Periodontal status is associated with oral function in community-dwelling older adults, independent of dentition status.

OBJECTIVE: To determine whether periodontal status is associated with oral function, including masticatory performance and occlusal force, among community-dwelling older adults. BACKGROUND: Although a potential association between periodontal status and oral function has been reported, variations in the root surface area (RSA) of each tooth have not been considered. METHODS: We used data from a population-based study involving community-dwelling older adults. The RSA with periodontal ligament (RSA-PL), which quantifies the RSA attached to the periodontal ligament and alveolar bone, was calculated based on full-mouth periodontal examination. Masticatory performance was assessed using spectrophotometric measurement of the color (a* value) of color-changing chewing gum. The bilateral maximal occlusal force (MOF) was measured using a pressure-sensitive sheet and dedicated software. The associations of the RSA-PL, a quantitative marker of periodontal tissue support, with the a* value and MOF were assessed using linear regression models. RESULTS: The analyses included data from 250 adults [60.8% women; age, mean (standard deviation) 82.5 (5.0) years]. On average, the study participants had an RSA-PL of 26.3 cm2 , a* value of 25.0, and an MOF value of 555.1 N. After adjustments for potential confounders, including dentition status, age, sex, dental visit regularity, smoking status, physical activity level, depressive symptoms, a history of stroke or diabetes mellitus, and body mass index, the RSA-PL was found to be associated with the a* value [coefficient (per 1 cm2 increase): 0.16, 95% confidence interval (CI) 0.10-0.22)] and MOF (coefficient: 9.2, 95% CI 5.3-13.1). CONCLUSION: This study demonstrated that greater amounts of remaining tooth-supporting structures, indicated by higher RSA-PL values, were associated with better masticatory performance and a higher occlusal force among community-dwelling older adults.

Xerostomia aggravates ligation-induced peri-implantitis: A preclinical in vivo study.

OBJECTIVES: Previous studies have indicated that xerostomia is a critical factor affecting periodontitis; nonetheless, it is controversial whether xerostomia impairs peri-implant tissue. The objective of this experimental study was to evaluate the effect of xerostomia on the peri-implant hard and soft tissues in the rat model. MATERIALS AND METHODS: Implants were placed in bilateral maxillae of male Wistar rats. The animals underwent submandibular and sublingual gland resection on both sides (DRY group) or sham operation (CTR group). Silk ligatures were placed around one side of abutments, which were randomly selected in each animal. The effects of xerostomia were assessed using micro-CT, histological analysis, real-time PCR, and 16S rRNA-based metagenomic analysis. RESULTS: Ligation with silk thread caused bone resorption around implants. Although xerostomia itself did not induce bone resorption, it significantly enhanced silk ligature-mediated bone resorption around implants. Histological analysis and real-time PCR indicated that xerostomia induced inflammation and osteoclastogenesis around implants with silk ligatures. Furthermore, it altered the microbiota of the plaque on the silk thread around implants. CONCLUSION: Xerostomia accelerates mucosal inflammation and osteoclastogenesis, which aggravates bone resorption around implants.

The relationship between masticatory performance and intakes of foods and nutrients in Japanese male workers: A cross-sectional study.

BACKGROUND: Although many studies have been conducted on the relationship between masticatory performance and nutrient ingestion in the elderly, few large-scale studies have been carried out using relatively young individuals. OBJECTIVES: The objective of this study was to clarify the association between the masticatory performance evaluated by the gummy-jelly test, not by visual examination, and nutrient ingestion state based on the brief self-administered diet history questionnaire (BDHQ). METHODS: This was a cross-sectional survey of 540 male workers. Somatometry, blood pressure measurement, blood test and medical interview were performed as a periodic health check-up. In the dental check-up, an oral examination, gummy-jelly test (glucosensor) and survey of ingested food and nutrients using BDHQ were performed. The participants were classified into two groups with low and normal values of masticatory performance. Participants with a score on the gummy-jelly test below 150 mg/dL or 150 mg/dL or higher were included in the low and normal groups, respectively. RESULTS: Two hundred and forty-eight participants (45.8%) had low masticatory performance, and 292 (53.2%) had normal masticatory performance. The intakes of some minerals and vitamins, such as calcium, vitamin D, vitamin B2 , small fish with bones and non-oily fish, were significantly lower in the low masticatory group than in the normal group. In contrast, the intake of sugar for coffee and tea and that of chicken were significantly higher in the low masticatory group than in the normal group. CONCLUSION: This study suggested that low masticatory performance can affect nutrient intake, which may cause non-communicable diseases.

