Download Mini-implant Aided Alignment of Horizontally Impacted Lower

Mini-implant Aided Alignment of Horizontally Impacted
Lower Second Molar A Case Report
Salwa Jeragh Alhaddad – BChD, MFDS, RCSI, MSc Ortho, M’Orth RCSEng
Ameri Dental Hospital – Kuwait – [email protected]
Mashael Alnasser – BA, BDSc, MFDS, MGDS, RCSI
Ameri Dental Hospital – Kuwait
Manar Alnouri – BDS, MFDS, MGDS, RCS
Ameri Dental Hospital – Kuwait
ABSTRACT
Aim: To present a contemporary method of aligning horizontally impacted teeth.
Case presentation: A medically fit 17 year old female patient, presented to the orthodontic clinic with a horizontally
impacted lower left second molar in an otherwise Class I occlusion with no aesthetic concerns.
A two year history of the lower left third molar extraction in an attempt to normalize the lower left second molar’s path
of eruption was reported by the patient with no evident success.
Intervention: The patient was treated with a sectional fixed appliance on the lower left quadrant supported by
a mini-implant temporary anchorage device in the left maxillary tuberosity region for inter-maxillary elastic wear.
Successful alignment of the lower left second molar was achieved in a period of eleven months.
Conclusion: The incorporation of mini-implants into orthodontic mechanics, has provided new limits to contemporary
orthodontics, enabling orthodontists to align teeth that were previously considered common extraction candidates.
KEYWORDS
Mini-implants, Uprighting terminal molar, Horizontal impactions, Sectional fixed appliance.
INTRODUCTION
Horizontal impaction of the terminal molar tooth is a
frequent problem orthodontists face in their daily practice,
with the lower third molar being the tooth most frequently
affected.1 Treatment lines ranged from accepting the
problem and placing the patient under periodic reviews,
to surgical extraction of the impacted tooth.
To date orthodontic correction and alignment has been
reserved for milder cases of impaction with sufficient
eruption.
During the past decade, however, the spreading use of
temporary anchorage devices (TADS/ Mini-implants) has
enabled orthodontists to expand their limits in terms of
force magnitude and vectors necessary to correct more
challenging cases.2
CLINICAL PRESENTATION
A medically fit and healthy 17 year old female
patient was referred to my clinic from the oral surgery
department requesting a second opinion prior to
the extraction of her horizontally impacted lower left
permanent second molar.
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History taking revealed the extraction of the lower
left third molar two years previously in an attempt to
normalize the path of eruption of the lower left second
molar, with no evident success.
Extra Oral Examination
Patient presented with a Class I skeletal pattern, average
vertical proportions, no signs of skeletal or soft tissue
asymmetry and healthy tempomandibular joints.
Intra Oral Examination
Patient presented with a Class I incisal, canine and molar
relations, with average overjet, overbite (Fig. 1A) and
minimal signs of crowding (Fig. 1B).
Upper and lower midlines were coincident (Fig. 1A).
The lower left second molar was partially erupted and
horizontally impacted (Fig. 1B), in an otherwise normal
occlusion.
(Radiograph 1) Initial Orthopantomogram of the dentition
(Fig. 1) A: Initial anterior view of the dentition. B: Initial lower
occlusal view of the dentition
SPECIAL TESTS
Radiographic examination of the patient confirmed the
presence of complete dentition except the lower left third
molar. The lower left second molar was horizontally
impacted with its occlusal surface paralleling the distal
root surface of the lower left first molar (Radiograph 1).
Both upper third molars and the lower right third molar
were unerupted, with the latter being horizontally
impacted (Radiograph 1).
Cephalometric analysis confirmed the clinical findings of
a Class I skeletal pattern with an element of bimaxillary
proclination, rendered normal according to the patient’s
racial group.3
(Radiograph 2) Initial lateral cephalogram
TREATMENT OPTIONS
Due to the partial eruption of the lower left second
molar, it was explained to the patient that any treatment
option that accepts the impaction would involve a
significant risk of carious attack on both the lower left
first and second molars. The option of extracting the
second molar, however, shortens the dental arch and
limits the occlusal table to the first molar rendering
the upper left second and third molar non-functional.
Therefore the use of a sectional fixed appliance
mechanics in the lower left quadrant supported with
a temporary anchorage device in the left maxillary
tuborosiy region for inter-maxillary elastic, was proposed
to the patient to upright the lower left second molar.
