Article

Accuracy of Computer-Assisted Template-Based
Implant Placement Using Two Different Surgical
Templates Designed with or without Metallic Sleeves:
A Randomized Controlled Trial
Marco Tallarico 1,2,*, Matteo Martinolli 3, Yongjin Kim 4, Fabio Cocchi 5, Silvio Mario Meloni 6,7,
Adem Alushi 8 and Erta Xhanari 1,91

Department of Implantology and Prosthetic Aspects, Master of Science in Dentistry Program,
Aldent University, 1001 Tirana, Albania; ertaxhanari@hotmail.com
2 Private practice, 00143 Rome, Italy
3 Private practice, 45014 Porto Viro, Italy; matteo.martinolli@hotmail.it
4 Apsun Dental Clinic, Ilsan 10381, Korea; ddskyj@naver.com
5 Private practice, 41121 Modena, Italy; ing.fabiococchi@gmail.com
6 Surgical, School of Dentistry, University of Sassari, 07100 Sassari, Italy; melonisilviomario@yahoo.it
7 Private practice, 07021 Arzachena, Italy;
8 Department of Restorative Dentistry, University of Medicine Tirana, 1001 Tirana, Albania;
info@ertaxhanari.com
9 Private practice, 1001 Tirana, Albania* Correspondence: me@studiomarcotallarico.it
Received: 7 February 2019; Accepted: 19 March 2019; Published: 2 April 2019

Abstract: Purpose: To compare virtual planning accuracy of novel computer-assisted, templatebased implant placement techniques, which make use of CAD/CAM stereolithographic surgicaltemplates with or without metallic sleeves. Furthermore, to compare open versus closed sleeves fortemplates without metallic sleeves. Materials and methods: Any partially edentulous patientsrequiring at least one implant to be placed according to a computer-assisted template-based
protocol were enrolled. Patients were randomized according to a parallel group design into two
arms: Surgical template with or without metallic sleeves. Three deviation parameters (angular,
horizontal, vertical) were defined to evaluate the discrepancy between the planned and placed
implant positions. Results: No implants failed, and no complications were experienced. Forty-one
implants were placed using surgical templates with metallic sleeves while 49 implants were placedwith a surgical template without metallic sleeves. Of these, 16 implants were placed through open
sleeves and 33 through closed sleeves. There was a statistically significant difference in angle (p =0.0212) and in the vertical plan (p = 0.0073) with lower values for implants placed with a surgicaltemplate without metallic sleeves. In the test group, close sleeves were more accurate comparedwith open sleeves in angle (p = 0.0268) and in horizontal plan (p = 0.0477). Conclusion: With thelimitations of the present study, surgical templates without metallic sleeves were more accurate in
the vertical plan and angle compared to the conventional template with metallic sleeves. Open
sleeves should be used with caution in the molar region only in case of reduced interarch space.
Further research is needed to confirm these preliminary results.
Keywords: intraoral scanner; digital impression; guided surgery; accuracy; dental implants

