A Clinical Guide To Occlusion
A Clinical Guide To Occlusion
A Clinical Guide To Occlusion
com/ PRACTICE
occlusion
What is occlusion?
1 S. Davies,1 and R. M. J. Gray,2
Patients need
a balanced
occlusion
Dentists need a
balanced view
on occlusion
}
• Repair the concept of Good Occlusal Practice, which is descended over this subject must be cleared,
• Move teeth applicable to all disciplines in dentistry. because no practising dentist can care well for
• Remove their patients without having regard for good
Guidelines of good occlusal practice occlusal practice.
without being involved These should be guidelines not rules.
in occlusion All patients are different, reacting to similar The importance of occlusion in dental
stimuli in different ways. So the detail of a practice
patient’s individual needs can and should be Occlusion can be defined very simply: it means
the contacts between teeth.
Before describing the significance of the dif-
ferent ways in which occlusal contacts are made
occlusion needs to be put into context.
Fig. 1 It has been claimed without evidence that The masticatory (or stomatognathic) system
occlusion causes: (Fig. 2) is generally considered to be made up of
three parts: the Teeth, the Periodontal Tissues,
and the Articulatory System.
Temporomandibular Negative influence on the It is a common criticism of dentists that our
disorders craniosacral mechanism dental schools ignore the third part of the
Poor posture Lack of beauty masticatory system, the articulatory system, in
Excessive ear wax Reduced strength in Deltoid their teaching. It appears that dentists feel that
Speech defects and Rectus Femoralis muscles their time at university did not prepare them
Prolapse of lumbar disc adequately in this area; and this view seems to
be the case worldwide. The undergraduate
dental education must, however, by necessity
Enamel
Dentine p
T
‘Occlusion’
=
Contacts
between
teeth
Perio y
Gingivae MJ
Bo al M
membrane
(a)
Change Change
in in
Articulatory System
(b)
Change Change
in in
Masticatory System
Centric Relation (CR) is not an occlusion at the condyle is against the most superior part of
all. CR has nothing to do with teeth because it is the distal facing incline of the glenoid fossa.
the only ‘centric’ that is reproducible with or This can be paraphrased as uppermost and
without teeth present. Centric Relation is a jaw foremost (Fig. 5).
The word relationship: it describes a conceptual relation- This is subject to debate. Some clinicians
ship between the maxilla and mandible. All prefer the idea that centric relation occurs in an
‘Centric’
attempts to lay down rigid definitions of centric ‘uppermost and midmost’ position within the
is an adjective. relation are plagued by the fundamental diffi- glenoid fossa; whereas very few people now
It should only be culty that there is no sure or easy way of proving support the idea that it is in an ‘uppermost and
used to qualify a that the locating criteria have been achieved. rearmost’ position. There is support for the
Centric Relation has been described in three uppermost and foremost hypothesis from a
noun.
different ways: anatomically, conceptionally,2 study of anatomy: the bone and fibrous articula-
Centric what? and geometrically. tory surfaces are thickest in the anterior aspect
of the head of the condyle and the most superior
Anatomical aspect of the articular eminence of the glenoid
Centric Relation can be described as the posi- fossa. This is, however, of only academic interest
tion of the mandible to the maxilla, with the and not of clinical significance as there is no reli-
intra-articular disc in place, when the head of able simple means of determining the exact
Conceptual
Centric relation can be described as that position
of the mandible relative to the maxilla, with the
articular disc in place, when the muscles that
support the mandible are at their most relaxed
and least strained position. This description is PB
pertinent to an understanding of ‘ideal occlu- el. att. IZ
sion’. This definition supports the concept of a AB
‘qualitative’ relationship between a jaw position
and another element of the articulatory system. BLZ SPt
IPt
Geometrical
Centric Relation can be described ‘as the posi-
tion of the mandible relative to the maxilla,
with the intra-articular disc in place, when the fib. att.
head of the condyle is in terminal hinge axis’.
In order to understand what this frequently
used definition means it is easier, initially, to
fib. att. = fibrous attachment to posterior neck of condyle
think about one side of the mandible only. The
mandible opens by firstly a rotation of the el. att. = elastic attachment to fossa
condyle and then a translation which is down- BLZ = bilarminar zone
wards and forwards. Therefore, when the PB = posterior band of meniscus
mandible closes the the terminal closure is IZ = intermediate zone of meniscus
purely rotational. At this phase of closure the AB = anterior band of meniscus
mandible is describing a simple arc, because the SPt = attachment to the superior pterygoid
centre of its rotation is stationary. This provides (superior head of lateral pterygoid)
the ‘terminal hinge point’ (of rotation) of one IPt = attachment to the inferior pterygoid
side of the mandible; but because the mandible is (inferior head of lateral pterygoid)
one bone with two connected sides these two ter-
minal hinge points are connected by an imagi-
nary line: the terminal hinge axis. This axis is,
therefore, envisaged by imagining the stationary,
centres of rotation of each condyle whilst the
mandible is moving only in the rotational phase
of movement. It is the fact that the mandible is
describing this simple arc, when the heads of
condyle are in the terminal hinge axis which is of
the most clinical significance. This will be dis-
cussed later, when the techniques for finding (a)
centric relation are presented.
•Reduces tissue
resistance
•Causes failure
•Promotes pain
/dysfunction
he mandible moves, relative to the max- the mandibular muscles. The lateral pterygoid
Technique
Dynamic occlusion
Articulating paper or foil
If the intention is to mark the occlusal surface
of a tooth in order to indicate the position of a RHS LHS
contact as opposed to simply discovering
whether there is such a contact (shimstock or Non-working side interferences
floss), then a medium to retain some ink needs
to be used. It may be double or single sided, Working side interferences
but it must be thin and dry (Fig. 9).
Crossover position NWS Int
At least two colours will be needed. Firstly
WS Int
so that the occlusal contacts in the static and
dynamic occlusions can be differentiated; and Canine guidance
secondly, so that in operative dentistry the
occlusion pre- and post-treatment can be Group function
compared.
Articulators
Notes
Articulators are not essential. Their use is not
a guarantee of success or of an easy life. Artic-
ulators are a very useful tool if the dentist
wishes to go in the direction of reproducing
the way in which the patient’s jaws move one Fig. 9 Paper tissue (for drying occlusal surfaces of
against another. This is valuable information teeth) and two colours of thin (40µ)
as it assists in the accurate recording of the articulating paper (for making occlusal
dynamic occlusion. The nearer a particular contacts) held by Miller forceps
articulator can reproduce the patient’s move-
ments, the closer it will be possible to con-
struct occlusal schemes that predictably
conform to the dentist’s objectives, whatever Because the paper is
they may be. thin it is much easier
In deciding which articulator to use, it is to use it if it is
important to ask the question, ‘What move- supported by a
ments of the mandible do I wish to reproduce, rigid holder
for this patient at this time?’
The key point about this approach is that it
Fig. 2a Left lateral excursion Fig. 2b Non working side interference during left
lateral excursion
case; the easiest approach is undoubtedly not to not ‘interfere’. The danger in this approach
consider whether the new restoration changes is that the new occlusion may still not be an
the patient’s occlusion, maybe hoping not to ideal one, because of the existence of other
‘Fingers crossed’ change it too much. The reason why the confor- potential interferences. This new ‘less than
dentistry equals mative approach is favoured is not because it is ideal’ occlusion may be a less harmonious
stress the easiest but because it is the safest. It is less one which the patient will tolerate less well
likely to introduce problems for the tooth, the ie the possibility of iatrogenic problems
periodontium, the muscles, the temporo- may arise.
mandibular joints, the patient and the dentist. 3. Finally there should not be an existing tem-
poromandibular disorder (TMD). If there
When to use the conformative approach? is, the decision must be taken whether or
The short answer is to use it whenever you can. not to treat it first, since it is possible that
It is possible to provide a restoration to the con- the treatment of the TMD will result in a
formative approach when: change of the patient’s occlusion.
