Prosthodontic treatment can improve the ingestible food profile in Japanese adult outpatients.

PURPOSE: To investigate the effect of prosthodontic treatment on the ingestible food profile in adult Japanese outpatients, and to identify the related risk factors that can deteriorate the profile. METHODS: The participants were 277 outpatients who visited university-based specialty clinics in Japan for prosthodontic treatment. The demographic data, number of present teeth assessed via intraoral examination, and oral health-related quality of life assessed by the total Oral Health Impact Profile (OHIP-J54) scores of all participants were recorded before treatment. Ingestible food profile score (IFS) was recorded using a validated food intake questionnaire. Eligible participants who answered the questionnaire before and after treatment were categorized into five groups based on the prosthodontic treatments they received (i.e., crowns, bridges, removable partial dentures, removable complete dentures, and removable complete and partial dentures). RESULTS: Multivariate analysis of covariance revealed a statistically significant main effect of prosthodontic intervention (time course: before and after treatment) on mean IFS (P=0.035, F=4.526), even after adjusting for covariates (age, number of present teeth, and treatment modality). Multiple linear regression analysis revealed that the low number of present teeth (r=0.427, P<0.001) and a high OHIP-J54 total score (r=-0.519, P<0.001) of the patients at the baseline were significantly associated with their baseline IFSs, even after adjusting for confounding variables. CONCLUSIONS: The findings of this multicenter follow-up study indicate the importance of prosthodontic rehabilitation in improving patients' ingestible food profiles.

A multi-centered epidemiological study evaluating the validity of the treatment difficulty indices developed by the Japan Prosthodontic Society.

PURPOSE: The Japan Prosthodontic Society developed a multi-axis assessment protocol to evaluate the complex variations in patients who need prosthodontic care, and to classify the level of treatment difficulty. A previous report found the protocol to be sufficiently reliable. The purpose of this multi-center cohort study was to evaluate the validity of this multi-axis assessment protocol. METHODS: The treatment difficulty was evaluated using the multi-axis assessment protocol before starting prosthodontic treatment. The time required for active prosthodontic treatment, medical resources such as treatment cost, and changes in the oral health-related QOL before and after treatment, were evaluated after treatment completion. The construct validity of this protocol was assessed by the correlation between the dentist's pre-operative subjective assessment of the treatment difficulty, and the level of difficulty determined by this protocol. The predictive validity was assessed estimating the correlations between a "comprehensive level of treatment difficulty" based on the four axes of this protocol and total treatment cost, total treatment time, and changes in the oral health-related QOL before and after treatment. RESULTS: The construct validity of this protocol was well documented except for psychological assessment. Regarding the predictive validity, the comprehensive level of treatment difficulty assessed before treatment was significantly correlated with the three surrogate endpoints known to be related to the treatment difficulty (total treatment cost, treatment time, and improvement in the oral health-related QOL). To further clarify the validity of the protocol according to patients' oral condition, a subgroup analysis by defects was performed. Analyses revealed that treatment difficulty assessment before treatment was significantly related to one or two surrogate endpoints in the fully edentulous patients and the partially edentulous patients. No significant relationship was observed in the patients with mixture of full/partial edentulism and the patients with teeth problems, possibly due to the small sample size in these groups. CONCLUSION: This study revealed that the multi-axis assessment protocol was sufficiently valid to predict the level of treatment difficulty in prosthodontic care in patients with fully edentulous defects and with partially edentulous defects.

A stability evaluation of a novel titanium dental implant/interconnected porous hydroxyapatite complex under functional loading conditions.

The aim of this study was to evaluate the stability of implant/interconnected porous calcium hydroxyapatite complex (implant/IPCHA-complex) under functional loading. Implant/IP-CHA-complexes were placed into the mandibles of four Beagle-Labrador hybrid dogs (complex-group). On the other side, an implant was placed directly (control-group). To subject the loading, the animals were fed a hard diet throughout the loading phase of 5 months. The implant stability quotients (ISQs) and bone implant contact (BIC), and histological evaluations were performed. The ISQs of implant/IP-CHA-complex was significantly lower at placement than that of the control-implant. On the other hand, there was no significant difference between in the groups during loading. The BIC measurements, there was no significantly difference between in both groups. Histologically, newly formed bone was observed in contact with most of the implant surface in the complex-group. An IP-CHA/implant-complex would be able to achieve both bone reconstruction and implant stability under functional loading conditions.

