To evaluate the three-dimensional (3D) stability and accuracy of additively manufactured surgical templates fabricated using two different 3D printers and materials.
Forty surgical templates were designed and printed using two different 3D printers: the resin group (n = 20) used a digital light processing (DLP) 3D printer with photopolymer resin, and the metal group (n = 20) employed a selective laser melting (SLM) 3D printer with titanium alloy. All surgical templates were scanned immediately after production and re-digitalized after one month of storage. Similarly, the implant simulations were performed twice. Three-dimensional congruency between the original design and the manufactured surgical templates was quantified using the root mean square (RMS), and the definitive and planned implant positions were determined and compared.
At the postproduction stage, the metal templates exhibited higher accuracy than the resin templates (p < 0.001), and these differences persisted after one month of storage (p < 0.001). The resin templates demonstrated a significant decrease in three-dimensional stability after one month of storage (p < 0.001), whereas the metal templates were not affected (p > 0.05). No significant differences in implant accuracy were found between the two groups. However, the resin templates showed a significant increase in apical and angular deviations after one month of storage (p < 0.001), whereas the metal templates were not affected (p > 0.05).
Printed metal templates showed higher fabrication accuracy than printed resin templates. The three-dimensional stability and implant accuracy of printed metal templates remained unaffected by one month of storage.
With superior three-dimensional stability and acceptable implant accuracy, printed metal templates can be considered a viable alternative technique for guided surgery.

暂无摘要。

OBJECTIVE: The surgical procedure of bony impacted supernumerary teeth (SNT) in hard palate is commonly done with poor visualization and uncomfortable posture. This study aims to introduce our primary practice of presurgical evaluation and guiding exodontia of bony impacted supernumerary teeth (SNT) in the hard palate to reduce surgical trauma, duration and uncertainty.
METHODS: Twelve patients with impacted supernumerary teeth in hard palate were included. Intraoral scan and the three-dimensional (3D) reconstruction of the cone beam computed tomography (CBCT) file was superimposed, and virtual simulation of flap elevation and osteotomy was conducted on the rebuilt 3D model. A couple of surgical templates were designed with surgical planning software Mimics, fabricated by a 3D printer and were used to guide the extraction of the impacted SNT.
RESULTS: The surgical templates fitted well to the teeth and operation site. All the impacted SNTs were accurately located and extracted without damaging the adjacent vital anatomical structures. All patients had an uneventful postoperative recovery without infection or sensory disturbance.
CONCLUSIONS: The application of 3D printed surgical templates reduced trauma and increased the accuracy and predictability of surgical extraction of bony impacted SNT in hard palate. The results of this study increased the accuracy and predictability of surgical extraction of bony impacted SNT in hard palate, and reduced the surgeon\'s embarrassment and surgical trauma because of location difficulty.

Segmental Le Fort I surgery is an effective technique to correct complicated dentomaxillofacial deformities. This retrospective study evaluated the accuracy of segmental Le Fort I surgery under the guidance of virtual surgical planning (VSP). A total of 129 patients who accepted segmental Le Fort I surgery were investigated in this study. VSP was transferred to segmental surgery with different pieces precisely with the aid of 3D-printed surgical templates and splints. The surgical result was evaluated by postoperative complications, color distance maps, and quantitative accuracy analysis. Outcomes showed that the VSP was successfully transferred to actual surgery with high accuracy. The overall mean linear difference was 1.28 mm, and the overall mean angular difference was 2.4°. Except for one case of root injury, there was no serious complication recorded. The results suggested that VSP was a reliable assistance for segmental Le Fort I surgery.

