Synthesis of ß-tricalcium phosphate by modifying the heating process of a dental casting mold.

This study investigated a novel method for artificial synthesis of ß-tricalcium phosphate (ß-TCP). The binder of the phosphate-bonded investment was replaced with calcium oxide instead of magnesium oxide and sintered in an electric furnace. The water/powder mixing ratio for hardening was determined using preliminary experiments. Thermal analysis was performed to check the thermal behavior of the sample tested. In addition, the fired sample was analyzed using an X-ray diffraction apparatus to identify the compounds after sintering. The hardened sample exhibited multiple compounds, including unreacted components, post which, new compounds were generated by heating. Peaks of calcium pyrophosphate and ß-TCP were confirmed at 800ºC and 1,300ºC, respectively. ß-TCP could be easily synthesized within the limited study by sintering at 1,300ºC both monoammonium phosphate and calcium oxide. Experimental results suggest that ß-TCP can be easily synthesized by simulating the conventional dental casting process.

Functional tooth number in the posterior region associated serum ucOC levels.

PURPOSE: The purpose of this study was to investigate serum undercarboxylated osteocalcin (ucOC) levels in partially edentulous patients scheduled to receive implant treatment and determine the association between ucOC levels, vegetable intake, vitamin K, dietary fiber intake, and functional tooth number in the posterior region (p-FTN). METHODS: A total of 46 patients (20 male and 26 female, 61.9 ± 12.7 years old) were included. The association among serum ucOC levels, vegetable intake, vitamin K and dietary fiber intake was assessed using Spearman's rank correlation coefficient and binary logistic regression analysis. RESULTS: In total, 35% of patients (16/46 subjects) showed an abnormally high ucOC level (≧ 4.5 ng/mL). p-FTN showed a weak positive correlation with vegetable intake, vitamin K and dietary fiber intake (r = 0.28, 0.21, and 0.14, respectively) and a significant negative correlation with ucOC levels (r = - 0.51). Multivariate analysis demonstrated that p-FTN as well as vitamin K intake showed a significant negative association with serum ucOC levels. CONCLUSIONS: More than one-third of patients showed abnormally high ucOC levels. p-FTN showed a negative association with serum ucOC levels, which indicated the possibility that oral status affected bone quality.

Functional involvement of acid-sensing ion channel 3 in the swallowing reflex in rats.

BACKGROUND: Difficulty swallowing represents a major health problem. Swallowing function is improved by incorporating weak acids in suspensions/food boluses, implicating acid-sensing ion channels (ASICs) in the swallowing reflex. However, the functional involvement of ASICs in the swallowing reflex has not been fully elucidated. METHODS: We localized ASIC3s in swallowing-related regions innervated by the superior laryngeal nerves (SLNs) and those in the nodose-petrosal-jugular ganglionic complex (NPJc) and examined their functional involvement in evoking the swallowing reflex in rats. KEY RESULTS: We localized ASIC3s on epithelial cells and nerve fibers in swallowing-related regions innervated by the SLNs. In the NPJc, around half of the SLN-afferent neurons expressed ASIC3. Two-thirds of ASIC3s were localized on unmyelinated neurons in the nodose and petrosal ganglia. In the jugular ganglia, they were equally distributed on unmyelinated and myelinated neurons. Topical application of a synthetic non-proton ASIC3 activator, 2-guanidine-4-methylquinazoline (GMQ), and its natural endogenous ligand agmatine (a metabolite of the amino acid arginine) in swallowing-related regions evoked a considerable number of swallowing reflexes. Increasing the concentration of GMQ and agmatine up to a certain concentration increased the number of evoked reflexes and shortened the interval between the evoked reflexes. Agmatine was less potent than GMQ in its ability to evoke swallowing reflexes. Prior topical application of an ASIC3 antagonist significantly attenuated the number of GMQ- and agmatine-evoked swallowing reflexes. CONCLUSIONS & INFERENCES: Acid-sensing ion channel 3s localized on nerves and epithelial cells in swallowing-related regions are functional in evoking the swallowing reflex and activation of these channels via a pharmacological agonist appears to improve swallowing behavior.

Sexual dimorphisms in the transcriptomes of murine salivary glands.