Dent. J. 2019, 7, 41; doi:10.3390/dj7020041

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1. Introduction
Nowadays, the development of three-dimensional (3D) imaging techniques and implant
planning software has contributed to a large diffusion of prosthetically guided implant placement,
nevertheless, the replacement of lost natural teeth is still a challenge for the clinician, mostly due tobone deficiency. Modern digital technology could help to improve patients’ acceptance and clinicalsuccess. In the last years, the use of digital intraoral optical scanner (IOS) has been shown to be a
viable option for the rehabilitation of partial edentulous patients, even when associated to computerguided template-assisted implant placement [1,2]. The clinician and the patient can benefit in termsof shorter treatment time if intraoral digital impression is used [2].
According to the Glossary of prosthodontic terms, surgical template (or surgical guide) isdefined as ‘a guide used to assist in proper surgical placement and angulation of dental implants’ [3].
In a randomized controlled trial with five years of follow-up, the implant survival rate has been
similar for conventional and computer-guided template-assisted implant placement procedures [4,5].
Furthermore, a significant reduction of post-operative pain and swelling, as well as statisticallysignificant lower marginal bone loss were found five years after loading, placing implants with atemplate-based approach [5].
The main objective of the surgical guide is to guide implant drills and provide accurate implant
placement according to the virtual, prosthetically driven, treatment plan. Thanks to improved
technologies, including stereolithography, surgical templates are easy to produce, representing theunion of guiding cylinders and contact surface. The latter fits either on hard and soft tissues giving
stability, while, the cylinders work as a drill guides orienting the drill in the exact location anddirection. Usually, surgical templates contain metallic sleeves to drive surgical drills. Recently,
surgical templates without metallic sleeves have been designed and introduced in the dental market,
with the goal to make guided surgery work-flow faster and easier. It is intrinsic that thanks to theabsence of metal, the templates designed without metallic sleeve can be customized, requiring, forexample, less mesio-distal space. Moreover, sleeve-designed templates can be produced with a slot
(usually buccal or lingual located) that allows the horizontal insertion of the drills (open sleeve),
reducing the minimum required interarch space, and also reducing the bone heating due to a direct
saline irrigation on the drill. Another advantage of the digital work-flow and the development ofhigh quality desktop 3D printers is making in-house surgical template production affordable [6]. This
makes the sleeve-designed templates easier to produce and probably less expensive due to theabsence of stainless steel or titanium drill-guiding tubes. Nevertheless, there is still lack of data about
their accuracy and predictability. For all of these reasons, the possibility to easily customize the newly
designed surgical templates should represent one of the most important benefits for the clinician. In
addition, evidence that newly developed templates are better than conventional ones is still lacking.
The purpose of the present randomized controlled trial is to compare implant survival rate,complications, and accuracy of computer-assisted template-based implant placement using surgicaltemplates designed with or without metallic sleeves. Furthermore, to compare implant accuracy
using open or closed holes in case of tubeless templates. The null hypothesis was that there would be
no differences between these groups. This trial is reported in accordance with the CONSORT(Consolidated Standards of Reporting Trials) statement (http://www.consort-statment.org) for
improving the quality of reporting of parallel-group randomized trials.
2. Materials and Methods
This study was designed as a randomized controlled trial of parallel group design conducted at
one center between May 2016 and March 2017. The study was performed after approval was received
from the institutional review board of the Aldent University, Tirana, Albania (2/2017). The
investigation was conducted according to the principles embodied in the Helsinki Declaration of 2013
and the trial was recorded and registered in the public register of clinical trials(www.clinicaltrials.gov) with the number NCT03641365. Surgical and prosthetic procedures were
performed by one expert clinician (MT). All patients were informed about the nature of the treatment
and their written consent was obtained. Data collection was designed to preserve patient anonymity.

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Any partially edentulous patients aged 18 years or older, able to sign an informed consent, in
need of an implant-supported fixed restoration was considered eligible for this study. Any potential
implant location based on individual patient requirements was considered eligible in the present
trial. Exclusion criteria were: General medical contraindication to oral surgery (American Society ofAnesthesiologist, ASA, class III or IV); irradiation in the head and neck area less than one year before
implantation; psychiatric problems; alcohol or drug abuse; pregnant or nursing; untreatedperiodontitis; severe bruxism or clenching; uncontrolled diabetes; poor oral hygiene and motivation;and inability to complete the follow-up.
Enrolled patients received preoperative photographs, periapical radiographs or panoramic xrays for initial screening and evaluation. The prosthetic-driven planning workflow started by taking
a cone beam computed tomography (CBCT) scan (Cranex 3Dx, Soredex, Tuusula, Finland) by using
a wax bite to separate dental arches. Then, the patients received intraoral digital impression takenusing the 3M True Definition Scanner (3M Italia, Pioltello, Milano). The digital data (STL, Surface
Tessellation Language) were imported in a 3D design software (exocad DentalCAD, Exocad GmbH,
Darmstadt, Germany) to realize a virtual wax-up according to the functional and esthetic
requirements. Then, the STL and DICOM (Digital Imaging and COmmunications in Medicine) data
were imported in a 3D software planning program (3Diagnosys ver. 5.0, 3DIEMME srl, Cantù, Italy).
Then, the reprocessed surface extrapolated from the DICOM data (by using a Hounsfield scale filter)
and the surface generated by the master cast scanning process, or by the intraoral scanning process,were merged with the best-fitting repositioning tools of the software (3Diagnosys ver. 5.0, 3DIEMME
srl). Afterwards, prosthetic-driven implants/abutments size and location were planned to take into
account the bone quality and quantity, soft tissue thickness, anatomical landmarks, as well as type,volume, and shape of the final restoration. After careful functional and esthetic evaluation and final
verification, the prosthetic-driven plan was approved. At this point, patients were randomly assigned
to receive conventional stereolithographic surgical template with (control group, Figure 1) or without(test group, Figures 2 and 3) metallic sleeves. Stereolithographic surgical templates were designed
and fabricated by an independent certified center not previously involved in the study (New
Ancorvis srl, Bargellino, Italy). In the test group, conventional templates with close-sleeve-design
were produced to place implants between premolars. In case of implants to be placed in molar area,
template with open sites were produced to solve interarch space limits.