OBJECTIVE: To evaluate the influence of crown coverage of surgical guides on the accuracy of static computer-assisted implant surgeries (sCAISs) in different partially edentulous situations.
METHODS: Acrylic models with five types of partially edentulous situations were fabricated in this study. In coDiagnostiX software (Dental Wings, Montreal, Canada), surgical templates were designed and fabricated with reduced crown coverage (RCC), standard crown coverage (SCC) and extended crown coverage (ECC). Then, fully guided implant placement into the acrylic models was performed by dental surgeons with more than 10 years of experience. In total, 120 models and 120 guides were manufactured, and 168 bone-level Straumann replica implants (4.1 × 10 mm, Institut Straumann AG, Basel, Switzerland) were inserted. Postoperative implant positions were scanned (Trios 3, 3 shape, Copenhagen, Denmark) and compared with the preplanned virtual positions via coDiagnostiX (Dental Wings, Montreal, Canada). The angular, coronal and apical deviations were measured and analyzed to evaluate the accuracy of implant insertion. Statistical analysis was performed using one-way ANOVA and Tukey\'s test.
RESULTS: For single tooth missing situations, the RCC group was similar to the SCC group and ECC group in anterior sites. In premolar or molar sites, the SCC and ECC groups had no statistically significant difference (p > .05), while the RCC group had more coronal and apical deviation (p < .05). For multiple teeth missing situations, there was no difference among the RCC, SCC and ECC groups (p > .05). No difference was found among the five edentulous situations with different CCs (p > .05).
CONCLUSIONS: The CC of templates can significantly affect the accuracy of guided surgeries when implants are inserted in a single gap at posterior sites. Templates with CC extended to the undercut line may be an optimal choice for static guided surgeries.
CONCLUSIONS: The accuracy of static guided implant surgery can be influenced by the CC of templates, and proper CC with the guide covering extending to the undercut line may contribute to improved accuracy. CC should be taken into consideration when designing surgical templates.

Although guided implant surgery is widely practiced, clinical studies examining the differences in accuracy between implanting systems that use the same surgical guide are currently lacking. This study aimed to evaluate and compare the effects of different dental implanting systems on positioning accuracy using a uniform type of stereolithographic surgical guide to account for cumulative errors in guide production. One hundred BEGO Semados® S implants (Group A) and ninety-one NobelActive® implants (Group B) were inserted into patients using the same type of guide. The accuracy was assessed by matching the preoperative and postoperative cone-beam computed tomography (CBCT). The implant shoulder, tip, depth and angular deviation were registered. Statistically significant differences between groups were  determined using student\'s t-test, bivariate correlation test and generalized estimating equation. The angular deviation was 3.16±1.74° in Group A and 2.58±1.41° in Group B (P=0.013 ); the depth deviation was 0.44±0.23mm in GroupA and 0.51±0.22mm in Group B (P=0.032). In terms of vertical accuracy, the Bego implant system is superior to the Nobel implant system using the same type of surgical guide, while the angle accuracy is opposite. Therefore, it is important to control the depth when using the template guided surgery in Nobel implant system. Similarly, angle control should be emphasized in Bego implant system. Measurements of the deviations provide the basis for a clinical reference that will be useful in preoperative analysis for improvement of the safety and accuracy of guided implant surgical procedures.

BACKGROUND: The patient-specific templates for osteotomy often have complex surface features. Using current commercial software to design such templates is quite complicated, tedious and unrepeatable.
OBJECTIVE: In this study, a novel surgical planning system for oral and maxillofacial surgery named EasyTemplate is developed, aiming to help doctors shorten the modelling time and assure the reliability in template design.
METHODS: In the simplified design process of an osteotomy guide, the main template can be formed efficiently using a surface offsetting algorithm, which is based on isosurface extraction and oriented bounding box. Thereafter, the cutting grooves can be generated automatically.
RESULTS: A complicated surgical guide could be built accurately in about 10 min. Clinical orthognathic cases were conducted successfully using osteotomy and repositioning templates designed by EasyTemplate.
CONCLUSIONS: Compared with commercially available softwares, higher efficiency and simpler design process were achieved, moreover, the time cost is one-third or even less.
CONCLUSIONS: EasyTemplate can be a useful alternative to traditional softwares. This software allows the auto-generation algorithm which helps avoid a tedious modeling process while providing basic shapes for designers.

To evaluate the accuracy of a computer numerical control (CNC) milled surgical guide for implant placement in edentulous jaws.
Edentulous patients seeking implants treatment were recruited in this prospective cohort study. Radiographic guides with diagnostic templates were fabricated from wax-up dentures. Patients took cone-beam computed tomography (CBCT) wearing the radiopaque radiographic guides. Implant positions were virtually designed in the planning software based on the CBCT data, and the radiographic templates were converted into surgical guides using CNC milling technique. Forty-four implants were placed into 12 edentulous jaws following guided implant surgery protocol. Post-surgery CBCT scans were made for each jaw, and the deviations between the planned and actual implant positions were measured. Deviation of implant position was compared between maxilla and mandible, and between cases with and without anchor pins using independent t-test.
Nine patients (3 males and 6 females) with 12 edentulous jaws were recruited. The mean age of patients was 59.2 ± 13.9 years old. All 44 implants was placed without complication and survived, the mean three dimensional linear deviation of implant position between virtual planning and actual placement was 1.53 ± 0.48 mm at the implant neck and 1.58 ± 0.49 mm at the apex. The angular deviation was 3.96 ± 3.05 degrees. No significant difference was found in the deviation of implant position between maxilla and mandible (P = 0.28 at neck, 0.08 at apex), nor between cases with and without anchor pins (P = 0.87 at neck, 0.06 at apex).
The guides fabricated using the CNC milling technique provided comparable accuracy as those fabricated by Stereolithography. The displacement of the guides on edentulous arch might be the main contributing factor of deviation.
Chinese Clinical Trial Registry, ChiCTR-ONC-17014159 (July 26, 2017).

