Dental bonding turning brown, did my dentist use older bonding? (Photo)

It is unlikely that the dentist used old or expired bonding material for your tooth. The expiration of the composite material would effect the texture and workability, not the coloring. It may effect the strength of the bonding or the attachment to the tooth. 
External stains such as your photo shows, are more likely due to a combination of dietary choices and the porosity of the bonding. Heavily staining foods/drinks such as coffee, red wine, tumeric supplements will stain a composite filling over time. A more porous filling/bonding cause by poor finishing and polishing will accept more stain. I recommend you return to have the bonding polished and ask for a sealer to be placed over it to offer additional protection. And of course, to minimize further stains, watch what you eat and drink. 
Dr Ebner

tommy140,It definitely looks like there is a yellow tooth on that side.  Correctly placed and polished, composite bonding should look pretty good for a few years.  It is possible that either older bonding was used or that it was not correctly polished, but that would be unusual I would think.  If you are seeing a conscientious dentist who has skill in the are of esthetics and cosmetics that shouldn't be the issue.  My suggestion is you go back and ask what is happening.  It is an easy fix.  Also, I am not sure why you are trying to avoid porcelain veneering, but using the newer porcelain restorations are really great and have a much higher longevity factor as well as being very natural and stain resistant.All the Best,

Hi:It's difficult to tell if the bonding material is an issue or you are consuming too much staining food or drinks such as coffee or black tea.  If it is external staining, by polishing the bonding you should capture the initial color.Best,Dr. Maddahi

Dear tommy140, There are a variety of different bonding materials and different polishing systems. I have used a microfill composite for cosmetic bonding for thirty years because it holds a fantastic long lasting polish. The newer nanohybrid composites are supposed to combine the durability of hybrid composites with the polishability of microfills. My experience is that they fall short when it comes to holding a polish, and I continue to use the old microfills with continued excellent results. The discoloration of your teeth is probably due to a roughened surface which is either due to a hybrid composite losing its initial polish or a polishing system that did not provide a glass like surface. That brown stain should be superficial and easily polished off. It is related to the type of material, it will return and then the only long term solution would be its replacement. However remember that no bonding material will last more than 3-10 years, but porcelain veneers will last indefinitely.