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Journal of Dental and Allied Sciences ¦ Jan-Jun 2014 ¦ Volume 3 ¦ Issue 1 1
Case Report
Introduction
Dental implants are prosthetic devices, made of alloplastic
materials that are inserted into the oral cavity to provide
retention and support to removable and fixed dental
prostheses.[1,2]
The concept of using implants to replace teeth
is age old. In fact, in ancient history thousands of years ago,
ivory teeth were used as implants in Egyptian mummies.
However, the era of modern dental implantology began
much later, in the 1940’s, with the discovery of screw type
implants by Formiggini et al.[3,4]
The introduction of the
concept and the biology of osseointegration, by Brånemark
et al., added another milestone in the history of dental
implantology.[5]
Over the years, this field has significantly
evolved and emerged as an extensively used treatment
modality for oral rehabilitation.
The first clinical outcome of surgical procedure is the primary
stability of the implant. Primary stability is rigid fixation and
lack of micro motion of the implant into the bone cavity.[1,6,7]
The absence of stability can lead to excessive mobility and
cause fibrous tissue formation around the implants inhibiting
osseointegration.[7,9]
Primary stability depends on the surgical
technique, implant design, and the implant site.[9,10]
Bone tissue is arranged in two macro architectural forms,
trabecular or cancellous and cortical or compact. Leckholm
and Zarb (1985) have classified bone types in the oral cavity,
depending on the relative proportions of cancellous and
cortical bone:
• Class I: Predominantly cortical.
• Class II: Thick layer of compact bone surrounding a dense
cancellous core.
• Class III: Thin layer of compact bone surrounding a
cancellous core.
• Class IV: Very thin compact layer around a low-density
trabecular bone.
Sennerby et al. compared implants placed in rabbit cortical
versus cancellous bone and established that cortical bone has a
higher modulus of elasticity, is harder to deform and provides
greater resistance to the motion.[11]
Hence, Class I and Class II
bone would facilitate higher primary stability.
The original protocol for loading, as described by Brånemark
et al., involved waiting for 3 months (for mandible) to 6 months
(for maxilla) after implant placement. Such a delayed loading
protocol was aimed at allowing undisturbed healing and
complete osseointegration before implants could be loaded.
For a long time, it was assumed that premature loading would
limit peri-implant osteogenesis and induce fibrous tissue
formation.[7,12]
Schnitman et al. introduced the concept of immediate loading,
which has been described as attachment of the prostheses
within 24 h to 1-week after implant placement.[13,14]
Some of
the advantages of immediate loading are shortened treatment
time and early functional, physiological and psychological
rehabilitation of the patient. In addition, there have been some
claims made about a biologic advantage in the form of enhanced
The Mandibular Two-Implant Overdenture
Abu-Hussein Muhammad, Azzaldeen Abdulgani1
, Musa Bajali2
, Chlorokostas Giogrges3
Visiting Professor, Napoli University, Italy and University of Athens, Greece, 1
Departments of Conservative Dentistry, 2
Periodontology, AlQuds University,
Jerusalem, Palestine, 3
Implantogist, Private Dentistry, Athens, Greece
Successful treatment with the two-implant overdenture has been documented with multiple implant designs (e.g., hexagonal, Morse taper, internal
connection) and many implant systems. Clinicians may select implants for retention of the two-implant overdenture according to personal
experience and preference with confidence that treatment success will not be determined by the selection made. This is due primarily to the
anatomy and density of the bone in the anterior mandible. The aim of this case report is to demonstrate the concept of immediate functional
loading in the mandible using unsplinted implants to support a locator attachment supported overdenture.
