Biomedical subjects

U Santana

Publications and source records attributed to U Santana.

5 recordsLinked to original sources

PubMed2000

Titanium for removable denture bases.

The aim of the present study was to compare titanium-base and resin-base maxillary complete dentures. In 13 patients with a maxillary complete denture with a titanium base (group I) and in 12 patients with a maxillary complete denture with a resin base (group II), the (a) patient's adaptation to the denture, (b) denture retention and (c) appearance of the mucosa under the denture were evaluated. In all cases, the adaptation was assessed with a questionnaire, while the retention and the appearance of the mucosa were assessed by clinical examination. None of the three measures considered (adaptation, retention and mucosa appearance) differed significantly between patients with titanium-base dentures and patients with resin-base dentures. Titanium bases are suitable for dentures likely to be subject to severe mechanical stresses (as in the case of maxillary complete dentures opposing natural teeth), and in patients who show hypersensitivity responses to other materials.

Acrylic Resins↗

PubMed1998

Myoelectric activity during unilateral chewing in healthy subjects: cycle duration and order of muscle activation.

STATEMENT OF PROBLEM: Craniomandibular disorders, unilateral mastication, and asymmetry of masticatory muscles appear to be related to each other. Thus, it is of interest to investigate masticatory muscle activity during unilateral mastication in healthy subjects. PURPOSE: This study monitored contractile activity of the right and left masticatory muscles during right- and left-side gum chewing. MATERIAL AND METHODS: Electromyographic techniques were used to determine chewing cycle duration and duration of contractile activity of the masticatory muscles (right and left masseter and anterior temporalis muscles) during unilateral chewing in 40 subjects without orofacial pain. The time-course of activation of the 4 muscles was also investigated. RESULTS: Electromyographic traces showed extensive interindividual variation. In both right- and left-side chewing tests, and regardless of whether the masseter or the temporalis muscles were considered, mean duration of the contraction phase did not differ significantly between the working and nonworking sides. The working side temporalis contracted first, whether alone or at the same time as the other muscles. CONCLUSIONS: In healthy subjects, no significant differences in masticatory muscle activity should be expected between either the right and left or the working and nonworking sides.

Adult↗

PubMed1998

Comparison of the fracture resistances of pulpless teeth restored with a cast post and core or carbon-fiber post with a composite core.

STATEMENT OF PROBLEM: The survival of pulpless teeth restored with a post and core system is a controversial issue. PURPOSE: This study compared the fracture resistance of 2 types of restorations: teeth restored with prefabricated carbon-fiber posts and composite cores to cast dowel-core restored teeth. MATERIAL AND METHODS: A total of 44 recently extracted sound premolars were randomly distributed into 2 equal groups: group I, restored with prefabricated carbon-fiber post and a composite core; and group II, with custom-cast type III gold alloy post and cores. The size and shape of the posts were identical in the 2 groups. All teeth were fully covered with a nonprecious cast crown. Fracture resistance was measured by applying a point force at 45 degrees to the long angle of the tooth. RESULTS: Mean fracture threshold was 103.7 +/- 53.1 kg for group I versus 202.7 +/- 125.0 kg for group II (differences significant with P = .003). In group II, however, fracture nearly always affected the tooth itself, whereas in group I, the post-core nearly always failed first. CONCLUSIONS: Significantly higher fracture thresholds were recorded for the cast post and core group. Teeth restored with cast posts typically showed fracture of the tooth, although at loads rarely occurring clinically.

Adolescent↗

PubMed1997

Myoelectrical activity of clinical rest position and jaw muscle activity in young adults.

Electromyographic activity of anterior temporal, superficial masseter, deep masseter and anterior digastric muscles was measured in 40 young healthy men and women during rest (at the beginning and the end of tests), clench, maximal opening, lateral displacement and CR manipulation. During initial rest position myoelectrical activity was 1.9 microV increasing to 2.1 microV at the end of tests (P = 0.08). During clench and maximal opening no significant differences between the sexes were found. The digastric muscle showed considerable activity during maximal opening, lateral displacement and CR manipulation.

Action Potentials↗

PubMed1995

Electromyographic analysis of the masticatory muscles of patients after complete rehabilitation of occlusion with protection by non-working side contacts.

Surface electromyography was used to study the function of the anterior temporal, surface masseter, deep masseter and anterior digastric muscles of 14 patients after complete rehabilitation of occlusion with fixed prostheses and/or removable partial prostheses. All patients had a balanced occlusion with protection by non-working side contacts during lateral excursion. Mean resting myoelectric activity was 2.5-3.8 microV, showing no hypertonia or muscular spasm. When patients clenched their teeth (i.e. exerted maximum voluntary occlusal force in centric occlusion), the anterior temporal muscles were the most active, followed by the surface masseters; the digastrics were significantly less active. During lateral displacements, the muscles exhibiting significantly higher potentials than the other muscles monitored were the working side anterior temporal muscle and the contralateral surface masseter. During mastication, the muscle that was most active in relation to its contralateral homologue was the working side surface masseter, the difference between the two being statistically significant.

Adult↗