Attachments used with implant supported overdenture

Abstract

Conventional complete denture is the traditional treatment plan for the completely
edentulous patient. Unfortunately, this treatment option has several complications,
especially for the lower denture. The advance of a dental implant with attachment
systems resolves many of these issues, particularly that related to the denture retention
and stability. A wide variety of commercially available attachment systems is used to
connect implants to overdentures. Most commonly used attachments include stud, bar,
magmatic, and telescopic attachments. Each of these types has owned its advantages,
disadvantages, and special requirements effi ciently to be used. The selection of
attachment system depend on, amount of retention needed, available inter arch space,
manual dexterities of the patient, skills of the dentist and fi nally the cost. In this article,
authors reviewed the literature concerning the types, designs, and requirements of
attachments systems.

Full text

International Dental & Medical Journal of Advanced Research ● Vol. 2 ● 2016 1
International Dental & Medical Journal of Advanced Research (2016), 2, 1–5
REVIEW ARTICLE
Attachments used with implant supported overdenture
Ahmed Yaseen Alqutaibi1,2, Amal Fatthy Kaddah1
1Department of Prosthodontics, Faculty of Oral and Dental Medicine, Cairo University, Cairo, Egypt, 2Department Prosthodontics, Faculty of Oral and Dental
Medicine, IBB University, IBB, Yemen
Abstract
Conventional complete denture is the traditional treatment plan for the completely
edentulous patient. Unfortunately, this treatment option has several complications,
especially for the lower denture. The advance of a dental implant with attachment
systems resolves many of these issues, particularly that related to the denture retention
and stability. A wide variety of commercially available attachment systems is used to
connect implants to overdentures. Most commonly used attachments include stud, bar,
magmatic, and telescopic attachments. Each of these types has owned its advantages,
disadvantages, and special requirements effi ciently to be used. The selection of
attachment system depend on, amount of retention needed, available inter arch space,
manual dexterities of the patient, skills of the dentist and fi nally the cost. In this article,
authors reviewed the literature concerning the types, designs, and requirements of
attachments systems.
Keywords
Attachment system, dental implant,
overdenture
Correspondence
Ahmed Yaseen Alqutaibi, Department of
Prosthodontics, Faculty of Oral and Dental
Medicine, Cairo University, Cairo, Egypt.
Email:Am01012002@gmail.com
Received 12December 2015;
Accepted 11August 2016
doi: 10.15713/ins.idmjar.45
Introduction
Edentulism is considered a poor health outcome and may
compromise the quality of life. The prosthetic management
of the edentulous patient has long been a major challenge for
dentistry.
The classical treatment plan for the edentulous patient is
the conventional complete denture. However, this treatment
has several complications that occur more frequently on
the lower denture; this led the researchers to focus more on
the mandibular jaw. Therefore, the problem of stability and
retention of a complete denture is partially solved with the use
of an implant retained denture, commonly known as an implant
overdenture.
A wide variety of commercially available attachment systems
are used to connect implants to overdentures either by splinting
or unsplinting the implants, most commonly used include stud,
bar, magmatic, and telescopic attachments.
Review of Literature
An attachment is defi ned as “a mechanical device for the fi xation,
retention, and stabilization of a prosthesis, a retainer consisting
of a metal receptacle and a closely fi tting part; the former (the
female matrix component) is usually contained within the
normal or expanded contours of the crown of the abutment
tooth and the latter (the male patrix component), is attached to
a pontic or the denture framework.”[1]
Attachments used in conjunction with implants were
found to enhance the retention, the stability and support of
overdentures together with the implants, thus extending their
longevity.[2]
A wide variety of commercially available attachment systems
is used to connect implants to overdentures either by splinting
or unsplinting the implants. The anatomic situation of the
mandible, desired level of retention, hygiene maintenance
capability, parallelism of the implants, and cost considerations
are important factors in choosing the appropriate overdenture
attachment type.[3-5]
The selection of the attaching mechanism for an implant
retained overdenture depend on: Cost eff ectiveness, amount
of retention needed, expected level of oral hygiene, amount of
available bone, patient’s social status, patient’s expectation,
maxillomandibular relationship, inter implant distance, and
status of the antagonistic jaw.[6]
According to retentive means the attachments can be
classi ed into
Frictional, mechanical, frictional and mechanical, and magnetic
attachments.[7]
The retentive force of the locator, ball, and magnetic
attachments is gained through mechanical interlocking,

