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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

Temporomandibular articular disorders can be alleviated with surgery.

DATA SOURCES: Medline, Embase and a variety of other sources were searched for English-language articles. Non-journal publications, conferences proceedings from professional organisations and from private and government agencies were screened. Bibliographies and reference lists from peer-reviewed and 'grey' literature were also reviewed. STUDY SELECTION: To meet the inclusion criteria articles must have reported studies of at least 10 patients, involve diagnoses of disc displacement with reduction (DDwR) or without reduction (DDw/oR) or degenerative joint disease (DJD) and include at least one of the following surgical techniques: arthrocentesis; arthroscopy; discectomy without replacement or disc repair/repositioning. DATA EXTRACTION AND SYNTHESIS: The outcome measured was the proportion of patients who reported improvement after treatment. Study success rates were recalculated on an intent-to-treat basis. Meta-analyses were performed along with meta-regressions where heterogeneity was an issue. Three classes of meta-analyses were performed using different artificial, untreated, control groups assuming three levels of spontaneous improvement, namely 0, 37.5 and 75%. RESULTS: Twenty-two studies, comprising 30 patient groups and sample sizes of 11-237 patients, met the inclusion criteria. For studies of patients with DDwR, at the 0 and 37.5% rates of control group improvement, arthroscopy and disc repair/repositioning resulted in treatment effects significantly greater than zero, with no significant differences in the efficacy of these two surgical techniques. For studies of patients with DDw/OR, the proportion of patients who improved after arthroscopy or arthrocentesis was significantly greater than zero at all three levels of estimated control improvement. Disc repair effect size was not significant at the 75% rate. CONCLUSIONS: Surgical treatments appear to have some efficacy for people who have temporomandibular articular disorders that do not respond to nonsurgical therapies.

Comment↗

Identification of RANKL in osteolytic lesions of the facial skeleton.

RANKL (receptor activator of nuclear factor kappaB ligand) promotes osteoclast differentiation, stimulates osteoclast activity, and prolongs osteoclast survival and adherence to bone. Abnormalities of the RANKL/RANK/osteoprotegerin system have been implicated in a range of diseases, including osteoporosis. To date, no work has been done in osteolytic lesions of the facial skeleton. In this study, specimens of ameloblastomas, dentigerous cysts, odontogenic keratocysts, and radicular cysts were subjected to immunohistochemical analysis for RANKL and tartrate-resistant acid phosphatase (TRAP). Immunofluorescence staining for TRAP was visualized under confocal microscopy. All specimens demonstrated distinct positive immunoreactivity to RANKL and TRAP. The TRAP-positive cells also stained with in situ hybridization for human calcitonin receptor, a definitive marker for osteoclasts. Mononuclear pre-osteoclasts were observed to migrate from blood to the connective tissue stroma and multinucleate toward the bone surface. It can be concluded that RANKL plays a role in bone resorption in osteolytic lesions of the facial skeleton.

Acid Phosphatase↗

Bisphosphonates--a word of caution.

There have been recent reports from various centres of a possible association between avascular necrosis of the jaws and the use of bisphosphonates. This commentary reviews the available data and alerts clinicians to a possible adverse reaction in the oral cavity to a group of drugs that are commonly prescribed.

Diphosphonates↗

The role of Internet and personal digital assistant in oral and maxillofacial pathology.

Internet usage for dentistry and medicine is growing. Using search engines available on the Internet, websites for oral pathology and oral medicine information resources are explored and evaluated. A framework, whereby the personal digital assistant is used in conjunction with the Internet to enhance the practice and education of oral pathology, is proposed.

Computers, Handheld↗

Oral pemphigus vulgaris: a case report and literature update.

INTRODUCTION: Pemphigus vulgaris is a rare cause of oral mucosal ulceration. CLINICAL PICTURE: A 47-year-old Chinese man presented with a 3-month history of oral ulceration. There were no lesions on the skin or other mucosal sites. Histology and immunostaining were consistent with pemphigus vulgaris. TREATMENT: Systemic and topical corticosteroids were instituted, together with topical antifungals. Conventional periodontal therapy was carried out to improve gingival/oral health. OUTCOME: Control of oral ulceration was achieved with re-establishment of normal oral function. No other sites to date have been involved. CONCLUSIONS: Chronic oral ulceration can be the sole manifestation of pemphigus vulgaris, at least initially. Early recognition of this lesion may prevent delayed diagnosis and inappropriate treatment of a potentially chronic dermatological condition.

Antifungal Agents↗

MELAS: a case report.

INTRODUCTION: Mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) is a rare, neurodegenerative and fatal disease caused by mutations in the mitochondrial DNA. Multiple systems of the body, including the oral cavity, can be affected by this disease. An electronic search of Medline spanning the years 1985 to 2003 was carried out using the key words "MELAS, Dentistry." It yielded no literature on the dental aspects of MELAS. CLINICAL PICTURE: This report documents the case of a 6-year-old Chinese boy diagnosed with MELAS and highlights problems encountered in the multidisciplinary management of MELAS patients, including its dental management. TREATMENT AND OUTCOME: Dental management was successfully performed under general anaesthesia with close medical supervision by paediatrician and anaesthetist. CONCLUSIONS: There is no known treatment of the underlying disease and the clinical course is usually unpredictable. Preventive dental care is important in this group of patients as concurrent medical conditions can complicate dental care.

