Abstract
This study aimed to determine the incidence of traumatic dental injuries (TDIs) during oral tracheal intubation by traditional laryngoscopy in general anesthesia (GA) in pediatric patients aged 4–13 and the correlated risk factors in Damascus, Syria. The study included children at the Department of General Surgery, Damascus University. Each child was examined before, during, and after 12–24 h of entering the operation room. The examination aimed to obtain demographic data and information regarding anesthesia procedures and the oral cavity. This study demonstrated that the incidence of TDIs during oral tracheal intubation was 16.00%. Most of those injuries are intra-oral, which were related to soft tissue. Maxillary incisors were the most affected teeth. Concussion and tongue injury were the common types of hard and soft tissue injury, respectively. There is a relation between TDIs and the occlusal stage, the difficulty of intubation, the number of intubation attempts, the Mallampati score, inter-incisor distance, and the distance between the mental and thyroid cartilage (p < 0.05). TDIs during oral tracheal intubation in GA are injuries with many risk factors and can’t be avoided even with skilled anesthetists. Careful Preoperative clinical examination of the oral cavity by anesthesiologists can reduce the incidence of TDIs.
Subject terms: Paediatric research, Dental trauma
Introduction
Iatrogenic injuries are damage caused by medical procedures1,2. Traumatic injuries are common iatrogenic injuries that often arise during laryngoscopy and intubation procedures3,4. Tracheal intubation with traditional laryngoscopy is a critical procedure in anesthesiology and is still obligatory in some clinical conditions5. However, inadequate airway management abilities lead to disappointing outcomes6.
Despite being a safe technique with few consequences, laryngoscopy may damage soft and hard tissue and cause postoperative pain and discomfort7. According to documented patient complaints, the most common traumatic injuries affect the larynx (33.00%), pharynx (19.00%), esophagus (18.00%), and temporomandibular joints (TMJs) (10.00%)4,8.
Although accidental damage to hard and soft tissues in the oral cavity is considered a minor complication, it can induce significant postoperative discomfort and pain9,10. Moreover, these injuries are the most common cause of litigation against anesthesiologists11–14.
Many retrospective studies have evaluated the prevalence of traumatic injuries15–17. In 2007, Newland et al.15 suggested that TDIs are among the most frequently noted negative occurrences linked with anesthesia among patients who had TDIs between August 1989 and December 2003. Contributory factors include poor dentition or preexisting dental restorations and intubation that ranges from moderately challenging to quite difficult. The incidence of TDIs was 0.05%, mainly including enamel fracture (32.10%) and subluxation (23.10%). In 2011, Martin et al.16 suggested that urgent tracheal intubation is a risk factor for traumatic injuries, with TDIs having an incidence of 0.20% among patients who required urgent non-operative intubation between December 2001 and July 2009. In 2017, the Kakei et al.17 study included patients who underwent general anesthesia (GA) between January 2008 and December 2015. The TDI incidence was 0.06%. TDIs mainly involve the maxillary left central incisor (50.00%), with avulsion (36.00%) and luxation (36.00%) being the most common type. In 2018, Tan et al.18 noted that the incidence of TDI during GA was 0.09% between January 2011 and December 2014. The main risk factors for TDIs are preexisting poor dentition, Mallampati score > 3, and reduced thyromental distance.
Prospective studies conducted by dentists demonstrate a higher number. In 1990, Chen et al.19 reported that the incidence of traumatic injuries was 18% during endotracheal anesthesia and maxillary incisors were mainly involved (12.10%). In 2011, Mourão et al.10 stated that the incidence of TDIs during GA when patients underwent orotracheal tube insertion by laryngoscope was 38.60%. The vast majority of TDIs were enamel fractures of maxillary incisors. Another study by Mourão et al.4in 2015 stated that the incidence of soft tissue trauma during tracheal intubation utilizing direct laryngoscopy was 52.10% and mainly involved tongue injury (36.30%). This wide variance in published results can be attributed to differences in methods used to detect traumatic dental injuries (TDIs)20.
Limited and scarce prospective studies evaluate soft and hard tissue injuries in the oral cavity related to endotracheal intubation by laryngoscope during general anesthesia, especially in pediatric patients1,4,21. Therefore, this study aimed to determine the incidence of TDIs during oral tracheal intubation by traditional laryngoscopy in GA in pediatric patients aged 4–13 and the correlated risk factors in Damascus, Syria.
