Effect of absorbable membranes on sandwich bone augmentation

Horizontal GBR with anorganic equine bone combined with a customized titanium mesh

This case report describes the fixed rehabilitation of the lower left arch in a patient following an horizontal GBR procedure by means of a customized titanium mesh and a new slow resorption bone substitute of equine origin.

Efficacy of biomaterials for lateral bone augmentation performed with guided bone regeneration. A network meta-analysis

Bone regeneration is often required concomitant with implant placement to treat a bone fenestration, a dehiscence, and for contouring. This systematic review assessed the impact of different biomaterials employed for guided bone regeneration (GBR) simultaneous to implant placement on the stability of radiographic peri-implant bone levels at ≥12 months of follow-up (focused question 1), as well as on bone defect dimension (width/height) changes at re-assessment after ≥4 months (focused question 2). Only randomized controlled trials (RCTs) and controlled clinical trials (CCTs) that compared different biomaterials for GBR were considered. A Bayesian network meta-analysis (NMA) was performed using a random-effects model. A ranking probability between treatments was obtained, as well as an estimation of the surface under the cumulative ranking value (SUCRA). Overall, whenever the biological principle of GBR was followed, regeneration occurred in a predictable way, irrespective of the type of biomaterial used. A lower efficacy of GBR treatments was suggested for initially large defects, despite the trend did not reach statistical significance. Regardless of the biomaterial employed, a certain resorption of the augmented bone was observed overtime. While GBR was shown to be a safe and predictable treatment, several complications (including exposure, infection, and soft tissue dehiscence) were reported, which tend to be higher when using cross-linked collagen membranes.

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.

Stability of contour augmentation of implant-supported single crowns in the esthetic zone: One-year cone-beam computed tomography results of a comparative, randomized, prospective, two-center clinical study using two different bone grafting techniques in early implant placement

BACKGROUND

Early implant placement with contour augmentation could provide support and volume to the hard and soft tissues. Herein, we aimed to ascertain whether freeze-dried bone allograft (FDBA) shares with deproteinized bovine bone material (DBBM) the results for esthetic outcomes for anterior teeth and stability of peri-implant facial bone thickness and height by conducting guided bone regeneration.

METHODS

Forty-eight patients were randomly assigned into two groups. In the control group, autogenous bone chips was used to cover the exposed implant surface, followed by a layer of DBBM. This graft combination was then covered with two layers of collagen membrane. In the test group, the exposed implant surface was covered with FDBA, combined with the collagen membrane. During this study, the hard tissue dimensional changes were measured at 12-months post-implant loading by using cone-beam computed tomography.

RESULTS

At 12 months postoperatively, all 48 implants were clinically successful. The mean thickness of facial bone walls ranged from 1.6 to 2.45 mm at the three levels of measurement in the control group and ranged from 1.6 to 2.10 mm in the test group. The mean facial vertical bone wall peak (IP-FC) after loading 1 year presented with values of 0.8 mm (range, 0.0 to 1.25 mm) and 0.5 mm (range, 0.1 to 1.1 mm) coronal to the implant platform in control and test implants, respectively. There were no significant differences in facial bone wall thickness and IP-FC between groups.

CONCLUSIONS

This study demonstrated that autogenous bone chips plus DBBM or FDBA showed similar outcome of peri-implant buccal bone stability in early implant placement after 1 year.

Immediate implant placement vs. early implant treatment in the esthetic area. A 1-year randomized clinical trial

OBJECTIVES

To assess the impact of implant placement and temporization timing on esthetic outcomes of single maxillary anterior implants with intact bone walls and interproximal bone.

MATERIALS AND METHODS

Test group patients received an immediate implant with immediate provisional restoration and socket preservation, while patients in the control group received an early implant placement with guided bone regeneration and delayed loading. Patients were followed for 1 year after final prosthetic and pink esthetic score (PES), mid-buccal mucosal level (MBML), crestal bone changes (CBC), and peri-implant soft tissue parameters, and patient chair time was recorded.