Key words: Freestanding implants, immediate loading, locator, mandibular overdenture
Abstract
Address for correspondence: Dr. Abu-Hussein Muhammad,
123 Argus Street,
10441 Athens, Greece
E-mail: abuhusseinmuhamad@gmail.com
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Abdulgani, et al.: The Mandibular Two-Implant Overdenture
Journal of Dental and Allied Sciences ¦ Jan-Jun 2014 ¦ Volume 3 ¦ Issue 12
osteoblastogenesis with immediate loading. An in-vivo study
by Qi et al., evaluated the response of mesenchymal stem cells
to mechanical strain and their consequent gene expression
patterns.[15]
Their results suggested that the mechanical strain
might act as a stimulator to induce differentiation of stem
cells into osteoblasts.[15]
Indeed, cyclic tensile strain has been
shown to increase osteoprotegrin synthesis and decrease
soluble receptor activator of nuclear factor kappa-B ligand,
thus favoring bone formation.[16]
This theory was tested in an
rabbit model by Duyck et al., who concluded that mechanical
loading stimulated bone formation and led to a higher bone
fraction.[17,18]
Treatment of complete edentulism: Implant overdentures
An overdenture is defined as any dental prosthesis that covers
and rests on one or more remaining natural teeth, the roots
of natural teeth, and/or dental implants.[2]
The concept of
overdentures is age old. Ledger as early as 1856, suggested
utilizing natural teeth to stabilize removable prostheses and
after a whole century Miller introduced the concept of tooth
retained overdentures.[19]
The downside of these prostheses was
the frequent failure of abutments caused by periodontal disease,
periapical lesions, caries and fracture of teeth.[20]
The introduction of osseointegrated implants and implant-
retained prostheses led to a paradigm shift for the management
of edentulism.This is true especially for mandibular edentulism,
wheretheproblemofadvancedalveolarresorptionanddifficulty
in providing stable, retentive and functionally comfortable
prostheses seemed to represent a major challenge.[21]
A number of randomized controlled trials (RCTs) have
demonstrated increased patient satisfaction and reduced
negative impact on the quality of life with implant retained
overdentures as opposed to conventional dentures in the
mandible.[22]
Other studies have reported an improvement
in chewing ability, bite force and in serum nutritional and
anthropometric parameters (such as skinfold thickness, waist
hip ratio and body mass index).[23,24]
The long-term efficacy of
implant-supported overdentures has been established in many
retrospective and longitudinal trials.[25-27]
Implant overdentures are used in conjunction with attachments,
and there are many different attachments provided by a large
number of manufacturers around the world. The attachments
currently available can be broadly divided into two major
categories:
• Splinted/bar attachments — Dolder bar and hader bar are
examples of splinted attachments
• Nonsplinted/solitary/stud attachments — Ball attachments,
magnets and locators exemplify solitary attachments.
Loading of implant overdentures
A fairly recent systematic review by Gallucci et al. (2009)
presented the strength of evidence available for different
loading protocols (conventional, early and immediate
loading) in completely edentulous patients. Their search
led to a conclusion that the highest level of scientific and
clinical validation was available for conventional loading
with mandibular overdentures. However, immediate loading
of mandibular dentures was clinically well documented but
not scientifically validated.[28]
Clinical documentation of
immediate loading can be exemplified by various prospective
trials that have been conducted using this protocol for
mandibular dentures. For example, a longitudinal study
with 3-8 years of follow-up by Chiapasco and Gatti looked
at success and survival of immediately loaded implants
supporting a mandibular overdenture. Four implants were
placed per patient, connected by a splinted bar attachment. A
cumulative success rate of 88.2% and survival rate of 96.1%
was seen after a mean follow-up period of 62 months.
The authors concluded that, for about 3 years after immediately
loading the implants, the success and survival were the same
as that documented for delayed loading. However, with a
longer follow-up it became evident that immediately loaded
implants had a moderate decrease in success rate.[29]
Similar
results were reported by Kronstrom et al., wherein he advised
caution in using immediate loading due to a low survival rate
of 81.8% at 1-year follow-up.[30]
Other investigators have,
however, reported higher rates of success and survival using
an immediate loading protocol. A cohort study by Gatti and
Chiapasco has shown a cumulative survival rate of 100% and
minimal bone level changes (0.5-0.9 mm) around immediately
loaded implants.[31]
Alfadda et al. used historical controls with
delayed loading in a prospective cohort study and compared it
to immediate loading.At 5 years, they found identical success,
survival, satisfaction and impact on the quality of life between
the two groups.[32]
Randomized clinical controlled trials are considered as the
most reliable (level I) form of validation in the hierarchy of
scientific evidence, essentially because they reduce spurious
causality and bias. In order to prove the efficacy and safety of
an immediate loading protocol, Chiapasco et al. performed
a RCT comparing an immediate and a delayed protocol for
four splinted implants supporting a mandibular overdenture.
