The knowledge of doing the PDL injection to give anesthesia is really a good thing for a person to have. Had I not learned the PDL injection and the mylohyoid injection early in practice, I would’ve had a real tough time because I can’t work on a patient who is in pain.

JD: The knowledge of doing the PDL injection to give anesthesia is really a good thing for a person to have. Had I not learned the PDL injection and the mylohyoid injection early in practice, I would’ve had a real tough time because I can’t work on a patient who is in pain.

The term I really like for PDL, which I read in a study from Israel, is the trans-ligamentary injection. It describes the process of the needle in the periodontal ligament from the solutions going to that cribriform plate of the tooth socket intraosseously. So it’s really an indirect intraosseous injection. It’s great to have that for intraosseous anesthesia. Recently, I read Dr. William Forbes’ article in Chairside^® magazine (Vol. 5, Issue 1) discussing alternatives to lower blocks. I really liked how he discussed that, as well as other tips on anesthesia.

I really enjoy the idea of the PDL injection, of being able to limit the area anesthetized. And for practitioners, they are able to do things quickly; that can be really great. Of course, in dental school we don’t do things quickly, so that will help us with difficult areas.

MD: That’s a good point — a PDL injection on a lower molar in private practice makes a lot of sense because I can set the syringe down and pick up a handpiece right away. I can finish prepping in eight minutes, take an impression and have that done in 10 minutes, and put a temporary on. But in dental school, with 45 minutes of pulpal anesthesia, it takes that long sometimes to get the instructor to come over and check that you broke the contacts correctly on the lower molar.

JD: That is correct! The length of time it can take does make it such that for clinical purposes, treating a tooth as a whole rather than just overcoming some difficulty does make it complicated. I really like the point you brought up with the maxillary infiltrations in the incisor regions because that is an incredibly sensitive area. You have to give the solution very slowly in order for it to be comfortable for the patient. Had someone not gone through the exercise of practicing injections on his or her peers, he or she might not understand the importance of giving injections more slowly in the incisor region than anywhere else in the mouth.

MD: Yeah, and what I like about the computer-controlled device is that I don’t have to concentrate on giving it as slowly as I can, but instead making sure I don’t give it too fast. I use it on an even lower speed than the manufacturer recommends when I’m up there, and I can step on the foot pedal and speed up halfway through, once the patient is partially anesthetized. Using the STA System allows me to talk to the patient, to make jokes, to talk to my assistant. It lifts my mood, and as a result it lifts the mood of the patient. Also, a hidden benefit of this device is that it really takes away the stress and pain from those maxillary infiltrations as well.

You mentioned the PDL injection and mylohyoid injection, two great techniques to have in your arsenal. I’m guessing you’re talking about those in cases where a lower block doesn’t completely anesthetize a lower molar. Do you teach these techniques to dental students? Do the students get a chance to try a PDL injection and a mylohyoid injection?

JD: You will be happy to know that we have added three rotations in local anesthesia to the curriculum. If I remember correctly, Mike, around the time you were a first-year student, we started in the preclinical course giving the inferior alveolar on one day and the Gow-Gates on the other. So, the students in the local anesthesia block before entering clinic know how to do those injections. During the second rotation, they do PDL injections on each other using both the standard syringe and the LIGMAJECT^® (Henke-Sass, Wolf GmbH; Tuttlingen, Germany) syringe because it is so hard to give solution with the standard syringe. Students actually do that on each other, and they do it in a way that, 40% of the time, the person does not feel it at all; 40% of the time it feels like a probing; and 20% of the time it feels like a really sharp probing. Interestingly enough, I found this out through one of my students who was a former hygienist. She said, “Hey, I learned a technique where it was totally comfortable.” I told her to do it on me, and sure enough, by having the needle in the sulcus but not touching the attachment and giving the solution for 10 to 15 seconds, then gently touching the attachment and penetrating the solutions for a couple of seconds was relatively pain free. Of course, you’ve got to penetrate farther and it feels like you can’t; you go to get solution and it feels like you can’t. So this technique that a dental student brought in and taught me has made the PDL injection a comfortable injection. From then on, I made PDL injections hands-on, with the students practicing on each other. And the students are amazed by how comfortable it is.