RESULTS

Fifty patients received the intended treatment (25 test and 25 control). No implants failed. PES after 1 year was 12.8 ± 1.19 for the test group and 12.5 ± 1.36 for the control group (p = .362). MBML difference between baseline (after final crown delivery) and the 1-year follow-up was gain of 0.2 ± 1.02 mm for the test group (p = .047) and no change in the control group. CBC after 1 year were 0.1 mm ± 0.21 mm (mesial) and 0.2 mm ± 0.22 mm (distal) for the test group and 0.2 mm ± 0.25 mm (mesial) and 0.3 mm ± 0.19 mm (distal) for the control group, p = .540 (mesial) and p = .462 (distal). Test group required half the chair time (127 ± 13 min) when compared to the control group (259 ± 15 min, p < .001).

CONCLUSIONS

Within the limits of this trial, both treatment protocols resulted in excellent esthetic outcomes with PES >12 after 1-year follow-up.

The effect of collagen membrane and of bone substitute on lateral bone augmentation with titanium mesh: An experimental in vivo study

AIM

The aim of this study was to identify the additional effects of collagen membrane (CM) and of synthetic bone substitute (BS) on lateral bone augmentation of chronic peri-implant defect with titanium mesh (TM).

MATERIALS AND METHODS

Atrophic alveolar ridge was induced in 6 canine mandibles and 5 peri-implant defects were achieved in each hemi-mandible. Bone augmentation was attempted using the following randomly allocated modalities: 1) Control: no treatment, 2) TM only group: blood clot covered by TM, 3) TM+BS group: BS covered by TM, 4) TM+CM group: blood clot covered by TM and CM, and 5) TM+BS+CM group: BS covered by TM and CM. After 16 weeks of submerged healing, micro-CT and histomorphometric analyses were performed.

RESULTS

TM exposure occurred in one case in the TM only group, one case in the TM+CM group, and two cases in the TM+BS+CM group. Histologically, pseudo-periosteum was observed along the inner and outer surfaces of TM, and the directions of the collagen fiber within the pseudo-periosteum differed according to the additional use of CM. In general, the TM only group rendered higher values in vertical defect fill and dimension of the augmented hard tissue in comparison to the other treatment groups.

CONCLUSIONS

Due to the small sample size, this pilot study remains inconclusive. Within the limitations of the study, the use of CM and/or BS did not appear to have an additional benefit on lateral bone augmentation of peri-implant defect with TM.

Complications in bone-grafting procedures: Classification and management

Bone-regenerative interventions aiming to restore deficient alveolar ridges, such as the use of block grafts or through the application of guided bone-regeneration principles, have reported positive outcomes in the published scientific literature. These interventions, however, are invasive, and hence, intraoperative and/or postoperative complications may occur. The types of complications and their severity may vary from the exposure of the biomaterial (membrane or graft) to postsurgical infections, neurosensorial disturbances, occurrence of hemorrhage, and pain, etc. The aim of the present narrative review was to search the available scientific evidence concerning the incidence of these complications, their effect on treatment outcomes, their clinical management and, finally, strategies aimed at prevention. Exposure of the barrier membrane or the block graft is the most common complication associated with oral regenerative interventions. To manage these complications, depending on the extent of the exposure and the presence or absence of concomitant infections, therapeutic measures may vary, from the topical application of antiseptics to the removal of the barrier membrane or the block graft. Regardless of their treatment, the occurrence of these complications has been associated with patient selection, with compliant patients (eg, nonsmokers) having a lower reported incidence of complications. Similarly, surgical factors such as correct flap elevation and a tensionless closure are of obvious importance. Finally, to prevent the incidence of complications, it appears prudent to utilize whenever possible less invasive surgical interventions.

