Localized ridge augmentation with allogenic block grafts prior to implant placement: case reports and histologic evaluations

Implant Site Changes in Three Different Clinical Approaches: Orthodontic Extrusion, Regenerative Surgery and Spontaneous Healing after Extraction: A Systematic Review

Both surgical and non-surgical techniques are employed for implant site development. However, the efficacy of these methods has not been thoroughly evaluated and compared. This systematic review aims to compare the biologic, functional and esthetic outcomes of three different approaches before implant placement in both the maxillary and mandibular arches: orthodontic extrusion, regenerative surgery and spontaneous healing after extraction. The systematic research of articles was conducted up to January 2020 in Medline, Scopus and the Cochrane Library databases. Studies were selected in a three-stage process according to the title, the abstract and the inclusion criteria. The methodological quality and the risk of bias of the included studies were evaluated using ROBINS-I tools for non-randomized studies, Rob 2.0 for RCT. Quality evaluation of case reports was performed using CARE guidelines. Through the digital search, 1607 articles were identified, and 25 of them were included in the systematic review. The qualitative evaluation showed a good methodological quality for RCT, sufficient for non-randomized studies and poor for case reports. Based on the available results, both orthodontic extrusion and regenerative surgery allowed the development of the implant site with satisfying esthetic and functional outcomes. Studies about the spontaneous healing of the extraction socket showed resorption of the edentulous ridge, which complicated the implant insertion. No study referred to failures or severe complications. Most of the studies reported only qualitative results. The present systematic review demonstrated that there is a substantial lack of data and evidence to determine which of the presented methods is better for developing a future implant site. Both surgical and non-surgical procedures appear effective in the regeneration of hard tissue, whereas not all the techniques can improve soft tissue volume, too. The orthodontic technique simultaneously enhances both hard and soft tissue.

Customized 3D printed nanohydroxyapatite bone block grafts for implant sites: a case series

PATIENTS

A case series of 12 patients (mean age, 53.5 years) with horizontal ridge deficiencies had augmentations with customized 3D printed nanohydroxyapatite (3DHA) block grafts prior to implant placement. 3DHA graft materials were fabricated to fit the individual patient defects using DICOMs from CBCT images obtained from each patient. The CBCT images were then converted into the STL file format and 3DHA was reconstructed by 3D printing. Surgical bone augmentation consisted of 3DHA incorporating concentrated growth factors (CGFs) and platelet-rich fibrin (PRF) membrane. At 6 months, a bone biopsy and implantation were performed. The primary outcome was horizontal bone gain after 6 months. The secondary outcomes included information on the clinical outcomes, dimensions, and histomorphometric results.

DISCUSSION

The 3DHA block graft was successful in 10 of 12 patients. Graft adjustment was not required. All 3DHA adapted and fit well at all defect sites. Maximum mean horizontal bone gains were 3.06 ± 1.02 and 3.56 ± 0.23 mm from the DICOMs and STL data sets, respectively. The volume gain was 229.8 ± 82.96 mm³. A low pain score after surgery was reported of 1.41 ± 0.51, while the healing index score increased with a maximum mean of 4.7 ± 0.67. Thirteen implants were placed with good primary stability (ISQ = 65 ± 4.08), without additional guided bone regeneration. Histomorphometric analysis revealed that new bone formation, bone tissue, residual grafts, and connective tissue were 28.6 ± 1.88, 30.48 ± 4.81, 19.82 ± 4.07, and 20.81 ± 4.41%, respectively.

CONCLUSIONS

A customized 3DHA block graft is a viable treatment option for primary implant-site augmentation.

Bone-implant-contact and new bone formation around implants placed in FDB blocks compared to placement at the adjunction of particulate FDB

BACKGROUND

The efficacy of human freeze-dried bone (h-FDB) as particulate vs block forms as a proper onlay augmented bone graft material to accommodate implants is undetermined.

PURPOSE

To evaluate osseointegration and new bone formation at implants placed in FDB blocks (BL group) and those at the adjunction of particulate FDB (PR group).

MATERIALS AND METHODS

Twelve pairs of h-FDB blocks were stabilized bilaterally to the calvaria of 12 rabbits. Twenty-four SLA implants were placed at the remodeled grafted blocks, 4 months later. A circumferential gap was created around one implant in each pair and packed with particulate h-FDB. Section biopsies were obtained at 2-month post implant placement (6 months post-block grafting). Bone-to-implant contact (BIC) and bone-area fraction (BAF) were histomorphometrically calculated.

RESULTS

The mean BIC was 34.4% and 33.5% for the BL and PR groups, respectively. The mean BAF was 23.9% and 26.4% for the corresponding groups, respectively. Osseointegration and newly formed bone were evident mostly between the threaded portions of the implants in proximity to the host rabbit calvaria compared to its cervical neck.

CONCLUSION

The particulate and the cancellous block h-FDB forms yielded similar BIC and BAF outcome. Full revascularization/revitalization is questioned.