Dental students also learn the mylohyoid injection in the second rotation. So, just into their third quarter in the clinic, they have learned both of those injections. I felt they needed to have those injections for handling accessory innervation issues. It doesn’t matter how many mandibular blocks you give and how thick the root feels; if there are accessory nerves coming in, you have to handle those to be effective in anesthesia.

MD: You know, it’s funny: The PDL technique you just mentioned is pretty much how I give it, too. I never really gave it a lot of thought, though — I just knew that I put the needle in and that I didn’t want to go into the attachment until I gave a couple drops of anesthetic. But I was thinking, well, what am I expecting? Am I expecting this to anesthetize the base of the sulcus on contact? It didn’t necessarily make a lot of sense to me, but I knew that if I put it in like it was a perio probe, gave a couple drops, advanced a little bit into the attachment, gave a couple drops and moved along, most patients will say, “I didn’t feel a thing” — especially compared to a lower block, where you’ve got to get across a couple muscles to get back where you’re going.

For dental phobics — who I’ve never really enjoyed working on to be honest, but you still find them in your practice — the ability to give what’s almost a closed mouth injection for a lower molar versus a wide-open lower block will really win over some patients. Patients who feared injections suddenly become brave because what they really hated was that injection, and it’s so much easier to hide it with a pleasant injection without all the soft tissue anesthesia that goes along with a lower block. I’ve found it to be a fantastic technique.

I can tell you that when I was in dental school, we did not learn the Gow-Gates. That’s one of the things about local anesthesia I find to be a little intimidating. To learn the Gow-Gates in dental school, when you’ve got an instructor standing next to you helping you through it, would be ideal. In private practice, it’s pretty easy for us to switch from one composite to another, try a different post system or a different bur. But when it comes time for somebody who’s been in practice for 10 years to try a Gow-Gates on a paying patient without somebody there, that’s a big leap. And most of the dentists I talk to say, “Wow, it sounds like it’s a great injection, but I’m terrified of telling someone to open wide and then aiming for their ear.” I’m not surprised you find it makes a big difference to expose students to a technique like Gow-Gates when they’re in dental school.

JD: It makes a big difference. Of course, having two different techniques to use helps if they miss the mandibular block using the standard inferior alveolar technique; instead, they can try the Gow-Gates. It’s a real benefit to the students, and they love the injection. In fact, at the end of their week in local anesthesia I talk to them about it, and about two-thirds of the students prefer the Gow-Gates injection to the inferior alveolar. So they’re already planning on entering clinic with that as their primary mandibular block.

It’s good for readers to try something different; it’s an anatomic issue that you can’t see that makes it a little more intimidating, but if the practitioner just palpates the patient’s neck at the condyle — and of course we’re needing to do that in doing temporal mandibular joint exams — if they just palpate that neck of the condyle and do their penetration and just aim for that, that’s the Gow-Gates. So you know it’s two things they are used to doing: the penetration for mandibular block and palpating the temporal mandibular joint area. Just those two things together, finding the neck of the condyle and their standard technique, and they’ll be fine aiming for it.

MD: That does break it down into two easy steps. For dentists who didn’t learn the Gow-Gates in dental school, it sounds more intimidating than something we’re used to doing. I don’t know what we think is going to happen if we try it, but you get sort of comfortable doing one thing and it does become difficult to change. So if you’re going to work on an average patient who comes in for a crown on teeth #18 or #19, are you going to go straight for a Gow-Gates or are you going to do an inferior alveolar? What’s your strategy?

Because I wasn’t showing my skill, I thought I’d try to act intelligent. I did the Gow-Gates and she was ecstatic that she was anesthetized. And that’s how I came to know and become a believer in the Gow-Gates. It’s a phenomenal mandibular block injection.

