The immediate effect of hard and soft splints on the EMG activity of the masseter and temporalis muscles

Abstract

The aim of this study was to compare the effects of hard and soft splints on the activity of the anterior temporalis and masseter muscles. Surface EMG recordings were made from these muscles during clenching at 10% of maximum, 50% of maximum and at maximum clench, both before and after insertion of a hard splint. This sequence was then repeated with a soft splint. The relative level of activity in the anterior temporalis and masseter muscles at all three activity levels was quantified by means of an Activity Index, which provides a measure of the balance of activity in the masseter relative to the activity in the anterior temporalis muscle. It was found that hard splints led to a decrease in EMG activity in relation to activity with no splint in both muscles at maximum clench and particularly the anterior temporalis. Soft splints produced a slight increase in activity of both muscles, but particularly the masseter muscle. The Activity Index indicated a shift in the balance of activity away from the anterior temporalis muscles with both splints, particularly at 10% of the maximum clenching level. It is possible that the decrease in activity of the temporalis muscles relative to the masseter muscles may be a factor in the therapeutic effect of both a hard and a soft splint, although the decrease is clearly greater with the hard splint.

Evaluation of the effect of two different occlusal splints on maximum occlusal force in patients with sleep bruxism: a pilot study

“…Although, these occlusal splints have slightly different appearances and properties, in fact, scientific evidence supports the use of hard acrylic resin occlusal splints12,19,20,21 that are preferentially of full coverage, located in the maxillary arch, with simultaneous, even, and bilateral contacts, and have anterior guidance and canine protected articulation 22,23. On the other hand, soft appliances have been less documented in the scientific literature, however some researchers suggest the use of soft-resin appliances24,25,26,27 that are easily fabricated, and may be inserted at an initial appointment, so practitioners may desire the use of soft appliances.…”

Types of Occlusal Splint in Management of Temporomandibular Disorders (TMD)

“…Supporting the pervious trail finding, another EMG study comparing the effects of hard and soft Occlusal appliances on the activity of the masseter and temporalis muscles during controlled clenching, the muscles activity was decreased more with use of a hard occlusal appliance, and the soft Occlusal appliances produced a slight increase in master and temporalis muscles activity [11].…”

Patient responses to vacuum formed splints compared to heat cured acrylic splints: pilot study

“…The vacuum formed splints and the heat cured acrylic splints in this study were fabricated in a similar manner as described in several studies [10,17]. They were all rigid and had a freedom of movement in all excursions [18,19]. The splints did not cause any irreversible changes in the occlusion or in the temporomandibular joint [12].…”