Effect of obesity on alveolar bone loss in experimental periodontitis in Wistar rats

Obesity has been linked to higher inflammatory status and periodontal breakdown.

Objective

The purpose of this study was to investigate the effect of obesity on alveolar bone loss in experimental periodontitis in rats.

Material and Methods

Twenty-four female Wistar rats were randomly divided into two groups: obese (n=13), which were fed with "cafeteria diet" (CAF diet - high amounts of sucrose and fat) for 90 days in order to gain weight, and non-obese (n=11) regularly fed rats. Ligature-induced experimental periodontitis was created in all animals. Body weight differed statistically between obese and non-obese groups (277.59 and 223.35 g, respectively) at the moment of the ligature placement. Morphometric registration of alveolar bone loss was carried out after 30 days of ligature placement to determine the effect of obesity on the progression of experimental periodontitis.

Results

Intra-group comparisons showed significantly higher alveolar bone loss mean values in maxillary teeth with ligature (P<0.05). Alveolar bone loss [mean (SD), mm] was not statistically different between obese and non-obese groups [0.71 (0.09) and 0.65 (0.07) mm, respectively]. However, when palatal sides are analyzed separately, obese group presented significantly higher alveolar bone loss (P<0.05) as compared to non-obese [0.68 (0.12) and 0.53 (0.13) mm, respectively].

Conclusions

In spite of the weak differences, it is possible to conclude that the progression of alveolar bone loss in ligature-induced periodontitis can be potentially influenced by body weight in rats.     

Initial changes in alveolar bone volume for sham-operated and ovariectomized rats in ligature-induced experimental periodontitis

Objectives

Osteoporosis is a disease characterized by a reduction in bone mass, poor bone strength, and microarchitectural deterioration primarily in postmenopausal women. With respect to periodontal disease, osteoporosis is thought to contribute to pre-existing alveolar degeneration although the association between both diseases is not fully characterized. The aim of the present study was to observe the initial changes in mandibular alveolar bone for sham-operated and ovariectomized (OVX) rats in ligature-induced experimental periodontitis.

Materials and methods

A total of 64 Wistar rats (7 weeks of age, 180–200 g) were used in this study (32 control sham-operated animals?+?ligature placement, 32 OVX animals?+?ligature placement). Following an 8-week period to induce an OVX model, micro-CT analysis was performed to calculate vertical and furcation bone loss of mandibular first molars at time points 0, 3, 7, and 11 days following ligature placement (six animals per group per time point). Furthermore, histological analysis was performed to calculate the loss of alveolar bone crest height from the cemento-enamel junction, and tartrate-resistant acid phosphatase (TRAP) staining was utilized to calculate the number of osteoclasts.

Results

The results from the present study demonstrate that OVX animals showed significant vertical bone loss at all time points when compared to control sham-operated animals. In the furcation area, no significant difference in bone loss was observed between sham-operated and OVX animals at 0, 3, and 7 days; however by 11 days, a significant decrease in bone volume/total volume and trabecular thickness was observed in the OVX group. The histological analysis also revealed that alveolar bone crest height was significantly reduced in OVX animals, and TRAP staining further revealed the greater number of multinucleated osteoclasts peaking at 3 days postligature placement.

Conclusion

The results from the present study demonstrate a direct correlation between the osteoporotic phenotype and the progression of periodontal breakdown in a diseased-induced animal model.

Clinical relevance

It may be suggested that an osteoporotic phenotype has the potential to speed periodontal breakdown and thus contributes to the overall degeneration of the periodontium in patients suffering from postmenopausal bone loss. Future research from human clinical studies are necessary to further understand the relationship between periodontal disease and osteoporosis.

     

Long-term evaluation of oral gavage with periodontopathogens or ligature induction of experimental periodontal disease in mice

Objective

To evaluate in long-term periods the destruction of periodontal tissues and bacterial colonization induced by oral gavage with periodontopathogens or ligature experimental periodontal disease models.