Transcriptional profiling identified 933 sexually dimorphic genes out of the 14 371 protein-coding genes expressed in the three major murine salivary glands: parotid, sublingual, and submandibular. Most (89%) sex-specific genes were enriched in a single gland, while only 0.5% of the sexually dimorphic genes were enriched in all glands. The sublingual gland displayed a strong male sex bias (94% of sex-enriched genes), while a sex preference was not obvious in the parotid or submandibular glands. A subset of transcription factor genes was correlated with the expression of gland-specific, sex-enriched genes. Higher expression of Cftr chloride and Scnn1 sodium channels in the male submandibular correlated with greater NaCl reabsorption. In conclusion, adult salivary glands display sex- and gland-specific differences in gene expression that reflect their unique functional properties.

Salivary gland hypofunction in KK-Ay type 2 diabetic mice.

BACKGROUND: Hypofunction of different organs in the body is associated with diabetes, including in the oral cavity. Diabetes is often associated with xerostomia, but the underlying mechanism is not well characterized. Thus, the mechanisms underlying diabetes-induced xerostomia were investigated in this study in KK-A y mice as an experimental model of type 2 diabetes. METHODS: The mechanisms involved in diabetes-induced xerostomia were investigated using the ex vivo glandular perfusion technique, histological analysis, and immunohistochemical and intracellular signaling analyses. RESULTS: Ex vivo submandibular gland secretions from KK-Ay mice decreased by 30% following stimulation with 0.3 µmol/L carbachol (CCh), a cholinergic agonist. Acinar cell weight was comparable between KK-Ay and control mice, whereas duct cell weight was significantly greater in KK-Ay mice. Concentrations of Na+ and Cl- in the secreted saliva decreased significantly in KK-Ay mice, supporting the finding of increased ductal tissue in KK-Ay mice. Immunohistochemistry revealed no significant differences between KK-Ay and control mice in terms of the expression of Cl- and water channels, Na+ -K+ -2Cl- cotransporters, and membrane proteins critical for fluid secretion. Cellular signaling analysis revealed that the increase in [Ca2+ ]i in response to 0.3 µmol/L CCh was reduced by 30% in KK-Ay mice, although there was no significant difference in the thapsigargin (1.0 µmol/L)-induced increase in store-depleted calcium between KK-Ay and control mice. CONCLUSIONS: These results demonstrate that submandibular fluid secretion is diminished in KK-Ay mice because of a diminished increase in [Ca2+ ]i . Duct cell weight increased in KK-Ay mice, possibly leading to increased ion reabsorption and thus decreased Na+ and Cl- concentrations in the secreted saliva.

Changes in oral health-related quality of life during implant treatment in partially edentulous patients: A prospective study.

PURPOSE: The aim of this prospective study was to evaluate the changes in oral health-related quality of life (OHRQoL) during implant treatment for partially edentulous patients, and to evaluate the influence of the type of partially edentulous arch. METHODS: Twenty patients with a small number of lost teeth (fewer than 4 teeth) who underwent implant treatment were selected. Chronological QOL change during implant treatment was measured. The subjects completed the shortened Japanese version of the Oral Health Impact Profile (OHIP-J14) before the surgery (T0), 1 week after the surgery (T1), 1 week after interim prosthesis placement (T2), and 1 week after definitive prosthesis placement (T3). Complete data of the twenty subjects were analyzed with the Wilcoxon signed-rank test. RESULTS: The total OHIP-J14 score was significantly reduced only at T3 (P<0.05). "Physical pain" and "Physical disability" scores significantly decreased at T3, and "Psychological discomfort" scores also significantly dropped at T2. However, "Functional limitation" scores significantly increased at T1. "Psychological disability", "Social disability", and "Handicap" scores remained the same. On the other hand, in the comparison depending on the type of partially edentulous arch, the total OHIP-J14 score significantly decreased at T3 in the unilateral free-end edentulous space, whereas no significant difference was observed in the bounded edentulous space. CONCLUSION: Although there is a temporary functional limitation after implant placement in overall OHRQoL improvement was observed after the definitive prosthesis placement. Moreover, implant treatment was more effective in the unilateral free-end edentulous space.

Strategies for alveolar ridge reconstruction and preservation for implant therapy.

