Regeneration processes of alveolar bone and microvascular changes after the application of platelet-rich fibrin.

OBJECTIVES: Platelet-rich fibrin (PRF) is a promising agent for bone regeneration (BR). Platelets contain several growth factors that promote angiogenesis and BR. In this study, we observed the morphology of alveolar BR. METHODS: PRF (Advanced PRF: A-PRF) was prepared by extracting 10 mL of blood from each dog in a collection tube before tooth extraction. The samples were centrifuged at 200 × g for 8 min and incubated for 10 min to allow clotting. The alveolar socket on the dentition's right side was densely filled with PRF. The opposite side, which did not receive PRF, served as the control group. Different methods were used for specimen preparation and observation. Sections stained with hematoxylin and eosin were observed under a light microscope. Bone specimens were observed using stereoscopic microscopy. The resin cast models were examined using a scanning electron microscope. Moreover, bone formation ratio and height were measured. RESULTS: Fourteen days postoperatively, angiogenesis and bone deposition were more advanced in the PRF group than in the control group. Thirty days postoperatively, both groups developed porous bone. In the PRF group, new bone trabeculae (BT) and a network of blood vessels were formed in the bone marrow. Ninety days postoperatively, the resin cast showed a normal bone structure with BT and bone marrow. Thick BT were observed in the PRF group. CONCLUSIONS: Growth factors in PRF stimulate microcirculation and promote angiogenesis and bone deposition. The benefits of PRF include safety and increased bone formation.

Effects of Diabetes and Voluntary Exercise on IgA Concentration and Polymeric Immunoglobulin Receptor Expression in the Submandibular Gland of Rats.

Background and Objectives: Patients with diabetes are more susceptible to upper respiratory tract infections (URTIs) because they are easily infected. Salivary IgA (sali-IgA) levels play a major role in transmitting URTIs. Sali-IgA levels are determined by salivary gland IgA production and polymeric immunoglobulin receptor (poly-IgR) expression. However, it is unknown whether salivary gland IgA production and poly-IgR expression are decreased in patients with diabetes. While exercise is reported to increase or decrease the sali-IgA levels, it is unclear how exercise affects the salivary glands of patients with diabetes. This study aimed to determine the effects of diabetes and voluntary exercise on IgA production and poly-IgR expression in the salivary glands of diabetic rats. Materials and Methods: Ten spontaneously diabetic Otsuka Long-Evans Tokushima Fatty (OLETF) rats (eight-week-old) were divided into two groups of five rats each: a non-exercise group (OLETF-C) and a voluntary wheel-running group (OLETF-E). Five Long-Evans Tokushima Otsuka (LETO) rats without diabetes were bred under the same conditions as the OLETF-C. Sixteen weeks after the study began, the submandibular glands (SGs) were collected and analyzed for IgA and poly-IgR expression levels. Results: IgA concentrations and poly-IgR expression levels in SGs were lower in OLETF-C and OLETF-E than in LETO (p < 0.05). These values did not differ between the OLETF-C and OLETF-E. Conclusions: Diabetes decreases IgA production and poly-IgR expression in the salivary glands of rats. Moreover, voluntary exercise increases sali-IgA levels but does not increase IgA production and poly-IgR expression in the salivary glands of diabetic rats. Increasing IgA production and poly-IgR expression in the salivary glands, which is reduced in diabetes, might require slightly higher-intensity exercise than voluntary exercise under the supervision of a doctor.

Application of multi-directionally forged high-strength titanium to dental implants in beagle dogs.

Pure titanium is widely used as a material in dental implants. However, it possesses inferior mechanical strength. This study aimed to elucidate the efficacy of acid treated multi-directionally forged (MDF) pure titanium in vivo. We verified the temporal changes until osseointegration in beagle dogs. Using two types of experimental materials (conventional pure titanium or MDF pure titanium), new bone formation was assessed using morphological examinations, and the bone-to-implant contact (BIC) value was evaluated at each time point (14, 30, and 90 days after the operation). As such, new bone formation was observed around the acid-etched MDF group, in which the BIC value was highest, followed by that in the acid-etched pure titanium group. MDF pure titanium implants showed early promotion of new bone formation compared to conventional titanium implants. The new acid-treated MDF made of pure titanium could be applied to humans in the future to prove its practicality.

