Endosseous implants for prosthetic rehabilitation in bone grafted alveolar clefts

The authors report their experience in the surgical and prosthetic rehabilitation of three patients affected by sequelae of cleft lip and palate, with residual alveolar cleft and absence of maxillary anterior teeth. The patients were treated by means of late secondary bone grafting of the alveolar cleft, followed by the insertion of endosseous titanium plasma-sprayed implants (IMZ). After a further healing period (6-12 months) fixed dental prostheses were constructed. Preliminary results from this series have shown how dental prostheses supported by endosseous implants in grafted alveolar clefts are a very reliable possibility in dental rehabilitation of this malformation.     

Alveolar bone growth in response to endosteal implants in two patients with ectodermal dysplasia

Osteitis condensans of the clavicle is a rare condition characterized by pain in the shoulder and often limitation of motion of the shoulder. The medical history and results of the physical examination, laboratory data, and radiographic studies (including computed tomography and magnetic resonance imaging), often establish the diagnosis. Patients who have slight or no pain usually require no treatment. Varying results have been reported for many different methods of treatment, including surgical excision, chemotherapy, antibiotics, nonsteroidal anti-inflammatory medications, radiation, local corticosteroid injection, and physical therapy. A typical case report and the differential diagnosis for condensing osteitis of the clavicle are presented.     

Available bone is the foremost criterion in the insertion of endosteal implants

The foremost criterion in the insertion of endosteal implants is bone availability. Implant dentists should consider first the amount of available bone of the edentulous ridge where the endosteal implant will be inserted. A common error and cause of many implant failures is the dentist's use of an implant modality which is not indicated for the density and morphology of the available bone in the edentulous ridge. Implant modality/system is not the primary criterion in the insertion of endosteal implants. Before the dentist inserts an endosteal implant, he should gauge or measure the amount of bone where the implant is intended to be placed. It should be measured in width, height, length, trajectory, and implant-crown ratio. After recording the measurements of the available bone, these should be placed in different categories to serve as guides in implant selection. If there is not enough bone for the endosteal implant, bone modification should be performed. This can be done either by osteoplasty or ridge augmentation with the use of bone grafting materials. Aside from the amount of available bone in the edentulous ridge, another very, very important thing that should be considered is the quality or its density. Any biocompatible implant demonstrates some osseointegrated surfaces depending upon the bone type into which it is placed and the loads placed upon it. Implant body must exhibit a macrogeometry suitable for acceptable levels of force transfer to the surrounding tissues as well as for implantation into a bony site of a particular anatomic size.     

Morphology of the bone that supports endosteal dental implants. Transmission electron microscopic and high voltage electron microscopic observations

The morphologic features of the bone-dental implant interface were investigated using an in vivo dog model. The undecalcified bone and associated support tissues were serially sectioned and examined with both conventional and high voltage transmission electron microscopy. A varied morphologic appearance of the tissues supporting clinically and radiographically appearing integrated implants was observed. Osteoblasts were observed at the implant interface, and osteocytes were routinely seen encased within lacunae extremely close to the implant surface. Often these osteocytes extended cellular projections to the implant surface. The variable tissue types observed were suggestive of healthy lamellar and appositional type mineralization patterns adjacent to the implants.     

Dental prosthetic reconstruction of osseointegrated implants placed in irradiated bone

Deficiency of the sixth component of human complement (C6) has been reported in a number of families from the western Cape, South Africa. Meningococcal disease is endemic in the Cape and almost all pedigrees of total C6 deficiency (C6Q0) have been ascertained because of recurrent disease. We have sequenced the expressed exons of the C6 gene from selected cases and have found three molecular defects leading to total deficiency: 879delG, which is the common defect in the Cape and hitherto unreported, and 1195delC and 1936delG, which have been previously reported in African-Americans. We also show that the 879delG and 1195delC defects are associated with characteristic C6/C7 region DNA marker haplotypes, although small variations were observed. The 1936delG defect was observed only once in the Cape, but its associated haplotype could be deduced. The data from the haplotypes indicate that these three molecular defects account for the defects in all the 38 unrelated C6Q0 individuals we have studied from the Cape. We have also observed the 879delG defect in two Dutch C6-deficient kindreds, but the 879delG defect in the Cape probably did not come from The Netherlands.     

