Root canal complications: 'the hypochlorite accident'

Root canal treatment is performed routinely in dental practice, using sodium hypochlorite which serves as an effective irrigant. The literature reviewed shows that several complications following irrigation with sodium hypochlorite may occur, but few practitioners are aware of it and its management. Such complications include injury to skin, oral mucosa and eyes, damage to clothing, air emphysema, allergic reactions, and injection beyond the foramen. In this article, a case report of injection with sodium hypochlorite beyond the foramen is presented, together with a review of the recent literature regarding common manifestations and case histories. The literature shows no standard management of this condition, but symptomatic therapies are discussed. It is important to minimize the risk of sodium-hypochlorite-induced damage during root canal therapy by use of protective measures, appropriate instrumentation and techniques, and consider alternate irrigation solutions.

A prospective, randomized comparison of the anesthetic efficacy of the greater palatine and high tuberosity second division nerve blocks

INTRODUCTION

Few clinical studies have evaluated the efficacy of the maxillary second division nerve block. The purpose of this prospective, randomized study was to compare the anesthetic efficacy of the greater palatine second division nerve block and the high tuberosity second division nerve block technique by using 3.6 mL of 2% lidocaine with 1:100,000 epinephrine.

METHODS

Forty subjects randomly received greater palatine nerve blocks and high tuberosity nerve blocks of 3.6 mL of 2% lidocaine with 1:100,000 epinephrine at 2 separate appointments spaced at least 1 week apart. The anterior, premolar, and molar teeth were pulp tested in 4-minute cycles for a total of 60 minutes.

RESULTS AND CONCLUSIONS

Both techniques resulted in a high success rate of pulpal anesthesia (95%-100%) for first and second molars. Around 70%-80% of the second premolars were anesthetized with both techniques. Both techniques were ineffective for profound pulpal anesthesia of the anterior teeth and first premolars.

Anti-allodynic effect of intracerebroventricularly administered antioxidant and free radical scavenger in a mouse model of orofacial pain

AIMS

To evaluate possible effects of the intracerebroventricular (icv) injection of either O-Tricyclo [5.2.1.0(2,6)] dec-9-yl dithiocarbonate potassium salt (D609), a potent antioxidant and inhibitor of phosphatidylcholine specific phospholipase C (PtdCho-PLC) and acid sphingomyelinase (ASMase), or the spin trap/free radical scavenger N-tert-Butyl-alpha-phenylnitrone (PBN), on mechanical allodynia induced by facial carrageenan injection in mice.

METHODS

Balb/c mice received icy injection of D609/PBN plus facial carrageenan injection, and the number of face wash strokes to von Frey hair mechanical stimulation of the maxillary skin was quantified. PtdCho-PLC and ASMase activities were also assayed in the brainstem, thalamus, and somatosensory cortex.

RESULTS

Mice that received the icy injection of 10 nmol D609 plus facial carrageenan injection showed significantly fewer face wash strokes evoked by von Frey hair stimulation (indicating reduced mechanical allodynia) at 1 and 3 days post-injection, compared to mice that received icy injection of isotonic saline plus facial carrageenan injection. Mice that received icy injection of 1.13 micromol PBN plus facial carrageenan injection likewise showed significantly fewer face wash strokes after facial carrageenan injection, compared to isotonic saline-injected plus carrageenan-injected controls. D609 injection also resulted in significantly reduced ASMase activity in the brainstem, thalamus, and somatosensory cortex 3 days after injection, compared to controls.

CONCLUSION

The icv injections of D609 and PBN were effective in reducing mechanical allodynia after facial carrageenan injection-induced pain. Together, the results point to a possible role of central nervous system sphingolipids and/or free radicals in orofacial pain.

Infraorbital nerve block in children: a computerized tomographic measurement of the location of the infraorbital foramen

BACKGROUND AND OBJECTIVES

Infraorbital nerve blocks are performed in children undergoing cleft-lip surgery and endoscopic sinus surgery. The nerve exits the maxilla at the level of the infraorbital foramen. A sensory block of the infraorbital nerve can be performed by use of an intraoral route or an extraoral route. The objective of this study was to derive a mathematical formula to determine the position of the infraorbital foramen.

METHODS

Computerized tomographic (CT) scans of children who were admitted to our institution for various reasons were evaluated with the assistance of a pediatric neuroradiologist. The distance of the foramen from the midline was determined, and a mixed-effects linear-regression model was used (PROC MIXED in SAS 9.1) to ascertain whether the distance of the infraorbital foramen correlated linearly with the age of the patient.

RESULTS

CT scans of 48 pediatric patients were evaluated. The age of the patient accounted for more than half of the variation in this model. Distance of the infraorbital foramen can be predicted by use of the following formula: [Distance of the infraorbital foramen (in mm) from midline = 21.3 + 0.5 x age (in years)].

