Long-term changes in graft height after maxillary sinus augmentation, onlay bone grafting, and combination of both techniques: a long-term retrospective cohort study

Use of autologous micrografts associated with xenogeneic anorganic bone in vertical bone augmentation procedures with Barbell Technique®

INTRODUCTION

Bidirectional vertical ridge augmentation in the posterior maxilla is very challenging.

PURPOSE

To evaluate the regenerative potential of micrografts, derived from periosteum or bone tissue, added to an anorganic xenograft in vertical reconstruction of the posterior maxilla, by a prospective, controlled study.

MATERIALS AND METHODS

After clinical selection and the analysis of CBCT scans, 24 posterior maxillary sites, in 19 patients, were treated by using Barbell Technique®. Sites requiring both inlay and onlay reconstruction were enrolled in the study. In the Control Group (CG, n = 8), a xenograft was used in the inlay site and for the onlay site, a 1:1 mix of xenograft and an autograft was used. In Test Group 1 (TG1, n = 8), both inlay and onlay sites were grafted with the xenograft associated with the micrografts derived from periosteum. In Test Group 2 (TG2, n = 8), both inlay and onlay sites were grafted with the xenograft associated with the micrografts derived from bone. Six months after the procedures, CBCT scans were obtained, and bone biopsy samples were harvested during implant placement surgery. The bone specimens were analyzed histomorphometrically, by measuring the percentages of vital mineralized tissue (VMT), non vital mineralized tissue (NVMT) and non mineralized tissue (NMT). Immunohistochemically, the levels of VEGF were categorized by a score approach.

RESULTS

Histomorphometric analysis revealed, for the inlay grafts, no significant difference among the groups for VMT, NVMT and NMT. However, for onlay grafts, CG achieved a higher amount of VMT in comparison with TG2, and the opposite occurred for NMT values. In this regard, no statistical difference was observed between CG and TG1. Concerning immunohistochemistry, the VEGF values for CG and TG1 were slightly higher than those obtained by TG2 for both inlay and onlay grafts, but without statistical significance. CBCT analysis showed a similar level of gain for all groups, for both inlay and onlay bone augmentation sites. Clinically, one implant (in CG) within a total of 50 implants installed, had early failure and was replaced after 3 months. All patients received implant supported prosthesis.

CONCLUSION

This study indicated that the clinical use of micrograft derived from periosteum may have some potential to increase bone formation in onlay reconstructions, unlike the micrograft derived from bone tissue.

Radiographic graft changes following maxillary sinus floor augmentation with autogenous bone compared with composite grafts: a one-year single-blind randomized controlled trial

This study evaluated radiographic graft changes following maxillary sinus floor augmentation with (A) autogenous bone, (B) 1:1 autogenous bone and deproteinized porcine bone mineral, or (C) 1:1 autogenous bone and biphasic bone graft material. Sixty patients were randomly allocated to groups A, B, and C (20 in each). CBCT scans were obtained at enrolment, after surgery (T1), after prosthetic rehabilitation (T2), and 1 year after implant loading (T3). Significant decreases in graft volume (3D) and graft height (2D) from T1 to T3 were observed in all groups (P < 0.05). However, at T2 and T3, graft volume was significantly higher in group B than in groups A and C (P < 0.05), and graft height was significantly higher in group B than in group A (P < 0.05). Bone density increased significantly from T1 to T2 in all groups (P < 0.001). However, bone density was significantly higher in group B than in groups A and C, at T2 and T3 (P < 0.05). No significant correlation between graft volume or height and implant protrusion length or residual bone height was found. In conclusion, 1:1 autogenous bone and porcine bone resulted in significantly higher graft volume, height, and bone density when compared with autogenous bone or a 1:1 ratio of autogenous bone and biphasic bone. However the higher graft volume, height, and bone density did not appear to lead to improved outcomes at 1 year of functional loading when compared to the other groups.

