RESUMEN
INTRODUCTION: Patients with mucosal cysts in the maxillary sinus require special consideration in patients who require implant therapy for the restoration when undergoing implant therapy for the restoration of the posterior maxillary dentition. Treatment strategies for these clinical situations remain controversial in the literature. Thus, this study seeks to describe a safe and effective therapeutic strategy for sinus augmentation in patients with pre-existing maxillary antral cysts. METHODS: A total of 15 patients and 18 sinuses were consecutively enrolled in this cohort study and underwent maxillary antral cyst treatment by needle aspiration and simultaneous maxillary sinus augmentation (MSA). During surgical procedures, threeimplants (Zimmer Biomet, Indiana, USA) were positioned in 11 sinuses and two implants (Zimmer Biomet, Indiana, USA) were positioned in 5 sinuses. RESULTS: Overall implant success and survival rates were 100% and 97.8%, respectively at 1 year and 5-year follow-ups. Crestal bone resorption averaged 0.3 ± 0.2 mm 5-year post-loading, showing bone stability. Implant survival rate at 5-year follow-up expressed predictability of the technique comparable to historical data when MSA was performed alone. Crestal bone resorption averaged 0.3 ± 0.2 mm 5 years post-loading and shows bone stability utilizing mucosal cyst aspiration with concomitant MSA procedures. Quality of life evaluation at 1-week post-op showed similar results to published historical data. In 81% (13 sinuses), the CBCT examination at 5-year follow-up showed no cyst reformation, in 19% (3 sinuses) cyst reformation was visible, but smaller in size when compared to the pre-op CBCT evaluation, and all the patients were asymptomatic. CONCLUSIONS: Maxillary sinus mucosal cyst aspiration with concomitant MSA, may be a viable option to treat maxillary sinus cyst.
Asunto(s)
Seno Maxilar , Elevación del Piso del Seno Maxilar , Humanos , Elevación del Piso del Seno Maxilar/métodos , Femenino , Masculino , Persona de Mediana Edad , Seno Maxilar/cirugía , Seno Maxilar/diagnóstico por imagen , Quistes/cirugía , Quistes/complicaciones , Adulto , Estudios de Cohortes , Anciano , Implantación Dental Endoósea/métodosRESUMEN
PURPOSE: To establish consensus-driven guidelines that could support the clinical decision-making process for implant-supported rehabilitation of the posterior atrophic maxilla and ultimately improve long-term treatment outcomes and patient satisfaction. MATERIALS AND METHODS: A total of 33 participants were enrolled (18 active members of the Italian Academy of Osseointegration and 15 international experts). Based on the available evidence, the development group discussed and proposed an initial list of 20 statements, which were later evalu-ated by all participants. After the forms were completed, the responses were sent for blinded ana-lysis. In most cases, when a consensus was not reached, the statements were rephrased and sent to the participants for another round of evaluation. Three rounds were planned. RESULTS: After the first round of voting, participants came close to reaching a consensus on six statements, but no consensus was achieved for the other fourteen. Following this, nineteen statements were rephrased and sent to participants again for the second round of voting, after which a consensus was reached for six statements and almost reached for three statements, but no consensus was achieved for the other ten. All 13 statements upon which no consensus was reached were rephrased and included in the third round. After this round, a consensus was achieved for an additional nine statements and almost achieved for three statements, but no consensus was reached for the remaining statement. CONCLUSION: This Delphi consensus highlights the importance of accurate preoperative planning, taking into consideration the maxillomandibular relationship to meet the functional and aesthetic requirements of the final restoration. Emphasis is placed on the role played by the sinus bony walls and floor in providing essential elements for bone formation, and on evaluation of bucco-palatal sinus width for choosing between lateral and transcrestal sinus floor elevation. Tilted and trans-sinus implants are considered viable options, whereas caution is advised when placing pterygoid implants. Zygomatic implants are seen as a potential option in specific cases, such as for completely edentulous elderly or oncological patients, for whom conventional alternatives are unsuitable.
Asunto(s)
Implantes Dentales , Elevación del Piso del Seno Maxilar , Humanos , Anciano , Maxilar/cirugía , Elevación del Piso del Seno Maxilar/métodos , Consenso , Técnica Delphi , Estética Dental , Atrofia/patologíaRESUMEN
Maxillary sinus floor elevation, via the lateral approach, is one of the most predictable bone augmentation procedures performed in implant dentistry. but both intra- and postoperative complications can occur, and some of them are severe. Our aim is as follows: To review the pertinent literature on the topic, especially assessing the risk factors related to complications. To give clinical recommendations to minimize intra- and postoperative complications with the ultimate scope of improving the standard of clinical care and patient safety.