Acellular mineralized allogenic block bone graft does not remodel during the 10 weeks following concurrent implant placement in a rabbit femoral model

OBJECTIVES

Due to bone loss, endosseous implants often require addition of a bone graft to support adequate primary fixation, bone regeneration, and osseointegration. The aim of this study was to compare effectiveness of autogenic and allogenic bone grafts when used during simultaneous insertion of the implant.

MATERIALS AND METHODS

4-mm-diameter rabbit diaphyseal bone autografts or allografts (n = 16/group) with a 3.2-mm pre-drilled hole in the center were placed into a 4 mm defect in the proximal femur of 3.5 kg male New Zealand White rabbits. Machined 3.2 × 10 mm grit-blasted, acid-etched titanium-aluminum-vanadium (Ti6Al4V) implants were placed. Control implants were placed into progressively drilled 3.2-mm holes in the contralateral limbs. Post-insertion day 70, samples were analyzed by micro-CT and calcified histology, or by mechanical torque and push-out testing followed by decalcified histology.

RESULTS

Both grafts were integrated with the native bone. Micro-CT showed less bone volume (BV) and bone volume/total volume (BV/TV) in the allograft group, but histology showed no differences in BV or BV/TV between groups. Allograft lacked living cells, whereas autograft was cellularized. No difference was found in maximum removal torque between groups. Compressive loading at the graft-to-bone interface was significantly lower in allograft compared with autograft groups.

CONCLUSIONS

There was less bone in contact with the implant and significantly less maximum compressive load in the allograft group compared with autograft. The allograft remained acellular as demonstrated by empty lacunae. Taken together, block allograft implanted simultaneously with an implant produces a poorer quality bone compared with autograft.

Human Bone Marrow-Derived Mesenchymal Stromal Cell-Seeded Bone Biomaterial Directs Fast and Superior Mandibular Bone Augmentation in Rats

Atrophic maxillary ridges present a challenge in the field of oral implantology. Autologous bone is still considered the gold standard grafting material, but the increased morbidity and surgical complications represent a major drawback for its use. The aim of this study was to assess the efficacy of an off-the-shelf cell-seeded bone biomaterial for mandibular bone augmentation, compared to its acellular counterpart. We used a rat model to test the osteogenic properties of bone marrow-derived mesenchymal stromal cells (MSCs)-seeded bone microparticles compared to acellular bone microparticles alone. Rats were euthanized at 4 and 8 weeks, and results analyzed using micro-CT imaging, histology (H&E, Masson’s Trichrome), histomorphometry and immunohistology (Tartrate-Resistant Acid Phosphatase-TRAP, Osteocalcin and human specific anti-mitochondria antibodies). Micro-CT analysis demonstrated that the cell-seeded biomaterial achieved significantly more bone volume formation at 4 weeks (22.75 ± 2.25 mm³ vs 12.34 ± 2.91 mm³, p = 0.016) and at 8 weeks (64.95 ± 5.41 mm³ vs 42.73 ± 10.58 mm³, p = 0.029), compared to the acellular bone microparticles. Histology confirmed that the cell-seeded biomaterial was almost completely substituted at 8 weeks, in opposition to the acellular biomaterial group. Immunohistochemical analysis showed a significantly higher number of TRAP and Osteocalcin positive cells at 4 weeks in the cell-seeded group compared to the acellular group, thereby demonstrating a higher rate of bone remodeling in the presence of MSCs. The grafted human cells remained viable and were detected up to at least 8 weeks, as observed using the human specific anti-mitochondria antibody. This off-the-shelf material available in unlimited quantities could therefore represent a significant advance in the field of mandibular bone augmentation by providing a larger volume of new bone formation in a shorter time.

Comparison of allogeneic and autogenous bone grafts for augmentation of alveolar ridge defects-A 12-month retrospective radiographic evaluation

OBJECTIVES

The aim of this study was to compare three-dimensional alterations following the use of autogenous versus allogeneic onlay grafts for augmentation at single tooth defects.

MATERIALS AND METHODS

Alveolar bone width at specific implant sites were assessed using sagittal and cross-sectional CBCT images prior grafting and at three subsequent time points. Twenty-one patients received autogenous bone blocks harvested from the retromolar region and another 21 patients received freeze-dried cancellous allogeneic bone blocks.

RESULTS

The vertical and horizontal dimensions did not significantly differ between autogenous and allogeneic bone grafts at any time point. In addition, there were no statistically significant differences in graft remodeling rates between autogenous (mean shrinkage rate after 12 months: 12.5% ± 7.8%) and allogeneic onlay grafts (mean shrinkage rate after 12 months: 14.4% ± 9.8%).