Figure 1. Surgical templates with metallic sleeves.
All patients underwent professional oral hygiene, prophylactic antiseptic with 0.2%
chlorhexidine (Curasept, Curaden Healthcare, Saronno, Italy) for one minute, and prophylactic
antibiotic therapy (2 g of amoxicillin or clindamycin 600 mg if allergic to penicillin). Immediately
before implant placement, the fit of the surgical templates was accurately tried in the patient mouthto achieve a stable fit (Fit Checker, GC—Tokyo, Japan). All patients were treated under local
anesthesia using articaine with adrenaline 1:100000 administered 20 min before surgery. The surgicaltemplates were stabilized on the residual teeth and fixed with two to three preplanned anchor pins.

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Figure 2. Surgical template without metallic sleeves: Closed sleeves.

Figure 3. Surgical template without metallic sleeves: Open sleeves.
Hopeless teeth were extracted at the end of the intervention in order to improve the stability ofthe surgical template and to provide more reference point for measurements of the implant accuracy.
Nevertheless, in the case of immediate post-extractive implants, residual teeth were extracted as atraumatically as possible immediately before surgery. In the test group, planned implants (Osstem
TSIII, Osstem, Seoul, South Korea) were placed flapless using dedicate drills (OneGuide Kit, Osstem)in combination with a sleeve-designed surgical guide. In this case the drills were used directly
through the sleeve-designed template without metallic tubs and without drill reductions. In thecontrol group, planned implants (Osstem TSIII, Osstem, Seoul, South Korea) were placed flaplessusing dedicate drills (OsstemGuide Kit [Taper], Osstem) in combination with reduction tools, within
the surgical templates containing metallic sleeves. If the keratinized gingiva and the amount of bone
were adequate, the implants were placed flapless. Otherwise, a flap was elevated and then the wound
was closed with single-stitch sutures using 4.0 resorbable suture material (Vicryl, Ethicon J&J
International, Sint-Stevens-Woluwe, Belgium). Implant sites were prepared based on the bonedensity evaluated by the surgeon at the first drill. All the implants were inserted according to a onestage protocol, with an insertion torque ranging from 35 to 45 N·cm. In case of poor bone density, theimplant site was underprepared. Immediately after implant placement, patients of both groups
received a digital impression (3M True Definition Scanner, 3M Italia, Pioltello, Milano) taken at
implant level using dedicated abutments (Scan body type AQ, New Ancorvis srl), to check theposition of the placed implants. Following implant placement, all patients received oral and writtenDent. J. 2019, 7, 41

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recommendations about the medication, oral hygiene maintenance, and diet. Implants were loaded
after eight to 12 weeks of healing. Then, patients were followed twice a year for hygiene maintenanceand occlusal control.
3. Outcome Measurements
Outcome measurements were implant failure, template-related complications, and accuracy.
An Implant was considered failed if it was lost for any reason (mobility, fracture or any
infection). The stability of each individual implant was measured according to a previously publishedstudy. [7]. Fracture and/or infection were evaluated clinically and radiographically.
Any complications involving the surgical template was considered as template-related
complication, including but not limited to, mismatching of the surgical template and fracture.
All the complications were recorded during at implant placement or during the follow-up by
the same clinician (MT), who performed all the surgical procedures.
Accuracy: Three deviation parameters (horizontal, vertical, and angular) were defined andcalculated between the planned and placed implant positions according to a previously publishedstudy [7]. An expert mechanical engineer (FC) not previously involved in the study, performed all
the measurements (Figure 4 and 5).