PURPOSE: In dental implant treatment, ridge preservation and immediate or early implant placement are recommended to minimize bone resorption after tooth extraction and achieve esthetic outcomes. However, there is no consensus concerning the efficacy of this surgical method. There is also no consensus on the efficacy of bone and soft tissue grafts and surgical methods for alveolar ridge reconstruction. STUDY SELECTION: This paper reports ridge alteration in the anterior maxilla after tooth extraction, and summarizes the efficacy of various ridge preservation methods and immediate or early implant placement as alveolar ridge preservation methods to minimize bone resorption after tooth extraction. The advantages and complications of alveolar ridge reconstruction methods, and the efficacy and surgical method of soft tissue graft are reviewed. RESULTS: The anterior maxilla is in the esthetic zone, and the thickness of the bone on the labial side around the natural tooth is less than 1mm in many cases. Therefore, it is impossible to prevent bone resorption completely, even if ridge preservation and immediate or early implant placement are performed after tooth extraction. It is necessary to obtain stable and long-term esthetics by combining connective tissue and free gingival grafts, in addition to hard tissue augmentation. CONCLUSIONS: It is important to consider the burden and level of satisfaction of patients, such as in terms of donor site morbidity in hard and soft tissue grafting, and to pay attention to appropriate indications to avoid overtreatment.

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.

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.

Non-randomized controlled prospective study on perioperative levels of stress and dysautonomia during dental implant surgery.

PURPOSE: The purpose of this study was to compare pre- and postoperative autonomic activities and changes in salivary stress biomarkers between patients who received only local anesthesia and those who received local anesthesia together with intravenous sedation in dental implant surgery. METHODS: A total of 21 patients were enrolled in this non-randomized controlled prospective study; 7 subjects underwent implant surgery under local anesthesia with intravenous sedation and 14 subjects underwent surgery under only local anesthesia. Stress was evaluated by measuring salivary levels of chromogranin A (CgA) and a spectral analysis of heart rate variability (HRV) at baseline (on a day other than the day of surgery), 1h preoperatively, and 1h postoperatively. HRV analysis yields low- (LF) and high-frequency (HF) components, the LF/HF ratio, and the component coefficient of variance (CCV[HF]), which provide indices of sympathetic and parasympathetic regulatory activity. RESULTS: CgA levels were significantly higher (p<0.05) at baseline in patients who received sedation than those who did not, but CgA levels did not differ prior to surgery. Also, the values of most parameters, including LF, HF, LF/HF (L/H), and CCV(HF), did not significantly differ between groups or among the three time points. Only ΔL/H and ΔCCV(HF) were significantly lower (p<0.05) at 1h preoperatively in patients who received sedation than those who received only local anesthesia. CONCLUSIONS: CgA levels were high in both groups immediately before surgery, and thus CgA values immediately before surgery may not be a reliable indicator of the need for intravenous sedation. Also, spectral analysis of HRV, especially ΔL/H and ΔCCV(HF), could be useful for assessing tension and anxiety.

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.

Low-intensity pulsed ultrasound enhances palatal mucosa wound healing in rats.

PURPOSE: Low-intensity pulsed ultrasound (LIPUS) has been used in fracture treatment to shorten the time needed for biological wound healing. However, the influence of LIPUS exposure on oral wound healing has not been sufficiently investigated. This study was conducted to evaluate low-intensity pulsed ultrasound on wound healing in palatal excisional wounds of rats. METHODS: Excisional wounds, 5 mm in diameter, were made in the center of the palate of rats. Animals were divided into four experimental and control groups (1-week after LIPUS exposure, 1-week control, 2-week after LIPUS exposure, and 2-week control). The affected area in the experimental group was exposed to LIPUS, daily frequency: 3 MHz, intensity: 160 mW, exposure time: 15 min. Specimens were fixed in 10% neutral formalin solution immediately after sacrifice. The wound was measured histologically. RESULTS: Wound width in the LIPUS group tended to be smaller than that of the control group. The experimental group in both 1-week and 2-week groups showed that unhealed areas were significantly smaller by LIPUS than those in the control groups (P<0.05). CONCLUSION: Our results suggest that the use of LIPUS on palatal excisional wounds was effective in promoting epithelial and connective tissue closure.

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.

Two-dimensional real-time blood flow and temperature of soft tissue around maxillary anterior implants.

