[Evaluation of electromyogram activity and masticatory efficiency in edentulous individuals whose maxillomandibular horizontal relationship records were obtained with three different methods].
OBJECTIVE
This study was performed to investigate the electromyographic (EMG) activity of the masseter muscle and the anterior temporalis muscle, as well as the masticatory efficiency after insertion of the dentures in edentulous individuals whose maxillomandibular horizontal relationship records were obtained with three different methods.


METHODS
Ten edentulous individuals were enrolled in this study. Three types of complete dentures for these 10 edentulous patients were made according to their different maxillomandibular horizontal relationship records. The maxillomandibular horizontal relationship of complete dentures was recorded by three methods. In the first method (A), the maxillomandibular horizontal relationship was determined at the gothic arch tracing apex. In the second method (B), the relationship was 1 mm anterior to the tracing apex with the gothic arch. In the last method (C), the horizontal jaw relation was recorded by natural chewing. The muscular activities of the three complete dentures were examined by EMG. The masticatory efficiency was evaluated based on the absorbance. The differences among the dentures were statistically analyzed with SPSS 17.0.


RESULTS
The muscular activities of dentures B and C were much higher than that of denture A during clenching in the center occlusion and during chewing (P<0.05). The highest asymmetry index was found indenture C, which was significantly higher than those of dentures A and B (P<0.05). A statistically significant increase in the absorbance was observed between dentures B and C (P<0.05); otherwise, no statistically significant differences were observed (P>0.05) between B and C.


CONCLUSIONS
Given the limitations of this experimental design, in edentulous individuals the maxillomandibular horizontal relationship recorded at 1 mm anterior to the tracing apex with the gothic arch can improve the function of masticatory muscles and strengthen masticatory performance.
Dept. of Prosthodontics, Qilu Hospital, Shandong University, Jinan 250012, China.
Liu
L
Cuiling
Dept. of Prosthodontics, School of Stomatology, Shandong University, Shandong Provincial Key Laboratory of Oral Tissue Regeneration, Jinan 250012, China.
Yang
Y
Liyuan
Dept. of Prosthodontics, School of Stomatology, Shandong University, Shandong Provincial Key Laboratory of Oral Tissue Regeneration, Jinan 250012, China.
Zheng
Z
Zheng
Dept. of Prosthodontics, School of Stomatology, Shandong University, Shandong Provincial Key Laboratory of Oral Tissue Regeneration, Jinan 250012, China.
Gao
G
Xu
D003768:Dental Occlusion, Centric; D003824:Denture, Complete; D004576:Electromyography; D006801:Humans; D008409:Mastication; D009066:Mouth, Edentulous; D013703:Temporal Muscle
complete denture; electromyogram; masticatory efficiency; maxillomandibular horizontal relationship records