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4 • Prosthodontics
137
4. Features that contribute to retention include:
n
peripheral (border) seal
n
area of impression surface
n
accuracy of fit
n
adhesion between the saliva, denture and oral
mucosa
n
cohesion within saliva film
n
orientation of the denture-bearing structures: the
shape of the palate, for example, will influence the
retention, a flatter palate providing better retention
but less stability
n
correct positioning of the denture base in relation to
displacing forces, namely soft tissue forces of the lips,
cheeks and tongue
n
anatomical features: for example, maxillary and
mandibular tori, frenal attachments, muscle attachments, genial tubercles, hard/soft palate junction,
maxillary tuberosity.
5. An Every denture conforms to a specific design to ensure
gingival health. It is restricted to use in the upper arch.
The denture design requires the presence of bounded
saddles. The design should incorporate the following
features: point contact between natural teeth and artificial teeth, wide embrasures, uncovered gingivae, distal
stabilisers and a ‘free occlusion’. The general principles
of partial denture design should be followed.
6. An acrylic or cobalt–chromium connector of a denture
can cover the gingival margins of teeth. If insufficient
support for the partial denture exists, then gingival
stripping can occur of the dentition under load. This can
be avoided by providing adequate tooth support for the
denture, using dental connectors that do not cover the
gingival margins of teeth and by the maintenance of
good oral hygiene.
7. Spoon dentures are simple acrylic dentures made to replace one or more anterior maxillary teeth. They derive
their support from the ridge and palate. They are used
commonly as they are cheap, easy to construct and
modify. However, such a denture is weak and non-rigid
and it is commonly unretentive and poses a possible airway risk.
8. Properties should include the following:
n
Strength. Should be strong enough in thin crosssection to withstand oral forces. Adding molybdenum in small amounts to cobalt–chromium alloy increases its strength; however, the addition of nickel
decreases its strength while increasing its ductility.
n
Ductility. In cobalt–chromium, the grains tend to be
large and, therefore, there are only two to three
grains across the thickness of a clasp. This reduces its
ductility and it is easily broken or distorted.
n
Malleability. A malleable material can be worked into
thinner sections; this property is of importance in
wrought clasps.
n
Proportional limit. The limit beyond which a clasp
will permanently deform or fracture.
n
Torsional elasticity. The rigid position of a clasp
arm should be above the survey line. The torsional
elasticity of the metal in the more rigid upright
part provides flexibility to the horizontal arm and
a more effective distribution of stress throughout
the structure.
n
Modulus of elasticity (resilience). The higher the
modulus, the shallower the undercuts that can be
engaged.
n
Appearance. A tooth-coloured clasp may be more aesthetically pleasing but may not provide other optimal
properties. Often gold alloys are more aesthetically
acceptable intraorally than ‘silver’-coloured alloys.
Three commonly used materials could be chosen
from cast cobalt–chromium, wrought stainless
steel, cast gold, wrought gold, tooth-coloured
resin clasps.
9. Denture stomatitis is a multifactorial condition. The
aetiological factors include poor denture hygiene,
trauma, Candida albicans infection, endocrine imbalance, iron deficiency anaemia, reduced salivary flow,
folate deficiency and diabetes mellitus. The clinical
picture is normally a diffuse erythematous area associated with denture support. Treatment includes the establishment and control of the relevant aetiological
factors.
10. Angular cheilitis is usually as a result of an infection
with C. albicans, Staphylococcus aureus and/or Strepto-
cocci. It is commonly related to denture stomatitis, but
other causes include iron deficiency, hypovitaminoses,
malabsorption conditions, HIV infection and other immune defects. Investigations can include blood pictures,
smears for fungal hyphae and bacteriological cultures.
The treatment should involve the resolution of any
systemic predisposing factors where possible and the
use of topical antifungals and antibacterial agents.
11. Denture hygiene should involve a regimen of brush,
soak, brush. The adherence of plaque to both acrylic
and cobalt–chromium requires that hygiene measures
are carried out at least twice daily. The initial brushing
will remove any food debris and then the use of a proprietary soaking solution will loosen and remove
stains, plaque and calculus deposits. The final brushing stage will remove any residual debris. It is essential
that a brush or cleanser that is not too abrasive is used
as otherwise this will scratch the acrylic and potentially provide a rougher surface for plaque attachment.
ESSAY ANSWER
This essay plan is to be seen as a template to the structure
of the essay. The content is not exhaustive but gives an example in each area of the content that could be included.
