A Prospective Study on the Accuracy of Mucosally Supported Stereolithographic Surgical Guides in Fully Edentulous Maxillae

Background: Flapless implant placement using guided surgery is widespread, although clinical publications on the precision are lacking. Purpose: The purpose of this study was to evaluate the accuracy of mucosal‐supported stereolithographic guides in the edentulous maxillae. Materials and Methods: Seventy‐eight OsseoSpeed? implants (Astra Tech AB, Mölndal, Sweden) of 3.5 to 5 mm width and 8 to 15 mm length were installed consecutively in 13 patients. Implants were functionally loaded on the day of surgery, and implant location was assessed with a computed tomography scan. Mimics 9.0 software (Materialise N.V., Leuven, Belgium) was used to fuse the images of the virtually planned and actually placed implants, and the locations, axes, and interimplant distances were compared. Results: One implant was lost shortly after insertion because of abscess formation caused by remnants of impression material. Seventy‐seven implant locations were analyzed. The deviation at the entrance point ranged between 0.29 mm and 2.45 mm (SD: 0.44 mm), with a mean of 0.91 mm. Average angle deviation was 2.60° (range 0.16–8.86°; SD: 1.61°). At the apical point, the deviation ranged between 0.32 mm and 3.01 mm, with a mean of 1.13 mm (SD: 0.52 mm). The mean deviation of the coronal and apical interimplant distance was respectively 0.18 mm (range 0.07–0.32 mm; SD: 0.15) and 0.33 mm (range 0.12–0.69 mm; SD: 0.28). These deviations are lower than the global coronal and apical deviations. Conclusion: The present study is the first to investigate the accuracy of stereolithographic, full, mucosally supported surgical guides in the treatment of fully edentulous maxillae. Clinicians should be warned that angular and linear deviations are to be expected. Short implants show significantly lower apical deviations compared with longer ones. Reasons for implant deviations are multifactorial; however, it is unlikely that the production process of the guide has a major impact on the total accuracy of a mucosal‐supported stereolithographic guide.     

Accuracy and Complications Using Computer‐Designed Stereolithographic Surgical Guides for Oral Rehabilitation by Means of Dental Implants: A Review of the Literature

Background: In the last decade several stereolithographic guided surgery systems were introduced to the market. In this context, scientific information regarding accuracy of implant placement and surgical and prosthodontical complications is highly relevant as it provides evidence to implement this surgical technique in a clinical setting. Purpose: To review data on accuracy and surgical and prosthodontical complications using stereolithographical surgical guides for implant rehabilitation. Material and Methods: PubMed database was searched using the following keywords: “three dimensional imaging,”“image based surgery,”“flapless guided surgery,”“customized drill guides,”“computer assisted surgery,”“surgical template,” and “stereolithography.” Only papers in English were selected. Additional references found through reading of selected papers completed the list. Results: In total 31 papers were selected. Ten reported deviations between the preoperative implant planning and the postoperative implant locations. One in vitro study reported a mean apical deviation of 1.0 mm, three ex vivo studies a mean apical deviation ranging between 0.6 and 1.2 mm. In six in vivo studies an apical deviation between 0.95 and 4.5 mm was found. Six papers reported on complications mounting to 42% of the cases when stereolithographic guided surgery was combined with immediate loading. Conclusion: Substantial deviations in three‐dimensional directions are found between virtual planning and actually obtained implant position. This finding and additionally reported postsurgical complications leads to the conclusion that care should be taken whenever applying this technique on a routine basis.     

Accuracy of Two Stereolithographic Surgical Templates: A Retrospective Study

Background: The use of computer software and stereolithography for dental implant therapy has significantly increased during the last few years. The aim of this study was to evaluate and compare the mean accuracy and maximum deviations values of dental implant placement using two stereolithographic (SLA) guide systems. Materials and Methods: Twenty patients were selected and 227 implants were inserted using bone‐, tooth‐ and mucosa‐supported SLA surgical guides. Thirty‐one guides, both single‐ and multiple‐type, were used. Some of the single‐type surgical guides were fixed with osteosynthesis screws. A postoperative computer tomography (CT) was performed and an iterative closest point algorithm was used to match the jaw of the CT preoperative with the jaw of the postoperative CT. Quantitative data of each group were described. The t‐test was used to determine the influence of the utilization of the different types of SLA on accuracy values. Results: t‐Test demonstrated a better accuracy of the multiple‐type guides in almost all deviation values when the mucosa‐supported guides were considered. Regarding the bone‐supported template, the single‐type fixed group showed a better accuracy while the highest values of deviation were registered by the multiple‐type guides. The single‐type group showed a better accuracy when the tooth support was considered. Conclusions: The results of the present study indicated best accuracy of the single‐type guide using a bone or tooth support. The multiple‐type guide recorded the best accuracy data when the mucosa support was considered comparing either a fixed and a not‐fixed single‐type guide.     

