Sten Isaksson

Osseous response to implanted natural bone mineral and synthetic hydroxylapatite ceramic in the repair of experimental skull bone defects

The purpose of this study was to assess and compare the osseous responses to implanted particles of resorbable anorganic xenograft bone mineral and non-resorbable dense synthetic hydroxylapatite of two different granule sizes. Four trephine calvarial defects were produced in each of 13 adult rabbits. The experimental materials were subsequently implanted in three defects, leaving the fourth defect for control purposes. Six animals were killed 4 weeks after surgery and seven at 14 weeks. The tissue responses were assessed by contact radiography, light microscopy, and histometry. The biocompatibility of the implants was confirmed. All defects healed uneventfully, although the resorbable hydroxylapatite seemed to promote initial bone regeneration. The importance to orthognathic surgery of early and effective healing of bone gaps, as well as of the advantage of implant resorbability to bone remodeling, are discussed.

Oral implants in combination with bone grafts: A 3-year retrospective multicenter study using the Brånemark implant system

Abstract A retrospective, multicenter, Scandinavian study of bone grafting of alveolar processes of severely atrophic jaws in combination with implant insertion was conducted with 150 patients. Five different grafting techniques were assessed: local or full onlay; inlay; combination of onlay/inlay grafts; and LeFort I osteotomies. The majority of the patients were treated using a one-stage approach (n=125) and all had autogenous bone grafts. A total of 781 Branemark implants were inserted, of which 624 were placed in bone grafts and alveolar bone. Twentyfive patients (17%) dropped out during the follow-up period of three years. Within the remaining patients, 77% of the inserted implants (n=516) were still in function at the end of the follow-up period. A further ten implants were kept mucosacovered, resulting in an overall implant survival rate of around 80%. Onlays, inlays and LeFort I osteotomies showed almost the same success rates (76–84%), whereas the onlay/inlay technique gave rise to less favourable results (60%). Most of the observed losses (n=131) took place during healing and the first year of loading. More implants were lost when they were inserted simultaneously with the grafting (23%) than when they were placed in a second stage (10%). The latter technique was used mainly in combination with local onlay grafting (16/25). The failure percentage for implants inserted in non-grafted bone (11%) was lower than for those inserted in bone grafts and alveolar bone (25%). The surviving implants of treated and followed patients served, in 88% of the cases (n=110), to support fixed bridges or overdentures, albeit, in some instances (n=23), after additional implant placement. In only 15 patients was it necessary to fall back on conventional removable prostheses or fixed partial bridges.

Maxillary alveolar ridge augmentation with onlay bone-grafts and immediate endosseous implants

Management of the atrophic maxilla can be a taxing surgical problems. One treatment alternative is to use autogenous bone transplants and immediate titanium fixture implantation. Despite the extensive literature on routine implant treatment of the edentulous jaws, only very few reports have dealt with the outcome of bone graft reconstructive surgery as part of the dental implant restoration. This study presents the treatment and healing results of 8 consecutive patients, who, over a period of 2 years and 8 months, were treated using onlay iliac bone grafts to atrophic maxillary alveolar ridges with immediate implant insertion. The patients were followed for 32-64 months. 83% of the fixtures (n = 46) were well-integrated. Two fixtures in each of 2 patients were lost due to traumatic bone-graft fractures. Palpatory bone-graft volume and prosthetic function were, with the exception of 1 patient, good. Radiological examination demonstrated preservation of the major part of the vertical dimension of the grafted bone. Patients assessment was of good aesthetics and intraoral function; 2 patients had minor phonetic problems. In conclusion, similar success to routine maxillary implant treatment can be achieved in the event of extreme maxillary bone deficiency, by bone grafting and immediate fixture insertion.

