Alternative Landmarks of the Mandibular Foramen to Prevent Nerve Injury during Ramus Surgery.

OBJECTIVE: To investigate the mandibular foramen (MF) position in relation to other bony landmarks on the mandibular ramus (MR) to better understand the anatomical landmark during the ramus surgery. MATERIAL AND METHOD: Ninety-two adult mandibles were studied by measuring four linear parameters: AB, the distance from the posterior limit of the MF (point A) to the posterior border of the MR (point B), BC, the MR width (Point C was located at the anterior border of the MR), DE, the distance from the lingula tip (the highest and the most anterior limit of the MF) (point D) to the mandibular notch (point E), and the MR height (EF, point F was located at the mandibular inferior border). Lines BC and EF were drawn through points A and D and parallel to the inferior and posterior borders of the mandible, respectively. These measurements were analyzed to determine the mean parameters related to the MF location. RESULTS: The mean lengths of AB, BC, DE, and EF were 12.7 ± 2.3, 35.0 ± 4.0, 17.5 ± 3.5, and 52.7 ± 5.2 mm, respectively. The ratios between AB/BC and DE/EF were 0.36 ± 0.05 and 0.33 ± 0.05, respectively. This study indicated that the MF located slightly anterior to the posterior third of the MR width and at the superior third of the MR height. CONCLUSION: Anatomical consideration of this area is useful to prevent neurovascular injury when performing the bony cut made in a ramus osteotomy; however, pre-operative examinations with appropriate radiographic analysis are also recommended.

Occurrence of the foramen of Vesalius and its morphometry relevant to clinical consideration.

All 377 dry skulls were examined for the occurrence and morphometry of the foramen of Vesalius (FV) both in the middle cranial fossa and at the extracranial view of the skull base. There were 25.9% and 10.9% of FV found at the extracranial view of the skull base and in the middle cranial fossa, respectively. Total patent FV were 16.1% (11.9% unilaterally and 4.2% bilaterally). Most FV were found in male and on the left side. Comparatively, FV at the extracranial view of the skull base had a larger maximum diameter. The distance between FV and the foramen ovale (FO) was as short as 2.05 ± 1.09 mm measured at the extracranial view of the skull base. In conclusion, although the existence of FV is inconstant, its occurrence could not be negligible. The proximity of FV to FO should remind neurosurgeons to be cautious when performing the surgical approach through FO.

Anatomical considerations of the Thai fibula used as a fibula osteocutaneous free flap in mandibular reconstruction and dental implant placement.

OBJECTIVE: Although the fibula osteocutaneous free flap has many proven advantages in restoring mandibular defects, the dimension of available fibula is one of its limitations. The present study aimed to investigate the suitability of dimensions and the quality of harvested fibulae for mandibular reconstruction and dental implant placement in Thais. MATERIAL AND METHOD: One hundred fourteen fibulae of 57 adult Thai cadavers were dissected. Total fibular length and the length of harvested fibula were measured. Dimensions of the fibula cross sections available for dental implant placement were recorded. Additionally, the cortical bone thickness and densities of cortical and spongy bones of 60 fibulae were assayed using cone beam computed tomography scan images. RESULTS: Mean total fibular length and mean length of harvested fibulae were 34.2 +/- 2.3 cm and 18.2 +/- 2.3 cm, respectively. A dental implant length of 7 to 10 mm could be placed in the fibula. The mean cortical bone thickness was 2.2 +/- 0.6 mm. The mean densities of the cortical and spongy bones were 614.4 +/- 148.8 HU and -600.6 +/- 228.7 HU, respectively. CONCLUSION: The present study suggests that, in Thais, a harvested fibula of 16 to 20 cm in length is sufficient to provide bone for reconstructing defected mandible and the dental implant placement is 7 to 10 mm in length. The mean cortical and spongy bone densities of fibula are less than that of the mandible in previous reports. The result supports the clinical experience using the fibula as donor site for the mandibular reconstruction and dental implant placement.

Infection of human gingival fibroblasts with Aggregatibacter actinomycetemcomitans: An in vitro study.