Combined effect of poor appetite and low masticatory function on sarcopenia in community-dwelling Japanese adults aged ≥ 75 years: A 3-year cohort study.

OBJECTIVE: This study aimed to investigate the longitudinal association of the combination of poor appetite (PA) and low masticatory function (LMF) with sarcopenia in community-dwelling older adults. METHODS: In total, 173 community-dwelling Japanese adults aged ≥ 75 years participated in the 3-year cohort study. Appetite assessment using the Simplified Nutritional Appetite Questionnaire (SNAQ) and masticatory function assessment using spectrophotometric measurement of differences in gum colour before and after masticating colour-changeable chewing gum (ΔE*ab) were performed at baseline. SNAQ score of ≤ 14 was defined as PA. The lowest tertile of ΔE*ab was defined as LMF. Follow-up examinations were administered annually over a 3-year period to determine sarcopenia incidence, which was defined by the criteria proposed by the Asian Working Group for Sarcopenia. Adjusted hazard ratios (HRs) of sarcopenia incidence according to the presence of PA and LMF were calculated using Cox proportional hazards regression models. RESULTS: At baseline, 81 participants (46.8%) had neither PA nor LMF, 34 (19.7%) had PA alone, 35 (20.2%) had LMF alone, and 23 (13.3%) had both PA and LMF. On follow-up, 31 participants (17.9%) developed sarcopenia. After adjusting for covariates, the adjusted HR for sarcopenia in participants with both PA and LMF was 4.4 (95% confidence interval = 1.6-12.2) compared with those without PA or LMF. PA or LMF alone was not significantly associated with sarcopenia development. CONCLUSIONS: Coexisting PA and LMF increase the risk of sarcopenia development among community-dwelling Japanese adults aged ≥ 75 years.

The apical anion exchanger Slc26a6 promotes oxalate secretion by murine submandibular gland acinar cells.

The solute carrier family 26 (SLC26) gene family encodes at least 10 different anion exchangers. SLC26 member 6 (SLC26A6 or CFEX/PAT-1) and the cystic fibrosis transmembrane conductance regulator (CFTR) co-localize to the apical membrane of pancreatic duct cells, where they act in concert to drive HCO3- and fluid secretion. In contrast, in the small intestine, SLC26A6 serves as the major pathway for oxalate secretion. However, little is known about the function of Slc26a6 in murine salivary glands. Here, RNA sequencing-based transcriptional profiling and Western blots revealed that Slc26a6 is highly expressed in mouse submandibular and sublingual salivary glands. Slc26a6 localized to the apical membrane of salivary gland acinar cells with no detectable immunostaining in the ducts. CHO-K1 cells transfected with mouse Slc26a6 exchanged Cl- for oxalate and HCO3-, whereas two other anion exchangers known to be expressed in salivary gland acinar cells, Slc4a4 and Slc4a9, mediated little, if any, Cl-/oxalate exchange. Of note, both Cl-/oxalate exchange and Cl-/HCO3- exchange were significantly reduced in acinar cells isolated from the submandibular glands of Slc26a6-/- mice. Oxalate secretion in submandibular saliva also decreased significantly in Slc26a6-/- mice, but HCO3- secretion was unaffected. Taken together, our findings indicate that Slc26a6 is located at the apical membrane of salivary gland acinar cells, where it mediates Cl-/oxalate exchange and plays a critical role in the secretion of oxalate into saliva.

Submandibular gland-specific inflammaging-induced hyposalivation in the male senescence-accelerated mouse prone -1 line (SAM-P1).

