DR MOHAMMED ASLAM V OLAVARA

1. Controversies
in
Orthodontics
Presented by :
DR MOHAMMED ASLAM V
DEPARTMENT OF ORTHODONTICS

2. contents
• Introduction
• Growth predicition
• etiology of malocclusion
– a] Genetic V/s environmental factors.
– b] Role of nasal obstruction and tongue thrust
• Extraction vs non-extraction
• Orthopedics in orthodontics
• Pre-adjusted edgewise appliance
• Tmd disorders
• Root resorption after orthodontic treatment
• Third molars
• Adult orthodontics
• Retention

3. introduction
Controversy – A prolonged argument/ dispute especially when
conducted publicly.
The orthodontic profession hs evolved its set of values with the
tacit approval of most clinicians, teachers and researchers.
A considerable variety of opinion concerning what constitutes
good orthodontics has characterized the profession since
beginning. No consensus exists today, and some opinions are even
mutually exclusive.

4. Even the science of orthodontics has been oriented toward
seeking explanations and validation of therapeutic methods rather
than toward establishing a basis for objectively assessing the
quality or utility of our clinical performance. Thus its more
“Opinion –based” rather than “evidence – based”. Such science
can neither validate the superiority of a technique nor help to
make rational choices among alternatives

5. In time, for most clinicians, practice becomes routine,
standardized and decreasingly introspective. Hence clinical
experience & common sense assume a more commanding role in
decision making.
It is tempting to follow techniques advocated because “they
work” or atleast are “claimed” to work and be the “latest and
best”. Also it is alluring to adopt innovations simply because they
are new and thus seem to represent the state of art.

6. Orthodontics is unique among dental specialities in that deals
with normal biologic variations rather than pathologies
Orthodontic treatment predominantly selective in terms of needs
and inevitably subjective in terms of criteria used to assess
prevalence, severity, treatment success and what constitutes
optimum care.
Hence controversies are common and similar to some analogous
issues in medicine.

7. Growth prediction
One of the hallmark of science is the reliability with which the
outcome of future can be predicted.
We find the idea of predicting treatment outcome
psychologically comforting.
The ability to predict is useful only to the extend to which it
enables us to either to understand and modify the general
processes of development or to control our patients response to
therapeutic inclination.

8. Different craniofacial phenomena are predictable with different
levels of precision and different craniofacial phenomena must
be known at different levels for predictions to be useful.
To a considerable degree we can predict:
1. The head and face of a preadolescent children will continue to
change in size and shape until the age of 20 yrs.
2. The growth of jaws and face from mixed dentition period to
maturity will be greater in inferior direction than in anterior
direction.
3. Prominence of dentition within the face will decrease during
maturation.
4. Class II malocclusion identified after eruption of molars to
occlusal contact ill rarley,if ever,resolve spontaneosly.

9. 5. Crossbites in permanent dentition will rarely, if ever resolve
spontaneously.
6. Anterior crowding & rotations visible after the permanent
incisors have erupted will rarely resolve spontaneously.
7. Permanent teeth tend to migrate mesially into extraction space
due to premature loss of teeth.
8. Unopposed teeth tend to supraerupt.
9. Angle of mandible tend to close with respect to cranium from
mixed dentition period to maturity.
10. Therapeutic intervention that alter occlusal intercuspation will
tend to open mandibular plane angle.

10. 11. Mandibular incisors that have been displaced or proclined
anteriorly during treatment will tend to relapse in post retention
period.
12. Arches in which buccal segments have been expanded will tend
to relapse to pretreatment widths.
13. Intercanine widths that has been increased returns to their
pretreatment widths.
14. Attempts to retract canine by anchoring them to posterior teeth
tend to result in advancement of posterior teeth.

11. On the other hand we cannot predict:
1. The magnitude and timing of spontaneous growth remodeling at
specific sites n head, face & jaws.
2. The impact of therapeutic intervention upon the expression of
each individual inherent growth potential.
3. Amt of correction that can be achieved at a specific anatomic
loci.
4. The amt of post therapeutic relapse that can occur.
.

12. etiology of malocclusion
Genetic V/s environmental
factors
The relative influence of genetics and environmental factors in
the etiology of malocclusion had been a matter of discussion,
debate and controversy in Orthodontic literature.
Each malocclusion occupies its own distinctive slot in the
genetic/environmental spectrum.
While the phenotype is inevitably the result of both factors, there
is irrefutable evidence for a single genetic influence in many
dental and occlusal variables

13. Malocclusion could be produced by inherited characteristics in two
possible ways:
1] Inherited disproportion between the size of teeth and that of the
jaws-producing crowding/spacing.
2] Inherited disproportion between size/shape of upper and lower
jaws –producing improper occlusal relations.

