Point-of-Care: A Novel Approach to Periodontal Diagnosis

Abstract

Being one of the prevalent oral diseases, periodontal disease is marked by the presence of gingival inflammation and periodontal tissue destruction. Recently, there is a paradigm shift in the understanding of periodontal disease; it is now believed to be episodic in nature, showing periods of activity and inactivity. Thereby, posing a challenge for clinicians to diagnose this. Conventional diagnostic methods basically measure past tissue destruction, arising the need for new diagnostic methods that should be able to detect active sites of destruction, predict future progression, and determine the response to the therapy thus, leading to early diagnosis and better cure for the patient. One such advance is the development of point-of-care devices, which are rapid chair-side testing methods. These devices are already in use in healthcare services, a common example being home-used pregnancy test strips. This point-of-care technology is now expanding its arms in periodontics as well, thus simplifying diagnosis and improving the therapeutic outcomes of the patient. In light of the above facts, this chapter throws light on periodontal diagnosis and various commercially available point-of-care devices.

1. Introduction

Oral cavity is the home of numerous microorganisms. Exposed to the outer environment, the oral mucosa is under continuous attack from various pathogens. The immune inflammatory response, which arises due to these pathogens, causes inflammation [1].

Periodontitis, the inflammation of periodontium, is one of the leading oral problems affecting the world. And like any other disease, the earlier it is diagnosed, the better is the prognosis [2].

Traditionally, periodontitis has been diagnosed by probing depth, bleeding on probing, or bone loss by radiographs [3, 4]. All these procedures tell us only the destruction caused by the disease till date and reflect only the clinical phenotype and not the biological phenotype. Knowledge about biologic phenotypes helps in assessing the burden of microbial and inflammatory load, which further affects the progression of periodontitis [1].

With advances in sciences, it has become known that diagnostic processes need to reveal much more than just the disease. It needs to help in locating the sites of active disease, susceptibility of the patient to disease, future progression of the disease, long-term maintenance, patient response, and microbial challenge [5, 6, 7].

Point-of-care (POC) testing can be defined as testing performed close to the patient at the time care is required. POC can revolutionize both periodontal diagnostic and therapy. These tests rely on the detection of a plethora of biomarkers of disease activity. These markers present in saliva, gingival crevicular fluid (GCF), plaque, or living tissue are quantifiable and indicate health and disease [8, 9]. This chapter covers all the latest POC diagnostics available (Table 1), which detect markers for periodontal diseases.

S. No.	Oral fluid	Test	Kit
1.	Saliva	Biochemical test	Oral fluid nano sensor test
			Electronic taste chip
			Ora quick
			Integrated microfluidic platform for oral Diagnostics
		Microbiological test	My periopath
			OMNIgene
			IAI pado test
2.	Gingival crevicular fluid	Biochemical test	Periogard
			Pocket watch
			Periocheck
			Prognostic
			MMP dipstick test
3.	Plaque	Microbiological test	Perioscan (BANA)
			Evalusite
			Perio 2000
			TOPAS
			Genetic test kits
4.	Living tissue	Genetic test	MyperioID
			Periodontitis susceptibility trait test

Table 1.

Table showing various available point-of-care devices [10].

2. Point-of-care diagnostics

A good diagnostic marker should always have high specificity and sensitivity [11]. Saliva and GCF are vehicles with great potential to be used in diagnostic tests for various diseases. They are easy to collect and are rich in locally or systemically derived biomarkers of periodontal diseases [10].

2.1 Saliva

Saliva is a bio-fluid that is very useful and easily accessible and can be used to monitor oral and systemic health (Table 2) [8]. Most of the biomarkers found in blood are also present in saliva (Table 3). Moreover, unlike blood, it does not clot or easily spreads infections. However, a disadvantage of saliva is the lower concentration of biomarkers in comparison to serum, thus requires the test to be highly sensitive [12]. Moreover, saliva is also influenced by environmental and psychological factors.