Child↗

Sustained microglial immunoreactivity in the caudal spinal trigeminal nucleus after formalin injection.

Recent studies indicate that glia may be involved in altered nociceptive processing after a peripheral inflammatory lesion produced by injection of inflammatory reagents such as formalin and zymosan. Most of these studies, however, confined their observations to a period shortly after the injections. This study investigated the immunohistochemical responses of microglia in the caudal part of the spinal trigeminal nucleus for up to 60 days after subcutaneous injection of formalin into the lateral faces of Wistar rats. The results showed obvious up-regulation of microglial markers such as OX-18, OX-42 and OX-6 up to 21 days after formalin injection. These were somewhat reduced at 30 days after injection. Electron microscope investigation revealed no evidence of significant phagocytosis of degenerative neuronal elements by microglia in the nucleus at the time--that is, 7 days after formalin injection, when microglial activation was at its peak. Significantly, however, the period of microglial activation corresponded closely to that showing enhanced nociceptive behavior after perioral formalin injection (Cadet et al., 1995). This study indicates a microglial role in the genesis of enhanced nociceptive behavior.

Animals↗

Qualitative light and electron microscope study of glutamate receptors in the caudal spinal trigeminal nucleus of the rat.

Though ionotropic and metabotropic glutamate receptors have recently been recognized to play important roles in the transmission of orofacial nociceptive impulses, their detailed distribution in the spinal trigeminal nucleus has not been systematically investigated. There is also controversy regarding the electron microscope localization of metabotropic receptors. We therefore undertook this investigation to address the above-mentioned issues in the caudal part of the spinal trigeminal nucleus, using light and electron microscope immunocytochemistry, to provide baseline information for the development of agonists and antagonists of these receptors in the clinical treatment of orofacial pain. The results showed some moderately to strongly stained glutamate receptor 1 neurons, and many strongly stained glutamate receptor 2/3 neurons in lamina II of the nucleus, suggesting that the latter may play an important role in orofacial pain processing, with the former playing a minor role. The metabotropic glutamate receptor 1 immunoreactive product was localized mostly in dendrites, while most of the metabotropic glutamate receptors 2/3 immunoreactive product was deposited in axon terminals containing synaptic vesicles of different shapes, suggesting that glutamate receptors 2/3 may control the release of both excitatory and inhibitory neurotransmitters.

Animals↗

Clinicopathologic study of odontogenic keratocysts in Singapore and Malaysia.

This was a retrospective study of odontogenic keratocysts in people from the Singapore-Malaysian region. The purpose of this study was to present the clinicopathologic features of odontogenic keratocysts in the Oriental population and to compare these data with those from other reported studies. Biopsy records from 1981 to 1992 of 61 cases of odontogenic keratocysts from patients in Malaysia and Singapore showed that 42.6% of patients were female and 57.4% of patients were male. Among patients with cysts, 75.4% were Chinese, 6.6% were Malays, 9.8% were Indians and 8.2% were other ethnic groups. The mean age of these patients was 26.98 +/- 15.38 years with a peak incidence occurring in the second to fourth decades. The location of the lesions was more often in the mandible (65.5%) than the maxilla (31.0%). There was a marked predilection for lesions to occur in the posterior mandible. Histologically, 90.2% of the cysts were lined with a para-keratinized stratified squamous epithelium while only 3.3% of the cysts were lined with orthokeratinized stratified squamous epithelium. Mixed para-keratinized and orthokeratinized epithelial linings were observed in 4 cases (6.5%). The cyst linings were mainly uninflamed (95.1%). Inflammation of the cyst wall was found in 42 cases (68.8%). Twelve (19.7%) cases contained keratin in the lumen. A satellite cyst was observed in only 6 cases (9.8%). In conclusion, most clinical and histological features seen in this study were similar to those found for Caucasians. The only clinical feature that was different was the peak age incidence, that ranged from the second to fourth decades, with an absence of a second peak. Odontogenic keratocysts presenting at the site of the dentigerous cyst were observed in 7 cases (11.5%).

Adolescent↗

Use of sedation in dentistry.

Fear and avoidance of dental treatment are major deterrents to oral health. Sedation can be used to control both the patient's fear and anxiety so that proper dental care can be provided for these patients. The purpose of this article is to discuss the use of sedation in dentistry and to provide a recommendation on the requirements and medico-legal aspects of sedation for the practitioner interested in incorporating sedation into their practice.

Anesthesia, Dental↗

Oral medicine and surgery interests on the Internet.

The Internet is a global network which link millions of people via the information highway. The internet use for dentistry is growing rapidly. This has been accelerated by the use of many browsers. There has been a very rapid increase in the number of media resources and the quality of information over the internet has improved. Many universities, institutions and dental suppliers are establishing web pages. The resources is getting vast and in this paper, we explore the usefulness of the internet. This paper serve as a guide to the oral surgery, oral pathology and oral medicine resources and forums available on the information highway.

Information Storage and Retrieval↗

A duty of quality.

Explore the source record for details and available documents.

Delivery of Health Care↗

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↗

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↗

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↗

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↗