Prefabricated CAD-CAM scaffolds for management of oro-antral communication: A case report and histological analysis

INTRODUCTION

Oro-control communication is one of the complications associated with dental extraction and oral surgeries. This case report presents a minimally invasive surgical approach for bone regeneration at the site of oro-antral communication utilizing a prefabricated computer-aided design and computer-aided manufacturing (CAD-CAM) allogenic bone block.

METHODS

A 20-year-old healthy female, nonsmoker, with a badly destructed upper right first molar was referred for dental implant placement after extraction. Cone beam computerized tomography images revealed the presence of a large bone defect associated with oro-antral communication with the maxillary sinus and insufficient bone for dental implant placement. A prefabricated CAD-CAM allogenic bone scaffold was fabricated. After surgical exposure, the scaffold was secured in place and covered with a non-resorbable membrane. A dental implant was placed after 5 months, and a trephining biopsy was processed for histological evaluation.

RESULTS

Closure of the oro-antral communication was clinically observed. The average width of the alveolar bone was 12 mm, and the average height was 11 mm. Histological analysis at 5-month intervals showed thin newly formed bone trabeculae encircling remnants of graft material surrounded by osteoid tissue. The newly formed bone percentages were 32 ± 18% and 28 ± 17% volume remained after the biodegradation of the scaffold. Specific immune-histochemical staining by anti-vascular epithelial growth factor expression index value was 32.06%.

CONCLUSIONS

A prefabricated CAD-CAM scaffold was successfully used to seal a large oro-antral communication and regenerate sufficient bone to place a dental implant.

Allogeneic versus autogenous shell technique augmentation procedures: a prospective-observational clinical trial comparing surgical time and complication rates

OBJECTIVES

Autogenous and allogeneic blocks for shell augmentation of the jaw have shown comparable results. This observational clinical study aimed to compare both materials for shell augmentation concerning surgery time and intra- and postoperative complications.

MATERIAL AND METHODS

Bone augmentation with the shell technique using autogenous or allogenous bone was performed in 117 patients with segmental jaw atrophy. The primary study parameter was the surgical time, comparing both materials. Subsequently, intra- and postoperative complications were recorded.

RESULTS

Allogeneic (n = 60), autogenous (n = 52), or both materials (n = 5) were used. The use of allogeneic material led to a significantly shorter operation time (p < 0.001). A more experienced surgeon needed significantly less time than a less experienced surgeon (p < 0.001). An increasing number of bone shells (p < 0.001), an additional sinus floor elevation, and intraoperative complications also significantly increased the operation time (p = 0.001). Combining allogeneic and autogenous shells (p = 0.02) and simultaneous sinus floor elevation (p = 0.043) significantly impacted intraoperative complications. No correlations were found between the included variables for postoperative complications (all p > 0.05). In total, 229 implants were inserted after a healing time of 4-6 months, with a survival of 99.6% after a mean follow-up duration of 9 months.

CONCLUSIONS

Compared to the autogenous technique, allogeneic shell augmentation has a shorter surgical time and a similar rate of intra- and postoperative complications as autogenous bone. Together with its promising clinical results, this technique can be recommended.

Horizontal augmentation techniques in the mandible: a systematic review

Purpose

Placement of dental implants has evolved to be an advantageous treatment option for rehabilitation of the fully or partially edentulous mandible. In case of extensive horizontal bone resorption, the bone volume needs to be augmented prior to or during implant placement in order to obtain dental rehabilitation and maximize implant survival and success.

Methods

Our aim was to systematically review the available data on lateral augmentation techniques in the horizontally compromised mandible considering all grafting protocols using xenogeneic, synthetic, or allogeneic material. A computerized and manual literature search was performed for clinical studies (published January 1995 to March 2021).