OBJECTIVE: Aggregatibacter actinomycetemcomitans is known to be a major cause of localized aggressive periodontitis. Previous research has suggested that A. actinomycetemcomitans can damage many types of host cells. There is evidence for the ability of this organism to invade endothelial and epithelial cells, but information pertaining to its potential for invading gingival fibroblasts is very limited. Internalization of bacteria is not only responsible for damaging host tissue but also a means to evade the host immune response. It was hypothesized that A. actinomycetemcomitans can invade and reside in human gingival fibroblasts (HGF). METHODS: Primary cultures of HGF were infected with A. actinomycetemcomitans at a ratio of 1:100. Bacterial internalization was determined by an antibiotic protection assay. Bacterial-fibroblast interaction was examined using phase-contrast, scanning and transmission electron microscopy. RESULTS: It was demonstrated that A. actinomycetemcomitans was internalized into HGF at an efficiency of 0.084%. Transmission electron microscopic study showed the presence of A. actinomycetemcomitans in the cytoplasm of HGF without the surrounding membrane. Scanning electron micrographs revealed the sloughing of HGF surfaces on which A. actinomycetemcomitans adhered. Rounded cells, attachment loss and damaged cells were also observed. CONCLUSIONS: It is concluded that the attachment and invasion of A. actinomycetemcomitans into human gingival fibroblasts play a role in periodontal tissue damage and may also be a means of immune evasion.

Anatomical consideration of pterion and its related references in Thai dry skulls for pterional surgical approach.

OBJECTIVE: Pterion is a crucial surgical landmark for surgical approaches to the middle meningeal artery particular lesions, and tumors in the brain. The present study aimed to analyze the types of the pterion and its location related with nearby landmarks in dry skulls. In addition, variations of pterion in sex, age, and skull side were compared. MATERIAL AND METHOD: Bilateral sides of 268 adult human Thai dry skulls were investigated Pterion types were classified as sphenoparietal, frontotemporal, epipteric, or stellate. To localize the pterion, linear distances were measured from the center of the pterion to neighboring landmarks. RESULTS: The results showed the two most common types of the pterion, the sphenoparietal (81.2%), and the epiteric (17.4%). Externally, the pterion was commonly located 38.48 +/- 4.38 mm superior to the zygomatic arch and 31.12 +/- 4.89 mm posterior to the frontozygomatic suture. Internally, it was located 38.94 +/- 3.76 mm lateral to the optic canal and 11.70 +/- 4.83 mm from the sphenoid ridge. Sex influenced the occurrence of thepterion type, while sex, skull side, and age affected its location. Mean skull thickness at the pterion was 5.13 +/- 1.67 mm. CONCLUSION: The pterion is predominantly sphenoparietal type and is typically located 39 mm superior to the zygomatic arch, 31 mm posterior to the frontozygomatic suture, 39 mm lateral to the optic canal and 12 mm from the sphenoid ridge. The data obtainedfrom the present study should be clinically useful for localizing the position of pterion.

The study of position of antilingula, midwaist of mandibular ramus and midpoint between coronoid process and gonion in relation to lingula of 92 Thai dried mandibles as potential surgical landmarks for vertical ramus osteotomy.

This study aims to investigate positions of the antilingula (AL), the midwaist of the mandibular ramus (MW) and the midpoint between the coronoid process and the gonion (MCG) in relation to the lingula of dried mandibles. Bilateral rami of 92 Thai dried mandibles were studied. The AL, the MW, the MCG and the corresponding position of the tip of lingula (L) were marked on the external aspect of the mandibular ramus. The distances from the AL, the MW and the MCG to the L were measured in the anterior-posterior and the superior-inferior planes using computerized image analysis. The results showed the AL was discernible in 80.4% of lateral mandibular rami studied. The most of the AL was found anterior-superior to the L with a maximum distance of 5.9 mm anteriorly and 8.2 mm superiorly. The MW was frequently located anterior-inferior to the L with a maximum distance of 9.3 mm anteriorly and 9.9 mm inferiorly. The majority of the MCG was found anterior-superior to the L with a maximum distance of 9.6 mm anteriorly and 8.9 mm superiorly. A 5 mm radius from the L included 84.5% of the AL, 81.5% of the MW and 79.4% of the MCG. Medians (interquartiles) of distances from the AL, the MW and the MCG to the L were 3.4 (2.3-5.0) mm, 3.8 (2.5-5.3) mm and 4.1 (2.8-5.3) mm, respectively. In conclusion, the AL was identified in 80.4% of lateral mandibular rami studied. The AL and the MCG were commonly found anterior-superior to the lingula, whereas the MW was mostly observed anterior-inferior to the lingula. Therefore, a cut made more than a 5 mm posterior or superior to these landmarks would be in 79% of cases, within a statistically safe area avoiding encroaching upon the inferior alveolar neurovascular bundle passing immediately lateral to the lingula. Although the MW and the MCG might be alternative surgical guides when the AL is absent, their use alone as surgical landmarks is not recommended.

Antibacterial activity of polysaccharide gel extract from fruit rinds of Durio zibethinus Murr. against oral pathogenic bacteria.

