Peter Raftery explains why the Stabident system is a must in ‘hot pulp’ extirpation appointments.

An uncomfortable dental truth is that we are not able to effectively anaesthetise mandibular ‘hot pulps’ via the traditional inferior alveolar nerve block (IANB) alone. It is only with supplementary injection techniques we can reliably achieve anaesthesia. For this reason, I feel every dentist ought to have the Stabident system; I wouldn’t consider approaching an irreversible pulpitis extirpation without it.

In recent years there has been a wealth of good quality local anaesthetic evidence published. These clinical studies show clearly that the IANB alone fails to sufficiently or adequately anesthetise patients during ‘hot pulp’ extirpation appointments (Kanaa, Whitworth and Meechan, 2012; Nusstein et al, 1998). This same body of new evidence appraises the effectiveness of supplemental injection techniques in achieving clinically adequate local anaesthesia once a traditional block has failed. It is intra-osseous local anaesthesia that proves the best of these (Nusstein et al, 1998; Matthews et al, 2009).

Evidence

University dental school settings – with their steady stream of walk-in pain patients – make for the ideal places to study local anaesthetic’s clinical effectiveness on irreversible pulpitis. Over recent years researchers have done just this (in Newcastle (Kanaa, Whitworth and Meechan, 2012), Ohio (Nusstein et al, 1998; Claffey et al, 2004), and Sao Paulo (Tortamano et al, 2009)) – looking into the ability of IANBs alone (whether articaine or lidocaine) to achieve successful clinical level of anaesthesia. Success was judged to have been an ‘absence of, or only mild’ pain self-reported by subjects following hot pulp extirpation.

When employing the traditional block alone, clear and consistent failure rates ranging from 55% (Kanaa, Whitworth and Meechan, 2012; Tortamano et al, 2009) to 81% (Nusstein et al, 1998) were seen, with no difference observed between lidocaine and articaine (Tortamano et al, 2009; Claffey et al, 2004). With IANB failure rates like these in precisely the situations they’re needed the most it becomes necessary to know which supplemental injection to employ to rescue that dreaded missed block.

Buccal articaine

Studies in pulpitis cases of supplementing a missed IANB (Matthews et al, 2009; Aggarwal et al, 2019; + 10) with buccal infiltration of articaine noted the technique delivered only modest success rates ranging from 20% to mid 50%.

This lack of appreciable benefit in pulpitis cases is in sharp contrast to its buccal articaine’s clear usefulness when used to secure profound local anaesthesia following an IANB in asymptomatic (uninflamed pulp) cases (Kanaa et al, 2009).

Intraligamentary

Intraligmaentary injections – with a specialised syringe – in supplementing a missed block in pulpitis cases brought success rates of less than 50% (Kanaa, Whitworth and Meechan, 2012) meaning it could not be relied upon for adequate patient comfort.

Intraosseous

Studies show intraosseous local anaesthetic to be the best rescue of a missed block (Kanaa, Whitworth and Meechan, 2012; Nusstein et al, 1998). Of all the possible techniques employed to supplement a failed IANB in pulpitis case – intraosseous delivers the best success rates of up to approximately 90%.

Case study in technique for intraosseous local anaesthetic

Intraosseous local anaesthesia is as simple as it is inexpensive. After making a small perforation, local anaesthetic solution may bypass the thick buccal cortical bone and flood the cancellous spaces surrounding the apical nerves resulting in instantaneous, profound anaesthesia.

Figure 1: Initial radiograph showing irreversible pulpitis in LL6
Figure 2: Patient recently had amalgam restorations

The above images recount the steps taken in a recent intraosseous case of mine. Firstly a calm, authorative and confident bedside manner is important – these patients are already in pain and nervous. Tell the patient through the use of modern local anaesthetic solutions and evidence-based techniques you ‘will be able to get them numb’ (Figures 1 and 2).

In this case – shortly prior to presentation with me – the patient had had their amalgam restorations in LL5, LL6 and LL7 replaced with white fillings. Sadly, an irreversible pulpitis in LL6 ensued.

After giving the traditional IANB (I suggest approximately 1.8ml) and buccal infiltration (0.4ml) in the normal way, I will then assemble my Stabident armamentarium while that first set of injections has time to work. I reload my syringe with a new cartridge of local anaesthetic; for intraosseous I prefer articaine 4% with adrenaline 1:200,000 although the efficacy of intraosseous with lidocaine (Nusstein et al, 1998; Bigby et al, 2006) is similar. I attach the short Stabident needle to the LA syringe and will pre-bend the Stabident needle to facilitate easier intraoral access to the location of the bony perforation I am about to make (Figure 3).

Figure 3: Pre-bend the Stabident needle for easier access

I select a target site in the interpoximal buccal papilla just distal to the tooth of interest. I want my injection – and therefore my cortical bony perforation – to be in attached gingivae (as it can be hard to ‘find’ your perforation hole – even seconds after – if puncturing at a site in the loose, mobile vascular mucosa). With a sharp probe I check this area is adequately numb for the ensuing Stabident (Figure 4). I then attach the bony perforator to the slow handpiece and ‘rehearse’ bringing the perforator to my chosen site (Figure 5).