Reconstruction of residual alveolar cleft defects with one-stage mandibular bone grafts and osseointegrated implants

PURPOSE: This study evaluates a treatment regimen for reconstruction of residual maxillary alveolar cleft defects consisting of mandibular bone grafting and immediate implant installation. PATIENTS AND METHODS: Sixteen cleft patients (five female and 11 male) had residual cleft defects of the alveolar ridge reconstructed with bone grafts from the mandibular symphyseal region. The bone graft was pretapped at the donor site before fixation in the residual ridge with Br?nemark implants. Twenty implants were installed according to this concept. The period of observation ranged from 36 to 69 months, with a mean of 48 months after implant installation. RESULTS: Five patients developed wound dehiscenses that resulted in total or partial bone graft sequestration. Two implants were lost, one due to sequestration and the other due to mobility at the abutment procedure; 18 implants were still well functioning at the end of the observation period. However, all patients showed significant periimplant bone resorption after this one-stage treatment. CONCLUSION: Because of the observed complication rate, the one-stage procedure may not be optimal for reconstructing residual cleft defects.     

Primary insertion of osseointegrated dental implants into fibula osteoseptocutaneous free flap for mandible reconstruction

Twelve patients with segmental mandibular defects were reconstructed with fibula osteoseptocutaneous flaps and simultaneous placement of osseointegrated implants. Decision to perform this procedure was based on the facts that all patients had benign diseases, did not require postoperative radiotherapy, were in good general and oral conditions, and were psychologically motivated. A total of 34 fixtures was inserted in the first stage. Eight patients underwent second stage surgery, which consisted of connection of the implant abutments to the fixtures and the use of palatal mucosal grafts around the implants. Final dental prostheses were fixed 1 month later in seven patients, at this time. All flaps survived after surgery, and no implant failure was observed after a mean follow-up period of 25 months. Only one fixture was not used during the subsequent stage and was left as a sleeper. Fixed dental prostheses were used in five patients and removable overlay prostheses in the other two. Chewing function was recovered between 4 and 6 weeks after the start using the definitive dental prosthesis. In contrast to previous results, we conclude that excellent results can be achieved when this combined procedure is used in carefully selected patients. In addition, it is confirmed that the fibula osteoseptocutaneous flap is a versatile, reliable composite tissue that facilitates primary placement of osseointegrated dental implants during mandible reconstruction, thus allowing full oral rehabilitation in a shorter period of time.     

Guided bone regeneration around dental implants in the atrophic alveolar ridge using a bioresorbable barrier. An experimental study in the monkey

The aim of this study was to evaluate guided bone regeneration (GBR) around dental implants placed in atrophic alveolar ridges using an experimental, nonporous bioresorbable barrier. In 8 Rhesus monkeys, the maxillary canines and lateral incisors were extracted bilaterally and the remaining alveoli were reduced to create atrophic ridges. After a healing period of 3 months, soft tissue expansion was performed using a subperiosteal tissue expander. After 1 month of tissue expansion, and IMZ implant was placed in the atrophic ridge on each side in such a way that its coronal 4 mm to 5 mm remained circumferentially exposed above the bone level. The test implants were covered with a bioresorbable barrier made of poly (D,L-lactid-co-trimethylencarbonate) in a 70/30 ratio, whereas the control implants were covered with a nonresorbable expanded polytetrafluoroethylene (e-PTFE) barrier. The e-PTFE barriers were stabilized with titanium minipins while the bioresorbable barriers were analogously fixed using bioresorbable minipins made of poly (L-lactid-co-D,L-lactid) 70/30. Clinical healing progressed uneventfully in both groups and no soft tissue dehiscences occurred. Histometric and histomorphometric analyses were performed 5 months post surgery. Both test and control implants exhibited direct bone-to-implant contact to variable extents. The mean direct mineralized bone-to-implant contact length fraction was 32% of the total implant length in the test sites and 58% in the control sites. Control sites exhibited significantly greater bone fill compared to the experimental sites (P < 0.001). Histologic observations of test specimens demonstrated a moderate inflammatory reaction related to the degradation and resorption products of the barrier. In conclusion, the nonresorbable e-PTFE GBR barrier was found to be superior to the bioresorbable barriers tested in the present investigation.     

