Histomorphometric and densitometric changes in bone volume and structure after avascular bone grafting in the extremely atrophic maxilla

AIM: To evaluate changes in volume and structure of bone after autogenous iliac crest bone grafting to the maxilla. To discover the predictive value of computed tomographic (CT) measurements of bone density and study their correlation with the results of histomorphometric analyses of bone structure. PATIENTS AND METHODS: In 25 patients with atrophic maxillae (mean age 47 years, range 15-71), who had onlay bone grafting and sinus floor augmentation with autogenous iliac crest bone, a CT analysis was carried out immediately before and after grafting, and 5 months (range 4-6) later, at the time of endosseous implantation. On both occasions, bone biopsy specimens were taken. HISTOLOGY OF BONE: After preparing and digitizing semithin sections, histomorphometry (NH-Image) was done to establish the ratio of trabeculae to medullary cavity. CT ANALYSIS: The available transverse and vertical bone and the bone density of natural and augmented bone were analyzed using the Simplant Program and the CT data. As reference, the bone density of the first cervical vertebra was used. By regression analysis, the correlation of CT bone density and histological bone structure was investigated. RESULTS: After a median healing period of 4.5 months, no significant changes were found in bone volume compared with the measurements made immediately after grafting. The changes in density in the cancellous portion of the grafted bone showed no correlation (correlation coefficient: +0.16) with the results of histomorphometric analysis of bone structure. CONCLUSIONS: The predictive value of measurement of bone density to evaluate bone structure on the basis of the D1-D4 classification needs to be reconsidered. The most favourable time for secondary implantation is 4-6 months after iliac crest bone grafting.     

Maxillary antral-nasal inlay autogenous bone graft reconstruction of compromised maxilla: a 12-year retrospective study.

During a 12-year period (1984-1996), 118 maxillary inlay autogenous bone grafts and 248 commercially pure titanium threaded root-form endosseous implants were placed in 54 consecutively treated patients with compromised maxillary bone. In this retrospective clinical study, 3 groups of patients were reviewed, group selection being based on anatomic location and surgical access to the recipient site. Group 1 included patients with bone grafts placed in the antrum floor via an intraoral antrostomy exposure, group 2 included patients with bone grafts placed in the nasal floor via an anterior intraoral nasotomy exposure, and group 3 included patients with bone grafts placed in the antral and nasal floor via an intraoral Le Fort I osteotomy downfracture exposure. Each patient received an implant-supported dental prosthesis. For the combined 3 groups, survival rates were 87% for endosseous implants and 100% for autogenous bone grafts. The success rate for the dental prostheses in the 3 groups was 95%. Sixty-nine dental prostheses functioned a mean of 57.1 months, whereas 3 prostheses required remaking because of implant loss. Of the medical and mechanical risk factors tabulated in this study, current use of nicotine, history of sinusitis, molar site implant placement, and shorter implant lengths had the most influence on implant failure.     

The model graft: reconstruction of the maxilla using a fibular bone graft template

The reconstruction of the partial maxillectomy decfect with a free graft depends on a team approach in a coordinated manner. However, this is not always possible due to physical limitations or, unfortunately, pragmatic factors in the era of managed care. A surgical template oftentimes is the critical measure of success in these cases, but may not be available or easily created for the previously mentioned reasons. In this article, we describe the use of redundant fibular bone as a template for reconstruction of the partial maxillectomy defect. This is a satisfactory alternative to a dental template in many cases, and, we believe, in some cases, may even be superior because it is the graft itself. As a result insetting can be hastened and precious ischemic time can be lessened-all favoring a successful, functional result.     

Three-dimensional volumetric changes of 5 different bone grafts in human maxillary sinuses reconstruction: a randomized clinical study

Oral and Maxillofacial Surgery - This study aimed to compare the three-dimensional volumetric changes of human maxillary sinuses after reconstruction using 5 different bone grafts. Patients...     

