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

Application of CAD-CAM Technologies for Maxillofacial Bone Regeneration: A Narrative Review of the Clinical Studies

The application of regenerative methods in treating maxillofacial defects can be categorized as functional bone regeneration in which scaffolds without protection are used and in-situ bone regeneration in which a protected healing space is created to induce bone formation. It has been shown that functional bone regeneration can reduce surgical time and obviate the necessity of autogenous bone grafting. However, studies mainly focused on applying this method to reconstruct minor bone effects, and more investigation concerning the large defects is required. In terms of in situ maxillofacial bone regeneration with the help of CAD-CAM technologies, the present data have suggested feasible mesh rigidity, perseverance of the underlying space, and apt augmentative results with CAD-CAM-based individualized Ti meshes. However, complications, including dehiscence and mesh exposure, coupled with consequent graft loss, infection and impeded regenerative rates have also been reported.

Application of biodegradable Patient-specific scaffolds for maxillofacial bone regeneration: a scoping review of clinical studies

This study aimed to systematically review clinical studies in which biodegradable patient-specific scaffolds were used for bone regeneration. Studies in which biodegradable scaffolds were fabricated through computer-assisted design and computer-assisted manufacturing (CAD-CAM) procedures were included. Those that applied non-biodegradable materials or used biodegradable materials in a condensable powder or block form were excluded. Among a total of 26 included studies, 11 used customised allogeneic bone blocks, five used polycaprolactone (PCL)-containing scaffolds, four used hydroxyapatite (HA) scaffolds, and four biphasic calcium phosphate (BCP). The majority of the studies applied scaffolds for minor intraoral defects. All the large defects were reconstructed with polymer-containing scaffolds. Results of the included studies showed partial to complete filling of the defect following the application of biodegradable scaffolds. However, limited graft exposure was reported when using PCL, BCP, and HA scaffolds. Tissue engineering can be considered a potential method for the treatment of maxillofacial bone defects. However, more evidence is required, especially for the application of biodegradable scaffolds in large defects.

Efficacy and volume stability of a customized allogeneic bone block for the reconstruction of advanced alveolar ridge deficiencies at the anterior maxillary region: a retrospective radiographic evaluation

OBJECTIVES

The aim of this retrospective case series was to evaluate the efficacy and volume stability of a customized allogeneic bone block (CABB) for the hard tissue reconstruction of severely atrophied anterior maxillary ridges.

MATERIALS AND METHODS

Hard tissue alterations between baseline (T1), 2-month follow-up (T2), and 6-month follow-up (T3) cone-beam computed tomography scans were evaluated with semi-automatic segmentation. Following automatic spatial alignment of the datasets, 3D subtraction analysis was performed. The volume stability of the inserted allogeneic bone block was determined on the basis of the ratio of the T3 and T2 hard tissue volumes.

RESULTS

The newly formed hard tissue volume at T2 averaged at of 0.75 cm³ ± 0.57 cm³, whereas at T3, an average of 0.52 cm³ ± 0.42 cm³ volumetric hard tissue gain could be detected. The T3/T2 ratio was found to be 67.83% ± 18.72% on average. The dice similarity coefficient between the T2 and T3 hard tissue models averaged at 0.73 ± 0.15.

CONCLUSIONS

Cancellous CABBs are a reliable option for the reconstruction of severely atrophied alveolar ridges. The resorption rates of these grafts are similar to those found in the literature; however, with precise manufacturing and proper intraoperative flap management, the resorption rates may be reduced.

CLINICAL RELEVANCE

With precise knowledge of the resorption patterns, the shape of blocks can be altered in the future to compensate for the volumetric loss.

Custom-made computer-aided-design/ computer-assisted-manufacturing (CAD/CAM) synthetic bone grafts for alveolar ridge augmentation: A retrospective clinical study with 3 years of follow-up

PURPOSE

To report on the results obtained with computer-aided-design/ computer-assisted-manufacturing (CAD/CAM) custom-made synthetic hydroxyapatite/beta-tricalcium-phosphate (HA/beta-TCP) bone grafts in alveolar ridge augmentation for dental implant placement.

METHODS

The procedure included: (1) cone-beam computed tomography (CBCT) of the bone defect; (2) virtual design of the custom-made onlay bone grafts; (3) milling of grafts from a pre-formed block of synthetic HA/beta-TCP; and (4) bone reconstructive surgery. Implants were placed 8 months later. The patients were followed for 3 years. The study outcomes were: (1) intra- and immediate post-operative complications; (2) 8-month vertical and horizontal bone gain; (3) implant survival; (4) implant-crown success; and (5) peri-implant marginal bone loss (MBL).

