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\begin{document}

\title{Management of a patient with a severely infraoccluded primary molar and
hypodontia}



\author[1]{Alaina Ng}%
\author[1]{Desmond Ong}%
\author[1]{Phillip Goh}%
\affil[1]{The University of Queensland}%


\vspace{-1em}



  
  \date{May 27, 2024}


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\selectlanguage{english}
\begin{abstract}
Infraocclusion of a primary molar is a relatively common occurrence
which seldom leads to serious complications, particularly when the
succedaneous permanent tooth is present. Despite the relative
infrequency of unfavourable outcomes, an infraoccluded primary molar may
be associated with other dental anomalies, including hypodontia.%
\end{abstract}%



\sloppy


\textbf{Introduction}

Infraocclusion is a condition that occurs when the occlusal surface of a
tooth is located below the occlusal plane of the adjacent teeth.
Submergence is a synonymous term also used to describe this clinical
presentation, which most commonly affects primary molar
teeth.\textsuperscript{1-3} Infraocclusion of primary teeth is caused by
ankylosis of the cementum to the surrounding alveolar bone, thus
impeding its eruption.\textsuperscript{1-3} The incidence of ankylosis
is approximately 1.3-38.5\% in primary
molars.\textsuperscript{1}Ankylosis can occur at any time and results in
the primary tooth failing to keep pace with the normal vertical alveolar
bone height changes in a growing individual. Therefore, ankylosis is the
phenomenon which results in the lack of tooth eruption and subsequently
leads to the clinical presentation of infraocclusion.

The prevalence of this condition is also affected by
age.\textsuperscript{1-4} Infraocclusion of the first primary molar is
reported to be more common in children under the age of nine and shows a
general increase in incidence after the age of
three.\textsuperscript{1-3} In comparison, the prevalence of
infraoccluded second primary molars increases after the age of five and
is more prevalent after the age of nine.\textsuperscript{1-3}

The prevalence of infraocclusion is significantly higher in the primary
dentition compared to the permanent dentition and more commonly found in
the mandible as opposed to the maxilla, with no significant gender
dimorphism reported. The most commonly affected teeth are the mandibular
first and second primary molars, with no predilection between the left
and right sides. It has been reported that 1.3-8.9\% of children are
affected by infraocclusion of one or more of their primary
teeth.\textsuperscript{1-3} In addition, it was found that 18-44\% of
the affected children's siblings also presented with infraoccluded
teeth, which appears to indicate a genetic contribution to this
condition.\textsuperscript{1-4}

Infraocclusion can also be categorised as slight, moderate, or
severe.\textsuperscript{1,2} The Facile classification, as described by
Brearly\textsuperscript{5}, defines infraocclusion as slight when the
occlusal surface of the tooth is one millimetre below that of its
neighbours, moderate when the occlusal surface of the tooth is level to
or below the contact point of the neighbouring teeth, and severe when
the occlusal surface of the tooth is below the interproximal gingival
tissue.\textsuperscript{1} Both the prevalence and severity of
infraocclusion increases with chronological age. Therefore, a younger
patient who experiences primary tooth ankylosis is likely to demonstrate
more severe infraocclusion due to the longer period of vertical alveolar
bone height development. Although most ankylosed primary teeth
eventually exfoliate with the ongoing eruption of the succedaneous tooth
underneath, delayed exfoliation is common. Despite the relative
infrequency of unfavourable outcomes, infraoccluded primary molars are
known to be associated with other dental anomalies, including
hypodontia.\textsuperscript{6} The eruption path of the successor tooth
must be monitored closely and periodically to avoid undesirable
permanent tooth impactions. In extreme cases, the ankylosed primary
tooth can submerge to the point of complete coverage by the surrounding
hard and soft tissues as detailed in this case
report.\textsuperscript{7}

Despite the uncertainty, there is a general consensus that
infraocclusion is multifactorial in aetiology.\textsuperscript{1-3} It
has been postulated that infraocclusion may be genetic in nature as this
condition can be seen in families, however, there are several factors
such as altered local metabolism, local trauma and infection that may
also potentially result in the infraocclusion of
teeth.\textsuperscript{1-3}

Hypodontia, also known as congenitally missing teeth, is another common
dental developmental anomaly that indicates that at least one permanent
tooth has failed to form and erupt into the oral
cavity.\textsuperscript{4,8-14}