Factors in implant integration failure after bone grafting: An osteometric and endocrinologic matched analysis

In a retrospective analysis of 49 patients who received bone graft augmentation to the maxillary sinuses in conjunction with implant insertion, 11 patients had a significantly reduced success rate. The aim of the present study was to determine whether bone quality, as assessed by osteometry and selected haematologic and urinary tests, influences the integration of implants, and whether such data can be prognostically useful. Relative bone mass density (BMD%) differed significantly among these patients as compared to age- and sex-matched control patients receiving the same reconstructive treatment (P=0.01). Other parameters tested did not demonstrate any significant differences. In addition to local complications, general disorders, such as osteoporosis, must be considered in cases of excessive implant loss.

Skeletal stability after mandibular advancement: A comparison of two rigid internal fixation techniques

OBJECTIVE To compare two different methods of rigid fixation for any difference in postoperative stability after mandibular advancement. MATERIAL AND METHODS Thirty-eight patients with Class II malocclusion treated by bilateral sagittal split osteotomy (BSSO) and mandibular advancement were selected for this retrospective study. Group A (n = 16) had noncompressive bicortical screws inserted in the gonial area through a transcutaneous approach and Group B (n = 22) had the bone segments fixed with unicortical screws and miniplates on the lateral surface of the mandibular body. Cephalograms were taken preoperatively, 2 days postoperatively, and 6 months after the operation, and a computer program was used to superimpose the three cephalograms and register the advancement and postoperative instability. RESULTS There was a minimal difference in advancement of the mandible in the two groups. Statistical analysis showed no significant difference in postsurgical stability. However, positive correlation between the amount of advancement and the amount of postsurgical instability was demonstrated using a linear multiple regression test (P = .0002). CONCLUSION This study indicates that the two different methods of internal rigid fixation of the segments after surgical advancement of the mandible give equal stability postoperatively and their use is a matter of surgical choice.

Early results from reconstruction of severely atrophic (class VI) maxillas by immediate endosseous implants in conjunction with bone grafting and Le Fort I osteotomy

This report presents our experience with 12 consecutive patients treated by the method of SAILER19, comprising bone grafting to the floor of the nose and the maxillary sinus after a Le Fort I inferior repositioning of the maxilla followed by immediate implantation of endosseous implants. The corticocancellous grafts were harvested from the iliac crest. Fifty-nine implants were inserted in the bone grafts and eight in the adjacent nongrafted bone. Fourteen implants (21%) had to be removed because of nonintegration, of which 10 had been placed in two patients. The follow-up ranged from 11 to 24 months. No implants have been lost after loading. Six patients received fixed prostheses, and four overdentures. The importance of complete preoperative positional stability of the bone grafts and implants is emphasized.

Sensibility following sagittal split osteotomy in the mandible: a prospective clinical study.

&NA; Bilateral sagittal split osteotomy may be associated with postoperative sensory deficiency in the area innervated by the inferior alveolar nerve. The aim of this study was to assess the neurosensory response of the inferior alveolar nerve after such surgery. Fifty consecutive patients receiving mandibular setback or advancement were investigated. Four different neurosensory tests were used: light touch, pin prick, static two‐point discrimination, and vibration thresholds. These tests were performed preoperatively, 2 days, as well as 3 months and 12 months postoperatively. The methodologic error was found negligible. The pin prick and light touch tests as well as vibratory thresholds often disclosed a short period of decreased local sensibility, whereas static two‐point discrimination displayed a slightly more extended postoperative sensory reduction. The patients did not experience any practical problems or essential drawbacks postoperatively. The only variable significantly associated with neurosensory disturbance was age. In conclusion, bilateral sagittal split osteotomy, when properly performed, must be considered a safe and reliable surgical technique, even from a neurosensory point of view. (Plast. Reconstr. Surg. 102: 325, 1998.)

