Models to evaluate the role of stress in periodontal disease

Influence of restraint stress on ligature-induced periodontitis in rats

The influence of stress on periodontal breakdown in Wistar rats was analyzed during experimental periodontitis, induced by placing silk ligatures around the maxillary right second molar teeth. The rats were divided into three groups with 10 animals in each; the first group was exposed to restraint stress for 12 h d(-1) for a period of 4 wk; the second group was exposed to restraint stress for 2.5 h d(-1) for a period of 4 wk; the third group served as a control group. Ligation for 4 wk resulted in an accelerated periodontal degradation, whereas the restraint stress by itself had no significant effect. Combined stress and ligation resulted in a significantly higher attachment loss and alveolar bone resorption than either treatment alone, while no differences were seen between the two stress regimens. After 4 wk, a reduced body weight was found in both restrained groups of rats and a reduced weight of the thymus in the rats restrained for 12 h d(-1), while no changes were observed in the weight or composition of the suprarenal glands. We conclude that stress alone does not result in periodontal disease but may modulate the pathophysiological processes of already present periodontal inflammation, resulting in accelerated degradation of periodontal tissues.

The relationship of some negative events and psychological factors to periodontal disease in an adult Swedish population 50 to 80 years of age

BACKGROUND

Clinical observations and epidemiological studies suggest that experiences of negative life events, especially those manifested as depression, may contribute to an increased susceptibility to periodontal disease.

OBJECTIVE

In the present study, the prevalence of some negative life events and psychological factors and their relation to periodontal disease were investigated. The sample consisted of individuals 50-80 years of age from an extensive cross-sectional epidemiological study performed in 1993 in the city of Jönköping, Sweden.

METHOD

298 dentate individuals from the Jönköping study were randomly selected. Clinical and radiographic examinations included registration of the number of existing teeth, plaque index, gingival index, pocket depth, and alveolar bone loss. In addition, a questionnaire about socioeconomic status, life events, and psychological and stress-related factors was used.

RESULTS

The results revealed that, in addition to the well-documented periodontal disease risk factors such as increased age, oral hygiene status, and smoking, the loss of a spouse (being a widow or widower) and the personality trait of exercising extreme external control were also associated with severe periodontal disease.

CONCLUSION

The findings support recent studies suggesting that traumatic life events such as the loss of a spouse may increase the risk for periodontal disease. Above all, the present results indicate that an individual's ability to cope with stressful stimuli (coping behavior), as measured by the beliefs of locus of control of reinforcements may play a role in the progression of periodontal disease.

Postnatal glutamate-induced central nervous system lesions alter periodontal disease susceptibility in adult Wistar rats

BACKGROUND

Inability to mount a suitable brain-neuroendocrine response to bacterial or other antigenic challenges has been found to play an important rôle in infectious and inflammatory disease susceptibility and progression, including periodontal disease.

OBJECTIVE

The present study was designed to determine the effects of glutamate administration to new-born Wistar rats on the development and progression of naturally occurring and ligature-induced periodontal disease in the rats as adults. Postnatal glutamate administration is known to permanently damage neurones in the hypothalamic arcuate nucleus.

METHOD

New-born rats were treated 1x daily subcutaneously with 2 mg/g of monosodium-L-glutamate (MSG) for 5 days from day 3 to 6. Control animals were injected with similar amounts of saline. Experimental ligature-induced periodontal disease was induced in the rats at the age of 12 weeks at maxillary right 2nd molar teeth. The contralateral maxillary left 2nd molars served as control teeth, and for assessment of naturally occurring periodontal disease. Disease progression was evaluated histometrically.

RESULTS

The results revealed that the glutamate-lesioned rats developed significantly more periodontal tissue destruction compared to sham-lesioned control rats in both the ligated and non-ligated teeth.

CONCLUSIONS

This study supports our recent findings indicating that inappropriate brain-neuroendocrine-immune regulation may play a rôle in periodontal disease susceptibility and progression.

[Relationship between periodontitis and lifestyle and health status]

The purpose of this study is to clarify the relationship between periodontitis and lifestyle and health status. The subjects were 349 male workers aged on 40s and 50s, who had been working on the development and manufacture of computers. Multiple logistic regression analysis showed that the existence of periodontitis was associated positively with age, the Brinkman index, systolic blood pressure, number of white blood cells, feeling of irritation, and negatively with the use of interdental cleaners. It is therefore important to practice more active oral health promotion in cooperation with the medical staff concerned, as a part of THP (Total Health Promotion) in the workplace.

Calcium and the risk for periodontal disease

BACKGROUND

Dietary calcium has long been a candidate to modulate periodontal disease. Animal as well as human studies of calcium intake, bone mineral density, and tooth loss provide a rationale for hypothesizing that low dietary intake of calcium is a risk factor for periodontal disease.

METHODS

We evaluated the role of dietary calcium intake as a contributing risk factor for periodontal disease utilizing the Third National Health and Nutrition Examination Survey (NHANES III), which is representative of the U.S. civilian non-institutionalized population. Dietary calcium intake was determined from a 24-hour dietary recall. The U.S. Department of Agriculture Nutrient Database was used as a source of nutrient composition data. Periodontal disease was measured by attachment loss. In addition, serum calcium was assessed using venous blood samples. Logistic regression analysis was used to examine the association between periodontal disease and dietary calcium intake or serum calcium levels after adjusting for covariants including age, gender, tobacco consumption, and gingival bleeding.

