Microscopy zooms in on dentistry

The International Association for Dental Research General Session begins next week in Miami, Fl. I was surprised by how much of the research presented there makes use of microscopy. Quite a few methods are represented:

• Atomic force microscopy (AFM) method for studying anti-plaque benefits of the toothpaste ingredient sodium tripolyphosphate (STP)
  
• Colgate uses confocal laser scanning microscopy to study its new Total toothpaste
  
• The ability of dental restoratives to stay glossy after brushing studied with AFM and optical scanning
  
• Polarized light microscopy characterizes enamel remineralization
• Electron microscopy analyzes nanoparticle distribution in a new class of endodontic materials 
• Confocal Raman microscopy measures water content in the dentin/adhesive interface (a good overview of confocal Raman microscopy is at http://tinyurl.com/dhwo3t)

I was looking for someone using a multiphoton microscopy method for dental applications, but I didn't see any. Do you know why multiphoton isn't getting used more in this field?