Purpose: Methods for analysis of occlusal contacts in the intercuspal position(IP) must be certified their levels of reliability, because the use of them without the knowledge is dangerous for implant patients when their teeth might be changed of their shapes based on false data. In this study, reliability of Add-picture was evaluated from intra- and inter-examiner agreements for detection of occluding teeth in comparison with articulating film, shimstock and silicone-black.Methods: Subjects were 20 dental students that 278 antagonistic occlusal pairs without clinical mobility and malocclusions and the patient subjects were 10 implant patients. One of two examiners well trained for all methods examined with articulating film and shimstock, and made registrations of silicone-black for five subjects successively. Then the other examiner followed in the same manner. For intra-examiner agreement, whole procedures were repeated once more. Examinations with silicone-black and Add-picture were performed by the same examiners who made registrations.The data in this study was clearly classified to positive(contact) or negative(no-contact), percent agreement and Kappa statistic were used to analyze inter- and intra-examiner agreements.Result: In intra-examiner agreements of examiner A and B, silicone-black and Add-picture showed higher levels of agreements than shimstock in Percent agreement and Kappa statistic. Articulating film showed the lowest levels of agreements. In inter-examiner agreements of session 1 and 2, there were not clear differences among the methods in Percent agreement and Kappa statistic, except that articulating film showed the lowest levels of agreements. Proportions of positive agreements were greater than those of negative agreements in all methods and examinations.Conclusion: Results that shimstock showed higher levels of agreements than articulating film consisted with those of Anderson1 et al.(1993). Silicone-black and Add-picture showed almost same or little higher levels of agreements with or than shimstock. These results supported that silicone-black and Add-picture could be used as reliably as shimstock for clinical decisions.
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.
Purpose: Radiotherapy influences bone formation at the surfaces of endosseous implants used for maxillofacial prosthetic rehabilitation in patients with oral tumors. We hypothesize that ionizing irradiation affects the differentiation and cellular physiology of osteoblasts, and thereby impairs matrix formation and mineralization during bone wound healing. The aim of this study was to investigate how the dosage of ionizing radiation affects differentiation of osteoblasts in vitro. Methods: Osteoblasts were isolated from the bone marrow of Wistar rats. They were exposed to 0, 40, 400, or 4000 mGy of gamma-radiation (using cobalt-60) and cultured for 5, 7, 10, or 14 days. Assays were performed for cell adhesion and alkaline phosphatase activity. Electron probe microanalysis was used to monitor bone matrix mineralization. The reverse transcription-polymerase chain reaction was used to determine mRNA expression for alkaline phosphatase, bone sialoprotein, collagen I, osteocalcin, heat shock protein 47, and β -actin. Results: Irradiation of less than 400 mGy induced no significant changes in cell adhesion, alkaline phosphatase activity, or osteoblastic gene expression, compared to controls. Electron probe microanalysis indicated that P and Ca signals were more evident throughout the culture period at doses of up to 400 mGy than at 4000 mGy. Bone matrix mineralization was reduced at 4000 mGy. Conclusion: These results suggest that the phenotypic and molecular changes induced in osteoblasts by higher doses of ionizing radiation interfere with differentiation and delay the mineralization of bone matrix.
The purpose of this study was to achieve optimal contrast of imaging characteristics in 4 dimensional MR images of the temporomandibular joint (TMJ) for evaluating the TMJ structures during mandibular movement. Twelve TMJs from six subjects without any TMJ dysfunction were studied. MRI was performed using a 1.5 MR system with an eight-channel phased array coil. The images were acquired using a balanced steady-state free precession (b-SSFP) sequence. The optimal flip angle was determined for differentiation for the main anatomical structures of the TMJ; the posterior band of the articular disc, the retrodiscal tissues, the condylar head, and the lateral pterygoid muscle, by examining the signal intensity (SI-d) of TMJ structures on b-SSFP MR images obtained using various flip angles. Repeated measures two-way analysis of variance (ANOVA) was performed, followed by Bonferroni's multiple comparison analysis. The main anatomical structures of the TMJ had the highest SI-d at flip angles of 30 degrees and 40 degrees, and there were the most significant differences between the SI-d of the articular disc and all other structures at a flip angle of 40 degrees, followed by a flip angle of 30 degrees. These data suggest that a flip angle of approximately 30 degrees to 40 degrees is appropriate for obtaining the optimal contrast of imaging characteristics for 4 Dimensional MR images of the TMJ with b-SSFP sequence.