Advanced platelet-rich fibrin (A-PRF) has an impact on the initial healing of gingival regeneration after tooth extraction.

OBJECTIVES: Platelet-rich fibrin (PRF) is widely used in wound healing because it contains several growth factors, including vascular endothelial growth factor (VEGF). In this study, we investigated the effects of advanced PRF (A-PRF) in early-stage gingival regeneration after tooth extraction. METHODS: Blood sample was collected from females beagle dogs (age: 12 months) before tooth extraction for A-PRF preparation. All animals were sacrificed by perfusion-fixation on postoperative days 1, 3, and 7. The upper jaws were prepared for hematoxylin and eosin staining and immunostaining (for CD34 and VEGF). The lower jaw samples were prepared for scanning electron microscope observations. Blood flow in the gingiva before and after surgery was measured using laser Doppler flowmetry. RESULTS: In the A-PRF group, a large number of microvessels were observed in the gingival tissue on postoperative day 1. The microvessels in the control group were fewer and sparse. Regarding the vascular resin cast, a large number of new blood vessels were observed on postoperative day 1 in the A-PRF group. A stronger CD34-positive signal was obtained around the blood vessels in the A-PRF group than in the control group. Further, a strong VEGF-positive signal was observed in the perivascular tissue in the A-PRF group. Gingival blood flow was significantly higher in the A-PRF group after surgery. CONCLUSION: A-PRF had a positive impact on angiogenesis in the gingiva through the induction of VEGF expression. Thus, A-PRF may be beneficial for gingival tissue regeneration.

Cognitive Dysfunction in a Mouse Model of Cerebral Ischemia Influences Salivary Metabolomics.

Vascular dementia, caused by cerebrovascular disease, is associated with cognitive impairment and reduced hippocampal metabolite levels. Specifically, cognitive impairment can be induced by decreased hippocampal brain-derived neurotrophic factor (BDNF) expression. The development of low or non-invasive biomarkers to characterize these diseases is an urgent task. Disturbance of metabolic pathways has been frequently observed in cognitive impairment, and salivary molecules also showed the potentials to reflect cognitive impairment. Therefore, we evaluated salivary metabolic profiles associated with altered hippocampal BDNF expression levels in a cerebral ischemia mouse model using metabolomic analyses. The effect of tacrine (a cholinesterase inhibitor) administration was also examined. The arteries of ICR mice were occluded with aneurysm clips to generate the cerebral ischemia model. Learning and memory performance was assessed using the elevated plus maze (EPM) test. Hippocampal and blood BDNF levels were quantified using an enzyme-linked immunosorbent assay. Glutamate decarboxylase 1 (GAD1) mRNA expression, is associated with cognitive impairment, was quantified by a real-time polymerase chain reaction. The EPM test revealed impaired spatial working memory in the cerebral ischemia mouse model; tacrine administration ameliorated this memory impairment. Cerebral ischemia suppressed GAD1 expression by decreasing hippocampal BDNF expression. In total, seven salivary metabolites, such as trimethylamine N-oxide and putrescine, were changed by cognitive impairment and tacrine administration. Our data suggest that salivary metabolite patterns were associated with cognitive function.

Effect of High Fat and Fructo-Oligosaccharide Consumption on Immunoglobulin A in Saliva and Salivary Glands in Rats.