Materials and methods
Study design and ethics
It is an observational, prospective study that explores the occurrence of TDIs during oral tracheal intubation using a traditional laryngoscopy in GA in hospitalized children at the University Children’s Hospital in Damascus in 2022. Ethical approval was obtained from the Scientific Research Committee of Damascus University (IRB No. UDDS-2599–09052022/SRC-1550). In addition, all procedures were carried out following the Helsinki Declaration, as revised in 2013. This descriptive study was presented according to the STORBE Statement guidelines. Before data collection began, all participants’ guardians gave informed consent.
Sample size calculation
The appropriate sample size was calculated using the Cochran formulation introduced in 1963: n0 = Z2.p.q/e2, commonly employed in observational studies22. The confidence level was 95.5%, z = 2, e = 10%, and p = 50%. Thus, the minimum required sample size was 100, which resulting a study power = 90%. The sample size was expanded to 150 to improve the study’s accuracy and validity.
Eligibility criteria
Children aged 4 to 13 years who require non-urgent procedures under GA at the Department of General Surgery, Damascus University, were included. Children must have at least one primary tooth and receive airway maintenance devices that contain a tracheal tube and laryngoscope with a Macintosh blade. However, children who are uncooperative or have special health care needs, children with orthodontic appliances, and whose guardians refused to participate were excluded. Furthermore, the children undergoing facial and upper airway tract surgery were excluded. In the case of a patient who stays one day in the hospital, it has been canceled.
Procedure
All children had a careful oral examination performed by two experienced dentists (ICC > 0.8). Before entering the operation room, gender, age, and dental condition were recorded using the decayed, missing, and filled teeth (DMFT) index criteria23 using WHO probes with 0.5 mm ball-shaped end (548/4, Medesy, Pordenone, Italy). In addition, the occlusal stage and inter-molar relationship were documented. Mallampati score and inter-incisor distance were measured with a maximum mouth opening, and the patient was seated. The thyromental distance was evaluated while the child was lying on the bed, their head at 45 degrees to the horizontal, and the neck was fully extended. The plan to manage the airway tract and anesthetic technique was left to the judgment of the supervising anesthesiologist and resident, who were blinded since they were unaware that the patient was participating in the study. Oral tracheal intubation was performed utilizing a Macintosh blade (Welch Allyn Standard Laryngoscope Blade- English MacIntosh- Size 2. MFID: 69242, New-Med Instruments, Sialkot, Pakistan). However, when oral tracheal intubation and Macintosh blades were not used, the patient was excluded automatically. The same two dentists performed a second oral examination after 12–24 h of GA (ICC > 0.8). In the event of TDIs, dental and soft oral tissue injuries were documented according to WHO’s classification modified by Andreasen et al.9. Moreover, the researcher recorded the number of intubation trials, the resident’s assessment of the difficulty of intubation according to the American Society of Anesthesiologists Practice Guidelines for Management of the Difficult Airway24, and the duration of anesthesia.
Data analysis
All statistical analyses were conducted utilizing the IBM SPSS software version 25 (IBM Corp., Armonk, NY, USA). The p-value was considered significant if it was less than 0.05 (p < 0.05). Kolmogorov-Smirnov test demonstrated that the data didn’t follow the normal distribution. Thus, the Mann-Whitney U test was used to compare two independent groups that are healthy children and those with TDIs, in the numeric variables (number of intubation attempts - duration of anesthesia - inter-incisor distance - the distance between the mental and the thyroid cartilage - DMFT + dmft index) according to TDIs occurrence. The chi-square test was used to study the correlation between TDI incidence and patients’ features, which are categorical variables (gender – age - occlusal stage - inter-molar relationship - Mallampati score - the resident’s assessment of the intubation difficulty). If the independent variables have a significance difference at p < 0.05 in the previous analyses, they were more investigated using Multi-logistic regression. Multi-logistic regression analysis was utilized to determine the potential risk factors for TDIs. Descriptive statistics were presented as frequency, percentage, minimum, maximum, mean, and standard deviation.
