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Emerging evidence points towards significant interrelations between the condition of the peri-implant tissue and the implant-abutment-prosthesis complex. A new paradigm is essential, where the peri-implant tissues will be studied in close interrelation with the implant, abutment and prosthesis complex, under the presence of oral biofilm. The aim of this paper is to introduce the concept of the "Implant Supra-crestal Complex" (ISC) and describe the critical elements that define it as a unique anatomic, and functional system of human tissues, mechanical components and oral bacteria / biofilm. The paper reviews recent evidence to identify the impact of design features on both short-term clinical outcomes, as well as on the long-term health of the peri-implant bone and soft tissues. Prosthetic-driven implant placement is the prerequisite for the proper design of the ISC, which in turn can indirectly influence the structure and dimensions of the peri-implant soft tissues. Design features of the implant-prosthesis-abutment complex such as the Emergence Profile (EP), Emergence Angle (EA) and Cervical Margin (CM), as well as the design of the implant-abutment and abutment-prosthesis junctions and their location in relation to the tissues of the ISC can have significant impact in the maintenance of stable and healthy peri-implant tissues in the long term.
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The Implant Supracrestal Complex and its significance for long term
successful clinical outcomes
Published in: International Journal of Prosthodontics, January 2021
Mattheos N 1,2, Vergoullis I 3,, Janda M 4, Miselli A 5.
1. Department of Oral and Maxillofacial Surgery, Faculty of dentistry Chulalongkorn
university, Bangkok, Thailand
2. Department of Dental Medicine, Karolinska Institute, Sweden
3. Department of Periodontics, Louisiana State University, USA
4. Department of Prosthodontics, Malmö University, Malmö, Sweden
5. Department of Prosthodontics, Universidad Central de Venezuela, Caracas, Venezuela
Corresponding author: Nikos Mattheos, DDS. MASc, Ph.D.
Department of Oral and Maxillofacial Surgery, Faculty of dentistry, Chulalongkorn University,
Bangkok, Thailand
34 Henri Dunant Road, Wangmai, Patumwan, Bangkok, Thailand 10330
Tel.: +662218-8587
Fax.: +66-2218-8581
e-mail: nikos@mattheos.net
Keywords: implantology, peri-implant tissues, implant supra-crestal complex, implant
transmucosal complex.
DO I: 10.11607/ijp.7201
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Abstract
Emerging evidence points towards significant interrelations between the condition of the peri-
implant tissue and the implant-abutment-prosthesis complex. A new paradigm is essential,
where the peri-implant tissues will be studied in close interrelation with the implant, abutment
and prosthesis complex, under the presence of oral biofilm. The aim of this paper is to introduce
the concept of the “Implant Supra-crestal Complex” (ISC) and describe the critical elements
that define it as a unique anatomic, and functional system of human tissues, mechanical
components and oral bacteria / biofilm. The paper reviews recent evidence to identify the
impact of design features on both short-term clinical outcomes, as well as on the long-term
health of the peri-implant bone and soft tissues. Prosthetic-driven implant placement is the
prerequisite for the proper design of the ISC, which in turn can indirectly influence the structure
and dimensions of the peri-implant soft tissues. Design features of the implant-prosthesis-
abutment complex such as the Emergence Profile (EP), Emergence Angle (EA) and Cervical
Margin (CM), as well as the design of the implant-abutment and abutment-prosthesis junctions
and their location in relation to the tissues of the ISC can have significant impact in the
maintenance of stable and healthy peri-implant tissues in the long term.
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Introduction
A multitude of terms has been utilised to describe the peri-implant tissue coronal to the
marginal bone. Initial terms were a direct extrapolation of periodontal terms from the concept
of the “Biologic Width” (1) to the recently introduced “Supracrestal Tissue Attachment” (2).
The significant anatomic and structural differences however between periodontal and peri-
implant tissues, (with the latter displaying “attachment” only at the level of the junctional
epithelium), do not allow for a direct extrapolation of terms from the periodontium.
Consequently, the terms “Peri-Implant Soft Tissue Barrier” (3), “Peri-implant Mucosa” (4),
“Implant Mucosal Tunnel” (5) and most recently the specific “Peri-implant Phenotype” (6)
have been suggested to describe the peri-implant tissues.
Although such definitions appear adequate to describe the soft peri-implant tissues, there is an
increasing body of evidence pointing towards significant interrelations between the condition
of the peri-implant tissue and the implant-abutment-prosthesis complex, all this under the
constant presence of oral bacteria. Emerging evidence suggests that factors such as the type of
implant-abutment junction and prosthesis design and retention can have significant influence
on both short-term clinical outcomes as well as the long-term health of the peri-implant bone
and soft tissues (7,8).
Consequently, a new paradigm is essential, where the peri-implant tissues will be studied in
close interrelation with the implant, abutment and prosthesis complex, under the presence of
oral biofilm, as one multi-element, anatomic and functional unit. In such a system of close
anatomic and functional interaction of the mechanical components and the human tissues,
deficiencies or problems in one of the parts might manifest problems clinically through
complications in any of the other. Such a paradigm is well aligned with the emerging concept
of health and chronic disease being perceived as Symbiosis or Dysbiosis, the outcome of
complex interactions between human, tissues medical devices such as dental implants and
bacteria (9-11).
The aim of this paper is to introduce the concept of the “Implant Supra-crestal Complex” (ISC)
and describe the critical elements that define it as a unique anatomic and functional system of
human tissues, mechanical components and oral bacteria / biofilm. Furthermore, this paper
aims to review the current evidence on critical design features of the Implant Supracrestal
Complex, which can contribute to long term sustainable and healthy outcomes or introduce
risks.
A. Anatomy and components of the Implant transmucosal complex.
The anatomic structures of the human tissues, the mechanical components of the Implant,
abutment and prosthesis and the oral bacteria are closely interrelated towards maintaining
health, as expressed through clinically stable long-term outcomes. In this capacity, the Implant
Supracrestal Complex displays elements of homeostatic regulation and the tissues of the ISC,
are in close anatomic and functional relation to mechanical components through the interface
of osseointegration and epithelial attachment. Homeostasis can be thought of as a dynamic
equilibrium rather than a constant, unchanging state, where tissues and cells respond to
constant internal and external changes in order to maintain long term anatomic integrity and
function
1) Anatomic structures of human tissues in the ISC
From apical to coronal in vertical direction, the tissues of the Implant Supra-crestal Complex
are defined by the Marginal Bone (MB), the Connective Tissue (CT), the Junctional Epithelium
(JE) and the Sulcus (S) with the sulcular epithelium.
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CT in implants appear with no vascular supply close to the abutment and very few fibroblasts,
resembling more a scar tissue; this is likely attributed to lack of the PDL vascular complex (3).
Blood vessels originating from the supra-periosteal complex are located in the lateral borders
of CT and JE zone. These blood vessels are the origin of the immune response to bacteria in
the sulcus (12,13). Similar to teeth, peri-implant crevicular fluid is produced, which flows into
the sulcus through the junctional epithelium. Analysis of peri-implant crevicular fluid (PICF)
for protein biomarkers such as pro-inflammatory cytokines, chemokines and bone turnover
markers can reveal clinical and sub-clinical inflammation (14).
Although the great majority of histomorphometry available comes from animal studies, human
studies point to the zone of the connective tissue and the junctional epithelium occupying
between 3 and 4.5 mm (3,15) in a vertical dimension. This zone previously called “Biologic
Zone” or “Biologic Width” (3) might be genetically determined. Although individual studies
have suggested small differences in the dimensions of the JE and CT dimensions when different
surfaces were used (3, 16), or when 2-piece were compared with one-piece implants (17), at
present no intervention, surface or implant design has been shown to predictably achieve any
morphological or structural changes of these tissues (18,19). As with all anatomic structures it
is reasonable to assume that the dimensions of the CT and JE could present with natural, limited
variation between different individuals, different anatomic locations (20) or sites of the peri-
implant tissues.
