Showing papers in "Prosthodontic Research & Practice in 2008"
TL;DR: It was confirmed that the new food intake questionnaire method, with a revised 25 food item list, was both valid and reliable.
Abstract: Purpose: The purpose of this study was to reduce the number of food items for ease of use, and to eliminate the influence of food preferences (likes and/or dislikes) on an earlier version of the food intake questionnaire method for evaluating the ability of mastication in complete denture wearers which had been previously developed by the authors.Methods: The subjects were 262 complete denture wearers (average age: 76.7±6.1 years old, male: 128 persons, female: 134 persons). The food intake questionnaire composed of a list of 35 food items which were used in the study. All subjects were asked to assign a mark to each type of food according to one of five categories (easily eaten, eaten with difficulty, cannot be eaten, do not eat because of dislike, have not eaten since starting to wear dentures). In order to reduce the number of the initial 35 food items in the questionnaire, the correlation coefficient of the masticatory score, representing the masticatory ability before and after elimination of foods, was examined in all the subjects. The masticatory performance (MP) was also evaluated by a sieving method in all subjects.Results: In the questionnaire with 5 categories composed of 25 foods, the reliability coefficient (Cronbach’s α) was 0.939. There was significant correlation between the masticatory score using the 35 food item list and the new masticatory score using the new 25 food item list (r=0.95, P<0.01). There was significant correlation between the MP using the sieving method and the N-MS using the 25 food item list (r=0.62, P<0.01).Conclusion: It was confirmed that the new food intake questionnaire method, with a revised 25 food item list, was both valid and reliable.
34 citations
TL;DR: In this article, the authors characterized the morphological, chemical, and structural features of hydroxapatite (HA) layers on SA-treated cpTi implants in rat maxilla.
Abstract: Purpose: Highly crystalline thin hydroxyapatite (HA) layers deposited on the surface of commercially pure titanium (cpTi) by discharge anodic oxidation and hydrothermal treatment (SA treatment) enhance the value of cpTi as endosseous implants in clinical dentistry. In particular, the SA treatment affects the osteoconductive properties of cpTi. Determining whether this HA layer retains its chemical stability during osseous wound healing is crucial for its use in implants. In this study, we characterized the morphological, chemical, and structural features of HA layers on SA-treated cpTi implants in rat maxilla.Materials and methods: SA-treated cpTi implants (diameter: 1.0 mm, length: 2.0 mm) were placed in the maxilla of 8-week-old Wistar rats. After 14, 21, and 28 days, the maxilla were harvested and the implant surfaces were analyzed by scanning electron microscopy (SEM), electron probe microanalysis (EPMA), and x-ray photoelectron spectroscopy (XPS).Results: SEM analysis revealed precipitated HA crystals on the implant surface; the crystals had a typical single hexagonal columnar shape and they were highly crystalline. Implantation up to 28 days changed neither the morphology nor the crystalline features of the thin HA layer. EPMA revealed an even distribution of P and Ca in the HA layers before and after implantation in the maxilla, while XPS indicated no change in the binding energies of P and Ca in the HA crystals.Conclusion: The thin HA layer formed on the SA-treated cpTi implants remained stable during the process of jaw bone formation.
15 citations
TL;DR: When a fluoride with less than 500 ppm concentration was added to the acid biofilm which was produced by Streptococcus mutans, the possibility to corrode was suggested and the Ti-0.5Pt alloy had a high corrosion resistance in the same condition.
Abstract: Purpose: As for commercially pure titanium (CP-Ti) and titanium alloys (Ti-6Al-4V, Ti-6Al-7Nb), when fluoride exists in an acidic environment, it is known to corrode from recent research. However, it is also reported that the corrosion resistance improves when small amount of platinum is added to pure titanium. The purpose of this study is to examine the corrosion behavior of CP-Ti, Ti-6Al-4V, Ti-6Al-7Nb, and high corrosion Ti-0.5Pt alloy when a fluoride added to the acidic environment produced by streptococcus mutans.Methods: The specimen (CP-Ti, Ti-6Al-4V, Ti-6Al-7Nb, and experimentally produced Ti-0.5Pt alloy) were polished like a mirror. Streptococcus mutans was cultured for 24 hours with brain heart infusion (BHI) medium adding sucrose on the specimen, and then 1000ppm fluoride solution of same medium volume was added (that is, fluoride concentration becomes 500 ppm). After 10 min, all the solutions were removed and new culture for 24 hours started again. These cycles of 3, 5, 7, and 10 times were repeated and the surfaces of the specimens were observed by scanning electron microscope (SEM).Results: The CP-Ti and Ti-6Al-4V, Ti-6AL-7Nb alloys were observed the typically metallographical structure by adding fluoride solution repeatedly. The surface of Ti-0.5Pt alloy was no change by adding fluoride solution.Conclusion: When a fluoride with less than 500 ppm concentration was added to the acid biofilm which was produced by Streptococcus mutans, as for CP-Ti, Ti-6Al-4V and Ti-6Al-7Nb alloys the possibility to corrode was suggested. The Ti-0.5Pt alloy had a high corrosion resistance in the same condition.
