Bacteroides gingivalis antigens and bone resorbing activity in root surface fractions of periodontally involved teeth

Inhibitory Effect of a Novel Bisphosphonate, TRK-530, on Dental Calculus Formation in Rats

BACKGROUND

A newly developed bisphosphonate, TRK-530 (disodium dihydrogen[4-(methylthio)phenylthio]methanebisphosphonate), has recently been reported to show anti-inflammatory and anti-bone-resorbing activity. Since bisphosphonates have been shown to inhibit the formation of calcium-phosphate crystals in vitro, TRK-530 may inhibit the formation of dental calculus. Therefore, the present study was performed to examine whether this compound has such an effect.

METHODS

Three groups of Wistar rats fed a calculogenic diet (RC16) were treated with TRK-530 in drinking water at concentrations of 0 (control group), 0.75, and 1.5 mM. Another group received a daily subcutaneous injection of TRK-530 at a dose of 2.25 micromoles/rat, which was assumed to correspond to the maximum amount of this compound absorbed from the intestine when rats received 1.5 mM TRK-530 in drinking water. Rat dental calculus formation was evaluated. The crystalline nature of dental calculus was studied by x-ray diffraction analysis. Finally, the effects of TRK-530 on the precipitation of calcium-phosphate from solution were tested in vitro.

RESULTS

TRK-530 in drinking water inhibited dental calculus formation dose-dependently. However, subcutaneous injection of TRK-530 did not have any significant effect, suggesting that the anticalculus effect of TRK-530 in drinking water was topical, not systemic. The calculus that formed in both the control and experimental groups was primarily hydroxyapatite, a main constituent of human dental calculus. TRK-530 inhibited the precipitation of calcium-phosphate from solution in vitro.

CONCLUSIONS

TRK-530 inhibited the formation of dental calculus in a dose-dependent fashion via a local effect. Inhibition of the precipitation of calcium-phosphate from solution might be involved in the anticalculogenic mechanism of this drug.

Tetracycline Conditioning Augments the In Vivo Inflammatory Response Induced by Cementum Extracts

BACKGROUND

Studies have shown that extracts of cementum from periodontally involved teeth stimulated cytokine secretion from cultured human monocytes and that this stimulatory effect is inhibited by conditioning of the cementum with tetracycline. Using the subcutaneous chamber model in mice, the present study was designed to test the ability of cementum extracts from periodontally diseased teeth to induce an inflammatory response in vivo and to evaluate the effect of cementum conditioning with tetracycline.

METHODS

Subcutaneous chambers were implanted in 24 mice. Two weeks later, the animals received intrachamber injection of one of the following: diseased-cementum extract, healthy-cementum extract, diseased-cementum extract preconditioned with tetracycline, or medium alone. Chamber exudates were harvested and analyzed for leukocyte levels, tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma, and interleukin-10 (IL-10).

RESULTS

Injection of healthy- or diseased-cementum extracts increased the intrachamber levels of leukocytes. Extracts of diseased cementum were found to significantly increase the levels of TNF-alpha, IFN-gamma, and IL-10, compared with extracts of healthy cementum or media alone. Peak cytokine levels were observed 2 hours postinjection. Conditioning of diseased cementum with tetracycline before extraction resulted in augmented levels of TNF-alpha and IFN-gamma, and reduced levels of IL-10, compared with untreated diseased cementum.

CONCLUSIONS

The present results demonstrate that conditioning of diseased cementum with tetracycline may induce an intense inflammatory response in a mouse model, and they suggest that local application of tetracycline for root conditioning should be carefully reinvestigated.

Study of Bacterial Viability within Human Supragingival Dental Calculus

BACKGROUND

There is evidence that supragingival calculus contains unmineralized channels and lacunae. The purpose of this study was to investigate the viability of bacteria within these areas.

METHODS

Supragingival calculus harvested from patients with moderate to severe chronic periodontitis was immediately frozen to -70 degrees C. Six samples were cryosectioned, stained with a bacterial viability kit, and examined with fluorescence microscopy. Controls comprised heat treatment of cryosections prior to staining. Four additional samples were stained and examined whole in a confocal laser scanning microscope (CLSM). Nine additional samples were prepared for bacterial culture, after initial irradiation with ultraviolet light to kill viable organisms on the covering plaque layer. Test samples were crushed to expose internal bacteria, while two controls were used without crushing.

