P. F. Nocini

Adult human bone cells from jaw bones cultured on plasma-sprayed or polished surfaces of titanium or hydroxylapatite discs

Adult human bone cells isolated from jaw bone biopsies were cultured either on Thermanox® coverslips or on polished or plasma-sprayed surfaces of titanium or hydroxylapatite and the levels of their various metabolic functions were compared after 2 and 5 days of staying in culture. Thus, jaw bone cells grown on hydroxylapatite proliferated very little, while expressing discrete levels of alkaline phosphatase activity and of osteocalcin secretion into the growth medium. On the other hand, bone cells seeded onto titanium surfaces proliferated much more intensely than those on Thermanox®, besides expressing alkaline phosphatase (very intensely after 5 days) and secreting osteocalcin. Thus, both kinds of titanium surfaces greatly enlarged the size of both populations of pre-osteoblastic precursors and of pre-osteoblasts in vitro, but plasma-sprayed titanium surfaces elicited, between day 2 and 5 in culture, greater increases in bone cell numbers markedly enhancing their proliferative and alkaline phosphatase activities, along with their osteocalcin secretion into the growth medium, and thus favouring the expression of the mature osteoblastic phenotype. These preliminary findings show that studies correlating the physical surface features of various biomaterials with the corresponding expression of specific differentiation markers by the bone cells cultured on these same surfaces can provide information relevant to the clinical application of biomaterials.

Functional rehabilitation of the atrophic mandible and maxilla with fibula flaps and implant-supported prosthesis.

Historically, nonvascularized bone grafts have been the standard treatment for severe mandibular and maxillary atrophy, followed by immediate or delayed implant placement. Extreme atrophy is an unfavorable biological and mechanical location for nonvascularized autologous bone transplants. The authors present the results of a multidisciplinary treatment protocol for rehabilitation of extreme mandibular and maxillary atrophy by use of the vascularized fibular flap. This protocol includes bone augmentation, implant surgery, soft-tissue management, and prosthetic restoration. Since 1993, 18 patients with a mean age of 47.5 years presented with extreme mandibular and/or maxillary atrophy and underwent alveolar crest augmentation with vascularized fibular flaps. Bone healing was achieved in 17 of the 18 patients. Seventy-three osteointegrated implants were inserted in 12 of 17 fibular flaps. Altogether, 62 implants were loaded and 11 dental prostheses were made. Average follow-up of the loaded implants was 41 months. The success rate of loaded implants was 100 percent. The authors strongly recommend the use of the fibular bone flap when dealing with extreme atrophy of the mandible and maxilla and suggest the protocol outlined in this review.

The use of computer-guided flapless dental implant surgery (NobelGuide) and immediate function to support a fixed full-arch prosthesis in fresh-frozen homologous patients with bone grafts.

Abstract The behavior of fresh-frozen homologous bone (FFB) when used in combination with computer-guided implant surgery has not been investigated yet, and there is a lack of clinical evidence in the literature. The purpose of this retrospective study is to evaluate the implant survival and related fixed full-arch prostheses at the 1- to 5-year follow-up when performed with immediate function using a flapless surgical procedure and computer-aided technology (NobelGuide; Nobel Biocare AB, Goteborg, Sweden) in patients previously treated with FFB grafts. Furthermore, the related values of torque and complications observed were analyzed and discussed. Clinical charts of patients with edentulous arches treated with FFB grafts and NobelGuide system with at least 1 year follow-up were reviewed retrospectively. A total of 65 patients met the criteria of inclusion, receiving a total of 342 implants and 77 full-arch prostheses, with a mean follow-up of 32.87 months (range, 1–5 years). Survival of implants and prostheses was high, reaching 96.5% and 95%, respectively. Factors significantly related to failure of the implants were smoking, position of the implant as last distal abutment, and fracture of basal maxillary bone. Prostheses survival was influenced by bruxism, failure of multiple implants, and torque level of implant equal to 0 at implant insertion. All implants and prostheses failures occurred in the first year. A higher torque level at implant insertion did not correspond to a lower risk of implant failure. Within the limitations of our retrospective study, this treatment modality was predictable with high survival rates and high insertion torque. However, a few implant and prosthetic failures were found, together with several complications.

Grafting of large mandibular advancement with a collagen-coated bovine bone (Bio-Oss Collagen) in orthognathic surgery.

Abstract Current principles for correction of dentoskeletal deformities ask to satisfy different treatment goals, making large mandibular advancements a common practice in orthognathic surgery. A main consequence of significant mandibular movements is the potential for unfavorable bone healing of osteotomy sites after traditional sagittal split procedures. This drawback, which mainly occurs at the level of inferior mandibular borders, can affect the stability and support of overlying soft tissues. Whereas the role of bone grafting for upper jaw defects after Le Fort I osteotomy is well addressed in the Literature, until now, just a few articles discussed the potential for grafting of mandibular osteotomy sites. The aim of this study is to evaluate the healing of mandibular bone defects because of large advancement (>8 mm) after sagittal spit procedures. In 20 patients treated for correction of class II dentoskeletal deformities, mandibular osteotomies defects have been grafted with a collagen-coated bovine bone substitute. Clinical, radiological, and histological evaluation of grafted sites showed a good healing of grafted area both in terms of recontouring of inferior mandibular borders and in terms of quality of newly formed bone. This confirms how this procedure could help to avoid the drawbacks related to significant mandibular advancement.