Iliac crest autogenous bone graft versus alloplastic graft and guided bone regeneration in the reconstruction of atrophic maxillae: a 5-year retrospective study on cost-effectiveness and clinical outcome

Background: Reconstruction of the atrophic maxillae with autogenous bone graft and jawbone‐anchored bridges is a well‐proven technique. However, the morbidity associated with the concept should not be neglected. Furthermore, the costs for such treatment, including general anesthesia and hospital stay, are significant. Little data are found in the literature with regard to a cost‐benefit approach to various treatment alternates. Purpose: The aim of this retrospective study was to compare from a health‐economical and clinical perspective the reconstruction of the atrophic maxillae prior to oral implant treatment either with autogenous bone grafts harvested from the iliac crest or the use of demineralized freeze‐dried bone (DFDB) in combination with a thermoplastic carrier (Regeneration Technologies Inc., Alachua, FL, USA) and guided bone regeneration (GBR). Materials and Methods: A total of 26 patients (13 + 13) were selected and matched with regard to indication, sex, and age. The study was performed 5 years after the completion of the treatment. Implant survival, morbidity, and complications were analyzed. Furthermore, a detailed analysis of the total cost for the respective treatment modality was performed, including material, costs for staff, sick leave, etc. Results: The study revealed no statistical difference with regard to implant survival for the respective groups. The average total cost, per patient, for the DFDB group was 22.5% of the total cost for a patient treated with autogenous bone grafting procedures. Conclusions: The study concluded that reconstruction of atrophic maxillae with a bone substitute material (DFDB) in combination with GBR can be performed with an equal treatment outcome and with less resources and a significant reduced cost in selected cases compared with autogenous bone grafts from the iliac crest.     

Reconstruction of the atrophic edentulous maxilla with free iliac crest grafts and implants: a 3-year report of a prospective clinical study

Purpose: The purpose of this study was to perform a longitudinal follow-up study of implant stability in grafted maxillae with the aid of clinical, radiological, and resonance frequency analysis (RFA) parameters. Materials and Methods: The atrophic edentulous maxillae in 29 patients were reconstructed with free iliac crest grafts using onlay/inlay or interpositional grafting techniques. The endpoint of the resorption pattern in the maxilla determined the grafting technique used. Endosteal implants were placed after 6 months of bone-graft healing. Implant stability was measured four times using RFA: when the implants were placed, after 6 to 8 months of healing, after 6 months and 3 years of bridge loading. Individual checkups were performed at the two later RFA registrations after removal of the supraconstructions (Procera® Implant Bridge, Nobel Biocare AB, Göteborg, Sweden). Radiological follow up of marginal bone level was performed annually. Results: Twenty-five patients remained for the follow-up period. A total of 192 implants were placed and with a survival rate of 90% at the 3-year follow up. Women and an implant position with a class 6 resorption prior to reconstruction were factors with significant increased risk for implant failure (multivariate logistic regression). Twelve of the 20 failed implants were lost before loading (early failures). The change in the marginal bone level was 0.3 ± 0.3 mm between baseline (bridge delivery) and the 3-year follow up. The implant stability quotient (ISQ) value for all implants differed significantly between abutment connection (60.2 ± 7.3) and after 6 months of bridge loading (62.5 ± 5.5) (Wilcoxon signed ranks test for paired data, p=.05) but were nonsignificant between 6 months of bridge loading and 3 years of bridge loading (61.8 ± 5.5). There was a significant difference between successful and failed implants when the ISQ values were compared for individual implants at placement (Mann-Whitney U test, p=.004). All 25 patients were provided with fixed implant bridges at the time of the 3-year follow up. Conclusion: This clinical follow up using radiological examinations and RFA measurements indicates a predictable and stable long-term result for patients with atrophic edentulous maxillae reconstructed with autogenous bone and with delayed placement of endosteal implants. The ISQ value at the time of placement can probably serve as an indicator of level of risk for implant failure.     

Staged reconstruction of the severely atrophic mandible with autogenous bone graft and endosteal implants.

