|Year : 2022 | Volume
| Issue : 3 | Page : 249-255
A comparative study to evaluate surface electromyographic correlations of mandibular implant-supported overdentures to conventional complete dentures in edentulous patients: An in vivo study
Yashi Garg, Rahul Nagrath, Manesh Lahori
Department of Prosthodontics and Crown and Bridge, K. D. Dental College and Hospital, Kota, Uttar Pradesh, India
|Date of Submission||14-Jul-2021|
|Date of Decision||02-May-2022|
|Date of Acceptance||02-May-2022|
|Date of Web Publication||18-Jul-2022|
K. D. Dental College and Hospital, NH-2, P. O. Chattikara, Mathura - 281 121, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
Aim: The aim of this study was to compare the function and coordination of masticatory muscles for patients with two implant-supported mandibular overdenture (ISOD) with that of conventional complete dentures (CCD) using surface electromyography (sEMG). The objectives were to assess the muscle activity (efficiency) and clinical outcome after the transition of CCD patients to ISOD.
Setting and Design: This was a crossover study.
Materials and Methods: This clinical trial was conducted in the department of prosthodontics. A total of 15 patients (nine males and six females) were assessed using sEMG. In each patient, a total of four surfaces were examined above the following muscles – right and left masseter and right and left temporalis muscles. The electromyography readings were recorded to assess muscle activity during Clenching, cotton roll clenching, and chewing. The readings were recorded first for CCD and then for ISOD (after installing attachments).
Statistical Analysis Used: Data analysis was done using independent t-test and one-way ANOVA.
Results: Mean muscular activity of masseter during clenching, cotton roll clenching, and chewing for patients with ISOD (44.3 ± 11.2 μV, 41.1 ± 13.4 μV, and 45.2 ± 17.5 μV) was higher than CCD (26.0 ± 11.3 μV, 22.6 ± 9.7 μV, and 24.2 ± 9.5 μV). The mean muscular activity of temporalis during clenching, cotton roll clenching, and chewing was also higher with ISOD (47.9 ± 11.2 μV, 45.6 ± 11.9 μV, and 51.0 ± 14.4 μV) than CCD (31.0 ± 12.2 μV, 29.7 ± 15.3 μV and 31.9 ± 14.2 μV). No statistically significant result was found between masseter and temporalis muscle activity on both sides (P < 0.05), indicating symmetrical activity on both the sides.
Conclusion: Two-ISODs prove to be a better and efficient treatment modality in rehabilitating edentulous patients as it enhances retention and also increases masticatory muscle activity and chewing efficiency.
Keywords: Electromyography, implant-supported overdenture, masseter muscle, masticatory muscle activity, temporalis muscle
|How to cite this article:|
Garg Y, Nagrath R, Lahori M. A comparative study to evaluate surface electromyographic correlations of mandibular implant-supported overdentures to conventional complete dentures in edentulous patients: An in vivo study. J Indian Prosthodont Soc 2022;22:249-55
|How to cite this URL:|
Garg Y, Nagrath R, Lahori M. A comparative study to evaluate surface electromyographic correlations of mandibular implant-supported overdentures to conventional complete dentures in edentulous patients: An in vivo study. J Indian Prosthodont Soc [serial online] 2022 [cited 2022 Aug 10];22:249-55. Available from: https://www.j-ips.org/text.asp?2022/22/3/249/351280
| Introduction|| |
Mastication is a complicated process that receives input from voluntary and automatic motor pathways. In dentulous subjects, this process is well coordinated, but in edentulous subjects, masticatory process gets affected as there are resorption of bone and muscular hypotonicity, which, in turn, reduces various functions of the stomatognathic system. Edentulous patients often complain of unstable lower dentures, leading to diffidence, inefficacious chewing, and in general disappointment with the prosthesis. Such patients when rehabilitated with mandibular implant-retained overdentures show improved masticatory function and overall satisfaction.