1. The patient has an ideal occlusion, ie centric Improving the occlusion within the restrictions of
Q: When do you occlusion (CO) is in centric relation (CR) the conformative approach
use the with anterior guidance free from posterior Although the principle of not changing the
interferences. This is unusual, it is much patient’s occlusion is paramount within the
conformative more likely that: conformative approach, this, of course, refers
approach? 2. The patient does not have an ideal occlu- to the occlusal contacts that the patient has
sion, but that the removal of the existing between their teeth that are not being
A: When ever occluding surface of the tooth to be restored presently restored. It does not mean that the
does not mean an inevitable change in the new restoration should slavishly reproduce
you can patient’s centric occlusion or anterior guid- the exact occlusion that the tooth in need of
ance. Examples of an occasion where this restoration has. One of the purposes of restor-
will not be possible is either if the tooth that ing it would probably be lost if that was the
is to be restored is a deflecting contact; ie it case. How the occlusion may be improved is
provides the principal guiding contact from best considered within the principles of ‘ideal
CR to CO, or if the tooth is providing a occlusion’.
heavy posterior interference. On the tooth level, ideal occlusion is
In both of cases shown in Figures 1 and 2 it described as an occlusal contact that is: ‘in line
is attractive to think that all that the dentist with the long axis of the tooth and simultane-
has to do is to provide restorations that do ous with all other occlusal contacts in the
Fig. 5 Shot of pre-existing Fig. 6 Close-up of tooth with Fig. 8a Initial check of finished Fig. 8b After adjustment
marks pre-existing marks restoration
touching in exactly the same way as they did to be accurately recorded and that record has
before. This is either done by referring to some to be transferred to the technician. This is the
diagrammatic record made, or by reversing the clinician’s responsibility. Secondly, the tech-
colour of the paper or foils used pre-opera- nician has the responsibility to preserve the
tively, or from memory. accuracy of that record during the laboratory
In the illustrated case it can be seen that the phase of treatment. Finally, because of the
occulsal contact against the mesial marginal interval in treatment to allow the restoration
ridge of the restored UL4 (24) is slightly too to be made, the clinician has the responsibil-
heavy (Fig. 8a); this has prevented the palatal ity to maintain the patient in the same occlu-
cusp of this tooth from occluding and has sion during that interval. Consequently it is
changed the occlusion of the canine. After min- imperative that the patient is dismissed from
imal adjustment, this has been rectified (Fig. the preparation appointment with a tempo-
8b). For simplicity of illustration, the dynamic rary restoration which will maintain the same
occlusion has not been shown in this series. relationship between the prepared tooth and
Fig. 7 Close-up of finished the adjacent and opposing teeth (Fig. 10).
restoration The EDEC principle for indirect restorations
The EDEC principle is still followed for indi- Examine
rect restorations (Fig. 9). The essential differ- The examination of the patient’s pre-existing
ence between a direct and an indirect occlusion is carried out in exactly the same way
restoration is that a second operator is as described for the direct restoration. There is a
involved, namely the laboratory technician. need for that information to be transferred
We believe that it is a more accurate represen- accurately to the laboratory technician: a record
tation of the working relationship to consider must be made.
the laboratory technician to be a second oper- The provision of an indirect restoration
There is no point ator rather than an assistant, as it makes it always involves the transfer of anatomical
in the technician clear that the technician also has expectations information in the form of the impressions. It is
and responsibilities the occlusal relationship of teeth which is the
designing the Two operators means there are several con- important record, because the technician can-
occlusal aspect of sequences to the treatment sequence (Fig. 10). not carry out his or her responsibilities without
the restoration The dentist not only has to examine the occlu- knowing how the upper and lower models
on models that sion but the results of that examination have relate to one another.
do not accurately
conform to the
Fig 9 The EDEC principle for indirect restoration
patient’s
occlusion
E = Examine and record the pre-existing occlusion
D = Design the restoration
E = Execute the restoration
C = Check the occlusion at the fit appointment
Fig. 13a A sketch is made of the patient’s Fig. 13b This sketch is reconfigured at the
occlusion (before preparation of a bridge) by the laboratory as an aid to the technician to confirm
dentist at the chairside the correct mounting of the models
For these reasons, three important guidelines • If a bite registration is going to be used to
emerge: record the relationship of other teeth it must
be carved so that no part of it touches the
• If possible the bite registration material models of the mucosal surfaces.
should only be used between the prepared • Before the technician starts to use the models
tooth and its antagonists; not used to take a to construct the occlusal part of the restora-
full arch record. tion, the occlusion of those models must be
Fig. 14a Patient in centric occlusion Fig. 14b Wax record of centric occlusion
Fig. 14c Patient goes into right lateral excursion Fig. 14d Duralay recording the pathway of the
LR 5 (45) relative to upper premolars during
right lateral excursion
Fig. 15a Set Duralay record of movement of Fig. 15b Twin stage articulator
LR5 (45) relative to upper premolars
Fig. 15c The Duralay record is used to cast an Fig. 15 d Centric occlusion (static occlusion)
opposing model opposing the inlay preparation of UR4 (14)
Fig. 16a Wax record is correctly seated... Fig. 16b ...indicating that the condylar angle is 45o
(scale FH) Frankfurt Horizontal (KaVo Articulator)
Fig. 17a Wax is incorrectly seated… Fig. 17b …because condylar angle is wrong
Fig. 18b Condylar angle is adjusted until... Fig. 18c ...gap on the NWS is the same as in the
mouth (see Fig. 18a)
Fig. 18d Too steep a condylar angle... Fig. 18e ...created too big a gap
Fig. 20a Transfer coping on die after technician Fig. 20b Transfer coping ready to use in the
has reduced the height of the core mouth prior to fit of crown
1 2 3
Impression making Model casting Model mounting
5 4
Proceed with Model Technician’s
laboratory fabrication grooming verification of
of restoration (if necessary) occlusion of models
against occlusal sketch
Fig. 22c Final crown on articulator with static Fig. 22d Final crown in mouth with static
occlusion marked occlusion marked
chance we have to get it wrong! If it is a posterior relationship which that occlusion dictates. In
restoration then it is unlikely to be ideal if there is that scenario, because inevitably the patient is
any occlusal contact during lateral or protrusive going to have a different jaw relationship after
excursion. Ask the patient to slide their teeth dental treatment, it is the responsibility of the
using one colour of articulating paper or foil, clinician to ensure that the new occlusion is
and then tap their teeth using a different colour. more, rather than less, ideal in relation to the
rest of the articulatory system.
The reorganised approach in simple As stated earlier, an occlusal contact that
restorative dentistry guides the mandible into the jaw relationship
The rationale and procedure for restoring a is known as a deflecting contact. Some restora-
patient to the ‘reorganised approach’ will be, tive authorities advise that teeth that are not
more appropriately, given in the section: ‘Good directly involved in the restoration (tooth to
Occlusal Practice in Advanced Restorative be restored and its opposing tooth) can be
Dentistry’. altered to improve the occlusion, within the
In that section, we will be considering the ‘conformative approach’. We agree that is an
treatment of a patient when the treatment of attractive idea to try to improve the occlusion
their dental needs means that it will be impossi- of the surrounding teeth, by say removing the
ble to keep the same occlusion and so the jaw incline contacts. The difficulty is to be sure
that one is not changing deflecting contacts,
because if they are being altered then jaw rela-
tionships are being changed. This, then, is not
the conformative approach. The objective is
now the provision of an ideal occlusion (Fig.