PURPOSE: Vastly different surgical techniques have been advocated for osseous reconstruction of the severely atrophic mandible. Endosseous implants placed in autologous bone grafts have been proposed to minimize graft resorption and restore function; however, sufficient bone must exist to support the implants and prevent pathologic fracture. The purpose of this retrospective analysis was to assess the efficacy of autologous bone grafting and the subsequent placement of endosteal implants as a staged procedure in patients with severely atrophic mandibles. MATERIALS AND METHODS: The records of all patients presenting to The University of North Carolina for treatment from 1997 to 1999 with atrophic mandibles (vertical mandibular height <7 mm as measured on panoramic radiographs in at least 1 site at the mandibular midline and at the thinnest portion of the mandibular body) were reviewed. Bone height was assessed preoperatively, immediately postoperatively, at the time of implant placement (4 to 6 months), and again at 12 and 24 months after bone grafting from posterior iliac crest to the mandible via an extraoral approach. Five endosteal implants were subsequently placed in each patient as a delayed procedure 4 to 6 months after bone grafting, and prosthetic rehabilitation was completed with implant supported prostheses. RESULTS: Fourteen consecutive patients were identified with a median preoperative bone height of 9 mm (interquartile range, 25th to 75th percentile [IQ], 7 to 10 mm) in the mandibular midline and 5 mm (IQ, 2 to 5 mm) in the body region. There were no perioperative complications. Median estimated blood loss during the bone graft procedure, as estimated by the surgeon and the anesthesiologist, was 300 mL (IQ, 150 to 1,100 mL), and 1 patient required blood transfusion secondary to symptomatic anemia. The mean loss of vertical bone height after grafting and during the 4 to 6 months before implant placement was 33%. After implant placement and at 12 months, the vertical bone loss was negligible in the implant-supported region and less than 11% in the body region. CONCLUSION: Reconstruction of the severely atrophic mandible using autogenous corticocancellous bone grafts followed by placement of osseointegrated implants in 4 to 6 months can restore and maintain mandibular bone sufficient to support implants and facilitate successful restoration of occlusion. A prospective study is planned to identify predictors of successful outcomes compared with other surgical/prosthetic treatment.     

Autogenous mandibular bone grafts and osseointegrated implants for reconstruction of the severely atrophied maxilla: a preliminary report

The purpose of this study is to present results obtained with a new procedure for reconstruction of the severely atrophied maxillary alveolar ridge that involves the use of intramembranous corticocancellous bone grafts obtained from the mandibular symphysis fixed to the residual bone by endosseous implants. A total of 107 implants were installed in grafted regions in 26 patients. The follow-up period ranged from 6 to 32 months, with a mean of 16 months. In partially edentulous patients the bone grafts were fixed with implants to the residual bone as 1) onlay graft to the alveolar ridge (8 implants in 4 patients); 2) grafts to the nasal and/or sinus floor after a transoral exposure and elevation of the mucosa of the maxillary sinus and/or the nasal mucosa (33 implants in 11 patients); or 3) a combination of these two (5 implants in 2 patients). In totally edentulous patients, implants and grafts were used as a combination of grafting to both the alveolar ridge and nasal and/or sinus floor sites (61 implants in 9 patients). One hundred of 107 implants showed normal clinical and radiologic healing, whereas 7 implants in 4 patients (6.5%) were lost prior to loading. Seventeen patients have had the implants and bone grafts loaded by a prosthodontic reconstruction from 6 to 26 months (mean, 14 months) without loss of any implants. Postoperative marginal resorption of the onlay bone graft of less than 15% was observed. These findings suggest, that the previously observed rapid resorption of endochondral iliac crest onlay bone grafts and the number of lost implants can be significantly reduced if bone from the mandibular symphysis firmly anchored with titanium implants is used.     

Interpositional bone graft augmentation of the atrophic mandible: a preliminary report.

The mandible is sectioned in an oblique direction and an iliac crest graft is placed between the fragments for augmentation of an atrophied mandible. The technique was used in 12 patients; follow-up examinations included serial panoramic radiographs and recording of changes in mandibular height. A 10% to 27% loss of the height gained occurred between three and 12 months postoperatively.     

