Leave or not???

Life is not work! Your time is just as valuable as that of another employee (even if they need to collect a child!) Try not to be cross with your other staff member, teach them patiently but don't do their sign offs if she is IC Lead (it sounds like not everything is getting done). The employer may be giving unfair treatment but don't let their error of judgement cause jealousy between the two of you.

As the economy approaches full employment we as dental nurses need to say no to being kicked around.
Being expected to work for free is 100% not on. (I consider it theft. I became very resentful when in this situation). In fact most dentists are too busy/stressed even to think about the issue because it does not affect them - it is up to us to bring it to their attention.
Inform your boss by email or letter (it needs to be in writing) you expect to be paid setup and cleanup time. If he/she is refusing to pay the extra time then just do your paid hours and give your dentist or therapist the list of tasks they will need to come in early/stay late and complete. (As self employed their hours are not fixed.)
He/she will not dare to dismiss you, you can go to employment tribunal and win.
This problem is amazingly common. If you give your notice and move to another job the same situation may be there. We all need to grow a backbone and insist on being treated in a correct manner.

I have been a dental nurse for the past 9 years, working in a few different dental practices basically trying to find the one for me!, I started in my current practice 4 months ago, when i first came here i loved it very different from practices i have worked at before mainly private and what we offer is different from in our area. My practice is a one man band, one therapist then me and there was another nurse who was also senior who ended up leaving which then left me running between both dentist and therapist doing all csu and even some days reception all in one day it got to the point where i was coming in 45 mins early to set up the whole practice and leaving 45mins late on a night(which i dont get over time for), i also took over most of the senior roles (which i didnt ask for). The dentist who owns it personally is lovely, however i never get thanks for what i have done only told off for what i havent done as i do not have the time!! Now we have a new nurse who has double my experience and has been brought in on more money per hour than me (totally understand) however before she started they praised how amazing she was going to be and how she will take over senior roles she has been here 6 weeks and still cannot work with our owner on her own im still having to shadow over her and help her which is making more jobs for me to do she claimed to be senior in her old place however does not know how to do any CSU tests e.g protein ect. . I feel working here has really taken it out of me and what i am expected to do without extra pay, as she has a child and cannot stay back it is expected of me staying late on a night without pay or over time for this. I am really considering handing my notice in because i have to give 8 weeks, The staff turn around here is shocking, i did not know this before hand the old senior told me, Just wondering if anyone has the same problem and how they solved it ? Its making me not want to be a dn anymore and making me really unhappy as i feel like my life is becoming work!!