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Initial Periapical radiograph
of the impacted lower left
second molar
2 months progress periapical
radiograph of the impacted
lower left second molar
Near end of treatment
Periapical radiograph of the
impacted lower left second
molar
(Fig. 3) A: Post treatment lower occlusal view of the dentition.
B: Post treatment anterior view of the dentition in occlusion.
C: Post treatment left view of the dentition in occlusion
Aims & Objectives of Treatment
• Maintaining the lower left second molar.
• Distal uprighting and extrusion of the lower left second
molar.
• Preventing the supra-eruption of the upper left second
molar.
Treatment Plan
A sectional fixed appliance on the lower left first and
second premolars and first molar was bonded with the
aid of a temporary anchorage device at the left maxillary
tuberosity region for intermaxillary elastic wear.
Initial distalization of the lower left second molar using
NiTi push coil was carried out.
This was followed by molar distal uprighting and
extrusion with an intermaxillary elastic applied in a
disto-vertical direction to the mini-implant, temporary
anchorage device at the left maxillary tuborosity.
(Fig. 2) A: 9 months progress of the lower dentition. B: 9
months progress of the left dentition in occlusion
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Treatment Progress
Sectional fixed appliance mechanics were used to aid initial
distalization and uprighting of the lower left second molar.
This step was later supported with the use of a mini-implant,
temporary anchorage device (of 8mm length and 1.4mm
diameter by Ormco), placed in the left maxillary tuberosity
region to provide a disto-vertical force vector as the patient
wears an intermaxillary elastic (3/16” of 3.5oz by Unitek).
The retention of TADs is mechanical in nature, which permits
immediate or early loading and is, therefore, dependent on
the length and diameter of the mini-implant used.5
The advantage of increasing the length and diameter must,
however, be weighed against the increased risk of root
damage to the neighboring teeth during placement.
Chen et al. had found that; mini-implants of 1.2mm
diameter and 8mm length offered a 90% success rate
with minimal damage to the roots of neighboring teeth.5
This side effect can further be minimized by careful
planning and radiographic examination of the target site.6
The alignment of the horizontally impacted terminal
molar places a great challenge on classic treatment
mechanics with limited force directions and magnitude.
The use of mini-implant temporary anchorage devices
has not only enabled orthodontists to align unfavorable
impactions, but has also reduced the need for extra-oral
anchorage devices (headgears) and the extractions of
teeth that were previously considered with unfavorable
path of eruption.
(Fig. 4) A: First year review, of the lower dentition. B: First
year review, of the anteriors in occlusion. C: First year review,
of the left dentition in occlusion
Nine months into treatment, the lower left second molar
was sufficiently erupted (Fig. 2) and a bondable tube
attachment (by American Orthodontics) was fixed to
finalize the alignment of the tooth and detail the occlusion
through the progression in archwire sequence (Fig. 3).
The first annual review revealed stable results (Fig. 4).
DISCUSSION
Temporary anchorage devices can be placed using a
simple surgical technique that can be performed by
orthodontists, to gain a wider range of force in terms of
magnitude and vectors.4
CONCLUSION
The introduction of temporary anchorage devices has
provided new limits to the practice of orthodontics
enabling the alignment of teeth that were previously
considered common extraction candidates.
REFERENCES
1. O Breik, D Grubor. The incidence of mandibular third molar
impactions in different skeletal face types, Aust Dent J.
2008;53(4):320-4.
2. Kanomi R. Mini-implant for orthodontic anchorage, J ClinOrthod.
1997;31:763-7.
3. Al-Azemi R and Artun J. Posteroanterior cephalometric norms for an
adolescent Kuwaiti population, Eur J Orthod. 2012;34(3):312-7.
4. Adriano G. Crismani,aMichael H. Bertl,bAlesˇ G. Cˇ elar,aHansPeter Bantleon,aand Charles J. Burstonec. Mini-screws in
orthodontic treatment: Review andanalysis of published clinical
trials, AJODO. 2010;137(1):108-13.
5. Chen CH, Chang CS, Hsieh CH, Tseng YC, Shen YS, Huang YI et
al. The use of mincroimplants in orthodontic anchorage, J Oral
MaxillofacSurg. 2006;64:1209-13.
6. Herman R, Cope JB. Miniscrew-implants: IMTEC mini-ortho
implants. SeminOrthod. 2005;11:32-9.
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