In contrast to the JE-CT zone, the peri-implant sulcus varies significantly in depth depending
on the local anatomy, the implant position, or between different sites around the same implant,
especially in the anterior maxilla (21,22). Unlike natural teeth, where the healthy sulcus extends
between 0.5-1.5 mm in depth, peri-implant sites might present with much deeper sulcus. The
natural scalloping of the gingival tissues observed around teeth is a result of the corresponding
scalloping of the underlying bone and the corresponding shape of the cementoenamel junction
(Figure 1). Such scalloping of the tissues has not been possible to maintain around implants
and the use of scalloped dental implant resulted in increased bone loss (23). Consequently, the
scalloping of peri-implant soft tissues - primarily pronounced in the aesthetic zone - is only
possible with a peri-implant sulcus depth of 3-5 mm at interproximal sites, while the same in
the buccal sites of the implant could be as little as 0.5-1.5 mm. It is therefore evident that the
concept of Supracrestal Attachment as described around natural teeth cannot be applied to the
peri-implant tissues. Similarly, a peri-implant sulcus deeper than 3 mm is not to be confused
with a periodontal pocket. The former is the outcome of tissue healing around a clean
biomaterial surface, while the latter is the result of slow apical migration of the junctional
epithelium, due to the challenge of biofilm induced chronic inflammation.
Taking into consideration the above information it becomes important to establish a minimum
peri-implant supra-crestal vertical tissue height of about 3 to 4.5 mm which will accommodate
adequately the biologic demands of sustainable health. In cases where the vertical height of the
peri-implant tissue is less than 3mm, marginal bone resorption has been often reported around
the implant platform. This might be a physiological remodeling, resulting in re-establishing the
vertical dimensions required to accommodate the soft tissues at the expense of the crestal peri-
implant bone. Several researchers have correlated this pattern of early bone resorption, to the
pre-operative supra-crestal gingival tissue height (24-25).
2) Characteristics of Implant – Abutment – Prosthesis
The critical design characteristics of the Implant-abutment-prosthesis complex (IAP), which
have been shown to impact the configuration of the peri-implant marginal bone and soft tissues,
will be discussed separately for Bone level and Tissue Level implants. As Tissue level implants
the authors consider all implants with a smooth transmucosal collar which varies from 0.5 to 3
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mm in vertical height. Bone level implants on the other hand are implants without a
transmucosal part and which are intended to be placed with bone contact for their entire length ,
while the transmucosal part is facilitated through a detachable abutment. Furthermore, as
Platform Switching is defined a horizontal discrepancy between the diameter of the implant
shoulder of bone level implants and the diameter of the corresponding abutment (26).
Two critical design features of the IAP intended to be in close contact with the peri-implant
soft tissues are the Emergence profile (EP) and the Cervical Margin (CM). The shape, position
and dimensions of both the EP and CM could significantly influence the short as well as long-
term outcomes of implant treatment.
Furthermore, the IAP contains two important interfaces, the Implant-abutment junction (IAJ)
and the abutment-prosthesis junction (APJ).
Understanding the influence such design choices can have on the healing and the long-term
configuration of the bone and soft tissues is essential for successful clinical outcomes.
i. Emergence Profile (EP)
The term Emergence Profile (EP) is defined in the 9th edition of the Glossary of Prosthodontic
terms as “the contour of a tooth or restoration, such as the crown on a natural tooth, dental
implant, or dental implant abutment, as it relates to the emergence from circumscribed soft
tissues”. No differentiation is being made in this definition with regards to implants and teeth,
while the emphasis is placed in its interrelation with the “circumscribed soft tissues”. For the
purpose of this paper and based on the implant literature so far, we would further define the EP
as the entire transmucosal part of the IAP, which extends from the most coronal part of the
peri-implant mucosa to the implant platform of a bone level implant, or to the most coronal
intraosseous segment for the Tissue level implant respectively (Figure 1). In the case of Tissue
Level implants, the soft tissue collar of the implant constitutes the apical end of the emergence
profile. The function of the emergence profile is to ensure a proper transition from the implant
to the Cervical Margin, while allowing for adequate space for the peri-implant tissues.
Emergence Angle likewise, was defined as “the angle between the average tangent of the
transitional contour relative to the long axis of a tooth, dental implant, or dental implant
abutment.” Emergence Angle has been initially defined on natural teeth and was calculated by
bringing the tangent line on the crown to the point corresponding to the gingival margin. Thus
as defined on natural teeth, EA presented the angle of the tooth or prosthesis crown at the exact
“point of emergence” through the gingival tissues (27,28).
Two recent studies (7,29) have measured the EA mesial and distal of implant restorations,
using periapical radiographs. The major limitation of the radiographs however is that it does
not allow for estimation of the soft tissue margin, thus calculation of the EA was conducted
without any relevance to the actual “point of emergence”, which was invisible in the
radiographs. Instead, two points were defined, one in the shoulder of the bone level implant or
the collar of the tissue level implant and a second in a selected point of the profile of the
prosthesis and the tangent line was drawn. The clinical relevance of defining the emergence
angle in this manner and what does it actually represent remains to be further clarified. Such
measurements include a significant risk of subjective judgement, as the convexity or concavity
of the emergence profile might influence the position of the second point and consequently the
tangent line. Furthermore, the true emergence and level of the soft tissues is not considered in
the calculation of the EA, which might reduce the clinical relevance. Finally, when
measurement is conducted on tissue level implants the first point is placed in a different
location of the supracrestal complex than when in bone level implants, which could also
seriously affect the calculation of the EA.
Bone level implants allow for the design of the emergence profile in its entirety and the angle
of the emergence can be determined by the prosthetic abutment. Although “prefabricated” or
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“catalogue” abutments offer very little variation of the Emergence profile, current CAD/CAM
custom made abutments allow for individual design of critical elements such as emergence
angle and convexity/concavity. Even prefabricated abutments today in many implant systems
come with different cuff height, thus allowing the selection of different angles for the
Emergence profile. The additional ability of platform switching on bone level implants
facilitates further customisation of the EP.
The Emergence profile of Tissue level implants starts with the implant smooth collar, which
corresponds to the apical part of the abutment of bone level implants. This smooth collar
provides the surface for CT adhesion and, depending on height of collar, possibly the whole or
part of the JE attachment. Both the angle and height of the soft tissue collar varies significantly
between different implant systems, or even implants of different types within the same system.
Consequently, the design of the Emergence Profile is predetermined for the most apical couple
of millimetres, as height and angle is defined by the design and dimension the soft tissue collar.
This prefabricated microgeometry together with the lack of platform switching could limit our
options when designing the Emergence Profile in such implants. Two studies (7,29)
investigating the impact of the Emergence Profile in Peri-implantitis prevalence, have however
excluded the transmucosal collar when calculating the Emergence Angle in Tissue Level
implant reconstructions. This might lead to inconsistency when attempting to assess the impact
of the Emergence Profile between Bone and Tissue level implants.
ii) Cervical Margin
The term Cervical Margin of the Prosthesis (CM) refers to the circumferential margin where
the most coronal border of the peri-implant mucosa receives the most apical visible portion of
the prosthesis or “cervix”. Terms as “restoration contour” or “soft tissue contourhave been
used interchangeably in the past to describe this margin. The authors however would like to
emphasize that the term Cervical Margin is a feature of the implant prosthesis, which is subject
to the planning and design of the clinician, while the peri-implant soft tissue margin is the
respective feature of the peri-implant mucosa, formed in response to the CM. Around natural
teeth, the Cervical Margin will coincide with the most coronal part of the periodontal sulcus.
