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British Journal of Healthcare and Medical Research - Vol. 10, No. 4
Publication Date: August 25, 2023
DOI:10.14738/bjhmr.104.15366.
Torii, K. (2023). Occlusal Analysis and Management of a Patient with Median Nerve Palsy of Unknown Etiology: A Case Report. British
Journal of Healthcare and Medical Research, Vol -10(4). 264-269.
Services for Science and Education – United Kingdom
Occlusal Analysis and Management of a Patient with Median
Nerve Palsy of Unknown Etiology: A Case Report
Kengo Torii
Department of Comprehensive Dental Care Unit,
School of Life Dentistry, Nippon Dental University, Tokyo, Japan
ABSTRACT
A patient presented with a diagnosis of median nerve palsy in the fingers of the right
hand of unknown etiology by an orthopedic surgeon. Occlusal analysis showed that
the habitual occlusal position and the muscular position were inconsistent, and in
the muscular position the left second premolars were in premature contact. When
the biting force was examined, it was mean 37 kg for the right and mean 13.3 kg for
the left at first visit. The left-right difference in bite force was significant (p<0.005).
As a result of five times of occlusal adjustment, occlusal contact of both molars was
obtained, and the occlusal force was mean 20 kg on the right and mean 21 kg on the
left, and there was no left-right difference. The median nerve palsy of the right hand
also disappeared. In this case, the bite force on the right side was abnormally
stronger than that on the left side, and the trigeminal motor nucleus on the right
side was abnormally excited. It was considered that the activity of the trigeminal
spinal cord nucleus was suppressed, resulting in median nerve palsy.
Keywords: occlusal discrepancy, occlusal force, trigeminal motor nucleus
INTRODUCTION
Median nerve palsy appears due to various causes such as trauma, tumor, overwork, etc., but
there is no report on extreme left-right difference in occlusal force. It has been reported on the
relationship between occlusal force and temporomandibular joint sound, occlusal force and
hearing and on various symptoms with occlusal discrepancy between habitual occlusal position
and muscular position [1-3]. This case may help us understand the relationship between
occlusion and limb motor skills.
CASE PRESENTATION
A 68-year-old woman presented with the complaint of food getting stuck in her upper right
premolar. She reported that three months earlier she had lost the ability to pinch with her right
thumb and forefinger and had been seen by an orthopedic surgeon who was diagnosed with a
median nerve palsy of unknown etiology (Fig. 1).
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Torii, K. (2023). Occlusal Analysis and Management of a Patient with Median Nerve Palsy of Unknown Etiology: A Case Report. British Journal of
Healthcare and Medical Research, Vol -10(4). 264-269.
URL: http://dx.doi.org/10.14738/bjhmr.104.15366
Figure 1: Median nerve palsy of right index finger and thumb
The patient's medical history included hypertension and taking medication. The patient had 25
teeth and was missing the mandibular left and right second molars and the maxillary right
second molars. All but five mandibular anterior teeth and the right first premolar had
undergone crown restoration (Fig. 2).
Figure 2: Lower and upper dental arches
No abnormalities in the temporomandibular joint (TMJ) were observed on the computed
tomography images taken in the habitual occlusal position (HOP) at the initial consultation (Fig.
3).
Figure 3: Bilateral tomographic images of temporomandibular joint
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British Journal of Healthcare and Medical Research (BJHMR) Vol 10, Issue 4, August- 2023
Services for Science and Education – United Kingdom
The maximum mouth opening was 47 mm, the opening was straight, and no tenderness was
observed in the masticatory muscles, trapezius, and sternocleidomastoid on palpation. At the
first visit, the HOP record was obtained using a vinyl polysiloxane bite registration material
(Exabite, GC, Tokyo, Japan), while the patient was seated upright with her jaw voluntarily
closed. The bite force was then measured at the first molars using an occlusal force meter (MPM
3000, NIHON KOHDEN, Tokyo, Japan). Three measurements performed on each side after
asking the patient to bite as strongly as possible. The statistical differences between mean
values were evaluated using a t-test. The mean value was 37 kg on the right side and 13.3 kg on
the left side, respectively. The statistical difference between the mean values was significant
(p<0.005). Subsequently, the upper and lower impression were obtained, and dental models
were fabricated. An anterior flat biteplate was fabricated on the upper model using self-curing
acrylic resin (Ortho-fast, GC, Tokyo, Japan). At the second visit, the patient wore the bite plate
for 5 min and the bite plate-induced occlusal position (BPOP) record was obtained, using the
same material as used for obtaining the HOP record. A BPOP wax record was obtained using
wax registration material (Bite wafer, Kerr US, Romulus, MI, U.S.A.) in the previously described
manner. The upper and lower models were mounted on an articulator with the BPOP wax
record. Regarding the occlusion of the upper and lower models, the right molar was not
occlusion (Fig.4).