Endo-sinus bone gain following sinus membrane elevation without graft compared with sinus floor augmentation and a composite graft: a one-year single-blind randomized controlled trial

The objective of this study was to assess endo-sinus bone gain (ESBG) and bone density (BD) following maxillary sinus membrane elevation without graft (test) compared with maxillary sinus floor augmentation and 1:1 ratio of autogenous bone from the buccal antrostomy and deproteinized porcine bone mineral (control) using two- and three-dimensional radiographic methods. Forty healthy patients were randomly allocated to the test and control groups. Cone beam computed tomography scans were obtained at enrolment (T0), immediately after surgery (T1), at delivery of the prosthetic rehabilitation (T2), and 1 year after functional implant loading (T3). Mean differences were expressed with the 95% confidence interval. Significance was set at ≤ 0.05. ESBG and BD were significantly higher in the control group than test group at T1, T2, and T3 (P < 0.001). A significant decrease in ESBG and increase in BD was observed from T1 to T3 with both treatments (P < 0.001). There was a non-significant positive correlation of ESBG with implant protrusion length and non-significant negative correlation with residual bone height. In conclusion, test was associated with significantly lower ESBG and BD compared with control. However, the lower ESBG and BD did not appear to negatively affect the implant stability quotient or implant treatment outcome after 1 year of functional implant loading.

Tilted Implants and Sinus Floor Elevation Techniques Compared in Posterior Edentulous Maxilla: A Retrospective Clinical Study over Four Years of Follow-Up

The aim of this study was to evaluate the implant survival rate, marginal bone loss, and surgical and prosthetic complications of implants placed through sinus floor elevation and tilted implants engaged in basal bone to bypass the maxillary sinus. Sixty patients were enrolled for this study. According to the residual bone height of the posterior maxilla, the sample was divided into three groups of 20 patients: Group A (lateral sinus floor elevation), Group B (transcrestal sinus floor elevation), and Group C (tilted implants employed to bypass the sinus floor). Follow-up visits were performed one week after surgery, at three and six months, and then once a year for the next 4 years. The outcomes were the implant survival rate, marginal bone loss, and surgical and prosthetic complications. Although Groups A, B, and C demonstrated implant survival rates of 83.3%, 86.7%, and 98.3%, respectively, the statistical analysis showed no statistically significant difference between groups. Statistically significant differences between groups were also not found concerning marginal bone loss, as recorded by intra-oral X-ray measurements during follow-up examinations. Regarding complications, it was not possible to perform a statistical analysis. To reduce possible surgical risks, implant placement in basal bone could be preferred.

Retrospective analysis of time-related three-dimensional iliac bone graft resorption following sinus lift and vertical augmentation in the maxilla

The atrophic maxilla frequently requires bone grafting using an onlay graft (OG) or sinus lifting (SL) before implant rehabilitation. The resorption of bone grafts is influenced by the time until implantation, quality of donor bone, and grafting technique. The aim of this study was to investigate the impact of both grafting techniques on the time-related resorption of autologous iliac bone graft. Forty-three patients underwent either onlay grafting or a sinus lift at 73 sites in the maxilla. Graft height was measured by cone beam computed tomography after augmentation and during follow-up for up to 12 months prior to implant insertion. The effect of time and technique on graft resorption was evaluated retrospectively. The reduction in bone graft height was greater for OG than SL over the investigated time intervals (OG = 51%, SL = 28%; P = 0.002). Each technique followed a specific course of resorption, which was independent of the initial graft height and could be calculated by a non-linear regression model. Iliac bone graft undergoes rapid resorption when used as an OG prior to implant insertion. For SL, this resorption is reasonably lower. This is especially crucial to determine the optimal time for implant insertion after graft healing to improve implant survival.

Maxillary Sinus Floor Augmentation with Autogenous Bone Graft Compared with a Composite Grafting Material or Bone Substitute Alone: a Systematic Review and Meta-Analysis Assessing Volumetric Stability of the Grafting Material

Objectives

Test the hypothesis of no difference in the volumetric stability of the grafting material following maxillary sinus floor augmentation with autogenous bone graft compared with composite grafting material or bone substitute alone applying the lateral window technique.