Markers of periodontal soft tissue inflammation	Markers of alveolar bone loss	Collagen breakdown products
Prostaglandin E2	Alkaline phosphatase	Aspartate aminotransferase
β-glucuronidase	Osteoprotegerin	Alanine aminotransferase
IL-1β	Osteocalcin	TIMPs
IL-6	Collagen telopeptidase	MMPs
Tumor necrosis factor-α	Pyridinoline cross-links of type I collagen	α2-macroglobulin
Matrix metalloproteinase (MMP-8,9&13)	RANKL
	Osteonectin

Table 2.

demonstrating the biomarkers present in saliva [10].

Test kits
Oral Fluid Nano Sensor Test	Detection of multiple salivary proteins and nucleic acids.
Electronic Taste Chips	Simultaneously monitor several biomarkers related to periodontal disease
OraQuick	Usually detects HIV 1 and HIV 2
Integrated Microfluidic	Quantification of an oral disease biomarker
Platform for Oral Diagnostics

Table 3.

Commercially available salivary point-of-care diagnostics [10].

2.1.1 Biochemical tests done on saliva

2.1.1.1 Oral fluid nano sensor test (OFNASET)

It is an ultrasensitive and ultraspecific automated electrochemical detection system for salivary proteins and nucleic acids. This test is an oral cancer screening device that is developed by the University of California, Los Angeles (UCLA) collaborative oral fluid diagnostic research laboratory, led by Dr. David Wong [8, 13]. Four salivary mRNA biomarkers (SAT, ODZ, IL-8, and IL-1b) and two salivary proteomic biomarkers (thioredoxin and IL-8) are detected in the system [14].

2.1.1.2 Electronic test chip

This microchip-based detection system is used for measuring analytes (acids, bases, electrolytes, and proteins) in the solution phase. Antigen-antibody reactions take place on the interior surface of microspheres. The microspheres, increase the surface area and thus, makes it more efficient than ELISA, where the reactions take place on a single layer on the bottom of the well [15].

2.1.1.3 OraQuick

It is the first FDA-approved oral swab in-home test for HIV-1 and HIV-2. It is a stick-like device with a fabric swab and provides results within 20 minutes [14].

2.1.1.4 Integrated microfluidic platform for oral diagnostics (IMPOD)

This kit rapidly measures MMP-8 a biomarker for detection of periodontal disease in saliva and other biomarkers by electrophoretic immunoassay [14].

2.1.2 Microbiological tests done on saliva

2.1.2.1 My periopath

My periopath is a commercially available POC device produced by oral DNA labs. It detects the pathogens causing periodontal disease in saliva samples. This test uses DNA polymerase chain reaction to detect the type and concentration of bacteria present in the salivary samples [16].

2.1.2.2 OMNIgene

This kit provides results in a short period and also these results can be mailed or faxed to the clinician. It can identify pathogens by either DNA probe or RNA probe. By DNA probes, it identifies Porphyromonas gingivalis, Prevotella intermedia, Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum, Eikenella corrodens, Campylobacter rectus, Bacteroides forsythus, and Treponema denticola [17]. By RNA probe, it identifies Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Treponema forsythia, and Treponema denticola [16].OMNIgene-ORAL is a commercial POC device produced by DNA Genotek company.

2.2 Gingival crevicular fluid (GCF)

GCF is a body fluid derived from serum, leukocytes, and cells of periodontium and oral microflora [18]. Its composition is influenced by both external environment and body physiology [19]. Therefore, GCF contains a variety of potential markers derived from the host and bacteria from supragingival and subgingival plaque (Table 4). These biomarkers can be categorized as (i) inflammatory and immune products, (ii) bacterial enzymes, (iii) host-derived enzymes, (iv) tissue breakdown products, and (v) bone-specific proteins.

