PURPOSEWith an increase in the aged population in Japan, it is important that clinicians evaluate the outcome of complete denture treatment based on evaluation by dentists and patients to provide high-quality treatment. The purpose of this study was to evaluate the evaluation and to clarify the relationship between them by dentists and patients.METHODSForty patients wearing complete dentures were selected, after obtaining informed consent. Scores of complete denture, supporting tissue, chewing function, satisfaction and QOL were the factors used for evaluation. These were evaluated at four stages in complete denture treatment: at the initial visit, before insertion of new dentures (just before), first visit after insertion of new dentures (1st visit) and 1 month after insertion. We compared scores obtained just before and at the 1st visit using t-test, and analyzed changes in scores with correlation coefficient. In addition, the relationship between dentists and patients was analyzed with kappa statistic.RESULTSEvaluation of the new denture was influenced by the evaluation of the old denture. In case of high evaluation of old dentures, evaluation of new dentures tended to decrease. Conversely, in case of low evaluation of the old dentures, evaluation of new dentures tended to increase (p < 0.01) . There was no significant correlation between the evaluation by the dentists and the patients.CONCLUSIONSChanges after wearing new dentures and the relationships were clarified. The disagreement of the evaluation by dentists and patients suggests that both evaluations should be done comprehensively.
It is believed that one of the potential risk factors for peri-implant bone loss and failure of the implant /implant prosthesis may be occlusal overloading. Overloading factors, e.g parafunctions, may negatively influence on implant longevity, however, It must be emphasized that currently there is little evidence regarding implant failure caused by overloading. The purposes of this paper are to discuss the importance of implant occlusion for implant longevity and to provide possible solutions managing complications related to parafunctions. This paper summarizes the lecture presented at the International Congress of Prosthodontics 2007 in Kobe.
Purpose: To evaluate the causes of temporomandibular disorder (TMD) by examining the relationships between 3 major TMD symptoms, parafunction, and stress, a questionnaire survey was performed during dental examinations in corporations.Methods: The survey was performed using 6 questions on the following topics: 1. Trismus; 2. Joint noise; 3. Pain; 4. Clenching in the daytime; 5. Nocturnal bruxism; and 6. Stress.There were 3,225 subjects, 2,809 males and 416 females and the mean age of the subjects was 40.12 years. The relationships between questions 1 to 5 and question 6 were examined by the chi-square test.Results: There were significant correlations (question 1, p=0.001; questions 2-5, p<0.001).Conclusion: Clearly, there was an influence of psychological factors, such as stress, on TMD, and such factors were considered to play important roles in its etiology, progression, and treatment. The results of this study suggest that well-controlled studies of TMD are necessary.
PURPOSE:To develop a new fluorine-containing soft denture lining material, the influences of fluorinated monomers on physical properties and contamination resistance were examined.METHODS:Five experimental materials of different chemical compositions in fluorinated monomer and two plasticized acrylics (Supersoft, VertexSoft) were used to evaluate water sorption, solubility, staining resistance, Shore A hardness, and contact angle. Five specimens for each test were fabricated. The results were analyzed with one-way analysis of variance (ANOVA) and Tukey's HSD test using statistical software at p=0.05.RESULTS:The amount of water sorption tended to decrease as the number of the fluorine atoms in fluorinated monomers increased. Similar solubility was shown regardless of the type of fluorinated monomer. The use of fluorinated monomers for immersion in coffee allowed suppression of discoloration. In beta -carotene, there were no significant differences in color changes among four experimental materials with fluorinated monomer. Shore A hardness was decreased and the contact angles tended to increase as the number of fluorine atoms in fluorinated monomers increased. When comparing the experimental materials and commercially available materials, the experimental materials containing fluorinated monomers with large numbers of fluorine atoms showed adequate clinical properties except for staining test of beta -carotene.CONCLUSION:Monomers with a large number of fluorine atoms can be used to develop applicable soft denture lining materials in clinical practice.