Material and Methods

MEDLINE (PubMed), Embase, Cochrane library and hand-search of relevant journals were conducted. Human studies published in English until the 9^th of October 2020 were included. Outcome measures included three-dimensional volumetric changes of the grafting material and potential predictive parameters. Volumetric changes were evaluated by descriptive statistics and meta-analysis including 95% confidence interval.

Results

Electronic search and hand-searching resulted in 102 entries. Four randomized controlled trials with unclear risk of bias fulfilled the inclusion criteria. The volumetric stability of the grafting material was significantly improved by mixing autogenous bone graft with a non-resorbable xenograft compared with autogenous bone graft. Meta-analyses assessing absolute and relative volumetric changes demonstrated no significant differences between autogenous bone graft compared with allogeneic bone graft, synthetic biomaterials combined with autogenous bone graft or used alone. Association between volumetric changes of the grafting material and potential predictive parameters were not assessed in the included studies.

Conclusions

Volumetric reduction of the augmented area seems inevitable following maxillary sinus floor augmentation regardless of the grafting material. The volumetric stability of autogenous bone graft is improved with addition of xenograft compared with autogenous bone graft. However, conclusions drawn from this systematic review should be interpreted with caution since only four studies using three-dimensional radiographic measurements were included.

Long-Term Influence of Platelet-Rich Plasma (PRP) on Dental Implants after Maxillary Augmentation: Retrospective Clinical and Radiological Outcomes of a Randomized Controlled Clinical Trial

: The long-term clinical and radiological outcomes of dental implants inserted in augmented bone treated with platelet-rich plasma (PRP) has not been well addressed in the literature yet. This study is based on a collection of patients from a randomized controlled trial (RCT) that did not report any short-term positive effects of PRP on bone healing after sinus lift surgery using autologous iliac crest bone graft. This study aimed to evaluate the long-term impact of PRP regarding clinical and radiological outcomes on the inserted implants in the previous RCT. For this evaluation, we considered the following variables: plaque index, probing depth, bleeding index, mobility grade, Periotest® values, and radiological bone loss. Out of 53 patients (n = 306 implants) included in the previous study we were able to reinvestigate 37 patients (n = 210 implants) in two centers (31 in Giessen, Germany and 6 in Erlangen, Germany). Clinical and radiographic parameters suggested overall healthy conditions of the peri-implant tissue. The PRP-group and the control group did not differ significantly in the majority of the parameters. The overall evaluation showed that result data of the PRP-group was inferior to the control group in 64 percent of the evaluated parameters. The present study cannot provide evidence of a positive effect of PRP on the long-term implant clinical and radiological outcomes. In fact, a tendency towards inferior long-term results in the PRP-group was detected without reaching a significant threshold. Further controlled trials need to be conducted to investigate this correlation.

Prosthetic Rehabilitation of the Posterior Atrophic Maxilla, Short (≤6 mm) or Long (≥10 mm) Dental Implants? A Systematic Review, Meta-analysis, and Trial Sequential Analysis: Naples Consensus Report Working Group A

PURPOSE

To compare the clinical and patient-reported outcomes of ≤6-mm implants with those of ≥10-mm implants placed after both lateral and transcrestal sinus floor elevation.

MATERIALS AND METHODS

Using PubMed (MEDLINE), EMBASE, and Cochrane, a literature search for randomized controlled trials was performed. All the outcome variables were evaluated through a quantitative meta-analysis, and the influence of other clinical covariates were determined with a metaregression. For the survival outcomes, trial sequential analysis (TSA) was performed to adjust results for type I and II errors and to analyze the power of the available evidence.

RESULTS

After full-text reading, 12 studies were included in the analyses. No statistically significant difference was found after 3 years between the 2 study groups (P = 0.36). Short implants displayed fewer biological complications (P = 0.05), less marginal bone loss (MBL) from implant placement (P < 0.01), and reduced surgical time and treatment cost. However, long implants showed a statistically significant smaller number of prosthetic complications (P = 0.03). TSA confirmed the results of the meta-analysis, revealing that additional studies are needed due to low statistical power of the available evidence.

