The triangle of safety: a modified posterior superior alveolar injection technique based on the anatomy of the PSA artery

The posterior superior alveolar (PSA) injection technique is commonly used to anesthetize soft and hard tissues of the posterior maxilla. As with all injections, complications arise, including hematoma formation secondary to needle-induced vascular trauma. In an attempt to develop a hemorrhage-free PSA injection technique, 361 infratemporal dissections were completed on human cadaver specimens. Three distribution patterns were identified for the external branch of the PSA artery. Regardless of distribution pattern, an anatomical Triangle of Safety was found superior to the maxillary second molar that was free of neurovascular tissues in more than 99% of individuals. Injection into this area appears to meet anesthetic needs while reducing the risk of hematoma formation. The combination of this anatomical triangle with newer anesthetic agents and computerized delivery systems holds promise for continued improvement of the PSA injection technique.     

Ocular complications after posterior superior alveolar nerve block: a case of trochlear nerve palsy

Many intraoperative complications occurring during third molar surgery are described in the literature. Unilateral trochlear nerve palsy secondary to dental anaesthesia is a rare complication. We report the case of a 36-year-old healthy man, ASA I classification, requiring upper third molar extraction. Articaine 1:200,000 epinephrine for right posterior superior alveolar (PSA) nerve block was administered locally in the mucobuccal fold above the upper third molar. A few minutes after PSA nerve block the patient experienced double-vision. The patient was subsequently visited by an ophthalmologist and the condition was diagnosed as transient unilateral vertical diplopia due to temporary paralysis of the superior oblique muscle as a result of the anaesthetic solution involving the IV cranial nerve. The authors report this unusual case and discuss the possible anatomical pathways that might explain this rare phenomenon.     

Transient diplopia from a posterior alveolar injection

Several anatomical vascular pathways have been proposed to explain oculomotor disturbances observed after injection of local dental anesthetics. The author suggests another possible pathway to account for the unusual clinical observations described in this report.     

Transitory paresis of the lateral pterygoid muscle during a posterior superior alveolar nerve block--a case report

The posterior superior alveolar nerve (PSAN) is a major sensory branch of the maxillary division of the trigeminal nerve. A PSAN block is a dental nerve block used for profound anesthesia of the maxillary molars. Complications arising from the PSAN block include hematoma formation, transient diplopia, blurred vision, and temporary blindness. This article presents a case of temporary paresis in the lateral pterygoid muscle following a PSAN block that utilized a 27-gauge long needle. The anatomical parameters and pathogenesis of such a complication are reviewed.     

Esotropia following posterior superior alveolar nerve block.

Adequate use of local anesthetics is an important phase of modern dentistry. Regardless of the care used in administration of local anesthetics, unusual reactions can occur. A case is presented in which posterior superior alveolar administration of two percent Lidocaine 1/100,000 epinephrine resulted in medial rotation of the orbit (esotropia).     

Anesthetic efficacy of the palatal-anterior superior alveolar injection

BACKGROUND: A single palatal-anterior superior alveolar, or P-ASA, injection has been reported to provide pulpal anesthesia of the four maxillary incisors and usually the canines. The authors conducted a prospective, randomized, double-blind study to compare the anesthetic efficacy of 2 percent lidocaine with 1:100,000 epinephrine and 3 percent mepivacaine using a computer-assisted injection system to administer the P-ASA injection. MATERIALS AND METHODS: In a double-blind manner, the authors used a crossover design to administer randomly P-ASA injections of 1.4 milliliters of the lidocaine solution and 1.4 mL of the mepivacaine solution using the computer-assisted injection system at two appointments to 40 subjects. They used a pulp tester to test for anesthesia of the central incisors, lateral incisors and canines in four-minute cycles for 72 minutes. Anesthesia was considered successful when two consecutive maximum readings (80 readings) with the pulp tester were obtained. RESULTS: For the lidocaine solution, successful pulpal anesthesia ranged from 32 to 58 percent for the six anterior teeth. For the mepivacaine solution, successful pulpal anesthesia ranged from 22 to 38 percent. Except for the left canine, the lidocaine solution was significantly more likely to result in pulpal anesthesia than the use of the mepivacaine solution. The duration of pulpal anesthesia, for both solutions, declined steadily over 72 minutes. CONCLUSIONS AND CLINICAL IMPLICATIONS: Using the computer-assisted injection system for the P-ASA injection, we concluded that the rather modest-to-low success rates of the lidocaine and mepivacaine solutions would not ensure predictable pulpal anesthesia of the four maxillary incisors and the canines.     

Detection of posterior superior alveolar artery using multi-detector row CT: a retrospective study focused on age-related changes

Oral Radiology - The posterior superior alveolar artery (PSAA) is a branch of the maxillary artery that supplies the lateral sinus wall and overlying membrane. This artery is one among several...     

