| We got what you’ve been missing… |
| Third molars, otherwise known as wisdom teeth are the most commonly missing teeth in the human dentition. What’s more is that 40% of agenesisof third molars often occurs unilaterally. Teeth development is resultant of epithelial cells interacting with underlying ectomesenchyme. At birth all permanent teeth have begun development and most of them show signs of calcification. The third molar is the only tooth that develops entirely after birth. Third molar tooth bud is initiated with jaw growth, and once formed it is a highly vascularized tissue and not covered with bone and thus vulnerable to injury via inferior alveolar nerve block (IANB). The forming tooth bud is located where the body of mandible meets the ascending ramus at the occlusal plane of primary teeth, a little too close for comfort when you consider where the IANB is deposited. Only later does the epithelial-mesenchymal interaction also induce bone formation around the follicle in the form of a bony crypt that can be seen on a radiograph as young as 5-6 years of age. |
| Study by Swee J. Et al. |
| A retrospective study examined a pool of 220 active patients from the pediatric department in the school of dental medicine at Tufts University. The population was selected based on the patients having had received IANB at ages 2-6 and who had panoramic radiographs between the ages of 7-12. 440 different mandibular quadrants were analyzed for third molar development sites. The study group was deemed developmentally healthy. The control group was comprised of 376 mandibular quadrants had no history of receiving IANB. The test group was comprised of 63 mandibular quadrants had a history of receiving IANB. Only 1.9 percent of the control group displayed no evidence of third molar development, whereas 7.9 percent of the test group showed no evidence of third molar development. What’s more is that the agenesis of third molars was found to be unilateral in all tests cases (the contralateral side had no IANB and third molar development was present). The authors found a statistically greater incidence of missing third molars in the quadrants that did receive IANB. The authors concluded that there’s a possible association between receiving an IANB between ages 2-6 and third molar agenesis. Studies conducted on rat pups, have shown that minimal invasion of developing third molar follicles prevented 80% of the mandibular third molars from developing. |
| So what? |
| IANB can serve as a physical insult in the form of needle penetration into the area near tooth as well as accompanied aspiration. Chemically, local anesthetics are typically acidic with a pH as low as 3.5 and can be cytotoxic to cells, which could be injurious to the developing follicle and disruptive to the biochemical signals needed for the third molar to develop. Moreover, local anesthetics often contain vasoconstrictors which restrict oxygen to the tissues further contributing to agenesis. IANB have been used for many years with great benefits for patients adult and pediatric alike. And by no means do the others offer this as a recommended therapy for preventing wisdom tooth formation nor do they believe that this is the only plausible explanation. However, it is food for thought and hopefully helps us refresh on our tooth development and proceed with caution the next time we are administering IANB for our pediatric patients. |
Today’s Morning Huddle was brought to you by Jerry Swee et. al.
Here’s a brush up on tooth developmental stages:
1) Video 1
2) Video 2