Implant Placement Accuracy When Using Stereolithographic Template as a Surgical Guide: Preliminary Results

Digitally guided root removal and simultaneous implant placement: A case study

BACKGROUND

Encountering a retained root tip post-extraction and prior to implant placement is a possible clinical complication. There are numerous approaches for removing retained roots that may be traumatic or atraumatic. Regardless of the approach, careful treatment planning is important to minimize complications, reduce morbidity, and preserve bony structures. The aim of the current case study is to introduce a technique and digitally generated device used for identifying and atraumatically removing a retained root tip and simultaneously placing a stable dental implant.

METHODS

A 63-year-old female with a history of myocardial infarction, hypertension, and acute pancreatitis presented for implant placement at site #5. Clinical examination revealed adequate interocclusal, mesiodistal, and buccolingual dimensions for implant placement. Radiographic examination using cone beam computed tomography revealed that retained root #5 interfered with implant placement. Digital planning was used to extract the root tip with minimal trauma to maintain adequate bone for simultaneous implant placement with good primary stability.

RESULTS

The follow-ups at 1, 3, and 6 weeks and 4, 8, and 10 months revealed good bone preservation with an osseointegrated implant.

CONCLUSIONS

Employment of digital planning to create a palatal window allowed excellent accuracy in removing the retained root while maintaining the bony foundation for a well osseointegrated dental implant.

KEY POINTS

Pre-planning using cone beam computed tomography scan merged with an intraoral digital scan is necessary for precise location of a retained root and correct implant placement with excellent primary stability. A digitally planned 3D surgical guide is a useful method for extracting retained roots during implant placement to minimize bone damage. Digital planning provides a precise and minimally invasive implant surgery.

Assessment of Deviations of Implants Installed with Prototyped Surgical Guide and Conventional Guide: In Vitro Study

OBJECTIVE

 The study aimed to assess the angular and linear deviations of implants installed in mannequins aided by surgical guides produced with the techniques of dual tomography (DT), model-based tomography (MT), and nonprototyped guide.

MATERIALS AND METHODS

 Implants were installed in mannequins of a partially edentulous maxilla and divided into three groups: Group C (n = 20), implants installed using the conventional technique with flap opening and conventional guide; Group DT (n = 20), implants installed using guided surgery with the dual tomography technique; and Group MT (n = 20), implants installed using the model-based tomography technique. After implant installation, the mannequin was subjected to a computed tomography (CT) to measure the linear and angular deviations of implant positioning relative to the initial planning on both sides.

RESULTS

 There was a higher mean angular deviation in group C (4.61 ± 1.21, p ≤ 0.001) than in groups DT (2.13 ± 0.62) and MT (1.87 ± 0.94), which were statistically similar between each other. Similarly, the linear deviations showed group C with the greatest discrepancy in relation to the other groups in the crown (2.17 ± 0.82, p = 0.007), central (2.2 ± 0.77, p = 0.004), and apical (2.34 ± 0.8, p = 0.001) regions.

CONCLUSION

 The techniques of DT and MT presented smaller angular and linear deviations than the conventional technique with the nonprototyped guide. There was no difference between the two-guided surgery techniques.

Failure rates associated with guided versus non-guided dental implant placement: a systematic review and meta-analysis

Objective

The purpose of the systematic review and meta-analysis was to evaluate implant failure rates and their association with guided and free-hand implant placement techniques.

Materials and methods

A literature search was conducted across PubMed, Medline via Ovid, Cochrane database, and Google Scholar. The search was completed in September 2020. Series of meta-analyses were conducted to compare implant failure rates with guided and free-hand techniques.

Results

A total of 3387 articles were identified from the electronic search. After applying the inclusion criteria, eight articles were selected for qualitative assessment and four for quantitative synthesis (meta-analysis). The included studies had a risk ratio of 0.29 (95% CI: 0.15, 0.58), P < 0.001 for the use of guided implant placement. Implant failure rates were affected by the different placement techniques indicated by the test for overall effect (Z = 3.53, P = 0.0004). The incidence of implant failure in guided surgery versus free-hand surgery was found to be 2.25% and 6.42%, respectively.