In implant supported prosthesis, the CM is a prosthetic concept which is defined by the visible
portion of the implant crown (Figure 2). Again, the Cervical Margin ideally coincides with the
most coronal part of the peri-implant sulcus.
iii) Implant-abutment junction
The interface between the implant and the abutment is probably the most studied and best
documented junction, which has evolved significantly as a result. The original configuration
of an external hex, flat-to-flat connection of the Brånemark implants, has been followed by a
wide arrange of designs, most notable changes being the internal, tapered connections and the
concept of platform switching. The original flat-to-flat external connection was reported to
allow wider micromovement (30) and also potential microleakage (31). The fact that in this
configuration the implant-abutment junction was placed at the bone level, might have been the
reason for the marginal bone resorption or remodeling observed during the first months post-
surgery, which might have led to the wide acceptance of 1.5mm marginal bone loss during the
first year post surgery as a biologic consequence of bone remodeling (32). Bacterial and fluid
microleakage has been related to oral malodour, inflammation and marginal bone loss, apart
from the potential technical implications it could have for the long-term tight fit of the
connection (33,34). On the other hand, implants with an internal tapered connection and
platform switching have been shown to increase connection fit and stability (30, 35),
effectively prevent microleakage (36), while interface gaps are found to be no more than 1-2
μm (Figure 3) (37). Albeit implants with such configurations have demonstrated clinically less
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marginal bone remodeling during the first and also consecutive years post-surgery (38, 39),
microbiological investigations have shown bacterial contamination of the implant abutment
junction in both external and internal connection types after 5 years in function (40). Seen
collectively, such results suggest that although the connection design might influence bacterial
activity levels qualitatively and quantitatively, no design has been shown to be clinically
completely immune to effects of microleakage in the long term. At the same time, it should be
noted that not all implant configurations might achieve very tight fit of the implant-abutment
junction, in particular when third party prosthetic components are used (Figure 4)
Tissue level implants are not designed to have an implant-abutment junction at the bone level,
but more coronally in the ISC, depending on the height of the implant soft tissue collar. In the
time of flat-to-flat external hex connections, the absence of an implant-abutment junction on
Tissue level implants was considered by many a “safer” configuration, as it eliminated the risks
associated with the junction being close to the marginal bone. Nevertheless, the height of the
soft tissue collar is an important parameter, seen under the light of the current understanding
of essential vertical dimensions of soft tissue. A soft tissue collar of less than 2mm might be
too short to properly accommodate the adequate soft tissue vertical dimensions. Furthermore,
the implant-abutment junction on tissue level implants is less precise, even if tight. As the
abutment sits externally on the implant collar, minor vertical discrepancies are shown to result
in a significant “undercut” of 50-100 μm (Figure 5) (41), which if populated with biofilm might
turn into a plaque retentive point. As this junction almost always is located in the apical section
of the sulcus, continuous apical migration of the biofilm reaching this point could exacerbate
the vicious circle of peri-implant tissue inflammation. This might reduce our ability to disinfect
the implant after being affected by Mucositis, if this junction is placed deep in the ISC (5).
iv) Abutment-prosthesis junction
The abutment-prosthesis junction (APJ) can be present in both bone and tissue level implants
but varies significantly between implant systems and types of restoration. In certain “one piece”
APJ configurations (e.g. precious alloy abutments where the prosthesis is being cast on the
abutment) this junction might not be detectable clinically, as the abutment and the prosthesis
are fused. When present, the abutment-prosthesis junction is intended to be within the sulcus
and thus it is of high clinical significance.
The interface between the implant and the prothesis is commonly structured in four different
ways (Figures 6-7 / a,b,c,d):
a. Prosthesis cemented on an extra-orally cementable, screw-retained abutment, such as a
Ti-base.
In this configuration, the often milled or CAD/CAM prothesis will be cemented outside the
mouth. The prosthesis-abutment complex is then polished and placed in the mouth as a one-
piece, screw retained restoration (42)
The extraoral cementation eliminates the risk of cement rests, yet a thin layer of cement is very
likely to be exposed in the abutment-prosthesis junction, even at ideal conditions (Figure 8)
(43). Even when tight, the interface between abutment and prosthesis in such cases can result
in some discrepancies that can act as plaque retention points. A alternative configuration is
prosthesis cast on top of a base abutment, which will result in a one-piece restoration without
any clinically detectable interface between abutment and prosthesis.
b. Prosthesis cemented on an intraorally cementable, screw-retained abutment
In this configuration, the prothesis will be cemented in the mouth typically due to aesthetic
requirements when the implant angle is not optimal. In such cases the abutment-prosthesis
junction coincides with the cementation level, so it is important to place it as close to the sulcus
opening as possible. The risk of cement rests increases significantly when this junction is
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placed deeper in the sulcus (44). Cement rests can constitute a major long term risk either being
pushed under the junctional epithelium jeopardizing the integrity of the ITC and/or through
acting as plaque retention points (45).
c. Prosthesis retained by a screw on an intermediate abutment.
This configuration will result in a reconstruction with one or two screws for every
implant. Tight fit of both the implant-abutment and abutment-prosthesis junctions is
paramamount to prevent microleakage and plaque retention.
d. Prosthesis directly to the implant (without an intermediate abutment).
A typical example would be a milled bridge on implant level. This will result in one screw
retaining the prosthesis on each implant. Studies have shown prostheses of that type on bone
level implants to present with increased risk of bone resorption (46), possibly related to
increased risk of misfit. The tight fit of this junction as well as the absence of misfit,
discrepancies and gaps is of paramount importance, otherwise bacterial products through
microleakage and / or plaque retention will directly affect the sulcus. In-vitro studies have also
documented that even small misfit in bridges with this configuration can have detrimental
effects to the veneering as well (46). Certain laboratory manufacturing processes resulting in
an oxidation layer on surface of the prosthesis might affect the tight fit, as the oxidation layer
has to be often removed with sandblasting, thus altering the prosthesis surface which connects
with the implant (41) .
3) Bacteria – Oral Biofilm
Plaque accumulation is detrimental for the health of peri-implant tissues. Studies of
experimental peri-implant mucositis in humans have shown that undisturbed plaque
accumulation will lead to inflammation of the peri-implant tissues within three weeks without
any exceptions (5, 48-50). At this point it is important to emphasize that detrimental peri-
implant inflammation is not caused by the presence of bacteria in the sulcus in planktonic status,
but rather the result of accumulation of mature pathogenic biofilm. Biofilm formation requires
a solid hard surface and a liquid environment infected with bacteria. As both conditions are
met on the surface of the prosthesis, Biofilm forms first on the part of the prosthesis exposed
in the oral cavity and it first interacts with the soft tissues at the Cervical Margin. Establishment
of a mature, pathogenic biofilm at the Cervical Margin will require at least 7-14 days, after
which it will provoke the immune response and lead to inflammation of the oral mucosa (5,48-
50). In the case of oral mucosa not in proximity to implants, the inflammation remains limited
superficially in the mucosa, as for example under an uncleanable prosthesis pontic or a denture.
However, biofilm accumulation in close proximity with the peri-implant sulcus leads to
inflammatory response from the peri implant soft tissue margins and the sulcular epithelium,
leading to peri-implant mucositis, kickstarting a vicious circle eventually resulting to apical
migration of the junctional epithelium, peri-implantitis and formation of peri-implant pocket.
There is at present no evidence that the depth of sulcus will influence the initiation of peri-
implant mucositis. On the contrary, a study of experimental mucositis (5) showed that peri-
implant tissues around shallow and deep sulci remained equally healthy with the application of
professional maintenance care and patient performed oral hygiene, thus maintaining the
cervical margin free of biofilm. The same study however, suggested a less favorable pattern
of resolution when peri-implant mucositis was initiated in tissue level implants with a deeper
sulcus.