JD: My strategy is the Gow-Gates; it’s my injection of choice. I got lucky because I kind of stumbled across the Gow-Gates injection as I was reading to keep abreast of everything. Then, my dental assistant had her mother come in for the first appointment. And I’m doing the exam, and she’s had so much dentistry done — I can still picture the whole thing — on the lower left side, and she needs a lot more, and in talking to her she said no one had ever completely numbed her lower left side. I cringed thinking she had all this dentistry done and hadn’t ever been satisfactorily anesthetized. So, I said to her, “That won’t be a problem for me.” Yeah, right. So, she comes in for her appointment; we start the treatment on the lower left quadrant. I start the mandibular block; it’s not successful. I do my second; it’s not successful. Now I’m not looking so skilled, so I said, “Well, I just read about this other injection called the Gow-Gates.” Because I wasn’t showing my skill, I thought I’d try to act intelligent. I did the Gow-Gates and she was ecstatic that she was anesthetized. And that’s how I came to know and become a believer in the Gow-Gates. It’s a phenomenal mandibular block injection.

MD: That’s a perfect first Gow-Gates, when you’re starting to sweat working on your assistant’s mother and it works! I can see how that would instantly become your preferred injection technique, and I’d probably never ditch it because it was able to help in that situation. I suppose you don’t give too many traditional lower blocks anymore than, do you?

JD: No, I don’t. The Gow-Gates is my primary injection. One reason is the success rate, but another reason is because it can be a higher injection than what’s traditionally taught with the Halstead method, but it will take care of some of the nerves that will cause accessory innervation. So, it will be high enough up there and most often get the mylohyoid, and sometimes it will actually get the buccal nerve, too. And that’s one of the things students think is so cool: With one injection at one location, you don’t have to go in and do the buccal injection as well, although that isn’t always the case.

MD: Well, I’ve seen, and correct me here if I’m wrong, but I’ve seen statistics on the traditional inferior alveolar that for the first block given, it’s missed 15% to 20% of the time. What’s your feel for that number? How would you compare that to a Gow-Gates being missed on the first attempt?

Fifteen percent to 20% of the time the dentist misses the mandibular block and needs to give a secondary one. And then, well, two things. One, with the Gow-Gates that number is far less — I’ll say 90% of the time to 95% of the time, the Gow-Gates gets it with the first injection.

JD: You’re a learned man because that’s correct. Fifteen percent to 20% of the time the dentist misses the mandibular block and needs to give a secondary one. And then, well, two things. One, with the Gow-Gates that number is far less — I’ll say 90% of the time to 95% of the time, the Gow-Gates gets it with the first injection. Another reason, though, that dentists miss the standard mandibular block technique is they’re uncertain where to penetrate for the injection, because if they don’t see that pterygomandibular triangle, all of a sudden they’ve lost their visual landmark. And if they use that coronoid notch to determine it, well, the coronoid notch is really too low and the coronoid notch is probably 15 mm lateral to where they need to be penetrating, so it can be really difficult. That’s one of the reasons the standard inferior alveolar is so often used; the dentist doesn’t know what to do and there aren’t any landmarks.

MD: That’s a good point, and I just thought of that the other day. A female patient came in, an obese patient in her 50s, and when she opened wide there was a lot of fatty tissue back there. There wasn’t a landmark to be seen, and I was really happy that I was planning on giving her a PDL injection on tooth #19. It occurred to me for the first time that, wow, this is a great technique on somebody like this, where I know I would’ve missed that block the first, second, maybe third time because there was so much fatty tissue back there. I just couldn’t see the landmarks we traditionally associate with a standard lower block. Now on that type of patient, where you don’t see the landmark, it’s a little different for the Gow-Gates, right? Are you able to use different landmarks in a patient like that?

JD: Well, the landmark in the neck of the condyle will help the dentist and the hygienist who is certified in local anesthesia know where to aim. But I think the other determination, whether it’s the standard injection or the Gow-Gates, is that it’s so important to actually feel the penetration site. Our first-year students can find the penetration site with their eyes closed. Of course the hand has to get to the mouth, and they learn by finding it on their own. So it’s a tactile type of mandibular block, where the person will find where the ramus is running up toward the maxilla. Sometimes the absence of mandibular molars makes it difficult for a dentist, having lost the landmarks they’re used to. But instead the dentist can find where the ramus runs up toward the maxilla and then find the internal edge and penetrate medial to that. If there aren’t landmarks, you can feel that internal edge of the ramus, you can run your finger a little farther medially and then feel the ligament and go, OK, I’m just penetrating between these two structures. So, even when the visual landmarks aren’t there, the tactile ones always are, and that is really a helpful thing; it’s one of the things I really enjoyed in the article by Dr. Forbes. He also went over some of the anatomic features for the penetration of the mandibular block.