14. There is considerable anthropological evidence that population
groups that are genetically homogenous tend to have a normal
occlusion e.g.: Melanesians of Philippine islands; this is the result
of genetic isolation and uniformity.
Since everyone in the group carries the same genetic information
for tooth and jaw size, there would be no possibility of a child
inheriting discordant characteristics.
Edward Angle and his contemporaries concluded that
malocclusion was the disease of civilization. They blamed this on
the improper function of jaws under degenerate modern
conditions.

15. The earlier part of the 20th century saw the
development of classical Mendelian genetics. The new
view was that malocclusion is primarily the result of
inherited dento-facial disproportions.
The seventies and eighties saw a revival and a swing
back to the earlier concept that jaw function is related to
malocclusion.

16. A number of familial and twin studies in the latter part of
the century by workers like Lundstrom (1984), Corrucini
(1980), Potter (1986), Bolton and Brush, Harris and
Johnson (1991) gave a more balanced view showing that
there is no single explanation for malocclusion in terms
of function, heredity or environment, but is a result of a
complex interplay of these elements.

17. Respiratory pattern as an etiologic factor for
malocclusions:
• Respiration - Primary determinant of jaw and tongue posture.
• Altered respiratory pattern  change posture of head, jaw, and
tongue  alters equilibrium  jaw growth and tooth position
affected.
• Effects - Increased face height, supra-erupted posteriors, open
bite, mandibular rotates downward and backward narrow
maxillary arch.

18. Ballard and Gwynne-Evans (58)
Lip incompetence not necessarily associated with mouth breathing.
Nose breathers, who have a lip - apart posture, usually have post seal
with tongue against soft palate as an adaptive mechanism.
Harvold, Tomer and Vargevik (81):
Total nasal obstruction in monkeys, for a prolonged time led to the
development of malocclusion.

19. Katherine & Vig
• Primates do not have same naso respiratory mechanism as
humans.
• Total nasal obstruction  not seen in humans.
“Relationship between mouth breathing, altered posture
and deviation of malocclusion is not so clear cut as the
theoretical outcome of shifting to oral respiration might
appear at first glance”.

20. Wood side, Linder-Aronson, Lundstrom (91):
Maxillary and mandibular growth in 38 children, 5 years after
adenoidectomy for severe nasopharyngeal obstruction.
20% did not show shift in breathing.
Concluded that change from mouth-open to mouth-closed breathing:
Greater mandibular growth expressed at chin in both sexes:
3.8mm in males (P<0.001)
2.5mm in girls (P<0.01)
Greater facial growth expressed at midface, only in males.
No change in maxillary growth direction.

21. Contemporary view:
2 opposing principles, leaving large gray area between them:
– Total nasal obstruction likely to alter pattern of growth
and lead to malocclusion. – High percentage of oral
respiratory is over-represented in long-face population.
– Majority of individuals with long-face deformity have
no evidence of nasal obstruction because some other
etiological factor as principal cause.
Mouth breathing – contribute to development of orthodontic
problems but as frequent etiologic agent is questionable.

22. Tongue-thrust as etiologic factor:
Definition: placement of tongue-tip forward between incisors during
swallowing.
Profitt (72) –the term tongue-thrust is a misnomer, since it implies
that the tongue is forcefully thrust forward. Laboratory studies
indicate that individuals who place the tongue tip forward when
they swallow do not have more tongue force against teeth than
those who keep tongue tip back- in fact, tongue force may be
lower.

23. The mature/ adult swallow pattern appears in some normal
children as early as age 3, but not present in majority
until about age 6 & is never achieved in 10-15% of a
typical population. Some times children & adults who
place their tongue between anterior teeth are spoken of
as having a retained infantile swallow- this is clearly
incorrect, since only brain damaged children retain a
truly infantile swallow in which posterior part of the
tongue has little or no role. (Proffit)

24. This is not to say that tongue has no role in the etiology of
open bite. From the “equilibrium theory” point of view:
Light but sustained pressure by tongue against the teeth
would be expected to have significant effect. Tongue-
trust swallowing simply has too short a duration to have
an impact on tooth position.

25. Current view point:
Tongue –thrust is primarily seen in 2 circumstances:
– In young children with normal occlusion – transitional
stage in normal physiologic maturation.
– In individuals of any age with displaced anterior teeth
– adaptive.
Hence it is more a “Result” than a “cause”

26. However tongue posture is more important.
 Light pressure for more duration  change in tooth position.
“If the position from which tongue movement starts is different from
normal, so that pattern of resting pressure is different, it can have
an effect on teeth, whereas if posture is normal, tongue-thrust
swallow has no clinical significance”.

