Intermaxillary Distance Research Articles

Reconstruction of the severely resorbed mandible prior to vestibuloplasty or placement of endosseous implants: A 2 to 5 year follow-up

Ninety-two patients underwent augmentation of the severely resorbed mandible using corticocancellous bone grafts in the symphysis and a mixture of autogenous cancellous bone chips and hydroxylapatite particles in the posterior area. This study, extending from 2 to 5 years, shows that predictable and stable results were achieved. The average loss of height measured at 3 reference points was approximately 20%. Slight sensory disturbance was present in 19 patients (23%). Benefits derived from augmentation of the atrophic mandible include: improvement of facial form due to the renewed support of the collapsed circumoral muscles, a decrease in the intermaxillary distance, and restoration of mandibular bone bulk that will accommodate endosseous implants of maximum size.

Reconstruction of the edentulous mandible with a lower border graft and subperiosteal implant

A technique is described that is designed to augment the severely atrophied edentulous mandible by the use of a bone or bone-hydroxylapatite filled mesh tray attached to the inferior border. This method permits the intraoral environment to remain unchanged, causing neither a decrease of intermaxillary distance nor placement of graft material on the ridge crest, which would offer a less stable and predictable base for acceptance of a subperiosteal implant. Lower facial length becomes augmented, inferior labial posture is improved, redundant cervical tissue is eliminated, and masticatory function is enhanced.

顎間距離増大後の咬筋の順応性に関する電子顕微鏡的研究

It is generally acknowledged that masseter muscles take a great part in occlusal stability after bite opening, a means used in orthodontic treatment. Various studies of adaptation of masseter muscles have been done from different standpoints. Histological investigations however have been limited in number. An experimental investigation of adaptation of masseter muscles therefore has been done from the standpoint of finestructure. The experiment on increasing intermaxillary distance was conducted with use of anterior bite plate (Experiment I) covering only the maxillary anterior segment and complete bite plate (Experiment II) covering the anterior and posterior segments in 21 adult dogs (mongrels) for one, three, and six months. The histological and electron-microscopic findings were as follows : 1. In both Experiments I and II, muscle fibers of the masseter muscles were thinner than the normal ones in width after one month. Arrangement of the muscle fibers zigzagged. Electron-microscopically, ruptures and disappearances were observed in myofibrils in part of Z-line and I-band. Most glycogen particles disappeared. The changes in myofibrils seen in Experiment I were not observed in Experiment II. Many instances of swelling and vacuolation of mitochondria were observed. The degree of vacuolation however was slight. 2. In both Experiments I and II in the third month, most muscle fibers were thicker than those in the first month although some were still thin in part. Electron-microscopically, more significant ruptures and disappearance were observed in Z-line and I-band of myofibrils. Glycogen particles decreased as in Experiment I in the first month. 3. In both Experiments I and II in the sixth month, the width of the muscle fibers on the whole was restored to that of the normal ones. Electron-microscopically, myofibrils and mitochondria tended to be restored to near normal. Glycogen particles showed a trend toward restoration to normal in Experiment I but remained disappeared in Experiment II. 4. In both Experiments I and II, the length of sarcomere increased with time. The length of I-band in particular showed a marked increase. Based on the foregoing finding, the finestructure indicative of complete adaptation was not observed. The experiment however suggested at least a need for a longer retension of bite plate in performing the orthodontic treatment of increasing intermaxillary distance to patients who have passed the growth period.

Consequences of Shortening the Intermaxillary Distance

Consequences of Shortening the Intermaxillary Distance