The current consensus is that the aetiology of congenitally missing
teeth is multifactorial, with genetic and environmental factors
potentially both playing a role.\textsuperscript{4,8-14} Heritability of
congenitally missing teeth has been established through familial studies
where parents and their offspring and/or siblings have presented with
the same or similar congenitally missing
teeth.\textsuperscript{4,6,8-18} Numerous developmental syndromes such
as Down, Book and Rieger are associated with congenitally missing teeth,
which suggests the influence of genetic factors on the development of
the dentition.\textsuperscript{6,13-15} It has been suggested that
missing anterior teeth have a stronger genetic contribution, while the
absence of posterior teeth may be more sporadic in
nature.\textsuperscript{13}

When reporting on the prevalence of hypodontia, the inclusion or
exclusion of the third molars produces a distinct difference in the
data.\textsuperscript{4} This difference is due to the high frequency of
congenitally missing third molars across all genetic
populations.\textsuperscript{4,19} Excluding the third molars, the
prevalence of congenitally missing teeth in specific teeth appears to be
determined by the population demographics.\textsuperscript{4,19} The
prevalence of congenitally missing teeth in the primary dentition has
been reported to be less than 1\%, however, the prevalence of missing
teeth in the permanent dentition ranges from 1.6-36.5\%, when the
absence of third molars are included. When missing third molars are
excluded from the data, the prevalence of congenitally missing permanent
teeth is significantly lower and reported to range between
1.6-6.9\%.\textsuperscript{13} It is also reported that congenitally
missing teeth occurs bilaterally in the mouth almost two to three times
more frequently than unilaterally. Excluding the third molars, the most
common congenitally missing teeth in the permanent dentition are the
mandibular second premolars followed by the maxillary lateral
incisors.\textsuperscript{13,14}

\textbf{Case Description and Diagnosis}

A 14-year-old patient was referred to assess the potential for
comprehensive orthodontic treatment. It was noted that the patient was
in the late mixed dentition with an atypical Class II indefinite
malocclusion. The overjet was determined to be 2mm and the maxillary
incisors covered approximately 25\% of the mandibular incisors in the
vertical plane. Although the maxillary and mandibular midlines were
coincident with each other, both dental midlines were located 2mm to the
right side of the facial midline. The right-side molar relationship was
Class III, however, the right-side canine relationship was half-unit
Class II. The crown of the mandibular right first permanent molar (46)
was also deemed to have a significant mesial tip. The mandibular right
second primary molar (85) was not clinically visible, and there was no
record of this tooth being extracted. Due to the presence of the
mandibular left second primary molar (75), the left-side molar
relationship had a mild Class II tendency and the left-side canine
relationship was Class I. A posterior lingual crossbite was present on
the left-side and no associated functional shift from the retruded
contact position to the position of maximum intercuspation was evident
(Figure 1).

A panoramic radiograph (Figure 2a) revealed ankylosis and severe
submergence of the 85 along with displacement and impaction of the
developing 45. It appeared that the ankylosis and submergence of the 85
had disrupted the alveolar development in this region, which in turn
resulted in the localised distortion of the posterior teeth in the
fourth quadrant. Despite the highly unusual radiographic appearance in
this area, no current or previous pain or discomfort was reported by the
patient. It was also noted that the mandibular left second premolar (35)
was congenitally missing and the mandibular left second primary molar
(75) was over-retained with significant remaining root structure. The 75
showed no evidence of infraocclusion and was clinically sound and
non-mobile. All third molars were present in the crown stage of
development.

A lateral cephalograph and subsequent cephalometric analysis revealed
that the patient had a horizontal skeletal Class I relationship, a
brachyfacial vertical facial morphology and normal angulation of the
maxillary and mandibular incisors. Soft tissue analysis determined that
the facial features were symmetrical, along with a pleasing facial
profile and competent lip function (Figure 2b).

The relevant diagnostic findings are summarized in Table 1 and as a
prioritized problem list in Table 2. Due to the severe submergence of
the 85 and impaction of the 45, the patient was referred to an oral and
maxillofacial surgeon for assessment of this area and to plan the
required surgical management. Several potential treatment options were
considered (Table 3). Each of these treatment options have been
summarised and compared along with their specific advantages and
disadvantages (Table 4).