CONCLUSIONS

Freeze-dried cancellous allogeneic bone blocks showed equivalent volumetric shrinkage rates as autogenous bone blocks when used for treating circumscribed bone defects classified as Type-II to Type-IV according to the ITI-treatment guide categories. Therefore, it is not necessary to over-contour the alveolar ridge when using allogeneic blocks for treating single tooth defects, but to apply the same procedure as when using autogenous blocks.

Comparison of autogenous and allograft bone rings in surgically created vertical bone defects around implants in a sheep model

OBJECTIVES

The aim of this study was to compare autogenous and allograft bone rings in surgically created vertical bone defects.

MATERIAL AND METHODS

Four male, 1-year-old sheep were used in this study. In each sheep, eight vertical bone defects 7 mm in diameter were created using trephine drill in the iliac wing. Autogenous and allograft bone rings 5 mm in height and 7 mm in diameter were used for vertical augmentation around implants. The study consisted of four groups according to the bone ring type and amount of vertical augmentation, autogenous 2 mm, allograft 2 mm, autogenous 4 mm, and allograft 4 mm. Two of the animals were sacrificed after 4 months, and the remaining two animals were sacrificed after 8 months. Undecalcified sections were prepared from harvested samples. Histological assessment and histomorphometric analysis were performed.

RESULTS

Autogenous 2 mm group showed higher values than allograft 2 mm group, and autogenous 4 mm group showed higher values than allograft 4 mm group in terms of bone area and bone-to-implant contact (BIC) after 4 months. However, allograft 2 mm group showed higher bone area and BIC values than autogenous 2 mm group after 8 months. Also, autogenous 4 mm and allograft 4 mm groups showed comparable results after 8 months. Allograft 2 mm and allograft 4 mm groups showed higher bone area and BIC values at 8 months compared with 4 months.

CONCLUSIONS

Allograft bone ring looks promising in augmentation of surgically created vertical bone defects around implants after 8 months of healing.

Injectable, compression-resistant polymer/ceramic composite bone grafts promote lateral ridge augmentation without protective mesh in a canine model

OBJECTIVE

The objective of this study was to test the hypothesis that a compression-resistant bone graft augmented with recombinant human morphogenetic protein-2 (rhBMP-2) will promote lateral ridge augmentation without the use of protective mesh in a canine model.

MATERIALS & METHODS

Compression-resistant (CR) bone grafts were evaluated in a canine model of lateral ridge augmentation. Bilateral, right trapezoidal prism-shaped defects (13-14 mm long × 8-9 mm wide × 3-4 mm deep at the base) in 13 hounds (two defects per hound) were treated with one of four groups: (i) absorbable collagen sponge + 400 μg rhBMP-2/ml (ACS, clinical control) protected by titanium mesh, (ii) CR without rhBMP-2 (CR, negative control), (iii) CR + 200 μg rhBMP-2 (CR-L), or (iv) CR + 400 μg rhBMP-2 (CR-H). All animals were euthanized after 16 weeks. Ridge height and width and new bone formation were assessed by μCT, histology, and histomorphometry. The release kinetics of rhBMP-2 from CR bone grafts in vitro and in vivo in a femoral condyle defect model in rabbits was also evaluated.

RESULTS

All four bone grafts promoted new bone formation (11-31.6 volume%) in the lateral ridge defects. For CR grafts, ridge height and width increased in a dose-responsive manner with increasing rhBMP-2 concentration. Ridge height and width measured for CR-H without the use of protective mesh was comparable to that measured for ACS with a protective mesh.

CONCLUSIONS

At the same dose of rhBMP-2, an injectable, compression-resistant bone graft resulted in a comparable volume of new bone formation with the clinical control (ACS). These findings highlight the potential of compression-resistant bone grafts without the use of protective mesh for lateral ridge augmentation.

Clinical and histological evaluation of increase in the residual ridge width using mineralized corticocancellous block allografts: A pilot study

Background. Lateral ridge augmentation is conventionally accomplished by means of autogenous bone grafts. However, due to its complications, the application of autogenous bone graft substitutes, e.g. mineralized corticocancellous allograft, is ecommended. Methods. In the present study, twelve patients were included, with insufficient alveolar ridge widths in the designated sites for dental implant placement. During the primary surgery, mineralized corticocancellous block allografts were fixed in deficient sites with titanium screws and resorbable collagen membranes were used to cover the blocks. After a period of six months, a flap was raised and variations in ridge width values was measured. Finally, a micro-biopsy was obtained from the sites for histologic investigation prior to preparing them for subsequent implant placement. Results. All the applied blocks were incorporated into the underlying bone except for one. A statistically significant difference was seen between the average ridge widths before placing the allografts compared with that of implant placement stage (2.62±1.02 mm vs. 7.75±1.63 mm, respectively). Vital bone tissue was detected in all the histological specimens obtained from the interface of blocks and the underlying bone. Conclusion. The results suggest that mineralized corticocancellous block allografts might be used as scaffolds for bone growth and ridge width augmentation.

