Biomedical subjects

M Eba

Publications and source records attributed to M Eba.

13 recordsLinked to original sources

PubMed1990

[Stability of screw fixation following sagittal splitting osteotomy of the mandibular ramus].

Recently, sagittal splitting osteotomy of the mandibular ramus is frequently performed in orthognathic surgeries of mandibular deformities. Although the surgical technique has been established. Methods for osteosynthesis following sagittal spitting of mandibular ramus still remain unestablished. Osteosynthesis is usually achieved by circumferencial wiring, interosseous wiring or screw fixation. It is unknown which of these three methods is best suited from dynamic and clinical point of view. The author carried out a simulation study of screw fixation using acrylic resin plate models and sagittally split air-dried human mandibles. The following result were obtained: 1) In the fixation experiment using an acrylic resin plate and AO cortical bone screws, a significantly smaller displacement was recorded by S3E type fixation, compared with other modes of fixation. In determining the amount of stress required for causing displacement, S3D type fixation required a significantly larger stress, compared with other modes of fixation. 2) In the destruction experiment using an acrylic resin plate and AO cortical bone screws, the critical displacement measured was significantly smaller by S3E type fixation compared with other modes of fixation S3C type fixation required a significantly larger amount of stress to cause destruction. 3) In the fixation experiment using the air-dried human mandibles and alumina ceramic screws, a significantly smaller displacement was recorded by 2-alumina ceramic screw fixation, compared with other modes of fixation. In determining the amount of stress required for causing displacement, 3-alumina ceramic screw fixation required a larger stress, compared with other modes of fixation. 4) In the fixation experiment using the air-dried human mandible and AO cortical bone screws, a significantly smaller displacement was recorded by 2-AO cortical bone screw fixation, compared with other modes of fixation. In determining the amount of stress required for causing displacement, 3-AO cortical bone screw fixation required a larger stress, compared with the 2-AO type of fixation. The above experimental results suggest that when the sagittally split proximal cortical plate retains enough thickness for tapping, clinical application of screw fixation either with alumina ceramic or AO cortical bone screws produces an adequately high anti-displacement effect, even if only 2 screws are used. However, when stability is evaluated in terms of the resistance to stress, 3-screw fixation is considered to amply satisfy the resistance required.

Acrylic Resins↗

PubMed1989

[Measurement of oral and facial blood flow with a laser Doppler flowmeter. 4. Alteration of oral blood flow by position change].

The laser doppler flowmeter was developed by Stern in 1975 and applied for practical use by Nilsson et al. in 1980. Since then, it has been used in various fields of medicine. The primary advantages of this device an that it is noninvasive and can monitor the blood flow continuously and rapidly. We used a Laser doppler flowmeter to continuously monitor the change in the oral peripheral blood flow due to changes in the body position of patients in a dental chair, since such changes are unavoidable during the course of dental treatment. A change from the sitting position to the supine position caused an increase in oral blood flow in 19 of 20 patients. In terms of the mean value per minute, oral blood flow was 23% greater in the supine position.

Blood Flow Velocity↗

PubMed1989

[Five cases referred to the First Department of Oral Surgery due to failure of impacted mandibular third molar extraction].

Of patients referred to our department over the post two years due to failure of tooth extraction 5 with impacated mandibular third molars were treated. We found that extraction had been hindered by the narrow operative field due to inadequate incision of the overlying mucosal tissue, insufficient bone resection and inadequate separation of the crown and root.

Humans↗

PubMed1989

[Two cases of Frey's syndrome].

During the taking of meals, complex symptoms such as perspiration, rubor, and febrile sensation can appear on the skin overlying the temporal area or the parotid gland after the passage of some time after an operation in the parotid area or trauma inflicted to this area. This phenomenon is usually called Frey's syndrome. We recently encountered two cases of this syndrome. The patients were a 16-year-old boy who developed this syndrome following open reduction of the fractured left temporomandibular articular process and a 72-year-old man who developed it following left hemimandibulectomy and left radical neck dissection performed for the treatment of left mandibular gingival cancer. Frey's syndrome is a relatively rare surgery-associated complication. However, it may be advisable to inform the patient of this possibility prior to an operation, because patients may be severely afflicted by heavy perspiration if this syndrome develops over an extensive area.

Adolescent↗

PubMed1989

[A case of bilateral impaction of the lower second molars].

A case of bilateral impaction of the lower second molars is presented. A 15-year-old boy with an ill feeling at the right lower first molar was referred to us. X-ray examination revealed bilateral impaction of the lower second molars and the presence of bilateral teeth that seemed to be the unerupted third molars distal to the impacted second molars. Furthermore, a radiolucency approximately 3 X 3 mm in size was detected in the mesioapical region of the right lower first molar. These impactions were managed under local anesthesia by extraction of the right lower first molar and fenestration of the right lower second molar. After approximately 4.5 months, the right lower third molar was extracted. It was further followed approximately 1 month later by extraction of the left lower third molar and ipsilateral fenestration of the lower second molar. As a result, the right lower second molar erupted but it was considerably inclined in a mesial direction. The left lower second molar erupted normally almost up to the occlusal plane. In the absence of systemic abnormality, facial trauma, and maldevelopment of the jaw, impaction seemed to have been closely associated with some unknown local factor.

Adolescent↗

PubMed1988

Calcifying odontogenic cyst immunohistochemical detection of keratin and involucrin in cyst wall.

Calcifying odontogenic cysts (COC) were immunohistochemically described using different keratin proteins and involucrin as well as histopathology. The cystic lining epithelium was composed of calcifying, keratinizing, squamous, and columnar epithelial cells, and included calcified masses of irregular shape and various size as well as ghost cells. Calcifying epithelium gave negative or only trace staining for keratins detected with low molecular keratin (PKK1), but were regularly positive with high molecular keratin (KL1) and polyclonal antibody for keratin (TK). They were occasionally positive for involucrin. The cells located in the periphery of the calcified masses had a particular abundance of high molecular weight and total keratins (KL1 and TK). Calcified bodies and ghost cells were devoid of any immunoreactivity. Squamous epithelium was relatively similar to that of normal squamous cell epithelium in the oral mucosa. It were most commonly found in columnar cystic epithelial cells which displayed intense staining with all immunoreagents. It is postulated that such epithelial cells may have a strong potentiality to transform into ghost cells or to undergo metaplasia. They may develop altered synthesis of homogenous acellular materials and finally become transformed into calcifying epithelium containing dystrophic calcified masses.

Adolescent↗

PubMed1988