27. Extraction vs non-extraction
“To extract or not to extract” was one of the early debates
that clouded orthodontic world ever since its
beginning.
2 main reasons for extraction:
• Provide space to align remaining teeth – crowding.
• Allow teeth to move – skeletal Class II / skeletal Class
III camouflaged.

28. History:
Late 1800 – early 1920’s:
Late 1800 saw a casual attitude towards extraction.
1902  Edward H. Angle gave his line of reasoning
towards development of his treatment philosophy
based on the ideas of Rousseau &Wolff

29. These influenced Angle to propose 2 key concepts:
• Skeletal growth  Influenced readily by external
forces.
• Proper function of dentition would be the key for
maintaining teeth in their correct position.
For him “relapse” meant – adequate occlusion not reached.
“If correct occlusion is produced  result is stable, if result
not stable it was the fault of orthodontist and not the
theory”.

30. Angle’s dogma:
• Every patient could be treatment with expansion of
dental arches and rubber bands.
• Extraction not necessary for stability or esthetics.
Calvin Case argued that although the arches could always
be expanded so that the teeth could be placed in
alignment, neither esthetics nor stability would be
satisfactory in the long term for many patients

31. The controversy culminated in a widely publicized debate
between Angle’s student Dewey and Case in the dental
literature of 1920’s.
Angle’s followers won – extraction disappeared between
World War I & II.

32. From 1930’s – 1970’s
Charles Tweed re-treated with extraction; the relapse cases
previously treated with non-extraction methodology,
& found occlusion to be much more stable.
Extraction reintroduced widely  late 1940’s
Raymond Begg popularized “Begg” appliance for
extraction treatment.

33. Between 1970-1990’s:
Saw the revival of non-extraction philosophy.
Reasons?
Premolar extraction does not guarantee stability of tooth
alignment.
Little, Wallen and Riedel – 1981 AJO.
MC Reynolds and Little – 1991 Angle Orthod.
Argument :
“If result not stable either way, why sacrifice teeth at all”.
v/s.
“If extraction cases are unstable, non-extraction would be worse”.

34. – Changing views of esthetics – fuller and more
prominent lips,than the orthodontic standards of
1950s & 1960s.
– Change from banding to bonding and introduction
of functional appliances eliminated the need for
band space,made it easier to expand arches – border
line case generally treated better without extraction.

35. – Premolar extraction causes distalization of mandible
posteriorly, displacement of condyle resulted in
perforation of articular disc  TMD. – Witzig and
Spahl (1980)
– Both Tweed’s and Begg’s rational for extraction, lost
some of their validity.

36. The contemporary respective:
Majority of patients can be treated without extraction, but
by no means all.
Extraction can be undertaken to compensate for:
• Crowding.
• Incisor protrusion.
• Camouflage skeletal discrepancies.&
• For surgery.

37. Treatment modalities converting borderline cases into non –
extraction cases:
Early intervention:
• Use of ‘E’ space.
• Proximal stripping of primary teeth.
• Space regainers with space maintainers.
• Arch expansion.
• Use of functional appliances.
• Molar distalization.
• Bonded attachments rather than banded ones.

38. Adult:
• Molar distalization.
• Inter-proximal reduction.
• Arch expansion.
• Surgery for skeletal discrepancies

39. Orthopedics in orthodontics
‘Orthopedic effect’ in orthodontics can be defined as:
“Change in the position of bones in the skull in relation to
each other induced by therapy”. – Daterloo.
This change in amount and direction and growth should be
permanent in nature. According to Issacson, orthopedic
appliance, provide a new muscular and functional
environment for the facial bones that encourages growth
changes of either the mandible or the maxilla.

40. In dentofacial orthopedics, orthodontists attempt to influence growth
by applying an external force, generally for two or three years.
Almost all orthopedic appliances act intermittently.
The growth of the jaws of growing child might be influenced if the
therapy starts at very young age and if it continuous until growth
has stopped.
However, we cannot expect patient to cooperate for such a long time.
Hence the main question remains whether orthodontists are able to
alter growth within a limited time period (2 or 3 years) in a
complex craniofacial skeleton that is growing and remodelling.

41. Controversies started with some clinicians who believe that the basic
bone biology is such that one cannot alter the bone growth beyond
its genetic potential except by chemical or surgical intervention.
But this hypotheses was rejected as many clinicians found that
functional appliances could alter the craniofacial skeleton in a
positive direction.
If at all failures occurred the blame was put on poor patient co-
operation, misdiagnosis, from the beginning or were not reported
at all.