Conclusion

Both guided and free-hand implant placement techniques resulted in a high implant survival rate. However, implant failure rates were almost three times higher in the free-hand implant placement category. A guided implant placement approach is recommended for a successful outcome.

Accuracy of half-guided implant placement with machine-driven or manual insertion: a prospective, randomized clinical study

OBJECTIVES

To compare the accuracy of implant placement performed with either a surgical motor or a torque wrench as part of a half-guided surgical protocol.

MATERIALS AND METHODS

Implant insertion with half-guided surgical protocol was utilized by surgical motor (machine-driven group) or torque wrench (manual group) in the posterior maxilla. After the healing period, accuracy comparison between planned and actual implant positions was performed based on preoperative cone beam computed tomography and postoperative digital intraoral scans. Coronal, apical, and angular deviations, insertion time, and insertion torque were evaluated.

RESULTS

Forty patients were treated with 1 implant each; 20 implants were inserted with a surgical motor and 20 implants with a torque wrench. Global coronal and apical deviations were 1.20 ± 0.46 mm and 1.45 ± 0.79 mm in the machine-driven group, and 1.13 ± 0.38 mm and 1.18 ± 0.28 mm in the manual group (respectively). The mean angular deviation was 4.82 ± 2.07° in the machine-driven group and 4.11 ± 1.63° in the manual group. Mean insertion torque was 21.75 ± 9.75 Ncm in the machine-driven group, compared to 18.75 ± 7.05 Ncm in the manual group. Implant placement duration was 9.25 ± 1.86 s in the machine-driven group at a speed of 50 rpm, and 36.40 ± 8.15 s in the manual group.

CONCLUSION

No significant difference was found between the two groups in terms of accuracy and mean insertion torque, while machine-driven implant placement was significantly less time-consuming.

CLINICAL RELEVANCE

Optimal implant placement accuracy utilized by half-guided surgical protocol can be achieved with both machine-driven and torque wrench insertion.

TRIAL REGISTRATION

ID: NCT04854239.

A Novel Digital Implant Planning Workflow in Patients with Preexisting Metal Restorations: A Technical Report

A prosthetically-driven virtual implant plan is considered a challenging procedure depending on accurate registration of the three-dimensional optical surface scan and 3D volumetric rendering reconstructed from cone-beam computed tomography (CBCT) images. However, the presence of preexisting metal restorations may significantly negatively influence the registration process. This technical report describes a novel digital workflow to optimize the implant planning outcome for the partially edentulous patient with preexisting metal restorations by accurately aligning the standard triangle language data of the intraoral scanner with the CBCT rendering using a dual-scan technique and an appliance with radiographic markers.

An evaluation of virtually planned and 3D-printed stereolithographic surgical guides from CBCT and digital scans: An in vitro study

STATEMENT OF PROBLEM

The process of manufacturing stereolithographic surgical guides for static computer-guided implant placement involves a series of steps. Errors can be incorporated in various forms and at various stages of manufacturing these guides. Errors introduced during this process have not been fully investigated.

PURPOSE

The purpose of this in vitro study was to assess the errors introduced during the manufacture of stereolithographic surgical guides generated from cone beam computed tomography (CBCT) and digital scans by using a virtual implant planning software.

MATERIAL AND METHODS

Ten stereolithographic surgical guides with the associated standard tessellation language (STL) files of their virtual design were used in this study. The STL files of the virtual design and the scans of the stereolithographic surgical guides were superimposed. Linear deviation at the center of the sleeve top and sleeve base and the angular deviation at the center of the sleeve were measured.

RESULTS

The minimum and maximum linear deviation at the center of the sleeve top and the sleeve base was found to be 0 and 40 μm, with less linear deviation observed at the center of the sleeve top (mean ±standard deviation 18 ±7 μm) than at the center of the sleeve base (20 ±7 μm). The minimum and maximum angular deviation at the center of the sleeve was found to be 0 degrees and 5.9 degrees respectively, with a mean ± standard deviation of 1.36 ±0.74 degrees.

CONCLUSIONS

Errors were found in the sleeve position between the virtual design and the stereolithographically manufactured surgical guide. This error may introduce errors in the final implant position.