Asunto(s)
Elevación del Piso del Seno Maxilar , Humanos , Elevación del Piso del Seno Maxilar/efectos adversos , Elevación del Piso del Seno Maxilar/métodos , Seno Maxilar/cirugía , Complicaciones Posoperatorias/prevención & control , Complicaciones Posoperatorias/cirugía , Factores de Riesgo , Implantación Dental Endoósea/efectos adversos , Implantación Dental Endoósea/métodosRESUMEN
The aim of the present study was to generate an international and multidisciplinary consensus on the clinical management of implant protrusion into the maxillary sinuses and nasal fossae. A total of 31 experts participated, 23 of whom were experts in implantology (periodontologists, maxillofacial surgeons and implantologists), 6 were otolaryngologists and 2 were radiologists. All the participants were informed of the current scientific knowledge on the topic based on a systematic search of the literature. A list of statements was created and divided into three surveys: one for all participants, one for implant providers and radiologists and one for otolaryngologists and radiologists. A consensus was reached on 15 out of 17 statements. According to the participants, osseointegrated implants protruding radiographically into the maxillary sinus or nasal fossae require as much monitoring and maintenance as implants fully covered by bone. In the event of symptoms of sinusitis, collaboration between implant providers and otolaryngologists is required. Implant removal should be considered only after pharmacological and surgical management of sinusitis have failed.
Asunto(s)
Implantes Dentales , Sinusitis , Consenso , Técnica Delphi , Implantes Dentales/efectos adversos , Humanos , Seno Maxilar/diagnóstico por imagenRESUMEN
Recently, the Low Window technique was proposed to facilitate sinus augmentation and reduce postsurgical patient discomfort. It was shown to be both safe and effective. This case series evaluates the postsurgical discomfort of patients undergoing Low Window sinus augmentation, the bone gain achieved, and whether these factors correlate with the osteotomy area. Records of patients (n = 26) who underwent a sinus elevation using the Low Window approach (n = 34 interventions), followed by implant placement and prosthetic rehabilitation (n = 97 implants), were assessed retrospectively. The analyzed outcomes were the medial, middle, and lateral bone gain ≥ 9 months after augmentation; pain at 5 to 6 hours postsurgery, evaluated on a visual analog scale (VAS; 0 to 100); pain, swelling, and hematoma formation every day up to 7 days postsurgery, evaluated by VAS; implant and prosthetic success and survival rates; and rate of complications. The average follow-up time was 62.1 ± 14.9 months. No intraoperative sinus membrane perforations or other complications occurred. Medial, middle, and lateral bone gains were 10.1 ± 1.7 mm, 11.6 ± 0.8 mm, and 10.7 ± 0.9 mm, respectively. At the last follow-up, the implant success rate was 99%. Postsurgical VAS pain 5 to 6 hours postsurgery was 12.3 ± 8.0 and decreased significantly thereafter. Swelling prevalence was 29.4% at 1 day postsurgery, 20.6% at 2 days, and 2.9% the following day. No swelling was observed from day 4 onward. Prevalence of hematoma was 8.8% for 2 days postsurgery, 2.9% the day after, and no hematoma was observed thereafter. Only the osteotomy area correlated with immediate postsurgical pain, but not with other discomfort outcomes or with bone gain. Low Window sinus elevation might allow bone gain and medium-term implant and prosthetic success rates similar to that of other access window designs. Prospective, comparative studies are needed to investigate whether the technique is more advantageous than traditional approaches.
Asunto(s)
Implantes Dentales , Elevación del Piso del Seno Maxilar , Implantación Dental Endoósea/efectos adversos , Implantación Dental Endoósea/métodos , Humanos , Maxilar/cirugía , Seno Maxilar/cirugía , Dolor/cirugía , Estudios Prospectivos , Estudios Retrospectivos , Elevación del Piso del Seno Maxilar/efectos adversos , Elevación del Piso del Seno Maxilar/métodosRESUMEN
Maxillary sinus elevation by the lateral window approach has been shown to be a highly predictable surgical procedure for increasing bone volume in the posterior maxilla. There are occasions, however, where this procedure may be difficult or impossible to perform in a highly predictable manner. There are many presurgical conditions and anatomical features that can make lateral window access difficult, leading to an increase in intraoperative complications and procedural failures. These complicating factors include complex internal sinus anatomy (multiple septa, anteroposterior septa), a narrow available window space, a thin or absent labial plate on adjacent teeth, and the presence of a root apex in the proposed window area, or it may be due to iatrogenically created defects, such as a previous failed sinus elevation, a healed oroantral fistula, or defects created by difficult extractions. While not frequently used or routinely reported in the literature, the palatal window approach may negate many of these obstacles. When it is reported, success rates are similar to those of lateral window procedures, and as an added advantage, postoperative morbidity is dramatically reduced, allowing the patient to wear a removable appliance immediately after surgery. There are, however, anatomical limitations that dictate when this procedure can be used. This case report is unique in that many of the lateral window complicating factors are present, and the palatal anatomy proved ideal for performing the technique.