CONCLUSIONS

Our study found a linear correlation with age to the distance of the infraorbital foramen. This anatomic knowledge of the location of the infraorbital foramen may facilitate correct positioning of the needle. Future studies on the use of this formula with anatomic coordinates should be performed to test the validity of this formula.

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.

Effectiveness of nasopalatine nerve block for anesthesia of maxillary central incisors after failure of the anterior superior alveolar nerve block technique

The purpose of this study was to assess the effectiveness of nasopalatine nerve block for anesthesia of maxillary central incisors after failure of the anterior superior alveolar nerve (ASAN) block technique. Secondarily, the possible innervation of the maxillary central incisors by the nasopalatine nerve was also investigated. Twenty-seven healthy, young adult volunteers (age: 17-26 years; gender: 9 males and 18 females) were enrolled in this study. All participants were undergraduate dental students of the University of Vale do Rio Verde de Três Corações. The volunteers had the anterior superior alveolar nerves anesthetized and a thermal sensitivity test (cold) was performed on the maxillary central incisors. The volunteers that responded positively to cold stimulus received a nasopalatine nerve block and the thermal sensitivity test was repeated. All participants were anesthetized by a single operator. Three patients presented sensitivity after both types of bilateral blocks and were excluded from the percentage calculations. In the remaining 24 patients, 16 had their maxillary central incisors anesthetized by the anterior superior alveolar block and 8 remained with sensitivity after the ASAN block. All these 8 patients had their maxillary central incisors successfully anesthetized by the nasopalatine block. In this study, 33.3% of the subjects had the innervation of one or both maxillary central incisors derived from the nasopalatine nerve, whilst most subjects (66.7%) had such teeth innervated by the anterior superior alveolar nerve. The nasopalatine nerve block was effective in anesthetizing the maxillary central incisors when the anterior superior alveolar nerve block failed.

[Pharmacological and physiological specificities of local anesthesia in dentistry]

Described in the paper are the specificity of local analgesia at the medical dental procedures and the effect produced by local anesthetics and vasoconstrictive agents on the induction of nervous fibers and peripheral blood circulation. The pharmacological-and-physiological mechanisms of local analgesia by a 2% artikain solution (with adrenalin, concentration 1:100,000) and by a 2% mepivakain solution (with adrenalin, concentration 1:100,000) exerted on the pain sensitivity and blood circulation in the tooth pulp are analyzed.

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.

A new method of continuous maxillary nerve block with an indwelling catheter

OBJECTIVE

We describe continuous maxillary nerve block at the pterygopalatine fossa and investigate the efficacy of this technique for perioperative pain control in oral surgery.

STUDY DESIGN

Sixteen patients undergoing radical maxillary sinusotomy were enrolled; group I (n = 8) received general anesthesia without maxillary nerve block, and group II (n = 8) received maxillary nerve block before general anesthesia. The intraoperative concentration of sevoflurane, the extent of blockade, and total analgesics (diclofenac sodium) needed after surgery were recorded.

RESULTS

The mean sevoflurane concentration was significantly lower in group II. Diclofenac sodium consumption was significantly reduced in group II.

CONCLUSION

Indwelling maxillary nerve catheter methods decrease anesthetic consumption and provide good postoperative analgesia.

Influence of anesthetic flow rate delivered by the Wand Local Anesthetic System on pain response to palatal injections

PURPOSE

To compare pain response between two different flow rates (slow versus fast) of local anesthetic solution injected into palatal tissue using the recently available Wand Local Anesthetic System (WLAS), which provides the technologic advance to permit reliable replication of constant injection flow rates, regardless of tissue resistance.

METHODS AND MATERIALS

Twenty adult subjects received bilateral palatal injections of local anesthetic in random sequence during the same appointment following topical anesthesia application. Pain response was measured by subjective self-report using a visual analogue scale, a quantified verbal descriptor scale, and a comparison to prior injection experience, as well as an operator's global assessment of the subject's pain response. Heart rate, as a physiologic indicator of pain response, was also recorded.

RESULTS

All measurements of pain response were statistically less for the slow compared to the fast injection rate. No significant difference in mean heart rate, however, was demonstrated between the two flow rates. A slow, constant flow rate (161 sec/mL) of a 0.3 mL volume of local anesthetic solution was statistically less painful than a fast flow rate (29 sec/mL) during palatal injection. Contrary to the manufacturer's claim, the WLAS reduced but did not eliminate pain elicited by palatal injections in some patients.

