Predictable Full Digital Workflow Using Stackable Surgical Templates for Complete Dental Arch Rehabilitation with Implant-Supported Fixed Restorations—Case Series and Proof of Concept

Abstract

Background: In recent years, advancements in digital dentistry have provided new opportunities for more predictable and efficient treatment options, particularly in patients with failing dentition. This study aimed to evaluate the effectiveness and accuracy of a fully digital workflow using stackable surgical templates for complete dental arch rehabilitation with implant-supported fixed restorations. Methods: Four patients, comprising two males and two females with a mean age of 66 years, were included in this case series. Each patient underwent meticulous digital planning, including CBCT and intraoral scanning, to create a virtual patient for preoperative assessment and virtual treatment planning. The assessment of the trueness of implant positioning was conducted in Geomagic Control X software (version 2017.0.3) by referencing anatomical landmarks from both the preoperative and one-year postoperative CBCT scans. Results: A total of 25 dental implants were placed in the maxilla, followed by the installation of long-term provisional restorations. The results showed minimal deviation between the planned and actual implant positions, with mean 3D coronal, apical, and angular discrepancies of 0.87 mm, 2.04 mm, and 2.67°, respectively. All implants achieved successful osseointegration, and no failures were recorded, resulting in a 100% survival rate at the one-year follow-up. Patients reported high satisfaction with both the esthetic and functional outcomes based on their subjective feedback. Conclusions: The findings suggest that the use of a fully digital workflow with stackable surgical templates is a reliable and effective approach for immediate implant placement and prosthetic rehabilitation, enhancing treatment precision and patient comfort.

Full text

Citation: Cristache, C.M.; Burlacu
Vatamanu, O.E.; Butnarasu, C.C.;
Mihut, T.; Sgiea, E.D. Predictable Full
Digital Workflow Using Stackable
Surgical Templates for Complete
Dental Arch Rehabilitation with
Implant-Supported Fixed
Restorations—Case Series and Proof
of Concept. Dent. J. 2024,12, 347.
https://doi.org/10.3390/dj12110347
Academic Editor: Daniele Botticelli
Received: 28 August 2024
Revised: 2 October 2024
Accepted: 27 October 2024
Published: 30 October 2024
Copyright: © 2024 by the authors.
Licensee MDPI, Basel, Switzerland.
This article is an open access article
distributed under the terms and
conditions of the Creative Commons
Attribution (CC BY) license (https://
creativecommons.org/licenses/by/
4.0/).
dentistry journal
Article
Predictable Full Digital Workflow Using Stackable Surgical
Templates for Complete Dental Arch Rehabilitation with
Implant-Supported Fixed Restorations—Case Series and Proof
of Concept
Corina Marilena Cristache
1,
* , Oana Elena Burlacu Vatamanu
2,
*, Cristian Corneliu Butnarasu
3
, Tamara Mihut
2
and Eliza Denisa Sgiea 2
1Department of Dental Techniques, “Carol Davila” University of Medicine and Pharmacy, 8 Eroii Sanitari
Blvd., 050474 Bucharest, Romania
2Doctoral School, “Carol Davila” University of Medicine and Pharmacy, 37 Dionisie Lupu Street,
020021 Bucharest, Romania; tamara.mihut@drd.umfcd.ro (T.M.); eliza-denisa.sgiea@drd.umfcd.ro (E.D.S.)
3Megagen Dental Laboratory, 38 Delea Noua Street, 030925 Bucharest, Romania
*
Correspondence: corina.cristache@umfcd.ro (C.M.C.); oana-elena.burlacu-vatamanu@drd.umfcd.ro (O.E.B.V.)
Abstract: Background: In recent years, advancements in digital dentistry have provided new op-
portunities for more predictable and efficient treatment options, particularly in patients with failing
dentition. This study aimed to evaluate the effectiveness and accuracy of a fully digital workflow
using stackable surgical templates for complete dental arch rehabilitation with implant-supported
fixed restorations. Methods: Four patients, comprising two males and two females with a mean age
of 66 years, were included in this case series. Each patient underwent meticulous digital planning,
including CBCT and intraoral scanning, to create a virtual patient for preoperative assessment and
virtual treatment planning. The assessment of the trueness of implant positioning was conducted
in Geomagic Control X software (version 2017.0.3) by referencing anatomical landmarks from both
the preoperative and one-year postoperative CBCT scans. Results: A total of 25 dental implants
were placed in the maxilla, followed by the installation of long-term provisional restorations. The
results showed minimal deviation between the planned and actual implant positions, with mean
3D coronal, apical, and angular discrepancies of 0.87 mm, 2.04 mm, and 2.67
◦
, respectively. All
implants achieved successful osseointegration, and no failures were recorded, resulting in a 100%
survival rate at the one-year follow-up. Patients reported high satisfaction with both the esthetic and
functional outcomes based on their subjective feedback. Conclusions: The findings suggest that the
use of a fully digital workflow with stackable surgical templates is a reliable and effective approach
for immediate implant placement and prosthetic rehabilitation, enhancing treatment precision and
patient comfort.
Keywords: full digital workflow; stackable guides; virtual patient; edentulous maxilla; stackable
surgical template; immediate fixed prosthesis
1. Introduction
Oral rehabilitation with dental implants has witnessed significant advancements over
the past decades, particularly in the treatment of patients with terminal dentition [
1
].
Failing/terminal dentition, characterized by the end-stage of dental diseases leading to
masticatory function loss, dentoalveolar alterations, teeth migrations, and esthetic im-
pairment, poses a significant challenge in the field of dentistry. The primary obstacle in
creating treatment plans for patients with failing dentition is the challenge of evaluating
the proposed orientation of the occlusal plane, the positioning of the incisal edge, and
the maxillomandibular relationship before implant surgery [
2
]. Digital advancements
Dent. J. 2024,12, 347. https://doi.org/10.3390/dj12110347 https://www.mdpi.com/journal/dentistry

Dent. J. 2024,12, 347 2 of 19
introduce valuable resources for the design and rehabilitation processes of these patients’
smiles, and masticatory function, incorporating the concept of a virtual dental patient [
3
].
These advancements include software programs available on the market that enable, in
addition to surgical planning and prosthetic wax-up, the simulation of digital smile design,
promoting better collaboration between patients, clinicians, and the interdisciplinary team
through the use of a virtual dental patient model [3,4].
Despite the progress in dental implantology and restorative techniques, several chal-
lenges persist in achieving predictable outcomes that satisfy both esthetic and functional
criteria. Most of the challenge comes from accurately transposing the planned implants
into position in the patient’s oral cavity [
5
]. While digital planning offers precision and
detailed guidance, the execution in a real-world setting introduces several variables that
can compromise the intended outcome. Factors such as patient anatomy, bone density
variations, surgical technique, and intraoperative adjustments can all impact the accurate
transfer of the digital plan to the clinical setting. These hurdles emphasize the need for
continuous refinement in both digital tools and surgical protocols to bridge the gap between
planning and practice, ensuring optimal results for patients [
6
,
7
]. Traditional approaches
often involve extensive treatment times, multiple procedures, and significant discomfort
for the patient, alongside the challenge of achieving a harmonious integration with the
patient’s dental and facial aesthetics [8].
In response to these challenges, the digitalization of dental processes has emerged
as a pivotal evolution, offering greater precision, shorter treatment times, and improved
patient outcomes. This approach leverages digital imaging, computer-aided design and
manufacturing (CAD/CAM), and digital treatment planning to offer a streamlined, accu-
rate, and minimally invasive treatment pathway. Among the most notable innovations is
the development of a predictable full digital workflow using stackable surgical templates
for complete arch rehabilitation with implant-supported fixed restorations [9,10].
The stackable guide protocol includes the following guides [11]:
-
Base guide: fits in the vestibule of the dental arch and is stabilized with a minimum
of three transverse pins (one anterior and two lateral) [
8
]. This base remains in place
until the provisional prosthesis is fixed on the inserted implants;
-
Tooth-supported surgical implant guide: used for implant placement when some of
the remaining teeth are utilized for guide stabilization before extraction [10];
-
Implant-supported guide: used for the insertion of all remaining implants after the
extraction of teeth;
-
Mucosal-supported guide: used for dental implant placement when the remaining
teeth are few or absent;
- Bone reduction guide: if necessary, this guide is used for bone remodeling;
- Prosthetic guide: used for the positioning of the provisional fixed restoration.
Although numerous studies on the use of stackable guides have been published,
most are limited to clinical case reports [
12
–
15
], with little focus on a comprehensive
digital workflow that includes virtual patient creation. These existing reports often lack
consistency in methodologies, making it difficult to assess the generalizability of their
findings [
8
]. As the application of stackable guides continues to grow, there is a clear need
for a standardized, repeatable digital protocol that can ensure implant placement accuracy
across diverse clinical scenarios. The current literature remains scarce in describing a fully
digital workflow that includes a thorough accuracy assessment of sequential stackable
guides, underscoring the importance of establishing a more reliable and reproducible
approach. Moreover, the criteria for determining the necessity of bone reduction in complete
arch rehabilitation remain underexplored in the literature. The decision-making process for
bone reduction, particularly in the context of immediate implant placement and provisional
restoration fitting, plays a critical role in treatment outcomes. This unresolved issue is one
that our study aims to address by providing a clearer framework for evaluating when and
if bone reduction is necessary to achieve optimal restoration outcomes.

