Accuracy and complications using computer-designed stereolithographic surgical guides for oral rehabilitation by means of dental implants: a review of the literature

Accuracy of a newly developed cone-beam computerized tomography-aided surgical guidance system for dental implant placement: an ex vivo study

The aim of the present study was to measure the accuracy of the cone-beam computerized tomography (CBCT)- aided StentCad Beyond surgical guidance system and to compare bone-supported and tooth/bone-supported guidance by using this system in dental implant placement ex vivo. Five cadaver mandibles were scanned using an Iluma CBCT scanner. After scanning, DICOM slices were transferred to the StentCad Beyond implant simulation software, which was used for preoperative implant planning. Using the StentCad Beyond guidance system, 9 implant drills were inserted using a bone-supported guidance system and 11 using a tooth/bone-supported guidance system. Mandibles were scanned again and these data were transferred to the StentCad Beyond software. Pre- and postoperative information was superimposed using the Rhinoceros version 4 software program, and deviations between planned and actual drill positions were calculated for each implant. In addition, differences between bone-supported and tooth/bone-supported guidance systems were analyzed by t-test, with a significance level of P < .05. Data analysis found a mean coronal deviation of 1.2 ± 0.3 mm and 0.6 ± 0.6 mm, mean apical deviation of 1.3 ± 0.6 mm and 0.7 ± 0.6 mm, mean apical and coronal depth deviation of 1.4 ± 0.3 mm and 1.3 ± 0.3 mm, and mean angular deviation of 4.2° ± 2.0° and 3.0° ± 1.5° for tooth/bone supported and bone-supported guides, respectively. No statistical differences were found in depth or angular deviations between groups (P > .05); however, statistically significant differences between groups were found in mean horizontal coronal deviation (P = .016) and mean horizontal apical deviation (P = .047). The StentCad Beyond system was found to be a reliable guide for placing implants ex vivo.

A clinically relevant validation method for implant placement after virtual planning

PURPOSE

To design a relevant method to compare the virtual planned implant position to the ultimately achieved implant position and to evaluate, in case of discrepancy, the cause for this.

MATERIALS AND METHODS

Five consecutive edentulous patients with retention problems of the upper denture received four implants in the maxilla. Preoperatively, first a cone-beam CT (CBCT) scan was acquired, followed by virtual implant planning. Then, a surgical template was designed and endosseous implants were flapless installed using the template as a guide. To inventory any differences in position, the postoperative CBCT scan was matched to the preoperative scan. The accuracy of implant placement was validated three-dimensionally (3D) and the Implant Position Orthogonal Projection (IPOP) validation method was applied to project the results to a bucco-lingual and mesio-distal plane. Subsequently, errors introduced by virtual planning, surgical instruments, and validation process were evaluated.

RESULTS

The bucco-lingual deviations were less obvious than mesio-distal deviations. A maximum linear tip deviation of 2.84 mm, shoulder deviation of 2.42 mm, and angular deviation of 3.41° were calculated in mesio-distal direction. Deviations included errors in planning software (maximum 0.15 mm), for surgical procedure (maximum 2.94°), and validation process (maximum 0.10 mm).

CONCLUSIONS

This study provides the IPOP validation method as an accurate method to evaluate implant positions and to elucidate inaccuracies in virtual implant planning systems.

Guided surgery for implant therapy

New three-dimensional diagnostic and treatment planning technologies in implant dentistry have expanded on concepts of a team approach to the planning and placement of dental implants. The accurate and predictable placement of implants according to a computer-generated virtual treatment plan is now a reality, taking the virtual plan from the computer to the patient clinically. Recent advances in three-dimensional imaging in dentistry, in combination with the introduction of third-party proprietary implant planning software and associated surgical instrumentation, have revolutionized dental implant diagnosis and treatment and created an interdisciplinary environment in which communication leads to better patient care and outcomes.

Factors influencing transfer accuracy of cone beam CT-derived template-based implant placement

OBJECTIVES

The aim of the present investigation was the analysis of the factors presumptively affecting the accuracy outcome of cone-beam computed tomography (CBCT)-derived laboratory-based surgical guides for implant placement in partially edentulous patients.

MATERIALS AND METHODS

In 52 partially edentulous patients a total of 132 implants were placed following CBCT diagnostics with the aid of laboratory-fabricated, tooth-borne templates. Based on the image fusion technique measurements were done to calculate linear and angular deviations between virtually planned and placed implants. The implant sites were stratified according to four factors that presumably may influence the transfer accuracy: (i) type of arch (maxilla/mandible), (ii) kind of template (single-tooth gap/interrupted dental arch/shortened dental arch/reduced residual dentition), (iii) surgical technique (flapless/open flap), (iv) number of sleeve-guided site preparation steps (fully guided placement/freehand placement/freehand final drilling). The data were analyzed using analysis of variance and the Bonferroni test.

RESULTS

The transfer accuracy of shoulder level, apex level, and angulation was similar for maxilla and mandible as well as for flapless and open flap approach. The differences were small in magnitude and reached no or only a borderline statistical significance. At implant sites in the reduced residual dentition group, the discrepancies were more pronounced than in the single-tooth gap group, whereas no significant differences could be determined between free ending templates in the shortened dental arch and bilateral anchored templates in the interrupted dental arch. Implant placement through the guide allowed a more accurate implementation of the virtual plan to the surgical site than freehand insertion or freehand final drilling.

CONCLUSION

CBCT-derived laboratory-based surgical templates enabled an implant placement in the cancellous maxilla as well as flapless procedures without compromising the transfer accuracy. The number and distribution of the remaining teeth as well as the number of sleeve-guided implant site preparation steps influenced the extent of deviation that can be achieved in partial edentulism.