MD: That’s a great point. I’m just playing with the skull here that sits on my desk as we speak.

JD: Good!

MD: I’ve always loved having the skull on my desk because it’s so great for local anesthesia, to be able to look and see what’s underneath — what the boney structures are and what’s going to be different. You can feel it and look at all the different foramen. I find it to be one of the more fascinating things we do as general dentists and certainly one of the areas where constant practice and improved technique will pay huge benefits.

Switching gears here: In the PDL technique I use, I use a 4% Septocaine^® (Septodont; New Castle, Del.). I’ve used infiltrations, but I’ve steered away from using 4% anesthetics like the 4% Septocaine on blocks because of some of the things I’ve seen in the literature. I know you’ve certainly spent some time on this topic, so how do you feel about a potentially higher rate of paresthesia with these 4% local anesthetics?

JD: Well, I’m really glad you’ve seen that in the literature; it has sparked your mind and impacted your use of the 4% solutions. With articaine, I think the thing that the dental practitioner needs to look at is the product insert. In the “adverse events” section of the product insert is all the information the practitioner needs, including a table of events that happened 1% of the time or more. Now, they only did 882 treatments with articaine in the FDA study that the product insert is from, which reported it having 11 paresthesias. Well, you haven’t had 11 paresthesias in your lifetime or the lifetime of pretty much everybody you know, but they have 11 in 882 treatments. That’s just radical when they start talking about a 1% occurrence in something that is life-changing for the dentist, who caused this in a sense to his or her patient, and the patient that experiences it. So 11 in 882 just from the product insert: If the dentist were to say to the patient, “Well, I can use this local anesthetic, but there’s a 1 in 100 chance you’ll experience paresthesia, where numbness is going to continue for two weeks, eight weeks or permanently,” I think the patient is going to opt against it.

The other thing to consider with that product insert is: after the table, it lists by body system the other adverse events. And when it comes to the neurologic system, it lists other paresthesias and other types of nuero injuries that we really term a paresthesia. So, the study really had 21 paresthesias out of 882. I don’t think there needs to be any controversy; I think the product insert speaks for itself.

MD: Wow, that is amazing. I would bet $1 million that if you asked your students to try to get 21 paresthesias during their next 882 injections, they couldn’t. As a local anesthesia instructor, do you think you could get 21 paresthesias with 2% lidocaine if you tried? That seems mind-boggling.

JD: The truth is, it is a mind-boggling number. So in my directing local anesthesia at the dental school since 1978, I don’t know of a single documented paresthesia case. I’ve heard about two or three that might have been, but I never saw the patient, never saw a follow-up. When you think of the number of chairs we have, 140 in our main clinic being used twice a day, we’re already at 280 patients per day. So if we don’t get paresthesia doing that many, it’ll just show you there’s no way. You know, when you graduated from dental school and when I graduated from dental school, paresthesia was a term we knew, but it sounded like something that happened to one in a million. So, you’re right, there would be no way to create that with a 2% solution.

MD: Yeah, paresthesia was something that happened to oral surgeons who were taking out wisdom teeth in and around the nerve. And then later it happened to dentists who were placing implants in and around the nerve. But the true paresthesia that came strictly from an injection was pretty rare. So, 21 out of 882 patients is amazing to me; I think most dentists will go their entire career without having more than one or two temporary paresthesias. I’m sure there’s the odd person who gets a permanent one, but that is really scary. You’re making me happy that I’ve stuck with 2% anesthetics for my blocks. So this would certainly hold true for a Gow-Gates or any other block anesthesia, I’m assuming.

JD: Yes, that’s true. Whichever of the mandibular blocks, that’s where it appears to occur. One of the other unfortunate and interesting things that came about with the 4% solutions is: I had heard the term “paresthesia,” but I had never heard the term “dysesthesia.” As you said, we heard about this from oral surgeons, and it was from creating physical trauma to the nerve in the removal of an impacted tooth. In the sense that we can traumatize a nerve and cause it to block conduction with paresthesia, what I read about with the 4% solutions is they have caused dysesthesia. So the other thing is we can traumatize a nerve and cause it to continually fire. Patients who experience dysesthesia from 4% local anesthesia, primarily to the lingual nerve to the tongue, describe that it feels like their tongue has just been scalded. But that is a chronic phenomenon. I know of patients who have a permanent dysesthesia to their tongue, and their life is forever changed. They’re a chronic pain patient. So that’s another aspect, not just the paresthesia but also this dysesthesia of pain.

