Shogo Kikuta

Intraoral vertico-sagittal ramus osteotomy: modification of the L-shaped osteotomy

The sagittal split ramus osteotomy and intraoral vertical ramus osteotomy carry the potential risk of postoperative nerve paralysis, bleeding, and fracture and dislocation of the condyle. In 1992, Choung first described the intraoral vertico-sagittal ramus osteotomy for the purpose of avoiding postoperative dislocation of the condyle. However, there is still potential for damaging the inferior alveolar nerve and maxillary artery with this technique. The authors have developed a modified technique to minimize these risks. An evaluation of surgical experience and patient outcomes with the use of this technique is presented herein. One hundred twenty-two sides in 97 Japanese patients diagnosed with a jaw deformity were analyzed. This technique includes a horizontal osteotomy that is performed at a higher position than in the original Choung procedure. Intraoperatively, there was no unexpected bleeding from the operative site. Proximal segment dislocation from the glenoid fossa was observed on one side (0.82%). Non-union of the osteotomy was not observed in any patient. Intraoperative fracture of the coronoid process occurred in 2.46%, but none necessitated treatment of the fracture. Nerve dysfunction was found in 2.46% at the 12-month postoperative follow-up. The modified technique presented herein was developed to reduce postoperative nerve dysfunction and intraoperative hemorrhage.

A Novel Method for Observation of the Mandibular Foramen: Application to a Better Understanding of Dental Anatomy

Cone‐beam computed tomography gives us much useful morphological information about the mandibular bone. Many studies of the mandible include findings from this technique. However, there have been no endoscopic studies of the mandible. Sixteen sides of eight dry mandibles resected from cadavers (age range 38–83 years) were examined by endoscopy. The head of the endoscope was 2.0 mm in diameter. We examined the mandibular foramen, lingula, mylohyoid groove, and mandibular canal. The mylohyoid grooves showed variations such as double grooves and canals. The mandibular lingula was located superior or medial to the the mandibular foramen. In a single case, the medial wall inside the mandibular canal showed a porous surface. The retromolar canal was observed in three sides. None of the images in the present study have been seen in other studies. Observation of the retromolar canal from the mandibular canal in particular can help dental students as well as oral and maxillofacial surgeons to understand its morphology. Anat Rec, 2017.

Adenosquamous Carcinoma in the Midline Dorsum of the Tongue: A Rare Case Report

Adenosquamous carcinoma (ASC) is a rare malignant tumor of the oral and maxillofacial region that displays histologic features of both adenocarcinoma and squamous cell carcinoma. ASC in the midline dorsum of the tongue is exceedingly rare. We report the case of a 48-year-old man who presented with a painless mass in the midline dorsum of the tongue. Although the case was diagnosed as adenocarcinoma by biopsy, a final diagnosis of ASC was established after surgery. Ten months after the patients initial visit, no recurrence or metastasis has been noted. ASC in the middle dorsum of the tongue is exceedingly rare, and no examples have been reported hitherto.

Anatomical Study of the Lingual Nerve and Inferior Alveolar Nerve in the Pterygomandibular Space: Complications of the Inferior Alveolar Nerve Block

The inferior alveolar nerve block (IANB) procedure delivers anesthetics to the pterygomandibular space through which the lingual nerve (LN) and inferior alveolar nerve (IAN) travel. Injury to the LN has been reported more often than injury to the IAN. However, the number of anatomical studies of LN injury is limited. We aimed to establish evidence by investigating LN and IAN anatomy at the level of the mandibular foramen (MF). Forty-four sides from 22 Caucasian cadaveric heads (16 fresh-frozen and six formalin-fixed cadavers) were used in this study. The LN and IAN were laterally dissected, and the diameter and the distance between the two nerves were measured at the level of the MF. The mean diameters of the LN and IAN were 2.57 mm and 2.53 mm in fresh-frozen specimens and 2.97 mm and 2.93 mm in formalin-fixed specimens, respectively. The mean diameters of the LN and IAN in all the specimens were 2.65 mm and 2.64 mm. The distance between the posterior edge of the LN and anterior edge of the IAN at the level of the MF ranged from 1.62 to 8.36 mm with a mean of 5.33 ± 1.88 mm. These findings could elucidate the risk of LN injury during the IANB procedure.

The Incisive Canal: A Comprehensive Review

The incisive canal, also known as the nasopalatine canal, is an interosseous conduit through the anterior maxilla connecting the oral and nasal cavities. Within this canal lies the nasopalatine nerve and the vascular anastomosis between the greater palatine and sphenopalatine arteries. The embryology of the canal has led to interesting theories explaining its function. Efforts have been made to describe the morphometrics of the incisive canal by radiologic evaluation across sex and ethnicities. This paper aims to review the current literature on the embryology, anatomy, and clinical relevance of the incisive canal.