Consumption of indigestible dietary fiber increases immunoglobulin A (IgA) levels in saliva. The purpose of this study is to clarify the synergistic effect of the intake of a high amount of fats and indigestible dietary fiber on IgA levels in saliva and submandibular glands (SMG). Seven-week-old Wistar rats were fed a low-fat (60 g/kg) fiberless diet, low-fat fructo-oligosaccharide (FOS, 30 g/kg) diet, high-fat (220 g/kg) fiberless diet, or high-fat FOS diet for 70 days. The IgA flow rate of saliva (IgA FR-saliva) was higher in the low-fat FOS group than in the other groups (p < 0.05). Furthermore, the concentration of tyrosine hydroxylase (a marker of sympathetic nerve activation) in the SMG was higher in the low-fat FOS group (p < 0.05) and positively correlated with the IgA FR-saliva (rs = 0.68. p < 0.0001. n = 32) in comparison to that in the other groups. These findings suggest that during low-fat FOS intake, salivary IgA levels may increase through sympathetic nerve activation.

Changes in the microcirculation in periodontal tissue due to experimental peri-implantitis.

OBJECTIVES: Peri-implantitis causes dislodgement of dental implants due to inflammation in the peri-implant tissue. The microcirculation in the periodontal tissue undergoes morphological and physiological changes due to inflammation. The immune mechanism of peri-implantitis differs from that of periodontitis. In this study, we examined the changes in the microcirculation in the peri-implant tissue with experimentally induced inflammation, using morphological and physiological techniques. METHODS: Six beagle dogs were used in the experiment. After extracting both mandibular premolars, three titanium screw implants were inserted on each side of the mandibular jaw. Dental floss was placed on the right side for 90 days in the study group but not in the control group. Microvascular resin cast models were created, and morphological changes were observed using scanning electron microscopy. Periodontal blood flow was measured using laser Doppler flowmetry. RESULTS: Ninety days after induction of inflammation, bone resorption was observed around the implant body. Osseointegration was impaired, and a gap at the implant-bone interface was observed. The resin cast models showed that inflamed gingival blood vessels had invaded the bone marrow through the resorbed apical margin of the alveolar bone. Analysis of the physiological data obtained using laser Doppler flowmetry showed a significant increase in blood flow around the implants with experimentally induced inflammation. CONCLUSIONS: Significant morphological and physiological changes occur in the gingival microcirculation of peri-implant tissue due to inflammation. Evaluating the vasculature and blood flow in the tissue surrounding the site of peri-implantitis may be helpful for pathologic analysis in clinical settings.

Application of deproteinized bovine bone mineral as proangiogenic scaffold for alveolar bone formation in beagle dogs.

Alveolar bone repair after tooth extraction is essential after oral surgeries. Various grafting materials are used to promote the regeneration of lost alveolar bone. This study analysed the morphological features of the tissue regeneration process using deproteinized bovine bone mineral (DBBM). DBBM was used to densely fill the extraction sockets in beagle dogs. Following resin casting of the vasculature, stereomicroscopy and scanning electron microscopy were used to observe blood vessels and hard tissues in haematoxylin and eosin-stained sections on postoperative days 14, 30 and 90 in conjunction with vascular endothelial growth factor (VEGF) immunostaining to evaluate alveolar bone vascularization. On day 14 post-operation, the DBBM granules tightly filled the extraction sockets, maintained alveolar margin height and formed a scaffold for aiding angiogenesis and new bone formation. On day 30, new bone formation was observed around the DBBM granules. By day 90, bone tissue regeneration progressed in both groups but was more pronounced in the DBBM group. Alveolar margin height was maintained in the DBBM group throughout the study. Furthermore, VEGF expression in the DBBM group was detected around newly formed bone. We conclude that DBBM acts as a suitable scaffold for new bone generation, as well as angiogenesis around healing alveolar bone, and that it has the potential to play a key role in vascularization and bone formation.

Hypertriglyceridemia-induced brain-derived neurotrophic factor in rat submandibular glands.

