Difficult anaesthetic challenge

 I was helping out one of the younger colleagues in the extraction department the other day with a very difficult case. This was one of the times I would say that the tooth was genuinely difficult to anaesthetise due to a hot pulp. In the past I had quite a few cases where I failed to achieve anaesthesia and blamed hot pulps only to realise it was probably my own technique that was inadequate and the excuse was just too convenient. This tooth was a heavily carious upper premolar with a significant curve on the root which bordered the maxillary sinus. The curve was to the mesial which was strange and it seemed to follow the outline of the sinus so we can assume that the expansion of the sinus at the time of tooth formation led the tooth root to curve to the mesial. 

Challenges involved in the anaesthesia of this patient were:

-Very dense bone: which I noted as we were elevating the tooth. Elevation and forcep movements hardly produced any movement of the tooth which is common with patients with stiff bone

-The proximity of the sinus would have prevented diffusion of the anaesthetic over to the palatal side of the tooth so the palatal anaesthesia would have to be very profound to achieve good anaesthesia

-Palatal position of the tooth. This meant the buccal bone was thicker and so there was more support for the tooth and resistance to movement as well as resistance for diffusion of the anaesthetic. In this case the patient may have had significant cortication of the bone which would have prevented anaesthetic effectiveness much like the posterior mandible

-The recession of the pulp made it very difficult to provide intrapulpal anaesthesia which in many cases can be seen as a last resort. When I stepped in to help I thought we were at the pulp and kept trying to inject into a divot in the centre of the tooth. Without any back pressure we cannot confirm that any anaesthetic has gotten into the pulp canal. It turns out we were just washing the tooth with anaesthetic and the divot in the tooth was not the pulp chamber but was misleading and each attempt to provide intrapulpal anaesthesia there was digging more of a hole into the caries.

My first suggestion when I stepped in was to provide anaesthesia  higher up in the sulcus. He had a very narrow sulcus and the needle tip contacted bone very early. Moving the needle tip more buccally will allow it to move away from the curve of the maxilla and reach a higher point. This is important as if the needle can't reach far enough then the anaesthetic may be deposited coronal to the apex of the tooth. This will definitely not effectively provide pulpal anaesthesia as the superior alveolar nerve plexus descends from above. In hindsight I would have suggested she deposit more anaesthesia to the mesial and distal of the tooth to see if we could get around the presence of the sinus and provide more regional anaesthesia. The other suggestion was to provide really good palatal anaesthesia where we expect the apex of the tooth to be and to either side of this. I think a lot of my "hot pulp" failures were here in failing to provide adequate anaesthesia in multirooted upper teeth as the palatal root may be far away from the buccal plate or the sinus may be interposed.

My next suggestion was to provide intraligamentary anaesthesia with good back pressure. I knew we had good soft tissue anaesthesia because the gingiva was not sore when i poked it but the bony and/or pulpal anaesthesia was not adequate as every time we tried to move the tooth the patient was in pain. This settled a bit after our previous strategies but still wasn't 100% good. 

The next attempt would normally be an intraosseous injection but as I thought the pulp was exposed my mind got fixated on trying to achieve intrapulpal anaesthesia. After a  few failed attempts I decided to use a handpiece to uncover the pulp. I was quite far off initially and the awkward angulation of the tooth as well as the severe damage due to caries led me to drill in the wrong spot. It is important if you are lost to stop, reevaluate and try again. There is no harm in cutting a wide area to locate the pulp if you are going to extract it anyway. After locating the pulp the pain settled but it was interesting to see how quickly the anaesthetic wore off, either because all the apical tissues were so inflamed that the solution washed away or more likely that such a small amount reaches the tissues through the pulp that it doesn't last long. For the remainder of the session I was topping up the anaesthetic every few minutes and I don't believe we ever achieved a pain free state for the patient. 

I would like to think that proper technique including ideal placement of the anaesthetic, adequate volume and use of supplementary techniques will achieve profound anaesthesia in most cases but in the future I would also consider adding on the intraosseous technique and providing oral analgesia with a combination of paracetamol and ibuprofen preoperatively or intraoperatively if we are struggling with the anaesthetic.