23). For this to be successfully achieved,
detailed planning and usually multiple
changes in occlusal contacts are needed.
The important limitation of the conforma-
tive approach is that none of the teeth to be
prepared or adjusted can be deflecting con-
tacts, because if they are then as a conse-
quence of changing them the jaw relationship
will probably be changed. If modification to
Fig. 24a New restorations Fig. 24b After adjustment of new these deflecting contact teeth is envisaged,
are too high restorations, occlusion of adjacent this then becomes a reorganised approach no
teeth returns
matter how few teeth are being restored. This,
The EDEC
principle when
restoring complex
cases to the
conformative
approach
E = Examine
the pre-existing Fig. 1b LL4 (34), LL6 (36) are prepared and
occlusion Fig. 1a Pre-operative view before proposed
Duralay ‘bites’ taken on these teeth using
occlusal contacts on LL5 (35) and LL7 (37) to
crown preparation of LL4,5,6,7 (34,35,36,37) ensure the ‘conformative approach’
D = Design
an operative
procedure well tolerated by the patient at every level. No
which allows the occlusion can be said to be ‘intrinsically bad’;
an occlusion may only be judged by the
conformative patient’s reaction to it.
approach An adverse or poorly tolerated reaction may
include the following:
E = Execute • A temporomandibular disorder
that plan • Occlusal trauma to the periodontal tissues,
leading to increased mobility
• Fracture of restorations or of the teeth
C = Check • Excessive tooth surface loss
that each stage Fig. 1c All teeth are now prepared, but bites • Hypersensitivity.
of the restoration against LL4 and 6 ensure models are mounted
to pre-operative registration (conformative Singularly or collectively these represent a
conforms to the approach) most unhappy outcome to dental treatment.
occlusion of The vast majority of dentists who have been
the previous actively involved in the provision of extensive
primary need for restoration of their teeth but restorative treatment plans have some experi-
stage also who have a TMD. These patient, in the ence of the distress that any or all of these
authors’ opinion, require the closest adherence sequalae produces.
to the principles of the re-organised approach. For every dentist actively involved in the
provision of advanced restorative treatments
When the Conformative Approach there is always the danger that a patient will
cannot be adopted, there are only react adversely to our treatment, but we
two possibilities: believe that this strategy makes it much less
likely. This is because the principle of provid-
First possibility ing an occlusion to the re-organised approach
Plan to provide new restorations to a different is to provide an occlusion that is ideal to the
occlusion which is defined before the work is patient, at every level.
The reference started: ie ‘to visualise the end before starting’:
points of the this is the re-organised approach. Definition of an ‘ideal occlusion’, at every
level
pre-existing Second possibility The definition of ‘ideal occlusion’ needs to be
occlusion may be Change the occlusion, without having given at the tooth level, at the system level and
lost with the first planned the new occlusion and the related jaw at the patient level.
sweeps of the air relationship. To provide an occlusion which
does not conform with the previously well The tooth level
rotor tolerated one. This is an occlusion that has An ideal occlusion will provide:
been arrived at by accident: ie the unorganised
approach. • Multiple simultaneous contacts
• No cuspal incline contacts
What is the treatment objective of a • Occlusal contacts that are in line with the
re-organised occlusion? long axis of the tooth
At its very simplest, it is to provide restorations, • Smooth and, wherever possible, shallow
which although changing the occlusion, will be guidance contacts.
Fig. 2 The flag is attached to the Fig. 3 An arc is drawn on the Fig. 4 The canine arc is bisected by an
articulator and the incisal pin is set flag at a set radius using the tip arc using the articulator hinge as its
before the upper model is removed of the lower canine as its centre centre. This intersection is the centre of
(Canine Arc) a possible occlusal plane (sphere)
7a
Fig. 7 Wax carved to proposed occlusal planes
7b 7c
The EDEC
principle in the
re-organised
approach
E = Examine the
characteristics of
the existing Fig. 8 Morphology is carved into the wax, to Fig. 10a Pre-operative lower model
represent the final abutments and pontic of the
occlusion, proposed bridge to a planned occlusion
including jaw
relationship
D = Design and
plan the new
occlusion
E = Execute
the new occlusal Fig. 10b Lower model after wax up to idealised
occlusal planes
prescription
prior to definitive Fig. 9 Minor occlusal adjustment is necessary to
restorations the teeth opposing the abutment teeth, whereas
the crown on the overupted tooth opposing the
gap ( in this case) will need to be replaced
C = Check that
you are conform- Step 7. Carve morphology into the wax to
ing to this new create the waxed up teeth (Fig. 8). (How do you
carve an elephant out of a block of marble?
occlusion in Knock off all the bits that don’t look like an ele-
the definitive phant.) .
restorations Step 8. The wax up of the lower arch is now
complete and the upper model is refitted to the Fig. 11a Pre-operative lower model, illustrating
articulator (Fig. 9). So that the incisal pin again lingual and mesial tilting of distal abutment of
proposed bridge
rests on the incisal table, adjustment will usu-
ally be needed to the opposing teeth in the
upper arch, this may be minor equilibration or
significant change to severely overupted teeth.
Note: These adjustments will need to be made
when the lower restoration is fitted; the patient
must be advised of this at the planning stage.
Is equilibrium
possible? Summary
Practice on A wax up of a proposed restoration is an ideal
opportunity to see the end point of an occlusal
plaster before change, before picking up a handpiece. The
making improvement in the occlusion can be devel- Fig. 11b Lower model after wax up illustrating
irreversible oped and visualised (Figs 10a,b and 11a,b) improved occlusal planes
changes in
The pre-definitive restoration reach it will already be known. This ‘mock
the mouth treatment phase equilibration’ is highly recommended. It pre-
(E = executing the planned new occlusion and vents anxiety in the mind of the clinician who
jaw relationship) when carrying out an equilibration may oth-
erwise wonder whether he or she will be able
Equilibration (adjusting natural teeth) to finish what they have started! The aim of
Equilibration will already have been per- equilibration is to effect changes in the centric
formed on the models in the design phase; so occlusion to give it as far as possible the
the end point and adjustments required to features of an ideal occlusion:
Fig. 12b Patient’s dentition exhibiting significant Fig. 12c Upper stabilisation splint with labial
tooth surface loss veneers to fit over unprepared upper anteriors
Fig. 12d Mirror view of upper stabilisation splint Fig. 12e Anterior view of upper stabilisation
splint. Note the provision of median diastema
Fig. 13a The models, including provisional crowns Fig. 13b Custom incisal guidance table. The
on upper anterior teeth, are used to carve a incisal pin of the articulator is resting in a postion
custom incisal guidance table in a slow setting that is related to the centric occlusion of the
autopolymerising acrylic models
accurate
representation
of the end point
of the treatment
plan
Fig. 13e Using this technique it is easy to see Fig. 13f Custom incisal guidance table
exactly what the crown lengh and palatal determining the lengh of right canine definitive
contour should be to provide the same canine crown
guidance as was present in the provisionals
http://dentalbooks-drbassam.blogspot.com/
Amendment: This paper is an updated version from the original printed version.
The terminology box at the base of Page 491 has been corrected. PRACTICE
occlusion
E = Examination
The examination of the patient’s pre-treatment
occlusion is the first stage.
Treatment
Treatment
The principal consequence of occlusal load- The intention of this technique is to ensure
ing onto the more deformable mucosa will be that the occlusal pressure will still be resisted by
the loss of occlusal contact. This is a particu- the ridges after the natural teeth have been min-
lar problem in patients with free-end saddles. imally displaced into their sockets.