A Review of 3D Printing in Dentistry: Technologies, Affecting Factors, and Applications

Three-dimensional (3D) printing technologies are advanced manufacturing technologies based on computer-aided design digital models to create personalized 3D objects automatically. They have been widely used in the industry, design, engineering, and manufacturing fields for nearly 30 years. Three-dimensional printing has many advantages in process engineering, with applications in dentistry ranging from the field of prosthodontics, oral and maxillofacial surgery, and oral implantology to orthodontics, endodontics, and periodontology. This review provides a practical and scientific overview of 3D printing technologies. First, it introduces current 3D printing technologies, including powder bed fusion, photopolymerization molding, and fused deposition modeling. Additionally, it introduces various factors affecting 3D printing metrics, such as mechanical properties and accuracy. The final section presents a summary of the clinical applications of 3D printing in dentistry, including manufacturing working models and main applications in the fields of prosthodontics, oral and maxillofacial surgery, and oral implantology. The 3D printing technologies have the advantages of high material utilization and the ability to manufacture a single complex geometry; nevertheless, they have the disadvantages of high cost and time-consuming postprocessing. The development of new materials and technologies will be the future trend of 3D printing in dentistry, and there is no denying that 3D printing will have a bright future.

Drill Bit Guiding System for Implant Placement

Introduction:

The implant angulation plays a very important role in the outcome of prosthetic and functional outcome. The conventional surgical stents uses a ring system to drill the pilot drill, only the CAD printed stents provides a guide sleeves for the sequential drill for implant placement.

The Purpose of this Study:

The purpose of the study was to fabricate a drill bit guide for the stent to transfer the angulation and implant placement planned using conventional method in prescribed drilling sequence.

Material and Methods:

A surgical stent with a threaded guide ring system was fabricated with internal drill bit guiding system. The interchangeable sequential drilling allows the drill bit to be in predetermined position throughout the procedure.

Results:

The surgical stent with the drill bit guiding system provided less than 1% error with a mean deviation of 0.48%.

Conclusion:

The drill bit guide fabricated has a complete limiting system and transfers the angulation and placement as desired with very minimal or no alteration, which enables the predetermined prosthetic outcome.

Accuracy of Guided Surgery via Stereolithographic Mucosa-Supported Surgical Guide in Implant Surgery for Edentulous Patient: a Systematic Review

Objectives

The purpose of the present study is to systematically review the accuracy of implant placement with mucosa-supported stereolithographic surgical guide and to find out what factors can influence the accuracy.

Material and Methods

An electronic literature search was performed through the MEDLINE (PubMed) and EMBASE databases. The articles are including human studies published in English from October 2008 to October, 2017. From the examination of selected articles, deviations between virtual planning and actual implant placement were analysed regarding the global apical, global coronal, and angulation position.

Results

A total of 119 articles were reviewed, and 6 of the most relevant articles that are suitable to the criteria were selected. The present data included 572 implants and 93 patients. The result in the present systematic review shows that mean apical global deviation ranges from 0.67 (SD 0.34) mm to 2.19 (SD 0.83) mm, mean coronal global deviation ranges from 0.6 (SD 0.25) mm to 1.68 (SD 0.25) mm and mean angular deviation - from 2.6° (SD 1.61°) to 4.67° (SD 2.68°).

Conclusions

It's clearly shown from most of the examined studies that the mucosa-supported stereolithographic surgical guide, showed not exceeding in apically 2.19 mm, in coronally 1.68 mm and in angular deviation 4.67°. Surgeons should be aware of the possible linear and angular deviations of the system. Accuracy can be influenced by bone density, mucosal thickness, surgical techniques, type of jaw, smoking habits and implant length. Further studies should be performed in order to find out which jaw can have better accuracy and how the experience can influence the accuracy.

Accuracy Evaluation of a Stereolithographic Surgical Template for Dental Implant Insertion Using 3D Superimposition Protocol

The aim

of this study was to evaluate the accuracy of a stereolithographic template, with sleeve structure incorporated into the design, for computer-guided dental implant insertion in partially edentulous patients.