7 citations
TL;DR: Investigation of the utility of originally developed measuring system of tongue pressure in the rehabilitation of dysphagic patients with prosthesis finds improvement of the tongue pressure production described by the system might contribute to the bolus transport in oral phase of swallowing.
Abstract: Tongue plays an important role by making contact with palate in swallowing This study was aimed for investigating the utility of originally developed measuring system of tongue pressure in the rehabilitation of dysphagic patients with prosthesis Subject was a 68 years old male post-surgical laryngeal cancer patient who underwent percutaneus endoscopic gastrostomy because of dysphagia Tongue pressure during dry swallow was recorded by using our original sensor sheet system (Nitta, Japan) with five measuring points (Chs1-5) attached on the palatal surface of maxillary denture (RPD) Tongue impression was taken by his maxillary denture and the palatal contour was changed into palatal augmentation prosthesis (PAP), then tongue pressure with PAP was recorded and compared with that with RPD Magnitude of tongue pressure on median line (CHs1-3) of palatal surface of RPD was nearly 0 and that on the circumferential part (Chs4 and 5) had laterality In PAP, however, magnitude of tongue pressure on the median line increased and showed normal pattern (Ch1>Ch2>Ch3) and that on the circumferential part showed no laterality Improvement of the tongue pressure production described by our system might contribute to the bolus transport in oral phase of swallowing
7 citations
TL;DR: In this article, Bruxism was associated with lifestyle, especially with sleeping hours and mental stress, which suggested that an improvement in lifestyle might reduce bruxism events in the Non-TMD group.
Abstract: The purpose of this experiment was to clarify relations among temporomandibular disorders (TMDs), bruxism, lifestyle, and psychological stress. Participants were selected from female patients (n=29, 23-78 yrs, mean age 50.8 yrs).Eighteen females were diagnosed as having TMD (TMD group, mean age 47.6 yrs), and 11 females were diagnosed as not having TMD (Non-TMD group, mean age 55.9 yrs). All participants underwent self-administered questionnaires which consisted of the Health Practice Index (HPI), the Tokai University Type A Pattern Scale, the 28-item General Health Questionnaire (GHQ-28), and the Zung Self-Rating Depression Scale (Zung-SDS). They were instructed to sleep at home with the disposable sleep bruxism sensor (BiteStrip®, S.L.P.) attached on their left masseter. The number of bruxers was significantly higher in the TMD group than in the Non-TMD group (P<.05), which suggested an association between bruxism and TMD. Based on BiteStrip score, participants were divided into bruxers and non-bruxers. In Non-TMD groups there was significant difference only in lifestyle, especially sleep and mental stress between bruxers and non-bruxers (P<.05). Bruxers showed higher anxiety and insomnia score than non-bruxers. Bruxism in the Non-TMD group was associated with lifestyle, especially with sleeping hours and mental stress. This suggests that an improvement in lifestyle might reduce bruxism events in the Non-TMD group.
7 citations
TL;DR: The results demonstrate the potential of SA-treated cpTi surfaces for enhancing surface-specific expression of osteoblastic phenotypes and for inducing changes in bone matrix gene expression.
Abstract: In the present study, we assessed the effects of commercially pure titanium (cpTi) by anodic oxidation and hydrothermal treatment (SA-treated cpTi) on osteoblastic differentiation and interfacial bone formation through parallel in vitro and in vivo investigations. Osteoblast cells were cultured on SA-treated cpTi disks for 5, 7, 10, and 14 days. Bone matrix mineralization was assessed by EPMA. The levels of collagen I, alkaline phosphatase, osteocalcin, osteopontin, bone sialoprotein, and β-actin mRNA were analyzed using RT-PCR. In addition, SA-treated cpTi implants were placed in the mandibles of beagles for 14 days, and then examined histologically by light microscopy. Widespread Ca and P signals were observed early in the in vitro culturing period, and mRNA expression was up-regulated in cells that were in contact with the SA-treated cpTi. The bone-to-implant contact formed at the mandible SA-treated cpTi implant sites involved direct contact of the implant with the surrounding bone tissue. These results demonstrate the potential of SA-treated cpTi surfaces for enhancing surface-specific expression of osteoblastic phenotypes and for inducing changes in bone matrix gene expression.
7 citations
TL;DR: The results suggest that stimulated saliva and oral moisture are related to subjective oral dryness; thus, both the Saxon test and the test using an oral moisture checking device are useful for the assessment of subjective Oral dryness.
Abstract: Purpose: The present study aimed to investigate the relationship between subjective oral dryness and stimulated saliva or oral moisture.Methods: Twenty-one patients with subjective oral dryness (OD) and 21 healthy adults (HA) were enrolled in the study. The Saxon test was performed by chewing a gauze sponge for 2 minutes. Oral moisture was measured at the lingual mucosa (LM) and buccal mucosa (BM) by using an oral moisture checking device. Group differences in the amount of stimulated saliva and oral moisture were compared using the Mann-Whitney U test and Student's t test.Results: The average amount of salivary secretion in OD and HA in the Saxon test was 0.65 ± 0.55 and 2.34 ± 1.41 g/2 min, respectively; the difference between the groups was significant (p < 0.01). The oral moisture at the LM in OD and HA was 27.2% ± 2.9% and 32.3% ± 1.7%, respectively; this difference was significant (p < 0.01). The oral moisture at the BM in OD and HA was 32.6% ± 2.1% and 34.0% ± 2.2%, respectively; this difference was also significant (p < 0.05).Conclusion: This study demonstrated that the amount of stimulated saliva became less than 2.00 g and the moisture at the LM became less than 30.0% in patients with subjective oral dryness. These results suggest that stimulated saliva and oral moisture are related to subjective oral dryness; thus, both the Saxon test and the test using an oral moisture checking device are useful for the assessment of subjective oral dryness.