Results
Of the 150 children, 98 (65.30%) were male, and 52 (34.70%) were female (Table 1). The Mean age was 7.49 ± 2.47 years. In terms of the occlusal stage, 49 (32.70%) had primary teeth, and 101 (67.30%) had primary and permanent teeth (Mixed dentition). From those, 60 (40.00%) have a class I inter-molar relationship, 47 (31.30%) have a mesial step, 16 (10.70%) have class II, 12 (8.00%) have a straight line, 10 (6.70%) distal step, and just 5 (3.30%) have class III inter-molar relationship. The DMFT + dmft index and presence of gingivitis distribution are described in (Table 1). The minimum number observed regarding DMFT + dmft was 0.00, and the maximum value was 18.00, with a mean of 4.90 (Table 2). The temporomandibular joint was normal in 139 (92.70%) and had a problem in 11 (7.30%). Mallampati score was class I in 51 (34%), class II in 44 (29.30%), class III in 24 (16.00%), and class IV in 31 (20.7.00%).
Table 1.
Demographic data and clinical characteristics of study participants.
| Categorical variables | N | % | |
|---|---|---|---|
| Gender | Male | 98 | 65.30 |
| Female | 52 | 34.70 | |
| Occlusion stage | Primary dentition | 49 | 32.70 |
| Mixed dentition | 101 | 67.30 | |
| Age (years) | 4–6 | 57 | 38.00 |
| 7–9 | 58 | 38.70 | |
| 10–13 | 35 | 23.30 | |
| Temporomandibular Joint | Normal | 139 | 92.70 |
| Not normal | 11 | 7.30 | |
| Occlusal classification of intermolar relationship | Class I | 60 | 40.00 |
| Class II | 16 | 10.70 | |
| Class III | 5 | 3.30 | |
| Straight line | 12 | 8.00 | |
| Mesial step | 47 | 31.30 | |
| Distal step | 10 | 6.70 | |
| Mallampati score | I | 51 | 34.00 |
| II | 44 | 29.30 | |
| III | 24 | 16.00 | |
| IV | 31 | 20.70 | |
| DMFT + dmft | 00 | 30 | 20.00 |
| 1–2 | 18 | 12.00 | |
| 3–4 | 22 | 14.70 | |
| > 5 | 80 | 53.30 | |
| Gingivitis | Yes | 41 | 27.30 |
| No | 109 | 72.70 | |
N, number of children; %, percentage of children; DMFT, mean number of decayed, missing, and filled permanent teeth; dmft, mean number of decayed, missing, and filled primary teeth.
Table 2.
Descriptive statistics of the numerical variables in study participants.
| Minimum | Maximum | Mean | SD | |
|---|---|---|---|---|
| Age (years) | 4.00 | 13.00 | 7.50 | 2.48 |
| Inter-incisor distance (cm) | 2.00 | 4.80 | 3.33 | 0.67 |
| The distance between the mental and thyroid cartilage (cm) | 4.00 | 9.50 | 6.92 | 1.18 |
| DMFT + dmft index | 0.00 | 18.00 | 4.97 | 3.92 |
SD, standard deviation; DMFT, mean number of decayed, missing, and filled permanent teeth; dmft, mean number of decayed, missing, and filled primary teeth.
Regarding inter-incisor distance, the minimum number recorded was 2.00 cm, while the maximum value was 4.80 cm with a mean of 3.30 cm. In addition, the mean distance between the mental and thyroid cartilage was 6.90 cm.
During the anesthesia procedures, difficult intubation was observed in 38 (25.30%) patients (Table 3), with a mean of intubation attempts of 3.23 (Table 4). The mean duration of anesthesia was 2.4 h, and 58 (38.70%) of total intubation operations were performed by the second years’ residents, 38 (25.30%) by the third years’ residents, 31 (20.70%) by the fourth years’ residents, and just 23 (15.30%) by the first years’ residents (Table 3).
Table 3.
Description of information collected during GA.
| Categorical variables | N | % | |
|---|---|---|---|
| Year of the residency | 1 | 23 | 15.30 |
| 2 | 58 | 38.70 | |
| 3 | 38 | 25.30 | |
| 4 | 31 | 20.70 | |
| The resident’s assessment of the difficulty of intubation | It was difficult | 38 | 25.30 |
| It wasn’t difficult | 112 | 74.70 | |
GA, general anesthesia; N, number of children; %, percentage of children.
Table 4.
Descriptive statistics of the numerical variables during GA.
| Minimum | Maximum | Mean | SD | |
|---|---|---|---|---|
| Number of intubation attempts | 1.00 | 9.00 | 3.25 | 2.00 |
| Duration of anesthesia (h) | 0.50 | 6.00 | 2.46 | 1.08 |
GA, general anesthesia; SD, standard deviation.
