11.1 Introduction

Periodontology has evolved from the discipline of controlling the diseases of the tooth-supporting structures to the robust science of understanding the physiology of these tissues and exploring the pathogenesis of periodontal and peri-implant diseases. The science of periodontology originated in the early practices of resecting the ‘diseased’ tissues, progressed through the era of repair and regeneration and is presently pushing the boundaries of technology with experiments of tissue engineering, infecto-genomics, bioinformatics, stem cell research and many other frontier areas. The rapid progress in periodontal research and clinical techniques has been possible largely due to the technology made available to us in the so-called ‘digital’ age. An anecdotal example to emphasize the sheer magnitude of this rapid progress can be obtained from a review by Teles et al. [1]. In their comprehensive assessment of the concepts of periodontal microbiology, the authors provided interesting data from the Forsyth Institute (Cambridge, MA, USA). They stated that the centre assessed 300 subgingival plaque samples by the culture method in the period between 1982 and 1988. This number increased to 9600 between 1988 and 1993 on the application of the colony lift technique and later increased to a staggering 34,400 between 1993 and 1999 after the advent of the checkerboard DNA-DNA hybridization. A centre that processed 300 samples between 1982 and 1988 was able to process about 5734 samples per year by 1999 [1]. This progress has been the result of scientific ingenuity and method, but the role of digitization and automation cannot be discounted.

The world is moving from the information age to the experience age. This transition has been ushered in with the ‘discovery’ of the modern currency—the data. Data or information is the new currency. This currency can be recorded, generated, analysed, stored and transmitted in digital form, thus making it a very powerful tool for progress. Data about a disease that required meticulous recording on paper, careful filing, cataloguing and analysis can today be recorded on smart devices connected to networks and can be analysed by powerful computers at geographically distant locations in a matter of seconds. This has raised the capabilities of scientific research to gigantic proportions. The measure of the quality of a hospital, clinic, university or laboratory is the amount of data it generates. Data is the backbone of epidemiology and can help to identify the trends and patterns in a disease process that may go unnoticed while treating patients at an individual level. Data can be crucial in medico-legal problems to identify the source of the error if any. It can also be a tool for hypothesis generation, testing and development of new clinical methods, all directed towards the ultimate goal of improving the standard of care for our patients.

Digitization of this data is a key step that allows for greater convenience in handling it. Clinicians can utilize digital data for recording and storing relevant findings in a systematic manner. A network of such clinics can generate valuable information about a disease that a single clinic would not be able to. Such a system of practice-based research networks (PBRNs) is already in use in the United States. It is a network of hundreds of private practitioners and has received funding from the National Institute of Dental and Craniofacial Research (NIDCR). Use of digital patient data in the PBRNs will make it an increasingly efficient instrument for dental research. It has been noted that electronic dental records are increasingly being used in the PBRNs and stated that such electronic data may offer an important resource to support not only clinical care but also quality assurance and research [2].

With all the improvements that digitization has to offer, it does come with its share of problems. Ease in the transmission of clinical data gives rise to concerns of privacy and confidentiality. Sensitive data can be accessed by the pharmaceutical industry or other commercial organizations in order to sell a product or treatment that may not always be in line with evidence-based dentistry (EBD). Use of digital media and techniques for diagnosis, treatment planning and even treatment may lead to an over-reliance on technology before it can be allowed to evolve adequately. Availability of too much data can also be tricky as it would finally be at the disposal of an individual who can be easily perplexed with the sheer volume of it. Finally, the very core trait of digitization and automation, which is its rapid evolution, is also its bane. Rapid change in technology leads inevitably to the need to change the hardware and the network bandwidths. This is presently expensive, especially in the developing world, and may be the only limiting factor for the universal acceptance of digital dentistry.

This chapter will focus on digital advances that have significantly contributed to the advancement of periodontology. Digital and technological aspects of various stages of periodontal management will be examined and the influence of digitization on periodontal research will also be discussed.

11.2 Digital Aids in Clinical Periodontics

11.3 Periodontal Probes

The most important tool for all the above-mentioned assessments is the periodontal probe. These are tools designed to measure the periodontal pocket depth. The periodontal pocket is a pathologically deepened gingival sulcus due to the apical migration of the junctional epithelium and has been called a ‘cardinal symptom of periodontitis’ [3]. The first-generation periodontal probes are simple hand instruments with a blunt tip, a calibrated blade and a contra-angled shank (Fig. 11.1). Michigan ‘O’ Probe with William’s markings, the UNC-15 and the WHO probe are a few popular first-generation probes. The first-generation probes are the most widely used instruments for periodontal charting even today. The most commonly stated disadvantages of using these instruments is the lack of standardization of the technique, angulation and the pressure used for probing—all of which can result in significant intra- and inter-examiner variations. This may cast a doubt on the reliability of first-generation probes in periodontal practice, but it has been observed that when used carefully, the first-generation probes can produce meaningful and reasonably reproducible data [4].