Results

Eight studies ultimately met the inclusion criteria comprising a total of 276 procedures of xenogeneic, allogeneic, or autogenous bone graft applications in horizontal ridge defects. Particulate materials as well as bone blocks were used as grafts with a mean follow-up of 26.0 months across all included studies. Outcome measures, approaches and materials varied from study to study. A gain of horizontal bone width of the mandible with a mean of 4.8 mm was observed in seven of eight studies. All but one study, reported low bone graft failure rates of 4.4% in average.

Conclusions

Only limited data are available on the impact of different horizontal augmentation strategies in the mandible. The results show outcomes for xenogeneic as well as autologous bone materials for horizontal ridge augmentation of the lower jaw. The use of allogeneic bone-block grafts in combination with resorbable barrier membranes must be re-evaluated. Randomized controlled clinical trials are largely missing.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40729-022-00421-7.

Customized Allogeneic Bone Augmentation Improves Esthetic Outcome in Anteromaxillary Dental Implantation

Purpose

In cases of severe atrophic maxilla or maxillary involution, augmentation is necessary for implant-supported prosthetics. Using bone grafts is a standard procedure, and using customized allogeneic bone blocks may be a predictable alternative before dental implantation. Clinical Findings. This case study shows the digital workflow, including a preimplantological augmentation by a customized allogeneic block, followed by soft tissue optimization and template-based dental implantation, after six months of healing. It is part of a three-year follow-up study on the resorption rate of allogeneic bone blocks. Outcomes. Allogeneic bone augmentation is an alternative treatment option to autologous bone grafts. It allows predictable advanced backward planning (ABP) even in the maxillary esthetic zone. Diameter-reduced implants show long-term stability of a minimum of three years after loading and excellent results of prosthetic fixtures.

Conclusion

Prefabricated customized allogeneic blocks for augmentation may increase the fitting accuracy of the graft, decrease morbidity, and reduce the operation time in esthetic maxillary rehabilitation.

The role of cortical perforations in allogeneic block grafting for lateral augmentation in maxilla: A randomized clinical trial

BACKGROUND

The need of decortication on the recipient site remains unclear for bone regeneration. To our knowledge, there are no human clinical trials that studied the influence of decortication on cancellous allogeneic block grafting.

PURPOSE

The aim of the present study is to evaluate the influence of perforating the cortex of the recipient site on cancellous allogeneic block graft integration and revascularization in the maxilla.

MATERIAL AND METHODS

Twenty-six patients referred for lateral bone augmentation were included in this clinical trial. Patients received freeze-dried bone allograft cancellous blocks obtained from the iliac crest; cortical perforations of the recipient bed were performed in the test group while in the control group it was left intact. After a 4-month healing period another surgery was performed to place dental implants, and a bone biopsy was collected using a trephine. All samples underwent micro-CT scans, and were processed for histomorphometric and immunohistochemical analysis. Implant survival comparisons were made using a repeated measures analysis of variance (ANOVA) while all other variables were compared using the analysis of covariance (ANCOVA).

RESULTS

One hundred and nineteen implants were placed into 110 augmented sites. One hundred percent implant survival rate was reported during 24 months follow-up period. No differences were reported in bleeding on probing at 1 (5.6 vs 9%) and 2 years (13.2 vs 12.1%), probing pocket depth at 1 (3.4 ± 0.95 vs 3.6 ± 1.12 mm) and 2 years (3.8 ± 1.02 vs 4.1 ± 1.46 mm), and marginal bone loss at 1 (0.2 ± 0.52 vs 0.3 ± 0.57 mm) and 2 years (0.6 ± 0.91 vs 0.5 ± 0.87 mm). No statistically significant differences were found in the micro-CT and histomorphometric analysis in terms of newly formed bone (25.7 ± 11.2% vs 22.3 ± 9.7%), soft tissue (33.0 ± 14.7% vs 36.5 ± 15.7%), remnant allograft (39.3 ± 20.4% vs 41.2 ± 22.7%), and bone mineralization (57.2 ± 10.6% vs 53.8 ± 8.7%). Perforating the cortex of the recipient site had no significant effect on angiogenesis as shown by immunohistochemical analysis of CD34 positive blood vessels (39.21 ± 10.53/mm² vs 34.16 ± 12.67/mm² ).