Material and methods

Forty-eight C57BL/6 J mice were divided into four groups: group C: negative control; group L: ligature; group G-Pg: oral gavage with Porphyromonas gingivalis; and group G-PgFn: oral gavage with Porphyromonas gingivalis associated with Fusobacterium nucleatum. Mice were infected by oral gavage five times in 2-day intervals. After 45 and 60 days, animals were sacrificed and the immune-inflammatory response in the periodontal tissue was assessed by stereometric analysis. The alveolar bone loss was evaluated by live microcomputed tomography and histometric analysis. qPCR was used to confirm the bacterial colonization in all the groups. Data were analyzed using the Kruskal-Wallis, Wilcoxon, and ANOVA tests, at 5 % of significance level.

Results

Ligature model induced inflammation and bone resorption characterized by increased number of inflammatory cells and decreased number of fibroblasts, followed by advanced alveolar bone loss at 45 and 60 days (p?<?0.05). Bacterial colonization in groups G-Pg and G-PgFn was confirmed by qPCR but inflammation and bone resorption were not observed (p?<?0.05).

Conclusions

The ligature model but not the oral gavage models were effective to induce inflammation and bone loss in long-term periods. Pg colonization was observed in all models of experimental periodontal disease induction, independent of tissue alterations. These mice models of periodontitis validates, compliments, and enhances published PD models that utilize ligature or oral gavage and supports the importance of a successful colonization of a susceptible host, a bacterial invasion into vulnerable tissue, and host-bacterial interactions that lead to tissue destruction.

Clinical relevance

The ligature model was an effective approach to induce inflammation and bone loss similar to human periodontitis, but the oral gavage models were not efficient in inducing periodontal inflammation and tissue destruction in the conditions studied. Ligature models can provide a basis for future interventional studies that contribute to the understanding of the disease pathogenesis and the complex host response to microbial challenge.

     

Local and cardiorenal effects of periodontitis in nitric oxide-deficient hypertensive rats

Objective

In this study we have assessed the renal and cardiac consequences of ligature-induced periodontitis in both normotensive and nitric oxide (NO)-deficient (L-NAME-treated) hypertensive rats.

Materials and methods

Oral L-NAME (or water) treatment was started two weeks prior to induction of periodontitis. Rats were sacrificed 3, 7 or 14 days after ligature placement, and alveolar bone loss was evaluated radiographically. Thiobarbituric reactive species (TBARS; a lipid peroxidation index), protein nitrotyrosine (NT; a marker of protein nitration) and myeloperoxidase activity (MPO; a neutrophil marker) were determined in the heart and kidney.

Results

In NO-deficient hypertensive rats, periodontitis-induced alveolar bone loss was significantly diminished. In addition, periodontitis-induced cardiac NT elevation was completely prevented by L-NAME treatment. On the other hand L-NAME treatment enhanced MPO production in both heart and kidneys of rats with periodontitis. No changes due to periodontitis were observed in cardiac or renal TBARS content.

Conclusions

In addition to mediating alveolar bone loss, NO contributes to systemic effects of periodontitis in the heart and kidney.     

Effects of Cachaça, a typical Brazilian alcoholic beverage,on alveolar bone loss and density: A study in peripubertal rats

Objective

The aim of the present study was to assess the impact of chronic consumption of Cachaça on alveolar bone loss (BL) induced by ligature and on alveolar bone density (BD) in peripubertal rats.

Design

Male Wistar rats were assigned into one of the following groups: Control: non-ingestion of Cachaça (n = 15); Cachaça: ingestion of ascending concentrations of Cachaça during 100 days (n = 15). 70th day after the beginning of Cachaça ingestion, one first mandibular molar received a ligature while the contralateral tooth was left unligated. After 30 days, the rats were killed. BL, BD, the positive cells for tartrate-resistant acid phosphatase (TRAP), receptor activator of NF-κB ligand (RANKL) and osteoprotegerin (OPG) were analyzed in the furcation area of the ligated and unligated mandibular molars.