Introduction
All removable prostheses will by their nature attract or
retain more plaque in the mouth than if an appliance
were not present. However, various features of design can
influence this, as well as factors of patient motivation and
instruction on cleaning techniques and materials. The
maintenance of oral health is also not purely dependent
on oral hygiene but also relies on the design of the prosthesis, which should aim to preserve what remains and
prevent future disease.
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Master Dentistry
Important Features to Discuss
Saddles. Number of saddles and the need to replace all miss-
ing units to prevent overeruption or drifting has important implications.
Support. The choice between tooth support or mucosal sup-
port of the denture will influence the load distribution to
the oral structures and could, therefore, affect the health
of the oral tissues.
Retention. All forms of clasps will cause plaque retention;
therefore, the correct number and positioning of clasps is
essential to maintain oral health.
Bracing/reciprocation. The prevention of movement of a
denture base during function will aid in the protection of
the dental tissues.
Connector. If a connector is designed to cover as little gingi-
val margins as possible, this will minimise gingival damage and limit plaque and debris accumulation.
Indirect retention. The provision of indirect retention will
help to prevent rotational forces being applied to abutment teeth and will, therefore, be important in the maintenance of oral health.
References
Carlsson GE. Critical review of some dogmas in prosthodontics. J Prostho-
dont Res. 2009;53(1):3–10.
Crum RJ, Rooney GE Jr. Alveolar bone loss in overdentures: a 5-year study.
J Prosthet Dent. 1978;40(6):610–613.
Ettinger RL, Fang Q. Abutment tooth loss in patients with overdentures.
J Am Dent Assoc. 2004;135(6):739–46.
Feine JS, Carlsson GE, Awad MA, et al. The McGill consensus statement on
overdentures. Montreal, Quebec, Canada. Int J Prosthodont. 2002;
15:413–414.
Fenlon MR, Sherriff M. An investigation of factors influencing patients’
satisfaction with new complete dentures using structural equation
modelling. J Dent. 2008;36:427–34.
Felton D, Cooper L, Duqum I, et al. Evidence-based guidelines for the care
and maintenance of complete dentures: a publication of the American
College of Prosthodontists. J Am Dent Assoc. 2011;142:1S–20S.
Graham R, Mihaylov S, Jepson N, et al. Determining ‘need’ for a removable
partial denture: a qualitative study of factors that influence dentist provision and patient use. Br Dent J. 2006;200:155–158.
Kawai Y, Murakami H, Shariati B, et al. Do traditional techniques produce
better conventional complete dentures than simplified techniques?
J Dent. 2005;33:659–668.
Kennedy E. Partial Denture Construction. Brooklyn, NY: Dental Items of In-
terest Publishing Co; 1928.
Lynch CD, Allen PF. Why do dentists struggle with removable partial den-
ture design? An assessment of financial and educational issues. Br Dent
J. 2006;200:277–281.
Thomason JM, Feine J, Exley C. Mandibular two implant-supported over-
dentures as the first choice standard of care for edentulous patients –
the York Consensus Statement. Br Dent J. 2009;207:185–186.
5
Restorative Management of Dental Implants
CHAPTER OUTLINE
Overview, 139
5.1 Basic Implant Terminology and
Componentry, 139
5.2 Planning Implant Restorations, 140
5.3 Surgical Phases, 143
Overview
Assisting patients to attain a healthy, functional and
aesthetic dentition is one of the primary goals of any dental practitioner. Unfortunately, there are many reasons
why this goal might not be achieved, and there is then a
requirement for intervention to repair or replace what is
damaged or lost over time. Osseointegrated dental implants have been developed over the last fifty years and, in
addition to removable dentures, bridges and tooth transplants, provide a further option for replacing missing
teeth. This chapter provides an intentionally basic overview of implant dentistry.
After an introduction to basic terminology, the chapter is
organised to follow a patient’s pathway through presurgical
planning, implant placement, provisional and then definitive restoration, followed by the maintenance phase of
management. The use of dental implants for both fixed and
removable restorations is described.
In the United Kingdom, the knowledge and skills to
provide implant restorations is regarded as an area that requires clinicians to undertake additional training following
basic qualification as a dentist.
5.1 Basic Implant Terminology and Componentry
LEARNING OBJECTIVES
You should:
• be familiar with the basic elements that go to make up
typical implant-borne restorations
• understand the basic difference between primary
implant stability and osseointegration.