42. The effect on mandibular growth is the most controversial issue.
Certainly remodelling of alveolar bone and basal bone occurs
from excessive force.
The dominance of role of genetic pattern was seen in the long
run.
It was seen that condylar growth is a compensatory filling in of
bone in response to vertical growth at the dentoalveolar process
complex & a stimulus was required for a considerable postnatal
development if the mandible had to be elongated & had to be
renewed to keep the increased growth rate present.

43. According to basic biology once cells are stimulated, their receptors
can be overwhelmed & their ability to respond depends either on
rest, an inhibitory signal, or entrance of a new cell population that
can be stimulated.
Therefore an intermittent stimulus of short frequencies makes the
most physiologic sense.
Whether it produces the best clinical response is subject to
speculation and testing.

44. Contoversies in Pre-adjusted
edgewise appliance
Torque in Base or Face:
Straight wire appliance developed from the concept, described by
Andrews in 1972, that the attainment of ideal orthodontic goals
could be related to certain relationships of naturally occuring good
occlusions which were judged not to require any orthodontic
intervention.
Using the mid-point of the long axis of the clinical crown(LA) as the
reference, it was intended that the appliance design should allow a
completely flat rectangular archwire, filling the slot, to be placed
at the completion of the treatment.

45. In this way, all the LA point of the individual teeth in each arch
would come to lie in the so called Andrews plane. this necessitated
the incorporation of labiolingual, tip and torque adjustments
within each bracket, specific to the particular tooth for which it
was designed.
It is possible to incorporate torque either into the bracket base or on
the bracket face, but to fulfill strict straight wire design the torque
has to be in the base of bracket.

46. When torque is in base:
The bracket stem is parallel to and is bisected by the Andrews plane
which thus passes through the base point & also through the
centre of the bracket slot.
Here the tooth surface has been represented as flat surface at an
angle to Andrews plane.

47. When torque is in face:
The bracket stem is perpendicular to the tooth surface and inclined at
an angle to the Andrews plane.
A slot cut into the bracket face will give the same value of torque,
will be parallel to the Andrews plane, but its long axis will be
displaced vetrically and will not intercept the LA point

48. It is seen that brackets with torque in face do not fulfill the strict
criteria laid down for the straight wire appliance, as the slot axis
will no longer intercept the base point and LA point.
If all the base points & LA points do lie in the Andrews plane, there
will be vertical discrepencies between the bracket slots.
The undesirable effects of having torque in face could be
summarized as:
• In-buit error in final vertical tooth positioning
• Interference with free archwire sliding.
Despite all the limitations commercially available systems do not
incorporate torque in base.

49. Tmd disorders
Functional disturbances of the masticatory system have been
identified by a variety of terms.
In 1934 James Costen described a group of symptoms that centered
on the ear &TMJ.
In 1959 Shore introduced the term Temporomandibular joint
dysfunction syndrome.
Later came the term Functional temporomandibular joint disorders
coined by Ash & Ramfjord.
Since the symptoms are not always isolated to the TMJ, Bell
suggested the term temporomandibular diorders(TMD).

50. In an article written by Dr James Costen in 1934, he suggested that
changes in the dental condition were responsible for various ear
symptoms.
In late 1930s and through 1940s , common therapies like bite-raising
appliances were used.
Later in the 1950s the use of such appliances were questioned.
Scientific investigations suggested that the occlusal condition could
influence masticatory muscle function.
Occlusion and later emotional stresses were accepted as major causes
through the 1960-70.

51. It was not until the 1980s that the profession began to recognize fully
and appreciate the complexity of TMDs.
This complexity now has the profession striving to find its proper
role in the management of TMDs and orofacial pain.

52. Occlusion And Temporomandibular Disorders:
Occlusion is cited as one of the major etiological factors within
the acknowledged multifactorial origin of TMD’s.
The assumed strong association between TMD and Occlusion has
been a major reason that the diagnosis and treatment has remained
within the purview of dentistry.

53. Despite agreement among TMD experts that occlusion actually only
has relatively small role in the etiologically diverse and
multifactorial origins of TMD, the influence of occlusion
continuous to be greatly over rated in comparison by practicing
dentists/ specialists.
Seligman and Pullinger reported 2 comprehensive reviews on
relation of occlusion to TMD.- One considering morphologic
occlusal relationships and other, functional occlusal relationships.