It was for this reason that Applegate An identical clinical procedure may be
described a technique of denture construc- undertaken for a reline and this maybe suffi-
tion,2 universally known as the ‘altered cast cient to restore the occlusion in saddle areas.
technique’, which consists of the following
stages: Mucosa-supported dentures
Treatment
Figures 5 and 6 show an entirely mucosa sup-
ported lower partial denture, immediately
after having been supplied to the patient (Fig.
5) there is an occlusion between the denture
and the patient’s maxillary teeth; whereas
after 6 months (Fig. 6), there is no occlusal
contact against the opposing teeth.
Complete dentures
It has been said that ‘a patient with no eyes
cannot see, a patient with no legs cannot run,
Fig 5 Occlusion at insertion
yet a patient with no teeth expects to eat and
Fig 9a F/F with compensating curves Fig 9b F/F with compensating curves
which might compromise this stability are curves (Fig. 9a and b) are incorporated into the
illustrated in Figure 7. They are: dentures. The same philosophy holds for lateral
excursions.
• Unilateral prematurities
This means that the ‘ideal occlusion’ for a
• Occlusal tables which are too large
patient with complete dentures differs from the
• Injudicious placement of teeth.
‘ideal occlusion’ for a dentate patient, for exam-
For other patients, however, lateral and pro- ple it is ‘ideal’ for complete denture stability if
trusive movements are part of their normal there is no posterior disclusion during lateral
‘ruminatory’ mandibular pattern and for these excursions, whereas immediate and lasting
patients, a balanced dynamic occlusion (bal- posterior disclusion is usually considered to be
anced articulation) is required. In other words, ideal for the dentate patient.
consideration must be given not only to the sta- It is because teeth on a denture are not
tic but also to the dynamic occlusal prescription. attached to the patient’s neuro-muscular skele-
In this situation, the teeth of the maxillary tal system and there is no possibility of neural
denture must maintain harmonious sliding stimulation via periodontal proprioceptors that
contacts with the teeth of the mandibular the criteria of what makes an ‘ideal occlusion’
denture in all excursive movements otherwise have changed. Although there are mechanore-
denture stability may be significantly compro- ceptors in the denture bearing oral mucosa, they
mised. For example, in a natural dentition, the do not continue to send a stream of impulses to
act of protrusion usually results in a posterior the sensory cortex.
open bite (the Christensen phenomenon — It, therefore, beholds the dentist to deter-
Fig. 8). Such a situation would lead to instabil- mine the occlusal requirements of complete
ity in complete dentures, hence compensating denture wearers prior to prescribing complete
CI I CI II CI III CI IV CI V
Stages of construction
1. The design of the fitting surfaces
‘impression taking’ Fig 11a Gothic arc trace apparatus
It is the dentist’s responsibility to design the
denture supporting area on some accurate
models and it is outside the scope of this section These will record a ‘map’ of the patient’s
to expand on this aspect of full denture con- range of movements, by asking the patient to
struction other than to say that it should not be go into:
left to the technician.
The term ‘bite registration’ is a poor one; as The starting point of these movements as
the patient is not asked to bite into anything; inscribed by this trace is the arrowhead (Fig.
in fact if they do, it is likely that they will 11b) and represents centric relation (CR or
make an uncontrolled mandibular move- RCP). If it proves impossible to obtain an
ment away from CR. arrowhead, this means that the patient does not
The purpose of this stage is to record the rela- have a reproducible maxillo-mandibular rela-
tionship between the upper and lower jaws; in tionship. This is an important finding and
the vertical, horizontal and anterio-posterior would indicate the need for some further pre-
planes. Before this stage can be completed, the definitive treatment in order to discover a
decision whether to make the dentures to the reproducible jaw relationship (ie CR).
conformative or re-organised approach must This could be achieved by the use of ‘pivotal
have been taken. In addition, it must have been appliances’. A polished pivotal appliance
decided whether only a balanced static occlu- (Fig.12) may look unusual but it is remarkable
sion (balanced occlusion) or also a balanced how well they are tolerated. After fitting, fur-
dynamic occlusion (balanced articulation) is ther adjustments are easily made to find the
Orthodontics and
6 occlusion
S. J. Davies,1 R. M. J. Gray,2 P. J. Sandler,3 and K. D. O’Brien,4
BRITISH DENTAL JOURNAL, VOLUME 191, NO. 10, NOVEMBER 24 2001 539
PRACTICE
occlusion
Treatment considerations
Orthodontic treatment methods can be
divided into two depending on the goals of
treatment,3 these are camouflage and modifi-
cation. To introduce this concept we must
Fig. 2 ‘Six keys to occlusion’ first consider the aetiology of a malocclusion,
are present (after Andrew ); which includes skeletal, dento-alveolar and
a perfect smile
soft tissue components, the first two compo-
540 BRITISH DENTAL JOURNAL, VOLUME 191, NO. 10, NOVEMBER 24 2001
PRACTICE
occlusion
nents being particularly relevant. An exam-
ple of the dento-alveolar component is
crowding as a result of an adverse tooth-alve-
olar tissue ratio. When the malocclusion is
caused by the skeletal component, the patient
typically presents with a discrepancy between
the size or position of his or her skeletal bases
in the anterio-posterior, lateral or vertical
dimension.
At a very simplistic level the orthodontist
when faced with these discrepancies has two
main choices:
• To provide treatment directed at camouflag-
ing the problem and not changing the skele-
tal pattern.
or
• Attempting skeletal modification with
either functional appliances or orthog-
nathic surgery Fig. 3 Not all ‘keys to occlusion’
have been achieved but
Camouflage aesthetics are still good
If the treatment is directed at camouflage, space
is created in the dental arches by extractions,
arch expansion or both, and the other teeth are
moved into this space to achieve the treatment
objective.
Even if the person has a skeletal discrep-
ancy, the orthodontist may choose to accept
the discrepancy and attempt to camouflage
the problem by simply moving the teeth.
Unfortunately, whilst the dental appearance
can be predicted the facial appearance cannot
(Figs 6 and 7). Furthermore, there is no scien-
tific evidence for any technique that may aid in
prediction. Some clinicians may say they can
accurately predict facial changes, but this claim Centric Relation
is totally unfounded.
BRITISH DENTAL JOURNAL, VOLUME 191, NO. 10, NOVEMBER 24 2001 541
PRACTICE
occlusion
General Record
Patient Date
Age
TMJ
Tender to palpation? Lateral pole Intra-auricularly
Lateral Pterygoid
U
542 BRITISH DENTAL JOURNAL, VOLUME 191, NO. 10, NOVEMBER 24 2001
PRACTICE
occlusion
Erupted teeth
X-Bites
scissors
IOTN If there is a
displacement no. DHC................. possibility of
AC................. changing the jaw
.......mm R L ANT
relationship, the
clinician should
Page 2 examine the
patient’s jaw
relationship
before and after
treatment
BRITISH DENTAL JOURNAL, VOLUME 191, NO. 10, NOVEMBER 24 2001 545
PRACTICE
occlusion
Buccal Segments
Molars
I II III
R .....unit
L .....unit
Canines
I II III
R .....unit
L .....unit
Static Occlusion
Does CO occur in CR? ................ IF NOT..prem contact in CR?
Roughly or exactly
Dynamic Occlusion
RHS LHS
Non-Working Side Interferences
Canine Guidance
Group Function
546 BRITISH DENTAL JOURNAL, VOLUME 191, NO. 10, NOVEMBER 24 2001
PRACTICE
occlusion
lower jaw. This type of treatment, if it works,
does provide excellent dental results (Fig. 8)
and, perhaps, reduces the overall time that a
child spends wearing fixed appliances.
