Vitamin C intake attenuates the degree of experimental atherosclerosis induced by periodontitis in the rat by decreasing oxidative stress

Objective

Periodontitis has been causally linked to cardiovascular disease, which is mediated through the oxidative stress induced by periodontitis. Since vitamin C has been suggested to limit oxidative damage, we hypothesized that vitamin C intake may reduce endothelial oxidative stress induced by periodontitis in the aorta. The aim of this study was to investigate the effects of vitamin C intake on the initiation of atherosclerosis in a ligature-induced rat periodontitis model.

Design

Eighteen 8-week-old-male Wistar rats were divided into three groups of six rats and all rats received daily fresh water and powdered food through out the 6-week study. In the vitamin C and periodontitis groups, periodontitis was ligature-induced for the first 4 weeks. In the vitamin C group, rats were given distilled water containing 1 g/L vitamin C for the 2 weeks after removing the ligature.

Results

In the periodontitis group, there was lipid deposition in the descending aorta and significant increases of serum level of hexanoyl-lysine (HEL), and aortic levels of nitrotyrosine expression, HEL expression and 8-hydroxydeoxyguanosine (8-OHdG) compared to the control group. Vitamin C intake significantly increased plasma vitamin C level and GSH:GSSG ratio (178% and 123%, respectively), and decreased level of serum HEL and aortic levels of nitrotyrosine, HEL and 8-OHdG (23%, 87%, 84%, and 38%, respectively).

Conclusions

These results suggest that vitamin C intake attenuates the degree of experimental atherosclerosis induced by periodontitis in the rat by decreasing oxidative stress.     

Recurrent Apical Periodontitis and Late Endodontic Treatment Failure Related to Coronal Leakage: A Case Report

Introduction

This article describes a case of late failure after endodontic retreatment as characterized by recurrent post-treatment apical periodontitis.

Methods

At the time of the initial treatment, the patient presented with acute apical abscess associated with a tooth with pulp necrosis caused by trauma. Four years later, the tooth was retreated because of persistent disease. The follow-up examination 28 months after retreatment showed complete healing.

Results

The patient returned 11 years and 7 months later for bleaching of the discolored tooth, and although the periodontal tissues were clinically and radiographically normal, a fracture line was observed on the mesial aspect of the pulp chamber. Extraction was indicated, but the patient only returned 5 years and 9 months later. Then a radiograph showed recurrent post-treatment apical periodontitis. The tooth was extracted, and histopathologic and histobacteriologic analyses revealed bacterial colonies along the fracture line and colonizing ramifications and accessory canals at the apical root canal system.

Conclusions

Coronal leakage can be regarded as the most reasonable explanation for resurgence of the disease. However, a predisposing overlapping condition in the form of root fracture conceivably favored the penetration of bacteria from saliva and plaque biofilm along the filled root canal.     

Influence of glycemic control on Epstein-Bar and Cytomegalovirus infection in periodontal pocket of type 2 diabetic subjects

Objective

The aim of the present study was to evaluate the influence of glycemic control on the frequency of Epstein-Bar (EBV) and Cytomegalovirus (CMV) in periodontal pockets of type 2 diabetic subjects with chronic periodontitis.

Design

Forty-six subjects presenting generalized chronic periodontitis and type 2 diabetes mellitus (DM) were selected for this study. Polymerase chain reaction (PCR) was used to determine the presence of EBV and CMV in shallow [Probing Depth (PD) ≤ 3 mm], moderate (PD = 4-6 mm) and deep (PD > 7 mm) pockets. HbA1c levels ≤7%, >7 to <10%, and ≥10% defined good, moderate and poor glycemic control, respectively.

Results

Higher frequency of EBV was found in the shallow pockets of the subjects with poor glycemic control (p < 0.05; chi-square test). Moreover, EBV-free subjects presented moderate or good glycemic control. Glycemic control did not influence the frequency of CMV in all pocket categories.

Conclusion

Poor glycemic control in type 2 diabetic subjects can increase the occurrence of EBV in shallow periodontal pockets.     

