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Biomedical subjects

J F Yeo

Publications and source records attributed to J F Yeo.

At least 19 recordsLinked to original sources
PubMed1998

Trigeminal neuralgia. A retrospective survey of a sample of patients in Singapore and Malaysia.

This survey was undertaken to study the clinical features of trigeminal neuralgia in an Asian population. Demographic data of 44 patients treated at the Dental Faculty of the National University of Singapore and at the University of Malaya were reviewed. The results of the survey were analysed and comparisons made with those of Caucasian patients as reported in other studies where there was a general similarity in the clinical findings. Trigeminal neuralgia presented predominantly in females. Right-sided involvement occurred at a greater frequency, and the peak age at onset was between the sixth and seventh decades of life. The only significant variant in the present sample was the greater involvement of the mandibular branch of the trigeminal nerve rather than the maxillary division. In addition, there was a much greater representation from Chinese patients over Malays as compared with their ratios in the general population.

Adult↗
PubMed1997

Ultrastructural study of NADPH-d positive neurons in laminae I and II of the rat caudal spinal trigeminal nucleus.

The present study investigated the ultrastructure of neurons in the caudal spinal trigeminal nucleus. These neurons which are believed to function as interneurons in the transmission of orofacial nonreflexive nociceptive information, measured 20 microns x 11 microns, and were nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) positive. The reaction product, formazan, was localized in the nuclear envelope, mitochondria, rough endoplasmic reticulum, and multivesicular bodies of these neurons. It was also localized in the membrane of the smooth endoplasmic reticulum at the axon terminal. The neurons were contacted by both axosomatic and axodendritic synapses formed by both NADPH-d positive and NADPH-d negative axon terminals. Two types of NADPH-d positive axon terminals could be recognized. The first was a large terminal containing many stained mitochondria and unstained small round agranular vesicles mixed with some slightly flattened ones. It formed asymmetrical axodendritic synapse. The second type of axon terminals contained pleomorphic synaptic vesicles and formed asymmetrical synapses upon both dendrites and soma. The sources of NADPH-d positive axon terminals were discussed. Most of the unstained axon terminals forming axosomatic and axodendritic synapses with stained cell bodies and dendrites contained flattened vesicles. In addition to the above, complicated synaptic configurations showing NADPH-d positive axoaxonic synapses in relation to NADPH-d negative dendritic spines were also seen in which a NADPH-d negative dendritic spine was completely contacted by a NADPH-d positive bouton which was in turn contacted by another NADPH-d positive bouton.

Animals↗
PubMed1997

Expression of glutamate receptor subunit 1 and nitric oxide synthase in the hypoglossal nucleus and dorsal vagal nucleus in the rat after neurectomy.

Using nitric oxide synthase (NOS) and glutamate receptor subunit 1 (GluR1) immunohistochemistry, the present study demonstrated changes in the expression of NOS and GluR1 in the hypoglossal (HN) and dorsal vagal nucleus (DVN) after neurectomy. Two and 7 days after sectioning the left hypoglossal nerve, NOS expression was seen in a few neurons but GluR1 immunoreactivity was drastically reduced in the ipsilateral HN. The upregulation of NOS immunoreactivity in the HN appeared to peak at 14 days postoperation (dpo). At this period, however, the GluR1 immunoreactivity almost completely disappeared. Twenty-one, 35 and 56 days after neurectomy, NOS immunoreactivity was still expressed in the ipsilateral HN; at the same time, GluR1 immunoreactivity reappeared in a few neurons of the nucleus. Ninety days after operation, NOS immunoreactivity completely disappeared on the operated side of the nucleus, but GluR1 immunoreactivity was re-expressed in many hypoglossal neurons. The number of such neurons was obviously less than that on the unoperated side. After sectioning the left vagus nerve in the same animals, the expression of NOS immunoreactivity in the ipsilateral DVN resembled that in the HN. On the unoperated side, NOS immunoreactivity was demonstrated in some neurons in the DVN, like that in the normal. In both normal and operated rats, only a few neurons expressed GluR1 immunoreactive products on both the operated and unoperated sides of the DVN. Combining with previous results on protein synthesis observed at 14 dpo, the present investigation suggested that in the early stages after neurectomy, the expression of NOS immunoreactivity and loss of GluR1 expression in the HN may indicate the organism's double protective mechanism. Lastly, the reappearance of GluR1 in the same nucleus from 21 to 90 days after operation may reflect functional recovery of the hypoglossal neurons.

