The Prevalence of Infraorbital Canal Dehiscence in Thai Cadaveric Skull : A Preliminary Report

Abstract

Background : The infraorbital nerve is one of the branches of the maxillary division of the trigeminal nerve.  It lies in the infraorbital canal forming the roof of maxillary sinus.  The infraorbital canal dehiscence may have a cance to disturb the infraorbital nerve more than the non-dehiscence and could be a cause of the facial pain.  Many investigators have been reported the prevalence of the infraorbital canal dehiscence in many countries but not in Thailand.  The purpose of this investigation is to study the prevalence of infraorbital canal dehiscence and decribe the morphology of the infraorbital canal in Thai cadavers.

Objective : To study the prevalence of the infraorbital canal dehiscance in Thai cadaveric skull and described the morphology of the i infraorbital canal in Thai cadavers.

Design : A descriptive study.

Setting : The study was carried out at the Department of Anatomy and the Department of Otolaryngology, Faculty of Medicine, Khon Kaen University, Kkhon Kaen, Thailand.

Subjects : The study included 80 specimens of half head and face from formalin-embalmed cadavers, 36-84 years of age (average 62 years(.  They could be indentified for genders by only 62 specimens; male 9 specimens and female 13 specimens.

Setting :

1. To study the infraorbital canal dehiscence that convering the infraorbital nerve as the following aspects :

1.1     The number of the sample that found dehiscence, comparing male to female as well as right to left sides

1.2     The site of the wall of the infraorbital canal which occurred dehiscence.

1.3     To measure the width and the length of dehiscence of the infraorbital canal.

2. To observe the type of infraorbital canal which occupied infraorbital nerve and measure the depth of the canal on the roof of the maxillary sinus.

3. To study the dehiscence of the bone that covers the superior alveolar nerve which gives the branch to supply the upper teeth as the following as pects :

3.1     The number of the sample with dehiscence.

3.2     The site of the wall of the canal that found dehiscence.

3.3     To measure the width and the length of dehiscence.

1. To measure the length between infraorbital foramen and infraorbital rim.
2. To study the number of the sample that dehiscence bone occxured around both infraorbital and superior alveolar nerves.

Results:

1. Infraorbital canal dehiscence

1.1     The infraorbital canal dehiscence was found in 15 specimens from 79 specimens of samples (1 specimen was broken before study). The sex difference and dehiscence was 7 specimens out of 61 in male and 4 out of 61 specimens in female from 61 specimens that can identify the sex.  In aspect of the side, we found that dehiscence in the right side was 7 specimens and the left side was 8 specimens.

1.2      The number of the side of the wall of infraorbital canal dehiscence at  the inferior, lateral, medial, infraorbital and infraorbital wall were 5,4,3,2 and 1 out of 15 specimens respectively.

1.3     The width of dehiscence of infraorbital canal was 0.5-3.5 mm., means 1.45 mm.  The ratio on the width of infraorbital canal and the diameter of infraorbital nerve was 10-100%, means 48%.  The length of the infraorbital canal dehiscence was 2.0-11.0 mm., means 5.09 mm.

1. The number of three types of infraorbital canal dehiscence were 1, 5 and 9 specimens of  the first, secon and third type respectively, whereas the non-dehiscence were 12, 26 and 26 sfpecimens respectively.  Moreover the depth of the canal on the roof of maxillary sinus was 0 mm., 2.0-8.0 mm. (mean 4.6), and 3.5-12 mm. (mean 6.9) of the first, second and third type respectively.
2. Superior alveolar nerve dehiscence

3.1     The superior alveolar nerve dehiscence was found 36 specimens out of 79 specimens.

3.2     The number of the site of the wall of superior alveolar nerve dehiscence at the lateral, inferior, medial anterior, infraorbital and inferomedial wall were 13, 9, 4, 3, 1 and 1 specimes respectively.

3.3     The width of dehiscence of superior alveolar nerve was 0.5-2.5 mm., mean 1.29 mm. The ratio on the width of the bone cover the superior alveolar nerve and the diameter of superior alveolar nerve was 40-100 %, means 96%.  The length of the dehiscence was 1.0-14.0 mm., mean 5.97 mm.

1. The distance from infraorbital foramen to the infraorbital rim of the orbit was 5.5-11.0 mm., mean 8.27 mm. Indehiscence group of the infraorbital canal and 1.0-11.0 mm., mean 7.49 mm. In non-dehiscence group.
2. Only one specimen of maxillary sinus that was found with dehiscence covering both infraorbital and superior alveolar nerve.

Conclusions : The results of this observation is the basic knowledge of the prevalence of the infraorbital canal dehiscence in Thai cadavers.  The infraorbital canal dehiscence was found 15 out of 79 of cases.  The dehiscence was found in femal more than male but there was no significance difference between right and left sides.  Among the types of infraorbital canal, the most prevalence was type 3 (total prominence type)j.  The knowledge from this observation is useful in medical sciences such as help to explain in diagnosis of the cause of facial pain.  One must be careful in performing antrostomy of the maxillary sinus.

Key words : Dehiscence, infraorbital canal, infraorbital foramen, infraorbital nerve