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10 cosmetic section DENTAL TECHNOLOGY, APRIL-JUNE 2023

TECHNIQUES IN CERAMIC VENEERS:

EXPERIMENTAL VS TRADITIONAL TECHNIQUES

AND THE MP TECHNIQUE

MIKE PROSPERINO, CDT AND DR. ANTONELLO MARIA MESSINA, DDS

One of the most outstanding achievements of cosmetic dentistry in CLINICAL CASE 1
recent years has come from the aid and development of new mate- A 39-year-old patient presented to the office because she was dissat-
rials. The effect of depth when we perceive the colour of teeth is due isfied with her smile, particularly the shape and colour of her upper
to the degree of translucency of natural dentin and enamel, in dif- incisors. An intraoral clinical examination showed a class II maloc-
ferent layers overlapping each other in a completely natural and clusion with deep bite and multiple diastemas in the frontal sector.
individual way. Also, it marked discolouration of the upper central incisors and loss
In this article, in addition to presenting traditional techniques of of substance at the incisal level of the left central incisor (Figure 1).
using millable and pressable aesthetic materials, a new experimen- Specifically, the patient reported a medical history of previous ortho-
tal procedure of coupling the two approaches, the CAD/CAM tech- dontics at the age of 32 years that lasted about 2 years and then of
nique and lithium disilicate pressing technique, will be presented. onset of aggressive periodontopathy treated surgically at 37 years.
The evolution of these technologies and materials based on their Despite the resolution of the periodontal disease, the patient was
optical characteristics has significantly changed the approach and not satisfied with the aesthetic result. This was partly due to
predictability of results. The goal of this work is to demonstrate how diastemas between the upper incisors and partly due to the alter-
with the coupling of feldspathic ceramic to a disilicate core, whether ation of the interdental papillae that created black triangles in the
made by pressing technique or computer-assisted, optimal results cervical interproximal areas. We then proceeded as a team with the
can be achieved and open new horizons and spectrums of applica- dental technician to study the case and take an impression for a
tion, especially in the resolutions of additive veneers where dental diagnostic wax-up and mock-up (Figure 2).
preparation is absent or minimal. A careful aesthetic-periodontal evaluation revealed the possibility
of correcting the gingival architecture to give harmony to the smile
PROPERTIES AND CHARACTERISTICS OF DENTAL SUBSTANCE without resorting to the new surgery. Thanks to the calibrated wax-
Dental enamel plays a dual and vital role: up and precise direct printing of the mock-up (Figure 3), we used
grinding food
protect the underlying dentin by its increased resistance to wear the same to perform calibrated preparation of the four frontal ele-
and tear . ments (Figures 4 and 5). Next, we took the impression and
[1]
reprinted a new mockup for provisional use. Finally, with the dental
On the other hand, one of the tasks of the underlying dentin is to technician, we decided to perform an aesthetic-functional rehabili-
absorb chewing forces due to its very high resistance to compressive tation using 4 feldspar ceramic veneers made on refractory, thus bal-
forces . In the current state of the art, it is not yet possible to use ancing and harmonising the patient's smile.
[2]
a material that can fully meet the compliance of the tooth substance After preparing the master alveolar model and preparing the
to which a ceramic restoration is applied. Moreover, no in vitro test structures for the first layering, we proceed to the construction of
can, unfortunately, simulate the complex situation of elasticity and the dentine (Figure 6). At this stage, it is imperative to keep dentin
function of the dental substances in the patient's mouth . in mind during restorations where a relatively large portion of the
[3]
lost tissue must be reconstructed; in this case with veneers, dentin
CERAMIC MATERIALS is one of the fundamental pillars of the final colour to be achieved.
The bibliography is rich in studies on the effectiveness of the mate- We use a silicone palatal template (Figures 7 and 8) to control the
rials available today. The continuous development of products and proper placement and size of the buccal mamelons.
techniques considerably broadens the application spectrum of inte- After constructing the dentin, we apply enamel light calibrated as
gral reconstruction materials. The same is true for their very high per the manufacturer to acquire the final tooth colour. After devel-
tissue biocompatibility, which classifies them as bioinert materi- oping festoons on the incisal margin, transparent enamel is layered
als , and their high survival rates ranging from 93% at 10 years to over the already applied enamel to imitate the classic transparencies
[4]
91-94% at 12 years. We can fire ceramic materials on both refracto- of central incisors (Figure 10). Next, we used lateral opalescent
ry & platinum sheets and lithium disilicate cores (Ref. McLean enamels to mimic the classic bluish transparencies present in natu-
Bibliography). ral teeth (Figure 11). Next, we layered mamelons (honey mamel-
These materials' weakness is their poor fracture toughness with a ons) over the transparent and opalescent enamels (Figure 12).
modulus of elasticity ranging between 50 and 120 MPa [6] . The entire layering is covered with a mixture of enamel and clear
Their strength increases significantly after their cementation, the coat to give final shape and vitality to the reconstruction. We selected
distribution and interaction of the crystals within the glass matrix this final mixture to give the underlying dentin a path to shine through
after the material's various silanisation and etching steps that give and reflect the reconstruction to its final colour (Figure 13).
the finished artefact an intimate chemical bond with the tooth Ultimately, the ceramics are ready for the first dentin and glaze firing.
substance. During firing, it is crucial to place the refractory dies on the firing
The latest generation of lithium disilicate ceramics has increased stand at a 45-degree angle so that when the ceramics are sintered in
their flexural strength by about 70%, significantly increasing the the firing furnace, the incisal margin does not lose its layered posi-
spectrum of indication and application . By exploiting these char- tioning due to the attraction effect of the furnace resistances. We
[7]
acteristics, the authors claim that we can obtain ceramisable cores paid particular attention to the final temperature of the first firing
of very high strength, controlling our reconstructions' varying as it must be raised by about 10 degrees more than the manufactur-
degrees of transparency and translucency. er's indication due to the heat absorption of the refractory materials