Sectional impressions for mandibular distal extension removable partial dentures.

STATEMENT OF PROBLEM: Corrected impression procedures provide the best possible support to be gained from an edentulous ridge for a removable partial denture, but they are time-consuming and technique-sensitive. PURPOSE: An experimental mandibular distal extension removable partial denture was used to measure the vertical movement of denture bases during biting. MATERIAL AND METHODS: Five patients participated for whom vertical movement of denture bases was measured by comparing the thickness of plaster interocclusal records made with the denture at rest and under biting pressure. Denture bases were processed on master casts formed from final impressions made in full arch custom trays. Secondly, bases were readapted using sectional relining impressions with the same regular body polysulfide impression material. RESULTS: Statistical analysis of the vertical movement of denture bases during biting at 4 points on the right and left denture bases showed a significant decrease in vertical movement with sectional impression. The reduction was less than a 0.1 mm, a result that questions the routine use of sectional impression for every distal-extension mandibular removable partial denture. CONCLUSION: Supportive form of distal-extension edentulous ridges can be recorded successfully by full arch impressions in custom trays.

Stomatognathic dysfunctional symptoms in Saudi Arabian adolescents.

Secondary school Saudi students participated in a questionnaire about stomatognathic dysfunction symptoms. The adolescents were interviewed about general health, peripheral joint disease, chewing function, oral parafunctions, and symptoms of dysfunction. Thirty-two per cent of participants had at least one dysfunction symptom. Pain on opening was the most common (35.7%), followed by headache (33.6%), and joint sounds (32.2%). Symptoms increased with decline in general health, particularly the health of peripheral joints. Chewing functions were not impaired. Tooth loss did not affect dysfunction symptoms in adolescents, whilst a weak relation was evident between oral parafunctions and symptoms of mandibular dysfunction.

Accuracy of freely adapted resin record bases.

Forty autopolymerizing resin record bases were made; 10 bases were adapted by finger pressure on tray resin material dough, 10 bases by sprinkling orthodontic resin, and 10 of repair material by either of the two previous techniques. Stone casts and acrylic resin bases were sectioned at canine, premolar, and molar coronal planes. Width of the gap between base and cast and the thickness of the base were measured at the buccal sulcus, ridge crest, lateral palatal slope, and palatal midpoint. Measurements were made through the eyepiece of a microhardness tester. Statistical analysis of 760 pairs of measurements revealed that (1) sprinkled bases fit better than finger-adapted dough bases; (2) specifically formulated materials fit better than repair material with either technique; (3) gap widths differed at different areas of the same base; and (4) gap width was not related to base thickness at any point.

Displacement of border tissues during final impression procedures.

Two different impression procedures were used to reproduce the maxillary tissue form of five edentulous patients. One procedure used modeling plastic to mold the borders of spaced trays while the tissue contour was recorded with regular-body polysulfide. The second procedure used tissue treatment material to mold the borders of selectively spaced trays while the impression was completed in lightbody polysulfide. Each procedure was repeated three times for the same patient. Comparison of the profiles of the casts at premolar and molar coronal sections showed that (1) there was no significant difference in results between the procedures, (2) peripheral tissues were readily displaceable with the least manipulation, and (3) the second procedure is recommended because of convenience to the patient and time efficiency for the clinician.

Stomatognathic dysfunction in the western desert of Egypt: an epidemiological survey.

Results of a study of 215 male subjects from Siwa oasis are presented. The Siwian community is representative of the Bedouin communities in the Egyptian western desert. The population belongs to a characteristic ethnic group, living in a primitive way. The most prevalent symptoms were headache (29%), pain in the ear (24%) and clicking joint sounds (19%); 84% of the subjects suffered from tenderness of one or more of the masticatory muscles; 8% of the subjects had painful movements of the mandible. The results extend knowledge of the distribution of jaw dysfunction complaints into hitherto uninvestigated communities.

The swallowing position as a centric relation record.

A brief review of the swallowing position and its relation to centric relation records was presented. Intraoral tracings of the swallowing position for six patients were made at the natural occlusal vertical dimension. Deviations of the position from the IP were measured. The swallowing position deviated anteroposteriorly and laterally from the IP, and this raises questions as to the validity of this method for recording centric relation.

The contractile effect of bombesin on the rat isolated urinary bladder.

We have investigated and compared the myotropic effects of bombesin (BB) and carbachol (C) in the rat isolated urinary bladder. BB (0.5 x 10(-9) to 0.5 x 10(-5) M) and C (2.7 x 10(-8) to 5.4 x 10(-5) M) were found to produce dose-dependent increases of the basal tone of the rat detrusor muscle. The maximal contraction produced by C was about 4 times greater than that elicited by BB or substance P (SP). However, the threshold concentrations of BB and SP required to stimulate the detrusor muscle were much lower than those of C. The pD2 (-log ED50) values of BB, SP and C were respectively 7.63, 7.05 and 5.8. The tissues exposed to BB relaxed more slowly after washout than those challenged with C or SP. The contractile effects of medium range concentrations of BB were not affected by pretreating the tissues with tetrodotoxin, atropine, antihistaminics, indomethacin, alpha- and beta-adrenergic blockers, methysergide or 8-leucine-angiotensin II. Tissues desensitized with high concentrations of bradykinin maintained their sensitivity to BB. The result suggest that the contractile effect of BB on the rat isolated urinary bladder is likely to be the result of a direct effect on the smooth muscle cells.