Long-term Retrospective Study of Implants Placed after Sinus Floor Augmentation with Fresh-frozen homologous block

Aim:

The aim of this study was to analyze and follow-up implants placed in the posterior maxillary regions previously grafted with homologous bone.

Materials and Methods:

Forty-one grafts with homologous bone blocks were performed in maxillary sinuses, and 121 implants were placed in premolar and molar regions approximately 6 months after the grafts. Patients were followed up for periods varying from 12 to 124 months after rehabilitation.

Results:

The results showed two implant failures, for a 98.3% success rate during the follow-up period.

Discussion:

The implants placed had an average torque of 40 N-cm, regardless of the, design, diameter, and length of the implants used.

Conclusion:

After following up on the implants placed in this study, we concluded that those placed in regions of the maxillary sinuses previously grafted with homologous bone blocks had high long-term success rates and met the functional masticatory requirements.

Potential of autogenous or fresh-frozen allogeneic bone block grafts for bone remodelling: a histological, histometrical, and immunohistochemical analysis in rabbits

Our aim was to compare the wound healing of autogenous bone grafts with that of fresh-frozen allogeneic block bone in rabbits. We used 25 animals. One was killed before the experiment to provide the allogeneic bone, and the remainder were killed at four time points (n=6 in each group). On histometrical analysis there was a significant difference between the two groups only at 45days and between 15 and 45days in the intergroup analysis. However, there was significantly more revascularisation (p<0.05), resorption (p<0.05), and bony replacement (p<0.05) in the autogenous group in the immunohistochemical analysis. In later periods, the autogenous bone was replaced by newly-formed bone in all samples, whereas it was always possible to find regions of devitalised bone in the fresh-frozen allogeneic bone grafts. Autogenous grafts were completely replaced whereas, in the fresh- frozen allogeneic grafts, we found acellular tissue that had been incorporated into the receptor bed interface during the later evaluation times.

Effect of Resorbable Collagen Plug on Bone Regeneration in Rat Critical-Size Defect Model

OBJECTIVE

The purpose of this investigation was to examine the effect of resorbable collagen plug (RCP) on bone regeneration in rat calvarial critical-size defects.

METHODS

About 5-mm-diameter calvarial defects were created in forty 12-week-old male Sprague-Dawley rats and implanted with or without RCP. Animals were killed at 1, 2, 4, and 8 weeks postoperatively. After being killed, specimens were collected and subjected to micro-computed tomography (μCT) and histological analysis.

RESULTS

The μCT showed a significant increase of newly formed bone volume/tissue volume in RCP-implanted defect compared with controls at all designated time points. After 8 weeks, the defects implanted with RCP displayed almost complete closure. Hematoxylin and eosin staining of the decalcified sections confirmed these observations and evidenced active bone regeneration in the RCP group. In addition, Masson's trichrome staining demonstrated that RCP implantation accelerated the process of collagen maturation.

CONCLUSIONS

The RCP enhances bone regeneration in rat critical-size cranial defects, which suggest it might be a desired material for bone defect repair.

Guided "sandwich" technique: a novel surgical approach for safe osteotomies in the treatment of vertical bone defects in the posterior atrophic mandible: a case report

PURPOSE

A novel technique to perform safe osteotomies during inlay block regenerative procedures in the posterior atrophic mandible is described.

MATERIAL AND METHODS

A 52-year-old male patient with vertical atrophy of the left posterior mandible was treated adopting an inlay block "sandwich" technique using an allogenic cancelous block and a mixture of mineralized and demineralized human bone allograft in putty form as graft. The horizontal osteotomy for the lifting of the osteotomized bone segment was performed using a template prepared from a virtual anatomical replica of the patient's mandible obtained from cone beam computed tomography data. In the second surgical phase, 3 months after the augmentation, 2 implants were easily placed.

RESULTS

The horizontal osteotomy was carried out, with no risk, very close to the nerve structures after the precise osteotomy line established preoperatively on the three-dimensional computed tomography (3D-CT) virtual reconstruction. No neurological complications were observed in the first days after the procedure, and no subsequent problems were recorded during the 3-month healing period.

CONCLUSION

Radiographic evaluations and complication-free clinical healing demonstrate the effectiveness of this technique to obtain safe and precise osteotomies.

Success rate of implants placed in autogenous bone blocks versus allogenic bone blocks: A systematic literature review

The aim of this study is to review and compare survival/success rate of dental implants inserted in autogenous and allogenic bone blocks (ALBs). A PubMed search was performed from January 1990 to June 2014 limited to English language and human studies. Studies that reported treatment outcome of implants inserted in augmented alveolar ridges with autogenous or ALBs were included. Primary search identified 470 studies. For autogenous bone block (ABB) 36 articles and for ALB 23 articles met the inclusion criteria. Evidence on implant survival/success rate of both techniques was limited to observational studies with relatively small sample sizes. Study design, treatment methods, follow-ups, defect location, and morphology varied among studies. The range of implant survival and success rates in ABB was from 73.8% to 100% and 72.8% to 100%, respectively. The corresponding numbers for ALB were 95.3-100% and 93.7-100%, respectively. A definite conclusion could not be reached. Future studies with long-term follow-ups are required to further elucidate this issue.