CONCLUSION

The placement of short implants is a predictable option in treating patients with maxillary atrophy up to a 3-year follow-up. Studies with a longer observational period are needed to study the long-term performance of these implants.

Maxillary Sinus Floor Augmentation With Autogenous Bone Graft From the Ascending Mandibular Ramus

PURPOSE

The objective of the present study was to assess patient satisfaction and esthetic implant outcome 10 years after maxillary sinus floor augmentation with autogenous bone graft from the mandibular ramus.

MATERIALS AND METHODS

Maxillary sinus floor augmentation with autogenous bone graft from the mandibular ramus was conducted in 48 consecutive patients from 2002 to 2006. Records and radiographs were retrospectively analyzed. Twenty-four patients including 34 sinus augmentation procedures and 37 implants were evaluated after 10 years. Subjective and professional evaluations of the final periimplant soft tissue, implant crown, and total implant treatment were conducted.

RESULTS

The 10-year survival of suprastructures and implants was 84% and 100%, respectively. The patients were highly satisfied with the esthetic and implant treatment outcome expressed by scores >90 on the visual analog scale. Most implants were characterized by scores of 1 or 2, resulting in a mean pink esthetic score of 9 (maximum 14) and a white esthetic score of 8 (maximum 10).

CONCLUSION

Maxillary sinus floor augmentation with autogenous bone graft is characterized by high long-term implant survival rate and patient satisfaction.

Long term follow-up of titanium implants installed in block-grafted areas: A systematic review

BACKGROUND

An enduring clinical question concerns the outcome (ie, success) of implants placed in areas grafted with block-grafts.

OBJECTIVE

To undertake a systematic review of the literature on the long term results (≥5 years) of implants placed in maxillofacial areas grafted with any type of osseous block-grafts in two-stage surgeries. Further, the review addresses how available success criteria were used within the studies.

MATERIALS AND METHODS

The MEDLINE (PubMed) and EMBASE bibliographic databases were searched up to March 2017 for studies evaluating the long term results of implants placed in grafted areas. The search strategy was restricted to English language publications using combined terms which referred to the treatment method (implants placed in areas grafted with bone blocks), and follow-up characteristics (≥5 years and assessment of at least one parameter related to implant success criteria). To qualify for inclusion, studies should present outcome measurements indicating the success (or at least the survival) of the implants.

RESULTS

The search strategy yielded 17 studies, which were included in this systematic review. These studies presented survival rates ranging from 88.7% (after 15 years follow-up) to 98.7% (after 5 years follow-up). Five studies presented data based on predefined success criteria with success rates ranging from 86.8% to 100%. In these studies, the term "success" was often not properly defined.

CONCLUSION

The long term survival (≥5 years) of implants placed into block-grafted areas in two-stage surgeries was not lower than 75%, while success rates ranged from 86.8% to 100%. Although it was possible to identify published success criteria for implant follow-up, there is no broad consensus on how to report implant success in a consistent manner.

Maxillary Sinus Floor Augmentation With Synthetic Bone Substitutes Compared With Other Grafting Materials: A Systematic Review and Meta-analysis

OBJECTIVE

To test the hypotheses of no differences in implant treatment outcome after maxillary sinus floor augmentation (MSFA) with synthetic bone substitutes (SBS) compared with other grafting materials applying the lateral window technique.

MATERIALS AND METHODS

A MEDLINE/PubMed, Embase and Cochrane Library search in combination with hand-search of selected journals was conducted.

RESULTS

Five randomized controlled trials with low risk of bias fulfilled the inclusion criteria. SBS disclosed high survival rate of suprastructures and implants with no significant differences compared to autogenous bone graft or xenograft. Meta-analysis revealed a patient-based implant survival rate of 0.98 (confidence interval: 0.89-1.08), indicating no differences between SBS and xenograft. SBS demonstrated significant less newly formed bone compared with autogenous bone graft, whereas no significant difference was revealed as compared to xenograft. High implant stability values, limited periimplant marginal bone loss, and few complications were reported with SBS.