Aging has pronounced effects on mammalian tissues and cells, but the impacts of aging on salivary gland function are relatively unknown. This study aims to evaluate the effects of aging on submandibular gland (SMG) and parotid gland (PG) functions in the male senescence-accelerated mouse. In vivo analysis at the systemic level revealed that salivary secretion induced by pilocarpine, a muscarinic agonist, from the SMG was significantly decreased in aged mice, whereas salivary secretion from the PG was not affected. To evaluate organ-level function, the SMG was perfused with the muscarinic agonists carbachol and calcium ionophore A23187 ex vivo to induce salivary secretion, and decreased saliva production was also observed in the aged SMG. Histological analysis revealed the presence of CD4-positive lymphocytes infiltrating the aged SMG. Furthermore, real-time PCR revealed that the aged SMG exhibited accelerated cell aging, increased levels of the inflammatory cytokine interleukin-6, and decreased mRNA levels of the water channel protein aquaporin-5 (AQP5). In summary, these results demonstrate that SMG function in aged mice was diminished, and that cell senescence, chronic inflammation, and the decreased gene expression of AQP5 are the likely causes of hyposalivation in the SMG of aged mice.

Is Anterior Guidance a Key Factor on Planning Implant Treatment for Free-End Missing in the Posterior Mandible?

To perform safe implant treatment, the anatomical structure and bone quality at implant placement sites are evaluated based on a patient's computerized tomography (CT) data, but there is no definite method to determine placement sites and the appropriate number of implants. The objective of this study was to investigate the influence of the number and arrangement of implants on the stress distribution in 3-unit posterior fixed partial dentures for the posterior mandible by mechanical analysis using the finite element method. Three-dimensional finite element analysis models were constructed from the CT data of a patient with missing mandibular teeth (Nos. 35, 36, 37). Implant placement was simulated under various conditions. Superstructures were connected and fixed with a titanium frame. As the loading conditions, 400 N vertical and lateral loads (45° on the lingual side and 45° on the buccal side) were applied to the upper areas of Nos. 35, 36, and 37, and the stress distribution and frame displacement were evaluated. When a vertical force was applied, no difference of the von Mises stress was noted among the 5 experimental conditions. When lateral force was applied from the lingual and buccal sides at 45°, the stress was higher than that induced by vertical force under all conditions, and it was especially high under mesial and distal cantilever conditions. When displacement of the titanium frame was measured, the displacement caused by lateral force was greater than that due to vertical force. In addition, comparison between long and short distal cantilever bridges revealed that displacement of the titanium frame tended to be smaller when the short cantilever was used. These findings suggested that the stress on peri-implant tissues and displacement of the titanium frame vary depending on the configuration and number of implants, with greater stress and more marked displacement of the titanium frame being induced by lateral force when the number of implants is reduced and a cantilever bridge is selected.

Promotion of insulin-induced glucose uptake in C2C12 myotubes by osteocalcin.

A close relationship between the bone and systemic glucose metabolism has recently been the center of attention, since the uncarboxylated form of osteocalcin (GluOC), a bone-derived protein, but not the γ-carboxylated form, is involved in glucose metabolism. However, the analysis of GluOC effect using isolated organs and related cell lines are required to understand its roles in a whole systemic metabolic status. In the present study, we examined the effect of GluOC on cell lines derived from skeletal muscle to explore the mechanisms by which GluOC regulates glucose uptake. In the differentiated C2C12 myotubes, GluOC dose-dependently induced the phosphorylation of ERK without affecting intracellular cAMP and Ca(2+) levels. This effect was inhibited by U0126, an inhibitor of ERK kinase (MEK). Additionally, U73122, an inhibitor of phospholipase C tended to inhibit it as well. Furthermore, cell treatment with GluOC for a long period promoted insulin-induced Akt phosphorylation and glucose uptake in the myotubes, which was abolished by ERK signaling inhibition. These results indicate that GluOC does not triggered Akt phosphorylation and glucose uptake by itself but promotes insulin-induced glucose uptake in myotubes, probably by up-regulating Akt signaling through ERK activation.

A prospective study of changes in oral health-related quality of life during immediate function implant procedures for edentulous individuals.