Stem cells: Sources, and regenerative therapies in dental research and practice

Stem cells are considered to be among the principle scientific breakthroughs of the twentieth century for the future of medicine, and considered to be an important weapon to fight against diseases, particularly those that have resisted the efforts of science for a long time. Human dental tissues have limited potentials to regenerate but the discovery of dental stem cells have developed new and surprising scenario in regenerative dentistry. Stem cell treatments are one example of the possibility using adult cells sourced from patients’ own bodies’ means that it can be expected that in the near future such treatments may become routine at dental practices. The hope is that it will become possible to regenerate bone and dental tissues including the periodontal ligament, dental pulp and enamel, and that the creation of new teeth may also become feasible. In view of this possibility of achieving restoration with regenerative medicine, it can be considered that a new era of dentistry is beginning. Thus the aim of this review is to give dental professionals a brief overview of different stem cells sources and the latest findings and their implications for improving oral health and treating certain conditions of the human mouth and face.

Effectiveness of biphasic calcium phosphate block bone substitutes processed using a modified extrusion method in rabbit calvarial defects

PURPOSE

This study evaluated the mechanical and structural properties of biphasic calcium phosphate (BCP) blocks processed using a modified extrusion method, and assessed their in vivo effectiveness using a rabbit calvarial defect model.

METHODS

BCP blocks with three distinct ratios of hydroxyapatite (HA):tricalcium phosphate (TCP) were produced using a modified extrusion method:HA8 (8%:92%), HA48 (48%:52%), and HA80 (80%:20%). The blocks were examined using scanning electron microscopy, X-ray diffractometry, and a universal test machine. Four circular defects 8 mm in diameter were made in 12 rabbits. One defect in each animal served as a control, and the other three defects received the BCP blocks. The rabbits were sacrificed at either two weeks (n=6) or eight weeks (n=6) postoperatively.

RESULTS

The pore size, porosity, and compressive strength of the three types of bone block were 140-170 µm, >70%, and 4-9 MPa, respectively. Histologic and histomorphometric observations revealed that the augmented space was well maintained, but limited bone formation was observed around the defect base and defect margins. No significant differences were found in the amount of new bone formation, graft material resorption, or bone infiltration among the three types of BCP block at either of the postoperative healing points.

CONCLUSIONS

Block bone substitutes with three distinct compositions (i.e., HA:TCP ratios) processed by a modified extrusion method exhibited limited osteoconductive potency, but excellent space-maintaining capability. Further investigations are required to improve the processing method.

Horizontal Resorption of Fresh-Frozen Corticocancellous Bone Blocks in the Reconstruction of the Atrophic Maxilla at 5 Months

Background

Reliable implant-supported rehabilitation of an alveolar ridge needs sufficient volume of bone. In order to achieve a prosthetic-driven positioning, bone graft techniques may be required.

Purpose

This prospective cohort study aims to clinically evaluate the amount of resorption of corticocancellous fresh-frozen allografts bone blocks used in the reconstruction of the severe atrophic maxilla.

Materials and Methods

Twenty-two partial and totally edentulous patients underwent bone augmentation procedures with fresh-frozen allogenous blocks from the iliac crest under local anesthesia. Implants were inserted into the grafted sites after a healing period of 5 months. Final fixed prosthesis was delivered ± 4 months later. Ridge width analysis and measurements were performed with a caliper before and after grafting and at implant insertion. Bone biopsies were performed in 16 patients.

Results

A total of 98 onlay block allografts were used in 22 patients with an initial mean alveolar ridge width of 3.41 ± 1.36 mm. Early exposure of blocks was observed in four situations and one of these completely resorbed. Mean horizontal bone gain was 3.63 ± 1.28 mm (p < .01). Mean buccal bone resorption between allograph placement and the reopening stage was 0.49 ± 0.54 mm, meaning approximately 7.1% (95% confidence interval: [5.6%, 8.6%]) of total ridge width loss during the integration period. One hundred thirty dental implants were placed with good primary stability (≥ 30 Ncm). Four implants presented early failure before the prosthetic delivery (96.7% implant survival). All patients were successfully rehabilitated. Histomorphometric analysis revealed 20.9 ± 5.8% of vital bone in close contact to the remaining grafted bone. A positive strong correlation (adjusted R² = 0.44, p = .003) was found between healing time and vital bone percentage.

Conclusions

Augmentation procedures performed using fresh-frozen allografts from the iliac crest are a suitable alternative in the reconstruction of the atrophic maxilla with low resorption rate at 5 months, allowing proper stability of dental implants followed by fixed prosthetic rehabilitation.