Results

The Cachaça group presented greater BL (0.75 ± 0.1 mm² for Cachaça and 0.66 ± 0.1 mm² for control group, respectively) and number of RANKL and OPG+ cells and lower BD (60.3 ± 4.2% for Cachaça and 76.8 ± 3.8% for control group, respectively) and number of TRAP+ cells around ligated teeth (p < 0.05), when compared to the control group. The Cachaça group (0.42 ± 0.02 mm²) also presented a higher BL around unligated teeth when compared to control group (0.31 ± 0.05 mm²).

Conclusions

Cachaça consumption per se and in the presence of ligature negatively affects alveolar bone by increasing the alveolar BL and reducing BD.     

Atherogenic cholesterol-rich diet and periodontal disease

Objective

This study investigated the effect of an atherogenic cholesterol-rich diet (AT) on the alveolar bone loss in rats with ligature-induced experimental periodontitis (EP).

Methods

Female Wistar adult rats were assigned either a control (Co) or an AT diet fed for 9 weeks. The AT diet was high in saturated fat, cholesterol and energy. At week 2, animals were subjected to a unilateral ligature (L) around the left first molar (Co + L and AT + L). The contra lateral first right molar (not ligated) of both groups (Co and AT) were used as untreated controls. At week 9, blood was drawn, rats were euthanized, hemi-mandibles removed and stained digital photographs (buccal and lingual surfaces) and radiographs were obtained for quantification of alveolar bone loss (ABL). The ABL was determined by distance and area methods (mm²) and X-rays were used for periodontal bone support (PBS), (%).

Results

Rats in the AT group exhibited a 17% increase in energy intake, gained significant body weight and showed the highest serum total-cholesterol (T-C) and non-high density lipoprotein-cholesterol (HDL-C) levels (p < 0.001). The amount of lost periodontal bone was the greatest in AT + L rats. AT feedings significantly increased the buccal area and distance of bone loss when compared with the unligated-teeth (p < 0.001). The rats in the AT + L group also achieved the lowest percentage of PBS (p < 0.001). The AT and Co + L rats showed similar PBS. This method more clearly elucidated the effect of the cholesterol-rich AT, with and without the influence of molar ligature, compared to the morphometric analysis.

Conclusion

The alveolar bone loss of EP was magnified by ingestion of an atherogenic diet high in saturated fatty acids and cholesterol.     

Peripheral kappa opioid receptors activation reduces alveolar bone loss in rats by modulating interleukin-6 and -10

Objective

The beneficial effects of kappa opioid agonist U-50,488 in preventing periodontal disease (PD) progression in rats have already been described, but its mechanism of action is unknown. The present study evaluated the expression of TNF-α, IL-6, IL-8 and IL-10 in the gingival tissues of rats with ligature-induced PD, treated with U-50,488. It also correlated the effects of this agonist with myeloperoxidase (MPO) activity and the presence of osteoclasts.

Design

Male Holtzman rats weighing 250–300 g were divided into four groups: (1) control, (2) ligature, (3) ligature + saline and (4) ligature + kappa agonist. Experimental PD was induced by placing a sterile silk ligature around the 2nd left upper molar. Rats from groups 3 to 4 were locally administered with either saline or U-50,488, respectively, from day 3 to day 5 following ligation. After 5 or 11 days, the rats were euthanized and periodontal tissue samples were collected for histological and morphometric analysis and for determination of TNF-α, IL-6, IL-8, IL-10 and MPO.

Results

Ligature placement induced significant alveolar bone loss. The number of osteoclasts, degree of MPO activity, IL-6, IL-8 and TNF-α expression were also increased by PD. U-50,488 reduced both bone loss and the number of osteoclasts, but did not alter histological inflammatory infiltrate or MPO activity. U-50,488 significantly reduced IL-6 and increased IL-10 levels, but did not affect TNF-α and IL-8.