B. Clinical implications for the design of the Implant Supra-crestal Complex
i) ISC and plaque induced peri-implant inflammation
Recent evidence has demonstrated that peri-implant tissue in particular mounts a greater host-
inflammatory response to plaque accumulation than those at teeth (51), suggesting that plaque
control around implants may be of critical importance in averting the cascade of destructive
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inflammatory peri-implant disease. There are two main factors that can expose the peri-implant
sulcus to the detriments of biofilm accumulation: deficient oral hygiene and improper design
of the Cervical Margin. The former one requires the proper training and motivation of the
patient, while the latter is an iatrogenic condition. When the Cervical Margin coincides with
the coronal margin of the peri-implant sulcus, oral hygiene can efficiently remove the biofilm
from the proximity of the sulcus (Figure 2). On the contrary, a non-anatomical Cervical Margin,
as this is created by the commonly used, cylindrical in shape, stock abutments, can be located
away from the sulcus resulting in a horizontal discrepancy between cervical margin and sulcus
or “Ridge Lap”. Plaque accumulation in proximity of the sulcus can then proceed with little
or no inhibition from oral hygiene, posing a significant risk and increasing the prevalence of
peri-implantitis (52). The wider the prosthesis the bigger this Ridge Lap becomes; in particular
as we move from the anterior to the posterior site restorations, since the lateral size of the
prosthesis increases. An improper Cervical Margin could furthermore inhibit monitoring of the
health of peri-implant tissues, preventing efficient probing or resulting in false negative
probing depth, thus underestimating the extent of bone loss (53). As the design of the Cervical
Margin is a key for access to oral hygiene and sustainability, calculation of the Emergence
Angle in implant prosthesis for exactly this location might be a much more clinically relevant
measurement, as it was conducted on natural teeth. A tangent line to the Cervical Margin of
the implant prosthesis might reflect the ability to maintain oral hygiene much more precisely
than a line drawn for the whole Emergence Profile. A wide Emergence Angle there would
approximate a ridge lap and inhibit Oral Hygiene, while a narrow one will resemble the
emergence angles reported for natural teeth (27,28). To do such a calculation on implants
however, we will require a precise location of the mucosal margin, which cannot be done
through radiographs.
Avoiding the need for a ridge lap design necessitates the placement of the implant in the
optimal restorative position, angle and depth (Figure 9). Katafuchi et al showed a correlation
between the depth of placement of bone level implants and the emergence angle, with the latter
being more favorable when implants were placed subcrestally (29). This indicates that
although subcrestal placement of bone level implants should not be seen as a norm, it might be
essential if directed by the need to create the desired prosthesis contour, cervical margin and
emergence profile.
ii) ISC and implant -abutment / prosthesis junctions
Attention needs to be paid to the risks presented by any “gaps” within the supra-crestal complex,
as the ones that might be created in the implant-abutment or implant-prosthesis junctions. Such
interfaces -if not tight enough- might facilitate microleakage and circulation of bacterial
products into the ISC, while micromobility of the components might also contribute to
problems. Furthermore, gaps within the ISC might act as retention points when infected with
biofilm, possibly inhibiting disinfection efforts through professional means and oral hygiene
and complicating the resolution of inflammation. Modern bone level implant systems with
internal connection, can achieve a very tight fit in the implant-abutment junction, which can be
at the level of 1-2 μm. In addition, in the case of bone level implants with platform switch, the
implant-abutment junction remains well apical of the junctional epithelium, thus potentially
protected by direct plaque contamination in the early stages of mucositis. Nevertheless, screw
loosening of the healing, temporary or prosthetic abutment at the bone level implant could
potentially be more detrimental to the bone margins and the tissue health than in the case of a
tissue level.
The implant-abutment junction of tissue level implants presents with a different configuration,
still however the fit of the components can be equally tight in the range of 1-2 μm (Figure 5).
Depending on the height of the smooth collar, this junction is in most cases exposed in the
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sulcus coronal of the junctional epithelium, or close to the sulcus opening, thus more easily
accessible through oral hygiene. Abutment loosening in this case might be less detrimental than
in the case of bone level. Nevertheless, if this interface is deep in the sulcus as in the case of
increased vertical dimension of the soft tissues or in subcrestal placement, this area could act
as a difiicult to disinfect retention point, if colonized with biofilm. It is therefore advisable to
avoid the placement of tissue level implants at sites with increased vertical soft tissue height,
which would result in placing the implant-abutment junction several millimetres under the
Cervical Margin. Subcrestal implant placement is well documented in the case of platform
switching Bone level implants, but should be avoided with Tissue level implants, as it would
result in the placement of the less precise implant-abutment-prosthesis junction (Figure 5) deep
under the supracrestal complex tissues.
Limitations
The authors accept that the use of these terms and the definition of the respective anatomical
and morphological structures correspond to a configuration during ideal conditions. For
example, in the case of subcrestal placement of a bone level implant, the Supra-crestal complex
will be established from below the implant crest, thus seemingly contradicting the term. The
term “Supra-platform implant Complex” was thus proposed to address such a configuration,
the authors however acknowledged that such a term will be confusing in the case of Tissue
Level implants, where the “platform” is already some millimeters coronal of the bone crest in
the Complex. Consequently, the authors have decided to describe the anatomic and
morphological landmarks of importance which will be present in most common Implant-
Abutment-Prostheses configurations, while acknowledging that some very specific implant
systems or configurations might not fall exactly within this terms. The terms have been thus
described for bone and tissue level two-piece implants which are being placed for axial loading.
Even within this category of implants, significant diversity of the design persists, for example
in the height and angle of the transmucosal collar of tissue level implants, or the presence and
extent of platform switching in bone level implants. The authors also acknowledge that there
exist a significant diversity of implant systems, connections and combinations, with potentially
different level of precision and fit of components. The samples that have been used for
discussion in this paper originate from specific published research in peer-reviewed journals
and is only addressing the conditions and results of these investigations. The use of different
material for the sub-mucosal components, such as titanium, gold alloys, ceramics and also the
use of non-original prosthetic components and screws might also impact the tissues and
configuration of the Supra-crestal complex.
Furthermore, the authors believe that as with any anatomic feature, the dimensions and
structure of the peri-implant tissue can present with significant, physiological variation
between individuals or different anatomic sites in the same person (20). Histological studies in
humans are scarce and typically based on very few samples. Even so, the means describing the
dimensions are accompanied by high standard deviations, suggestive of significant variation.
Acknowledgements
The authors would like to thank Professor Lisa Heitz-Mayfield for her critical review and
important feedback to the writing of this paper.
11
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15
Figure 1. Natural scalloping of the periodontal tissues corresponding to the interdental
papilla is a result of the corresponding bone anatomy and root morphology of the natural
teeth. Simulating this interproximal scalloping with implants, in particular in the aesthetic
zone is only possible through a deep peri-implant sulcus at the interproximal sites. The
Emergene Profile remains the transition from the bone crest to the cervical margin, regardless
if Bone or Tissue level implants are utilised. Interproximal view of the Connective Tissue
(CT) and Junctional Epithelium (JE) space, Emergence Profile (yellow line), the Cervical
Margin (red line) and interproximal sulcus depth (probe) for bone (left) and tissue level
(right) configurations of the Supracrestal Complex.
16
Figure 2. Tissues of the Emergence Profile in a typical Implant-Abutment-Prosthesis
complex in the aesthetic zone. Subcrestal placement of this bone level implant (in relation to
mesial and distal bone level on neighbouring teeth) has allowed for maintaining the desired
scalloping of the soft tissues, but resulted in increase of sulcus depth in the mesial and distal
area. Observe that implant position and the design of the Emergence Profile allows for the
Cervical Margin to coincide with the most coronal part of the sulcus, as in natural teeth.