PURPOSE: The aims of this study were to (1) evaluate the basic nature of soft tissue surrounding maxillary anterior implants by simultaneous measurements of blood flow and surface temperature and (2) analyze differences with and without bone grafting associated with implant placement to try to detect the signs of surface morphology change. MATERIALS AND METHODS: Twenty maxillary anterior implant patients, 10 bone grafting and 10 graftless, were involved in this clinical trial. Soft tissue around the implant was evaluated with 2-dimensional laser speckle imaging and a thermograph. RESULTS: Blood flow was significantly lower in attached gingiva surrounding implants in graftless patients (P = 0.0468). On the other hand, it was significantly lower in dental papillae (P = 0.0254), free gingiva (P = 0.0198), and attached gingiva (P = 0.00805) in bone graft patients. Temperature was significantly higher in free gingiva (P = 0.00819) and attached gingiva (P = 0.00593) in graftless patients, whereas it was significantly higher in dental papilla and free gingiva in implants with bone grafting. CONCLUSION: The results suggest that simultaneous measurements of soft-tissue blood flow and temperature is a useful technique to evaluate the microcirculation of soft tissue surrounding implants.

Three-dimensional finite element analysis of fixed complete-arch prostheses supported by 4 immediate-loaded implants in the completely edentulous maxilla using clinical computerized tomography data.

Mechanical simulation by loading an occlusal force (load), assumed to be that loaded under clinical conditions, was performed in a computerized tomography (CT) data-based immediate-loaded implant placement simulation. Stresses on and displacements of the implants and surrounding bone tissue were analyzed mechanically using 3-dimensional finite element analysis (FEA). The purpose of this study was to investigate the possibility of practical preoperative design and its evaluation and to assess the effects of connected fixation. Implants with a diameter of 4.0 mm were placed in the bilateral upper incisor and second premolar regions in a 69-year-old woman. An X-ray CT of the head was carried out, and implant placement simulation and 3-dimensional FEA models were constructed from the CT data. Forces were loaded on 4 individual implants placed in this model or all connected implants, and a mechanical analysis was performed. A 100-N vertical force was loaded on each implant as individual loading for the control group, and a 400-N vertical force was loaded on the connected implants as connected loading for the test group. The displacement and stress distributions were assessed using the 3-dimensional FEA. In the test group, established on the assumption of connected fixation for provisional restoration facilitating immediate loading, the maximum stress and displacement of peri-implant bone were smaller than those in the control group undergoing individual loading. The implant displacement level was suggested to serve as a numerical prognostic index of osseointegration of immediate-loaded implants. This method was shown to be immediately applicable to implant placement simulations using CT data currently generated in clinical practice, with no modification. Such a mechanical assessment using the FEA model can be performed noninvasively.

DNA amplification using phi29 DNA polymerase validates gene polymorphism analysis from buccal mucosa samples.

Venous blood is currently the most common source of DNA for gene polymorphism screening; however, blood sampling is invasive and difficult to perform in general dental treatment. Buccal mucosa samples provide an alternative source of DNA, but it is frequently difficult to effectively amplify the DNA owing to the small amounts of sample material obtained. This study was performed to establish a method for performing total genomic DNA amplification from buccal mucosa samples using phi29 DNA polymerase. Total genomic DNA was isolated from buccal mucosa samples obtained from healthy subjects and was amplified using phi29 DNA polymerase. To determine the suitability of the extracted DNA for genotyping, polymerase chain reaction and restriction fragment length polymorphism analyses were performed for the IL-1 gene polymorphism. Genotyping of the IL-1 polymorphism was successful using the amplified DNA from a buccal mucosa, but genotyping was unsuccessful using the unamplified control because of low DNA purity. The method of extracting DNA from a buccal mucosa is painless, simple, minimally invasive, and rapid. Genomic DNA from a buccal mucosa can be amplified by phi29 DNA polymerase in sufficient quantity and quality to conduct gene polymorphism analyses.

The effects of low-intensity pulsed ultrasound exposure on gingival cells.