Orthognathic surgery obviously alters a per-
son’s skeletal pattern, however, this is a very
complex specialist treatment that should only be
carried out, after counselling, for those patients
who have major concerns with their facial and
dental appearance.
One other form of ‘growth modification’ is
expansion of the dental arches with either
removable or fixed appliances. This type of
treatment is gaining popularity with many den-
tists and orthodontists, especially those who
attend courses of the latest ‘orthodontic guru’.
There is, however, no evidence that these
appliances can alter the growth of the alveolus
and some research has suggested that most
expansion is not stable and simply invites
relapse in the occlusion.7
BRITISH DENTAL JOURNAL, VOLUME 191, NO. 10, NOVEMBER 24 2001 547
PRACTICE
occlusion
als have been carried out these theories must
remain as simply conjecture, anecdotal and
lacking in evidence.
Summary
The relationship between orthodontics and
occlusion is important. Unfortunately, suppo-
sition and hearsay can govern treatment phi-
losophy.
d Confining considerations to factors that are
supported by scientific evidence, the following
conclusions may be accepted:
548 BRITISH DENTAL JOURNAL, VOLUME 191, NO. 10, NOVEMBER 24 2001
PRACTICE
occlusion
Fig. 9a i –iii Pre-
treatment
photographs of a Cl 2
patient before
orthognathic surgery
BRITISH DENTAL JOURNAL, VOLUME 191, NO. 10, NOVEMBER 24 2001 549
http://dentalbooks-drbassam.blogspot.com/ PRACTICE
occlusion
Occlusal considerations in
7 periodontics
S. J. Davies,1 R. J. M. Gray,2 G. J. Linden,3and J. A. James,4
In this part, we will
discuss:
• Whether occlusal Periodontal disease does not directly affect the occluding
trauma is significant surfaces of teeth, consequently some may find a section on
in the aetiology of periodontics a surprising inclusion. Trauma from the occlusion,
periodontal disease
• Whether occlusal
however, has been linked with periodontal disease for many
treatment is indicated years. Karolyi published his pioneering paper, in 1901
for patients suffering ‘Beobachtungen uber Pyorrhoea alveolaris’ (occlusal stress and
from periodontal ‘alveolar pyorrhoea’).1 However, despite extensive research
disease over many decades, the role of occlusion in the aetiology and
• Making a diagnosis of pathogenesis of inflammatory periodontitis is still not
trauma from occlusion
• Tooth mobility
completely understood.
• Occlusal equilibration
and the splinting of
teeth
Why should trauma from occlusion be force applied to a tooth or to teeth with normal
considered to have a role in the aetiology and healthy supporting tissues.
of periodontal disease? Secondary occlusal trauma refers to changes
Occlusal trauma
which occur when normal or abnormal
Injury to the
cclusal trauma has been defined as occlusal forces are applied to the attachment
periodontium resulting
from occlusal forces which
exceed the reparative
capacity of the
O ‘injury to the periodontium resulting from
occlusal forces which exceed the reparative
capacity of the attachment apparatus’: ie the tissue
apparatus of a tooth or teeth with inadequate or
reduced supporting tissues. Recently, the dis-
tinction between primary and secondary
attachment injury occurs because the periodontium is occlusal trauma has been challenged as mean-
unable to cope with the increased stresses it ingless since the changes that occur in the peri-
experiences. Compare this definition with the odontium are similar irrespective of the initial
Periodontitis one for inflammatory periodontal disease: level of periodontal attachment. More usefully,
The result of an ‘Periodontitis is the result of an interaction occlusal trauma can also be described as acute
interaction between a between a susceptible host and bacterial factors in or chronic.
susceptible host and dental plaque, which exceeds the inherent protec- Acute trauma from occlusion occurs follow-
bacterial factors in dental tive mechanisms of the host’. ing an abrupt increase in occlusal load such as
plaque, which exceeds occurs as a result of biting unexpectedly on a
the protective mecha- Both processes result in injury to the attach- hard object. Chronic trauma from occlusion is
nisms of the host ment apparatus because the periodontium is more common and has greater clinical signifi-
unable to cope with the pathological insult cance. In the context of this paper occlusal
1*GDP, 73 Buxton Rd, High Lane, which it experiences. It is quite right, there- trauma will mean chronic occlusal trauma.
Stockport SK6 8DR; P/T Lecturer in fore, that dentists should ask themselves two
Dental Practice, University Dental questions: Question 1
Hospital of Manchester, Higher Does occlusal trauma have a role in the
Cambridge St., Manchester M15 6FH; 1. Does occlusal trauma have a role in the
2Honorary Fellow, University Dental aetiology of periodontal disease?
aetiology of periodontal disease?
Hospital of Manchester, Higher This is a key question because the answer will
Cambridge St., Manchester M15 6FH
2. Should occlusal treatment be considered
determine:
3Reader in Periodontology, Divsion of for the patient with compromised peri-
Restorative Dentistry, School of odontal attachment? • Whether occlusal forces influence the onset
Dentistry, Queen’s University, Belfast of plaque-induced inflammation.
BT12 6BP 4Lecturer in Oral Pathology Before attempting to answer these two
and Periodontics, University Dental • Whether occlusal forces enhance the rate of
questions, the different types of trauma from
Hospital of Manchester, Higher periodontal destruction.
Cambridge Street, Manchester occlusion need to be defined.
M15 6FH Considerable energy has been directed at try-
*Correspondence to : Stephen Davies How is trauma from occlusion classified? ing to determine the answer to these questions,
email: stephen.j.davies@man.ac.uk Historically trauma from occlusion has been clas- because of the possibility that trauma from
REFEREED PAPER
© British Dental Journal sified as either primary or secondary. Primary occlusion might contribute to the pathogenesis
2001; 191: 597–604 occlusal trauma results from excessive occlusal of periodontal disease. Research studies
BRITISH DENTAL JOURNAL, VOLUME 191, NO. 11, DECEMBER 8 2001 597
PRACTICE
occlusion
designed to examine the effects of occlusion fall directions. This is usually created in the ani-
into three categories: mal by the provision of a supraoccluding
It is the aim of this onlay.
section to answer • Human cadaver investigations • Or is an orthodontic force, created by a spring
two questions • Animal studies and is a unilateral force that results in the
• Human clinical studies. deflection of the tooth away from the force.
1. Human cadaver investigations
Question 1
Studies published in the 1960s and 1970s were 3. Human clinical studies
Does occlusal inconclusive.2,3 Few clinical studies have identified a clear rela-
trauma have a role 2. Animal studies tionship between trauma from the occlusion
in the aetiology In these studies the variables were the level of and inflammatory periodontitis in humans.
of periodontal periodontal attachment and the characteristics A major problem with clinical studies of this
of an applied force, and the way in which it type is the lack of a reliable index for measuring
disease? might be varied (See Figure 1 for a summary of the degree of occlusal trauma to which a tooth
the results). is subjected.
Question 2 The periodontal attachment level is one of If trauma from occlusion exists there are obvi-
three types: ous difficulties in assessing whether the rate of
Should occlusal
attachment loss is greater in patients with a con-
treatment be • A normal healthy periodontal support
tinuing plaque induced periodontitis. This is
• A healthy periodontal support but a reduced
considered for the because secondary referral units where the
bone height. This is the experimental model
patient with a majority of clinically based studies are carried
equivalent of a post-periodontal therapy
out, do not routinely monitor patients who
compromised level
maintain good plaque control.
periodontal • An active plaque-induced periodontitis.
