Sandwich Bone Augmentation for Predictable Horizontal Bone Augmentation

Particulate bone grafting with a resorbable collagen membrane and horizontal alveolar ridge augmentation with tenting screws in dental implant placement: A case report

Key Clinical Message

We used a mixture of particulate bone grafts (xenografts/allografts) with tenting screws to prevent membrane collapse and covered the graft with a resorbable collagen membrane to guide bone regeneration. This strategy can exclude the need for additional procedures, such as non-resorbable membranes and major block grafting surgeries. Although the initial outcomes are promising, continuous follow-up is required to examine the stability of the newly regenerated bone and the long-term success of the implant.

Abstract

This case demonstrates the use of particulate bone grafts covered with a resorbable collagen membrane and supported by tenting screws to correct horizontal alveolar ridge defects. A man in his 40s presented with missing maxillary anterior central and lateral incisors and required a fixed dental prosthesis. One year before, #12, #11, #21, and #22 had been extracted. The area showed horizontal and slight vertical bone loss. We used a mixture of particulate bone grafts (xenografts and allografts) with tenting screws to prevent membrane collapse and covered the graft with a resorbable collagen membrane to guide bone regeneration. After 6 months, complete bone regeneration was achieved, and the dental implants were submerged in the bone. After another 6 months, the patient was administered with a fixed dental prosthesis. This method can be used to correct horizontal alveolar ridge defects and achieve esthetic restoration without the need for more extensive procedures.

Bone regeneration in implant dentistry: Which are the factors affecting the clinical outcome?

The key factors that are needed for bone regeneration to take place include cells (osteoprogenitor and immune-inflammatory cells), a scaffold (blood clot) that facilitates the deposition of the bone matrix, signaling molecules, blood supply, and mechanical stability. However, even when these principles are met, the overall amount of regenerated bone, its stability over time and the incidence of complications may significantly vary. This manuscript provides a critical review on the main local and systemic factors that may have an impact on bone regeneration, trying to focus, whenever possible, on bone regeneration simultaneous to implant placement to treat bone dehiscence/fenestration defects or for bone contouring. In the future, it is likely that bone tissue engineering will change our approach to bone regeneration in implant dentistry by replacing the current biomaterials with osteoinductive scaffolds combined with cells and mechanical/soluble factors and by employing immunomodulatory materials that can both modulate the immune response and control other bone regeneration processes such as osteogenesis, osteoclastogenesis, or inflammation. However, there are currently important knowledge gaps on the biology of osseous formation and on the factors that can influence it that require further investigation. It is recommended that future studies should combine traditional clinical and radiographic assessments with non-invasive imaging and with patient-reported outcome measures. We also envisage that the integration of multi-omics approaches will help uncover the mechanisms responsible for the variability in regenerative outcomes observed in clinical practice.

Evaluation of a Double Layer Technique to Enhance Bone Formation in Atrophic Alveolar Ridge: Histologic Results of a Pilot Study

The atrophic alveolar ridge has been a challenge in implant dentistry; various techniques using the principle of guided bone regeneration (GBR) have been applied in the past 2 decades.The aim of this study was to introduce and evaluate-clinically, histologically, and radiographically-a novel technique of regenerating a new bone in the atrophic alveolar ridge, which is based on the GBR principles, the double layer technique (DLT). Six patients with partially edentulous jaws with a residual bone width less than or equal to 4 mm in the maxilla were subjected to GBR. The sites were grafted using a DLT. At first, sites were grafted with allogenic bone and then a second layer of deproteinized bovine bone was placed. Next, grafted sites were covered with a resorbable membrane tucked with 2 titanium pins. Cone-beam computed tomography scans were obtained before and 5 months after DLT. In the latter case and during implant site preparation, trephine biopsies were obtained and processed for histologic and histomorphometric evaluation. In all cases, implants were successfully installed and primary stability was established. Implant diameter ranged from 3.8 to 4.1 mm. In all cases, radiographic findings showed increased alveolar ridge width before and after surgery. The new tissues consisted mostly of a variable amount of new trabecular bone, some loose connective tissue, blood vessels, and occasional inflammatory cells. All 15 implants placed had 100% survival rate after a 5-year follow-up. On the basis of these preliminary results, it seems that the double layer GBR technique may achieve satisfactory results from a clinical, radiographic, and histologic perspective favoring placement of dental implants in the atrophic maxillary alveolar ridge.

Periosteal Releasing Incision With Diode Laser in Guided Bone Regeneration Procedure: A Case Series

Introduction: Periosteal releasing incision (PRI) is nearly always essential to advance the flap sufficiently for a tension-free flap closure in bone augmentation procedures. However, hematoma, swelling, and pain are recognized as the main consequences of PRI with scalpel. The aim of this case series was to investigate the effectiveness of laser-assisted PRI in guided bone regeneration (GBR) procedure. In addition, postoperative hematoma, swelling, and pain and implant success were assessed. Methods: Seventeen patients needed GBR were included in this study. Diode laser (940 nm, 2 W, pulse interval: 1 ms, pulse length: 1 ms, contact mode, 400-μm fiber tip) was used in a contact mode to cut the periosteum to create a tension-free flap. Facial hematoma, swelling, pain, and the number of consumed nonsteroidal anti-inflammatory drugs (NSAIDs) were measured for the six postoperative days. Six months after implant loading, implant success was evaluated. Results: Minimal bleeding was encountered during the procedure. A tension-free primary closure of the flap was achieved in all cases. The clinical healing of the surgical area was uneventful. None of the patients experienced hematoma, ecchymosis, or intense swelling after surgery. The mean value of maximum pain (visual analogue scale - VAS) was 20.59 ± 12.10 mm (mild pain). Patients did not need to use NSAID after four postoperative days. All implants were successful and functional and none of them failed after 6 months of implant loading. Conclusion: This study revealed the effectiveness of laser-assisted PRI in GBR procedure. This technique was accompanied with minimal sequelae at the first postoperative week. All implants were successful and no complication was noted during the course of this study.

