Yoshihiro Sawaki

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.

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.

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.

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.

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.

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.

Disseminated intravascular coagulation presenting as hemorrhage after tooth extraction

odontomas. In the latter author’s case, which had been radiographically followed-up for 5 years, the odontomasis developed directly from the basal cells of the oral mucosa, and a part of the soft odontoma developed into a hard odontoma. In our case, soft radiography showed fine radiopaque material scattered in the cystic cavities within the masses. This finding suggests that if the lesions were not removed, some would have calcified into mature, solid, hard, masses. The cause of odontoma is still unknown, although local trauma or infection have been implicated.z Furthermore, multiple odontomas have been suggested to be related to systemic syndromes such as cleidocranial dysostosis or Gardner’s syndrome.3 However, no systemic symptoms were evident in this case. Odontomas have been categorized as neoplastic lesions derived from odontogenic cells; however, some investigators4,5 regard them as hamartomas or malformations rather than neoplasms. Therefore, enucleation is curative, and recurrence is not a problem. In this case, the tumors may have arisen from bilateral supernumerary tooth germs, because all permanent teeth except the lower first premolars, which had been extracted for convenience, had erupted normally. They seemed to have arisen as a regional abnormality in the mandible, neither localized to a single tooth germ nor, like Bader’s case,l to be associated with general multiple malformations. Therefore, they should be placed into an intermediate status between the two.

Modified osteosynthesis for condylar neck fractures in atrophic mandibles

A fixation system combining both plate and lag screw osteosynthesis for condylar neck fractures of the mandible is described. The currently available device is adapted in that the lag screw is inserted in the lateral cortical bone of the condylar segment instead of the cancellous bone alone.

Cultured oral epithelium as an effective biological dressing using for palatal wounds after palatoplasty

Abstract Cultured allografts derived from mucosal tissue provide a potent stimulus to wound healing in a wide variety of wounds. In the field of oral surgery, mucoperiosteal defect of the hard palate after palatoplasty causes 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 a strangers cultured cells. We grafted cultured oral epithelium in the hope of improving growth of maxilla. 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 pushback operation. Oral epithelial cells in 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. In all patients, the grafted areas underwent re-epithelialization after about 1 week and did not exhibit any side effects of graft rejection. Grafted areas healed completely after 2–3 weeks in all cases. Cultured epithelial allografts serve as a temporary biological dressing, and accelerates 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.

Two Cases of Distraction Osteogenesis in Lengthening Hypoplastic Mandible of Hemifacial Microsomia. Evaluation 3 Years after Distraction.

Mandibular lengthening by distraction osteogenesis was performed on two females (6 and 9 years old) with hemifacial microsomia to correct facial asymmetry. The follow up was done by cephalometric analysis for 3 years.The results were as follows:1) Three years after distraction, the morphological symmetry corrected by distraction had almost been maintained.2) However, a slight amount of deviation on affected side was noticed at the Menton.3) In lateral chepharogram, ∠SN-Pog did not changed for 3 years after distraction.4) Downward growth of the maxilla on the affected side was not observed. Open bite at lengthened side seemed to be closed by eruption of the permanent molars.