The bucco-gingival branch of the posterior superior alveolar artery: a source of haematomata when injecting in the maxilla

A bstract — Anatomical dissections and examination of the soft tissues in the region of the buccal sulcus of the maxilla reveal the presence of a bucco-gingival branch of the posterior superior alveolar artery which approaches the infra-orbital surface of the maxilla. In some specimens this was found to anastomose with the infraorbital artery. It is suggested that this branch is the major contributor to rapidly forming haematomata which may sometimes occur following injections to obtain anaesthesia of the maxillary teeth. A modification to accepted techniques for local anaesthesia is proposed to avoid or minimize this complication.     

Comparison of posterior alveolar canal location measured on computer tomography scan with cadaveric measurement of posterior superior alveolar foramen in Japanese samples

The aim of this study was to analyse anatomical characteristics of the most posterior alveolar canal (PAC) on computed tomography (CT) images and the posterior superior alveolar foramen (PSAF) physically identified in cadaveric samples, to avoid injuring the posterior superior alveolar artery (PSAA) during surgery in the maxillary tuberosity region. The study included 125 hemi-heads of 64 Japanese cadavers. Simple CT data of the maxillary bone region of the samples were obtained and analysed using measurement software. The alveolar crest (AC) and the PAC were identified to calculate the shortest distance between the AC and the PAC (AC-PAC). Then the samples were dissected to measure physically the shortest distance between the AC and the PSAF (AC-PSAF). The data were analysed statistically. The mean value and standard deviation were 20.7 ± 4.2 mm for AC-PAC and 20.7 ± 4.3 mm for AC-PSAF. The intraclass correlation coefficient between AC-PAC and AC-PSAF was 0.98. The CT-measured PAC locations were found to be almost identical to the PSAF positions identified physically in the samples. Preoperative CT localization of the PAC aids in avoiding injury to PSAA, while preoperative CT evaluation is important for each case due to significant individual variability in the anatomical PAC and PSAF locations.     

Evaluation of the posterior superior alveolar artery location and diameter with a newly defined stable plane

The aim of this study was to analyse the vertical location of the posterior superior alveolar artery (PSAA) using a reliable new reference plane regardless of tooth and alveolar bone, and to measure the diameter in each posterior tooth region, which is of relevance to lateral sinus floor elevation surgery. A total of 270 sinuses in 139 patients were examined in this study. The A-plane was defined by A-point and the bilateral jugal points on reconstructed three-dimensional images. The distance from the PSAA to the defined plane was measured in four regions: first premolar (P1), second premolar (P2), first molar (M1), and second molar (M2). The average distance of the PSAA above the plane in the P1, P2, M1, and M2 regions was determined to be 10.24 mm, 7.35 mm, 5.47 mm, and 7.23 mm, respectively. The PSAA was found to run above the plane in 97.4% of sinuses, below the plane in 1.1%, and on the plane in 1.5%. In conclusion, the new plane is useful for intraoperative location of the PSAA. According to the study findings, the area below the reference plane can be considered safe for lateral approach sinus surgery in terms of preserving the integrity of the PSAA.     

Location of posterior superior alveolar artery and evaluation of maxillary sinus anatomy with computerized tomography: a clinical study

Objectives: Knowledge and evaluation of the maxillary sinus anatomy before sinus augmentation are essential for avoiding surgical complications. Posterior superior alveolar artery (PSAA) is the branch of maxillary artery that supplies lateral sinus wall and overlying membrane. The aims of this study were to examine the prevalence, diameter, and location of the PSAA and its relationship to the alveolar ridge and to study the prevalence of the sinus pathology and septum using computerized tomography (CT) scans. Materials and methods: One hundred and twenty‐one CT scans (242 sinuses) from patients undergoing sinus augmentation procedure and/or implant therapy were included. Lower border of the artery to the alveolar crest, bone height below the sinus floor to the ridge crest, distance of the artery to the medial sinus wall, diameter of the artery, and position of the artery were measured; presence of septa and pathology were recorded from CT sections. Results: Prevalence of sinus septa and sinus pathology was 16.1% and 24.8%, respectively. Artery was seen in 64.5% of all sinuses and was mostly intraosseous (68.2%). Mean diameter of PSAA was found 1.3 ± 0.5 mm. No significant correlation between the diameter of the artery and age was observed. Conclusions: The results from this study suggested that CT scan is a valuable tool in evaluating presence of sinus pathology, septa, and arteries before maxillary sinus surgery. Although variations exist in every patient, the findings from this study suggest limiting the superior border of the lateral window up to 18 mm from the ridge to avoid any potential vascular damage. To cite this article:
Güncü GN, Yildirim YD, Wang H‐L, Tözüm TF. Location of posterior superior alveolar artery and evaluation of maxillary sinus anatomy with computerized tomography: a clinical study.
Clin. Oral Impl. Res. 22 , 2011; 1164–1167.
doi: 10.1111/j.1600‐0501.2010.02071.x     

