Diet-induced Generalized Periodontitis in Lewis Rats

Characterisation of the influence of dietary fat and sugar on bone health utilising densitometry, micro-computed tomography and histomorphometry

Obesogenic feeding can affect systemic metabolism and impact bone health and microarchitecture, but the findings of published studies often appear contradictory. This study aimed to compare the effects of a medium-fat/high-sugar (MF/HS) and a high-fat/high-fructose (HF/Fr) diet on the femora of weanling male Wistar rats, examining bone mineral content and density (BMC, BMD), cortical and cancellous bone microarchitecture and the cell populations within bone. Furthermore, we explored the correlations between circulating bone-targeting factors (in particular leptin, adiponectin and insulin) and bone parameters. Rats were assigned to one of three dietary groups (control: CON; MF/HS: OB1; HF/Fr: OB2; n = 12 each) for 17 weeks. Right-hand side femora were subjected to densitometry to measure BMC and BMD, and micro-computed tomography (μCT) was utilised to assess cortical and cancellous bone. Osteoblast (N.Ob), osteoclast (N.Oc), adipocyte (N.Ad) and chondrocyte numbers (N.Ch) were quantified histomorphometrically. Diet OB1 was largely beneficial to bone, while diet OB2 exerted detrimental effects on BMC, BMD, bone microarchitecture and bone cell populations. In cortical bone, N.Ob was positively correlated with BMD, cortical area and serum leptin. In cancellous bone, N.Ob was positively correlated with serum leptin and BMD, while N.Oc was negatively correlated with serum leptin. Overall, these findings support a role for endogenous circulating leptin in promoting bone formation. We conclude that the impact of different obesogenic diets may be driven by individual dietary effects on circulating factors, which may partly explain the contradictory reports in existing literature on the impact of HF and HS diets on bone.

Aerobic exercise training-induced bone and vascular adaptations in mice lacking adiponectin

Adiponectin regulates lipid and glucose metabolism, and insulin sensitivity in various target organs; however, the effects of adiponectin on bone health remain controversial. Exercise training can enhance bone density, bone microarchitecture, and blood flow. This study aimed to elucidate the role of adiponectin in adaptations of bone microarchitecture and bone vasculature in response to aerobic exercise training. Adult male C57BL/6 wild-type (WT) and homozygous adiponectin knockout (AdipoKO) mice were either treadmill exercise trained or remained sedentary for 8-10 weeks. The trabecular structures of the distal femoral metaphysis, a weight-bearing bone, and the mandible, a non-weight-bearing bone, were examined using microcomputed tomography. The femoral principal nutrient arteries were isolated to assess vasoreactivity (vasodilation and vasoconstriction) and structural remodeling. At the femoral metaphysis, impaired trabecular bone structures, including reduced connectivity density and increased trabecular spacing, were observed in AdipoKO mice compared to WT mice. In addition, nitric oxide-mediated, endothelium-dependent vasodilation was substantially reduced, and wall-to-lumen ratio was significantly increased in the femoral principal nutrient artery of AdipoKO mice. Interestingly, although exercise training-induced enhancements in trabecular connectivity density were observed at the femoral metaphysis of both WT and AdipoKO, increased vasoconstrictor responses were only observed in the femoral principal nutrient artery of WT mice, not in the AdipoKO mice. In mandibular trabecular bone, exercise training increased trabecular bone volume fraction (BV/TV, %) and intersection surface in the mandible of both WT and AdipoKO mice. These findings indicate that adiponectin is crucial for maintaining normal bone microarchitecture and vasculature. Although the absence of adiponectin compromises bone vascular adaptation to exercise training in mice, some exercise training-induced alterations in bone microarchitecture occurred in the absence of adiponectin, suggesting contribution of compensatory mechanisms during exercise training.

A New Way to Model Periodontitis in Laboratory Animals

The prevalence of periodontal diseases is increasing, tends to increase with age and is considered as one of the main causes of tooth loss. To assess the effectiveness of new methods of treatment of periodontal diseases, studies on laboratory animals can be promising.

THE AIM OF THE STUDY

to develop a new method of accelerated modeling of experimental periodontitis on laboratory animals.

