Shape, height, and location of the lingula for sagittal ramus osteotomy in Thais.

This study aims to investigate the shape, height, and location of the lingula in relation to surrounding structures for sagittal ramus osteotomy. Dried Thai mandibles were studied and compared with other races. From both sides of 92 mandibles, the shape of the lingula was classified into triangular, truncated, nodular, or assimilated types. Of 92 mandibles, 146 sides with at least a premolar and a molar on the same side were selected for distance measurement. Height of the lingula was measured from the lingular tip to the mandibular foramen. The location was determined by five distances from the lingular tip to: the anterior and the posterior borders of the mandibular ramus, the mandibular notch, the distal surface of the mandibular second molar, and the occlusal plane. The results showed that truncated lingulae were most frequently found (46.2%) and most appeared to be bilateral (71.7%). Triangular, nodular, and assimilated shapes presented in 29.9%, 19.6%, and 4.3%, respectively. The mean lingular height was 8.2 +/- 2.3 mm. The lingula was located at 20.6 +/- 3.5 mm from the anterior border of the mandibular ramus and 16.6 +/- 2.9 mm from the mandibular notch. In the majority of the mandibles studied, the lingula was located above the occlusal plane. In conclusion, the shape and metric characteristics of the lingula in relation to surrounding structures in Thais vary from other races. All parameters associated with the lingula should be considered for sagittal ramus osteotomy to avoid intraoperative complications.

Anatomical considerations of the deep peroneal nerve for biopsy of the proximal fibula in Thais.

The present research aims to study the anatomical relationship between the deep peroneal nerve and the neighboring structures in the proximal fibula of Thais, with special regard to define the boundaries of a "safe" area when performing a biopsy of the proximal fibula. The proximal parts of 118 legs of 59 formalin-embalmed adult cadavers (31 males, 28 females) were investigated. The distance from the apex of the fibular head to the point of origin of the deep peroneal nerve, the distance from the most lateral prominence of the fibular head to the anterior intermuscular septum, and the angle between the deep peroneal nerve and the fibula axis were measured. The results showed that the mean distances from the apex of the fibular head to the point of origin of the deep peroneal nerve was 28.4 +/- 4.8 mm and from the most lateral prominence of the fibular head to the anterior intermuscular septum was 14.9 +/- 2.0 mm. The mean angle between the deep peroneal nerve and the fibular axis was 28.1 degrees +/- 7.2 degrees . In conclusion, these findings suggest that a "safe" area for bone biopsy in the proximal fibula of Thais is palpable anterior to the fibular head and downward laterally, not lower than 28 mm or 8% of the fibular length and from the most lateral prominence transverse medially not further than 14 mm. The inferior boundary of this area is an oblique line of the deep peroneal nerve about 28 degrees from the fibular axis.

Supraorbital Notch/Foramen, Infraorbital Foramen and Mental Foramen in Thais: anthropometric measurements and surgical relevance.

OBJECTIVE: To determine the morphology and the locations of the SupraOrbital Notch/Foramen (SON/F), InfraOrbital Foramen (IOF), and Mental Foramen (MF) relative to frequently encountered surgical landmarks. MATERIAL AND METHOD: One hundred and six Thai adult skulls were investigated. RESULTS: Mean horizontal widths of SON, SOF, IOF and MF were 4.31 +/- 1.61 mm, 2.81 +/- 0.62 mm, 3.35 +/- 0.62 mm and 2.80 +/- 0.70 mm, respectively. The SON/F was situated 25.14 +/- 4.29 mm lateral to the nasal midline, 26.57 +/- 3.92 mm medial to the temporal crest of the frontal bone and 3.15 +/- 1.29 mm superior to the supraorbital rim. The IOF was 28.43 +/- 2.29 mm lateral to the maxillary midline, 9.23 +/- 2.03 mm below the infraorbital rim and 2.15 +/- 1.67 mm medial to the zygomaticomaxillary suture. Mean vertical distances from the IOF to the SOF and to occlusal plane of the upper teeth were 44.95 +/- 2.96 mm and 42.52 +/- 3.89 mm, respectively. The IOF was frequently found in the same vertical line with the second upper premolar and its usual direction of opening pointed downward medially. The MF was a mean of 28.52 +/- 2.15 mm lateral to the symphysis menti and most commonly observed in line with the second lower premolar. Its usual direction of opening was in a posterosuperior direction. CONCLUSION: The results of the present study may assist surgeons to localize important maxillofacial neurovascular bundles passing through these foramina in facilitating surgical, local anesthetic and other invasive procedures.

Mental foramen in Thais: an anatomical variation related to gender and side.