OBJECTIVES: Salivary glands produce brain-derived neurotrophic factor (BDNF), which increases plasma BDNF content. Salivary BDNF influences the hippocampus and enhances anxiety-like behaviors. Dyslipidemia affects the brain, promoting depression and anxiety-like behaviors. This study was performed to investigate whether hypertriglyceridemia influences salivary BDNF expression. METHODS: Hypertriglyceridemia was induced in rats by high-fat diet intake for 10 weeks. BDNF protein levels in the saliva and submandibular glands were measured using enzyme-linked immunosorbent assay (ELISA). Bdnf mRNA levels in the submandibular gland were determined using real-time polymerase chain reaction. RESULTS: A hypertriglyceridemia rat model was established. Body weight did not differ between the control and hypertriglyceridemia groups. Bdnf mRNA and protein expression was increased in the submandibular gland in the hypertriglyceridemia group compared to the control group. BDNF expression was also significantly increased in the saliva of the hypertriglyceridemia group. CONCLUSIONS: This is first study to show that hypertriglyceridemia induces BDNF expression in the rat submandibular gland and suggests that salivary BDNF is associated with lipid metabolism.

Inhibitory effect of omega-3 fatty acids on alveolar bone resorption and osteoclast differentiation.

In this study, a Porphyromonas gingivalis (P.g.)-infected mouse periodontitis model was used to investigate the effect of omega-3 fatty acid intake on differentiation and maturation of cultured osteoclast. Four-week-old C57BL/6JJcl mice were divided into four groups according to the diets they were fed from the beginning of the experiment (i.e., food containing omega-3 or omega-6 fatty acids) and whether they were orally administered P.g. Thirty-three days after beginning the experiment, bone marrow cells were sampled from the femoral bone of mice from each group and differentiated into osteoclasts; the effects of the ingestion of different fatty acids were subsequently investigated. There was no statistical interaction between the different fatty acids and P.g. infection on the number of osteoclasts (P = 0.6). However, the fatty acid type affected the number of osteoclasts in mice (P = 0.0013), with the omega-3 groups demonstrating lower osteoclast numbers than the omega-6 groups. Furthermore, the addition of resolvin E1 (RvE1), which is an omega-3 fatty acid-derived lipid mediator, suppressed the differentiation of mouse cultured osteoclasts (P < 0.0001). Therefore, the ingestion of omega-3 fatty acids may suppress osteoclast differentiation while inhibiting bone resorption and tissue destruction due to periodontitis.

Faster Short-Chain Fatty Acid Absorption from the Cecum Following Polydextrose Ingestion Increases the Salivary Immunoglobulin A Flow Rate in Rats.

Salivary immunoglobulin A (IgA) plays a vital role in preventing upper respiratory tract infections (URTI). In our previous study, we showed that the intake of carbohydrates increases the intestinal levels of short-chain fatty acids (SCFAs), which in turn increase salivary IgA levels. However, the mechanism underlying this phenomenon has not been fully elucidated. In this study, we investigated in rats the effect of polydextrose (PDX) ingestion on salivary IgA level and SCFA concentration in cecal digesta and the portal vein. Five-week-old rats were fed with a fiber-free diet (control) or with 40 g/kg of PDX for 28 days. Compared to the control, ingestion of PDX led to a higher salivary IgA flow rate (p = 0.0013) and a higher concentration of SCFAs in the portal vein (p = 0.004). These two data were positively correlated (rs = 0.88, p = 0.0002, n = 12). In contrast, the concentration of SCFAs in cecal digesta and cecal digesta viscosity were significantly lower following PDX ingestion, compared to the control (p = 0.008 and 0.05, respectively). These findings suggest that the ingestion of PDX increases the absorption rate of SCFAs in the intestine through PDX-induced fermentation, which is accompanied by an increase in SCFA levels in the blood, and ultimately leads to increased salivary IgA levels.

Vitamin C and eggshell membrane facilitate orthodontic tooth movement and induce histological changes in the periodontal tissue.

