Quando Usar Gow Gates?
*Assistant Director and Attending Dentist in Anesthesia, Advanced Education in General Dentistry, Attending Dentist in Anesthesia, Graduate Pediatric Dentistry and Dental Anesthesiology, Lutheran Medical Center, Brooklyn, New York, Clinical Associate Professor, Endodontics, Oral and Maxillofacial Surgery and Orthodontics, The Herman Ostrow School of Dentistry of the University of Southern California, Los Angeles, California, Affiliate Assistant Professor, Department of Restorative Dentistry, School of Dentistry, The Oregon Health Science University, Portland, Oregon, Clinical Instructor, Department of Dentistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada, Associate Professor in Residence, The University of Nevada Las Vegas, School of Dental Medicine, Las Vegas, Nevada, Private Practice, Tucson, Arizona
Onset of anesthesia depends on the proximity of the nerve-blocking drug to the related nerve trunk. It is possible that the senior author may not to be sufficiently experienced with this technique and did not deposit the anesthetic solution closely enough to the oral sensory branches of the mandibular nerve in the pterygomandibular space. Accuracy in performing the injection should not, therefore, be neglected in the overall evaluation of the success rate and frequency of successful anesthesia.
Selected References
Immediately after achieving a positive response for anesthesia in all 3 terminal nerve test areas, the extraction began. In this study Grade A anesthesia was considered completely satisfactory anesthesia by the patient and did not require any kind of reinforcement. Grade B was less complete anesthesia, which required another injection for the patient. If pain appeared during the extraction before the 16 minutes after injection, additional time was allowed until the next time level (8, 12, or 16 minutes); pain appearance after 16 minutes post injection was considered Grade B category. Postoperatively, anesthesia was classified as successful anesthesia (Grade A) or unsuccessful anesthesia (Grade B).
‡ Associate Faculty, Swedish Medical Center General Practice Residency, Seattle, Washington, Clinical Assistant Professor, Endodontics, Oral and Maxillofacial Surgery and Orthodontics, The Herman Ostrow School of Dentistry of the University of Southern California, Los Angeles, California, Private Practice, Newcastle, Washington
Results
Supplementary local anaesthesia was administered by buccal (subgroup A) or lingual (subgroup B) infiltration of the 1.8 mL (one cartridges) of same anaesthetic solution for patients who felt pain during cavity preparation (Figure 1). In subgroup A, the solution was injected slowly (over 30 sec) buccal to the tooth apex using standard aspirating dental cartridge syringes. In subgroup B, sub-periosteal infiltration was performed at the mucogingival junction in the lingual furcation area. When complete anaesthesia and analgesia were achieved, access cavity preparation was completed and pulpotomy or pulpectomy was performed, followed by dressing with calcium hydroxide and Coltosol (Coltene Whaledent, Henan, China) as a temporary filling. When complete anaesthesia was not achieved, another type of supplementary injection was used; upon the achievement of complete analgesia, the procedures were completed as described previously, but these cases were excluded from the study.
When a small percentage of B is available, the speed of onset of anesthesia would be considerably slowed were it not for the body's buffering capability. Once injected into the tissues, the natural process of buffering occurs. The normal pH of tissues is 7.4. A drug with a lower pH (e.g. 3.5) that is injected into tissues will be buffered by the body, and the pH of the injected solution will be slowly increased toward 7.4. As this process continues, the percentage of B ions in the solution steadily increases. For example, at a pH of 6.5, 3.83% of lidocaine ions are B, while at a pH of 7.4, this figure is 24.03%.
Abstract
Patients were asked to report when their lips were numb. An operator blinded to injection type then tested the teeth with an EPT. The teeth were tested again 15 min after injection. The canine teeth usually served as the control tooth to assess the success rate of INA block injection; if the canine did not meet the requirements for a control tooth, another tooth in the same quadrant was chosen. All data were recorded into a Microsoft Excel sheet (Microsoft Office Excel 2003). The second operator then initiated the preparation of an access opening in the involved tooth.
The patients were randomly assigned to the groups by selecting a sealed opaque envelope with the group number concealed inside it. Patients in group 1 received standard IANB injections using 2% lidocaine with 1:100000 epinephrine (Persocaine; Darou Pakhsh, Iran). The first author injected the solution using 27-gauge long needles (NRK Medical Devices, Tehran, Iran). After reaching the target area, aspiration was performed and 3.6 mL (two cartridges) solution was deposited at a rate of 1 mL/min.