Conclusion

Lowering the levels of IL-6 and increasing IL-10 are important mechanisms by which U-50,488 reduces alveolar bone loss in ligature-induced periodontal disease.     

Expression of suppressor of cytokine signaling 1 and 3 in ligature-induced periodontitis in rats

Objective

: Evaluate expression of inducible negative regulators of JAK/STAT pathway and their target proteins during the course of ligature-induced experimental periodontal disease in rats.

Design

: Rats were sacrificed 07, 15 and 30 days after disease induction for histological evaluation of periodontal inflammation and macroscopic analysis of alveolar bone loss. SOCS expression and the activation status of STAT1 and STAT3 were evaluated in gingival biopsies by real time PCR and Western blot.

Results

: Ligature-induced model presented significant progressive bone loss from 7 to 30 days. Inflammation was evident and similar for 07 and 15 days; however, a decrease on severity at the end of the experimental period was observed. There was a significant (p < 0.05) increase on SOCS1 and SOCS3 gene expression in PD compared to control group at 15 and 30 days. The SOCS1 and SOCS3 protein expression and activation of STAT1 and STAT3 were increased in earlier periods in the ligature model.

Conclusion

: This study suggests that SOCS1 and SOCS3 were directly correlated with regulatory mechanism of the inflammatory process responsible for the periodontal disease destruction.     

VDR deficiency affects alveolar bone and cementum apposition in mice

Objective

To compare the mineralisation density (MD), morphology and histology of alveolar bone and cementum amongst VDR +/+, VDR −/−, and VDR −/− groups supplemented with a diet TD 96348, containing 20% lactose, 2.0% calcium and 1.25% phosphorous.

Methods

Four groups of mice (6 mice/group) were identified by genotyping: VDR +/+ mice (VDR wild type), VDR −/− mice (VDR deficient), VDR −/− offsprings derived from VDR −/− parents receiving a supplemental diet (early rescued), and VDR −/− mice fed with a supplemental diet beginning at age one month (late rescued). All mice were sacrificed at age 70.5 days. Micro-CT was used to compare MD and morphology of alveolar bone and cementum. H–E and Toluidine blue staining was used to examine the ultrastructure of the alveolar bone and cementum at matched locations.

Results

In VDR −/− group, alveolar bone and cementum failed to mineralise normally. Early rescue increased MD of alveolar bone in VDR −/− mice with excessive alveolar bone formation, but which not observed in late rescue group. MD and morphology of cementum–dentine complex in both early and late rescue groups were comparable with VDR +/+ group when feeding with high-calcium rescue diet.

Conclusions

VDR affects alveolar bone mineralisation and formation systemically and locally. However, cementum apposition and mineralisation is mainly regulated by calcium concentrations in serum.     

Evaluation of two morphometric methods of bone loss percentages caused by periodontitis in rats in different locations

Objective

The present study evaluated morphometrically bone loss percentages in experimental periodontitis in rats, comparing different locations (lingual mandible, palatal maxilla and buccal maxilla) and two evaluation methods (distance and area methods).

Material and Methods

Ligatures were placed around the maxillary right second molar and around the mandibular right first molar in 14 female Wistar rats. The contralateral molars served as intragroup controls. After 4 weeks, the rats were sacrificed and their mandible and maxilla were removed. The specimens were dissected and stained with methylene blue dye. Bone loss was evaluated by two different methods on the surfaces of the defleshed jaw. In the first method, the distance from the cementoenamel junction (CEJ) to the alveolar bone crest was measured in the roots of teeth associated with ligature. In the second method, the area of bone loss was determined using the alveolar tissue bone, CEJ and the proximal region of roots associated with the ligature as reference. The data were converted to bone loss percentages caused by ligature: (ligated – unligated) x 100/ligated.

Results

When comparing the distance and area methods, no statistically significant difference was observed (p>0.05). Both methodologies indicated that the maxilla presented greater bone loss than the mandible and it was more accentuated on the buccal side than on the palatal side (p<0.05).