Asunto(s)
Elevación del Piso del Seno Maxilar , Implantación Dental Endoósea/métodos , Humanos , Maxilar/cirugía , Seno Maxilar/cirugía , Hueso Paladar/cirugía , Elevación del Piso del Seno Maxilar/métodosRESUMEN
INTRODUCTION: Maxillary sinus augmentation is a common and predictable procedure utilized to gain vertical alveolar bone height to allow for successful placement of dental implants in the deficient posterior maxilla. The surgical techniques, however, may be associated with intraoperative complications, the most common of which is Schneiderian membrane perforation and, less commonly, bleeding and the loss of an implant into the sinus cavity. CASE PRESENTATION: In the current report, we present two cases with unique complications. A large perforation which was discovered after the graft material had been placed was successfully managed by carefully removing the graft material from both sides of the perforation and sealing the perforation with a resorbable membrane and a tack fixation. The second case involved a patient who presented with an implant that had migrated into the sinus during an unsuccessful transcrestal sinus lift. The case was successfully treated by locating and removing the implant through an intentional membrane perforation, repairing the perforation, and placing a new implant with simultaneous grafting. CONCLUSION: Management and repair of maxillary sinus membrane perforations that are either intentionally or iatrogenically created can be predictable procedures with favorable outcomes if thoughtful evaluation and treatment are provided. Managing such complications at the time of occurrence avoids unnecessary additional surgical procedures that might prove to be even more complicated.
Asunto(s)
Implantes Dentales , Seno Maxilar , Implantación Dental Endoósea/métodos , Implantes Dentales/efectos adversos , Humanos , Enfermedad Iatrogénica , Maxilar/cirugía , Seno Maxilar/diagnóstico por imagen , Seno Maxilar/cirugíaRESUMEN
Maxillary sinus grafting is generally a safe procedure. However, intraoperative complications, as well as early and late postoperative complications, may occur. Included in the latter group are graft infections that can be triggered by peri-implantitis. The aim of the present study was to report three cases of late maxillary sinus graft infections and to histologically evaluate the effects of peri-implantitis in the grafted area. In peri-implantitis cases in grafted sinuses, the sole removal of the implant along with accompanying debridement of the infected area may not be sufficient to resolve the infection, and a more-aggressive treatment may be necessary.
Asunto(s)
Implantes Dentales , Sinusitis Maxilar , Periimplantitis , Elevación del Piso del Seno Maxilar , Implantes Dentales/efectos adversos , Humanos , Seno Maxilar/diagnóstico por imagen , Seno Maxilar/cirugía , Sinusitis Maxilar/diagnóstico por imagen , Sinusitis Maxilar/etiología , Sinusitis Maxilar/cirugía , Periimplantitis/etiología , Elevación del Piso del Seno Maxilar/efectos adversosRESUMEN
Maxillary sinus augmentation is a procedure commonly performed in patients in need of posterior maxillary implants with limited vertical ridge height and sinus pneumatization. However, minimal information has been presented to evaluate the complexity of the sinus elevation procedure via a lateral window approach based on patient examination, including extraoral findings, anatomical factors, and the possible influence from the surgeon's experience. Therefore, this article presents a new scheme of maxillary sinus floor elevation difficulty score based on comprehensive patient- and surgical-related factors. The proposed scoring tool aims to aid surgeons in performing a comprehensive presurgical evaluation prior to the lateral wall sinus augmentation surgery and also enhance communication between clinicians and patients regarding the complexity of the case.