They found no difference in cumulative survival rate, bone
loss, clinical and radiographic parameters at 2 years between
the two groups.[33]
Review paper by Gallucci et al. (2009) and 10 years clinical
trial by Meijer et al., among many others, have shown that there
is no difference in the clinical and radiographic performance of
two or four implants supporting a mandibular overdenture.[27,28]
Hence, having established that immediately loaded four
implants supporting a mandibular overdentures are comparable
to delayed loaded implants, it would be interesting to see if
these results can be replicated when two-implants were used
in conjunction with unsplinted attachments such as locators.
Case Report
A 58-year-old female patient without any medical
contraindication for implant therapy presented with an ill-
fitting, lower complete denture that she had been wearing for

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Abdulgani, et al.: The Mandibular Two-Implant Overdenture
Journal of Dental and Allied Sciences ¦ Jan-Jun 2014 ¦ Volume 3 ¦ Issue 1 3
4 years. The clinical and radiographic findings revealed slight
to moderate mandibular ridge resorption with an ill-fitting
lower denture [Figures 1 and 2]. The patient was given the
option of placing two-implants to support her existing lower
denture. The treatment plan was accepted and included an
immediate functional loading using a locator attachment-
supported mandibular overdenture.
At the surgical appointment, following the administration of
local anesthetic, a mid-crestal incision was performed, and
a full-thickness flap was reflected. In addition, osteotomies
were prepared in type II bone. Bone taps were used to
countersink the sites, after which two ITI tapered implants
(ITI 3.3 mm × 14-mm) were placed with the hand piece and
hand ratchet. The implants were torqued to 35 N [Figures 3
and 4]. Immediately after implant surgery, the mandibular
denture was seated in the patient’s mouth and adjusted to
provide clearance in the area of the locator(s). Two locators
(4 mm in length) were torqued to 30 N [Figures 5 and 6].
Following the suture of the flap with 4-0 vicryl, the processing
rings were placed over the locators and were picked up
directly in the mouth using hard self-curing acrylic [Rebase
II, Tokuyama; Figure 8]. The patient was given postoperative
AQ1
instructions, including the use of 0.12% chlorhexidine
gluconate 3 times a day.
She was furthermore prescribed 500 mg of amoxicillin
(to be taken every 6 h for 7 days). The patient was then
informed that the implant-supported overdenture was to
be left in place for 48 h. Two days later, she was seen for a
follow-up visit, and the healing process was uneventful. The
black processing rings were switched to blue rings 10 weeks
after the placement. After 6 months, the patient returned for
another follow-up visit and all two locators were torqued
to 30 N [Figures 5 and 6]. It was determined that all two-
implants had achieved full integration. Currently, the patient
is on a 6 months recall to ensure the proper maintenance of
the implants and the prosthesis [Figures 9 and 10]. The last
maintenance visit was 24 months postplacement and all
implants have maintained healthy soft tissue and a stable
bone level.
Conclusion
In conclusion, within the limits of this interim report,
immediate loading of two-implants supporting a locator
retained mandibular overdenture seems to be a suitable
treatment option. The marginal bone level changes around
immediately loaded implants are comparable to those seen
AQ2
Figure 1: Mandible at the time of implant placement with moderate bone
resorption Figure 2: Preoperative panoramic radiograph
Figure 3: Guiding pins at the time of implant placement Figure 4: Two tapered implants at placement

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Abdulgani, et al.: The Mandibular Two-Implant Overdenture
Journal of Dental and Allied Sciences ¦ Jan-Jun 2014 ¦ Volume 3 ¦ Issue 14
around implants loaded with a torque do not effect peri-implant
bone loss. Implant survival of immediately loaded implants
may be lower than those loaded with a delayed protocol, but
this needs to be confirmed in future investigations with a larger
sample size. Elayed protocol, at 6 months postsurgery. Implant
length and peak insertion.
References
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Figure 5: Occlusal view of the locators 2 weeks postimplant placement Figure 6: Buccal view of the locators 2 weeks postimplant placement
Figure 7: Panoramic radiograph immediately after locator implant
placement
AQ3
Figure 8: The processing rings were picked up directly in the mouth
Figure 9: Buccal view of the overdenture in place
Figure 10: Final smile

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Abdulgani, et al.: The Mandibular Two-Implant Overdenture
Journal of Dental and Allied Sciences ¦ Jan-Jun 2014 ¦ Volume 3 ¦ Issue 1 5
How to cite this article: We will update details while making issue
online***.
Source of Support: Nil. Conflict of Interest: None declared.
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