Following extensive communication between the orthodontist, general
dentist and the oral and maxillofacial surgeon, it was determined that
the most predictable treatment option involved removal of the submerged
85 and the impacted 45. The oral and maxillofacial surgeon indicated
that removal of the ankylosed 85 would necessitate significant bone
removal and the impacted 45 would be likely to be damaged during in this
process. In addition, surgical exposure and subsequent orthodontic
traction with a gold chain to disimpact the 45 was expected to be both
prolonged and challenging. As the 35 was also congenitally missing, a
decision was also required regarding the over-retained 75. Given that
the mandibular third molars were developing and that over-retained
primary teeth generally have reduced longevity compared to healthy
permanent teeth, removal of the 75, uprighting of the 46 and complete
orthodontic space closure through bilateral mandibular molar
mesialisation was recommended. This treatment option would require the
use of temporary anchorage devices (TADs) to ensure maximum
predictability of these challenging orthodontic tooth movements.
Complete orthodontic space closure in the mandibular arch through
bilateral mandibular molar mesialisation would be associated with the
numerous potential benefits for the patient. Firstly, this option would
eliminate the need for future prosthodontic replacement for the
congenitally missing 35 and the irretrievable 45. The process of
orthodontic tooth movement has been shown to be osteo-inductive and has
the ability to regenerate atrophic alveolar bone resulting from
congenital absence of teeth and/or iatrogenic issues. Effective
mandibular molar mesialisation would also protect the harmonious
pre-treatment incisor angulation and lip positions whilst also creating
significant space for spontaneous future eruption of the developing
third molar teeth into functional positions.

\textbf{Orthodontic Treatment Progress}

The patient exhibited satisfactory oral hygiene and was motivated to
undergo orthodontic treatment. General dental examinations and
preventative treatment were provided at six-monthly intervals during the
comprehensive orthodontic treatment.

\textbf{Placement of Fixed Appliances}

Comprehensive orthodontic treatment commenced with a placement of a
Hyrax rapid maxillary expansion appliance to correct the left-side
posterior lingual crossbite and pre-adjusted maxillary labial fixed
appliances (0.022'' \selectlanguage{ngerman}× 0.028'' slot, MBT prescription, 3M Oral Care, MN,
USA). Instructions were given to turn the rapid maxillary expansion
appliance once daily for 26 consecutive days. Following another review,
the maxillary arch expansion was deemed to be satisfactory.

\textbf{4 months}

The rapid maxillary expansion appliance was removed and bonded molar
tubes were placed on the 16 and 26. The patient had a general
anaesthetic three weeks later, where the oral and maxillofacial surgeon
removed the 75,85,18,28 and 45. Temporary anchorage devices (1.8 x 8.0mm
-- Synthes® Solothurn, Switzerland) were placed between the mandibular
canines and first premolars to facilitate complete orthodontic space
closure in the mandibular arch.

\textbf{9 months}

Due to the significant mesial crown tip of the 46, a hybrid mandibular
archwire technique was implemented (Figure 3). The rigid rectangular
(0.016'' × 0.022'') stainless steel archwire ended at the distal aspect
of the 44. A sectional flexible nickel-titanium (0.016'') wire was
placed from the 43 to the 46 and was located underneath the rectangular
steel archwire in the 43 and 44 region. The TAD between the 43 and 44
was connected to the 43 and 44 brackets with a fine stainless steel
ligature wire. This ligature wire, along with the rectangular stainless
steel archwire provided stabilising anchorage for the 43 and 44, as the
reciprocal biomechanical force generated from the uprighting of the
mesially tipped 46 was expected to be significant. These fixed appliance
components provided effective stabilisation to prevent undesirable
movement of the 43 and 44.

\textbf{15 months}

The 46 was successfully uprighted and mesial movement of the mandibular
molar teeth progressed without incident (Figure 4 and 5). The ligature
wire remained in place bilaterally to facilitate the remaining mesial
movement without undue distal movement of the mandibular anterior teeth.
The alveolar bone and soft tissue regeneration associated with the
mesial movement of the 46 was deemed to be very favourable.

\textbf{28 months}

The fixed labial orthodontic appliances were removed and maxillary and
mandibular flossable fixed retainers were bonded on the anterior teeth
to reduce the potential for rotational relapse (Figure 6). Maxillary and
mandibular vacuum formed Essix® C+ material (Dentsply Raintree Essix®)
removable retainers were also issued for indefinite nocturnal wear.

