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\begin{document}

\title{THE USE OF 3D PRINTED MODEL AS A RECONSTRUCTION AID IN THE MANAGEMENT OF
AN EXTENSIVE AMELOBLASTOMA OF THE MANDIBLE}



\author[1]{Walter Odhiambo}%
\author[2]{James Gatune}%
\author[2]{Symon Guthua}%
\author[3]{Chris Muraguri}%
\affil[1]{University of Nairobi}%
\affil[2]{University of Nairobi College of Health Sciences}%
\affil[3]{Micrive Infinite}%


\vspace{-1em}



  
  \date{May 27, 2024}


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\begin{abstract}
Ameloblastoma is a benign jaw tumor that can grow to a very huge size
with high rate of recurrence. The large tumours pose a challenge during
resection and reconstructive surgery. We present a massive ameloblastoma
of the mandible that was surgically treated with the aid of 3D printed
model.%
\end{abstract}%



\sloppy


\textbf{THE USE OF 3D PRINTED MODEL AS A RECONSTRUCTION AID IN THE
MANAGEMENT OF AN EXTENSIVE AMELOBLASTOMA OF THE MANDIBLE}

\textbf{-- A CASE REPORT}

Abstract

Ameloblastoma is a benign jaw tumor that can grow to a very huge size
with high rate of recurrence. The large tumours pose a challenge during
resection and reconstructive surgery. We present a massive ameloblastoma
of the mandible that was surgically treated with the aid of 3D printed
model.

Key words: 3D printing, ameloblastoma, mandible

Introduction

Ameloblastoma is a locally aggressive benign jaw tumor, with high rate
of recurrence. It is an odontogenic tumor arising from residual
epithelium of the tooth germ, though aetiology remains
uncertain\textsuperscript{1}. The tumour has a higher predilection for
the mandible (80-90\%) than the maxilla. It is often diagnosed in the
2\textsuperscript{nd}and 3\textsuperscript{rd} decade in the sub-Saharan
African population while a more advanced age is reported in the European
literature.

Ameloblastoma is the commonest jaw tumor and is characterized by various
histological subtypes. There has been recent reclassification of this
tumour into; conventional, unicystic, extraosseous/peripheral and
metastasizing (malignant) ameloblastoma. The unicystic variant tends to
occur in the younger age groups\textsuperscript{2,3,4}.

The management of ameloblastoma is resection of the affected jaw with a
safety margin of more than 1.5cm and reconstruction to restore form and
function of the resultant surgical defect. The affected patients among
black Africans tend to present to the hospitals late with massive
tumors, an observation that has been attributed to a range of factors.
Some of these factors include; poverty, lack of awareness, traditional
beliefs and possibly asymptomatic nature of the disease. (5). This late
presentation pose a great challenge in the management as its often
characterized by the difficult intubation during general anaesthisia
that at times require tracheostomy. There is also a threat of damage to
major blood vessels and nerves within the proximity as well as
reconstruction challenges due to the huge defect created after tumor
resection. Extensive tumours may require multiple or staged surgical
procedures that at times involve initial reconstruction with titanium
implant and later own bridging of the continuity defect with a bone
graft. There is usually a lot of time spent intra-operatively when
trying to shape the reconstruction implant into the correct anatomical
position. The use of 3D printed models can allow for pre-operative
bending of plates into the desired shape, thus reducing the time spent
in surgery.

We present a case of an extensive ameloblastoma in a middle aged male
that was managed with the aid of 3D printed models.

Case description

A 31-year-old male reported to the University of Nairobi Dental Hospital
in June, 2018 complaining of massive swelling on the left side of the
face. He gave a history of having been well until 2012 when he noticed a
swelling after a tooth (38) extraction. The painless swelling had been
slowly increasing in size; the associated teeth progressively became
mobile and fell off. He had lost about 6kgs over the last 1 year (Figure
1).

\textbf{Fig 1: Clinical photographs and CT-OPG of a patient with
ameloblastom at presentation.}

Past dental history was significant for tooth extraction one month
before he noticed a small swelling at the site for which he was put on
antibiotics in a peripheral facility without improvement.

On examination the patient appeared moderately wasted exhibiting mild
conjuctival pallor but no palpable cervical lymph nodes. There was a
massive swelling on the left extending from the left temporal region to
lower border of mandible measuring19cmx16cm in superficial dimensions.
The swelling caused both lingual and buccal expansion with an egg
crackling texture in some areas on palpation. A computerized tomographic
(CT) scan of the lesion showed an extensive destruction of the mandible
and compression of the left maxilla (Figure 2).

\textbf{Fig. 2: 3-D reconstructed CT scan and coronal view
demonstrating} \textbf{the tumour extent}

An incisional biopsy was done and showed features of tumor cells
suggestive of mixed ameloblastoma (Figure 3).

\textbf{Fig 3: Histopathological picture showing peripheral tall
columnar cells with hyperchromatic nuclei surrounding a central mass of
stellate reticulum-like cells features of ameloblastoma.}

The patient had challenges in accessing adequate funds to cater for the
cost of surgery and appropriate implant and it took a while for the
department to solicit for support for his treatment from corporate
partners. He was recalled ten months later when arrangement for his
surgical treatment including sourcing for appropriate reconstruction
implant had been finalized. During the waiting period cutaneous
ulceration occurred on the overlying skin thereby creating apprehension
of possible malignant transformation. (Figure 4).

\textbf{Fig 4: cutaneous ulceration on the tumour surface ten months
after the initial presentation}

Preoperative 3-D bio-printing was done from the CT scan images and
mirror image of the normal side used to generate a stereographic 3D
model of a normal mandible (Figure 5).

