Two different designs of the 4-implants used for assisting mandibular complete overdentures: Clinical evaluation

Objectives: The aim of this study was to compare between two different designs used for assisting mandibular complete overdentures. One design was  with four axially placed implants and the other was "all-on-four design" concerning peri-implant soft tissue health and implant stability.
Methods: Ten completely edentulous male patients were eligible for the present study. All patients received mandibular complete overdentures supported by 4 implants opposed by single maxillary dentures. The patients were randomly classified into 2 groups. Two axially placed implants were inserted at canine areas for both groups. Two implants were placed posteriorly, for group A two axially parallel implants in 2^nd premolar regions while for Group B the patients received two distally inclined implants of 30^o in the 1^st premolar regions. All implants were attached to the mandibular overdentures through ball and socket attachments. Peri-implant soft tissue health and implant stability evaluation were carried out immediately, 3 months and 6 months after insertion of definitive overdenture.
Results: There was no significant difference between both groups when comparing peri-implant gingival, plaque, bleeding indices, probing depth and implant stability. Nonetheless, there was an improvement of all scores values and measures of all tested aspects through all time intervals in each group. Better values were noticed for anterior implants compared to posterior ones for both groups through all time intervals.
Conclusions:The results of the study boost that both designs; four axially inserted implants and All-on-four design could be successful treatment options for assisting mandibular complete overdentures. Yet both designs revealed comparable results with respect to the standard levels of peri-implant soft tissue health and implant stability, All-on-four design could be a promising alternative when being indicated.
Recommendations: More long term studies of variant evaluation methods are thus required to validate the results of this study.