Dr. Eißing, what is your experience in your own practice: In how many cases are bone augmentations necessary – and in which regions of the jaw do they occur particularly frequently?
Alfons Eißing: The figures you mention correspond very well with my own experience. In about four out of five cases, we need to perform augmentation—especially in the aesthetic zone of the upper jaw. It is important to distinguish between two things: if the aim is to restore volume to support the red-white aesthetics, i.e., the gum contours, the focus is more on the shape. In this case, volume augmentation with bone replacement material that does not necessarily need to be revitalized is often sufficient. The situation is different in cases of bone deficits, such as a narrow alveolar ridge in the posterior region – whether in the lower or upper jaw – or in cases of vertical defects. In these cases, we need well-perfused, vital bone for stable implant placement. Autologous bone is clearly preferred here.
In most cases, we perform augmentation in a single stage. However, for more complex defects – when we work with bone shells, whether autologous or allogeneic, or augment with a bone block – we opt for a two-stage procedure to ensure optimal visibility and stable positioning of the graft. Minor corrections may be necessary during the subsequent implant session. We use bone substitute material (BSM) and a collagen membrane for this purpose.
What factors are decisive for you when choosing a membrane for guided bone regeneration (GBR)?
In GBR, choosing the right membrane is a key factor for successful treatment. From my experience with different products and manufacturers, several criteria have proven to be particularly relevant: First, the membrane must be biocompatible and support rapid revascularization and wound healing. Second, it must have a sufficient retention time of three to four months so that the membrane can reliably fulfill its barrier function. This prevents rapidly proliferating soft tissue cells from migrating into the augmented area.
Another crucial aspect is dimensional stability: only if the membrane remains dimensionally stable can it keep the space required for bone regeneration open and prevent collapse into the defect area. Last but not least, clinical handling plays an important role: The membrane should be malleable, flexible, and tear-resistant, i.e., easy to suture or pin, and can be used in practice without unnecessary complications. Ideally, it should not be sticky and should allow precise placement.
According to the manufacturer, Straumann® Membrane Flex is suitable for augmentation around implants, for local ridge augmentation, for filling bone defects or as part of GBR in dehiscence defects, and for GTR in periodontal defects, among other things.
In which indications do you use the all-round membrane?
I have been using Straumann® Membrane Flex for about a year, mainly in implant cases with volume deficits in the aesthetic zone. In these indications, I often work with xenogeneic replacement materials in combination with a collagen membrane. The Membrane Flex has proven to be very reliable for me.
The larger the bone defect, especially if a large proportion of the implant is not covered by bone, the more likely I am to opt for a dimensionally stable, non-resorbable membrane, as these offer reliable spatial stability over a longer period of time. This comes at the expense of a second procedure to remove the membrane. Therefore, its use is always indicated after weighing up the benefits and additional surgical effort involved.
In smaller defect situations, however, where I mainly work with replacement material, I clearly prefer resorbable membranes. The reason for this is their uncomplicated handling and the significantly lower complication rate, especially with regard to exposure or secondary procedures.
What particularly impresses you about this resorbable membrane?
What particularly impresses me is its excellent handling: the membrane is very easy to position, pin, and suture, which is a weak point of other products. These often tear, degrade prematurely, or cause problems during placement, especially if the membrane has excessive tip elasticity and recedes.
This is not the case with Membrane Flex: it has good dimensional stability and, at the same time, practical flexibility, which makes it much easier to use. Compared to collagen membranes from other manufacturers that we have used in the past, the Straumann® Membrane Flex scores particularly well in terms of intraoperative handling. It allows flexible application as it is not side-specific and can be used both dry and hydrated without sticking to gloves or instruments. This facilitates precise placement and repositioning. The membrane adapts naturally to defects and contours, making it a reliable option for daily use in regenerative therapy. It also impresses with its high tensile strength thanks to minimal cross-linking of the porcine peritoneum, which enables secure fixation with sutures. Although I do not yet have a large number of cases to report, healing in my cases to date has been unremarkable and clinically convincing.
What is your proven procedure when using a membrane in vestibular defects, particularly with regard to adaptation, fixation, and stability during the procedure?
I follow a standardized procedure for typical vestibular defects: I would always cut the membrane to size in a dry state before inserting it into the defect. As soon as the membrane comes into contact with fluid, it loses its dimensional stability and becomes difficult to handle – it then behaves like a wet washcloth and collapses.
To define the appropriate size and shape of the membrane in advance, we use a custom-made template, e.g. made from the aluminum packaging of the biomaterial. We place this over the defect area and adjust it exactly to the width and length. This allows the membrane to be cut precisely while dry. In the next step, the membrane is first fixed basally with two pins. I then insert the augmentation material – either autogenous bone or a substitute material – into the defect and position the membrane over it.
The membrane is tensioned crestally with an absorbable suture and additionally fixed via periosteal relief and mobilization of the mucosa from the lingual or palatal side. Finally, the soft tissue is closed without tension. The membrane thus lies stable over the augmentation and enables reliable regeneration.
Looking back over the past year with the Straumann® Membrane Flex, what would you particularly highlight? What has convinced you about the membrane in the long term?
Looking back, it was above all the good workability that stuck in my mind. The membrane is very easy to handle – it is tensile, stable and can be fixed reliably, either by suturing or pinning. The intraoperative handling is also impressive: it can be cut to size, positioned cleanly over the defect and is easy to locate even after some time. For me, it is therefore a practical, solid solution for GBR – especially in cases where a combination of stability and flexibility is required.