17
Figure 3. Implant abutment junction under the Scanning Electron Microscope of Bone level
implants. a,b Astratech Morse Taper internal connection at 32x(a) and 120x(b). c,d Strauman
Bone Level Crossfit connection at 20x(c) and 55x(d) magnification. The tight fit at the
implant shoulder in both cases allows for a gap of less than 2 μm.
a.
b.
c.
d.
.
18
Figure 4: Straumann bone level implant restored with a,b) Straumann Cares abutment and
c,d) third party abutment at 20x(a, c), 40x(b) and 27x(c) magnification. Deficient fit of the
abutment in the coronal part of the internal connection is evident in c,d.
a.
b.
c.
d.
19
Figure 5. Implant abutment junction under the Scanning Electron Microscope of Tissue level
implants. a,b Strauman Tissue Level Synocta connection with Gold abutment at 30x (a) and
100x(b) magnification. c,d Strauman Tissue Level Synocta connection with third party
Titanium abutment at 13x (c) and 100x (d) magnification. Observe the tight fit between the
implant and abutment at the shoulder which in both cases allows for a gap of less than 2 μm,
but also the horizontal discrepancy which in both cases creates an “undercut” exceeding 50
μm .
a.
c
20
Figure 6. Common current types of implant-abutment-prosthesis configurations. Schematic
representation on Bone Level implants. a) Prosthesis cemented on an extra-orally cementable
abutment such as a Ti-base. b) Prosthesis cemented on an intraorally cementable abutment c)
Prosthesis retained by a screw on an intermediate abutment. d) Prosthesis directly to the
implant (without an intermediate abutment).
21
Figure 6a,b,c,d. Details of IAP interface of a) prosthesis cemented extra-orally on abutment,
b) Prosthesis cemented on an intraorally cementable abutment c) Prosthesis retained by a
screw on an intermediate abutment. d) Prosthesis directly to the implant (without an
intermediate abutment) for Bone Level implants. Red line: Peri-implant soft tissues and
emergence profile. Red line: Peri-implant soft tissues and emergence profile. Blue line:
Prosthesis-abutment junction. Yellow line: Implant-Abutment junction.
a)
22
b)
23
c)
24
d)
25
Figure 7. Common current types of implant-abutment-prosthesis configurations. Schematic
representation on Tissue Level implants. a) Prosthesis cemented on an extra-orally
cementable abutment such as a Ti-base. b) Prosthesis cemented on an intraorally cementable
abutment c) Prosthesis retained by a screw on an intermediate abutment. d) One piece
prosthesis cast on abutment.
26
Figure 7a,b,c,d. Details of IAP interface of a) prosthesis cemented extra-orally on abutment,
b) Prosthesis cemented on an intraorally cementable abutment c) Prosthesis retained by a
screw on an intermediate abutment. d) Prosthesis cast on the abutment for Tissue Level
implants. Red line: Peri-implant soft tissues and emergence profile. Red line: Peri-implant
soft tissues and emergence profile. Blue line: Prosthesis-abutment junction. Yellow line:
Implant-Abutment junction.
a)
27
b)
28
c)
29
d)
30
Figure 8. Slice of Prosthesis after extraoral cementation on a titanium abutment and polish. A
thin layer of cement is present in the interface between the prosthesis and the abutment, while
the undercut between implant and abutment is also visible. Magnification 40x at the Scanning
Electron Microscope.
31
(Figure 9). Placement of this Bone Level implant in a shallow and palatal position has
resulted in the need of a ridge lap in order to fulfil the aesthetic requirements of the
prosthesis. a) vertical height between implant shoulder and most apical part of the peri-
implant mucosa margin is only 1.5 mm b) Ridge lap of the cervical margin of the prosthesis,
inhibiting the access of plaque control to the opening of the sulcus buccally.
Red line on the crown indicates the Cervical Margin.
... Current research increasingly points towards significant impact of the implant supracrestal complex features towards long term health and stability of the peri-implant tissue ( Mattheos, Vergoullis, Janda, & Miseli, 2021) . Recent studies suggest that the emergence profile and angle, as well as the implant-abutment-prosthesis junctions in relation to the accessibility to perform oral hygiene, can have significant impacts on the long-term health of the peri-implant bone and soft tissue ( de Tapia et al. , 2019;Göthberg, Gröndahl, Omar, Thomsen, & Slotte, 2018;Katafuchi, Weinstein, Leroux, Chen, & Daubert, 2018;Serino & Hultin, 2019;Serino & Ström, 2009;Valente, Wu, Toti, Derchi, & Barone, 2020;Yi, Koo, Schwarz, Ben Amara, & Heo, 2020).The design of the implant prosthesis and its features in relation to the accessibility to perform oral hygiene have been studied very scarcely in the scientific literature (de Tapia et al., 2019), despite its well acknowledged significance for the health of the peri-implant tissue. ...
... Deeper PD on average was found around ISSC than the adjacent tooth, but this is not necessarily related to inflammation. The peri-implant sulcus can be deeper than the adjacent periodontal sulcus, due to anatomical factors and prosthesis design (Mattheos, Vergoullis, et al., 2021). The case definition of peri-implantitis used in this study is the recommended one for cross-sectional studies, it has been however shown in a recent study (Romandini, Berglundh, Derks, Sanz, & Berglundh, 2021) to present with high level of specificity but low sensitivity. ...
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Purpose: 1) To investigate tissue features and interproximal contour of posterior implant supported single crowns (ISSC), which correlate with food impaction. 2) To evaluate the influence of food impaction on the health of the adjacent peri-implant tissue and patients' oral health related quality of life (OHRQoL). Materials and methods: Patients with posterior ISSC under maintenance between July 2019 and July 2020 were recruited. OHRQoL of patients who self-reported food impaction between ISSC and teeth was evaluated by Oral Impacts on Daily Performance questionnaire and reported at patient level. Interproximal prosthesis contours and periodontal/peri-implant tissue conditions were assessed by clinical and radiographic examination. Differences between food impaction (FI) and non-food impaction (NFI) sites were analysed. Results: Totally 178 patients (286 ISSC and 410 interproximal spaces) were included. Among 119 patients who self-reported food impaction, 84 (70.6%) reported their OHRQoL to be affected with minor to severe intensity. The most common affected daily performance was the ability to clean the teeth. Plaque accumulation at ISSC, deeper probing depth, complete interdental papilla fill, loose contact, longer contact length, lower contact point level, closer distance between ISSC and tooth, lesser embrasure surface area, tissue level implant and cement-retained restoration were found significantly more in the FI group than the NFI group (P<0.05). Conclusion: Interproximal features of the implant prosthesis were associated with food impaction between the ISSC and the adjacent tooth, which might affect periodontal and/or peri-implant tissue health conditions. Patients' OHRQoL was commonly affected by food impaction, but the intensity was low.
... The term 'implant supracrestal complex' has been recently proposed in order to describe the anatomic complex of human tissue, mechanical components and bacteria extending through the transmucosal part of an implant prosthesis. The paradigm of the 'implant supracrestal complex' aims to describe the human tissue in parallel with the design features of the implant-abutment-prosthesis complex and assists in identifying the role of design elements in health and disease of the peri-implant tissue [21]. The review article by Mattheos et al. investigated seven focus questions regarding emergence profile, emergence angle and/or 'implant supracrestal complex' [21]: ...