Inflammatory and immune products	Bacterial proteases	Host-derived enzymes	Tissue breakdown products	Bone-specific proteins
Prostaglandin E2 (PGE2)	Alkaline phosphatase	Alkaline phosphatase	Glycosaminoglycan	Pyridinium crosslink urine pyridinoline
Cytokines	Aminopeptidases	β-Glucuronidase	Hyaluronic acid	Pyridinium crosslink collagen peptide fragment
Antibacterial antibodies	Chondroitin sulfatase	Elastase	Chondroitin-4-sulfate	Tartrate-resistant acid phosphatase
Acute-phase proteins	Collagenase	Cathepsins	Chondroitin-6-sulfate	Hydroxyproline
Complement	Fibrinolysin	Serine proteinase (G)	Dermatan sulfate	Galactosyl hydroxylysine
Vasoactive intestinal peptide	Glucosidases	Nonspecific neutral proteinases	Hydroxyproline	Glycosaminoglycans
Neurokinin a	Hemolysin	Matrix metalloproteinase-l,3,8,13	Fibronectin fragments	Osteonectin and bone phosphoprotein
Neopterin	Hyaluronidase	Aspartate amino transferase	Connective tissue and bone proteins	osteocalcin
Platelet-activating factor	Phospholipase	Myeloperoxidases	Type I collagen peptides
	Hydroxyproline	Lactate dehydrogenase	polypeptide growth factor

Table 4.

Biomarkers in gingival crevicular fluid [10].

Test kits	Enzymes
Periogard	AST
Pocket watch	AST
Periocheck	Collagenase (neutral protease)
Prognostik (Dentsply), Biolise	Elastase (serine protease)
MMP dipstick method	MMP

Table 5.

Commercially available kits using GCF for detecting host-derived enzymes [10].

Markers present in dental biofilm
Specific	Nonspecific	Systemic
Immunoglobulins (IgA, IgG and IgM)	Mucins	C-reactive protein
	Lysozyme
	Lactoferrin
	Histatin
	Peroxidase

Table 6.

Biomarkers present in dental biofilm [10].

Test kits	Bacteria and their products
Perioscan (BANA test)	Trypsin like protease
Oral B lab
Evalusite (Kodak)	P.gingivalis, P.intermedia, A.actinomycetemcomitans
Perioscan/ Diamond probe/Probe 2000 system	For volatile sulfur compounds
TOPAS	Bacterial toxins and protease

Table 7.

Other commercially available kits for detecting bacterial protease [10].

The biomarkers in GCF provide information regarding inflammation, loss of bone, patient susceptibility, detection of periodontal disease, prognosis of disease, and onset of disease (Table 5) [20, 21]. The disadvantages of GCF are that it requires multiple samples of individual tooth sites and extreme lab processing [22]. Moreover, the collection of samples is difficult, and easy contamination of GCF can occur [23]. This makes GCF a difficult medium for chair-side diagnosis.

2.2.1 Biochemical tests done on GCF

2.2.1.1 Periogard

It detects aspartate aminotransferase (AST), which is released on cell death due to periodontal diseases (Figure 1) [24]. Thus, periogard can easily locate sites with active disease processes [25]. The only disadvantage is the numerous steps required and difficulty in colour measurement [26].

Figure 1.

Principle of periogard.

2.2.1.2 Pocket watch

Pocket watch also analyzes AST levels but through a different method. AST acts as a catalyst in the exchange of an amino group of cysteine sulfuric acid by α-keto-gluteric acid to produce β-sulfinyl pyruvate in the presence of pyridoxal phosphate. Inorganic sulfite is released by the spontaneous decomposition of glutamate β-sulfinyl pyruvate. These sulfite ions produced react with malachite green to convert it into a colorless form, thereby showing the pink-colored rhodamine B dye. Thus, the rate of conversion assesses the AST concentration [27].

2.2.1.3 Periocheck

It detects neutral proteases in GCF, such as elastases, proteinases, and collagenases, and is a FDA-approved rapid chair-side test (Figure 2) [28].

Figure 2.

Principle of periocheck.

2.2.1.4 Prognostik

It was developed in 1993 and helped in identifying active sites by measuring elevated MMP (Figure 3). MMPs are host-derived proteinases, which play a major role in periodontitis and dental peri-implant health and disease. MMPs, such as elastases, are released by the lysosomes of polymorphonuclear leukocytes [29].

Figure 3.

Principle of prognostik.

2.2.1.5 MMP dipstick

MMP dipstick detects MMP-8, which differentiates sites having healthy gingiva, gingivitis, and periodontitis [30].

2.2.1.6 Plaque

Numerous studies have detected pathogens in dental plaque causing periodontal diseases (Table 6). Numerous commercially available kits have emerged, which detect these pathogens and help in diagnosis and treatment (Table 7) [10].