RESULTS

Viable bacteria, as identified using the bacterial viability stain, were found within cavities/lacunae in supragingival calculus cryosections. Similar results were obtained from whole calculus samples using CLSM. Of the nine experimental samples where bacterial culture was attempted, five provided positive bacterial culture under both aerobic and anaerobic conditions; one showed positive growth under aerobic conditions only; while one showed no bacterial growth. The controls showed no bacterial growth.

CONCLUSIONS

From this study, it appears that viable aerobic and anaerobic bacteria may be present within supragingival calculus, specifically within the internal channels and lacunae. Clinically, this may be important, since incomplete removal of supragingival calculus may expose these reservoirs of possible pathogenic bacteria and be a factor in the recurrence of periodontal diseases after treatment.

Dental calculus: recent insights into occurrence, formation, prevention, removal and oral health effects of supragingival and subgingival deposits

Dental calculus, both supra- and subgingival occurs in the majority of adults worldwide. Dental calculus is calcified dental plaque, composed primarily of calcium phosphate mineral salts deposited between and within remnants of formerly viable microorganisms. A viable dental plaque covers mineralized calculus deposits. Levels of calculus and location of formation are population specific and are affected by oral hygiene habits, access to professional care, diet, age, ethnic origin, time since last dental cleaning, systemic disease and the use of prescription medications. In populations that practice regular oral hygiene and with access to regular professional care, supragingival dental calculus formation is restricted to tooth surfaces adjacent to the salivary ducts. Levels of supragingival calculus in these populations is minor and the calculus has little if any impact on oral-health. Subgingival calculus formation in these populations occurs coincident with periodontal disease (although the calculus itself appears to have little impact on attachment loss), the latter being correlated with dental plaque. In populations that do not practice regular hygiene and that do not have access to professional care, supragingival calculus occurs throughout the dentition and the extent of calculus formation can be extreme. In these populations, supragingival calculus is associated with the promotion of gingival recession. Subgingival calculus, in "low hygiene" populations, is extensive and is directly correlated with enhanced periodontal attachment loss. Despite extensive research, a complete understanding of the etiologic significance of subgingival calculus to periodontal disease remains elusive, due to inability to clearly differentiate effects of calculus versus "plaque on calculus". As a result, we are not entirely sure whether subgingival calculus is the cause or result of periodontal inflammation. Research suggests that subgingival calculus, at a minimum, may expand the radius of plaque induced periodontal injury. Removal of subgingival plaque and calculus remains the cornerstone of periodontal therapy. Calculus formation is the result of petrification of dental plaque biofilm, with mineral ions provided by bathing saliva or crevicular fluids. Supragingival calculus formation can be controlled by chemical mineralization inhibitors, applied in toothpastes or mouthrinses. These agents act to delay plaque calcification, keeping deposits in an amorphous non-hardened state to facilitate removal with regular hygiene. Clinical efficacy for these agents is typically assessed as the reduction in tartar area coverage on the teeth between dental cleaning. Research shows that topically applied mineralization inhibitors can also influence adhesion and hardness of calculus deposits on the tooth surface, facilitating removal. Future research in calculus may include the development of improved supragingival tartar control formulations, the development of treatments for the prevention of subgingival calculus formation, the development of improved methods for root detoxification and debridement and the development and application of sensitive diagnostic methods to assess subgingival debridement efficacy.

Periodontal pocket treatment in beagle dogs using subgingival doxycycline from a biodegradable system. I. Initial clinical responses

The present study evaluated the clinical response of periodontal pockets in beagle dogs after treatment with a biodegradable delivery system containing 10% doxycycline hyclate (ABDS-D). Eight adult, female beagle dogs had generalized, severe periodontitis with plaque and calculus-laden pockets. In each animal, 3 teeth with multiple pocket sites > or = 4 mm (mean depth = 6.0 mm) associated with attachment loss (mean = 5.4 mm) and which bled on probing (mean score = 2.5) were treated with a single application of either ABDS-D (experimental group) or the delivery system alone without the doxycycline (control group). Residual polymer was removed at day 7. Bioassay of doxycycline in gingival crevicular fluid associated with presence of ABDS-D gave mean levels of bioactivity of approximately 250 micrograms/ml. Levels of bioactive doxycycline were detected for approximately 7 days after ABDS-D removal. Periodontal maintenance consisted of thrice-weekly toothbrushing the treated sites. Clinical responses were evaluated at 2 weeks, and at bi-weekly intervals thereafter for 4 months. Analyses of the data from the control group showed that there was only slight clinical improvement. In contrast, in the experimental group, bleeding on probing and probing depths were significantly reduced from baseline at all post-treatment time points. At 1 month, mean probing depth reduction was 2.4 mm and this was maintained at 4 months (mean reduction = 2.5 mm). These probing depth reductions occurred primarily through gain of clinical attachment which was 2.0 mm at 4 months. Bleeding had been virtually eliminated (mean = 0.2). It was concluded that, for the beagle dogs with severely infected periodontal pockets in this study, treatment with subgingival doxycycline using the delivery system resulted in substantial improvement in periodontal health.

