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Biomedical subjects

Y Sawaki

Publications and source records attributed to Y Sawaki.

At least 19 recordsLinked to original sources
PubMed2004

Experimental study of mechanical analysis in mandibular lengthening. Application of strain gauge measurement.

In distraction osteogenesis, the assessment of new bone formation and the decision of when to remove the distraction device are very important from clinical viewpoint. The purpose of this study was to measure bone stiffness using a strain gauge during and after mandibular lengthening, and to compare the results with those from radiographic and histological examinations. Twelve adult mongrel dogs served as the experimental subjects. An external distraction device was connected to the mandible, and distraction was started 7 days after operation and continued for 10 consecutive days. The animals underwent strain gauge measurement and radiographic examination of the mandible at the completion of distraction and every 2 weeks until the end of the consolidation period. The animals were then sacrificed at 2, 4, 6, 8, 10, and 12 weeks after completion of the distraction for histologic examinations. There was correlation between the amount of decrease in strain, increase in ratio of radiopacity, and newly formed bone in the distracted area.

Animals↗
PubMed2001

The fate of developing teeth in mandibular lengthening by distraction: an experimental study.

Purpose: The purpose of this study was to observe developing teeth in a lengthened mandible after distraction. Material: Ten mongrel dogs with deciduous dentitions were used. Methods: A corticotomy was carefully made around a tooth bud and the external distractor (Orthofix M-100((R))) was connected. After a 5-day latent period, distraction was started at a rate of 0.75 mm per day for 10 consecutive days. Then, the lower jaw was stabilized by an external fixation to allow ossification. While the operation was performed on the left side (Distraction group), the contralateral side was studied for comparison (Control). In addition, a corticotomy, artificial fracture and external fixation were carried out to confirm the influence of the operation (Fracture group). Then macroscopic, radiographic and histological evaluations were carried out. Results: In the Distraction group, the space between the wall of the dental follicle and the crown expanded as distraction began. The end of the calcified root became wider and irregular during the distraction period, and finally, the apex closed. In the Fracture group, the teeth erupted although slight alterations of the root shape were observed in association with the operation period. Conclusion: The root became irregular, but the teeth erupted within the distraction area. Copyright 2001 European Association for Cranio-Maxillofacial Surgery.

Journal Article↗
PubMed2001

Spatial image of school environment in children with cleft lip and/or palate.

To evaluate the adaptability of children with cleft lip and/or palate to school, their mental images of the school environment were investigated in a semantic differential method survey using 23 pairs of adjectives. The following eight places on and off the school grounds were chosen as environmental factors; classroom, gymnasium, school nurse's office, teachers' office, playground, hallway, road leading to school and road leading back home. 50 children with cleft lip and/or palate (ages 10-11 years) were enrolled in this study. These children had a feeling of liberation in the teachers' office and school nurse's office. However, they did not have an established feeling of relaxation or affinity in the classroom, gymnasium, playground, hallway, or on the road to and from school, the very locales that were the main areas of their school activity. This suggested that self-expression and adaptation were difficult for these children.

Adaptation, Psychological↗
PubMed2000

Psychological study of cleft palate children with or without cleft lip by kinetic family drawing.

To clarify how cleft palate children with or without cleft lip perceive their family, we applied the Kinetic Family Drawing (KFD) technique to 60 cleft palate children (with or without cleft lip). The children were aged 7-9 years (in the 1-3 grade of elementary school) and attended the Department of Oral Surgery, Nagoya University Hospital, between 1990 and 1997. Controls consisted of 100 normal elementary school children of the same age. Major findings were: (1) Compared with normal children, cleft lip and palate boys and cleft palate only girls drew their self-images significantly more often in region D (lower right) and in region A (upper left), respectively. (2) Cleft palate children with or without cleft lip felt anxiety and fear toward their family, rarely viewing their homes as a restful place; this suggested insecurity. Uniquely dynamic relations were also suggested in their homes. (3) Cleft palate children with or without cleft lip often perceived their father or mother as persons easily acceptable in society. Rather remote psychological distance between parents and cleft palate children with or without cleft lip was suggested.

Activities of Daily Living↗
PubMed1999

Clinical application of cultured oral epithelium for palatal wounds after palatoplasty: a preliminary report.