AIM: The polysaccharide gel (PG) extract from durian fruit rinds (Durio zibethinus Murr. "Monthong") is a pectic polysaccharide with antibacterial activity. This study aimed to investigate the in vitro antibacterial activity of PG against oral pathogens, Streptococcus mutans (S.mutans) and Aggregatibacter actinomycetemcomitans (A.actinomycetemcomitans). METHODS: The inhibitory activity of PG at 50, 100, and 150 mg/mL against S.mutans (American Tissue Culture Collection 25175) and A. actinomycetemcomitans (American Tissue Culture Collection 43718) was determined after 1- and 5-min exposure by broth macrodilution susceptibility test and scanning electron microscopy. Normal saline or culture broth medium and 0.1% chlorhexidine were used as negative and positive controls, respectively. RESULTS: For 1-min exposure, 150 mg/mL PG or 0.1% chlorhexidine significantly possessed bactericidal activity against both tested bacteria (P=0.037), while PG at 100 mg/mL possessed significant bactericidal activity against S.mutans (P=0.037) and inhibitory activity against A.actinomycetemcomitans (P=0.05). Blebs, irregular-shaped cells, and disrupted cells were found in bacteria treated with either 0.1% chlorhexidine or 50-150mg/mL PG under scanning electron microscopy. CONCLUSION: The bactericidal activity of PG at 150 mg/mL against oral bacteria at 1-min exposure suggests its possibility to be used as a natural antibacterial ingredient in oral hygiene products.

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.

Dimensional guide to harvesting the radius for orofacial reconstruction.

OBJECTIVE: To provide an accurate harvesting guide to maintain the maximum possible safe dimensions of the radius for orofacial reconstruction using the osteocutaneous radial forearm free flap. MATERIAL AND METHOD: Two hundred radii of 100 adult formalin-embalmed cadavers (52 males, 48 females) were measured. RESULTS: The mean minimum circumference of the radius measured between the pronator teres and brachioradialis insertions was 41.0 +/- 4.3 mm. At this point, the mean medio-lateral diameter was 13.4 +/- 1.6 mm. The mean of the maximum harvested length of the radius between the pronator teres and brachioradialis insertions was 81.3 +/- 10.4 mm. On the average, the maximum harvested length of the radius was 34.9% of its total length. The minimum medio-lateral diameter of the radius was consistently 1-5 mm less than 40% of its minimum circumference. There was no significant dimensional difference between sides but gender difference existed in all measurements (p < 0.001), except the maximum harvested length of the radius. CONCLUSION: The present study may be helpful to guide reconstructive surgeons for safer harvesting of the radius using the osteocutaneous radial forearm free flap to repair orofacial defects.

Dimensions for midline and paramidline andibulotomy: a radiographic study in the dentate Thai population.

BACKGROUND: Mandibulotomy is an important surgical approach of the oral cavity, oropharynx, and parapharyngeal space. OBJECTIVE: To provide dimensions for placement of bone cuts for midline (between two central incisors) and paramidline (between lateral incisor and canine) mandibulotomy. MATERIAL AND METHOD: Two hundred and sixteen periapical radiographs with the mandibular anterior teeth of 72 healthy Thai dental patients (30 males, 42 females) were selected. The angles between the long axes of the two central incisors (M) and between the lateral incisor and canine (PM) were bilaterally measured using computerized imaging. The horizontal distances (at crestal, middle, and apical levels) between the roots and the alveolar bone heights of the aforementioned teeth were also measured. RESULTS: The angles between the PM (0.00-9.26 degrees) were less convergent than those between the M (0.00-11.66 degrees) (p < 0.05). The distances between the PM were 0.60-8.03 mm, whereas those between the M were 0.47-6.63 mm (p < 0.05). Mean alveolar bone height is 15.88 +/- 1.72 mm in the canine. CONCLUSION: The paramidline mandibulotomy is done in a wider space than the midline cut and could have a better chance to avoid the extraction of a central incisor and preserve the origin of the genioglossus, geniohyoid, and digastric muscles.

Anatomical study of the maxillary artery at the pterygomaxillary fissure in a Thai population: its relationship to maxillary osteotomy.

