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\begin{document}

\title{A rare case of bilateral double incisors; early orthodontic management}



\author[1]{Soghra Yassaei}%
\author[1]{Mohadeseh Sharifi}%
\author[2]{Zahra Ebrahiminik}%
\affil[1]{Shahid Sadoughi  University of Medical Sciences and Health Services}%
\affil[2]{Aja University of Medical Sciences}%


\vspace{-1em}



  
  \date{May 22, 2024}


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\selectlanguage{english}
\begin{abstract}
Early improvement of smile esthetic is critical in patients with
severely malformed front teeth particularly when it affects the
patient's confidence. As illustrated in this report, correction of
midline by moving a fused central incisor across the midpalatal suture
was successfully performed to make an acceptable esthetic smile.%
\end{abstract}%



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\textbf{Introduction:}

Double tooth is a general word commonly used to describe either fusion
or gemination \textsuperscript{1}. The literature showed prevalence
estimates for bilateral double teeth ranging from 0.01\% to 0.04\% in
the primary dentition, and 0.05\% in the permanent dentition.
Differential diagnosis between these two anomalies can be challenging,
however tooth count is always the first step \textsuperscript{2}. In
gemination tooth count is normal while in fusion the number of teeth is
one fewer unless it happens between a supernumerary tooth and a normal
one \textsuperscript{3, 4}.

These anomalies could lead to higher caries potential, malocclusion,
changes in the dental arch shape, periodontal disease, hyper
/hypodontia, and poorer esthetics. Treatment options include restorative
treatment (35\%), hemisection (33\%), extraction (15\%) and no
intervention (17\%) based on violaine's report \textsuperscript{5}.
Orthodontic treatment has been reported to be a main or alternative
option in 57\% of the cases with double teeth anomaly\textsuperscript{5,
6}.

Animal studies \textsuperscript{7} and case
reports\textsuperscript{8-10} have shown that movement of the teeth
across the midpalatal suture (MPS) is biologically possible however it
always offers a unique challenge for the orthodontists. The main
considerations are root resorption and frenum
inflammations\textsuperscript{9}. Jason pin in 2011 represented a case
of bilateral gemination in which they extracted the right incisor and
moved the left one 3 mm across the suture to correct the
midline\textsuperscript{10} . In their case the geminated tooth had
smaller widths compared to a normal one\textsuperscript{10}. Garib
(2012) also reported a case that the right incisor moved through the
suture to replace the absent contralateral tooth \textsuperscript{8}. In
both cases frenectomy has been done to decrease the inflammation of
stretched frenum, also, to decrease the chance of relapse. However no
major root resorption was reported by any of those studies. In this
study a rare case of moving a bi-rooted fused central incisor across the
MPS is presented.

\textbf{Case presentation}

A 10-year-old male patient presented to the orthodontic department of
Shahid Sadoughi University of Medical Sciences with the main complaint
of enlarged front teeth. The patient was the first of 3 siblings of
parents with no history of consanguinity. The patient appeared normal
and healthy with no reported history of orofacial trauma.

2.1. Diagnosis

On examination, the maxillary right (\# 11) and left (\# 21) central
incisors had increased mesiodistal widths with slight notching presented
in the incisal region extending through the labial cervical third. Both
incisors were within the arch form with no evidence of any caries. The
remaining teeth were of normal size and shape and the total number of
teeth was normal (Figure1).

Radiographic evaluations (Figure 2) showed that \#21 had a single root
and a common pulp chamber while \#11 had two distinct diverging roots
and their pulp chambers were individualized. The diagnosis was made to
be bilateral double teeth which \# 21 was an incomplete gemination and
\# 11 was a fusion between the incisor and a supernumerary tooth.

Lateral cephologram analysis (Figure 3) showed skeletal class I and
slight tendency to the vertical growth pattern. Dental cast (Figure 4)
analysis showed severe space deficiency in both arches. (12 mm in upper
arch and 11 mm in lower arch)

2.2. Treatment objectives

Treatment objectives were to increase the patient confidence by
restoring smile aesthetic, also to establish a class one occlusion, an
ideal overjet/overbite and maintain the facial profile proportions.

Treatment plan was to reduce the front dental mass by extraction of \#21
and mesializing \#11 to correct the midline. Also comprehensive
orthodontic treatment with four first premolar extractions was
anticipated for relieving the severe crowding.

Treatment alternatives

Alternative treatment plans include extraction of two anterior double
incisors and implant placement, or reduction of the incisor's widths by
splitting/hemisection and improvement of the esthetic by ceramic crowns.
These options would be opened only after the patient's skeletal
maturation. Moreover, surgical, endodontic and prosthetic procedures
were needed for those options. The patient preferred the less aggressive
procedure therefore ext of \#21 and mesialization of \#11 was the chosen
plan. The patient and his family granted approval for the publication of
the treatment records.