Molar loss and powder diet leads to memory deficit and modifies the mRNA expression of brain-derived neurotrophic factor in the hippocampus of adult mice.

BACKGROUND: It is known that tooth loss is known to be a risk factor for Alzheimer's disease and soft diet feeding induces memory impairment. Recent studies have shown that brain-derived neurotrophic factor (BDNF) is associated with tooth loss or soft diet in young animal model, and that BDNF expression is decreased in patients with Alzheimer's disease. However, single or combined effect of tooth loss and/or soft diet on brain function has not fully understood. Here we examined the effect of molar loss and powder diet on memory ability and the expression of BDNF mRNA in the hippocampus of adult C57BL/6J mice. Twenty eight-weeks-old C57BL/6J mice were divided into intact molar group and extracted molar group. They were randomly divided into the I/S group (Intact upper molar teeth/Solid diet feeding), the E/S group (Extracted upper molar teeth/Solid diet feeding), the I/P group (Intact upper molar teeth/Powder diet feeding), and the E/P group (Extracted upper molar teeth/Powder diet feeding). The observation periods were 4 and 16-week. To analyze the memory ability, the step-through passive avoidance test was conducted. BDNF-related mRNA in the hippocampus was analyzed by real-time polymerase chain reaction (RT-PCR). RESULTS: At 4 weeks later, we performed memory test and isolated brains to analyze. There were no differences in memory function and BDNF mRNA level between these four groups. However, at 16 weeks later, E/S and E/P group showed memory impairment, and decreased level of BDNF mRNA. Whereas, the powder diet had no effect on memory function and BDNF mRNA level even at 16 weeks later. CONCLUSIONS: These results suggest that the effect of molar loss and powder diet on memory function and BDNF mRNA levels were different, molar loss may have a greater long-term effect on memory ability than powder diet does.

Tooth loss might not alter molecular pathogenesis in an aged transgenic Alzheimer's disease model mouse.

BACKGROUND AND OBJECTIVE: Previous studies have reported that tooth loss is a risk factor of Alzheimer's disease (AD). However, the association between tooth loss and cognition and the impact of tooth loss on the molecular pathogenesis of AD remain elusive. In this study, we tested the effect of tooth loss on learning and memory and on the molecular pathogenesis of AD in an aged AD model mice. MATERIALS AND METHODS: We divided 14-month-old amyloid precursor protein (APP) transgenic mice, an AD model mouse line, into upper molar extracted group (experimental) and molar intact group (control). At 18 months old, we analysed not only the changes of amyloid-beta (Aß), pyramidal cells in the brain but also the learning and memory ability with step-through passive avoidance test. RESULTS: The amount of Aß and the number of pyramidal cells in the hippocampus were not significantly different between the experimental and control group. Similarly, the difference of learning and memory ability could not be distinguished between the groups. CONCLUSION: Neither molecular pathogenesis of AD nor associated learning and memory were aggravated by tooth loss in these mice. The limited results of this study which used the aged mice may help the dental profession to plan and explain treatments to patients with AD, which must be designed while taking into account the severity of the AD symptoms.

The Effect of Superstructures Connected to Implants with Different Surface Properties on the Surrounding Bone.

The objective of this study was to investigate how the connection of superstructures to implants with different surface properties affects the surrounding bone. The right and left mandibular premolars and molars of 5 dogs were extracted. After 12 weeks, a machined implant was placed mesially and an anodized implant was placed distally on one side of the edentulous jaw, with the positions reversed on the opposite side. Twelve weeks after implantation, splinted superstructures were set to the implants. At 24 weeks after implantation, the implant stability quotient (ISQ) was measured, radiographs were obtained. Removal torque values were measured and histologic observation was performed. The ISQ values at 24 weeks after implantation were not significantly different between the groups. The removal torque values were significantly different between the distal anodized and distal machined implants (p < 0.05). From 12 to 24 weeks, marginal bone losses were not significantly different between the groups. Fluorescent observation of tissue samples revealed bone-remodeling activity around all of the implants. The results of this study suggest that when implants with different surface properties are connected, machined implants at the most distal sites might be a potential risk factor for implant-bone binding.