Dent. J. 2024,12, 347 3 of 19
Therefore, the aim of this study was to describe a predictable, fully digital protocol for
immediate implant placement and prosthetic rehabilitation of a complete maxillary dental
arch, and to evaluate its accuracy across four consecutive cases, with particular emphasis
on the role of the virtual dental patient in achieving successful clinical outcomes.
2. Materials and Methods
The study was conducted in accordance with ethical principles including the World
Medical Association Declaration of Helsinki, the Belmont report, the Council for Interna-
tional Organizations of Medical Sciences (CIOMS) guidelines, and the International Confer-
ence on Harmonization in Good Clinical Practice (ICH-GCP). It received approval from the
Ethics Committee of the ‘Carol Davila’ University of Medicine and Pharmacy (36368/2023,
Bucharest, Romania). The research took place in a partner private clinic affiliated with
the ‘Carol Davila’ University of Medicine and Pharmacy between January 2023 and June
2024. Four consecutive patients with failing maxillary dentition were enrolled in the present
study [11]. A detailed presentation of one patient is in the Supplementary Materials.
The enrolled patients were subject to the following inclusion criteria: either experienc-
ing failure of maxillary dentition or failing maxillary prosthetic restoration, necessitating
and agreeing to full implants supported fixed rehabilitation; possessing good overall health
with no contraindications for implant surgery; and exhibiting good mental health and the
ability to fully comprehend and complete the consent form.
The exclusion criteria were: limited bone volume, requiring bone grafting; poor oral
hygiene and lack of compliance; limited mount opening; and Parkinson’s disease.
2.1. Data Collection
The following data were mandatory for the creation of the virtual patient:
-
Digital impression of the dental arches and occlusion registration in Centric Relation
(CR) or intercuspal position (ICP) using Carestream 3600 (Carestream Dental LLC,
Atlanta, GA, USA) intraoral surface scanner operated by DEXIS IS ScanFlow 1.0.10.
(Envista Holdings Corporation Headquarters, Brea, CA, USA) and saved as STL
(stereolithography) file format.
-
CBCT, saved in Digital Imaging and Communications in Medicine (DICOM) format
with a large field of view (FoV) 20
×
19 using NewTom™ VGi evo (NewTom Cefla S.C.,
Imola, Italy), performed in CR or ICP using a standardized protocol. Two scenarios
were used to facilitate predictable file superimposing, depending on the number and
position of the remaining teeth:
(a)
for existing teeth, with no provisional removable prosthesis, three dental cotton rolls
were placed in the buccal vestibule to move the lip away from the teeth, according to
the “lip-lift” technique [16].
(b)
for a reduced number of remaining teeth with an existing removable denture, radio-
opaque composite spheres were placed on the existing denture to serve as markers.
-
Facial scanning, performed with Bellus Arc 1 (Bellus3D Inc., Campbell, CA, USA)
surface scanner, saved as OBJ (3D file format created by Wavefront Technologies,
Paramount, CA, USA).
-
One single operator performed intraoral scanning and facial scanning to ensure
consistency.
2.2. Protocol for Virtual Dental Patient Creation
For treatment planning and surgical template design, R2Gate™ software, version
2.0.0 (MegaGen, Daegu, Republic of Korea) was used. The software includes 10 features
with corresponding steps: (1) CBCT and STL matching; (2) fine-tuning model matching
and fine-tuning facial scan matching; (3) CBCT reorientation and digital facebow; (4) hard
tissue cephalometric analysis; (5) 3D smile design; (6) wax-up design; (7) mandibular

Dent. J. 2024,12, 347 4 of 19
nerve tracing; (8) implant surgery; (9) quick guide and digital mounting; (10) adjusting the
vertical dimension (VD) and Face Guide view [17] (Figure 1).
Dent. J. 2024, 12, x FOR PEER REVIEW 4 of 20
For treatment planning and surgical template design, R2Gate™ software, version
2.0.0 (MegaGen, Daegu, Republic of Korea) was used. The software includes 10 features
with corresponding steps: (1) CBCT and STL matching; (2) fine-tuning model matching
and fine-tuning facial scan matching; (3) CBCT reorientation and digital facebow; (4) hard
tissue cephalometric analysis; (5) 3D smile design; (6) wax-up design; (7) mandibular
nerve tracing; (8) implant surgery; (9) quick guide and digital mounting; (10) adjusting
the vertical dimension (VD) and Face Guide view [17] (Figure 1).
Figure 1. Overview of the steps involved in using R2Gate™ software for virtual patient creation and
treatment planning.
2.2.1. Importing Data
All data collected are imported into a single folder with the patients name in the
R2Data file. To ensure compatibility with the software, multiframe DICOM files were
exported following the CBCT scan.
Virtual patient creation starts with step no. 3, where CBCT is arranged to be centered
and symmetrical and the Frankfort plane (drawn from Po—Porion to Or—Orbitale) is set
as a horizontal plane (Figure 2).
(a) (b)
Figure 2. CBCT re-orientation (Patient #1): (a) frontal alignment of CBCT—centering and orienting
with the orbital line parallel to the horizontal line; (b) lateral view with the Frankfort plane set as
the horizontal plane.
2.2.2. Merging Data
In steps 1 and 2, the intraoral (IOS) and facial scans are imported and matched with
the CBCT file (Figure 3). The 3D alignment of the files, particularly between the CBCT and
Figure 1. Overview of the steps involved in using R2Gate™ software for virtual patient creation and
treatment planning.
2.2.1. Importing Data
All data collected are imported into a single folder with the patient’s name in the
R2Data file. To ensure compatibility with the software, multiframe DICOM files were
exported following the CBCT scan.
Virtual patient creation starts with step no. 3, where CBCT is arranged to be centered
and symmetrical and the Frankfort plane (drawn from Po—Porion to Or—Orbitale) is set
as a horizontal plane (Figure 2).
Dent. J. 2024, 12, x FOR PEER REVIEW 4 of 20
For treatment planning and surgical template design, R2Gate™ software, version
2.0.0 (MegaGen, Daegu, Republic of Korea) was used. The software includes 10 features
with corresponding steps: (1) CBCT and STL matching; (2) fine-tuning model matching
and fine-tuning facial scan matching; (3) CBCT reorientation and digital facebow; (4) hard
tissue cephalometric analysis; (5) 3D smile design; (6) wax-up design; (7) mandibular
nerve tracing; (8) implant surgery; (9) quick guide and digital mounting; (10) adjusting
the vertical dimension (VD) and Face Guide view [17] (Figure 1).
Figure 1. Overview of the steps involved in using R2Gate™ software for virtual patient creation and
treatment planning.
2.2.1. Importing Data
All data collected are imported into a single folder with the patients name in the
R2Data file. To ensure compatibility with the software, multiframe DICOM files were
exported following the CBCT scan.
Virtual patient creation starts with step no. 3, where CBCT is arranged to be centered
and symmetrical and the Frankfort plane (drawn from Po—Porion to Or—Orbitale) is set
as a horizontal plane (Figure 2).
(a) (b)
Figure 2. CBCT re-orientation (Patient #1): (a) frontal alignment of CBCT—centering and orienting
with the orbital line parallel to the horizontal line; (b) lateral view with the Frankfort plane set as
the horizontal plane.
2.2.2. Merging Data
In steps 1 and 2, the intraoral (IOS) and facial scans are imported and matched with
the CBCT file (Figure 3). The 3D alignment of the files, particularly between the CBCT and
Figure 2. CBCT re-orientation (Patient #1): (a) frontal alignment of CBCT—centering and orienting
with the orbital line parallel to the horizontal line; (b) lateral view with the Frankfort plane set as the
horizontal plane.
2.2.2. Merging Data
In steps 1 and 2, the intraoral (IOS) and facial scans are imported and matched with the
CBCT file (Figure 3). The 3D alignment of the files, particularly between the CBCT and IOS,
was completed in two stages: first, automatically by setting reference points (Figure 3a),
and then manually for fine alignment (Figure 3b).