RESULTS

Twenty-six patients underwent ridge augmentation with custom-made CAD/CAM HA/beta-TCP onlay grafts. Eight months later, these patients were rehabilitated with dental implants. During surgery, 25/26 (96.1%) of the grafts adapted well to the bone defect. Immediate post-operative complications were pain and swelling (2/26 patients: 7.6%), and bone graft exposure (3/26: 11.5%); one exposure led to infection, removal of the graft, and failure of the procedure. Excellent integration of the other grafts was observed 8 months after the regenerative procedure, with mean vertical and horizontal bone gains of 2.10 mm (± 0.35) and 2.96 mm (± 0.45), respectively. Twenty-five implants were placed and restored with single crowns. Three years later, all implants were in function. The 3-year implant crown success rate and peri-implant MBL were 92.0% and 0.7 mm (±0.19), respectively.

CONCLUSIONS

With custom-made CAD/CAM synthetic HA/beta-TCP onlay grafts reconstruction of small vertical and/or horizontal defects of the alveolar ridge was obtained; this enabled implant placement, with high implant-crown success rate after 3 years. Further studies are needed to validate this technique.

STATEMENT OF CLINICAL RELEVANCE

Custom-made CAD/CAM synthetic HA/beta-TCP onlay grafts may represent an option for regeneration of small bone defects prior to implant placement.

The use of 3D ceramic block graft compared with autogenous block graft for rehabilitation of the atrophic maxilla: a randomized controlled clinical trial

Background

Dental implant placement may require a bone graft for vertical and horizontal alveolar ridge augmentation. Due to its osteoconduction, osteoinductive, and osteogenesis, autogenous bone graft characteristics are considered the standard gold treatment. However, autografts can promote postoperative morbidity and implicate difficulties concerning the graft adaptation to the recipient's bone since it can eventually avoid gaps. To overcome these issues, this trial will compare the performance of Plenum® Oss 3Dβ fit, an alloplastic graft, and a 3D-printed patient-specific graft based on β-tricalcium phosphate to the autograft procedure.

Methods

This is a split-mouth randomized clinical study designed to evaluate the performance of personalized (patient-specific) bioceramic bone grafts (Plenum® Oss 3Dβ fit) for bone augmentation of the atrophic anterior maxilla in comparison to the autogenous bone graft. We hypothesize that the gain and maintenance of the grafted area volume and the quality of the newly formed bone tissue after eight months postoperative with the synthetic patient-specific graft will be superior to the autogenous bone graft. To assess the quantity and the quality of bone neoformation, volumetric and histological analyses will be performed.

Discussion

The fabrication of medical devices by additive manufacturing presents advantages over conventional manufacturing processes, mostly related to the precision of geometry and anatomy. Additionally, the osteoconductive proprieties of β-tricalcium phosphate enable this synthetic bone substitute as an alternative solution over autogenous graft for bone defect reconstruction. Thus, patient-specific bone grafts can potentially improve patient satisfaction, reducing the need for autogenous bone grafts, consequently avoiding implications related to this type of treatment, such as patient morbidity.

Trial registration

This study is registered in REBEC (Registro Brasileiro de Ensaios Clínicos): RBR-76wmm3q; UTN: U1111-1272-7773. Registration date: 14 September 2021.

Specially designed and CAD/CAM manufactured allogeneic bone blocks using for augmentation of a highly atrophic maxilla show a stable base for an all-on-six treatment concept: a case report

Background

In terms of a highly atrophic maxilla, bone augmentation still remains very challenging. With the introduction of computer-aided design/computer-aided manufacturing (CAD/CAM) for allogeneic bone blocks, a new method for the treatment of bone deficiencies was created. This case report demonstrates the successful use of two specially designed and CAD/CAM manufactured allogeneic bone blocks for a full arch reconstruction of a highly atrophic maxilla with an all-on-six concept.

Case presentation

We report the case of a 55-year-old male patient with a highly atrophic maxilla and severe bone volume deficiencies in horizontal and vertical lines. In order to treat the defects, the surgeon decided to use a combination of two allogeneic bone blocks and two sinus floor augmentations. The bone blocks were fabricated from the data of a cone beam computed tomography (CBCT) using CAD/CAM technology. After the insertion of the two bone blocks and a healing period of 7 months, six dental implants were placed in terms of an all-on-six concept. The loading of the implants took place after an additional healing time of 7 months with a screw-retained prosthetic construction and with a milled titanium framework with acrylic veneers.

Conclusion

The presented procedure shows the importance of the precise design of CAD/CAM manufactured allogeneic bone blocks for the successful treatment of a highly atrophic maxilla. Proper soft-tissue management is one of the key factors to apply this method successfully.

Guided Bone Regeneration using Titanium Mesh to Augment 3-dimensional alveolar defects prior to implant placement. A Pilot Study

Objectives

To evaluate the outcomes of bone regeneration using a customized titanium mesh scaffold to cover a bone graft for reconstruction of complex defects of the jaws.