Human monocyte response to cementum extracts from periodontally diseased teeth: effect of conditioning with tetracycline

Monocyte inflammatory cytokines, such as TNF alpha and IL-1 beta, have been implicated in the pathogenesis of periodontal destruction. The present study was designed to test the ability of extracts of cementum from periodontally diseased teeth to induce the secretion of these mediators by monocytes, to evaluate the role of adsorbed endotoxin in this process, and to test the effect of cementum conditioning with tetracycline on the monocyte response. Human monocytes were incubated with varying concentrations of cementum extracts, and TNF alpha and IL-1 beta levels in the media were measured. The results showed that while extracts of healthy cementum had no effect on monocyte secretion, concentration as low as 0.5 mg/ml of cementum from diseased sites raised the levels of TNF alpha and IL-1 beta secretion 10-fold. This response was dose-dependent. Diseased cementum were found to contain 1.5 ng/mg endotoxin, while endotoxin was not detectable in the extracts of the healthy cementum. However, neutralization of the endotoxin by polymyxin B only partially reduced the monocyte secretory response by 50 to 70%, suggesting that other factors in the extracts are also involved in monocyte stimulation. To simulate the effect of root conditioning, cementum was first agitated in a tetracycline or control solution prior to its extraction in media. Pretreatment of diseased cementum with tetracycline (50 mg/ml) was found to block the secretion of TNF alpha from cementum-stimulated monocytes. Pretreatment of the diseased cementum with 10 mg/ml tetracycline was not more effective than saline and HCI controls, with all treatments reducing cytokine secretion by approximately 80%. The direct addition of tetracycline to cementum-stimulated monocyte culture was found to block TNF alpha secretion in a dose dependent manner. The results suggest that extracts from diseased cementum are potent stimulators of monocyte secretion, and that endotoxin as well as other factor(s) appear to be involved. These factors are partially extracted by washing and a 10 mg/ml tetracycline solution is not more effective than saline in achieving this goal. In addition, tetracycline was found to be a potent inhibitor of TNF alpha secretion by cementum-stimulated monocytes, suggesting a novel mechanism for this drug in periodontal therapy.

Calculus update: prevalence, pathogenicity and prevention

Does reduction of supragingival calculus provide only a cosmetic effect, or does it benefit oral health as well? The author discusses the causes and effects of calculus development and reviews methods of calculus control.

Relationship of gingival calculus and bleeding on probing in CPITN code 2 sextants

The aims of this study were twofold: firstly, to evaluate the relationship of supra- or subgingival calculus and bleeding on probing (BOP) in sextants coded 2 in the Community Periodontal Index of Treatment Needs (CPITN); and secondly, to compare the differences in four investigations in Taiwan, Hong Kong, Japan and Norway. In a national survey, a total of 2658 Chinese dentate adults were examined by using modified CPITN in the Taiwan area from 1985 to 1987. Sextants given Code 2 were divided into four subclassifications: supragingival calculus with bleeding (I+), supragingival calculus without bleeding (I-), subgingival calculus with bleeding (II+) and subgingival calculus without bleeding (II-). The results showed that of the 9394 sextants given Code 2, the highest percentage (70%) were characterized by the presence of subgingival calculus with bleeding and the lowest percentage (4%) by supragingival calculus with bleeding. The ratio of sextants coded 2 with only supragingival calculus versus subgingival was 1:6.2. The bleeding to nonbleeding ratio of sextants coded 2 in this study was similar to the Hong Kong study. However, differences among Taiwan, Japan and Norway were found. The results indicated that sextants with subgingival calculus had a higher tendency to BOP, with a ratio of 4:1. Those with supragingival calculus had a ratio of 3:7. We conclude therefore, that it is essential to scale teeth to remove subgingival calculus for determination of the necessity of periodontal treatment.