Influence of implant surface topography on primary stability in a standardized osteoporosis rabbit model study.

Evaluating primary stability is important to predict the prognosis of dental implant treatment. Primary stability is decreased in a low bone density site such as osteoporosis. However, it is difficult to apply in small animal and the effect of the different implant surface topography for the primary stability at low bone density site has not yet fully been investigated. The purpose of the present study was to evaluate the influence of implant surface topography on primary stability in a standardized osteoporosis animal model. Six rabbits underwent ovariectomy and administrated glucocorticoid to induce an osteoporosis model. Sham-operations were performed in additional six rabbits. Implants with machined or oxidized-surfaces were inserted into the femur epiphyses and insertion torque (IT) and implant stability quotient (ISQ) were measured. In sham model, the IT and ISQ did not differ significantly between the both implant. However, the IT value of oxidized-surface implant was significantly higher than that of the machined implant in the osteoporosis model. Meanwhile, ISQ did not significantly differ between the machined and oxidized-surfaced implants. In conclusion, the IT of implants is higher with rough than with smooth surfaces but that there are no differences in ISQ value between different surfaces in a standardized osteoporosis bone reduced rabbit model.

Inorganic polyphosphate adsorbed onto hydroxyapatite for guided bone regeneration: an animal study.

Inorganic polyphosphate (poly(P)) is recognized as a therapeutic agent that promotes fibroblast growth factor and enhances osteogenic differentiation, and in vivo, when adsorbed onto interconnected porous calcium hydroxyapatite (IP-CHA) enhances bone regeneration. The present study focused on the effect of poly(P) adsorbed onto IP-CHA granules (Poly(P)/IP-CHA) in guided bone regeneration (GBR). Dental implants were placed into the edentulous mandibular areas of five Beagle-Labrador hybrid dogs with screw expose on the buccal side, and then bone defects were filled Poly(P)/IP-CHA (test) or IP-CHA (control). After 12 weeks, histological evaluation and histomorphometrical analysis were performed. Newly-bone formation around exposed implant screw was clearly detected in the test-group. The ratio for regenerated bone height in the test group versus the control-group was 85.6±20.2 and 62.6±23.8, respectively, with no significant difference, while, that for bone implant contact was significantly higher (67.9±11.8 and 48.8±14.1, respectively). These findings indicate that Poly(P)/IP-CHA enhances bone regeneration in GBR.

The influence of fixation in formalin on the measurement of stability of implants using resonance frequency analysis and Periotest M®: a study in a dog.

Resonance frequency analysis (RFA) and Periotest® have been widely used to evaluate measurements of the stability of implants in clinical studies and animal experiments. In animals, these measurements are often made after bone has been fixed in formalin. However, it is not yet clear how this fixation influences RFA and Periotest®, and our aim was to clarify this using the implant stability quotient (ISQ) and Periotest® value (PTV). Six titanium implants were placed, 3 into each femur, of one male dog (a beagle/labrador cross). After 2 months blocks of bone were harvested, each block containing 3 implants, and were fixed in 10% neutral formalin. Measurements were made before fixation (time 0) then at 4h, and 1, 7, 14, 21, and 28 days. ISQ values of 6 implants were evaluated 3 times on the short and long axes, as were PTV. ISQ ranged from 67.5 to 79.3 and tended to increase with time. ISQ at 7-28 days were significantly higher than that at time 0. PTV ranged from -7.7 to -7.8 and did not differ significantly among fixation times. These results suggest that fixation of bony tissue in formalin might affect ISQ, so it might be preferable to measure ISQ during the early stages of fixation.

Polyphosphate-mediated inhibition of tartrate-resistant acid phosphatase and suppression of bone resorption of osteoclasts.