Nevertheless, there have been constant efforts to improve the accuracy and reliability of the periodontal probe. The second-generation probes were designed to achieve ‘gentle probing’ and were designed to be pressure sensitive. Gabathuler and Hassell designed the first true pressure-sensitive probe [5]. Another example of this generation is the Yeaple probe designed by Polson et al. [6]. This probe has a pen-like handpiece and an electronic control unit that can be used to set the probing force between 0.05 N and 0.5 N. The handpiece is designed to allow a variety of probe tips to be attached to it.

Third-generation probes were designed to have a constant probing force. The Florida Probe system designed by Gibbs et al. is a prototype of third-generation probes and has seen constant changes as per the changing concepts and technology [7]. The original design of the Florida Probe® system included a handpiece, a displacement transducer with a digital readout, a footswitch and a computer. The system incorporated a 0.4-mm probe tip (resembling a Michigan ‘O’ probe tip) and a standardized force of 25 g. The most important feature of this probe was that it provided a digital output that is directly recorded in a computer [7]. A version of the Florida Probe for use along with an acrylic stent is also available. A common practical issue with periodontal charting is the need for an assistant. A chair-side assistant can help make the charting process faster by noting the findings on a chart or feeding them in a computer system. But this has the disadvantages of requiring more manpower and also the introduction of a source of error. Having the operator record the findings personally has the problem of increasing the appointment time and the need for complex infection control protocols (Fig. 11.2) [8, 9].

To overcome these problems, the Florida probe has been upgraded with a voice recognition tool and is available as VoiceWorks™. This enables a single operator to carry out the periodontal charting. The software allows the operator to record not only the probing depth but also other clinical variables like recession, bleeding on probing, furcation involvement, exudation and mobility. The Florida probe system has been tested for reproducibility and has been validated by several studies and can be considered as a ‘golden standard’ for automated probing [7, 8–11]. Combined with a voice assistant, digital charting, controlled pressure and the option of using a stent, the Florida probe system seems to be a good choice for routine clinical use.

The Toronto automated periodontal probe [12] is another example of third-generation probes. The Toronto probe uses the occlusal or incisal surface of the tooth as a reference point and has the facility of adjusting the probing pressure with the help of air pressure. The probe also incorporates a mercury column for indicating and guiding the angulation of probing. The Toronto probe was modified by Tessier et al. for the estimation of probing velocity [13]. The probing velocity is intended to be a measure of the integrity of the dento-gingival unit (junctional epithelium and a gingival group of fibres) and may be used to quantify the effect of inflammation on the probing depth. This concept is quite ingenious, especially on account of its simplicity and needs to be explored further in clinical studies for improving probe designs.

The Interprobe™ electronic probe system comprises an optical encoder and an optical filament that is inserted into the periodontal pocket. The flexible nature of this probe (optical filament) may result in improved patient comfort, but it may also get displaced due to the presence of sub-gingival deposits. The Interprobe too has a connected digital interface for recording the findings on a computer with graphically illustrated charts [14].

Imaging of the periodontal pocket can also be combined with therapeutic strategies. Elashiry et al. conducted an in vitro study to explore this concept [15]. The authors combined calcium tungstate micro-particles with an antibacterial compound (K 21) and observed that this enhanced the antibacterial action of this mixture against Porphyromonas gingivalis and Streptococcus gordonii. This combined strategy can prove beneficial by facilitating periodontal charting and therapy in a single procedure.

Probing a pocket is a fundamental clinical procedure and is a part of basic oral examination. From the available evidence, it may be prudent to say that a manual probe (first-generation) in the hands of a trained clinician is still a reliable and efficient tool for pocket charting. With this in mind, it is necessary to include adequate training sessions for periodontal probing in the dental graduate curriculum. It has been suggested that dental students should be exposed to actual periodontal probing in patients during preclinical training [16]. Furthermore, this training should be checked by a faculty member and any discrepancy in measurement in excess of 1 mm has to be demonstrated to the student [17].