54. However, 4 occlusal factors were mainly seen in TMD patients and
not in healthy population.
• Presence of anterior skeletal openbite.
• RCP-ICP slides > 2mm.
• Overjets > 4mm
• 5 or more missing and unreplaced posterior teeth.
Pullinger and coworkers concluded that many occlusal parameters
that traditionally were believed to be influential contribute only in
minor amount to the change in risk in the multiple factor analysis
used in their study. They reported that although the relative odds
for disease were elevated with several occlusal variables, clear
definition of disease groups were evident only in selective
extreme ranges and involved only in few subjects. Thus, they
concluded that occlussion cannot be considered the most
important factor in definition of TMD.

55. Orthodontic treatment and TMJ disorders :
It had been suggested that patients who received orthodontic
treatment have a higher ratio of TMD disorders than average.
However in a study by Rendell, Norton, and Gay 1992 a
relationship between either the onset of TMJ pain and dysfunction
and the course of orthodontic treatment or the change in TMJ pain
and dysfunction and the course of orthodontic treatment could not
be established.

56. The prevalence of temporomandibular (TM) disorders and the
status of the functional occlusion in former orthodontic patients
many years after treatment were evaluated in two independent
clinical studies Sadowsky and Polson in 1984.
The findings for these two studies are similar and suggest that
orthodontic treatment performed during adolescence does not
generally increase or decrease the risk of developing TM disorders
in later life.

57. Extraction causes TMD disorders:
First premolar extractions are considered by many to be an
etiologic factor in TMJ disorders. It is believed that extraction of
premolars permits the posterior teeth to move forward resulting in
a decrease in the vertical dimension of occlusion. The mandible is
then allowed to overclose, and the muscles of mastication become
foreshortened. As a result, TMJ problems are likely to occur.

58. Another theory that has been proposed is that first premolar
extractions lead to overretraction of the anterior teeth, particularly
the maxillary anteriors . This overretraction of anterior teeth is
thought to displace the mandible and the condyles posteriorly
Staggers 1994:
Evaluation of the treatment results of the extraction and
nonextraction cases showed that the vertical changes occurring
after the extraction of first premolars were not different than those
occurring in the nonextraction cases. This study does not support
the theory that first premolar extractions reduce the vertical
dimension of occlusion, and thus predispose extraction patients to
TMJ disorders.

59. Beattie, Paquette, and Johnston 1994
In long-term evaluation of the functional status of both the head
and the neck musculature and the temporomandibular joints of
treated Class II malocclusions showed no significant differences
between the extraction and nonextraction samples. The popular
notion that "premolar extraction causes TMJ disorders does not
hold true.

60. Orthodontic treatment and posterior condylar
displacement:
View point articles  variety of traditional ortho procedures
(premolar extraction, extraoral traction, retraction of maxillary
anterior teeth) cause TMD signs/symptoms by producing distal
displacement of condyle.

61. Gianelly, Cozzani, and Boffa 1991
There is little or no risk of condylar retroposition resulting from
maxillary premolar extraction treatment
Luecke and Johnston 1992
Condylar position with Xn of maxillary first premolars
70% - forward mandibular displacement and slight opening rotation
of mandible.
30% Remainder – distal movement of condyle.
Also said incisal movement – essentially unrelated to condylar
displacement.

62. Parafunction:
Bruxism and clenching – cited as etiological factors but
similarly like occlusal interferences, this is endemic in general
population.
Seligman and Pullinger – increasing evidence – parafunction
not associated with chronic occlusal factors.
Okerson – Reversible rather than non reversible treatment –
prevent/minimize harmful effects of this activity.

63. Summary:
• Signs and symptoms of TMD occur in healthy individuals.
• Signs and symptoms of TMD increase with age,
particularly with adolescence. Thus, TMD that originates
during treatment may not be related to treatment.
• Orthodontic treatment performed during adolescence
generally does not increase or decrease the odds of
developing TMD later in life.
• Extraction of teeth as a part of orthodontic treatment does
not increase the risk of TMD.

64. • Although a stable occlusion is a reasonable orthodontic
treatment goal, not achieving a specific ideal occlusion
does not result in TMD signs/symptoms.
• No method of TMJ disorders prevention has been
demonstrated.
• When more severe TMD signs and symptoms are present,
simple treatment can alleviate them in most patients.

65. Root resorption after
orthodontic treatment
• Bates 1856 – 1st to discuss root resorption of permanent teeth.
• Ottolengui 1914 – related root resorption to orthodontic treatment.
• 1927  Root resorption was subject of major concern to
orthodontic field.

66. Etiology:
By Phillips, Reitan and Shafer et al
• Physiologic tooth movement.
• Adjacent impacted tooth pressure.
• Periapical or periodontal inflammation.
• Tooth implantation / replantation.
• Continuous occlusal trauma.
• Tumors/cysts.

