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Biomedical subjects

T Jemt

Publications and source records attributed to T Jemt.

At least 73 records · Page 4Linked to original sources
PubMed1986

Adhesion of polycarboxylate-based dental cements to enamel: an in vivo study.

The bond strength of two polycarboxylate and two glass ionomer cements to enamel in vivo has been measured by a tensile test method. The four cements were used to cement small stainless steel cylinders onto the facial surfaces of 11 and 21. The cylinders were removed by a tensile force applied by a handpiece containing a semi-conductor sensory unit. The results showed that all cements gave two sets of bond strength values, either a good bond corresponding to a cohesive failure, or a weak bond corresponding to an adhesive failure. The mean bond strength values were lower than those recorded in vitro, and differences among the cements were limited.

Adhesiveness↗
PubMed1985

Changes in chewing patterns of patients with complete dentures after placement of osseointegrated implants in the mandible.

Mandibular movements were recorded with the Selspot system in 16 complete denture patients, before and after treatment with mandibular OIFD. The general chewing pattern underwent only minor changes. However, some chewing cycle parameters showed obvious alterations. Increased mandibular velocity and displacement, especially in the opening phase, were registered. The cycle duration showed a tendency to decrease due to a significant shortening of the occlusion phase. This can be attributed to the stabilization of the occlusion provided by the fixed denture in the mandible.

Adult↗
PubMed1985

Masticatory movements in patients treated with fixed prosthesis on osseointegrated dental implants in the mandible.

Mandibular movements were recorded by means of an optoelectronic system (Sel spot) in 16 complete denture wearers before and after insertion of tissue integrated prostheses in the mandible. Analysis of the single chewing cycle revealed an obvious increase in mandibular velocity and displacement after rehabilitation. The duration of the occlusion phase was also significantly shortened, probably due to the stabilization of the occlusion provided by the fixed implant bridge.

Computers↗
PubMed1984

Computer-based analysis of the single chewing cycle during mastication in repeated registrations.

A new computer-based analysis of the single chewing cycle was described as a complement to the Selspot system used for recording mandibular movements. Fifteen adults took part in a clinical investigation of masticatory movements recorded in two sessions with an interval of about 4 weeks. The analysis of the single cycle was performed in regard to chewing rhythm, mandibular displacement, and velocity; the results showed agreement with earlier published results. Most parameters showed agreement between the two registrations, but there was an indication of a weak adaptation to the test situation that should not be disregarded in repeated test situations.

Adult↗
PubMed1984

Masticatory mandibular movements. Analysis of a recording method and influence of the state of the occlusion.

The aims of this thesis were, firstly, to develop a method for three-dimensional recording of mandibular movements based on available optoelectronic devices, and to evaluate the accuracy of the method in a clinical setting, and secondly, to study the habitual chewing pattern in individuals with complete natural dentitions by repeated registrations and compare them with persons suffering from different degrees of tooth loss before and after prosthetic treatment. This methodological approach imposes minimal constraint upon movement and permits three-dimensional registration of the movements of a point on the mandible for study of the overall pattern and analysis of chewing rate, mandibular displacement and velocity. The total error of the system was less than 1 per cent of the recorded area, where the movements of the reference system, attached to spectacle frames in the clinical test, were shown to be minimal. The methodological error had minimal influence on the data yielded. Great intra- and interindividual variations were observed in the overall pattern as well as in different parameters studied, but the individual chewing performance was relatively consistent in short-term registrations. A tendency towards adaptation of the chewing performance was observed in repeated registrations. The changes indicated an increased mandibular velocity and displacement, analogous to changes in the movement pattern induced by prosthetic rehabilitation but not so pronounced. The findings in this series of investigations indicate that oral function is reflected in quantitative parameters, e.g. mandibular velocity and displacement, within a relatively consistent overall chewing pattern. Thus, increased mandibular velocity and displacement could be interpreted as improved oral comfort.

Adult↗
PubMed1983

Chewing patterns before and after treatment with completè maxillary and bilateral distal-extension mandibular removable partial dentures.

Prosthodontic rehabilitation with complete maxillary dentures and mandibular bilateral distal-extension removable partial dentures did not change the general masticatory function to any great extent. However, the velocity of the mandible was increased, especially in the opening phase, and so was the mandibular displacement. The latter seems to be the cause for a long closing duration. The chewing cycle became more even and teardrop shaped, and the prosthodontic rehabilitation also resulted in a decrease of the number of chewing cycles. The Selspot system offers a possibility to study adaptation to prosthodontic treatment objectively by measurements of time and movement.

Adaptation, Physiological↗
PubMed1982

Positions of the mandible during chewing and swallowing recorded by light-emitting diodes.

The Selspot system has been developed to record mandibular movements with LED. The aim has been to make a system that is easy to manipulate and permits chewing performance with only minimal mechanical interferences. This study was performed to obtain information on the suitability of the Selspot system for collecting data on the cranial position of the mandible during chewing and swallowing. The results coincided with reports by others using different methods, and the suitability of the system was regarded as good for studying occlusal position during function. The following conclusions could be drawn from the results: 1. In the sagittal plane the chewing activity was performed in a more anterior position than the swallowing contact position. 2. The lateral and vertical cranial position is unstable in the beginning of the chewing period but stabilizes to the occlusal position in the latter half of the chewing period. 3. The occlusal position during chewing does not seem to be a single position but rather a three-dimensional occlusal zone.

Adult↗
PubMed1982

Interocclusal distance measurement comparing chin and tooth reference points.

