Preprosthetic surgery is the surgical improvement of the denture bed in the upper and/or lower jaw.
Due to tooth loss and lack of loading on the alveolar bone (jawbone), atrophy (recession) of the bone occurs. Often, the mobile mucosa reaches close to the alveolar ridge. As a result, the retention of dentures is often unsatisfactory, as the low bone height and adjacent mobile ginigva (gums) cause the denture to fit poorly and come loose quickly.
Deeply inserting ligaments in the vestibule (front of the mouth) or the lingual frenulum can also negatively affect the retention of dentures.
Indications (areas of application)
Preprosthetic surgery is used to improve the prosthesis bearing. A well-fitting prosthesis contributes significantly to maintaining quality of life by restoring speech, function, and esthetics.
Surgical procedures
Different procedures are used to improve prosthesis fit, depending on the situation at hand.
Interfering ligaments on the lips, cheeks or tongue are surgically corrected so that they do not interfere with the prosthesis during movement and no painful pressure points are created there.
In the presence of a floppy ridge (connective tissue transformation of the alveolar bone) or the presence of flap fibromas (irritant fibromas, denture margin hyperplasia caused by ill-fitting dentures), there is also an indication for surgical improvement of the denture bearing. In both cases, removal of the excess tissue is usually combined with vestibuloplasty (oral vestibuloplasty).
Corrections to the bone are necessary if sharp bone edges, exostoses (bone protrusions), e.g. in the form of the torus palatinus (bone protrusion in the middle of the palate) or also a strongly pronounced linea obliqua (bone edge on the outside of the lower jaw) disturb the fit of the prosthesis and lead to painful pressure points.
Vestibuloplasty in the upper jaw is a surgical procedure to deepen the oral vestibule. This indirectly raises the alveolar ridge and improves the retention of the dentures. A distinction is made between open vestibuloplasty, in which the tissue is detached via a circular mucosal incision and reattached further cranially (above), and the closed method according to Obwegeser.
The disadvantage of the open method is the subsequently exposed periosteum (bone skin), which is left to open granulation (healing wound). This can lead to more severe scarring and thus to a renewed loss of alveolar process height. Alternatively, these areas can be covered by free mucosal grafts, for example from the palate, to avoid this.
In the closed method according to Obwegeser, the mucosa is tunneled and the underlying soft tissue and musculature are relocated cranially (above).
In the mandible, in addition to vestibuloplasty, it is often necessary to lower the floor of the mouth in order to improve the prosthesis fit in the long term. The floor of the mouth, the mylohyoid muscle and the vestibule are moved caudally (downward). Here it is enormously important to observe the course of the mental nerve (mandibular nerve).
If the floor of the mouth is to be deepened, especially in the posterior region, a retromolar lowering of the floor of the mouth can be performed. In this case, the mucosa of the floor of the mouth and the attachment of the mylohyoid muscle are moved caudally (downward).
Following the above vestibuloplasty or oral floor lowering methods, either the previously extended (lengthened) prosthesis or a dressing plate is used until the situation has healed sufficiently for a new prosthesis to be fabricated.