During and post-intubation examinations demonstrated that TDIs were in 24 (16.00%) children. These injuries affected both the extra and intra-oral cavity. In extra-oral injuries, only 3 (75.00%) cases were pain in TMJ, and just one was pain with limited mouth opening. Regarding intra-oral injuries, 15 (75.00%) were soft tissue injuries and 5 (5.00%) were hard tissue injuries. Moreover, hard tissue injury types were disturbed as follows: concussion (60.00%), avulsion (20.00%), and sub-luxation (20.00%). While soft tissue injury locations were as follows: 46.60% on the tongue, 33.30% on the upper lip, and 20.10% on the floor of the mouth (Table 5). All injuries were single, and right maxillary first primary central incisor (avulsion and subluxation) (Fig. 1) and maxillary first permanent central incisors (concussion) were the only teeth affected.
Table 5.
Distribution of traumatic dental injuries during GA among hospitalized children.
| N | % of the same type of injuries | % of TDIs | % of the total sample | ||
|---|---|---|---|---|---|
| Incidence of TDIs during ETI in GA | 24 | ||||
| Place of TDIs | Intra-oral | 20 | 83.33 | 83.30 | 13.30 |
| Extra-oral | 4 | 16.67 | 26.70 | 2.70 | |
| Extra-oral TDIs | Pain in TMJ | 3 | 75.00 | 12.50 | 2.00 |
| Pain in TMJ with the limited opening of the mouth | 1 | 25.00 | 4.20 | 0.70 | |
| Intra-oral TDIs | Soft tissue | 15 | 75.00 | 62.50 | 10.00 |
| Hard tissue | 5 | 25.00 | 20.80 | 3.30 | |
| Type of hard tissue TDIs | Concussion | 3 | 60.00 | 12.50 | 2.00 |
| Sub-luxation | 1 | 20.00 | 4.15 | 0.70 | |
| Avulsion | 1 | 20.00 | 4.15 | 0.70 | |
| Location of soft tissue TDIs | Tongue | 7 | 46.60 | 29.20 | 4.70 |
| Upper lip | 5 | 33.30 | 20.80 | 3.30 | |
| Floor of mouth | 3 | 20.10 | 12.50 | 2.00 | |
GA, general anesthesia; N, number of children; %, percentage of children, TDIs, traumatic dental injuries; ETI, endotracheal intubation, TMJ, temporomandibular joint.
Fig. 1.
Avulsed right maxillary first deciduous central incisor endotracheal intubation in general anesthesia.
When patients without TDIs were compared with patients with TDIs. Gender, year of residents, and DMFT + dmft index weren’t associated with the incidence of TDIs during GA (p > 0.05) (Table 6). The chi-square test showed that the incidence of TDI in primary dentition was higher than in mixed dentition with a statistical difference (p = 0.003). In addition, the 4–6 age group has the highest number of injuries (62.50%). The III and IV grades of the Mallampati score, the mesial step of the inter-molar relationship, and the presence of gingivitis have the greatest possibility of TDIs during oral intubation in general anesthesia.
Table 6.
Association between incidence of TDIs and factors studied using Chi-square test.