OBJECTIVE: The aim of this prospective clinical study was to evaluate longitudinal changes in oral health-related quality of life (OHRQoL) attributable to fixed dental prostheses during All-on-4(®) treatment in one or both jaws. MATERIALS AND METHODS: Ten patients underwent placement of four or six endosteal dental implants on the basis of the All-on-4(®) treatment concept in the edentulous maxilla or both jaws and immediate loading with acrylic interim prostheses. The prostheses were replaced after 3-6 months, and definitive prostheses with titanium framework and reinforced resin facing were fixed after another 5 months or more. The subjects completed the shortened Japanese version of the Oral Health Impact Profile (OHIP-J14) before the surgery (T0), 1 week after the initial (T1) and secondary (T2) interim prostheses were placed, and 3 months after definitive prosthesis placement (T3). Complete data of nine subjects were analyzed with the Wilcoxon signed-rank test. RESULTS: The total OHIP-J14 score significantly reduced only at T3 (P < 0.05). "Functional limitation," "physical pain," "physical disability," and "psychological disability" scores significantly decreased at T3, and "psychological discomfort" scores also significantly dropped at T2. "Social disability" and "handicap" scores remained unchanged throughout. CONCLUSION: Fixed definitive prostheses with metal framework are more effective than fixed all-acrylic prostheses in improving OHRQoL during All-on-4(®) treatment.

Soft tissue biological response to zirconia and metal implant abutments compared with natural tooth: microcirculation monitoring as a novel bioindicator.

INTRODUCTION: Zirconia is often used for implant abutments for esthetics. The aim of this clinical study was to compare the effects of zirconia and metal abutments on periimplant soft tissue. MATERIALS AND METHODS: Ten maxillary anterior implant patients, 5 with metal abutments and 5 with zirconia abutments, were enrolled in this trial. The soft tissue around the implant abutments was evaluated by 2-dimensional laser speckle imaging and thermography. The blood flow in soft tissue around natural teeth was also measured to correct for differences among the subjects. RESULTS: Significantly greater blood flow was detected in the zirconia abutment group (95.64 ± 5.17%) relative to the metal abutment group (82.25 ± 8.92%) in free gingiva (P = 0.0317). Reduced blood flow (by almost 18%) was detected in the tissue surrounding metal abutments compared with the tissue surrounding natural teeth. The surface temperature showed no significant difference for all measurements. CONCLUSIONS: These results suggest that blood flow in tissue surrounding zirconia abutments is similar to that in soft tissue around natural teeth. Moreover, zirconia abutments could be advantageous for the maintenance of immune function by improving blood circulation.

Na(+)-K(+)-2Cl(-) cotransporter-mediated fluid secretion increases under hypotonic osmolarity in the mouse submandibular salivary gland.

Water-handling epithelia are sensitive to the osmotic environment. In this study, the effects of a hypo-osmotic challenge on carbachol (CCh)-induced fluid secretion was investigated using an ex vivo submandibular gland perfusion technique and intracellular pH and Ca(2+) measurements. The osmolality of the perfusion solution was altered to examine the response of the gland to a hypotonic challenge. The flow rate was increased by 34% with a 30% hypotonic solution (225 mosmol/kgH2O), although the Ca(2+) response was unchanged. The lowering of the external Cl(-) by 50% abolished this increase in the 30% hypotonic solution. Furthermore, bumetanide, an inhibitor of the Na(+)-K(+)-2Cl(-) cotransporter (NKCC1), completely inhibited the fluid secretion increase caused by the 30% hypotonic solution, and both the total amount of fluid and the flow rate were identical to those of the isotonic solution. This finding was confirmed by measuring the NKCC1 bumetanide-dependent NH4 (+) transport; Na(+)-K(+)-2Cl(-) transport was upregulated >40% by a 30% hypotonic challenge. Therefore, the increase in CCh-induced fluid secretion in response to hypotonic conditions can be attributed, to a large extent, to the specific activation of the NKCC1.

Development of zirconia-based polymer-infiltrated ceramic network for dental restorative material.