Three‐Dimensional Accuracy of Guided Implant Placement: Indirect Assessment of Clinical Outcomes

Purpose: Precise preoperative implant planning and its exact intraoperative transfer are crucial for successful implant‐supported rehabilitation of partially or completely edentulous patients. In the present pilot study, optical laser scanning was used to evaluate deviations between three‐dimensonal computer‐assisted planned and actual implant positions by indirect methods. Material and Methods: Five patients receiving a total of 15 implants were included in this study. The used planning software was SimPlant 12.0 (Materialise Dental, Leuven, Belgium) to visualize the implant positions, and with an appropriate guided surgery protocol (Navigator?, Biomet 3i, Palm Beach Gardens, FL, USA) implant positions were implemented via tooth‐supported stereolithografic surgical guides. All implants (Osseotite?, Biomet 3i) were inserted in a flapless approach and immediately provided with prefabricated temporary splinted restorations. Intraoral pickup impressions were taken postoperatively, and the implant positions of the master casts were compared with presurgical casts. Implant replica deviations were evaluated by three‐dimensional optical laser scanning providing distances and angulations between implant replicas. Results: Overall, the postsurgical implant replica positions were found to deviate from the positions in the preoperative cast by a mean of 0.46 ± 0.21 mm (range: 0.09–0.85 mm). Positional deviations were 0.27 ± 0.19 mm (range: 0.04–0.60 mm) along the x‐axis representing the buccal‐lingual directions, 0.15 ± 0.13 mm (range: 0.0–0.34 mm) along the y‐axis representing the ventrodorsal direction, and 0.28 ± 0.19 mm (range: 0.02–0.59 mm) along the z‐axis representing cranial and apical directions. Rotational deviations amounted to 14.04 ± 11.6° (range: 0.09–36.47°). Conclusions: The results of this pilot study demonstrate precise transfer of implant replica position by means of simulated guided implant insertion into a preoperative cast and a postoperative cast obtained from impressioning. Further studies are needed to identify appropriate evaluation techniques and mechanisms to increase the transfer precision of three‐dimensional planning and guiding systems.     

Use of Stereolithographic Templates for Surgical and Prosthodontic Implant Planning and Placement. Part I. The Concept

Surgical and prosthodontic implant complications are often an inadvertent sequelae of improper diagnosis, planning, and placement. These complications pose a significant challenge in implant dentistry. Presented in this article is a technique using a highly advanced software program along with a rapid prototyping technology called stereolithography. It permits graphic and complex 3D implant simulation and the fabrication of computer-generated surgical templates. These templates seat directly on the bone and are preprogrammed with the individual depth, angulation, and mesio-distal and bucco-lingual positioning of individual implants as planned during the 3D computer simulation.     

Use of Stereolithographic Templates for Surgical and Prosthodontic Implant Planning and Placement. Part II. A Clinical Report

Eight implants were placed in the posterior part of the mandible using computer-generated stereolithographic templates. Preoperative implant simulation was done on a 3D computer model created by reformatted computerized tomography data. The surgeon and the prosthodontist positioned the simulated implants in the most favorable position addressing all concerns with regard to anatomy, biomechanics, and esthetics. The length and diameter of each implant along with the angulation/collar of abutments required for a screw-retained prosthesis were determined. Stereolithographic templates were then fabricated by incorporating the precise spatial position of the implants within the bone as previously planned during the computer simulation. The templates were fabricated to seat directly on the bone and were stable. The first template was used to complete osteotomies with a 2-mm twist drill followed by the second template for the 3-mm drill. Implants were placed and allowed to integrate for 4 months. After second-stage surgery, the definitive abutments were torqued into place followed by insertion of the definitive screw-retained prostheses. Dimensions of all implants and abutments were the same as planned during the computer simulation.     

Bone and Skin-Supported Stereolithographic Surgical Guides for Cranio-Facial Implant Placement

Purpose

Osseointegrated skin-penetrating implants enhance the retention and stability of the craniofacial prostheses and provide the long-term comfort. However, to determine the implant locations is a great challenge facing the surgeon. Implants may either be located in conventional manner or by STL generated surgical guides.

Materials and Methods

Present study reports the CT based 3D virtual modeling, preoperative virtual planning and the implant placement by using a STL surgical guide, in an anotia case.

Results

Employed materials and the methods facilitated the implant surgery while improving the operational security.

Conclusions

CT based 3D virtual modeling of the surgical site, determining the implant locations virtually and the STL guided placement of the craniofacial implants, were found useful applications in order to facilitating the surgical intervention and providing prevention from complications.