In a group of nine dentate students with a mean age of 23.1 years, a comparison of their interocclusal distances was determined using tooth and chin reference points. This determination was made with two reference LEDs, one attached to a lower tooth and the other attached to a point on the chin. These two LEDs were registered simultaneously using the Selspot system and analyzed with the use of a computer. Three different methods were used to establish the interocclusal distance: a phonetic method, a relaxation method, and a swallowing method. Independent of the method selected, there was a greater interocclusal distance recorded by the tooth-attached reference LED. This study indicates that, in the clinical determination of interocclusal distance, where a chin reference is used the dentist should be aware of this difference--especially when lip activity is involved.

Adult↗
PubMed1982

The relative movements of the chin and the mandible during chewing.

The suitability of the soft tissue over the chin as a reference point in studies of mandibular performance during chewing was investigated. The movements of reference diodes (LEDs), one on the chin and the other attached to the lower front tooth, were registered simultaneously using the Selspot system and analysed in relation to the reference system in this method. With respect to chewing rhythm, the conformity of the behaviour of the two diodes-or the two tissue locations-was good, thus allowing the conclusion that the chin reference point is suitable for analysing chewing rhythm. Vertical displacement and velocity were less marked with the chin reference than with the tooth reference, however, indicating that the skeletal part of the mandible moves within the tissues envelope. The difference in movement at maximal opening was significant, the magnitude of the difference being between 12 and 20%. Lateral displacement seemed to be of similar magnitude, although a tendency towards larger movements of the chin point than of the tooth was found.

Adult↗
PubMed1982

Computer-analysed movements in three dimensions recorded by light-emitting diodes. A study of methodological errors and of evaluation of chewing behaviour in a group of young adults.

Mandibular movements recorded by means of intraorally placed light-emitting diodes (LEDs) were described and tested. By using a reference system attached to the test subject, the influence of head movements on the registration of the mandibular movements could be avoided. The errors of the method were tested. The stability of the reference system during function was found to be greater when the light impulses did not have to penetrate the lip. A limited clinical test was performed and the following observations were made: the mean cycle duration was, after the first cycles, stable through the whole chewing phase, 0.52 s when chewing crispbread; the duration of the occlusion phase appeared to be shorter than that of the opening and closing phases; the velocity of the mandible was greater in the opening phase than in the closing phase, with a mean velocity of 84 and 70 mm/s respectively; the clinical test showed that the method was easy to handle in the clinical situation, thereby creating an instrument for studies in larger groups of patients. By adding a simple computer program, the manual analysis could be reduced considerably and a number of variables could be measured with a high degree of precision.

Adult↗
PubMed1981

Chewing patterns in dentate and complete denture wearers - recorded by light-emitting diodes.

Chewing patterns of ten dentate and eleven edentulous test subjects were recorded by a computer based on light-emitting diodes and photosensitive detector-surfaces (Selspot-system). A comparison of the mandibular pattern between the two groups was made with respect to chewing rhythm and degree of mandibular displacement and velocity. Differences could be found between these two groups showing a higher chewing rhythm and mandibular velocity in the dentate group. Also greater chewing-cycles were performed by the dentate persons. These differences seemed to some extent have followed as a results of adaptation to a complete denture situation.

Adult↗
PubMed1980

Mandibular movements during mastication before and after rehabilitations with new complete dentures recorded by light-emitting-diodes.

Mandibular movements in wearers of complete dentures were registered before and after rehabilitation with new dentures by light-emitting diodes (LEDs). The duration of the opening, closing and occlusion phases as well as the whole chewing cycle were studied. The closing phase had the longest duration of the three phases, 0.36 s, and represented 45% of the duration of the total chewing cycle. Only minor changes in the movement pattern were found when comparing different test-foods and after rehabilitation with new dentures.

Aged↗
PubMed1979

Mandibular movements of young adults recorded by intraorally placed light-emitting diodes.

Mandibular chewing movements of 10 young adults were registered with LED. The registrations were performed manually, and the following observations were made: 1. The mean cycle duration was reduced from 1.12 seconds for cycle 1 to 0.76 second for cycle 16. 2. The duration of the opening phase appeared to be shorter than that of the closing phase. 3. The maximal vertical movement of the mandible decreased throughout the chewing period. The results obtained in this study agree with those reported by other investigators and indicate that a system using LED is suitable for analyzing the mandibular movement pattern in clinical situations.

Adult↗
PubMedDate not supplied

Laser-welded titanium frameworks supported by implants in the edentulous maxilla: a 2-year prospective multicenter study.

PURPOSE: The aim of this study was to evaluate the clinical and radiographic performance of patients who received implants and fixed prostheses with laser-welded titanium frameworks. MATERIALS AND METHODS: Fifty-eight consecutive patients were treated with 349 osseointegrated implants ad modum Brånemark in the edentulous maxilla at 6 implant centers. The patients were randomly arranged into 2 groups at the time of final impression. Twenty-eight patients received laser-welded titanium frameworks and 30 patients received conventional cast frameworks. Clinical and radiographic data were collected for 2 years in function. RESULTS: The 2 groups of patients showed similar results. The 2-year overall cumulative implant survival rate from the time of implant placement and prosthesis insertion was 93.7% and 96.2%, respectively. The corresponding cumulative survival rate for prostheses was 96.6%. Two patients, 1 from each group, failed completely and resumed using conventional complete dentures. The only obvious factor that could possibly be related to the 2 complete failures was a smoking habit. However, it was not possible to significantly correlate implant failures to smoking habits in this study. No fractures were observed in the frameworks or implant components, and both groups experienced the same frequency of resin veneering material fractures. The overall average marginal bone loss was 0.4 mm (SD 0.8 mm). CONCLUSION: Patients treated with implant-supported prostheses fabricated with laser-welded titanium frameworks in the edentulous maxilla presented comparable results to patients with conventional cast frameworks after 2 years in function.

Adult↗