| Incidence of TDIs during ETI in GA | p-value | |||||
| No | Yes | |||||
| N | % | N | % | |||
| Gender | Male | 82 | 83.70 | 16 | 16.30 | 0.881 |
| Female | 44 | 84.70 | 8 | 15.30 | ||
| Occlusal stage | Primary dentition | 35 | 71.50 | 14 | 28.50 | 0.003 * |
| Mixed dentition | 91 | 90.10 | 10 | 9.90 | ||
| Age (years) | 4–6 | 42 | 73.70 | 15 | 26.30 | 0.017 * |
| 7–9 | 54 | 93.10 | 4 | 6.90 | ||
| 10–13 | 30 | 85.70 | 5 | 14.30 | ||
| Year of the residency | 1 | 19 | 82.60 | 4 | 17.40 | 0.417 |
| 2 | 46 | 79.40 | 12 | 20.60 | ||
| 3 | 35 | 92.10 | 3 | 7.90 | ||
| 4 | 26 | 83.90 | 5 | 16.10 | ||
| The resident’s assessment of the difficulty of intubation | Difficult | 17 | 44.70 | 21 | 55.30 | 0.001 * |
| Not difficult | 109 | 97.30 | 3 | 2.70 | ||
| Evaluation of the temporomandibular Joint | Normal | 119 | 85.60 | 20 | 14.40 | 0.105 |
| Not normal | 7 | 63.30 | 4 | 36.70 | ||
| Occlusal classification of intermolar relationship | Class I | 56 | 93.40 | 4 | 6.60 | 0.017 * |
| Class II | 13 | 82.40 | 3 | 17.60 | ||
| Class III | 2 | 40.00 | 3 | 60.00 | ||
| Straight line | 11 | 91.70 | 1 | 8.30 | ||
| Mesial step | 36 | 76.60 | 11 | 23.40 | ||
| Distal step | 8 | 80.00 | 2 | 20.00 | ||
| Mallampati score | I | 49 | 96.10 | 2 | 3.90 | < 0.001* |
| II | 41 | 93.20 | 3 | 6.80 | ||
| III | 16 | 66.70 | 8 | 33.30 | ||
| IV | 20 | 64.50 | 11 | 35.50 | ||
| DMFT + dmft | 00 | 27 | 90.00 | 3 | 10.00 | 0.105 |
| 1–2 | 14 | 77.80 | 4 | 22.20 | ||
| 3–4 | 15 | 68.20 | 7 | 31.80 | ||
| > 5 | 70 | 87.50 | 10 | 12.50 | ||
| Gingivitis | Yes | 15 | 75.00 | 5 | 25.00 | 0.017 * |
| No | 85 | 94.40 | 5 | 5.60 | ||
TDIs, traumatic dental injuries; ETI, endotracheal intubation GA, general anesthesia; N, number of cases; %, percentage of cases according to incidence of TDIs; *, significant difference p-value < 0.05, p-values written in bold are statistically significant (p < 0.05); DMFT, mean number of decayed, missing, and filled permanent teeth; dmft, mean number of decayed, missing, and filled primary teeth.
According to the Mann-Whitney U test, there were significant differences between the group of TDI incidence and the healthy group related to the number of attempts (p < 0.001), Inter-incisor distance (p < 0.001), and the distance between the mental and thyroid cartilage (p = 0.028). However, no significant difference was found in duration of anesthesia (p = 0.983) (Table 7).
Table 7.
The results of Mann-Whitney U test for comparing between healthy children and those with TDIs.
| Incidence of TDIs | p-value | ||
|---|---|---|---|
| No | Yes | ||
| Mean | Mean | ||
| Age (years) | 7.63 | 6.77 | 0.063 |
| Number of attempts | 2.80 | 5.62 | < 0.001* |
| Duration of anesthesia (h) | 2.47 | 2.39 | 0.983 |
| Inter-incisor distance (cm) | 3.42 | 2.84 | < 0.001* |
| The distance between the mental and thyroid cartilage (cm) | 7.01 | 6.40 | < 0.028* |
| DMFT + dmft index | 4.98 | 4.91 | 0.676 |
TDIs, traumatic dental injuries; *, significant difference p-value < 0.05, p-values written in bold are statistically significant (p < 0.05); DMFT, mean number of decayed, missing, and filled permanent teeth; dmft, mean number of decayed, missing, and filled primary teeth.
All of the variables that have a significant difference or correlation (occlusal stage, age, the resident’s assessment of the difficulty of intubation, occlusal classification of intermolar relationship, Mallampati score, gingivitis, number of attempts, Inter-incisor distance, and the distance between the mental and thyroid cartilage) were undergo to multi-logistic regression individually, and then all factors were collected together.
Multi-logistic regression demonstrated that Children who have primary teeth are 3.60 times as likely to the occurrence of TDIs during oral intubation in general anesthesia than mixed dentition. In addition, children with difficult intubation are 50.00 times more likely to have TDIs (Table 8). Moreover, the IV-grade Mallampati score is 13.50 times more exposed to TDIs than the I grade. As the number of intubation attempts increases, the risk of incidence of TDIs increases 2.27 times. However, there wasn’t a significant coefficient related to the occlusal classification of the intermolar relationship (Table 8).
Table 8.