CONCLUSIONS

There seem to be no differences in implant treatment outcome after MSFA with SBS compared to other grafting materials.

A prospective controlled trial comparing xenograft/autogenous bone and collagen-stabilized xenograft for maxillary sinus augmentation-Complications, patient-reported outcomes and volumetric analysis

OBJECTIVE

Compare maxillary sinus augmentation (MSA) using two different materials-anorganic bovine bone mineral (ABBM) + autogenous bone (AB) (control group) vs. collagen-stabilized ABBM (test group) in terms of complications, patient-reported outcome measures (PROMs) and volumetric analysis.

MATERIALS AND METHODS

Sixty patients underwent sinus augmentation (30 control + 30 test group). Intra- and postoperative complications were recorded. PROMs measured the impact of grafting on daily activities, pain and morbidity. CT scans were used to measure graft volume, ridge height, material selection and degree of contact of graft-to-surrounding sinus walls. Dental implant placement parameters were also recorded.

RESULTS

All complications were minor and did not prevent completion of the augmentation or subsequent implant placement. Schneiderian membrane perforation was the most frequently encountered complication. Both treatment groups reported moderate limitation in the 1st 48 hr post-surgery but little or none by day 3 or 4. Jaw opening, chewing and bruising were significantly higher in the control group. The impact on work and social life was moderate initially but reduced to little or none by the 2nd day. Mild to moderate pain and interference to daily activities were reported for the first 3 days requiring the use of NSAIDs only. A mean graft volume of 1.46 cm³ (±0.77) was calculated in the control group and 1.27 cm³ (±0.65) in the test group. Extent of contact between graft and surrounding sinus walls had a significant impact on bone volume. Shorter (8 mm) implants were utilized more frequently in the test group, which was also more likely to require additional vertical augmentation, but this was not statistically significant.

CONCLUSION

MSA using a lateral wall approach is safe and associated with mild to moderate pain and restrictions to daily activities for 48-72 hr. Patients' reports of morbidity were greater with autogenous bone harvesting. Collagen-stabilized ABBM provides comparable bone volume to AB + ABBM that is sufficient for placement of implants of adequate size with no need for further vertical augmentation. Engaging the surrounding sinus walls had a significant positive impact on graft volume.

Periosteal elevation induces supracortical peri-implant bone formation

PURPOSE

The aim of the study was to evaluate the possibility of supracortical peri-implant bone formation after periosteal elevation.

MATERIALS AND METHODS

Periosteal elevation with an elevation height of 5 or 10 mm was performed in an animal experiment with 24 female domestic pigs. For this purpose, four implants were inserted in the frontal bone of each animal. The implants protruded from the local bone by 5 or 10 mm. In the test groups, the periosteum was attached to the protruding implants. In the control groups, the implants were covered with biocompatible degradable periosteal-shielding devices. Each 8 animals were sacrificed after 20, 40 and 60 days. De novo bone formation was evaluated radiographically and histologically.

RESULTS

Bone formation rate was higher in the test groups compared to the control groups after 20, 40 and 60 days. After 40 and 60 days, a statistically significant higher (P < 0.01) bone formation rate was found for both elevation heights. The maximum height of the generated bone was statistically significantly higher (P < 0.01) in the test groups for both elevation heights, compared to the control groups for all time points investigated.

CONCLUSION

Periosteal elevation by dental implants is a treatment option for supracortical peri-implant bone formation.

Clinical efficacy of grafting materials in alveolar ridge augmentation: A systematic review

PURPOSE

To evaluate the efficacy of grafting materials in lateral and vertical ridge augmentations.

MATERIALS AND METHODS

A systematic review of the literature on the clinical use of grafting materials of the years 1995 to April 2015 was conducted using electronic search of PubMed and Cochrane libraries and hand search of eight print journals. A total of 184 papers were included, comprising 6182 patients. Parameters evaluated were observation period [months], bone formation [histologic area%], defect fill [%], horizontal and vertical gain [mm], loss of augmented volume [mm], complication rate [%], and implant survival rate [%]. Results are expressed as weighted means ± SD.