MD: Wow, that is a lot to think about. Even if somebody didn’t fully believe this study for whatever reason, it’s in the package insert inside the Septocaine. I have to admit I hadn’t taken the time to read that insert. I did see your letter in JADA, which is how I became aware of this. But I’m a little ashamed I didn’t read the insert before that. You know, we think it’s like lidocaine; it’s got “caine” at the end of it. You can see how a dentist might skip that. But the insert contains some pretty important information. Let me ask you this: If a patient comes into your office and you’re going to be doing multiple maxillary anterior crowns, let’s say they have single-unit crowns from tooth #5 all the way over to tooth #12, how are you going to approach that in terms of local anesthesia?

JD: Well, it can be done in a number of ways if the practitioner does not want to affect the patient’s use of their lip. If they want to have natural lip use from not anesthetizing some of the muscles of facial expression, what we’re doing there is infiltrations and then things like what you were mentioning: periodontal ligament injection or the injection they call the AMSA by injecting into the palate. And really what that injection is doing, it’s really a subperiosteal injection, in that the needle is placed at osseous contact. The solution is under periosteum, so really it’s another indirect intraosseous injection in the palate. We have the PSA nerve in the posterior, and the AMSA is saying there’s an anterior superior alveolar and a middle superior alveolar, and that’s the AMSA, the anterior and middle. By doing that approach on the palate, a subperiosteal injection, we’re saying we’ll anesthetize that anterior middle superior alveolar nerve going to those teeth. There was a study done that appeared in JADA, and it was really the only study that showed how much solution you would use and what areas it would anesthetize and at what frequency. Dr. Al Reader out of Ohio State was, I believe, the primary author. Any dentist who wants to do that injection into the palate to anesthetize the teeth should read that article to get an idea of how successful it’s going to be. What will my frequency of success be? Besides the standard approach of infiltrations, that approach of PDL injections or doing a subperiosteal on the palate to try to achieve that would be some of the other techniques I would use.

MD: I still do the multiple infiltrations. To me, the patient losing the ability to smile is a little bit of a liability, but I want guaranteed profound anesthesia for a while if I’m doing that many units. The patient’s comfort is first and foremost in my mind. And by the time we get the temporaries on, they’ll probably have a little bit of their lip back. So if you’re giving from first bicuspid to first bicuspid over on the other side — infiltrations — are you giving a carpule per tooth? Are you splitting the difference between a couple of teeth like the central and the lateral? How many carpules will you give in a case like that?

JD: A good way to limit the amount of penetrations is by injection between the teeth, as you mentioned. So if it was that first bicuspid to first bicuspid situation, if you infiltrated between the cuspid and the first bicuspid, that will pick up both of those, and between the lateral and central incisor, you’ll pick up both of those. I would say you’ll want to give three-fourths of a carpule. If you usually give, let’s say half to three-fourths for a standard infiltration, I’d say using three-fourths between the teeth would usually get both teeth. I think you’re correct — anesthesia is the most important thing to the patient. And with doing the infiltration, you know you’ve got it, where with this AMSA technique, you don’t have that assurance until you start working on the teeth and find what is anesthetized and what isn’t.

MD: That’s a good point. I’m trying to think of other injections. I don’t know that there’s any other like the Gow-Gates that can be so useful to a GP who’s willing to learn it. It doesn’t sound to me like the AMSA is quite the game-changer that Gow-Gates could be for a practitioner. Is that correct?

JD: I would say so, yes. You know I feel the same as you do, Mike. Besides wanting the assurance of anesthesia, I know where my pre-gingival margins are, so I’ve got that. I know preoperatively where the lip line is if I want to use that. So to cosmetically have, after you’ve done your dentistry, the patient’s lip be normal, I don’t see that as having much importance as compared to knowing that we have anesthesia.