MATERIAL AND METHODS

The study was carried out on 22 female rats. A wire ligature was applied to the cervical area of the incisors of the animals in an eight-shaped manner. Plaque obtained from a patient with periodontitis was placed under the wire, and nicotine and ethyl alcohol solutions were injected under the gingival mucosa. A complex index has been proposed to assess inflammation. At the end of the experiment the animals were euthanized, their jaws were dissected into dentoalveolar blocks and further descriptive histologic analysis was performed.

RESULTS

On the second day the gingiva of the rats acquired a cyanotic-pink color, on the fourth day the consistency of the gingiva became friable, mobility appeared in the lower incisors. Complex index of inflammation in animals of the main group: before the study-9, on the 7th day-195. Gingival preparations showed signs of exudative inflammation. In alveolar processes-irreversible resorption of bone structures. The difference of indicators in animals before and after the experiment was statistically significant (p < 0.05).

CONCLUSION

The new experimental model of periodontitis is reproduced in a short period of time, provides intensive development of inflammation, leads to disruption of the integrity of epithelial and connective tissue attachment, destruction of alveolar bone.

Stevioside reduces inflammation in periodontitis by changing the oral bacterial composition and inhibiting P. gingivalis in mice

BACKGROUND

Excessive sugar intake has become a major challenge in modern societies. Stevioside is a promising non-calorie sweetener with anti-inflammatory effects; however, its effects on the oral environment and periodontitis remain unclear. Therefore, this study explores the effect of stevioside on periodontitis in mice.

METHODS

Mice were divided into four groups, namely, control, treated with water, and periodontitis models, established using 5 - 0 silk sutures ligation around the second molar then infected the oral cavity with Porphyromonas gingivalis (P. gingivalis) viscous suspension, divided into three groups treated with 0.1% stevioside (P + S), 10% glucose (P + G), or water (P). Micro-CT scanning was used to assess alveolar bone resorption, while RT-PCR was used to evaluate the inflammatory factors expression and P. gingivalis invasion in the gingiva. The composition of the oral bacteria was analysed using 16 S rRNA sequence in the saliva. In addition, P. gingivalis was co-cultured with stevioside at different concentrations in vitro, and bacterial activity was detected via optical density values and live/dead staining. The virulence was detected using RT-PCR, while biofilm formation was detected using scanning electron microscopy.

RESULTS

Compared with 10% glucose, treatment with 0.1% stevioside reduced alveolar bone absorption and osteoclasts while decreasing IL-6, TNF-α, IL-1β, and P. gingivalis in the gingiva of periodontitis mice. The CEJ-ABC distance in the P + S group was significantly lower than that in the P and P + G groups (P < 0.05). Moreover, the composition of the oral bacteria in the P + S group was similar to that of the control. In vitro stevioside treatment also reduced the bacterial activity and toxicity of P. gingivalis in a dose-dependent manner and affected its biofilm composition.

CONCLUSION

Our results indicate that, compared with 10% glucose, 0.1% stevioside intake can reduce alveolar bone resorption and inflammation in periodontal tissues in mice; the bacterial composition following 0.1% stevioside intake was similar to that of a healthy environment. In vitro, high concentrations of stevioside reduced P. gingivalis activity, biofilm formation, and virulence expression. Therefore, stevioside is a potential alternative to glucose for patients with periodontitis.

The optimization of ligature/bone defect-induced periodontitis model in rats

The destruction of alveolar bone is a crucial manifestation of severe chronic periodontitis, which stem cell-based bioengineered therapies are expected to cure. Therefore, a cost-effective, reproducible, quantifiability and easier to administrate animal model that mimics human periodontitis is of great importance for further endeavor. In this study, we created periodontitis rat models in silk ligation group, bone defect group and bone defect/silk ligation group, respectively. Obvious periodontal inflammation but slight alveolar bone resorption was observed in the ligation group, while surgical trauma was not robust enough to continually worsen the constructed bone defect area in the bone defect group. In the bone defect/ligature group, significant and stable periodontal inflammation was the most enduring with similar evolving pathological patterns of human periodontitis. It also exhibited enhanced clinical similarity and confirmed its superiority in quantitativeness. The present rat model is the first study to reproduce a pathological process similar to human periodontitis with reliable stability and repeatability, manifesting a priority to previous methods. Day 9-12 is the best time for reproducing severe periodontitis syndromes with vertical bone resorption in this model.