11.4 Detection of Sub-Gingival Calculus

Dental calculus is the mineralized form of dental plaque. Based on its location on the tooth and with reference to the location of the gingival margin in health, dental calculus is classified as supra-gingival calculus and sub-gingival calculus. While calculus may by itself not be the cause of periodontal disease, it is the most important plaque retentive factor and hence is a key player in the pathogenesis of plaque-induced periodontal diseases. Sub-gingival calculus is a bigger threat to periodontal health than supra-gingival calculus due to crucial differences in the nature of its formation and organization. Sub-gingival calculus derives its mineral content from the gingival crevicular fluid (GCF). It is tenaciously attached to the tooth surface and is sometimes seen to merge with cementum to form the ‘calculo-cementum’. It is often greenish or brown in colour and harbours on its surface an un-mineralized layer of sub-gingival plaque that can be rich in putative periodontal pathogens. Indeed, it has been known for a long time that teeth with sub-gingival calculus lose attachment faster than teeth without sub-gingival calculus [18].

11.4.1 Fibre-Optic Endoscopy

The Perioscopy device (Perioscopy Inc., Oakland, CA, USA) is the only fibre-optic endoscopy-based device available for calculus detection (Fig. 11.3) [19, 20]. The device is a miniaturized version of the medical endoscope and permits a direct visual examination of the tooth wall of a periodontal pocket. The system consists of a 1-mm fibre-optic bundle with illumination, irrigation and a digital display. A randomized controlled trial using this endoscope for sub-gingival scaling showed that use of the Periscopy device resulted in a statistically significant calculus removal, but this effect was limited to interproximal sites deeper than 6 mm [21].

11.4.2 Spectro-Optical Technology (Differential Reflectometry)

This technology is based on a sensor used to detect the variations in the absorption, reflectance or emission of light by dental calculus. A red-light-emitting diode (LED) is used in combination with a fibre-optic ‘spectroscope’ to detect the ‘spectral signature’ of sub-gingival dental calculus. The device (DetecTar; Dentsply Professional, York, PA, USA) consists of a portable, cordless handpiece that picks up the signal and conveys it to a computer which then decodes it using certain algorithms. The instrument also has a curved periodontal probe with millimetre markings and provides audible and visible signals to the operator on detecting calculus (Fig. 11.4) [18, 22].

11.4.3 Autofluorescence-Based Technology

Dental root surface and calculus have the ability to emit fluorescent light after exposure to specific wavelengths of light [18]. This property can be used to detect sub-gingival calculus. The DIAGNOdent caries detection instrument (refer to Chap. 2 for more details on the device) (KaVo, Biberach, Germany) has been adapted for sub-gingival calculus detection (Fig. 11.5). Light is delivered on to the root surface with an optical fibre, and the resulting fluorescence is captured [18]. The intensity of fluorescence is measured and scored on a relative value scale of 0–99 (Table 11.3).

Table 11.3

DIAGNOdent values (as per the manufacturer)

Value	Interpretation
≤5	Clean root surface
5–40	Very small calcified plaque sites
≥40	Mineralized deposits

In vitro studies have shown promising results for using laser fluorescence (DIAGNOdent) for the detection of sub-gingival calculus [23, 24].

11.4.4 Keylaser3

The same diode (InGaAsP) laser unit used in the DIAGNOdent device has been combined with an Er:YAG laser in the Keylaser3™ (KaVo, Biberach, Germany) (Fig. 11.6). The 2940-nm Er:YAG laser can be used for removal of the sub-gingival calculus. The Keylaser3 has shown better results as compared to a differential reflectometry-based device (DetecTar) for the detection of sub-gingival calculus in an in vitro study [25]. The Er:YAG laser has been shown to be comparable to ultrasonic devices for sub-gingival scaling [18] and in combination with a calculus-detection system can be a useful albeit expensive clinical tool.

11.4.5 Ultrasonic Technology

Ultrasonic technology, used widely for scaling has been adapted for the detection of sub-gingival calculus. The PerioScan (Sirona Dental Systems, Bensheim, Germany) device incorporates this technology along with a conventional ultrasonic scaler device. The device has a detection mode and a treatment mode and indicates the detection of calculus by light and sound signals (Fig. 11.7) [26]. A clinical study has demonstrated that the PerioScan device is a reasonably reliable tool for the detection of sub-gingival calculus [27]. This study also observed that the reproducibility of the device was higher in areas of deeper probing depths and furcation involvement.