Implant overdentures attachments Alqutaibi and Kaddah
2 International Dental & Medical Journal of Advanced Research ● Vol. 2 ● 2016
frictional contact, or magnetic forces of attraction between the
patrices and matrices.[8]
Attachments used to connect the denture and implants are
fabricated either by machine milling an alloy or custom casted
from plastic patterns. Machine milled attachments are commonly
used on the individual implant while custom cast attachments in
the bar design are popular. Both designs have shown satisfactory
results in terms of implant success and patient satisfaction.[9,10]
The attachments used to retain implant overdenture include
stud, bar, magnets, and telescopic attachments.
Stud attachment
Stud attachments consisted of a female part which is frictionally
retained over the male stud and incorporated into the denture
resin either by the means of a transfer coping system and the
creation of a master cast incorporating a replica of the attachment
or directly in the mouth using self-cured or light-polymerized
resin.[11]
The stud attachments are classifi ed according to function into
resilient and non-resilient attachments. Resilient attachments
permit some tissue ward vertical and rotational movements,
thus protecting the underlying abutments or implants against
overload. However, resilient attachments usually require a large
space and might cause posterior mandibular resorption with the
vertical movement of the denture. On the other hand, the non-
resilient type does not permit any movement of the overdenture
during function and were commonly employed when the
interocclusal space was limited.[12]
One of the main advantages of stud attachments is the
ability of its use in cases with V-shaped arches where the
straight connection between the implants can aff ect the tongue
space.[13,14]
Stud attachments include
O-rings attachment
It is consists of a titanium male unit and an easily replaceable
rubber ring female unit that is retained in a metal retainer ring. It
transfers the amount of stress to the abutments and provides an
excellent shock resorbing eff ect during the function.[15]
Evaluated the retention force of an O-ring attachment
system in diff erent inclinations to the ideal path of insertion and
concluded that when the O-rings attachments were properly
placed parallel each other, the retention was adequate for a
longer time and the retentive capacity of O-ring was aff ected by
implant inclinations.[16]
ERA attachment
It is an extra-radicular attachment with two design systems.
The fi rst is a partial denture attachment for placement on the
proximal (mesial/distal) aspects of artifi cial crowns while
the second is an axial (or overdenture) attachment, either
for placement inside the prepared roots or the ERA implant
abutment for the overdenture prosthesis. The abutments are
available in two types, fi rst is the straight one-piece abutment
type and second are the two pieces angulated abutment type (5°,
11°, and 17 angles). Each ERA retentive system is available in
four color codes, (white, orange and blue, and gray) that provide
diff erent degrees of retention from light to heavy. It’s indicated
when resiliency is required as it provides vertical resiliency and
universal stress relief.[17]
Ball attachments
The ball and socket attachments consist of a metal ball (male
portion) which is screwed into the fi xture, where the female part
is incorporated in the fi tting surface of the denture. The female
part may be one of the following types:
a. The O-ring in which the retentive element is rubber ring. It’s
better to have parallel implants. Otherwise, the rubber ring
will wear within a few weeks
b. A metal part as in dalbo system. This permits less resilience;
however, the retentive forces are almost twice those obtained
with the O-ring system
c. A spherical metal anchor in which the female part contains
a spring. These attachments have the advantage of being
resilient and easily activated.[18]
Ball attachments are among the simplest of all stud
attachments widely used because of their low-cost, ease of
handling, minimal chair side time requirements and their
possible applications with both root and implant supported
prostheses.[19]
Many authors agree that for unsplinted implants, the
most common attachment used is the ball attachment. This
attachment system is a practical, eff ective, and relatively low-cost
prosthetic concept.[15,20,21]
Solitary balls were claimed to be less costly, less technique
sensitive, and easier to clean than bars. Moreover, the potential
for mucosal hyperplasia was more reduced with solitary ball
attachments. However, bars were shown to be more retentive.[22-24]
Naert et al.[25] concluded that the ball attachments are the best
regarding soft tissue complications, and patient satisfaction when
compared to the bar attachment and the magnet attachment.
One of the studies done that compared load transfer and
denture stability in mandibular implant retained overdenture
retained by the ball, magnet, or bar attachments, suggested
that the use of ball attachment was advantageous in regards to
optimizing stress and minimizing denture movement.[26]
Another study was done to compare the retention of bar/
clip, ball, and magnet attachment in mandibular implant
retained overdenture. The ball and socket attachment recorded
the highest value followed by the bar/clip then the magnet
attachment.[27]
In comparison, done between overdentures retained by ball
and socket attachment and another design retained by two clips
on a bar connecting the two implants, regarding stresses on the
peri-implant bone. The result revealed that stress on the peri-
implant bone was greater with the clip/bar than that of ball
attachment.[28]
After 3-year of the prospective study for implant supported
mandibular overdentures either retained with the ball, bar,