Inorganic polyphosphate (poly(P)) has recently been found to play an important role in bone formation. In this study, we found that tartrate-resistant acid phosphatase (TRAP), which is abundantly expressed in osteoclasts, has polyphosphatase activity that degrades poly(P) and yields Pi as well as shorter poly(P) chains. Since the TRAP protein that coprecipitated with anti-TRAP monoclonal antibodies exhibited both polyphosphatase and the original phosphatase activity, poly(P) degradation activity is dependent on TRAP and not on other contaminating enzymes. The ferrous chelator α, α'-bipyridyl, which inhibits the TRAP-mediated production of reactive oxygen species (ROS), had no effect on such poly(P) degradation, suggesting that the degradation is not dependent on ROS. In addition, shorter chain length poly(P) molecules were better substrates than longer chains for TRAP, and poly(P) inhibited the phosphatase activity of TRAP depending on its chain length. The IC50 of poly(P) against the original phosphatase activity of TRAP was 9.8 µM with an average chain length more than 300 phosphate residues, whereas the IC50 of poly(P) with a shorter average chain length of 15 phosphate residues was 8.3 mM. Finally, the pit formation activity of cultured rat osteoclasts differentiated by RANKL and M-CSF were markedly inhibited by poly(P), while no obvious decrease in cell number or differentiation efficiency was observed for poly(P). In particular, the inhibition of pit formation by long chain poly(P) with 300 phosphate residues was stronger than that of shorter chain poly(P). Thus, poly(P) may play an important regulatory role in osteoclastic bone resorption by inhibiting TRAP activity, which is dependent on its chain length.

Inorganic polyphosphate suppresses lipopolysaccharide-induced inducible nitric oxide synthase (iNOS) expression in macrophages.

In response to infection, macrophages produce a series of inflammatory mediators, including nitric oxide (NO), to eliminate pathogens. The production of these molecules is tightly regulated via various mechanisms, as excessive responses are often detrimental to host tissues. Here, we report that inorganic polyphosphate [poly(P)], a linear polymer of orthophosphate ubiquitously found in mammalian cells, suppresses inducible nitric oxide synthase (iNOS) expression induced by lipopolysaccharide (LPS), a cell wall component of Gram-negative bacteria, in mouse peritoneal macrophages. Poly(P) with longer chains is more potent than those with shorter chains in suppressing LPS-induced iNOS expression. In addition, poly(P) decreased LPS-induced NO release. Moreover, poly(P) suppressed iNOS mRNA expression induced by LPS stimulation, thereby indicating that poly(P) reduces LPS-induced iNOS expression by down-regulation at the mRNA level. In contrast, poly(P) did not affect the LPS-induced release of TNF, another inflammatory mediator. Poly(P) may serve as a regulatory factor of innate immunity by modulating iNOS expression in macrophages.

Tooth loss induces memory impairment and neuronal cell loss in APP transgenic mice.

Tooth loss is a known risk factor of Alzheimer's disease (AD). However, the association of tooth loss with the molecular pathogenesis of AD is still unknown. The hypothesis that the molecular pathogenesis of AD is enhanced by molar tooth loss was tested. Seventeen female transgenic mice (J20) were divided into the experimental (EX, n=10) and control (C, n=7) groups. In the EX group, maxillary bilateral molar teeth were extracted at the age of 6 months. In the C group, however, these teeth remained intact. Passive avoidance test was performed to evaluate learning and memory abilities right after tooth extraction (6 months old) and 4 months later (10 months old). After the test at 10 months, amyloid beta (Aß) deposition and changes of neuronal cell number and area in the hippocampus were investigated using half of the brains. The other half was homogenized and used to determine Aß40 and Aß42 levels by ELISA. At the 10 months of age, learning and memory abilities were significantly impaired in the EX group compared to the C group (P<0.05). The neuronal cell number in the CA1 and CA3 regions was significantly lower in the EX group than in the C group (P<0.05). Total Aß, Aß40, and Aß42 levels showed no significant intergroup difference. Molar tooth loss may cause neuronal cell loss in the hippocampus, leading to memory impairment; this process may be independent of the amyloid cascade.

Increased crown-to-implant ratio may not be a risk factor for dental implant failure under appropriate plaque control.