PURPOSE:Clinical findings were compared with glucose, protein, albumin, bilirubin, creatinine, pH, occult blood, ketone body, nitrite, and white blood cells contained in whole saliva to investigate the components that most markedly reflect the periodontal condition.MATERIAL AND METHOD:The subjects were staff of the Prosthodontics Department, Showa University, and patients who visited for dental treatments (57 subjects in total). At the first time, saliva samples were gargled with 1.5 ml of distilled water for 15 seconds and collected by spitting out into a paper cup. At the second time, saliva samples were collected by the same method. At the third time, saliva samples after chewing paraffin gum for 60 seconds were collected by spitting out into a paper cup. Thus whole saliva collecting that was divided on three times. After sampling, 8 mul of the saliva sample was dripped in reagent sticks for the 10 items of urinary test paper and the reflectance was measured using a specific reflectometer. In the periodontal tissue evaluation, the degree of alveolar bone resorption, probing value, and tooth mobility and the presence or absence of lesions in the root furcation were examined and classified into 4 ranks. The mean values in each periodontal disease rank and correlation between the periodontal disease ranks and the components were statistically analyzed.RESULTS:Bilirubin and ketone body were not measurable. The components density of the 8 items was increased as the periodontal disease rank increased. Regarding the correlation between the periodontal disease ranks and the components, high correlations were noted for protein, albumin, creatinine, pH, and white blood cells.CONCLUSION:The simultaneous measurement method of 8 salivary components using test paper may be very useful for the diagnosis of periodontal disease of abutment teeth.
PURPOSE:To clarify the section showing minimal intraindividual variations in the movement of the mandibular incisal point during mastication of softened chewing gum.METHODS:Twenty healthy subjects were asked to chew softened chewing gum on the habitual side for 20 seconds. The change in the spatial parameters (gape and masticatory width) and temporal parameter (cycle time) were investigated for 20 cycles from the first cycle. The coefficients of variation of these parameters were investigated for each of 10 consecutive cycles (first to eleventh series).RESULTS:The spatial and temporal parameters were maximal at the first cycle, decreased progressively until the fourth or fifth cycle, and then remained almost unchanged thereafter. The coefficients of variation of the parameters were maximal during the first series, decreased progressively until the fourth to sixth series, and then tended to increase gradually thereafter. Minimal coefficients of variation were observed during the fifth and sixth series for the gape, during the fifth series for the width, and during the fourth series for the cycle time.CONCLUSION:These results suggest that the ten cycles after the fourth to the sixth cycle was the section showing minimal intra-individual variations in the masticatory movement during the chewing of softened chewing gum.
PATIENT The patient's chief complaint was difficulty of mastication in molar regions. The diagnosis was masticatory dysfunction caused by loss of occlusal contacts. Initially provisional restorations were fabricated, then disharmonious contours were corrected during the following treatments including endodontic and periodontic treatments and tooth extraction. Final restorations were made with fixed partial dentures. DISCUSSION Preservation of the left incisor of mandible enabled recontouring the provisional restoration and consequently, determining a definitive occlusal scheme for the final restoration. CONCLUSION For a patient with collapse of posterior occlusal contacts, hopeless teeth which should be extracted were used as temporary abutment for the provisional restoration. This treatment plan minimized trouble for the patient during treatment, resulting in successful final occlusal reconstruction.
Purpose: The purpose of this study was to investigate whether edentulous patients with a permanent acrylic resilient liner denture (RLD) in mandibles exhibit significant improvements in their satisfaction ratings at the first appointment following the delivery of RLD dentures when compared to those with conventional heat-activated acrylic resin dentures (ARD) in mandibles.Methods: Seventy-four subjects were randomly allocated into RLD and ARD groups by a random permuted block within the strata method after written informed consent. A parallel-randomized controlled clinical trial at two centers was conducted from April 2004 to July 2006. The outcomes were satisfaction ratings with a 100 mm visual analog scale (VAS) involving general satisfaction as well as satisfaction related to chewing, speaking, cleaning, stability, retention, comfort, and esthetics. The pain rating was also measured by the VAS. The outcomes were analyzed by Student t-test and Pearson's correlation coefficient.Results: A significant difference between the RLD and ARD group in the maxillary denture was only obtained in the satisfaction rating of speaking. A significant difference between the RLD and ARD groups for the mandibular dentures was obtained in every satisfaction rating. The pain rating of the RLD group was significantly lower than that of the ARD group. The satisfaction ratings of mandibular denture functions significantly correlated with ratings of comfort and pain.Conclusion: Despite the limitation of a short-term observation, the mandibular satisfaction ratings were dramatically higher in RLD wearers than in ARD wearers.