Dent. J. 2024,12, 347 5 of 19
Dent. J. 2024, 12, x FOR PEER REVIEW 5 of 20
IOS, was completed in two stages: first, automatically by seing reference points (Figure
3a), and then manually for fine alignment (Figure 3b).
(a) (b)
Figure 3. (Patient#1): (a) DICOM files from the CBCT, STL files from the intraoral scan (edentulous
maxilla with preexisting adapted denture), and OBJ files from facial scanning were imported into
the software; (b) fine manual alignment of the DICOM and STL files.
2.2.3. Cephalometric Analysis
A cephalometric analysis is then performed (step no. 4) to evaluate the skeletal
paern of the patient for treatment planning and to verify the occlusal vertical dimension
(OVD) and the preexisting occlusal plane direction.
From the available options in the software, the AP (anteroposterior) position analysis
of the maxilla and mandible (Mx Mn) can be selected to calculate the A-Nasion-B (ANB)
angle. Before the measurement, several key points were marked on the 2D sagial
midsection of the CBCT: nasion (N), sella (S), orbitale (Or), subspinale (A), upper incisor
root apex (UIA), upper incisor incisal edge (UIT), lower incisor incisal edge (LIT), lower
incisor root apex (LIA), supramentale (B), and pogonion (Pog) (Figure 4). After these
landmarks were set in the specified order, the software automatically calculated various
angles. The sagial jaw relationship was then classified based on the ANB angle: normal
skeletal class I (0.3° to +4.8°), skeletal class II (>+4.8°), and skeletal class III (<0.3°) [18–20].
For edentulous patients, the reference dental points are marked based on the wax-up
of the final restoration or the existing removable denture if it effectively restores the
patients esthetic function. The position of the root apex is approximate, and as a result,
the ANB angle value should be considered indicative rather than precise.
Figure 3. (Patient#1): (a) DICOM files from the CBCT, STL files from the intraoral scan (edentulous
maxilla with preexisting adapted denture), and OBJ files from facial scanning were imported into the
software; (b) fine manual alignment of the DICOM and STL files.
2.2.3. Cephalometric Analysis
A cephalometric analysis is then performed (step no. 4) to evaluate the skeletal pattern
of the patient for treatment planning and to verify the occlusal vertical dimension (OVD)
and the preexisting occlusal plane direction.
From the available options in the software, the AP (anteroposterior) position analysis of
the maxilla and mandible (Mx Mn) can be selected to calculate the A-Nasion-B (ANB) angle.
Before the measurement, several key points were marked on the 2D sagittal midsection of
the CBCT: nasion (N), sella (S), orbitale (Or), subspinale (A), upper incisor root apex (UIA),
upper incisor incisal edge (UIT), lower incisor incisal edge (LIT), lower incisor root apex
(LIA), supramentale (B), and pogonion (Pog) (Figure 4). After these landmarks were set in
the specified order, the software automatically calculated various angles. The sagittal jaw
relationship was then classified based on the ANB angle: normal skeletal class I (0.3
◦
to
+4.8◦), skeletal class II (>+4.8◦), and skeletal class III (<0.3◦) [18–20].
Dent. J. 2024, 12, x FOR PEER REVIEW 5 of 20
IOS, was completed in two stages: first, automatically by seing reference points (Figure
3a), and then manually for fine alignment (Figure 3b).
(a) (b)
Figure 3. (Patient#1): (a) DICOM files from the CBCT, STL files from the intraoral scan (edentulous
maxilla with preexisting adapted denture), and OBJ files from facial scanning were imported into
the software; (b) fine manual alignment of the DICOM and STL files.
2.2.3. Cephalometric Analysis
A cephalometric analysis is then performed (step no. 4) to evaluate the skeletal
paern of the patient for treatment planning and to verify the occlusal vertical dimension
(OVD) and the preexisting occlusal plane direction.
From the available options in the software, the AP (anteroposterior) position analysis
of the maxilla and mandible (Mx Mn) can be selected to calculate the A-Nasion-B (ANB)
angle. Before the measurement, several key points were marked on the 2D sagial
midsection of the CBCT: nasion (N), sella (S), orbitale (Or), subspinale (A), upper incisor
root apex (UIA), upper incisor incisal edge (UIT), lower incisor incisal edge (LIT), lower
incisor root apex (LIA), supramentale (B), and pogonion (Pog) (Figure 4). After these
landmarks were set in the specified order, the software automatically calculated various
angles. The sagial jaw relationship was then classified based on the ANB angle: normal
skeletal class I (0.3° to +4.8°), skeletal class II (>+4.8°), and skeletal class III (<0.3°) [18–20].
For edentulous patients, the reference dental points are marked based on the wax-up
of the final restoration or the existing removable denture if it effectively restores the
patients esthetic function. The position of the root apex is approximate, and as a result,
the ANB angle value should be considered indicative rather than precise.
Figure 4. (Patient #1): Cephalometric analysis of the anteroposterior (AP) position of the maxilla
(Mx) and mandible (Mn) for determining the A-Nasion-B (ANB) angle. Cephalometriclandmarks are
displayed in the image on the right. N = nasion, S = sella, Or = orbitale, A = subspinale,
UIA = upper
incisor root apex, UIT = upper incisor incisal edge, LIT = lower incisor incisal edge, LIA = lower
incisor root apex, B = supramentale, Pog = pogonion.