Figure 4: Ensure area is sufficiently numb
Figure 5: I ‘rehearse’ bringing the perforator to my chosen site

I calmly let the patient know they’re about to hear a whir and feel a thud. I don’t overexplain to patients that I’m about to ‘drill through their cortical bone’. Communicating unnecessary detail to a nervous patient in a tense environment is at best unhelpful and probably even reckless. After all when giving the earlier traditional block I didn’t feel the desire nor the obligation to list out loud all of the tissues and muscles I was expecting my needle to penetrate.

I then make my perforation. Not much will happen in the first one second of perforator contact but with one more second of gentle pressure the perforator painlessly perforates. The feel of the perforator entering cancellous bone having traversed the cortex is unmistakable. I angle the perforator apically to allow the solution to be deposited through the needle closer to the root ends.

Figure 6: Needle ‘falls’ into perforation hole

So as not to ‘lose’ my perforation hole I make the time between withdrawal of perforator and insertion of the needle (at the same angulation as the perforator went in) as short as is (safely) possible and without taking my eyes off the site. Having the syringe nearby is crucial in this endeavour. Tactile feedback tells you when the needle ‘falls into’ the matched sized perforation hole (Figure 6). With medium pressure I then slowly deposit the full cartridge. I calmly let patients know they ‘may feel a short-lived elevation in heartbeat from local anaesthetic solution getting to the right places.’

Figure 7: Final radiograph

After this? Anaesthesia onset is instant and so it’s on with the rubber dam, out with the pulp (Figure 7) and time to ready yourself for the patient’s plaudits. Remember to ask the patient to fill in an online review about their expectation versus experience. And breathe.

Cautions

The healing capacity of the mouth is amazing. I have never yet seen any wound healing complication associated with the Stabident procedure. To keep it this way I’d ensure you observe the following basic precautions.

Select a perforation spot not immediately above important structures such as the roots, the mental nerve etc. Common sense and thorough scrutiny of a pre-op radiograph should suffice. Periodontitis patients (with marginal no bone to aim for) are unsuitable cases.

Be on the look out for backflow of anaesthetic solution – this will negatively affect success and may necessitate selection of a second (more anterior) perforation site.

Spinning drills generate heat – it is unwise to allow the perforator to rotate in the same position for more than around three seconds.

Conclusions

The Stabident system is inexpensive at around £1 per use and works with equipment all dentists already own. Compare this to the purchase of an intraligamentary syringe at around £200 or a compared to computer controlled local anaesthetic devices at around £3,000. The Stabident intraosseous system is the most (by clinical outcome and by cost) effective way to rescue a missed block.

But finally, I always thought it strange – for equipment that tends to be used during the more stressful appointments – I really think they ought to change the name! Asking the nurse to grab the ‘Stab-ident’ does nothing for an already nervous patient’s blood pressure!

References

Aggarwal V, Singla M and Kabi D (2010) Comparative evaluation of anesthetic efficacy of Gow-Gates mandibular conduction anesthesia, Vazirani-Akinosi technique, buccal-plus-lingual infiltrations, and conventional inferior alveolar nerve anesthesia in patients with irreversible pulpitis. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 109(2): 303-8

Aggarwal V, Singla M, Miglani S and Kohli S (2019) Efficacy of Articaine Versus Lidocaine Administered as Supplementary Intraligamentary Injection after a Failed Inferior Alveolar Nerve Block: A Randomized Double-blind Study. J Endod 45(1): 1-5

Bigby J, Reader A, Nusstein J, Beck M and Weaver J (2006) Articaine for supplemental intraosseous anesthesia in patients with irreversible pulpitis. J Endod 32(11): 1044-7

Claffey E, Reader A, Nusstein J, Beck M and Weaver J (2004) Anesthetic efficacy of articaine for inferior alveolar nerve blocks in patients with irreversible pulpitis. J Endod 30(8): 568-71

Kanaa MD, Whitworth JM and Meechan JG (2012) A prospective randomized trial of different supplementary local anesthetic techniques after failure of inferior alveolar nerve block in patients with irreversible pulpitis in mandibular teeth. J Endod 38(4): 421-5

Kanaa MD, Whitworth JM, Corbett IP and Meechan JG (2009) Articaine buccal infiltration enhances the effectiveness of lidocaine inferior alveolar nerve block. Int Endod J 42: 238-46

Matthews R, Drum M, Reader A, Nusstein J and Beck M (2009) Articaine for supplemental buccal mandibular infiltration anesthesia in patients with irreversible pulpitis when the inferior alveolar nerve block fails. J Endod 35(3): 343-6

Nusstein J, Reader A, Nist R, Beck M and Meyers WJ (1998) Anesthetic efficacy of the supplemental intraosseous injection of 2% lidocaine with 1:100,000 epinephrine in irreversible pulpitis. J Endod 24(7): 487-91

Simpson M, Drum M, Nusstein J, Reader A and Beck M (2011) Effect of combination of preoperative ibuprofen/acetaminophen on the success of the inferior alveolar nerve block in patients with symptomatic irreversible pulpitis. J Endod 37(5): 593-7

Tortamano IP, Siviero M, Costa CG, Buscariolo IA and Armonia PL (2009) A comparison of the anesthetic efficacy of articaine and lidocaine in patients with irreversible pulpitis. J Endod 35(2): 165-8