67. • Metabolic / systemic disturbances.
• Hyperparathyroidism.
• Hypophosphatemia.
• Paget’s disease.
• Hypothyroidism.
• Hypo/hyperpituitarism.
• Local functional / behavioral problems.
• Nail –biting.
• Tongue thrust with open bite.
• Dilacerations.
• Orthodontic treatment – Fixed > Removable
Edgewise > Begg
• Individual susceptibility.

68. Andresen  3 types of root resorption:
» Surface resorption – self-limiting process, usually involving
small outlining areas followed by spontaneous repair.
» Inflammatory resorption – initial root resorption has reached
dentinal tubules.
» Replacement resorption – bone replaces resorbed tooth
material  ankylosis.

69. Controversies – factors influencing root
resorption:
Nutrition:
• Marshall – malnutrition causes root resorption.
• Beck – root resorption in animals deprived of Ca and Vit. D.
• Linge and Linge – nutritional imbalance not a major factor.

70. Gender:
Massler – no correlation between gender and root resorption.
Newman – more in females
Spurrier et al (1990) – males more than females.
Alveolar bone density:
Becks, Reitan, Tager-Root resorption > dense bone
Wainwright – Density affects tooth movement rate, but no relation to
extent of root resorption.

71. Specific tooth vulnerability:
Ketcham,Steadman-Maxillary teeth more vulnerable
Reitan - Maxillary incisors most prone
Hemley,Sjolien-Mandibular incisors > maxillary incisors
Most frequently affected according to severity maxillary lateral >
maxillary central > mandibular incisors > distal root of 6 >
mandibular 2nd premolar > maxillary 2nd premolar.

72. Fixed V/s Removable:
Linge and Linge – fixed > removable.
Stuteville – removable > fixed  Jiggling forces more harmful
Begg V/s edgewise:
Begg < Edge wise
Malmgren et al (82) – root resorption higher in traumatized tooth
(maxillary incisors) when intruded by Begg technique compared
with E.W. technique (48%: 43%).

73. Continuous V/s intermittent forces:
Reitan, Oppenheim,Dougherly-Intermittent forces allows resorbed
areas to heal and prevents further resorption.
Hall – Intermittent forces causes jiggling hence more detrimental.
Extent of tooth movement:
Dermaut, Hollender, Sharpe-Root resorption and extent of root
movement.
Philips,Dermaut-No correlation

74. Occlusal trauma:
Doughery – Occlusal forces on poorly aligned teeth can cause root
resorption.
Newman – no correlation.

75. Third molars
The role that mandibular third molars play in lower
anterior crowding has provoked much speculation in
the dental literature.
The removal versus the preservation of third molars
became the subject of contention in dental circles. The
differing views ranged between extremes, and can be
expressed in two different statements:

76. – Third molars should be removed even on a
prophylactic basis, because they are frequently
associated with future orthodontic and periodontal
complications as well as other pathologic conditions.
– There is no scientific evidence of a cause and effect
relationship between the presence of third molars and
orthodontic and periodontal problems

77. Justification for 3rd molar extraction.
Evolutionary
Most often absent/ malformed.
Little room for a full complement of teeth.
Prophylactic:
Will become impacted (poorly angulated).
In adulthood-operative and postoperative problems – hemorrhage,
pain, swelling, osteitis and trismus likelihood of nerve damage
increases.

78. Pathologic:
Cysts, tumors, resorption of 2nd molar roots, caries,
pericoronitis and other infectious processes.
Orthodontic:
Post treatment crowding – relapse / late lower arch crowding.
Mandibular orthognathism surgery.

79. Relationship between 3rd molars and incisor crowding:
Untreated normals:
Bishara et al (89 and 96):
Evaluated changes in lower incisor between 12 and 25 years and
again at 45 years – findings indicated :
• Increase in tooth size arch length discrepancy with age –
consistent decrease in arch length.
• Average changes 2.7mm in males; 3.5mm in females. These
changes were attributed to a consistent decrease in arch
length that occurred with age.
Similar findings by Lundstrom (68) and Sinclair and Little (83):

80. Orthodontic treatment patients:
Fastlicht (70) found that in orthodontically treated subject-
11% had 3rd molars, but 86% had crowding.
Little et al (81) observed that 90% of extraction cases that
were well treated orthodontically ended up with an
unacceptable lower incisor crowding.

81. Studies relating 3rd molar to crowding of dentition:
• Bergstrom and Jensen (61) concluded:
– More crowding in the quadrant with 3rd molar
present than in the quadrant with the third molar
missing.
– Mesial displacement of lateral dental segments on
the side with 3rd molar present in the mandibular
arch not in the maxillary arch.
– The unilateral presence of a third molar did not have
an effect on the midline.

