| Abstract|| |
Aim: The objective of this work is to present a new collaborative method for teaching administration of anesthetic block in dentistry, with three-dimensional anatomical models used to improve learning and thereby increase safety, reduce anxiety, and improve the performance of students during the administration of anesthesia in the patients.
Materials and Methods: Three-dimensional (3D) models of skulls were made that reproduced all innervations of the V th cranial nerve (trigeminal nerve), as well as some blood vessels, glands, and muscles of mastication. For teaching the local anesthetic techniques we prepared pictures and videos of the administration of anesthesia in the models , which were presented to 130 students in two universities in Brazil. With the help of the models the students could follow the path of the nerves to be anesthetized and identify the anatomical points of reference for the correct positioning of the needle in the tissues. After the presentation the students answered a questionnaire aiming to assess the effect of the 3D models on learning.
Results: Eighty-eight percent of students rated the material as excellent, 12% as good, 0% as regular, and 0% as bad (unnecessary materials). After the presentation, 70% of the students felt confident about being able to achieve the nerve block in patients.
Conclusion: When exposed to an appropriate method, students recognized the importance of knowledge of anatomy for learning local anesthetic techniques. This method improved the quality of education and increased patient safety during the first injection.
Keywords: Anatomic imaging, anatomical models, anatomical sciences, anatomy teaching, dental education, oral and maxillofacial surgery
|How to cite this article:|
Canellas J, Araujo M M, Arce J. The use of anatomical models for learning anesthesia techniques in oral surgery. Indian J Dent Res 2013;24:326-30
Dental anesthesia should be carefully studied because the success of any operation depends on the effectiveness of the anesthesia. For the student to achieve excellence in oral surgery, he or she must be familiar with anesthetic techniques that will ensure complete absence of pain during the surgery.
|How to cite this URL:|
Canellas J, Araujo M M, Arce J. The use of anatomical models for learning anesthesia techniques in oral surgery. Indian J Dent Res [serial online] 2013 [cited 2021 Jul 27];24:326-30. Available from: https://www.ijdr.in/text.asp?2013/24/3/326/117995
Although the administration of local anesthetic is one of the most common procedures carried out by dentists, it is not exempt from bad results. Some complications in maxillary and mandibular anesthesia may require the student to interrupt or even postpone the oral surgery; for example, needle breakage, hematoma, failure to obtain local anesthesia, and neurological symptoms such as facial nerve paralysis or visual disturbances. Blanton and Jeske  stated in their work that detailed knowledge of the anatomy of the head and neck, particularly neuroanatomy, is fundamental for successful and safe administration of local anesthesia. Jenkins and Spackmann  have emphasized the relevance of the anatomy in clinical practice and have suggested refresher lessons in anatomy before students administer their first nerve blocks in patients.
The beneficial effects of the use of training models in the preclinical teaching of local anesthesia techniques has been reported by Brand et al.  They showed that the recipients of injection considered students who had practiced on the training model before the first injection as being significantly more confident and calm; patients also reported a decrease in the level of pain between insertion of the needle and the feeling of a tingling. Thus preclinical training may have small but positive effects on the administration of local anesthetics by dental students and may help to prepare them for the demands of general practice.
Brand et al.  investigated students' opinions about theoretical and clinical training in local anesthesia at different European dental schools. Many students felt insufficiently prepared when administering their first injection in a human. The students indicated that there was need for better training prior to the first injection. The desirability of having preclinical training on models has been frequently expressed by students.
The objective of this work was to present a new, collaborative, teaching method for administering anesthetic block in dentistry. We used three-dimensional (3D) anatomical models to demonstrate techniques to students in order to improve learning and thus increase safety, reduce anxiety, and improve the performance of students during the implementation of these techniques in patients.
| Materials and Methods|| |
This study was approved by the ethical committee of the University Estadual Paulista, Brazil.
With the intention of improving the teaching of local anesthesia techniques to undergraduate students in the department of oral surgery at the dentistry school of Federal Fluminense University, Niterói City, state of Rio de Janeiro, Brazil, and Estadual Paulista University, São José dos Campos, state of São Paulo, Brazil, we created 3D models using dry human skulls, reproducing the neuroanatomy of the face as accurately as possible [Figure 1]. Given the extreme importance of various nerves in the anesthesia for oral surgery, all branches of the trigeminal nerve (V th cranial nerve) were carefully reproduced, maintaining the maximum possible fidelity in the path of the nerve through the various anatomical spaces.
