Since 1853, the needle and syringe has been the gold standard approach in order to deliver parenteral medicine. Even in dentistry; since 1884 when cocaine was the first local anaesthetic to be injected intraorally, the needle and syringe has remained by far and away our number one delivery system. The only changes that have occurred with the needle and syringe since 1853 is its ability to accept a local anaesthetic cartridge (as opposed to drawing up the local anaesthetic) and the addition of an aspirating plunger.1
As different techniques and delivery systems have evolved, dentists have been given the opportunity to have at their fingertips, methods to anaesthetize teeth, which before proved very stubborn. The “hot tooth” or a mandibular molar with accessory innervation are two examples of such situations.
In 1968, Magnus used a needle and syringe to inject local anaesthesia directly into bone,2 while in 1974, Bourke described a technique to inject local anaesthetic directly into the cancellous bone.3 By using a small round bur to drill an entry through the cortical plate, local anaesthesia was introduced into the cancellous bone via a standard needle and syringe. Teeth that were previously unable to be treated because of pain during preparation were now more predictably anaesthetized.
Since 1968, other intraosseous techniques have been developed. The Stabident System, the Hypo Brand Needle and a variety of PDL injection techniques are some examples.
In 1999, a new system called the X-tip was launched. This intraosseous technique was invented by Dr. Arthur (Kit) Weathers from Griffin, GA. Dr. Weathers developed a simple and effective way to perforate bone while at the same time, leaving dentists with the ability to easily re-enter the perforated site and then be able to inject local anaesthetic directly into the cancellous bone. The system comes in a sterile packet. Inside this packet is a vial which contains the X-tip product. This is composed of a 9mm 27-gauge hollow perforator, which sits inside a 7mm 23-gauge cannula called a guide sleeve. The perforator therefore sticks out 2mm past the guide sleeve. This unit has a 15mm long, universal latch-type attachment, for a slow speed handpiece (Figure 1). The perforator and cannula are covered with a protective red cap. As well, a 27 gauge ultra short needle (8 mm long) comes with this system.
To use the X-tip, the following technique is employed. The first step must be for the operator to take a radiograph of the interdental site to be perforated to ensure enough inter proximal bone lies between the teeth so as to not violate the periodontal ligament. Other hazards to look for are the mental foramen, a horizontally impacted third molar or a low-lying maxillary sinus. As well, intraosseous anasthesia will not work between the central incisors due to the predominance of cortical bone. The dentist can now place topical anaesthetic, and then inject 0.3-0.4ml of local anaesthesia in the buccal vestibule at the area desired for perforation.
The soft tissue site chosen for the perforation should be in attached gingiva, 2mm coronal to the mucogingival line between the teeth. Due to the pathways of the nerve it is recommended to perforate distal to the tooth being operated on if in the mandible while in the maxilla it matters less due to the greater porosity of the bone in this arch. This technique cannot be used with periodontal disease due to the lack of attached gingiva.
After attaching the perforator and guide sleeve unit to the slow speed, (Figure 2) the perforation can begin. This is accomplished with a pecking motion and should take no longer than 2 seconds so as to avoid heating up the bone thereby possibly causing necrosis. There is a feeling of breakthrough once the cortical plate has been perforated (Figure 3). Using a pair of cotton pliers, the guide sleeve is held against the gingiva while the slow speed and perforator are removed. The 27 gauge ultra short needle can now be introduced through the guide sleeve and one-third of a cartridge should be injected (Figure 4). The injection should be done slowly and take 30 seconds. Local anaesthetic with vasoconstrictor should be used (the author recommends a vasoconstrictor concentration of 1:200,000 epinephrine) in order to achieve a hard tissue anaesthesia duration of approximately 20 minutes. Without vasoconstrictor, one will achieve virtually no duration of anaesthesia due to the vascular nature of cancellous bone. In fact, this should be considered an intravascular injection and as such, different studies have shown that between 60-100% of patients will experience palpitations immediately after this injection with the use of vasoconstrictor. Patients should be warned of this in advance and intraosseous anaesthesia should not be used at all in patients with cardiovascular disease. The manufacturer recommends limiting the volume used to one cartridge per visit.
Once an injection is complete, the operator uses cotton pliers to remove the guide sleeve and dental anaesthesia should occur immediately.
After using this system repeatedly, the following has been observed by the author. This technique is easy to perform and with the guide sleeve, the possible problem of finding the perforated hole with the needle is eliminated. As with any intraoessus technique, perforating distal to a mandibular second molar may not be possible due to the thick cortical plate of bone. If it takes longer than two seconds to perforate, this technique should be abandoned. As well, it is usually necessary to bend the needle to enter the perforation in this posterior area. Also, a survey of studies have shown that approximately 2-5% of the time, an infection may develop at the perforation site. This is easily treated with a course of antibiotics. In addition, 2-15% of the time, the patient may report post-operative pain.4 It should be noted that these incidents of post-operative infection and pain have been reported with the Stabident system. This system has a different perforator and so one may not be able to transpose these post-operative sequela to the X-tip. Due to the very recent emergence of the X-tip, studies are needed to report any postoperative incidences. It has also been noticed that local anaesthesia can leak back out through the guide sleeve into the patient’s mouth, especially if the needle is not inserted into the guide sleeve to its hub. Finally, the cost of this system is approximately $3.00 per use (as compared to the Stabident system which is $1.00 per use) and is available in Canada through Confident.
The X-tip system is an effective and simple way of achieving intraosseus anaesthesia and may be a tool to stock in a dental office for use especially when treating a tooth that proves resistant to block or infiltration technique.
r. Isen maintains a private practice in Toronto treating patients with special medical requirements, apprehension control and local anaesthesia and station management.
Oral Health welcomes this original article.
REFERENCES
1.Local Anaesthesia of the Oral Cavity. J.T. Jastak, J.A. Yagiela, D. Donaldson, W. B. Saunders, Toronto, 1995.
2.Magnus GD Intraosseus Anaesthesia. Anaesthesia Progress 15:264-7, 1968.
3.Bourke K., Intraosseus Anaesthesia. Dental Anaesthesia Sedation 3:13-9, 1974.
4.Brown, R., Intraosseous Anaesthesia; a review. Oral Health, March 2000.