Participation of the endocannabinoid system in lipopolysaccharide-induced inhibition of salivary secretion

Objective

The aim of the present paper was to assess whether lipopolysaccharide (LPS)-induced inhibition of salivary secretion involves the activation of the endocannabinoid system and the participation of tumor necrosis factor (TNF)α in the submandibular gland.

Design

Pharmacological approaches were performed by using CB1 and/or CB2 cannabinoid receptor antagonists, AM251 and AM630, respectively, injected into the submandibular gland, to study the participation of the endocannabinoid system in LPS inhibitory effects on metacholine-induced salivary secretion. To assess the participation of TNFα on LPS inhibitory effects, salivary secretion was studied in LPS treated rats after the intraglandular injection of etanercept, a soluble form of TNF receptor which blocks TNFα action. Finally, to evaluate the possible interplay between endocannabinoids and TNFα on the submandibular gland function reduced during LPS challenge, the salivary secretion was studied after the intraglandular injection of this cytokine alone or concomitantly with AM251 and AM630.

Results

AM251 and AM630, injected separately or concomitantly, partially prevented LPS-induced inhibition of salivation. Also, anandamide synthase activity was increased in submandibular glands extracted from rats 3 h after LPS injection, suggesting that the endocannabinoid system was activated in response to this challenge. On the other hand, etanercept, prevented the inhibitory effect of LPS on salivary secretion and moreover, TNFα injected intraglandularly inhibited salivary secretion, being this effect prevented by AM251 and AM630 injected concomitantly.

Conclusion

The present results demonstrate the participation of the endocannabinoid system and TNFα on salivary responses during systemic inflammation induced by LPS.     

A comparative mechanical and bone remodelling study of all-ceramic posterior inlay and onlay fixed partial dentures

Objectives

Comparative studies of bone remodelling and mechanical stresses between inlay and onlay fixed partial dentures (FPD) are rather limited. The purpose of this paper was to evaluate the biological consequence in posterior mandibular bone and the mechanical responses in these two different prosthetic configurations.

Methods

Three-dimensional (3D) finite element analysis (FEA) models are created to explore the mechanical responses for the inlay and onlay preparations within the same oral environment. Strain induced bone remodelling was simulated under mastication. The remodelling adopted herein relates the strain in the bone to the change of Hounsfield Unit (HU) value in proportion to the surface area density (SAD) of bony morphology, which allows directly correlating to clinical computerised tomography (CT) data.

Results

The results show that both FPD designs exhibit a similar resultant change in bone mineral density (BMD) though the onlay configuration leads to a more uniform distribution of bone density. The inlay design results in higher mechanical stresses whilst allowing preservation of healthy tooth structure.

Conclusions

This study provides an effective means to further clinical assessment and investigation into biomechanical responses and long-term restorative outcome with different FPD designs.

Clinical significance

Quantifying in vivo stress distributions associated with inlay/onlay FPDs can further supplement clinical investigations into prosthetic durability, FPD preparation techniques (i.e., taper angles, material development), consequent stress distributions and the ongoing biomechanical responses of mandibular bone.     

Comparative evaluation of platelet-rich plasma and guided tissue regeneration membrane in the healing of apicomarginal defects: a clinical study

Introduction

The aim of the study was to compare the healing responses of platelet-rich plasma (PRP), PRP + a collagen sponge, and a collagen membrane used as guided tissue regeneration (GTR) materials for the treatment of apicomarginal defects.

Methods

Thirty patients with suppurative chronic apical periodontitis and apicomarginal communication were selected and allocated randomly into three groups according to the barrier technique to be used during periradicular surgery: the collagen membrane group, the PRP group, and the PRP + collagen sponge group. Clinical and radiographic measurements were determined at baseline and every 3 months after surgery up to 1 year. Cases were defined as healed when no clinical signs or symptoms were present, and radiographs showed complete or incomplete (scar tissue) healing of previous radiolucencies.