CONCLUSION

Cancellous allogeneic bone block grafts are a clinically acceptable alternative for horizontal bone augmentation. Cortical perforations of the recipient site in the maxilla did not improve angiogenesis nor bone formation within the block graft.

Comparative Study of Biological Characteristics, and Osteoblast Differentiation of Mesenchymal Stem Cell Established from Camelus dromedarius Skeletal Muscle, Dermal Skin, and Adipose Tissues

Mesenchymal stem cells (MSCs) showed in vitro mesoderm-lineage differentiation and self-renewal capacity. However, no comparative study was reported on the biological characteristics of stem cells derived from skeletal muscle (SM-MSCs), dermal skin (DS-MSCs), and adipose tissues (A-MSCs) from a single donor in camels. The present study aimed to evaluate the influence of MSCs source on stem cell characteristics. We evaluated proliferation capacity and mesoderm-lineage differentiation potential from SM-MSCs, DS-MSCs, and A-MSCs. They showed spindle-like morphology after homogenization. The proliferation ability was not significantly difference in any of the groups. Furthermore, the portion of the cell cycle and expression of pluripotent markers (Oct4, Sox2, and Nanog) were similar in all cell lines at passage 3. The differentiation capacity of A-MSCs into adipocytes was significantly higher than that of SM-MSCs and DS-MSCs. However, the osteoblast differentiation capacity of A-MSCs was significantly lower than that of SM-MSCs and DS-MSCs. Additionally, after osteoblast differentiation, the alkaline phosphatase (ALP) activity and calcium content significantly decreased in A-MSCs compared to SM-MSCs and DS-MSCs. To the best of our knowledge, we primarily established MSCs from the single camel and demonstrated their comparative characteristics, including expression of pluripotent factors and proliferation, and in vitro differentiation capacity into adipocytes and osteoblasts.

Novel bone repairing scaffold consisting of bone morphogenetic Protein-2 and human Beta Defensin-3

Background

Synthetic biomaterials assist in modulating the vascular response in an injured bone by serving as delivery vehicles of pro-angiogenic molecules to the site of injury or by serving as mimetic platforms which offer support to cell growth and proliferation.

Methods

This study applied natural phospholipid modified protein technologies together with low temperature three-dimensional printing technology to develop a new model of three-dimensional artificial bone scaffold for potential use in repairing body injuries. The focus was to create a porous structure (PS) scaffold of two components, Bone Morphogenetic Protein-2 and Human Beta Defensin-3 (BMP2 and hBD3), which can synchronously realize directional bone induction, angiogenesis and postoperative antibacterial effects. BMP2 induces osteogenesis, whereas hBD3 is antibacterial.

Results

Our data showed that in the BMP2-hBD3-PS or hBD3-PS scaffolds, BMP2 had a slow-release rate of about 40% in 30 days, ensuring that BMP2 could penetrate into stem cells for osteogenic differentiation for a long time. The scaffolds promoted cell growth when in combination with BMP2, thus showing its importance in promoting cell growth. Alkaline Phosphatase (ALP) staining showed that the ALP content of BMP2-hBD3-PS and BMP2-PS had a significant increase in samples that contained BMP2, thus showing that these scaffolds promoted osteogenic differentiation. In all the constructs that had hBD3, they displayed antibacterial properties with hBD3, having a slow release of about 35% in 30 days, thus ensuring they provided protection.

Conclusion

Based on this study, the 3D printed BMP2 scaffolds show a great potential for the development of biodegradable bone implants.

Level of evidence

Level II, experimental comparative design.

