Supplementary routes to local anaesthesia

The satisfactory provision of many dental treatments, particularly endodontics, relies on achieving excellent pain control. Unfortunately, the administration of a local anaesthetic solution does not always produce satisfactory anaesthesia of the dental pulp. This may be distressing for both patient and operator. Fortunately, failure of local anaesthetic injections can be overcome. This is often achieved by using alternative routes of approach for subsequent injections. Nerves such as the inferior alveolar nerve can be anaesthetized by a variety of block methods. However, techniques of anaesthesia other than the standard infiltration and regional block injections may be employed successfully when these former methods have failed to produce adequate pain control. This paper describes some supplementary local anaesthetic techniques that may be used to achieve pulpal anaesthesia for endodontic procedures when conventional approaches have failed. Although some of these techniques can be used as the primary form of anaesthesia, these are normally employed as 'back-up'. The methods described are intraligamentary (periodontal ligament) injections, intraosseous anaesthesia and the intrapulpal approach. The factors that influence the success of these methods and the advantages and disadvantages of each technique are discussed. The advent of new instrumentation, which permits the slow delivery of local anaesthetic solution has led to the development of novel methods of anaesthesia in dentistry. These new approaches are discussed.     

Dental treatment need and dental general anesthetics among preschool‐age children with cleft lip and palate in northern Finland

Cleft lip and palate incidence is high in northern Finland. This study aimed to investigate the proportion of children in need of restorative dental treatment among cleft lip and palate patients in northern Finland, as well as their need for dental treatment under general anesthesia. The records of 183 cleft lip and palate patients, treated in Oulu University Hospital from 1997 to 2013, were reviewed. Data on dental caries were analyzed in association with cleft type, considering also the presence of syndromes. The frequency of dental general anesthetic (DGA) use, and of treatments, were also analyzed. Dental treatment need was most frequently observed, in this rather limited study population, in patients with the most severe deformities, namely bilateral cleft lip and palate, of whom 60% had caries. Among the study population, 11.5% (n = 21) had a syndrome. Of those, 57.1% had dental caries at the age of 3 or 6 yr, and only four could be treated without a DGA. Dental treatment under general anesthesia was performed in 14.8% of cleft patients without a syndrome, but in 38.1% of those with a syndrome. General anaesthesia is required for the provision of dental care more often in cleft (17.5%) than in non‐cleft (0.2%) patients, and especially for those with a syndrome.     

Dental caries, age and anxiety: factors influencing sedation choice for children attending for emergency dental care

OBJECTIVES: The aim of the study was to examine how physical (dental caries) and psychosocial (age, dental anxiety and dental health behaviour) factors, associated with child and parent, influenced dentists' sedation choice when a child presents in pain. METHODS: 600 parents whose children were aged between 5 and 11 years took part: 200 attended for routine dental care (RDC); the remaining 400 attended as emergency patients and were offered either dental general anaesthesia (DGA) or relative analgesia (RA). The subjects were approached and invited to take part. The researcher was blind as to the child's pattern of dental attendance and the type of sedation offered. All parents and children completed self-reported ratings of dental anxiety. The children's teeth were examined to determine past and present dental caries experience. RESULTS: The results showed that children who were offered DGA had greater experience of dentinal caries, were younger and dentally anxious. The children offered RA were older, had a higher frequency of brushing their teeth with fluoride toothpaste and were also dentally anxious. Discriminant analysis showed that 2 canonical functions provided clear categorisation of the three treatment groups. Function 1 was a physical (dental caries) factor, which was related to the child's experience of dentinal caries. Function 2 was a psychosocial factor, which was related to the child's age, dental anxiety and frequency of tooth brushing. A greater proportion of the variance in the treatment offered was explained by Function 1, suggesting that the most important factor in the decision to offer DGA was dentinal caries. Function 2 was of lesser importance. CONCLUSIONS: The findings have implications for the type of sedation offered to children presenting for emergency care. These children may not otherwise receive treatment and the need to provide less anxiety provoking forms of sedation must be promoted. By doing so, parents who have only brought their children when in pain may take advantage of RDC and the treatments offered to prevent and control dental caries and anxiety in their children.     