Stability of Le Fort I osteotomy with advancement: A comparison of single maxillary surgery and a two-jaw procedure

PURPOSE This study compared single maxillary surgery and a two-jaw procedure in patients who underwent one-piece Le Fort I advancement without bone grafting. PATIENTS AND METHODS Fifty-three patients had Le Fort I osteotomy performed using a standard technique. Twenty-two patients had maxillary surgery alone, and 31 patients additionally had a bilateral sagittal split ramus osteotomy performed. Both rigid and nonrigid fixation were used. The postoperative movement of the maxilla was investigated, comparing cephalograms taken preoperatively, 2 to 3 days postoperatively, and at least 6 months postoperatively. A computer program was used to superimpose the three radiographs. RESULTS No difference in postoperative stability was found when the two surgical procedures were compared, and no correlation between magnitude of advancement and degree of relapse could be identified (P > .05). Nonrigid fixation in patients receiving only maxillary surgery resulted in greater postoperative forward movement of the maxilla (P = .022). CONCLUSION This study indicates that postoperative stability of the maxilla in a two-jaw procedure is equivalent to that of single maxillary surgery. Nonrigid fixation in single maxillary surgery reduces the need for postoperative orthodontics.

Sinus inlay bone augmentation: Comparison of implant positioning after one- or two-staged procedures

PURPOSE This study was undertaken to compare implant angulation and position after one- or two-stage sinus inlay bone augmentation. PATIENTS AND METHODS Twenty patients were retrospectively selected; group 1 (n = 10) was operated on with a one-stage procedure, and group 2 (n = 10) with a two-stage operation. Casts processed for the final permanent or temporary bridgework were collected and photographed from an oblique anterior view paralleling the alveolar crest on the right and left sides, as well as from an occlusal view. The angle between impression pins inserted in the abutments relative to the true vertical was recorded. In the occlusal view, the midpoints of the abutments were related to an individual computerized superimposed parabola. RESULTS The implants inserted during the one-stage procedure were generally placed more palatally (Wilcoxon rank sum test, P = .0101) and angled more palatally (P = .0009) compared with those placed with the two-stage operation. CONCLUSION This study showed that the two methods of treating patients by sinus inlay bone augmentation differed significantly with regard to placement and angulation of the implants. A two-stage procedure seems to offer the surgeon more optimal conditions for positioning the implants.

Bone Regeneration Using a Hollow Hydroxyapatite Space-Maintaining Device for Maxillary Sinus Floor Augmentation - A Clinical Pilot Study

BACKGROUND The mere lifting of the maxillary sinus membrane by implants protruding into the sinus cavity allows the establishment of a void space for blood clot and new bone formation. PURPOSE To evaluate bone formation by using a spherical, hollow, and perforated hydroxyapatite space-maintaining device (HSMD) in a two-stage sinus lift procedure where residual alveolar bone height was ≤2 mm. MATERIAL AND METHODS Spherical, hollow, and perforated HSMDs with a diameter of 12 mm were manufactured for this pilot study. Three patients with a residual bone height of 1-2 mm, as verified clinically and radiographically, and in need of a sinus augmentation procedure prior to implant installation were selected for the study. The HSMD and bone formation was evaluated by cone beam computerized tomography (CBCT) 6 months after augmentation procedure. Implants were installed 6 to 9 months after augmentation. The implant sites were prepared by a trephine drill to obtain a specimen of HSMD and bone for histological evaluation. After implant installation, the condition of the sinus membrane adjacent to the HSMD was evaluated endoscopically. After an additional 8 weeks, fixed partial prostheses were fabricated. RESULTS Bone formation verified by CBCT was found around and inside the device in all three patients after 6 months. Despite the fact that residual bone before augmentation was ≤2 mm, 12-mm-long implants with diameter of 4.8 mm could be inserted with preservation of an intact and healthy sinus membrane verified endoscopically. Bone formation inside HSMDs was noted histologically in two out of three HSMDs. Implants were stable and without any marginal bone loss after 1 year of prosthetic loading. CONCLUSION A spherical, hollow, and perforated HSMD used in sinus lift procedures can produce a void space for blood clot and new bone formation and subsequent implant installation.