OBJECTIVE: The aim of this study was to evaluate whether increased crown-to-implant (C/I) ratio influences implant stability or not under proper healthy control of peri-implant mucosa. The hypothesis of this study is that implant stability can be maintained despite High C/I, under appropriate plaque control. MATERIALS AND METHODS: Five male Beagle-Labrador hybrid dogs (2 years old) were used. Their bilateral mandibular premolar extraction was performed. After allowing 12 weeks for bone healing, 3 types of vertical marginal bone loss were simultaneously prepared randomly. Then, 30 titanium implants were placed in the edentulous areas and defined as High C/I, Mid C/I and Low C/I groups. This time point was designated as the baseline (0 Week). Twelve weeks after implant placement, metal superstructures were cemented to the implants and an occlusal plate was set at the opposite side. At the same time, Calcein green was injected for remodeling evaluation. Implants were loaded by feeding the dogs a hard pellet diet. Tooth brushing was performed 5 days per week during the study to maintain healthy peri-implant mucosa. Twenty-four weeks following implant placement, the interface structure was evaluated clinically, radiologically, and histologically. RESULT: Implant stability quotient (ISQ) increased with time in all 3 groups, without any significant correlation with the C/I value (p >0.05). Moreover, mean marginal bone loss adjacent around implants in all 3 groups ranged between 0.11 and 0.19 mm, with no significant difference (p >0.05). Many fluorescence-labeled bones are shown in the High C/I group. It is considered that high remodeling activity prevent marginal bone loss in the High C/I group and this may provide favorable implant stability under proper plaque control. CONCLUSION: These findings suggest that increased C/I may not be a risk factor for implant failure if the peri-implant mucosa is kept healthy, as was the case in this animal model.

New development of carbonate apatite-chitosan scaffold based on lyophilization technique for bone tissue engineering.

Carbonate apatite-chitosan scaffolds (CA-ChSs) were fabricated using the lyophilization technique. It was found that ChSs prepared with 200 mg chitosan powder (ChSs200) had well-structured three-dimensional architecture with high porosity and good retentive form without brittleness. In addition, it was shown that the number of osteoblast-like cells MC3T3-E1 proliferated on desalinated ChSs200 was larger than that on the non-desalinated ChSs200. CA-ChSs were fabricated by adding 100 mg carbonate apatite (CA) to 200 mg chitosan gels followed by freeze-drying (CA100ChSs200). SEM observation revealed that CA100ChSs200 had favorable three- dimensional porous structures. The number of living cells increased more rapidly on CA100ChSs200 prepared with different amounts of CA than on ChSs. ALP activity significantly increased after day 14 and reached a plateau after day 21 in ChSs200 and CA100ChSs200. It was concluded that newly developed CA100ChSs200 may be a possible scaffold material for tissue engineering.

Relationship between behavioral and psychological symptoms of dementia and oral health status in the elderly with vascular dementia.

OBJECTIVES: The aim of this study was to clarify the relationship between behavioral and psychological symptoms of dementia (BPSD) and oral status in the elderly with vascular dementia. BACKGROUND: There have been some reports of a relationship between disease symptoms and oral status in the elderly with Alzheimer's disease, but few reports have been conducted in the elderly with vascular dementia. Until now, the relationship between BPSD and oral status has been unknown. MATERIALS AND METHODS: An investigation was conducted concerning BPSD and oral status among 57 subjects with vascular dementia (mean age, 85.7 ± 5.5 years). The wearing of dentures and oral activities of daily living (oral ADL) were examined. RESULTS: Subjects with activity disturbances and those with aggressiveness had significantly lower rates of denture wearing than those without these two symptoms (p < 0.05). Significantly lower oral ADL scores were obtained from subjects with delusional ideas, hallucinations, activity disturbances and diurnal rhythm disturbances (p < 0.05), as well as those with affective disturbances (p< 0.01). CONCLUSION: This study indicated a relationship between BPSD and the wearing of dentures in the elderly with vascular dementia. The study also demonstrated relationships between BPSD and oral ADL.

Influence of formalin fixation on the implant stability quotient and mechanical characteristics of bone.