RESULTS

Results were obtained after a weighted mean observation period of 27.4 months (range 3-168 months). Bone formation in the augmented areas varied from 33.2 ± 14.9% for allogeneic grafts to 56.0 ± 25.6% for mixtures of autogenous and other grafting materials. Defect fill in dehiscence defects ranged from 51.0 ± 13.6% (synthetic) to 85.8 ± 13.4% (xenogeneic) for the different materials, with an overall weighted mean of 79.8 ± 18.7%. Weighted mean horizontal gain for all particulate grafting materials was 3.7 ± 1.2 mm, with variation between 2.2 ± 1.2 mm (synthetic) and 4.5 ± 1.0 mm (mixtures of autogenous bone with allogeneic/xenogeneic grafting material) without statistical significance. Weighted overall mean vertical gain was 3.7 ± 1.4 mm. Vertical gain was substantially higher when space-making barrier materials such as titanium meshes were used; however this was also associated with strong increase in complication rate. Block grafts achieved higher horizontal gain by approximately 1 mm. The use of block grafts achieved significantly increased vertical gain compared to particulate material only when autogenous block grafts from extraoral donor sites were used.

CONCLUSION

Horizontal and vertical gain by 3.7 mm on average can be achieved using particulate materials. This can be increased by using titanium meshes. Substantial vertical gains beyond this dimension require the use of extraoral bone block grafts.

Long-term outcomes of implants placed after vertical alveolar ridge augmentation in partially edentulous patients: a 10-year prospective clinical study

AIM

The aim of this study was to evaluate the long-term clinical results around non-submerged implants placed after vertical alveolar ridge augmentation.

MATERIAL AND METHODS

The original population consisted of two groups of partially edentulous patients (Clinical Oral Implants Research, 15, 2004, 73; Clinical Oral Implants Research, 18, 2007, 286), receiving a total of 82 implants, after a vertical bone augmentation of at least 4 mm. Following cementation of the fixed dental prostheses, patients were asked to follow an individualized supportive periodontal therapy (SPT) program for an appropriate clinical and radiographic follow-up.

RESULTS

At the 10-year examination, seven of the 41 patients were lost to follow-up. During SPT, additional antibiotic and/or surgical therapy was necessary in 18 implants, and four of these implants were removed for biological complications. The overall implant survival rate was 94.1%. The mean interproximal bone loss (BL) was 0.58 ± 0.57 mm.

CONCLUSIONS

The results of this study confirmed that implants, placed after vertical augmentation and followed by an adequate SPT, offer predictable long-term results. Nevertheless, patients whose bone atrophy was consequence of a previous history of periodontitis presented a statistically significant greater BL.

Conditioned medium from fresh and demineralized bone enhances osteoclastogenesis in murine bone marrow cultures

OBJECTIVES

Osteoclasts rapidly form on the surface of bone chips at augmentation sites. The underlying molecular mechanism, however, is unclear. Soluble factors released from bone chips in vitro have a robust impact on mesenchymal cell differentiation. Whether these soluble factors change the differentiation of hematopoietic cells into osteoclasts remains unknown.

METHODS

Osteoclastogenesis, the formation of tartrate-resistant acid phosphatase-positive multinucleated cells, was studied with murine bone marrow cultures exposed to RANKL and M-CSF, and conditioned medium from fresh (BCM) and demineralized bone matrix (DCM). Histochemical staining, gene and protein expression, as well as viability assays were performed.

RESULTS

This study shows that BCM had no impact on osteoclastogenesis. However, when BCM was heated to 85°C (BCMh), the number of tartrate-resistant acid phosphatase-positive multinucleated cells that developed in the presence of RANKL and M-CSF approximately doubled. In line with the histochemical observations, there was a trend that BCMh increased expression of osteoclast marker genes, in particular the transcription factor c-fos. The expression of c-fos was significantly reduced by the TGF-β receptor I antagonist SB431542. DCM significantly stimulated osteoclastogenesis, independent of thermal processing.