\textbf{Fig 5: Superimposition of 3D bio-printed model on the tumour
surface(R) and with the reproduced mirror image of the normal side(R)}

Routine pre-operative investigations were done, including; full
haemogram, urea electrolytes and creatinine as well as blood grouping
and cross matching. The admitting haemoglobin level at admission was
5.7g/dl, therefore, 3 units of blood were transfused preoperatively and
additional 2 units given intra-operatively.

\emph{Surgical approach}

The patient was prepared in the standard way for craniomaxillofacial
surgery and the skin markings made for the planned surgical approach.
Through a lip-split incision that extended to the mental, submandibular
and retromandibular area, the lesion was exposed by a combination of
sharp and blunt dissection and tumor successfully resected. (Figure 6).

\textbf{Fig 6: Intraoperative: incision through extended lip split
(left), surgical defect after tumor resection with a display of lingual
nerve.}

A titanium mandibular reconstruction plate with condylar head extension
was bent into anatomical shape with the aid of 3-D bio-printed model of
the simulated normal mandible. The plate was then secured to the normal
side of the mandible with bicortical screws. The surgical defect was
then closed in layers (Figure 7).

\textbf{Fig 7: Bending the plate with the aid of the stereographic
created 3D model of the mandible (L) and the titanium plate placed in
the surgical defect.}

Post-operatively the patient was put on anti-inflammatory analgesics,
antibiotics and in addition to these routine medication regime he was
also put on \emph{Ranferon} 30mg once a day and \emph{Freshubin} 400mls
thrice daily due to the preoperative cachexia. The post-operative
recovery was uneventful and at three months follow up the patient was
found to weigh 67kg up from preoperative of 57 kg. The occlusion on the
non-operated side was satisfactory enough for masticatory function and
he awaits a second surgery to bridge the continuity defect with a bone
graft (Figure 8).

\textbf{Fig 8: 10 weeks post-operative appearance (left) and
satisfactory occlussal relationship of the spared teeth}

Discussion

Ameloblastoma is a locally aggressive benign tumor, with high rate of
recurrence (WHO, 2005) but rarely exhibits malignant behavior. This most
common odontogenic tumour was previously called adamantinoma and was
first identified by Cusack in 1827. It can grow to a very massive size,
exhibits high recurrence tendency and has been reported to recur even
more than 5 years after surgery, including recurrence in the bone graft
used in the reconstruction. \textsuperscript{4,5,6}

It occurs in individuals aged 20-40 years, but a unicystic type occurs
more frequently among the adolescent age group. The posterior aspect of
mandible is the most common location and the tumour shows no gender
predilection, though some authors have reported a higher female
incident. \textsuperscript{7,8,9}.

The management of ameloblastoma remains marginal or en bloc resection
with a margin of safety of 1-2cm, however, some histologic sub-types
have been shown to be less aggressive especially the unicystic variant
seen in younger age category. This unicystic type has been treated
conservatively in a number of cases often by enucleation with little
recurrence.

It has been noted that recurrent ameloblastomas can be diagnosed even
ten years after the first treatment hence need for long term follow
up.\textsuperscript{8}

The late presentation poses a serious challenge not only in terms
surgical resection of the extensive tumour but also reconstruction of
the continuity defect as well as functional rehabilitation. The use of
3D printed helps in highlighting the extent of the tumour as well as
appreciating the anticipated challenges that can be discussed with the
patient prior to obtaining consent. But what proved useful in this case
was the application of the generated 3D stereographic mirror image in
creating a near normal mandible that aided in accurate bending of the
reconstruction plate to achieve the pre-pathology normal anatomy.

\emph{Conclusion}

3D bio-printing is a useful aid in the treatment planning, surgical
reconstruction of extensive jaw tumours and can reduce operating theater
time as well as minimise intra-operative morbidity with improved
anatomical profile.

\textbf{References .}

1. Wright J and Tekkesin M; odontogenic tumors: where are we in 2017?
Journal of Istanbul University Faculty of Dentistry\emph{.} 2017;
51(3):S10-s30

2. Hendra F et al, Global incidence and profile of ameloblastoma: a
systematic review and meta-anlysis, ResearchGate, 2019;
Doi:10.1111/0di13031

3. Arotiba G, Hille J, Guthua S, et al; Ameloblastoma in Black Africans
the Need for Multi-National Collaborative Research. 2017; JSM Dent Surg.

4. Verneul A, Sapp, Huang C, Abemayor E; Malignant
ameloblastoma:classification, diagnostic, and therapeutic challenges; Am
J Otolaryngol. 2002; Jan-Feb;23(1):44-8

5. Ram H, Mohammad S, Husain N and Gupta P: Ameloblastic Carcinoma, J
Maxillofac Oral Surg. 2011; 9(4):415-419

6. Ramon Y, Mozes M and Buchner A, A fatal case of
Ameloblastoma(adamantinoma). Int. J of surgical reconstruction, 1964;17;
pp320-324

7. Butt F M, Guthua S W, Awange DA, Dimba E A O and Macigo F G, 2011.
The pattern and occurrence of ameloblastoma in adolescents treated at a
university hospital, in Kenya: A 13-year study. J of Cranio-Max-Fac
Surg. 2012; Feb,40(2):39-45

8. Nguyai C, Ogalo J, Guthua S, Odhiambo W, The Potential of using 3D
printed Specific Models in Reconstructive Surgery of the mandible. Afr.
J of Oral Health Sci, 2017; (1)5:7-

9. Kumar A, Verma A, Baduni A and Kaur N, Ameloblastoma and its
Malignant Transformation: Treatment Ladder, Related Syndromes and
Controversies, International Journal of Contemporary Medical Research.
2017; 83(4 2): 2393-915

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