Materials and Methods

Sixty-five implants were placed in twenty-five consecutive patients with a stereolithographic surgical template. After surgery, digital impression was taken and 3D inaccuracy of implants position at entry point, apex, and angle deviation was measured using an inspection tool software. Mann–Whitney U test was used to compare accuracy between maxillary and mandibular surgical guides. A p value < .05 was considered significant.

Results

Mean (and standard deviation) of 3D error at the entry point was 0.798 mm (±0.52), at the implant apex it was 1.17 mm (±0.63), and mean angular deviation was 2.34 (±0.85). A statistically significant reduced 3D error was observed at entry point p = .037, at implant apex p = .008, and also in angular deviation p = .030 in mandible when comparing to maxilla.

Conclusions

The surgical template used has proved high accuracy for implant insertion. Within the limitations of the present study, the protocol for comparing a digital file (treatment plan) with postinsertion digital impression may be considered a useful procedure for assessing surgical template accuracy, avoiding radiation exposure, during postoperative CBCT scanning.

Accuracy Assessment of Immediate and Delayed Implant Placements Using CAD/CAM Surgical Guides

The aim of this study is to assess the accuracy of immediately placed implants using Anatomage Invivo5 computer-assisted design/computer-assisted manufacturing (CAD/CAM) surgical guides and compare the accuracy to delayed implant placement protocol. Patients who had implants placed using Anatomage Invivo5 CAD/CAM surgical guides during the period of 2012–2015 were evaluated retrospectively. Patients who received immediate implant placements and/or delayed implant placements replacing 1–2 teeth were included in this study. Pre- and postsurgical images were superimposed to evaluate deviations at the crest, apex, and angle. A total of 40 implants placed in 29 patients were included in this study. The overall mean deviations measured at the crest, apex, and angle were 0.86 mm, 1.25 mm, and 3.79°, respectively. The means for the immediate group deviations were: crest = 0.85 mm, apex = 1.10, and angle = 3.49°. The means for the delayed group deviations were: crest = 0.88 mm, apex = 1.59, and angle = 4.29°. No statistically significant difference was found at the crest and angle; however, there was a statistically significant difference between the immediate and delayed group at the apex, with the immediate group presenting more accurate placements at the apical point than the delayed group. CAD/CAM surgical guides can be reliable tools to accurately place implants immediately and/or in a delayed fashion. No statistically significant differences were found between the delayed and the immediate group at the crest and angle, however apical position was more accurate in the immediate group.

An Accuracy Study of Computer-Planned Implant Placement in the Augmented Maxilla Using Mucosa-Supported Surgical Templates

PURPOSE

The purpose of this study was to determine the clinically relevant accuracy of implant placement in the augmented maxilla using computer planning and a mucosa-supported surgical template.

MATERIALS AND METHODS

Twenty-five consecutive edentulous patients with an extreme maxillar alveolar ridge resorption were treated with a bone augmentation procedure. In a second stage, six Brånemark MkIII Groovy (Nobel Biocare®, Zürich, Switzerland) implants were installed. Preoperatively, a cone beam computer tomography (CBCT) scan was acquired, followed by virtual implant planning and flapless implant placement using a surgical template. A postoperative CBCT scan was acquired and registered to the preoperative scan. The Implant Position Orthogonal Projection validation method was applied to measure implant deviations in both the buccolingual and mesio-distal plane. The influence of fixation pins and the position on the dental arch were investigated with regard to implant deviations, and rotations and translations of the surgical template.

RESULTS

One hundred fifty implants were installed. In mesio-distal direction, a mean implant deviation of 1.50 mm was scored at the implant tip, 1.27 mm at the shoulder, -0.60 mm in depth, as well as a mean deviation of angulation of 2.50°. In buccolingual direction, a mean implant deviation of 0.99 mm was found at the implant tip, 0.76 mm at the implant shoulder, -0.57 mm in depth, and a deviation of angulation of 2.48°. Of all implants, 53% was placed too superficial compared with the planning. The use of fixation pins and implant deviations in both buccal and mesial directions as also for rotations and translation of the surgical template showed statistically significant differences.