Alqutaibi and Kaddah Implant overdentures attachments
International Dental & Medical Journal of Advanced Research ● Vol. 2 ● 2016 3
or telescopic attachments, the authors found that implant
success and peri-implant condition did not diff er between both
attachments, but the ball attachment showed signifi cantly higher
frequency of technical complications than that of telescopic and
bar attachment in implant supported overdentures.[20]
Locator (self-aligning) attachment
The locator attachment system is an attachment system with
self-aligning feature and has dual retention (inner and outer).
Locator attachments come in diff erent colors (white, pink, and
blue), and each has diff erent retentive value. Additional features
are the extended range attachments, which can be used to correct
implant angulation up to 20 they are off ered in green, which has
standard retention, and red, which has extra-light retention.[29]
The reduced height of this attachment is advantageous for
cases with limited interocclusal space or when retrofi tting an
existing old denture.[30]
A laboratory study investigated the properties of this
attachment founded that short profi le distance of locator may
aff ect the load transfer to the implant. The rounded edges of the
abutment help to guide the nylon male within the denture into
place (self-aligning feature).[31]
Locator attachment will also accommodate divergent
implants up to 20°. A variety of abutment heights, angulations
correction, and diff erent levels of retention are available that help
to create the optimum overdenture restoration for each case.[32]
In a study evaluating the clinical performance as well as
patient and clinician satisfaction on two diff erent prosthodontic
retention systems (locator and bar) for implant overdentures in
the mandible, the authors emphasized that patient satisfaction
was similar in both groups; the locator system demonstrated
better soft tissues scores; however, the frequency of chronic
infl ammations around the implants was more around bars
attachment group.[33]
Magnet attachments
Magnetic retention is a popular method of attaching the
removable prosthesis to either retained roots or osseointegrated
implants. The magnet is usually cylindrical or dome-shaped
attached to the fi tting surface of the acrylic resin base of the
overdenture. The magnetic keeper casted to a metal coping
cemented to root surface or screwed over the implant fi xture.[34]
The magnet system used for overdenture retention
incorporates the magnet into the overdenture which is a
neodymium-iron-boron alloy or a cobalt-samarium alloy. The
second part of the magnetic system is the ferromagnetic keeper
which is screwed into the implants.[35]
The retention force of magnet attachments in implant
retained mandibular overdenture treatment is markedly less
than the retention force of ball and bar/clip attachments.[27]
The immediate loading of magnet attachment retained
mandibular implant overdentures is considered as a viable
treatment option in cases of the complete edentulous patient
that increase retention and stability of conventional dentures.[36]
Bar attachments
The bar attachment consists of a metallic bar that splints two or
more implants or natural teeth spanning the edentulous ridge
between them and a sleeve (suprastructure) incorporated in
the overdenture which clips over the original bar to retain the
denture. The bar attachments are available in wide variety of
forms, they could be prefabricated or custom made.[37]
There are two basic types based on the shape and the action
performed:
Bar joint that permit some degree of rotation or resilient
movement between the two components. Spacers should be
provided to ensure a small gap between the sleeve and the bar
during processing. Bar joints are subdivided into two types:
Single sleeve and multiple sleeves; the single sleeve has to run
straight without allowing the anteroposterior curvature of
the arch, so it is used in square arches. On the other hand, the
multiple sleeves can follow the curvature of the arch. It also
enables the use of more than one clip.
Bar units that provide rigid fi xation of the overdenture
allowing no movement between the sleeve and the bar.[34]
The prefabricated bars are preferred to milled bars as they
are less expensive and more solid with an equal cross section.
Prefabricated bars are either round, ovoid, or rectangular
(U-shaped). Round bars off er more denture rotation than
rectangular bars, so produce less torque on implants. However,
Round bars require more frequent clip activation than U-shaped
bars. Therefore, oval or U-shaped bar are preferred when using
two implants.[38]
The bar and clip attachments are probably the most widely
used attachments for implant tissue supported overdentures as
they off er greater mechanical stability and more wear resistance
than solitary attachments. In addition, short distal extensions
from rigid bars can be achieved which contribute to the
stabilization and prevent shifting of the denture.[11,39,40]
The assumed advantage of bar attachment is the better
transmission of forces between the implants due to the primary
splinting eff ect, load sharing, better retention, and the least post
insertion maintenance.[18,27]
Telescopic attachment
Telescopic crowns are also known as a double crown, crown,
and sleeve coping. These crowns consist of an inner or primary
telescopic coping, permanently cemented to an abutment, and
a congruent detachable outer or secondary telescopic crown,
rigidly connected to a detachable prosthesis.[41]
The use of telescopic retainers has been expanded to include
implant retained prostheses to make use of their enormous
advantages. These retainers provide excellent retention resulting
from frictional fi t between the crown and the sleeve. They also
provide better force distribution due to the circumferential
relation of the outer crown to the abutment which make the axial
transfer of occlusal load that produce a less rotational torque on
the abutment by improving the crown root ratio so preserving
the tooth and alveolar bone.[42]

Implant overdentures attachments Alqutaibi and Kaddah
4 International Dental & Medical Journal of Advanced Research ● Vol. 2 ● 2016
According to wall design telescopic retainers can be classifi ed
into parallel sided crowns, tapered (conical-shaped) crowns, and
crowns with additional attachments.[43]
Telescopic retained restoration has the advantage of the
ease of removability. This encourages the patient for repeated
cleaning and maintenance purposes. Moreover, the overdentures
self-fi nding mechanism in telescopic constructions facilitated
prosthesis insertion considerably. This construction seemed
to be an eff ective treatment modality for geriatric patients with
serious systemic diseases as in Parkinson’s diseases.[44]
Conclusions
• The attachment retained implant supported overdenture
solves the problems inherited with conventional denture
• The selection of attachment system depend on, amount
of retention needed, available inter arch space, manual
dexterities of the patient, skills of the dentist and fi nally the
cost.
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How to cite this article: Alqutaibi AY, Kaddah AF. Attachments
used with implant supported overdenture. Int Dent Med J Adv
Res 2016;2:1-5.