The implant stability quotient (ISQ) has been widely evaluated in clinical studies and animal experiments. However, accurate measurement is often difficult in animal models. In such cases, measurement of ISQ in bone is needed after formalin fixation. However, it is not yet clear how such fixation influences the measurement. The purpose of this study was to investigate the influence of formalin fixation on ISQ and the mechanical characteristics of bone. Fourteen tibias were harvested from rabbits; the samples from the left (length 60mm, control group) were soaked in saline and the samples from the right (length 60mm, fixation group) were fixed in 10% neutral-buffered formalin at 4°C for 4h. Three-point bending tests were done at 5mm/min to measure the maximum load and total absorbed energy. Twelve titanium implants (Brånemark System(®) Mk-III TiUnite, Nobel Biocare, Sweden) were placed into the edentulous molar site of the mandibles of 2 dogs and the ISQ was measured by Osstell(®) (control group) 3 months later. The implants involved in the bone block were then fixed for 4h (fixation group) and the ISQ measured. The maximum load values did not differ significantly between the control and fixation groups. Total absorbed energy was significantly higher in the control group than in the fixation group. ISQ did not differ significantly between the groups. These results suggest that formalin fixation of bone might affect some of the mechanical characteristics of bone, but not its ISQ.

Development of implant/interconnected porous hydroxyapatite complex as new concept graft material.

BACKGROUND: Dental implant has been successfully used to replace missing teeth. However, in some clinical situations, implant placement may be difficult because of a large bone defect. We designed novel complex biomaterial to simultaneously restore bone and place implant. This complex was incorporated implant into interconnected porous calcium hydroxyapatite (IP-CHA). We then tested this Implant/IP-CHA complex and evaluated its effect on subsequent bone regeneration and implant stability in vivo. METHODOLOGY/PRINCIPAL FINDINGS: A cylinder-type IP-CHA was used in this study. After forming inside of the cylinder, an implant was placed inside to fabricate the Implant/IP-CHA complex. This complex was then placed into the prepared bone socket in the femur of four beagle-Labrador hybrid dogs. As a control, implants were placed directly into the femur without any bone substrate. Bone sockets were allowed to heal for 2, 3 and 6 months and implant stability quotients (ISQ) were measured. Finally, tissue blocks containing the Implant/IP-CHA complexes were harvested. Specimens were processed for histology and stained with toluidine blue and bone implant contact (BIC) was measured. The ISQs of complex groups was 77.8±2.9 in the 6-month, 72.0±5.7 in the 3-month and 47.4±11.0 in the 2-month. There was no significant difference between the 3- or 6-month complex groups and implant control groups. In the 2-month group, connective tissue, including capillary angiogenesis, was predominant around the implants, although newly formed bone could also be observed. While, in the 3 and 6-month groups, newly formed bone could be seen in contact to most of the implant surface. The BICs of complex groups was 2.18±3.77 in the 2-month, 44.03±29.58 in the 3-month, and 51.23±8.25 in the 6-month. Significant difference was detected between the 2 and 6-month. CONCLUSIONS/SIGNIFICANCE: Within the results of this study, the IP-CHA/implant complex might be able to achieve both bone reconstruction and implant stability.

Inorganic polyphosphates stimulate FGF23 expression through the FGFR pathway.

Polyphosphate (polyP) is composed of linear polymers of orthophosphate residues linked by high-energy phosphoanhydride bonds. It has been reported to improve osteoblastic differentiation, stimulate periodontal tissue regeneration, and accelerate bone repair. The aim of this study was to evaluate the effect of polyP on the expression of FGF23, a hormone secreted mostly be mature osteoblasts and osteocytes. In this study, different types of polyP were synthesized and co-cultured with osteoblast-like UMR-106 cells. Real-time PCR and western blot were used to analyze the gene and protein expression of FGF23. We found that 1 mM polyP was able to increase FGF23 expression after 4 h, reaching a peak after 12-24 h, with expression decreasing by 48 h. We also found that polyP could activate the FGFR pathway, as evidenced by increased phosphorylation of FGFR, FRS2, and Erk1/2. When FGFR signaling was inhibited by the specific inhibitor SU5402, the effect of polyP on FGF23 expression was significantly reduced. Our results indicate that polyP is able to stimulate osteoblastic FGF23 expression and that this effect is associated with activation of the FGFR pathway. These findings provide support for the clinical use of polyP by indicating a mechanism for polyP in bone regeneration.