MD: That’s a good point. I was flipping through a journal the other day and saw an ad for an anesthesia-reversal agent. As you know, patients enjoy the effects of local anesthesia because it keeps them from experiencing pain, but they don’t necessarily enjoy the injections — the path you have to use to get there. This anesthesia-reversal agent also has to be injected, and I don’t think I could put myself in the mindset of saying to a patient, “OK, well, your appointment is done, but I’ve got to give you one last shot to un-numb you.” I think the patient would say, “Well, won’t it wear off on its own?” I don’t know how quickly it reverses the anesthesia, but I like that patients are going to be numb for another hour or so and it’s going to gradually taper off. If I did something that is going to cause inflammation, they have the chance to take 800 mg of ibuprofen before it fully wears off. I’m not totally sold on the idea of giving someone one last injection at the end of the appointment to reverse the effects more quickly. Am I missing something here? Is this maybe something that has limited applications? I could see that it makes a lot of sense for children.

JD: Once again I really respect your thought line because I, too, don’t see much usefulness for this reversal anesthetic. It works by dilating the blood vessels that we restricted with epinephrine, causing the duration to lessen. But like you say, hey, I’m going to give you one more shot. And, of course, the expense of the materials, too. And, as you say, having that period of time if we cause some pulpal inflammation to have the patient in a period of anesthesia where they won’t feel anything once the anesthetic wears off is important. The other important thing, especially for mandibular blocks and the PSA injection is, we know when we give an injection we aspirate first to make sure we’re not in a blood vessel. If we are, we back up a little bit, aspirate again and inject. And, of course, we’re using a vasoconstrictor in the local anesthetic so it’s going to take care of that little puncture we did. But if you did the same thing with the reverse, if you puncture the blood vessel and back up and give your solution, now you’ve dilated that puncture in the blood vessel. So I have a concern as far as hemorrhage effects from using a vasoconstrictor with the potential of penetrating a blood vessel. I guess one of the places in their study that I felt tried to avoid an area of issue was, as I understand it, they did not do the PSA injection. Of course, that’s the one where dentists worry about a hematoma. Then again, if you were worried about a hematoma with a vasoconstrictor, what kind of hematoma would you get with a vasodilator?

MD: It’d be a full-face hematoma! It’s funny; I remember in dental school when I received my first PSA from the student to my left, who was a hygienist and had already been giving injections. I was excited that someone with experience was going to be working on me. I remember going downstairs after the clinic and somebody saying to me, “What happened to your face?” and I was like, “What?” And I actually received a hematoma on the very first PSA that I ever got, and I had to go through all the phases of colored bruises on the side of the face. But the student who gave it to me also baked me cookies for about a month after that, so it was a good tradeoff! I’ve always been very attuned to carefully aspirating since I’ve gone through that myself. I agree that leaving hematoma out of the study seems suspicious at worst or terribly absent-minded at best.

I was having a discussion with my dad the other day, and I think he was being serious with me, but he said when he was in dental school, I think from 1961 to 1964, needles were not disposable. Is that true?

JD: It’s hard to imagine, but the needles were not disposable. They would try to sharpen them up. It wasn’t too much earlier from when you were a dental student that a dentist would reuse prophy cups and prophy brushes and saliva injectors.

MD: Wow.

JD: Yes, I know. Dentistry has changed.

MD: I don’t know how many times you can sharpen a needle, or if you just go to give an injection and it won’t penetrate the mucosa and you break down and say, “OK, I guess we’re going to have to use a new needle now.”

When I was in dental school, we were taught to give lower blocks with a 27-gauge extra-long needle, and all my friends who went to USC are big fans of the 25-gauge needle. And when I look at it, it really scares me. I know it’s not that different from a 27-gauge, but it looks like it’s on a whole other level. Do you guys still teach the 27-gauge at UOP, and can you describe the difference between those two needles?