7 citations
TL;DR: The time required for swallowing shows a tendency to decrease over time as a subject becomes accustomed to a palate covering, mainly due to shortening of the oral stage.
Abstract: Purpose: The purpose of this study was to elucidate the temporal relationship between habituation to a palate covered by a prosthesis and swallowing function.Materials and methods: Ten healthy adults were selected as subjects. Tongue pressure on an experimental palatal plate with four pressure sensors was recorded simultaneously with surface electromyography measurements of suprahyoid muscles during swallowing of 3 ml of water. Measurements were performed 6 times: immediately after placement of the experimental palatal plate (Day 0), and on Day 1, Day 3, Day 7, Day 10, and Day 14. Temporal changes were analyzed in terms of the order of EMG activity and tongue pressure, and the duration for total swallowing (DTS), oral preparatory stage (DOPS), oral stage (DOS), and pharyngeal stage (DPS).Results: Onset of activity of the suprahyoid muscles was observed significantly earlier in all regions compared to onset of tongue pressure. Onset of tongue pressure in the posterior region was significantly delayed compared to onset of tongue pressure in another region. These results remained constant over the measurement period. DTS and DOS were significantly shortened on and after Days 3 and 7, respectively, compared to the respective values on Day 0. DOPS was significantly shortened on Day 7, compared to Day 0 and 1. DPS showed no significant change over time.Conclusion: The time required for swallowing shows a tendency to decrease over time as a subject becomes accustomed to a palate covering. This was mainly due to shortening of the oral stage.
6 citations
TL;DR: The results of this study demonstrated that the measurement value increased at LM by repeating measurement and increased at 5 minutes after rinsing, and wasn't influenced by measurement time.
Abstract: The aim of this study was to investigate the influence of the measurement condition on the measurement value of an oral moisture checking device. Healthy adults were enrolled to investigate the influence of repeating measurement, rinsing, and measurement time. Oral moisture was measured at the lingual (LM) and buccal mucosa (BM) using the oral moisture checking device. The statistical analysis (Friedman test) was performed to compare the moisture of 3 times' repeating measurement, and the moisture just after rinsing, 3, and 5 minutes after rinsing, and the moisture according to measurement time (at 9:00, and 11:00 a.m., and at 1:00, 3:00, and 5:00 p.m.). As the results of the repeating measurement, there were significant difference between the measurement value at LM of the first time and third time measurement, second time and third time measurement (p<0.01), and the first time and second time measurement (p<0.05). As the results of rinsing, statistically significant difference was found between the measurement value at LM just after rinsing and 5 minutes after rinsing, and 3 minutes after rinsing and 5 minutes after rinsing (p<0.01). There was not significant difference among the measurement time. The results of this study demonstrated that the measurement value increased at LM by repeating measurement and increased at 5 minutes after rinsing, and wasn't influenced by measurement time. It was suggested that practicing the measurement using an oral moisture checking device was necessary, and the measurement could be performed at any time.
5 citations
TL;DR: The load-measuring devices were mounted on the implants inserted in the mandible of a 62 aged female subject to clarify the effect of the number of implants on the loads and to measure the three-dimensional loads exerted on the implant supporting an overdenture.
Abstract: The aims of this study were to measure the three-dimensional (3-D) loads exerted on the implants supporting an overdenture during function in vivo and to clarify the effect of the number of the implants on the loads. The load-measuring devices were mounted on the implants inserted in the mandible of a 62 aged female subject. Either two or four implants connected with a bar were used for supporting her overdenture. The loads on the implants were expressed three dimensionally as load vectors and were analyzed in the coordinates based on the Frankfort horizontal plane and sagittal plane. The tasks examined were maximum voluntary clenching (MVC) and gum chewing (GC). The total load exerted on the implants with a four-implant supported overdenture (4I-Od) was larger than that with a two-implants supported overdenture (2I-Od) at MVC. The maximum occlusal force on the overdenture showed the same manner (p<0.01). The directions of the loads were posterior and lateral at MVC. The total load exerted on the implants located on the working side, was larger than that on the implants located on the non-working side during GC in the case of 4I-Od. The similar manner was also observed in the 2I-Od. The tensile loads were registered during GC. The functional loads exerted on the individual implants in the case of 4I-Od were smaller than those in the 2I-Od. The loads on the implants during function are thus affected by the number of implants supporting the overdenture.
5 citations
TL;DR: Perceived difficulty in swallowing with a palatal plate showed wide individual variation, and covering the palate with a denture showed no effect on tongue pressure.