Dent. J. 2024,12, 347 6 of 19
For edentulous patients, the reference dental points are marked based on the wax-up of
the final restoration or the existing removable denture if it effectively restores the patient’s
esthetic function. The position of the root apex is approximate, and as a result, the ANB
angle value should be considered indicative rather than precise.
Based on the cephalometric analysis, the positions of point A and Pogonion (Pg)
relative to the McNamara line are evaluated to assess the maxillary and mandibular
positions in relation to the cranial base [
21
,
22
]. The McNamara line is defined as the
perpendicular line drawn from the nasion to the Frankfort plane. In a normal maxilla, point
A should lie on or slightly anterior (by approximately 1 mm) to the McNamara line. A
negative value indicates a retruded maxilla, while a positive value indicates a protruded
maxilla. Similarly, the analysis involving the position of point Pg relative to the McNamara
line (normal range:
−
4 to 0 mm for females and
−
2 to +2 mm for males) interprets positive
values as indicating a protruded mandible and negative values as indicating a retruded
mandible [
21
,
22
]. The protrusion or retrusion of the maxilla and mandible, along with
the occlusal vertical dimension and extent of bone atrophy, will guide the selection of the
ideal type of restoration and the classification of the case according to the Prosthodontic
Classification proposed by Misch (FP1, FP2, FP3, RP4, and RP5) [23].
For the assessment of the appropriate vertical dimension and occlusal plane in patients
with preexisting dentition or to verify the accuracy of provisional restorations, Kim’s
analysis was employed. This analysis involves setting the following reference points:
Nasion (N), Sella (S), Orbitale (Or), Porion (Po), Point A, the root apex of the upper incisor,
the incisal edge of the upper incisor, the posterior point of occlusion, Pogonion (Pog),
Menton (Me), and Gonion (Go) (Figure 5). The Y-angle, which is the angle between the
Frankfort plane and the Sella–Menton (S-Me) line, serves as an indicator for the correct
occlusal vertical dimension (OVD) setting. According to Down’s normative values for
Caucasians, the average Y-angle is 59.4◦(ranging from 53◦to 66◦) [24].
Dent. J. 2024, 12, x FOR PEER REVIEW 6 of 20
Figure 4. (Patient #1): Cephalometric analysis of the anteroposterior (AP) position of the maxilla
(Mx) and mandible (Mn) for determining the A-Nasion-B (ANB) angle. Cephalometriclandmarks
are displayed in the image on the right. N = nasion, S = sella, Or = orbitale, A = subspinale, UIA =
upper incisor root apex, UIT = upper incisor incisal edge, LIT = lower incisor incisal edge, LIA =
lower incisor root apex, B = supramentale, Pog = pogonion.
Based on the cephalometric analysis, the positions of point A and Pogonion (Pg)
relative to the McNamara line are evaluated to assess the maxillary and mandibular
positions in relation to the cranial base [21,22]. The McNamara line is defined as the
perpendicular line drawn from the nasion to the Frankfort plane. In a normal maxilla,
point A should lie on or slightly anterior (by approximately 1 mm) to the McNamara line.
A negative value indicates a retruded maxilla, while a positive value indicates a protruded
maxilla. Similarly, the analysis involving the position of point Pg relative to the
McNamara line (normal range: −4 to 0 mm for females and −2 to +2 mm for males)
interprets positive values as indicating a protruded mandible and negative values as
indicating a retruded mandible [21,22]. The protrusion or retrusion of the maxilla and
mandible, along with the occlusal vertical dimension and extent of bone atrophy, will
guide the selection of the ideal type of restoration and the classification of the case
according to the Prosthodontic Classification proposed by Misch (FP1, FP2, FP3, RP4, and
RP5) [23].
For the assessment of the appropriate vertical dimension and occlusal plane in
patients with preexisting dentition or to verify the accuracy of provisional restorations,
Kims analysis was employed. This analysis involves seing the following reference
points: Nasion (N), Sella (S), Orbitale (Or), Porion (Po), Point A, the root apex of the upper
incisor, the incisal edge of the upper incisor, the posterior point of occlusion, Pogonion
(Pog), Menton (Me), and Gonion (Go) (Figure 5). The Y-angle, which is the angle between
the Frankfort plane and the Sella–Menton (S-Me) line, serves as an indicator for the correct
occlusal vertical dimension (OVD) seing. According to Downs normative values for
Caucasians, the average Y-angle is 59.4° (ranging from 53° to 66°) [24].
The occlusal plane angle (OP) (Figure 5) can be used to assess the appropriateness of
the preexisting occlusal plane or to verify the direction of the newly established occlusal
plane. Downs analysis indicates that, for Caucasians, the occlusal plane angle should
typically be around 14.5° (with a range of 3.5° to 20°) [24].
Figure 5. (Patient #2): Kims cephalometric analysis for assessing the positioning of the maxilla in
relation to the McNamara line, as well as evaluating the Y-angle and occlusal plane (OP) angle for
precise treatment planning. N = Nasion, S = Sella, Or = Orbitale, Po = Porion, A = Point A, 6 = the
Figure 5. (Patient #2): Kim’s cephalometric analysis for assessing the positioning of the maxilla in
relation to the McNamara line, as well as evaluating the Y-angle and occlusal plane (OP) angle for
precise treatment planning. N = Nasion, S = Sella, Or = Orbitale, Po = Porion, A = Point A, 6 = the
root apex of the upper incisor, 7 = the incisal edge of the upper incisor, 8 = the posterior point of
occlusion, Pog = Pogonion, Me = Menton, Go = Gonion.
The occlusal plane angle (OP) (Figure 5) can be used to assess the appropriateness of
the preexisting occlusal plane or to verify the direction of the newly established occlusal
plane. Down’s analysis indicates that, for Caucasians, the occlusal plane angle should
typically be around 14.5◦(with a range of 3.5◦to 20◦) [24].

Dent. J. 2024,12, 347 7 of 19
2.2.4. Digital Facebow
In step #3 of the R2Gate software (CBCT reorientation and Digital Facebow), the center
of the mandibular condyle is identified, and an appropriate type of articulator is selected
from the available options. For all cases, the Artex articulator was chosen (Figure 6). The
hinge axis of the selected articulator is then aligned with the hinge axis of the condyles. As
shown in Figure 6a, the mounting plate of the articulator and the hinge axis are aligned
with the maxillary model, and this configuration can be saved as an STL file for transfer to
EXOCAD version 3.1 Rijeka (Exocad GmbH, Darmstadt, Germany) software. In EXOCAD,
the hinge axis and mounting plate corresponding to those of the Artex articulator (Amann
Girrbach AG, Mäder, Österreich) are used for the digital mounting of the models and for
designing the prosthetic provisional (Figure 6b).
Dent. J. 2024, 12, x FOR PEER REVIEW 7 of 20
root apex of the upper incisor, 7 = the incisal edge of the upper incisor, 8 = the posterior point of
occlusion, Pog = Pogonion, Me = Menton, Go = Gonion.
2.2.4. Digital Facebow
In step #3 of the R2Gate software (CBCT reorientation and Digital Facebow), the
center of the mandibular condyle is identified, and an appropriate type of articulator is
selected from the available options. For all cases, the Artex articulator was chosen (Figure
6). The hinge axis of the selected articulator is then aligned with the hinge axis of the
condyles. As shown in Figure 6a, the mounting plate of the articulator and the hinge axis
are aligned with the maxillary model, and this configuration can be saved as an STL file
for transfer to EXOCAD version 3.1 Rijeka (Exocad GmbH, Darmstadt, Germany)
software. In EXOCAD, the hinge axis and mounting plate corresponding to those of the
Artex articulator (Amann Girrbach AG, Mäder, Österreich) are used for the digital
mounting of the models and for designing the prosthetic provisional (Figure 6b).
(a) (b)
Figure 6. (Patient #2): Digital Mounting in the Articulator: (a) Artex articulator with the Frankfort
horizontal plane selected as the reference plane in R2Gate™ software; (b) mounting imported as an
STL file into EXOCAD software for the design of the provisional restoration.
2.2.5. Occlusal Plane Seing
Additionally, in step #3 of the software, the central incisor edge is identified using
the central cursor, and one of three available options for the digital occlusal plane is
selected. These options correspond to different craniofacial types: 180 R for a wide
(brachycephalic) type, 200 R for a normal (mesocephalic) type, and 220 R for a narrow
(dolichocephalic) type (Figure 7). After importing, the occlusal plane can be adjusted, and
the STL file is then exported to EXOCAD for provisional prosthesis design.
Figure 6. (Patient #2): Digital Mounting in the Articulator: (a) Artex articulator with the Frankfort
horizontal plane selected as the reference plane in R2Gate™ software; (b) mounting imported as an
STL file into EXOCAD software for the design of the provisional restoration.
2.2.5. Occlusal Plane Setting
Additionally, in step #3 of the software, the central incisor edge is identified using the
central cursor, and one of three available options for the digital occlusal plane is selected.
These options correspond to different craniofacial types: 180 R for a wide (brachycephalic)
type, 200 R for a normal (mesocephalic) type, and 220 R for a narrow (dolichocephalic)
type (Figure 7). After importing, the occlusal plane can be adjusted, and the STL file is then
exported to EXOCAD for provisional prosthesis design.
Dent. J. 2024, 12, x FOR PEER REVIEW 8 of 20
Figure 7. (Patient #2): Occlusal plane alignment using R2Gate™ software.
2.3. Prosthetically Driven Treatment Planning
2.3.1. Design of the Provisional Restoration
STL files of the maxilla and mandible IOS, OBJ file of the facial scan, virtual
articulator mounting, and occlusal plane STL files were imported into EXOCAD software
to design the provisional screw-retained prosthetic restoration (Figure 8).
Figure 8. (Patient #2): Digital Smile Design in EXOCAD software for selecting anterior teeth,
followed by designing the provisional restoration based on previously obtained information.
2.3.2. Implants Planning
The STL file of the provisional restoration is imported into the R2Gate software,
where the number, length, diameter, and position of the implants are planned according
to the final restoration design. To facilitate bone quality assessment, the softwares
“Digital Eye” option automatically converts the CBCT grayscale into five basic colors for
preoperative bone density evaluation [5,25]. The implant planning data is then exported
as an STL file for guide design. For patients with remaining teeth, a stepwise approach is
planned for extraction and implant insertion, initially using a tooth-supported surgical
guide. The software also provides a drilling sequence based on bone density and implant
design. Figure 9 shows the treatment planning for a patient with a single remaining tooth,
where one implant insertion guide was used. Figure 10 displays a drilling report for two
Figure 7. (Patient #2): Occlusal plane alignment using R2Gate™ software.