\textbf{53 months (25 months post-deband)}

The patient was reviewed 25 months following the completion of active
orthodontic treatment. (Figure 7). The overall alignment and tooth
interdigitation had been maintained. The 26 was noted to be in a
posterior lingual crossbite position, however, this minor irregularity
did not present any aesthetic or functional concerns. The 38 and 48 were
noted to be partially erupted with a very high likelihood of gaining
acceptable antagonistic contact with the opposing 17 and 27. An updated
panoramic radiograph (Figure 8) demonstrated that alveolar bone
regeneration had occurred in the fourth quadrant and that the eruption
path of the developing 38 and 48 appeared favourable.

\textbf{Discussion}

This case report has detailed a pleasing overall treatment outcome which
addressed the presenting malocclusion and eliminated the future need for
prosthodontic treatment for the congenitally missing 35 and 45. The
spontaneous eruption of the 38 and 48 into satisfactory clinical
positions further enhanced the treatment outcome from a functional
perspective. The eruption of the 38 and 48 was made possible through
effective mesialisation of the mandibular first and second permanent
molars during the orthodontic treatment. Such mesial movement created
space distal to the mandibular second molars which subsequently created
an unobstructed eruption path for the 38 and 48. Although an argument
could be made for improving the alignment of the 38 and 48 with a second
phase of fixed appliances, this was not desired by the patient. Should
the 38 and/or 48 not erupt further and require removal for any dental
health reason, such removal would be undoubtedly more straightforward
compared to their original pre-treatment position and angulation (Figure
2b). This improvement in angulation and vertical position can be
attributed to the effective orthodontic mesialisation of the mandibular
first and second permanent molars.

The mandibular right second primary molar tooth was not visible
clinically at the initial orthodontic consultation. The pre-treatment
panoramic radiograph was rather confronting as it revealed a severe
submergence of the 85 and its resultant effect upon the succedaneous 45.
This problematic outcome emphasizes the need for routine and periodic
assessment of growing patients. The dentition of a growing patient is as
an individual and dynamic entity which requires all dental practitioners
to be familiar with the eruption sequence of teeth. Any deviation from
the norm should be diagnosed and managed in a timely manner, in order to
preserve dental arch integrity and to avoid negative
outcomes.\textsuperscript{20} In retrospect, earlier diagnosis of the
infraoccluded 85 (i.e. when this tooth was still in a supragingival
position) would have been ideal and may have completely avoided the
surgical and orthodontic management challenges encountered in the fourth
quadrant.

Congenitally missing premolar teeth are relatively common and are often
associated with both short and long-term clinical dilemmas. Numerous
factors must be carefully considered in the diagnostic and treatment
planning~process. It is imperative that every relevant treatment option
be evaluated from the cost-benefit perspective and thoroughly discussed
with the patient as part of the informed consent process.

Maintaining an over-retained primary molar when the succedanenous
premolar is congenitally missing may be a reasonable option for some
individual patients, particularly if the primary molar demonstrates no
sign of infraocclusion, is unrestored, non-mobile and has significant
remaining root structure. Such a tooth may be expected to have a good
long-term prognosis and decent clinical longevity. It has been reported
that after the age of 20 years, retained primary molars display minimal
change with respect to infraocclusion, tipping of adjacent teeth and
root resorption. Therefore, should a primary molar still be present in
the dental arch at 20 years of age, it may have a good prognosis for
long-term survival.\textsuperscript{21}

However, it is difficult to argue that an intact primary tooth would
have superior clinical longevity in comparison to a healthy permanent
tooth. For some patients, it may be advantageous to remove primary
molars and appropriately close the extraction spaces in conjunction with
orthodontic treatment. Such space redistribution may create sufficient
space for third permanent molars to successfully erupt, as demonstrated
in this case report.