Integration of hamstring tendon graft with bone in reconstruction of the anterior cruciate ligament

Anterior cruciate ligament (ACL) reconstruction using four-strand hamstring graft with round-headed, cannulated, interference (RCI) screw fixation requires osteointegration of the tendon graft. This report describes the histology at the bone-tendon junction of two specimens retrieved from patients undergoing revision surgery after traumatic mid-substance ACL graft rupture at 6 and 10 weeks after initial reconstruction. Revision was performed at 12 and 15 weeks. Integration of the graft was evident by observation of collagen fiber continuity between bone and tendon. This histology plus the low incidence of early graft failure suggest that free tendon autograft attached to bone by RCI screw allows adequate osteointegration between 6 and 15 weeks after surgery.     

Immediate insertion of two types of implants into vascularized bone grafts used for mandibular reconstruction in miniature pigs

Genomic DNAs of metallothionein I and II in Caenorhabditis elegans (CeMT-I and CeMT-II) were isolated by YAC library/polytene filter hybridization followed by subcloning of corresponding cosmid clones. Both genes are mapped at chromosome V. Although the similarities of 5'-flanking regions and coding regions have shown only 55-58%, the introns are split at the same position in both genes, indicating that these two genes are originally from the same gene. While several metal responsive elements are conserved among eukaryotes, only one metal responsive element was found in the promoter region in CeMT-II and not in CeMT-I. Indeed, neither of 5'-flanking regions of CeMT-I nor CeMT-II connected to chloramphenicol acetyltransferase reporter gene is responsive to heavy metals in mammalian culture cells by transient transfection analysis. These results would suggest that the metal regulatory factors in C. elegans might be different from those conserved in invertebrates and vertebrates, although the MTs in C. elegans revealed the similarities to mammalian MTs in several points.     

Anterior cruciate ligament reconstruction with autogenous patellar tendon graft in patients with articular cartilage damage

To test if anterior cruciate ligament reconstruction with autogenous patellar tendon can alleviate symptoms and functional limitations and increase activity levels in patients with advanced articular cartilage damage, we looked at 53 patients with arthroscopically documented cartilage damage. In this group, a mean of 7.5 years had elapsed between the original injury and the reconstruction, and 90 prior operative procedures had been done. Postoperatively, all patients had immediate motion and early functional rehabilitation. The results were assessed with the Cincinnati Knee Rating System. At followup (mean, 27 months), significant improvements were found for pain, swelling, giving way, functional limitations with daily and sports activities, and the overall rating score. Forty-two patients (79%) had returned to some type of athletic activity. Only three patients (6%) had failed results. In the patients' own ratings of the overall knee condition, 8 of 51 (16%) rated their knees as normal, 28 (55%) as very good, 7 (14%) as good, 5 (10%) as fair, and 3 (6%) as poor. We concluded that the majority of patients benefited from the arthroscopically assisted anterior cruciate ligament reconstruction because it decreased episodes of giving way with daily activities and increased activity without aggravating the preexisting arthrosis.     

Endosseous implant and autogenous bone graft reconstruction of mandibular discontinuity: a 12-year longitudinal study of 31 patients

Surgical, medical, and prosthodontic records of 61 consecutively treated patients with mandibular discontinuity were reviewed retrospectively. All 61 patients had undergone discontinuity reconstruction with autogenous bone grafts; 31 of 61 had also received endosseous dental implants and a dental osseoprosthesis. Of these 31 implant-reconstructed patients, 23 had free autogenous nonvascularized and 8 had vascularized bone grafts. The surgical-prosthetic protocol consisted primarily of secondary, free autogenous nonvascularized bone graft reconstruction and secondary root-form endosseous implant and fixed prosthesis dental reconstruction. Vascularized bone (8 patients) or soft tissue (4 patients) grafts were utilized selectively for severely compromised patients after extensive oncologic resection, avulsive trauma, or after previous radiation treatment. Endosseous implant survival (95.5% in 31 patients), autogenous bone graft success (98.4% in 61 patients), and dental osseoprosthesis success (100% in 31 patients) were favorable. A high incidence (9.1%) of nonfunctioning (sleeping) implants was recorded for this patient population. The need to remove the titanium mesh tray for various reasons (17.6%) and the need to reconstruct soft tissue in the irradiated patient (12%) were noteworthy.     

