THE EFFECT OF TWO PROTECTIVE OCCLUSAL SCHEMES OF IMMEDIATELY LOADED MINI-IMPLANT SUPPORTED MANDIBULAR OVERDENTURE ON MASSETER MUSCLE ACTIVITY AND RIDGE KERATINIZATION

background:  Lingualized and monoplane occlusal (LO and MO) schemes are the most protective schemes regarding the prognosis of the immediately loaded mini-implants. The occlusal scheme in complete overdentures is a prime factor that affects masticatory efficiency that will subsequently determine the forces transmitted through the denture base to the denture foundation thus affecting ridge keratinization reaction as well as the degree of mini-implant osseo-integration .
 
material and methods: Twenty completely edentulous male patients were divided into two equal groups. Complete upper and lower dentures were constructed for all patients with their artificial teeth set following the LO scheme for group I patients and the MO scheme for group II patients. Four mini-implants were installed interforaminally and immediately loaded in each patient. Electromyographic (EMG) records, keratinization index (KI) values and periotest values (PTVs) were collected at the time of denture delivery, one month and four months after denture delivery.
 
results: Median EMG and KI values for LO and MO groups showed a significant increase after 1 and 4 months. Similarly, the median PTVs for LO group increased along the follow up periods showing a significant increase after 1 and 4 months. However, the median PTVs for MO group showed a perculating pattern showing a significant increase after 1 month followed by a significant decrease after 4 months of denture delivery. Changes in median KI values for MO group showed a significant difference than that for LO group after 1 and 4 months. Changes in median PTVs for LO group showed a significant difference than that for MO group after 4 months only. A significant inverse correlation was noticed between changes in EMG records and PTVs as well as between PTVs and KI values after 4 months of denture delivery