Figure 4. Superimposition of the Surface Tessellation Language (STL) derived from theplanning with the STL taken after implant placement.

Figure 5. Measurement of the virtual planning accuracy by superimposition of the STL
derived from the planning with the STL taken after implant placement.
4. Randomization
One computer-generated restricted randomization list was created by independent
investigators, not involved in the selection and treatment of any patients. The random codes wereenclosed in sequentially numbered, identical, opaque, sealed envelopes, that were opened
consecutively, immediately after final approval of the computer-assisted plan.

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5. Statistical Analysis
No “a priori” sample size calculation was made. Patient data were collected in a Numbers
spreadsheet (Version 3.6.1 for Mac OS X 10.11.4). A bio-statistician analyzed the data using SPSS
software for Mac OS X (version 22.0; SPSS Inc., Chicago, IL, USA) for statistical analysis. Descriptive
analysis was performed for numeric parameters using mean ± standard deviation and median withconfidence interval (95% CI). Implant failure and template-related complications between the twointerventions were compared using the Fisher’s exact probability test. The nonparametric MannWhitney U test were used to compare the mean differences in horizontal, vertical, and angulardeviation between groups. All statistical comparisons were conducted at the 0.05 level of significance.
6. Results
A flow diagram of activities through the phases of the trial is shown in Figure 6. Thirty-two
patients were considered eligible for this trial. Two patients were not included, because they refused
to participate in this study. No patient dropped out, and all patients were treated according to theallocated interventions.

Figure 6. Consolidated Standards of Reporting Trials (CONSORT) diagram.
Fifteen patients (eight female and seven males with a mean age of 45.1 years) were randomized
to the control group (template with metallic sleeves) and 15 (10 female and five males with a mean

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7 of 11age of 55.2 years) to the test group (without metallic sleeves). A total of 41 implants were placed in
the control group while 49 implants were placed in the test group. Of these, 16 implants were placed
through open sleeves and 33 through closed sleeves.
No implants failed and no complications were experienced at 6 months after loading follow-up.
All the implants were inserted according to the manufacturer’s instructions, with an insertion torqueranged between 35 and 45 N·cm.
In the control group, the analysis of the final implant accuracy revealed a total mean error of
2.25 ± 1.41° (range 0.3–5.0°; 95% CI 0.52 to 1.65°) in angle; 0.52 ± 0.30 mm (range 0.1–1.1 mm; 95% CI
0.39 to 0.61 mm) in the horizontal plan (mesio-distal), and 0.58 ± 0.44 mm (range 0.0–1.6 mm; 95% CI
0.44 to 0.76 mm) in the vertical plan (apico-coronal). Overall, in the test group, the analysis of the
final implant accuracy revealed a total mean error of 1.98 ± 2.38° (range 0.1–11.8°; 95% CI 0.13 to 1.47°)
in angle; 0.61 ± 0.49 mm (range 0.05–2.53 mm; 95% CI 0.36 to 0.64 mm) in the horizontal plan (mesiodistal), and 0.37 ± 0.28 mm (range 0.0–1.3 mm; 95% CI 0.23 to 0.39 mm) in the vertical plan (apicocoronal). Comparing the mean value of the control group (closed metallic sleeves) with mean valueof the closed sleeves of the test group, there was a statistically significant difference in angle (P =0.0063) and in the vertical plan (p = 0.0126), with lower values in the test group. However, there was
not a statistically significant difference in the horizontal plan (p = 0.7546) (Table 1).
Sub-group analysis relieved a mean error in angle of 3.3 ± 3.1° (range 0.2–11.8°; 95% CI 1.1 to4.1°) with open sleeves and 1.35 ± 1.57° (range 0.1–5.9°; 95% CI 0.19 to 1.25°) with closed sleeves; thedifference was statistically significant (p = 0.0268). In the horizontal plan (mesio-distal), the meanerror was 0.87 ± 0.62 mm (range 0.2–2.53 mm; 95% CI 0.45 to 1.05 mm) with open sleeves and 0.51 ±0.38 mm (range 0.05–1.7 mm; 95% CI 0.29 to 0.55 mm) with closed sleeves; the difference was slightly
significant (p = 0.0477). In the vertical plan (apico-coronal), the mean error was 0.42 ± 0.33 mm (range
0.0–1.0 mm; 95% CI 0.19 to 0.51°) with open sleeves and 0.32 ± 0.24 mm (range 0.05–1.3 mm; 95% CI
0.22 to 0.38 mm) with closed sleeves; the difference was not statistically significant (p = 0.2929) (Table
2).
Table 1. Analysis of the final implant accuracy.

