Customized Impressions in Dental Implants - Soft Tissues Changes
Phase: NA
Conditions: Soft Tissue
Sponsor: Implantology Institute

Customized Impressions in Dental Implants - Soft Tissues Changes 
NCT03496428 
March 25th 2019 
 

Study Protocol with Statistical Analysis Plan 
2.1 | Patient selection 
This clinical study was conducted in full compliance with the Helsinki World Medical 
Association Declaration and its most recent amendments, being approved by the local ethics 
committee and registered at the U.S. National Library of Medicine ClinicalTrials.gov website 
under the reference number NCT03496428.  
The patients were chosen according to the following criteria: be at least 18 years of age; have 
at least one implant in the anterior maxilla with the indication for rehabilitation with a 
definitive implant supported crown; have two mesial and two distal adjacent teeth to the 
implant and be rehabilitated with a provisional implant supported crown for at least 3 months. 
As this was a pragmatic trial undertaken in a private clinical setting, patients with active 
smoking habits and evidence of parafunctional habits (ie, bruxism) were not excluded. Each 
patient was thoroughly informed about the procedures and each signed an informed consent 
agreement before entering the study. 
2.2 | Digital impression method 
Following the digital workflow method above (Figure 1), immediately after the removal of the 
provisional implant supported crown, digital impressions were the first to be obtained by an 
experienced clinician (DM) using an IOS (TRIOS, 3Shape, Copenhagen, Denmark) following the 
manufacturer recommended scanning sequence—first, the emergence profile was scanned 
right after the removal of the provisional crown (Figure 2A) to assess the emergence profile, 
after which a scan body was attached to the implant and an intraoral scan performed (Figure 
2B,C) to obtain the implant analogue alignment (Figure 2D). This IOS uses optical scanning with 
structured light on the principle of confocal microscopy, which does not require opacization of 
the model and produces 3D color images. The datasets from each scan were automatically 
saved as STL files. 
2.3 | Conventional impression method with coping customization, stone model fabrication, 
and digitalization 
In the same appointment, following the conventional workflow method (Figure 1), the CIIC was 
obtained by a previously described indirect technique. Briefly, the provisional crown was 
attached to an implant analog and placed into a polyvinyl siloxane impression material matrix 
(Affinis Putty, Coltene, Altstätten, Switzerland). The mold was obtained and the provisional 
returned to the patient's mouth to avoid soft tissue collapse. The impression coping was 
attached to the implant analog and filled with composite resin (Supreme 3M flow, 3M ESPE, 
Saint Paul, Minnesota), which took the 3D shape of the provisional soft tissue emergence, thus 
obtaining a CIIC (Figure 3). It was hand tightened and the proper seating was confirmed by 
visual and X-ray verification.  
A dual viscosity impression in one-step pick-up procedure was constructed using a polyvinyl 
siloxane material (Affinis Light Body Type 3, Putty soft Type 0, Coltene, Altstätten, Switzerland) 
in a standard plastic die lock tray (Single Use Perforated Impression Tray, Solo, J&S Davis, 
Stevenage, Herts, United Kingdom) prepared prior to loading into position. The impression was 
removed from the patient's mouth at least 2 minutes longer than the manufacturer's 
recommendation (2 minutes) and stored at 23ºC for 8 hours. The impression was poured with 
type IV dental stone (Top Super Hard Stone, class IV light yellow, Sherahard-rock, SHERA 