Materials and Methods

19 large defects were digitally reconstructed using CT scans according to the prosthetic requirements. A titanium mesh scaffold was designed to cover the bone (autologous/bovine bone particulate) graft. At least 6 months after surgery, a new cone‐beam CT was taken. The pre‐ and postoperative CT datasets were then converted into three‐dimensional models and digitally aligned. The actual mesh position was compared to the virtual position to assess the reliability of the digital project. The reconstructed bone volumes (RBVs) were calculated according to the planned bone volumes (PBVs), outlining the areas under the mesh. These values were then correlated with the number of exposures, locations of atrophy, and virtually planned bone volume.

Results

The mean matching value between the planned position of the mesh and the actual one was 82 ± 13.4%. 52.3% (40% early and 60% late) exposures were observed, with 15.8% exhibiting infection. 26.3% resulted as failures. The amount of reconstructed bone volume (RBV) in respect to PBV was 65 ± 40.5%, including failures, and 88.2 ± 8.32% without considering the failures. The results of the exposure event were statistically significant (p = .006) in conditioning the bone volume regenerated.

Conclusions

This study obtained up to 88% of bone regeneration in 74% of the cases. The failures encountered (26%) should underline the operator's expertise relevance in conditioning the final result.

Volumetric Changes of a Customized Allogeneic Bone Block Measured by Two Image Matching Tools: Introduction of a Novel Assessment Technique for Graft Resorption

Objective

The purpose of this case report was to present a method for the assessment of volumetric changes of bone blocks during healing and demonstrate its practicability by analysing the resorption of a pre-shaped allogeneic bone block used for the reconstruction of a complex maxillary defect.

Materials and methods

CBCT-scans of a 19-year-old male treated with an allogeneic bone block were recorded pre-OP, post-OP, and following six months of healing. Graft shrinkage was assessed via two image matching tools, namely coDiagnostiX® and Slicer. A biopsy specimen was harvested along the implant canal at the time of implantation.

Results

The osseous defect was successfully restored and advanced graft remodelling was found upon re-entry as confirmed by the histomorphometric and histologic analysis. The initial volumes of the graft determined via coDiagnostiX® and Slicer were 0.373 mL and 0.370 mL., respectively, while graft resorption after six months of healing was 0.011 mL (3.00%) and 0.016 mL (4.33%).

Conclusions

The avoidance of bone harvesting and reduction of invasiveness display an important issue in dentoalveolar restorations. However, before grafting materials can be considered a safe alternative, understanding their clinical performance, especially resorption stability, is pivotal. The present case report demonstrates a limited resorption of the allogeneic bone block and further emphasizes the practicability of determining bone resorption by the here introduced method. As our investigation comprises solely one subject, the results should be considered with care and substantiated by further studies.

A customized allogenic bone block for alveolar reconstruction quantitated by a 3D matching technique: A case report

After initial resorption, the bone volume showed long-term stability following loading of the implant. Furthermore, 3D matching was a suitable quantification method to analyze the volume development of bone augmentation.

Custom allogeneic block graft for ridge augmentation: Case series

INTRODUCTION

Alveolar bone deficiency is a common postextraction sequela that adversely affects implant placement. Therefore, ridge augmentation is often required to obtain proper bone quantity and quality for restoratively driven implant placement. This case series describes the successful horizontal and vertical alveolar ridge augmentation using custom-fabricated allogeneic block bone grafts.

CASE SERIES

Two healthy partially edentulous patients presented to private practice seeking dental implant treatment. Initial clinical examination and cone-beam computed tomography (CBCT) radiographic analysis showed moderate to large horizontal ridge defects. Treatment options were discussed for alveolar ridge augmentation and the patients elected to undergo the custom allogeneic block graft procedure to regenerate the atrophied alveolar ridges. The CBCT scan in conjunction with computer-aided design/computer-aided manufacturing (CAD/CAM) technology was used to fabricate customized allogeneic block grafts based on alveolar ridge topography. The custom allogeneic block graft allowed less surgical time and decreased postoperative morbidity. The grafted area was allowed 6 months of healing time. Follow-up radiographs showed the stability of the graft followed by dental implant placement. The dental implants were functionally loaded, and successful implant esthetics and function achieved.

CONCLUSION

Custom allogeneic block grafts could provide a promising innovative method for optimal ridge augmentation.

KEY POINTS

Why are these cases new information? Less invasive procedure as an alternative conventional two-stage block augmentation. More predictable outcome due to customized block graft. What are the keys to successful management of these cases? It is important determining the type of bone defect. Vertical and horizontal bone loss. Primary closure. What are the primary limitations to success in these cases? Limited data from prospective clinical trials documenting the effectiveness of custom allogeneic block grafts. Limited data are available to confirm accuracy of the CAD/CAM process. Passive flap closure is needed.

[Experimental study of the bearing capacity of lyophilized allogeneic bone material]

THE AIM OF THE STUDY

Was to conduct an experimental study of the bearing capacity and determination of the Young's modulus of lyophilized allogeneic bone material.

MATERIALS AND METHODS

The study used 5 prototypes of lyophilized allogeneic bone blocks, which were alternately subjected to static loading by compressive force. The experimental values of Young's modulus of all bone samples were determined. When applying the Student's probability distribution in statistical processing of experimental data, the average indicators of the forces of destruction of the samples were obtained and Young's modulus was determined.