Polymer-infiltrated ceramic network (PICN) materials have gained considerable attention as tooth restorative materials owing to their mechanical compatibility with human teeth. However, the mechanical strength of contemporary PICN materials is lower than those of conventional resin composites and ceramics. This study aims to develop novel high-strength PICN for use as a dental restorative material. Zirconia-based PICN (EXP) was fabricated using 3 mol% yttria tetragonal polycrystalline zirconia powder and resin monomers via slip casting, followed by sintering and polymer infiltration. Comprehensive analyses of the microstructure, mechanical properties, and physicochemical properties of EXP were performed using scanning electron microscopy with energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, inorganic content measurements, three-point bending test, Vickers hardness test, two-body wear test, shear bond strength (SBS) test, surface free energy analysis, and water sorption/solubility test. Commercially available computer-aided design/computer-aided manufacturing (CAD/CAM) materials, including resin composite (CERASMART), silicate-based PICN (ENAMIC), and zirconia ceramic (e.max ZirCAD), were used for comparison. The analyses highlight the dual network structure of EXP, which comprised a zirconia skeleton and an infiltrated resin phase. EXP exhibits a flexural strength of 346.0 ± 46.0 MPa, flexural modulus of 44.0 ± 3.7 GPa, and Vickers hardness of 440.1 ± 51.2 VHN. The mechanical properties of EXP are significantly higher than those of CERASMART and ENAMIC but lower than those of ZirCAD. Notably, the EXP hardness closely mimics that of the human enamel. The wear volume, SBS, and water sorption/solubility of EXP are comparable to those of CERASMART and ENAMIC. Therefore, EXP has potential applications as a tooth restorative material.

Impact of CAD/CAM Material Thickness and Translucency on the Polymerization of Dual-Cure Resin Cement in Endocrowns.

The objective of this study is to evaluate the impact of the thickness and translucency of various computer-aided design/computer-aided manufacturing (CAD/CAM) materials on the polymerization of dual-cure resin cement in endocrown restorations. Three commercially available CAD/CAM materials-lithium disilicate glass (e.max CAD), resin composite (CERASMART), and a polymer-infiltrated ceramic network (ENAMIC)-were cut into plates with five different thicknesses (1.5, 3.5, 5.5, 7.5, and 9.5 mm) in both high-translucency (HT) and low-translucency (LT) grades. Panavia V5, a commercial dual-cure resin cement, was polymerized through each plate by light irradiation. Post-polymerization treatment was performed by aging at 37 °C for 24 h under light-shielding conditions. The degree of conversion and Vickers hardness measurements were used to characterize the polymerization of the cement. The findings revealed a significant decrease in both the degree of conversion and Vickers hardness with increasing thickness across all CAD/CAM materials. Notably, while the differences in the degree of conversion and Vickers hardness between the HT and LT grades of each material were significant immediately after photoirradiation, these differences became smaller after post-polymerization treatment. Significant differences were observed between samples with a 1.5 mm thickness (conventional crowns) and those with a 5.5 mm or greater thickness (endocrowns), even after post-polymerization treatment. These results suggest that dual-cure resin cement in endocrown restorations undergoes insufficient polymerization.

Application of anti-vascular endothelial growth factor antibody restores the function of saliva secretion in a type 2 diabetes mouse model.

OBJECTIVES: Xerostomia, a common complication of type 2 diabetes, leads to an increased risk of caries, dysphagia, and dysgeusia. Although anti-vascular endothelial growth factor (VEGF) antibodies, such as ranibizumab (RBZ), have been used to treat diabetic retinopathy, their effects on the salivary glands are unknown. This study evaluated the effects of RBZ on salivary glands to reduce inflammation and restore salivary function in a mouse model of type 2 diabetes. METHODS: Male KK-Ay mice with type 2 diabetes (10-12 weeks old) were used. The diabetes mellitus (DM) group received phosphate-buffered saline, while the DM + RBZ group received an intraperitoneal administration of RBZ (100 µg/kg) 24 h before the experiment. RESULTS: Ex vivo perfusion experiments showed a substantial increase in salivary secretion from the submandibular gland (SMG) in the DM + RBZ group. In addition, the mRNA expression levels of TNF-α and IL-1ß were considerably lower in this group. In contrast, those of aquaporin 5 were substantially higher in the DM + RBZ group, as revealed by quantitative reverse transcription PCR. Furthermore, the number of lymphocyte infiltration spots in the SMG was notably lower in the DM + RBZ group. Finally, intracellular Ca2+ signaling in acinar cells was considerably higher in the DM + RBZ group than that in the DM group. CONCLUSION: Treating a type 2 diabetic mouse model with RBZ restored salivary secretion through its anti-inflammatory effects.

