Introduction

Archer in 1975 defined an impacted tooth as a tooth that is completely or partially unerupted and is positioned against another tooth, bone or soft tissue so that its further eruption is unlikely (Santosh, 2015). Literature from around the world states mandibular third molars to be the most commonly impacted tooth (Alsadat-Hashemipour, Tahmasbi-Arashlow, & Fahimi-Hanzaei, 2013; Gisakis, Palamidakis, Farmakis, Kamberos, & Kamberos, 2011; Kruger, Thomson, & Konthasinghe, 2001). This can be due to discrepancy in jaw and tooth size which can be attributed in part to evolution, aberrant position of third molar in the arch due to dense external oblique ridge or due to retarded maturation of third molar because of lag in dental development when compared to skeletal development (Carter & Worthington, 2016; Kumar, Yadav, Kahsu, Girkar, & Chakraborty, 2017; Msagati, Simon, & Owibingire, 2013; Padhye, Dabir, Girotra, & Pandhi, 2013).

These impacted teeth also give rise to various pathologies of odontogenic origin making (Celikoglu, Miloglu, & Kazanci, 2010; James, Srinivas, & Muthusekhar, 2018; Jesudasan, Wahab, & Sekhar, 2015; Nagappan, Gopinath, Elango, Pillai, & Mani, 2016) the prophylactic removal of third molars more common in recent times (Muralidharan, Kritivasan, & nazar, 2019; Ravikumar & Narayanan, 2018; Shoshani-Dror, Shilo, Ginini, Emodi, & Rachmiel, 1985). Surgical removal of mandibular third molar is a routine and the most common minor oral surgical procedure done in the outpatient department under local anesthesia (Rashid et al., 2018). The prime factor that provides for the best surgical outcome and patient satisfaction/experience is a pain-free procedure (Danda, Wahab, Narayanan, & Siddareddi, 2010; Jerjes et al., 2009; Sekhar, Narayanan, & Baig, 2001). No amount of emphasis made can fully substantiate the importance of a pain-free procedure that is done on a conscious patient (Pacey, 2014; Shanmugaavel, Asokan, John, Priya, & Raaja, 2016). Hence, achieving adequate anesthesia of the surgical site is the first and the most important step in the surgical removal of third molars (James & Maheshwari, 2017; James & Nazar, 2018; Kumar, 2017). Various nerve block techniques have been proposed over the years for the same, popularly, the conventional inferior alveolar nerve block technique, Vazirani Akinosi technique, Gow-Gates mandibular nerve block technique (Malamed, 2020).

Though the nerve block technique used to anesthetize the surgical site is an independent decision of the surgeon, the most commonly used technique is the Conventional Inferior Alveolar Nerve Block (IANB) technique. This can be due to the fact that this is where the surgical training of an oral and maxillofacial surgeon begins and is a foundation upon which the surgeon builds his skills (Christopher, Marimuthu, Krithika, Devadoss, & Kumar, 2018; Okamoto, Takasugi, Moriya, & Furuya, 2000; Thangavelu, Kannan, & Kumar, 2012).

As much as the anesthesia technique, the amount of anesthetic solution and the type of anesthetic solution used are also of clinical importance. The composition of anesthetic solutions has evolved drastically since the introduction of novocaine (Bahl, 2004; Deepa & Thirrunavukkarasu, 2010; Kumar, 2015; Ogle & Mahjoubi, 2012). Nowadays, longer acting and more potent local anesthetic solutions with potentially lesser complications have been introduced (Hariharan, Narayanan, & Soh, 2014; Jain & Nazar, 2018; Ramadurai, Gurunathan, Samuel, Subramanian, & Rodrigues, 2019; Srisakthi, 2014). Nonetheless, the gold standard still continues to 2% lignocaine. Adrenaline in concentrations 1:80,000, 1:1,00,000 or 1:2,00,000 is used along with lignocaine for its vasoconstrictor property. This provides more visibility, increases the concentration of the drug and reduces systemic absorption of lignocaine (Malamed, 2020; Okamoto et al., 2000). With respect to the amount of local anesthetic solution used, the maximum recommended dose (MRD) of 2% lignocaine with adrenaline is 7mg/kg up to 500mg. The MRD of plain 2% lignocaine is 4.4mg/kg up to 300mg. Hence, the amount of local anesthesia used in mandibular third molar surgery is crucial and while aiming to provide a pain-free comfortable experience, the overzealous use should be cautioned against (Becker & Reed, 2012; Defosse, 1999; Ogle & Mahjoubi, 2011).

