Dental Calculus and Periodontal Health: Evidence Review

Introduction

Maintaining periodontal health is important for a number of reasons. Left untreated, periodontitis has been shown to produce a wide range of adverse health outcomes, including increased incidences of cardiovascular disease, stroke, diabetes mellitus, and low birth weight in preterm infants. Termed the "silent killer" dental disease by some authorities, periodontitis is an insidious condition that can affect people largely without their knowledge for many years without exhibiting any discernible symptoms. Likewise, the accumulation of dental calculus that is typically associated with the aging process can advance for years without discernible symptoms beyond the appearance issues such accumulation presents.

It has been shown, however, that periodontal health can be established and maintained without the removal of dental calculus. Therefore, because healthcare resources are by definition scarce, it is important to ensure that the removal of calculus is predicated on sound, evidence-based care guidelines. To this end, this paper provides a review of the relevant peer-reviewed and scholarly literature concerning periodontal health, calculus (supragingival and subgingival), and the implications of the removal of dental calculus. A summary of the research and important findings is presented in the conclusion.

Definition of Periodontal Health

Generally speaking, the term "periodontal disease" is used to describe the production of harmful factors and bacterial growth that, over time, attack the tissue surrounding and supporting the teeth; the term "periodontal" itself refers to "around the tooth" (Lewis 2002:16). The disease process starts with the formation of plaque, a process that is ongoing and largely indiscernible (Lewis 2002). According to Lewis, "When it accumulates to excessive levels, it can harden into a substance called tartar (calculus) in as little as 24 hours" (Lewis 2002:16). Calculus is particularly difficult to remove because it is tightly bound to teeth and can only be removed by professional cleaning (Lewis 2002). Both gingivitis and periodontitis represent the two primary forms of gum disease, with each condition being characterized by processes that take place under the gumline (Lewis 2002). While gingivitis typically occurs prior to the onset of periodontitis, not all cases of gingivitis progress to periodontitis (Lewis 2002). Beginning in the 1960s, the most popular measure of periodontal health was based on variance in periodontal index (PI) scores, and this measure remains an important indicator today (Cheraskin 2003).

The general definition provided by the World Health Organization indicates that periodontal health is "a state of being free from chronic mouth and facial pain, oral and throat cancer, oral sores, birth defects such as cleft lip and palate, periodontal (gum) disease, tooth decay and tooth loss, and other diseases and disorders that affect the oral cavity" ("Oral health" 2010:1). Other indicators of periodontal health — at least in animals — also include the amount of plaque and calculus, changes in the gingiva, probing depth, evaluation of attachment, and grade of mobility ("Periodontal indices" 2007). While plaque is the primary cause of periodontal disease, the American Academy of Periodontology (AAP) notes that other factors are thought to increase the risk, severity, and speed of gum disease development, including the following:

According to Zacharczenko, "Periodontitis is the 'silent killer' dental disease. It can progress for years without symptoms. It is estimated that the majority of middle-aged and elderly Americans have some degree of this disease" (1998:56). Left untreated, ongoing periodontitis has been linked with diabetes mellitus, cardiovascular disease, stroke, infective endocarditis, and low birth weight in preterm babies (Zacharczenko 1998). The research to date also indicates that some people are predisposed to periodontal disease; although the precise reasons remain unclear, it is thought that genetics, diet, lifestyle, and oral hygiene all play a role to varying degrees, but the extent of oral cleanliness has not been demonstrated to be predictive of gum disease (Zacharczenko 1998).

Other recent research has shown that immune defenses in the human body mediate the extent and severity of the bone destruction that results from bacterial growth in the periodontium. Preferred treatments for periodontal disease typically involve dental scaling and root planing, various surgeries, and aggressive home care regimens (Zacharczenko 1998). The goal of these interventions is to reduce the amount of plaque, pockets of gum disease, and calculus surrounding the involved teeth. However, Zacharczenko emphasizes that "The inflammatory components responsible for the decimation of dental alveolar bone have never been adequately addressed. These components include collagenase, prostaglandins, and other mediators that induce bone loss" (Zacharczenko 1998:56).

Definition and Types of Dental Calculus

A helpful description of calculus is provided by Hopkins, who reports: "With aging the teeth become both longer and looser, a condition that really has its beginning some time earlier when a colorless film of sticky, bacterially produced material called plaque forms on the tooth surfaces without the owner's knowledge and — in time — turns into deposits of tartar, or calculus" (1994:31). The potential consequences of calculus accumulation are also noted by Hopkins: "As the stuff forms, it crowds, irritates, loosens and eventually pushes back the gumline. Inflammation and infection set in around the tooth's root, and the gum slowly recedes" (1994:31). Over time, this process can cause teeth to become looser, opening the way for other conditions that adversely affect periodontal health. Hopkins concludes that "As the infected area widens and deepens, the bone in which the tooth is set shrinks away. This makes the tooth's pocket deeper and gives the roots less anchorage. Sometimes it is years before the patient really knows what is happening" (1994:31).

How far the disease process has progressed largely dictates what type of methods and procedures are used to treat periodontitis. In cases where the condition is treated at an early stage, scaling and root planing may be sufficient (Hopkins 1994). Calculus accumulations are usually removed with various scraping instruments or machine-driven buffing pads; in other cases, ultrasonic vibration is used to remove calculus deposits (Hopkins 1994). According to Hopkins, "Removal of calculus below the gumline and root planing are usually done by a dentist or periodontist. Root planing consists of removing plaque and calculus from the root to provide a smooth surface to which the gum may reattach" (1994:31).