Anchorage is defined as a resistance to unwanted tooth
movement\textsuperscript{22} and anchorage control is a fundamental
principle of contemporary orthodontic
treatment.\textsuperscript{7,23}Anchorage can be controlled through the
use of intra-oral or extra-oral devices. The development of
non-osseointegrating titanium bone screws has revolutionised orthodontic
anchorage control as they offer a simple, safe and effective option with
reduced patient compliance.\textsuperscript{24} These mechanically
retained bone screws are generically referred to as temporary anchorage
devices (TADs) and due to their placement into inter-radicular,
mandibular or palatal bone, their clinical application is also known as
skeletal anchorage.\textsuperscript{7,22-24}

The use of TADs can permit safe, predictable and effective orthodontic
mesialisation of the mandibular first and second permanent molars.
Although such movement can also be achieved through the implementation
of intermaxillary elastics or bite correcting springs, TADs can
significantly reduce the amount of patient compliance required for
challenging tooth movements. With the benefit of hindsight, the authors
concede that the TADs used for this patient may have provided better
indirect anchorage control if rigid wire splinting was used between the
TADs and the mandibular canines or premolar
teeth.\textsuperscript{25,26} In addition, mesial force applied directly
to the TADs could also have been implemented following uprighting of the
46.\textsuperscript{27}

The mesialisation of first and second permanent molars to provide space
for third molars has been widely discussed in the literature. When a
premolar or a second primary molar is extracted and the remaining
posterior teeth have been moved mesially, the probability of spontaneous
eruption of the third molars does increase.\textsuperscript{28-33} In
general, the greater the distance of first and second molar
mesialisation, the greater the probability of spontaneous normal
eruption of the third molar teeth.\textsuperscript{28}

Removal of significant alveolar bone was required to extract the
ankylosed 85 and impacted 45. Fortunately, subsequent spontaneous bone
regeneration generally allows bony defects to fill with bone without the
presence of a stimulus or grafting material.\textsuperscript{34} This
phenomenon also occurs in patients who have had large cysts removed from
the ramus of the mandible. In addition, orthodontic tooth movement
through the area of an alveolar bony defect can further facilitate
regeneration of bone.\textsuperscript{34} Orthodontic tooth movement can
both stimulate and help maintain bone formation, however, how this
process occurs is not completely understood.\textsuperscript{35} Two
hypotheses exist with respect to the process of osteogenesis. The first
hypothesis is a bone bending theory as described by Epker and
Frost\textsuperscript{36,37}, which postulates that the flexion of the
alveolar bone creates convexities and concavities which in turn
stimulates osteogenesis and resorption. The second hypothesis is known
as the pressure tension hypothesis.\textsuperscript{38,39} This
hypothesis relates to the concept of creates pressure and tension areas
that occur within the periodontal ligament as the tooth moves. The
pressure and tension stimulates simultaneous bone resorption and
osteogenesis which then allows for tooth movement. For the patient
described in this case report, the large bony defect which resulted from
surgical removal of the 85 and 45 was completely resolved, and likely
occurred through a combination of normal bone healing and by the
osteogenic effects of orthodontic tooth movement.

In recent times, there has been a resurgence in the technique of tooth
autotransplantation, which refers to the technique of transplanting
embedded, impacted or erupted teeth from one site into another in the
same individual.\textsuperscript{40} Autotransplantation can provide a
cost-effective and biocompatible solution for adolescent patients with
congenitally missing teeth or significantly compromised teeth when a
suitable donor tooth is available.\textsuperscript{41} Although
carefully considered individual case selection and surgical skill are
the critical determinants for success, advances in three-dimensional
computed tomography and rapid prototyping have the potential to
significantly reduce the technique sensitivity of the
autotransplantation procedure.\textsuperscript{41}

The patient in this case report was also considered to be a potential
candidate for tooth autotransplantation. The left mandibular third molar
(38) may have eventually become a reasonable donor tooth to replace the
congenitally missing 35. However, the 38 did not demonstrate sufficient
tooth development at the time of the planned removal of the ankylosed 85
and impacted 45 to permit safe autotransplantation under a single
general anaesthetic. The clinicians involved in the management of this
case determined that effective mesialisation of the mandibular molars
would result in a very high likelihood of successful eruption of the 38.
The favourable third molar eruption outcome which was attained with the
orthodontic treatment ultimately justified the clinical decisions made
at the treatment planning stage.

Although restorative implants are increasing in acceptance and
popularity amongst both patients and clinicians, such treatment may not
always represent the most ideal option for compromised or congenitally
missing teeth. Actively growing adolescent patients may also pose
several management issues for future implant
placement.\textsuperscript{42} Given this patient's relatively young
age, presence of third molars of suitable morphology and the need for
comprehensive orthodontic treatment, maintaining the over-retained 75
with a view to eventual implant replacement was not considered to be the
ideal option for this individual patient.