RESULTS AND DISCUSSION

As a result of the study, the indices of the maximum loading (6012H) and Young's modulus (147.2±0.228 MPa) of lyophilized allogeneic bone material were obtained.

CONCLUSION

The obtained Young's modulus of lyophilized allogeneic bone material is of great importance in scientific activity, providing the possibility of further investigation of the properties of lyophilized allogeneic bone tissue to form a preoperative forecast of the behavior of an osteoplastic material and a dental implant installed in it.

Ex Vivo and In Vivo Analyses of Novel 3D-Printed Bone Substitute Scaffolds Incorporating Biphasic Calcium Phosphate Granules for Bone Regeneration

(1) Background: The aim of this study was examining the ex vivo and in vivo properties of a composite made from polycaprolactone (PCL) and biphasic calcium phosphate (BCP) (synprint, ScientiFY GmbH) fabricated via fused deposition modelling (FDM); (2) Methods: Scaffolds were tested ex vivo for their mechanical properties using porous and solid designs. Subcutaneous implantation model analyzed the biocompatibility of PCL + BCP and PCL scaffolds. Calvaria implantation model analyzed the osteoconductive properties of PCL and PCL + BCP scaffolds compared to BCP as control group. Established histological, histopathological and histomorphometrical methods were performed to evaluate new bone formation.; (3) Results Mechanical testing demonstrated no significant differences between PCL and PCL + BCP for both designs. Similar biocompatibility was observed subcutaneously for PCL and PCL + BCP scaffolds. In the calvaria model, new bone formation was observed for all groups with largest new bone formation in the BCP group, followed by the PCL + BCP group, and the PCL group. This finding was influenced by the initial volume of biomaterial implanted and remaining volume after 90 days. All materials showed osteoconductive properties and PCL + BCP tailored the tissue responses towards higher cellular biodegradability. Moreover, this material combination led to a reduced swelling in PCL + BCP; (4) Conclusions: Altogether, the results show that the newly developed composite is biocompatible and leads to successful osteoconductive bone regeneration. The new biomaterial combines the structural stability provided by PCL with bioactive characteristics of BCP-based BSM. 3D-printed BSM provides an integration behavior in accordance with the concept of guided bone regeneration (GBR) by directing new bone growth for proper function and restoration.

Alveolar ridge augmentation using the shell technique with allogeneic and autogenous bone plates in a split-mouth design-A retrospective case report from five patients

Atrophic alveolar ridges of five patients were augmented with allografts and autografts on opposite sites, followed by dental implantation. Both augmentation materials led to equivalent bone gains. Allografts did not compromise the clinical outcome.

A novel digital and visualized guided bone regeneration procedure and digital precise bone augmentation: A case series

BACKGROUND

Although the traditional bone augmentation technology can basically meet the clinical needs at present, the effect of bone augmentation in most cases is related to the experience of the operator.

PROPOSE

This study commits to providing a digital solution for precise bone augmentation in the field of oral implantology.

MATERIALS AND METHODS

After collecting the data of patients' intraoral scanning and DICOM (digital imaging and communications in medicine), the implant position is digitally designed, and the alveolar bone is digitally augmented around the ideal implant position. On the premise of ensuring that the thickness of labial bone is 2 mm, and there is sufficient alveolar bone 3 to 4 mm apically from the ideal gingival margin for implant placing, we carry out excessive augmentation of 0.5 and 1 mm on the labial bone and alveolar crest, respectively, to compensate for possible bone resorption after 6 months. After 3D printing the reconstructed alveolar bone model, the titanium mesh is trimmed and preformed on the alveolar bone model. Outcomes are reported in terms of mean values (5%-95% percentile values).

RESULTS

Thirty implant sites have accepted this novel virtually designed alveolar bone augmentation. Before the second-stage surgery, the average vertical bone gain was 2.48 mm (0.29-6.32), the average horizontal bone gain was 4.11 mm (1.19-8.74), the average height of the residual alveolar bone above the implant platform was 1.44 mm (0.59-2.92), the average thickness of the labial bone width at the implant platform was 2.00 mm (0.93-3.64), the average thickness of the labial bone width at 2 mm apically from the implant platform was 2.74 mm (1.40-5.46). The virtual augmentation of each tooth position was 349.41 mm³ (165.70-482.70), while the actual augmentation of each tooth position was 352.94 mm³ (159.24-501.78), the accuracy of the final actual augmentation reached 95.82% (range from 88.53% to 99.15%).

CONCLUSION

This case series suggests that a virtually digital guided bone regeneration (GBR) workflow is precise and controllable. The practicality, safety and effectiveness of this procedure needs to be compared to other bone augmentation procedures in randomized controlled trials.

