Surgeons' Prediction of Dental Surgery Complications and the Influence of Patient Characteristics: Development of an AI Model

Objective Clinical decision-making is based on intuition and experience, patients value, and the biological plausibility supported by literature. Prior to oral surgery the surgeon must consider patient-related, surgical-related and tooth-related factors. It can be limited by human ability, which is why artificial intelligence is suggested to improve clinical decision-making. An assessment tool that predicts complications has not yet been established.

Aim This study aims to evaluate the incidence and predictors of intra- and postoperative complications and assess the surgeon's ability to foresee these events. The study aims to systematize predictable variables to create an artificial intelligence prediction model to assist the oral surgeon in clinical decision-making. The current study will describe the frequencies of complication at a private referral clinic, Specialtandlægerne Sjælland (SPSJ), and clarify the impact of the surgeon and patient as predictive variables. The study contributes to advancing the use of artificial intelligence with the aim of improving clinical outcomes for patients, reducing the occurrence of complications intra- and postoperatively as well as ease the work of the surgeon. The study can potentially provide information regarding optimizing treatment, prognosis, survival and success of oral surgery. In addition, the study will provide valuable information about the surgeon's predictive abilities, and the impact of the patient's anxiety level and personal characteristics on the outcome of successful treatment.

Background The current study will explore the most frequent surgical intervention at a referral dental clinic being third molar removal, apical root surgery and placement of dental implants. Complications can occur intra- and postoperatively and are rarely fatal but often disabling in the short- or longterm. Expected predictive variables will be reported. Sociodemographic factors, patient-related factors and surgeon-related factors will be reported in the same manner independently of the surgical procedure. Additionally, anatomic factors, pathological factors as well as factors related to surgical procedure might affect the risk of complications.

There is a lack of evidence in measuring surgeons' experience and the clinical impact of it as a predictive factor. Studies report a higher incidence of complications occurs for patients operated by less experienced surgeons, hereof an increased risk for alveolar nerve deficiency and postoperative pain. Contradictory, seniority did not impact operation time according to previous studies. Apical surgery requires special knowledge and skills. A study compared the pooled success rate between endodontists and oral and maxillofacial surgeons, with a slightly higher success rate from endodontists, but a greater confidence interval in the group of surgeons. The international team for implantology (ITI) consensus report 2019 states that the clinician constitutes a significant risk factor, however it is not included in the Simple-Advanced-Complex classification guideline due to lack of accuracy in its measure. The investigators will include the surgeon's risk assessment of complications, as well as a self assessment evaluation postoperatively.

Dental anxiety level can affect the postoperative recovery, have serious implications in clinical situations and is reported to impact the intraoperative difficulty. Anxiety can have different expressions, but an objective measure of anxiety is the Spielberger State-Trait Anxiety Inventory (STAI). Measuring the state anxiety prior to the surgery has not yet been examined in a dental referral clinic. This study will ask the patients to fill out the STAI-6 to measure state anxiety prior to the surgery. An association of negative affectivity (NA) and decreased oral health related quality of life has been found. NA is suggested to have influence on human experience and includes fear, anxiety, stress level, anger, guilt, hostility, irritability, being ashamed and jittery. Additionally, lack of compliance can delay implant treatment due to an indirect effect on the outcome. This study will elucidate the connection between NA, state anxiety and oral surgery.

Third molar removal Specifically for the third molar removal few complications have been reported but a great difference in frequencies of complications is reported. Worth mentioning is alveolar osteitis, abscess formation, continuous hemorrhage and prolonged pain anf trismus. Additionally, impaired sensation has been registered. If the third molar is adjacent to the nerve it happens that compression can give rise to a temporary sensory impairment. This will be registered, but the definition of a nerve injury in this study will be permanent sensory impairment, lasting >6 months and verified by a neurosensory evaluation method. Surgical time was significantly associated with postoperative pain, swelling and impaired sensation in the lower lip and may predispose to inflammatory complications. Pell and Gregory categorization describe the anatomic level of impaction of the third molar, ABC as the depth of impaction, and I, II or III as bone coverage from ramus mandibulae. A study concluded that the class C impaction was associated with an impaired sensation, worse postoperative discomfort and prolonged trismus. Another study reports a significant association with the level of impaction, pre-existing infections or pathology with postoperative complications (SSI or AO). Pathological variables include caries, periodontal disease, infection: cellulitis or abscess, resorption of adjacent tooth or internal resorption, tooth fracture, osteomyelitis, pathology of follicle hereof cyst or tumor. In terms of the surgical procedure, inappropriate flap retractions may increase the risk of periodontal defects on adjacent teeth. Whether to do a lingual retraction or not is much debated. It has been significantly associated with increased surgical time, worse postoperative pain, increased risk of AO with an OR. Conversely, it has been suggested to improve access, simplify the procedure, and lead to a higher incidence of temporary nerve deficiencies but a complete reduction in permanent nerve injuries.