In recent years "practice guidelines" based on EBM techniques have even been attracting attention at a societal level, and guidelines modeled after the procedure for preparing practice guideline (described at http://www.niph.go.jp/glgl-4.3rev.htm) have begun to be drafted and made public. With the aim of ensuring the quality and presenting the basic concepts of prosthodontic therapy, the Japan Prosthodontic Society, which bears a great obligation and responsibility toward society and the Japanese public, has decided to undertake the formulation of guidelines related to prosthodontic therapy, and decided to first undertake the formulation of "Practice guideline for denture relining and rebasing", and to prepare a guideline model. We tried to prepare the guidelines according to the "Procedure for preparing practice guidelines", but because of the scientific uniqueness of prosthodontic treatment and dentistry, research to elucidate the basis of treatment has been insufficient, and we ultimately reconfirmed the current state of affairs in which it is difficult to perform. We therefore prepared the guidelines based on the limited evidence obtained in a search of the scientific literature and on the consensus of experts. The Japan Prosthodontic Society has investigated and prepared a Society guideline "model" to the extent possible at the present time, and it has prepared "Guidelines for adhesion bridge" and "Practice guidelines for denture prosthodontics" based on it. Nevertheless, the fact of the matter is that we are faced with numerous problems, and we think that in the future new bases and clinical knowledge will be accumulated by promoting scientific clinical research, and that the guidelines should be revised regularly based on them.
PATIENTA 70-year-old woman visited our clinic with a chief complaint of chewing difficulty due to serious periodontitis and an improper RPD. A poor prognosis of the maxillary anterior residual teeth was predicted. However, the patient' s consent for tooth extraction could not be obtained. Consequently, the RPD was designed for the future additional tooth.DISCUSSIONThe maxillary RPD has been functioning for 9 years through repeated additional teeth and repairs. Designing of the metal plate for the predicted prognosis allowed for additional teeth and repairs after losing of the residual teeth.CONCLUSIONDesigning of the denture for the predicted prognosis allowed long-term continuous use of the denture.
PURPOSE:We previously reported correlations between the pressure pain threshold (PPT) at the styloid process, which represents individual pain sensitivity, and PPTs of the masticatory muscles in healthy subjects, and proposed the 95% confidence interval (95%CI) of the PPT at the styloid process as a reference range. In this study, we evaluated its usefulness as a reference range.METHODS:Serial changes in the PPT relative to the 95%CI were studied in 7 healthy subjects. Next, the determination of abnormal sites in the PPT relative to the 95%CI was studied in 7 patients with temporomandibular disorders (TMD).RESULTS:In the healthy subjects, the PPT remained within the 95%CI at all sites. Since the PPT deviated from the 95%CI at some sites in TMD patients, abnormal sites could be determined.CONCLUSION:The 95%CI of the PPT at the styloid process is useful as a means for the evaluation of muscle symptoms of TMD patients.
Purpose: The aim of this study was to develop a means of coordinating helical computed tomography (CT)—based morphological data in 3 dimensions (3-D) with that pertaining to jaw movement as recorded by a device that measures jaw movement in six-degrees-of-freedom (6-DOF), thus producing multi-point movement analysis of the condyle.Methods: The study sample was two volunteers. One of the subjects had erosive bony changes in both condyles, while the other had healthy condyles. We employed a customized facebow, which enabled us to coordinate jaw movement data and morphological volume data from CT. Total uncertainty of the coordination was computed, according to International Organization for Standardization (ISO). In order to demonstrate the effects of multi-point analysis for complex condylar movement, we tried to visualize the trajectory of the working condyle in lateral excursion.Results: The overall uncertainty at a condylar center chosen as an example to illustrate the method was 0.38 mm, 0.19 mm, and 0.50 mm in antero-posterior, latero-medial, and supero-inferior directions, respectively, in terms of 95% coverage as defined by the ISO.Conclusion: We developed facebow-based X-ray markers with high clinical operability, which could correlate the helical CT's coordinate system with our 6-DOF jaw movement measuring system for precise analysis of 3-D condylar movements. In motion analysis of rotational condyle, even a small amount of measurement error cannot necessarily be neglected. Then, a multi-point approach such as that realized by our system presents the best option.
PURPOSEThe aim of this study was to determine the adaptability of fracture toughness evaluation and the relationship between three testing methods: single-edge notched beam fracture toughness test (SENB), indentation fracture toughness test (IF), and notchless triangular prism fracture toughness test (NTP).METHODSTwo types of indirect composite, Ceramage and Estenia C&B, were used. Four types of experimental specimens were prepared under two curing conditions for each composite resin. One curing condition was only light curing and the other was heat curing after light curing. The fracture toughness value (K(Ic)) of the experimental specimens was measured by each of the three fracture toughness tests. K(Ic) of each test was compared by ANOVA and Tukey's multiple comparison test for the adaptability of fracture toughness evaluation. Then the correlation of two tests was evaluated by a simple linear regression analysis.RESULTSEvaluation of the load-strain curve (or load-deflection curve) and fracture surface observation of SEM suggested the plane strain fracture phenomenon. K(Ic) values obtained by the three testing methods were significantly different (p<0.01). SENB could separate significantly these experimental specimens into four groups. IF could separate them into two groups. NTP could separate them into three groups. The fracture toughness evaluation of NTP was almost the same as that of SENB. The relationship between SENB and NTP showed a significant correlation (R(2)=99.7%) and its equation was NTP (K(Ic))=0.82 SENB(K(Ic))+1.05. IF did not show a significant correlation.CONCLUSIONThese indirect composites tested exhibited different fracture toughnesses. This difference occurred due to the contents and curing conditions. The adaptability of fracture toughness evaluation showed different values depending on the testing method. The relationship of SENB and NTP showed a significant correlation.