Severe maxillary atrophy treatment with Le Fort I, allografts, and implant-supported prosthetic rehabilitation.

PurposeRecently, several authors have described that autologous and fresh-frozen bones are effective materials to correct jaw bone defects before endosseous implant positioning. The aim of this study was to report a multistep oral rehabilitation of severe atrophic maxilla by means of Le Fort I osteotomy for maxillary downward and forward repositioning, allografts, implant insertion, and prosthetic loading. MethodsPatients with severe maxillary atrophy underwent Le Fort I osteotomy associated to fresh-frozen interpositional bone allografts. At 7 months after reconstructive procedure, 2 biopsies for each patient have been taken, and in the same surgical procedure, endosseous implants were placed. Five months afterward, abutments were connected for the final prosthodontic restauration. Each patient was evaluated at 1-year follow-up after prosthetic loading. ResultsAt 1-year follow-up after functional prosthetic loading, no infection of the allografts or implant failure has been reported. Clinical and radiologic follow-up showed no sign of bone resorption in all the osteotomic sites and in the grafted areas. Histological analysis showed evidence of allograft osteointegration and healing. ConclusionsMultistep oral rehabilitation of severe atrophic maxilla with Le Fort and interpositional bone allografts represents a reliable surgical technique. According to this clinical, radiologic, and histologic reports, interpositional fresh-frozen bone allograft seems to be a valuable material for grafting jaw as it is cheaper than other materials and is safe, and it avoids donor site, decreasing the morbidity of the treatment.

Jaw reconstruction by free fibular transfer: emphasis on osseointegrated implants, TMJ and maxilla reconstruction

Abstract From December 1989 to September 1997 21 patients were treated for mandible reconstruction and 10 for maxilla reconstruction using the fibular flap. The age of patients ranged from 25 to 64, the length of the bone grafts from 7 to 25 cm. In 16 cases osseointegrated implants were used for denture rehabilitation; in 3 cases the reconstruction involved the TM joint. In the maxilla the fibula flap was used to reconstruct extreme atrophy of the alveolar process in 4 cases; to reconstruct a previous hemimaxillectomy in 3 cases and post-traumatic bone loss in 3 cases. Bone fixation was obtained by K-wires in 4 cases and miniplates in the remaining 27. The TM joint was reconstructed with an osteochondral graft from the second metatarsal head or an ear cartilage graft sutured on top of the fibula. In one case the homologous condyle conserved after tumor resection was used. The flaps were bone only (12 cases), bone plus muscle (15 cases) and osteocutaneous (4 cases). Average follow-up was 3–4 years. Twenty-eight flaps had no complications, with good functional and morphological results. One flap was lost because of infection, 1 flap was lost after 3 years due to a recurrence of malignancy; 1 flap had a segmental bone necrosis because partial devascularization occurred after hemostasis to stem major bleeding. Seventy-nine fixtures were placed, 47 into the new mandibles and 32 into the reconstructed maxillae. All implants have been well osseointegrated, except 1 removed at the time of surgery because of poor primary stability. Sixteen patients have had an implant-supported prosthesis. In our experience fibula is one of the most versatile flaps for jaw reconstruction, especially when osseointegration is planned or the TMJ and the maxilla need to be reconstructed.

Simultaneous Le Fort I osteotomy and zygomatic implants placement with delayed prosthetic rehabilitation.

AbstractPatients affected by severe maxillary atrophy and skeletal malocclusion have been widely treated by simultaneous orthognathic surgical procedures, interpositional bone insertion and immediate or delayed implant placement.Although several authors have described that the “quad” technique using 4 zygomatic fixtures as an effective way to fully rehabilitate the severe atrophic maxilla, there are still no experiences relative to the use of zygomatic fixtures associated to maxillary osteotomies in case of large skeletal discrepancy.The aim of this study is to report a 1-step surgical rehabilitation of severe atrophic maxilla by means of Le Fort I osteotomy for maxillary forward repositioning and simultaneous insertion of 4 zygomatic implants with immediate prosthetic loading.

Relationship Between Primary Stability and Crestal Bone Loss of Implants Placed with High Insertion Torque: A 3-Year Prospective Study.

PURPOSE Concerns have been expressed about the possibility of high insertion torque (IT) causing necrosis, impaired osseointegration, and crestal bone loss over time. The present study investigated the relationship between primary stability and implant success, including early and late maintenance of crestal bone levels. MATERIALS AND METHODS Implants were placed in patients at three study centers. Every effort was made to achieve the highest possible primary stability, which was measured with IT and implant stability quotient (ISQ). The IT and ISQ at insertion and reopening (3 to 4 months), as well as bone levels at several points in time, were recorded. The correlations between IT, ISQ, and immediate and 3-year crestal bone loss were investigated through linear regression analyses. RESULTS Average IT was 76.1 ± 20.8 Ncm, while the average ISQ score was 80.4 ± 8.4. The implant success rate at 36 months was 98.6%. The crestal bone loss around most implants (41.0%) ranged from 0.05 to 0.5 mm. None of the osseointegrated implants had crestal bone loss greater than 2.5 mm. The linear regression analysis showed no correlation among early or 3-year crestal bone loss and IT, ISQ at surgery, and ISQ at reopening. CONCLUSION The implants studied avoided any negative effects deriving from the high IT values (≥ 50 Ncm) applied during 3 years of follow-up.