Vertical Preparation The document discusses different approaches to vertical preparation for prosthetic dentistry. It summarizes the advantages of a shoulderless vertical preparation approach using a specialized non-cutting bur. This approach allows for a conservative preparation while avoiding damage to the biological width. It maintains tooth structure for strength and guides soft tissue regeneration for a tight seal along the crown margin. The approach aims to optimize biomechanics and periodontal outcomes for stable, long-term restorations.

1. Vertical Preparation
Made by:
Mohamed Ali

2. Vertical Preparation
 The development of new materials and equipment, as well as a better comprehension
of soft tissue biology, has given birth to a new revolutionary approach in prosthetic
dentistry:
the shoulderless concept
 The preparation of the abutment using horizontal finish lines (shoulder and chamfer)
has been widely used in the last three or more decades and acknowledged by the
academic world as the gold standard.

3. “Horizontalists” authors claim for the
following alleged advantages:
 1 - Avoiding overhangs
 2 - Avoiding horizontal and vertical over-contouring
 3 - Respecting of the biologic width
 4 - Finish line capturing and determination on the die
 5 - Better lab-clinician workflow

4. The same “horizontalists” authors have alleged preparations with vertical
finish lines as having the following alleged drawbacks:
 1 - Unavoidable overhangs
 2 - Unavoidable over-contouring
 3 - Uncontrolled invasion of the gingival sulcus and biologic width
 4 - Difficulty of capturing and determining a finishing line on the die
 5 - More difficult lab-clinician workflow

5. Thus on the basis of prevailing thought, the academic world has
unanimously considered the vertical preparation an incorrect
approach.
Over the years, a minority of professionals dealing with
“verticalism” have developed two main approaches and schools
of thought:
- the shoulderless approach
- the edgeless approach

6. The shoulderless approach
 known also as bevel, has been used extensively in the Gold Era, thanks to the possibility
to finish metal margins at a minimal thickness. Shoulderless design has been always
unanimously acknowledged as the most conservative approach towards dental structure
and the less prone to marginal gap.

7. The edgeless approach
 known also as gingitage, was born with the work of Vick Pollard and Rex Ingraham. A
variant of this approach was proposed by Morton Amsterdam and later by the team of Di
Febo and Carnevale (Mascarella’s school) and recently by Ignazio Loi (BOPT).

8. The edgeless approach, distinct from shoulderless approach, aims to
place finish lines subgingivally and to seal the preparation coronally
to the finish lines on the prepared portion of the tooth with the
indirect restoration, according to the need of the technician and the
clinician.
This approach, useful in periodontally compromised teeth, was not
well suited for periododontally sound teeth, often resulting in
irreversible damage to the periodontal attachment. Moreover this
approach would be truly aggressive in the pericervical area
and would result in a rough prepped surface on the uncrowned and
exposed area.
The suggested burs and protocol of Mascarella's school and BOPT
are not easy to be handled without a high level of
magnification (microscope) and require exceptional dexterity in
preparing teeth.

9. BOPT approach clinician and technicians have
therefore to face the following problems:
 - Problematic and inevitable undercuts
 - Excessive taper of the prepared tooth
 - Inevitable damage of connective attachment
 - Profuse bleeding
 - Six weeks of waiting/healing period prior to impression
 - Unpredictable soft tissue regeneration
 - Time consuming trial and error on temporaries during the healing period
 - Absence of a neat, clear-cut, visible finishing area and finish lines
It has been a common and frustrating experience among the colleagues starting to practice
the Mascarella’s approach.

10. The three aims of this preset paper are:
 A- Demystify the “hypothesis” of periodontal damage from vertical finish lines
 B- Show the biomechanical advantages of the vertical finish lines
 C- Introduce a completely new approach in designing and managing the vertical finish
lines

11. Part A
Demystify the “hypothesis” of periodontal damage from vertical
preparation
This new technique is periodontally and biologically friendly. With the aid of the special burs it is
virtually impossible to violate the Biological Width (BW).
BW is defined by the sulcus, the junctional epithelium (JE) and the connective tissue attachment (CT).
The only structure that has a biologic reaction after invasion is the connective attachment. We may
highlight that the JE is not important, as it may simply be juxtaposition of epithelial structures on a
surface, that in a “healthy environment” is represented by
 - the enamel
 - the emidesmosomes, connecting epithelial cells to a surface as long as this surface is hard,
smooth and clean. This surface may be either enamel, cement, dentin, composite or zirconia.

12. Rotary curettage performed inside the sulcus area or in the JE zone is actually an advantage
because it produces a smooth, non lacerated, sulcular wall surface compared to other
techniques like electrosurgery or retraction chords. This wound heals by re-epithelization of
exposed connective tissue from contiguous oral epithelium. The formation of a new lamina
propria and junctional epithelium and a return to the original quality and distribution of
microvascularization of the tissue, occur rapidly and predictably.
The sooner the final restoration (crown) is delivered the better will be GUIDED the
regeneration of the new pattern of epithelium. This represents the core of the
approach borrowed from the post-extractive immediate loading of implants
the cervical anatomy provided from our technician will GUIDE the regeneration of the
tissues.
Violation of the CT attachment (and in particular of the root cementum into whom the
connective tissue fibers insert) induces an inflammatory reaction leading to the production
of inflammatory molecules (proteases, cytokines, prostaglandins, and host enzymes), that
will activate osteoclasts to induce bone resorption and risk of soft tissue recession. This is to
be avoided.