Animals↗
PubMed1996

A survey of reasons for extraction of permanent teeth in Singapore.

A survey was carried out to determine the reasons for tooth extractions of permanent teeth in Singapore. Data were obtained from 52 dentists practising general dentistry over a period of 12 months. At the end of the 12-month period, data were collected from 1276 patients, from whom a total 272 teeth were extracted. In this population group, the results showed that the percentage of teeth extracted due to periodontal reasons and caries were about the same, that is 35.8% and 35.4%, respectively. There was an increase in teeth extracted due to periodontal reasons with age. In patients above 40 yr, an average of 76% of teeth were lost due to periodontal reasons. An average of 26.7% of teeth were lost due to periodontal reasons in patients under 40 yr old. However, the trend for loss of teeth due to caries is reversed. Posterior teeth were more frequently extract compared to anterior teeth. Third molars accounted for 24.7% of all extractions carried out, whilst central incisors were 8.0% of all extractions. Molars were often lost due to caries and lower anterior teeth were most frequently lost due to periodontal reasons. The results of this study did not demonstrate one predominant reason for extraction. Both caries and periodontal reasons were equally common causes of tooth extraction.

Adolescent↗
PubMed1995

Oral pyogenic granuloma (excluding pregnancy tumour)--a clinical analysis of 304 cases.

A clinical analysis of 304 cases of pyogenic granuloma (excluding pregnancy tumour) were obtained from the clinical evaluations submitted by clinicians while sending specimens for biopsy. The average age of the patients with pyogenic granuloma was 28.9 years with a peak age incidence in the second decade. More female patients were affected and the lesions present mainly in the Chinese. The majority of the lesions were ulcerated and pedunculated. The lesions had a mean diameter of 10.8 mm with a mean lesion duration of 6.0 months. The gingiva was the prevalent site for these lesions with a greater number being located in the maxilla. The recurrence rate was found to be 14.1%.

Adolescent↗
PubMed1991

Primitive neuroectodermal tumour in the oral cavity. Case report.

Primitive neuroectodermal tumour is regarded as a rarely seen lesion as it occurs mainly within the central nervous system. However, this neoplasm does occasionally occur elsewhere in the body. One such case which occurred in the posterior part of the palate in a child is reported. Following a combined therapeutic approach comprising surgery, radiotherapy and chemotherapy, the patient has been well for nine years since treatment.

Child↗
PubMed1990

Bifid mandibular condyle.

This report brings the total number of bifid mandibular condyles reported so far in the English-language literature to 15 cases. In addition, one dried specimen with two distinct condylar heads is reported. This rare anomaly does not appear to have a predilection for any particular race or either gender. At the time of initial consultation, almost all patients are adults. Sixty-seven percent of the patients have no complaints related to the affected condyles, but the condition is an incidental dental panoramic radiographic finding. The left condyles seem to be affected twice as often as the right condyles. We do not yet fully know the etiology, epidemiology, and long-term functional effects of this condition. We recommend the transorbital condylar view as a good, inexpensive, and lower dosage technique, compared with the tomogram, to demonstrate this anomaly.

Adult↗
PubMed1990

Amyloidosis with oral involvement. Case report.

A patient with chronic renal failure was investigated after complaining of oral discomfort which was found to be due to macroglossia and generalized involvement of the oral soft tissues by amyloidosis. A search for multiple myeloma proved to be positive. She also had a previous history of Carpal-tunnel syndrome. Despite an initial good response to treatment with phenylalanine nitrogen mustard (melphalan hydrochloride), she finally succumbed to end-stage renal failure.

Amyloidosis↗
PubMed1990

Evaluation of soft tissue profile following intraoral ramus osteotomy in Chinese adults with mandibular prognathism.