|Figure 1: Front view of three-dimensional models made in dry skulls. The main branches of the three divisions of the trigeminal nerve were reproduced using moldable porcelain. Glands and blood vessels were also reproduced using the same material. The muscles were made of latex rubber and gum was sculpted with wax red|
Click here to view
All the nerves and blood vessels of the face were made with moldable porcelain (Fox Industry, São Paulo). The following colors were used: White for nerves, blue for veins, and red for the arteries. Some of the cranial nerves were reproduced from their origin in the central nervous system until their point of exit from the cranial cavity, with the exception of the oculomotor, abducent, and trochlear nerves. The dural venous sinuses and the middle meningeal artery were also reproduced in the models. The reproduction of V th cranial nerve , the target of this study, included the trigeminal ganglion and the three divisions, ophthalmic nerve, maxillary nerve and mandibular nerve passing by the superior orbital fissure, the foramen rotundum and the foramen ovale, respectively, until its terminal branches. The four parasympathetic ganglions (ciliary, pterygopalatine, submandibular, and otic) connected with the trigeminal nerve were reproduced, along with the pre- and post-ganglionic fibers. The mandible had its innervation mounted within the same criteria, articulating the mandibular condyle in the mandibular fossa, with the teeth in the maximum intercuspal position. Since most anesthetic techniques are administered with the patient's mouth open, two muscles of mastication, the masseter and medial pterygoid, were reproduced. We used latex rubber and glue to secure them on the zygomatic arch and the medial surface of lateral pterygoid plate, respectively. These 'muscles' stabilized the mandible and also allowed the movements of opening and closing of the mouth, besides serving as reference points for some of the injections studied [Figure 2]. The three major salivary glands, parotid, submandibular, and sublingual, along with their secretor ducts, were also reproduced using the same material as was used for the nerves and vessels; the glands were colored orange [Figure 3].
|Figure 2: Pterygomandibular space - The medial pterygoid muscle was displaced to allow visualization of the nerves of the mandibular division of the trigeminal nerve|
Click here to view
|Figure 3: Posteroinferior view of the oral cavity - The three pairs of major salivary glands were reproduced|
Click here to view
We then made a video of each anesthetic technique being carried out on the 3D models, with the emphasis being on the importance of using anatomical landmarks to ensure proper administration. Subtitles were included on the images explaining, step-by-step, the deposition of anesthetic solution in the tissues. The video was divided into two sections according to the block: Maxillary and mandibular. Models were then subjected to a photo shoot where the anesthetic techniques were recorded [Figure 4].The videos and photos were presented to students in class. Photographs of the performance of the injection in patients were compared with the injection in the 3D models.
|Figure 4: Inferior alveolar nerve block in the models showing the anatomical relationship of the needle with the nerve during injection|
Click here to view
We tested the proposed teaching technique in six groups of students in two universities in Brazil: The Federal Fluminense University and Estadual Paulista University. One hundred and thirty students in the discipline of oral surgery were trained using the prepared material before they administered their first anesthetic injection. The presentation was divided into two parts: In the first part the neuroanatomy of the head and neck was reviewed and, in the second part, all the techniques were explained to the students, clearing any doubts and explaining the details of the techniques. Finally, after the presentations, the students performed the anesthetic techniques on the anatomical models.
At the end of the class a questionnaire was distributed to the students to evaluate the effects of the teaching material on their learning of anesthetic techniques. The questions posed to students were: (1) What did you think of the use of anatomical models as teaching tools? (2) Did you considere valid the neuroanatomy review? (3) Do you think the lesson with the models facilitated your learning of the correct implementation of anesthetic techniques? (4) Do you feel ready to perform the techniques on patients during the clinic or do you still have doubts and feel unable to execute them? (5) Give a score to the didactic material presented (on a scale of 0-10) and give your suggestions for any changes.
| Results|| |
The first question evaluated whether the models, images, and videos served as an effective teaching tool. Among the responders 88% rated the material as excellent, 12% as good, 0% as regular (images confused), and 0% as bad (unnecessary materials). The significant proportion of the students rating the presentation as excellent shows that this teaching method was very acceptable to students [Figure 5]a.
The second question assessed whether the student considered valid the review of anatomy before teaching the techniques of local anesthesia. To this question all 130 students answered 'yes.' They felt that a review of anatomy with the use of anatomical models was useful and, moreover, the students realized the importance of applied anatomy in the clinic. Similarly, in answer to the third question, all 130 students felt that the model facilitated learning of correct techniques by allowing visualization of the positioning nerves and needle in the tissues.
In the fourth question, students were asked if after the presentation they felt confident of being able to perform these techniques in patients during the clinic. As [Figure 5]b shows, 70% of students felt able to achieve the block injections in patients. These values coincide with what was observed by teachers in the clinic: i.e., the greater ability of students, higher rate of success of the block, and less anxiety during performance of anesthetic techniques after the use of anatomical models for teaching.
Finally, in the fifth question the students evaluated the content, the quality of the images, the presentation format, the video quality, and the precision of the reproduced anatomical relations. The average grade given by the students on a scale of 0-10 was 9.3.
| Discussion|| |
In dentistry, as in other medical fields, students are faced with the transition from didactic teaching to patient care at the clinic. In the department of oral surgery, the anesthetic injection is the main point of transition, and at this time the students need to recall their knowledge of anatomy and apply them during administration of anesthesia. However, as anatomy is traditionally presented to students early in the curriculum, it is not always easy for the student to recall and apply this knowledge. Thus, it can be useful to have a review of the anatomy of the concerned part before the demonstration of anesthetic techniques. 
