The Level of Anesthesia Resident Training Does Not Affect the Risk of Dental Injury

Dental trauma is the most common complication of general anesthesia. Retrospective analysis reports an incidence of 1:1000 endotracheal intubations [1], but prospective analysis reports a higher incidence. Chen et al. [2] studied a series of 745 patients undergoing endotracheal anesthesia whose dentitia was examined both before and after the anesthetic. The frequency of dental damage was 12.1%. Based on this report, Chadwick and Lindsay [3], both dental surgeons, advocated a dental examination by a dental surgeon before any anesthetic involving endotracheal intubation. Precautionary measures could be taken, and customized mouth guards could be made before the surgery. However, this action is not cost-effective for all patients. It is important to identify risk factors preoperatively to effectively use this information. Risk factors for dental injury include periodontal disease and dental prostheses [4]. Several authors cite dental trauma as a frequent cause of litigation. Chadwick and Lindsay [3] reported that dental injury accounted for one third of all confirmed or potential anesthetic claims reported to the Medical Protection Society between 1977 and 1986. Over a 7-yr period, the Harvard Risk Management Foundation found that dental damage was the most common injury associated with malpractice claims, accounting for 29% of all cases filed [5]. A review of the Accident Compensation Corporation files in New Zealand found dental trauma to be relatively common [6]. Thus, dental trauma not only is an annoyance for the patient, but also has possible financial implications for the anesthesiologist in terms of time and reimbursement. No study has examined the influence of the level of training of the individuals providing the anesthesia on the risk of dental injury or the characteristics of at-risk patients. Lockhart et al. [7] reported a frequency of dental injury of 1:1000 when general anesthesia was provided by an anesthesia resident. This study relied on a survey sent to 133 directors of training programs in anesthesiology and did not examine whether the level of training affected the incidence of dental injury. For the study period at our institution, all anesthetics were provided by anesthesia residents supervised by attending anesthesiologists in a 1:1 or 2:1 ratio. Case assignments were based on the resident's rotation for the month and was not influenced by the level of training or the anticipated difficulty of the airway. The purpose of this retrospective study was to determine the risk of dental injury when general anesthesia is provided by residents at various levels of training. Methods With institutional review board approval, we reviewed the medical records of all patients sustaining a dental injury during the period of 1992-1996. Dental injuries were identified by the anesthesiologist reporting an injury or by the patients noting a change postoperatively. Data obtained included patient age, height, weight, level of training of anesthesia resident, evidence of preoperative documentation of dental status, and amount of reimbursement for dental claims. For this time period, the residents' American Board of Anesthesiologists reports were also reviewed to determine the number of general anesthetics performed. Relative risks with 95% confidence intervals were calculated for each level of training. Results Sixty dental injuries were identified. The records of 97 anesthesia residents were reviewed, and the total number of general anesthetics performed during this period was 61,139. The incidence of dental injury when general anesthesia was provided by an anesthesia resident was 0.1%. Table 1 categorizes dental injuries based on the level of training of anesthesia residents. The relative risk is also presented. Of the dental injuries, 51% were in women. The ages of the patients ranged from 24 to 87 yr, with a median of 56 yr. The height recorded for these patients was 138-193 cm (median 168 cm). The weights of those patients with dental injuries ranged from 46 to 136 kg (median 80 kg). Table 2 presents the location of the dental injuries. Except for Teeth 9 and 24, which are positioned in the middle, all injuries occurred on the right side. There was no documentation of preoperative dental status in 30% of the injuries. There was payment in 36% of the injuries, ranging from $42 to $6476 (median $125). There was no case associated with a law suit.Table 1: Incidence of Dental Injury and Risk Based on Level of TrainingTable 2: Location and Frequency of Dental InjuryDiscussion In our retrospective study, the overall incidence of dental injury when general anesthesia is provided by a resident in training was 1:1000. Although medical students and other trainees were working with residents, no injuries were caused by these less experienced trainees. This most likely represents the high selection criteria for appropriate intubations by these trainees. When one calculates the relative risk based on the level of training, there seems to be a slight increase in risk when the resident is the first or second year and a protective effect when the resident is the third year. However, with 95% confidence, the interval for each level of training includes the null value; the observed association is not statistically significant at the 0.05 level. This is reassuring to those involved in the education of residents, as the level of training does not affect the risk of dental injury. For each level of training, a confidence interval was calculated, and the width of each interval was narrow. The width of the confidence interval indicates the amount of variability inherent in the relative risk and, thus, the effect of sample size. The larger the study sample, the more stable the estimate and the narrower the confidence interval. Although the intervals for the first and second years of training (0.7-2.0 and 0.7-2.1) were larger than that for the third year (0.3-1.1), all intervals were narrow enough to support to the claim that there is no increased risk for each level of training. One limitation of our study is its retrospective nature. Dental injuries were identified by the attending or resident anesthesiologist intraoperatively or by the patient postoperatively. Injuries in which the anesthesiologist failed to note the injury or in which the patient assumed the injury was part of the anesthetic and did not report it were missed. Furthermore, minor damage, such as microfractures of the enamel, may have been undetected. Thus, the actual incidence may be higher, although our incidence did not differ from other retrospective studies. All injuries were on the patient's right side, both upper and lower, which suggests that not only laryngoscopy, but also placement of the endotracheal tube, can result in injury. The finding that dental work accounted for a significant percentage of the injuries (40%) is not surprising and has been previously reported [1]. When examining the demographics of patients who sustained an injury, we were unable to determine the high-risk patient because the ranges for height and weight were large. Dental injury can occur in any patient regardless of height, weight, gender, or age. In regard to payment, the range is also great. However, payment was made when the chart did not contain appropriate documentation concerning preoperative dental status and counseling about the risk of injury. The policy of dental injury in our department is reviewed with the residents each year, and documentation of preoperative dental status and of the risk of dental damage are emphasized. If it is written in the chart that the patient is at particular risk of dental trauma based on physical examination and that the patient understood and consented to these risks, payment is not made. Payment is made in those cases in which there is incomplete documentation or in which the chart states that there were no dental problems preoperatively. We attempt to avoid litigation through proper risk management, as res ipsa loquitur has been successfully used in cases involving dental injury [8]. It is imperative that the preoperative assessment include dental status and documentation that the risk of dental injury was discussed.