The effect of synthetic bone graft substitutes on bone formation in rabbit calvarial defects

The aim of this study was to evaluate the influence of the intensity of the biomimetic hydroxyapatite (HA) coating of α-tricalcium phosphate (α-TCP) on biomaterial degradation and bone formation. Twenty-four female NZW rabbits of approximately 12 weeks of age were used. Critical size defects were randomly treated with 3%:97% HA:α-TCP (BBCP1), 12%:88% HA:α-TCP (BBCP2), and 23%:77% HA:α-TCP (BBCP3), respectively or sham. All defects were covered with a resorbable collagen membrane. Animals were euthanized after 3 and 12 weeks of healing and samples were investigated by micro-CT and histologic analysis. Ingrowth of newly formed woven bone from the original bone at 3-week healing period was observed in all samples. At the 12-week healing period, the new bone in the peripheral area was mainly lamellar and in the central region composed of both woven and lamellar bone. New bony tissue was found on the surface of all three types of granules and at the interior of the BBCP1 granules. Samples with 3% HA showed significantly less residual biomaterial in comparison to the other two groups. Furthermore, BBCP1 significantly promoted new bone area as compared to other three groups and more bone volume as compared to the control. Within its limitations, this study indicated the highest degradation rate in case of BBCP1 concomitant with the highest rate of bone formation. Hence, formation of new bone can be affected by the level of biomimetic HA coating of α-TCP.

High Potential of Bacterial Adhesion on Block Bone Graft Materials

Bone graft infections represent a challenge in daily clinics, resulting in increased patient discomfort and graft removal. The aim of this study was to investigate the initial adhesion of five representative pathogens on three different block bone graft materials (xenogeneic, alloplastic and allogeneic) and to assess if chlorhexidine (CHX) can effectively control the initial bacterial adhesion. Three different block bone grafting materials (Tutobone®, Endobon® and human spongiosa) were incubated with Escherichia coli, Staphylococcus aureus, Streptococcus mutans, Enterococcus faecalis and Pseudomonas aeruginosa in the presence or absence of 0.2% CHX solution. Bacterial adhesion was assessed by the direct counting of the colony-forming units (CFUs) and visualized by scanning electron microscopy (SEM). Overall, the selected bacterial species adhered successfully to all tested bone replacement scaffolds, which showed similar bacterial counts. The lg CFU values ranged from 5.29 ± 0.14 to 5.48 ± 0.72 for E. coli, from 4.37 ± 0.62 to 5.02 ± 0.48 for S. aureus, from 4.92 ± 0.34 to 4.95 ± 0.21 for S. mutans, from 4.97 ± 0.40 to 5.22 ± 0.13 for E. faecalis and from 4.23 ± 0.54 to 4.58 ± 0.26 for P. aeruginosa. CHX did not interfere with initial microbial adhesion, and yet it killed all adhered bacterial cells. Thus, CHX can be used to prevent subsequent biofilm infections.

Horizontal Alveolar Ridge Augmentation with Allogeneic Bone Block Graft Compared with Autogenous Bone Block Graft: a Systematic Review

Objectives

The objective of the present systematic review was to test the hypothesis of no difference in implant treatment outcome after horizontal ridge augmentation with allogeneic bone block compared with autogenous bone block.

Material and Methods

A MEDLINE (PubMed), Embase and Cochrane Library search in combination with a hand-search of relevant journals was conducted including human studies published in English through March 13, 2019. Comparative and non-comparative studies evaluating horizontal ridge augmentation with allogeneic bone block were included. Cochrane risk of bias tool and Newcastle-Ottawa Scale were used to evaluate risk of bias.

Results

One comparative study with high quality and 12 non-comparative studies fulfilled the inclusion criteria. Considerable heterogeneity prevented meta-analysis from being performed. The comparative retrospective short-term study demonstrated no significant difference in implant treatment outcome between the two treatment modalities. Non-comparative long-term studies revealed high implant survival, gain in alveolar ridge width and bone regeneration with allogeneic bone block. However, non-comparative studies disclosed high incidence of complications including dehiscence, exposure of allogeneic bone block and partial or total loss of the grafts.

Conclusions

There seemed to be no difference in implant treatment outcome after horizontal ridge augmentation with allogeneic bone block compared with autogenous bone block. However, increased risk of complications was frequently reported with allogeneic bone block.