\emph{\textbf{Treatment progress}}

Due to the young age of the patient, emphasis on the oral hygiene
instruction was always a priority of the visiting sessions. At the
beginning, ext of \#21 was ordered (Figure 5) and it was planned to
consider \#11 as two central incisors (readily existing in the form of a
single macrodontic, fused tooth).

One week after the extraction of \#21, bracket bonding of maxillary
teeth (including the primary canines and molars) was performed (0.028 \selectlanguage{ngerman}×
0.022-in slot size bracket, discovery® smart, Dentaurum, Germany).

Two central incisor brackets with the help of a stiff wire, as shown in
figure 6, were bonded on the \#11 at an exact same height to avoid
unwanted forces among two parts of the fused tooth, also to increase its
mesiodistal control.

0.014-in nickel titanium (Niti), 0.016-in Niti, 0.018-in stainless steel
(SS) were sequentially placed in 3 months. On 0.018-in SS main archwire
two tie back loop mesial to the first molars were formed. On this 18 ss
working wire, 150 gram mesialization force was delivered to the \#11 by
incorporation of a segment of Niti push coil at right and elastomeric
chain at left of fused incisor brackets.

After midline correction in 10 months, sequential extraction of primary
molars and first premolars, immediately after their eruption, was
ordered. Leveling and alignment of the teeth were performed according to
the standard protocols. Treatment was completed in 26 months (Figure
7-10). Minor restorative treatment was done to slightly correct the form
of the fused incisor (Figure 11). Hawley retainer for the upper and
lower arch was provided for the patient\textbf{.}

Treatment results:

The facial profile remained unchanged after treatment (table 1 \& figure
9). The patient smile was balanced and pleasing. The final occlusion
showed a Class I occlusion with ideal overjet/overbite and coincident
dental midlines. The maxillary right lateral incisor experienced palatal
crown torque and labial root torque. In total, the incisor was moved
across the MPS about 6 millimeters. The midline frenum was slightly
stretched toward the left side but no major inflammation requiring
periodontic procedures was observed. White spot lesions were observed
particularly on the maxillary teeth. Based on the final radiographs, a
proximation between the distal root of the fused incisor and the right
lateral incisor was evident (All the other roots were parallel). That
was inevitable because of the divergent roots of the fused incisor.

\textbf{Discussion:}

This case was a rare example of bilateral double teeth. Based on the
literature, the prevalence of such condition is 5 out of 100,000 in the
human being population \textsuperscript{3}. Movement of bi-rooted \#11
through the MPS was successfully achieved. Indication of tooth movement
through the MPS is closing a central incisor space which might be
congenitally absent, severely malformed or hopeless to maintain. It
aimed to avoid prosthetic treatment, reduce the number of extractions of
healthy teeth, and help correct crowding and incisor
proclination\textsuperscript{9}. Major considerations in moving teeth
across the MPS, are labial frenum inflammation and root resorption. Case
studies reported that in growing patients that their suture is not yet
ossified, moving incisors through the MPS would be less complicated,
while in adult patients, root resorption reported to be a serious
accompanying effect of teeth crossing the ossified suture. In the
present study, the patient was in the early mixed dentition at the
beginning of the treatment and the speed of \#11 mesialization was
comparable to a normal-sized tooth (0.98 mm per month). No dire root
resorption was observed in this case while in Kato's \textsuperscript{9}
and Follin's\textsuperscript{7} studies root resorption were
considerable. Chiho Kato reported replacing a missing maxillary incisor
with the contralateral one in a 26 years old woman. In their case while
the maxillary left incisor crown crossed the midline and 8.7\% of the
apex remained in the same side, the root length shortened 3.3
mm.\textsuperscript{9}.

Bulut managed a case of fused maxillary central incisor by moving that
across the MPS. In their case, no root resorption was observed, however
frenectomy had been performed, also root canal therapy had to be done to
prepare the tooth for casting restorations \textsuperscript{11}.

Likewise in the present study, a mild stretch in the maxillary frenulum
toward the movement of \#11 (the left side) was observed. However, its
inflammation was minor and under the control. Therefore, there was no
need to perform frenectomy as advised by a periodontist.

A disadvantage of this treatment plan was the long period of treatment
time (26months).In spite of emphasis on the oral hygiene, the patient
had lost his cooperation which resulted in poor oral hygiene and
extensive white spots. Dividing the treatment period into two separate
phases would have prevented such complications.