Investigating oral and systemic pathways between unhealthy and healthy dietary patterns to periodontitis in adolescents: A population-based study

AIM

To investigate pathways between unhealthy and healthy dietary patterns and periodontitis in adolescents (18-19 years of age).

MATERIALS AND METHODS

This population-based study (n = 2515) modelled direct and mediated pathways (via biofilm and obesity) from patterns of healthy diet (fruits, fibre, vegetables, and dairy) and unhealthy diet (sugars, snacks, and salty/fast foods) with initial periodontitis (bleeding on probing [BoP], probing depth [PD] ≥ 4 mm, clinical attachment loss [CAL] ≥ 4 mm), moderate periodontitis (BoP, PD ≥ 5 mm, and CAL ≥ 5 mm), and European Federation of Periodontology and the American Academy of Periodontology (EFP-AAP) periodontitis definitions, adjusting for sex, socio-economic status, smoking, and alcohol, through structural equation modelling (α = 5%).

RESULTS

Higher values of healthy diet were associated with lower values of initial periodontitis (standardized coefficient [SC] = -0.160; p < .001), moderate periodontitis (SC = -0.202; p < .001), and EFP-AAP periodontitis (p < .05). A higher value of unhealthy diet was associated with higher values of initial periodontitis (SC = 0.134; p = .005) and moderate periodontitis (SC = 0.180; p < .001). Biofilm mediated the association between higher values of unhealthy diet and all periodontal outcomes (p < .05).

CONCLUSIONS

Our findings suggest that both healthy and unhealthy dietary patterns may contribute to reduced or increased extent and severity of periodontitis by local and systemic mechanisms, preceding the effect of other established causes such as smoking and obesity, in younger population.

Preventing or controlling periodontitis reduces the occurrence of osteonecrosis of the jaw (ONJ) in rice rats (Oryzomys palustris)

INTRODUCTION

Osteonecrosis of the jaw (ONJ) is an adverse event that requires association of both systemic risk factors, such as powerful anti-resorptives (pARs; e.g. zoledronic acid [ZOL]), and local oral risk factors (e.g. tooth extraction, periodontitis). Whereas optimal oral health prior to initiate pARs is recognized as critically important for minimizing ONJ risk, the efficacy of preventive/maintenance measures in patients who are taking pARs is understudied. Rice rats fed a standard diet (STD), rich in insoluble fiber, develop localized periodontitis. STD-rats with localized periodontitis treated with ZOL for 18-24 wk develop ONJ. Hence, we hypothesized that controlling/preventing localized periodontitis in the ZOL-treated rats, reduces ONJ occurrence.

METHODS

We used two approaches to attempt reducing periodontitis prevalence: 1) periodontal cleaning (PC); and 2) replacing the STD-diet with a nutritionally-equivalent diet high in soluble fiber (SF). 75 four-week-old male rats were weight-randomized into five groups (n = 15) in a 24-week experiment. Three groups ate the STD-diet and two the high SF-diet. STD-diet groups received intravenous (IV) vehicle (VEH) q4wks (STD + VEH), 80 μg/kg ZOL q4wks IV (STD + ZOL), or ZOL plus PC q2wks (STD + ZOL + PC). The SF-diet groups received VEH (SF + VEH) or ZOL (SF + ZOL). Jaws were processed for histopathology and evaluated for ONJ prevalence and tissue-level periodontitis.

RESULTS

1) 40% of STD + VEH rats developed maxillary localized periodontitis with no ONJ; 2) 50% of STD + ZOL rats developed ONJ; 3) 7% of STD + ZOL + PC rats developed ONJ (p < 0.01 vs. STD + ZOL); and 4) one SF + ZOL rat developed localized periodontitis, and no SF + VEH or SF + ZOL rats developed ONJ (p < 0.001 vs. STD + ZOL).

CONCLUSIONS

1) Periodontal cleaning in ZOL-treated rats decreases localized periodontitis severity and reduces ONJ prevalence; and 2) feeding a SF-diet to ZOL-treated rats reduces both incidence of localized periodontitis and ONJ. Our data indicates strong oral microbial community shifts according to oral health condition and trends in the shifts associated with diet.