Figure 4: The arrow indicates the gap between upper and lower molars on the right side.
Figure 5: Recorded premature occlusal contact
Premature occlusal contact was recognized on the left second premolar (Fig. 5). To examine the
direction from the BPOP to HOP, two- dimensional measurements were performed on a
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Torii, K. (2023). Occlusal Analysis and Management of a Patient with Median Nerve Palsy of Unknown Etiology: A Case Report. British Journal of
Healthcare and Medical Research, Vol -10(4). 264-269.
URL: http://dx.doi.org/10.14738/bjhmr.104.15366
modified articulator using previous records. The recording disc was approximately the same as
that of a condyle of TMJ. Therefore, the shift was caused by one of the condyles (Fig. 6).
Figure 6: Recorded the habitual occlusal position (HOP) and the bite plate- induced occlusal
position (BPOP). The arrow indicates the shift from BPOP to HOP.
Subsequently, to examine the direction from BPOP to HOP, three-dimensional measurements
near the first molars were performed with the modified articulator using the polysiloxane
records. Her HOP deviated posterolaterally to the left from BPOP (Fig. 7).
Figure 7: Three dimensional records. The arrows indicate the shift from the bite plate-induced
occlusal position (B) to the habitual occlusal position (H).
Occlusal adjustment was performed on the models mounted the articulator according occlusal
position correcting therapy [4]. Then, the adjustment site on the model was transferred to a
template, and the template was adapted to the teeth in the mouth for occlusal adjustment.
Occlusal adjustment was performed five times until bilateral occlusal contacts were obtained
(Fig. 8).
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British Journal of Healthcare and Medical Research (BJHMR) Vol 10, Issue 4, August- 2023
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After the occlusal adjustment was completed, the occlusal force was measured. The mean value
was 20 kg on the right side and 21 kg on the left side with no statistical difference. Statistical
difference between before and after the occlusal adjustment was observed only on the right
side (p<0.005). The patient's right hand median nerve palsy disappeared (Fig. 9).
Figure 8: Confirmation of bilateral occlusal contacts
Figure 9: Disappearance of median nerve palsy
DISCUSSION
It has been reported that various symptoms appear due to occlusal discrepancy between
habitual occlusal position and muscular position (3). However, the patient in this case did not
show any symptoms of the temporomandibular system. Moreover, although there is report that
the right occlusal force was weak when the right posterior teeth was not occluded (1),
extremely strong occlusal force was shown in this case. How should we think about this? In the
case of this patient, the right posterior teeth were brought into occlusal contact and
unconsciously exerted an extremely strong occlusal force. Therefore, it is thought that the
molars on both sides were in contact with each other in the muscular position, and that the
temporomandibular system was functioning normally without any symptoms. However, if such
a state in which an abnormally strong bite force must be constantly exerted continues, the
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Torii, K. (2023). Occlusal Analysis and Management of a Patient with Median Nerve Palsy of Unknown Etiology: A Case Report. British Journal of
Healthcare and Medical Research, Vol -10(4). 264-269.
URL: http://dx.doi.org/10.14738/bjhmr.104.15366
motor nucleus of the trigeminal nerve will be abnormally excited. It was considered that the
activity of the trigeminal spinal cord nucleus was suppressed, resulting median nerve palsy.
We learned from this case that even if there is the discrepancy between the habitual occlusal
position and the muscular position, symptoms may not appear in the temporomandibular
system, and abnormalities may appear in other body parts.
ACKNOWLEGEMENT
Written consent was obtained from the patient prior to the publication of this study.
References
1. Torii K (2022) Occlusal analysis and management of a patient with unilateral high-frequency hearing
impairment and stiff shoulder: A case report. Brit J Health & Med Res 9(6):168-175.
2. Torii K (2011) Longitudinal course of temporomandibular joint sounds in Japanese children and
adolescents. Head Face Med. 7:17.
3. Torii K (2018) Occlusal disease. J Dent Health & Res 1:2.
4. Torii K (2018) Occlusal position correcting therapy for temporomandibular disorders. EC Dental Science,
2018;17:168-176.