Dental local anesthesia in Family Health Units : use , pain and associated factors

BACKGROUND AND OBJECTIVES: In spite of the relevance of controlling pain during dental procedures and of the fundamental role of Family Health Units in the Brazilian health system, there are few studies integrating both subjects. So, this study aimed at analyzing some aspects of dental anesthesia in Family Health Units of the city of Caruaru-PE. METHODS: We have interviewed 372 adolescent and adult patients from 12 units, in the waiting room or close to it, after dental treatment, using a form with 14 questions. Pain was investigated with a numerical scale of 21 points (0 to 10 with 0.5 intervals). RESULTS: Anesthesia was used in 16.1% of procedures. There has been pain during most anesthesias (58.3%), with intensity of 1±1.2, being more frequent when procedures were in the anterior oral region. For non-surgical invasive procedures, anesthesia was more used in adolescents, in procedures in the posterior oral region, when there was previous pain in the treated region and when the dentist asked patients about their preference. Also for these procedures, pain during treatment as a whole was more frequent and more severe when anesthesia was used. CONCLUSION: Dental anesthesia is rarely used in these units and pain during anesthesia is frequent, however of low intensity. During non-surgical invasive procedures, its use is associated to some characteristics of patients and treatments, but not to a painless or less painful treatment.


INTRODUCTION
Pain in dentistry may be associated to a disease affecting the oral cavity and, in these cases, clinical procedures are decisive for its eradication.It may also be associated to the dental procedure itself, very often needing local anesthetic solution administration to control such sensation.However, studies have shown that some patients are afraid of anesthesia 1 and others consider it more painful than the treatment itself 2 , in addition to the fact that anesthetic injection may fail in promoting adequate anesthesia for the dental procedure 3 .Other aspects of dental local anesthesia include the effect of ORIGINAL ARTICLE DOI 10.5935/1806-0013.20150051anesthetic injection pressure on anesthetic pain 4 , the evaluation and comparison among techniques 5,6 , the efficacy of anesthetic agents 7,8 etc. Frequency and factors influencing professionals to use or not anesthesia for nonsurgical invasive procedures, such as restorations, are absolutely scarce 9 , as well as there are no literature studies evaluating anesthetic pain in basic attention services of the Brazilian health system, such as Family Health Units (USF).These health units in general assist destitute communities which, consequently, have no good oral health conditions and so have further need for clinical treatments and interventions.So, the need to control pain is frequent in dental assistance to such communities, which increases the importance of studies addressing pain and anesthesia in such health services.In light of the above, this study aimed at identifying and evaluating some aspects regarding dental local anesthesia in USF of the city of Caruaru-PE.

METHODS
This is an epidemiologic, observational, cross-sectional and analytical study carried out in the urban zone of the city of Caruaru, Pernambuco, from May to September 2013, according to the ethical principles of the Declaration of Helsinki.Sample was made up of 372 adolescent and adult patients (12 to 59 years of age), assisted in 12 USF (from 20 of the urban zone of the city with oral health teams), in a total of 31 patients per unit.Sample was by conglomerate (double stage), where USF were the groups.So, USF were selected by simple and randomized sampling, and from those, patients were selected.Sample size was defined by the program Power Analysis and Sample Size (version 2005).Data were collected in the waiting room of the USF or close to it, according patients' preference, after dental assistance, by means of a standardized interview with a form with 14 questions.Anesthetic pain and pain during treatment as a whole were investigated using numeric evaluation scales with 21 points (from zero to 10 with 0.5 intervals) 10 and anxiety was defined by Corah's the Dental Anxiety Scale (DAS) 11 .DAS checks the level of anxiety with the dental treatment by means of 4 questions, each one with five alternative answers which score from 1 to 5 and classify the level of anxiety in null (up to 4 points), low (5 to 9 points), moderate (10 to 14 points) and exacerbated (15 to 20 points).

Statistical analysis
Data were analyzed by the statistical package SPSS (version 20).Chi-square, likelihood ratio and Fisher Exact tests were used for categorical variables and Mann-Whitney test was used for quantitative variables.For all tests, significance level was 5%.This study was approved by the Ethics Committee of the Associação Caruaruense de Ensino Superior -Faculdade ASCES (CAAE 15037513.8.0000.5203)and a pilot study has tested and adjusted methods and logistics.

RESULTS
From 372 treated patients, anesthesia was used in just 60 (16.1%).For nonsurgical invasive procedures (248) there have been cases with anesthesia (11.3%) and without anesthesia (88.7%), as shown in table 1. Table 2 shows that the use or not of anesthesia for nonsurgical invasive procedures was associated to some patients and treatment characteristics, so that anesthesia was significantly more used (p<0.05) in adolescent patients, for posterior oral region procedures, when there was previous pain in the treated region and when the dentist would ask patients about their preference with regard to anesthesia.There has been pain in most anesthesias (in 35 out of 60 cases, or 58.3%), with mean intensity of 1±1.2 and maximum of 5, in a scale of 0 to 10.With the help of table 3 it was possible to observe that the presence of pain was associated (p<0.05)just to the treated oral region, among all evaluated variables, being pain induced by anesthesia more frequent when the anterior region was treated.It is important to highlight that the use of topical anesthesia was not associated to lack of anesthetic pain; in fact, this pain was more frequent when topical anesthetics were used, although without significant difference (p=0.102).Table 4 shows that patients have felt pain during treatment as a whole in 71.4% of cases with anesthesia when procedure was nonsurgical and invasive, and in 59.4% of surgical procedures, without significant difference.It also shows that pain during nonsurgical invasive procedures was significantly less frequent in cases without anesthesia (44.5%) as compared to those with anesthesia.Pain intensity during treatment as a whole in anesthetized cases has varied from zero to 10, with mean of 1.6±1.9 and was not significantly different between surgical and nonsurgical invasive procedures (p=0.227 by Mann-Whitney test).However, mean pain intensity during nonsurgical invasive procedures was significantly higher in cases with anesthesia (2.1±2.5) as compared to those without anesthesia (1.1±1.8)(p=0.004 by Mann-Whitney test).