Conclusion

The findings of this study show that both the area and the distance methods can be used to evaluate bone loss caused by ligature placement in rats, and suggest applying the morphometric methodology to the maxilla on the buccal side.     

Effect of sympathetic nervous activity on alveolar bone loss induced by occlusal hypofunction in rats

Objective

To elucidate the effect of sympathetic nervous activity on alveolar bone loss induced by occlusal hypofunction in rat molars.

Design

Occlusal hypofunction in the molar area was produced by attaching appliances to rat maxillary and mandibular incisors. In addition, a non-selective β-adrenergic receptor antagonist, propranolol, was administered orally to rats in drinking water to pharmacologically suppress sympathetic nervous activity. After 1 week, alveolar bones in all groups were examined by micro-CT, histomorphometry and histology to determine their trabecular bone phenotypes and histological changes.

Results

The marrow spaces of the interradicular alveolar bone of rat mandibular first molars (M1) increased in the occlusal hypofunction group (Group H) but not in the control group (Group C), whilst these decreased in rats in the occlusal hypofunction group that were administered propranolol (Group HB). Bone volume/tissue volume (BV/TV), trabecular thickness (Tb.Th) and trabecular number (Tb.N) for interradicular alveolar bone in M1 in Group H were significantly lower than those in Group C, whereas those in Group HB remained as high as those in Group C. The number of TRAP-positive cells in Group H increased compared to that in Group C, whereas it significantly decreased in Group HB.

Conclusions

These results suggest that sympathetic nervous activity may influence the alveolar bone loss induced by occlusal hypofunction.     

Effects of exercise training on gingival oxidative stress in obese rats

Objective

The purpose of the present study was to investigate the effects of exercise training on serum reactive oxygen species (ROS) level and gingival oxidative stress in obese rats fed a high-fat diet.

Design

Rats were divided into three groups (n = 14/group): one control group (fed a regular diet) and two experimental groups (fed a high-fat diet with and without exercise training [treadmill: 5 days/week]). The rats were sacrificed at 4 or 8 weeks. The level of serum reactive oxidative metabolites (ROM) was measured as an indicator of circulating ROS. The level of 8-hydroxydeoxyguanosine (8-OHdG) and reduced-form glutathione (GSH)/oxidised-form glutathione (GSSG) ratio were determined to evaluate gingival oxidative stress.

Results

The obese rats fed a high-fat diet without exercise training showed higher serum ROM levels [Carratelli Units (CARR U)] (mean ± SD; 413 ± 64) than the control (333 ± 12) at 4 weeks (p = 0.023). Such a condition resulted in higher 8-OHdG levels (ng/mg mtDNA) (0.97 ± 0.18) (p < 0.05) and a lower GSH/GSSG ratio (17.0 ± 3.1) (p < 0.05) in gingival tissues, compared to the control (0.55 ± 0.13 for 8-OHdG and 23.6 ± 5.8 for GSH/GSSG ratio) at 8 weeks. In addition, the obese rats fed a high-fat diet with exercise training showed lower serum ROM (623 ± 103) (p < 0.001) and gingival 8-OHdG levels (0.69 ± 0.17) (p = 0.012) than those without exercise training (1105 ± 95 for ROM and 0.55 ± 0.13 for 8-OHdG) at 8 weeks.

Conclusions

Obesity prevention by exercise training may effectively suppress gingival oxidative stress by decreasing serum ROS in rats.     

Osteogenic effect of Drynariae rhizoma extracts and Naringin on MC3T3-E1 cells and an induced rat alveolar bone resorption model

Objective

To investigate if Drynariae rhizoma (DR) and its main ingredient Naringin could reduce alveolar bone loss by stimulating the proliferation and differentiation of osteoblasts.

Materials and methods

The effect of DR water (DRWE), ethanolic extract (DREE), and Naringin on MC3T3-E1 cells was evaluated respectively by MTT method and by measuring the activity of alkaline phosphatase (ALP activity) as well as the level of osteocalcin in medium. Bone mineral density (BMD) detection, osteoclast counting by tartrate resistant acid phosphatase staining, and histopathological analysis were performed in an induced rat model of alveolar bone resorption after gastric perfusion with DR extracts or Naringin.