In this study, we aim to retrospectively assess the amount of local anesthesia being used in surgical removal of impacted mandibular third molar.

METHODOLOGY

The retrospective observational study was conducted among the patients reporting to the Department of Oral and Maxillofacial surgery at Saveetha Dental College and hospital, Chennai during the time period June 2019 to March 2020.

The approval for the study was given by the “Institutional Ethical committee, SIMATS Review Board”.

The inclusion criteria for the study were patients of any age and gender undergoing surgical extraction of impacted mandibular third molar under local anesthesia.

The exclusion criteria for the study were patients undergoing closed extraction of mandibular third molar either in local or general anesthesia and open extraction of mandibular third associated with any pathologies, patients with a history of debilitating systemic diseases and mentally or physically challenged patients.

Diagnostic Criteria

The diagnosis of impacted mandibular third molar was made with clinical findings and radiographic interpretations using intra-oral periapical radiograph (IOPA) and orthopantomogram (OPG). Based on their interpretations, the difficulty of extraction was predicted using Pederson's Difficulty Index (PDI) as minimally difficult, moderately difficult and very difficult.

Data Collection

The patient demographic details and data pertaining to study parameters were retrieved from “DIAS- Dental Information Archive System” provided by the institution.

A total of 782 patients had reported to the department of oral and maxillofacial surgery at Saveetha Dental College, Chennai for surgical extraction of mandibular third molar under local anesthesia between the study duration (June 2019 to March 2020). Of the 782 patients, only 658 fulfilled the inclusion criteria and exclusion criteria and were included in the study. The sample size of the population studied is 658.

Study Parameters

From DIAS, the following data were extracted for the purpose of the study:

• Demographic details (age, gender)

• Nomenclature of the impacted tooth to be surgically removed (38 or 48)

• Pederson's Difficulty Index (PDI) for the tooth.

• Amount of local anesthetic used during the procedure in millilitre (ml)

Surgical Procedure

All the surgical removal of impacted teeth were carried out by residents (postgraduate students) of oral and maxillofacial surgery in their final year of training. For standardization, only cases which used 2% lignocaine with 1:2,00,000 adrenaline and employed conventional inferior alveolar nerve blocking (IANB) technique were included in the study. And in all the cases either wards or modified wards incision was used to gain access to the surgical site. Closure was done using 3-0 silk suture.

Statistical Analysis

The data obtained was subsequently tabulated in an excel spreadsheet and was exported to IBM SPSS version 20.0 for statistical analysis. The data was analysed descriptively measuring mean, standard deviation, percentage and frequency. The association between different study parameters were analysed using Pearson Chi-square test at 95% confidence interval. The output was generated as tabular or graphical representation.

Results and Discussion

Analysis of the demographic data of the study population revealed that a majority of them were in their 3^rd decade of life (53.6%) with mean age 29.1 years when they underwent surgical removal of lower third molar (Figure 1). Gender distribution did not show much significance with 58.4% being males and 41.6% being females (Figure 2).

The study population underwent surgical removal of 38 (54.1%) more than 48 (45.9%), though not statistically significant (Figure 3). Of the 658 impacted teeth included in the study, 54.4% were moderately difficult, 38.4% were minimally difficult and 7.1% were very difficult as per Pederson's Difficulty Index (PDI) (Figure 4). Distribution of the amount of local anesthesia used during the procedure revealed that 2ml was sufficient to achieve adequate anesthetic effect in 64.7% cases. This was followed by 4ml (17.2%), 3ml (14.6%), 5ml (1.8%), 6ml (1.4%), 8ml and 10ml (0.2%) (Figure 5). Association between PDI of impacted mandibular molar and amount of local anesthesia used was statistically significant with p < 0.01 at confidence interval 95% (Figure 6) (Table 1).