BACKGROUND: Low-intensity pulsed ultrasound (LIPUS) has been used in fracture treatment to shorten the time needed for biologic wound healing. Clinical trials applying LIPUS in implant dentistry have reported accelerated soft-tissue healing and osseointegration. However, details of the clinical effects of LIPUS have not been well characterized. Connective tissue growth factor (CCN2/CTGF) plays an important role in wound healing and angiogenesis in periodontal tissue. In this study, we focus on the effect of LIPUS on gingival epithelial cells and the role of CCN2/CTGF therein. METHODS: Gingival epithelial cells (GE1) were cultured in six-well cell-culture plates for 24 hours at 37°C with 5% CO(2), and then exposed to LIPUS for 15 minutes at 3-MHz frequency and 40-mW/cm(2) power. Total RNA was extracted after LIPUS exposure and analyzed by real-time polymerase chain reaction to detect CCN2/CTGF. Additionally, total protein from each sample after LIPUS exposure was immunoblotted with anti-CCN2/CTGF antibody. RESULTS: LIPUS exposure increased the mRNA level of CCN2/CTGF on exposure, and the level was significantly greater at 0 and 15 minutes after LIPUS exposure compared to the control. Western blotting analysis showed intense staining of CCN2/CTGF for 60 minutes after LIPUS exposure. The results demonstrate that LIPUS exposure accelerates soft-tissue healing by increasing CCN2/CTGF on exposure, in addition to its effects on bone formation. CONCLUSION: Our findings demonstrate that LIPUS exposure accelerates soft-tissue healing by increasing connective tissue growth factors via a mitogen-activated protein kinase signaling pathway on exposure.

Cevimeline-induced monophasic salivation from the mouse submandibular gland: decreased Na+ content in saliva results from specific and early activation of Na+/H+ exchange.

Cevimeline and pilocarpine are muscarinic agonists used clinically to treat dry mouth. In this study, we explored fluid secretion from mouse submandibular glands to determine the mechanism of cevimeline, pilocarpine, and an experimentally used agent carbachol. Cevimeline evoked almost the same amount of secretion at concentrations from 30 µM to 1 mM. Pilocarpine also induced secretion at a concentration as low as 1 µM and was the most powerful secretagogue at 10 µM. Secretion was induced by carbachol at 0.1 µM, with maximum secretion at 1.0 µM. Cevimeline induced monophasic secretion at all concentrations tested, whereas higher concentrations of pilocarpine and carbachol induced secretion with variable kinetics, i.e., an initial transient high flow rate, followed by decreased secretion after 2 to 3 min. In the presence of an epithelial Na(+) channel blocker, amiloride, neither carbachol nor pilocarpine affected the Na(+) level of secreted saliva; however, it significantly increased the Na(+) content of cevimeline-induced saliva. The intracellular Ca(2+) response of acinar cells was almost identical among all three agents, although recovery after drug removal was slower for cevimeline and pilocarpine. A profound decrease in intracellular pH was observed during pilocarpine and carbachol treatment, whereas intracellular acidification induced by cevimeline was only seen in the presence of a Na(+)/H(+) exchange inhibitor. When external HCO(3)(-) was removed, cevimeline-induced saliva significantly decreased. These findings suggest that cevimeline specifically activates Na(+)/H(+) exchange and may promote Na(+) reabsorption by stabilizing epithelial sodium channel activity.

Preoperative assessment of treatment planning on minimization of micro-movement during healing period of immediate-loaded implants using X-ray CT data-based simulation.

Abstract The purpose of this study was to investigate the possibility of practical preoperative design and its evaluation and to assess the effects of connected fixation on minimization of micro movement during healing period of immediately loaded implants.Mechanical simulation by loading an occlusal force (load), assumed to be that loaded under clinical conditions, was performed in a computed tomography (CT) data-based immediate-loaded implant placement simulation. Stresses on and displacements of the implants and surrounding bone tissue were analyzed mechanically using three-dimensional finite element analysis.An X-ray CT of the head was carried out, and implant placement simulation andthree-dimensional finite element analysis models were constructed from the CT data. Forces were loaded on four individual implants placed in this model or all connected implants, and a mechanical analysis was performed. A 100 N vertical force was loaded on each implant as individual loading for the control group, and a 400 N vertical force was loaded on the connected implants as connected loading for the test group. The displacement and stress distributions were assessed using the three-dimensional finite element analysis. In the test group, established on the assumption of connected fixation for provisional restoration facilitating immediate loading, the maximum stress and displacement of peri-implant bone were smaller than those in the control group undergoing individual loading.The implant displacement level was suggested to serve as a numerical prognostic index of osseointegration of immediate-loaded implants. This method was shown to be immediately applicable to implant placement simulations using CT data currently generated in clinical practice, with no modification. Such a mechanical assessment using the finite element analysis model can be performed noninvasively.