Dent. J. 2024,12, 347 8 of 19
2.3. Prosthetically Driven Treatment Planning
2.3.1. Design of the Provisional Restoration
STL files of the maxilla and mandible IOS, OBJ file of the facial scan, virtual articulator
mounting, and occlusal plane STL files were imported into EXOCAD software to design
the provisional screw-retained prosthetic restoration (Figure 8).
Dent. J. 2024, 12, x FOR PEER REVIEW 8 of 20
Figure 7. (Patient #2): Occlusal plane alignment using R2Gate™ software.
2.3. Prosthetically Driven Treatment Planning
2.3.1. Design of the Provisional Restoration
STL files of the maxilla and mandible IOS, OBJ file of the facial scan, virtual
articulator mounting, and occlusal plane STL files were imported into EXOCAD software
to design the provisional screw-retained prosthetic restoration (Figure 8).
Figure 8. (Patient #2): Digital Smile Design in EXOCAD software for selecting anterior teeth,
followed by designing the provisional restoration based on previously obtained information.
2.3.2. Implants Planning
The STL file of the provisional restoration is imported into the R2Gate software,
where the number, length, diameter, and position of the implants are planned according
to the final restoration design. To facilitate bone quality assessment, the softwares
“Digital Eye” option automatically converts the CBCT grayscale into five basic colors for
preoperative bone density evaluation [5,25]. The implant planning data is then exported
as an STL file for guide design. For patients with remaining teeth, a stepwise approach is
planned for extraction and implant insertion, initially using a tooth-supported surgical
guide. The software also provides a drilling sequence based on bone density and implant
design. Figure 9 shows the treatment planning for a patient with a single remaining tooth,
where one implant insertion guide was used. Figure 10 displays a drilling report for two
Figure 8. (Patient #2): Digital Smile Design in EXOCAD software for selecting anterior teeth, followed
by designing the provisional restoration based on previously obtained information.
2.3.2. Implants Planning
The STL file of the provisional restoration is imported into the R2Gate software, where
the number, length, diameter, and position of the implants are planned according to the
final restoration design. To facilitate bone quality assessment, the software’s “Digital Eye”
option automatically converts the CBCT grayscale into five basic colors for preoperative
bone density evaluation [
5
,
25
]. The implant planning data is then exported as an STL file
for guide design. For patients with remaining teeth, a stepwise approach is planned for
extraction and implant insertion, initially using a tooth-supported surgical guide. The
software also provides a drilling sequence based on bone density and implant design.
Figure 9shows the treatment planning for a patient with a single remaining tooth, where
one implant insertion guide was used. Figure 10 displays a drilling report for two of the
six implants being inserted in a stepwise manner, with the first stackable implant guide
supported by both mucosa and remaining teeth.
2.4. Stackable Guides Design and Manufacturing
Blenderfordental (B4D, Blenderfordental
®
2019) software was used to design stackable
guides. The following guides were created for each patient: a base guide that fits into the
vestibule of the dental arch, stabilized with three to four transversal pins, and a palatal
pin if necessary, which remains in place until the provisional prosthesis is fixed on the
inserted implants; a tooth-supported surgical guide for implant placement when some
remaining teeth are used for stabilization before extraction; an implant-supported guide
for the insertion of all remaining implants after the remaining teeth are extracted; and a
prosthetic guide for the placement of the provisional fixed restoration (Figure 11).

Dent. J. 2024,12, 347 9 of 19
Dent. J. 2024, 12, x FOR PEER REVIEW 9 of 20
of the six implants being inserted in a stepwise manner, with the first stackable implant
guide supported by both mucosa and remaining teeth.
Figure 9. (Patient #1): Prosthetically driven implant planning. Six implants were planned for this
patient, along with the design of four transverse pins for base guide stabilization.
Figure 10. (Patient #2): Detailed positioning of the implants and transversal pins generated by
R2Gate™ software according to the surgical plan. Bone density and the recommended drilling
sequence for each implant position are also displayed. The R2Gate™ software converts the CBCT
grayscale into five basic colors corresponding to the 256 shades of gray (right images): black
represents air, red indicates soft tissue, blue represents soft bone, yellow corresponds to dense bone,
and green represents high-density structures (such as enamel, cortical bone, and metal structures).
2.4. Stackable Guides Design and Manufacturing
Blenderfordental (B4D, Blenderfordental
®
2019) software was used to design
stackable guides. The following guides were created for each patient: a base guide that fits
Figure 9. (Patient #1): Prosthetically driven implant planning. Six implants were planned for this
patient, along with the design of four transverse pins for base guide stabilization.
Dent. J. 2024, 12, x FOR PEER REVIEW 9 of 20
of the six implants being inserted in a stepwise manner, with the first stackable implant
guide supported by both mucosa and remaining teeth.
Figure 9. (Patient #1): Prosthetically driven implant planning. Six implants were planned for this
patient, along with the design of four transverse pins for base guide stabilization.
Figure 10. (Patient #2): Detailed positioning of the implants and transversal pins generated by
R2Gate™ software according to the surgical plan. Bone density and the recommended drilling
sequence for each implant position are also displayed. The R2Gate™ software converts the CBCT
grayscale into five basic colors corresponding to the 256 shades of gray (right images): black
represents air, red indicates soft tissue, blue represents soft bone, yellow corresponds to dense bone,
and green represents high-density structures (such as enamel, cortical bone, and metal structures).
2.4. Stackable Guides Design and Manufacturing
Blenderfordental (B4D, Blenderfordental
®
2019) software was used to design
stackable guides. The following guides were created for each patient: a base guide that fits
Figure 10. (Patient #2): Detailed positioning of the implants and transversal pins generated by
R2Gate™ software according to the surgical plan. Bone density and the recommended drilling
sequence for each implant position are also displayed. The R2Gate™ software converts the CBCT
grayscale into five basic colors corresponding to the 256 shades of gray (right images): black represents
air, red indicates soft tissue, blue represents soft bone, yellow corresponds to dense bone, and green
represents high-density structures (such as enamel, cortical bone, and metal structures).

Dent. J. 2024,12, 347 10 of 19
Dent. J. 2024, 12, x FOR PEER REVIEW 10 of 20
into the vestibule of the dental arch, stabilized with three to four transversal pins, and a
palatal pin if necessary, which remains in place until the provisional prosthesis is fixed on
the inserted implants; a tooth-supported surgical guide for implant placement when some
remaining teeth are used for stabilization before extraction; an implant-supported guide
for the insertion of all remaining implants after the remaining teeth are extracted; and a
prosthetic guide for the placement of the provisional fixed restoration (Figure 11).
Figure 11. (Patient #3): Design of stackable guides (from left to right): maxillary model before
extractions, base guide, tooth-supported guide for the insertion of the first two implants; model with
virtual extractions, base guide, implant-supported guide; model with virtual extractions, base
guide, and prosthetic guide.
The connection between the base guide and the subsequent guides is established
using specific aachments, as illustrated in Figure 12. These aachments ensure a secure
and precise alignment of the guides during the surgical procedure, facilitating accurate
placement of the implants.
Figure 12. Matrix (displayed in blue)-patrix (displayed in
beige) type of aachment between the
base guide and subsequent surgical or prosthetic guides.
The guides and models with virtual extractions were printed using the Phrozen Sonic
XL 4 K printer (3Dream Teknoloji, Turkey), which employs Digital Light Processing (DLP)
technology. Following post-processing, digital implant analogs were inserted into the
models, and the corresponding abutments—OT Equator™ (Rhein83, Bologna, Italy)—
along with temporary cylinders, adjusted in height to match the temporary restorations
(Figure 13a–d).
For all patients, a long-term milled provisional restoration was fabricated using G-
CAM material (Graphenano, Spain) (Figure 13d). In cases where patients had a reduced
number of remaining teeth, a puy bite registration (Zeta Plus, Zhermack, Badia Polesine,
Figure 11. (Patient #3): Design of stackable guides (from left to right): maxillary model before
extractions, base guide, tooth-supported guide for the insertion of the first two implants; model with
virtual extractions, base guide, implant-supported guide; model with virtual extractions, base guide,
and prosthetic guide.
The connection between the base guide and the subsequent guides is established
using specific attachments, as illustrated in Figure 12. These attachments ensure a secure
and precise alignment of the guides during the surgical procedure, facilitating accurate
placement of the implants.
Dent. J. 2024, 12, x FOR PEER REVIEW 10 of 20
into the vestibule of the dental arch, stabilized with three to four transversal pins, and a
palatal pin if necessary, which remains in place until the provisional prosthesis is fixed on
the inserted implants; a tooth-supported surgical guide for implant placement when some
remaining teeth are used for stabilization before extraction; an implant-supported guide
for the insertion of all remaining implants after the remaining teeth are extracted; and a
prosthetic guide for the placement of the provisional fixed restoration (Figure 11).
Figure 11. (Patient #3): Design of stackable guides (from left to right): maxillary model before
extractions, base guide, tooth-supported guide for the insertion of the first two implants; model with
virtual extractions, base guide, implant-supported guide; model with virtual extractions, base
guide, and prosthetic guide.
The connection between the base guide and the subsequent guides is established
using specific aachments, as illustrated in Figure 12. These aachments ensure a secure
and precise alignment of the guides during the surgical procedure, facilitating accurate
placement of the implants.
Figure 12. Matrix (displayed in blue)-patrix (displayed in
beige) type of aachment between the
base guide and subsequent surgical or prosthetic guides.
The guides and models with virtual extractions were printed using the Phrozen Sonic
XL 4 K printer (3Dream Teknoloji, Turkey), which employs Digital Light Processing (DLP)
technology. Following post-processing, digital implant analogs were inserted into the
models, and the corresponding abutments—OT Equator™ (Rhein83, Bologna, Italy)—
along with temporary cylinders, adjusted in height to match the temporary restorations
(Figure 13a–d).
For all patients, a long-term milled provisional restoration was fabricated using G-
CAM material (Graphenano, Spain) (Figure 13d). In cases where patients had a reduced
number of remaining teeth, a puy bite registration (Zeta Plus, Zhermack, Badia Polesine,
Figure 12. Matrix (displayed in blue)-patrix (displayed in beige) type of attachment between the base
guide and subsequent surgical or prosthetic guides.
The guides and models with virtual extractions were printed using the Phrozen Sonic
XL 4 K printer (3Dream Teknoloji, Turkey), which employs Digital Light Processing (DLP)
technology. Following post-processing, digital implant analogs were inserted into the
models, and the corresponding abutments—OT Equator™ (Rhein83, Bologna, Italy)—
along with temporary cylinders, adjusted in height to match the temporary restorations
(Figure 13a–d).
For all patients, a long-term milled provisional restoration was fabricated using G-
CAM material (Graphenano, Spain) (Figure 13d). In cases where patients had a reduced
number of remaining teeth, a putty bite registration (Zeta Plus, Zhermack, Badia Polesine,
Italy) was created to aid in the accurate positioning of the initial guide and the stabilization
of the transversal pins (Figure 13e).

