The aim of this study was to evaluate the longitudinal clinical and physiological changes in masticatory function for unilateral shortened arch, partially edentate patients by treatment with removable partial denture prostheses from the denture insertion over approximately four years of observation. The present follow-up study was conducted using objective findings and standpoints of unilateral occlusal deficit case, especially the clinical and physiological relation between musculature activity and changes of load center location periodically. The changes in masticatory functions by the muscle activity observed in EMG, and the occlusal loads and distributions throughout the arc, were surveyed by the modified Prescale system. The findings were statistically analyzed by using a sophisticated computer system that was developed by our research institute. The results were as follows: i) The functional musculature of unilateral shortened arc patients was clearly activated by using the unilateral RPD, and the improvements continued for four years after initial denture insertion. ii) The activation of masticatory muscle by denture-wearing over time, was in edentate side masseter, although the amplification of anterior temporal muscle was distinct in mandibular cases. iii) The muscle activity during rhythmical motion, such as tapping with denture-wearing, increased about two times than that of two and three years from the starting edentate value similarly to the clenching values within the measured period. iv) The masticatory efficacy of unilateral free end saddle prosthodontics was estimated using the changes in I-EMG values during peanut mastication. These findings suggested that the use of RPD accomplished an arc form and improved masticatory function for agglomeration of foods and masticatory efficiency over time.
Le Fort I osteotomy has been established by many studies and is generally used, but hypoesthesia of the dental pulp, the most common complication, occurs in almost all patients. As such, we examined dental pulp sensibility, pulpal blood flow, and histological changes, to elucidate the process of functional recovery of dental pulp after Le Fort I osteotomy. Monkeys (Macaca fusucata) were used in this study. The animals underwent Le Fort I osteotomy in their unilateral maxillae. Histological and angiographic examinations were performed to observe the postoperative changes in the maxillae and dental pulp. Postoperative pulpal blood flow was examined using a laser Doppler flowmetry. Postoperative pulpal blood flow, by a laser Doppler flowmetry, and dental pulp sensibility, by electrodiagnostics, in patients who underwent Le Fort I osteotomy, were also examined. Although nerve fibers observed in the dental pulp of the maxilla degenerated and disappeared by one week postoperatively, they reappeared sparsely from two to three months after osteotomy, and there were abundant nerve fibers by one year postoperatively. In the angiographic examination, blood supply to the maxillary dental pulp was maintained throughout the postoperative period. In the examinations of laser Doppler flowmetry and dental pulp electrodiagnostics, ischemia in the dental pulp for three or four days after osteotomy might delay the recovery of dental pulp sensibility. These results suggested that blood flow in dental pulp at three or four days after surgery may affect the recovery of dental pulp sensibility.
Squamous Cell Carcinoma (SCC) is the most frequent malignancy in the oral cavity. p53 protein has been reported to be expressed at high levels in malignant lesions, while the level in premalignant lesions has yet to be determined. In this study, oral leukoplakia and oral SCC were examined. Seventy-four incision or excision samples from 43 cases diagnosed as leukoplakia, and 41 samples from 37 SCC cases in the oral cavity, were obtained. All samples (formalin-fixed, paraffin embedded) were examined immunohistochemically for overexpression of p53 protein with monoclonal antibody BP 53-12. As the result, 1. Twenty-two out of 43 leukoplakia cases, and 29 out of 37 oral SCC cases, were positive for p53 protein. 2. p53 protein was overexpressed in premalignant lesions, especially in the cases with moderate and severe epithelial dysplasia. 3. There was a relation between p53 protein expression and pathological features of leukoplakia (epithelial dysplasia), statistically. 4. There was a relation between p53 protein expression and clinical features of leukoplakia, statistically. 5. Malignant transformation during clinical observation was seen in 11 cases. Nine out of 11 cases were positive for p53 even before malignant transformation. Since in cancer-development cases, p53 staining was detected even before malignant transformation of oral leukoplakia to squamous cell carcinoma, it is indicated that p53 accumulation occurred at a early stage of cancer-development. In conclusion, immunohistochemical analysis of p53 protein is suggested to be useful diagnostic procedure for oral leukoplakia, which may develop into oral SCC.
The purpose of this study was to elucidate the relationship between oral manipulative skill and masticatory function. Thirty-six dentate subjects and twenty complete denture wearers were instructed to make their fastest possible movement to bite a small rubber ball 8 mm in diameter repetitively on the right and left posterior teeth by turns. The time for this movement was measured using the Motion Capture System as an index of oral manipulative skill. Masticatory function was evaluated by assessing masticatory performance according to the sieving method. The results were as follows; 1. Among the dentate group, the cycle time of the movement and the masticatory performance of 2g of peanuts (at 10 and 20 masticatory strokes) were significantly correlated. Furthermore, the cycle time and the masticatory performance of 3g of peanuts (at 10 masticatory strokes) were also correlated. 2. The cycle time for the complete denture wearer group was significantly longer than that of the dentate group. 3. Among the complete denture wearer group, the cycle time and the masticatory performance of 2g of peanuts (at 10 and 20 masticatory strokes) were significantly correlated. It is suggested that this index of oral manipulative skill might be related to masticatory function.