\textbf{Conclusion}

This case report documents the management of a severely infraoccluded
primary molar, an impacted second premolar and a congenitally missing
premolar tooth which resulted in significant surgical and orthodontic
challenges. Comprehensive planning and careful orthodontic treatment,
including use of temporary anchorage devices (TADs), effectively
addressed the presenting malocclusion. Although this ambitious
orthodontic treatment did not attain an ideal occlusion, favourable
outcomes were achieved with respect to alveolar bone regeneration,
avoidance of future prosthodontic rehabilitation and spontaneous
mandibular third molar eruption.

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34. Nová\selectlanguage{polish}č\selectlanguage{english}kov\selectlanguage{ngerman}á S, Marek I, Kamínek M. Orthodontic tooth movement: Bone
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\textbf{Table 1. Key Diagnostic FeaturesSkeletal}

\begin{itemize}
\tightlist
\item
  Class I skeletal base with a mild Class III tendency (Horizontal)
\item
  Mesofacial growth pattern with a mild brachyfacial tendency (Vertical)
\item
  Normal facial symmetry (Transverse)
\end{itemize}

\textbf{Dental}

\begin{itemize}
\tightlist
\item
  RHS: ½ unit Class II canine relationship, LHS: Class I molar and
  canine relationship (Horizontal)
\item
  Slightly increased overjet \textasciitilde{} 2mm (Horizontal)
\item
  Normal angulation of the maxillary and mandibular incisors
\item
  Normal anterior overbite \textasciitilde{} 25\% (Vertical)
\item
  Both maxillary and mandibular dental midlines located 2mm to the RHS
  of the facial midline (Transverse)
\item
  LHS posterior lingual crossbites, indicating a relative maxillary
  transverse deficiency (Transverse)
\end{itemize}

\textbf{Soft Tissues}

Normal lip position (Horizontal)

Normal lip seal (Vertical)

Normal chin point position (Transverse)

\textbf{Other Diagnostic Features of Note}

\begin{itemize}
\tightlist
\item
  Significant mesial tip crown of the 46
\item
  Over-retained 75 (non-mobile)
\item
  Congenitally missing 35 (noted on the panoramic radiograph)
\item
  85 was not clinically visible
\item
  Severely infraoccluded 85 due to historical ankylosis and associated
  impaction of the 45 (noted on the panoramic radiograph)
\item
  Mild maxillary arch malalignment
\item
  Mild mandibular arch spacing in the 4\textsuperscript{th} quadrant
\item
  Third molar teeth present in the early stage of formation
\end{itemize}

\textbf{Table 2: Systematic Problem List}

\begin{enumerate}
\tightlist
\item
  Severely infraoccluded 85 due to historical ankylosis, associated
  impaction of the 45 and disrupted alveolar development in the fourth
  quadrant
\item
  Mandibular arch distortion, arch asymmetry and spacing in the fourth
  quadrant
\item
  Over-retained 75 and congenitally missing 35
\item
  LHS posterior lingual crossbite
\item
  Likely future impaction of the developing maxillary and mandibular
  third molars
\end{enumerate}

\textbf{Table 3: Relevant Treatment Options}

\textbf{Treatment Option 1:}

\textbf{Extract the over-retained 75, infraoccluded 85, impacted 45 and
18,28. Comprehensive orthodontic fixed appliance treatment including
effective mandibular molar mesialisation.}

\begin{itemize}
\tightlist
\item
  Rapid maxillary expansion (RME) to address the maxillary transverse
  deficiency and correct the LHS posterior lingual crossbite
\item
  Removing the 75 will avoid the need for a future implant in this
  region and effective mesialisation of the 36,37 will create space for
  the unerupted 38
\item
  Removing the 85 and 45 will create an alveolar bony defect which can
  be regenerated with normal healing and effective mesialisation of the
  46,47. Such mesialisation will also create space for the unerupted 48
\item
  Removing the 18,28 as these teeth will be either impacted or
  occlusally redundant post-treatment
\item
  Use of TADs can provide safe, predictable and effective orthodontic
  tooth movements as required (i.e. uprighting of the tipped 46 and
  effective mandibular molar mesialisation)
\item
  Aims to maintain normal anterior overbite, overjet and the currently
  harmonious lip positions and incisor angulations
\item
  Review the unerupted mandibular third molars until their expected
  eventual clinical eruption
\end{itemize}