On the system level ideal occlusion is or is not
attachment? The type of force that can be applied to the ideal for the rest of the articulatory system: the
animal tooth is: temporomandibular joints and the masticatory
muscles. It has, however, been stressed that there
• Either a jiggling force, which is produced by
is no such thing as an intrinsically bad occlusal
multi-directional displacement of a tooth in
contact, because the effect is a product of not
alternating buccolingual or mesiodistal
only the‘quality’ of the contact or contacts but
598 BRITISH DENTAL JOURNAL, VOLUME 191, NO. 11, DECEMBER 8 2001
PRACTICE
occlusion
Patient Date
First
examined
Periodontal status
Mobility CI 1 CI 1I CI III
Persistent discomfort
upon eating
Radiographic changes
Widening or
Discontinuity in Thickening of funneling of
lamina dura lamina dura periodontal ligmanent
also the frequency at which the contact or con- ment apparatus to withstand a less than ideal
tacts are made. Also, it is widely accepted that occlusion may be compromised by periodontal
some patients, at some times will have an articu- inflammation.
latory system which is compromised by other This leads to the second question:
factors which reduce their tolerance to a less than
ideal occlusion. Factors may range from a sys- Question 2
temic disease such as rheumatoid arthritis to the Should occlusal treatment be considered
debilitating effects of chronic long term stress. for the patient with compromised
On the tooth level an occlusion may or may periodontal attachment?
not be ideal for the attachment apparatus, and If it is accepted that increased occlusal forces
the same consideration must be given to the could result in a further loss of attachment for
frequency of occlusal contact, ie Does parafunc- teeth with an active inflammatory periodonti-
tion occur? In addition, the ability of the attach- tis, then it follows that a treatment plan aimed
BRITISH DENTAL JOURNAL, VOLUME 191, NO. 11, DECEMBER 8 2001 599
PRACTICE
occlusion
It follows, therefore, that even though
occlusal trauma is not a proven aetiological
factor in periodontal disease dentists as part of
their responsibility to help patients keep their
teeth for as long as possible in maximum
health, comfort and function must carry out a
thorough occlusal examination. Treatment
aimed at reducing occlusal forces so that they
fall within the adaptive capabilities of each
patient’s dental attachment apparatus will
benefit; particularly those with, or at future
risk, of periodontitis.
Technique
Examination:
Clinical diagnosis of trauma from occlusion
Fig. 3 UR 2 (12) has migrated
distally. Examination of the Increased tooth mobility is not always indica-
dynamic occlusal contacts of tive of trauma from occlusion. It is important,
this tooth indicate that the however, that hypermobility which does
marked wear facet fits closely occur as a result of trauma from occlusion is
against those of LR 2 and LR1
(42, 41) during a right lateral detected in patients with reduced periodontal
excursion of the mandible attachment. The reason for this is that trauma
from occlusion may accelerate further reduc-
tion in attachment in a patient with active
at preserving these teeth must address both periodontitis.
problems. This does not mean that trauma A clinical diagnosis of occlusal trauma can
from occlusion causes periodontitis; rather, it only be confirmed where progressive mobility
means that occlusal forces may exceed the can be identified through a series of repeated
‘resistance threshold’ of a compromised attach- measurements over an extended period. This
ment apparatus thereby exacerbating a pre- means that simple but reliable monitoring
existing periodontal lesion. While we know that needs to be undertaken. A simple monitoring
trauma from occlusion can have an effect on protocol is needed (Fig. 2).
the supporting tissues of the teeth, there is no The common clinical signs of occlusal trauma
evidence, at present, that trauma from occlu- are:
sion is an aetiological factor in human peri-
• Increasing tooth mobility and migration or
odontal disease.
drifting (Fig. 3)
• Fremitus
• Persistent discomfort on eating.
600 BRITISH DENTAL JOURNAL, VOLUME 191, NO. 11, DECEMBER 8 2001
PRACTICE
occlusion
Tooth mobility can be recorded using Miller’s
Photo: Periotest-Equip
Index:
I — up to 1 mm of movement in a horizontal
direction
II — greater than 1 mm of movement in a
horizontal direction
III — excessive horizontal movement and
vertical movement.
Fremitus
Fremitus is the movement of a tooth or teeth
subjected to functional occlusal forces, this
can be assessed by palpating the buccal aspect
of several teeth as the patient taps up and
down.
Periodontometers
A periodontometer was a research tool used in
the 1950s and 1960s to standardise the mea-
surement of even minor tooth displacement.
To date, this instrument has been used in a few
clinical studies and has limited practical use.
Periotest ®
Fig. 6 Initial examination of the
This device (Fig. 5) was produced in Germany UR 1 (11), in Fig. 6a, may
in the late 1980s to provide a more reliable suggest an occlusal cause of the
method for determining tooth mobility. It is drifting; however, as is shown in
designed to measure the reaction of the peri- figure 6b the reason is the
relationship with the lower lip
odontium to a defined percussion, delivered by
a tapping instrument. Again this is of limited
use in general dental practice.
BRITISH DENTAL JOURNAL, VOLUME 191, NO. 11, DECEMBER 8 2001 601
PRACTICE
occlusion
Equilibration
All these stages may be necessary
Study models
Successful Mock equilibration
mounted to CR on
stabilisation splint on duplicated
a semi-adjustable
therapy study models
articulator
eating this will have a direct influence upon • Whether the inflammatory periodontitis
treatment. The decision will need to be taken, in has been treated successfully. If there is an
consultation with the patient, whether to accept inflammatory periodontal process this
the discomfort, extract or splint. should be treated initially. Subsequently
when the periodontal condition is stable,
Treatment occlusal therapy may be necessary for some
(Occlusal considerations in the treatment of patients and could involve either occlusal
periodontitis) equilibration or splinting.
• The radiographic appearance of the peri-
Equilibration odontal support. Occlusal equilibration is
Occlusal equilibration is the modification of the considered an effective form of therapy for
occlusal contacts of teeth to produce a more teeth with increased mobility which has
ideal occlusion. developed together with an increase in the
width of the periodontal ligament (PDL).
Is there a need for occlusal equilibration in the Reducing the occlusal interference on a
periodontally compromised dentition? tooth with normal bone support will nor-
The literature does not give an answer to this malise the width and height of the PDL.
question. Some studies have shown occlusal Eliminating any occlusal interferences for a
therapy to be beneficial in the management of tooth which has a reduced bone height as a
periodontal disease, whilst others have failed to result of periodontal disease will result in
do so.7–9 Burgett et al. reported that occlusal bone formation and remodelling of the
adjustment to reduce tooth mobility before alveolus only to the pre-trauma level.
conventional periodontal treatment, leads to In contrast, if the hypermobile tooth has
probing attachment gain after such therapy.7 reduced bone height but normal periodontal
The current dental literature, however, suggests ligament width, then elimination of occlusal
that if occlusal adjustment is required it should trauma will not alter the mobility of the
be carried out after periodontal treatment. tooth. In this situation occlusal equilibra-
There is no evidence at the present time to tion is only indicated if the patient is com-
suggest that occlusal equilibration is an appro- plaining of loss of function or discomfort.
priate method for preventing the progression of
periodontitis. It would, however, be useful to Occlusal therapy in a periodontal treatment plan
know whether equilibration of a periodontally is established practice
compromised dentition is beneficial for the ‘The World Workshop of the American Acad-
long-term preservation and comfort of teeth, in emy of Periodontology’,13 issued some guide-
those patients who fail to achieve an excellent lines for situations when occlusal equilibration
level of plaque control. may be indicated:
• When there are occlusal contact relationships
Equilibrating mobile teeth
that cause trauma to the periodontium,
In a patient with mobile teeth, it may be necessary
joints, muscles or soft tissues
to temporarily stabilise those teeth before equili-
• When there are interferences that aggravate
bration is possible (Fig. 7a,b). If a tooth is mobile,
parafunction
it is very difficult if not impossible to effectively
• As an aid to splint therapy.
modify its shape with the aim of reducing the
occlusal forces acting upon it (equilibration). Splinting
When should teeth be splinted together in the
When to equilibrate (Fig. 8) patient with reduced periodontal support?