CONCLUSIONS

These data demonstrate that activated BCM by heat and DBM are able to stimulate osteoclastogenesis in vitro. These in vitro results support the notion that the resorption of autografts may be supported by as yet less defined paracrine mechanisms.

Anorganic bovine bone (ABB) vs. autologous bone (AB) plus ABB in maxillary sinus grafting. A prospective non-randomized clinical and histomorphometrical trial

OBJECTIVES

This investigation focused on histological characteristics and 5-year implant survival after sinus floor augmentation with anorganic bovine bone (ABB, Bio-Oss) and ABB plus autologous bone (AB) with a ratio of 1/1.

MATERIAL AND METHODS

Nineteen consecutive patients with bony atrophy of the posterior edentulous maxilla and a vertical bone height ≤4 mm were prospectively included in this study. In the first surgical stage, the maxillary sinus was non-randomized either augmented with ABB alone (n = 12) or a 1/1 mixture of ABB and AB (n = 7). After a mean healing period of 167 days, biopsies were harvested in the region of the grafted sinus with a trephine burr and implants were placed simultaneously, ABB n = 18 and ABB + AB n = 12. The samples were microradiographically and histomorphometrically analyzed judging the newly formed bone (bone volume, BV), residual bone substitute material volume (BSMV), and intertrabecular volume (soft tissue volume, ITV) in the region of the augmented maxillary sinus. Implant survival was retrospectively evaluated from patient's records.

RESULTS

No significant difference in residual bone substitute material (BSMV) in the ABB group (31.21 ± 7.74%) and the group with the mixture of ABB and AB (28.41 ± 8.43%) was histomorphologically determined. Concerning the de novo bone formation, also both groups showed statistically insignificant outcomes; ABB 26.02 ± 5.23% and ABB + AB 27.50 ± 6.31%. In all cases, implants were installed in the augmented sites with sufficient primary stability. After a mean time in function of 5 years and 2 months, implant survival was 93.75% in the ABB and 92.86% in the ABB + AB group with no statistically significant differences.

CONCLUSION

The usage of ABB plus AB to a 1/1 ratio leads to an amount of newly formed bone comparable with the solitary use of ABB after grafting of the maxillary sinus. Considering that ABB is a non-resorbable bone substitute, it can be hypothesized that this leads to stable bone over time and long-term implant success. Importantly, in the sole use of ABB, bone grafting and therefore donor site morbidities can be avoided.

Deproteinated bovine bone vs. beta-tricalcium phosphate as bone graft substitutes: histomorphometric longitudinal study in the rabbit cranial vault

OBJECTIVES

This article aims to study differences in the bone formation and the graft resorption of two bone graft substitutes (BGS). Besides, it is our attempt to observe possible qualitative and quantitative differences in the bone reparation of the outer layer covered by collagen membrane and the uncovered inner layer in close contact with dura mater.

MATERIAL AND METHODS

Twelve rabbits were employed. Deproteinized bovine bone (DBB) and β-tricalcium phosphate (BTCP) were used as BGS. Four subcritical round defects (7 mm) were drilled in the cranial vault, removing both cortical walls. One of the holes was filled with DBB, and other was filled with BTCP. Each symmetrical position to DBB and BTCP was left empty. The whole defect set was covered with a collagen membrane. Histological and morphometric analysis was performed for 1, 4, 8, 16, 32 and 52 weeks. Morphometry measurements were carried out taking into account the whole defect and splitting inner and outer areas.

RESULTS

In DBB sites, a rapid bone growth is observed, linking the remaining particles and integrating them into the bone matrix. Permanence of these DBB particles from week 16 onwards restrains the growth of bone fraction. A greater bone growth appears in areas repaired with BTCP than in those repaired with DBB, both in the outer layer (under-membrane) and the inner layer (over dura mater). In DBB sites, a slower growth is observed in the inner layer, with no significant differences in the final bone fraction at both strata.

CONCLUSIONS

Both materials favour the closure of the defects provoked. In both cases, a synergistic effect with the collagen membrane is observed. DBB remains integrated in the bone matrix, while BTCP displays a pattern of highly developed progressive resorption with an outstanding bone fraction development.