JOURNAL CLUB PRESENTATION IN PROSTHODONTICS on biologically oriented preparation technique (BOPT)

1. DIGITAL PROTOCOL FOR
CREATING A VIRTUAL GINGIVA
ADJACENT TO TEETH WITH
SUBGINGIVAL DENTAL
NAMITHA AP
II nd MDS
DEPT OF
PROSTHODONTICS
COORG INSTITUTE OF
DENTAL SCIENCES
Agustín-Panadero R, Loi I, Fernández-
Estevan L, Chust C, Rech-Ortega C, Pérez-
Barquero JA.
Journal of Prosthodontic Research. 2019
Nov 28.
JOURNAL CLUB
PRESENTATIO
N

2. CONTENTS
INTRODUCTION
OBJECTIVES
MATERIALS AND METHODS
DISCUSSION
CONCLUSION
RELATED ARTICLES
REFERENCES

3. INTRODUCTION
Dental preparation techniques for restoration by fixed prostheses are
undergoing a significant change
horizontal finish lines (short or long chamfer, straight shoulder,
beveled shoulder, etc.) are now being replaced by preparations without
finish line, following the biologically oriented preparation technique
(BOPT)

4. BIOLOGICALLY ORIENTED
PREPARATION TECHNIQUE
This procedure is characterized by
the creation of a non-dental,
prosthetic finish line situated at a
depth of 0.5–1 mm in the periodontal
sulcus, first preparing the tooth with
a vertical axial plane between the
anatomical crown and the root.
Intraoral
scanners
Inefficient in
detecting
subgingival dental
anatomy
Provisional prosthesis is
removed for impression
taking
gums collapse onto the
tooth
impossible to obtain a
digital record of the
dental preparation, the
gingival sulcus, or its
emergence
CORRECT HEALING
OF SURROUNDING
GINGIVAL TISSUES
CERVICAL
EMERGENCE AND
OVOID
CONTOURING
healthy gingival adaptation with the same
shape as gingival tissue adapted to the
convex emergence of the natural
emergence profile of an untreated tooth
Provisional
crown

5. OBJECTIVES
to describe a digital technique for reproducing the subgingival part of
a tooth prepared without finish line (BOPT) and the adjacent dento-
gingival sulcus without variations derived from gingival collapse.
This technique is able to create a ‘virtual gingiva’ with the same
emergence morphology as when the provisional prosthesis is
cemented in place on the tooth.

6. MATERIALS AND METHODS
Tooth preparation
• The exact measurement to the bone level must
be determined as this structure must remain
untouched by dental preparation
1.Double probing
2.Supragingival dental preparation
3.Subgingival dental preparation
BOPT procedure
described by Loi

7. DOUBLE PROBING
periodontal chart and a series of radiographs
Distance from the gingival margin to the bone crest is
measured in order to confirm that the teeth present no
bone problem and that both cortices are intact (2.7–3.2
mm)
position of the tooth’s cemento-enamel junction - depth of
dental preparation inside the gingival sulcus
GIGIVAL
SULCUS(SULCULA
R EPITHELIUM)
JUNCTIONAL
EPITHELIUM
(ATTACHMENT)
PROBED WITH
PERIODONTAL
PROBE
1.6–2.4
mm
free from
signs of
inflammati
on,
alterations
in color,
hemorrhagi
ng and
bacterial
plaque
When it is resting on the bone and laterally on the tooth, it is
withdrawn gently in coronal direction in touch with the root
anatomy until it reaches the start of anatomical crown
emergence.
At this point the movement stops and the distance to the gingival
margin is measured. This distance will determine the extent of

8. SUPRAGINGIVAL PREPARATION
incisal edge or occlusal face is reduced by 2 mm
beveling the vestibular face of the incisal edge or the external slope
of the functional cusp to an angle of approximately 45 º
axial walls are reduced by 1 mm supragingivally with a conical shaft
turbine diamond bur, of 1.4 mm diameter, with 100 μm
granulometry.
chamfer finish line 2 mm from the gingival margin.
In the interproximal area, scalloped dental preparation is carried out
following the anatomy of the papilla but without touching it.
In cases of retreatment with fixed prostheses, this step should be
omitted as the tooth has already undergone subgingival preparation

