Loma Linda Guide: A Stereolithographically Designed Surgical Template: Technique Paper

The first surgical template was developed for the surgical reduction of the maxillary tuberosities.1,2 Surgical guides have been used in dentistry since the early 1980s for the fabrication of subperiosteal dental implants using stereolithiography.3 Truitt and James3 first used stereolithographic models at Loma Linda University for the design and fabrication of subperiosteal implants. Stereolithographic techniques are now gaining great popularity in implant dentistry, being widely used to generate models which replicate the anatomy of the patients' jaws. Dental implant surgical templates assist in the correct directional orientation of the osteotomy preparation and thus aid in the correct fixture placement.4,5 Stereolithographic 3-D models can be very helpful in conjunction with Cone Bean Computerized Tomographic (CBCT) scans25,26 for the treatment planning and preoperative assessment. These technologies have facilitated presurgical implant site evaluation of the patients' jaws making implant dentistry more predictable.25–32 Flapless surgery is becoming increasingly popular; it can present a number of benefits for the patient by having a less invasive procedure that can minimize postoperative complications such as discomfort and inflammation and lead to a more positive experience for the patient. This alternative procedure can be very challenging and careful case selection is of utmost importance.30–32 This paper presents an alternative procedure of developing a surgical template created in the dental laboratory using a CBCT scan, the patients' own denture, and stereolithographic model.

1. At the first appointment, a complete oral evaluation and diagnostic work-up is required.

2. Check the patients' existing prosthesis. If it is deemed inadequate, proceed in fabricating a new prosthesis for the patient.

3. The new denture should closely replicate the final prosthetic design, both functionally and esthetically. This will facilitate the planning of prosthetically guided implant placement.

4. The first CBCT scan is made with the patient wearing the prosthesis (ICAT ISI, Hatfield, Pa). Prior to scanning the denture is modified with gutta-percha markers, a minimum of six indentations are made to a 1-mm depth and width using a round bur, these are then obturated with gutta-percha. A second scan is made of the prosthesis alone, with the occlusal plane parallel to the horizon. All images that are generated from the CBCT scan must be stored in a Digital Communication in Medicine (DICOM) format. These files are then sent to a stereolithographic modeling company to be processed for the fabrication of a 3-D stereolithiographic acrylic-resin model. The 3-D model (Medical Modeling LLC, Golden, Colo) is a replica of the patient's jaw that can include a duplicate denture and gingival tissue.

5. Verify that the three components fit properly without any discrepancies. Place markings with a pen or pencil where the implants will be placed (Figure 3). Check the angulations and direction of the implants; any correction should be done at this moment before starting to drill on the 3-D model (Figures 1 and 2).

6. Start drilling the osteotomies in the dental laboratory using the low speed micro-motor (DLT50K laboratory micro-motor, Brassler, Savannah, Ga) using old/used surgical drills (Steri-Oss, Nobel Biocare, Yorba Linda, Calif) (Figures 3 and 4).

7. Insert the implants using the manual torque wrench and implant mount, those that were used for this case were from Nobel Biocare (Nobel Biocare). Short closed-tray impression posts are used to hold the implants in the correct position, while fixating them into the 3-D model osteotomies with clear acrylic splint resin (Great Lakes, Wis) (Figures 5 and 6).

8. Apply the splint resin using a 30-mL plastic syringe (Monoject, Kendall, Mansfield, Mass) and place the 3-D model in the thermo-curing pressure pot (GC, Alsip, Ill) with warm water at 20 psi for 15 minutes according to the manufacturer's instructions (Figure 7).

9. Place the cover screws (Nobel Biocare) and place polyvinylsiloxane paste (Fit-Checker, GC Japan Inc, Tokyo, Japan) to locate and drill through the duplicate stereolitographic denture (Figures 8 and 9).

10. Trim any excess with an acrylic bur (Brassler, Savannah, Ga). Then drill through the duplicate denture in locations coincident with the impression copings. This will facilitate placement of the duplicate denture over the copings and in intimate contact with the 3-D model.

11. Adjust the template (duplicate of the stereolithographic denture) verifying that the surgical sleeves (Medical Modeling LLC) fit accurately. Position them and apply resin to stabilize them. Then, place the 3-D model in the thermo-curing pressure pot with warm water for 15 minutes (Figure 10).

12. After 15 minutes trim any excess with the acrylic burs on the occlusal access of the template. Add two buccal holes to aid in anchoring the template with 9-mm titanium screws and one mid-palatal 5-mm titanium screw (Ace Surgical, Ontario, Calif) to have a 3-point fixation at the time of surgery (Figures 11 and 12).

13. Take the duplicate denture surgical template and polish at slow speed lathe (Baldor, Fort Smith, Ark) using a small rag wheel (Pearson, Calif) and polishing powder (Resilence, KERR, Romulous, Wis) (Figures 13 through 15).

14. Use the steam cleaner to remove any residue of the polishing material (Bar Instruments, Newberry Park, Calif).

15. At the time of surgery use additional instrumentation to aid the preparation of the osteotomies in the patient using surgical guide custom tools (Medical Modeling LLC) (Figure 16). Store the template in a plastic bag (Ziploc, Racine, Wis) with sterile saline to maintain the hydration of the template and thereby prevent distortion (Figure 17).

Truitt and James used stereolithographic 3-D models at Loma Linda University for the planning and development of subperiosteal implants.3 They pioneered an innovative accurate technique for the reproduction of the patients' jaws that is now used by many companies for dental and maxillofacial purposes. The use of CBCT has the potential to be an accurate, noninvasive practical method to reliably determine osseous topography.27,33 It has the additional advantage of reduced radiation exposure for the patient versus conventional medical-grade computerized tomography.

The use of CBCT in preoperative planning facilitates identification of important anatomical features. These include tracing of the inferior alveolar canal, location of mental foramina, and maxillary sinus topography. Together with a radiographic template generated from a duplicate of the final prosthetic design, accurate 3-D implant placement can be planned. This will ultimately lead to a successful treatment outcome for the patient and minimize the possibility of intra- and postoperative complications.23,24 As highlighted in our technique paper, the subsequent fabrication of a prosthetically driven treatment plan and surgical guide can then simplify the execution of treatment.

Following the diligent planning and fabrication of the surgical guide, flapless surgery allows for less postoperative discomfort and an accelerated soft tissue healing phase.

The accuracy of utilizing the 3-D models in preparation for the surgery in implant dentistry is very advantageous. The case can be planned and prepared by simulating a mock surgery to adjust angulations and prevent any surgical complications that may compromise the prosthetic outcome of treatment. The use of CBCT technology is now a standard of care for diagnosis and treatment planning in implant dentistry, though due diligence must be ensured in order to avoid excessive radiation exposure for our patients. Communication and teamwork between the restorative dentist and surgeon are critical through all phases of planning and execution of treatment. With thorough planning, we have the ability to treat our patients using state of the art technology to reduce treatment complications, minimize postoperative discomfort and reduce treatment times.

The Advanced Education Program in Implant Dentistry, at Loma Linda University, Loma Linda, California supported the publication of this article. We would like to also thank Marsha Booner (Medical Modeling LLC, Golden, Colo) for the delivery of the 3-D models and instruments for the completion of this project.