Asunto(s)
Seno Maxilar/cirugía , Elevación del Piso del Seno Maxilar , Implantación Dental Endoósea , Humanos , Maxilar/cirugíaRESUMEN
Maxillary sinus augmentation is the most predictable of the pre-prosthetic surgical procedures. There are, however, known and well-documented complications that can and do occur. The most common are the intraoperative complications of sinus membrane perforation and bleeding, and the postoperative complications of sinus graft infections, sinus infections, and sinusitis. The majority of these complications can be prevented, or their incidence greatly reduced, through a thorough understanding of maxillary sinus anatomy, the multifaceted etiologies of these conditions, and the steps that can be taken to avoid them. This volume of Periodontology 2000 will discuss both the preoperative and intraoperative procedures that will prevent these untoward outcomes and the necessary treatment modalities that will limit their adverse effects.
Asunto(s)
Elevación del Piso del Seno Maxilar , Implantación Dental Endoósea , Humanos , Complicaciones Intraoperatorias , Seno Maxilar , Complicaciones Posoperatorias , Factores de RiesgoRESUMEN
This retrospective study investigated the changes in the maxillary sinus floor and alveolar crest following extraction of maxillary molars. Pre- and postextraction cone beam computed tomography scans of 23 patients were analyzed. Paired-sample t tests compared pre- and postextraction measurements, and independent-sample t tests were utilized for intergroup comparisons. Pearson correlation was used to assess the association between the measured variables and the outcome measures. The mean alveolar bone height reduction was 3.42 ± 2.40 mm and the alveolar crest loss was 3.07 ± 2.53 mm. The maxillary sinus floor position shifted coronally by a mean of 0.47 ± 0.32 mm. Approximately 88% of postextraction changes in alveolar bone height were due to alveolar crest changes, compared to 12% due to changes in the sinus floor position. The results of this study challenge the commonly held concept of extensive postextraction maxillary sinus floor alterations leading to sinus pneumatization.
Asunto(s)
Elevación del Piso del Seno Maxilar , Tomografía Computarizada de Haz Cónico Espiral , Tomografía Computarizada de Haz Cónico , Humanos , Seno Maxilar , Diente Molar , Estudios RetrospectivosRESUMEN
PURPOSE: The present, randomized, controlled clinical trial compared the histologic and histomorphometric results from maxillary sinus augmentation with either biphasic calcium phosphate (BCP) (60% hydroxyapatite and 40% ß-tricalcium phosphate) or autogenous bone (AB) as bone-grafting materials. MATERIAL AND METHODS: Ten patients received bilateral sinus elevation surgery with intraoral AB chips (control group) on one side and BCP (test group) on the contralateral side. After a healing period of 6 to 8 months, implant sites were created and trephine cores were harvested for histological and histomorphometric analysis of the grafted areas. RESULTS: The histological examination of biopsies showed BCP particles interconnected by bridges of a vital newly formed bone. Histomorphometry demonstrated that the amount of newly formed bone in the control group (36.8%) was significantly greater than that in the BCP (28.2%) group (P = 0.0032). BCP and AB cores revealed an average of residual graft particles of 32.9% and 4.8%, respectively. The average percentage of soft tissue components was 38.9% in the BCP cores and 58.4% in the AB cores. CONCLUSIONS: Based on our findings, the amount of vital bone formation was significantly higher for AB than that for BCP. However, BCP seemed to be a biocompatible and osteoconductive material that can be used with success as a bone substitute in maxillary sinus procedures.
Asunto(s)
Trasplante Óseo/métodos , Cerámica/uso terapéutico , Elevación del Piso del Seno Maxilar/métodos , Adulto , Anciano , Regeneración Ósea , Sustitutos de Huesos/uso terapéutico , Humanos , Hidroxiapatitas/uso terapéutico , Seno Maxilar/patología , Persona de Mediana EdadRESUMEN
Several systematic reviews have shown that maxillary sinus augmentation is a predictable and effective procedure for augmentation of an atrophic posterior maxilla. However, we know of no reviews that have covered all the clinical aspects. We searched the PubMed, EMBASE, Cinhal, and Cochrane databases up to January 2015 to select relevant studies that cover the different objectives of this review, including the anatomy of the maxillary sinus, surgical techniques, biomaterials used in the sinus augmentation, and potential complications.
Asunto(s)
Materiales Biocompatibles , Seno Maxilar/cirugía , Elevación del Piso del Seno Maxilar , Implantación Dental Endoósea , Humanos , MaxilarRESUMEN
Conventional dentoalveolar osseous augmentation procedures for creating bone volume for dental implant placement often involve the use of grafting materials with or without barrier membranes to foster selective cell and tissue repopulation. A study was conducted to determine the efficacy of equine particulate bone (Equimatrix, Osteohealth) to augment the creation of new bone and preserve the volume of bone at extraction sites for the purpose of placing an implant in an optimal position for restoration. Clinical and histologic evidence supported the suitability of equine particulate bone for extraction site augmentation that allowed dental implant placement after a 6-month healing period.