Abstract: Purpose: The purpose of this study was to clarify the effects of covering the palate with a palatal plate on tongue pressure during swallowing.Methods: We investigated 21 subjects (12 males and 9 females; mean age: 25±2 years). Maximum voluntary tongue pressure and tongue pressure during swallowing were measured with and without the application of an experimental palatal plate. The subjects were asked to compress a pressure probe with a small balloon between the tongue and anterior area of the palate with maximum force, and the peak pressure recorded was regarded as the maximum voluntary tongue pressure. They were also asked to swallow a gelatin drink, and the maximum pressure recorded was regarded as tongue pressure during swallowing. Maximum voluntary tongue pressure and tongue pressure during swallowing recorded with and without the palatal plate were compared. Statistical analysis was performed with the paired-sample t- test. Perceived difficulty in swallowing with the palatal plate was evaluated using a 100-mm visual analog scale (VAS).Results: No significant difference was noted in maximum voluntary tongue pressure or tongue pressure during swallowing between with and without the palatal plate. The mean ± SD of the VAS score for difficulty in swallowing with the palatal plate was 49.3±26.5.Conclusion: Perceived difficulty in swallowing with a palatal plate showed wide individual variation. Covering the palate with a denture showed no effect on tongue pressure.
TL;DR: It is suggested that acrylic resin incorporating FAp-TiO2 prevents the adhesion of C. albicans, indicating a wide range of possibilities for the practical use of new photocatalysts in acrylic resin.
Abstract: Purpose: This study investigated the inhibitory effect of acrylic resin incorporating FAp-TiO2 against the adhesion of C. albicans.Materials and methods: FAp-TiO2 was added at 1, 5, 10 wt% to acrylic resin to form specimen disks of 7 mm diameter, and the surface roughness was measured. Then, C. albicans was cultured aerobically at 37 °C for 24 hours in glucose peptone yeast extract (GPY) broth, and adjusted to OD=1 at 550 nm with a KCl-buffer. The disks were immersed in the C. albicans suspension for 2 hours at 37 °C with UVA from a black light source. After the incubation, the disks were washed gently with phosphate buffer saline (PBS), and the luminescent signal derived from the viable cells on the disks was determined using a bioluminescence adenosine triphosphate (ATP) assay.Results: In the measurement of surface roughness, no significant difference was observed between any of the specimens. The adhesion assay of C. albicans revealed that a statistically significant decrease was observed in FAp-TiO2 when compared with the control (p‹0.01).Conclusion: We suggest that acrylic resin incorporating FAp-TiO2 prevents the adhesion of C. albicans, indicating a wide range of possibilities for the practical use of new photocatalysts in acrylic resin.
TL;DR: The results of this study pose questions regarding the importance of examinations of tooth contact during lateral excursion and occlusal adjustment based on this examination regarding the role of occlusion in the progression of periodontal disease.
Abstract: Purpose: The role of occlusion in the progression of periodontal disease has long been discussed, and occlusal trauma is considered a cofactor that allows absorption of the alveolar bone, which might temporarily or permanently increase tooth mobility. In general practice, occlusion has been evaluated during border and tapping movements to detect and remove premature and non-working contacts. Since previous studies have compared occlusion with periodontal tissue that might have a periodontal problem, it has been difficult to differentiate primary and secondary occlusal trauma. This study focused on primary occlusal trauma and evaluates the relationship between tooth contact during lateral excursions and periodontal status.Methods: Teeth without periodontal disease were studied in 50 men and 50 women and classified into two groups according to the presence or absence of non-working contacts. Probing depth, clinical attachment levels, and tooth mobility were compared between the two groups.Results: There was no significant difference in the Periotest value, probing depths and clinical attachment levels of the first and the second molars between teeth with and without non-working contacts.Conclusion: The results of this study pose questions regarding the importance of examinations of tooth contact during lateral excursion and occlusal adjustment based on this examination. Since the significance of non-working contact as a causative factor of occlusal trauma was not proved, the validity of occlusal adjustment for eliminating non-working contact is questionable.
TL;DR: The patients were partially or completely edentulous individuals who received prosthodontic treatment, including cast partial or complete dentures, at the Tsurumi University Department of Removable Prosthodontics between 1999 and 2007.
Abstract: A review of the statistics and outcomes related to the use of titanium dentures used at the Tsurumi University Dental Hospital between 1992 and 1998 was previously reported. This report contains details of the evaluation of the use of titanium dentures between 1999 and 2007.The patients were partially or completely edentulous individuals who received prosthodontic treatment, including cast partial or complete dentures, at the Tsurumi University Department of Removable Prosthodontics between 1999 and 2007. According to the laboratory instructions at the Tsurumi University Dental Laboratory Center, the denture frameworks were classified as partial (PD) or complete (CD) and fabricated from commercially pure titanium (CPTi), a titanium alloy (Ti Alloy), a cobalt-chromium alloy (Co-Cr), and a Type IV gold alloy (Au-Pt).From April 1999 to March 2007, we prepared a total of 1,470 cast metal plate dentures, 295 (20.1%) of which were made with titanium. CP Ti (Grade 3) dentures were used in 263 patients (17.9%), and Ti Alloy (Ti-6Al-7Nb) dentures were used in 32 (2.2%). The majority of the cast plates were made with Co-Cr (995, 67.7%). CP Ti is well known to be softer and more prone to wear than Ti-6Al-7Nb but is frequently used for the preparation of partial dentures at our University because of its high biocompatibility.CP titanium is favorable because it rarely results in metal allergy, and is lightweight.