The effect of electronic dental analgesia during sonic scaling

Abstract The aim of the present study was to investigate the effects of electronic dental analgesia (EDA) during sonic scaling. The clinical trial included 30 healthy adult subjects and was conducted as a randomised single-blind split-mouth design. The applied procedure consisted of periodontal scaling by means of a sonic sealer, while using the EDA device either in an active or placebo state. Rather similar results were obtained for the subjective pain rating in both the active and the placebo trials. When patients rated their discomfort on a scale 0-4 from no pain to very severe pain, the mean (s.d.) score for both the EDA and the placebo was 1.2 (0.6). The subjective pain estimate was positively correlated to the electrical current intensity provided. This implied that with a stronger pain experience, patients tried to administer more anaesthesia by turning the dial of the control box to an increased intensity of the electrical current. This remained insufficient to eliminate pain sensation. It was concluded that application of electronic dental anaesthesia in periodontal treatment remains questionable.     

Articaine buccal infiltration enhances the effectiveness of lidocaine inferior alveolar nerve block

Aim  To compare mandibular tooth pulpal anaesthesia and reported discomfort following lidocaine inferior alveolar nerve block (IANB) with and without supplementary articaine buccal infiltration.
Methodology  In this prospective randomized double-blind cross-over study, thirty-six healthy adult volunteers received two IANB injections of 2 mL lidocaine 2% with epinephrine 1 : 80 000 over two visits. At one visit, an infiltration of 2 mL of articaine 4% with epinephrine 1 : 100 000 was administered in the mucobuccal fold opposite a mandibular first molar. At the other visit, a dummy injection was performed. Injection discomfort was recorded on 100 mm visual analogue scales. Pulpal anaesthesia of first molar, premolar, and lateral incisor teeth was assessed with an electronic pulp tester until 45 min post-injection. A successful outcome was recorded in the absence of sensation on two or more consecutive maximal pulp tester stimulations. Data were analysed using McNemar and Student's t -tests.
Results  The IANB with supplementary articaine infiltration produced more success than IANB alone in first molars (33 volunteers vs. 20 volunteers respectively, P  < 0.001), premolars (32 volunteers vs. 24 volunteers respectively, P  = 0.021) and lateral incisors (28 volunteers vs. 7 volunteers respectively, P  < 0.001). Buccal infiltration with articaine or dummy injection produced less discomfort than IANB injection ( t  = 4.1, P  < 0.001; t  = 3.0, P  = 0.005 respectively).
Conclusions  The IANB injection supplemented with articaine buccal infiltration was more successful than IANB alone for pulpal anaesthesia in mandibular teeth. Articaine buccal infiltration or dummy buccal infiltration was more comfortable than IANB.     

The effectiveness of electronic pulsed soft tissue vibration compared with topical anaesthesia in reducing the pain of injection of local anaesthetics in adults: a randomized controlled split-mouth clinical trial

The purpose of this study was to evaluate the effectiveness of an electronic hand-held pulsed vibration device on the pain of local analgesia (LA) injection and physiologic changes. A prospective randomized controlled clinical trial using split-mouth (crossover) design was implemented. The control-side injection was performed after using topical anaesthesia. The experimental side injection was carried out without topical anaesthesia, but with the aid of a switched-on vibration device. Overall, 332 dental LA injections were given to 166 patients for routine exodontia. The pain at penetration and pain during injection were significantly lower in the experimental sides (vibrations sides) compared with those of the controls (P < 0.001). Similarly, the heart rate changes at penetration and during injections were significantly lower in the experimental sides (P < 0.001). The vibration device was clinically and statistically more effective than topical anaesthesia in the reduction of dental injection pain in adults, measured subjectively and objectively, regardless of the gender, injection technique (infiltration or block) or anxiety level.     

Fatal subarachnoid haemorrhage associated with dental local anaesthesia

A case is described of sudden death occurring after the use of a noradrenaline-containing local anaesthetic. Autopsy revealed a massive subarachnoid haemorrhage following a ruptured cerebral aneurysm. The noradrenaline in the local anaesthetic is thought to be an important factor in the cause of the rupture. It is recommended that preparations containing 1:25,000 noradrenaline not be used.     