9. SUBGINGIVAL PREPARATION
milling of both tooth and gum are performed
simultaneously (rotary gingival curettage) with a 1.2 mm
diameter diamond flame bur with 100 ƒÊm ganulometry.
Bur is inserted in the gingival sulcus obliquely at an angle of
10 -15 0 to the dental axis
Tooth is milled with one side of the bur while the gingiva is
curetted with the other side and the bur tip.
When the first millimeter of the anatomical crown
emergence has been milled, to prevent the bur tip from
damaging part of the tooth root, the angle of the bur is
altered so that it runs parallel to the tooth axis; in this way,
the convexity of the anatomical crown beyond the cemento-
enamel junction is eliminated.
To complete preparation, the bur is inclined slightly in
occlusal/incisal direction to give the axial walls of the tooth
the correct convergence (6 o).

10. cell differentiation for the formation of new gingival tissue
new structuring of the periodontium around the prosthetic emergence’s new
morphology
creates a blood clot in the apical area
stabilized by the design of the provisional prosthesis
milling the tooth and gum at the same time
controlled de-epithelization of the
sulcus’ free and junctional epithelium
vertical axial plane
The function of the
provisional prosthesis is to
shape a new prosthetic
angular component with a
new prosthetic cemento-
enamel junction (PCEJ)
situated in the gingival sulcus
at a depth of 0.5- 1 mm
(respecting biologic width)

11. Provisional must not be removed from the tooth for the first four
weeks in order to avoid gingival healing problems.
Later, until the complete maturation of soft tissue (8–12 weeks), the
shape of the provisional can be modified to achieve the correct
modeling of the gingival margin.
The provisional is fabricated by the laboratory technician from an
initial pre-treatment model.
The technician mills the tooth model, which then acts as a post to
support the (juxta-gingival) provisional prosthesis.
The provisional is fabricated from acrylic resin of very fine thickness
(0.3 mm).

12. This will function as an “egg-
shell”provisional, facilitating relining
without compromising its seating.
When the tooth has been prepared,
the fit of the provisional is checked
and then it is relined with self-
polymerizing acrylic resin (Sintodent.
Sintodent S.R.L).
Lastly, while the relining material is
setting, the provisional can be
adjusted on the tooth and inserted
0.5–1 mm inside the gingival sulcus
(controlled invasion of the gingival
sulcus)
The provisional prosthesis will
remain cemented on the tooth until
the gingival tissues have matured
completely

13. IMPRESSION TECHNIQUE
It is important to follow an impression taking protocol that will
reproduce the real position of the gums when the provisional is in
place on the prepared tooth, and that is reproducible and does not
depend on clinical skill.
Captures data in three dimensions
produces STL files of the gingiva, first scanning the occlusal face,
followed by the vestibular and lingual aspects.
The data obtained are downloaded from the 3 M Connection Center,
providing one STL file per scan.

14. CHAIR SIDE PROTOCOL STEP BY
STEP
creates a virtual model of the
gingiva( used to fabricate the crown
)
Six intraoral scans generate six
types of STL file.
The first STL file (STL-1) is obtained
by scanning the provisional
prosthesis cemented onto the tooth,
reproducing its morphology and
adjacent gingival emergence.
When doing this, it is important to
reproduce the other teeth in the
arch

15. The second scan captures the provisional crown removed from the mouth.
It is important to reproduce the intrasulcular emergence of the cervical area
of the crown as this will define prosthetic invasion of the gingival sulcus,
both vertically and horizontally under conditions of periodontal health.
To do this, the prosthesis is placed on a vertical wax rod, supporting the
incisal edge with the internal part and emergence placed upwards
In this way, the crown’s entire internal surface and peripheral cervical area
can be scanned

16. Then, to reproduce the whole crown and ensure best-fit alignment of
the surfaces, the prosthesis is replaced on the wax rod the other way
up, placing the internal part and emergence on the rod with the
incisal edge upwards, so that the complete morphology and the
prosthesis peripheral cervical emergence can be scanned
Accurate reproduction of the cervical part is of key importance for
correct alignment of the two scans, which are then used to generate a
3D virtual reproduction of the whole provisional, an STL file (STL-2)
of the complete prosthetic anatomy.