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.

Clinical and radiographic outcomes of allogeneic block grafts for maxillary lateral ridge augmentation: A randomized clinical trial

BACKGROUND

A main drawback of bone block graft surgery is the resorption occurring in early stages of healing. To our knowledge, there are no studies comparing outcomes of freeze-dried bone allograft (FDBA) blocks with different architecture.

PURPOSE

The aim of this work was to investigate different factors that can affect graft resorption and to compare the resorption rates of two different types of allogeneic blocks, corticocancellous and cancellous.

MATERIALS AND METHODS

A randomized clinical trial was designed. Twenty-eight patients referred for onlay bone augmentation prior to implant placement were included in the study. Preoperative computerized tomography (CT) was taken for all patients. Patients received FDBA blocks of either cancellous or corticocancellous bone obtained from the iliac crest. After a 4-month follow-up, postoperative CT was taken. Then, another surgery was performed, with the purpose to place dental implants. The aforementioned groups were compared for bone resorption and implant outcome using analysis of covariance (ANCOVA) and repeated ANOVA measures, respectively. Demographic data, trabecular bone density, and graft sites were also analyzed.

RESULTS

A total of 93 implants were placed in the augmented bone sites over 28 patients. A 100% survival rate was achieved during a mean follow-up period of 24 months in both groups. Higher bone resorption rate was found with cancellous bone grafts (29.2% ± 2.6) compared with corticocancellous grafts (19.3% ± 2.3). Moreover, higher resorption rates in patients with lower bone density (<185 Hounsfield Units) (31.7% ± 3.1) and smokers (26.39% ± 2.3) were observed when compared with patients with higher bone density (>185 Hounsfield Units) (16.8% ± 2.1) and nonsmokers (22.1% ± 2.3), respectively.

CONCLUSION

Within the limitations of this study, these findings indicate that both corticocancellous and cancellous FDBA grafts constitute a clinical acceptable alternative for bone reconstruction, although cancellous grafts present higher resorption rates. Moreover, host factors such as patient's low bone density and smoking habits may also increase graft resorption rates.

Anterior atrophic mandible restoration using cancellous bone block allograft

BACKGROUND

Bone block grafting may be required to restore the alveolar process prior to implant placement in Kennedy Class IV partial edentulism of the anterior mandible.

PURPOSE

Evaluate the application of allograft cancellous bone blocks for the augmentation of the anterior atrophic mandible.

MATERIALS AND METHODS

Fourteen consecutive patients underwent augmentation with cancellous bone block allografts in the anterior mandible. A bony deficiency of at least 3 mm horizontally and up to 3 mm vertically according to computerized tomography para-axial reconstruction served as inclusion criteria. Following 6 months, 26 implants were placed and a cylindrical sample core was collected. All specimens were prepared for histological and histomorphometrical examination. The rehabilitation scheme was two dental implants, placed in the lateral incisor area, supporting a 4-unit implant-supported prosthesis.

RESULTS

Twenty-four blocks were placed in 14 patients. Mean follow-up was 26 ± 17 months. Mean bone gain was 5 ± 0.5 mm horizontally, and 2 ± 0.5 mm vertically. Twenty-six implants were used. Marginal bone loss at last follow up did not extend beyond the first thread. Block and implant survival rates were 91.6% and 100%, respectively. All patients but one received a fixed implant-supported prosthesis. Histomorphometrically, the mean fraction of the newly formed bone was 42%, that of the residual cancellous block-allograft 17%, and of the marrow and connective tissue 41%.

CONCLUSIONS

The potential of cancellous bone block allografts for reconstruction of Kennedy Class IV partial edentulism in the anterior mandible seems promising but still has to be evaluated scientifically in long-term observations.

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.

Novel Technique for Reconstruction of the Severely Resorbed Posterior Maxillae: Tuberosity-Flip Approach

PURPOSE

This report describes a novel technique that allows for 3-dimensional augmentation of localized bone defects of the posterior maxilla and simultaneous implant placement by means of using the maxillary tuberosity as a block graft.