Dent. J. 2024,12, 347 11 of 19
Dent. J. 2024, 12, x FOR PEER REVIEW 11 of 20
Italy) was created to aid in the accurate positioning of the initial guide and the stabilization
of the transversal pins (Figure 13e).
(e)
Figure 13. 3D Printed Stackable Guides: (a) base guide on the 3D-printed model with implant digital
analogs and OT Equator™ corresponding abutments in the planned positions; (b) mucosa-
supported guide for dental implant insertion; (c) prosthetic guide with temporary fixed restoration;
(d) temporary fixed restoration with temporary cylinders in place and Seeger™ conical Teflon rings
(OT Equator™ abutments with temporary cylinders and Seeger™ conical Teflon rings are also
displayed separately); (e) base guide and mucosa-supported guide with puy bite for base guide
fixation using transverse pins.
2.5. Implants Insertion and Provisional Restoration
The surgical procedures were conducted by an experienced surgeon (C.M.C.) in strict
accordance with the manufacturers guidelines. The surgeries were performed under local
anesthesia using a flapless and minimally invasive technique. Prior to implant insertion,
Figure 13. 3D Printed Stackable Guides: (a) base guide on the 3D-printed model with implant
digital analogs and OT Equator™ corresponding abutments in the planned positions; (b) mucosa-
supported guide for dental implant insertion; (c) prosthetic guide with temporary fixed restoration;
(d) temporary fixed restoration with temporary cylinders in place and Seeger™ conical Teflon rings
(OT Equator™ abutments with temporary cylinders and Seeger™ conical Teflon rings are also
displayed separately); (e) base guide and mucosa-supported guide with putty bite for base guide
fixation using transverse pins.
2.5. Implants Insertion and Provisional Restoration
The surgical procedures were conducted by an experienced surgeon (C.M.C.) in strict
accordance with the manufacturer’s guidelines. The surgeries were performed under local
anesthesia using a flapless and minimally invasive technique. Prior to implant insertion, a
prophylactic antiseptic mouth rinse containing 0.2% Chlorhexidine (Corsodyl, GlaxoSmithK-
line, Brentford, UK) was administered for one minute to reduce bacterial contamination.

Dent. J. 2024,12, 347 12 of 19
The base guide was correctly positioned and secured with transverse pins. In patients
with remaining hopeless dentition, serial extractions were performed before placing the
initial guide for dental implant insertion, following the preoperative plan.
For all four patients, AnyRidge implants (MegaGen, Daegu, Republic of Korea) were
inserted according to the preoperative plan. The osteotomy sites were prepared based on
preoperative bone density assessments obtained from CBCT scans and the drilling protocol
provided by the planning software (Figure 10). The preparation was performed using
shank-modified drills, which consist of three components: the stopper, the guide, and the
drilling parts [
4
,
5
,
25
,
26
]. All implants were placed under fully guided conditions, and a
hand ratchet was used to achieve the predetermined insertion depth at the designated
anatomical landmarks.
OT Equator™ abutments, selected during the treatment planning phase based on the
anticipated implant positions, were screwed onto the corresponding implants and torqued
to 35 Ncm. These abutments, due to their geometry, can compensate for severe angulation
discrepancies between implants (up to 80
◦
, according to the manufacturer). The abutments
were initially fitted onto the printed model (Figure 13a) to facilitate accurate matching
during the insertion of the provisional restoration.
Temporary cylinders, adjusted for height, were mounted onto the OT Equator™
abutments. Using a prosthetic guide, the temporary fixed restoration was positioned and
secured to the temporary cylinders with composite resin. The provisional restoration was
then removed for final adjustments, including emergence profile contouring and gingival
surface polishing. Seeger™ conical Teflon rings (Rhein83, Bologna, Italy) (Figure 13e)
were placed between the prosthesis and the abutments to absorb functional shocks. After
adjustments, the provisional restoration was screwed into place with a torque of 15 Ncm.
Following the placement, functionalization of the fixed provisional restoration was
performed, and a panoramic X-ray was taken. Patients were provided with written post-
operative care instructions, including the use of a 0.2% Chlorhexidine mouth rinse and a
prophylactic antibiotic regimen of 1 g amoxicillin with clavulanate potassium, taken twice
daily for the following seven days. Additionally, a nonsteroidal anti-inflammatory drug
(Ibuprofen 400 mg) was prescribed for two days.
Patients were scheduled for follow-up appointments at one week, one month, six
months, and one year postoperatively, with the long-term provisional restoration being
replaced at the one-year mark.
2.6. Outcome Measurements
2.6.1. One-Year Implants Survival Rate
Implant survival was assessed at each follow-up, up to one year, using the criteria
proposed by Albrektsson et al. [
27
], which include the evaluation of mobility, radiographic
peri-implant radiolucency, and the presence of symptoms such as pain, infection, or neu-
ropathies, but without effectively measuring bone loss. Panoramic X-rays were performed
at the one-week and six-month follow-ups to assess bone remodeling around implants.
A CBCT with a large field of view (FoV) 20
×
19, following the same protocol as
at treatment planning was conducted at the one-year follow-up to assess the deviation
between the planned and actual implant positions.
2.6.2. One-Year Survival and Complications of the Provisional Fixed Prosthetic Restoration
At one week, one month, and six months, patients were recalled for clinical assessment,
checking for proper tissue healing, assessment of bleeding, and inflammation.
All complications and appointments solicited by the patients were recorded.
Prosthesis success was determined based on function: if a prosthesis remained func-
tional without requiring replacement, it was considered successful [
28
]. The incidence of
mechanical complications, such as fractures of the fixed prosthesis and screw loosening, as
well as biological complications, including soft tissue inflammation, fistula formation, or
abscess development, was also assessed.

