Aim of the study: The current study was conducted to evaluate the clinical performance of PEEK 
polymeric material used as a Computer-aided design or computer-aided manufacturing (CAD /CAM)
posterior fixed functional space maintainer clinical performance. Methods: A randomized clinical 
trial was carried out to evaluate PEEK polymeric materials used as CAD/CAM posterior fixed 
functional space maintainers in terms of clinical performance in thirteen children with premature 
unlateral loss of the first primary molar were selected. Assessment was done according to the 
modified United States Public Health Service (USPHS) criteria at 3, 6 and 12 months. Data were 
statistically analyzed between different times at P<0.05 level of significance. Results: Analysis of 
data regarding success rate in PEEK at 3,6 and 12 months revealed that there were insignificant 
differences (p >0.05) regarding all study parameters: color match, anatomic contour, surface texture , 
marginal integrity, gross fracture indicating no change in PEEK SM during 12 months follow up.
Conclusion: PEEK CAD/CAM space maintainers represent valuable alternatives to conventional 
space maintainer with superior clinical performance.