A basic understanding of implant treatment requires
knowledge of the component parts that go to make up implant-borne restorations. Implant dentistry is a rapidly
changing area of clinical practice with ever-evolving
products and techniques. It is not the intention here to provide a detailed review of implant dentistry of individual
implant brands, but rather to provide an understanding of
5.4 Provisional and Definitive Restoration
of Dental Implants, 144
5.5 Maintenance Phase, 145
Self-Assessment: Questions, 146
Self-Assessment: Answers, 146
the underlying principles of implant dentistry from a
generic perspective.
A basic implant-borne restoration may be considered as
comprising three distinct elements: one that interfaces
with the hard tissues; an element which interfaces with the
soft tissues and an element that interfaces with the oral
environment. These different structural elements may take
the form of either one, two or three separate components.
Fig. 5.1 shows the three separate components diagram-
matically and how they are associated with one another in
a typical single crown implant restoration. The component
that is osseointegrated with bone is usually referred to as
the implant itself. The implant in Fig. 5.1 would be expected
to have bone up to the region of the implant–abutment
interface. The abutment is the component that is connected to the implant by a holding screw known as the
abutment screw. It traverses the overlying soft tissue to
provide a connection between the implant in bone and the
overlying restoration: it is the transmucosal part. The final
component of the system is the restoration or superstructure that gains support and retention from the implant
through the abutment. Although this is a basic overview
of a generic implant system, it may be applied to many
products whether they comprise separate implant, abutment and restoration, or whether, for example, the implant
and abutment are one physical unit.
IMPLANTS
Osseointegrated implants are available in a vast array of
sizes, shapes, surface morphologies and implant–abutment
interface-linking configurations. In all cases, the primary
aim of the implant is to integrate rapidly and reliably with
the bone in order to provide long-term stability and retention for the overlying restoration. The tightness in bone
upon insertion of an implant is partly responsible for what
is referred to as primary stability. Good primary stability
assists in achieving osseointegration at the outset and is
influenced by implant thread design and whether, for example, an implant is tapered or parallel sided in overall
shape. Primary stability is also influenced by what is termed
bone quality (related to cortical and cancellous bone density) and the shape of the site in bone (the osteotomy)
139
140
Master Dentistry
Implant-supported
restoration
Single unit crown
cement retained
Implant abutment
with holding screw
in position
Implant
IMPLANT RESTORATIONS
Implant-supported restorations serve to replace the tissues
which have been lost, and it is convenient to consider these
as either replacing teeth or replacing a combination of
teeth and supporting tissues. A further way to classify
restorations is according to whether they are fixed, so that
they cannot be removed by the patient (e.g. cemented or
screw-retained implant crowns or bridges), or removable
restorations that are designed so that the patient can disengage them (e.g. partial or complete dentures that are
connected to abutments by means of retentive anchors of
various sorts: implant-assisted overdentures).
5.2 Planning Implant Restorations
LEARNING OBJECTIVES
You should:
• be familiar with the indications and contraindications
of using dental implants
• be aware of the stages involved in planning for dental
implant restorations.
Fig. 5.1 Diagram to show the basic elements of an implant restoration.
where the implant is to be inserted. The long-term function
of the implant is dependent upon establishment of biological osseointegration, or secondary stability. Many factors
influence the establishment of osseointegration, but fundamental to the process are the presence of a biocompatible
implant material (usually titanium dioxide which forms
naturally on the surface of titanium), a healthy infectionfree bony recipient site, avoidance of heat generation during osteotomy preparation and implant insertion and good
primary stability. Successful osseointegration results in
direct connection of living bone onto the surface of the
implant and is indicated by a completely non-mobile implant that gives a high-pitched/bright note when percussed.
Failure of an implant to osseointegrate or loss of secondary
stability is apparent when an implant is mobile, in which
case it may eventually exfoliate.
ABUTMENTS
An abutment links the implant to the restoration in the
mouth. It provides support and retention for the overlying
restoration through either a fixed physical link (e.g. a
permanently cemented or screw-retained single crown) or
a breakable physical link (e.g. a magnetically retained implant-assisted overdenture). Somewhere along the surface
of the abutment or at the coronal end of the implant, a
circumferential soft tissue (mucosal) seal is established
consisting of epithelial and connective tissue elements.
It is essential, as with any treatment planning, that the final
outcome is taken into account at the outset of the planning
process. Consideration of the final restoration and the
expectations of the patient must be taken into account at
the outset so that the treatment plan can achieve the most
desirable outcome.