Association between TDIs and patients’ characteristics utilizing multi-regression analysis. Each explanatory variable was studied without adding the other variables. Values are number (95% CI).
| OR | p-value | ||
|---|---|---|---|
| Occlusal stage | Primary dentition | 3.640 (1.47–8.95) | 0.005 * |
| Mixed dentition | 1** | ||
| Age (years) | 4–6 | 2.140 (0.70–6.53) | 0.180 |
| 7–9 | 0.444 (0.11–1.78) | 0.252 | |
| 10–13 | 1** | ||
| the resident’s assessment of the difficulty of intubation | Difficult | 1** | |
| Not difficult | 0.020 (0.01–0.08) | 0.001 * | |
| Occlusal classification of intermolar relationship | Class I | 0.286 (0.04–1.82) | 0.185 |
| Class II | 0.923 (0.12–6.78) | 0.937 | |
| Class III | 6.000 (0.56–63.98) | 0.138 | |
| Straight line | 0.364 (0.02–4.73) | 0.440 | |
| Mesial step | 1.200 (0.22–6.62) | 0.816 | |
| Distal step | 1** | ||
| Mallampati score | I | 0.074 (0.01–0.36) | 0.001 * |
| II | 0.133 (0.03–0.53) | 0.004 * | |
| III | 0.909 (0.29–2.79) | 0.868 | |
| IV | 1** | ||
| Gingivitis | Yes | 2.700 (1.09–6.67) | 0.030 * |
| No | 1** | ||
| Number of attempts | 2.270 (1.65–3.13) | 0.001 * | |
| Inter-incisor distance (cm) | 0.222 (0.09–0.49) | 0.001 * | |
| The distance between the mental and thyroid cartilage (cm) | 0.629 (0.42–0.94) | 0.024 * | |
TDIs, traumatic dental injuries; CI, confidence intervals, OR, odds ratios; **, the reference; *, significant difference p-value < 0.05, p-values written in bold are statistically significant (p < 0.05).
When all the explanatory variables (which had significant coefficients previously) were collected together to build a comprehensive model using Multi-logistic regression, all of them lost their statistical significance, except the 7–9 age group and the III grade of the Mallampati score. (Table 9) With consideration of all explanatory variables in the model, multi-logistic regression showed that children who were in the 10–13 age group were 6.60 times more likely to have TDIs during oral intubation in general anesthesia than the 7–9 age group. In addition, children with a III grade on the Mallampati score are 10.6 times more likely to have TDIs than IV grade.
Table 9.
Association between TDIs and patients’ characteristics utilizing multi-regression analysis. All explanatory variables were studied together. Values are number (95% CI).
| OR | p-value | ||
|---|---|---|---|
| Occlusal stage | Primary dentition | 0.448 (0.01–20.92) | 0.682 |
| Mixed dentition | 1** | ||
| Age (years) | 4–6 | 0.060 (0.001–2.53) | 0.140 |
| 7–9 | 0.015 (0.001–0.42) | 0.014 * | |
| 10–13 | 1** | ||
| The resident’s assessment of the difficulty of intubation | Difficult | 1** | |
| Not difficult | 0.078 (0.01–1.14) | 0.063 | |
| Occlusal classification of intermolar relationship | Class I | 0.590 (0.01–32.22) | 0.796 |
| Class II | 5.730 (0.06–491.22) | 0.442 | |
| Class III | 57.830 (0.35–9293.73) | 0.119 | |
| Straight line | 1.070 (0.02–57.36) | 0.972 | |
| Mesial step | 2.930 (0.17–49.45) | 0.454 | |
| Distal step | 1** | ||
| Mallampati score | I | 2.480 (0.01–32.22) | 0.559 |
| II | 1.340 (0.11–17.34) | 0.818 | |
| III | 10.640 (1.06–106.97) | 0.044 * | |
| IV | 1** | ||
| Gingivitis | Yes | 4.600 (0.78–26.96) | 0.090 |
| No | 1** | ||
| Number of attempts | 1.620 (0.84–3.13) | 0.149 | |
| Inter-incisor distance (cm) | 0.282 (0.02–3.12) | 0.302 | |
| The distance between the mental and thyroid cartilage (cm) | 0.872 (0.41–1.86) | 0.724 | |
TDIs, traumatic dental injuries; CI, confidence intervals, OR, odds ratios; **, the reference; *, significant difference p-value < 0.05, p-values written in bold are statistically significant (p < 0.05).
Discussion
TDIs cause pain, discomfort, psychological problems, emotional distress, and difficulty in communication with peers and society. Thus, TDIs affect children’s quality of life25,26. TDIs are generally more time-consuming and expensive than other types of unintentional injuries that present in emergency clinics and hospitals27.
