This document discusses late lower incisor crowding. It begins with definitions and an introduction noting crowding is common and multifactorial. Etiology includes mandibular growth rotations, occlusal forces, mesial drift, soft tissue changes, periodontal changes, diet, tooth size and shape, and possibly third molar eruption. A literature review discusses studies that both support and refute an association between third molars and crowding. Management depends on severity and can include monitoring, removable appliances, or fixed appliances with possible extractions. Prophylactic third molar removal is not recommended to prevent crowding. Multifactorial etiology and a bonded retainer are emphasized for treatment and retention.

1. LATE LOWER INCISOR
CROWDING
Seminar
Dept of Orthodontics UiTM
30/3/2015
Group C

2. Outlines
 Definition
 Introduction
 Etiology
 Third molar and late lower labial
crowding: literature review
 Management of late lower labial
crowding
 Conclusion
 References

3. Definition
 Late crowding of the mandibular incisors
beginning between the ages of 17 and
mid-twenties and progressing
throughout adult life
(Sakuda et al 1976)

4. Introduction
 Crowding of the mandibular incisors is one of the most common
problems encountered in the permanent dentition and is one of
the most likely things to relapse after orthodontic treatment.
(Cobourne’s Handbook of orthodontics)
 because of its high prevalence, late mandibular incisor crowding is
considered a normal part of the aging process.
(American Association of Orthodontics 1999)
 Approximately two-thirds of adolescents with good alignment and
“normal” occlusions will develop incisor irregularity by early
adulthood
(sinclair et al 1983)
 The aetiology of late lower incisor crowding is recognized as being
multifactorial
(Laura mitchell’s Introduction to Orthodontics,)

5. Etiology of late lower incisor crowding
1. Mandibular growth rotations;
 When mandibular growth outpaces maxillary growth,
forces from the maxillary arch and labial soft tissues
cause uprighting, or lingual movement of lower incisors
 This results in crowding by forcing the incisors to occupy
a smaller arch perimeter.
American Association of Orthodontic,
Orthodontic Dialog vol 11 no. 1, Spring

6. Cont..
2. Anterior component of occlusal forces
 can either be physiological or pathological (high
bite, parafuntional habits)
3. Physiologic mesial drift
 the teeth are gradually displaced mesially
and causing the crowding of lower incisors
4. Soft tissue maturation
 hyoid bone and tongue descend with
age, relative to surrounding structures,
causing imbalance between lip and tongue
and resulting in crowding
( Bench et al,. 1952 )

7. Cont..
5. Degenerative periodontal changes allowing
teeth to drift under light pressures
6. Change in diet and lack of interproximal
wear
 Diet influence the teeth interproximal wear, less
interproximal wear lead to more crowding.
7. Tooth size and shape
8. Third molar eruption?

8. LITERATURE REVIEWS
“Mandibular third molar and
late lower incisor crowding”

9. Studies relating 3rd molar to late lower
incisor crowding
 Bergstorm and Jensen (1961)
 presence of 3rd molar may influence the development of dental arch,
but they do not justify on the prophylactic removal of 3rd molars.
 Vego (1962)
 greater degree of crowding in the group presence of mandibular 3rd
molar.
 He suggested there are multiple factors involve the crowding- not
only the third molars
 Shanley (1962)
 Study on comparison in bilaterally impacted, erupted and
congenitally absent 3rd molar.
 He found no significant differences and concluded that 3rd molar
have little influence only.
 Selmer-Olsen’s (1970)
 Suggested people with unilateral congenital absence of third molar
will have less crowding on quadrant without 3rd molar, and crowding
on quadrant with presence of 3rd molar.

10. Cont..
 Schwarze (1975)
 He compared between group with 3rd molar germectomy and non-
extraction group.
 Significant lower incisor crowding in non-extraction group.
 Lindqvist and Thilander (1982)
 They found 0.16mm less crowding in group with 3rd molar
removal.
 They concluded that extraction could be recommended in severe
crowding malocclusion.
 Richardson ME (1989)
 Study was done on subjects with intact lower arches and bilateral
3rd molars presence.
 Showed increase in crowding as 4mm and only 16% did not show
the crowding.
 She considered 3rd molars as one of the causes of lower late
incisors crowding.