Results

The PRP and PRP + collagen sponge groups depicted 83.33% and 88.89% healing, respectively, in terms of combined clinical-radiographic healing as compared with 80% in the collagen membrane group. All the three treatments showed highly significant (P < .05) reductions in the periodontal pocket depth (PD), the clinical attachment level (CAL), the gingival margin position (GMP), the size of the periapical lesion, the percentage reduction of the periapical rarefactions, and periapical healing. No significant differences between the three groups were evident for these parameters (P > .05).

Conclusions

GTR applied to apicomarginal defects using PRP or PRP + collagen sponge lead to similar enhancements of the clinical outcome of periradicular surgery in terms of periapical healing, gain of periodontal support, PD reduction, and PRP may be an alternative treatment for GTR membrane in the treatment of apicomarginal defects.     

Prevalence and distribution of serotype-specific genotypes of Aggregatibacter actinomycetemcomitans in chronic periodontitis Brazilian subjects

Objective

Previous studies have suggested that Aggregatibacter actinomycetemcomitans is involved in the aetiology of aggressive periodontitis as well as chronic periodontitis. In addition, some authors have also reported that serotype-specific antigens of A. actinomycetemcomitans determine the severity of disease. This study aimed to elucidate the prevalence of A. actinomycetemcomitans and the distribution of A. actinomycetemcomitans serotypes in Brazilian subjects with chronic periodontitis.

Design

A total of 486 individuals were enrolled in this survey. All patients received clinical examinations that included periodontal pocket depth, clinical attachment loss, plaque, and gingival indexes. Subgingival samples were taken for microbial analysis. The genomic DNA of A. actinomycetemcomitans was provided by PCR.

Results

Out of 486 subjects examined, A. actinomycetemcomitans was isolated in 85 (17.5%) individuals. Out of 85 positive samples, 68 were infected by at least 1 serotype, 7 by mixed infection, and 10 were non-serotyped. Serotypes d and f were not detected. Serotype c showed the highest prevalence (52.9%), followed by serotype a (31.8%).

Conclusions

Intragroup analysis revealed that, in slight/moderate periodontitis, serotypes c and a were significantly more prevalent than serotypes b and d-f; the prevalence of serotype c in severe periodontitis was significantly greater than that of serotypes a and b. Our data were similar in Asian and Eurasian populations.     

Dental caries analysis in 3-5 years old children: A spatial modelling

Objectives

The main objective of this study was modelling experienced caries of deciduous teeth in 3-5 years old children treated in Children's Department of Tehran University of Medical Sciences, Iran, using the spatial autologistic regression. The other objective was identifying a risk pattern of decayed dents of these children.

Materials and methods

The study group consisted of 400 children (3-5 years old). Two groups of postgraduate and under graduate dentistry students under consideration and approval of the professors of dentistry from the Tehran University of Medical Sciences diagnosed and categorised the caries statuses of deciduous dents of the children. The caries statuses were considered as spatially correlated binary data. The appropriate model was autologistic regression.

Results

The fitted autologistic model showed that caries in the three nearest neighbours of a tooth, which includes the two adjacent and the one vertically opponent teeth, had significant effect on its caries. The computed risks based on the fitted model revealed a definite-spatial pattern of caries events.

Conclusions

Every decayed deciduous tooth in the mouth of a preschool child threatens the three nearest teeth. The risk pattern of caries in each quarter of the teeth lattice of children from incisors to molars has an ascending rate. The dents in maxilla and posterior locations have higher risks of caries than in mandible and anterior locations. These findings are valuable in preventive health care and therapeutic approaches in dentistry of children.     

Sex Differences in Neuropeptide Content and Release from Rat Dental Pulp

Introduction

Studies to examine sex differences in response to pain have suggested that females exhibit lower threshold responses to painful stimuli and that threshold response varies greatly at different stages of the menstrual cycle. Additional studies suggest that sex differences may be caused by societal sex roles or differences in anxiety responses by men and women.

Objective

The purpose of this study was to evaluate biologically evident sex differences in male and female rats chronically treated with a systemic algogen, the nerve growth factor (NGF), by measuring neuropeptides (calcitonin gene-related peptide) content and release from isolated dental pulp.