There are many causes and risk factors related to the occurrence of TDIs. Iatrogenic injuries are the most common, which mainly consist of damages related to endotracheal intubation (ETI) and laryngoscopy2,11,13,28.
According to Lam et al.27, researchers can study the epidemiology of TDIs in retrospective and prospective studies. In retrospective studies, the researchers use a percentage called prevalence, which means the total number of injuries that have occurred in a population at a specific point in time. However, in the prospective studies, the researchers use a percentage called incidence, which means the total number of new injuries in a given population from a specific point in time. These studies are more time-consuming and resource-intensive, especially when a long period is chosen for data collation. According to Kestenbaum et al.29, there are two definitions of incidence differing by the choice of denominator Incidence proportion (%) = number of new cases of disease over time/population without disease at baseline × 100%. Incidence rate (case per person – time) = number of new cases of disease over time/person-time at risk. In this study, the authors used the first form like most of the same studies4,10,30,35.
The sample size was set according to Nahas et al.31study, which is an observational study conducted in the same community and the same circumstances. In addition, the same studies had a sample size equal to or less than this study30, which consisted of 46 individuals of different ages, and Mourão et al.10 study which consisted of 121 individuals in ages ranged between 18 and 78. In this study, the authors studied TDIs in a specific age group that are difficult to manage, especially during follow-up periods when children are tired or unable to cooperate.
This study demonstrated a high incidence of TDIs during ETI during GA among hospitalized children. This value is higher than recorded in many retrospective studies15,17,28,32–35. However, it was less than the percentages documented in the Mourão et al.4,10,35 studies, the Christensen et al.36 study, the Manifar et al.8 study, and the Chen et al.19 study. That can be attributed to the careful pre and postoperative examination, which included two professional dentists.
The incidence of soft tissue injuries was higher than the incidence of hard tissue injuries in the oral cavity. This finding agrees with the results of the Manifar et al.8study. This type of injury is common but not life-threatening12. The tongue was the most common location for TDIs in GA (46.6%), which confirms the results of many studies4,8,10,37, followed by the upper lip (33.3%) and the floor of the mouth (20.1%).
Regarding intra-oral hard tissue injuries, maxillary central incisors were the most teeth affected. This result is consistent with most studies4,8,11–15,17–20,28,33–36,38–42. It can be explained by the nature of the laryngoscopy procedure, which exerts a lot of pressure on maxillary incisors. In addition, the Macintosh blade’s prominent flange may help43. According to the Newland et al.15study, the right side is more vulnerable to injury than the left, which agrees with the current study. That can clarified by the anesthesiologists initially inserting the laryngoscope into the right side of the oral cavity, then rotating the blade to the left when they reach the pharynx44. This study found that concussion is the most common type of hard tissue injury, while one avulsion was noted. However, this discrepancy was found in many published studies10,15,17,33,36. The percussion test, which was used in this study, is one of the exclusive tools to diagnose concussion injuries, which are considered a clinically silent injury45.
There wasn’t a significant correlation between the gender of children and TDIs. In addition, the resident experience wasn’t associated with the occurrence of injuries. This result confirms what was mentioned in the Gaiser and Castro46study. It can attributed to the strict assessment of the condition and continuous supervision by specialized anesthesiologists. However, the occlusion stage correlated with TDIs. The multi-logistic regression test showed that primary dentition is 3.64 times more vulnerable to exposure to TDIs during ETI than mixed dentition. This result conflicts with what was mentioned in the Windsor and Lockie12review. In addition, the 4–6 age group has the highest number of injuries (62.5%), and the age group had a significant correlation with TDIs. However, when Multi-logistic regression was used to build a comprehensive model of explanatory factors, the 10–13 age group had the highest probability of having TDIs. This result is consistent with many studies15,33, which reported that the older the patient, the higher the risk of exposure to the injury.
Endotracheal Intubation is a vital procedure that consists of equipment, including a classic laryngoscope, which can harm the hard and soft tissues. Laryngoscope is the main responsible tool for causing TDIs, whether in selective or emergency cases5,7,19.