OBJECTIVES: Collagen remodeling of the periodontal tissue is an important mechanism that involves several biologically active substances to accelerate orthodontic tooth movement. It is known that Vitamin C (VC) enhances collagen production and induces tooth movement. Moreover, the eggshell membrane (ESM) is an integral component of various formulations used to promote wound healing. The purpose of our study was to determine the effects of combined treatment with VC and ESM on periodontal tissues during tooth movement. METHODS: Nine-week-old male osteogenic disorder Shionogi rats were randomized into four groups: control, VC, ESM, and VC + ESM. The control group was given tap water, and the VC, ESM, and VC + ESM groups were orally administered 0.1% VC solution, 1 wt% ESM solution, and a combination of 0.1 wt% VC and 1 wt% ESM solutions, respectively. A force of 25 or 75 g was applied for 10 days to produce orthodontic tooth movement. Distances of tooth movement were measured on days 3, 7, and 10 of treatment. Histological examination of the periodontal ligament was performed to determine the increase in type I and III collagen levels in response to treatment. RESULTS: Distances of tooth movement were significantly greater in the VC + ESM group than in the control group. The compression area of the alveolar bone showed increased osteoclastic activity and higher levels of bone resorption in the VC + ESM group. Expression levels of type I and III collagen in the tension area of the alveolar bone were higher in the VC + ESM group than in the control group. CONCLUSIONS: This study revealed that the combined administration of VC and ESM accelerated tooth movement by protecting the periodontal tissue during orthodontic treatment. The combined clinical application of VC and ESM could potentially shorten orthodontic treatment time.

Microcirculation changes in gingival tissue after ultrasonic tooth preparation in beagle dogs.

OBJECTIVE: Ultrasonic wave technology is widely used during dental treatments. We previously demonstrated that this method protects the gingival tissue. However, the physiological change on the gingival microvasculature caused by this method remains unclear. The aim of this study was to investigate the relationship between the morphological and physiological effects on gingival microcirculation when preparing teeth, using the conventional dental turbine or ultrasonic method. METHODOLOGY: The lower premolar teeth of beagle dogs were prepared along the gingival margin by using a dental turbine or ultrasonic wave instrument. Gingival vasculature changes were investigated using scanning electron microscopy for corrosion resin casts. Gingival blood flow at the preparation site was determined simultaneously by laser Doppler flowmetry. These assessments were performed immediately (Day 0), at 7 days and 30 days after tooth preparation. RESULTS: At day 0, in the turbine group, blood vessels were destroyed and some resin leaked. Furthermore, gingival blood flow at the site was significantly increased. In contrast, the ultrasonic group demonstrated nearly normal vasculature and gingival blood flow similar to the non-prepared group for 30 days after preparation. No significant alterations occurred in gingival circulation 30 days after either preparation; however, the turbine group revealed obvious morphological changes. CONCLUSIONS: Based on multiple approach analyses, this study demonstrated that ultrasonic waves are useful for microvascular protection in tooth preparation. Compared with a dental turbine, ultrasonic wave instruments caused minimal damage to gingival microcirculation. Tooth preparation using ultrasonic wave instruments could be valuable for protecting periodontal tissue.

Brain-derived neurotrophic factor is related to stress and chewing in saliva and salivary glands.

Chewing is one of the most important orofacial functions. During this process, food is reduced in size, while saliva moistens the food and binds it into a bolus that can be easily swallowed. Characteristics of the oral system, including the number of teeth, bite force, and salivary flow, influence the masticatory process. In addition, salivary glands produce several cell growth factors and play an important role in human health. The nerve growth factor (NGF) family consists of NGF, brain-derived neurotrophic factor (BDNF), and neurotrophins-3 to 7. BDNF is a well-studied neurotrophin involved in the neurogenesis, differentiation, and maintenance of select peripheral and central neuronal cell populations during development and adulthood. However, there has been no detailed description of the expression of neurotrophins other than NGF in the salivary gland. We previously studied the effect of immobilization stress + chewing on BDNF secretion and its receptor, tyrosine receptor kinase B, in rat submandibular glands and found increased BDNF expression in duct cells under these conditions. In this review, we describe recent advances in understanding the role of stress and chewing-related BDNF in the saliva and salivary glands.