     

Accuracy of Virtually Planned and Template Guided Implant Surgery on Edentate Patients

Purpose: Scientific evidence regarding the accuracy of implants placed into patients by the aid of a surgical template is limited. The objective of the present study was to verify if any variation exists between virtually planned implants' position using a computer, compared with the subsequently clinically placed implants with the aid of a surgical template in the mandible and the maxilla. Material and Methods: A total number of 25 edentate jaws were treated with the aid of a surgical template. In total, 139 implants were inserted. Fifty implants were inserted in the mandible and 89 in the maxilla. A voxel‐based registration method was used to match two separate cone‐beam computed tomography scans of the patients. The implant positions were calculated and compared between the planned implants and the implants' clinical position after more than 1 year after surgery. The results included the linear differences in distance at the level of the hex, the apex, and the depth. The angular differences were presented in degrees. Results: Statistical results indicated some factors with significant deviations. The greatest errors were found when comparing between patients moving during the computed tomography scans and those that did not move. The results showed significant divergence at the level of the hex and apex of the implants. Conclusion: The hypothesis was rejected, as the statistical results indicated that there were significant differences between virtually planned implants' position and the final position of implants placed clinically.     

Conventional Multi‐Slice Computed Tomography (CT) and Cone‐Beam CT (CBCT) for Computer‐Aided Implant Placement. Part II: Reliability of Mucosa‐Supported Stereolithographic Guides

Purpose: Deviations of implants that were placed by conventional computed tomography (CT)‐ or cone beam CT (CBCT)‐derived mucosa‐supported stereolithographic (SLA) surgical guides were analyzed in this study. Materials and Methods: Eleven patients were randomly scanned by a multi‐slice CT (CT group) or a CBCT scanner (CBCT group). A total of 108 implants were planned on the software and placed using SLA guides. A new CT or CBCT scan was obtained and merged with the planning data to identify the deviations between the planned and placed implants. Results were analyzed by Mann‐Whitney U test and multiple regressions (p < .05). Results: Mean angular and linear deviations in the CT group were 3.30° (SD 0.36), and 0.75 (SD 0.32) and 0.80 mm (SD 0.35) at the implant shoulder and tip, respectively. In the CBCT group, mean angular and linear deviations were 3.47° (SD 0.37), and 0.81 (SD 0.32) and 0.87 mm (SD 0.32) at the implant shoulder and tip, respectively. No statistically significant differences were detected between the CT and CBCT groups (p = .169 and p = .551, p = .113 for angular and linear deviations, respectively). Conclusions: Implant placement via CT‐ or CBCT‐derived mucosa‐supported SLA guides yielded similar deviation values. Results should be confirmed on alternative CBCT scanners.     

Influence of Metal Guide Sleeves on the Accuracy and Precision of Dental Implant Placement Using Guided Implant Surgery: An In Vitro Study

Purpose

Metal sleeves are commonly used in implant guides for guided surgery. Cost and sleeve specification limit the applications. This in vitro study examined the differences in the implant position deviations produced by a digitally designed surgical guide with no metal sleeve in comparison to a conventional one with a metal sleeve.

Materials and Methods

The experiment was conducted in two steps for each step: n = 20 casts total, 10 casts each group; Step 1 to examine one guide from each group with ten implant placements in a dental cast, and Step 2 to examine one guide to one cast. Implant placement was performed using a guided surgical protocol. Postoperative cone-beam computed tomography images were made and were superimposed onto the treatment-planning images. The implant horizontal and angulation deviations from the planned position were measured and analyzed using t-test and F-test (p = 0.05).

Results

For Step 1 and 2, respectively, implant deviations for the surgical guide with sleeve were –0.3 ±0.17 mm and 0.15 ±0.23 mm mesially, 0.60 ±1.69 mm, and –1.50 ±0.99 mm buccolingual at the apex, 0.20 ±0.47 mm and –0.60 ±0.27 mm buccolingual at the cervical, and 2.73° ±4.80° and –1.49° ±2.91° in the buccolingual angulation. For Step 1 and 2, respectively, the implant deviations for the surgical guide without sleeve were –0.17 ±0.14 mm and –0.06 ±0.07 mm mesially, 0.35 ±1.04 mm and –1.619 ±1.03 mm buccolingual at the apex, 0.10 ±0.27 mm and –0.62 ±0.27 mm buccolingual at the cervical, and 1.73° ±3.66° and –1.64° ±2.26° in the buccolingual angulation. No statistically significant differences were found in any group except for mesial deviation of the Step 2 group (F-test, p < 0.001).

Conclusions

A digitally designed surgical guide with no metal sleeve demonstrates similar accuracy but higher precision compared to a surgical guide with a metal sleeve. Metal sleeves may not be required for guided surgery.     

Influence of Thread Design on Implant Positioning in Immediate Implant Placement

Background: It is generally believed that implants placed in extraction sockets have a tendency to shift in the facial direction during insertion. The purpose of this study is to investigate the effect of different thread designs on the final implant position in immediate implant placement. Methods: In a split‐mouth design involving 11 cadaver heads, each specimen received two implants, one with a square and one with a V‐shaped thread design, in maxillary incisor extraction sockets. The facio‐lingual locations of the drills and the implant were tracked, and the displacements were compared between the two groups. Results: No statistically significant differences were observed between the square and V‐shaped thread design groups. The mean displacements of the different groups showed a general tendency of the implants to be positioned facially compared with the initial drill trajectory. This tendency was greater for implants with square thread design. Conclusion: There was no significant effect of implant thread design on the positioning of implants in extraction sockets.