13. In the technique proposed over these years by other authors (Di
Febo, Loi, etc.) the introduction of the bur in the sulcus was very
dependent by the operator’s skills and feeling.
With the technique proposed by the authors the violation of BW is
virtually impossible because the non-working tip of the special
bur is calibrated in order not to touch the first millimeter of the root
where the connective tissue fibers insert into the cementum.
Moreover the possibility to use a smaller tip in comparison to
conventional vertical preparation techniques allows a rotary
curettage involving only the epithelial component of the sulcus with
minor or no bleeding and faster healing.

14. It is critical, in case of sub-gingival finish lines, that the crown
restoration be designed with an emergence profile that will support
the gingival tissues and cause them to produce a tight gingival cuff
that will act as a tight gasket around the crown’s cervical area. A
tight cervical cuff will protect against food impaction in the gingival
sulcus as well as prevent plaque and tartar from accumulating
inside the loose gingival tissues on the untreated surface of the
tooth. The emergence profile advocated here is considered to be
over-contouring by conventional standards. The concept presented
here is borrowed from the anatomy of the emergence profile of
enamel on natural teeth and its relationship to the gingival tissues
in the early dentition.

15. Papilla Predictability


16. In periodontally healthy teeth the use of a non
cutting tip allows not only to do a better controlled
invasion of the sulcus , but to accomplish two critical
elements:
- a more conservative preparation of the tooth
- the maintenance of a non-prepared area of the
Tooth (shoulderless approach). The convergence of
the root with the neighboring teeth keeps the same
inter-root distance and allows to maintain and get
better inter-proximal tissues.

17. PART B
showing the biomechanical advantages of the vertical finish lines
 The biomechanical perspective in the tooth abutment design is
intimately correlated with the concept of ferrule. The word “ferrule” has
been widely misunderstood over the years and not properly addressed.
In common usage the word “ferrule” is referring to the residual dental
structure in two dimensions when it really refers to the “ferrule effect.”

18. Ferrule is a corruption of Latin “viriola” (small bracelet) under the
influence of “ferrum” (iron).
Ferrule is any of a number of objects used for fastening, joining or
reinforcement. They are often narrow circular metallic rings. Thus,
the ferrule in prothetic dentistry is the PROSTHETIC CROWN, which
is going to fasten, like a bracelet, the residual dental structure.
As in mechanical engineering, the ferrule in prosthetic dentistry
should have designed and built according to these two following
features:
- being built in a material with modulus of elasticity larger than that
of dental structure
- being designed not at the expense of residual dental structure

19. First then, the crown should be in material with high modulus of elasticity, as
metals or zirconia. Material like composite or similar are not suitable for this
goal.
Second, being not at the expense of the residual dental structure, means that
we should not reduce residual dental structure, i.e. the dentin, especially the
pericervical dentin (PCD). To distinguish common usage of ferrule from the
remaining tooth structure, Clark and Khademi refer to this remaining tooth
structure as 3DF three-dimensional-ferrule.
Enamel to some extent is not a structural material. It’s main functions are to seal
the denting and protect the tooth from wear. These two functions are in some
way “replaceable” by prothetic material. Evidence that enamel is not necessary
for long-term tooth survival is given by the many cases of recession with
exposed root structure, often with little or no functional impairment.

20. The primary problem with all “horizontal” finish line designs is that
the ferrule effect is created at the expense of the residual dental
structure: the 3DF. This is further aggravated by more apically
placed finish lines in a futile attempt to improve retention, as
dentin thickness decreases.
This is very detrimental, especially in endodontically treated teeth.
The shoulder version of the horizontal finish line is the worst
scenario, because not only it reduces the thickness of the 3DF but
but it creates a stress-concentration point at the shoulder itself
undermining the ferrule effect it was attempting to provide.

21. Super imposition of different preparation designs
- shoulderless
- chamfer of 0.4 mm above finish line
- chamfer of 0.8 mm above finish line

22. The only way we have to prep the “ferrule” without affecting the
3DF is to avoid any “horizontal” invasion (like shoulder or
chamfer), but to create a shoulderless preparation.
For the ferrule to be effective, the residual dental structure
should be well engineered by the dentists. The clinician should
prepare the abutment maximizing the 3DF taking care of the
following parameters about the remaining dental structure:
- thickness
- height
- spatial position

25. PART C
introducing a new approach in designing and managing vertical
finish lines
 Integral to these preparation protocols is a round-ended tapered diamond bur with a
non-cutting end.
 This bur is well known in the endodontic field as Batt-Bur.
 This bur has the following advantages:
 - Taper of about 2 degrees facilitates an optimal taper of the abutment
 - Coronal diameter of 1.2 mm and apical diameter of only 0.7 mm facilitate a very
conservative approach.
 - Non-cutting end of 1 mm reduces or avoids the damage to the connective
attachment.
 - Non-cutting end of 1 mm allows-facilitates a tooth-guided preparation procedure.

26. - Facilitates a machined preparation. What you drill is what you get.
- Non-cutting end allows a bloodless gingitage, creating space for the
immediate impression and an easy provisional relining.
- Non-cutting end allows to work in the presence of cord or teflon tape, without
any tearing or impingement.
- Bur design allows even the non-expert clinician to avoid any undercuts into
the prepped abutment.
- Non-cutting end allows to be used as a periodontal probe.
- Design differs from flame burs used in the approach of Mascarella’s school
and BOPT, allowing a pure geometrical frustum and true vertical finish lines.
- Encourages immediate impression and provisionalization, in contrast to the
other approaches.

27. Used kit in shoulderless prep