MATERIALS AND METHODS

The residual bone in maxillary tuberosity is harvested as a whole. The recipient site and the bone graft are prepared with compatible implant drills. The bone graft is flipped to fit the defect and fixated in place using the dental implant, which anchors both the graft and the subantral bone.

RESULTS

The defect of the posterior maxilla is reconstructed with autogenous bone harvested from maxillary tuberosity, and simultaneous implant placement is achieved.

CONCLUSION

The proposed technique enables the clinician to reconstruct alveolar defects of the posterior maxilla without the need for an additional donor site and simultaneously place dental implants.

The application of a delayed expansion technique for horizontal alveolar ridge augmentation in dental implantation

The aim of this study was to evaluate the application of delayed expansion of the alveolar ridge in dental implantation. This method avoids the need to harvest autogenous bone and the requirement to fix a block with screws, and could help prevent the uncontrolled fracture and avascular necrosis that may result from the traditional alveolar split. Eighteen patients and 43 implants were included in this retrospective study. The width of the alveolar ridge was measured before implantation, immediately after implantation, and after the final restoration. The width increased significantly after the insertion of implants and decreased slightly after bone remodelling. Overall, the width of the alveolar ridge increased by 2.37±1.44mm on average, ranging from -0.20mm to 5.75mm. The results suggest the use of delayed expansion for horizontal alveolar bone augmentation; however, the maxillary premolar area may not be a suitable site.

Histomorphometric and immunohistochemical evaluation of collagen containing xenogeneic bone blocks used for lateral bone augmentation in staged implant placement

BACKGROUND

The osteoconductive properties of collagen containing xenogeneic bone blocks (CCXBB) remain unclear. The aim of this prospective single-arm clinical study was to assess the histological outcomes of CCXBB blocks used as bone replacement grafts for lateral bone augmentation procedures.

METHODS

In 15 patients with severe horizontal alveolar ridge resorption, lateral augmentation procedures were performed using CCXBB as bone replacement grafts. Twenty-six weeks postoperatively, a re-entry procedure was performed to evaluate the bone width for adequate implant placement and two histological specimens were retrieved from each patient, one being processed for ground sectioning and the other for decalcified paraffin-included sections. In non-decalcified sections, the relative proportions occupied by bone, biomaterials, and connective tissue present in the biopsies were identified. In de-calcified sections, structures and cells positive for osteopontin (OPN), tartrate-resistant acid phosphatase activity (TRAP), osteocalcin (OSC), and alkaline phosphatase (ALP) were assessed.

RESULTS

Soft tissue dehiscence occurred during the follow-up in 5 out of 15 patients (33.3%). The mean crest width at baseline was 2.78 mm (SD 0.57) and the mean crest width at re-entry was 6.90 mm (SD 1.22), with a mean ridge width increase of 4.12 mm (SD 1.32). Twenty-six bone biopsies were obtained from 13 patients. Histomorphometric analysis showed a mean of 26.90% (SD 12.21) of mineralized vital bone (MVB), 21.37% (SD 7.36) of residual CCXBB, 47.13% (SD 19.15) of non-mineralized tissue, and 0.92% of DBBM. The immunohistochemical analysis revealed a large number of OPN-positive cells 8.12% (SD 4.73), a lower proportion of TRAP positive multinuclear cells 5.09% (SD 4.91), OSC-positive cells 4.09% (SD 4.34), and a limited amount of ALP positive cells 1.63% (SD 2).

CONCLUSIONS

CCXBB achieved significant horizontal crestal width allowing for staged implant placement in most of the patients. In light of the histological outcomes and implant failures, special attention must be placed to prevent soft tissue dehiscence when CCXBB is used in severe atrophic alveolar crests.

