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Definition of contemporary orthodontics : The dental specialty
and practice of preventing and correcting irregularities of the teeth,
as by the use of braces (i.e , TMJ dysfunction , psychological disorders
, Prosthodontic- implant interactions , orthognathic surgery )
Definition of adjunctive orthodontics : Tooth movement to carried
out to facilitate other dental procedures necessary to control disease,
restore. function, or enhance appearance ( i.e ,Uprighting posterior
teeth , crossbite correction , extrusion , intrusion , alignment of
anterior teeth , forced eruption, treating diastema closure and space
redistribution)
Typically, adjunctive treatment will involve any or all of the
several procedures :
1. Repositioning of teeth : that have drifted after extractions or
bone loss so as to facilitate the placement of removable or fixed
partial dentures or even implants.
2. Forced eruption : of badly broken teeth to expose sound tooth
structure on which to place crowns
3. Alignment of anterior teeth : to allow more esthetic
restorations or successful splinting .
4. Correction of cross bites : if these compromise jaw function
Aims of adjunctive orthodontics :
1. Facilitate restorative treatment by positioning the teeth so :
a. More ideal and conservations methods can be used.
b. Optimal esthetics can be achieved with bonding or porcelain
restorations.
Relationship between Orthodontics and
Fixed Prosthodontics
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2. Improve periodontal health by eliminating plaque harboring
areas and improving the alveolar ridge contour adjacent to teeth .
3. Establish favorable crown to root ratios and position the teeth so
that occlusal forces are transmitted along the long axis of teeth .
Characteristic of therapy :
Adjunctive orthodontics implies limited orthodontic goals :
1. Appliances are required only a portion of the dental arch (i.e)
partial fixed appliance
2. Treatment should be completed within 6 months
3. Orthodontic treatment of TMD shouldn’t be considered
adjunctive
Diagnosis and treatment planning consideration :
1. Planning for adjunctive treatment requires 2 steps :
a. Collecting an adequate data base
b. Developing a comprehensive but clearly stated list of
patient’s problems
2. Records include IOPA and panoramic x-rays
3. Pre- treatment cephalogram not required
4. Dental casts made from fully extended impression covering
the contour of supporting alveolar bone is required
Possible tooth movement in adjunctive treatment :
1. Mesial or distal movements of specific crowns or roots
2. Correction of axial inclination of drifted teeth
3. Correction of buccolingual position of certain teeth
4. Corrections of rotations
Notes : Intrusion of teeth is avoided as an adjunctive procedure
because of the technical difficulties involved and possibility of
periodontal complications and excessively extruded teeth are
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treated by reduction of crown height which improves the
crown/root ratio .
Introduction :
The combination of orthodontic and prosthodontic treatment
resulted in a more favorable outcome than prosthodontic treatment
alone. When planning prosthodontic treatment, the dentist should
embrace a dynamic view of tooth position and determine whether
restorative treatment can be enhanced by tooth movement.
Improved tooth position can eliminate potentially pathologic
occlusion and create a healthier periodontal environment that is
easier to maintain. In addition, it permits the dentist to place
restorations that often require less natural tooth reduction during
preparation, and that are more esthetic, functional, stable, and
durable. This valuable treatment option facilitates tooth preparation,
path of insertion , optimum oral hygiene, and a better pontic and
abutment design, while occlusal forces can be directed against the
long axes of the teeth for a more predictable prognosis. The major
indication for adjunctive orthodontic treatment is to facilitate and
improve the dental restorative conditions at the level of the arch
(space management), roots (parallel abutments) and bone height
(periodontal considerations) for the placement of well-adapted and
contoured restorations, crowns or implants.
The restorative dentist will occasionally be confronted with
complex treatment planning decisions resulting from the
following (Miller, 1995):
1. Unesthetic position of the anterior dentition caused by
overcrowding or excessive spacing
2. Poor position of posterior abutments due to malocclusion
3. Supra eruption and occlusal plane discrepancies
4. Mesial drift into edentulous areas
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5. Collapse of the occlusal vertical dimension due to loss of
posterior teeth.
Questionable Abutment Situations in Fixed Partial denture
prosthesis :
1. Extensively damaged teeth
2. Periodontaly weakened teeth
3. Pier abutments
4. Tilted abutments
5. Cantilever fixed partial dentures
6. Short abutments.
We’ll talk about abutment situation N.O 3 and 4 in more details
Pier abutments : A pier (intermediate) abutment is a natural tooth
located between terminal abutments that serve to support a fixed or
removable dental prosthesis. Rigid connectors (e.g., solder joints)
between pontics and retainers are the preferred way of fabricating
most fixed partial dentures. However, a completely rigid restoration
is not indicated for all situations requiring a fixed prosthesis.
Physiologic tooth movement, arch position of the abutments and a
disparity in the retentive capacity of the retainers can make a rigid
5-unit fixed partial denture a less than ideal plan of treatment.
Studies in periodontometry have shown that the faciolingual
movement ranges from 56 to 108 μm and intrusion is 28 μm. Teeth
in different segments of the arch move in different directions
(because of the curvature of the arch). The faciolingual movement of
an anterior tooth occurs at a considerable angle to the faciolingual
movement of a molar.
Use of the non-rigid connector is restricted to a short span fixed
partial denture replacing one tooth. Prostheses with non-rigid
connectors should not be used if prospective abutment teeth exhibit
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significant mobility. Nearly 98% of posterior teeth tilt mesialy when
subjected to occlusal forces. If the keyway of the connector is placed
on the distal side of the pier abutment, mesial movement seats the
key into the keyway more solidly. Placement of the keyway on the
mesial side, however, causes the key to be unseated during its mesial
movements.
Tilted molar abutments : A common problem that occurs with some
frequency is the mandibular molar abutment that has tilted mesialy
into the space formerly occupied by the lost natural teeth anterior to
it . It is impossible to prepare the abutment teeth for a fixed partial
denture along the long axes of the respective teeth and achieve a
common path of insertion. There is a further complication if the third
molar is present.
Ways of dealing with a tilted posterior tooth :
1. Uprighting of the tilted molar with orthodontic treatment
2. Fixed partial denture using a proximal half-crown as a retainer
on a tilted molar abutment
3. Fixed partial denture using a telescopic crown and coping as a
retainer on a tilted molar abutment
4. A non-rigid connector on the distal aspect of the molar retainer
compensates for the inclination of the tilted molar.
Optimization of restorative conditions : Uncompensated old
extractions alter adjacent and antagonist teeth position as well as
their bone level: the contiguous teeth will tilt toward the vacant space
creating an angular bony defect in addition to the loss of the available
space. In order to address these cited problems, an orthodontic
treatment is needed to eliminate the bony defect by uprighting the
tipped tooth
[1]
. Therefore, an amelioration of the tooth axis is often
mandatory for a better realization of the prosthetic crown and a
better distribution of occlusal forces
[2]
. Orthodontics is essential to
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