Results

DRWE and Naringin effectively increased the proliferation of MC3T3-E1 cells, whilst DREE and Naringin enhanced the differentiation of osteoblastic cells. The in vivo study indicated an elevated BMD value in the tooth-periodontal tissues from DRWE, DREE and Naringin treated groups after 10, 20 and 30 days of perfusion (P < 0.05). In DRWE treated group, the number of osteoclasts at days 10, 20 and 30 decreased remarkably as compared to the corresponding negative controls (P < 0.05), and no osteoclast could be found at day 30. New non-calcified bone-like matrix attached by osteoblasts at the root furcation was also shown.

Conclusions

DR could be a supplementary medicine for periodontal therapy as it could reduce bone resorption in rat model of alveolar bone resorption and exert osteogenic effect on osteoblasts.     

Effects of ovariectomy on turnover of alveolar bone in the healed extraction socket in rat edentulous mandible

Objective

The number of patients with postmenopausal osteoporosis receiving dental implants because of edentulism is increasing. Since osseointegration around implants requires formation and maintenance of new bone, knowledge of how ovariectomy (OVX) affects turnover of mandibular and maxillary bone is required. In the present study, we investigated the effects of OVX on turnover of alveolar bone in the healed extraction socket of the rat left mandibular incisor.

Methods

The molars and the incisor on left side in 6-month-old Sprague–Dawley female rats (n = 38) were extracted and left to heal for 4 months. Animals were then ovariectomized and killed at the time of OVX (baseline) (n = 4), 6 weeks (n = 10), 6 months (n = 12) and 9 months (n = 12) post-OVX. Changes in bone mass and bone turnover were assessed using static and dynamic histomorphometric parameters.

Results

Bone turnover was increased by ovariectomy (OVX) as reflected by increased static parameters of bone formation and resorption. The changes in dynamic parameters were not statistically significant. Cancellous bone volume/total volume (%) in the post-OVX group decreased more than that in the control group.

Conclusions

Our results suggest that OVX increases the turnover of alveolar bone in the healed extraction socket of rat mandibular incisor, resulting in a decrease of cancellous bone volume with time.     

Effects of mastication on glucose metabolism in rats, with emphasis on differences in properties of food consumed whilst breeding

Objective

In this study, to elucidate the effects of preferred properties of food that affect the daily masticatory habits on the onset of lifestyle-related disease, we investigated whether groups of rats continuously fed with diet having distinct properties show differences in glucose metabolism.

Design

Thirty-six male Wistar rats aged 4 weeks were divided into two groups; only the pellet type feed was given to one (solid diet group), and the powdered feed to the other (powder diet group).The oral glucose tolerance test (OGTT) was performed to measure glucose metabolism.For the determination of statistical significance (p < 0.05), blood glucose level and areas under the blood glucose response curve (AUC) were analysed using the Mann–Whitney U-test.

Results

The AUC values were significantly different between the two diet groups when the animals were 45 and 51 weeks of age. The median blood glucose level in 45-week-old rats fed with the powder diet was significantly higher than those in age-matched rats fed with solid diet 45 and 120 min after glucose load. Similarly, the median blood glucose level in the 51-week-old rats in the powder diet group was significantly higher than those in the solid diet group at 30, 45, 60, and 120 min after glucose load.

Conclusions

We showed that the rats which had been fed with solid diet and therefore had been masticating the feed plentifully enhanced glucose metabolism. This can suggest the possible use of masticatory and dietary intervention, which promotes sufficient mastication of hard food, in the prevention and cure of human lifestyle-related diseases.     

