Wisdom Tooth Surgery Complications—Local Anaesthesia versus General Anaesthesia

Purpose: To compare the complication rates arising from surgical removal of lower third molars (L3M) under general anaesthesia (GA) versus local anaesthesia (LA) in the Oral and Maxillofacial Surgery (OMFS) Department, Hospital Sultanah Nora Ismail (HSNI), Batu Pahat, Johor, Malaysia. Materials and methods: This is a retrospective clinical audit of patients who underwent L3M removal under LA or GA from 1/1/2013 to 31/3/2018, with recorded complications such as surgical site infection (SSI), wound breakdown, severe pain, trismus, retained tooth structure, nerve injury and dry socket evaluated at different time intervals. Results: A total of 313 patients with 375 L3M were included in this study (male: 160, 51.1%; female: 153, 48.9%) with an age range of 18 to 40 years (mean = 27.43 years). 79 L3M were removed under GA (34.2% were classified as mild; 65.8% were moderate), whereas 296 L3M were removed under LA, (31.4% were mild impaction, 63.9% moderate and 4.7% severe. Preoperative antibiotics were given before all L3M removal under GA, while only 23 out of 296 L3M removal under LA had antibiotics. 15.2% of L3M removal under GA and 16.6% of those done under LA were associated with complications. Generally, patient with GA had lesser complications; however only SSI outcome was significant (p = 0.034). Conclusion: L3M removal under LA may have a higher risk of SSI when compared to GA. This raises the possibility that a single prophylactic antibiotic dose may prevent SSI in LA procedures.

mon procedure carried out in oral surgery units. Lower third molar (L3M) can be carried out under local anaesthesia (LA) or general anaesthesia (GA). It is not uncommon to have multiple L3M removed under GA in centres with general anaesthesia facilities. Bouloux et al. (2007) [1] reported that the incidence for surgical site infection (SSI) in 3M removal was 1% -4%. It is uncommon to have nerve injury after L3M removal, but if it happens, it will be one of the most undesirable complications and can be distressing to certain patients [2].
As for alveolar osteitis, the incidence shown in published studies ranges form 0.3% -26% [3] [7] [8] [9] [10]. Mandibular fracture and osteomyelitis were considered as rare complications during L3M removal [11]. The reported incidence for mandibular fracture was 0.0049% [12]. These published complication rates are vital in monitoring the surgical risks in patients and there is a growing need to regularly audit such procedures.

The Oral and Maxillofacial Surgery (OMFS) department in Hospital Sultanah
Nora Ismail Batu Pahat (HSNI) has been carrying out minor oral surgery (MOS) procedures for many years since its setting up in 2012. While the complications (SSI and nerve injuries) are monitored, we have not been able to compare the complication rates for these procedures when conducted under LA and GA.
The aim of the current study is to assess the rate of complication of L3M removal under GA and LA in this centre.

Methods
This is a retrospective study of L3M removal under LA or GA performed at the Department of OMFS, HSNI. L3M were removed by specialists or senior dental officers. The patients' details were collected from the operating theatre list, surgical notes and clinical records. A variety of data were collected for each patient including age, sex, medical status at the time of procedure and the type of procedure performed. Open Journal of Stomatology 4) Acute abscess patients whose removal was done as an "emergency" procedure.

5)
Removal of residual L3M cases such as residual tooth structure that had prior attempted removal. Procedure: All L3M removal under LA or GA and meeting the criteria of this study were identified: 1) All clinical notes and patient records (radiographs) were retrieved and assessed.
2) Pre operative and post operative assessment data was collected and collated.
3) Follow-up intervals were recorded and analyzed accordingly. tures. Post op instruction and medication was given (analgesic and mouthwash).
Tablet prednisolone 10 mg was prescribed post operatively for 3 days. Meanwhile, MOS of L3M under GA involves the same procedure and surgical technique as LA, post op instruction and medication were given (analgesic and mouthwash) prior to discharge. For GA procedure, patient was admitted one day prior. On the day of surgery, patient was orally intubated, sedated and scrubbed. IV Dexamethasone 8 mg and antibiotics were served as pre-operative medication for GA procedure given by anaesthesist after intubation [14].
Data to be collected 1) Patients' demographic details.
3) Surgery details-surgical approach, date of MOS, date of discharge, intra operative complication, post operative complications.  Depth of impaction (with respect to occlusal plane): Occlusal plane of impacted tooth at same level as occlusal plane of second molar 1 Occlusal plane of impacted tooth between occlusal plane and cervical line of second molar 2 Impacted tooth below cervical line of second molar 3 Available space (with respect to ascending mandibular ramus): Sufficient space between ramus and distal part of second molar to accommodate mesiodistal diameter of third molar 1 Space between second molar and ramus of mandible is less than mesiodistal diameter of third molar 2 All or most of third molar is in ramus of mandible 3 Score: 3 -4 = mild; 5 -7 = moderate; 8 -10 = severe. g) Retained root. data was expressed as mean and standard deviation (SD), while categorical data was described in the form of frequency and its percentage. Differences and association in the patient's demographic profiles, clinical characteristics, and the complication following wisdom tooth surgery between groups of general anaesthesia (GA) and local anaesthesia (LA) were assessed using independent t-test for continuous variables; and Pearson chi-square or Fisher's exact test for categorical variables. Odds ratios (OR) and 95% confidence intervals (CI) were calculated using logistic regression, to determine the association between the type of anaesthesia with each type of complication. All p-values reported were two sided, and a p-value of less than 0.05 was considered significant.      Adj. OR = Adjusted odds ratio; CI = Confidence interval. Complication "Yes" is coded as the event of interest; percentages is reported by row (by each procedure). The other type of complication is not available since there is "0" or very small cell observation. *Adjusted for age, gender, ethnic, tooth, type of impaction, close proximity to ID canal, antibiotic taken and intra-operative complication.