17. The third scan captures the teeth prepared with BOPT, recording all
tooth walls and the gingival area which will have collapsed due to the
removal of prosthetic support (STL-3).
It is also important to reproduce the rest of the arch (both teeth and
gingival tissue) in order to ensure better accuracy in future
alignments.

18. The fourth scan records the antagonist arch (teeth and gingival
tissue).
The fifth and sixth scans register occlusion in maximum
intercuspation on the left and right sides.
Exported to design software to create a digital model of the gums.
This ’virtual gingiva’ process begins by superimposing STL-1
(patient’s arch with bonded provisional[s]), which acts as a reference
for the entire alignment process, and STL-3 (patient’s arch with
prepared tooth stumps), which acts as a ‘floating’ archive.
For correct alignment, it is important to select the surfaces that are
common to both STL files.
When digital alignment has been performed, its quality can be
checked by creating a color map, which will highlight any surfaces
presenting variations between the scans
when any variations between one scan and the other are identified,
the corresponding surfaces should be eliminated from the points
selected for purposes of alignment before repeating the alignment

19. Most of the superimposed areas that
represent hard tissues show an error
of + - 20 micrometers, with the
exception of the central areas
In STL 3 the central incisors have
been milled.
Grey area represents those parts of
the STL-3 file that does not contain
information in either of the two files
(in this case STL 3), which
corresponds to the area of incisor
milling.
Interproximal area, as well as the
gingival sulcus, are typically ‘noisy,’
so these should be omitted when it
come to performing best fit.
Soft tissues have less dimensional
stability than hard tissues so these
should also be omitted when it
A color map that includes + - 200 micrometers,
whereby any deviation –any area subject to
error –within this range will be marked in color,
taking on the most extreme color on the map’s
color gradient

20. STL-1 (reference) and STL-2(floating)
are then aligned.
To do this, only the provisional crown in
the complete arch (STL-1) is selected
for alignment with the visible part of
the cemented provisional in STL-2, in
other words the contact points,
subgingival area and internal area are
omitted as these features are not visible
in either STL files and so are of no use
for purposes of superimposition.
Again color mapping is used to check
the precision of the superimposition as
in the previous alignment

21. 6 STL Files
STL Files
1+2+3
virtual gingiva
STL Files
4+5+6
prosthetic
crown
When a sagittal cross-section of the three aligned scans is examined,
the third file shows the collapsed gingiva; when the provisional was
removed this caused the gingiva to move centripetally inwards to- wards
the tooth, filling the space formerly occupied by the provisional.
To avoid this collapse and obtain a gingival position identical to that
achieved when the provisional was in place, a virtual gingiva is created,
erasing the collapsed gingiva to create gingival morphology adapted to
the provisional crown’s cervical emergence

22. BOOLEAN OPERATION TO
GENERATE VIRTUAL GINGIVA
Creates an object through a mathematical operation, in which two
objects can remain, intersect or unite to form a new object.
In the present technique, the software’s ’remain’ tool is used.
To do this it is necessary to reproduce the most apical contour of the
provisional crown, so STL-2 must be as precise as possible; as in
STL-1, the most apical portion of the provisional is not visible as it is
positioned subgingivally.
The Boolean operation generates a new master model with an open
gingival sulcus
which can then be exported in the software’s STL format to CAD
software in such a way that the definitive crown can follow the
gingival anatomy created by the provisional

24. CAD-CAM software designed for fabricating dental restorations is used to fabricate
a metal-free crown (made of lithium disilicate, monolithic zirconia, or resin nano-
ceramic) using completely digital techniques and maintaining the exact morphology
of the provisional prosthesis used to generate the biocopy
ensures that the definitive crown is adapted to periodontal tissue on all aspects
(vestibular, lingual and palatal) in exactly the same way as the provisional. Whenever
this non-metallic crown design protocol is used is it advisable to mill a test sample
from transparent resin to check restoration-preparation fit, evaluate dental
size,dental morphology, contact points, and occlusion

25. it is important to ensure by frontal and occlusal visual examination
that the prosthetic emergence does not provoke ischemia at any point
in the gingival sulcus