A survey of local anaesthesia education in European dental schools

Objective: A survey of European dental schools was conducted in 2006 to determine the curricular structure, techniques and materials used in local anaesthesia teaching to dental students. Materials and methods: A questionnaire was designed to collect information about local anaesthesia education. The questionnaires were sent to the Dean of each dental school in Europe and Israel; 49 returned the completed survey, resulting in a response rate of 18.4%. Results: Results from this survey show that dental schools are managing local anaesthesia education in different ways. At most schools, theoretical teaching begins during the first half of the third year (41%), half a year before the practical instruction (43%). In 37% of the dental schools, students use non‐human objects to practice before they inject an anaesthetic in humans. The first injection in humans, usually a fellow student (61%), is mostly supervised by an oral and maxillofacial surgeon (65%). The number of injections under supervision usually depends on the individual capabilities of the student (41%). Ten per cent of the schools need permission of a medical ethics committee for the practical instruction on fellow students. All dental curricula include teaching of mandibular block anaesthesia. The majority also include instruction of infiltration anaesthesia of the upper (98%) and lower (92%) jaws in addition to infra‐orbital block anaesthesia (57%). Although 82% of the schools are satisfied with the current curriculum with regard to local anaesthesia, 43% are planning changes, frequently the introduction of preclinical training models. Conclusion: Local anaesthesia teaching programmes show considerable variation across the surveyed European dental schools.     

Assessment of occlusion after placement of stainless steel crowns in children – a pilot study

Many stainless steel crowns (SSCs) disrupt the occlusion in children, but stabilisation appears to occur within a short period post‐placement. The extent and mechanism of these short‐term occlusal changes in children are unknown. This study sought to determine whether placement of a SSC changes the maximum intercuspation position (MIP) in children, whether the MIP returns to normal within 4 weeks and whether local anaesthesia had an effect on the child's ability to achieve MIP. The T‐Scan^® III was used for the measurement of occlusal contacts. Reliability and reproducibility of the system was determined using a calibration exercise where MIP recordings were taken of eleven children not undergoing any dental treatment. For the main study, the percentage of total occlusal force on each tooth was recorded in 20 children preoperatively, after local anaesthesia, after SSC placement and 4 weeks postoperatively. There was no significant difference in MIP (P = 0·435) preoperatively and post‐administration of local anaesthesia. There was a significant difference between the preoperative force on a tooth and the reading after crown placement (P = 0·0013, Wilcoxon test). By 4 weeks, there was no significant difference overall between post‐SSC placement and the preoperative value for the tooth (P = 0·3). Administration of local anaesthesia did not affect the ability of a child to attain MIP. Maximum intercuspation position was disturbed by the placement of a SSC in seven of 20 cases. When MIP was disturbed, in most cases, it returned to preoperative status within 4 weeks of crown placement.     

European dental students’ opinions on their local anaesthesia education

Objective: To investigate students’ opinion about theoretical and clinical training in local anaesthesia at different European dental schools. Materials and Methods: A questionnaire was designed to collect information about local anaesthesia teaching. Students’ opinion was quantified with five‐point Likert scales. The web‐based questionnaire was distributed through European Dental Students Association contacts amongst students of 25 different dental schools. Eight hundred and eighteen completed questionnaires from students of 12 dental schools were analyzed statistically. Results: Dental schools showed a wide variation in the beginning of the theoretical teaching of local anaesthesia and the practical teaching. A preclinical training model was used by a small number of students, but these students found it a useful preparation. Many students felt insufficiently prepared when they administered their first injection in a human (17–81%). In dental schools from the UK, Ireland, Sweden and the Netherlands, this first injection is administered to a fellow dental student, whilst in the other countries the first injection is usually performed in a patient. Instruction in mandibular block anaesthesia was frequently reported (81–100%) as well as in infiltration anaesthesia of the upper and lower jaws (78–100% and 30–93% respectively). Many students expressed that they like to receive teaching in intraligamentary anaesthesia (13–70%). Other changes in the curriculum were also frequently suggested (33–100%), especially the introduction of preclinical training models and practical teaching earlier in the curriculum. Conclusion: Local anaesthesia teaching programmes and the rating of this teaching by dental students show a considerable variation across European dental schools. Students considered better preparation highly desirable. The variability in programmes may have implications for mobility of students between European dental schools.     

