I was in your spot about 9 months ago. I was shadowing a dentist for about a month or so and one of his assistants left to work at another office. They offered me a job I took it. Here is what you should expect. Of course your experience will differ based on the skill level, ambition, and temperment of the dentist you work for. There are two dentists in the office where I work and their styles are very different.
In the office where I work we have two dentists, 3 hygienists, 3 assistants, and two front office staff.
As an assistant you arrive early to run the lines (wash out the disinfectant), set up the rooms, turn on the radio etc. The doctors arrive about the same time as the first patient. In our office we have one assistant per doctor and a floater to assist the hygienists with periodontal charting, help set up and break down rooms, help seat patients, make up trays and steralize instruments.
The patient arrives and the front office will buzz. You go to the front grab the chart and call the pt back to the room. You put the bib on the patient, open the intstruments, take any needed X-Rays, double check the room set up and then let the doctor know the patient is ready. The doctor comes in chats for 2 minutes with the patient, looks at the chart and X-Rays lays them back and the fun begins.
If it is an initial exam you will have already taken a full mouth series (18 X-Rays). You will next take down the existing teeth and dental work as called off by the doctor, chart periodontal depths, and results of soft tissue and TMJ exam. You will also write down important info the doctor notes during the exam and any work that will need to be done. You next, while the doctor is chatting with the pt, make up the treatment plan and print it out so the fron desk staff has it and the end of the apt. When the doc is done he says his good byes signs the chart and you walk the pt out.
If you are doing a restoration you will seat the pt, put bib on pt, open instruments and let doc know what room pt is in. The doc will come in and chat for 2 min and then set up to anesth the pt. One doc I work for likes his carples of anesth warmed up in H2O the other doesnt. One likes me to hand him the topical and syringe the other doesnt. If you work for more than one doctor you will find it difficult at first to keep there their routines straight. While the dr is delivering the anesth you will be ready with your suction and air/water syringe. When s/he is done you will wash out the pts mouth unless it is an extremely anterior tooth. While the pt is getting numb you will double check room, seat other pts, sterilize instruments etc. Once numb you will start the restoration. You will suction while the dr is using the high-speed drill and use the air water syringe to keep the mirror from fogging. You will also use your suction to protect the pts tongue and retract cheeks when needed. Be sure not to place your suction in the center of the pts mouth towards the back b/c the pt will gag. It is best to place it near the location where the doc is working or nearly resting on the back molars. Be sure not to block the drs view of his work area and once you have your suction in place to not move it all around. You will find that at time you can not keep the mouth from filling with H2O. Dont worry. There will be breaks in the action when you can swoop down and suction out that H2O. Once the doctor is done drilling he will has for caries detector. Put it on a swab and hand it to him (holding the swab a the extreme end so he can grasp it). He will put the caries detector in the prep and hand the swab back. You take it, put it down, and prepare to either suction as the doc washes the prep or you yourself washing and suctioning, and drying the prep. If there is still decay he will continue. If not he will be ready to place the composite. In my office we use SE Bond, Tetric flowable and Filtek. You will hand the doc the SE Bond PRIMER on a swab. He will place it on the tooth and let it sit 20 to 30 seconds. Next you will hand him the SE Bond. Once placed on the tooth you will cure it with the light for 10 seconds. Most likely the dr will next want the flowable (make sure you have the tooth color already picked out so the right flowable is ready). You hand him the flowable and keep a 4x4 in your left hand. He places the flowable and hands you it. You wipe the tip, place it between your middle and ring finget with the handle out. The Dr. may use the explorer to thin the flowable. If he does he may hold the instrument out for you to wipe the tip. If so wipe it without your glove touching the instrument. You will then cure the flowable for 20 seconds with the light. The Dr. may grab the flowable from your hand while you are curing so that he can use it again or he may decide he next wants the filtek. Some dr will get their own filtek others want you to get it for them. You squeeze it out on a pad and cover it. Grab the flat placer, turn off the overhead light and give the flat placer and hold the pad with filtek out so the dr can take what he wants. You set the flitek down and grab the burnisher and a 4X4. Dip each end of the burnisher in SE Bond and hold it ready to give to the dr. The dr will remove any excess filtek and hold out his instrument for you to clean. you wipe it. When he is ready for the burnisher you hand it to him and take the flat placer. He finishes shaping the filling and when done you cure the filling for 20 seconds. The dr. next uses the high speed to finish shaping the filling. You will suction b/c he will most likely use the high speed. You will be ready with the bite paper to check the pts bite. Tell the pt to bite down, tap, grind side to side etc. This marks the occlusal surface for the dr. He will then make additional adjustments with the hight speed and slow speed and finish up by polishing the filling with disks.
You chart what you did and the dr signs the chart and you walk the pt out.
If you are preping a crown you pretty much suction and retract. However, remember to take the initial impression for the temporary before the dr comes in. Protect the tongue when suctioning b/c if the burr gets ahold of it it will eat it up. Once the tooth is prepped the dr will take the final impression. In our office we use relatively quick setting impression material. The dr getts the light and you get the heavy. Once he has dried the tooth he will tell you to start and you will fill the impression tray with the heavy material while he puts the light around the tooth. You hand him the tray and the pt bites down on it. When it hardens he will take it out and check it. If it is ok you will make the temporary by putting integrity (tooth colored material) in the initial impression tray and asking the pt to bite down on it. Once dry you shape it and check the bite and seat it using temporary cement. You clean off the cement, chart what you did, fill out the lab slip, and walk the pt out.
When the crown comes back from the lab you will take off the temporary, clean off the cement, try in the crown and check the margins and contacts and bite. Some dentists will allow you to adjust the bite others will not. Once done let the dr know the pt is here. He will come in and do the final check. You mix the cement, put the cement into the crown (to the drs liking), hand the crown to the dr occlusal surface up. He will take it place it on the tooth, you will hand him swab so he can clean any cement that flows out. Next he will take the 4x4 you hand him and have the pt bite down. Once set you will clean off any excess cement and chart and walk the pt out.
Root canals are pretty fun and relaxing. All you do is hand the files to the dr, clean them off, take a couple X-Rays, suction a bit, etc.
Sorry for the long reply. If you want specific info PM me.