Surgical Template
Background: Mandible contour surgery, including reduction gonioplasty and genioplasty, has become increasingly popular in East Asia. However, it is technically challenging and, hence, leads to a long learning curve and high complication rates and often needs secondary revisions. The increasing use of 3-dimensional (3D) technology makes accurate single-stage mandible contour surgery with minimum complication rates possible with a virtual surgical plan (VSP) and 3-D surgical templates. This study is to establish a standardized protocol for VSP and 3-D surgical templates-assisted mandible contour surgery and evaluate the accuracy of the protocol.
surgical template
Methods: In this study, we enrolled 20 patients for mandible contour surgery. Our protocol is to perform VSP based on 3-D computed tomography data. Then, design and 3-D print surgical templates based on preoperative VSP. The accuracy of the method was analyzed by 3-D comparison of VSP and postoperative results using detailed computer analysis.
Result: All patients had symmetric, natural osteotomy lines and satisfactory facial ratios in a single-stage operation. The average relative error of VSP and postoperative result on the entire skull was 0.41 0.13 mm. The average new left gonial error was 0.43 0.77 mm. The average new right gonial error was 0.45 0.69 mm. The average pognion error was 0.79 1.21 mm. Patients were very satisfied with the aesthetic results. Surgeons were very satisfied with the performance of surgical templates to facilitate the operation.
Conclusions: Our standardized protocol of VSP and 3-D printed surgical templates-assisted single-stage mandible contour surgery results in accurate, safe, and predictable outcome in a single stage.
The desired configuration of the surgical stent is determined by the prescribed prosthesis. The surgical template dictates to the surgeon the implant body placement that offers the best combination of (1) support for the repetitive forces of occlusion, (2) esthetics, (3) hygiene requirements.[2,3]
Adrian et al. used auto polymerizing acrylic resin to fabricate radiographic cum surgical template. He molded lead foil over the maxillary and mandibular incisors and used lateral cephalogram to cross verify related parameters.[17] Tarlow employed the use of acrylic resin duplicate denture wherein he adapted vacuum-formed thermoplastic matrix (0.02 inch) over duplicate denture. Such designing dictates accurate implant location and angulations, with minimal interference to surgical access.[18] Espinosa Marino et al. showed the first clinical use of heat polymerizing acrylic resin in fabrication of the surgical template particularly for partially missing situations. To make it radio-opaque on CT, they applied dual-curing composite resin mixed with colored chalk.[8] Stellino et al. demonstrated acrylic resin provisional fixed restorations with the use of gutta parcha as redio-opaque marker.[19] This is particularly useful as an alternative for removable radiologic template where a provisional fixed restoration bridges the implant site. Pesun and Gardner used vacuum-formed thermoplastic matrix to adapt over diagnostic model.[20] Takeshita et al. were the first to introduce the concept of mixing acrylic resin with radio-opaque material to fabricate surgical template (instead of pure acrylic resin). They meshed barium sulate powder with acrylic resin in 4:1 ratio.[21] Sicilia et al. used orthodontic wires and auto polymerizing acrylic resin while Minoretti et al. used vacuum-formed thermoplastic matrix or auto-polymerizing acrylic resin to fabricate template.[22,23] The partially limiting design allows only the first drill for osteotomy wherein the remaining osteotomy and implant placement is finished freehand by the surgeon. This design philosophy basically follows the initial fabrication of a radiographic template, which is then converted into a surgical guide template following radiographic evaluation. Ku and Shen applied vacuum-formed thermoplastic matrix filled with auto polymerizing resin acrylic resin where the use to remove the marker with carbide bur later.[24] This designed is employed in single implant therapy or short-span implant-supported prostheses. Becker and Kaiser, Cehreli et al. used vacuum-formed thermoplastic matrix (0.020 inch) and orthodontic resin. They showed that this methodology construct very precise surgical guide resulting in a functional and aesthetically pleasing restoration. This was shown to be very valuable in placing implants in posterior maxillary region with poor bone density.[25,26,27] Almog et al. used auto polymerizing resin with vacuum formed thermoplastic matrix and lead strip (2 mm) vertically on the lingual/palatal wall of the buccal access groove. The clinical results of this template were questionable as there was more error encountered in the bucco-lingual placement of implant.[28] Completely limiting design restricts, all of the instruments used for the osteotomy in a bucco-lingual and mesio-distal plane. Moreover, the addition of drill stops limits the depth of the preparation, and thus, the positioning of the prosthetic table of the implant.