INDICATIONS
Implants are primarily indicated when there is partial or
total loss of the dentition and/or the supporting tissues or
where there are teeth that are considered to have a hopeless
prognosis that will require replacement. Teeth may be missing due to developmental problems, or the loss of teeth and
supporting tissues may be a consequence of dental caries
and periodontitis, resorptive lesions, or due to trauma, advanced tooth-wear or treatment for jaw pathology, such as
neoplasia. Implants provide retention and support for a
dental restoration that may take the form of a single tooth,
groups of teeth or the entire dentition in one or both jaws.
As well as replacement of missing teeth, each type of prosthesis can also include missing periodontium and alveolar
tissue, or even facial appendages, such as the nose, orbit or
auricle. Implants destined for future use as foundations for
dental restorations can also be used in the interim as anchors for orthodontic treatment.
CONTRAINDICATIONS AND RELATIVE CONTRAINDICATIONS
There are few absolute contraindications for implant
treatment. The surgery to insert implants may be considered an elective oral surgical procedure, and therefore any
absolute or relative contraindications for surgery will also
be applicable to surgery involved in the insertion of dental
implants. In general terms, local or systemic conditions
5 • Restorative Management of Dental Implants
141
that impact upon wound healing would be expected to
have the same effect upon healing at the implant site and
may impact on the process of osseointegration and longterm success of implant treatment. As well as surgery,
patients need to be able to tolerate the prosthodontic and
maintenance stages of implant dentistry such as having
impressions. A sufficient mandibular opening range is required to allow safe and effective use of instruments such
as screwdrivers.
Absence of sufficient bone in which to place implants
may rule out implant restorations unless bone can be augmented by some means. Patients who have a history of
periodontal disease and associated risk factors such as
smoking and diabetes are likely to be at higher risk of complications, and the presence of these factors can be regarded as relative contraindications.
CASE SELECTION
The selection of patients for implant treatment begins
with thorough history and examination. It is important to
determine why the patient is seeking implant treatment
and to ascertain their understanding of what is involved,
as well as finding out their expectations of the likely outcome in terms of function and aesthetics. It should then
be possible to balance the patient’s expectations with
what is clinically achievable to ensure that both the
patient and the clinical team are likely to be satisfied with
the outcome.
A detailed discussion of the care pathway should be undertaken with the patient to ensure that they understand
the extent of the procedures, timescales, side effects, risks,
possible complications and long-term maintenance implications. For example, during the healing phase, it is sometimes necessary to ask the patient not to wear an interim
prosthesis for a short period to aid healing. This may not be
acceptable to some patients.
For fee-paying patients, the cost of delivering implant
treatment (and long-term maintenance) must be clearly
laid out in writing along with payment schedules and terms
and conditions.
PROSTHODONTICALLY DRIVEN (OR REVERSE) PLANNING
Implant planning commences by establishing the features
of the teeth and any missing alveolus that are to become
the implant-borne restoration. In today’s implant dentistry,
it is not acceptable to simply place an implant where bone is
available, on the assumption it can be effectively restored. A
decision needs to be made as to whether it is appropriate to
use the features of the patient’s remaining dentition or current prosthesis as a basis for planning implant positions, or
whether any modifications to the current situation need to
be made to improve aesthetic features or occlusion before
planning implant positions in detail.
For partially dentate patients, accurate preoperative
study casts, mounted on a semi-adjustable articulator,
will support the planning process and enable simulation
of the final restoration using a diagnostic wax-up or try-in
prosthesis.
When planning implant restorations in the aesthetic
zone, particular attention needs to be given to planning
how the mucosal (pink) supporting tissues around a final
restoration will appear. For example, in cases where there is
a high level to the animated upper lip, it may be unacceptable to restore an implant which, though stable, exhibits
un-natural supporting tissues.
SPECIAL INVESTIGATIONS AND DETAILED PLANNING
Once the prosthodontic arrangement has been envisaged, it
is necessary to find out whether there is sufficient bone
present to accommodate implant(s) in the ideal position(s)
to support the proposed restoration. Each type of implant
restoration has particular requirements in this regard, and
details are beyond the scope of this text.
