Patients received ball abutments on each implant without splinting for retaining an implant retained mandibular overdenture.

Stability was assessed using resonance frequency analysis measured with the Osstell device instrument. The Osstell unit records a numeric value of 1-100 which is referred to as the implant stability quotient (ISQ). The measurements were performed and 3 mean of three readings were recorded in each evaluation period.

Peri-implant probing depth refers to the distance between the gingival margin and the most apically probable portion in millimeters (mm). The peri-implant probing depth was measured using a graduated plastic periodontal probe. The probe was held parallel to the long axis of the implant and introduced to the peri-implant sulcus until slight resistance was felt. Measurements were made at four sites around each implant; buccal, lingual, mesial and distal. Probing depth of 1 mm or less was recorded as "1mm", and those exceeding 1 mm but less than 2 mm were recorded as "2mm" and so forth. The mean records for each implant were then calculated.

It is the distance from the junction implant/abutment to the most apically probable portion, in millimeters. Assessment of the clinical attachment level was performed simultaneously while measuring the peri-implant probing depth.

The peri-implant mucosal tissues around the implants were assessed using Apse's modification of Löe and Silness index. The criteria for assessment were:

0 =Normal mucosa, 1 =Mild inflammation, slight change in colour and texture, slight oedema and no bleeding on probing, 2 =Mild inflammation, redness, in all portions of gingival margin, 3 =Moderate inflammation, 4 =Severe inflammation. The gingival index was assessed at 4 sites around each implant (buccal, lingual, mesial and distal) the sum gingival index score was calculated from all these surfaces and then divided by 4 to obtain the gingival index for each implant. Indices of the three implants were added to each other, and then divided by 3 to get the mean gingival index for each case. A score from 0.1-1.0 reflects mild inflammation; 1.1-2.0 reflects moderate inflammation from, and 2.1-3.0 signifies severe inflammation.