Asunto(s)
Densidad Ósea , Alveolo Dental/cirugía , Adulto , Anciano , Animales , Implantes Dentales , Femenino , Caballos , Humanos , Masculino , Persona de Mediana Edad , Radiografía , Alveolo Dental/diagnóstico por imagenRESUMEN
The predictability of maxillary sinus augmentation has been extensively reported. Procedural outcomes, most often measured as implant survival rates, have customarily used inclusion criteria that included a minimum 1-year loading time. The inclusion criteria of this review extended the minimum postloading evaluation to 3 years to determine if the previously reported short-term survival rates are maintained. An electronic search of the literature was performed and retrieved articles were screened using specific inclusion criteria, paramount of which was a minimum of 3 years of follow-up. The search revealed 18 articles for the lateral window approach (6,500 implants in 2,149 patients) and 7 for the transalveolar approach (1,257 implants in 704 patients). Overall, implant survival after a minimum of 3 years loading was 93.7% and 97.2% for the lateral window and transalveolar approaches, respectively. Of importance is the fact that 80% of failures occurred within the first year and 93.1% of the failures occurred within 3 years. The risk of implant failure after 3 years can now be directly calculated as the overall risk of failure after 3 years (6.3%) × the incidence of late failures (6.9%), thus equaling 0.43%. This review discredits the theory that studies of a lower level of evidence report inflated results when compared with prospective randomized controlled clinical trials.
Asunto(s)
Implantación Dental Endoósea , Seno Maxilar/cirugía , Fracaso de la Restauración Dental , HumanosRESUMEN
The purpose of this study was a histomorphometric comparison of vital bone formation following maxillary sinus augmentation with two different particle sizes of anorganic bovine bone matrix (ABBM). Bilateral sinus floor augmentations were performed in 13 patients. Trephine bone cores were taken from the lateral window areas of 11 patients 6 to 8 months after augmentation for histologic and histomorphometric analysis. Bone samples from both the large and small particle size groups showed evidence of vital bone formation similar to that seen in previous studies, confirming the osteoconductivity of ABBM. Significant bone bridging was seen creating new trabeculae composed of the newly formed bone and residual ABBM particles. Histologic evaluation revealed the newly formed bone to be mostly woven bone with some remodeling to lamellar bone. Osteocytes were seen within the newly formed bone as well as osteoblast seams with recently formed osteoid. Isolated osteoclasts were observed on the ABBM surfaces. Vital bone formation (primary outcome measure) was more extensive in the large particle grafts compared with the small particle grafts (26.77% ± 9.63% vs 18.77% ± 4.74%, respectively). The histologic results reaffirm the osteoconductive ability of ABBM when used as the sole grafting material in maxillary sinus augmentation. The histomorphometric results at 6 to 8 months revealed a statistically significant increase (P = .02) in vital bone formation when the larger particle size was used. Additional studies should be performed to confirm these results.
Asunto(s)
Matriz Ósea/trasplante , Xenoinjertos/trasplante , Osteogénesis/fisiología , Elevación del Piso del Seno Maxilar/métodos , Animales , Biopsia/métodos , Densidad Ósea/fisiología , Células de la Médula Ósea/patología , Matriz Ósea/patología , Remodelación Ósea/fisiología , Sustitutos de Huesos/uso terapéutico , Bovinos , Tejido Conectivo/patología , Femenino , Estudios de Seguimiento , Osteón/patología , Xenoinjertos/patología , Humanos , Masculino , Seno Maxilar/patología , Minerales/uso terapéutico , Osteoblastos/patología , Osteocitos/patología , Tamaño de la Partícula , Estudios Prospectivos , Resultado del TratamientoRESUMEN
CONTEXT: The maxillary sinus elevation procedure has become an important pre-prosthetic surgical procedure for the creation of bone volume in the edentulous posterior maxilla for the placement of dental implants. Research and clinical experience over the past 30 years has increased the predictability of this procedure as well as reduced patient morbidity. EVIDENCE ACQUISITION: Data on grafting materials and implant survival rates comes from 10 published evidence-based reviews that include all relevant published data from 1980 to 2012. Supporting clinical material comes from the experience of the authors. EVIDENCE SYNTHESIS: The evidence-based reviews report and compare the implant survival rates utilizing various grafting materials, implant surfaces, and the use or non-use of barrier membranes over the lateral window. Clinical studies report on complication rates utilizing piezoelectric surgery and compare them to complication rates with rotary instrumentation. CONCLUSIONS: The conclusions of all the evidence-based reviews indicate that the utilization of bone replacement grafts, rough-surfaced implants, and barrier membranes result in the most positive outcomes when considering implant survival. Further, the utilization of piezoelectric surgery, rather than rotary diamond burs, for lateral window preparation and membrane separation leads to a dramatic reduction in the occurrence of the intraoperative complications of bleeding and membrane perforation.