An approximate estimation of the dimension of the alveolus may be made using callipers that penetrate the
overlying soft tissues to estimate bone width along an
edentulous space (ridge mapping). In all cases though, a
detailed clinical examination needs to be supplemented
with additional radiographic assessment such as plain film
radiography, and computed tomography, such as coned
beam computed tomography (CBCT). CBCT provides detailed three-dimensional (3-D) information about bone volume and adjacent structures which must not be violated
during surgery to insert implant(s). It is usual to gain further information from CBCT scans by using software applications that enable the proposed prosthesis to be visualised and to carry out virtual implant insertion tailored to
the requirements of the prosthesis (Fig. 5.2). The ways this
can be achieved include:
n
Creating virtual tooth replacements within the planning
software itself
n
Obtaining the CBCT whilst the patient has a radioopaque replica of the intended prosthesis in place
n
Using the planning software to combine a 3-D optical
scan of the intended prosthesis with the CBCT data.
At this point in planning, it should be possible to determine if there is sufficient bone volume to house implant(s),
or if not, whether additional bone can be generated using
a bone augmentation technique such as bone grafting.
Occasionally, radiographic investigations may show that
insertion of implant(s) in prosthodontically driven positions is not possible.
If it is decided that there is sufficient bone to insert the
implants in the required positions, it is usual to use the
information to generate an implant insertion guide (often
called a surgical stent), either using a digital workflow
directly from the simulated planning environment or by
traditional ‘analogue’ means in a dental production laboratory. It is also possible to use digital planning information with so-called dynamic guidance systems that allow
visualisation of the bone-drilling instruments in relation
to the 3-D plan in real-time, thereby avoiding the need for
a surgical guide. Planning information can also be used
to prefabricate restorations ready for immediate use following implant insertion.
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Master Dentistry
Fig. 5.2 Virtual placement of an implant to replace a missing maxillary lateral incisor. The figure on the left shows a cross section, and the figure on the
right, a transparent 3D image of a virtually placed implant in a position to support the proposed prosthetic tooth (shown in yellow in the right hand
figure).
TYPES OF RESTORATION
Restorations supported by dental implants may be classified
into two broad groups:
n
Those that replace only the lost dental hard tissues
(teeth themselves) and are therefore directly comparable to conventional single crowns or bridges, with
the dental implants acting as the ‘roots’ of the teeth
(Fig. 5.3).
n
Restorations that replace both the teeth and the supporting alveolar tissues to a greater or lesser extent. Such
prostheses include implant-assisted removable dentures
and fixed implant-assisted bridges that incorporate pinkcoloured prosthetic material (Fig. 5.4).
Single tooth and tooth-only bridge restorations are retained on the implant abutments using either a cement
lute or via screw retention. The access hole for the screw is
restored using a directly placed restoration such as composite resin after first applying a layer of soft protection
over the abutment screw head. Implant-assisted removable
dentures achieve greater support and retention than their
conventional counterparts because the implants with their
abutments act to support and retain the overdenture.
Abutments for implant-assisted dentures may incorporate
various kinds of precision attachment, magnet or a bar
and clip (Fig. 5.5).
The fixed implant-assisted bridge that incorporates pinkcoloured prosthetic material to replace both teeth and pink
tissues (periodontium and alveolus) is sometimes called a
hybrid prosthesis. For added strength, it usually incorporates
a titanium framework that is customised to be screwed either directly to the implants themselves or to transmucosal
abutments.
TIMING OF PROCEDURES
Multidisciplinary treatment planning for implant cases is
helpful to allow the clinical team to generate a customised
A
B
Fig. 5.3 (A) Screw-retained zirconium dioxide abutment and (B) cementretained implant-supported crown.
care pathway for each patient. For example, surgery may be
carried out by a different person from the person who plans
and delivers the restoration. The different stages in the
management pathway should be identified and any contingency plans that may need to be incorporated into the care
Fig. 5.4 Fixed implant maxillary bridge that incorporates pink-coloured
prosthetic material.
A
B
Fig. 5.5 Abutments as stud attachments (A) to provide retention for a
mandibular implant-assisted overdenture (B).
pathway should be highlighted. Fig. 5.6 shows a flow chart
of the potential care pathways that a patient may follow
during implant management.
5 • Restorative Management of Dental Implants
143
A detailed description of the surgical aspects of implant
treatment is outwith the scope of this text. What follows is
a brief overview of implant placement and abutment connection with specific reference to the involvement of the
restorative dentistry clinician.
PRE-IMPLANT PLACEMENT
The treatment plan should specify the precise positions for
implants that will support the implant-borne superstructure that should already have been envisaged.