Computer-aided design/computer-aided manufacturing (CAD/CAM) surgical templates allow precise mandibular reconstructive surgery. However, their clinical accuracy is limited by manual plate bending. Digitally hydroformed plates maintain a digital workstream in virtual planning.
Twelve patients with Brown\'s class IIc mandibular defects were randomized into two groups: group I (experimental), the reconstruction plate was digitally hydroformed, and group II (control), surgeries were performed CAD/CAM guided with the reconstruction plate manually prebent. The linear and angular deviations of reconstruction outcomes were compared to surgical simulation in both groups.
The mean linear and angular deviations of middle and posterior segments were 2.14 ± 0.79 mm, 3.71 ± 0.95 mm, 8.73° ± 1.91°, and 9.06° ± 0.96° in group I and 4.31 ± 0.78 mm, 6.74 ± 1.40 mm, 16.35° ± 0.72°, and 31.48° ± 3.38° in group II, respectively. Measurements in group I were significantly lower than group II (P < .005).
Digital hydroforming for plate prebent is a reliable method that helps improving the clinical accuracy of CAD/CAM-guided mandibular reconstruction surgery.

BACKGROUND: Mandibular angle ostectomy (MAO) is a standard approach in reconstruction of facial contour that is commonly used in East Asian patients with prominent mandibular angles (PMA). MAO is commonly performed via an intraoral approach to reduce scar visibility and risk of facial nerve injury. Since this intraoral approach for MAO has limited visual guidance during the procedure, plastic surgeons often perform the operation based on personal clinical experience. Therefore, we designed a 3D digital ostectomy template (DOT) for guidance during surgery to improve the accuracy and safety of MAO.
METHODS: 10 female patients (average age 25.3 years) with PMA were enrolled in this study from August 2014 to October 2015. The DOTs were designed and printed preoperatively and utilized in the operation to guide the osteotomy. The excised mandibular angle bone and the DOTs were measured respective to each other. The data were analyzed to verify the feasibility and safety of the DOT.
RESULTS: All of the patients were satisfied with the surgical results, and no complications such as fracture, hemorrhage and infection occurred. The distance from gonion (Go) along inferior margin of mandible forward to the distal end of the excised bone is \"a\". The distance from Go along posterior margin of ramus upward to the distal end of the excised bone is \"b\". The widest distance from Go to the ostectomy line is denoted by \"c\". Similarly, the corresponding distance in the DOT is denoted by \"a\'\", \"b\'\", \"c\'\". The statistical results showed that left a vs a\', b vs b\', c vs c\' was 63.27 ± 6.39 mm vs 62.97 ± 6.30 mm (p > 0.05), 23.98 ± 2.25 mm vs 21.83 ± 2.27 mm (p < 0.05), 13.58 ± 2.24 mm vs 13.37 ± 2.14 mm (p > 0.05), respectively. The right a vs a\', b vs b\', c vs c\' was 62.92 ± 5.00 mm vs 62.72 ± 4.99 mm (p > 0.05), 24.03 ± 1.88 mm vs 21.80 ± 1.91 mm (p < 0.05), 13.36 ± 1.70 mm vs 13.22 ± 1.72 mm (p > 0.05), respectively. The results indicate a significant difference between b and b\' both on the right and left sides.
CONCLUSIONS: Through the application of DOT in MAO, the accuracy and safety of the operation were improved significantly. Unfortunately, the osteotomy could not be guided well in the posterior rim of the ramus. Further improvements in the surgical template are needed for application in PMA associated with oversized chin deformity or in PMA associated with large mandibular angle and severe involution.