Sixty-nine adult mandibles (45 male, 24 female) of Thai dry skulls were assessed to determine the size, the orientation and the location of the mental foramen (MF) related to gender and side. The results showed that the usual direction of exit of the MF was in a posterosuperior direction. The most common location of the MF was bilaterally symmetrical and located on the same vertical line with the long axis of the lower second premolar. The mean distances from the MF to the symphysis menti (A), to the posterior border of the mandibular ramus (P), to the lower border of the mandible (mb) and to the buccal cusp tip of the second premolar (cm) were 28.83, 68.85, 14.88 and 24.27 mm, respectively. The mean distances from the alveolar bone crest across the MF to the lower border of the mandible (ab) was 29.97 mm. The mean distance from the buccal cusp tip of the second premolar through the long axis of the clinical crown to the lower border of the mandible (cb) was 39.18 mm. No measurements varied according to the sides (P > 0.05). In contrast, gender differences were significant in all measurements with the longer distances in males (P < 0.05). The mean ratios of A/(A + P), mb/ab and cm/cb in all subjects were 0.30, 0.50 and 0.62, respectively. The values of the three ratios were nearly equal in males and females. Our results may assist surgeons to localize important maxillofacial neurovascular bundles passing through the MF in avoiding complication from local anesthetic, surgical and other invasive procedures.

Anatomy of greater palatine foramen and canal and pterygopalatine fossa in Thais: considerations for maxillary nerve block.

This study aims to investigate the anatomy of the greater palatine foramen (GPF), greater palatine canal (GPC) and pterygopalatine fossa (PPF) with special reference to the blockage of the maxillary nerve. A correlation between the length of GPC and PPF and the heights of the orbit and the maxilla was also studied using simple linear regression analysis. The morphology of the GPF, GPC and PPF as well as heights of the orbit and the maxilla were assessed in 105 Thai skulls. The thickness of the mucosa over the GPF was also measured from the dissection of 55 cadavers. The results showed that most GPF appeared as an oval foramen located at the palatal aspect of the upper third molar. The GPF was 16.2+/-1.3 mm lateral to the median sagittal plane of the hard palate, 2.1+/-1.3 mm anterior to the posterior border of the hard palate and 5.1+/-1.3 mm from the greatest concavity of the distolateral margin of the hard palate. The mean length of GPC and PPF was 29.7+/-4.2 mm. The mean angles of the GPC in relation to the hard palate and the vertical plane were 57.9+/-5.8 degrees and 6.7+/-5.2 degrees , respectively. In attempting to insert a needle to reach the foramen rotundum through the GPF, 31.7% passed into the orbit while 8.7% passed into the brain. The mean thickness of the mucosa over GPF was 6.7+/-2.3 mm. Two models for estimating the depth of needle injection in maxillary nerve block have been developed as follows: Length of GPC and PPF=19.038+0.314 (orbital height) and length of GPC and PPF=21.204+0.187 (maxillary height). The calculated length combined with the mucosal thickness was the estimated depth of needle injection. In conclusion, our results concerning the GPF, GPC and PPF will provide the useful reference for clinicians to anesthetize the maxillary nerve with a greater degree of success.

Clinical anatomy of the posterior maxilla pertaining to Le Fort I osteotomy in Thais.

This article studies the anatomy of the posterior maxilla pertaining to bone-cut design of Le Fort I osteotomy to avoid the injury to the descending palatine artery in Thais. Fifty-five skulls (38 males, 17 females) were assessed for the anatomical landmarks by a combination of direct inspection, computerized imaging, and computed tomography scan analysis. The results showed that 27.28% of the pterygomaxillary junction (PMJ) became synostosis. The mean heights of the PMJ, posterior maxilla, and maxillary tuberosity were 15.14 +/- 2.46 mm, 22.51 +/- 3.50 mm, and 7.45 +/- 2.76 mm, respectively. The mean length of the medial sinus wall measuring from the piriform rim to the descending palatine canal at the Le Fort I level was 34.40 +/- 2.96 mm. The mean widths of the posterior incision of Le Fort I osteotomy at the maxillary tuberosity and PMJ were 20.38 +/- 2.82 mm and 11.60 +/- 1.57 mm. The mean length of the posterior maxilla was 27.18 +/- 2.49 mm. Distances from the greater palatine foramen to the maxillary tuberosity incision and PMJ incision were 1.76 +/- 1.12 mm and 3.59 +/- 1.40 mm. The mean angle between the descending palatine canal and the hard palate was 57.33 +/- 4.54 degrees . There were no significant differences in any measurements between sides and genders, except the pterygoid process width and posterior maxilla length of males were longer than those of females (P < 0.05). This study could provide better understanding of the posterior maxillary anatomy that is important for the bone-cut design of Le Fort I osteotomy to avoid excessive intraoperative and postoperative hemorrhage including ischemia of the mobilized maxilla.