There remains a paucity of knowledge among the general public — and among adolescents in particular — concerning plaque and calculus. A study by Yuen, Wiegand, Slate, Magruder, Salinas, and London (2008) investigated the level of dental health knowledge among adolescents and found that this lack of knowledge did not appear to be a contributing factor to higher prevalence rates of periodontal disease. According to these researchers, "Some confusion may have no detrimental impact on the dental health of the adolescents. For example, not fully understanding the difference between plaque and calculus, and the functions of dental sealant and fluoride, may not necessarily contribute to poor dental health as long as a proper daily oral hygiene routine with fluoridated toothpaste is maintained" (Yuen et al. 2008:15).

As the term implies, supragingival calculus refers to calculus located above the gumline ("Calculus removal" 2010). Supragingival calculus is not regarded as a direct cause of periodontal disease; in addition, there has been a decrease in prevalence levels in recent years due in part to reduced tobacco use, improvements in oral cleanliness, and the increased use of anti-tartar and therapeutic toothpastes (Sheiham 2001). Nevertheless, an individual may prefer to have this type of calculus removed for aesthetic reasons or as part of a long-term treatment regimen. For example, Bennett and McCrohan note that when the American Dental Association approved Warner-Lambert's mouthwash Listerine by stating that it "has been shown to help prevent and reduce supragingival plaque accumulation and gingivitis," sales rose significantly (1993:398).

It remains unclear what effect, if any, supragingival calculus has on gingival inflammation. Mandel and Gaffar report that "Although there is no doubt that gingivitis can develop in the absence of supragingival calculus, it is not clear to what extent the presence of mineralized deposit enhances gingival inflammation" (1986:249). Although the composition of the material is the same, calculus located below the gumline is termed "subgingival," and this condition is discussed further below.

Because of its location below the gumline, researchers have increasingly focused on treatment modalities that could effectively address subgingival calculus. Clinical studies reported by Cooley and Lewkowicz examined the efficacy of Elyzol dental gel combined with subgingival scaling. These early studies, however, were flawed in several ways and appeared to be biased in favor of using Elyzol gel as an initial treatment or as a replacement for subgingival scaling. According to these researchers, "As the gel is an antibiotic, it is reasonable that the gel should be applied only if the mechanical treatment fails to solve the pocket. Moreover, the study groups in the studies seem to have been poorly defined" (Cooley & Lewkowicz 2003:63). The results of a more recent randomized clinical and microbiological slit-mouth design study (Stelzel & Flores-de-Jacoby 1996) concerning the efficacy of metronidazole 25% dental gel compared to subgingival scaling on recall subjects showed no statistically significant differences between the two treatment modalities. Limitations of this study included a relatively small sample (n=30) and the inclusion of smokers, which may have influenced the outcomes (Cooley & Lewkowicz 2003).

According to Zacharczenko (1998), many prescription drugs have also been introduced in recent years to treat periodontal disease and the associated inflammatory response. These products include Peridex (chlorhexidine gluconate, Zila) and Perioguard (chlorhexidine gluconate, Colgate Oral Pharmaceuticals) rinses, as well as over-the-counter alternatives such as Colgate's Total and Viadent Advanced Care toothpastes, designed to treat initial colonization of bacterial growth, plaque accumulations, and gingivitis (Zacharczenko 1998). One such product, PerioChip (chlorhexidine gluconate 2.5 mg, Astra), has been introduced as a treatment for adult periodontal disease (Zacharczenko 1998). The product is described by Zacharczenko as "a biodegradable, subgingival, sustained-release chip, measuring 4mm x 5mm x 350 microns" (1998:56). It is inserted into a periodontal pocket by the treating dentist and degrades over the following seven to ten days, at which point the treatment is complete (Zacharczenko 1998). The active ingredient, chlorhexidine, is a powerful bactericidal agent and has been shown to be highly effective in treating periodontal disease (Zacharczenko 1998). It should be noted, however, that the PerioChip treatment is intended to be part of a more comprehensive treatment regimen and is meant to supplement, not replace, traditional periodontal therapeutic interventions (Zacharczenko 1998).

The focus of a study by Alaluusua et al. (2004) was to determine the effect of dioxins on human organogenesis, including periodontal health in general and the percentage of subgingival calculus sites in particular. Although it was determined that dioxins could affect the organogenesis process in humans, exposure did not affect the number of subgingival calculus sites (Alaluusua et al. 2004:1313).

Conclusion

The research showed that a number of factors contribute to periodontal health, including tobacco use, changes in hormonal levels, stress, medication regimens, nutritional practices, other illnesses, and clenching and grinding teeth. The research also showed that although there is a consensus among healthcare practitioners that periodontal health is important for a variety of reasons, there remains less agreement concerning the need for the removal of sub- and supragingival calculus accumulations. Some authorities indicate that calculus accumulations can lead to more serious periodontal diseases including gingivitis, while others maintain that calculus does not play a major role in the pathogenesis of periodontal diseases and that its removal is clinically unjustified.

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