CONCLUSIONS

Computer-aided implant planning showed to be a clinically relevant tool. However, this study emphasizes that the surgeon should take into account that deviations are larger compared with implant placement without augmentation procedure. Deviations are mainly caused by angulations and translations of the surgical template.

Virtual planning and construction of prototyped surgical guide in implant surgery with maxillary sinus bone graft

PURPOSE

To evaluate the efficacy of associating techniques of bone grafting in the maxillary sinus with the use of a prototyped surgical guide for planning and positioning dental implants in total edentulous maxillae, rehabilitated after six months.

METHODS

Eight patients consecutives with totally edentulous maxilla presenting few remaining bone in the posterior alveolar ridge, associated with pneumatization of the maxillary sinus were selected. Twenty eight Brånemark RP 10mm implants were installed in 14 maxillary sinuses. The surgical planning for the implant installation was performed with the DentalSlice software by means of a computerized tomography. The obtained images were used for building a surgical guide that, placed over the maxilla, showed the exact position for the implants installation (prototyped surgical guide). The portion of the implants that went into the maxillary sinus was covered by an autogenous bone graft.

RESULTS

The patients were re-evaluated six months after the surgery and a 100% success rate was achieved. All of the implants presented no mobility or symptoms, permitting an oral rehabilitation with total fixed screw-retained prosthesis over the implants.

CONCLUSION

The technique of associating implants and bone graft in the maxillary sinus aided by a prototyped guide planned on DentalSlice has showed itself efficient for positioning implants and for quantifying and locating the bone graft.

Accuracy of computer-aided implant placement

AIM

To assess the accuracy of static computer-guided implant placement.

MATERIAL AND METHODS

Electronic and manual literature searches were conducted to collect information on the accuracy of static computer-guided implant placement and meta-regression analyses were performed to summarize and analyse the overall accuracy. The latter included a search for correlations between factors such as: support (teeth/mucosa/bone), number of templates, use of fixation pins, jaw, template production, guiding system, guided implant placement.

RESULTS

Nineteen accuracy studies met the inclusion criteria. Meta analysis revealed a mean error of 0.99 mm (ranging from 0 to 6.5 mm) at the entry point and of 1.24 mm (ranging from 0 to 6.9 mm) at the apex. The mean angular deviation was 3.81° (ranging from 0 to 24.9°). Significant differences for all deviation parameters was found for implant-guided placement compared to placement without guidance. Number of templates used was significant, influencing the apical and angular deviation in favour for the single template. Study design and jaw location had no significant effect. Less deviation was found when more fixation pins were used (significant for entry).

CONCLUSION

Computer-guided implant placement can be accurate, but significant deviations have to be taken into account. Randomized studies are needed to analyse the impact of individual parameters in order to allow optimization of this technique. Moreover, a clear overview on indications and benefits would help the clinicians to find the right candidates.

A clinically relevant accuracy study of computer-planned implant placement in the edentulous maxilla using mucosa-supported surgical templates

PURPOSE

The purpose of the study is to determine the clinically relevant accuracy of implant placement in the edentulous maxilla using computer planning and a mucosa-supported surgical template.

MATERIALS AND METHODS

In each of in total 30 consecutive edentulous patients suffering from retention problems of their upper denture, two or four Brånemark MkIII Groovy (Nobel Biocare®, Zürich, Switzerland) implants in the maxilla were installed. Preoperatively, first, a cone-beam computer tomography (cone beam computer tomography) scan was acquired, followed by virtual implant planning. Hereafter, a surgical template was designed to allow flapless implant placement using the template as a guide. To inventory the accuracy of implant placement, a postoperative CBCT scan was obtained and matched to the preoperative scan. The accuracy of implant placement was validated three-dimensionally. The Implant Position Orthogonal Projection validation method was applied to measure the clinically relevant implant deviations (i.e., in both the bucco-lingual and mesio-distal plane). Also, the influence of type of surgery, use of fixation pins, and position on the dental arch were investigated with regard to implant deviations.