Angle (°)
Horizontal plan (mm)Vertical plan (mm)Control Group2.25 ± 1.41° (range 0.3–5.0°;
95% CI 0.52 to 1.65°)
0.52 ± 0.30 mm (range 0.1–1.1
mm; 95% CI 0.39 to 0.61 mm)
0.58 ± 0.44 mm (range 0.0–1.6
mm; 95% CI 0.44 to 0.76 mm)

Test Group
1.98 ± 2.38° (range 0.1–11.8°;
95% CI 0.13 to 1.47°)
0.61 ± 0.49 mm (range 0.05–2.53mm; 95% CI 0.36 to 0.64 mm)
0.37 ± 0.28 mm (range 0.0–1.3
mm; 95% CI 0.23 to 0.39 mm)Table 2. sub-group analysis of the final implant accuracy.

Angle (°)
Horizontal plan (mm)Vertical plan (mm)Open Sleeves
3.3 ± 3.1° (range 0.2–11.8°; 95%
CI 1.1 to 4.1°)
0.87 ± 0.62 mm (range 0.2–2.53mm; 95% CI 0.45 to 1.05 mm)
0.42 ± 0.33 mm (range 0.0–1.0
mm; 95% CI 0.19 to 0.51°)

Closed Sleeves
1.35 ± 1.57° (range 0.1–5.9°;
95% CI 0.19 to 1.25°)
0.51 ± 0.38 mm (range 0.05–1.7
mm; 95% CI 0.29 to 0.55 mm)
0.32 ± 0.24 mm (range 0.05–1.3
mm; 95% CI 0.22 to 0.38 mm)

7. Discussion
In regards to the accuracy of the digital guided implant surgery, several works have been
published in recent years with the aim to scientifically assess the accurateness of these techniques [8].
This randomized controlled trial was conducted with the aim to understand which kind of
surgical template could be preferable to rehabilitate partial edentulous patients between CAD/CAM
stereolithographic surgical guide with or without metallic sleeves. Furthermore, to evaluate possible
differences in accuracy between open versus closed sleeves in case of sleeve-designed templates.

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Both templates were able to achieve successful results, nevertheless, the null hypothesis that
there would be no differences in implant accuracy between templates with or without metallic sleeves
was partially rejected in favor of the hypothesis of differences. In fact, there was not a statisticallysignificant difference in the horizontal position between the virtual and planned implant position,
but there were statistically significant differences in angle and vertical discrepancy between thegroups, with more accurate values for tubeless templates. A possible explanation is that the holes
within the templates without metallic sleeves can be customized compared with standard metallic
sleeves. On the contrary, the metallic sleeves cannot be modified in case of collision with soft or hardtissues (Figure 7). Hence, a flap must be elevated to avoid misfitting of the surgical template during
its insertion. Otherwise, templates without metallic sleeves can have a customized fitting to thepatient’s anatomy, reducing the risk of losing accuracy.

Figure 7. Collision between the mesial side of the metallic sleeve and the patient’s anatomy.
Accordingly, in the templates without metallic sleeves, the contact points between the template
and the surgical drills with the entire space between the soft tissue and the templets results in a longer
guide compared to the 3.5 mm of standard metallic sleeves, plus 1 mm of the metallic reduction(Figure 8) in case of templates with metallic sleeves. This difference should allow for larger and morestable contact between the surgical template and the guided drills during the implant site
development, slightly reducing the overall wobbling of the guided drills. Indeed, a longer guiding
channel was found to reduce the angular deviations of implants in an in vitro investigation [9]. Lastly,
the implant mount drivers used in combination with surgical templates designed without metallic
sleeves (NoMount Driver and Fixture Driver, OneGuide Kit, Osstem) are designed without any stop
drill to the surgical guide. A stop drill should touch the surgical template on the side, creating a highpressure on the template that could generate a distortion of the same template, resulting in a
reduction of the final implant accuracy [7]. Another benefit of the surgical templates designed
without metallic sleeves was the reduced mesio-distal space. In fact, the metallic tubes have athickness of 0.5 mm, which could make it impossible for their use in the case of narrow mesio-distal
distance, such as in case of lower incisor or upper lateral incisors. In this case, the manual insertionof the implant after removing the surgical template is required.

