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An attempt was done to evaluate clinical figures in the first examination of mandibular dysfunction patients with two or more symptoms of temporomandibular joint (TMJ) pain, TMJ sounds and limitation of mandibular movement followed by no organic change in the TMJ. The results were as follows:1. A great prevalence of female was seen and the ratio of female/male was 9 to 1.2. In age distribution, the patients of 10 years old to 19 and 20 to 29 were predominant.3. Most patients were treated by restorative therapies and few of them had experiences of several general diseases.4. Evaluating the chief complaints associated with the first symptoms, TMJ pain was much predominant in comparison with TMJ sounds.5. Clinical symptoms were expressed by TMJ pain, TMJ sounds and limitation of mandibular movement with other symptoms as headache, neck and shoulder pain and ear symptoms.6. Most patients had natural dentitions. Premature contacts were seen in centric relation in all patients and more than half of them had occlusal interferences in eccentric relations.7. The remarkable presence of oppressive pains in masticatory muscles was observed. The finding that factors which might be associated with muscle tensions were seen in many patients suggest the correlation between mandibular dysfunction and muscle hyperactivity.

The clinical effect of full coverage occlusal splint during 13 weeks insertion was investigated in 30 mandibular dysfunction patients with two or more symptoms of temporomandibular joint (TMJ) pain, TMJ sounds and limitation of mandibular movement followed by no organic change in the TMJ, who were reported in part 1 of this study.A remarkable effect of occlusal splint was obtained and 86.7% of the 30 patients were improved totally. Especially, the symptoms, TMJ pain and shoulder stiffness were much improved, but less effective was seen to buccal pain and temporal headache. The period of producing the effect of occlusal splint was different to each symptom, but no change was seen after 10 weeks in any symptoms.These results clearly show the effect of full coverage occlusal splint for mandibular dysfunction patients and useful suggestion of occlusal splint therapy to this disease was obtained.

Artificial bone has been employed to reconstruct bone defects. However, only few reports on implant placement after block bone grafting exist. Objectives The purpose of this study was to evaluate the osseointegration of dental implant in bone reconstructions with interconnected porous calcium hydroxyapatite (IP-CHA). Material and Methods The IP-CHA cylinders (D; 4.3 mm, H; 10.0 mm) were placed into bone sockets in each side of the femurs of four male dogs. The IP-CHA on the right side was a 24-week sample. Twelve weeks after placement, a titanium implant was placed into a socket that was prepared in half of the placed IP-CHA cylinder on the right side. On the left side, another IP-CHA cylinder was placed as a 12-week sample. After another 12 weeks, the samples were harvested, and the bone regeneration and bone-implant contact (BIC) ratios were measured. Results New bone formation area was superior in the 24-week IP-CHA compared with the 12-week IP-CHA. BIC was not significantly different between IP-CHA and the parent sites. Osseointegration was detected around the implant in IP-CHA-reconstructed bone. Conclusion Our preliminary results suggest that IP-CHA may be a suitable bone graft material for reconstructing bones that require implant placement.

Purpose: The Japan Prosthodontic Society (JPS) has proposed a new diagnostic nomenclature system (DNS), based on pathogenesis and etiology, to facilitate and improve prosthodontic treatment. This systemspecifies patient disability and the causative factor (i.e. ‘‘B (disability) caused by A (causative factor)’’). The purpose of this study was to examine the reliability and validity of this DNS. Study selection: The JPS Clinical Guideline Committee assessed mock patient charts and formulated disease names using the new DNS. Fifty validators, comprising prosthodontic specialists and dental residents, made diagnoses using the same patient charts. Reliability was evaluated as the consistency of the disease names among the validators, and validity was evaluated using the concordance rate of the disease names with the reference disease names. Results: Krippendorff’s α was 0.378 among all validators, 0.370 among prosthodontic specialists, and 0.401 among dental hospital residents. Krippendorff’s α for 10 validators (3 specialists and 7 residents) with higher concordance rates was 0.524. Two validators (1 specialist and 1 resident) with the highest concordance rates had a Krippendorff’s α of 0.648. Common disease names had higher concordance rates, while uncommon disease names showed lower concordance rates. These rates did not show correlation with clinical experience of the validator or time taken to devise the disease name. Conclusions: High reliability was not found among all validators; however, validators with higher concordance rates showed better reliability. Furthermore, common disease names had higher concordance rates. These findings indicate that the new DNS for prosthodontic dentistry exhibits clinically acceptable reliability and validity.