... The paradigm of the 'implant supracrestal complex' aims to describe the human tissue in parallel with the design features of the implant-abutment-prosthesis complex and assists in identifying the role of design elements in health and disease of the peri-implant tissue [21]. The review article by Mattheos et al. investigated seven focus questions regarding emergence profile, emergence angle and/or 'implant supracrestal complex' [21]: ...
Chapter
This chapter will address evidence-based prosthetic concepts in dental implantology as well as clinical evidence with focus on appropriate logic and technical skills. Those prosthetic factors are as just important as surgical factors, and long-term success can only be achieved if both of those factors are considered, respected, and strictly followed from planning to prosthetic phase of treatment. This chapter will deal with materials selection for prosthetic part, shape, size, and design of supracrestal parts of abutments and their influence on soft tissue and bone stability around dental implants. Furthermore, one of most important decisions is about choosing the proper way of retention: screw- vs. cement-retained restorations, and it will be discussed in detail. Additionally, emergence profile and its function in soft tissues adaptation and adhesion to different prosthetic materials also have important role in long-term success of dental implant restorations.
... The microdesign describes the surface characterization of the implant. Design features of the implant-prosthesis-abutment complex, such as the cervical margin, emergence angle and emergence profile, as well as the design of the implant-abutment and abutment-prosthesis junctions and their locations in relation to the oral tissues, can significantly impact peri-implant tissues in the long term [3]. There is an ongoing discussion in literature whether the broad part of the implant, which is supposed to be covered by bone, should be designed in a more or less rough way in order to directly increase cell accumulation and therefore favor osseointegration [4]. ...
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Purpose The collar region of an implant is its connection to the oral cavity. A balance between osseointegration on one hand and the absence of plaque accumulation on the other hand is necessary for successful implantation. It is yet to be determined which implant collar design, polished or rough, is best to stabilize the crestal bone level, avoiding peri-implantitis and subsequent risk of implant loss. The aim of this study was to investigate the influence of the architecture of the collar region on marginal bone and soft tissue response. Methods This prospective, randomized, clinically controlled multicenter study included 58 patients undergoing dental implant treatment using a pair of dental implants with either machined or rough-surfaced shoulder regions. Patients were clinically and radiologically examined for bone level height and signs of inflammation after 6, 12 and 24 months. Results No implant was lost within the 2 years of follow-up (100% survival rate). No significant differences on crestal bone loss (machined neck: 0.61 mm ± 0.28 mm, rough neck 0.58 mm ± 0.24 mm) and on soft tissue response (probing depth 3–6 mm with bleeding on probing 7.6% in machined-neck implants and in 8.3% in rough neck implants) were observed between implants with machined and roughened neck after 2 years. Conclusions Machined and roughened neck implants achieved equally good results concerning peri-implant bone loss, the rate of peri-implantitis and implant survival rate/hard and soft tissue integration. None of the two collar designs showed a clear advantage in peri-implant reaction. Trial registration German Clinical Trials Register, DKRS00029033. Registered 09 May 2022—Retrospectively registered, http://www.dkrs.de
... The transmucosal implant placement makes it possible to start implant loading by means of a provi-sional prosthesis and tissue conditioning after 8 weeks, which is beneficial in improving the final esthetic result. 33,34 A potential limitation of this technique could be related to the surgical expertise required to perform tissue management and the layering of multiple materials. Furthermore, being a multilayer technique, it is also difficult to establish whether the same result can be obtained without using one or more layers. ...
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... The implant supracrestal complex (ISC) was recently defined as the anatomic and functional area extending from the marginal periimplant bone level to the most coronal extension of the peri-implant mucosa. Accordingly, it encompasses various components of the implant-abutment-prosthesis junction located in the transmucosal area (Mattheos et al. 2021b). ...
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Objective: To evaluate the influence of implant and prosthetic components on peri-implant tissue health. A further aim was to evaluate peri-implant soft-tissue changes following surgical peri-implantitis treatment. Materials and methods: Group discussions based on two systematic reviews (SR) and one critical review (CR) addressed (i) the influence of implant material and surface characteristics on the incidence and progression of peri-implantitis, (ii) implant and restorative design elements and the associated risk for peri-implant diseases, and (iii) peri-implant soft-tissue level changes and patient-reported outcomes following peri-implantitis treatment. Consensus statements, clinical recommendations, and implications for future research were discussed within the group and approved during plenary sessions. Results: Data from preclinical in vivo studies demonstrated significantly greater radiographic bone loss and increased area of inflammatory infiltrate at modified compared to non-modified surface implants. Limited clinical data did not show differences between modified and non-modified implant surfaces in incidence or progression of peri-implantitis (SR). There is some evidence that restricted accessibility for oral hygiene and an emergence angle of >30 combined with a convex emergence profile of the abutment/prosthesis are associated with an increased risk for peri-implantitis (CR). Reconstructive therapy for peri-implantitis resulted in significantly less soft-tissue recession, when compared with access flap. Implantoplasty or the adjunctive use of a barrier membrane had no influence on the extent of peri-implant mucosal recession following peri-implantitis treatment (SR). Conclusions: Prosthesis overcontouring and impaired access to oral hygiene procedures increases risk for peri-implantitis. When indicated, reconstructive peri-implantitis treatment may facilitate the maintenance of post-operative peri-implant soft-tissue levels.
... The stability and the anatomical characteristics of the so-called 'implant supracrestal complex (ISC)' are fundamental for maintaining oral hygiene and for limiting the possibility of occurring in peri-implant inflammatory diseases [50]. The EMD are adopted for increasing the stability and the health status of ISC in general, showing a substantial improvement in soft tissue healing but we have no information on the long-term clinical outcomes, since a number of factors could be more important in determining implant success over time. ...
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Enamel matrix derivative (EMD) has been successfully used for periodontal regeneration in intrabony defects. Recently, its use for peri-implant bone regeneration has also been hypothesized. The aim of this paper is to review preclinical and clinical studies investigating the use of EMD in correspondence with titanium implants, alone or as an adjunct to other biomaterials. Clinical trials and case series with more than five cases were included. Seven in vitro studies evaluated the effect of EMD, placed on titanium surfaces: An increase in proliferation and viability of osteoblasts was observed in all but two studies. An increase in TGF-β1 and osteocalcin production, alkaline phosphatase activity, and angiogenesis was also reported. Nine animal studies investigated the use of EMD at implant placement or for bone regeneration of peri-implant bone defects, and some of them reported a significant increase in bone formation or bone-to-implant contact. In four of eleven clinical trials on humans, EMD was successfully used at implant placement. The other seven evaluated the use of EMD in protocols for the treatment of peri-implantitis. In conclusion, the results of EMD seem promising, but further randomized clinical trials are needed to evaluate its efficacy.
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Objectives: The objective of this study was to analyze the impact of the abutment width on early marginal bone loss (MBL). Material and methods: A balanced, randomized, double-blind clinical trial with two parallel experimental arms was conducted without a control group. The arms were "cylindrical" abutment and "concave" abutment. Eighty hexagonal internal connection implants, each with a diameter of 4 × 10 mm, were placed in healed mature bone. The main variable was the peri-implant tissue stability, which was measured as MBL at 8 weeks and 6 months. Results: The final sample consisted of 77 implants that were placed in 25 patients. 38 (49.4%) were placed using the cylindrical abutment, and the other 39 (50.6%) were placed using the concave abutment. The early global MBL of -0.6 ± 0.7 mm in the cylindrical abutment group was significantly higher than it was in the concave abutment group, in which the early global MBL was -0.4 ± 0.6 mm (p = .030). The estimated effect size (ES) was negative for the cylindrical abutment (ES = -1.3730, CI -2.5919 to -0.1327; t-value = -2.4893; p = .0139), therefore implying a loss of mean bone level, and it was positive for the concave abutment (ES = 2.8231; CI: 1.4379 to 4.2083; t-value = 4.0957; p = .0002), therefore implying an increase in the average bone level. Conclusions: The concave abutments presented significantly less early MBL at 6 months post-loading than classical cylindrical abutments did.