Twenty-five Chinese adults with mandibular prognathism were treated with either the intraoral vertical subcondylar osteotomy or the bilateral sagittal split ramus osteotomy. The patients were kept in maxillomandibular fixation for 6 to 8 weeks while osteosynthesis was achieved with the use of intraosseous wiring. Serial lateral cephalograms were taken presurgery and between 12 and 26 months postsurgery, and specific soft and hard tissue points were digitized on a computer. The mean mandibular setback postsurgically was 8.4 +/- 3.2 mm, with a 5.2-degree reduction in point A-nasion-point B angle. Posterior movement of pogonion, point B and the mandibular incisal edge was accompanied by posterior movement of 95% at soft tissue pogonion (r = .96), 89% at soft tissue point B (r = .83), and 67% at labrale inferius (r = .81), respectively. The correlation between changes in the labrale superius and mandibular setback appeared to be dependent on both the amount of mandibular setback and the degree of mandibular rotation during the setback surgery. The presently reported ratios of the soft tissue response to hard tissue movement vary from those reported in white patients by other researchers, which confirms the need for different ratios for different racial types.

Adult↗
PubMed1989

Florid osseous dysplasia in Orientals.

Florid osseous dysplasia has been described as a condition that characteristically affects the jaws of middle-aged black women. It usually manifests as multiple radiopaque cementum-like masses distributed throughout the jaws. This condition has also been classified by various authors as sclerosing osteomyelitis, sclerosing osteitis, sclerotic cemental masses, gigantiform cementoma, and various other terms. In this series, we want to document eight cases of florid osseous dysplasia in middle-aged, female ethnic Chinese and one case in an Indian subject on the basis of radiographic and histopathologic findings. On the basis of this series, incidence is estimated to be 0.01 case per year 100,000 population. Florid osseous dysplasia constitutes 11% of cemental lesions in our files.

Adult↗
PubMed1989

Talisman in the orofacial region.

Among the various traditional beliefs and practices of the peoples of the Southeast Asia region is the practice of inserting talismans under the skin in various parts of the human body. In the orofacial region, these talismans (also called charm needles or charm pins) are also seen, usually as incidental radiographic findings. These talismans are believed to enhance the beauty of the wearers, as well as to provide protection to the wearers against harm. It is also believed that they could help the wearer obtain favorable business deals inasmuch as they are believed to have a "spell-like" influence on the business counterparts. In the present series, 67% of the patients are female and 66% of them are Muslim. Very little is known about the possible ill effects of these talismans because there is no report of these radiographic findings in major dental journals. In the present series of 12 cases representing a total of 65 talismans, only one talisman was surgically removed. We believe that generally no definitive treatment is required. However, we believe that the existence of these talismans should be made known so that they will not be misdiagnosed and mismanaged.

Adult↗
PubMed1989

Serious circulatory disturbance after Le Fort I osteotomy. A case report.

Severe impairment of the blood supply occurred in a patient who underwent a Le Fort I type osteotomy in which the fragment was displaced in a cranio-dorsal direction. Necrosis with sequestration of the torus palatinus present and some permanent parodontal damage ensued. Alternative procedures and management of developing circulatory impairment during surgery are discussed.

Adult↗
PubMed1989

Histoplasmosis presenting as hyperplastic gingival lesion.

A case of histoplasmosis presenting as ulcerated, hyperplastic gingiva and with no other systematic signs and symptoms is reported. The clinical presentation and the rarity of this condition led one of us to the differential diagnosis of a malignant lesion. The correct diagnosis was made after histological examination and tissue culture which yielded Histoplasma capsulatum. The patient was successfully treated with ketoconazole.

Adult↗
PubMed1989

Multiple odontogenic keratocysts of the jaws. Case report.

Single odontogenic cysts are very well documented in the literature. Of those less common reports concerning multiple jaw cysts, many have been associated with systemic conditions or syndromes such as Gorlin-Goltz or basal cell naevus syndrome, Hunter's syndrome and mucopolysaccharidosis, for example, Maroteaux-Lamy syndrome. A case of multiple odontogenic keratocysts unassociated with any syndrome is reported so as to add to the growing number of such cases in the literature. The possibility of this case being a partial expression of the Gorlin-Goltz syndrome is discussed.

Adolescent↗
PubMed1989

Retrograde removal of fractured endodontic instruments.

During root canal therapy, accidental fracture of endodontic instruments may occur. While in the majority of such cases the fragment concerned can be retrieved non-surgically, there are some occasions that surgical intervention is needed in order to remove the broken tip lodged within the root canal. In this paper the authors would like to suggest a management approach to this uncommon and extremely unpleasant complication in dental practice.

Adolescent↗