Diagnostic potential of endothelin-1 in peri-implant diseases: a cross-sectional study.

PURPOSE: This study aimed to evaluate the potential of Endothelin-1 (ET-1), a peptide derived from vascular endothelial cells, as a biomarker for diagnosing peri-implant diseases. METHODS: A cohort of 29 patients with a total of 76 implants was included in this study and subsequently divided into three groups based on peri-implant clinical parameters and radiographic examination: healthy (peri-implant health) (n = 29), mucositis (n = 22), and peri-implantitis (n = 25) groups. The levels of ET-1 (ρg/site) and interleukin (IL)-1ß (ρg/site) in peri-implant sulcus fluid (PISF) samples were determined using enzyme immunoassay. Statistical analyses were conducted using Kruskal-Wallis and Steel-Dwass tests. Logistic regression and receiver operating characteristic (ROC) curve analyses were performed to evaluate the diagnostic performance of the biomarkers. RESULTS: ET-1 levels were significantly elevated in the peri-implantitis group compared to those in the healthy group, and were highest in the peri-implant mucositis group. Additionally, IL-1ß levels were significantly higher in the peri-implantitis group than those in the healthy group. ROC curve analysis indicated that ET-1 exhibited superior area under the curve values, sensitivity, and specificity compared to those of IL-1ß. CONCLUSIONS: Our findings suggest that the presence of ET-1 in PISF plays a role in peri-implant diseases. Its significantly increased expression in peri-implant mucositis indicates its potential for enabling earlier and more accurate assessments of peri-implant inflammation when combined with conventional examination methods.

Mechanical insights into jawbone characteristics under chronic kidney disease: A comprehensive nanoindentation approach.

The mechanical properties of the jawbone play a critical role in determining the successful integration of dental prostheses. Chronic kidney disease (CKD) has been identified to abnormally accelerate bone turnover rates. However, the impact of CKD on the mechanical characteristics of the jawbone has not been extensively studied. This study sought to evaluate the time-dependent viscoelastic behaviors of rat jawbones, particularly in the scenarios both with and without CKD. We hypothesized that CKD might compromise the bone's innate toughening mechanisms, potentially owing to the time-dependent viscoelasticity of the bone matrix proteins. The maxillary and mandibular bones of Wistar rats were subjected to nanoindentation and Raman micro-spectroscopy. Load-hold-displacement curves from the cortical regions were obtained via nanoindentation and were mathematically characterized using a suitable viscoelastic constitutive model. Raman micro-spectroscopy was employed to identify nuanced vibrational changes in local molecular structures induced by CKD. The time course of indenter penetration onto cortical bones during the holding stage (creep behavior) can be mathematically represented by a series arrangement of the Kelvin-Voigt bodies. This configuration dictates the overall viscoelastic response observed during nanoindentation tests. The CKD model exhibited a reduced extent of viscoelastic contributions, especially during the initial ramp loading phase in both the maxillary and mandibular cortical bones. The generalized Kelvin-Voigt model comprises 2 K-Voigt elements that signify an immediate short retardation time (τ1) and a subsequent prolonged retardation time (τ2), respectively. Notably, the mandibular CKD model led to an increase in the delayed τ2 alongside an increase in non-enzymatic collagen cross-linking. These suggest that, over time, CKD diminishes the bone's capability for supplementary energy absorption and dimensional recovery, thus heightening their susceptibility to fractures.

Chronic kidney disease compromises structural and mechanical properties of maxillary cortical bone in a rat model.