Block allograft for reconstruction of alveolar bone ridge in implantology: a systematic review

PURPOSE

The aim of this study was to evaluate the literature regarding clinical efficacy and predictability of block allograft for restoration of vertical and/or horizontal bone defects.

MATERIALS AND METHODS

A literature search was conducted in PubMed/MEDLINE and Cochrane databases about studies reporting the use of block allografts. The review included studies published in English from 1960 to 2011 and excluded single-case reports and articles that did not use block allograft stabilized by fixation screws.

RESULTS

The search revealed 567 articles, but only 14 were included, which were conducted in humans with a total of 194 patients treated with block allografts, totalizing 253 blocks.

CONCLUSIONS

Although a high success rate has been reported for the bone allograft survival, this systematic review demonstrated low level of scientific evidence articles with short follow-up time and diversified methodology with difficult possibilities to compare their results.

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.

Influence of Autologus Adipose Derived Stem Cells and PRP on Regeneration of Dehiscence-Type Defects in Alveolar Bone: A Comparative Histochemical and Histomorphometric Study in Dogs

BACKGROUND AND OBJECTIVES

Autogenous bone grafts is considered to be the best choice for reconstructive surgery. Adipose Derived Stromal Cells (ASCs) represents a promising tool for new clinical concepts in supporting cellular therapy. The goal of our study was to investigate bone regeneration following application of autologous ASCs with or without Platelet-Rich Plasma (PRP) at dehiscence-type defects in alveolar bone in dogs.

METHODS AND RESULTS

Standardized buccal dehiscence defects (4× 3×3 mm) were surgically created in eighteen dogs, the defects were grafted with either ASCs -PRP, ASCs alone, or without grafting material. Three months later; a bone core was harvested from grafted and non grafted sites for histological, histochemical and histomorphometric assessment. There was no evidence of inflammation or adverse tissue reaction with either treatment. Defects grafted with ASCs-PRP showed a significantly higher result (p≤ 0.05), with a mean area % of spongy bone and compact bone of (64.96±5.37 and 837.62±24.95), compared to ASCs alone (47.65±1.43 and 661.92±12.65) and without grafting (33.55± 1.74 and 290.85±7.27) respectively. The area % of lamellated bone increased significantly reaching its highest level in group A followed by group B. Also a significant increase in area % of neutral mucopolysaccharides and calcified reactivity of Masson|s Trichrome stain in groups A and B compared to group C was obtained.

CONCLUSIONS

Our results suggest that, the addition of PRP to ASCs enhances bone formation after 3 months and may be clinically effective in accelerating postsurgical healing in both periodontal and maxillofacial surgical applications.

Treatment of the atrophic upper jaw: rehabilitation of two complex cases

In reconstructive surgery, the fresh frozen homologous bone (FFB) represents a valid alternative to the autologous bone, because FFB allows bone regeneration thanks to its osteoinductive and osteoconductive properties. The purpose of this work is to describe the surgical-implant-prosthetic treatment of two complex cases using FFB. In particular, fresh frozen homologous bone grafts were used to correct the severe atrophy of the maxilla, and, then, once the graft integration was obtained, implant therapy was performed and implants placed in native bone were immediately loaded.

Repair of critical-size bone defects using bone marrow stromal cells: a histomorphometric study in rabbit calvaria. Part I: use of fresh bone marrow or bone marrow mononuclear fraction

OBJECTIVES

The aim of this study was to compare the bone healing observed after the use of (1) a scaffold enriched with fresh bone marrow, (2) a scaffold enriched with bone marrow mononuclear fraction, and (3) a scaffold alone.

MATERIAL AND METHODS

Twenty one rabbits were randomly divided into three groups of six animals and 1 group of 3 animals. Bilateral 12-mm diameter defects were created in the animals' parietal bones. In Control Group, the defects were filled with a xenograft alone (n = 6); in Group 1, with a xenograft enriched with fresh bone marrow (n = 6); in Group 2, with a xenograft enriched with bone marrow mononuclear fraction (n = 6) and in Unfilled Group, nothing was grafted (n = 3). In Groups 1, 2, and Control, one of the calvarial defects was randomly covered with a barrier membrane. The rabbits were sacrificed 8 weeks after surgery, and their parietal bones were harvested and analyzed histomorphometrically.

RESULTS

The histomorphometric analysis showed no difference between Group 1 and the Control Group regarding non-vital mineralized tissue area, but Group 2 showed a statistically significant higher percentage than the Control Group (P < 0.05) for both situations, with membrane (21.24 ± 3.78% and 13.52 ± 3.00%, respectively) and without membrane (20.91 ± 2.01% and 13.08 ± 1.72%, respectively). Group 2 showed the highest percentage of vital mineralized tissue area, followed by Group 1 and the Control Group (P < 0.05) for both situations, with membrane (28.17 ± 3.19%; 21.14 ± 7.38% and 13.06 ± 5.24%, respectively) and without membrane (21.13 ± 0.55%; 12.45 ± 6.34% and 6.56 ± 1.20%, respectively). Group 2 showed the lowest percentage of non-mineralized tissue area, followed by Group 1 and Control Group (P < 0.05) for both situations, with membrane (50.59 ± 6.64%; 58.75 ± 7.14% and 73.41 ± 6.87%, respectively) and without membrane (57.97 ± 1.91%; 71.74 ± 6.63% and 80.37 ± 2.67%, respectively). The sides in which the defects were covered with the barrier membrane showed better bone healing compared with the uncovered sides, in all groups (intragroup comparison, P < 0.05). The Unfilled Group specimens showed no bone formation.