Integrated 3D Information for Custom-Made Bone Grafts: Focus on Biphasic Calcium Phosphate Bone Substitute Biomaterials

Purpose: Several studies showed that the sintering temperature of 1250 °C could affect the formation of α-Ca₃(PO₄)₂, which is responsible for the reduction of the hardness value of biphasic calcium phosphate biocomposites, but they did not evaluate the inference of the sintering time at peak temperature on transition of β-Ca₃(PO₄)₂ to α-Ca₃(PO₄)₂. This analysis explored, in an innovative way, inferences and correlations between volumetric microstructure, mechanical properties, sintering temperature, and time at peak temperature in order to find the best sintering conditions for biphasic calcium phosphate composites grafted in severe alveolar bone defects. Methods: Sintered biphasic calcium phosphates (30%-hydroxyapatite/70%-tricalcium phosphate) were tested by microCT imaging for the 3D morphometric analysis, by compressive loading to find their mechanical parameters, and by X-ray diffraction to quantify the phases via Rietveld refinement for different sintering temperatures and times at the peak temperature. Data were analysed in terms of statistical inference using Pearson’s correlation coefficients. Results: All the studied scaffolds closely mimicked the alveolar organization of the jawbone, independently on the sintering temperatures and times; however, mechanical testing revealed that the group with peak temperature, which lasted for 2 hours at 1250 °C, showed the highest strength both at the ultimate point and at fracture point. Conclusion: The good mechanical performances of the group with peak temperature, which lasted for 2 hours at 1250 °C, is most likely due to the absence of the α-Ca₃(PO₄)₂ phase, as revealed by X-ray diffraction. However, we detected its presence after sintering at the same peak temperature for longer times, showing the time-dependence, combined with the temperature-dependence, of the β-Ca₃(PO₄)₂ to α-Ca₃(PO₄)₂ transition.

Influence of Different Rehydration Protocols on Biomechanical Properties of Allogeneic Cortical Bone Plates: A Combined in-vitro/in-vivo Study

Introduction: Allogeneic cortical bone plates (CP) are used for alveolar ridge augmentation. Since CP are freeze-dried and dehydrated during processing, the breaking strength (BS) and the flexibility (FX) are reduced, resulting in a relevant risk for plate fractures during insertion. The aim of this study was to evaluate the influence of rehydration time on the biomechanical properties (BS & FX) of CP in-vitro and in vivo.Material and Methods: 40 CP were randomly divided into four experimental groups. (A) untreated control (n = 10), rehydration for 10 (B), 30 (C) and 60 (D) minutes in 0.9% saline solution (n = 10 each). BS [Newton, N] and FX [mm] (force till fracture and distance of deflection to the breaking point) were analyzed. Besides, architectural features of all CP groups were visualized and examined by scanning electron microscopy (SEM). In addition, the frequency of CP fractures of rehydrated- vs. non-rehydrated CP was retrospectively analyzed in 6 patients.Results: Compared to the control group, significantly increased BS and FX were demonstrated after 10, 30 and 60 minutes of rehydration (p each ≤ 0.035). After a rehydration time of 10 minutes, no additional increase of BS and FX was seen when compared to30 and 60 minutes (p each = 1.0). SEM scans demonstrated that the CP fracture characteristics were influenced by the different rehydration protocols. The frequency of CP fractures was reduced in patients by CP rehydration.Conclusion: The biomechanical properties of CP can be significantly improved by 10 min of rehydration, resulting in an increased BS and FX, that might be clinically relevant.

Customized allogeneic bone grafts for maxillary horizontal augmentation: A 5-year follow-up radiographic and histologic evaluation

We report the histological evaluation of an individualized allogeneic bone block 5 years after alveolar ridge augmentation. The biopsy showed a well-vascularized lamellar bone with fatty incorporations without any avital allograft remnants. The presence of osteocytes, lining cells, macrophages, and blood vessels indicated a healthy and vital bone tissue.

Evaluation of Alveolar Ridge Height Gained by Vertical Ridge Augmentation Using Titanium Mesh and Novabone Putty in Posterior Mandible

Aim

The purpose of this case series was to report the clinical and radiographical outcomes of vertical ridge augmentation in edentulous posterior mandible using a combination of titanium mesh with novabone putty.

Material and Method

Twenty patients were included, and grafting was done using alloplastic novabone putty supported by titanium mesh as the barrier for guided bone regeneration.

Results

Sixteen patients exhibited good soft tissue healing. Postoperative flap dehiscence occurred relatively early in the healing period in one patient followed by graft extrusion and delayed healing in other three patients. The mean vertical height of augmented bone was 4.825 ± 1.1387 mm.

Conclusion

This report demonstrates the remarkable efficacy of guided bone regeneration using a combination of titanium mesh and novabone putty for vertical ridge augmentation, thus expanding the indications for implant therapy and allowing recovery of the three-dimensional esthetic architecture in a severely resorbed alveolar ridge.