Masticatory function of 10 telescope denture wearers in the Kennedy class II mandible patients was evaluated with electromyography. Electromyographic activity during mastication with kamaboko and peeled raw carrot was recorded from bilateral masseter and the anterior part of temporal muscles at each interval: Before treatment, immediately after denture insertion and 2, 4, 6, 8 weeks after respectively. Mean of duration, interval and cycle of EMG activities, coefficient of variation and average variation were calculated. The results were as follows: 1. Means of duration and cycle times decreased immediately to 2 weeks after denture insertion. 2. EMG activities during raw carrot chewing became regular immediately to 2 weeks after denture insertion, and within 4 weeks in kamaboko chewing. These results suggest that telescope dentures would be adapted to stomatognathic system within short period after denture insertion.

A procedure for extension of the maxillary denture base for development of a posterior palatal seal is described. The technique involves provisional extension with paraffin wax and adding direct relining resin supported by a silicone putty core. This simple, quick procedure achieves immediate recovery of retention for underextended maxillary dentures without additional laboratory procedures.

summary The aim of this study was to investigate whether there were sex differences in the electro-myograms (EMG) of the masticatory muscles and in the mandibular movement of young adults when chewing food. Twenty subjects with normal dentitions were selected. The II test foods selected were all easily available in Japan. The results showed firstly that although there were no significant differences of chewing frequency between males and females, females chew food more slowly with less masticatory force and narrower mouth opening width than males; and secondly it appears that the chewing function in females is lower than in males.

Reproducible and quantitative evaluation of patient satisfaction with their complete dentures is of great importance for preoperative diagnosis, treatment planning and assessment of complete denture treatment outcome. This study attempted (1) to clarify the degree of contribution of various factors to overall satisfaction, and (2) to develop a method for quantitative assessment of overall satisfaction with complete dentures. Twelve satisfaction factors and a three-grade scale were used to assess 302 complete denture patients. The contribution of each grade of the 12 factors to the overall satisfaction level was determined by multiple regression analysis. Seven factors were highly correlated to the overall satisfaction. Based on the level of contribution by these seven significant factors, a scoring method for satisfaction was established. Category scores for these factors were calculated and the sum of the category scores was converted to an integer between 0 and 100. The resulting quantification score was closely correlated with overall satisfaction. A protocol for scoring overall satisfaction was developed based on the scientifically analysed contribution of each satisfaction factor.

In order to establish diagnostic and treatment system for temporomandibular (TM) disorder patients, data were collected on mandibular border and tapping movements at incisive point and compared with those from the subjects without any TM disorders. Significant differences on the ratio of left and right sides of maximum lateral deviation, maximum opening amount and length of pathway of lateral border movement were clearly obtained, the values of maximum speed and acceleration of closing phase in tapping movement obtained from TM disorder patients were also different significantly from those in the control subjects. These findings suggests that those measured indices in this study would be useful for diagnosis of TM disorders.

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

Statement of problem. Reproducible and quantitative clinical evaluation of complete denture prostheses is of great importance for preoperative diagnosis, treatment planning, and assessment of quality of denture treatment. Purpose. This study attempted (1) to clarify the degree of contribution each clinical factor made to the general assessment of experienced prosthodontists to complete denture prostheses, and (2) to develop a method for quantitative assessment of complete denture quality. Methods. Sixteen clinical factors with a three-grade scale were used to evaluate complete denture prostheses in 320 patients. The general assessment of the dentures was conducted with a 10-point scale. The contribution of each grade of the 16 factors to the general assessment level was determined by a multiple regression analysis. Results. Seven factors were highly correlated to the general assessment. On the basis of these significant contributions, a complete denture scoring method was established followed by the calculation of the category scores of these factors and conversion of the total sum of each category score to an integer number between 0 and 100. The resultant quantification score was closely correlated with the general assessment of the denture. Conclusion. An evaluation protocol used for scoring of complete dentures was developed based on the scientifically analyzed knowledge of experienced prosthodontists. (J Prosthet Dent 1998;80:52-7.)