PURPOSE:The purpose of this study was to clarify the effect of different chewing rates on salivary cortisol levels as a stress indicator.METHODS:The subject group consisted of 16 healthy males. They were required to rest for 30 min, and then given arithmetic calculations to perform for 30 min as stress loading. Immediately after, the first set of saliva specimens (S1) was collected over a period of 1 min to measure cortisol levels. Next, they were asked to chew a tasteless gum base for 10 min, and the second set of saliva specimens (S2) was collected in the same manner. They were then required to rest for 10 min, after which the third set of saliva specimens (S3) was collected. Chewing rates were set to slow, habitual, and fast in time with a metronome. Salivary cortisol levels were analyzed by radioimmunoassay. Changes in salivary cortisol levels comparing S1 with S2, and S1 with S3 were determined.RESULTS:Changes in salivary cortisol levels between S1 and S2 showed a reduction of 4.7%, 14.6%, and 16.2% with slow, habitual, and fast chewing, respectively. A significant difference was observed between slow and fast chewing. Changes in salivary cortisol levels between S1 and S3 showed a reduction of 14.4%, 22.2%, and 25.8% with slow, habitual, and fast chewing, respectively. A significant difference was observed between slow and fast chewing.CONCLUSION:This study showed that differences in chewing rate affected salivary cortisol levels as a stress indicator, and suggested that the effect on stress release with fast chewing is greater than that with slow chewing.
PURPOSE To elucidate the influence of the improvement of denture function on brain activity in complete denture wearers. METHODS Eighteen complete denture wearers (5 males and 13 females, 63-87 years, mean: 75.2 years) participated in the study. To evaluate denture function, the occlusal contact area and occlusal force were measured for comparison before and after denture treatment using the Dental Prescale Occluzer (GC Co., Tokyo, Japan). To evaluate brain activity, electroencephalogram data obtained using an electroencephalographic measurement apparatus ESA-pro (Brain Functions Laboratory, Inc., Kanagawa, Japan) were analyzed using DIMENSION (Diagnosis Method of Neural Dysfunction). The duration of the measurement was 3 minutes before and after denture treatment. RESULTS The occlusal contact area significantly increased after denture treatment in all 18 subjects (p<0.05). The occlusal force significantly increased in 17 patients (p<0.05). Activation of brain activity was noted in 14 of the 18 patients (p<0.05). Measurement before denture treatment showed that 12 patients were in the sub-normal/impaired region and 6 were in the normal region. After denture treatment, brain activity was significantly activated in all 12 patients who were in the impaired/sub-normal region before treatment. CONCLUSION An improvement in denture function was observed after denture treatment in complete denture wearers, and brain activity was enhanced by the functional improvement in the complete dentures. Not only denture function improvement but also brain functional activation was achieved by denture treatment in elderly complete denture wearers who were at risk of brain activity deterioration.
PURPOSE:Neck pain is one of the main symptoms of temporomandibular disorder. Muscle activity of the sternocleidomastoid muscle during occlusion has been clarified in recent years. We reported that when healthy individuals were instructed to chew rapidly, the activity of the sternocleidomastoid muscle responded to activity of the masseter muscle, however, during voluntary jaw opening, activity of the sternocleidomastoid muscle did not respond, but worked actively due to motor programming. The objective of the present study was to investigate the learning effects of repetitive training, that is, changes in activity mode of the neuromuscular system.MATERIALS AND METHODS:The sternocleidomastoid and the anterior belly of digastric muscles in 8 healthy male adults were analyzed. In response to acoustic stimulation, each subject was instructed to open their mouth as quickly and widely as possible a total of 30 times with a break between measurements. EMG-reaction times (RT) of the sternocleidomastoid and anterior belly of digastric muscles were measured, and the length of time from the start of EMG activity of agonist to the start of actual movement was measured.RESULTS:In all subjects, at first measurement, EMGRT of the sternocleidomastoid muscle did not precede that of the anterior belly of digastric muscle. With each measurement, the difference in EMG-RT between the sternocleidomastoid and the anterior belly of digastric muscles decreased, and in 6 of the 8 subjects, EMG-RT of the sternocleidomastoid muscle preceded that of the anterior belly of digastric muscle.CONCLUSION:Repetitive task movement alters the start times of muscular activities, and from the perspective of EMG kinesiology, motor learning effects were confirmed with maximum ballistic voluntary jaw opening.