A randomized clinical trial evaluating the efficacy of the sandwich bone augmentation technique in increasing buccal bone thickness during implant placement. II. Tomographic, histologic, immunohistochemical, and RNA analyses

OBJECTIVES

This study aimed to evaluate the biologic and structural phenotypes of the bone regenerated via the sandwich bone augmentation (SBA) technique, on buccal implant dehiscence defects.

MATERIAL AND METHODS

Twenty-six patients with one buccal implant dehiscence defect each were randomly assigned to two groups. Both groups received a standardized amount of mineralized cancellous and cortical allogenic bone graft. In the test group, a bovine pericardium membrane was placed over the graft, while no membrane was placed in the control group. After 6 months of healing, a bone core biopsy of the regenerated bone was harvested and processed for histologic, immunohistochemical, mRNA, and micro-computed tomography (μCT) analyses. Of the 26 bone core biopsies, only six cores from the test group and six cores from the control group were suitable for the analysis.

RESULTS

Bone volume (BV) in the test group was maintained, but tissue maturation appeared to be delayed. In contrast, tissue maturation appeared to be completed in the control group, but BV was compromised. Micro-CT analysis showed that specimens from the control group were more structured and mineralized compared with those from the test group. Histologic analysis showed more residual graft particles scattered in a loose fibrous connective tissue matrix with sparse bone formation in the test group, while the control group showed obvious vital bone formation surrounding the residual graft particles. Positive periostin (POSTN), sclerostin, and runt-related transcription factor-2 (RUNX2) immunoreactivities were detected in both the control and test groups. However, tartrate-resistant acid phosphatase (TRAP) positive was mostly noted in the control group. There were significant differences in POSTN, RUNX2 and VEGF expressions between the test and control groups.

CONCLUSION

These findings indicated that the SBA technique was an effective method in preserving adequate structural volume while promoting new vital bone formation. Use of the collagen barrier membrane has successfully maintained the volumetric dimensions of the ridge but might have slowed down the complete maturation of the outermost layer of the grafted site.

Using Cone Beam Computed Tomography Angle for Predicting the Outcome of Horizontal Bone Augmentation

BACKGROUND

The aim of this study was to assess the influence of ridge morphology on the amount of horizontal bone augmentation achieved with the sandwich bone augmentation (SBA) technique in the reconstruction of buccal dehiscence defects on dental implants.

METHODS

Cone beam computed tomography (CBCT) was used to assess bone width changes in 26 patients who participated in a randomized controlled trial conducted in 2008 to 2011. The amount of horizontal bone gain was evaluated at four different levels (3, 6, 9, and 12 mm apical to the alveolar crest) and three different time points (T1: baseline, T2: at time of graft placement, and T3: 6 months later). Different morphological characteristics of the alveolar ridge were also evaluated to determine their influence on horizontal bone augmentation. A total of 78 CBCT scans were assessed.

RESULTS

Comparison of the changes in ridge morphology at all measurement locations showed an overall ridge width gain of 2.30 ± 2.20 mm after 6 months. The use of membranes and the angulation of the concavity played a role in influencing the outcomes of the SBA technique. Critical crest angulation (CA) is 150° for bone gain at 9 mm apical to the crest. When CA is smaller than 150°, the horizontal bone gain was 4.3 ± 2.2 mm; if CA is greater than 150°, the gain was significantly lower at 1.3 ± 1.7 mm (p = .001).

CONCLUSIONS

SBA is a reliable and predictable technique to gain horizontal ridge width with simultaneous implant placement. Crest ridge angulation can be used as a tool to predict bone gain at 9 mm apical to the bone crest.

Morphology of bone particles after harvesting with 4 different devices

INTRODUCTION

Autogenous bone is routinely used for regeneration of osseous defects around teeth and implants, and different instruments are available for bone harvesting.

OBJECTIVES

The purpose of this study was to describe the morphology of bone particles after harvesting with 4 different instruments.

MATERIALS AND METHODS

Bone particles were harvested from fresh cow ribs with 2 different types of back action chisels, a safescraper and a sonic device. The samples were examined morphologically using light microscopy and scanning electron microscopy.

RESULTS

The bone particles after the back action chisel I had an appearance similar to "pencil shavings." With the back action chisel II, they were like thin paper with an "accordion bellows" appearance. After removal with the safescraper, they had an irregular shape (with an irregular surface) resembling "crushed stone." Finally, the appearance of the bone particles obtained with the sonic device was homogenous, condensed and continuous, and had a "seaweed" appearance.

CONCLUSIONS

Harvesting of bone particles with 4 different devices produce distinctly difference sizes and shapes, which may influence the results of grafting procedures.