TL;DR: The present study indicated that the use of the superstructure with higher elastic material is useful for reducing the mechanical risk of All-on-4 system.
Abstract: The purpose of this study was to investigate the mechanical risk factors of All-on-4 system by analyzing the stress distribution induced on implants and surrounding bone tissue using a 3-dimensional finite element method (3D-FEM). The effects of bone quality and superstructure material property were also investigated.A 3D-FEM model of an edentulous mandible was constructed from computerized tomographic images. The two anterior-most implants were placed in the right and left lateral incisor areas. Two additional implants were placed anterior to the mental foramen with a distal inclination of 40 degrees to the occlusal plane. The 3D-FEM All-on-4 model included a fixed mandibular complete-arch superstructure supported by four implants. Four types of bone (1 to 4) were simulated by varying the Young's modulus for cancellous bone. In addition, three superstructure materials were prepared: acrylic resin, gold alloy, and Co-Cr alloy. A 100 N load was applied on the left first molar region. Stress concentration was observed around the left posterior inclined implants, especially on the distal side. When the cancellous bone is low elastic, greater stress concentration was observed. Of the three materials, the acrylic resin superstructure showed the greatest stress concentration around the inclined implant.The present study indicated that the use of the superstructure with higher elastic material is useful for reducing the mechanical risk of All-on-4 system.
TL;DR: The results suggested that sandblasting could be effective to increase the amount of deflection causing VC cracking in a clasp arm.
Abstract: The aim of this study was to compare different methods for effective adhesion between a glass fiber-reinforced composite (FRC) material for framework and a veneering composite (VC) material for coating framework when fabricating clasps (FRC clasp (with VC)). Vectris pontic and EG fiber were used as FRC materials, the glass fibers of which were preimpregnated with resin. Palfique estelite LV was used as the VC material.Laminate specimens were fabricated by coating FRC with VC (Palfique⁄Vectris, Palfique⁄EG fiber). Five adhesion methods were used when coating the framework. Three specimens were prepared for each adhesion methods. Deflection and load when VC cracked were examined using the three-point flexural test. The mean and S.D. of each value were calculated and subjected to two-way analysis of variance (ANOVA) and multiple comparisons (Bonferroni⁄ Dunn) to determine the significance of the differences (P = 0.05 and 0.01) between the results of the respective methods.The deflection of Palfique⁄Vectris and Palfique⁄EG fiber was 0.497-0.631 and 0.426-0.481 mm, respectively, the load of which was 92.33-108.00 and 60.17-72.50 N, respectively. The deflection and load under all adhesion methods were significantly higher in Palfique⁄Vectris than Palfique⁄EG fiber (P<0.01). In Palfique⁄Vectris, deflection under non-adhesion was significantly lower than under others, but there were no significant differences among loads in different adhesion methods. In Palfique⁄EG fiber, there were no significant differences among deflections and loads in all adhesion methods.In the present study, the results suggested that sandblasting could be effective to increase the amount of deflection causing VC cracking in a clasp arm.
TL;DR: The results of this study suggested that in the patients who requested implant treatment, OHRQoL might be lower than the Patients who requested conventional denture treatment.
Abstract: Purpose: To compare oral health-related quality of life (OHRQoL) with patients who requested implant treatment and conventional denture treatment.Materials and methods: Data were collected by means of self-administered questionnaire during July 2004-January 2005 at four dental offices located in Japan. Subjects who requested implant treatment (IT) were 12, and requested conventional denture treatment (DT) were 19. OHRQoL was measured by the 16-item Oral Health Impact Profile (OHIP-JP16). The OHIP-JP16 total and subscale scores were calculated by summing the 16 items score without weighting. The mean OHIP-JP16 total scores and the mean scores of six subscales (functional limitation, physical discomfort, psychological discomfort, physical disability, psychological disability, handicap) between groups were analyzed by the Mann-Whitney U-test. Chi square tests were used compare responses to individual items. ‘Never’ and ‘hardly ever,’ (no impact) were recorded as ‘0’, ‘occasionally’, ‘fairly often’, and ‘very often’ (any impact) were recorded as ‘1’.Results: The mean age was 62.4 years old in IT and 66.6 years old in DT (p=0.596). No differences in denture status, self-perceived oral health, number of teeth were found between two groups. DT subjects had better OHIP-JP16 total scores than IT, but it was not statistically significant (p>0.05). Chi square tests were performed for each of 16 items. The number of subject reported ‘any impact’ was significantly greater (p<0.05) in IT in the following items; ‘worried’, ‘self-conscious’, ‘avoid eating’, ‘upset’ and ‘life unsatisfactory’. No significant differences were detected in the following 5 subscales; ‘functional limitation’, ‘psychological discomfort’, ‘physical disability’ , ‘psychological disability’ and ‘handicap’, while ‘physical discomfort’ was signify- cantly lower (e.g. higher QOL status) in DT.Conclusion: OHIP-JP16 scores of the subjects who requested implant treatment were significantly higher in ‘physical discomfort’ than requested conventional denture. The results of this study suggested that in the patients who requested implant treatment, OHRQoL might be lower than the patients who requested conventional denture treatment.