CONCLUSIONS

Both methods using bone marrow stromal cells contributed to enhancing bone healing, especially that using the bone marrow mononuclear fraction. The use of a barrier membrane seemed to have a synergistic effect.

Full-arch vertical reconstruction of an extremely atrophic mandible with "box technique". A novel surgical procedure: a clinical and histologic case report

PURPOSE

To describe a new augmentation procedure named "box technique" for bone reconstruction in a severely atrophic jaw with mandibular and mental nerve dehiscence.

MATERIAL AND METHODS

The first surgical box technique procedure was performed to augment the atrophic posterior area. Simultaneously, 2 implants were inserted into the interforaminal zone to stabilize the denture. After 6 months, 2 implants were positioned in the regenerated bone, and a second box technique procedure was performed to reconstruct the ridge in the area of fixture exposition. Six months after the second surgery, the patient was rehabilitated with a removable prosthesis retained on 4 implants.

RESULTS

The clinical and histologic analyses highlighted outstanding healing resulting from this vertical and horizontal allografting and included complete resorption of poly D,L-lactide meshes and substitution of the mineralized human bone allograft with an excellent quality new bone formation.

CONCLUSIONS

Results confirm the effectiveness of the technique, which needs a further case series study endorsing its reliability.

The use of bovine screws to promote bone formation using a tibia model in dogs

The objective of this study was to evaluate the use of a unique resorbable bovine bone screw to stimulate bone formation. Bovine bone screws were inserted in the tibia of beagle dogs. Each animal received 8 screws, divided into groups A (screws + no membranes), B (screws + titanium reinforced membranes), and C (bone defects treated with autogenous bone grafts). Animals were killed at 2, 4, and 6 months. New bone was measured with a periodontal probe and reported an average of 7.4 mm in vertical bone gain for group B, 3.6 mm for group A, and 1.7 mm for group C. Submission to Kruskal-Wallis test showed statistical differences among groups (P < .05). Histologic examination revealed an intimate contact between the newly formed bone and the resorbing bone screws. We conclude that bovine bone screws provide an environment for new bone formation and thus may provide an alternative therapy for enhancing bone formation vertically, including for regenerative procedures as well as before implant therapy.

Histological results after maxillary sinus augmentation with Straumann® BoneCeramic, Bio-Oss®, Puros®, and autologous bone. A randomized controlled clinical trial

OBJECTIVE

This investigation focused on a comparison of clinical and histological characteristics after sinus floor augmentation with biphasic calcium phosphate (BCP, Straumann BoneCeramic(®) ), anorganic bovine bone (ABB, Geistlich Bio-Oss(®) ), mineralized cancellous bone allograft (MCBA, Zimmer Puros(®) ), or autologous bone (AB).

MATERIALS AND METHODS

Thirty consecutive patients with a posterior edentulous maxillary situation and a vertical bone height less than or equal to 4 mm were included in this study. A two-stage procedure was carried out. After augmentation of the maxillary sinus with ABB, BCP, MCBA, or AB followed by a healing period of 5 months, biopsies were taken with simultaneous implant placement. The samples were analyzed using microradiography and histology.

RESULTS

Ninety-four implants were placed in the augmented positions and 53 bone biopsies were taken and evaluated. The bone volume fraction of newly formed bone was measured as 30.28 ± 2.16% for BCP, 24.9 ± 5.67% for ABB, 41.74 ± 2.1% for AB, and 35.41 ± 2.78% for MCBA with significant increases in bone volume of AB vs. BCP and ABB, and MCBA vs. ABB samples. Significantly different residual bone substitute material was measured as 15.8 ± 2.1% in the BCP group and 21.36 ± 4.83% in the ABB group.

CONCLUSION

As it provides the highest rate of de novo bone formation, AB can be considered to remain the gold standard in sinus floor augmentation. All tested control materials showed comparable results and are suitable for maxillary sinus augmentation.

Bone grafting the mandible

Many bone grafting techniques have been used to reconstruct the partially dentate and edentulous mandible. This article discusses the various bone grafting techniques to reconstruct mandibular defects. Also included are issues such as whether autogenous bone is necessary for reconstruction of the mandibular ridge and the importance of membranes.