From esthetic point of view, this case, although acceptable, it was not
ideal. The upper and lower midlines were coincident. However
preservation of malformed incisor in front of the mouth was
unattractive. A hemisection procedure to separate the teeth could be a
solution. Since the \#11 was asymptomatic and the patient was satisfied
with the results only a minor restorative correction was performed.

\textbf{Conclusion:}

In complex cases of malformed teeth and severe crowding, it might be an
appropriate option to move the tooth across the MPS in young patients.

\textbf{CONFLICT OF INTEREST}

None declared

\textbf{AUTHOR CONTRIBUTIONS}

S. Yassaei made the early diagnosis of the case and the main idea of
treatment plan, also had provision on all the stages of treatment.

M. Sharifi contributed with providing the patients records, arranged the
necessary dental procedures visits and helped with drafting of the
manuscript.

Z. Ebrahiminik performed the clinical stages of patient treatment and
visited the patient every month session and was a major contributor in
drafting and submitting the manuscript.

\textbf{ETHICS APPROVAL AND CONSENT TO PARTICIPATE}

The patient's parents provided informed written consent prior to all
interventions according to the requirements of the intuitional review
board of the Faculty of Dentistry, Aja University of Medical Science.

\textbf{CONSENT FOR PUBLICATION}

Informed written consent for publication was obtained from the patient's
parents

\textbf{References}

{[}1. Le Gall M.; Philip C.; Aboudharam G.: Orthodontic treatment of
bilateral geminated maxillary permanent incisors. American journal of
orthodontics and dentofacial orthopedics. 2011;139(5):698-703.

2. Mahendra L.; Govindarajan S.; Jayanandan M.; Shamsudeen SM.; Kumar
N.; Madasamy R.: Complete bilateral gemination of maxillary incisors
with separate root canals. Case reports in dentistry. 2014;2014.

3. Altug-Atac AT.; Erdem D.: Prevalence and distribution of dental
anomalies in orthodontic patients. American Journal of Orthodontics and
Dentofacial Orthopedics. 2007;131(4):510-4.

4. Duncan WK.; Helpin ML.: Bilateral fusion and gemination: a literature
analysis and case report. Oral Surgery, Oral Medicine, Oral Pathology.
1987;64(1):82-7.

5. Smail-Faugeron V.; Terradot J.; Bolla MM.; Courson F.: Management of
non-syndromic double tooth affecting permanent maxillary central
incisors: a systematic review. Case Reports. 2016;2016.

6. Finkelstein T.; Shapira Y.; Bechor N.; Shpack N.: Fused and geminated
permanent maxillary central incisors: prevalence, treatment options, and
outcome in orthodontic patients. Journal of Dentistry for Children.
2015;82(3):147-52.

7. Follin M EI.; Thilander B.: orthodontic movement of maxillary
incisors through the midpalatal suture area - an experimental study in
dogs. Eur J Orthod. 1985;7:17-24.

8. Garib DG.; Janson G.; dos Santos PBD.; de Oliveira Baldo T.; de
Oliveira GU.; Ishikiriama SK.: Orthodontic movement of a maxillary
incisor through the midpalatal suture: a case report. The Angle
Orthodontist. 2012;82(2):370-9.

9. Kato C.; Kokai S.; Ono T.: Orthodontic movement of a contralateral
maxillary central incisor across the midpalatal suture. APOS Trends in
Orthodontics. 2020;10(1):50-9.

10. Pair J.: Movement of a maxillary central incisor across the midline.
The Angle orthodontist. 2011;81(2):341-9.

11. Bulut H.; Pasaoglu A.: Multidisciplinary management of a fused
maxillary central incisor moved through the midpalatal suture: A case
report. The korean journal of orthodontics. 2017;47(6):384-93.

\textbf{Figure legends:}

Figure 1: Pretreatment extraoral and intraoral photographs

Figure 2: Pretreatment panoramic radiograph

Figure 3: Pretreatment lateral cephalogram

Figure 4: Pretreatment dental casts

Figure 5: The extracted \#21 tooth mass had one apex and one single,
enlarged pulp canal

Figure 6: Bonding of two brackets to \#11 with the help of a stiff wire
(0.019 × 0.025-in SS) to adjust both at a same vertical level

Figure 7: Posttreatment extraoral and intraoral photographs

Figure 8: Posttreatment panoramic radiograph

Figure 9: Posttreatment Lateral cephalometric radiograph

Figure 10: Posttreatment dental casts

Figure 11: Smile close up photographs demonstrating the progress of
smile esthetic, a) pretreatment smile photograph, b)post orthodontic
smile photograph, c) smile photograph after minor restorative
corrections of \#11\selectlanguage{english}
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