TL;DR: Although no interference to sleep was observed, the ambulatory bruxism recording system caused some technical difficulty in a few subjects and more detailed operation manual and simplified software seemed to be necessary.
Abstract: We developed an ambulatory bruxism recording system that analyzes sleep stage. This system enables us to measure sleep bruxism activities in each sleep stage on an electromyographic and auditory basis at home. The purpose of this study was to examine the usability of this recording system. Six volunteers with self-awareness of sleep bruxism were recruited. They were instructed to operate the recording system by themselves and they recorded their bruxism activities at home. Afterward, they were asked to answer the questionnaire on the usability and the influence of the device on sleep. Data recordings were carried out in 3 to 5 nights per subject. All subjects could easily operate this system. Two subjects, however, failed to record in some nights. They reported problems of the sensors falling off from the skin. There was no complaint on disturbance of sleep due to the measurement. Although no interference to sleep was observed, our ambulatory recording system caused some technical difficulty in a few subjects. More detailed operation manual and simplified software seemed to be necessary.
TL;DR: Within the limitations of this in-vitro study on 9 all-ceramic core systems, a significant range of translucency was identified across specimen groups.
Abstract: Purpose: All-ceramic restorations are widely used in esthetic dentistry. Various materials have been used to improve ceramic core strength, but it is unclear whether they affect the opacity of all-ceramic systems. The aim of this study was to compare the translucency of 9 all-ceramic system core materials at clinically appropriate thickness.Materials and methods: A 360-degree round deep chamfer preparation for the all-ceramic crown was made for a maxillary right first molar tooth as the dental model. Coping of 0.5mm thickness were fabricated by Empress Esthetic (ETC1, EOC1, EO1, EO2), Empress2 (50) (IVOCLAR VIVADENT), Procera AllCeram, Procera AllZirkon (Nobel Biocare), LAVA (3M ESPE), and DentaCAD Systeme (Hint-Els). Abutments were made by black wax and white wax. Spectrophotometric measurements were made by a spectrophotometer. The final color of the central part of the buccal surface was measured and the L*a*b* color space was used to obtain the color values. Contrast ratios were calculated from the luminous reflectance (Y) of the specimens with a black (Yb) and a white (Yw) backing to give Yb⁄Yw with CIE illuminant D65 and 2-degree observer function (0.0=transparent, 1.0=opaque).Results: Contrast ratio in order of most translucent to most opaque were as follows: EO2 .41, EO1 .43, ETC1 .43 , EOC1 .44, Empress2 .50, AllCeram .63, AllZirkon .74, LAVA .76, DentaCAD.80. There was no significant difference(p<.05) between the AllZirkon, LAVA, DentaCAD or ETC1, EOC1, EO1, EO2.Conclusion: Within the limitations of this in-vitro study on 9 all-ceramic core systems, a significant range of translucency was identified across specimen groups.
TL;DR: Molar tooth loss may impede learning and memory in rats subjected to a passive-avoidance task consisting of acquisition and retention trials, and hippocampal glutamate release was measured with a telemetric glutamate biosensor.
Abstract: Purpose: To clarify the effects of molar tooth loss on learning and memory, hippocampal glutamate release during a passive-avoidance task was measured with a telemetric glutamate biosensor.Methods: Male Sprague-Dawley rats were used. Under general anesthesia, all the maxillary molars were extracted from the EXT group rats (n = 8); those in the CON group (control, n = 8) were anesthetized without tooth extraction. At age 7 weeks, the rats were subjected to a passive-avoidance task consisting of acquisition and retention trials. Simultaneously, hippocampal glutamate release was measured. First, during the acquisition trial, the rats were placed in a light compartment, and the duration before they entered a dark compartment was measured (reaction latency). Immediately after the rat entered the dark compartment, an electric shock was applied through a grid floor. After 24 h, the retention trial was performed, and the reaction latency was measured in the same manner. Further, a biosensor was used to measure the release of hippocampal glutamate before and after the start of each trial.Results: Regarding the reaction latency during the passive-avoidance task, no significant differences were seen between the groups in the acquisition trial. Reaction latency increased in both groups in the retention trial, but was significantly shorter in the EXT group. Furthermore, hippocampal glutamate release in the acquisition trial was significantly shorter in the EXT group, but in the retention trial, no significant difference in glutamate release was seen between the groups.Conclusion: Molar tooth loss may impede learning and memory.
TL;DR: In this study, displacement of the denture base was smaller in design A than in design B, so design A would be more useful clinically thandesign B, but the abutment tooth would require greater support.
