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To elucidate the ultrastructure of peri-implant junctional epithelium (IJE) on single-crystal 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 Å 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. [ABSTRACT FROM AUTHOR]

Thirteen healthy adults performed sustained clenching at 50% maximum clenching level judged electromyographically. Electromyograms were recorded from both anterior temporal and masseter muscles during clenching and the silent period latency and duration were measured. As the result of muscle fatigue, the silent period latency significantly decreased, whilst the duration significantly increased up to 3 min from the beginning of clenching. [ABSTRACT FROM AUTHOR]

Pen-implant tissues of the single-crystal sapphire implant connected with neighbouring teeth by a metal bridge-work were examined clinically, radiographically, and histologically in ten monkeys. Professional tooth cleaning was performed during the study. At 3-12 months after insertion, most of the implants were firmly connected to the surrounding tissues and pen-implant girigiva was regarded as healthy, based on various periodontal parameter scores. Destructive changes of the pen-implant bone were not found radiographically. Histologically, pen- implant gingiva was revealed to show similar structure to that of the gingiva around natural teeth. Direct bone-implant interface was observed at 3 months after insertion, while a thin loose fibrous connective tissue layer was present between bone and implant at 6 and 12 months. Such different interrelationship between bone and implant might be attributable to the difference in distribution of functional stress. [ABSTRACT FROM AUTHOR]

Mandibular movement and masticatory performance were evaluated in the edentulous patients with an experimental denture using posterior artificial teeth of different occlusal schemes in order to determine the criterion for the selection of posterior artificial teeth. Lower masticatory performance was observed with non-anatomic posterior teeth than with semi-anatomic or anatomic ones regardless of the condition of residual ridge and inclination of the horizontal condylar guidance. The value of the lateral component of the masticatory cycle was closely related to the inclination of the cusp and the value of masticatory performance. This suggested strongly that the component could be a criteria for the selection of the type of the artificial posterior teeth. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

An objective parameter for the electromyographic evaluation of the masticatory function of edentulous patients was studied. The normal ranges of the parameters for such subjects were also established. This study focused on the time parameter of electromyography, which is one of the most reproducible parameters. The variation coefficient of the time parameters (interval and duration) were revealed to be reliable and reproducible for the evaluation of masticatory functions. [ABSTRACT FROM AUTHOR]

The incidence and virulence of Staphylococcus aureus from upper dentures and tongues of maxillary resection and edentulous patients were examined. The incidence rates of S. aureus on dentures and tongues from the 8 maxillary resection patients were significantly higher than those from the 20 maxillary edentulous patients. Some S. aureus strains in both patient groups were resistant to antibiotics, and 1 methicillin-resistant S. aureus strain was isolated in each group. Exfoliative toxin was not produced, whereas diverse types of enterotoxin were detected in 4 of the 8 maxillary resection patients and in 3 of 13 maxillary edentulous patients. These findings show that S. aureus inhabits dentures and tongues of maxillary resection patients more often than those of maxillary edentulous patients and that some strains have potential virulence, suggesting that maxillary resection patients are potentially more exposed to a threat from S. aureus and would be the carriers. [ABSTRACT FROM AUTHOR]