Bone grafting in periodontal therapy
Verlorenes Knochengewebe kann mit Eigenknochen aufgebaut werden
With larger defects, cleaning alone is not enough. The build-up of bone is then supported deliberately – with guided tissue regeneration, GTR for short, and with materials that serve the body as a scaffold.
Which material
Lost bone can be replaced with the patient's own bone – harvested elsewhere and particularly well accepted. Alternatively, bone substitute material stimulates the body's own bone formation and acts as a guide along which new bone grows.
The decisive point
Bone grows slowly, mucosa quickly. Without a countermeasure a long junctional epithelium would grow into the defect from above and enclose the tooth in connective tissue – it would then not be firmly anchored. Preventing exactly that is the point.
Membrane technique
The most effective way to prevent this is to cover the root surface with a membrane. It keeps the fast-growing epithelial cells away from above and gives the slower tissues of the tooth-supporting apparatus the time they need.
This method was long the first choice. Enamel matrix proteins have since added a second way of forming new tissue – depending on the defect, one, the other or both are used.
Clinical experience
Enamel matrix proteins are well researched and have been used worldwide in more than a million patients. They enable the body to re-form the tooth-supporting apparatus – all three of its components:
- the root cementum
- the fine bundles of fibres connecting root cementum and jawbone
- the jawbone itself
The build-up begins immediately after treatment and continues over a longer period – often for more than a year.
Exposed tooth necks
When the gum recedes, this is called a recession. The exposed tooth necks are not merely a cosmetic problem: they often react sensitively to cold, heat and sweetness.
Such recessions can be covered. Here too enamel matrix proteins help – applied once, they restore both function and appearance by biological means.
Allogeneic bone block augmentation
Allogeneic bone blocks can be used as an alternative augmentation method to rebuild bone lost to periodontitis. Block-shaped bone grafts are needed in allogeneic bone block augmentation wherever larger augmentations and extensive defects call for adequate volume stability during the healing period.
Autogenous bone block grafts in periodontal surgery are taken from the patient intraorally – blocks from the chin region or the posterior region of the lower jaw. They have proved their worth thanks to good tolerance and a high probability of success. One drawback of autogenous grafts is the greater burden on the patient, since a second operation is required to harvest the bone.
An alternative that spares the patient any harvesting is the allogeneic bone graft, obtained from deceased or living donors. The bone material usually comes from the femoral heads of human donors who are immunologically unobjectionable. After special processing it is supplied by tissue banks.
Bone reconstruction after a tooth is removed
Once a tooth has been removed, the jawbone shrinks at that spot. With a conventional bridge, for which the neighbouring teeth have to be ground down to carry it, a gap can form beneath the bridge after healing. Besides looking unattractive, such a gap makes cleaning the teeth and keeping the mouth healthy more difficult.
If an implant is planned, it can often be placed later only after elaborate bone grafting, because an implant needs sufficient bone to sit firmly.
Immediately after the extraction there is an opportunity to preserve and build up the tissue. Bone-preserving measures can accompany the planning of a bridge or precede an implantation, so that a durable and aesthetically demanding result becomes possible.
If there is no acute infection after a tooth has been removed and no immediate implant is placed, the socket left behind can be filled with bone substitute material.
If the bony wall of the socket is damaged, a tissue membrane may additionally be needed. The membrane prevents soft tissue from growing in and allows the bone to heal undisturbed.