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Summary In order to assess the tissue compatibility of the hybrid materials for the dental implant (hydroxyapatite, titanium oxide and titanium nitride coated titanium alloys), tissue response to these materials implanted in the rat subcutaneous tissue was histologically examined. Initial inflammatory response was less evident in titanium oxide coated and non-coated titanium alloys. All materials were encapsulated by thin fibrous connective tissues. The membrane thickness of hydroxyapatite coated titanium alloy was significantly higher than that of titanium nitride coated one. These results suggest that all materials possess favourable tissue compatibility and may encourage clinical use as the dental implant.

Summary To elucidate the Ultrastructure of peri-implant junctional epithelium (IJE) on singlecrystal sapphire dental implants connected to the adjacent teeth by a metal superstructure, the peri-implant gingivae of ten monkeys were examined using a transmission electron microscope (TEM) at 3, 6 and 12 months after implant insertion. At the time of examination, the ultrastructural features of the IJE were almost identical to those of junctional epithelium (JE) attached to natural teeth, i.e. developed Golgi complexes, rough-surfaced endoplasmic reticulum, numerous free ribosomes and mitochondria. The innermost cells of IJE were attached to the implant surface by means of basal lamina-like structures (500–1000 A in thickness) and hemidesmosomes, but lacked a dental cuticle as seen on teeth. Such epithelial attachment of the IJE was often indistinct or absent at the apical portion of the IJE which terminated at the level of alveolar crest. A continuous basal lamina-like structure was also present along basal cells at the interface between the IJE and gingival connective tissue except at its apical portion.

Histochemical changes in the three basic fibre types of the deep masseter muscle of the rat were studied following functional stretch due to increased vertical dimension of the occlusion A large number of muscle fibres showed changing histochemical profiles for succinic dehydrogcnase (SDH) and phosphorylase (PhR) during degeneration and subsequent regeneration of muscle fibres. On the other hand, a small number of muscle fibres with well defined sarcolemmas presented a normal pattern (i.e. low SDH and high or intermediate PhR activities) during this experiment. The ratio between the three basic fibre types remained unchanged after recovery of the muscle fibres. These results suggest that fast-twitch-oxidative-glycolytic and slow-twitch-oxidative fibres underwent degeneration and regeneration, while almost all the fast-twitch-glycolytic fibres retained normal SDH and PhR staining following functional stretch.

F or decades dentists have applied clinical skills to partially and totally edentulous patients to provide satisfactory removable dentures.‘-’ Nevertheless, evidence indicates that many patients are not completely satisfied with removable dentures.‘,4,6~*~9 Because of this dissatisfaction, many implant systems have been used in the management of partially and totally edentulous patients.‘O At present, however, there is little information on the acceptance of removable dentures and patient recognition of implant therapy. This study (1) clarifies the removable denture patient’s evaluation of dentures and the recognition of implant therapy and (2) determines the relationship between patient satisfaction with dentures and attitudes toward implant therapy. Table II. Patient recognition of implant therapy

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.

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.)

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.