Current trends and future perspectives of bone substitute materials – From space holders to innovative biomaterials

An autologous bone graft is still the ideal material for the repair of craniofacial defects, but its availability is limited and harvesting can be associated with complications. Bone replacement materials as an alternative have a long history of success. With increasing technological advances the spectrum of grafting materials has broadened to allografts, xenografts, and synthetic materials, providing material specific advantages. A large number of bone-graft substitutes are available including allograft bone preparations such as demineralized bone matrix and calcium-based materials. More and more replacement materials consist of one or more components: an osteoconductive matrix, which supports the ingrowth of new bone; and osteoinductive proteins, which sustain mitogenesis of undifferentiated cells; and osteogenic cells (osteoblasts or osteoblast precursors), which are capable of forming bone in the proper environment. All substitutes can either replace autologous bone or expand an existing amount of autologous bone graft.Because an understanding of the properties of each material enables individual treatment concepts this review presents an overview of the principles of bone replacement, the types of graft materials available, and considers future perspectives. Bone substitutes are undergoing a change from a simple replacement material to an individually created composite biomaterial with osteoinductive properties to enable enhanced defect bridging.     

Bleeding incidence after oral surgery with continued oral anticoagulation

Objectives

The aim of this retrospective study was to assess the incidence of postoperative hemorrhage in patients treated with coumarins without interruption of the anticoagulant treatment undergoing oral surgical procedures, mostly osteotomies for tooth removal, when compared with patients who had never been anticoagulated.

Material and methods

Six hundred thirty-seven patients underwent 934 oral surgical procedures on an outpatient basis. The INR was measured preoperatively being 2.44 in the mean SD 0.61. Local hemostasis was carried out routinely (80%) with collagen fleece, local flap, and acrylic splint.

Results

Of these 637 patients, 47 presented with a postoperative hemorrhage (7.4%), 15 of these 47 cases had to be treated in hospital (2.4%). All patients showed up finally with a good wound healing, no administration of blood was necessary, and local measures revealed to be sufficient in all cases except for two patients, where the preoperative anticoagulant treatment had to be changed for 6?days. The bleeding incidence in 285 patients with comparable oral surgical procedures, who had never been anticoagulated, was 0.7%.

Conclusions

The results suggest that oral surgical procedures can be performed safely without alteration of the oral anticoagulant treatment.

Cinical relevance

Local hemostasis with collagen fleece, local flap, and acrylic splint seems to be sufficient to prevent postoperative bleeding.     

10‐Year Follow‐Up of Immediately Loaded Implants with TiUnite Porous Anodized Surface

Background: The immediate loading of implants with a porous anodized surface is a well‐described technique. Few data are however available on the long‐term outcomes. Purpose: The aim of this prospective study was to assess the 10‐year performance of TiUnite implants supporting fixed prostheses placed with an immediate loading approach in both postextractive and healed sites. Materials and Methods: All patients received a fixed provisional restoration supported by immediately loaded parallel design, self‐tapping implants with a porous anodized TiUnite surface, and an external‐hexagonal connection. Both healed and postextractive cases were included. Success and survival rate for restorations and implants, changes in marginal peri‐implant bone level, probing depth measurements, biological or technical complications, and any other adverse event were recorded at yearly follow‐up up to 10 years after surgery. Results: A total of 210 implants fulfilled the inclusion criteria and were consecutively placed in 59 patients. Forty‐seven (22.38%) implants were lost because of the recalled patient refused to attend the planned 10‐year follow‐up. Five over 210 (2.38%) implants were lost. At the final follow‐up, the accumulated mean marginal bone loss and probing depth were, respectively, 1.93 mm (SD 0.40) and 2.54 mm (SD 0.44) for the implants placed in healed sites (n = 84); 1.98 mm (SD 0.37) and 2.63 mm (SD 0.39) for the implants placed in postextractive sites (n = 74). The restorations examined achieved a cumulative 65.26% success rate and 97.96% survival rate. The implants placed in healed and postextractive sites, respectively, achieved a 98.05% and a 96.52% cumulative survival rate. Conclusions: Positive results in terms of bone maintenance in the long‐term perspective are to be expected using immediately loaded implants with a TiUnite porous anodized surface in both postextractive and healed sites when adequate levels of oral hygiene are kept.     

Push-out bond strength and SEM evaluation of a new bonding approach into the root canal

Objective

This study evaluated the performance of different adhesive systems in fiber post placement aiming to clarify the influence of different hydrophobic experimental blend adhesives, and of one commercially available adhesive on the frictional retention during a luting procedure.

Material and Methods

One luting agent (70 Wt% BisGMA, 28.5% TEGDMA; 1.5% p-tolyldiethanolamine) to cement fiber posts into root canals was applied with 4 different adhesive combinations: Group 1: The etched roots were rinsed with water for 30 s to remove the phosphoric acid, then rinsed with 99.6% ethanol for 30 s, and blotdried. A trial adhesive (base to catalyst on a 1:1 ratio) was used with an experimental luting agent (35% Bis-GMA, 14.37% TeGDMA, 0.5% eDMAB, 0.13% CQ); Group 2: A trial adhesive (base to catalyst on a 1:2 ratio) was luted as in Group 1; Group 3: One-Step Plus (OSP, Bisco Inc.) following the ethanol bonding technique in combination with the luting agent as in Group 1; Group 4: OSP strictly following the manufacturer''s instructions using the luting agent as in Group 1. The groups were challenged with push-out tests. Posted root slices were loaded until post segment extrusion in the apical-coronal direction. Failure modes were analyzed under scanning electron microscopy.

Results

Push-out strength was not significantly influenced by the luting agent (p>0.05). No statistically significant differences among the tested groups were found as Group 1 (exp 1 - ethanol-wet bonding technique)=Group 2 (exp 2 - ethanol-wet bonding technique)=Group 3 (OSP - ethanol-wet bonding technique)=Group 4 (control, OSP - water-wet bonding technique) (p>0.05). The dominating failure modes in all the groups were cohesive/adhesive failures, which were predominantly observed on the post/luting agent interface.

Conclusions

The results of this study support the hypothesis that the proposal to replace water with ethanol to bond fiber posts to the root canal using highly hydrophobic resin is plausible, but this seems to be more the proof of a concept than a clinically applicable procedure.     

Matters of life and breath: A role for hypoxia in determining cell state

Thus, hypoxia appears to inhibit the transition from quiescence to senescence by a non-canonical mechanism that is independent of both p53 and HIF-1. Comment on: Leontieva OV et al. Hypoxia suppresses conversion from proliferative arrest to cellular senescence. Proc Natl Acad Sci U S A. 2012 Aug 14;109(33):13314-13318.