BACKGROUND: The maxillary artery (MA) and its terminal branches are commonly damaged in the maxillary osteotomy, especially during separation of the pterygomaxillary junction (PMJ). OBJECTIVE: To evaluate the positional relationship between the MA at the pterygomaxillary fissure (PMF) and the PMJ in Thais, as well as to measure the diameter of the MA as it enters the pterygopalatine fossa (PPF) and the heights of PMJ, maxillary tuberosity and posterior maxilla. SUBJECTS AND METHOD: Both sides of 100 Thai adult cadavers (50 males and 50 females) were examined The mean age of the subjects was 64.5 +/- 12.8 years. With the lateral infratemporal approach, the branches from the third part of the MA, PMJ and posterolateral maxilla were dissected. Measurements taken included the following: First, the distance from the most inferior point of the PMJ to the most inferior position of the MA as it entered the PPF; second, the external diameter of the MA as it entered the PPF; third, vertical heights of the PMJ, maxillary tuberosity and posterior maxilla. Means, standard deviations and ranges were determined and statistical differences were calculated between sides and genders at p < 0. 05. RESULTS: The MA entered the PPF at a mean distance of 23.5 +/- 2.5 mm above the most inferior point of the PMJ. The mean external diameter of the MA as it entered the PPF was 2.8 +/- 0.6 mm. The mean heights of the PMJ, maxillary tuberosity and posterior maxilla were 19.5 +/- 2.3 mm, 6.1 +/- 2.7 mm, and 25.6 +/- 3.3 mm, respectively. There were no differences with respect to side and gender, except that the distance from the most inferior point of the PMJ to the most inferior position of the MA as it entered the PPF was longer in males than in females (p < 0.05). CONCLUSION: The mean location of the MA was 23.5 mm apart from the most inferior point of the PMJ, therefore, dysjunction of the PMJ using an osteotome with a 15-mm cutting edge may be conducted without damaging to the MA. When properly placed, the margin of safety from the superior cutting edge of the osteotome to the MA is approximately 8 mm in adults.

Effects of autoclave sterilization on properties of dental rubber dam as related to its use as barrier membrane in guided tissue regeneration.

BACKGROUND AND OBJECTIVE: Dental rubber dams (RDs) were used as barrier membranes in guided tissue regeneration for the treatment of periodontal intraosseous defects with acceptable clinical results. The aim of the present study was to investigate the effects of autoclave sterilization on properties of RD as related to its use as a barrier membrane in guided tissue regeneration. METHODS: RDs were sterilized by either an autoclave, gamma irradiation, or chemical agents and then co-cultured with human gingival fibroblasts. The cell responses to sterilized RDs were investigated by inverted phase contrast microscopy, scanning electron microscopy (SEM) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) technique. The surface alterations of the autoclaved RDs were observed under SEM. The tensile strength, tear strength and elongation at break of the autoclaved RDs were tested by a universal testing machine. RESULTS: The results from cell culture, microscopic and MTT studies showed that RDs sterilized by autoclave and gamma irradiation did not deteriorate gingival fibroblasts and provided surfaces suitable for cell attachment, whereas chemical-sterilized RDs were toxic to these cells. Ultrastructurally, surface changes from the non-autoclaved RDs, including some melted areas, small pores and folds were observed on the autoclaved RD surface. The tensile strength and tear strength of the autoclaved RDs were significantly lower than those of the non-autoclaved RDs (p = 0.042, p < 0.001, respectively). In contrast, the elongation at break of the autoclaved RDs was higher than that of the non-autoclaved RDs (p < 0.001). CONCLUSION: These results suggest that the autoclave sterilization deteriorated the physical properties of RDs even though they seemed to be compatible to the cultured human cells. Therefore, the sterilization method should be taken into consideration when RDs are utilized as barrier membranes.

Connective tissue and bacterial deposits on rubber dam sheet and ePTFE barrier membranes in guided periodontal tissue regeneration.

The aim of this study was to compare the connective tissue and bacterial deposits on rubber dam sheets and expanded polytetrafluoroethylene membranes used as barrier membranes in guided tissue regeneration for periodontal treatment. Twenty patients having intrabony defects and/or furcation defects were surgically treated by guided tissue regeneration employing either rubber dam sheets (10 patients) or expanded polytetrafluoroethylene membranes (10 patients) as barrier membranes. Four to six weeks after the first operation, membranes were retrieved from the lesion sites and processed for scanning electron microscopy. The lesion-facing surfaces of membranes were examined for the presence of connective tissue and bacterial deposits. The differences between the numbers of fields and the distributions of connective tissue and bacteria on both types of membranes were analysed by the Chi-square test at the level of 0.05 significance. The results showed a lot of fibroblasts with their secreted extracellular matrices, known as components of the connective tissue on rubber dam sheets and expanded polytetrafluoroethylene membranes. There was no significant difference in the total number of connective tissue on both types of membranes (P = 0.456). Many bacterial forms including cocci, bacilli, filaments and spirochetes with the interbacterial matrices were identified. The total number of bacteria on rubber dam sheets was statistically less than that on expanded polytetrafluoroethylene membranes (P < 0.001). The comparable number of connective tissue on both types of membranes suggests that the healing process under both types of membranes was also comparable. Therefore, the rubber dam sheet might be used as a barrier membrane in guided tissue regeneration.