RESULTS

In total, 104 implants were installed. In bucco-lingual direction, a mean implant deviation of 0.67 mm was scored at the implant tip, of 0.51 mm at the shoulder, of -0.83 mm in depth, as also a mean deviation of angulation of 1.74°. In mesio-distal direction, a mean implant deviation of 0.75 mm was found at the implant tip, of 0.60 mm at the implant shoulder, of -0.75 mm in depth, and a deviation of angulation of 1.94°. Of all implants, 74% was placed not deep enough compared with the planning. Implant position on the dental arch, the use of fixation pins, and type of surgery showed no significant effect on implant deviations. However, a significant difference for implant deviations in both buccal and mesial direction was observed, explained by a nonoptimal positioning of the surgical template.

CONCLUSIONS

Computer-aided implant planning showed to be a clinically relevant tool for the placement of two or four implants in the maxilla of fully edentulous patients. Exact positioning of the surgical template in anterior/posterior direction is crucial in reducing implant deviations both in buccal and mesial direction.

Preoperative analysis of the stability of fit of a patient-specific surgical guide

Although the use of patient-specific surgical guides has gained popularity over the past decade, little research has been done to examine in an objective and qualitative way the fit of such instruments. In this study, we have developed a model to predict the stability of a guide designed to fit on a supporting bone surface, thereby providing feedback on the translational and rotational stability of the device. The method was validated by comparing different guide designs with respect to their stability on the contact surface and comparing these results to those measured with a set of experiments. This validation experiment indicates that our stability model can be used to predict the stability of the fit of a surgical guide during the preoperative design process.

Accuracy of three different types of stereolithographic surgical guide in implant placement: an in vitro study

STATEMENT OF PROBLEM

Precise treatment planning before implant surgery is necessary to identify vital structures and to ensure a predictable restorative outcome.

PURPOSE

The purpose of this study was to compare the accuracy of implant placement by using 3 different types of surgical guide: bone-supported, tooth-supported, and mucosa-supported.

MATERIAL AND METHODS

Thirty acrylic resin mandibles were fabricated with stereolithography (SLA) based on data from the cone beam computerized tomography (CBCT) scan of an edentulous patient. Ten of the mandibles were modified digitally before fabrication with the addition of 4 teeth, and 10 of the mandibles were modified after fabrication with soft acrylic resin to simulate mucosa. Each acrylic resin mandible had 5 implants virtually planned in a 3-D software program. A total of 150 implants were planned and placed by using SLA guides. Presurgical and postsurgical CBCT scans were superimposed to compare the virtual implant placement with the actual implant placement. For statistical analyses, a linear mixed models approach and t-test with the 2-sided alpha level set at .016 were used. All reported P values were adjusted by the Dunn-Sidak method to control the Type I error rate across multiple pairwise comparisons.

RESULTS

The mean angular deviation of the long axis between the planned and placed implants was 2.2 ±1.2 degrees; the mean deviations in linear distance between the planned and placed implants were 1.18 ±0.42 mm at the implant neck and 1.44 ±0.67 mm at the implant apex for all 150 implants. After the superimposition procedure, the angular deviation of the placed implants was 2.26 ±1.30 degrees with the tooth-supported, 2.17 ±1.02 degrees with the bone-supported, and 2.29 ±1.28 degrees with the mucosa-supported SLA guide. The mean deviations in linear distance between the planned and placed implants at the neck and apex were 1.00 ±0.33 mm and 1.15 ±0.42 mm for the tooth-supported guides; 1.08 ±0.33 mm and 1.53 ±0.90 mm for the bone-supported guides; and 1.47 ±0.43 mm and 1.65 ±0.48 mm for the mucosa-supported SLA surgical guides.

CONCLUSIONS

The results of this study show that stereolithographic surgical guides may be reliable in implant placement and that: 1) there was no statistically significant difference among the 3 types of guide when comparing angular deviation and 2) mucosa-supported guides were less accurate than both tooth-supported and bone-supported guides for linear deviation at the implant neck and apex.

Reliability of implant surgical guides based on soft-tissue models

The purpose of this study was to determine the accuracy of implant surgical guides fabricated on diagnostic casts. Guides were fabricated with radiopaque rods representing implant positions. Cone beam computerized tomograms were taken with guides in place. Accuracy was evaluated using software to simulate implant placement. Twenty-two sites (47%) were considered accurate (13 of 24 maxillary and 9 of 23 mandibular sites). Soft-tissue models do not always provide sufficient accuracy for fabricating implant surgical guides.

