of connective tissue | |
It is also of relevance to differentiate between the terms “pocket depth” and “probing depth.” The measurement obtained with a probe into the gingiva includes not only the depth of the gingival sulcus or periodontal pocket, but also an additional distance that represents varying degrees of adjacent tissue penetration.15 Therefore, the objective when a periodontal probe is inserted into the space between the tooth and the gingiva is to measure the probing depth instead of the anatomical structure of the pocket depth, which can only be accomplished histologically.2 Listgarten also emphasized the use of the correct terminology “probing depth” when describing periodontal probing in the literature.15
CLINICAL ATTACHMENT LEVEL
The definition of CAL is the distance from the cementoenamel junction (CEJ) to the tip of a periodontal probe during diagnostic periodontal probing.1 The amount of gingival recession is needed to calculate the CAL. Recession by definition is the migration of the gingiva to a point apical to the CEJ,1 and it is often described as the distance between CEJ and the free gingival margin. Recession can be recorded as a positive (+) or negative (–) measurement. Recession is recorded as “+” when CEJ is visible and the free gingival margin is below the CEJ. However, when there is gingival enlargement, recession is recorded as a negative “–” measurement (Fig 2-1). CAL can then be calculated by adding PD and recession (making sure to include “+” or “–”). In Fig 2-1, all four case scenarios measured 6 mm PD; however, when recession is taken into account to determine the CAL, it is clear that the degree of periodontal destruction of these four cases is very different. Therefore, compared with PD, the level of CAL can provide a better overall estimate of the periodontium, and it usually correlates better with radiographic bone loss.3
Fig 2-1 Representation of different situations with 6 mm PD and different attachment levels. Rec, recession.
ATTACHED GINGIVA AND KERATINIZED GINGIVA
The amount of AG and the width of KG are also important clinical parameters to record during a comprehensive periodontal evaluation. AG extends from the free gingival marginal groove to the mucogingival junction (MGJ), and it is the portion of the gingiva bonded to the tooth and the alveolar bone through gingival fibers1 (Fig 2-2). On the other hand, KG includes free (marginal) gingiva and the AG. Around teeth, healthy and uninflamed gingival tissue usually encompass a band of AG, which is crucial to defend against pathogens.2
Fig 2-2 Gingival landmarks.
Lang and Löe performed a clinical study evaluating the inflammation status by examining gingival exudate of teeth with or without 2 mm of KG.16 The results from this investigation indicated that most teeth with < 2 mm of KG presented with clinical inflammation and varying amounts of exudate while surfaces with ≥ 2 mm of KG were healthy, and most of these surfaces showed no exudate.16 Therefore, it was concluded that 2 mm of KG and 1 mm of AG are needed to maintain periodontal stability.16 Nevertheless, evidence from another study demonstrated that when good plaque control is achieved through adequate home care, the presence of AG/KG is not an essential prerequisite for the maintenance of periodontal health and attachment.17 Overall, it is generally accepted that the presence of a collar of KG and AG is beneficial for the long-term stability of the periodontium, and even more important when oral hygiene is not optimal. The MGJ and the width of KG can be determined using the methods demonstrated in Fig 2-3 and Box 2-2.2,16
Fig 2-3 Visual examination of the MGJ. The arrow indicates the junction between the KG and the mucosa. KG presents as a coral pink color, while mucosa is redder.
BOX 2-2 Methods to determine the location of MGJ and the width of KG3,16
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