Dent. J. 2024,12, 347 13 of 19
2.6.3. Assessment of Trueness of Implants Insertion
Assessment of trueness was performed by evaluating the deviation between planned and
placed implants, expressed by three deviation parameters: 3D coronal, 3D apical, and angular
according to a previously described technique [
5
,
26
]. The assessment of trueness in implant
positioning was conducted by referencing anatomical landmarks from both the preoperative
and one-year postoperative CBCT scans, which were performed using a strict protocol at the
same radiologic center (FM Medident, Bucharest, Romania). The preoperative CBCT, along
with the treatment plan saved as an STL file, was superimposed onto the postoperative CBCT
in R2Gate software (Figure 14), using anatomical landmarks for alignment.
Dent. J. 2024, 12, x FOR PEER REVIEW 13 of 20
All complications and appointments solicited by the patients were recorded.
Prosthesis success was determined based on function: if a prosthesis remained
functional without requiring replacement, it was considered successful [28]. The incidence
of mechanical complications, such as fractures of the fixed prosthesis and screw loosening,
as well as biological complications, including soft tissue inflammation, fistula formation,
or abscess development, was also assessed.
2.6.3. Assessment of Trueness of Implants Insertion
Assessment of trueness was performed by evaluating the deviation between planned
and placed implants, expressed by three deviation parameters: 3D coronal, 3D apical, and
angular according to a previously described technique [5,26]. The assessment of trueness
in implant positioning was conducted by referencing anatomical landmarks from both the
preoperative and one-year postoperative CBCT scans, which were performed using a
strict protocol at the same radiologic center (FM Medident, Bucharest, Romania). The
preoperative CBCT, along with the treatment plan saved as an STL file, was superimposed
onto the postoperative CBCT in R2Gate software (Figure 14), using anatomical landmarks
for alignment.
Figure 14. Aligned preoperative CBCT with treatment plan (right) and postoperative CBCT (left) in
R2Gate software.
In the postoperative CBCT, the corresponding implant library (with specific implant
length and diameter) was applied, and the file was saved. Both the planned and actual
implant position files were saved within the same coordinate system, and the assessment
of trueness was performed in Geomagic Control X software, version 2017.0.3 (3D Systems,
Rock Hill, SC, USA) with the STL of the planned implant position set as reference data
(Figure 15).
Figure 14. Aligned preoperative CBCT with treatment plan (right) and postoperative CBCT (left) in
R2Gate software.
In the postoperative CBCT, the corresponding implant library (with specific implant
length and diameter) was applied, and the file was saved. Both the planned and actual
implant position files were saved within the same coordinate system, and the assessment of
trueness was performed in Geomagic Control X software, version 2017.0.3 (3D Systems, Rock
Hill, SC, USA) with the STL of the planned implant position set as reference data (Figure 15).
Figure 15. Assessment of the 3D positions of the planned implants (shown in blue) versus the placed
implants (shown in green). Tolerance limits were set to
±
0.1 mm (indicated by green on the scale).
The 3D deviation for each point was calculated as the square root of the sum of the squared deviations
along the three axes (x, y, and z).

Dent. J. 2024,12, 347 14 of 19
3. Results
Four consecutive patients were included in this cohort study, comprising two males
and two females, with a mean age of 66 years (standard deviation [SD] 7.87 years). Accord-
ing to the ANB angle measurements, two patients exhibited a normal skeletal class I profile
(2.4
◦
and 4.3
◦
), while the other two patients were classified as skeletal class II (6.2
◦
and
6.5◦). Detailed patient characteristics are summarized in Table 1.
Table 1. Patient characteristics and distribution of inserted implants.
Patient #1 Patient #2 Patient #3 Patient #4
Gender (M/F) M F F M
Age 75 58 61 70
Number of remaining hopeless teeth (maxilla) 1 9 6 7
ANB angle (◦) 2.4 6.5 6.2 4.3
McNamara line to A (mm) 2.2 −2.5 −0.6 12.3
Y angle (◦) 57.8 63.5 59.5 53.7
Implants inserted nr./diameter (mm) ×length (mm) 6/4 ×11.5
1/4 ×10;
2/4 ×13;
1/3.5 ×13;
1/4.5 ×11.5;
1/4.5 ×10
1/4 ×11.5;
2/4 ×13;
1/4.5 ×8.5;
2/4 ×10
2/4 ×13;
3/4 ×10;
2/4.5 ×11.5
Except for patient #4, who exhibited a severe maxillary protrusion, the other three
patients had measurements close to normal values. This was taken into consideration
during provisional planning. The Y angle was within acceptable limits for all patients,
indicating that the preset occlusal vertical dimension (OVD) was appropriate (Table 1).
Following meticulous digital planning, as previously described, a total of 25 AnyRidge
implants were inserted into the maxilla. The implants varied in length from 8.5 to 13 mm,
with a mean length of 11.38 mm (SD
±
1.29 mm), and in diameter from 3.5 to 4.5 mm, with
a mean diameter of 4.08 mm (SD
±
0.24 mm) (Table 1). The position of the implants was
determined based on the requirements of the prosthetic restoration, while the length and
diameter of the implants were dictated by the available bone. No major complications were
encountered during the insertion of the provisional restorations. All patients expressed
satisfaction with the aesthetic outcomes, based on their subjective feedback, and necessary
functional occlusal adjustments were performed during the adaptation session. Before
the final tightening of the provisional restorations, adjustments were made to the mucosal
aspect to facilitate the emergence profile conformation, followed by careful polishing to
minimize the risk of mucosal irritation. Seeger™ conical Teflon rings were then positioned
(Figure 13d, and the provisional restorations were secured over the OT Equator abutments
with a torque of 15 Ncm. The occlusal access holes were subsequently sealed with Teflon
tape and composite resin.
Further occlusal evaluations were conducted at one-week and one-month intervals. At
the six-month follow-up, after conducting a panoramic X-ray assessment, the provisional
restorations were removed to allow for clinical evaluation of gingival healing, with addi-
tional adjustments performed as needed. All patients completed the one-year follow-up
period without any loss to follow-up. Successful osseointegration was observed in all
implants, and no implant failures were recorded, resulting in a 100% survival rate. The
long-term provisional restorations demonstrated satisfactory performance, with only two
unscheduled appointments required by one patient for occlusal adjustments within the
first six months.
Implant deviations from the planned positions, measured as mean (SD) for 3D coro-
nal, apical, and angular discrepancies, were 0.87 (
±
0.50) mm, 2.04 (
±
0.69) mm, and 2.67
◦
(
±
1.25
◦
), respectively. At the one-year follow-up, the long-term provisional fixed restora-
tions were replaced with definitive zirconia-on-titanium milled restorations.

Dent. J. 2024,12, 347 15 of 19
4. Discussion
The present study aimed to establish a protocol for the full fixed rehabilitation of a
maxillary dental arch with failing dentition. There were two main reasons for choosing a
fully digital workflow for restoring the maxilla: first, intraoral scanning is more predictable
for the maxilla due to the fixed palatal mucosa, whereas the mandible has less stable
mucosa on the residual ridge, making digital impressions less accurate. Second, maxillary
restoration is crucial for achieving esthetic outcomes.
The protocol consists of several steps: initially, the creation of a virtual dental patient,
followed by prosthetic design and implant planning. Subsequent steps include the design
and production of surgical guides and the manufacturing of the provisional prosthesis. By
following this protocol, both surgical and prosthetic restoration become more predictable,
enabling immediate esthetic restoration. This standardized, fully digital workflow not
only enhances precision in implant placement but also minimizes variations between
planned and actual outcomes. The collaborative approach involving the entire clinical team,
alongside the use of virtual simulations, ensures that treatment is tailored to each patient
while maintaining consistency and predictability across cases.
For the first guide design, the number of pins is carefully determined based on the
available bone, remnant dentition, and bone density, which we assess using the “Digital
Eye” feature in the R2Gate software. This allows for precise evaluation of the necessary
number of pins, as more pins do not always equate to better stabilization. In fact, in cases
of dense mandibular bone, exceeding three pins can create internal tensions that may lead
to guide fracture. Four transverse pins were used for each of the four enrolled patients
(Figures 9and 13e), in line with other published case reports [12,15,29,30].
Another important consideration is the manufacturing technique and material used
for the first guide. We employ DLP (Digital Light Processing) technology and use a
dedicated resin (SG Surgical Guide) from NexDent (Vertex-Dental B.V., Centurionbaan,
the Netherlands), ensuring a minimum thickness of 3 mm. This combination provides the
guide with excellent mechanical properties, allowing for durability and stability during
the surgical procedure [
31
]. In some clinical reports, guides were manufactured using
selective laser melting (SLM) from cobalt–chromium alloy powder [
32
]. We preferred the
use of NextDent resin and the DLP technique for several reasons. First, the guides were
mucosa-supported (or mixed teeth and mucosa), and the maxillary mucosa had a certain
degree of resilience, which could be compensated for by the low resilience of the resin.
Additionally, the use of resin guides presents a more cost-effective option. Moreover, due
to the large dimensions of the first guide, not all CAM centers had the capability to sinter
the guide, limiting its accessibility.
The stackable components of the guides are connected using various types of attach-
ments, such as magnets [
13
,
33
], balls [
29
], screws [
9
,
12
,
30
], or notches [
34
], depending
on the preference of the medical team. To date, no study has proven one system to be
more efficient than another. In our study, we used a matrix-patrix system designed in
Blender4Dental with an adjustable offset (Figure 14), depending on the required retention
between the guides.
While several case reports and case series have been published on the use of stackable
surgical guides, most of these studies involved open-flap surgery and the use of a bone
reduction guide to establish a suitable ridge for implant placement and to accommodate a
bone-supported drill guide [8,35–37].
This protocol introduces several innovations compared to previously published case
reports and series [
12
,
13
,
38
]. One significant innovation is the creation of a virtual dental
patient and the clinically oriented cephalometric analysis performed to gather information
for planning the provisional restoration. The introduction of the virtual dental patient
significantly improves upon previous methods by allowing enhanced preoperative plan-
ning, visualization, and communication between the clinical team and the patient. This
digital approach reduces treatment time by enabling more precise implant positioning and
prosthetic design, minimizing the need for adjustments during surgery.