Discussion
MOS of L3M is a common procedure and complications that arise should be managed accordingly. We aimed to assess the rate of complication post MOS SSI in L3M procedure can be characterised by swelling or fluctuation and purulent discharge from the socket with associated pain [16]. The risk factors identified as being associated with this complication are longer surgical procedure, severity of impaction, age of patient above 25 years old, sterility of working environment and preoperative antibiotic used in GA procedure. Bouloux et al.
(2007) [1] reported that the incidence for SSI in 3M removal is 1% -4%. This correlates with our study finding (3.7% for LA and 6.3% for GA). Clauser et al. higher risk to develop SSI. SSI was recognized as a significant contributor to expense, morbidity and mortality within the health care system. Hence, identifying the variables that affect the incidence of SSI was a crucial step to help reduce the incidence and expense of SSI [18].
When comparing LA and GA environment, performing procedure under GA environment was more sterile as a positive pressure gradient and air filters between the theatre environment and its surroundings can reduce airborne pathogens and contamination. Conventional (turbulent) ventilation changes the air 20 times per hour. Temperature was maintained between 18˚C -25˚C while humidity was maintained at 40% -60% [19]. Hence GA procedures can reduce the risk of SSI. In almost all the SSI cases, the treatment of choice involves systemic antibiotics, generally Amoxicillin/Augmentin and antimicrobial mouthwash (0.2% Chlorhexidine mouthwash) in our setting.
In our study, all L3M removal under GA was given preoperative antibiotic.
Prophylactic antibiotics were proven to reduce the evidence of SSI [20] [21] [22].  [25]. This may also be a contributing factor to the reduced incidence of SSI in our series. This also raises the possibility that prophylactic antibiotics (single dose) may prevent SSI.

Nerve Involvement
There was no recorded permanent paraesthesia 6 months after the MOS in our setting. Queral-Godoy et al. (2005)  pine, venlafaxine for chronic pain, and topical 5% lidocaine patches or combination of these was introduced but only provided partial relief of the symptoms.
Cases of neuropathic pain can be treated as described by Renton and Yilmaz (2012) [29] which include cognitive behavior therapy, surgery, medication (Pregabalin, oxcarbazepine, venlafaxine for chronic pain), and topical 5% lidocaine patches or combination of these. For cases that were close to nerve, coronectomy was carried out, and this may be the reason that no significant difference on nerve injury was noted between LA and GA [30].

Pain
It is common to have pain for the first few days after the procedure secondary to inflammation on the surgical site. If the pain worsens, we need to rule out underlying complication such as alveolar osteitis or infection and treated accordingly. Non-steroidal anti-inflammatory drugs can be given postoperatively to patients that have no contraindication, partial opioid agonists such as tramadol as a step up drug in severe pain under LA procedure. In addition to this, tablet prednisolone 10 mg was given for three days in tapering dose for our patients. In GA procedures, a single dose of intravenous dexamethasone 8 mg was given at induction and a single dose of intramuscular tramadol was given post operatively. We found out that there was no significant difference (pain) between LA Open Journal of Stomatology and GA procedure despite different medications prescribed for the patients.

Alveolar Osteitis
The reported incidence of dry socket in our study was 5 [10]. Patients were treated with either wound irrigation with saline solution to remove food remnants, sedative dressing, mild to strong analgesic prescriptions or with combination of these, plus reassessment if the complaints persisted. There was no significant difference in incidence between LA with GA procedure in our centre.

Limitations
This study has some limitations. As the study was retrospective, the complication rate might have been underestimated. Some patients do not seek medical attention for small complications and had defaulted follow up. There was also a significant difference in antibiotic prescriptions between the two procedures.
The sample size in our study was small compared to other studies.

Conclusion
In conclusion, we compared the complications arising from removal of third molar extraction in both GA and LA procedures and note that GA procedures had less surgical site infection. This may be due to the preoperative antibiotics before surgery in the group operated under GA but only a certain number of patients operated under LA. This finding also seeks to raise the question if preoperative antibiotics in all LA procedure are justified. More preventive measurements are warranted to reduce this complication. A prospective study would be ideal to further validate this audit's finding. Patients' age act as a contributing factor for the complication and should be informed of this possibility. Ideal working environment such as sterility should be emphasized for all surgical procedures. Audit can be carried out annually to ensure sterility during procedure. Patients who are medically compromised can be offered L3M removal under GA to further reduce the complication. Variation in antibiotic prescription and the correlation with SSI needs further evaluation.