Al-Dajani et al. in 2017 studied the patterns of mandibular third molar impaction in Saudi population and concluded that it was more prevalent in the second and third decade of life with a mean age of 33.5 years (Al-Dajani et al., 2017). A similar study conducted by Mitra et al. in 2016 in Indian population of Ranchi revealed mandibular third molar impaction to be more common in males of age group 21-25 years (Mitra, 2016).

The demographic data of our study population revealed similar results where the majority of patients who underwent mandibular third molar impaction surgery were in their 3^rd decade of life (53.6%) with a mean age of 29.1 years. The distribution of gender did not reveal any significant difference ( male – 58.4%, female – 41.6%) though it refuted the recent results from (Al-Dajani et al., 2017; Dubey et al., 2019; Enabulele & Obuekwe, 2017; Ravikumar et al., 2018). This can be due to our stringent inclusion and exclusion criteria (Al-Dajani et al., 2017; Dubey et al., 2019; Enabulele & Obuekwe, 2017; Ravikumar et al., 2018).

Mahdey et al. in 2015 retrospectively analysed the Pederson’s Difficulty Index (PDI) of impacted mandibular third molar in Malaysian population using 1249 orthopantomograms (OPGs). They concluded that the majority of impacted mandibular third molars were “very difficult” as per PDI (Mahdey, 2015). In our study however, we found that “moderately difficult” mandibular third molars were more subject to surgical removal (54.4%).

An innovative evaluation in our study was that of the amount of local anesthetic solution used during the duration of surgical removal of mandibular third molar. We observed that in 64.7% cases only 2ml local anesthetic solution was used. The largest amount of local anesthetic solution used in this study was 10ml in 0.2% of cases corresponding to the “very difficult” category of PDI. Malamed in his “Handbook of local anesthesia” recommends the amount of local anesthesia solution (with adrenaline) required to anesthetize each nerve. For inferior alveolar nerve blocks following the conventional technique he recommends the following: Inferior alveolar nerve-1.5ml, lingual nerve-0.2ml, long buccal nerve-0.3ml. Hence, 2 ml of local anesthetic solution containing adrenaline is sufficient to provide adequate anesthesia in conventional IANB technique (Malamed, 2020). Our finding is consistent with Malamed’s statement. Association between PDI of impacted mandibular third molar and amount of local anesthesia used was statistically significant with p < 0.01 at confidence interval 95%.

In Figure 1, X-axis represents age in decade and Y-axis represents the percentage; patients with impacted mandibular third molars underwent open extraction of the impacted tooth more commonly in the third decade of life (55.78%). In Figure 4, the most commonly impacted mandibular third molars were moderately difficult (54.41%) as per the PDI. In Figure 5, X-axis represents the amount of LA used during the procedure (in ml) and Y-axis represents the percentage; 2ml (64.74%) of LA solution was used the maximum while 8ml (0.15%) and 10ml (0.15%) were used the minimum. In Figure 6, X-axis represents the PDI of impacted mandibular third molar and Y-axis represents the amount of LA used in percentage and count; Chi-square test: p< 0.01 shows significant association i.e. as the PDI score increased, the amount of LA used also increased.

Limitations

In this retrospective observational study, the popularly used classification of mandibular third molar impaction viz. Winters, Pell and Gregory classification were not considered individually even though Pederson's Difficulty Index is based on these classifications. Also, this retrospective analysis is restricted to a single study niche reporting to a dental college within a narrow study duration.

Conclusion

Within the limits of our study, we found that 2ml of 2% lignocaine with adrenaline (1:1,00,000 or 1:2,00,000) is sufficient in achieving adequate anesthesia during surgical removal of the third molar in most cases and the amount of local anesthetic solution used may increase with increased PDI score.

Conflict of Interest

The authors declare that there is no conflict of interest for this study.

Funding Support

The authors declare that they have no funding support for this study.