Microcirculation changes in gingival tissue after ultrasonic tooth preparation in beagle dogs

Abstract Ultrasonic wave technology is widely used during dental treatments. We previously demonstrated that this method protects the gingival tissue. However, the physiological change on the gingival microvasculature caused by this method remains unclear. Objective The aim of this study was to investigate the relationship between the morphological and physiological effects on gingival microcirculation when preparing teeth, using the conventional dental turbine or ultrasonic method. Methodology The lower premolar teeth of beagle dogs were prepared along the gingival margin by using a dental turbine or ultrasonic wave instrument. Gingival vasculature changes were investigated using scanning electron microscopy for corrosion resin casts. Gingival blood flow at the preparation site was determined simultaneously by laser Doppler flowmetry. These assessments were performed immediately (Day 0), at 7 days and 30 days after tooth preparation. Results At day 0, in the turbine group, blood vessels were destroyed and some resin leaked. Furthermore, gingival blood flow at the site was significantly increased. In contrast, the ultrasonic group demonstrated nearly normal vasculature and gingival blood flow similar to the non-prepared group for 30 days after preparation. No significant alterations occurred in gingival circulation 30 days after either preparation; however, the turbine group revealed obvious morphological changes. Conclusions Based on multiple approach analyses, this study demonstrated that ultrasonic waves are useful for microvascular protection in tooth preparation. Compared with a dental turbine, ultrasonic wave instruments caused minimal damage to gingival microcirculation. Tooth preparation using ultrasonic wave instruments could be valuable for protecting periodontal tissue.

Effect of social isolation stress on saliva BDNF in rat.

Salivary glands produce various compounds, including brain-derived neurotrophic factor (BDNF), which serve as biomarkers of stress-related disorders. Social isolation-induced stress models a form of chronic mild stress that induces neurodegenerative changes in the brain and behavioral alterations. This study employed a rat model to determine whether social isolation stress affects BDNF levels in saliva. Male Sprague-Dawley rats were randomly allocated to social isolation stress (1 animal/cage) or control (3-4 animals/cage) groups and reared for 8 weeks. The concentration of BDNF was quantified in specific brain regions, blood, and saliva using enzyme-linked immunosorbent assay (ELISA). The levels of expression of Bdnf and tyrosine kinase B (TrkB) mRNA were quantified using reverse transcriptase-polymerase chain reaction. Behavioral alterations were analyzed using the open-field and elevated plus maze assays. The BDNF concentration was lower in the hippocampus, prefrontal cortex, blood, and saliva of the stress group than in those of the controls. Trkb expression in the hippocampus and prefrontal cortex was decreased by social isolation stress. Moreover, the social isolation stress group showed behavioral deficits in both tests. In conclusion, these findings indicate that social isolation stress may reduce the expression of BDNF protein in blood and saliva, thus providing a potentially valuable biomarker for diagnosis of stress-related disorders.

Detection of anti-citrullinated protein antibody (ACPA) in saliva for rheumatoid arthritis using DBA mice infected with Porphyromonas gingivalis.

OBJECTIVE: The anti-citrullinated protein antibody (ACPA), an autoantibody of rheumatoid arthritis (RA), is very specific in the diagnosis of RA and has been detected in early cases and several years before the onset of the disease. In this study, we focused on ACPA and examined whether it could be detected in saliva whether it is associated with periodontal disease. DESIGN: Porphyromonas gingivalis (Pg) or Escherichia coli (Ec) was administered into the oral cavity of DBA/1JJmsSlc mice. The arthritis index was measured in foot bones, and collected saliva and serum. The amount of ACPA in serum and saliva was measured using ELISA, and antibodies in serum, saliva, and foot bones were detected and analysed by western blotting. RESULT: Histopathological analysis of foot bones of the Pg/RA group detected greater inflammatory cell infiltration than in the RA group, and bone resorption was evident. Furthermore, ELISA results show that the amount of ACPA in serum was significantly higher in the Pg/RA group (P < 0.05), with a tendency to also increase in the saliva. In addition, western blotting results show a 55 kDa citrullinated protein in the serum and saliva of the RA and Pg/RA groups. CONCLUSIONS: We conclude that Pg infection increases ACPA in the serum and is reflected in the saliva, and may be involved in the inflammatory progression of RA.