Laser-assisted regenerative surgical therapy for peri-implantitis: A randomized controlled clinical trial

BACKGROUND

Different surgical approaches have been proposed to treat peri-implantitis defects with limited effectiveness and predictability. Laser has been proposed as an effective tool to assist in bacterial decontamination and modulating peri-implant tissue inflammation. The aim of this pilot clinical trial was to evaluate the adjunctive benefits of Er:YAG laser irradiation for regenerative surgical therapy of peri-implantitis-associated osseous defects.

METHODS

Twenty-four patients diagnosed with peri-implantitis with a radiographic infrabony defect were randomized into two groups. Both test and control groups received the following treatment: open flap mechanical debridement, supracrestal implantoplasty, bone grafting using a mixture of human allograft with demineralized bone matrix human allograft putty, and then covered with acellular dermal matrix membrane. The only difference in the test group was the adjunctive use of Er:YAG laser to modulate and remove inflammatory tissue as well as to decontaminate the implant surface. Clinical assessments, including pocket depth (PD), clinical attachment level (CAL), and gingival index (GI) were performed by calibrated masked examiners for up to 6 months following surgery. Standardized radiographs were also taken to evaluate linear bone gain and defect bone fill. Student t-tests were used to analyze those clinical parameters.

RESULTS

Both groups showed significant reductions in PD, GI, and CAL gain overtime. The test group demonstrated significantly higher PD reductions at the site level compared to the control group (2.65 ± 2.14 versus 1.85 ± 1.71 mm; test versus control, P = 0.014). There were no statistical differences found in CAL gain (1.90 ± 2.28 versus 1.47 ± 1.76 mm; test versus control), GI reduction (-1.14 ± 1.15 versus -1.04 ± 0.89; test versus control), radiographic linear bone gain (1.27 ± 1.14 versus 1.08 ± 1.04 mm; test versus control) or proportional defect size reduction (- 24.46 ± 19.00% versus -15.19 ± 23.56%; test versus control). There was a positive trend for test patients on PD reduction and CAL gain found in narrow infrabony defects. Major membrane exposure negatively impaired the overall treatment outcome of CAL gain (2.47 ± 1.84 versus 1.03 ± 1.48 mm; no/minor versus major exposure, P = 0.051) and PD reduction in the test group (-3.63 ± 2.11 versus -1.66 ± 1.26 mm, P = 0.049).

CONCLUSION

This pilot study indicated using laser irradiation during peri-implantitis regenerative therapy may aid in better probing PD reduction. Nonetheless, a larger sample size and longer follow-up is needed to confirm if Er:YAG laser irradiation provides additional clinical benefits for peri-implantitis regenerative therapy (Clinicaltrials.gov: NCT03127228).

Horizontal ridge augmentation using native collagen membrane vs titanium mesh in atrophic maxillary ridges: Randomized clinical trial

BACKGROUND

Several techniques have been proposed to reconstruct deficient alveolar ridges including bone blocks, ridge splitting and guided bone regeneration (GBR). GBR has been successfully established in restoring horizontal bone deficiency. However, yet still there is a debate regarding the ideal barrier for GBR.

PURPOSE

To evaluate the quantity and the quality of the bone gained using collagen membrane with 1:1 mixture of autogenous and anoraganic bovine bone mineral compared to titanium mesh with the same mixture of bone for GBR of horizontally deficient maxillary ridges.

MATERIALS AND METHODS

Two different grafting techniques were evaluated, 10 patients receiving GBR using native collagen membrane using 1:1 autogenous and anorganic bovine bone mineral (ABBM) bone mixture, and 10 patients receiving GBR using titanium mesh with same mixture of bone.

RESULTS

Statistical analysis showed a significant increase in alveolar bone width in both techniques with a mean bone gain of 4.0 mm for Collagen group and 3.7 mm for titanium mesh group. Bone area percent was almost 28% for both groups. For Ti-mesh group, six sites soft tissue healing was uneventfully with no signs of wound dehiscence. However, four cases showed mesh exposure first 3 patients showed this exposure 3 weeks postoperatively while the fourth patient showed exposure 4 months postoperatively. The mean graft resorption in the Collagen and mesh group 6 months postoperative was considered nonsignificant.