JD: Yeah, we still use the 27-gauge. And yes, the 25-gauge when put up against a 27-gauge looks big, it looks wide — although a benefit of a wide needle is that it’s supposed to deflect less. Also, you’ll know for certain if you’re in a blood vessel to a higher degree of certainty than with a 27. At the same time, when you’ve made that hole in the blood vessel with the 25, it’s a bigger hole. And you know, they’ll say the 25 is no more painful than the 27-gauge, but the study they’ll do won’t be a true study of the injection. It’ll be similar to when they say topicals don’t work. They’ll take a needle and take it to periosteum. It’s like, well, wait a minute now — we don’t use these things without topical and without anesthetizing ahead. So although I definitely wouldn’t say the 25-gauge is improper, I’m a person that likes the 27-gauge and I feel like it’s a great needle. One of the things I think also confuses practitioners is: I remember getting out of school and a short needle was a short needle, a long needle was a long needle. I remember in the first practice I associated in, I was looking at the long needle thinking, “Wow, that thing looks so long.” And I thought, well, no, it’s a long needle; it just looks extra long to me. Well, it turned out that our 27-gauge needle at school was 32 mm long and this needle was 40 mm long. So I think it’s really important for the practitioner to know the length of the needle they’re used to, and if they order something different, to check it. Eight millimeters is a big difference.

MD: Yeah, 8 mm is a big difference, and you would no doubt be able to see it. I’m wondering, I know the puncture points are relatively the same, but is the target area for the Gow-Gates a linear measurement? Is it farther away than a traditional lower block?

JD: I would say the answer to that is yes. At UOP, we’re still going 25 mm to 30 mm on inferior alveolar and Gow-Gates; at least that’s our primary range. But I think you’re right — that’s really intuitive that you’ve come up with that. It is a little farther distance to get to the neck of the condyle, than say to get to a mid-ramus depth. But, it’s interesting; we’re doing it still in that 25 mm to 30 mm range for the most part and having success. But you’re right, looking at it anatomically you’d figure, OK, it looks like we should go deeper for the Gow-Gates.

MD: Yeah, I was just picturing the difference in needle lengths you were mentioning. If a practitioner had been using a shorter 27-gauge, and he or she had a needle that was too short, they would come away from it saying, “Oh, I tried that Gow-Gates; it doesn’t work.” It would seem like maybe the extra 8 mm could be helpful for that type of block when you’re giving it for the first time.

A lecturer once said he was giving lower blocks with 30-gauges very successfully because he felt the 30-gauge was even less painful than the 27-gauge needle. And I tried a few of them like that, and I’ve never tried a 25-gauge, so I’ll just accept what you say is true, that the 27-gauge deflects more than the 25, but there’s a huge jump there. When I tried to give a couple lower blocks with a 30-gauge just to see what it was like, I could feel the deflection taking place.

JD: I would agree with you. The 30-gauge has a lot of deflection, and you know we usually use it in deflections where we don’t go that deep. So, to take that 25 mm to 30 mm, that can have a lot of deflection. Just like you say, it’s almost as though you could feel it when you penetrate tissue; you could almost see the needle deflecting and bending in the outer tissue. And it is interesting because, similar to you, I know dentists who use 30-gauge needles for mandibular blocks, and they’ll even use 30-gauge short needles, and it blows my mind, but they say they’re successful. It’s really a curious phenomenon that some dentists use all these different diameter needles and different length needles and have success, and some practitioners have tried everything and can’t get success with anything for a mandibular block.

MD: Yeah, that is. The majority of what I do, and the majority of what a lot of other general dentists that I talk to do, is one and two single-unit crowns. You know, you’re doing a single-unit crown on a tooth that broke and nothing else in the quadrant needs anything. So my favorite needle has become the 30-gauge extra-short with the PDL, which I learned today was kind of an intraosseous technique at the same time. I had tried intraosseous injections before because I liked the idea of getting so close to a tooth and not having to give a block, but I always found it really difficult. I remember that Stabadex system where you would pierce the mucosa and make the hole in the bone and then hopefully when you went back to put the anesthetic in the hole, the soft tissue still lined up with the hole in the bone. And it always felt strange to put a hole in the bone just to put some anesthesia in there. It seems some of those systems have fallen out of favor, but I like the idea that we can use this other, what we would traditionally term a PDL, and get that same kind of effect.

JD: Yeah, it really works well that way. And with that direct intraosseous system, I think one of the things practitioners like about the improved version of the X-tip system is the little sleeve to put the needle in to help with placement. So that is a helpful technique, but like you said, using a PDL technique to create that same situation of anesthetic going intraosseously works well, too.