Methods

Rats were injected subcutaneously every other day with either murine NGF (1 mg/kg) or vehicle for 7 or 13 days. Isolated incisor pulp tissue was evaluated from these male and female rats (n = 96). Capsaicin-evoked neurosecretion of CGRP and tissue content were measured using a previously validated radioimmunoassay.

Results

Dental pulp from female rats at 7 days showed significantly increased capsaicin-evoked immunoreactive CGRP release (>50% increase) compared with tissue from male rats. After 13 days, this release was significantly increased only in NGF-treated female rats (3-fold increase) when compared with control females or both male groups. The CGRP content in tissue from both female groups was also significantly increased after 7 days of treatment (>3 fold), but after 13 days this content was only significantly increased in tissue from NGF-treated female rats (P = .0001).

Conclusions

These data suggest that sex differences affect the role of NGF in the modulation of inflammation through the regulation of peripheral neuropeptide release and content.     

A single application of hydrogen sulphide induces a transient osteoclast differentiation with RANKL expression in the rat model

Objective

Oral malodor is mainly attributed to volatile sulphur compounds (VSCs) such as hydrogen sulphide (H₂S), methyl mercaptan and dimethyl sulphide. VSC accelerate periodontal soft tissue destruction. However, there is little information about the potential role of H₂S in alveolar bone loss. The purpose of this animal study was to examine the effects of sodium hydrogen sulphide (NaHS), H₂S donor drug, on osteoclast differentiation in rat periodontal tissue.

Design

Twenty-four male Wistar rats (8 weeks old) were divided into four groups: a control group and three experimental groups, which were examined at 3 h, 1 day, and 3 days after topical application of 3 μl NaHS (l M in physiological saline) into the gingival sulcus of rat first molar. Expression of tumour necrosis factor (TNF)-α, RANKL, NF-κB and tartrate-resistant acid phosphatase (TRAP) was evaluated in the periodontal tissue.

Results

Three hours after NaHS application, TNF-α expression increased in the periodontal ligament. The numbers of RANKL-positive osteoblasts and TRAP-positive osteoclasts significantly increased progressively with time and reached a maximum level after 1 day. Significant up-regulation of RANKL and NF-κB mRNA was observed at 3 h after NaHS application.

Conclusions

H₂S application caused a transient increase of osteoclast differentiation with up-regulation of RANKL expression in osteoblasts. H₂S, which is primarily responsible for halitosis, may also contribute to alveolar bone resorption through RANKL expression.     

Clinical and microstructural aberrations of enamel of deciduous and permanent teeth in patients with autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy

Objective

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) causes multiple endocrine deficiencies, oral candidiasis and different forms of ectodermal dystrophy including enamel hypoplasia, documented in permanent teeth. Our purpose was to examine dental aberrations associated with APECED, including possible manifestations in primary teeth.

Design

We studied clinically, radiographically, and by scanning electron microscopy (SEM) teeth of children belonging to two APECED families with different mutations in the AIRE gene.

Results

In addition to enamel defects in the permanent teeth we observed hypoplastic pits and hypomaturated patches in the deciduous teeth with underlying changes in the prismatic ultrastructure. The enamel of the permanent molars exhibited a layered arrangement with included whirl-like formations.

Conclusions

Our findings confirm that APECED causes enamel defects that are individually but chronologically distributed, and can alter enamel development early enough to affect deciduous teeth.     

Astaxanthin restores the enzymatic antioxidant profile in salivary gland of alloxan-induced diabetic rats

Objective

To evaluate the effect of astaxanthin on antioxidant parameters of salivary gland from diabetic rats. The hypothesis of the study was whether the supplementation of diabetic rats with astaxanthin might antagonize, or at least prevent, the defect in their antioxidative status.

