Treatment of grossly resorbed mandibular ridge Dr.Mohammad Al Sayed 29/4/2008

2.Prosthodontic treatment * History and examination: - Medical history - Dental history - Examination of the existing dentures. * Intraoral examination a. The health of the ridge and the surrounding tissue. b.Vestibular depth.

Alveolingual sulcus: The alveololingual sulcus (the space between the residual ridge and the tongue) extends posteriorly from the lingual frenum to the retromylohyoid curtain. Part of it is available for the lingual flange of the denture. The alveolingual sulcus can be considered in three regions: - Sublingual crescent space. - sublingual fossa. - Retromylohyoid fossa.

c. Tonicity of the tissue. d. Tongue position. e. Buccal shelf. f. Buccal pad of fat. g. Identification of the interarch-space problems. * Radiographic examination.

Impression objectives: 1.A broad area coverage, with maximal denture base extension, deceases the force experienced per unit area of the mucosa beneath the denture likehood of its trauma. However in the grossly resorbed ridge the area of tissue available for support is reduced and extension of the base is critical to avoid interference with movement of the border structures. 2.A controlled pressure technique would decrease occlusal loading over the affected area and distribute forces more to primary support areas like the mandibular buccal shelf. 3.Impression technique should ensure that the denture fitting surface is smooth and does not cause frictional abrasion of the underlying mucosa.

Impression materials and techniques: - An impression material with adequate flow properties should be used to void uneven pressure during impression procedures that could result in a localized rebounding effect on the compressed tissues under the denture and/or “sore spots”. Either of these conditions could result in uneven seating of the finished denture and loss of intimate tissue contact. - The impression material should also provide adequate reproduction of surface detail to prevent small irregularities capable of entrapping air. - The elimination of dislodging forces by accurate border molding that prevents overextension should be accomplished.

- A slight generalized pressure on the soft tissues is desirable - A slight generalized pressure on the soft tissues is desirable. Use of a moderately viscous light bodied impression material with sufficient flow, elimination of full arch relief spacers in the tray and use of a nonperforated custom tray are among those modifications in in technique that can lead to an impression recording of the tissues in a mildly displaced form. - Special impression techniques to determine accurately a denture extension with reference to functioning tissue at its denture border have been evolved.

- Complete lower dentures made from static impressions and dentures that are not stable may be used effectively for making dynamic impressions. After the occlusion of the denture (which is to serve as a tray) has been tested for deflective occlusal contacts, the border extension are adjusted and severe undercuts are reduced. The tissue conditioning material is mixed carefully and placed over the entire impression surface of the denture. The denture is inserted into the mouth. After the material has set for 3 to 4 minutes, the patient sucks and swallow several times, and the impression material is allowed to cure for 10 minutes.

Fibrous tissue “Flappy ridge” Overlying the residual ridge, may compromise denture stability and special techniques have been devised which either load other sites and avoid displacement, or surgically remove such redundant tissue.

Vertical dimension of occlusion: In cases of marked ridge loss the vertical dimension may be further reduced in order to place the occlusal table closer to the alveolar ridge and create a more stable lower denture by reduction in the height of the denture.

Denture occlusion General considerations 1.the teeth should be set over the center of the ridges so that the forces applied to the teeth when occluding and chewing are directed straight through the ridges to seat the dentures firmly on them. 2.Destabilizing forces from the lips, cheeks, an tongue act on the denture polished surfaces and dental arch. Additional forces will be generated by the teeth during contact.It is accepted that the occlusion should be balanced in centric relation. 3.Increased denture stability , together with reduction in force per unit area applied to the mucosa, may be achieved with a reduction in length of the occlusal table by reducing the number of teeth.

4.the lower denture should be made narrow in the premolar area. 5.stresses to the anterior ridges can be reduced by removal of anterior tooth contacts in centric relation closure. Shaping of polished surface -the buccal surface of the lower denture should be concave,to face up and out. the mandibular lingual flange should slope toward the tongue. The use of soft liners Post –insertion follow-up

Surgical management 1.enlargement of denture-bearing areas a.vestibuloplasty b.ridge augmentation 2.implants a.subperiostal b.transosseous c.endosseous

Ridge augmentation by subperiosteal injection of hydroxyapatite