Werkstoff-Technologie GmbH & Co. KG, Lemförde, Germany) after mixing according to 
manufacturer instructions. The stone model was separated from the impression after 40 
minutes, stored at laboratory temperature (21ªC-23ªC) for 24 hours with no exposure to 
sunlight, and then scanned with the extraoral scanner D2000 (3Shape, Copenhagen, Denmark) 
with 5-megapixel high resolution cameras, multiline technology, and color scanning, achieving 
accuracy up to 5 μm, thus creating a STL file, which was previously calibrated according to 
manufacturer's instructions. This digitalized model was considered the reference. 
2.4 | 3D analysis 
Two STL files were obtained from each patient and, to allow for blinding, an external operator 
provided the STL files named with the patient reference number followed by the letter A 
(reference) or B (measured), keeping the correspondence code in an opaque sealed envelope 
until the end of the study. The files were imported into a reverse engineering software 
Geomagic Design X (3D Systems, Rock Hill, South Carolina) where they were cut to the zone of 
interest with the “Split” tool, removing unnecessary information and submitted to the “Healing 
Wizard” to reduce the number of distortions and small artifacts that could influence analysis. 
The generated datasets were then imported into the point-cloud inspection software 
Geomagic Control X (3D Systems).  
Software validation was performed as previously reported and repeated five times per scan 
(60 repetitions in total) to check software reliability, after which, virtual sagittal planes were 
created to guide the standardization of the locations of interest—through the cervicalapical 
axis of each of the five structures (four teeth and one implant), frontal planes over the 
mesiodistal axis of the implant and the two adjacent teeth, three transversal planes parallel 
between them in the four teeth, one at the gingival zenith and two others apically from the 
first with 1 mm spacing between them, and in the implant at emergence profile base level 
which was defined with a horizontal plane in the most apical identifiable point of the 
customized emergence profile, mucosal zenith, and in the middle of them. The locations were 
determined by the intersection between the described planes with the superimposed scans 
and the linear differences obtained by the 3D analysis program. The amount of deviation 
between methods was obtained by calculating the root mean square (RMS) by previously 
established methods. 
To evaluate the trueness between conventional (reference) and digital (comparison) 
impression methods, RMS distances were determined on both the buccal and palatal sides of 
the teeth, at cervical, incisal and in the middle point between them in each tooth (Bc, Bm, Bi, 
Pc, Pm, and Pi) and in the respective soft tissues (Gbc, Gbm, Gbz, Gpz, Gpm, and Gpc), as 
shown in Figure 4A. In the interproximal area of the implant (mesial and distal sides, Mip and 
Dip), the same locations as in buccal/palatal were measured (Figure 4B). In total, 304 
comparisons were performed in teeth's hard and soft tissues to assess trueness between 
methods.  
To evaluate the soft tissue replication between methods in periimplant soft tissues, the 
locations were measured at emergence profile base level (epbl), at the zenith (z), and middle 
(m) on the different sides of the implant mucosa: the buccal of the buccal mucosa (Bbm), the 
palatine of the buccal mucosa (Pbm), the buccal of the palatine mucosa (Bpm), the palatine of 
the palatine mucosa (Ppm), and the mesial and distal mucosa (Mm and Dm, respectively) 
(Figure 4C,D), corresponding to 18 locations per patient, amounting to a total of 108 

measurements. If the scans presented teeth with modifications, for prosthesis fabrication or 
distortions, the affected areas were not assessed.  
For each location with the “3D Compare” tool an area of interest with at least 1 mm2 was 
selected and used to measure the differences between methods, with three replicates 
performed per location. The analysis software automatically calculated RMS and the mean of 
the three replicates considered for statistical analysis.  
For optimal 3D visualization, a colored map was created with negative (blue, showing the 
comparison scan going inwards) and positive values (red, going outwards), as shown in Figure 
5. Specific parameters were set to the color scale, ranging from +1000 to −1000 μm and the 
best results ranging between +100 and −100 μm, highlighted in green. Values over or below 
the color scale's limits were presented in gray. 
2.5 | Statistical analysis 
Although no studies employing this technique were found in the literature, from a study on 
direct and indirect techniques in CIIC22 we expected a mean difference of 1 mm. A statistical 
power analysis was performed to determine the number of patients with an equivalence study 
design. With an α = .05, and a power of 0.80, the calculations revealed that at least six patients 
would be needed to be 95% sure that the limits of a two-sided 90% confidence interval would 
exclude a difference in means of more than 500 μm. 
Primary outcomes were defined as the variation in the RMS between the two methods in the 
hard (teeth) and soft (teeth and periimplant mucosa) tissues' measurements. Descriptive 
statistic (means and 95% confidence intervals) was performed on the studied parameters. 
Normality of distribution was tested by the Shapiro-Wilk Normality test and the Levene test 
was used to assess the equality of variance. According to the results, the nonparametric Mann-
Whitney U and Kruskal-Wallis tests were used to compare RMS between methods in hard and 
soft tissues (α = .05). When performing multiple comparisons, the P-value was adjusted 
according to the Bonferroni Correction method. 
Effect size between soft tissues' measurements (tooth vs implants) was calculated as Hedges' g 
± 95% confidence interval as a result of different sample sizes.27–30 Effect size was considered 
as small (<0.3), moderate (0.3-0.8), or large (≥0.8) effect. The level of significance was set at 
.05. All calculations were carried out with statistical software (SPSS 25.0, SPSS Inc., Chicago, 
Illinois).