In vitro and in vivo biocompatibility of calcium-phosphate scaffolds three-dimensional printed by stereolithography for bone regeneration

Stereolithography (SLA) is an interesting manufacturing technology to overcome limitations of commercially available particulated biomaterials dedicated to intra-oral bone regeneration applications. The purpose of this study was to evaluate the in vitro and in vivo biocompatibility and osteoinductive properties of two calcium-phosphate (CaP)-based scaffolds manufactured by SLA three-dimensional (3D) printing. Pellets and macro-porous scaffolds were manufactured in pure hydroxyapatite (HA) and in biphasic CaP (HA:60-TCP:40). Physico-chemical characterization was performed using micro X-ray fluorescence, scanning electron microscopy (SEM), optical interferometry, and microtomography (μCT) analyses. Osteoblast-like MG-63 cells were used to evaluate the biocompatibility of the pellets in vitro with MTS assay and the cell morphology and growth characterized by SEM and DAPI-actin staining showed similar early behavior. For in vivo biocompatibility, newly formed bone and biodegradability of the experimental scaffolds were evaluated in a subperiosteal cranial rat model using μCT and descriptive histology. The histological analysis has not indicated evidences of inflammation but highlighted close contacts between newly formed bone and the experimental biomaterials revealing an excellent scaffold osseointegration. This study emphasizes the relevance of SLA 3D printing of CaP-based biomaterials for intra-oral bone regeneration even if manufacturing accuracy has to be improved and further experiments using biomimetic scaffolds should be conducted.

Computer-Aided Design/Computer-Aided Manufacturing Milling of Allogeneic Blocks Following Three-Dimensional Maxillofacial Graft Planning

Despite the advent of stereolithography in craniofacial surgery for creating surgical guides and custom synthetic scaffolds, little is known about the feasibility of computer-aided design/computer-aided manufacturing (CAD/CAM) milling of freeze-dried allogeneic bone blocks following previously designed volumetric graft plans. The aim of this technical report is to present a methodology for CAD/CAM milling to achieve the volume and shape of allogeneic bone blocks as estimated by using a virtual planning software. To perform the current methodology, an ex vivo simulation was performed. The milled allogeneic block presented satisfactory dimensional accuracy as compared with the respective three-dimensional virtual model.

Comparative Study between Laser Light Stereo-Lithography 3D-Printed and Traditionally Sintered Biphasic Calcium Phosphate Scaffolds by an Integrated Morphological, Morphometric and Mechanical Analysis

In dental districts, successful bone regeneration using biphasic calcium phosphate materials was recently explored. The present study aimed to perform a comparative study between 3D-printed scaffolds produced by laser light stereo-lithography (SLA) and traditionally sintered biphasic calcium phosphate scaffolds by an integrated morphological, morphometric and mechanical analysis. Methods: Biphasic calcium phosphate (30% HA/70% β-TCP) samples, produced by SLA-3D-printing or by traditional sintering methods, were tested. The experimental sequence included: (1) Microtomography (microCT) analyses, to serve as control-references for the 3D morphometric analysis; (2) loading tests in continuous mode, with compression up to fracture, to reconstruct their mechanical characteristics; and (3) microCT of the same samples after the loading tests, for the prediction of the morphometric changes induced by compressive loading of the selected materials. All the biomaterials were also studied by complementary scanning electron microscopy to evaluate fracture regions and surfaces. Results: The characterization of the 3D mineralized microarchitecture showed that the SLA-3D-printed biomaterials offer performances comparable to and in some cases better than the traditionally sintered ones, with higher mean thickness of struts and pores. Interestingly, the SLA-3D-printed samples had a higher ultimate strength than the sintered ones, with a smaller plastic region. Moreover, by SEM observation, it was observed that fractures in the SLA-3D-printed samples were localized in the structure nodes or on the external shells of the rods, while all the traditionally sintered samples revealed a ductile fracture surface. Conclusions: The reduction of the region of plastic deformation in the SLA-3D-printed samples with respect to traditionally sintered biomaterials is expected to positively influence, in vivo, the cell adhesion. Both microCT and SEM imaging revealed that the studied biomaterials exhibit a structure more similar to human jaw than the sintered biomaterials.

Marginal and internal fit of 3D printed resin graft substitutes mimicking alveolar ridge augmentation: An in vitro pilot study

Recent improvements in additive manufacturing technologies may facilitate the use of customized 3D printed grafts for horizontal and vertical augmentation of the atrophic alveolar ridge. The accurate fit of such grafts could reduce the clinical treatment time and contribute optimal bone regeneration. The aim of this in vitro study was to evaluate the marginal and internal fit of 3D printed resin grafts as they could be used for alveolar ridge augmentation. Alveolar ridge morphologic data were derived from the Cone Beam Computed Tomography (CBCT) scans of six patients with alveolar bone defects. These data were transferred to a segmentation program to produce virtual 3D reconstructions of the alveolar ridge models. Using a Computer Aided Design (CAD) program, the alveolar bone defects were defined and customized grafts were designed and both the defects as well as the grafts generated (CAM) as 3D projects. These projects were imported into a 3D printer and were manufactured in resin. Hereafter, the grafts were fitted to the defect sites of the corresponding models and new CBCT scans were performed. Based on these scans, measurements were made at the marginal and internal part of the fitted grafts to evaluate the marginal and internal fit, respectively. The statistical analysis revealed that the mean marginal fit was significantly better (P < 0.05) than the mean internal fit. The fit of the grafts was dependent on the shape and on the size of the grafts. Specifically, the total void surface between the fitted graft and the corresponding defect site was significantly larger in the large-defect grafts than the small-defect grafts (P < 0.05). Within the limitations of the study, it could be demonstrated that it is possible to fabricate 3D printed resin grafts with acceptable fit in customized shapes, when combining CBCT scans and computer aided design and 3D printing techniques.

