I've used both Canon and Nikon for clinical dental photography. In my personal opinion, there is not 1 but many reasons why dentists must be wary of NIKON equipment for dental photography. In this episode I have enumerated all the drawbacks present in the NIKON system. I thing that I forgot to mention was the cost factor.
In the cost of 1 105 mm Nikon Macro lens I could buy 1 Canon basic DSLR + 100 mm macro lens.