Clinical and Histomorphometric Assessment of Lateral Alveolar Ridge Augmentation Using a Corticocancellous Freeze-Dried Allograft Bone Block

Horizontal ridge augmentation with allografts has attracted notable attention because of its proper success rate and the lack of disadvantages of autografts. Corticocancellous block allografts have not been adequately studied in humans. Therefore, this study clinically and histomorphometrically evaluated the increase in ridge width after horizontal ridge augmentation using corticocancellous block allografts as well as implant success after 12 to 18 months after implantation. In 10 patients receiving implants (3 women, 7 men; mean age = 45 years), defective maxillary alveolar ridges were horizontally augmented using freeze-dried bone allograft blocks. Ridge widths were measured before augmentation, immediately after augmentation, and ∼6 months later in the reentry surgery for implantation. This was done at points 2 mm (A) and 5 mm (B) apically to the crest. Biopsy cores were acquired from the implantation site. Implant success was assessed 15.1 ± 2.7 months after implantation (range = 12-18 months). Data were analyzed using Friedman and Dunn tests (α = 0.05). At point A, ridge widths were 2.77 ± 0.37, 8.02 ± 0.87, and 6.40 ± 0.66 mm, respectively, before surgery, immediately after surgery, and before implantation. At point B, ridge widths were 3.40 ± 0.39, 9.35 ± 1.16, and 7.40 ± 1.10 mm, respectively, before surgery, immediately after surgery, and before implantation. The Friedman test showed significant increases in ridge widths, both at point A and point B (both P = .0000). Postaugmentation resorption was about 1.5-2 mm and was statistically significant at points A and B (P < .05, Dunn). The percentage of newly formed bone, residual graft material, and soft tissue were 33.0% ± 11.35% (95% confidence interval [CI] = 24.88%-41.12%), 37.50% ± 19.04% (95% CI = 23.88%-51.12%), and 29.5%, respectively. The inflammation was limited to grades 1 or zero. Twelve to 18 months after implantation, no implants caused pain or showed exudates or pockets. Radiographic bone loss was 2.0 ± 0.7 mm (range = 1-3). It can be concluded that lateral ridge augmentation with corticocancellous allograft blocks might be successful both clinically and histologically. Implants might have a proper clinical success after a minimum of 12 months.

Volumetric Stability of Fresh Frozen Bone Blocks in Atrophic Posterior Mandible Augmentation

Fresh frozen bone allografts (FFB) have become an alternative for bone augmentation in the past decades, especially because of the absence of recent reports of disease transmission or immunologic reactions when it is used. The aim of this prospective controlled study is to evaluate volumetric changes of newly created bone following reconstruction of the atrophic posterior mandible. Twenty consecutive patients presenting for reconstruction of posterior mandibular alveolar bone ridge width ≤6.0 mm and/or height ≤6.0 who met all inclusion and exclusion criteria were included. FFB blocks were used. The main outcome variable investigated was bone volume dynamics. Vertical, horizontal, and 3-dimensional bone gain data were measured from computerized tomography scans. The main predictor variable was time evaluated at 3 points: immediately after surgery (T1), at implant placement (T2), and 1 year after functional loading (T3). Secondary outcome parameters evaluated were implant survival, histologic findings, and microtomographic morphometry. The study included 28 hemi-mandibles, 50 FFB bone blocks, and 15 female and 5 male patients (mean age, 51.8 years). Block and implant survival rates were 100% and 96%, respectively, after 31.75 months of follow-up. Vertical and horizontal bone gain at T2 was 5.15 and 6.42 mm, respectively. Volumetric resorption was 31% at T2, followed by an additional 10% reduction at T3. Histologic evaluation showed newly formed vital bone in intimate contact with the remaining FFB. Microtomography revealed 31.8% newly formed bone, 14.5% remaining grafted bone, and 53.7% connective tissue and bone marrow. Thus, FFB blocks may lead to new bone formation and consolidation, with satisfactory volumetric bone maintenance, allowing implant-supported rehabilitation with high success rates.