More validity of finite element analysis in implant biomechanics requires element downsizing. However, excess downsizing needs computer memory and calculation time. To investigate the effectiveness of element downsizing on the construction of a three-dimensional finite element bone trabeculae model, with different element sizes (600, 300, 150 and 75 microm) models were constructed and stress induced by vertical 10 N loading was analysed. The difference in von Mises stress values between the models with 600 and 300 microm element sizes was larger than that between 300 and 150 microm. On the other hand, no clear difference of stress values was detected among the models with 300, 150 and 75 microm element sizes. Downsizing of elements from 600 to 300 microm is suggested to be effective in the construction of a three-dimensional finite element bone trabeculae model for possible saving of computer memory and calculation time in the laboratory.

An I-bar clasp is a popular retainer for distal-extension removable partial dentures. However, there have been almost no evidence-based criteria on the mechanically preferable shape. The present study aimed to investigate the variations of dimension in I-bar clasps used in patients, and to clarify the effect of the variations on stiffness and stress of I-bar clasps by finite element analysis. Dimensions (thickness, width, taper, radius of curvature, length, relation to oral structures) of 23 I-bar clasps were measured. A three-dimensional finite element model was made for each measured I-bar clasp with vertical and horizontal straight sections connected with a curved section. A concentrated load of 5 N was applied at the lowest point of the tip that contacted the abutment in the buccal direction. Maximal equivalent stress and stiffness of each clasp were evaluated. The measured dimension, stiffness, and maximum stress showed wide variations. Mean stiffness was far from the proper one, and mean stress was near the proportional limit of Co-Cr alloy. Considering the stiffness and stresses in this study, only six clasps out of 23 were appropriate. These results suggest that evidence-based criteria of preferable shape of I-bar clasps should be determined.

Muscle fatigue due to clenching, grinding is suggested to be in relation to the pain in TMJ dysfunction patients. A number of investigators report that in normal pe rsons experimental muscle fatigue provoked the similar symptoms seen in TMJ dysfunction patients. These reports suggest that muscle fatigue plays a great role in the onset of TMJ dysf unction.The purpose of this study was to investigate the effects of muscle fatigue on the silent period of normal subjects. The results were summarized as follows:1. The silent period during tooth tapping was either absent or incomplete after muscle fatigue. This tendency is seen in patients with TMJ dysfunction.2. In one subject, double silent periods occurred. After muscle fatigue, the subject may be to have a lower pain threshold.3. The silent period following jaw-jerk showed significantly shorter latency and longer duration after muscle fatigue. The longer duration may be observed that double silent merged together.4. In the present study, the silent period is suggested to be useful in the diagnosis and prognosis of TMJ dysfunction.

It has been observed that in speaker‐independent multi‐template digit recognition, the 5th‐order perceptually based LP (PLP) analysis method yields about 40% lower error rates than does the standard 14th‐order LP. In speaker‐dependent recognition, the 5th‐order PLP model yields essentially the same recognition accuracy as do high‐order PLP or standard LP models. In order to clarify the reasons for this result, RPS distances for LP and PLP models of single‐frame phoneme‐like spectra of male and female speakers were computed and arranged into distance matrices. Single‐speaker 10th‐order model matrices were adopted as the reference matrices for both LP and PLP methods. Cross‐speaker PLP matrices become more similar to PLP reference matrices as the model order of cross‐speaker matrices decreases to the 4th order. LP cross‐speaker matrices remain relatively similar to the 5th order. Single‐speaker PLP matrices remain relatively similar to the 5th order of the model while the single‐speaker LP matrices of lower order differ significantly from the high‐order ones. These results agree well with recognition rates obtained in the cross‐speaker alpha‐digit recognition for the same speakers. Results support the F1, F2′ theory of speech perception.