Melanotic neuroectodermal tumor of infancy involving the mandible: 7-year follow-up after hemimandibulectomy and costochondral graft reconstruction

Oral and maxillofacial tumors occur rarely in the pediatric population compared with the adult population. We report a case of a 6-months old female infant suffering from a melanotic neuroectodermal tumor of infancy involving the mandible. Tumor resection was performed using a submandibular approach; the mandibular defect was reconstructed primarily with autogenous costochondral grafts. During a 7-year follow-up period, there has been no tumor recurrence. The costochondral graft healed well; tracing of panoramic radiographs at 2, 3, and 6 years documented some vertical overgrowth and growth retardation in the transversal dimension. The authors conclude that the use of costochondral grafts despite its controversial role for mandibular reconstruction can be recommended in particular after continuity resections in newborn infants. However, long-term follow-up is necessary as well as secondary corrective surgery at early skeletal maturity.     

Biologic mechanical advantages of 3 different cranial bone grafting techniques for implant reconstruction of the atrophic maxilla.

PURPOSE: The purpose of this study was to test the mechanical capacities of 3 different bone grafting techniques in the atrophic maxilla when co-stabilized with dental implants. Reconstruction of the atrophic maxilla is a difficult clinical challenge and implants cannot be placed without adequate bone. METHODS: The biomechanical performance of 3 different grafting techniques was evaluated in vitro using a maxillary model, cadaveric cranial bone blocks, and dental implants. A maxillary model fabricated from polyurethane (sawbone) was selected as a substrate for this study because of consistency in shape, size, and mechanical properties. This anatomic model was more consistent than different cadaveric maxilla, where significant variation was found to exist among atrophic specimens. Cadaveric cranial bone graft blocks were secured to the model maxilla (sandwich, ridge only, and sinus inlay) with a dental implant. The strength of the implant/bone graft complex was tested to failure in an Instron machine (Instron Inc, Canton, MA). RESULTS: The 3 bone grafting methods showed significantly different deformation and strength characteristics. The sandwich technique enhanced resistance to deformation under higher imposed loads. The location of the graft influenced the overall mechanical performance (eg, the ridge onlay) and showed a significantly higher resistance to compressive loads applied toward the alveolar ridge (mastication force). CONCLUSION: The ridge onlay grafting procedures created a higher biomechanical tolerance to imposed load than the sinus grafting (sinus inlay). Sinus grafting, although successful, was not the most ideal location for immediate mechanical loading resistance when compared with ridge augmentation in this in vitro model.     

Three-dimensional assessment of morphologic changes of the maxilla: a comparison of 2 kinds of palatal expanders.

Previous studies of the morphologic changes of the maxilla after palatal expansion have used 2-dimensional methodologies. In the present study, we used a 3-dimensional surface laser scanning technique and computerized cast analysis, in addition to analysis of anteroposterior cephalograms, to assess the morphologic changes of the palate by 2 kinds of expanders: tissue borne (Haas; n = 9) and tooth borne (Hyrax; n = 10). Cast analysis demonstrated that, although all patients started treatment with similar malocclusion, treatment outcomes were different depending on the appliance used. Both appliances generated maxillary expansion (ie, improved mean surface area, mean intermolar linear distance, and mean perimeter) (P <.05). However, the appliances performed differently to achieve the final expansion. Haas appliances demonstrated a greater orthopedic movement (ie, improvement of the mean interpalatal distance) (P <.05), and Hyrax appliances demonstrated dentoalveolar expansion by increasing the mean palatal angulation of the alveolus (P <.05). Anteroposterior cephalometric analysis showed that both appliances increased mean maxillary width and mean intermolar distance significantly (P <.05). On the other hand, differences in nasal cavity width and upper incisal apex distance were not statistically significant (P >.05). This new 3-dimensional methodology proved useful for comparing treatment outcomes by evaluating the morphologic changes induced by palatal expansion and generated a better visualization of these outcomes.