27. DISCUSSION
In the technique described here, the provisional crown plays an
important role, providing registers of the soft tissue response and
emergence profile, which are later reproduced exactly in the final
restoration
The difference between the emergence created by the provisional and
the collapsed gingiva once the provisional has been removed, even
though it may be minimal, does affect the placement of the definitive
restoration; variation will also increase according to the time the
patient spends without the provisional in place
It is a fast procedure and is easy to apply in cases when the gingiva
does not adapt correctly.
It also makes it possible to create an intrasulcular mock-up with ideal
prosthetic cervical contours and horizontal overcontouring

28. LIMITATIONS OF THIS STUDY
Intraoral scanners demand considerable economic investment and
their correct use constitutes a steep learning curve, and requires
constant updating.
Intraoral scanners obtain good results in terms of prosthetic precision
on a small scale, but this is not the case in full arch restorations.
However, in the case of BOPT, intraoral scanning is an innovative
technique that has not been widely reported in the literature, so
further assessment of soft tissue behavior is needed in the form of
prospective clinical trials with long-term follow-ups.
At the same time, mono- lithic materials milled using CAD-CAM
technology obtain optimal results in terms of strength and fit but may
present limitations, especially regarding esthetics.
They cannot be individualized like analogue restorations that are
manually shaped and crafted by the laboratory technician.

29. CONCLUSIONS
This digital protocol is of great relevance to clinicians, as it makes it
possible to reproduce anatomical dental information, soft tissue
contours, and emergence profiles exactly, without the use of
conventional impression-taking techniques, unaffected by gingival
collapse when the provisional is removed, and exactly transferring the
periodontal morphology around the provisional crown to the
definitive restoration.

30. RELATED ARTICLES
Loi I, Di Felice A. Biologically oriented preparation technique (BOPT): a
new approach for prosthetic restoration of periodontically healthy
teeth. Eur J Esthet Dent. 2013 Mar 1;8(1):10-23.
In this article, the author presents a prosthetic
technique for periodontally healthy teeth using
feather edge preparation in a flap- less approach
in both esthetic and posterior areas with
ceramometal and zirconia restorations, achieving
high quality clinical and esthetic results in terms
of soft tissue stability at the prosthetic/tissue
interface, both in the short and in the long term
(clinical follow-up up to fifteen years).

36. AGUSTÍN-PANADERO R, SERRA-PASTOR B, FONS-FONT A,
SOLÁ-RUÍZ MF. PROSPECTIVE CLINICAL STUDY OF ZIRCONIA
FULL-COVERAGE RESTORATIONS ON TEETH PREPARED WITH
BIOLOGICALLY ORIENTED PREPARATION TECHNIQUE ON
GINGIVAL HEALTH: RESULTS AFTER TWO-YEAR FOLLOW-UP.
OPERATIVE DENTISTRY. 2018 SEP;43(5):482-7.
To evaluate the clinical behavior of
one-piece complete-coverage
crowns and fixed partial dentures
(FPDs) on teeth with vertical
preparation without finish line
biologically oriented preparation
technique (BOPT).
The sample was divided into two
groups: one-piece crowns and FPDs,
all with zirconia cores, feldspathic
ceramic veneer, and a 0.5-mm
prosthetic finish line of zirconia.
Evaluated oral hygiene, periodontal
state, gingival thickening, gingival
margin stability, the presence of

37. Teeth prepared with BOPT and restored with
zirconia crowns or FPDs presented a 100% survival
Technique generates gingival thickening , as well
as gingival margin stability in 100% of samples.
High periodontal tissue and gingival margin stability, provided
the patient
maintains adequate oral hygiene

38. PANIZ, G., NART, J., GOBBATO, L., MAZZOCCO, F., STELLINI,
E., DE SIMONE, G. AND BRESSAN, E., 2017. CLINICAL
PERIODONTAL RESPONSE TO ANTERIOR ALL-CERAMIC
CROWNS WITH EITHER CHAMFER OR FEATHER-EDGE
SUBGINGIVAL TOOTH PREPARATIONS: SIX-MONTH RESULTS
AND PATIENT PERCEPTION. INTERNATIONAL JOURNAL OF
PERIODONTICS & RESTORATIVE DENTISTRY, 37(1).
The purpose of this
prospective randomized
clinical study was to
determine if two different
subgingival margin designs
influence the periodontal
parameters and patient
perception. Deep chamfer
and feather-edge
preparations were compared
on 58 patients with 6 months
follow-up.