Should a failing tooth or root remnant be present at a
potential implant site, the decision needs to be made as to
whether the implant will be placed immediately after tooth
extraction or following a delay to allow gingival healing.
Details about decision-making in this situation are beyond
the scope of this text.
IMPLANT PLACEMENT
The following description assumes the patient is able to
tolerate minor oral surgery and the restorative dentistry
procedures to complete treatment, has been deemed suitable in all other respects to embark on implant treatment
and has given informed consent to proceed with treatment.
Once implant positions have been determined, and if sufficient bone exists to allow implants to be inserted with the
likelihood of good stability, then surgery can proceed. Local
anaesthesia, sometimes in conjunction with intra-venous
sedation, is usually sufficient. Precise positioning of implants is essential if the goals of the treatment plan are to be
achieved. Whilst it may be possible for the experienced implant dentist to insert implants accurately using local anatomical landmarks, the procedure is facilitated using a
surgical guide that can precisely constrain the instruments
used for making the osteotomy in bone. Implant insertion
often involves making incisions to elevate a full thickness
mucoperiosteal flap, although it may sometimes be possible
to insert implants without flap elevation.
Once the implant is in place, a decision is made whether
to attach the transmucosal section with adaptation of the
mucoperiosteal flap around the transmucosal abutment or
whether to close the mucosa over the implant to leave it to
osseointegrate totally submerged.
An interim restoration is usually required before the implant is ready for restoration or further surgery to attach an
abutment. Where implants are totally submerged or where
only a healing abutment has been attached, either a removable denture or tooth-borne provisional bridge can be provided. It is important that interim restorations do not impart
loads onto implants that could interfere with osseointegration.
5.3 Surgical Phases
LEARNING OBJECTIVES
You should:
• be aware of the basic surgical principles for dental implant
placement
• be aware of the restorative/surgical interface associated
with the provision of dental implants.
ABUTMENT CONNECTION
If an implant is submerged beneath mucosa after insertion in
order to assist osseointegration, then it will be necessary to
uncover it, by means of a minor surgical procedure, in order
to attach a transmucosal part (often a healing abutment –
hence abutment connection surgery). This is achieved either
by raising a mucoperiosteal flap or, in some cases, through a
localised excision of the overlying mucosa using a tissue
punch or laser. Abutment connection surgery also offers the
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Master Dentistry
History and Examination
Special Investigations
Insufficient bone to place
implant
Bone grafting to planned
implant site
Partial failure of osseointegration of
implant – repair may be possible using
guided bone regeneration (GBR)
Complete failure of osseointegration
of implant – removal of failed implant
Options for modification of definitive
restoration in original treatment plan
Definitive restoration
agreed, ideal implant
placement determined
Surgical placement of
implant(s)
Surgical placement of
transmucosal abutment
Provisional restoration of
transmucosal abutment
Definitive restoration of
transmucosal abutment
Long-term maintenance of
implant and replacement
programme of restorations
Simultaneous placement of
transmucosal abutment or
provisional restorations
Simultaneous placement of
transmucosal abutment or
provisional restorations
Fig. 5.6 Flow diagram of the care pathway followed during implant treatment.
opportunity to manipulate the peri-implant mucosal condition for optimal aesthetics and long-term resilience.
5.4 Provisional and Definitive
Restoration of Dental Implants
LEARNING OBJECTIVES
You should:
• understand how dental implants are provisionally and
definitively restored
• recognise the options available for restoring dental
implants.
The numerous dental implant companies offer a plethora
of components and tools to allow dentists to restore their
implants. The practicing implant dentist must be intimately
familiar with the relevant components and instruments. This
section describes the basic stages during implant restoration.
IMMEDIATE RESTORATION OF IMPLANTS
Immediate restoration of implants describes attachment of
either provisional or definitive transmucosal sections (abutments), which in turn carry the restoration. This approach
requires implants tightly inserted into bone (i.e. have good
primary stability) that also benefit from being linked
together (splinted) to share mechanical load. For fixed
implant crowns and bridges, there are numerous ways of
attaching the overlying restoration either directly to implants
themselves by means of attachment (abutment) screws or to
intermediary abutments by means of attachment (prosthetic)
screws or cement. Immediate delivery of fixed restorations is
most often by means of a provisional restoration which can
either be developed at the chairside immediately following
implant insertion or made ready prior to surgery via a digital
workflow. Immediate restoration can also be achieved by fitting abutments onto implants immediately following implant
insertion that enable a removable denture (an implantassisted overdenture) to be attached. Typical attachment systems consist of ball-and-socket-type arrangements.