Biomaterial shell bending with 3D-printed templates in vertical and alveolar ridge augmentation: a technical note

OBJECTIVES

Alveolar ridge and vertical augmentations are challenging procedures in dental implantology. Even material blocks with an interconnecting porous system are never completely resorbed. Shell techniques combined with autologous bone chips are therefore the gold standard. Using biopolymers for these techniques is well documented. We applied three-dimensional (3-D) techniques to create an individualized bending model for the adjustment of a plane biopolymer membrane made of polylactide.

STUDY DESIGN

Two cases with a vertical alveolar ridge defect in the maxilla were chosen. The cone beam computed tomography data were processed with a 3-D slicer and the Autodesk Meshmixer to generate data about the desired augmentation result. STL data were used to print a bending model. A 0.2-mm poly-D, L-lactic acid membrane (KLS Matin Inc., Tuttlingen, Germany) was bended accordingly and placed into the defect via a tunnel approach in both cases. A mesh graft of autologous bone chips and hydroxylapatite material was augmented beneath the shell, which was fixed with osteosynthesis screws.

RESULTS

The operative procedure was fast and without peri- or postoperative complications or complaints. The panoramic x-ray showed correct fitting of the material in the location. Bone quality at the time of implant placement was type II, resulting in good primary stability.

CONCLUSIONS

A custom-made 3-D model for bending confectioned biomaterial pieces is an appropriate method for individualized adjustment in shell techniques. The advantages over direct printing of the biomaterial shell and products on the market, such as the Xyoss shell (Reoss Inc., Germany), include cost-efficiency and avoidance of regulatory issues.

Bovine bone matrix/poly(l-lactic-co-ε-caprolactone)/gelatin hybrid scaffold (SmartBone®) for maxillary sinus augmentation: A histologic study on bone regeneration

The ideal scaffold for bone regeneration is required to be highly porous, non-immunogenic, biostable until the new tissue formation, bioresorbable and osteoconductive. This study aimed at investigating the process of new bone formation in patients treated with granular SmartBone^® for sinus augmentation, providing an extensive histologic analysis. Five biopsies were collected at 4-9 months post SmartBone^® implantation and processed for histochemistry and immunohistochemistry. Histomorphometric analysis was performed. Bone-particle conductivity index (BPCi) was used to assess SmartBone^® osteoconductivity. At 4 months, SmartBone^® (12%) and new bone (43.9%) were both present and surrounded by vascularized connective tissue (37.2%). New bone was grown on SmartBone^® (BPCi=0.22). At 6 months, SmartBone^® was almost completely resorbed (0.5%) and new bone was massively present (80.8%). At 7 and 9 months, new bone accounted for a large volume fraction (79.3% and 67.4%, respectively) and SmartBone^® was resorbed (0.5% and 0%, respectively). Well-oriented lamellae and bone scars, typical of mature bone, were observed. In all the biopsies, bone matrix biomolecules and active osteoblasts were visible. The absence of inflammatory cells confirmed SmartBone^® biocompatibility and non-immunogenicity. These data indicate that SmartBone^® is osteoconductive, promotes fast bone regeneration, leading to mature bone formation in about 7 months.

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.

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.

Posterior atrophic mandible rehabilitation with onlay allograft created with CAD-CAM procedure: a case report

AIM

Implant rehabilitation of the atrophic right posterior mandible in a 48-year-old woman using dehydrated homologous bone block, shaped with a computer aided design-computer aided manufacturing (CAD-CAM) system, to avoid harvesting of autologous bone block and to assure a perfect fitting of the block above the alveolar crest.

RESULTS

After 7 months, 6.09, 7.36, and 8.08 mm (mean, 7.18 mm) of total horizontal bone gain was observed at sites 6, 12, and 18 mm posterior to the right mental foramen, respectively.

CONCLUSIONS

The use of a bone block with CAD-CAM system for alveolar ridge augmentation is a valuable alternative to autograft because it reduces time, cost, and complications for the patients. Data from a computerized tomographic scan can be used to shape a precise 3-dimensional homologous bone block using a CAD-CAM system.

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.