While the guidelines do have a purpose, they can cause a lot of unnecessary stress and worry for moms. Simply because you're concerned about it tells me you're a hands-on mom and probably naturally provide your son with the love, care and appropriate developmental stimuli. At 10 months, all you need to do is meet his needs, help him feel secure, talk to him, sing to him, read to him, and narrate your day around him. After that, he'll take what he wants and leave the rest. An active 10 month old boy is often more concerned with physically conquering the world around him than with letting anyone know what he's thinking, and much less bothering to verbalize it. Also at this age, kids have a very focused approach to development -- they often ignore one skill as they are developing another. If he's close to walking, that's all he can focus on right now. Chances are good that as soon as he takes his first steps, you'll hear him pick up a few words, or begin saying those things the experts say he's "supposed" to say.
For a broader range of "normal" development, I'd look at the ECI information rather than what the pediatrician uses.
As far as teeth - we started both of ours at 6 months (with or without teeth). Every evening when we'd brush our own teeth before bed, we made it a family affair. We sat the baby on the counter in front of the mirror and handed him/her a wet baby toothbrush to gnaw on. They loved being included in this experience! We'd make all sorts of sound effects ("eeeeeee" and "ahhhhhh" and "ohhhhhh"). It wasn't long before the baby would mimic our actions (and sound effects!). After several days of toothbrushing fun, we attempted "mommy's turn" to brush the baby's teeth. We had to make it fun, so I'd say "OK, mommy's turn! I want to tickle your teeth!" and put my hand over the baby's hand (they usually had a death grip on the brush), and just try to swipe the brush across their teeth a little, then say "Bye-bye toothbrush" and put the brush away. Initially, parting with the toothbrush would upset the baby, but very soon they were readily letting me have a turn to brush their teeth, and saying "bye" to the brush as well. A good distraction to letting go of the toothbrush is picking them up to switch off the bathroom light.
Now, at 2 and 4, they both open wide for me to brush their teeth well, and they have both had dental checkups with no problem.