The prevalence and location of the posterior superior alveolar artery in the maxillary sinus wall: A preliminary computed-cone beam study

The lateral wall of the maxillary sinus is supplied by the posterior superior alveolar artery (PSAA). It may be affected by trauma, pathology, or surgery performed to access or correct any fracture involving the maxillary sinus. This study analysed the prevalence and distance of the PSAA from the floor of the maxillary sinus in selected Southeast Asian patients. Methods: This is a cross sectional study conducted using cone-beam computed tomographic images of 83 dentate patients with a mean age of 38.3 years. Results: One hundred sixty-six maxillary sinuses of 54 males and 29 females were evaluated, with PSAA observed in 91.6 % of sinuses. Of the PSAA identified (n = 152), 64.5 % were intraosseous (n = 98), 25.7 % were beneath the sinus membrane (n = 39), and the remaining 15 (9.9 %) were on the external cortex of the lateral sinus wall. The mean distance between PSAA and the lowest point of the sinus floor was 11.44 mm (SD, 3.36). Sixty-four maxillary sinus walls (38.6 %) presented with 2 PSAA branches. The inferior and superior branches were located 6.42 mm (SD, 2.68) and 8.48 mm (SD, 3.56) from the floor of the maxillary sinus, respectively. The mean difference between these 2 branches was 2.25 mm (SD, 1.90). Conclusion: This study confirms the different locations of the PSAA in relation to the lateral wall of the maxillary sinus with no gender influence. Branching of PSAA occurs, and should be highlighted to surgeons.     

上牙槽前、中神经阻滞麻醉技术在上颌牙周治疗中的应用

目的研究采用计算机控制局部麻醉仪行上牙槽前、中神经阻滞麻醉（AMSA）在上颌牙周治疗中的临床效果。 方法选取45例因牙周炎需要进行牙周治疗的患者,随机将上颌牙列左右两侧分为试验组及对照组,分别采用AMSA及局部浸润麻醉,麻醉药物均为4%阿替卡因。注射后采用10点视觉模拟标尺表（VAS）比较注射疼痛,通过临床评估及问卷调查评估麻醉效果、并发症情况、麻醉后唇颊不适程度及麻醉时间,分别采用t检验、卡方检验、Fisher精确检验及秩和检验进行统计学分析。 结果试验组VAS值为1.86 ± 0.76,对照组为3.18 ± 1.05,试验组明显低于对照组（t = -9.487,P<0.001）。试验组成功率为82.2%,对照组为93.3%,差异无统计学意义（χ² = 1.6571,P = 0.198）。试验组并发症发生率为2.2%,对照组为0,差异无统计学意义（P = 0.5）。试验组患者均无唇颊麻木不适感,而对照组中,患者均有不同程度的麻木不适感,麻醉后舒适程度试验组显著优于对照组（Z = -8.857,P<0.001）。试验组麻醉时间均为30~90 min,而对照组中83.3%为61~120 min,试验组麻醉时间明显短于对照组（Z = -5.748,P<0.001）。 结论在上颌牙周治疗中,采用计算机控制局部麻醉仪进行AMSA具有一定优势,患者感觉舒适,更容易被接受。     

Efficacy of anterior and middle superior alveolar (AMSA) anesthesia using a new injection system: the Wand.

OBJECTIVE: This study examined the effect of anterior and middle superior alveolar (AMSA) field block of maxillary nerves using a new local anesthetic system--the Wand. METHOD AND MATERIALS: Twenty healthy volunteers aged 23 to 44 years were used in the study. Either side of the maxillary teeth was randomly selected for AMSA injection; the other side was left as a control. For each side, 1.8 mL of 2% lidocaine solution with 1/80,000 epinephrine was injected by the Wand on a point that bisects the maxillary first and second premolars and is midway between the crest of the free gingival margin and the midpalatine suture. Pain rating score (PRS) and visual analogue scale (VAS) were applied for measurement of puncture, insertion, and injection pain. Electric pulp stimulation was given to each maxillary tooth every 10 minutes for 1 hour after the injection in order to find out the specific tooth on which AMSA injection was effective. RESULTS: During needle insertion, 14 out of 20 subjects answered moderate pain and VAS showed 27.3 mm (mean). During injection, 11 of 20 revealed no pain and the mean of VAS was 14.5 mm. No one claimed severe pain by PRS. Electric pulp stimulation indicated that lateral incisors, canines, and first and second premolars were more anesthetized than central incisors and first molars. CONCLUSION: AMSA injection using the Wand method seems to avoid severe injection pain and seems to be very effective for pulpal anesthesia at lateral incisors, canines, and premolars.