Effect of ingesting yogurt fermented with Lactobacillus delbrueckii ssp. bulgaricus OLL1073R-1 on influenza virus-bound salivary IgA in elderly residents of nursing homes: a randomized controlled trial.

Objective: The purpose of this study was to clarify the influence of consuming yogurt fermented with Lactobacillus delbrueckii ssp. bulgaricus OLL1073R-1 (1073R-1-yogurt) on influenza virus-bound salivary immunoglobulin A (IgA) levels, in the elderly residents of nursing homes. Methods: A double-blind, parallel-group, randomized controlled trial was conducted with 96 elderly volunteers residing in 2 nursing homes. During the trial, participants consumed 100 g of 1073R-1-yogurt every morning for 12 weeks, whereas the control participants consumed yogurt fermented with a different Lactobacillus strain (control yogurt). Saliva was collected before the trial and after 4, 8 and 12 weeks of yogurt ingestion. Results: Our data indicated that consumption of 1073R-1-yogurt affected influenza A virus subtype H3N2-bound IgA levels in saliva (p = .001). In addition, saliva flow rate and total IgA levels increased in response to the yogurt intake period in both the 1073R-1 and control yogurt groups (p = .04). Conclusions: Our study suggests that continuous daily ingestion of 1073R-1-yogurt may help prevent infection with influenza A virus subtype H3N2 in elderly subjects with weakened immunity, by increasing the production of influenza A virus subtype of H3N2-bound salivary IgA.

Effect of advanced platelet-rich fibrin on accelerating alveolar bone formation in dogs: a histological and immunofluorescence evaluation.

Several methods have been developed to regenerate lost alveolar bone. Platelet-rich fibrin (PRF) is a useful adjunct for new bone formation in dentistry. To elucidate the effect of advanced PRF (A-PRF) on bone formation, we inserted A-PRF clots in sockets after tooth extraction. Premolars were extracted from beagle dogs, and A-PRF was applied to the socket. New bone formation was assessed using histological and immunofluorescence examinations, and the bone formation ratio was evaluated 14 and 30 days postoperatively. Histological examination revealed newly formed bone filling the sockets up to the center in the A-PRF group at 14 days postoperatively, while thick and regular bone trabeculae were arranged in porous bone after 30 days. Higher expressions of osteocalcin and osteopontin were observed in newly formed bone in the A-PRF group, compared to the control group. The bone formation ratio was also higher in the A-PRF group than in the control group. Thus, A-PRF application may result in enhanced new bone formation and may aid in accelerating bone formation. A-PRF was more rapid than a self-limiting process during induction of bone formation by enhancing osteoblast activity and may be useful for bone formation in clinical medicine.

Continuous combined intake of polydextrose and lactitol stimulates cecal fermentation and salivary IgA secretion in rats.

Immunoglobulin A (IgA), which plays an important role in infection defense, is upregulated in the large intestine and oral cavity through dietary fiber intake. However, the mechanism underlying salivary IgA increase through dietary fiber intake remains unknown. This study investigated time-dependent effects of non-absorbable polydextrose (PDX) and lactitol intake on salivary IgA secretion and cecal fermentation. Five-week-old rats were fed a fiber-free diet with or without 25 g/kg PDX and 25 g/kg lactitol for 1, 4, and 8 weeks. Compared to control, those who ingested PDX and lactitol had higher salivary IgA flow rates per weight of submandibular gland tissue at 4 and 8 weeks (P < 0.05), greater cecal weight and digesta at 1, 4, and 8 weeks (P < 0.05), and lower concentrations of short chain fatty acids (SCFAs) in cecal digesta (P = 0.0003). These findings suggest that the consumption of PDX and lactitol may upregulate salivary IgA secretion possibly by stimulating absorption of SCFAs produced by cecal fermentation. Thus, continuous ingestion of PDX and lactitol for up to 4 weeks could increase salivary IgA and promote immune defense against pathogen invasion through the oral route.