Balance of glutamate and dopamine in the nucleus accumbens modulates self-stimulation behavior after injection of cholecystokinin and neurotensin in the rat brain.

Subpopulations of dopamine (DA) neurons in the ventral mesencephalon have been reported to contain cholecystokinin (CCK) and neurotensin (NT), giving rise to DA, DA/NT, NT/CCK and DA/CCK/NT projections. More precisely, colocalized DA/CCK neurons project mainly to the caudal part of the medial nucleus accumbens, whereas its rostral portion receives CCK and DA nerve terminal networks that are structurally independent. We investigated the respective effects of both CCK and NT on the intracranial self-stimulation behavior (ICSS) from the posterolateral hypothalamus after their direct administration into the lateral ventricle (ICV), into both portions of the nucleus accumbens, into the ventral tegmental area (VTA), and into the subiculum of the hippocampal formation (SUB). The ICV injection of 150 pmol CCK8 induced a decrease in the rate of ICSS. By contrast, the direct administration of 150 pmol CCK8 into the mediocaudal part of the nucleus accumbens induced an enhanced rate of ICSS while a similar injection into its rostral portion gave rise to a slight transient decrease of ICSS. When injected into the SUB, both CCK8 and glutamate produced decreased rates of ICSS at femtomolar doses one thousand-fold under the picomolar concentrations used for ICV injections. Neurotensin induced similar behavioral profiles to that observed after the ICV injection of CCK8 or into both portions of the nucleus accumbens. Neurotensin and CCK8 displayed opposite effects on ICSS when administered into the SUB or into the VTA, suggesting they may regulate ICSS most probably through different synaptic mechanisms and through different anatomical pathways.

Pseudodynamic magnetic resonance imaging in the diagnosis of temporomandibular joint dysfunction.

Two imaging methods are useful in diagnosing internal derangements of the temporomandibular joint: arthrography and magnetic resonance imaging (MRI). Clinical and pseudodynamic MRI findings of 200 temporomandibular joints in 100 patients were evaluated and compared. In 66.5% of the joints, there was a positive correlation between both diagnostic methods. MRI showed the possibility to correct the clinical diagnosis in more than half of the remaining joints. The other half of the joints are a source of discussion and suggest that MRI has some difficulties in detecting the exact disk position, especially in joints with an anterior disk displacement with early reduction. MRI revealed degenerative changes in 43.5% of the joints. They were often seen in joints with a disk displacement without reduction, even in young patients. Pseudodynamic MRI is especially useful in the differential diagnosis of a "closed lock" and should certainly be done when disk surgery is planned.

[Imaging of the temporomandibular joint]. / L'imagerie de l'articulation temporo-mandibulaire.

A large number of imaging techniques are available nowadays to visualise the temporomandibular joint and surrounding structures. It is important that osseous structures as well as soft tissue can be shown. Transcranial images, conventional tomography, panoramic radiography and computed tomography (CT) are more suitable for viewing the osseous structures. The best techniques to evaluate the soft tissues are arthrography and especially magnetic resonance imaging (MR). The panoramic radiography is the technique of choice in the general practice and provides adequate screening images of the temporomandibular joints, mandible, maxilla, teeth and surrounding tissues. When the joint is suspected of developmental anomalies, neoplastic conditions or a condylar trauma, CT-images are necessary to depict the bony abnormalities. CT has a poor reliability in imaging the disk. For this reason, disk displacements of the temporomandibular joint are best shown with MR, although the clinician should be very restrictive in using MR-images. They are very expensive and are only useful to confirm an uncertain diagnosis, or if disc surgery is the treatment of choice. The anamnesis and the clinical investigation are still the most important elements in diagnosing craniomandibular dysfunction.

Visco-elastic properties of four currently used tissue conditioners.

About 60% of complete denture wearers experience a mostly painless inflammation of the palatal mucosal membrane. Especially prosthetic trauma and Candida albicans infection are assumed as aetiological factors. The treatment can be prosthetic or medicamentous, dependent on the cause. In this connection tissue conditioners could be very effective by their visco-elastic properties. Four tissue conditioners have been examined (Coe Comfort, FITT, Ivoseal, Visco Gel) for their impression softness and elastic recovery. All tests have been done on 20 mm specimens. The length of the specimens was measured during a 10 min compression and a 60 min relaxation. Eight ageing times have been taken into consideration. From the results large differences appear between the various tissue conditioners. Two main groups can be distinguished. FITT and Ivoseal are harder materials, whereas Coe Comfort and Visco Gel are softer. The ageing time has a clear hardening influence especially on Visco Gel. Visco Gel appears to be the best tissue conditioner by its relative plasticity during the first hours and its elastic behaviour during a longer ageing period. The clinical relevance of these materials is certainly not proved by this study. Further research will show this.