Several methods for completing this transition between didactic knowledge and clinical care have been reported. ,,, Practicing anesthetic techniques on anatomical specimens before administering nerve blocks in patients is an effective method of training students, These techniques are performed without any visualization of the deeper anatomical structures. Through the use of models, in combination with images of injections in patients, the student can identify the point of needle penetration in the mucosa and observe its final position in the anatomic space. This makes the technique more easily understandable. It became clear that we associated the images of models with the images of the technique being done in patients, the student could more easily relate the tissue surface with the deeper levels and so understand the technique in its essence.
Through the use of models all anesthetic techniques could be explained. However, some of them have higher failure rates and thus require greater attention. Anesthetic block of the inferior alveolar nerve, for example, has a higher failure rate (15-20% failure rate) than other nerve blocks.  Thus, a large part of the presentation time was reserved for describing the technique in inferior alveolar nerve block.
The trigeminal nerve, were reproduced according to a series of studies. ,,,,, The sensory innervation of the mandibular teeth by the mylohyoid nerve is a factor that contributes to ineffective blockade, as many of these sensory fibers are not anesthetized during the standard inferior alveolar nerve block ,,, With the models it was possible to demonstrate the different positions of the origin of the mylohyoid nerve, allowing the student to understand the anatomical relationship with the inferior alveolar nerve and the clinical implications during the blockade. The anatomical barriers to buccal nerve anesthesia during standard inferior alveolar nerve block and during Gow-Gates mandibular block , could also be explained to the students using the models, where anatomical structures had been reproduced on the basis of dissections shown in the work of Aker. 
The anatomical models described in this article facilitate teaching in many ways. With the use of these models it was possible to conduct a comprehensive review of anatomy, especially the neuroanatomy of the cranial nerves. We could show in detail the path, the ramifications, and anatomical relations of the V th cranial nerve with other structures. Thus, the students perceived the importance of anatomy during the execution of anesthetic techniques in the dental clinic. This method of teaching showed good results regarding the safety of students during the first injection, where 70% of students who had never administered an anesthetic earlier said that they were confident of doing so. The students from the six classes included in the study had lower anxiety and higher success rate when carrying out the procedure on patients in the clinic. Teachers from these two universities had expressed concern regarding the extreme anxiety and apprehension shown by students at the time of their first injection.
Certainly, the experience with the models is different from dealing with actual patients. The students showed great interest in the training material, including the photos and videos, and even wanted to examine the models closely after the presentation. The models provided an overview of the anatomical spaces in the tissues and facilitated the teaching of anatomy and the techniques of local anesthesia administration, and thus had a positive impact on the ability of the students.
| References|| |
|1.||Blanton PL, Jeske AH. The key to profound local anesthesia: Neuroanatomy. J Am Dent Assoc 2003;134:753-60. |
|2.||Jenkins DB, Spackman GK. A method for teaching the classical inferior alveolar nerve block. Clin Anat 1995;8:231-4. |
|3.||Brand HS, Baart JA, Maas NE, Bachet I. Effects of a training model in local anesthesia teaching. J Dent Educ 2010;74:876-9. |
|4.||Brand HS, Tall LL, van der Spek SJ, Baart JA. European dental students opinions on their local anaesthesia education. Eur J Dent Educ 2011;15:47-52. |
|5.||Bonnette GH, Hayward JR. Introductory approach to the study of oral surgery: Preclinical laboratory. J Dent Educ 1969;33:350-4. |
|6.||Barber HD, Kaya K, Lilie J, Raubolt P, Michjalenko W. Human cadaver material in preclinical oral surgery. J Dent Educ 1993;57:29-31. |
|7.||Malamed SF. Manual de Anestesia Local. 5 th ed. Madrid: Elsevier; 2005. |
|8.||Barker BC, Davies PL. The applied anatomy of the pterygomandibular space. Br J Oral Surg 1972;10:43-55. |
|9.||Roda RS, Blanton PL. The anatomy of local anesthesia. Quissentessence Int 1994;25:27-38. |
|10.||Aker FD. Blocking the buccal nerve using two methods of inferior alveolar block injection. Clin Anat 2001;14:111-9. |
|11.||Harn SD, Durham TM. Anatomical Variations and Clinical Implications of the artery to the lingual Nerve. Clin Anat 2003;16:294-9. |
|12.||Sillanpää M, Vuori V, Lehtinen R. The mylohyoid nerve and mandibular anesthesia. Int J Oral Maxillofac Surg 1988;17:206-7. |
|13.||Stein P, Brueckner J, Milliner M. Sensory innervation of mandibular teeth by the nerve to the mylohyoid: Implications in local anesthesia. Clin Anat 2007;20:591-5. |
|14.||Gow-Gates G. Mandibular conduction anesthesia: A new technique using extraoral landmarks. Oral Surg Oral Med Oral Pathol 1973;36:321-8. |
|15.||Gow-Gates G, Watson JE. Gow-gates mandibular block-applied anatomy and histology. Anesth Prog 1989;36:193-5. |
Department of Diagnostic Surgery, School of Dentistry, Estadual Paulista Univesity, São José dos Campos, São Paulo
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]