PURPOSE: This study aimed to investigate the effects of chronic kidney disease (CKD) on the structural and mechanical properties of the maxillary and mandibular cortical bone. METHODS: The maxillary and mandibular cortical bones from CKD model rats were used in this study. CKD-induced histological, structural, and micro-mechanical alterations were assessed using histological analyses, micro-computed tomography (CT), bone mineral density (BMD) measurements, and nanoindentation tests. RESULTS: Histological analyses indicated that CKD caused an increase in the number of osteoclasts and a decrease in the number of osteocytes in the maxilla. Micro-CT analysis revealed that CKD induced a void volume/cortical volume (%) increase, which was more remarkable in the maxilla than in the mandible. CKD also significantly decreased the BMD in the maxilla. In the nanoindentation stress-strain curve, the elastic-plastic transition point and loss modulus were lower in the CKD group than that in the control group in the maxilla, suggesting that CKD increased micro fragility of the maxillary bone. CONCLUSIONS: CKD affected bone turnover in the maxillary cortical bone. Furthermore, the maxillary histological and structural properties were compromised, and micro-mechanical properties, including the elastic-plastic transition point and loss modulus, were altered by CKD.

Comparison of plaque accumulation and soft-tissue blood flow with the use of full-arch implant-supported fixed prostheses with mucosal surfaces of different materials: a randomized clinical study.

OBJECTIVE: The aims of this clinical study were to determine differences in plaque accumulation and to compare the effects of reinforced composite resin and titanium on peri-implant soft-tissue and residual-ridge inflammation. MATERIAL AND METHODS: A total of 19 subjects were enrolled in this clinical trial; 10 jaws had implant-supported fixed prostheses with composite resin mucosal surfaces, 11 jaws had titanium prostheses fabricated by computer-aided design/computer-aided manufacture (CAD/CAM), and 6 jaws had acrylic resin prostheses. Plaque area indexes (PAIs) were calculated on the mucosal surfaces of prostheses, and blood flow in the mucosa was captured with two-dimensional laser speckle imaging to evaluate residual-ridge inflammation. Subjects were educated about oral hygiene and reevaluated after 3 months. RESULTS: The PAI was significantly lower on titanium mucosal surfaces than on reinforced composite resin surfaces at the initial and second measurements (initial, P = 0.0052; second, P = 0.0044). Self-curing acrylic resin surfaces did not show any significant difference when compared with reinforced resin or titanium. Blood flow was significantly lower in mucosa contacting titanium surfaces than in mucosa contacting reinforced composite resin surfaces at the initial measurement (P = 0.0330). Although subjects were instructed about plaque control after the initial measurement, PAIs indicated that the difference between the two materials could not be overcome. CONCLUSION: In terms of oral hygiene and mucosal inflammation, titanium was superior to reinforced composite resin in implant-supported fixed prostheses for edentulous subjects, and the short-term use of acrylic resin was superior to the use of reinforced composite resin.

Effects of thirty-times chewing per bite on secretion of glucagon-like peptide-1 in healthy volunteers and type 2 diabetic patients.

Glucagon-like peptide 1 (GLP-1) is secreted from the small intestine to the blood in response to glucose intake during a meal; however, it is not known whether mastication affects GLP-1 secretion. Here, we examined the relationship between mastication and GLP-1 secretion, along with postprandial blood glucose and insulin concentrations. We compared the levels of blood glucose, serum insulin, and plasma active GLP-1 concentrations after young healthy volunteers ate a test meal either by usual eating (control) or in one of three specified ways: 1. unilateral chewing, 2. quick eating, 3. 30-times chewing per bite. Ten volunteers participated in each of the three groups. Plasma active GLP-1 concentrations did not change by unilateral chewing or quick eating, but did increase by the third method, without affecting the concentrations of blood glucose or serum insulin. Next, we tested whether 30-times chewing per bite increased plasma active GLP-1 concentrations in 15 patients with type 2 diabetes mellitus, but there was no difference in results between usual eating and 30-times chewing per bite. This is a pilot trial with a small number of subjects, but is the first study to investigate the relationships between various styles of mastication and the GLP-1 secretion in young healthy volunteers and type 2 diabetic patients.