Whether occlusal equilibration is indicated will (Fig. 8)
depend upon: Also outlined13 were some indications for
602 BRITISH DENTAL JOURNAL, VOLUME 191, NO. 11, DECEMBER 8 2001
PRACTICE
occlusion
Normal bone
height
BRITISH DENTAL JOURNAL, VOLUME 191, NO. 11, DECEMBER 8 2001 603
PRACTICE
occlusion
1 Karolyi M. Beobachtungen uber
Pyorrhoea alveolaris. Ost-Unt Vjschr
Zahnheilk 1901; 17: 279.
2 Glickman I, Smulow J B. Alteration
Guidelines of good occlusal practice
in the pathway of gingival
inflammation into the underlying
tissues induced by excessive occlusal 1 The examination of the patient involves the teeth, periodontal tissues and
forces. J Periodontol 1962; 33: 8-13. articulatory system.
3 Waerhaug J. The infrabony pocket
and its relationship to trauma from
2 There is no such thing as an intrinsically bad occlusal contact, only an
occlusion and subgingival plaque. intolerable number of times to parafunction on it.
J Periodontol 1979; 50: 355-365. 3 The patient’s occlusion should be recorded, before any treatment is started.
4 Green M S, Levine D F. Occlusion
and the periodontium: A review and 4 Compare the patient’s occlusion against
rationale for treatment. J Calif Dent the benchmark of ideal occlusion.
Assoc 1996; 24: 19-27.
5 Jin L J, Cao C F. Clinical diagnosis of
5 A simple, two dimensional means of recording the patient's occlusion
trauma from occlusion and its before, during and after treatment is an aid to good occlusal practice.
relation with severity of 6 The conformative approach is the safest way of ensuring that the
periodontitis. J Clin Perio 1992; 19:
92-97. occlusion of a restoration does not have potentially harmful
6 Philstrom B L, Anderson K A, Aeppli consequences.
D, Shafter E M. Association between
signs of trauma from occlusion and
7 Ensuring that the occlusion conforms (to the patient’s
periodontitis. J Periodontol 1986; 57: pre-treatment state) is a product of examination, design,
1-6. execution and checking (EDEC)
7 Burgett F G, Ramford S T, Nissle RR,
Morrison E C, Charbeneau T D, 8 The ‘reorganised approach’ involves firstly the establishment
Caffesse R G. A randomised trial of of a ‘more ideal’ occlusion in the patient’s pretreatment teeth
occlusal adjustment in the treatment or provisional restorations; and then adhering to that design
of periodontitis patients. J Clin
Periodontol 1992; 19: 381-388. using the techniques of the ‘conformative approach’
8 Galler C, Selipsky H, Philips C, 9. An ‘ideal occlusion’ in removable prosthodontics is one
Amnons W F Jr. The effects of which reduced de-stabilising forces
splinting on tooth mobility. II. After
osseous surgery. J Clin Periodontol 10. The occlusal objective of orthodontic treatment is not clear,
1979; 6: 317-333. but a large discrepancy between centric occlusion and centric
9 Linde J, Nyman S. Clinical relation should not be an outcome of treatment
Periodontology and Implant Dentistry.
3rd Ed. Ch 23: Occlusal Therapy 11. An ‘orthodontic’ examination of the occlusion should include:
pp711-726 Copenhagen: the dynamic occlusion; and the jaw relationship in which the
Munksgaard, 1997. patient has centric occlusion
10 Svanberg G K, King G T, Gibbs C H.
Occlusal considerations in 12. The occlusion of periodontally compromised teeth should
periodontology. Periodontol 2000 be designed to reduce the forces to be within the adaptive
1995; 9: 106-117. capabilities of the damaged periodontia
11 Walton G, Heasman P. The role of
occlusion in periodontal disease.
Dent Update 1998; 25: 209-216.
12 Polson A M, Zander H A. The effect
of periodontal trauma upon
infrabony pockets. J Periodontol
1983; 54: 586-592.
13 Proceedings of the World Workshop in
Clinical Periodontics. Chicago.
Consensus report: Occlusal Trauma.
The American Academy of
Periodontology 1989: III-1/III-23.
604 BRITISH DENTAL JOURNAL, VOLUME 191, NO. 11, DECEMBER 8 2001
http://dentalbooks-drbassam.blogspot.com/ PRACTICE
occlusion
any of the factors governing the devel- then the equivilant molar in the fourth quad-
In this part, we will
discuss:
• Why occlusal
M oping occlusion have already been
covered in the section on orthodon-
tics, but there are specific instances in which the
rant should be extracted in order to keep the
development and drift symmetrical in each
quadrant.
considerations are dentist in general practice will be faced with
different in children decisions which could have an influence on the The ‘submerging E’
• How the adult occlusion of child patients. This section aims to The sight of a primary second molar that
occlusion can be present these situations and give guidelines, appears to be ‘submerging’ below the level of
influenced by which will help the reader make the most the occlusal plane of the adjacent teeth is not
the treatment of appropriate treatment decision for their indi- uncommon. Submergence is an inaccurate
common problems in vidual patients. term as it is the adjacent teeth which are erupt-
the child’s dentition ing normally, whilst the ankylosed primary
PROBLEMS AND CHOICES: molar is remaining static (Fig. 1 ).
The significance of the ‘submerging E’ lies
Premature loss of a tooth in the primary not just with the loss of occlusal contact with
dentition: the opposing teeth, but also the loss of contact,
If a primary tooth is lost prematurely, then con- interdentally, with the adjacent teeth, especially
sideration of an extra (balancing) extraction distally with the first permanent molar.3 Figure
will be necessary.1,2 This will be with a view to 2 shows that the first permanent molar has
preventing a shift of the midline or resultant tilted mesially, because of the loss of an effective
disruption of the developing occlusion. stabilising contact with the second primary
molar.
• If a primary incisor tooth is lost as a result of The issues, therefore, are:
1*GDP, 73 Buxton Rd, High Lane, caries or trauma this does not usually have Is there an effective contact with the opposing
Stockport SK6 8DR; P/T Lecturer in an effect on the developing occlusion. Space
Dental Practice, University Dental closure is not going to occur as primary
Hospital of Manchester, Higher incisor teeth usually become spaced prior to
Cambridge St., Manchester M15 6FH;
2Honorary Fellow, University Dental exfoliation.
Hospital of Manchester, Higher • If a primary canine tooth needs to be
Cambridge St., Manchester M15 6FH extracted, then the contralateral primary
3Senior Lecturer/Honorary Consultant,
Unit of Paediatric Dentistry,
canine should also be extracted, in many
Department of Dental Medicine and cases, to prevent an untoward midline shift.
Surgery, University Dental Hospital of Only if the anterior dentition is spaced
Manchester, Higher Cambridge Street, should unilateral loss be accepted.