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Objective: The aim of this review was to investigate the evidence correlating the emergence profile (EP) and emergence angle (EA), peri-implant tissue height, implant neck design, abutment and/or prosthesis material, retention and connection types with risk of peri-implant mucositis and peri-implantitis. Methods: Seven focus questions were identified, and seven electronic search queries were conducted in PubMed. Human studies reporting on bleeding on probing, probing depth or case definitions of peri-implant mucositis and peri-implantitis were included. Results: Emerging evidence with bone-level implants suggests a link between EA combined with convex EP and peri-implantitis. Depth of the peri-implant sulcus of ≥3 mm is shown to be reducing the effectiveness of treatment of established peri-implant mucositis. Modification of the prosthesis contour is shown to be an effective supplement of the anti-infective treatment of peri-implant mucositis. Limited evidence points to no difference with regard to the risk for peri-implant mucositis between tissue- and bone-level implants, as well as the material of the abutment or the prosthesis. Limited evidence suggests the use or not of prosthetic abutments in external connections and does not change the risk for peri-implantitis. Literature with regard to prosthesis retention type and risk for peri-implantitis is inconclusive. Conclusions: Limited evidence indicates the involvement of EA, EP, sulcus depth and restricted accessibility to oral hygiene in the manifestation and/or management of peri-implant mucositis/peri-implantitis. Conclusions are limited by the lack of consensus definitions and validated outcomes measures, as well as diverse methodological approaches. Purpose-designed studies are required to clarify current observations.
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This article proposes a definition for the term "peri-implant phenotype" and provides a comprehensive description of all its components.
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The aim of this consensus meeting was to assess the influence of implant neck and abutment characteristics on peri‐implant tissue health and stability. Group and plenary discussions were based on two systematic reviews focusing on the effect of titanium implants with different collar designs/ surface modifications and the abutment material on the stability of marginal bone levels (MBL's), peri‐implant health, and survival rates. The changes in MBL's were not influenced by the abutment material and were also similar at one‐ and two‐piece implants after one year of loading. Rough collar implants improved MBL's in comparison to machined collar implants. Additional modifications of the collar had no beneficial clinical effect on MBL′s. Titanium abutments were associated with significantly higher increases in bleeding on probing when compared with zirconia abutments. MBL's are mainly influenced by the microstructure (i.e. rough surfaced) of the implant neck. Consensus statements and specific recommendations for future research were elaborated during the consensus meeting. This article is protected by copyright. All rights reserved.
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Background Resolution and prevention of peri‐implant mucositis is key in preventing peri‐implantitis. This case‐control study aims to assess the modifying effect of a deep mucosal tunnel on the induction and resolution phases of experimental peri‐implant mucositis. Methods 19 subjects with a tissue level implant were assigned to cases (deep mucosal tunnel, depth >3mm, DMT) or controls (shallow mucosal tunnel < 1 mm, SMT). Subjects underwent a standard experimental peri‐implant mucositis protocol characterized by an oral hygiene optimization phase, a 3‐week induction phase using an acrylic stent to prevent self performed oral hygiene at the experimental implant, and a 3+2 weeks resolution phase. Modified plaque (mPI), gingival index (mGI) and peri‐implant sulcus fluid IL‐1β concentrations were measured over time. Differences between DMT and SMT were assessed with the Mann‐Whitney test. Results mPI and mGI increased in parallel during the induction phase. After resumption of oral hygiene practice, mPI and mGI resolved towards baseline values in the SMT group. In DMT, mPI and mGI values diverged: plaque resolved but resolution of inflammation was delayed and of smaller magnitude during the first 3 weeks after resumption of oral hygiene. IL‐1β concentrations were significantly higher in DMT at 21 days (end of induction) and during the resolution phase corroborating the clinical findings. Removal of the crown and sub‐mucosal professional cleaning were needed to revert mGI to baseline values in DMT implants. Conclusions The depth of the mucosal tunnel modifies the resolution of experimental peri‐implant mucositis at transmucosal implants. This observation raises important questions on the effectiveness of self‐performed oral hygiene in cases where implants are placed deeper and the ability to resolve mucositis and effectively prevent peri‐implantitis in such situations. This article is protected by copyright. All rights reserved.
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Despite many discoveries over the past 20 years regarding the etio-pathogenesis of periodontal and peri-implant diseases, as well as significant advances in our understanding of microbial biofilms, the incidence of these pathologies still continues to rise. This review presents a general overview of the main protagonists and phenomena involved in oral health and disease. A special emphasis on the role of certain keystone pathogens in periodontitis and peri-implantitis is underlined. Their capacity to bring a dysregulation of the homeostasis with their host and the microbial biofilm lifestyle are also discussed. Finally, the current treatment principles of periodontitis and peri-implantitis are presented and their limits exposed. This leads to realize that new strategies must be developed and studied to overcome the shortcomings of existing approaches.
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Purpose: To compare the sealing effectiveness of four different implant-abutment connections against Staphylococcus aureus (S. aureus). The null hypotheses stated that there was no difference on sealing ability among the implant-abutment connections tested. Methods: Five diverse commercially available dental implants were used to investigate the degree of microleakage at the implant-abutment junction (IAJ): Group 1: Torque Type conical implant with double conic connection - TTc (Winsix); Group 2: Torque Type conical implant with Cone Morse connection - TTcm (Winsix); Group 3: Free Lock connection - K type implant (Winsix); Group 4: Internal double hexagon - OsseoSpeed; Group 5: Internal hexagon - Aadva Implant. Nine implants were tested in each group and one group was used as the negative control (Group 4). The abutments were connected to implants according to manufacturers' recommendations. All procedures involving connection and disconnection of implants were performed in sterile conditions in a laminar flow biological safety cabinet. S. aureus ATCC 6538, a methicillin susceptible reference strain, was chosen for the experiments to test the degree of microleakage. Statistical analysis was performed in order to find significant differences among the five groups regarding sealing capability of the implant-abutment connections tested. The recorded data were statistically analyzed. Results: One implant from Group 4 was excluded from the study because of the growth of a contaminant after 48 hours of incubation in all three wells (i.e. Paenibacillus pabuli, environmental Gram-positive bacteria). Wells A and B (i.e. wells where the samples were passed before being located in the final well C) of all other samples (n = 46) remained sterile over the 72 hours of incubation, indicating the lack of external contamination during implant-abutment connection. Similarly, no bacterial growth was observed in the five negative controls (i.e. one implant for each type), which had been inoculated with sterile saline and processed as the others. Bacterial microleakage was demonstrated with three samples, including one sample of Group 1, one of Group 3 and one of Group 5, in which growth of S. aureus in wells C after 48 hours of incubation was demonstrated (Table 1). No statistically significant difference between groups was noticed (P> 0.05). Clinical significance: Within the limitations of the present in vitro model, the results obtained suggest a tendency toward a better sealing capability for conical connections and internal hexagon.