2.2.2 Microbial tests done on plaque

2.2.2.1 Perioscan (BANA)

It basically detects trypsin-like proteins, which are produced by various periopathogens, such as P. gingivalis, T. denticola, and T. forsythia (Figure 4) [31]. A major disadvantage of perioscan is that it cannot differentiate among these bacteria. Moreover, it cannot detect non-trypsin-like enzymes, thus limiting the number of pathogens [32].

Figure 4.

Principle of perioscan.

2.2.2.2 Evalusite

This kit uses membrane-based enzyme immunoassay and can detect A. actinomycetemcomitans, P. gingivalis, and P. intermedia (Figure 5). The major limitation is the ability to detect only these three pathogens. Moreover, the detection is done by assessing the change in color, which is always subjective and varies from person to person [24].

Figure 5.

Principle of evalusite.

2.2.2.3 Perio 2000

Similar to perioscan, this kit detects P. gingivali, P. intermedia, and T. forsythia. It measures volatile sulfide compounds (VSCs), which are produced by bacteria after degrading the serum proteins (cysteine and methionine), and displays it digitally. The main advantage is that there is no need to collect GCF as the probe tip can be inserted directly into the gingival sulcus.

2.2.2.4 Toxicity prescreening assay (TOPAS)

It directly detects bacterial toxins and bacterial proteins in GCF. Thus, it is able to locate active disease sites. It is a chair-side test kit that shows results by changing color intensity according to toxin concentration in the GCF [33].

2.2.3 Genetic tests

2.2.3.1 MyperioID

MyperioID does not identify any pathogens, but basically provides genetic susceptibility of the patient to periodontal diseases [16].

2.2.3.2 Periodontitis susceptibility trait test

The periodontitis susceptibility trait test (PST) is the test that identifies the genetic predisposition of the patient for periodontitis. It detects polymorphism in IL-1 gene, which has been linked with periodontal diseases [17].

2.3 Diagnostics-lab-on-chip

Lab-on-chip is a newer generation of POC technology still undergoing development [14]. It basically integrates and automates all the complexities of a laboratory procedure onto a computer chip [28]. This technology will thus measure multiple biomarkers in a small sample of plaque, GCF, or saliva [13, 16]. It will omit all the requirements of heavy expensive equipment or trained lab technicians. The result will be chair-side, instant, and not subjective.

3. Advantages of POC

It increases patient cooperation as no blood is drawn from the patient. Cost and inventory for shipping samples to a centralized laboratory are reduced. Large populations can be screened. Treatment can be started immediately as results are obtained rapidly. It requires lesser training and resources than current diagnostic methods. Patients with higher risk can be recognized and treated.

4. Disadvantages of POC

The use of POC diagnostics in periodontal surveillance looks promising; however, in the clinical setting, these approaches suffer from various obstacles. These tests still need validation and acceptance by dentists. Cost-effectiveness of the procedure and kit is another concern. Finally, the clinician needs to be abreast with the knowledge of diagnosis, disease risks, and prevention before diagnostics may be integrated into routine clinical periodontal practice.

5. Conclusion

The cornerstone for a successful periodontal treatment is an accurate initial diagnosis. The current existing diagnostic methods suffice the purpose but cannot achieve any more goals than this. Knowledge of patient susceptibility and active disease sites are desired by any clinician from the diagnostic methods. With the introduction of new chair-side test kits, which use the host and bacterial markers of periodontal disease, monitoring of specific sites is now possible. The various oral fluids easily available for test are under great amount of research and investigation. Though with various challenges, saliva, GCF, and plaque are promising mediums to be used for periodontal diseases. One of the latest clinical applications of POCT is in the detection of the SARS-CoV-2 virus. Although SARS-CoV-2 RNA detection in nasopharyngeal swabs is reported to be the gold standard method but it is an invasive method, and therefore uncomfortable for the patient. Due to the limitations of this method, saliva is now suggested to be a better alternative because it is easy to collect the sample and is not uncomfortable for the patient [34]. SpeciMAX is the commercially available saliva collection kit for the detection of SARS-CoV-2 virus.

The need of an hour is to develop POC devices for diseases, such as cancer and hyperthyroidism, so that these can be detected with the help of biomarkers at home leading to their early diagnosis and effective intervention at right time.