Clinical Application of the IllumiScan Fluorescence Visualization Device in Detecting Oral Mucosal Lesions

Objective: Fluorescence visualization devices are screening devices that can be used to examine lesions of the oral mucosa non-invasively. We observed oral squamous cell carcinoma (OSCC) and leukoplakia using the IllumiScan (Shofu, Kyoto, Japan) fluorescence visualization device and examined its usefulness and characteristics. Methods: We investigated 31 OSCC and nine leukoplakia in patients who were examined using the IllumiScan and treated in our department from January 2017 to February 2018. Images taken with the IllumiScan were analyzed using image analysis software. We also examined the lesions using narrowband imaging (NBI). Additionally, the IllumiScan and NBI images and the non-stained areas of iodine staining method (IOM) were visually evaluated. Results: The average luminance of OSCC in the keratinized mucosa was significantly lower than that of OSCC in non-keratinized mucosa. The average luminance of OSCC was significantly lower than that of leukoplakia. Even in keratinized mucosa where IOM is impossible to use, the OSCC lesion exhibited fluorescence visualization loss. Conclusion: The application of the fluorescence visualization device to the oral mucosa may be useful for distinguishing between cancer and normal areas and can be used to detect OSCC in the keratinized mucosa. The use of the IllumiScan in combination with other conventional screening methods may lead to a better diagnosis.

Activation of cathepsin L contributes to the irreversible depolarization induced by oxygen and glucose deprivation in rat hippocampal CA1 neurons

Oxygen and glucose deprivation (OGD) elicits a rapid and irreversible depolarization with a latency of ∼5min in intracellular recordings of hippocampal CA1 neurons in rat slice preparations. In the present study, we examined the role of cathepsin L in the OGD-induced depolarization. OGD-induced depolarizations were irreversible as no recovery of membrane potential was observed. The membrane potential reached 0mV when oxygen and glucose were reintroduced immediately after the onset of the OGD-induced rapid depolarization. The OGD-induced depolarizations became reversible when the slice preparations were pre-incubated with cathepsin L inhibitors (types I and IV at 0.3-2nM and 0.3-30nM, respectively). Moreover, pre-incubation with these cathepsin inhibitors prevented the morphological changes, including swelling of the cell soma and fragmentation of dendrites, observed in control neurons after OGD. These findings suggest that the activation of cathepsin L contributes to the irreversible depolarization produced by OGD.

Undetected Small Accessory Mental Foramina Using Cone-Beam Computed Tomography

Introduction The accessory foramina could not be identified on some imaging modalities such as surface-rendered images. The purpose of this study was to investigate the ability of surface-rendered images in detecting these foramina. Materials and methods We analyzed 20 accessory mental foramina (AMF) in nine mandibles removed from cadavers with cone-beam computed tomography (CBCT) and assessed in surface-rendered images. All AMF were divided into three groups depending on their visibility. Results Group 1 included AMF that were clearly visible as foramina, Group 2 were not clearly visible but could be recognized with concave parts, and Group 3 were not visible and the smooth surface of the bone was observed. Group 1 ranged from 1.3 to 5.1 mm2, Group 2 from 0.3 to 3.8 mm2, and Group 3 from 0.2 to 1.1 mm2. A statistically significant difference in the mean size between Groups 1 and 3 was observed. Even if the AMF are smaller (e.g., 1 mm in diameter), they should still be avoided to prevent injury. Conclusions The clinician should be aware that smaller foramina might not be detected on these images.

Multiple accessory foramina of the mandibular ramus: risk factor for oral surgery

A 27-year-old female was referred to our hospital with a chief complaint of removal of an impacted right mandibular third molar. Panoramic radiography showed two small circular radiolucencies on the right mandibular ramus. Computed tomography revealed that one of the radiolucencies was an accessory foramen located lateral to the mandibular ramus, and the other radiolucency was an accessory foramen located medial to the ramus; it was also connected to the mylohyoid groove. Continuity with the mandibular canal was confirmed for both accessory foramina. After explaining the risks of extraction, the patient decided against surgery and the impacted tooth was left in situ. Most patients have at least one or more accessory foramina in the mandible; however, accessory foramina of the lateral aspect of the mandibular ramus have not been reported. The high resolution of cone-beam computed tomography and three-dimensional reconstructed images enable improved detection of accessory foramina. Therefore, additional accessory foramina that are similar to those found in the present case could be found in the future using such imaging modalities.