Patient: A 70-year-old edentulous woman with a flap reconstruction presented Kyushu University Dental Hospital for a masticatory dysfunction because of insufficient retention and stability with her complete denture. She had received 5 implants in the mandible for an implant-supported fixed prosthesis. Although an implant-supported fixed prosthesis could provide improved stability and function, the fixed prosthesis and lack of keratinized mucosa led to the difficulty of cleaning. To improve oral hygiene, an implant-supported overdenture was fabricated after free gingival graft from palate. However, a failure in the graft union and the subgingival plaque resulted in peri-implantitis. The patient received open flap debridement and was treated with antibiotics. Although the patient had used this prosthesis with a slight inflammation for 5 years, a deep pocket was observed around the implant. As a treatment of peri-implantitis, abrasive debridement with beta-TCP was performed. Up to the present, the patient healed uneventfully.Discussion: The implant-supported prosthesis is an alternative to the conventional removable denture and is used to provide predictable retention, stability and function in a flap reconstruction patient. However, we should consider the patient's cleaning ability and the condition of soft tissue around implants.Conclusion: Prosthodontic treatment planning is a complex process that involves various factors such as the surgical factors, occlusion, superstructure and oral hygiene. If we make a plan in the light of these factors, implant-supported prosthesis must offer better function, comfort and predictable result to the patients.
Prosthesis has a close relation with parallel. When installing prostheses, sometimes dentists need to reform abutment teeth or remaining teeth. In the case of partial denture, remaining teeth and its contours should be parallel. In the case of crown & bridge, abutment teeth and pins should be parallel. In the case of implant, success of the following prostheses depends on implant's direction. The ideal preparation is not easy even for skilled dentists, much less for students and beginners. If they use parallel measurements, they would save time and its accuracy gets higher. Therefore, we invented the parallel measurement apparatus which is convenient for clinical use.
The purpose of this study was to compare the response to the treatment of TMD in the two major groups of TMD disc disorders. 80 subjects with disc disorders with reduction who were treated only with behavioral modification and exercise were compared with 30 disc disorder patients as previously reported.1 Data gathered during the examination period was compared with the data after symptom were stabilized. First examination data included the TMD question and answer form, CMI test, and ordinary oral examination data. During the treatment duration, some of the data showed a significant correlation. However, no valid multivariate prediction formula for estimating treatment duration was seen. In the amount of mouth opening, two groups of TMD patients demonstrated different correlations between tenderness sites and amount of mouth opening. Tenderness of anterior temporalis at start of the treatment correlated with treatment duration and mouth opening at the end of the treatment. In patients without reduction group, more tenderness was shown. Result of this study showed that two group of TMD patients may have different responses to the TMD treatment.
Purpose: The aims of using denture adhesives are to provide denture-wearers with improved fit and comfort of their dentures and to improve their chewing ability and confidence. However, there have been few reports on denture-wearers who regularly use denture adhesives, especially among maxillofacial patients. The objective of the present study was to evaluate the usefulness of a denture adhesive in a maxillectomy patient.Materials and methods: The subject investigated in the present study was a maxillectomy patient who had undergone surgical resection and radiotherapy. After delivery of a new dento-maxillary prosthesis, we investigated his speech and masticatory functions objectively using a speech intelligibility test and mixing ability test, respectively.Results: In the speech intelligibility test, the score changed from 22.3% without the prosthesis to reasonable scores of 83.7% with the prosthesis alone and 84.7% with the prosthesis plus the denture adhesive. In the mixing ability test, the score changed from being immeasurable without the prosthesis to scores of -0.48 with the prosthesis alone and 0.10 with the prosthesis plus the denture adhesive.Conclusion: Use of the denture adhesive led a marked improvement of the masticatory function.