OBJECTIVE: Mucoperiosteal defects of the hard palate after palatoplasty scar causing scar contraction, leading to poor growth of the maxilla. The promotion of wound healing in these cases through cultured epithelial allografting has been reported. Cultured epithelial allografting was done using allogeneic cultured cells, in the hope of improving growth of maxilla. SUBJECTS AND METHODS: Clefts of the soft and hard palate (seven patients), and a cleft of the soft palate (two patients) were present. Average patient age was 1 year 4 months. Palatoplasty was done by a conventional push-back operation. Oral epithelial cells from healthy adults were cultured using 3T3 cells as the feeder layer. After 3 weeks, cultured oral mucosal epithelium was grafted on a raw surface following palatoplasty. RESULTS: The result was compared in two patients who had undergone push-back operation only. In all patients, the grafted areas underwent re-epithelialization after about 1 week and did not exhibit any clinical signs of graft rejection. Grafted areas healed completely after 2-3 weeks in all cases. CONCLUSION: Cultured epithelial allografts serve as a temporary biological dressing, and accelerate epithelialization and wound healing. Allografting by cultured oral epithelium has proved to be a very useful therapeutic modality in palatoplasty, as well as effective augmentation materials in cases of oral mucosal defects.

3T3 Cells↗
PubMed1999

Alveolar ridge augmentation by distraction osteogenesis using titanium implants: an experimental study.

The left mandibular premolars were extracted from five adult dogs. After twelve weeks, a box-shaped osteotomy of the alveolar bone was carried out and two 10 mm implants were placed 5 mm into the transport alveolar segment, leaving 5 mm exposed. The alveolar bone was vertically augmented 5 mm by screwing the implants. After distraction, the implants were left to integrate into the bone. Histological and radiographical evaluations showed the lifting of the transport segment and the development of new bone in the distraction area. Although integration of implants within both the transport segment and the regenerated bone was observed, two of the ten implants failed and partial bone resorption of the transport segment was noted.

Alveolar Process↗
PubMed1998

Segmental mandibular reconstruction by distraction osteogenesis under skin flaps.

In five adult dogs, molars were extracted and skin flaps from the neck prepared for delayed transplantation. Two weeks later, a 25-mm segment of the mandible was excised with surrounding periosteum and gingiva. The mandible was stabilized with a reconstruction plate and the intraoral defect repaired with a pedicled skin flap. A proximal transport segment was created and an external distraction device was applied. After one week, distraction of the transport segment was begun at a rate of 1 mm/day. After distraction was completed, the lengthening appliance was left in place for 12 weeks until the dogs were killed. Radiologic and histologic examination revealed new bone at the distraction site. The intraoral skin flap was pushed out of the defect as distraction progressed. Bony union of the transport segment to the distal stump was not achieved due to intervening soft tissue. These results suggest that it is feasible to bridge a mandibular defect that is covered with a skin flap, with distraction osteogenesis.

Animals↗
PubMed1998

A study of sports-related mandibular angle fracture: relation to the position of the third molars.

Mandibular angle fractures have been considered attributable to the presence of unerupted third molars. We examined the relationship between the incidence of sports-related mandibular angle fractures and the presence of a mandibular third molar with emphasis on the position of the third molar. The incidence of angle fracture was significantly higher in the sports-related injury group than in the group with fracture due to other causes (P < 0.05). The incidence of angle fracture in the athletes with higher impaction scores was significantly higher than that in the subjects with higher scores who did not have sports-related fractures (P < 0.05). The percentage of rugby athletes with third molars was significantly higher than that of those without third molars (P < 0.001), and a high proportion of young athletes (89.5%) was considered to belong to a potential high-risk group for angle fractures. Our findings suggest that mandibular angle fractures are influenced by the presence and characteristics of the third molar in sports-related injuries.

Accidents, Traffic↗
PubMed1998

Oral injury and mouthguard usage by athletes in Japan.

The use of mouthguards in contact sports effectively prevents oral injury and preserves oral structures. We investigated oral injuries and awareness concerning mouthguards among Japanese high school soccer and rugby players. Athletes were asked a series of questions concerning their history of oral injury while participating in sports, and their pattern of mouthguard use was determined. The data were evaluated statistically using chi-square analysis. The incidence of oral injuries was 32.3% for soccer athletes and 56.5% for rugby athletes, with 0.8% and 24.1% of the respective groups having mouthguards. There were significant differences between the soccer and rugby groups (P < 0.001). Although 81.8% of soccer athletes thought mouthguards were unnecessary, only 26.2% of rugby athletes shared this opinion and there was a significant difference between the soccer and rugby groups. Many soccer athletes had insufficient knowledge about mouthguards and were not concerned about preventing oral injury, although it was in fact a common problem in their sport. Athletes as well as coaches must be made aware of the high risk of oral injury when playing soccer, rugby, and other contact sports.

Adolescent↗
PubMed1997

Trifocal distraction osteogenesis for segmental mandibular defect: a technical innovation.