Diplopia as a complication of local anesthesia: a case report

Diplopia caused by local anesthesia at the superior posterior alveolar nerve for the removal of the maxillary third molar is a rare complication. The diplopia is due to facial palsy of the oculomotor muscles of the globe. This paper describes the case of a 22-year-old woman, in whom diplopia was observed after an overall uncomplicated removal of the semi-impacted third molar. Possible causes of the anesthetic effects are reported. The most accepted explanation is that the anesthetic diffuses on the abducent nerve in the cavernous sinus. The necessary actions that the dental surgeon must perform are reported.

Structure-function relationships in rat brainstem subnucleus interpolaris. X. Mechanisms underlying enlarged spared whisker projections after infraorbital nerve injury at birth

Prior studies indicate that the central projections of noninfraorbital vibrissae occupy greater than normal transverse areas in the rat trigeminal brainstem complex after infraorbital nerve section at birth. Here, we assessed the development of this phenomenon and possible underlying mechanisms. Cytochrome oxidase patches representing spared supraorbital (SO) or posteroorbital (PO) whiskers in the trigeminal subnucleus interpolaris (SpVi) were not reliably larger than those on the control side 24 hr after the infraorbital lesion. By 72 hr, SO and PO patches were 91% and 28% larger than those on the control side. Reliable increases were also observed on postnatal day 5 (PND5), PND7, and PND10 for the SO (59%, 65%, 66%) and PO (23%, 44%, 51%) patches. To test the hypothesis that central reorganization reflects the maintenance of peripheral supernumerary axons, myelinated and unmyelinated axons in SO vibrissa follicles were counted at PND0, PND7, PND17, and PND60. A corollary hypothesis, that peripheral regeneration errors result in both SO and surviving infraorbital axons, contributing to central SO patches, was tested with retrograde double-labeling methods. Both hypotheses were rejected. Thus, enlargement of SO patches is not due to either the maintenance of an immature peripheral innervation pattern, or regeneration of infraorbital axons into SO follicles. To determine if the enlargement of SO and PO patches produced by infraorbital nerve section is due to an activity-dependent competitive disadvantage imposed upon infraorbital afferents, TTX or bupivicaine was applied to the intact infraorbital nerve over the first 5-9 postnatal days. Brainstem maps developed normally and SO and PO patch areas were unaffected. Thus, impulse activity-based mechanisms do not appear to contribute to injury-induced patch enlargement. To test the hypothesis that patch enlargement is due to central collateral reorganization, intra-axonal recording and staining methods were applied to control and spared-whisker primary afferents in adult rats. Total bouton or collateral numbers did not differ in SpVi; however, arbor areas were reliably larger in experimental (14,879 +/- 350 microns 2) versus control (5527 +/- 1811 microns 2) fibers.(ABSTRACT TRUNCATED AT 400 WORDS)

Duration of experimental nerve block by combinations of local anesthetic agents

The effects of bupivacaine-prilocaine and meperidine-lidocaine combinations (as compared with those of the agents used alone) on the duration of peripheral sensory nerve block were studied with the infraorbital nerve block model (IONB) in the rat, and those on motor block with spinal anesthesia (SA) in the mouse. The duration of bupivacaine-induced IONB was invariably prolonged when prilocaine was included in the solution. When included in 0.125% bupivacaine, 1.0% prilocaine had a slightly less pronounced enhancing effect than 0.5% prilocaine (24-57% vs. 74%-104%, respectively). The duration of IONB with 1.0% prilocaine was significantly reduced (14-37%) by inclusion of 0.125% bupivacaine. In SA, inclusion in 0.125% bupivacaine of prilocaine (0.5% or 1.0%) prolonged motor block by 128% and 192%, respectively. When included in 0.25% bupivacaine, both 0.5% and 1.0% prilocaine significantly reduced the duration of SA, by 42% and 37%, respectively. With one exception, the duration of IONB by meperidine was significantly shortened (< 44%) when lidocaine was included in the solution. In SA, inclusion of 2% lidocaine with 2% meperidine did not affect the duration of meperidine-induced motor block. The duration of SA obtained with the combination of 4% lidocaine and 4% meperidine was 45% shorter than that induced by 4% meperidine alone. The reasons for these variable effects are not clear, but may be due to interaction or antagonism at any of multiple sites.

Epinephrine as an adjuvant to amino-amide local anesthetics does not prolong their duration of action in infraorbital nerve block in the rat