† Professor, Endodontics, Oral and Maxillofacial Surgery and Orthodontics, The Herman Ostrow School of Dentistry of the University of Southern California, Los Angeles, California
Acknowledgment
The onset of clinically adequate anesthesia was achieved in 8 minutes by 56% of the subjects (9 of 16) of the second group and in 1 of 16 (6.25%) in the first group. At 12 minutes, only 1 subject of the second group reported onset of complete anesthesia (6.25%). At 16 minutes in the second group, 4 of 16 (25%) subjects confirmed onset of complete anesthesia and 1 of 16 (6.25%) of the first group (data not shown).
Study subjects were recruited from patients referred to the Endodontic Department of MUMS. Inclusion criteria were: age of 18‒50 years, good health, provision of informed consent, moderate to severe pain in a mandibular molar, prolonged response to cold testing with cold spray (Endo-Frost; Roeko, Langenau, Germany) positive response to an electric pulp tester (EPT) (Parkell; NY, America), and vital coronal pulp on access opening. Exclusion criteria were: periapical radiolucency, active site of pathosis in the injection area, allergy to lidocaine and/or adrenalin, severe systemic disease contraindicating an endodontic procedure, pregnancy, use of medication that might affect anaesthetic assessment, inability to provide informed consent and understanding the visual analogue scale.
Abstract
The first procedures tested the response of the buccal, lingual, and inferior alveolar nerves, respectively. This test was used because it is still the most available practical clinical test to ensure an objective anesthesia sign before any dental extraction. The test procedures began 8 minutes after the injection, and if pain persisted, additionally every 4 minutes until 16 minutes after injection time. The anesthesia response was recorded as positive or negative.
If the pH of the local anesthetic solution in the dental cartridge could be increased to 7.4 prior to injection, the speed of onset of the anesthetic should increase, as well as the comfort to the patient during the injection. (Local anesthetics at a pH of 3.5 produce a “burning” sensation as they are injected, and higher-pH solutions are rated by patients as more comfortable.) A third advantage to buffering the local anesthetic solution would be the 6,000-fold increase in the number of B molecules available to enter into the nerve, which would theoretically provide a more profound anesthetic effect.
Materials and Methods
In this study 3 time stages were designed (8, 12, and 16 minutes). At 8, 12, and 16 minutes after injection a sharp dental explorer test (sharp stimuli) was used on the buccal mucosa test side, apical to the second mandibular permanent molar. On the lingual mucosa test side, the test was done apical to the first mandibular premolar. On the second buccal mucosa test side, the test was done apical to the first mandibular premolar, then another puncture was made into the buccal and lingual gingival tissue of the teeth involved in the corresponding extraction procedure. The subject's response was recorded for each test side, and also the sensory subjective response of the auriculotemporal nerve was determined and was compared with the contralateral one. The following question was asked: “Does this area feel numb compared to the other area?”
This study achieved an 82.5% incidence of complete anesthesia without the use of reinforcement injections in any nerve when using 3.6 mL of anesthetic solution. Two of 16 patients (17.5%) in the second group (3.6 mL) failed to achieve buccal anesthesia. One of these patients required a first premolar (3.4 international, #21 US) extraction and exhibited pain during the explorer test in the buccal nerve area after 16 minutes post injection. It is possible that extraction of the premolar was not achieved painlessly because of the buccal nerve location that could reach the second permanent premolar buccal tissue; but this study considered successful anesthesia when all test areas were anesthetized (mandibular conduction anesthesia) and when the extraction procedure was intervened without pain, at maximum time of 16 minutes.
Before choosing a mandibular block, there are factors to be evaluated: the type of procedure for the teeth involved and the possible inflammation processes that are present in the tissue puncture target point and in the apical region of the tooth that is to be treated or extracted. Operator experience also needs to be considered. Malamed suggested 2 approaches for becoming proficient with the Gow-Gates technique. The first method is to start using the technique on all patients requiring mandibular anesthesia, allowing a minimum of 1 to 2 weeks, gaining clinical experience. The second method is to continue using the conventional inferior alveolar nerve block but administering the Gow-Gates technique whenever clinically inadequate anesthesia occurs, ie, reanesthetizing the patient using the Gow-Gates technique.