Amr Mohamed Shawky1, Mohammed M Fouad2,RadwaM Emera3, Moustafa A Neamat-Allah 4.
1Dentist – Ministry of Health – Egypt.
2Professor of Removable Prosthodontics, Faculty of Dentistry, Mansoura University, Egypt.
3Associate Professor of Removable Prosthodontics, Faculty of Dentistry, Mansoura University, Egypt.
4Associate Professor of Biochemistry, Faculty of Medicine, Mansoura University, Egypt.

Abstract:
Objectives: The aim of this study was to compare the metabolic activity around implants between four axially placed implants and “all-on-four" designs used for assisting mandibular complete overdentures.
Methods:Ten healthy male completely edentulous patients of age ranging from 50 to 60 years were selected for this study.
 All patients received 4 implants used for assisting mandibular complete overdentures opposed by maxillary single denture. Each patient
received four implants using one-stage flapless surgical technique. The patients were divided randomly into two equal groups,
 Group A: Patients received four axially parallel placed implants in canine and second premolar regions and Group B: Patients received
 four implants (two parallel implants in canine regions and two 300 distally inclined implants in the 1st molar regions).All implants
 were attached to the mandibular overdentures through ball and socket attachments. Biochemical evaluation of peri-implant tissue was done immediately, 3 months and 6 months after insertion of definitive overdenture. This is done by measuring glycosaminoglycans (GAGs) and chondroitin-4-sulphate (C4S) levels in the peri-implant sulcular fluid.
Results:When comparing metabolic activities of anterior (or posterior) implants within each group in all intervals of study,
there was a significant decrease in total values of glycosaminoglycans and chondroitin 4 sulfate. When comparing between
 the two groups regarding the total means of GAGs and C4S around all implants along the T3 and T6 intervals,
 there was an insignificant difference.
Conclusions:Although the insignificant difference between the two groups, the four parallel axially placed implants can be considered more favorable design than the “all-on-four" design regarding the peri-implant metabolic activity for assisting the mandibular complete overdentures.