Bilateral maxillary augmentation using CAD/CAM manufactured allogenic bone blocks for restoration of congenitally missing teeth: A case report

OBJECTIVE

Various biomaterials have been successfully applied in alveolar bone regeneration, however, the reconstruction of extensive osseous defects remains challenging and is often unfeasible with granular grafting materials. Several studies have outlined allogenic bone blocks as valid alternative to autologous block grafting.

CLINICAL CONSIDERATIONS

In this report, we demonstrate the regeneration of two large osseous defects in the maxilla with allogenic bone blocks made from human donor bone. The bone blocks were customized using the CAD/CAM technology in order to enable the insertion of four dental implants.

CONCLUSIONS

Both blocks perfectly matched the defect geometry, showed limited resorption, led to the formation of sufficient amounts of mineralized bone in both horizontal and vertical dimensions and enabled the installation of implants according to the treatment plan. The implementation of innovative technologies for individualization of allogenic bone blocks simplifies the restoration of complex and extensive osseous defects and poses great benefits for both practitioners and patients.

CLINICAL SIGNIFICANCE

The here presented procedure demonstrates the successful regeneration of two extensive osseous defects in a patient suffering from hypodontia using two CAD/CAM manufactured allogenic bone blocks, rendering the procedure far less invasive as compared to guided bone regeneration carried out with autologous transplants. Furthermore, to the best of our knowledge, this is the first case report that radiographically demonstrates the new formation of a cortical bone layer following block grafting with solely cancellous bone blocks.

Treatment of a bilaterally severely resorbed posterior mandible due to early tooth loss by Guided Bone Regeneration using customized allogeneic bone blocks: A case report with 24 months follow-up data

OBJECTIVE

The use of allogeneic bone grafts for alveolar ridge reconstruction has become an often-discussed alternative to augmentation procedures using autografts. Nevertheless, there still is a lack of literature concerning long-time experiences of allografts for alveolar ridge reconstruction. Especially the results of the use of allogeneic bone blocks for mandible reconstructions need to be further investigated.

CLINICAL CONSIDERATIONS

In this case report, we present the use of customized allogenic bone blocks in Guided Bone Regeneration (GBR) procedures for severely deficient mandibulary bones, the implantation after a healing period of 5 month and the 24-month follow-up data.

CONCLUSIONS

Customized allogeneic bone blocks seem to be a successful alternative to augmentations with autologous bone blocks reconstructing highly resorbed mandibulary alveolar ridges, showing highest volume stability and no signs of bone resorption after implant loading.

CLINICAL SIGNIFICANCE

The application of customized allogeneic bone blocks has shown to be a successful augmentation technique even compared with with autologous bone blocks reconstructing highly resorbed mandibulary alveolar ridges demonstrating no compromises regarding clinical outcome, functionality and esthetics.

Horizontal ridge reconstruction of the anterior maxilla using customized allogeneic bone blocks with a minimally invasive technique - a case series

BACKGROUND

Different surgical procedures have been proposed to achieve horizontal ridge reconstruction of the anterior maxilla; all these procedures, however, require bone replacement materials to be adapted to the bone defect at the time of implantation, resulting in complex and time-consuming procedures. The purpose of this study was to describe how to use a 3D printed hardcopy model of the maxilla to prepare customized milled bone blocks, to be adapted on the bone defect areas using a minimally invasive subperiosteal tunneling technique.

METHODS

Cone beam computed tomography (CBCT) images of the atrophic maxilla of six patients were acquired and modified into 3D reconstruction models. Data were transferred to a 3D printer and solid models were fabricated using autoclavable nylon polyamide. Before the surgery, freeze-dried cortico-cancellous blocks were manually milled and adapted on the 3D printed hardcopy models of the maxillary bone, in order to obtain customized allogeneic bone blocks.

RESULTS

In total, eleven onlay customized allogeneic bone grafts were prepared and implanted in 6 patients, using a minimally invasive subperiosteal tunneling technique. The scaffolds closely matched the shape of the defects: this reduced the operation time and contributed to good healing. The patients did not demonstrate adverse events such as inflammation, dehiscence or flap re-opening during the recovery period; however, one patient experienced scaffold resorption, which was likely caused by uncontrolled motion of the removable provisional prosthesis. Following a 6 month healing period, CBCT was used to assess graft integration, which was followed by insertion of implants into the augmented areas. Prosthetic restorations were placed 4 months later.