RESULTS

The association of lower dietary calcium intake with periodontal disease was found for young males and females (20 to 39 years of age), and for older males (40 to 59 years of age). The relationship between low dietary calcium intake and increased levels of periodontal disease showed an estimated odds ratio (OR) of 1.84 (95% CI: 1.36 to 2.48) for young males, 1.99 (95% CI: 1.34 to 2.97) for young females, and 1.90 (95% CI: 1.41 to 2.55) for the older group of males. These odds ratios were adjusted for gingival bleeding and tobacco consumption. The dose response was also seen in females, where there was 54% greater risk of periodontal disease for the lowest level of dietary calcium intake (2 to 499 mg) and 27% greater risk in females who took moderate levels of dietary calcium (500 to 799 mg) as compared to those who took 800 mg or more dietary calcium per day. A statistically significant association between low total serum calcium and periodontal disease was found in younger females aged 20 to 39 with OR = 6.11 (95% CI: 2.36 to 15.84) but not for males or older females, after adjusting for tobacco use, gingival bleeding, and dietary calcium intake.

CONCLUSIONS

These results suggest that low dietary intake of calcium results in more severe periodontal disease. Further studies will be needed to better define the role of calcium in periodontal disease and to determine the extent to which calcium supplementation will modulate periodontal disease and tooth loss.

Prevaccination with SRL172 (heat-killed Mycobacterium vaccae) inhibits experimental periodontal disease in Wistar rats

Periodontal disease is a bacterial dental plaque-induced destructive inflammatory condition of the tooth-supporting tissues, which is thought to be mediated by T lymphocytes secreting T helper 2 (Th2) cytokines, resulting in recruitment of high numbers of antibody-producing B lymphocytes/plasma cells as well as polymorphonuclear leucocytes (PMN) secreting tissue-destructive components, such at matrix metalloproteinases and reactive oxygen metabolites into the gingival connective tissues. One treatment strategy may be to down-regulate the Th2 response to those dental plaque microorganisms which induce the destructive inflammatory response. In this study we have examined the effects of a potent down-regulator of Th2 responses on ligature-induced periodontal disease in an experimental rat model. A single s.c. injection into Wistar rats of 0.1 or 1 mg of SRL172, a preparation of heat-killed Mycobacterium vaccae (NCTC 11659), 13 days before application of the ligature, significantly reduced the subsequent destruction of the tooth-supporting tissues, as measured by loss of periodontal attachment fibres (P < 0.001) and bone (P < 0.002). This protective effect occurred not only on the experimental (ligatured) side but also on the control unligatured side. SRL172 has undergone extensive toxicological studies and safety assessments in humans, and it is suggested that it may provide a safe and novel therapeutic approach to periodontal disease.

Periodontitis modified by systemic factors

Microbial dental plaque is the initiator of periodontal disease but whether it affects a particular subject, what form the disease takes, and how it progresses, are all dependent on the host defenses to this challenge. Systemic factors modify all forms periodontitis principally through their effects on the normal immune and inflammatory defenses. Some good examples of this effect exist such as when there is a reduction in number or function of polymorphonuclear leukocytes (PMNs) that may result in an increased rate and severity of periodontal destruction. Many other systemic factors are much less clear cut and are difficult to causally link to periodontitis. In many cases the literature is insufficient to make definite statements on links between systemic factors and periodontitis. It is also at times difficult to be precise regarding the causative agent in systemic exposures such as smoking and even prescribed drug therapy. The possible role of systemic diseases and systemic exposures in initiating or modifying the progress of periodontal disease is clearly a complex issue. It is however generally agreed that several conditions may give rise to an increased prevalence, incidence, or severity of gingivitis and periodontitis. The categorization of the systemic modifying factors causing periodontitis and the evidence to support the role of these factors are the focus of this review. An attempt has been made to consider the conditions under broad headings, but it will be clear that many conditions fall within more than one category and that for several conditions only case reports exist whereas in other areas an extensive literature is present.

Potential adjunctive applications of hypnosis in the management of periodontal diseases

Many uses of hypnosis in dentistry have been described in the literature including anesthesia, analgesia, anxiety management, treatment for bruxism, to control gagging, and the alteration of salivary flow and bleeding control during treatment. However, very few references have been made specifically regarding the use of hypnosis with patients who have periodontal disease, a wide spread chronic inflammatory disease affecting the oral cavity of about 80% of the population. The purpose of this paper is to describe potential adjunctive applications of hypnosis in the treatment of patients with periodontal diseases. The supporting literature from two broad areas for potential application, health behaviors and psychoneuroimmunology is discussed, followed by proposed hypnotic strategies and suggestions for use with patients with periodontal diseases.

The pathobiology of periodontal diseases may affect systemic diseases: inversion of a paradigm

A new paradigm for the pathobiology of periodontitis is presented, and the manner in which periodontitis may relate to susceptibility for certain systemic diseases such as cardiovascular disease and preterm labor is described. Periodontitis is caused by a small group of Gram-negative bacteria present on the tooth root surfaces as bioffilms. Lipopolysaccharide (LPS) and other substances gain access to the gingival tissues, initiate and perpetuate immunoinflammation, resulting in production of high levels of proinflammatory cytokines. These induce production of matrix metalloproteinases which destroy the connective tissues of the gingiva and periodontal ligament, and prostaglandins which mediate alveolar bone destruction. Periodontitis may enhance susceptibility to systemic diseases in several ways. LPS and viable Gram-negative bacteria from the biofilms and proinflammatory cytokines from the inflamed periodontal tissues may enter the circulation in pathogenic quantities. In addition, periodontitis and certain systemic diseases, such as cardiovascular disease, share risk factors including tobacco smoking, male gender, race/ethnicity, stress, and aging.