82. Schwarze (75):
In his studies found significantly greater forward movement of
first molars associated with increased lower arch crowding in
the non extraction of 3rd
molars.
Lindquist and Thilander (82):
Extracted third molar unilaterally in 52 patients and found
more stable space conditions (less increase in crowding) on the
extraction side compared with the control side in 70% of cases.

83. Belfast third molar study – Richarson M.E. (82-87).
Produce further evidence “Pressure from behind” theory:
According this theory that late lower arch crowding is caused by
pressure from the back of the arch.
Whether this pressure results from:
• Dev. 3rd molar.
• Physiologic mesial movement / drift.
• Anterior component of force derived from forces of occlusion
on mesially inclined teeth.
Is not clear.

84. Another school of thought is (Graber, Woodside, Selmer-
Olsen):
“In absence of 3rd molar, the dentition has room to settle
distally under anterior pressures caused by late growth or
soft tissue changes”.

85. Retrospective studies:
Kaplan (74): Presence of 3rd molar does not produce a greater
degree of lower anterior crowding or rotational relapse after
cessation of retention.
Ades et al (90):Majority of cases have incisal crowding, but no
correlation with 3rd molars.
Lifshitz (82) :In his studies concluded that there is a significant
decrease in arch length and a significant increase in
crowding, but there were no significant difference between
the groups that did or did not have premolar extractions or
whether third molars were present or missing.

86. Prospective studies:
Lindquist and Thilander (82):Unable to predict which patients
benefit from prophylactic extraction.
Southhard (91) et al measured proximal contact tightness between
the mandibular teeth in cases with bilaterally unerrupted third
molars. Surgical removal of 3rd molar – no significant effect on
contact tightness.
Pirttiniccni et al (94) evaluated the effect of removal of impacted
third molars on 24 individuals. They found that extraction of 3rd
molar allowed for slight distal drift of 2nd molar but no significant
change in incisal area.

87. Morphologic factors that can influence space available
for 3rd molar:
Bjork et al (56): examined 243 cases to estimate the relationship
between various cephalometric parameters and the space
available for mandibular third molars they identified three
skeletal factors that may influence third molar impaction:
– Vertical direction of condylar growth as indicated by
mandibular base – ramus angle.
– Decreased mandibular length – Cd-Pog.
– Backward – directed eruption of mandibular dentition
as determined by degree of alveolar inclination.
Capelli (91) added two more factors :
– Retarded maturation of 3rd molars.
– Greater mesial crown inclinations of 3rd molars crowns

88. Current views on removal of 3rd molars:
According to the National Institution of Dental Research (79) and
American Association of OMFS (93).
When and what condition – extraction of 3rd molar advised.
• Lower incisor crowding – multifactorial etiology.
– Tooth size, shape and relationships.
– Decrease in intercanine width.
– Retrusion of incisors.
– Growth changes.
• If adequate room is available – donot extract.

89. • Orthodontic treatment – distalization of molars – if causes
impaction extract.
• Post-operative pain, swelling, infection etc. decreased if patients
are young and roots 2/3rd deviation.
• If extraction is indicated – early extraction beneficial.
• Present predictive technique not completely accepted hence
enucleation at 7-9 years not valid.
• Inform patients about possible complications of extraction pain,
swelling, trismus, nerve damage etc.

90. Adult orthodontics
During the last decade the number of adults seeking
orthodontic treatment has increased significantly. In
addition epidemiologic studies have shown that more
than 75% of adults older than 40 years of age have
periodontal disease.

91. Because of physiologic differences between adolescent
and adult patients, there may well be differences in the
way malocclusions are corrected . Since adults do not
experience any substantive growth during treatment,
combined with physiologic bone differences, this would
be a reasonable hypothesis.

92. Bone remodeling in adulthood:
After skeletal maturity at approximately the age of 20 years, the
amount of cortical bone in many different bones has been reported
to decrease as a normal accompaniment of the aging process.
Epker et al have documented a progressive thinning of cortical
bone after adulthood is attained, stemming from enlargement of
the marrow cavity.
Liu et al had assessed alveolar bone & observed a significant
decrease in pore volume with increasing age along with a decrease
in lacunar-canalicular pore diameter and an increase in density.

93. Periodontal changes:
In the growing child, the tooth-supporting tissues are in a state
of proliferation. Within the periodontal ligament and in marrow
spaces surrounding the alveolus, large numbers of connective
tissue cells are actively involved in alveolar growth and
remodeling.
Reitan in his study concluded that there is a measurable delay in
bone formation in the adult that is not observed in the child.
Graber points out that older persons are more prone to root
resorption, apparently because of the penetration of the cementoid
layer and the inability of the cells in this area, with their reduced
vitality to deposit new cementoid and protect the resorbing root
surface.