Apical Surgery A study claims that surgical root resection is a minimally invasive procedure with few complications. Success rate is high, reported as 88% 6-12-month postoperatively or a consensus report states that it is >90%. A study concludes that a higher degree of infection and inflammation prior to surgery can affect the outcome negatively. Anatomic conditions might affect the outcome. Premolar has shown a significantly better outcome compared to anterior teeth or molars, mainly due to loss of buccal plate, as well as difficulty with the apical osteotomy on teeth with more than one root. A higher success rate has occurred for the anterior compared to posterior teeth and maxillary teeth compared to mandibular teeth. Except for the lateral incisor due to the perforation of the palatal cortical plate. A success outcome was significantly dependent on size of the lesion, tenderness to percussion or fistula present. Loss of buccal bone was reported as a predictive variable of surgical failure. Moreover, a high risk of sinus perforation was significantly associated with a distance of <1mm from apex to the maxillary sinus. However, sinus perforation is not considered a complication in this study unless it gives rise to the development of an oro-antral fistula 1-2 weeks postoperatively. A study concluded that better periapical healing rates occur after bevel resection and ultrasonic preparations 3mm coronally in the root canal compared to the bur-cut and class 1 cavity root filling.

Implantology To our knowledge, no AI-based model can predict complications following placement of dental implants, even though the ITI has a well-established assessment tool. A successful implant placement is based on osseointegration, survival rate, prosthesis stability, bone loss, absence of infection and asymptomatic conditions. Moreover, soft tissue is demanded to ensure peri-implant health, esthetics, good prosthodontic conditions and patient satisfaction. Dental implants often require augmentation of hard and/or soft tissue prior to or during surgery, which is suggested to be critical for peri-implant postoperative health.

Hypotheses The investigators hypothesize that the surgeons are good at predicting which patients will have postoperative complications. In addition, the investigators hypothesize that an artificial intelligence network trained by former data can increase the accuracy of these predictions.

Materials and methodology This prospective clinical observational study is conducted at a private referral dental clinic specialized in oral and maxillofacial surgery, SPSJ. The study design captures the natural progression of intra- or postoperative complications following routine clinical practice. The study is a collaboration with the Department of Odontology, University of Copenhagen. The surgical procedures involved in the study are third molar removal, apicoectomy, and placement of dental implants. The clinic receives referrals from dentists, and patients will then receive an invitation to participate in the study. A study population of approximately 3000 patients is expected. The referral clinic will facilitate equipment in terms of radiographic imaging, surgical instruments and clinical staff. Concerning dental implantology different biomaterials (Geistlich Pharma International: BioOss granulates, collagen or membranes) and implants (Dentsply Sirona or Straumann) will be used. Participation in this study will imply economic cost, but patients will be offered additional control visits free of costs.

Written consent will be obtained. Data will be collected through dental journals. In addition, questionnaires (STAI-6 and PANAS-SF) for patients prior to the surgery will be collected. Per- and postoperatively, questionnaires for the surgeons will be completed. All data will be treated confidentially with respect to the law of the Danish Data Protection Agency.

Predictive variables Sociodemographic factors: age, sex, medical status, the use of alcohol and tobacco, as well as a subdivision according to The American Society of Anesthesiologists Physical Status, ASA classification. In terms of anamnestic information, history of pain will be recorded, as well as intervention prior to surgery. Anatomic factors, pathological factors as well as factors related to surgical procedure will be reported. The time from first incision to last suture will be noted. In terms of the surgical procedure use of local analgesic agents (dosage, type and concentration), choice of incision, flap design and factors specific for the surgical procedure will be reported. Prescriptions will be included in the study, including analgesic and antibiotics prior to surgery or in the postoperative sequelae. The use of antibiotics will be based on guidelines from the national board of health in Denmark in 2019, as well as an individual assessment based on the patient's risk profile. The antibiotics used in the study will be penicillin V, or in combination with metronidazole. Clindamycin if the patient is allergic to penicillin, and prescription of broad-spectrum amoxicillin with clavulanic acid if an infection persists. It will be recorded if prescription of antibiotics has been ordinated prior to the referral, or if an antibiotic sensitivity test is indicated. In some cases, hallucinogenic medication (0.125/0.250 mg Halcion) or general anesthesia (propofol/remifentanil) are indicated.

The apical surgery treatment management will be flap elevation, osteotomy, identification of infected canals, curettage of granulation tissue, removal of root tips, and effective sealing with a biomaterial and subsequently sutural closure.

The current study will divide the implant cases into different main categories to systematize multiple possibilities. The time of implant placement following tooth extraction can be either type 1: immediate after tooth extraction, type 2: following soft tissue coverage (4-8 weeks), type 3: in clinical and radiographically sufficient bone (12-16 weeks) or type 4: in healed alveolar sockets. The loading protocol will be reported as well, which can either be >2 months after implant placement, namely conventional loading. Early loading if 1-2 months after implant placement, or immediate loading <1 week after implant placement. The category of implant placement and loading will be subdivided into 12 categories. Additionally, the surgeries will be classified as only implant placement, implant placement with simultaneous bone augmentation or with an open sinus lift, additionally. Another category will be an isolated bone augmentation procedure with either just autologous bone transplant harvested from the mandible, or an autologous bone transplant supported by a titanium enhanced membrane. The reconstruction of soft tissue can be either with autologous free gingival flap, connective tissue graft, with acellular dermal grafts or xenogeneic grafts. The guide for the implant surgical procedure provided by the manufacturer of implant will be complied with, and it will be reported if the implants are placed brain guided, partially guided or fully guided and how it affects the complication rate.

Statistical analysis Descriptive statistics will be used to characterize the study population and the frequency of complications, as well as the STAI-6 and NA level. Associations between predictive variables and complications will be examined using multivariate logistic regression analysis. The surgeon's ability to predict the patients who present complications will be rated. Additionally, the data will be analyzed by training an artificial intelligence model, the Random Forest algorithm, to explore the feasibility of predicting complications based on pre-, intra- and postoperative data.