Design

Wistar rats (n = 32) were divided in 4 groups: untreated control, treated control, untreated diabetic and treated diabetic rats. Astaxanthin (20 mg/kg body weight) was administered daily by gavage for 30 days. On day 23, diabetes was induced by injection of alloxan (60 mg/kg body weight). After 7 days of diabetes induction, the rats were killed and submandibular and parotid removed. Superoxide dismutase (SOD), catalase, glutathione peroxidase and reductase activities and the content of thiol groups were determined. Data were compared by ANOVA and the Tukey test (p < 0.05).

Results

Diabetes caused a reduction of SOD, and thiol content and increase of catalase and glutathione peroxidase activities of submandibular gland whilst in the parotid gland diabetes caused an increase of thiol content and no effect in the antioxidant system. The astaxanthin restores the enzymatic activities in the salivary gland, however does not prevent its oxidative damage.

Conclusion

The submandibular gland presented more susceptibility to oxidative alterations induced by diabetes. Astaxanthin presented a positive effect on the oxidative protection of the salivary gland from diabetic rats.     

Evaluation of rat alveolar bone response to Angelus MTA or experimental light-cured mineral trioxide aggregate using fluorochromes

Introduction

The aim of this study was to evaluate the rat alveolar bone response after the implantation of experimental light-cured mineral trioxide aggregate (MTA) or Angelus MTA (Angelus, Londrina, Paraná, Brazil) by histological and fluorescence analysis.

Methods

Thirty Wistar Albino rats were divided into three groups. In the control group, empty polyethylene tubes were inserted into the rat alveolar sockets immediately after extraction. In the other groups, the tubes were filled with light-cured MTA or Angelus MTA. Five animals from each group were injected with calcein on day 7, alizarin on day 14, and oxytetracycline on day 21. On day 30, these animals were killed, and the right hemimaxillas were removed and histologically processed. Half of the maxillas were processed and stained with hematoxylin and eosin. The remaining maxillas were processed for fluorescence analysis and stained with Stevenel blue and alizarin red. New bone was histomorphometrically evaluated using a Merz grid.

Results

The light-cured MTA presented a similar response when compared with Angelus MTA; it was characterized by a mild inflammatory response and complete bone healing. In the light-cured MTA group, the fluorescence areas were more evident at 21 days, showing an increase in bone formation. However, dystrophic mineralization was observed only with Angelus MTA.

Conclusions

It was concluded that both materials present a similar inflammatory response and bone healing, but dystrophic mineralization was observed only with Angelus MTA.     

Supraposition of unopposed molars in young and adult rats

Objective

Previous clinical studies indicate that the overeruption of unopposed teeth may be different between young and adult individuals. The aim of this study was to investigate the position of the unopposed molar, in young and adult rats.

Methods

In young (4-week old) and adult (26-week old) rats, the right maxillary molar crowns were reduced occlusally by grinding. After 4 weeks, the animals were sacrificed and scanned by micro-CT.

Results

The unopposed molars of the young animals were in supraposition being on average 262 μm (±135 μm) higher than the position of molars with antagonists. This was more pronounced than in adults (average 125 ± 108 μm, P < 0.01). In the young animals the alveolar bone level was higher in the unopposed molars with supraposition while no differences were found in the adults’ molars.

Conclusions

Our results demonstrated that the overeruption potential of unopposed molars is higher in young than adult rats.     

Mandibular first molar with six separate canals

Introduction

Many anatomical variations can occur within the mandibular first molar. Commonly, 3-4 canals are located, but as many as 6-7 canals have been reported.

Methods

This report describes a case of a mandibular first molar with 6 separate canals (3 mesial and 3 distal) that was instrumented with conventional hand and rotary files and obturated by using a hybrid warm vertical compaction technique.

Results

Recall examination as far as 3 years post-treatment found no sensitivity to percussion or palpation and recall radiographs after treatment show resolution of the previous apical periodontitis.

Conclusions

The existence of such teeth as these underlies the importance of looking for additional canals.     

The association of tooth wear, diet and dietary habits in adults aged 18-30 years old

Objective

The association of acidic foods and drinks to the development of erosive tooth wear was investigated in a single cohort of adults aged 18-30 years.