\textbf{Treatment Option 2:}

\textbf{Maintain the over-retained 75 long-term. Extract the
infraoccluded 85, impacted 45 and 18,28,38. Comprehensive orthodontic
fixed appliance treatment including effective mandibular molar
mesialisation on the right side}

\begin{itemize}
\tightlist
\item
  Rapid maxillary expansion (RME) to address the maxillary transverse
  deficiency and correct the LHS posterior lingual crossbite
\item
  Removing the 85 and 45 will create an alveolar bony defect which can
  be regenerated with normal healing and TAD-assisted mesialisation of
  the 46,47. Effective mesialisation will also create space for the
  unerupted 48
\item
  Maintaining the 75 is clinically justifiable as this tooth is
  structurally sound and demonstrates no evidence of infraocclusion or
  mobility. Upon its eventual clinical failure, a restorative implant
  can be placed in this region. This represents simpler orthodontic
  treatment in the 3\textsuperscript{rd} quadrant
\item
  Review the unerupted 48 until its expected eventual clinical eruption
  and the over-retained 75 for any structural integrity issues
\end{itemize}

\textbf{Treatment Option 3:}

\textbf{Maintain the over-retained 75 long-term. Extract the
infraoccluded 85 and the impacted 18,28,38,48. Attempt orthodontic
alignment of the impacted 45 in conjunction with comprehensive
orthodontic fixed appliance treatment.}

\begin{itemize}
\tightlist
\item
  Rapid maxillary expansion (RME) to address the maxillary transverse
  deficiency and correct the LHS posterior lingual crossbite
\item
  Surgical exposure and subsequent orthodontic traction with a gold
  chain to disimpact the 45 is likely to be both prolonged and
  challenging. The 45 may also be significantly damaged during removal
  of the ankylosed 85
\item
  Maintaining the 75 is clinically justifiable as this tooth is
  structurally sound and demonstrates no evidence of infraocclusion or
  mobility. Upon its eventual clinical failure, a restorative implant
  can be placed in this region
\end{itemize}

\textbf{Treatment Option 4:}

\textbf{Extract the over-retained 75, infraoccluded 85, impacted 45 and
15,25 in conjunction with comprehensive orthodontic fixed appliance
treatment.}

\begin{itemize}
\tightlist
\item
  Rapid maxillary expansion (RME) to address the maxillary transverse
  deficiency and correct the LHS posterior lingual crossbite
\item
  Removing the 15,25 can be justified to balance the removal of the
  75,85
\item
  Ideally, TAD-assisted space closure should be performed in both the
  maxillary and mandibular arches for effective molar mesialisation and
  to avoid any significant incisor retraction (as the current lip
  position and incisor angulations are deemed to be harmonious and
  favourable)
\item
  Review the unerupted maxillary and mandibular third molars until their
  expected eventual clinical eruption
\end{itemize}

\textbf{Treatment Option 5:}

\textbf{Extract the infraoccluded 85, impacted 45 and 18,28. Instead of
attempting effective mandibular molar mesialisation in the third
quadrant, comprehensive orthodontic fixed appliance treatment can be
used to facilitate future autotransplantation of the 38 into the
congenitally missing 35 region.}

\begin{itemize}
\tightlist
\item
  Rapid maxillary expansion (RME) to address the maxillary transverse
  deficiency and correct the LHS posterior lingual crossbite
\item
  The 38 did not demonstrate sufficient tooth development at the time of
  the planned removal of the ankylosed 85 and impacted 45 to permit safe
  autotransplantation under a single general anaesthetic
\item
  Although future third molar autotransplantation would significantly
  reduce the orthodontic tooth movement required in the third quadrant,
  the autotransplantation procedure must be delayed until an ideal stage
  of third molar root development is present (at approximately 18 years
  of age)
\item
  Although contemporary tooth autotransplantation techniques have a high
  success rate, post-transplant complications are still possible
\end{itemize}