Bone grafting the mandible

Many bone grafting techniques have been used to reconstruct the partially dentate and edentulous mandible. This article discusses the various bone grafting techniques to reconstruct mandibular defects. Also included are issues such as whether autogenous bone is necessary for reconstruction of the mandibular ridge and the importance of membranes.

Rehabilitation of atrophic maxilla using the combination of autogenous and allogeneic bone grafts followed by protocol-type prosthesis

Currently, there are several techniques for the rehabilitation of atrophic maxillary ridges in literature. The grafting procedure using autogenous bone is considered ideal by many researchers, as it shows osteogenic capability and causes no antigenic reaction. However, this type of bone graft has some shortcomings, mainly the restricted availability of donor sites. In recent years, several alternatives have been investigated to supply the disadvantages of autogenous bone grafts. In such studies, allogeneic bone grafts, which are obtained from individuals with different genetic load, but from the same species, have been extensively used. They can be indicated in cases of arthroplasty, surgical knee reconstruction, large bone defects, and in oral and maxillofacial reconstruction. Besides showing great applicability and biocompatibility, this type of bone is available in unlimited quantities. On the other hand, allogeneic bone may have the disadvantage of transmitting infectious diseases. Atrophic maxillae can be treated with bone grafts followed by osseointegrated implants to obtain aesthetic and functional oral rehabilitation. This study aimed to show the viability of allogeneic bone grafting in an atrophic maxilla, followed by oral rehabilitation with dental implant and protocol-type prosthesis within a 3-year follow-up period by means of a clinical case report.

Fresh-Frozen Bone Allografts in Maxillary Ridge Augmentation: Histologic Analysis

Bone allograft has become an alternative to autogenous bone due to its decreased operative trauma and the almost unlimited supply of reconstructive material. The aim of the present study was to histologically evaluate the suitability of fresh-frozen bone graft (test group) used in maxillary ridge augmentation, comparing it to autogenous bone (native maxilla: control group). During the re-entry procedures, 9 months after the fresh-frozen allogeneic bone blocks were placed in the atrophic maxillary ridges, bone cores were removed with a trephine bur from test and control treatments in the same patient. Routine histologic processing using hematoxylin and eosin and Picrosirius staining was performed. Mature and immature collagen area and density analysis were carried out for both groups under polarization. The results of Student’s t test for paired samples (P &gt; .05) showed no statistically significant difference in mature and immature collagen area or density percentage between test and control groups. Histologically similar bone formation patterns were observed in both groups. We concluded that fresh-frozen bone allograft is a biologically acceptable alternative for augmentation of the deficient alveolar ridge, showing a similar collagen pattern to that of autogenous bone.

Placement of implant after bone graft using J block allograft

Securing sufficient alveolar bone is important for a successful implant. Alveolar bone should be augmented to adequate height and width for an implant to satisfy the functional, biological, and aesthetic properties. The subjects of this study were 3 patients with severe bone defects caused by either a periodontal disease or a failure of implants on mandibular posterior tooth, mandibular anterior tooth, and maxillary posterior tooth. The shape of the commercial block allograft (Puros J-Block, Zimmer Dental Inc., Carlsbad, CA) was modified to match the shape of the defect, and resorbable membrane (Puros Pericardium Allograft Membrane, Tutogen Medical GmbH, Germany) was used before suturing the soft tissue. The transplant sites were exposed 4 months later to install the implant. The grafted bone was united with the bone tissue to obtain enough alveolar ridge and to install the implants. Bone allograft used in these cases reduced the need to collect autogenous bone in patients with severe alveolar ridge loss.

A new tunnel technique with acellular dermal matrix for soft tissue preparation prior to symphyseal block graft--a description of technique and case report

The aim of this report was to describe a newly designed tunnel technique (A New Tunnel Technique) using acellular dermal matrix (ADM) allograft for soft tissue augmentation prior to mono-cortical block graft. Two cases with vertical and horizontal ridge deficiency in the mandibular anterior area were indicated for mono-cortical block grafting before implant placement. Soft tissue evaluation and measurements showed thin tissue covering the defect area composed mainly of nonkeratinized alveolar mucosa measuring 1 to 2 mm in most of the sites. Soft tissue augmentation was done first using a new tunnel technique with ADM allograft. After 2 months of healing, mono-cortical block graft was harvested from the mandibular symphysis area and fixed to the recipient site. Soft tissue measurements were made before soft tissue graft and immediately before block graft. Healing was evaluated at 2, 4, 12, and 24 weeks post-block grafting surgery to evaluate healing. In both cases, there was generalized 1- to 2-mm increase in soft tissue thickness covering the defect areas following allograft. Both cases had healed uneventfully with no soft tissue complications following block grafting procedure to the time of implant placement. The new tunnel technique for soft tissue augmentation using acellular dermal matrix allograft seems to be a valid approach in soft tissue preparation prior to mono-cortical block grafting. Further research is needed to evaluate if this procedure will help to prevent soft tissue complications associated with block grafting.