Use of demineralized bone implants in orbital and craniofacial reconstruction and a review of the literature

A retrospective study and review of the literature was performed on the use of demineralized bone implants for the correction of orbital and craniofacial defects. Demineralized bone implants heal by endochondral osteogenesis, inducing a transformation of local cells, as well as by osteoconduction, similar to autogenous grafts. They induce the chemotaxis and transformation of mesenchymal cells into chondroblasts, followed by ossification. They also act as a scaffold, with bone resorption taking place simultaneous with bone formation. This study reviewed 21 patients and 31 orbits, in which demineralized bone was used for orbitocranial reconstruction for congenital deformities (nine patients), after surgery for orbital fractures (seven patients: four floor, three roof), and orbital tumors (five patients). The surgical technique is described, and the results are discussed. The follow-up period averaged 15 months (6 months to 33 months). The overall resorption rate of the demineralized bone implants was estimated based on follow-up radiologic studies (facial films, computed tomography scans, and magnetic resonance imaging scans), as well as clinical examinations. All patients had a satisfactory to excellent result. The demineralized bone and Grafton (Osteotech, Shrewsbury, NJ, U.S.A.) was obtained from the Musculoskeletal Transplant Foundation of Holmdel, New Jersey, and it was all processed and reconstituted in a standard manner with Alloprep System. Surgical complications were cerebrospinal fluid leaks (one patient) with infection, transient chemosis, enophthalmos, and hypophthalmos. There were no complications related to demineralized bone alone. Properly prepared demineralized bone is a safe material for orbital reconstruction that eliminates the need for a second operative site to harvest a bone graft.     

Biomechanical and histologic alteration of facial recipient bone after reconstruction with autogenous bone grafts and alloplastic implants: a 1-year study

Potential alteration of the underlying recipient bone resulting from a graft or implant has significant clinical relevance. The present study was designed to evaluate the biomechanical and histologic alteration of facial recipient bone with autogenous bone graft and alloplastic implants over a 1-year period. The bilateral arches of 15 rabbits were randomized between four groups: (1) control (n = 6), subperiosteal exposure of the zygomatic arch was made; (2) onlay (n = 12), bone graft was placed as an onlay to the zygomatic arch; (3) inlay (n = 6), bone graft was placed as an inlay within the zygomatic arch; (4) implant (n = 6), a stainless steel plate was placed as an onlay to the zygomatic arch. Animals were killed 1 year after grafting. In the onlay groups, all steel implants and half of the onlay bone grafts (n = 6) were separated from the zygomatic arch; the remaining onlay bone grafts (n = 6) were left on the zygomatic arch. Three-point breaking strength was measured through the center of the graft/implant site on the zygomatic arch, followed by histologic evaluation and histometric assessment of residual bone density. The findings demonstrated no difference in the breaking strength per unit bone area between the control zygomatic arch group and the onlay group in which the bone graft was left in place. Breaking strength of the zygomatic arch in the former two groups was significantly greater than that in either group in which the onlay bone graft or implant had been removed, and was also greater than the breaking strength in that group in which inlay bone had been placed (p < 0.05). Histologic assessment showed full-thickness conversion in architecture of the zygomatic arch from compact to woven bone beneath onlays of either autogenous bone graft or steel implant; histometric assessment demonstrated an accompanying decrease in bone density in the latter groups relative to the control zygoma (p < 0.05). We conclude that onlay autogenous bone graft and alloplastic implants to the facial skeleton induce transformation of both graft and recipient bone from compact to woven architecture, accompanied by a reduction in bone density. The biomechanical strength of recipient facial bone is significantly weakened if an onlay bone graft or implant is removed. Weakening occurs per unit area of remaining bone, and is therefore independent of any thinning that may occur within the recipient bone because of graft/implant placement. These findings may impact upon decisions to augment stress-bearing regions of the facial skeleton with bone graft or implants, particularly if the graft/implant may eventually require removal.     

Histological evaluation of bone reactions to aluminium oxide dental implants in man: a case report

Alumina implants have been shown to possess high biocompatibility. The authors present the case of an aluminium oxide ceramic implant removed because of fracture of the abutment after a 30-month loading period. It was possible to observe microscopically that the implant was covered by highly mineralized mature compact lamellar bone; no connective tissue or inflammatory cells were present at the interface. Osteocytes were observed very close to the bone-implant interface. These features indicate the good biocompatibility of the implant.