Applied anatomy of the pterygomandibular space: improving the success of inferior alveolar nerve blocks

A thorough knowledge of the anatomy of the pterygomandibular space is essential for the successful administration of the inferior alveolar nerve block. In addition to the inferior alveolar and lingual nerves, other structures in this space are of particular significance for local anaesthesia, including the inferior alveolar vessels, the sphenomandibular ligament and the interpterygoid fascia. These structures can all potentially have an impact on the effectiveness of local anaesthesia in this area. Greater understanding of the nature and extent of variation in intraoral landmarks and underlying structures should lead to improved success rates, and provide safer and more effective anaesthesia. The direct technique for the inferior alveolar nerve block is used frequently by most clinicians in Australia and this review evaluates its anatomical rationale and provides possible explanations for anaesthetic failures.     

Evaluation of bevelled needle tip deformation with Dental Inferior Alveolar Nerve blocks

The study aimed to investigate whether any correlation existed between bevel orientation and needle tip deformation following the administration of a standard inferior alveolar nerve block (IANB) technique during patient treatment. Ninety‐three needles of a single brand were collected from a group of eleven similarly trained Australian dentists’ following either single or dual insertion and bone contact. Specimens were examined under scanning electron microscopy at 500x, and both the direction of deformation (either towards or away from lumen) and the extent of deformation were calculated using image processing software. Results showed no correlation between bevel orientation and either the direction (P = 0.8787) or degree (P = 0.0752) of deformation. Significance was demonstrated, regardless of bevel orientation, following multiple needle use with respect to extent of needle tip deformation (P < 0.0001). A clinical recommendation can be made that the dental needle should be routinely replaced when subsequent injections are required during the delivery of a typical IANB.     

The effect of adjusting the pH of local anaesthetics in dentistry: a systematic review and meta‐analysis

The acidic nature of commercial local anaesthetics (LAs) can cause pain during infiltration and delay the onset of anaesthesia. It is suggested that adjusting the pH of anaesthetic agents could minimize these effects. This systematic review aimed to evaluate the efficacy of buffered LAs in reducing infiltration pain and onset time during dental procedures. MEDLINE, Embase, Scopus and Scielo databases were searched up to April 2017. Randomized controlled trials comparing buffered and unbuffered LAs for intraoral injections were included. Risk of bias was assessed using the Cochrane Collaboration tool. Data upon injection pain and onset time were pooled in a random‐effects model. Subgroup analyses compared normal and inflamed tissues, and terminal infiltrations and inferior alveolar nerve (IAN) blocks. Meta‐regressions were performed to explain heterogeneity. Fourteen articles were included in this review. Lidocaine with epinephrine was the most used anaesthetic combination. Nonlidocaine studies (n = 2) were not pooled in the meta‐analysis. Buffered lidocaine did not result in less pain during intraoral injections: mean difference ?6.4 (95% CI ?12.81 to 0.01) units in a 0–100 scale. Alkalinized lidocaine did not reduce the onset time in normal tissues when terminal infiltration techniques were used, but resulted in a more rapid onset for IAN blocks (?1.26 min) and in inflamed tissues (?1.37 min); however, this change may not be clinically relevant, considering the time required to prepare the buffered agent. Studies performed using other anaesthetic salts did not show robust and clinically significant results in favour of alkalinization.     

Effects of mandibular nerve block on heat- or cold-induced changes in pulpal blood flow in man

Abstract – Laser Doppler flowmetry (LDF) was used to study the effect of mandibular nerve block, using 3% mepivacain, on heat-or cold-induced changes in pulpal blood flow (PBF) evoked by application of cold or heat to the lingual surfaces of teeth 33 and 43 in nine young subjects. PBF on average showed a 7% increase in response to heat (48°C) and a 20% decrease when exposed to cold (3°C). Neither response was affected by mandibular block. From this we concluded that the effects on PBF of the presently applied heating and cooling of the tooth were solely due to direct thermal influences on the blood vessels, without involvement of vasomotor or sensory nerves.