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.
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.
In our continually aging society, dental care professionals now have the option of using implants in addition to conventional defect prosthodontics to repair defects, and we can now better respond to a variety of defects. However, there are growing demands from patients for not only the recovery of oral function, but also strong urgings for the therapy to focus on prosthodontic morphology, esthetics, a shortening of the duration of the therapy, and convenience, among others.
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.
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.
Bruxism is a very common parafunction of the masticatory system. Currently, there is consensus about the multifactorial nature of the etiology of bruxism, and it is thought to be a central nervous system phenomenon related to stress and pain behavior rather than structural components. The relationship of bruxism and subjective stress has remained unclear. Recently, biomarkers have been used for assessing stress reaction such as chromogranin A (CgA) and cortisol. The level of CgA provides a sensitive and reliable index for evaluating psychological stress. We can have many reports about plasma CgA, but we can't have enough reports about salivary CgA. The aim of this study was to clarify circadian variation CgA in saliva. Four adults (1 male, 3 females) participated in this research. Subjects provided ten saliva samples. Saliva samples were collected in the morning (9 am) and in the night (21 pm), and every 3 h for 24 h. In addition, saliva samples were two-minute stimulated and unstimulated samples to measure CgA concentration, major salivary stress biomarkers. Unstimulated salivary CgA concentration varied more in time and individual difference than stimulated. Stimulated salivary CgA concentration was increased from 12 pm to 18 pm. Salivary CgA seemed to have a circadian variation with peak in the afternoon-night period and a nadir in the noon. With regard to circadian variations, salivary CgA concentrations, in particular stimulated saliva, hardly differ from plasma CgA. It was concerned that CgA concentration was influenced from a lot of factors.
The principle of dental treatment focuses on to achieve a good balance between “maintaining the residual tissues in healthy condition” and “the functional recoveries”. At first, the two major prerequisite for the residual tissues maintenance are bacterial control and mechanical loading force control, through pre-operative microbial test, and examinations and diagnostics of residual tissues such as temporomandibular joint, muscular groups, existing teeth, periodontal tissues, and residual ridges. Secondly, the functional recoveries are to increase the rate to the utmost of various functions of stomatognathic system as mastication, swallowing, respiration pronunciation and sensation, including aesthetics.
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.
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.
There are the problems of harmful side effect such as allergy and durability of antibacterial effect at the dental materials. The purpose of this study is to develop the dental materials which can solve these problems. And we focus on the anti-microbial proteins, lysozyme (LYZ) which exists in oral cavity commonly. In this study the development of anti-microbial dental cement containing the cation exchange resin which binds anti-microbial protein LYZ was performed. The amount of LYZ binding to the glass ionomer cement and its anti-microbial activity against Streptococcus mutans (S.mutans) were examined. Then the mechanical property of the glass ionomer cement-containing the cation exchange resin was tested. The result presented that the amount of LYZ binding to the cement containing the cation exchange resin was significantly greater than the cement non-containing the cation exchange resin (p<0.05). Moreover, the cement binding with LYZ showed anti-microbial activity against S.mutans. In compression strength test, the strength of cement containing cation exchange resin (3wt%) was lower than cement non-containing cation exchange resin (p<0.05). The findings suggest that glass ionomer cement-containing cation exchange resin binds LYZ and have an anti-microbial activity against S.mutans. After all, the application of cation exchange resin for prosthesis is useful for prevention of dental caries and treatment for the other oral diseases, since the concentration of anti-microbial protein in saliva may increase in oral cavity by this procedure.