11. Cont..
 Southard et. al. (1991)
 Their hypothesis was that the mesial force exerted by unerupted
3rd molar increases the lower late incisor crowding.
 However they can’t detect the pressure, and concluded that
pressure from 3rd molar is insignificant
 Vander Schoot et. al (1997)
 Study done on subjects with 3rd molar erupted, impacted,
extracted and congenitally missing.
 They concluded that no relationship exists between crowding and
the presence or absence of 3rd molars.
 Harradine et al (1998)
 They done study to evaluate the effect of extraction 3rd molars and
late lower incisor crowding.
 They concluded that the removal of 3rd molar to reduce or prevent
late crowding could not be justified.

12. Cont..
 Gavazzi M et al (2014)
 193 orthodontists and oral surgeon were
asked to express their opinion on the
relation between upper and lower third
molar eruption and anterior crowding.
 The majority of both groups of clinicians do
not consider their preventive extraction
useful in order to prevent anterior
crowding.

13. Management of Late lower incisor
crowding
 The decision to treat mandibular incisor
crowding depends largely on the severity of
crowding and the complexity of other
components of the patient’s malocclusion
 In the presence of significant malocclusion,
incisor crowding is best managed as part of a
comprehensive orthodontic treatment plan.
 However, if a patient has Class I dental
relationships and good maxillary alignment,
limited treatment may be appropriate.
(American Association of Orthodontic, Orthodontic Dialog vol 11 no. 1, Spring

14. Cont..
 Accept and monitor
 Esthetically acceptable, able to maintain
good oral hygiene.
 Removable appliance
 limited to tipping and rotational movement
 in cases of mild crowding where space can
be required by enamel stripping
Clinical Problem Solving in Orthodontics and Paediatric De
By Declan Millett

15. Cont..
 Fixed appliances
 In cases of moderate to severe crowding
where bodily movement is required.
 Extraction is usually required to provide
space.
 Extraction of lower incisors can be done in
treating late lower incisor crowding but it is
not advisable as it can compromised the
esthetics.

16. retainer
 Preferably using the fixed bonded
retainer

17. Conclusion
 The causes of late lower labial crowding is multifactorial.
 Removal of symptomless lower third molars has been
advocated in the past in order to prevent lower labial
segment crowding.
 It is likely that third molar have an effect upon mandibular
arch crowding but this effect is one component of a
multifactorial condition and prophylactic third molar
extraction is unlikely to remove the problem
(Richardson, 2002).
 The National Institute for Health and Clinical Excellence
(NICE) in the UK has recommended that prophylactic removal
of pathology- free impacted third molars, which includes
removal to prevent occlusal changes in the incisor regions, be
discontinued. Handbook of Orthodontics by by Martyn T
Cobourne

18. References
 An introduction to orthodontics 4th edition by laura mitchell
 Handbook of Orthodontics by by Martyn T Cobourne
 Clinical Problem Solving in Orthodontics and Paediatric Dentistry By
Declan Millett
 Sakuda M., Kuroda Y
., Wad K., Matsumoto M. Changes in crowding of
teeth during adolescence and their relation to the growth of the
facial skeleton. Trans Eur Orthod Soc. 1976:93–104.
 Sinclair, P.M., Little, R.M.:Maturation of untreated normalocclusions.
Am. J. Orthod. Dentofac.Orthop. 1983;83:114-123.
 Sumitra, Arundi : Third Molars and Late Mandibular Incisor Crowding
– A Review, J Ind Orthod Soc 2005
 American Association of Orthodontic, Orthodontic Dialog vol 11 no. 1,
Spring 1999
 Sumitra, Arundi : Third Molars and Late Mandibular Incisor Crowding
– A Review, J Ind Orthod Soc 2005