Application of Surgical Templates in the Surgical Exposure of Impacted Canines

Overview

The first choice therapy in case of palatally impacted canines is their exposure and orthodontic eruption to improve facial esthetics and prevent pathologies associated with impacted teeth and Temporomandibular Joint Disorders. Current solutions in digital dentistry allow the registration of three dimensional imaging datasets such as cone beam computed tomography (CBCT) and digital impression of the dentition and soft tissues obtained via intraoral scanning using orthodontic planning software. This allows the surgeon to visualize the position of the impacted canine prior to surgery and to design and manufacture a surgical guide to aid in the localization of the impacted tooth during surgery. The aim of this randomized clinical trial is to assess the feasibility of surgical exposure of palatally impacted upper canines with open-eruption technique using a surgical template. The secondary purpose of this study is to compare this method with the conventional free-hand surgical exposure. Patients included in this study are randomly assigned to two study groups. In Group 1 surgical exposure for open eruption of palatally impacted canines is performed following virtual planning using a surgical template. In Group 2 surgical exposure for open-eruption of palatally impacted canines is carried out using the conventional free-hand method. We hypothesize that guided exposure of the impacted canines will be as successful as the conventional method with shorter surgical intervention and higher associated costs.

Objectives The aim of this randomized clinical trial is to assess the feasibility of surgical exposure of palatally impacted upper canines with open-eruption technique using a surgical template. The secondary purpose of this study is to compare this method with the conventional free-hand surgical exposure. Our null-hypothesis is that there will be no significant differences in the outcome measures between the two methods. Materials and methods Groups * Group 1 (test group): Surgical exposure for open eruption of palatally impacted canines following virtual planning using a surgical template. * Group 2 (control group): Surgical exposure for open-eruption of palatally impacted canines using the conventional free-hand method. Simple randomization is performed to determine whether patients are included in the test or control group. 20 patients are recruited per group. During continuous recruiting, sample size calculation is to be carried out to determine the actual number of patients included in this study. Surgical planning The upper jaw of the patient is scanned using an intraoral scanner (IOS, Trios 4, 3Shape, Copenhagen, Denmark). Cone beam tomography (CBCT) scans (Green X, Vatech, Hwaseong, Korea) are performed before surgical exposure to assess the position, angulation, possible dilaceration, and bone coverage of the impacted canines. The scanning conditions are constant at 200 μm isotropic voxel size with 360◦ rotation, 94 kiloVolt (kV) tube voltage, 7.2 miliAmper (mA) tube current, and 9 s exposure time with a field of view of 15 × 8 cm. In the test group OnyxCeph³™ software is used to register the standard tessellation language (STL) file of the digital impression with the Digital Imaging and Communications in Medicine (DICOM) data of the pre-operative CBCT reconstruction by surface registration. A surgical template is designed to cover the palate, incisal, and occlusal surfaces of the dentition with an opening that outlines the window to be prepared to expose the impacted canine. Fused deposition modeling (FDM) is used for the rapid prototyping of the surgical template (FlashForge Creator Pro 4, Zhejiang Flashforge 3D Technology Co., Ltd, Jinhua City, China) using polylactic acid filament (PLA). Surgery In both groups patients rinse their oral cavity with 0.2% chlorhexidine solution for 1 min before surgery and surgical interventions are performed under local anesthesia. In the test group the fit of the surgical template is a checked and a surgical laser (SiroLaser Blue, Dentsply Sirona, Charlotte, North Carolina, U.S.A.) is used for the exposure of the impacted canine. In the control group the surgeon relies on the surgical plan and their experience to localize the impacted canine. The attachment is bonded to the exposed canine by an orthodontist. Patients are instructed to clean the wound using toothpaste and toothbrush and to rinse with 0.2% chlorhexidine solution in the morning and in the evening for a week starting on the day after surgery. Anti-inflammatory drugs (25 mg diclofenac three times a day for 3 days) are prescribed to control postoperative pain Management of participant-bias Surgical planning and interventions are performed by a skilled surgeon. The clinician performing the exposure of the impacted canine is not involved in the evaluation of the outcome measures. The examiner carrying out the measurement of the outcome variables was blinded to the surgical modality used during surgery.