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Objective To evaluate how vertical mucosal tissue thickness affects crestal bone stability around triangular‐shaped bone‐level implants, restored with low profile titanium bases and monolithic lithium disilicate restorations. Material and methods Fifty‐five bone‐level implants of 4.3 mm diameter were evaluated in 55 patients (22 males and 34 females, mean age 48.3 ± 3.4 years) in prospective cohort study. According to vertical mucosal thickness, patients were assigned into three groups: 1 (thin, 2 mm or less), 2 (medium, 2.5 mm) and 3 (thick, 3 mm and more). Implants were placed in posterior mandible and maxilla in one‐stage approach and, after integration, were restored with single screw‐retained monolithic lithium disilicate crowns, using low gingival profile titanium bases. Radiographic examination was performed after implant placement and after 1‐year follow‐up. Crestal bone loss was registered mesially and distally, and mean value was calculated. One‐way ANOVA and Tukey's HSD tests were applied; significance was set to 0.05. Results Mean vertical tissue thickness in 1 group was 1.76 ± 0.26 mm, 2 group–2.5 mm and 3.91 ± 0.59 mm in group 3, with statistically significant difference between all groups (p < 0.001). After 1‐year follow‐up, implants in group 1 (thin) had 1.25 ± 0.8 mm bone loss. Implants in group 2 (medium) had 0.98 ± 0.06, while implants in group 3 (thick) lost 0.43 ± 0.37 mm of crestal bone. Tukey's HSD test showed that differences between 1/3 and 2/3 were statistically significant (p < 0.001 and p = 0.0014, respectively), while between 1 and 2 was not significant (p = 0.310). Conclusions Significantly less bone loss occurs around triangular‐shaped bone‐level implants in thick mucosal tissues (≥3 mm), compared to medium or thin tissue biotype. Crestal bone loss did not differ between medium and thin tissues.
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Purpose: To investigate whether the interposition of a sealing-connector was able to reduce the bacterial leakage in external hexagon implants. Methods: 20 implants with external hexagon connection were used. Ten Test implant-abutment assemblies were connected with the interposition of a sealing-connector molded in the exact shape of the two opposed surfaces. Ten Control implant-abutment assemblies were connected with no sealing-connector interposed. Two types of bacteria were introduced into the internal portion of the implant, before placing the connector. The study lasted 28 days. Results: All control specimens, seeded with P. aeruginosa (PA) and A. actynomycetemcomitans (AA), showed contamination of the culture medium, indicative of microbial leakage. In the Test specimens, three instances of contaminated specimens were found in the samples seeded with PA and two contaminated specimens in the ones seeded with AA, for a total of five contaminated samples out of 10. The use of the sealing-connector was able to prevent bacterial leakage in half of the samples (50%). The leakage in both groups occurred mainly in the last week of the experiment. Probably, a longer period, under the conditions of this experiment, is necessary for the migration of the bacteria, and, furthermore, an observation period of 7 or 14 days may not be enough to show microbial contamination. Clinical significance: Using an interface under in vitro non-loading experimental conditions, could sometimes (50%) prevent bacterial microleakage and thus possibly the risk of peri-implant site infection. Moreover, less bone resorption and the maintenance of soft tissues and esthetics might be achieved in those cases where bacterial leakage does not occur.
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Background The implant‐abutment connection (IAC) is known to be a key factor for the long‐term stability of peri‐implant tissue. Purpose The aim of the present in vitro study was to detect and measure the mechanical behavior of different IACs by X‐ray imaging. Materials and Methods A total of 20 different implant systems with various implant dimensions and IACs (13 conical‐, 6 flat‐, and 1 gable‐like IAC) have been tested using a chewing device simulating dynamic and static loading up to 200 N. Micromovements have been recorded with a high‐resolution, high‐speed X‐ray camera, and gap length and gap width between implant and abutment have been calculated. Furthermore, X‐ray video sequences have been recorded to investigate the sealing capacity of different IACs. Results Out of the 20 implant systems, eight implant systems with a conical IAC showed no measurable gaps under static and dynamic loading (200 N). By contrast, all investigated implant systems with a flat IAC showed measurable gaps under dynamic and static loading. X‐ray video sequences revealed that a representative conical IAC had sufficient sealing capacity. Conclusion Within the limits of the present in vitro study, X‐ray imaging showed reduced formation of microgaps and consecutive micromovements in implants with conical IAC compared to flat IACs.
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Statement of problem: Evidence for micromorphology and precision of fit of third-party prosthetic components compared with the original manufacturer's components is lacking. Purpose: The purpose of this in vitro pilot study was to evaluate the micromorphological differences among different commercial brands of zirconia, titanium, and gold abutments for dental implants in terms of tight surface contact. Material and methods: The following abutments (n=3 per type) were preloaded on Straumann Bone Level implants according to the manufacturer's instructions for zirconia (Zr, Zr2, Zr3), titanium (Ti and Ti2), and gold (Gold 1, Gold 2). The micromorphology of the implant-abutment units was investigated by using scanning electron microscopy (original magnification ×10 to ×500) after microtome sectioning. After we calibrated, the length of the areas with tight contact (TC) (discrepancy ≤3 μm) was calculated at the level of conical connection (CC), lower internal connection (LIC), and screw threads (STs). The interexaminer agreement was assessed by using intraclass correlation coefficient(s) (ICC). One-way ANOVA was used for the overall comparison of the Zr groups, and the Student paired t test was used for pairwise comparisons of the abutments of the same group. After we adjusted for multiple comparisons, the significance level for the overall and pairwise comparisons of Ti and Gold groups was set at a P value of .008 and a P value of .003 for the Zr groups. Results: Major differences were found among the different abutment types in terms of design and extent of surface contact. The TC showed significant differences among the abutments of Zr group, depending on the side and level of evaluation (Zr1 > Zr2 > Zr3 on the left side for CC; Zr1, Zr2 > Zr3 on the right side for CC, and, Zr2 > Zr3 on the right side for LIC; P<.003). In Ti group, no significant differences were found (P>.008). The Gold and Gold 2 groups had significantly greater contact on the left side of CC (P<.008). Conclusions: A difference in design of the abutments was apparent. The tight surface contact was significantly different among the examined abutments or abutment screws and the respective area of the inner surface of the implants.
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A classification scheme for periodontal and peri‐implant diseases and conditions is necessary for clinicians to properly diagnose and treat patients as well as for scientists to investigate etiology, pathogenesis, natural history, and treatment of the diseases and conditions. This paper summarizes the proceedings of the World Workshop on the Classification of Periodontal and Peri‐implant Diseases and Conditions. The workshop was co‐sponsored by the American Academy of Periodontology (AAP) and the European Federation of Periodontology (EFP) and included expert participants from all over the world. Planning for the conference, which was held in Chicago on November 9 to 11, 2017, began in early 2015. An organizing committee from the AAP and EFP commissioned 19 review papers and four consensus reports covering relevant areas in periodontology and implant dentistry. The authors were charged with updating the 1999 classification of periodontal diseases and conditions1 and developing a similar scheme for peri‐implant diseases and conditions. Reviewers and workgroups were also asked to establish pertinent case definitions and to provide diagnostic criteria to aid clinicians in the use of the new classification. All findings and recommendations of the workshop were agreed to by consensus. This introductory paper presents an overview for the new classification of periodontal and peri‐implant diseases and conditions, along with a condensed scheme for each of four workgroup sections, but readers are directed to the pertinent consensus reports and review papers for a thorough discussion of the rationale, criteria, and interpretation of the proposed classification. Changes to the 1999 classification are highlighted and discussed. Although the intent of the workshop was to base classification on the strongest available scientific evidence, lower level evidence and expert opinion were inevitably used whenever sufficient research data were unavailable. The scope of this workshop was to align and update the classification scheme to the current understanding of periodontal and peri‐implant diseases and conditions. This introductory overview presents the schematic tables for the new classification of periodontal and peri‐implant diseases and conditions and briefly highlights changes made to the 1999 classification.1 It cannot present the wealth of information included in the reviews, case definition papers, and consensus reports that has guided the development of the new classification, and reference to the consensus and case definition papers is necessary to provide a thorough understanding of its use for either case management or scientific investigation. Therefore, it is strongly recommended that the reader use this overview as an introduction to these subjects. Accessing this publication online will allow the reader to use the links in this overview and the tables to view the source papers (Table 1).