The purpose of this study was to investigate the influence of mastication on the amount of hemoglobin in human brain tissue. Nine healthy volunteers (6 males and 3 females) participated in this study. They underwent two tasks: 1) at rest, 2) gum-chewing. In seven of the nine (4 males and 3 females), experimental occlusal interference was applied to the first molar of the mandibule on the habitual masticatory side. They underwent the gum-chewing task. To evaluate the amount of hemoglobin, both the hemoglobin oxygenation state and blood volume during gum-chewing were measured in the frontal region, using near-infrared spectroscopy. The amount of total-hemoglobin (blood volume) and oxyhemoglobin of subjects significantly increased during gum-chewing (p<0.01) . When the subjects finished gum-chewing, both levels returned to the original levels. When experimental occlusal interference was imposed on the subject, the amount of them significantly decreased compared with subjects without experimental occlusal interference (p<0.05) . The results suggested that increases of cerebral blood flow in the frontal region were not due to the mandibular movement, and that human brain activity caused by mastication was not only in the cortical masticatory area but also in the frontal region.
The purpose of this study was to evaluate periodontal wound-healing after the application of enamel matrix derivative (EMD) in rats. Periodontal defects were surgically created on the mesial side of the first maxillary molar of 24 male Long-Evans rats. EMD was applied to cover the denuded root surfaces in the experimental group. The contralateral molar was used for the control group, which received the same treatment without EMD. The rats were sacrificed at 2 weeks (8 rats), 4 weeks (8 rats), and 8 weeks (8 rats) after the surgery. Demineralized paraffin sections were stained with Masson's trichrome. Histological analysis and histomorphometric measurements were performed on the periodontal sections. Using an immunohistochemical technique, the localization of osteocalcin (OC) was also examined. The formation of new cementum was statistically significant in the experimental group, especially new cementum with extrinsic fiber. Both acellular and cellular cementum were also rather strongly observed in the experimental group. Epithelial down growth was also strongly inhibited in the experimental group at 8 weeks after the surgery. OC-positive cells and matrix were limited at the bottom of the defects in the control group, while positive reaction was detected not only at the bottom but also spreading to the coronal portion of the defects in the experimental group. These results suggest that EMD has potential to promote cementum regeneration, especially fiber-inserted cementum, and to create a favorable environment that will promote periodontal regeneration.
The purpose of this study is to know the outline of clinical statistics of new patients at the Clinic for Initial Diagnosis/Emergency, Dental Hospital, Tokyo Medical and Dental University. We examined 1, 001 new patients who visited our hospital from 19 October to 8 December 1995. The results were obtained as follows: 1. Our subjects were 1, 001 patients, males were 357 (35.7%) and females 644 (64.3%) . The ratio of male to female was 1: 1.8. 2. Concering age distribution, the majorities were in their twenties and fifties in order. 3. 71.5% of patients said it took less than one hour for them to come to our hospital. 4. The rate of introduced patients was 5.5% of all the new patients.
The aim of this study was to clarify the entity of localized cemento-osseous dysplasia (COD), which occurs mainly in the posterior mandible. The clinical, radiographical, and histopathological features of 51 patients with COD were retrospectively studied. Radiographic features of the COD were classified into four types, according to the appearance of calcified bodies with related teeth and without related teeth. Pathological features of the COD were classified into four grades, based on the maturation of cemental masses. The results are summarized as follows: 1. Forty-four (86%) of the 51 patients were women. The mean age of the total group was 52.5 years, and 98% of COD lesions occurred in the posterior mandible. Clinical symptoms of COD were significantly more frequent in cases without related teeth (87%) than in cases with related teeth (55%) . 2. The radiolographical calcification of COD was not related to the mean age, but it was related to the grade of histopathological maturation. 3. The four progressive stages of COD were recognizable both radiographically and histopathologically. The early stage is the osteolytic process, the intermediary stage is the cementoblastic process, the mature stage is the cementosclerotic process, and the end stage is necrotization of the cemental mass. These results suggested that localized COD in the posterior mandible had progressive stages both radiographically and histopathologically. The entity of localized cemento-osseous dysplasia was identified with focal cemento-osseous dysplasia, which was reported by Summerlin and Tomich.