Abstract: Objectives: The purpose of this study was to determine the mechanically appropriate retainer design for unilateral distal-extension removable dentures.Methods: Two models were constructed, each with a different design of retainer placed on the first and second mandibular premolars. Each model was composed of bone, denture underlying mucosa, retainer and denture base. In design A, Akers clasps were set on the first and second premolars, and in design B, an occlusal rest and back-action clasp with mesial rest were set on the first and second premolars, respectively. Loading on the occlusal surface of the denture was performed in the vertical and oblique directions. Load on the abutment tooth and displacement of the denture base were determined by 3-dimensional finite element analysis.Results: Load on the abutment tooth in the vertical direction caused by vertical loading on the denture was lower in design B than in design A. No large difference in displacement of the denture base was observed between design A and B. Load on the abutment tooth both in the vertical and buccolingual direction induced by loading on the denture in the lingual and buccal directions was lower in design B than in design A. However, displacement of the denture base in the vertical and buccolingual directions induced by loading on the denture in the lingual direction was higher in design B than in design A.Conclusion: In this study, displacement of the denture base was smaller in design A than in design B, so design A would be more useful clinically than design B, but the abutment tooth would require greater support.
TL;DR: It is concluded that the RKKP indicated biocompatibility and bioactive property to HGE-15 cells morphologically from SEM and TEM findings in vitro.
Abstract: Purpose: The purpose of this study was histological examination for bioactive glass (RKKP) by using human epithelial gingival cells (HGE-15) through SEM and TEM in vitro.Methods: Commercial titanium alloy (CT), RKKP, Plastic culture dishes (F) were used in this experiment. 10×105 HGE-15 cells were inoculated on the each samples, and cultured for 30 minutes, 1 hour, 2 hours, and 24 hours for SEM. For TEM, HGE-15 cells were cultured for 24 hours and 1 week. The cells were fixed in 2.5% glutaraldehyde, dehydrated conventionally, and subjected to critical point drying. The cells were then coated with gold and examined by SEM. For TEM, HGE-15 cells were fixed in 2.5% glutaraldehyde, postfixed in 1% osmium tetroxide, dehydrated, and embedded in Epon 812. The materials were removed with liquid nitrogen and re-embedded and double-stained, and examined.Results: SEM findings: On RKKP, though increase and spreading of cells were delayed compared with F and CT after 30 minutes, 1 hour and 2 hours, however, samples were mostly covered with polygonal-shaped cells conclusively 24 hours after incubation. TEM findings: We have observed the double-layer structure on F and CT at the interface. On RKKP, recognized the density layer near the interface. HGE-15 cells were bonded directly to the RKKP.Conclusion: We have concluded that the RKKP indicated biocompatibility and bioactive property to HGE-15 cells morphologically from SEM and TEM findings in vitro
TL;DR: It was concluded that variations of the masticatory path of the incisor point was not related to the amount of lateral movement, but was closely and proportionally related toThe amount of vertical movement.
Abstract: Purpose: The purpose of this experiment was to clarify the effect of amount of masticatory movement on variation of path of mandibular incisor point.Methods: Forty healthy subjects were asked to chew softened chewing gum on their habitual side. For the 10 cycles from the fifth cycle of mastication, the opening distance (amount of vertical movement) and the masticatory width (amount of lateral movement) as the indicators representing the amount of masticatory movement, and the standard deviations of the lateral opening, lateral closing, and vertical compoments as indicators representing the variations of the masticatory path were calculated. The relationship between the indicators for the amount of movement and indicators for variations of the masticatory path were investigated.Results: The values of indicators for variations of the masticatory path were large when the opening distance was large, and there was a significant positive correlation between the two (r=0.508-0.685, P<0.01). There was no correlation between the masticatory width and the indicators for variations of the masticatory path.Conclusion: From these results it was concluded that variations of the masticatory path of the incisor point was not related to the amount of lateral movement, but was closely and proportionally related to the amount of vertical movement.
TL;DR: Investigating whether or not abutment tooth support helps to stabilize the overdenture using the dynamics of atmospheric pressure (DAP) as an index of denture stability found that smaller changes of AP reflect better stability of dentures.
Abstract: Purpose: The purpose of the present study was to investigate whether or not abutment tooth support helps to stabilize the overdenture using the dynamics of atmospheric pressure (DAP) as an index of denture stability.Methods: Experimental dentures for measuring DAP were prepared by indirectly relining duplicates of overdentures used by five subjects (1 male, 4 females). The experimental dentures were relieved at the part of the abutment teeth. These dentures were not supported by the abutment teeth (non tooth-supported overdenture). Those were adjusted and used for 1 week. DAP under non tooth-supported overdenture was measured three times at the center of the palatal plate under experimental conditions with and without food in the mouth. After the measurements, non tooth-supported overdentures were immediately placed in contact with the abutment teeth using an auto-polymerizing resin (tooth-supported overdentures). DAP under tooth-supported overdentures was measured in a similar manner to that under non tooth-supported overdenture. Measurements for the respective experimental dentures were compared.Results: Under both experimental conditions with and without food in the mouth, the respective patterns of DAP using tooth-supported overdentures and non tooth-supported overdentures were similar. However, the amount of change of atmospheric pressure (AP) was significantly smaller under tooth-supported overdenture than under non tooth-supported overdenture.Conclusion: It is considered that smaller changes of AP reflect better stability of dentures. Accordingly, the stability of tooth-supported overdenture was superior to that of non tooth-supported overdenture.
TL;DR: Reactions in the cerebral cortex apparently related to dental pain were measured and these reactions varied associated with the degree of pain, and these measurement responses were quick and reactions could be shown within a few seconds during an event.