MD: I didn’t really follow up with this question when we talked about it, but I’ve heard a lot of lecturers say for probably 10 years now that Septocaine is great for infiltrations. They say you can actually infiltrate teeth that you couldn’t before: lower bicuspids and lower anteriors. If you used it on a maxillary tooth, you could pack cord on the palatal without giving additional anesthesia. I’ve largely found this to be true, so I’ve liked Septocaine as an infiltration. We spoke specifically of what you don’t like about Septocaine as a block anesthetic, but do you like it as an infiltration anesthetic?

JD: Well, I agree with what you’ve said, for infiltration it is more successful. I believe both 4 percents are more successful, but articaine definitely in the infiltration injections are where 2 and 3 percents should not be relied on. I would probably go to prilocaine myself — it’s a 4%. The other thing, there are some patients — substance abusers or former substance abusers, and it may be 20 years since they first got clean — for which our 2% local anesthetic will just not anesthetize them. Four percent prilocaine is what I’d use for patients who aren’t numbed by 2% anesthetic, so I really like it for that.

You mentioned earlier about not using 4% for the PDL injection, and I concur. There’s a higher degree of postoperative sensitivity using a 4% in attached gingival, doing an interdental injection, or doing the nasal palatine or doing the PDL. I would say, in those places, I don’t care for the 4% solution.

MD: OK, interesting. Well, that was a quick hour; the time just flew by. It was fascinating. Do you have any upcoming courses or an easy way for dentists to check on your lecture schedule to see where you’re going to be speaking?

JD: Thank you for asking, Mike, I appreciate that. I stopped speaking outside the dental school about 10 years ago, so currently I give the course at the University of Pacific Arthur A. Dugoni School of Dentistry a couple times a year. It’s a hands-on course, so the dentist will learn the Gow-Gates and many of the other things we’ve talked about. I thoroughly enjoy teaching these courses and enjoy working with practitioners and helping them, so they’re comfortable when they treat their patients.

MD: Yeah, that’s a great idea. I flew more than 100,000 miles last year lecturing and I would like to settle down, too, because the airplanes and the hotels get a little old after a while. That’s easy enough: If they want to take your course, they just need to come spend a weekend in San Francisco at the best dental school in the country — the University of the Pacific Arthur A. Dugoni School of Dentistry, which I’m proud to call my alma mater.

I appreciate your time today. It’s been fantastic, and you have given our readers something to think about. Once again, I’ll issue my challenge to GPs reading this article: What’s keeping you from giving a Gow-Gates? It sounds like it can solve the issues of incomplete mandibular anesthesia that we’ve all fought during our careers. We’ll see if 2010 is the year we get more GPs to try the Gow-Gates.

Thanks again for your time. I really appreciate it.

JD: Thanks, Mike. And thanks for what you’re doing with Chairside magazine. I think it’s really beneficial to the practitioner. Good talking with you. It was fun to pull out my class picture from the class of 1988 and look through some of the faces as you were recalling the hematoma. I was looking at the picture thinking, OK, I think that person’s initials were R.D., trying to figure out who caused your hematoma that benefitted you with many cookies.

MD: It was actually K.D., Kristi Doverance. You know you seat by alphabetical order, and she was on my left. And she’s now an oral surgeon. She was really one of the stars of our class. Of course, right next to her was Mike Doy, who had been a lab tech for 13 years before going to dental school, so every time we had to wax something up he was done in three minutes and after two hours ours still looked like crap. But it was really sort of a star-studded row. I had Rob Cunin there, who went on to go to orthodontic school. Kristi was fantastic with her hands. It just goes to prove you can do everything right and still get a hematoma. The truth of the matter is, we’re always trying to get the tip of the needle right back in that area, aren’t we?

JD: Yes. Interestingly enough, our PSA technique is like our infiltration technique in that it’s parallel with our alveolar bone. And, like you said, even though you get the best operator using the correct technique, bad things happen to good people.

MD: It wasn’t that bad. If that had been the biggest problem of my life, my life would’ve been easy!

Dr. James Dower is an associate professor at the University of the Pacific Arthur A. Dugoni School of Dentistry. Contact him at jdower@pacific.edu or 415-929-6538