39. RESULTS

40. Statistically significant differences were present for bleeding on probing, gingival recession,
and patient satisfaction. Featheredge preparation was associated with increased bleeding on
probing and deep chamfer with increased recession; improved patient comfort was registered
with chamfer margin design. Subgingival margins are technique sensitive, especially when
feather-edge design is selected. This margin design may facilitate soft tissue stability but can

41. AGUSTÍN-PANADERO R, MARTÍN-DE LLANO JJ, FONS-
FONT A, CARDA C. HISTOLOGICAL STUDY OF HUMAN
PERIODONTAL TISSUE FOLLOWING BIOLOGICALLY
ORIENTED PREPARATION TECHNIQUE (BOPT).
JOURNAL OF CLINICAL AND EXPERIMENTAL
DENTISTRY. 2020 JUN;12(6):E597.Aim of this study was to conduct histological analysis of a human
tooth resected with the periodontal insertion apparatus intact
following treatment using biologically oriented preparation technique
(BOPT)
This descriptive histological dento-periodontal study used an anterior
tooth extracted with the surrounding periodontal tissues intact,
following prosthetic restoration with BOPT.
Eight serial sections of the restored tooth were processed. The
relative location and histological characteristics of the cemented
prosthetic crown, the dental tissues of the tooth prepared by BOPT
technique, and the periodontal tissues were analyzed.

42. RESULTS
Structural analysis of the neoformed junctional epithelium showed
that the number of layers decrease apically until there was a single
row of cells perfectly adhered to the acellular cementum, and beneath
the epithelium a connective tissue evidently free from inflammation.
The tissues of the neoformed periodontium (gingival ligament,
sulcular epithelium, junctional epithelium) presented histologic
normality.

43. PERIS H, GODOY L, COGOLLUDO PG,
FERREIROA A. CERAMIC VENEERS ON CENTRAL
INCISORS WITHOUT FINISH LINE USING BOPT IN
A CASE WITH GINGIVAL ASYMMETRY. JOURNAL
OF CLINICAL AND EXPERIMENTAL DENTISTRY.
2019 JUN;11(6):E577.This clinical case report describes the rehabilitation of central
incisors with veneers in a patient with gingival asymmetry.
The teeth were prepared without finish line, applying BOPT concepts
to correct asymmetry, and obtained a harmoniously integrated
restoration with optimal periodontal health.

45. It is possible to correct gingival asymmetry by
performing dental preparation without finish line
providing
a correct periodontal analysis is first performed, which
will contribute to successful soft tissue stabilization

46. REFERENCES
Loi I, Di Felice A. Biologically oriented preparation technique (BOPT): a new
approach for prosthetic restoration of periodontically healthy teeth. Eur J
Esthet Dent. 2013 Mar 1;8(1):10-23.
Peris H, Godoy L, Cogolludo PG, Ferreiroa A. Ceramic veneers on central
incisors without finish line using bopt in a case with gingival asymmetry.
Journal of clinical and experimental dentistry. 2019 Jun;11(6):e577.
Agustín-Panadero R, Martín-de Llano JJ, Fons-Font A, Carda C. Histological
study of human periodontal tissue following biologically oriented
preparation technique (BOPT). Journal of Clinical and Experimental Dentistry.
2020 Jun;12(6):e597.
Paniz, G., Nart, J., Gobbato, L., Mazzocco, F., Stellini, E., De Simone, G. and
Bressan, E., 2017. Clinical Periodontal Response to Anterior All-Ceramic
Crowns with Either Chamfer or Feather-edge Subgingival Tooth Preparations:
Six-Month Results and Patient Perception. International Journal of
Periodontics & Restorative Dentistry, 37(1).
Agustín-Panadero R, Serra-Pastor B, Fons-Font A, Solá-Ruíz MF. Prospective
clinical study of zirconia full-coverage restorations on teeth prepared with
biologically oriented preparation technique on gingival health: results after
two-year follow-up. Operative dentistry. 2018 Sep;43(5):482-7.