\emph{}

\textbf{Table 4. Comparison of the Relevant Treatment Options}\selectlanguage{english}
\begin{longtable}[]{@{}llllll@{}}
\toprule
\begin{minipage}[b]{0.14\columnwidth}\raggedright\strut
\strut
\end{minipage} & \begin{minipage}[b]{0.14\columnwidth}\raggedright\strut
\textbf{Treatment Option 1} Extract 75,85,45 and 18,28 Bilateral
TADs\strut
\end{minipage} & \begin{minipage}[b]{0.14\columnwidth}\raggedright\strut
\textbf{Treatment Option 2} Maintain 75 Extract 85,45 and 18,28,38
Unilateral TAD\strut
\end{minipage} & \begin{minipage}[b]{0.14\columnwidth}\raggedright\strut
\textbf{Treatment Option 3} Maintain 75 Extract 85 and 18,28,38,48
Attempt disimpaction of the 45\strut
\end{minipage} & \begin{minipage}[b]{0.14\columnwidth}\raggedright\strut
\textbf{Treatment Option 4} Extract 75,85,15,25,45 Bilateral TADs\strut
\end{minipage} & \begin{minipage}[b]{0.14\columnwidth}\raggedright\strut
\textbf{Treatment} \textbf{Option 5} Extract 85,45 and 18,28 Unilateral
TAD Future autotransplantation of 38\strut
\end{minipage}\tabularnewline
\midrule
\endhead
\begin{minipage}[t]{0.14\columnwidth}\raggedright\strut
Maintain Lip and Incisor Positions\strut
\end{minipage} & \begin{minipage}[t]{0.14\columnwidth}\raggedright\strut
Yes\strut
\end{minipage} & \begin{minipage}[t]{0.14\columnwidth}\raggedright\strut
Yes\strut
\end{minipage} & \begin{minipage}[t]{0.14\columnwidth}\raggedright\strut
Yes\strut
\end{minipage} & \begin{minipage}[t]{0.14\columnwidth}\raggedright\strut
Yes\strut
\end{minipage} & \begin{minipage}[t]{0.14\columnwidth}\raggedright\strut
Yes\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.14\columnwidth}\raggedright\strut
Avoids the Need for Future Restorative Implants\strut
\end{minipage} & \begin{minipage}[t]{0.14\columnwidth}\raggedright\strut
Yes\strut
\end{minipage} & \begin{minipage}[t]{0.14\columnwidth}\raggedright\strut
No\strut
\end{minipage} & \begin{minipage}[t]{0.14\columnwidth}\raggedright\strut
No\strut
\end{minipage} & \begin{minipage}[t]{0.14\columnwidth}\raggedright\strut
Yes\strut
\end{minipage} & \begin{minipage}[t]{0.14\columnwidth}\raggedright\strut
Yes\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.16\columnwidth}\raggedright\strut
Regenerates Alveolar Bone in Quadrant 4\strut
\end{minipage} & \begin{minipage}[t]{0.16\columnwidth}\raggedright\strut
Yes\strut
\end{minipage} & \begin{minipage}[t]{0.16\columnwidth}\raggedright\strut
Yes\strut
\end{minipage} & \begin{minipage}[t]{0.16\columnwidth}\raggedright\strut
Yes\strut
\end{minipage} & \begin{minipage}[t]{0.16\columnwidth}\raggedright\strut
Yes\strut
\end{minipage} & \begin{minipage}[t]{0.16\columnwidth}\raggedright\strut
Yes\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.16\columnwidth}\raggedright\strut
Facilitate Future Third Molar Eruption\strut
\end{minipage} & \begin{minipage}[t]{0.16\columnwidth}\raggedright\strut
Yes (38,48)\strut
\end{minipage} & \begin{minipage}[t]{0.16\columnwidth}\raggedright\strut
Yes (48)\strut
\end{minipage} & \begin{minipage}[t]{0.16\columnwidth}\raggedright\strut
No\strut
\end{minipage} & \begin{minipage}[t]{0.16\columnwidth}\raggedright\strut
Yes (18,28,38,48)\strut
\end{minipage} & \begin{minipage}[t]{0.16\columnwidth}\raggedright\strut
Yes (48)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.14\columnwidth}\raggedright\strut
Orthodontic Treatment Difficulty\strut
\end{minipage} & \begin{minipage}[t]{0.14\columnwidth}\raggedright\strut
++\strut
\end{minipage} & \begin{minipage}[t]{0.14\columnwidth}\raggedright\strut
+\strut
\end{minipage} & \begin{minipage}[t]{0.14\columnwidth}\raggedright\strut
+++\strut
\end{minipage} & \begin{minipage}[t]{0.14\columnwidth}\raggedright\strut
+++\strut
\end{minipage} & \begin{minipage}[t]{0.14\columnwidth}\raggedright\strut
+\strut
\end{minipage}\tabularnewline
\bottomrule
\end{longtable}

\textbf{Hosted file}

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