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Figure 8. Differences between surgical templates with (lower) and without (upper) metallic
sleeves for a regular diameter implant of 7 mm length.
To the best of our knowledge, at the time of writing this article, this was the only RCT comparing
the accuracy of the surgical template with and without metallic sleeves. This makes it difficult toevaluate how the present results were consistent with other comparable studies. Nevertheless, recent
independent studies reported similar results in three-dimensional deviation between virtualplanning and final implant positions [10–12].
In the last years, high precise 3D printing machines have become popular in dentistry. Among
their applications, 3D printing machines can be used for surgical guide production, using
biocompatible acrylate materials. Surgical templates without metallic sleeves can be easily designed
and customized using dedicated software. This allows us to eliminate the metal tubes, and possibility
to reduce the tolerance between the printed sleeves and the drill-guiding keys [13].
In the present study, closed sleeves showed higher accuracy in the angle compared to the open
holes. According to reference [2], the maximum acceptable value for angle discrepancy should range
between 5.9 and 16.7° depending on the implant length and diameter. In the present study, a mean
discrepancy of 2.89 degrees was experienced. It should not involve clinical results because it is under
the safety margin of the virtual planning. Furthermore, the clinicians can choose between open or
closed sleeves, limiting the use of the open holes only in case with limited access in the posterior
areas. In fact, according to previous reports, limited access is one of the most experienced
complications when a surgical template was used [10,14], not allowing for a guided approach.
In an in vitro study by Schneider et al. it was shown that the tolerance of surgical instruments
and therefore the amount of lateral movement of drills can be significantly reduced by using amodified protocol for surgical guide production. This protocol includes CAD and the use of 3D
printing for surgical guide production without the use of any metal sleeves and with a more intimatecontact between the guide and the drill-guiding drill key [13].
Despite the evident benefits related to higher accuracy in the vertical plan and angle experienced
with the tubeless templates, there is still the need to clinically evaluate the long-term aesthetic andfunctional advantages. Particularly, it would be useful in the future to determine whether possible
wear of sleeve-designed templates may affect the final implant position. The main limitation of thepresent study was the small sample size. Nevertheless, this limitation can only be solved by
performing more similar trials with larger sample sizes, calculated based on these preliminary
results.
The positive side is that this RCT is the only one published to date that makes such a comparison.
Therefore, we hope that with this study as a precedent, other researchers will be stimulated to test
similar hypotheses. Such studies are difficult to conduct for the reasons previously mentioned but

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10 of 11are badly needed to understand the correct approach when dealing with teeth with an uncertain
prognosis.
8. Conclusions
With the limitation of the present randomized controlled trial, the surgical templates designed
without metallic sleeves were more accurate in the vertical plan and angle compared to theconventional template with metallic sleeves. Open sleeves should be used with caution in the molar
region only in case of reduced interarch space. Nevertheless, in both groups, the maximum
tridimensional deviations (angular, horizontal, vertical) did not exceed the safe offset of the software.
Further research with a higher sample size and longer follow-up are needed to confirm thesepreliminary results.
Author Contributions: M.T. had substantial contributions to the conception and design of the work; theacquisition analysis, and interpretation of the data; drafting the work and final approval of the version to be
published. M.M., Y.K., F.C., S.M.M., A.A., E.X., had substantial contributions to the acquisition of the data andfinal approval of the version to be published.
Funding: This research received no external funding.
Conflicts of Interest: Dr. Marco Tallarico and Yongjin Kim are consultant of the Osstem Implant and New
Ancorvis. Dr. Fabio Cocchi is consultant of New Ancorvis. However, this study was self-supported. Databelonged to the authors and by no means did the companies interfere with the conduct of the trial or the
publication of its results.

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© 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open accessarticle distributed under the terms and conditions of the Creative Commons Attribution(CC BY) license (http://creativecommons.org/licenses/by/4.0/).