The purpose of this study was to evaluate the utility of recombinant human bone morphogenetic protein-2 (rhBMP-2) as a bone substitute on artificial alveolar clefts of adult Macaca fuscata monkeys. First, we created simulated alveolar clefts to represent human bilateral alveolar clefts, and then we implanted a mixture of rhBMP-2 and autogenous particulate marrow cancellous bone (PMCB) into these models, as experimental groups. The mixture ratio was varied as follows (mixture ratio = rhBMP-2: PMCB) . Group 1: rhBMP-2 alone. Group 2: Mixture of rhBMP-2 and PMCB (1 : 1) . Group 3: Mixture of rhBMP-2 and PMCB (3 : 1) . Group 4: Mixture of rhBMP-2 and PMCB (4 : 1) . Positive control group: PMCB alone. Negative control group: PLGA (poly [L-lactide-co-glycolide] copolymer/gelatin sponge complex (PGS) alone. All animals were sacrificed 12 weeks after implantation and evaluated radiographically and histologically. The results were as follows. Bone bridge formation was not observed in Group 1, using rhBMP-2 alone, but it was observed in Groups 2, 3, and 4 using mixture of rhBMP-2 and PMCB. The vertical height of bone bridge formation in Group 4 was equal to that in the positive control group, roughly. The histological finding showed that the bone density of Group 4 was higher than in the positive control group, and the structure of cancellous bone turned into mature type. Bone formation and remodeling was active in Group 4. These results indicated that rhBMP-2 may be an effective substitute for autogenous PMCB in bone grafting into alveolar clefts.
Telomeres, the physical ends of eukaryotic chromosomes, are important to stabilize the chromosome and have a unique simple repetitive DNA sequence, TTAGGG in humans. In most normal somatic cells, telomere length becomes 50-100 by shorter with every cell division, and the cells finally go into senescence, while most cancer cells have been reported to maintain the length and thus are immortalized. Telomeres are replicated by a special transcriptase, called telomerase, which is composed of a template RNA (hTR) and at least two component proteins: hTERT (hEST 2/hTRT) and hTEP 1 (hTLP 1/hTP 1) . In the present paper, I examined the status of telomerase activities in oral squamous cell carcinomas (OSCCs), precancerous lesions, and also cell lines established from OSCCs, by using a non-radioactive PCR-based TRAP (telomeric repeat amplification protocol) assay. Telomerase activities were detected in 23 of 30 OSCCs, 8 of 17 leukoplakias, 0 of 5 normal tissues, and in 8 of 8 OSCC cell lines and 0 of 5 normal human keratinocyte cultures. These results indicated that telomerase activity might have some association with carcinogenesis and might be used as a tumor marker in OSCC.
The purpose of this study was to produce newly vascularized bone, and to form the bone into the desired shape. Silicone molds given the shape of a cylinder were used to deliver collagen sheets impregnated with or without rhBMP-2. The superficial inferior epigastric neurovascular bundle in a Wistar rat was identified and sandwiched between the silicone molds. The molds containing collagen sheets impregnated with 10μg of rhBMP-2 were used for the experimental purpose, and those without rhBMP-2 were used as a control. In some of the experimental molds, the neurovascular bundle was ligated at both proximal and distal sites of the molds. After 2 and 4 weeks operation, bone formation was detected macroscopically, radiologically, and histologically. As a result, newly formed bone was observed in all experimental sites without the ligation, and the shape of the bone was exactly the same shape as the silicone mold. Newly formed bone was supplied by the superficial inferior epigastric artery, whereas newly formed bone was not observed in the control and the ligated flaps. Newly vascularized and shaped bone was created by applying an osteoinductive factor to a neurovascular bundle. This study demonstrates that this experimental model could be a therapeutically potential approach for effective bone reconstruction.
The purpose of this study was to evaluate the effect of an oral appliance (Sleep Splint) for obstructive sleep apnea syndrome (OSAS) patients, and to examine problems with this therapy. Fixed in the oral cavity, the Sleep Splint intends to reduce the occurrence of apnea and prevent blockage of the upper airway during sleep. In this study, the therapy using Sleep Splint was done for 50 patients (41 men and 9 women) who had been introduced by the physician diagnosing with OSAS. Sleep monitoring around an oral appliance mounting was carried out, and the effect was evaluated. In addition, the ESS was used in respect of the evaluation of the daytime sleepiness. However, four patients stopped using the oral appliance due to serious discomfort in the maxillofacial region, and they were excluded from the study. Forty-six patients were classified into three groups by the seriousness of OSAS, or into two groups according to body fatness, and the difference of the effect between each group was compared. The results obtained were as follows. 1. As to the Apnea hypopnea index (AHI), Apnea hypopnea density, Oxygen desaturation, and ESS, there was statistically significant improvement regardless of the seriousness of OSAS and body fatness. 2 . About all patients except for the patient group of the mild cases (AHI < 10), the occurrence of snoring showed the statistically significant improvement. These results indicated that oral appliance therapy was an effective treatment for OSAS.