Method

A tooth wear index was recorded on 1010 participant's who had a mean age of 21.9 years (SD 0.1) and of which 70% were female and 30% males. Participant's completed a previously validated questionnaire containing 50 questions about current and historical dietary habits. Data were analysed at the tooth level using odds ratio.

Results

Tooth wear was statistically significantly associated to acidic foods and drinks with high titratable acidity and dietary habits, including drinking from a glass and holding drinks, (OR 5 and 6.5 respectively). A history of heartburn was statistically significantly associated to palatal dentine exposure (p ≤ 0.05 and OR 7.6).

Conclusion

In this sample of adults, tooth wear was associated to a number of acidic dietary products and drinking habits.     

Hydrogen-rich water prevents lipid deposition in the descending aorta in a rat periodontitis model

Objective

Periodontitis has been causally linked to atherosclerosis, which is mediated by the oxidative stress. As hydrogen-rich water (HW) scavenges reactive oxygen species (ROS), we hypothesized that HW could prevent lipid deposition induced by periodontitis in the aorta. The aim of this study was to investigate the effects of HW on the initiation of atherosclerosis in a rat periodontitis model.

Design

Eighteen 8-wk-old male Wistar rats were divided into three groups of six rats; the periodontitis group, periodontitis + HW group and the no treatment (control) group. In the periodontitis and periodontitis + HW groups, periodontitis was induced using a ligature for 4 wk, while the periodontitis + HW group was given water containing 800–1000 μg/L hydrogen during the 4-wk experimental period.

Results

In the periodontitis group, lipid deposition in the descending aorta was observed. The periodontitis group also showed significant higher serum levels for ROS and oxidised low-density lipoprotein-cholesterol (ox-LDL) (1.7 and 1.4 times, respectively), and higher aortic expression levels of nitrotyrosine and hexanoyl-lysine (HEL) (7.9 and 16.0 times, respectively), as compared to the control group (p < 0.05). In the periodontitis + HW group, lipid deposition was lower. Lower serum levels of ROS and ox-LDL (0.46 and 0.82 times, respectively) and lower aortic levels of nitrotyrosine and HEL (0.27 and 0.19 times, respectively) were observed in the periodontitis + HW group than in the periodontitis group (p < 0.05).

Conclusions

HW intake may prevent lipid deposition in the rat aorta induced by periodontitis by decreasing serum ox-LDL levels and aortic oxidative stress.     

Development of a model of tissue with potentially malignant disorders (PMD) in the hamster cheek pouch to explore the long-term potential therapeutic and/or toxic effects of different therapeutic modalities

Objective

Given that locoregional recurrences developing from a tissue with potentially malignant disorders (PMD) in oral mucosa are a frequent cause of therapeutic failure, and that tissue with PMD is dose-limiting, the aim of the present study was to develop a model of tissue with PMD to evaluate the long-term therapeutic/toxic effects of different therapeutic modalities.

Materials and methods

We evaluated 5 carcinogenesis protocols based on topical application of the carcinogen dimethyl-1,2-benzanthracene in the hamster cheek pouch, twice a week for 4, 6, 7, and 8 weeks and the classical 3 times a week for 12 weeks.

Results

Long-term follow-up (8 months after protocol completion) was only possible with the 4- and 6-week carcinogenesis protocols. Tumour development increased progressively with time and aggressiveness of the carcinogenesis protocols. The time at which tumours developed in ≥90% of the animals was at protocol completion (T0) for the 12-week protocol, 1 month post-T0 for the 8-week protocol, 3 months post-T0 for the 7-week protocol and 4 months post-T0 for the 6-week protocol. <40% of the animals in the 4-week protocol developed tumours within the 8 months follow-up period. DNA synthesis rose as a function of time and protocol aggressiveness.

Conclusions

The 6-week carcinogenesis protocol was selected for long-term studies of different therapeutic modalities in tissue with PMD because it permitted long-term follow-up and guaranteed tumour development in ≥90% of the animals.