Marginal Accuracy of Milled Versus Cast Cobalt Chromium Alloys in Long Span Implant-Supported Frameworks: A Systematic Review and Meta-analysis

Aim: To assess if milled cobalt chromium (Co-Cr) alloy offers significantly better marginal accuracy than cast Co-Cr alloy for screw-retained long-span dental implant framework. Materials and Methods: A search PICO was formulated using suitable keywords and an electronic search was initiated. The databases of PubMed, Cochrane Library, Google Scholar and Embase were searched for related articles. Bibliographies of randomised control trials and reviews, identified in the electronic search, were analysed for studies published outside the electronically searched journals. Electronic search identified 26 studies. A total of 16 studies were eliminated after reading the abstracts. Out of the remaining 10 studies, 3 were eliminated based on the inclusion and exclusion criteria, and finally 7 studies were finalised for systematic review. Results Data were extracted from the included studies and analysed. The obtained data were suitable for meta-analysis, which showed an overall effect size z = 4.97 (P < .001) at 95% CI showing a significant statistical difference between milled and cast Co-Cr frameworks. Conclusion: Milled cobalt chromium frameworks are significantly more accurate than cast frameworks for long-span implant-supported frameworks used in dental prosthetic rehabilitation. More randomized controlled trials need to be conducted with a larger sample size to get a more authentic conclusion in a clinical scenario.