[Temporomandibular joint symptoms in orthognathic surgery: a retrospective study]. / Kaakgewrichtssymptomen in orthognatische chirurgie: een retrospectief onderzoek.

The records of 152 consecutive patients who underwent orthognathic surgery in the Division of Maxillofacial Surgery A.Z. St.-Jan, Brugge, between 1/10/90 and 1/10/91 were evaluated for pre- and postoperative temporo-mandibular joint (TMJ) symptoms. Fewer TMJ symptoms were found postoperatively, than preoperatively (14.4% versus 19.7%). In the mandibular retrognathism group there were twice as much TMJ symptoms preoperatively in the low and normal mandibular angle patient group than in the high mandibular angle group (26% versus 13%). After surgery, there was a decrease of TMJ symptoms in the low and normal angle patient group (83% improvement). In the high angle absolute mandibular retrognathism group however, more new TMJ symptoms were seen postoperatively (21%). Bimaxillary surgical correction of a high angle absolute mandibular retrognathism case may provoke condylar resorption. Advice for follow-up and suggestions to reduce this annoying complication are given.

[Inter-university cooperation in Flanders--an academic point of view on peer review]. / La Collaboration Interuniversitaire en Flandre - un point de vue académique sur les peer review.

Peer review as a possibility for discussion among practising dentists was introduced in Belgium in 1998 in the framework of a quality ensuring program. The 'Interuniversitary Cooperation', an initiative of Flemish universities active in teaching, research and patient treatment in dentistry has been involved in this program since its beginning to set up a dialogue between academia and dental practitioners and to gather information on scientific and educational matters. In this article the principles and organisation are described and thought is given to the attitude of the participants and future possibilities.

[Rehabilitation of the anterior portions of the maxilla and mandible by means of implants and bone grafts]. / Réhabilitation orale des régions antéro-inférieure et antéro-supérieure à l'aide d'implants et de greffons osseux.

This article describes the possibilities and difficulties of reconstruction in the front regio by means of implants and bone transplants in five patients. First of all, planning is the most important step. Sometimes the class III relationship is a real challenge. Different bone transplants, the inlay and onlay technique, the number of the implants, the importance of the way the implants are uncovered in the second stage are discussed. In the front region, we aim for functional and esthetic reconstruction.

[Treatment of a congenitally missing upper lateral incisor with an implant]. / Traitement de l'agénésie de l'incisive latérale supérieure au moyen d'un implant.

The presentation of a case where an agenetic lateral tooth was replaced by an oral implant, has been described. The following parameters are important: oral hygiene, the moment of implant surgery, presurgical orthodontic treatment, alternative prosthetic treatment possibilities and recall of the patient.

Condylar resorption in orthognathic surgery: a retrospective study.

A retrospective study was performed to examine the occurrence of condylar atrophy in connection with orthognathic surgery. Patients with high-angle mandibular deficiency (n = 29) were selected from among those who underwent bimaxillary osteotomy (n = 93) during the period from January 1987 through December 1990. This group of 29 was examined for shortening of the ascending ramus of the mandible because of condylar resorption. In 9 of these 29 (31%), the ramus had resorbed more than 2 mm, or more than 6% of the total length of the ramus. All 9 of these patients were female. There was no correlation between resorption and age, the amount of retrognathism, or the presence of preoperative temporomandibular joint dysfunction. Female patients with high-angle retrognathism should be informed of the possibility of postoperative condylar resorption and should be followed with radiographic controls for at least 2 years after surgery.

[Dynamic MRI of temporomandibular joint: technique and application]. / L'IRM dynamique de l'articulation temporo-mandibulaire: technique et application.

Internal derangements or disk dysfunctions represent the most frequent pathology of the temporomandibular joint (TMJ). The radiological study of TMJ dysfunction was, for a long time, restricted to arthrography. More and more MR is used to study the TMJ, because MR, allows non-invasive visualisation of without the use of X-rays. Moreover a "dynamic" MR technique can be used to study disk movements during mouth opening. A lot of the internal derangement problems can be solved with this technique and arthrography can often be avoided. This dynamic MR technique is described and some cases are discussed.