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Biomedical subjects

J E Brouwers

Publications and source records attributed to J E Brouwers.

4 recordsLinked to original sources

[Dental implants in tooth grinders].

Bruxism (tooth grinding and clenching) is generally considered a contraindication for dental implants, although the evidence is usually based on clinical experience only. So far, studies to the possible cause-and-effect relationship between bruxism and implant failure do not yield consistent and specific outcomes. This is partly due to the large variation in the technical and the biological aspects of the investigations. Although there is still no proof that bruxism causes overload of dental implants and their suprastructures, a careful approach is recommended. Practical advices as to minimize the chance of implant failure are given. Besides the recommendation to reduce or eliminate bruxism itself, these advices concern the number and dimensions of the implants, the design of the occlusion and articulation patterns, and the use of a hard nightguard.

Bite Force↗

Electromyographic parameters related to clenching level and jaw-jerk reflex in patients with a simple type of myogenous cranio-mandibular disorder.

A discriminant analysis has been applied on several electromyographic (EMG) parameters of the masseter and the anterior temporal muscles, related to clenching and the jaw-jerk reflex, to characterize jaw muscle function of patients with craniomandibular disorder (CMD) with respect to controls. The subject samples, matched for age, consisted of 20 females with myogenous CMD, and 20 symptom-free females. The jaw-jerk reflex was elicited by a downward-directed mandibular load, transmitted by a bite-fork causing a similar occlusion and bite-rise as a splint. The patients differed mainly from the controls by smaller maximum EMG activity in both muscle groups (P less than 0.05 with the bite-fork inserted). This finding was related to a smaller muscle strength as the EMG level did not improve with pain-free jaw muscles after therapy using a relaxation splint. Discriminating factors of secondary importance were an enhanced bilateral asymmetry in the muscle activity of the patients, and in the reflex amplitude normalized for background EMG activity. In all subject samples, the activity of the anterior temporal muscles decreased with respect to the masseter muscles when the bite-fork was inserted (P less than 0.05-0.001). The therapeutic effect of a relaxation splint may, in part, be related to a relief of the temporal muscles.

Adult↗

Dynamic loading of surgical knots.

Lately, many suture materials have been introduced. Their physical characteristics in combination with knots are not well known. In this study, seven knots (square--1=1, 2=1, 2=1-S and 1=1=1--and sliding--SxSxS, S=S parallel S and 1-S parallel S parallel S) made in seven suture materials (plain catgut, Dexon [polyglycolic acid)] Maxon [polyglyconate], PDS [polydiaxone], Vicryl [polyglactine 910], Mersilene [polyester fiber], Prolene [polypropylene] were tested dynamically to ascertain tensile strength. The knots were classified as "predominantly breaking" (PB) and "predominantly slipping" (PS). A new method for statistical analysis, the Kaplan-Meier survival estimate, was introduced. Square knots provided good mechanical results but did not prevent slippage completely. Most sliding knots were weak. The 1=1=1 knot was superior. PS knots (1=1, 2=1, SxSxS and S=S parallel S) were unsuitable for surgical practice in monofilament or coated multifilament suture materials. The classification PB and PS knots gave an easy impression of the knot holding capacities. Application of the Kaplan-Meier estimate resulted in a more realistic analysis than classical methods.

Materials Testing↗