PURPOSE:To date, the minimum thickness required for a mouthguard has been assumed to be around 2 mm to 4 mm. However, this figure is based mostly on experience and is yet to be standardized. The purpose of this study is to determine the minimum thickness required to obtain sufficient energy absorption.METHODS:The thicknesses of the tested ethylene vinyl acetate) samples were 1, 2, 3, 4, 5, and 6 mm. The pendulum- type testing equipment used in the present study was also used in a series of earlier studies. Three types of sensors (strain gauge, accelerator, and load cell) and two different impact objects (a steel ball and baseball) were used.RESULTS:The results showed that all the above-mentioned mouthguard thicknesses reduced shocks for all the three types of sensors and both types of impact objects; little difference was observed between sensors and clear results were obtained for the steel ball. An improvement in the energy absorption was observed with an initial increase in the thickness. However, a further increase in the thickness from 4 mm to 5 mm and 6 mm tended to yield a smaller improvement in energy absorption.CONCLUSION:Within the limitations of this study, from the viewpoint of energy absorption ability, the minimum thickness required for a mouthguard is 4 mm, which is generally too large from the viewpoint of player comfort. This finding indicates the necessity of improving the impact absorption ability of mouthguards by considering new designs and developing new materials.
PATIENT The patient was a 75-year-old woman who underwent maxillary bone resection due to maxillary left gingival carcinoma. The treatment denture for defected jaw was applied, and adjustment was done several times. Thereafter, the final denture for defected jaw was inserted. DISCUSSION We applied the hollow-type obturator for the treatment denture for defected jaw. Because we considered that adjustment of the hollow-type obturator was easier than buccal flange type because of the patient's deficient ability of mouth opening. Adjustment was done several times; thereafter, the final denture of which the obturator was buccal flange type, was applied for optimal fitting. CONCLUSION It was important to select a suitable form of the obturator acceptable to the condition of the patient.
A firmly established theory on occlusion, even with natural teeth, has been all but absent throughout history. it is even more difficult to find and evidence-based concept of occlusion for the relatively new field of implantology. Since i harbored doubts on initial gnathological theories of occlusion decades ago, my work in treating occlusion in patients with temporomandibular arthrosis has brought me to the realization that the diagnosis and adjustment of the alignment or misalignment of the light guide tapping position ( LGTP ) and clenching position (CLP) in the stable condylar position are important focal points for clinical occlusion. I have therefore striven for the seamless incorporation of the prosthodontic techniques of maintaining, correcting, and restoring occlusion into my day to day clinical practice, which includes periodontal treatment and orthodontics. Implantology has now been added to this context, and i feel there is no need to take a drastically different approach to creating and adjusting implant occlusion. I will present actual case reports and post operative observations of patients who received implant therapy in our clinic.
PURPOSE:The purpose of this study was to apply in vivo modal analysis to the maxillary dentition of the maxillectomy patient using obturator prostheses which were different in lateral wall height of the bulb: specifically a high type (H type), middle type (M type), and low type (L type).METHODS:The left central incisor was struck with an impact hammer, and the response at each measurement point was detected using a Laser-Doppler vibrometer. The transfer function was then obtained from each measurement point using a fast Fourier transform analyzer. Finally, a computer analysis and simulation were performed based on the measured transfer functions to obtain the natural frequency, modal shape decay rate (DR), and maximum displacement (MDP).RESULTS:The results showed that the natural frequency was different between with and without obturator prostheses, that the modal shapes with M and L type obturator prostheses are more suitable than that with H type. The DR of the maxillary dentition with the L type was significantly higher than that with the H or M types, and the MDP of the maxillary dentition with an obturator prosthesis was significantly lower than without an obturator prosthesis.CONCLUSION:From the standpoint of vibratory characteristics, the L type obturator prosthesis is the most suitable bulb design for the patient of the three types obturator prostheses. This is the first report to apply in-vivo modal analysis to the maxillary dentition of the maxillectomy patient using obturator prostheses and clarify the vibratory characteristics of the dentition.