Abstract: Objective measurement of pain may be useful for dental diagnosis and therapy. The purpose of this study is to measure reactions to pain in the cerebral cortex during dental treatment using NIRS (Near Infrared Spectroscopy), and to assess potential applications of this measuring system in the field of dentistry. Oxygen exchange in the cerebral cortex (oxygenated Hb, deoxygenated Hb and total Hb) was measured to indicate brain function, with and without pain. Also, measured data were mapped using a COE (Cerebral functional mapping of Oxygen Exchange) system. We obtained the following results: (1) reactions in the cerebral cortex apparently related to dental pain were measured, (2) these reactions varied associated with the degree of pain, (3) these measurement responses were quick and reactions could be shown within a few seconds during an event, and (4) the reactions also disappeared quickly after the pain disappeared. The results of this research indicated that this measuring system of brain function has a high potential for use in dentistry.
TL;DR: A choice of appropriate implant system and the consideration about the conditions of implant insertion are significant in order to maintain satisfactory long-term esthetic results.
Abstract: The objective of this study was to observe what influences the differences in implant systems and their configuration and conditions at insertion of implant would cause in change of soft tissue over time after setting of crown, and consequently to clarify what type of clinical treatment should be applied in order to minimize invasion to patients as well as achieve maximum results. This study was conducted through implant-prosthetic treatments with the cases of single tooth loss in maxillary anterior area. The lengths of clinical crown were measured both at the time of setting crown and after follow-up of 4.5 years in average. Used were 60 implants, composed of 26 of Tapered Screw-Vent, 22 of Straumann and 12 of Ankylos. In the cases with Ankylos, whose configuration is of platform switching, the clinical crowns turned out to have got longer only by 0.3mm, while that with Tapered Screw-Vent by 1.1mm and that with Straumann by 1.3mm.Furthermore, the cases with Tapered Screw-Vent were divided into 2 groups according to the conditions of insertion. One group was that the implants were inserted at an angle to the axis of natural teeth and on the labial side, and the other was that the implants were inserted vertically and on the palatal side. The variations were 1.9mm longer in the former group and 0.3mm in the latter respectively. The results obtained, in spite of the use of one implant system, varied according to the seating conditions, and with the cases with Tapered Screw-Vent seated vertically, the variation of soft tissue was as quite small as the cases with Ankylos. It indicates that a choice of appropriate implant system and the consideration about the conditions of implant insertion are significant in order to maintain satisfactory long-term esthetic results.
TL;DR: The data suggest that the depth of palate both at the middle and at the posterior region have an influence on the subjective difficulty in speech immediately after the insertion of a palatal bar.
Abstract: The purpose of this study was to determine the relationship between subjective discomfort⁄difficulty in function after insertion of a palatal bar and location of the bar. Also, the effect of palatal depth was examined. Thirty-four healthy subjects were asked to rate 3 types of bar (anterior, middle, and posterior bar) for 5 items representing various aspects of discomfort and subjective difficulty in function immediately after the insertion of each bar appliance. The palatal depth in anterior, middle and posterior regions was measured for each subject; and the relationship between the rated scores and palatal depth was investigated. In addition, in 12 of the 34 subjects, these palatal bars were inserted; and the score of each item was determined immediately and 3 days after the insertion. The posterior bar showed the highest scores for all items. The anterior bar showed a higher score on the item related to speech, but a lower score on the item related to chewing than did the middle one. The subjects with their palate being deeper at the middle region and shallower at the posterior showed a significantly lower score on the item related to speech than those with a palate deeper at the middle and posterior regions. By 3 days after the insertion of the middle bar, the scores significantly decreased for most of items. Our data suggest that the depth of palate both at the middle and at the posterior region have an influence on the subjective difficulty in speech immediately after the insertion.
TL;DR: It is suggested that the bolus remaining around the epiglottis contributes to an increased risk of aspiration and that observation of the second swallowing sound may be effective in the evaluation of swallowing function.
Abstract: The purpose of this study was to establish a noninvasive method of evaluating swallowing function using swallowing sounds. Four handicapped patients with congenital or postnatal dysphagia were selected as subjects and five healthy, fully dentate males were selected as control subjects. A jelly on the market for the elderly in need of nursing care was used as the test food. Ultra-sound diagnostic equipment and a heart-sound microphone were used to record tongue movements and swallowing sounds. Moreover, an endoscope was used to observe the bolus and larynx. In all healthy subjects, the first swallowing sound before endoscopic whiteout and the second swallowing sound after endoscopic whiteout were detected in the swallowing test. On the other hand, in all subjects with dysphagia, the first swallowing sound and endoscopic whiteout were detected. However the second swallowing sound was not detected clearly in the 3 subjects with congenital dysphagia. Waveforms of an unclear first swallowing sound or second swallowing sound were observed repeatedly in the subject with postnatal dysphagia. A part of the bolus aspirated into the trachea upon inspiration made some patients choke and cough. Our findings suggest that the bolus remaining around the epiglottis contributes to an increased risk of aspiration and that observation of the second swallowing sound may be effective in the evaluation of swallowing function.