DISCUSSION
As compared to available literature data, the frequency of local anesthetics use in the studied population was low, both general frequency and that specific for nonsurgical invasive procedures.In a Finland 12 study, for example, in the age group with the lowest frequency of use, anesthesia was used in 38% of restorative procedures.Local anesthesia for dental care varies among cultures.Americans use more anesthesia than Nordics and those more than Chinese 13 .Features of dental service institutions may also influence the frequency of local anesthetics use, not simply for being public or private, but also because there are several aspects of their operations.A study has found that anesthesia for restorative procedures was more frequent in the public service as compared to private service 9 , but in this public service adult patients do not have totally free assistance.It might be that the low frequency found in our study is influenced by the fact that dentists have quotas of patients to be treated, so that they are available for other jobs the sooner they meet such quota.
It is probable that they avoid wasting time with anesthesia for nonsurgical invasive procedures.Obviously, this speculation deserves further studies.It does not seem adequate to think that the low prevalence of anesthesia during nonsurgical invasive procedures was due to patients' preference, since in the vast majority of cases dentists have not asked patients about their preference.In addition, it was observed that exactly when dentists asked that question, the use of anesthesia was more frequent.In addition to checking patients' preference, other variables were associated to the use or not of anesthesia for nonsurgical invasive procedures, such as age, treated oral region and the presence or not of previous pain in treated region.These results are similar to other study 12 which points to more frequent use of anesthesia in adolescents and posterior oral region, however without difference with regard to patients' gender.
As to the presence or not of previous pain in the treated region, it was to be expected a more frequent use of anesthesia in cases of pain.In these cases, it is well possible that there is a peripheral sensitization by an inflammatory process, with increased responsiveness to stimuli and decreased activation threshold 14 .So, if dentists start a nonsurgical invasive procedure without anesthesia it is to be assumed that soon after they decide to use it due to patient's pain report.
The high frequency of anesthesia-induced pain found in our study reinforces literature data with regard to the painful potential of such procedure.Its use has already been identified as one of the strongest predictors of pain during dental treatment 15 and was mentioned by 30% of patients as reason of pain during tooth extractions 10 .In spite of this high frequency, anesthesia-related pain was mild, similarly to other studies 16,17 .However, the adequate posture would not be to expect patients to stand the pain just because it is mild.Dentists and dentistry should always work to offer a painless treatment.These efforts have to include investigation on technique-related variables which might influence anesthetic pain, since there is a clear lack of such information in the literature.In this sense, our study contribution was to show that anterior oral region is more susceptible to this pain, which was also found by a previous study 5 .Anxiety with anesthesia might influence perceived pain during such procedure 17 , although anxiety with dental treatment and fear of anesthesia were not significant in our study.Patients' gender really does not seem to determine anesthetic pain 18 .
With regard to anesthetic technique-related variables, our study confirms previous studies about the ineffectiveness of topical anesthetics to eliminate anesthetic pain.They might even decrease needle insertion pain intensity, but not eliminate it, and for pain at anesthetic injection they are even less effective, especially if dentists do not wait long enough for the anesthetic to act 18 .As already discussed, working circumstances of studied institutions do not seem to favor the waiting for this effect.Anesthesia has also not provided a painless treatment for most anesthetized patients.In fact, full effectiveness is in general not reported and this is why new anesthetic drugs and techniques continue to be tested 8,19 .However, the situation was more severe in cases of nonsurgical procedures, given the presence of pain during the procedure as a whole and the fact that it was more severe when anesthesia was used.It really seems that anesthetic pain is worse than pain of the procedure itself 2 .This might be dentists' understanding, due to their clinical experience, and the reason why they seldom use anesthesia for such procedures.This same fear of anesthetic pain may also lead dentists to use anesthesia only when patients refer pain during the procedure.This puts an end to any possibility of a totally painless treatment.

CONCLUSION
Local dental anesthesia is seldom used in USFs of Caruaru, anesthetic pain is frequent, especially in the anterior oral region, however its intensity is low.
In nonsurgical invasive procedures its use is associated to some patients and treatment characteristics, but not to a painless or less painful dental treatment.So, dentists and managers of evaluated institutions have to review dental anesthesia practices to favor painless treatments.

Table 1 .
Frequency of dental anesthesia according to the type of procedure *clinical evaluation, polishing, sealant, varnish or fluoride application, drug prescription; ** crown opening, filling/restoration, tartar removal, stitches removal; ***tooth extraction, surgeries and suture.

Table 3 .
Frequency of dental anesthesia pain, according to patients and treatment characteristics p 1 = Pearson Chi-square; p 2 = Likelihood Ratio, p 3 = Fischer Exact.*According to Corah Dental Anxiety Scale.** 1 patient did not know whether topical anesthetic was used.

Table 2 .
Frequency of use of dental anesthesia for nonsurgical invasive procedures, according to patients and treatment characteristics p 1 = Pearson Chi-square; p 2 = Likelihood Ratio, p 3 = Fischer Exact.*According to Corah Dental Anxiety Scale.

Table 4 .
Pain during treatment as a whole, according to the use or not of anesthesia and according to type of invasive procedure Pearson Chi-square test; § = comparing nonsurgical without anesthesia versus with anesthesia. *