الفهرس 
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Abstract
Seven patients were selected for this study. Patients were having
edentulous maxilla. Two restorable canines having adequate bone support
were only the remaining natural teeth in the lower ridge. Root canal
treatment was carried out to the 2 remaining lower canines. The crowns
were reduced to 1-2 mm above the free gingival margin and contoured to a
dome shape preparation. Upper conventional complete upper denture and
lower complete tooth supported overdenture were constructed for each
patient.
The EMG activity of masseter and temporalis muscles was recorded for
each patient during maximum clinching and eating soft food (banana).
The root canals of the two abutments were prepared to receive the post
part of the ball attachment. Impression was made for the seated castable
posts in the root canals. Construction of the attachment (post, coping and
ball head) was done and cemented in the patient mouth. The metal housings
with the rubber o-rings were seated on the ball heads of the attachment.
Relief of the fitting surface of the lower denture was done opposite to the
the two metal housings using an acrylic bur. The relieved areas were filled
with pink, fast cold-cure acrylic resin mix in dough stage. The denture was
inserted in the patient’s mouth and the patient was instructed to close in
maximum intercuspation till full curing of the resin to a hard set. The
denture was removed, cleaned, and flash was trimmed and delivered to the
patients
Another EMG activity of masseter and temporalis muscles was
recorded during maximum clinching and eating soft food (banana) for the
tooth retained lower overdenture against the upper conventional complete
denture.
Surface electrodes were repositioned at the same elctrode sites using a
face transparent template constructed for each patient at the end of the 1st
electromyographic record. The 2nd electromyographic record was done with
the same procedures and under the same circumstances of the 1st record.
Data obtained from the electromyographic evaluation of the 2 masticatory
muscles (masseter and temporalis) were collected, arranged, tabulated and
statistically analyzed.
The results of this study reviled statistical insignificant difference
between the electromyographic activity of masseter and temporalis muscles
for tooth supported overdentures and tooth retained overdentures during
maximum clenching. However statistically significant decrease of muscle
activity of the two studied muscles was recorded for the tooth retained
mandibular overdenture compared with the tooth supported mandibular
overdenture during chewing soft food .