Effect of sumac extract on serum oxidative status,RANKL/OPG system and alveolar bone loss in experimental periodontitis in rats

Objectives

Sumac (Rhus coriaria L.) is widely used spice which has several properties such as antioxidant, anti-inflammatory and antimicrobial. The purpose of this animal study was to evaluate the effects of sumac extract on levels of receptor activator of nuclear factor-kappa B ligand (RANKL), osteoprotegerin (OPG) expression, serum oxidative status, and alveolar bone loss in experimental periodontitis.

Material and Methods

Twenty-four Wistar rats were separated into three groups: non-ligated (NL, n=8), ligature only (LO, n=8), and ligature and treated with sumac extract (S, n=8) (20 mg/kg per day for 11 days). A 4/0 silk suture was placed around the mandibular right first molars subgingivally; after 11 days, the rats were sacrificed, and alveolar bone loss was histometrically measured. The detection of RANKL and OPG were immunohistochemically performed. Levels of serum total antioxidant status (TAS)/total oxidant status (TOS), and oxidative stress index (OSI) were also analyzed.

Results

Alveolar bone loss was significantly greater in the LO group compared to the S and NL groups (p<0.05). The number of inflammatory cell infiltrate (ICI) and osteoclasts in the LO group was significantly higher than that of the NL and S groups (p<0.05). The number of osteoblasts in the LO and S groups was significantly higher than that of the NL group (p<0.05). There were significantly more RANKL-positive cells in the LO group than in the S and NL groups (p<0.05). OPG-positive cells were higher in S group than in LO and NL groups (p<0.05). TOS and OSI levels were significantly reduced in S group compared to LO group (P<0.05) and TAS levels were similar in S and NL group (p>0.05).

Conclusions

The present study showed that systemic administration of sumac extract may reduce alveolar bone loss by affecting RANKL/OPG balance, TOS and OSI levels in periodontal disease in rats.     

Effects of a Mikania laevigata extract on bone resorption and RANKL expression during experimental periodontitis in rats

Objectives

The Mikania laevigata extract (MLE) (popularly known in Brazil as "guaco") possesses anti-inflammatory properties. In the present study we tested the effects of MLE in a periodontitis experimental model in rats. We also investigated possible mechanisms underlying such effects.

Material and Methods

Periodontal disease was induced by a ligature placed around the mandibular first molars of each animal. Male Wistar rats were divided into 4 groups: non-ligated animals treated with vehicle; non-ligated animals treated with MLE (10 mg/kg, daily); ligature-induced animals treated with vehicle and ligature-induced animals treated with MLE (10 mg/kg, daily). Thirty days after the induction of periodontal disease, the animals were euthanized and mandibles and gingival tissues removed for further analysis.

Results

Morphometric analysis of alveolar bone loss demonstrated that MLE-treated animals presented a decreased alveolar bone loss and a lower expression of the activator of nuclear factor-κB ligand (RANKL) measured by immunohistochemistry. Moreover, gingival tissues from the MLE-treated group showed decreased neutrophil migration myeloperoxidase (MPO) assay.

Conclusions

These results indicate that MLE may be useful to control bone resorption during progression of experimental periodontitis in rats.     

Effect of Alveolar Segmental Sandwich Osteotomy on Alveolar Height: A Preliminary Study

Purpose

Bone loss following extraction is maximum in horizontal dimension. Height is also reduced which is pronounced on the buccal aspect. Various surgical procedures are available to correct the bone volume viz. GBR, onlay bone grafting, alveolar distraction and sandwich osteotomy. Sandwich osteotomy has been found to increase the vertical alveolar bone height successfully.

Objectives

The objective of the study was to assess the effect of alveolar segmental sandwich osteotomy on alveolar height and crestal width.

Materials and Methodology

A prospective study was undertaken from December 2012 to August 2014. Seven patients with 12 implant sites with a mean age of 36 years were recruited. All seven patients with 12 implant sites underwent alveolar segmental sandwich osteotomy and interpositional bone grafting. Alveolar bone height was assessed radiographically preoperatively, immediate post-op, and at 3 months post-op. Alveolar bone width was assessed radiographically preoperatively and at 3 months post-op. Statistical significance was inferred at p < 0.05.