The effects of epinephrine as an adjuvant to local anesthetics were studied in the rat infraorbital nerve block (IONB) model, using solutions of 0.5% prilocaine, 0.5% mepivacaine, 0.125% bupivacaine or 0.125% ropivacaine in 50 mmol/l tris-hydroxymethylaminomethane (THAM) tested both without and with epinephrine (EPI) added at 2, 4, 8 or 16 micrograms/ml. Solutions of THAM and EPI in normal saline did not induce IONB. THAM-buffered solutions of bupivacaine induced IONB of longer duration than bicarbonate-buffered solutions. Intensity of block during onset was increased only when EPI at 2 and 16 micrograms/ml was included in bupivacaine solutions. The duration of block induced by prilocaine, bupivacaine and ropivacaine was not significantly prolonged by addition of EPI at any of the concentrations tested. Only at a concentration of 16 micrograms/ml did EPI significantly prolong the duration of mepivacaine-induced block (+48%). Low concentrations of EPI in solutions of bupivacaine and ropivacaine significantly reduced their duration of action by up to 22% and 57%, respectively. It is concluded that the duration of action of local anesthetics in buffered solutions is only moderately affected by the inclusion of EPI, the effects differing only slightly from one to another. The efficacy of EPI as an adjuvant would seem to be governed by factors affecting the local disposition of the main drugs, such as non-specific binding, buffering of solutions and tissue pH.

Effects of glycerol on the rat infraorbital nerve: an experimental study

Glycerol was injected into the infraorbital canal of 12 rats to determine neurolytic effects on the peripheral trigeminal nerve. Saline and 90% ethanol were injected in control animals. One week after the injection, histopathological changes were noted in both glycerol and alcohol groups. In the former group, axonolysis and demyelination were restricted to the outer zone of the nerve bundles. Centrally located axons remained undamaged. A total destruction of all axons was found in the alcohol group. Four weeks after the injection in the glycerol group, small sized axons with thin myelin replaced damaged axons at the periphery of the bundle. No signs of regeneration were noted in the alcohol group. A possible mode of action of glycerol injected at the peripheral trigeminal nerve in relieving trigeminal neuralgia is described.

A retrospective study of paresthesia of the dental alveolar nerves

Paresthesia is a rare clinical finding subsequent to surgery accompanied by the administration of local anesthetics. A small patient population was identified whose clinical problem may be explained by neurotoxicity due to a local anesthetic metabolite. Reasonable questions arise from these clinical observations that would benefit from prospective studies to explain sensory loss on a biochemical basis.

Expansion of receptive fields in the mouse cortical barrelfield after administration of capsaicin to neonates or local application on the infraorbital nerve in adults

A possible role fore peripheral unmyelinated fibres on the establishment and maintenance of stable receptive fields mediated by myelinated afferents has been studied in the mouse cortical barrelfield. The barrels are cytoarchitectonic units consituting a visible and particularly precise somatotopic map of the facial vibrissae. Barrelfields were mapped electrophysiologically in adults using two experimental setups: (i) after destruction of unmyelinated peripheral fibres by systemic administration of capsaicin neonatally; and (ii) after inactivation of these fibres by local application of capsaicin to the nerve subserving the vibrissae in the adult. The latter procedure is known not to destroy fibres. Control animals received the vehicle used to dissolve capsaicin. The effectiveness of capsaicin on the peripheral fibres was assessed histochemically on their terminals in the substantia gelatinosa. Both methods of application of capsaicin resulted in a large expansion of cortical receptive fields: units within a particular barrel were driven by a statistically significant, larger number of vibrissae than in controls. No morphological alterations of the barrels were found in cortical tangential sections. We concluded that capsaicin treatment 'defocusses' the normal physiological precision without destroying the general plan of representation and without alteration of the barrel pattern.

Effect of anticonvulsant drugs on inhibitory and excitatory pathways

A conditioning stimulus to the periventricular gray matter inhibits the response of spinal trigeminal neurons to maxillary nerve stimulation. Sodium valproate and ethosuximide decrease the periventricular inhibition without significantly affecting the response of these neurons to the unconditioned maxillary nerve stimulus. We have now found that carbamazepine and phenytoin decrease the response to the unconditioned maxillary nerve stimulus, and only depress the periventricular inhibition secondarily. These results further support the hypothesis that the ability to depress selectively inhibitory pathways in the CNS is an important characteristic of antiabsence drugs, and that absence seizures may represent paroxysmal discharges in inhibitory pathways.

Epileptogenic agents applied to trigeminal ganglia: absence of neuronal hyperexcitability

Chronic application of alumina cream to the trigeminal ganglion in 10 cats failed to produce a long-lasting behavioral syndrome of facial dysesthesia. Histologic and electron microscopic analysis demonstrated morphologic similarities between these ganglia and primate neocortical alumina cream epileptic foci. None of 87 ganglia neurons recorded extracellularly exhibited evidence of intrinsic hyperexcitability, i.e., abnormal spontaneous or physiologically evoked activity or any significant differences in threshold of responses to antidromic or orthodromic electrical stimulation, compared to 67 normal ganglion cells. Furthermore, topical application of penicillin to normal ganglia failed to produce abnormal activity in 42 neurons tested. These data suggest that neuronal somata lacking either dendrites or postsynaptic membranes, or both, do not develop abnormal firing behavior when challenged with these two epileptogenic agents.