The chi-square test resulted in a significant difference related to the intubation difficulty. This result confirms what was documented in many studies14,15,33. In addition, there was a significant difference between the TDIs group and the healthy group concerning the number of intubation attempts. Multi-logistic regression demonstrated that as intubation attempts increase, the risk of injury is increased. This outcome is similar to the outcome of the Mourão et al.35study. TDIs may result from the anesthesiologist’s repeated attempts at intubation, which may need a higher force (> 49 N) to view the epiglottis with the laryngoscope blade43.
The Mallampati test is used to estimate the difficulty of airway management since it relates to the tongue size and the maximum mouth opening, which can be potential predictors of the difficulty of intubation47. It depends on evaluating the oral soft tissues and the amount of space they occupy when the pharynx is visualized47. Sitot et al.48 suggested that the Mallampati test is an accurate predictor of difficult laryngoscopy. The Mallampati test is scored by viewing the oropharynx when the patient is seated with their head in a neutral position. The mouth opens maximally, and the tongue fully protrudes. This study found that those who have a III and IV grade on the score have the highest number of injuries, and there is a significant relation with the incidence of TDIs during GA. This finding confirms what was reported in the study by Sitot et al.48and can be explained by the III and IV grades, which refer to the difficulty in intubation. In grade III, only the soft palate is visible, and in grade IV, nothing beyond the tongue is observable, only the hard palate. Patients presented with difficult airways are more prone to TDIs compared with those with straightforward airways47,48.
The mean distance between mental and thyroid cartilage in the TDIs group (2.84 cm) was significantly less than recorded in the healthy group (3.42 cm). This result makes the distance between mental and thyroid cartilage a predictive factor in the TDI incidence during GA. This result agrees with the results of many studies4,35. In addition, it can be attributed to the fact that the distance between mental and thyroid cartilage is one of the measures to evaluate the difficulty of the airway48.
Mann-Whitney test showed that the difference related to inter-incisor distance between the two studied groups was significant. It confirms what was noted in many studies12,13,35,39. However, this result is different from the Mourão et al.4 study and the Tan et al.18 study.
This study didn’t reveal a significant association between the values of DMFT + dmft index and TDIs during ETI in GA. This result contrasts many studies14,15,33,36. It can be explained by the fact that Syrian children have a high number on the DMFT index49.
The comprehensive model built using Multi-logistic regression showed that TDIs during ETI in GA are combined injuries consisting of multi-risk factors. However, children who were in the 7–9 age group and children who have grade III on the Mallampati score noticeably have higher properties to injury during general anesthesia.
The main limitation of this study is the inadequate power of the small sample size. Thus, the results of the current study should be generalized with caution due to the lack of reliability. In addition, there is no radiographic diagnosis, data related to the classification of the laryngeal view during direct laryngoscopy, or comparison between classic laryngoscopes and other devices like flexible bronchoscopic intubation and video laryngoscopy.
Conclusions
Based on our findings, TDIs during oral tracheal intubation in GA are injuries with many risk factors and cannot be avoided even with skilled anesthetists. Careful Preoperative clinical examination of the oral cavity by anesthesiologists, especially with difficult intubation, can reduce the incidence of TDIs during oral tracheal intubation by laryngoscope during GA and improve the quality of procedures. In addition, the medical staff must inform the patient about the possibility of dental injury, especially when having some related risk factors. Moreover, a protocol should be developed to help the medical team, including dentists, who must play a role in the assessment procedure by recording all patients’ details. It may help in avoiding legal claims and dental problems. Clinical dentistry concepts about the anatomy of the oral cavity and treatment plans should be included in anesthesiologists’ courses to reduce those injuries and raise awareness among anesthesiologists. In addition, using existing tests and indexes to prevent oral trauma can be quite beneficial. Dentists have a critical role in assessing patients undergoing endotracheal intubation. Patients with GA should have a full oral and dental examination by a dentist or anesthesiologist. Furthermore, the likelihood of this kind of injury occurring during oral-endotracheal intubation was increased by many intubation attempts, intubation difficulty, III or IV Mallampati score, occlusal stage, and inter-incisor distance.
Author contributions
M.N.A.S. collected data, extracted the data and performed the statistical analysis, wrote the manuscript; M.A. research concept and design, supervised the project, performed critical revision of the manuscript; M.K. contributed to writing. All authors have read and approved the manuscript.
Funding
This research is funded by Damascus University – funder No. 501100020595.
Data availability
The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.
Declarations
Competing interests
The authors declare no competing interests.
Informed consent
Informed consent was obtained from all subjects.
Footnotes
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.