Results

The mean vertical augmentation at immediate post-op was 6.58 mm (p = 0.001). The vertical augmentation that was achieved 3 months post-op was a mean of 3.75 mm which was statistically significant (p = 0.004). The change in alveolar height from immediate post-op to 3 month post-op was a mean 1.69 mm. The mean change in alveolar crestal width at 3 months was a mean of ?0.29 mm (p = 0.57).

Conclusion

Sandwich osteotomy can be used as an alternative technique to increase alveolar bone height prior to implant placement. Moderate alveolar deficiency can be predictably corrected by this technique.

     

Radiographic assessment of photodynamic therapy as an adjunctive treatment on induced periodontitis in immunosuppressed rats

Objective

The aim of this study was to assess radiographically the effect of photodynamic therapy (PDT) as an adjunctive treatment to scaling and root planing (SRP) on induced periodontitis in dexamethasone-induced immunosuppressed rats.

Material and Methods

The animals were divided into 2 groups: ND group (n=60): saline treatment; D group (n=60): dexamethasone treatment. In both ND and D groups, periodontal disease was induced by the placement of a ligature in the left first mandibular molar. After 7 days, ligature was removed and all animals received SRP, being divided according to the following treatments: SRP: saline and PDT: phenothiazinium dye (TBO) plus laser irradiation. Ten animals per treatment were killed at 7, 15 and 30 days. The distance between the cementoenamel junction and the height of the alveolar bone crest in the mesial surface of the mandibular left first molars was determined in millimeters in each radiograph. The radiographic values were analyzed statistically by ANOVA and Tukey''s test at a p value <0.05.

Results

Intragroup radiographic assessment (ND and D groups) showed that there was statistically significant less bone loss in the animals treated with PDT in all experimental periods compared to those submitted to SRP. Intergroup radiographic analysis (ND and D groups) demonstrated that there was greater bone loss in the ND group treated with SRP compared to the D group treated with PDT at 7 and 30 days.

Conclusion

PDT was an effective adjunctive treatment to SRP on induced periodontitis in dexamethasone-induced immunosuppressed rats.     

The effect of commercial conjugated linoleic acid products on experimental periodontitis and diabetes mellitus in Wistar rats

Objective: The aim of present study was to determine the effects of conjugated linoleic acid enriched milk on alveolar bone loss, hyperglycaemia, oxidative stress and apoptosis in ligature-induced periodontal disease in diabetic rat model.

Methods: Wistar rats were divided into six experimental groups: 1; non-ligated (NL, n?=?6) group, 2; ligature only (LO, n?=?6) group, 3; streptozotocin only (STZ, n?=?8) group, 4; STZ and ligature (STZ?+?L, n?=?8) group, 5; ligature and conjugated linoleic acid (CLA) (L?+?CLA, n?=?8) group, 6; STZ, ligature and CLA group (STZ?+?L?+?CLA, n?=?8) group. Diabetes mellitus was induced by 60?mg/kg streptozotocin. Rats were fed with CLA enriched milk for four weeks. Silk ligatures were placed at the gingival margin of lower first molars of mandibular quadrant. The study duration was four weeks after diabetes induction and the animals were sacrificed at the end of this period. Changes in alveolar bone levels were clinically measured and tissues were histopathologically examined. Inducible nitric oxide synthase (iNOS) and Bax protein expressions, serum interleukin-1β (IL-1β), low-density lipoprotein (LDL), high-density lipoprotein (HDL) and triglyceride levels and tartrate resistant acid phosphatase (TRAP)+?osteoclast numbers were also evaluated.

Results: At the end of four weeks, alveolar bone loss was significantly higher in the STZ?+?LO group compared to the other groups (p?p?p?p?>?.05).

Conclusion: Within the limits of this study, commercial CLA product administration in addition to diet significantly reduced alveolar bone loss, increased osteoblastic activity and decreased osteoclastic activity in the diabetic Wistar rats.