Manchester M15 6FH
*Correspondence to : Stephen Davies, • If a single primary molar tooth is unsavable
73 Buxton Rd, High Lane, Stockport and the other teeth have a good prognosis Fig. 1 A case where the degree of submergence is
SK6 8DR there is no need to extract other molar teeth. minor; there is no tilting of the first permanent
email: stephen.j.davies@man.ac.uk molar. This requires no treatment because the
REFEREED PAPER
If primary first and/or primary second primary tooth is usually eventually shed, as long
© British Dental Journal as the permanent sucessor is present
2001; 191: 655–659 molars in three quadrants have to be extracted
BRITISH DENTAL JOURNAL, VOLUME 191, NO. 12, DECEMBER 22 2001 655
PRACTICE
occlusion
ion should be sought so that an early decision
can be taken as to whether:
• To encourage eruption of the permanent
successor
• To leave the permanent canine unerupted
• To arrange surgical removal of the unerupted
permanent canine
656 BRITISH DENTAL JOURNAL, VOLUME 191, NO. 12, DECEMBER 22 2001
PRACTICE
occlusion
• Presence of all other unerupted permanent
teeth , especially second premolars
• Development of the second permanent
molars.
If an assessment reveals that sponta-
neous space closure is desirable, timing
of extractions is crucial. When the
bifurcation of the second molars is vis-
ible (just formed) on radiographs and
the upper lateral incisor teeth have
erupted, this is the best time to extract
the first molars to ensure maximum
spontaneous alignment. This is because
if this stage of development has been
reached the lower second molars will
move bodily mesially during eruption Fig. 3 Panoramic radiograph: the lower first permanent molars are carious and there
is premolar crowding
rather than tilt mesially, which is what
happens if extraction are left until
later.6
• Hypoplasia of unerupted premolar teeth Fig. 4a–c Extraction of first permanent molars.
If the premolar teeth are of poor quality
and there is potential crowding then the
After carrying out the examination,
balance swings towards conservation of the difficult decision of whether to advise
the first permanent molars. The deci- extraction of one or more of the first
sion on which teeth to extract is delayed permanent molars must be taken.
until the premolars can be assessed
upon their eruption.
The flowcharts in Figures 4 a, b, and c
• Crowding in the premolar region are offered as guidelines, when
If the first molars are so carious or considering extraction of first
hypoplastic as to warrant extraction, permanent molars in patients in the
then often the second primary molars
may well have previously been age range of 8 to 10 years.
extracted. This may have allowed the
first molars to have drifted mesially
resulting in a lack of space for the
unerupted second premolar. In this sit- Fig. 4a One carious first permanent molar
uation, extraction of the permanent
first molars is certainly indicated as it
removes a tooth with a poor prognosis
and also relieves premolar crowding Is there crowding?
(Fig. 3). No Yes
Factors influencing decision to extract
• Number of other carious teeth Restore
• Extent of caries (extract if there is pulpal
involvement) Is the motivation high?
• Oral heath status Yes No
• Motivation towards dental health
• Presence of malocclusion
• Motivation towards orthodontic treatment
Restore Extract
But consider extraction If upper If lower
later instead of sound
premolar
‘Restoration
at all costs’
may not extract extract
always be only upper upper and lower
the best option on that side
BRITISH DENTAL JOURNAL, VOLUME 191, NO. 12, DECEMBER 22 2001 657
PRACTICE
occlusion
Trauma in the permanent dentition
The general dental practitioner frequently
Fig. 4b Two carious first permanent molars encounters a patient presenting with a frac-
tured or avulsed upper incisor tooth. The
management of the clinical condition of the
fractured, or avulsed, tooth is the subject of
Is there crowding? many publications and the practical and
No Yes definitive treatment plan can be sought else-
where. What we aim to address in this section
is the effect of the treatment plan upon the
Restore occlusion.
Is there crowding?
No Yes
Restore
Fig. 5 Anterior view of space maintainer showing
Is the motivation high? mesial and distal stops
Yes No
Restore Extract
But consider extraction All four molars
later instead of sound
premolar
658 BRITISH DENTAL JOURNAL, VOLUME 191, NO. 12, DECEMBER 22 2001
PRACTICE
occlusion
the teeth either side of the gap, at the level Missing permanent teeth 1 Andlaw R J, Rock W P. A manual of
paediatric dentistry. 4th edn.
of the gingival papillae. If the tooth frac- In the case of the congenital absence of perma- Edinburgh: Churchill Livingstone,
tures off this appliance, then the stops nent teeth, the general practitioner’s responsi- 1996.
will maintain the space until the appli- bility is early detection. The responsibility, now, 2 Ball I A. Balancing the extraction of
ance can be repaired (Fig. 5, 6). for treatment planning lies with the paediatric primary teeth: a review. Int J Paed
Dent 1993; 4: 176-185.
dentist and specialist orthodontist because with 3 Shaw W C. Orthodontic and occlusal
Fracture of permanent upper incisor timely referral many of the potential problems management. Oxford: Wright, 1993.
• The most common fracture involves the of hypodontia can be avoided. 4 British Orthodontic Society. Young
practitioners guide to orthodontics.
mesial or distal aspects of the crown. These
British Orthodontic Society, 1998.
teeth can be relatively easily and quickly
a 5 Blinkhorn A S, Mackie I C. Treatment
restored by acid etch composite tips so pre- planning for paedodontic patients.
serving the contact point with the adjacent London: Quintessence, 1992
6 Mackie I C, Blinkhorn A S, Davies P J
tooth. The restoration of the contact with the H. The extraction of permanent first
adjacent tooth is very important. In the case molars during the mixed dentition
illustrated (Fig. 7 a,b) the failure to do so has period — a guide to treatment
resulted not only in a mesial and labial tilting planning. J Paed Dent 1989; 5: 85-92.
of the unrestored tooth, but also in a loss of
palatal width. As a consequence of this inac-
tion the restoration of this young patient’s
dentition represents a major orthodontic and
restorative challenge. Fig. 7a Despite the poor
• Fortunately a horizontal fracture of the b aesthetics and marginal
crown of a tooth is less common. It is impor- adaptation, the fracture of UR1
tant that the crown of a tooth so fractured is (11) has been restored. The
lack of restoration of UL1 (21)
restored to its original size and shape to pre- has allowed mesial and labial
vent occlusal problems developing. The tilting
results of this type of injury to the tooth
remaining unrestored are over-eruption of Fig. 7b The tilting of UL1 (21)
the opposing tooth, and less obviously the has resulted in narrowing of the
damaged tooth may tilt buccally because space for the crown of the
tooth
there is reduced lip control.
1 The examination of the patient involves the teeth, periodontal tissues and articulatory system.
2 There is no such thing as an intrinsically bad occlusal contact, only an intolerable number of times to
parafunction on it.
3 The patient’s occlusion should be recorded, before any treatment is started.
4 Compare the patient’s occlusion against the benchmark of ideal occlusion.
5 A simple, two dimensional means of recording the patient's occlusion before, during and after
treatment is an aid to good occlusal practice.
6 The conformative approach is the safest way of ensuring that the occlusion of a restoration does
not have potentially harmful consequences.
7 Ensuring that the occlusion conforms (to the patient’s pre-treatment state) is a product of examination,
design, execution and checking (EDEC)
8 The ‘reorganised approach’ involves firstly the establishment of a ‘more ideal’ occlusion in the patient’s
pretreatment teeth or provisional restorations; and then adhering to that design using the techniques of
the ‘conformative approach’
9. An ‘ideal occlusion’ in removable prosthodontics is one which reduced de-stabilising forces
10. The occlusal objective of orthodontic treatment is not clear, but a large discrepancy between
centric occlusion and centric relation should not be an outcome of treatment
11. An ‘orthodontic’ examination of the occlusion should include: the dynamic occlusion; and the
jaw relationship in which the patient has centric occlusion
12. The occlusion of periodontally compromised teeth should be designed to reduce the forces to be
within the adaptive capabilities of the damaged periodontia
13. Good occlusal practice in children is determined by the needs of the developing occlusion,
consequentially ‘restoration at all costs’ may not be the best policy.
BRITISH DENTAL JOURNAL, VOLUME 191, NO. 12, DECEMBER 22 2001 659