Koichiro Ihara

Measurement of Labio-lingual Bone Thickness in the Mandibular Interforaminal Region: a Pilot Cadaveric Study

Abstract Objective: To measure the labio-lingual bone thickness in the mandibular interforaminal region to facilitate safe implant placement in Asian patients. Materials and Methods: Labio-lingual bone thicknesses were measured at 16 points in the interforaminal region of mandibles from 10 Japanese cadavers. Results: Mean thickness ranged from 9.23 to 11.80 mm with a minimal value of 5.23 mm in the midline region. No significant difference was noted between dentate and edentulous specimens. Conclusion: The thinnest region is medially located and is narrower than the minimum required for a 3.75 mm diameter endosseous implant.

Masticatory Function after jaw Resection and Rehabilitation with Dental Implants

Abstract Objective : To assess masticatory function after jaw resection and prosthodontic treatment using implants and to evaluate the effectiveness of such treatment. Patients and Methods : Masticatory function was investigated in 21 patients who underwent jaw resection and 23 non-resection patients rehabilitated with dental implants. Twenty-eight volunteers with natural dentition acted as control subjects. Masticatory function was assessed by 4 tests and the 3 groups were compared. Results : No significant differences in all tests were found between the control group and the non-resection patients. There were significant differences in masseter muscle action potential amplitudes between patients who underwent jaw resection and the other groups. No specificity was seen in the factor score distribution in the principal component analysis. Conclusion : Masticatory function can be restored to almost normal levels by appropriate reconstruction of soft tissues combined with prosthodontic treatment with dental implants, even for patients undergoing jaw resection.

Long-term Observation of Masticatory Function and Neurosensory Disturbance after Mandibular Correction by Bilateral Sagittal Split Ramus Osteotomy

Bilateral sagittal split ramus osteotomy (SSRO) is commonly used to treat jaw deformities. The purpose of this study was to evaluate the postoperative course of patients that underwent SSRO from before operation to fiveyearsafteroperation.A total of 41 female patients with jaw deformities underwent SSRO and their masticatory functions and neurosensory recovery were examined with appropriate indicators pre-and posto-peratively. The control group consisted of 24 females with individual normal occlusion assessed as having normal masticatory function.The skeletal stability was well maintained for five years after the operation.The result was that masticatory function following orthognathic surgery showed a decline at one month after surgery, but gradually improved. Especially, the values of occlusal contact area and occlusal force reached the maximum level at four years after surgery. There were no significant differences between the levels of the patients and control subjects three to five years after surgery. The score of the Helkimo index for temporomandibular dysfunctions at one year after surgery was lower than that before surgery. However, this score increased from three years after surgery.The S-W sensory test was used for clinical sensory testing of the lower labiomental area, and differences in degree of sensory disturbance were statistically analyzed. Most patients experienced a marked sensory disturbance in the immediate postoperative period. These symptoms dramatically improved within one year after surgery. However, the result showed that recovery of sensation tended to be limited to within one year after surgery.

Clinicopathological study on three cases of cemento-ossifying fibroma.

セメント質骨形成線維腫3例について臨床病理学的に検討した。性別は, 3例すべて男性で, 初診時年齢は14歳, 43歳, 47歳 (平均年齢: 34.7歳) であった。3例とも下顎臼歯部に発生していた。X線所見では, すべて境界明瞭な病変で, X線透過像とX線不透過像の混在例であった。治療法は, 3例すべてに対し腫瘍摘出術を行い, 自家腸骨海綿骨移植を追加施行した。術後経過はすべて良好で, 再発例は認めていない。摘出した腫瘍は被膜を欠いており, 線維性組織中に種々の成熟度を示すセメント質様ないし骨様組織の形成が認められた。

Clinicostatistical analysis of 56 cases of odontogenic tumors.

1981年10月から2002年6月までの20年8か月間に, 奈良県立医科大学口腔外科において経験した135例の歯原性腫瘍について, 1992年のWHO分類に基づき臨床統計的検討を行った。組織型別ではエナメル上皮腫が56例と最も多く, 続いて集合性歯牙腫が41例, 複雑性歯牙腫が18例であり, 残り良性腫瘍が17例, 悪性腫瘍が3例であった。初診時年齢は5歳から77歳で平均年齢は29.8歳であった。性別では, 男性71例, 女性64例で, 男女比は1.1: 1であった。部位別は上顎が45例, 下顎が90例であった。エナメル上皮腫, 集合性歯牙腫, 複雑性歯牙腫の好発部位は, それぞれ下顎臼歯部, 上顎前歯部, 下顎臼歯部であった。主訴の大部分が精査依頼であったが, エナメル上皮腫においては腫脹が最も多かった。エナメル上皮腫におけるX線所見は, 多房性が22例, 単房性が14例, 蜂巣状が3例であった。関連埋伏歯は全症例中39例みられた。隣在歯の歯根吸収はエナメル上皮腫に24例みられた。治療法は摘出が90例, 開窓が16例, 下顎区域切除が12例, 下顎辺縁切除が3例, 上顎部分切除が3例であった。再発は一次症例ではエナメル上皮腫に3例, 二次症例ではエナメル上皮腫に3例, 歯原性粘液腫に1例と悪性エナメル上皮腫に1例に認められた。