94. Chasens listed the following clinical situation where orthodontic
treatment should be avoided:
• Uncontrolled infection & inflammation
• Lack of retention for stabilization of teeth in their new position
• Inadequate space into which teeth can be moved
• Movement of teeth against occlusal trauma
• Movement of teeth in which periodontal health, function or
esthetics will not improve.
• Movement of teeth against inadequate anchorage
• Movement of teeth into unfavorable environment
• Lack of patient motivation & co-operation
• Patients with systemic problems

95. Although clinical studies have documented slight but
statistically significant periodontal connective tissue loss
among adolescent patients who have undergone fixed
orthodontic treatment, there have been few studies
reporting periodontal status among periodontically
healthy adults undergoing fixed orthodontic treatment
and the effect on periodontal bone support in adults with
advanced loss of periodontal support.

96. Boyd, Leggott, Qui 1989
In their study have indicated that during the course of fixed
orthodontic treatment:
• 1. Tooth movement in patients with a reduced but healthy
periodontium does not result in significant further loss of
attachment.
• 2. Tooth loss for periodontal reasons may occur in adults with
severely periodontally compromised teeth that have pocket depths
> 6 mm and/or advanced furcation involvements.

97. Vast majority of limitations claimed to be related to the
biomechanical systems used.
Biologic basis for tooth movement is the same in
adults and in growing children, but special consideration
need to be given to dental and periodontal status.
With regard to intrusion and extrusion of teeth in these
pts, both can be done but should be at constant but low
force levels and under absolute 3 dimensional control.

98. Retention
Retention is one of the controversies of modern
orthodontics, with uncertainty being the only certainty.
Angle stated that "the problem involved in retention is
so great as to test the utmost skill of the most competent
orthodontist, often being greater than the difficulties
being encountered in the treatment of the ease up to this
point."

99. Reidel attempted to rationalize the problem and
summarized his findings in three statements:
1. Teeth moved through bone by orthodontic appliances
often have a tendency to return to their former positions;
2. Arch form, particularly mandibular arch form, cannot be
permanently altered by appliance therapy;
3. Bone and adjacent tissues must be allowed time to
reorganize after treatment.

100. Kaplan 1988 in his study of different retention procedures has noted
that:
1. There are very few cases requiring minimum or no retaining
appliances and these would include:
a. Blocked out canines in Class I extraction cases with no incisor
crowding
b. Class I anterior and/or posterior crossbites with very steep cusps
and no anterior crowding
c. Class II cases slightly over treated with headgear to restrict
maxillary growth with sufficient arch length indicated by
mandibular anterior spacing and absolutely no mandibular incisor
rotations
d. The above-described cases should be seen on a scheduled basis
during the post treatment adolescent period to check possible
spacing or unfavorable growth changes or TMJ symptoms.

101. 2. Routine cases, extraction or nonextraction, should have retaining
appliances— fixed or removable.
a. At least until the destiny of the third molar teeth is determined
[or]
b. Until the growth process has slowed in late teens and early
twenties [and]
c. Afterward at the option of the patient
3. Cases that will need indefinite retention
a. Class II, Division 2 Angle deep bite cases
b. Arch expansion treatment for esthetic demands
c. Patients with uncontrolled muscular or tongue habits
d. Again the orthodontist should be most emphatic about this need.

102. 4. Cases that require operative procedures with indefinite retention
a. Treatment limitations such as tooth size discrepancies (that is,
larger maxillary teeth) may result in increased overbite or super
Class I.
b. Reversely, larger mandibular teeth will result in end-to-end
incisor relationships, maxillary spacing, or buccal end-on
occlusion.
c. Stripping or reproximation of oversized teeth and esthetic
bonding of malshaped or undersized teeth may help resolve this
problem.
d. A very vertical incisal relationship, which for any reason cannot
be corrected, will lead to deepening overbite unless retained.

103. 5. Cases requiring special construction and/or renewal of
removable retaining appliances or acrylic on the labial
bows
a. Posttreatment adolescent palatal changes
b. Late mandibular growth spurt and Tweed type C
growers
c. To maintain torque and overbite correction

104. Researchers have concluded that those cases that will
relapse cannot be predicted and that indefinite retention
is necessary if the finished result of active orthodontic
treatment is to be maintained.
Many appliance types have been used for the retention
of post treatment tooth position.
There is no agreement in the literature of a uniform
system of retention, and the clinical orthodontist, in
consultation with each patient, must determine the
appropriate retention regime for each case.

105. Thank youThank you