When an implant placement is planned in clinically challenging cases, several surveying techniques are available, among which Computerised Tomography (CT) has been shown to be among the most precise ones [17]. The two-dimensional representation which is rendered by the printed sections, however, is a limiting factor in interpretation and surgical planning of implant treatment [13].To address this concern, computer software packages have been designed to enhance clinical implant treatment planning through reading and interpreting CT scans, performing measurements, and evaluating anatomic relationships by placing virtual images on the screen (computer aided design [CAD]). Placement of a radiographic template prior to CT scanning further enhances treatment through visualisation of the proposed prosthetic plan with respect to underlying anatomic limitations [18].
Radiographic and surgical guide templates assist in diagnosis and treatment planning and facilitate proper positioning of implants in bone. In general, the diagnostic casts and wax-up are the basis to form radiographic or surgical templates.
A radiographic template is used for imaging and is still part of the diagnostic process. The diagnostic wax-up is copied and an acrylic resin matrix is made over the occlusal part of the remaining dentition, including the future position of the implant-supported restoration. Stable positioning of the template in the mouth of the patient is mandatory. A hole is placed into the acrylic resin in line with the desired position and angulation of the implant in relation with the future restoration. The hole is filled with a radiopaque material such as a metal bar or gutta-percha. With this radiographic template a radiograph can be made to get insight in the relation between the restoration-driven position and angulation of the implant and the availability of bone and vicinity of neighbouring teeth and other anatomical structures.
A surgical guide template is used during surgery as an aid for proper positioning of the implant in the bone. There are three design concepts based on the amount of surgical restriction offered by the surgical guide templates:
This completely guided design is based on cone beam computer tomography and planning software, instead of casts and a wax-up. The template is made with computer-assisted design and manufacturing (CAD/CAM) with titanium drill-guiding tubes, providing control of position, angulation and depth.
The aim of the present study was to assess the clinical relevance of the potential mechanical error (intrinsic error) caused by the cylinder-burr gap in a 'single type' stereolithographic surgical template in implant guided surgery. 129 implants were inserted in 12 patients using 18 templates. The pre- and postoperative computed tomography (CT) scans were matched allowing comparison of the planned implants with the placed ones. Considering only the angular deviation values, the t test was used to determine the influence of the guide fixation and the arch of support on accuracy values. The Pearson correlation coefficient was used to correlate angular deviation and bone density. The intrinsic error was mathematically evaluated. t test results indicated that the use of fixing screws (P=009) and the upper arch support (P=027) resulted in better accuracy. The Pearson correlation coefficient (0.229) indicated a significant linear correlation between angular deviations and bone density (P=009). A mean intrinsic error of 2.57 was mathematically determined considering only the angular deviation, as it was not influenced by other variables. The intrinsic error is a significant factor compared to all the variables that could potentially affect the accuracy of computer-aided implant placement.
Background: Based on three-dimensional implant planning software for computed tomographic (CT) scan data, customized surgical templates and final dental prostheses could be designed to ensure high precision transfer of the implant treatment planning to the operative field and an immediate rigid splinting of the installed implants, respectively.
Purpose: The aim of the present study was to (1) evaluate a concept including a treatment planning procedure based on CT scan images and a prefabricated fixed prosthetic reconstruction for immediate function in upper jaws using a flapless surgical technique and (2) validate the universality of this concept in a prospective multicenter clinical study.
Materials and methods: Twenty-seven consecutive patients with edentulous maxillae were included. Treatments were performed according to the Teeth-in-an-Hour concept (Nobel Biocare AB, Göteborg, Sweden), which includes a CT scan-derived customized surgical template for flapless surgery and a prefabricated prosthetic suprastructure. 041b061a72