CONCLUSIONS

GBR with both collagen membrane and titanium mesh using a 1:1 mixture of autogenous and ABBM is a viable technique for horizontal augmentation of deficient maxillary alveolar ridges. Titanium mesh is a more technique sensitive compared to collagen membrane. Soft tissue dehiscence and difficulty during second stage removal should limit its use in augmentation of horizontally deficient maxillary ridges.

A Preshaped Titanium Mesh for Guided Bone Regeneration with an Equine-Derived Bone Graft in a Posterior Mandibular Bone Defect: A Case Report

One of the most often used bone augmentation techniques is the guided bone regeneration procedure. The authors report the case of a 75-year-old man with an atrophic right posterior mandible who underwent bone augmentation through guided bone regeneration with a preshaped titanium mesh adapted on a stereolithographic model of the patient’s jaw. The graft volume was simulated with a light-curing resin. The actual site was grafted with a mixture of autogenous and equine-derived bone. Five months later, the mesh was retrieved, three cylindrical implants were positioned, and a bone biopsy was collected for histomorphometric analysis. A provisional prosthesis was delivered three and a half months later. Definitive rehabilitation was accomplished after one additional month. The graft allowed for effective bone formation (newly formed bone, residual biomaterial, and medullar spaces were, respectively, 39%, 10%, and 51% of the core volume). The patient has functioned successfully throughout six and a half years of follow-up. Using the preshaped titanium mesh in association with the enzyme-treated equine bone substitute provided effective bone regeneration.

Guided bone regeneration: materials and biological mechanisms revisited

Guided bone regeneration (GBR) is commonly used in combination with the installment of titanium implants. The application of a membrane to exclude non‐osteogenic tissues from interfering with bone regeneration is a key principle of GBR. Membrane materials possess a number of properties which are amenable to modification. A large number of membranes have been introduced for experimental and clinical verification. This prompts the need for an update on membrane properties and the biological outcomes, as well as a critical assessment of the biological mechanisms governing bone regeneration in defects covered by membranes. The relevant literature for this narrative review was assessed after a MEDLINE/PubMed database search. Experimental data suggest that different modifications of the physicochemical and mechanical properties of membranes may promote bone regeneration. Nevertheless, the precise role of membrane porosities for the barrier function of GBR membranes still awaits elucidation. Novel experimental findings also suggest an active role of the membrane compartment per se in promoting the regenerative processes in the underlying defect during GBR, instead of being purely a passive barrier. The optimization of membrane materials by systematically addressing both the barrier and the bioactive properties is an important strategy in this field of research.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Vertical ridge augmentation of the atrophic posterior mandible with sandwich technique: bone block from the chin area versus corticocancellous bone block allograft--clinical and histological prospective randomized controlled study

The aim of the present study is to compare the histological aspects of bone formation in atrophic posterior mandibles augmented by autologous bone block from chin area with corticocancellous bone block allograft used as inlays with the sandwich technique.

MATERIALS AND METHODS

Sixteen patients with bilateral partial edentulism in the posterior mandible were selected. The residual bone height, preliminarily measured by computed tomography scans, ranged between 5 and 7 mm from the inferior alveolar nerve. All patients required regeneration procedure with autologous bone block from chin area (control group) versus bone block allograft Puros (Zimmer Dental, 1900 Aston Avenue, Carlsbad, CA, USA) (test group). Histological and histomorphometric samples were collected at the time of implant positioning in order to analyze the percentage of newly formed bone, the residual graft material, and marrow spaces/soft tissue.

RESULTS

No statistically significant differences between the two groups were found regarding the percentage of newly formed bone. The percentage of residual grafted material was significantly higher in the test group, whilst the percentage of marrow spaces was higher in control group.

CONCLUSIONS

In conclusion, both procedures supported good results, although the use of bone blocks allograft was less invasive and preferable than harvesting bone from the mental symphysis.