Asunto(s)
Sustitutos de Huesos , Trasplante Óseo/métodos , Maxilar/cirugía , Seno Maxilar/cirugía , Procedimientos Quirúrgicos Preprotésicos Orales/métodos , Implantes Dentales , Humanos , Membranas Artificiales , Piezocirugía/métodos , Trasplante Heterólogo/métodosRESUMEN
PURPOSE: Long-term success of dental implants has been demonstrated when placed simultaneously with or after a sinus augmentation procedure. However, optimal bone formation can be from 6 to 9 months or longer with grafting materials other than autogenous bone. For this reason, there is interest in any surgical technique that does not require autogenous bone harvesting, yet results in sufficient bone formation within a relatively short time frame. MATERIALS AND METHODS: This study evaluated and compared bone formation following sinus-augmentation procedures using either an allograft cellular bone matrix (ACBM), containing native mesenchymal stem cells and osteoprogenitors, or conventional allograft (CA). RESULTS: Histomorphometric analysis of the ACBM grafts revealed average vital bone content of 32.5% ± 6.8% to residual graft content of 4.9% ± 2.4% for the 21 sinuses in the study, at an average healing period of 3.7 ± 0.6 months. Results for the CA, in the same time frame, were average vital bone content of 18.3% ± 10.6% to residual graft content of 25.8% ± 13.4%. A comparison of ACBM and CA grafts, for both vital and residual bone contents, showed P values of .003 and .002, respectively, indicating a statistically significant difference between the groups. CONCLUSION: The high percentage of vital bone content, after a relatively short healing phase, may encourage a more rapid initiation of implant placement or restoration when a cellular grafting approach is considered.
Asunto(s)
Aumento de la Cresta Alveolar/métodos , Matriz Ósea/trasplante , Seno Maxilar/cirugía , Trasplante de Células Madre Mesenquimatosas/métodos , Adulto , Anciano , Proceso Alveolar/patología , Biopsia , Criopreservación/métodos , Femenino , Estudios de Seguimiento , Supervivencia de Injerto , Humanos , Procesamiento de Imagen Asistido por Computador , Masculino , Maxilar/patología , Maxilar/cirugía , Seno Maxilar/patología , Persona de Mediana Edad , Osteogénesis/fisiología , Conservación de Tejido/métodos , Tomografía Computarizada por Rayos X , Trasplante Homólogo , Cicatrización de Heridas/fisiologíaRESUMEN
The objective of the following case reports was to assess whether mineralized bone replacement grafts (eg, xenografts and allografts) could be added to recombinant human bone morphogenetic protein-2/acellular collagen sponge (rhBMP-2/ACS) in an effective manner that would: (1) reduce the graft shrinkage observed when using rhBMP-2/ACS alone, (2) reduce the volume and dose of rhBMP-2 required, and (3) preserve the osteoinductivity that rhBMP-2/ACS has shown when used alone. The primary outcome measures were histomorphometric analysis of vital bone production and analysis of serial computed tomographic scans to determine changes in bone graft density and stability. Over the 6-month course of this investigation, bone graft densities tended to increase (moreso with the xenograft than the allograft). The increased density in allograft cases was likely the result of both compression of the mineralized bone replacement graft and vital bone formation, seen histologically. Loss of volume was greater with the four-sponge dose than the two-sponge dose because of compression and resorption of the sponges. Vital bone formation in the allograft cases ranged from 36% to 53% but, because of the small sample size, it was not possible to determine any significant difference between the 5.6 mL (four-sponge) dose and the 2.8 mL (two-sponge) dose. Histology revealed robust new woven bone formation with only minimal traces of residual allograft, which appeared to have undergone accelerated remodeling or rhBMP-2-mediated resorption.