Dent. J. 2024,12, 347 16 of 19
Another novel aspect is the use of OT Equator abutments as part of the OT Bridge
protocol to compensate for the angulation between the inserted implants and the require-
ments for restoration. In addition to compensating for implant angulation, these abutments
facilitate bone remodeling. Their design eliminates the need for space to accommodate
angulation correction components, such as multi-unit abutments (MUAs), thereby reduc-
ing the necessity for a bone-reduction stackable drill guide. The OT Equator abutment
offers several advantages, such as a short profile, narrow emergence, and the ability to
resolve implant divergence while reducing tensions in the structure due to the Seeger
solution. Moreover, the Seeger ring system helps manage higher stresses associated with a
single-piece maxillary fixed prosthetic reconstruction during functional loading [39].
The use of a long-term milled provisional material, G-CAM (Graphenano, Spain),
allows the temporary fixed restoration to be maintained for up to one year, enabling adjust-
ments and bone remodeling due to its favorable properties. The graphene nano-reinforced
biopolymer G-CAM disc is specifically designed for permanent dental structures and is
available in different shades to provide a natural aesthetic appearance. It offers superior
mechanical, physicochemical, and biological properties compared to other materials cur-
rently used in the sector [
40
]. In comparison to unmodified Poly(methyl methacrylate)
(PMMA), G-CAM, which incorporates graphene-like materials, offers improved properties
such as enhanced flexural strength and fracture toughness. According to the study by
Agarwalla et al. [
41
], while G-CAM showed similar translucency and hardness to unmodi-
fied PMMA, it demonstrated mechanical strength and reliability that make it suitable for
CAD/CAM prosthetic restorations, including complete arch restorations. Furthermore,
the use of graphene-like materials improves the performance of PMMA-based resins, al-
lowing them to withstand higher occlusal forces, which is a significant advantage over
traditional PMMA. The robust mechanical properties of G-CAM eliminate the need for
metal-reinforced PMMA structures [
42
], thereby reducing the risk of fracture during the
healing period.
Key factors in the dental rehabilitation procedure include the hinge axis position,
centric relation (CR) or intercuspal position (ICP), and vertical dimension of occlusion
(VDO) [
43
]. This information is obtained during the virtual patient creation and analysis.
Additionally, the maxillary position relative to the hinge axis was transferred as a virtual
articulator mounting (Artex for all four patients) into the software for provisional prosthesis
design, eliminating the need for a conventional facebow and model mounting.
For implant position planning, provisional design, and stackable guide design, three
different software programs were utilized: R2Gate, EXOCAD, and Blender4Dental. R2Gate
was used for virtual patient creation and analysis, operating on a pay-per-export basis.
EXOCAD, a widely recognized software in dental laboratories, was employed for the design
of provisional restorations under a paid license. Blender4Dental, a recently introduced and
cost-effective paid software, was used for designing the surgical guides.
The mean deviation between the planned and actual implant positions was 0.87 mm
(
±
0.50 mm) at the coronal level and 2.04 mm (
±
0.69 mm) at the apical level. These values
are comparable to those reported in other studies, although slightly lower at the apical
level, which ranged from 0.44 mm to 1.43 mm for coronal deviations and 0.887 mm to
1.90 mm for apical deviations [
32
,
33
,
37
,
44
]. The observed higher apical deviation in this
study can be attributed to the implant length and the softer maxillary bone, compared
to other studies that primarily assessed the mandible. The mean angular deviation was
2.67
◦
(
±
1.25
◦
), which is consistent with other studies reporting mean values between 2.4
◦
and 4.14
◦
[
32
,
33
,
37
,
44
]. Overall, all deviations observed were within acceptable clinical
limits [45].
A limitation of this study is the small sample size, consisting of only four participants
(two males and two females), and the lack of a comparative group using guided implant
insertion without stackable guides. However, the authors’ previous experience with im-
mediate loading of the full maxilla without using prosthetic stackable guides resulted in

Dent. J. 2024,12, 347 17 of 19
suboptimal outcomes, highlighting the potential benefits of the approach evaluated in
this study.
Another challenge is the inherent learning curve associated with adopting digital
workflows and stackable guide systems, particularly for clinicians unfamiliar with these
technologies. This learning curve may influence the outcomes and efficiency of the treat-
ment process.
The fully digital workflow and the use of stackable guides allowed for more personal-
ized treatment by providing precise control over implant positioning and prosthetic design,
tailored to each patient’s anatomical conditions. The ability to visualize and simulate
treatment outcomes using virtual planning helped ensure that the restorations were both
functional and aesthetically aligned with the patient’s needs.
A Randomized Clinical Trial (RCT) study comparing the stackable guide protocol
and the conventional All-on-6 protocol in the maxilla could provide valuable insights into
the benefits and limitations of each approach. Additionally, further studies with larger
sample sizes and comparative groups would help assess the broader efficacy of this method
and refine the protocol for more complex anatomical situations. This would provide a
more comprehensive understanding of how the fully digital workflow and stackable guide
system perform in different clinical scenarios.
5. Conclusions
This report on four consecutive clinical cases of failing maxillary dentition highlights
the effectiveness of a fully digital workflow using stackable surgical templates for the
immediate rehabilitation of a complete maxillary arch. By leveraging virtual patient
creation, precise implant placement, and innovative materials, this approach enhances
treatment predictability and improves patient outcomes, setting a benchmark for future
advancements in digital dentistry.
Supplementary Materials: The following supporting information (Case Presentation: Patient #1) can
be downloaded at: https://www.mdpi.com/article/10.3390/dj12110347/s1.
Author Contributions: Conceptualization, C.M.C. and O.E.B.V.; methodology, C.M.C., O.E.B.V., T.M.,
and C.C.B.; software, C.M.C. and C.C.B.; validation, T.M., E.D.S., and C.M.C.; formal analysis, T.M.;
investigation, C.M.C. and O.E.B.V.; resources, E.D.S.; data curation, C.M.C.; writing—original draft
preparation, O.E.B.V., T.M. and E.D.S.; writing—review and editing, C.M.C. and C.C.B.; visualization,
T.M.; supervision, C.M.C.; project administration, C.M.C.; funding acquisition, C.M.C. and O.E.B.V.
All authors have read and agreed to the published version of the manuscript.
Funding: This research received no external funding.
Institutional Review Board Statement: The study was conducted in accordance with the Declaration
of Helsinki, and approved by the Ethics Committee of the “Carol Davila” University of Medicine and
Pharmacy (36368/2023).
Informed Consent Statement: Informed consent was obtained from all subjects involved in the study.
Data Availability Statement: Further data are available upon request from the corresponding authors.
Acknowledgments: The authors would like to acknowledge Ronen Boiangiu and FM Medident for
establishing and conducting CBCT scans according to a standardized protocol for all patients. A part
of this research was presented as an ePoster at the DDS Global Congress CASABLANCA 2023, and
the abstract was published in the Journal of Dentistry, vol 147, August 2024, https://doi.org/10.1016/
j.jdent.2024.105203 (accessed on 15 August 2024).
Conflicts of Interest: The authors declare no conflicts of interest.
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