Radiographic detection of dental calculus

To determine the sensitivity and specificity of the radiographic detection of calculus, 275 proximal tooth surfaces from 18 patients were evaluated. Standardized periapical radiographs obtained before extraction were coded, batch processed, and evaluated independently by two investigators under optimum viewing conditions. After extraction, the teeth were photographed and evaluated both microscopically and by planimetry on 40 X linear projections. Evaluation of calculus by conventional radiography showed low sensitivity: radiographic deposits were detected on only 44% of surfaces that demonstrated calculus microscopically. Specificity was high and the rate of false positives was only 7.5%. Detection of calculus was influenced by the thickness of calculus, the percentage of root surface occupied by calculus, and by tooth type; but not by attachment loss, probing depth, proximal surface, or arch location. These results show that present radiographic techniques are not appropriate for detecting calculus on root surfaces.

Calculus removal by scaling/root planing with and without surgical access

We assessed the presence and extent of calculus on subgingival root surfaces of teeth that received scaling and root planing (S/RP) alone, S/RP with modified Widman flap, or no treatment. After extraction, each surface was examined to determine the pocket depth (PD), area of root surface exposed to the pocket (A), and amount of pocket area showing retained calculus (C). Calculus-positive teeth (CPT) and surfaces (CPS) and percentage of pocket area occupied by calculus (C/A) were derived for each group. In general, CPT and CPS were significantly lower after S/RP with flap (37% and 14%, respectively) than after S/RP alone (62% and 24%). The advantage of S/RP with flap was greatest for facial and lingual surfaces and for anterior and premolar teeth. In both treatment groups CPS were similar over a pocket depth range of 0 to 6 mm. But in deeper pockets, CPS in teeth treated by S/RP with flap remained constant at 17% while after S/RP alone CPS increased linearly to approximately 45% at greater than 8 mm. The mean C/A was essentially equal in both treatment groups (11%) and was not related to pocket depth.

Calculus revisited. A review

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. Partial inhibition of plaque mineralization can be accomplished by chemical agents, but there has been no demonstration in humans of a reduction in gingivitis. It remains to be established what level of inhibition (if any) is required to have more than a cosmetic effect. Since the accepted scenario is that apical growth of supragingival plaque precedes the formation of subgingival calculus, there is no longer an issue of whether subgingival calculus is the cause or the result of periodontal disease. Subgingival mineralization results from the interaction of subgingival plaque with the influx of mineral salts that is part of the serum transudate and inflammatory exudate. This chronology, however, should not be the basis for relegating calculus to the ash heap. Morphologic and analytical studies point to the porosity of calculus and retention of bacterial antigens and the presence of readily available toxic stimulators of bone resorption. When coupled with the increased build up of plaque on the surface of the calculus, the combination has the potential for extending (beyond that of plaque alone) the radius of destruction and the rate of displacement of the adjacent junctional epithelium. The centrality of thorough scaling and root planing in the successful maintenance of periodontal health supports the view that subgingival calculus contributes significantly to the chronicity and progression of the disease, even if it can no longer be considered as responsible for initiation.

Reaction of human sera from juvenile periodontitis, rapidly progressive periodontitis, and adult periodontitis patients with selected periodontopathogens

The levels of serum antibody reactive to selected periodontopathogens were determined in 182 clinically characterized patients: 35 healthy control, 50 juvenile periodontitis, 42 adult periodontitis and 55 rapidly progressive periodontitis. Reactive antibody levels were determined using an enzyme-linked immunosorbent assay with whole cell preparations of Bacteroides gingivalis, Capnocytophaga (Bacteroides) ochraceus, Fusobacterium nucleatum and Actinobacillus actinomycetemcomitans (Y-4) serving as antigens. Increased reactivity to B. gingivalis and F. nucleatum was observed in all three disease groups studied while antibody reactive to A. actinomycetemcomitans was increased in juvenile and rapidly progressive periodontitis. Antibody levels reactive to C. ochraceus in healthy subjects did not differ from those observed in any disease patient groups. Possible implications in the etiology and progression of the diseases coupled with environmental changes which occur in the econiche of the periodontal pocket are described.

Surface coatings on dental cementum incident to periodontal disease. (II). Scanning electron microscopic confirmation of a mineralized cuticle

Root surfaces, exposed by periodontal disease, were studied after treatment with sodium hypochlorite. Observations of the anorganic specimens demonstrated that substantial changes occur in root surfaces incident to periodontal disease. A mineralized surface coating was seen in all areas of the involved root surface, although local regions occurred where the coating was apparently unmineralized. These findings generally confirmed the results of a previous study where the same specimens were studied without hypochlorite treatment. It is concluded that the coating is probably identical to the dental cuticle, and stems from adsorption of components of the gingival inflammatory exudate to the root surface. The coating may also be the carrier matrix for exogenous cytotoxic substances, previously thought to be located in the cementum. The findings may have implications for the way of treating periodontitis-involved root surfaces.