Integration of 3D anatomical data obtained by CT imaging and 3D optical scanning for computer aided implant surgery

BACKGROUND

A precise placement of dental implants is a crucial step to optimize both prosthetic aspects and functional constraints. In this context, the use of virtual guiding systems has been recognized as a fundamental tool to control the ideal implant position. In particular, complex periodontal surgeries can be performed using preoperative planning based on CT data. The critical point of the procedure relies on the lack of accuracy in transferring CT planning information to surgical field through custom-made stereo-lithographic surgical guides.

METHODS

In this work, a novel methodology is proposed for monitoring loss of accuracy in transferring CT dental information into periodontal surgical field. The methodology is based on integrating 3D data of anatomical (impression and cast) and preoperative (radiographic template) models, obtained by both CT and optical scanning processes.

RESULTS

A clinical case, relative to a fully edentulous jaw patient, has been used as test case to assess the accuracy of the various steps concurring in manufacturing surgical guides. In particular, a surgical guide has been designed to place implants in the bone structure of the patient. The analysis of the results has allowed the clinician to monitor all the errors, which have been occurring step by step manufacturing the physical templates.

CONCLUSIONS

The use of an optical scanner, which has a higher resolution and accuracy than CT scanning, has demonstrated to be a valid support to control the precision of the various physical models adopted and to point out possible error sources. A case study regarding a fully edentulous patient has confirmed the feasibility of the proposed methodology.

Precision of implant placement with stereolithographic templates: a pilot in vitro study

This pilot study assesses the accuracy of 2 bone-supported stereolithographic surgical templates with respect to placement of implants in originally planned positions, and it tests the precision of dental volumetric tomography planning. Two mandibles retrieved from formalin-fixed human cadavers were scanned by dental volumetric tomography for planning of the implant positions, leading to stereolithographic models and fabrication of surgical guides. The situation immediately following drilling and implant insertion by an experienced surgeon was scanned and the outcome compared with the initial planning. The 3-dimensional discrepancies were then analyzed and determined. The results show deviations of the placed implants from the original planning, especially in the vertical direction, making the seating of a prefabricated denture impossible. At present, the flapless surgery technique based on stereolithographic surgical templates appears unsafe; further improvement is required.

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 guide systems for computer-aided implant placement: a computed tomography-based clinical comparative study

BACKGROUND

Stereolithographic surgical guides provide significant benefits during the simultaneous placement of multiple implants with regard to the final prosthetic plan. However, deviation from the planning poses a significant risk. Deviations of implants that were placed by bone-, tooth-, and mucosa-supported stereolithographic surgical guides were examined in this study.

METHODS

After enrolling 54 eligible patients, 294 implants were planned on cone-beam computerized tomography CB(CT)-derived images. Sixty guides, both single- and multiple-type, were produced using two commercial systems. Mucosa-supported guides were fixed with osteosynthesis screws. Implants were inserted, and at the end of osseointegration period, a new CB(CT) scan was performed. Preoperative planning was merged with the new CB(CT) data to identify the deviations between the planned and placed implants for each support type and manufacturer. The Kruskal-Wallis and Mann-Whitney U tests were used for comparison (P <0.05).

RESULTS

There were no damage-related complications in any critical anatomy. Implants that were placed by bone-supported guides had the highest mean deviations (5.0 degrees +/- 1.66 degrees angular, and 1.70 +/- 0.52 mm and 1.99 +/- 0.64 mm for implant shoulder and tip, respectively), whereas the lowest deviations were measured in implants that were placed by mucosa-supported guides (2.9 degrees +/- 0.39 degrees angular, and 0.7 +/- 0.13 mm and 0.76 +/- 0.15 mm for implant shoulder and tip, respectively).

CONCLUSIONS

Computer-aided planning and manufacturing surgical guides in accordance with CB(CT) images may help clinicians place implants. Rigid screw fixation of a single guide incorporating metal sleeves and a special drill kit further minimizes deviations.