DELAYED RESTORATION OF IMPLANTS
Implants can be restored at the time of abutment connection surgery in the same way as for immediate restoration
at the time of implant insertion, the difference being that
the implants would now be expected to have osseointegrated. If records were obtained at the time of implant insertion, then restorations can be fabricated in readiness for
attachment at the time of abutment connection.
Implants replacing teeth in the aesthetic zone usually
benefit from being initially restored with provisional restorations. This approach, which may well be applicable to
5 • Restorative Management of Dental Implants
145
other parts of the mouth, allows trial and conformation
of aesthetic, occlusal and phonetic qualities, as well as
ensuring superstructures are as accessible to home
and professional cleaning as possible. The provisional
restoration can also be used to create a transmucosal
emergence form that makes a suitable transition from
round implant head to the natural cervical form of the
tooth to be replaced.
Definitive restoration requires accurate capture of the
implant position, the surrounding soft tissues and remaining teeth. This is achieved using transfer impression copings which are incorporated into either a physical impression or transfer copings which are recorded as part of a
digital intraoral scan.
5.5 Maintenance Phase
LEARNING OBJECTIVES
You should:
• understand the requirement for long-term maintenance
and follow-up of dental implants
• be familiar with potential complications associated with
dental implants.
The long-term follow-up and maintenance of implant restorations is an essential requirement to help ensure longterm stability and success. The provision and maintenance
of implants should be considered in conjunction with the
long-term dental care and maintenance of the remaining
dentition.
After delivery of implant treatment, the importance of
long-term care must be emphasised to the patient. Patients
must be instructed in the use of appropriate oral hygiene
techniques using suitable aids such as floss or miniinterdental brushes.
Radiographs of completed restorations can be used as a
baseline record of the implant–bone interface and allow the
clinician to check that restorations have been seated correctly onto the implant or abutment with no gaps or excess
cement seen at the interfaces.
LONG-TERM FOLLOW-UP
Implant, abutments and implant-supported restorations
are susceptible to plaque accumulation, which can induce
mucosal inflammation (peri-implant mucositis) that can
lead to inflammatory processes that result in loss of periimplant bone (peri-implantitis), eventually resulting in
total loss of osseointegration: implant failure. It is essential that a long-term review and maintenance regime is
established that is tailored to the risk profile of the individual patient, which needs to take account of factors
such as:
n
Susceptibility to peri-implantitis (e.g. smoking, diabetes,
previous history of periodontal disease)
n
Likelihood of mechanical overload (e.g. a patient with a
history of bruxing)
n
Complexity of the implant restoration where, for example, access for home hygiene is challenging
n
Predictable wear and tear where overdenture attachments are present.
In practice, this means patients will benefit from review at
least once per year. At follow-up appointments, the health of
the peri-implant mucosa must be carefully assessed by observation and palpation. At the time of writing, peri-implant
pocket depth measurement is controversial, partly because
accurate pocket depth measurements are difficult to record,
are not directly commensurate with disease in the same way
as they are for teeth and also because there is concern that
peri-implant probing might cause damage to the delicate
peri-implant mucosal attachment. Percussion of an osseointegrated implant gives a high pitch/bright sound and provides a crude test for osseointegration. Percussion of a fixed
implant restoration that produces a dull sound or mobility
should alert the clinician to the possibility of implant failure
or some other problem such as a loose abutment screw. Reassessment of the occlusal contacts on implant restorations
must be made at follow-up appointments to ensure that they
remain as planned.
Sequential radiographs (ideally long cone periapical)
provide an assessment of supporting bone levels compared
to baseline records taken at or soon after completion of
treatment. Progressive loss of peri-implant bone is a cardinal sign of peri-implantitis. The frequency of radiographic
follow-up should be a patient-based decision and should
conform to best practice with respect to regulations for the
use of ionising radiation.
COMPLICATIONS
Whilst the long-term survival rates of implants is high, complications of various sorts are relatively frequent and are
categorised as biological or mechanical. Long-term, longitudinal clinical studies have reported success rates of nearly
90% 10 years following placement of fixed, implant bridges,
although this success rate falls to 70% after 15 years. The
success for single-tooth restorations supported by dental
implants is higher, with a reported 10-year survival being in
excess of 95%.
