Principles of alveolar bone preservation
The volume and shape of the jawbones are maintained through physiological masticatory pressure transmitted via the periodontal tissues. For this reason, the baseline strategy of pre-prosthetic surgery is to save as many teeth as possible, which will later serve as abutments for prosthetic structures.
If extraction is inevitable (especially multiple extractions in severe periodontitis), the clinician must use minimally invasive techniques to prevent bone loss. To prevent post-extraction atrophy and ensure proper healing, the following approaches are used:
- Smoothing the edges: bone projections and sharp alveolar edges are removed with a bur or rongeur forceps.
- Filling the defect: osteoplastic materials are placed into the socket.
- Isolation: primary closure using a mucoperiosteal flap is considered the ideal option. If conditions for plastic surgery (using membranes or free gingival grafts) are lacking, the gingival edges are simply approximated with sutures, placing an antibacterial agent (e.g., Alvogyl) between them.
Tooth-conserving procedures: hemisection and root amputation
When the pathological process (root caries, periodontitis, iatrogenic perforation, or overfilling of the root canal) affects only one root of a multi-rooted tooth, partial removal is performed.
Hemisection is used on mandibular molars (provided the second root is intact).
- Using fine burs or discs with continuous water cooling, the crown and the furcation area are sectioned.
- Most often, the mesial root is removed along with the adjacent part of the crown.
- The remaining distal root is used as an abutment for a fixed partial denture (bridge). The procedure must be performed extremely carefully to avoid luxation of the preserved part.
Root amputation is indicated for maxillary molars, since trifurcation makes hemisection ineffective here.
- Usually, one of the buccal roots is excised. The palatal root is almost always preserved as it bears the main load-bearing function.
- Access is created through the outer wall of the socket by raising a flap and trephining the bone with a bur under cooling.
- Crucial rule: the root must be removed with a perfectly smooth surface. Any remaining burrs will inevitably provoke chronic inflammation and tooth loss. The wound is closed with a flap to form an aesthetic gingival contour.
Soft tissue and bone contour correction
For high-quality prosthetic treatment (e.g., when using posts), correction of the gingiva around the remaining root is often required. The free gingival margin is excised with a laser (no sutures needed), a scalpel, or scissors (hemostatic sutures required).
If the root is destroyed deep beneath the bone level (due to trauma), working with the gingiva alone is insufficient. In this case, part of the alveolar bone wall is carefully removed using a bur. Afterward, sutures and a periodontal dressing must be applied to isolate the prepared tissue.
Management of the alveolar ridge:
- Excision of excess gingiva: performed using two converging semi-oval incisions. The tissue is thinned, excess is removed, and sutured. However, prior to this, the surgeon must evaluate whether this 'excess' can be used for ridge augmentation.
- Alveolectomy: bone irregularities do not always hinder prosthetics. Often they act as additional retention points, increasing the stability of removable laminar dentures, or serve as a good foundation for subsequent bone grafting.
Briefly: answers to topical questions
What are the contraindications for hemisection and root amputation?
Contraindications for hemisection and root amputation of a tooth are identical and depend on the condition of the surrounding tissues. They include:
- Resorption — resorption of the interradicular septum.
- Bone pockets — presence of deep bone pockets.
- Mobility — grade III–IV tooth mobility.
- Perforation — perforation of the preserved root.
- Hypercementosis — hypercementosis in the area of the preserved root.
What specific classes of osteoplastic materials are used to fill the socket after tooth extraction?
Four main classes of osteoplastic materials are used to fill the socket of an extracted tooth. The following groups are distinguished:
- Autografts (Autograft) — the patient's own bone.
- Allografts (Allograft / Homograft) are bones of human origin that have undergone special processing.
- Xenografts (Xenograft) — animal-derived bone.
- Alloplasts (Alloplast) — synthetic bone materials.
What vestibuloplasty techniques are used during surgical preparation for prosthetics?
Various vestibuloplasty techniques are used during surgical preparation for prosthetics to deepen the oral vestibule. The main methods include:
- Kazanjian's technique (Lip Switch) — using a repositioned mucosal flap from the lip.
- Edlan's technique (Edlan) — modification involving the relocation of the periosteum to close the wound.
- Obwegeser's technique (Obwegeser) — submucosal vestibuloplasty.
- Using grafts — application of free mucosal or skin autografts, as well as allografts.
- Using a silicone complex — a high-tech outpatient technique.
- Using a stent graft — application of a stent wrapped in a skin autograft.
What types of barrier membranes are used for guided bone regeneration during socket grafting?
Resorbable and non-resorbable barrier membranes are used for guided bone regeneration and socket preservation. The following types of membranes are used:
- Polymeric — made of resorbable polymer.
- Collagen — made of synthetic collagen.
- Bone — made of freeze-dried bone.
- Titanium — non-resorbable membrane made of pure titanium.
Class and exam questions
Why is an effort made not to touch the palatal root during amputation in the maxilla?
The palatal root performs the main supporting function for the upper molars. If it is extracted, the tooth is highly likely to lose stability.
What to do if the root is destroyed below the socket bone level?
In this case, isolated gingival excision is insufficient. Partial removal of the bone wall is performed using a bur, after which the wound must be sutured and a periodontal dressing applied.
Is it mandatory to smooth all tubercles and irregularities of the alveolar ridge prior to prosthetics?
No. In a number of cases, such irregularities contribute to better fixation of removable dentures by creating retention points, or serve as a support during bone grafting.
What is the difference between hemisection and root amputation?
Hemisection involves sectioning the crown and removing the root along with its corresponding part of the crown (used on mandibular molars). In root amputation, only the root itself is removed through a trephination opening in the socket wall (used on maxillary molars).
What else to study on this topic
- Socket grafting materials: types of membranes and autografts
- Specifics of working with bone tissue in severe periodontitis
- Hemostasis protocol during laser and surgical soft tissue gum correction
- Indications for alveolar ridge augmentation prior to prosthetics
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Other topics in "Chapter 16. Surgical Preparation of the Oral Cavity for Prosthetic Treatment (A.V. Shchipsky)"
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