A Novel Parsimonious Method as Accurate as Extravagant Counterparts: Streolithographically-Modeled Patient-Specific Drill Guide Template for Subaxial Cervical Pedicle Screw Insertion

Background: This study was conducted to develop a modified, parsimonious, faster to produce, easier to implement, and patient-specific drill guide template and also to examine if such a modification might affect the accuracy. Methods: On two cadaveric spines, using reverse engineering, the orientation of pedicles and safe corridors for pedicle screw were determined. A drill template was designed with a surface that was the inverse of the posterior vertebral surface. The drill template was manufactured using rapid prototyping technique. To decrease the costs, the cervical spine corresponding prototypes were not manufactured. In contrary to previous studies, to preserve the stability from posterior element, the templates were designed in such a way that removing interspinous and supraspinous ligaments was not necessary. The accuracy was evaluated by computed tomography (CT) images and classified into three grades of 0: correct placement, 1: malposition by less than a half screw diameter, and 2: malposition by more than a half screw diameter. Results: Of 20 positions available, we inserted 19 screws, because the trajectory of one of the patient-specific drill guide templates was misdirected. The overall accuracy rate for cervical pedicle screw (CPS) placement was 84.2% (16 of 19). Safely inserted screws, combining the grades 0 and 1 categories, were as high as 100%. We observed no “unsafe screw placement”. Conclusions: The total cost and the latency period before the operation was reduced and the interspinous and supraspinous ligaments were preserved. A good applicability and high accuracy was obtained for subaxial CPS (SCPS) insertion.

Pedicle screw placement in spinal neurosurgery using a 3D-printed drill guide template: a systematic review and meta-analysis

Background Many surgeons believe that the use of a 3D-printed drill guide template shortens operative time and reduces intraoperative blood loss compared with those of the free-hand technique. In this study, we investigated the effects of a drill guide template on the accuracy of pedicle screw placement (the screw placed completely in the pedicle), operative time, and intraoperative blood loss. Materials/Methods We systematically searched the major databases, such as Medline via PubMed, EMBASE, Ovid, Cochrane Library, and Google Scholar, regarding the accuracy of pedicle screw placement, operative time, and intraoperative blood loss. The χ2 test and I2 statistic were used to examine heterogeneity. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to calculate the accuracy rate of pedicle screw placement, and weighted mean differences (WMDs) with 95% CIs were utilized to express operative time and intraoperative blood loss. Results This meta-analysis included 13 studies (seven randomized controlled trials and six prospective cohort studies) involving 446 patients and 3375 screws. The risk of research bias was considered moderate. Operative time (WMD = − 20.75, 95% CI − 33.20 ~ − 8.29, P = 0.001) and intraoperative blood loss (WMD = − 106.16, 95% CI − 185.35 ~ − 26.97, P = 0.009) in the thoracolumbar vertebrae, evaluated by a subgroup analysis, were significantly different between groups. The 3D-printed drill guide template has advantages over the free-hand technique and improves the accuracy of pedicle screw placement (OR = 2.88; 95% CI, 2.39~3.47; P = 0.000). Conclusion The 3D-printed drill guide template can improve the accuracy rate of pedicle screw placement, shorten operative time, and reduce intraoperative blood loss.

3D printing of drill guide template for access cavity preparation in human molars: a preliminary study

Purpose This paper aims to use cone-beam computed tomography (CBCT) and computer-aided design/3D printing technology to design and fabricate a drill guide template for access cavity preparation of permanent molars, and conduct a preliminary evaluation of its effectiveness. Design/methodology/approach CBCT scans were performed on two permanent maxillary first molars extracted due to periodontitis. Based on the scans, guide templates of access cavities were designed. The angle of the guiding cylinders was determined based on the direction of the long axis of the tooth. A 3D resin printer with high resolution was used to print the guide templates. The printed guide templates were used by a dentist with specialized clinical experience to perform access cavity preparation in a dental simulator. Then the prepared access cavities were scanned again by CBCT, and scan data were compared to the design data. Findings The 3D printed drill guide template had a close fit with the extracted tooth fit. The access cavity prepared using the guide template enabled the removal of the pulp chamber roof, and formed a straight-line access. Points were selected for measurement at regularly spaced intervals of 0.5 mm along the side wall of the access cavity. The mean deviation between the actual access cavities of the two permanent maxillary first molars and the designed cavities was less than 0.1 mm, with a maximum deviation of about 0.5 mm, showing a good conformance between the actual cavity and the designed cavity. Originality/value A drill guide template was designed and fabricated by 3D printing technology, which easily guided burs to complete the access cavity preparation work forming an ideal cavity shape with satisfying accuracy, and thus may reduce the complications during pulp chamber entry.