Biological complications are not at all uncommon and
include peri-implant mucositis and peri-implantitis as described above. Peri-implant mucositis and peri-implantitis
broadly correspond to gingivitis and periodontitis, respectively. Peri-implant mucositis is a reversible condition directly related to plaque accumulation and should prompt
efforts to motivate and instruct the patient to achieve
improved and sustained plaque control. Professional debridement may be required to remove plaque and calculus, and care must be taken to keep scalers and other
instruments from damaging delicate surfaces. It may
be necessary to periodically detach implant-borne superstructures to facilitate assessment and cleaning. Periimplantitis usually commences as peri-implant mucositis
and causes peri-implant bone loss. It may present with
symptoms of discomfort or unsightly mucosal recession,
but often it is symptomless until the implant loses osseointegration, at which point, it is not amenable to reparative treatment. Vigilance and radiographic follow-up is
required to detect peri-implantitis. Unfortunately, periimplantitis is difficult to treat: various surgical and
non-surgical approaches are advocated.
Mechanical complications present in a variety of ways,
probably the most common in fixed implant restorations being abutment screw loosening causing a loose restoration
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and fracture/delamination of prosthetic tooth material. For
implant-assisted overdentures, wear and deterioration of
detachable components is common.
Soft tissue recession around abutments and along im-
plants may occur over time and lead to problems with
Self-Assessment: Questions
EXTENDED MATCHING ITEMS QUESTIONS
Theme: Components of the implant system
The list below (1–10) comprises different components of
the generic implant system together with restorations and
prostheses that may be implant retained. For each of the
statements (a–e), which describe an implant component or
restoration that is often used in implant-retained units,
select from the list the single most appropriate item that applies to that statement. Each item may be used once, more
than once or not at all:
1. Implant.
2. Abutment.
3. Screw-retained crown.
4. Screw-retained bridge.
5. Cement-retained crown.
6. Cement-retained bridge.
7. Screw-retained metal/acrylic hybrid bridge.
8. Overdenture.
9. Abutment screw.
10. Impression coping.
a. The section of an implant system that provides
retention and stability to a restoration.
b. The section of an implant system which traverses
the epithelial lining of the oral cavity.
c. A restoration which replaces the hard and soft
tissues of the oral cavity and cannot be removed by
the patient.
d. A device which allows the accurate transfer of an
implant’s position and orientation within the oral
cavity to the laboratory.
e. A restoration that is retained by stud, magnetic or
bar and clip precision attachments and that may be
removed by the patient.
aesthetics. Implant-supported restorations are not immune to the effects of trauma in the maxillofacial region.
With the union between implant and bone being direct,
there may be potentially more risk of bony fractures as
compared to avulsion of a natural tooth.
SHORT NOTES QUESTION
Write short notes on the steps taken to plan for a single
tooth implant to replace a missing upper central incisor.
SINGLE BEST ANSWER QUESTIONS
1. Primary stability of a dental implant
A. has no relationship to implant insertion torque
B. is unrelated to implant thread design
C. is unrelated to bone quality
D. should be as low as possible if immediate loading is to
be contemplated
E. is related to the density of the bone surrounding it
2. For use in implant planning, a scan appliance that the
patient wears at the time of having a cone beam volumetric tomography (CBCT) scan
A. must contain radiolucent teeth
B. should ideally contain discrete markers made with
temporary acrylic
C. should allow visualisation of the entire prosthetic
volume
D. prevents the prosthetic plan from being visualised in
relation to alveolar bone
E. can only be made by copying a removable denture
3. Peri-implant mucositis
A. implies loss of attachment of bone from an implant
surface
B. is a reversible condition
C. is a rare condition
D. is best treated surgically
E. has no similarities to gingivitis around teeth
Self-Assessment: Answers
EXTENDED MATCHING ITEMS ANSWERS
a. 1
b. 2
c. 7
d. 10
e. 8
SHORT NOTES ANSWER
A comprehensive list of notes would include:
Patient factors
n
Willingness to undergo surgery.
n
Willingness to leave restorations/prostheses out
during immediate, postoperative healing periods.
n
Lip/smile line.
Risk factors
n
Systemic.
n
Surgical.
n
Environmental (further trauma to area; e.g. through
contact sports).
n
Sufficient funding.
n
Other options for restoration (removable or fixed prostheses).
Site factors
n
Sufficient space between adjacent teeth, the need for
presurgical orthodontics.