recommended dose per root is 0.2 ml. Although pulpal anaesthesia is not due to
ischaemia, the technique is significantly more successful when a vasoconstrictor-
containing solution is employed. The anaesthetic of choice is 2% lidocaine
(lignocaine) with 1 : 80,000 epinephrine (adrenaline). Sensible dose limitations must
be used, as entry into the circulation of intraosseously administered drugs is as rapid
as by the intravenous route.
The technique involves inserting a 30-gauge needle at an angle of approximately 30°
to the long axis of the tooth into the gingival sulcus at the mesiobuccal aspect of each
root, and advancing the needle until firm resistance is met. It would seem sensible to
have the bevel facing the bone when the solution is being expelled; however, it has
never been demonstrated that the direction to which the bevel faces affects the
efficacy of the technique. The needle will not advance far down the ligament, as even
a 30-gauge needle is many times wider than a healthy periodontal ligament. The
needle normally remains wedged at the alveolar crest. The solution is then injected
under firm controlled pressure until 0.2 ml has been delivered. The application of the
appropriate pressure is easier with specialized syringes (175HFigs. 5.6 and 176H5.7) but the
technique is equally effective with conventional dental syringes. Another advantage
of the specialized syringes is that they deliver a set dose per depression of the trigger
(0.06-0.2 ml depending on design). When using conventional syringes for
intraligamentary injections the recommended dose of 0.2 ml for each root can be
visualized as this is approximately the volume of the rubber bung in the cartridge. It is
important not to inject too quickly; about 15 s per depression of the specialized
syringe lever is needed. Also, it is best to wait about 5 s after the injection before
withdrawing the needle to allow the expressed solution to diffuse through the bone,
otherwise it escapes via the gingival sulcus into the mouth. Intraligamentary
anaesthesia reduces, but does not completely eliminate, the soft tissue anaesthesia
which accompanies regional block anaesthesia in the mandible. This helps reduce the
occurrence of self-mutilation of lip and tongue. Intraligamentary anaesthesia is often
mistakenly considered a 'one tooth' anaesthetic. Adjacent teeth may exhibit
anaesthesia and care must be used if this method is being used as a diagnostic tool in
the location of a painful tooth. There are few indications for the use of the pdl
technique in the maxilla because reliable pain-free anaesthesia should be possible in
all regions of the upper jaw using infiltration techniques. In the maxilla,
intraligamentary anaesthesia is best considered as a supplementary method of
achieving pain control if conventional techniques have failed. The technique can be
invaluable in the posterior mandible and can eliminate the need for uncomfortable
regional block injections.
177H
Fig. 5.5 Intraligamentary injection in
a child.