Distraction osteogenesis in the mandible is a promising method, not only for correction of mandibular hypoplasia such as hemifacial microsomia, but also for reconstruction of segmental bone defects in the mandible. The authors report a case in which a mandibular segmental defect, about 60 mm in length, was reconstructed by distraction osteogenesis. The patient was a 45-year-old man who had been treated for an oral floor cancer. After preoperative chemotherapy and irradiation therapy, the mandible had been resected from the second incisor on the right side to the first molar on the left side, and had been reconstructed with a titanium plate and a vascularized rectus-abdominis compound flap. However, an infection developed around the titanium plate and this plate had to be removed. Therefore, trifocal distraction using an original three-dimensional distractor was performed, at the rate of 1 mm per day (0.5 mm in the morning and 0.5 mm in the evening). During the distraction period, the skin flap was pushed out from the bone defect. Although small free bone transplants were needed for complete continuity, the segmental bone defect was almost filled by the regenerated bone with the lengthened gingiva. Radiographic observation showed successful new bone formation in the lengthened area.

Bone Plates↗
PubMed1997

Maxillary advancement by distraction osteogenesis using osseointegrated implants.

The purpose of this study was to establish a new technique for distraction osteogenesis in the maxilla, using an osseointegrated implant and intraoral device. After extraction of the premolar and molar teeth, four titanium implants were installed in the maxillary alveolar bone. Three months later, the distraction device was connected to the abutments, and osteotomy in the medial portion of maxilla between the implants was performed. Distraction was carried out at the rate of 1 mm per day to obtain a 10-mm elongation, Morphological, radiographic and histological examinations showed that successful maxillary advancement was achieved. New bone was primarily formed by intramembranous ossification and partial endochondral ossification. Titanium implants placed for anchorage of the distraction device remained stable during the course of maxillary advancement. This technique can provide significant advancement of the maxilla with better stability. The treatment system can be applied in any kind of maxillary deformities which need to be corrected surgically by classic osteotomy without bone grafting.

Alveolar Process↗
PubMed1997

Mouth guard for athletes during orthodontic treatment.

Mouth guards have been proven to greatly reduce the number and severity of traumatic dental injuries to participants in contact sports. However, there are some difficult problems in making mouth guards for athletes with orthodontic appliances on their teeth. We developed a method of making mouth guards by using a coating material for such athletes to prevent dental and oral sports injuries and to protect the orthodontic appliances. This mouth guard fits well and does not damage the appliances.

Athletic Injuries↗
PubMed1997

Three-dimensional model simulation in orthognathic surgery.

Surgery simulation with a three-dimensional model constructed with stereolithography from digital image data has proven to be useful in the maxillofacial area. The simulation and surgery of Le Fort I and bilateral sagittal split osteotomies were carried out in two patients. The models replicating the facial skeleton with precise internal anatomy facilitated design of the osteotomy and preparation of osteosynthesis. Each sectioned segment of the maxilla and mandible was accurately repositioned by transferring the positional relationships of multiple reference points on the model to the bone surface. Cephalograms taken at simulation and after surgery showed little difference in the positions of the landmarks.

Adult↗
PubMed1996

Mandibular lengthening by distraction osteogenesis using osseointegrated implants and an intraoral device: a preliminary report.

PURPOSE: This study investigated an approach to distraction osteogenesis of the mandible using osseointegrated implants and an intraoral device. MATERIALS AND METHODS: Five adult dogs were used for this experiment. After the extraction of the left mandibular premolar and molar teeth, two osseointegrated implants were placed. Abutment connection, attachment of the intraoral distraction device, and an osteotomy in the region between the implants were performed 3 months after implantation. The distraction was done at rate of 1 mm/day for 10 consecutive days to elongate the mandible 10 mm. The animals were killed 2, 3, and 4 weeks after the distraction was completed, and radiographic and histologic examinations were done. RESULTS: The longer the time after completion of distraction, the more uniform the new bone that was observed radiographically and histologically in the gap created by the distraction. The titanium implants remained stable during the course of mandibular lengthening. CONCLUSION: An intraoral device using osseointegrated dental implants can serve as a mechanism for distraction osteogenesis in the maxillofacial skeleton.

Animals↗
PubMed1993

Photochemical reactions in organized and semiorganized media.

The article describes organic photochemical reactions in heterogeneous fields. The first part of the article includes an introduction of miscellaneous electrostatic fields adsorbing photoactive species and the second part summarizes the types of photochemical reactions in their fields. Photochemical reactions carried out in various heterogeneous fields, inorganic as well as organic, were classified by their reaction type, that is, unimolecular reactions, bimolecular reactions, energy transfer reactions, and electron transfer reactions.

Chemical Phenomena↗
PubMed1993

Three-dimensional computed tomographic analysis for placement of maxillofacial implants after maxillectomy.

Three-dimensional computed tomography scanning was used to examine six patients who had undergone maxillectomy and who were being considered for endosseous dental implants in the residual maxillary bone. This technique allowed three-dimensional visualization of the precise structures of the deformed maxilla, which facilitated the operation procedure by indicating optimal sites for fixture installation.

Adult↗