A day in extraction clinic

With the hospital on higher restrictions we have shifted to emergency only and I spent a day in the extraction clinic today. I had some successes and some challenges and I will put my thoughts about some particular challenges below:

- When a lower molar is heavily carious and the caries on the buccal or lingual is subgingival, it can be difficult to get forceps around the tooth. If you still have one root that has solid buccal and lingual tooth structure i.e the caries is on the distobuccal aspect subgingivally, you may be able to fit a set of lower universal forceps on this good root to try and move the whole tooth. The upside is that you may be able to extract the tooth straightforwardly if the roots are fairly straight or there is bone loss. The downside is that if the caries on the weak root is too extensive, the tooth may section unfavourably and make access difficult.

- When you break a root tip you can use an Endo file to remove it when the canal is visible. I had difficult with an upper molar palatal root because the canal was quite calcified. Finding the right file size is important as if it is too fine then it will slip in and out of the canal and not engage and if it is too large it won't enter the canal at all. The aim is to have a file size slightly larger than the anatomical diameter of the canal so it can fit into the canal and engage the walls. Test the file on the part of the tooth that is extracted before messing about in the socket. The diameter of the root end of the extracted tooth will match the diameter at the coronal aspect of the retained root. Test with the file size you have chosen and see if it engages into the extracted tooth. You need a surgical suction right at the base of the socket. Good vision (direct or with a clean mirror) and put the endo file down the socket into the canal. Screw the file clockwise into the canal so it locks into the walls. Screwing it clockwise and placing mild apical pressure will guide the file down the canal so it engages the smaller diameter apex. Ensure that you thread floss through the small hole in the fie handle with floss long enough for your assistant to hold and prevent aspiration if you drop the file.

-When the sinus floor is low and appears to drop between the roots of upper premolars or molars it will be difficult for the local anaesthetic to diffuse across from the buccal injection site to anaesthetise the palatal root. It doesn't have to drop down far, just enough to contact the roots radiograpically. If the gingiva is numb when you test with a sharp instrument but the tooth is sore when you move the it then the bone, pulp or PDL still has sensation. If you suspect it is the sinus preventing diffusion, you need to put a good volume of anaesthetic on the palatal where you suspect the palatal root tip to be. My habit lately has been to inject for palatal anaesthesia only about 4mm from the gingival margin. However to reach the palatal root tip you need to inject about 10-15mm from the gingival margin. Once you have achieved soft tissue anaesthesia you need to come back and put quite a bit of pressure to add more anaesthetic as the palatal bone is quite dense and the palatal tissue doesn't allow much volume to be added. You will be able to add more volume the further you are from the gingival margin as the tissue is looser with salivary glands and looser, fatty tissue present. If the sinus floor doesn't encroach on the tooth roots, LA troubleshooting may include not enough volume, depositing the solution too shallow, or not waiting long enough for anaesthesia.

-Root tips almost always fracture at apical third as that is where there is usually a sharper curve in the root, that is where the tooth is thinnest (as it tapers down to a tip) and where it is more calcified (due to dentine sclerosis and deposition of apical cementum. Pay attention to what direction you are applying force when you hear a crack as it can help predict what shape the fragment is. It is rarely a horizontal root fracture and tends to be an oblique fracture with one aspect of the root higher than the other. For example the root I fractured was the palatal root of the upper 6. The root fractured with buccal movement of the forceps and the root tip fractured obliquely with the furcal side higher than the palatal aspect. Obviously this prediction is not foolproof and you need good inspection of the tooth that has been removed to confirm what shape the remaining root is. I suspect that the direction you move the tooth may not be as important as the direction of the curve of the root tip. In this case the palatal root tip curved to the buccal so the buccal side of the root fracture was higher. I will have to pay more attention to confirm my suspicions. The reason why discovering the morphology of the root tip is important is it determines how you will approach removal of the root. The elevation point is usually favourable is the higher side of the fracture. In this case I snuck a root pick on the buccal aspect of the root tip and gently felt around for a catch indicating the tip of the instrument was between the root tip and the bone. You can't elevate from here as the fragment is quite thin at this point and you should wriggle the instrument with slight apical pressure to move the instrument apically and elevate the root tip by displacement rather than rotation of the instrument. In this case it was quite frustrating as every time the root pick would slip past the root it would suddenly drop down as the root rotated making it feel like I perforated into the sinus and every time the root rotated it would lock in against the wall of the socket preventing removal of the root. Usually if you can engage the tip of the root pick against the root and pull coronally the root tip will emerge but in this case any rotation of the root bound it too tightly against the walls and it didn't emerge. It was very frustrating as the root kept coming slightly out then dropping back into place. Finally, I got it out by rotating it which allowed the higher part of the root (buccal side) to stick up and used a pair of fine artery forceps to grab this tip tightly and pulled coronally and the root tip emerged. Be careful as you only have one shot at this as the part of tooth you are grabbine will usually be quite fine and if you don't grab it far down enough the part you engage may be too thin and will fracture. Lock the forceps tight and pull straight up with slight wriggling movements. Try not to rotate the root tip with any significant force as you risk breaking off the purchase point.

- I found giving LA to upper 8s in weird positions especially challenging this day. When they are quite far posteriorly or the patient has a narrow sulcus with a fatty cheek or the coronoid process is tight against the teeth there can be insufficient room for good access of your needle. Simply turning the mirror head around and putting the reflective surface facing the teeth can allow you to retract the soft tissues better. This is because the coronoid process often acts as a barrier for the handle of the mirror and you can't place the mirror head back far enough to retract the tissues near the upper 8s. Also get the patient to close very slightly once your needle tip is near the site to allow the tautness of the tissues to decrease and move the coronoid process back even further.