CONCLUSIONS

These observations suggest that customized bone allografts can be successfully used for horizontal ridge reconstruction of the anterior maxilla: patients demonstrated reduced morbidity and decreased total surgery time. Further studies on a larger sample of patients, with histologic evaluation and longer follow-up are needed to confirm the present observations.

Treatment of Severely Resorbed Maxilla Due to Peri-Implantitis by Guided Bone Regeneration Using a Customized Allogenic Bone Block: A Case Report

The objective of this case report is to introduce a customized CAD/CAM freeze-dried bone allograft (FDBA) block for its use in Guided Bone Regeneration (GBR) procedures for severely deficient maxillary bones. Additionally, a special newly developed remote incision technique is presented to avoid wound dehiscence. The results show optimal integration behavior of the FDBA block after six months and the formation of new vital bone. Thus, the results of the present case report confirm the use of the customized CAD/CAM bone block for augmentation of complex defects in the maxillary aesthetic zone as a successful treatment concept.

Custom-milled individual allogeneic bone grafts for alveolar cleft osteoplasty-A technical note

INTRODUCTION

Bone grafts from the iliac crest are most commonly used for osteoplasties of the cleft alveolus. To preclude undue donoresite morbidity custom-milled allogeneic bone grafts might be an appropriate choice.

MATERIAL AND METHODS

This technical note showcases the repair of an alveolar cleft using an individualized allogeneic bone graft in a 36-year old female patient. She was asking for an alternative to the iliac crest bone grafting. Her alveolus was successfully build up by a custom-milled cancellous bone block allograft (maxgraft^® 80 bonebuilder).

RESULTS

Custom-milled cancellous bone block allografts can greatly facilitate alveolar cleft repair and may present an effective treatment option under the premise that resorption resistance corresponds to autografts.

CONCLUSION

Further clinical studies are needed to explore the potential of bone block allografts for alveolar cleft osteoplasty.

Custom-Made Synthetic Scaffolds for Bone Reconstruction: A Retrospective, Multicenter Clinical Study on 15 Patients

Purpose. To present a computer-assisted-design/computer-assisted-manufacturing (CAD/CAM) technique for the design, fabrication, and clinical application of custom-made synthetic scaffolds, for alveolar ridge augmentation. Methods. The CAD/CAM procedure consisted of (1) virtual planning/design of the custom-made scaffold; (2) milling of the scaffold into the exact size/shape from a preformed synthetic bone block; (3) reconstructive surgery. The main clinical/radiographic outcomes were vertical/horizontal bone gain, any biological complication, and implant survival. Results. Fifteen patients were selected who had been treated with a custom-made synthetic scaffold for ridge augmentation. The scaffolds closely matched the shape of the defects: this reduced the operation time and contributed to good healing. A few patients experienced biological complications, such as pain/swelling (2/15: 13.3%) and exposure of the scaffold (3/15: 20.0%); one of these had infection and complete graft loss. In all other patients, 8 months after reconstruction, a well-integrated newly formed bone was clinically available, and the radiographic evaluation revealed a mean vertical and horizontal bone gain of 2.1 ± 0.9 mm and 3.0 ± 1.0 mm, respectively. Fourteen implants were placed and restored with single crowns. The implant survival rate was 100%. Conclusions. Although positive outcomes have been found with custom-made synthetic scaffolds in alveolar ridge augmentation, further studies are needed to validate this technique.

Custom-Made Computer-Aided-Design/Computer-Aided-Manufacturing Biphasic Calcium-Phosphate Scaffold for Augmentation of an Atrophic Mandibular Anterior Ridge

This report documents the clinical, radiographic, and histologic outcome of a custom-made computer-aided-design/computer-aided-manufactured (CAD/CAM) scaffold used for the alveolar ridge augmentation of a severely atrophic anterior mandible. Computed tomographic (CT) images of an atrophic anterior mandible were acquired and modified into a 3-dimensional (3D) reconstruction model; this was transferred to a CAD program, where a custom-made scaffold was designed. CAM software generated a set of tool-paths for the manufacture of the scaffold on a computer-numerical-control milling machine into the exact shape of the 3D design. A custom-made scaffold was milled from a synthetic micromacroporous biphasic calcium phosphate (BCP) block. The scaffold closely matched the shape of the defect: this helped to reduce the time for the surgery and contributed to good healing. One year later, newly formed and well-integrated bone was clinically available, and two implants (AnyRidge, MegaGen, Gyeongbuk, South Korea) were placed. The histologic samples retrieved from the implant sites revealed compact mature bone undergoing remodelling, marrow spaces, and newly formed trabecular bone surrounded by residual BCP particles. This study demonstrates that custom-made scaffolds can be fabricated by combining CT scans and CAD/CAM techniques. Further studies on a larger sample of patients are needed to confirm these results.