Many techniques exist for studying the stomatognathic mechanism; the electromyographic readings are one of the most comprehensible and valuable means as it directly records muscle activity. Hardyck in the 1960s clinical used surface electromyography (sEMG) to treat specific disorders. Robert E. Moyers is known as a pioneer for using electromyography (EMG) in dentistry. He used it to verify the neuropsychological analysis of the factors linked to prosthetic rehabilitation procedures. A study done by Dakhilalian et al., Tiwari et al., and van der Bilt et al. showed that masticatory function and coordination improves in edentulous patients rehabilitated with two-implant-supported overdenture.,,, de Liz Pocztaruk et al. found out that patients with overdenture with ball or bar–clip attachment showed enhanced masticatory performance and satisfaction, but the result was not equivalent to those found for dentate subjects. In a study done by Soni et al., it was observed that all-on-four treatment shows the highest biting force and chewing efficiency, followed by implant-supported overdenture and complete denture. Bersani et al. found that during rest maintenance position, the patients with mandibular implant-supported prosthesis in accordance with the Branemark protocol and removable maxillary complete dentures showed increased electromyographic activity than the dentulous patients.
In consideration to the currently available studies, it has been observed that the comparison between conventional complete denture (CCD) and implant-supported mandibular overdenture (ISOD) has mostly been recorded on different patients. The previous studies have made use of calibrated EMG device which require manual interpretation of reading, leading to human error. This study uses a digital EMG apparatus to obtain precise values of muscle activity which has never been used in the past. The present study aimed to compare the function and coordination of masticatory muscles of the same patients when rehabilitated with conventional and two-ISODs using surface electromyograms. The objectives were to assess the muscle efficiency and clinical success after the transition of CCD patients to ISOD. The null hypothesis stated that the masticatory muscle activity increases when the transition is made from CCD to ISOD.
| Materials and Methods|| |
This crossover trial was conducted in the department of prosthodontics. A total of 15 patients (both male and female) were selected as per the inclusion and exclusion criteria [Schematic Chart 1] and [Figure 1]. The study was accepted by the institutional ethical committee.
Placement of dental implants
These patients were referred for cone-bean computed tomography and routine blood investigation. A dose of prophylactic antibiotic was administered orally an hour before surgery as per the guidelines of Centers for Disease Control and Prevention. Lignocaine 2% with 1:100,000 adrenalin (Septodont, India) was infiltrated locally. A crestal incision was made on the mandibular ridge followed by raising a full-thickness mucoperiosteal flap. Two implants (3.5 mmD × 10 mmL, Touareg™-S Spiral Implant, double-lead threads, ADIN Dental Implant System Ltd.) of selected diameter were placed in B and D regions following a standard protocol. Cover screws were placed over implants and flaps were closed with interrupted sutures. Patients were asked to come after 2 weeks for sutures removal and postoperative checkup.
Fabrication of conventional complete denture
Upper and lower complete denture was fabricated using a standard protocol. Bilaterally balanced occlusion was given using semi-anatomic acrylic resin teeth. Dentures were evaluated for retention, stability, support, esthetics, centric relation, and occlusion. Patients were recalled after 1 week for postinsertion checkup. After 3 months of denture insertion, masticatory muscles (masseter and temporalis) of patients were assessed using sEMG (NeuroTrac Simplex, Verity Medical Ltd., Co., Wexford, Ireland).
Electromyography recording and measurement
In each patient, a total of four surfaces above the following muscles were examined – right and left masseter and right and left temporalis muscles. Pregelled and self-adhesive electrodes of size 23 mm × 50 mm with three surface leads (two recording electrodes and one reference electrode placed on glabella) were used. During this process, patients were made to sit on a chair looking straight at a distant object with a head unsupported. The number of trials in EMG machine was set to one.
- For temporalis muscle, the electrodes were placed by palpating the muscle contraction above a line joining the outer canthus of the eye to the upper ear [Figure 2]
- For masseter, the angle of the mandible was palpated and electrodes were placed anterosuperiorly over the muscle [Figure 3].
The area of electrode placement was cleaned with alcohol in order to accomplish superior conductivity. Readings were taken for three actions such as during clenching (maximum intercuspation), during cotton roll clenching (maximum bite force), and during chewing peanuts for CCD. For recording muscle activity during clenching, patients were asked to relax for 10 s, followed by 10 s of clenching and 10 s of rest. For cotton roll clenching and chewing, patients were asked to rest for 10 s, followed by 10 s of continuous unilateral cotton roll clenching/chewing and 10 s of rest. Implant placement and EMG recordings for all the patients were recorded by the same operator. EMG readings were obtained in microvolt (μV) digitally.
Installation of ball and socket attachment
For second-stage surgery, these patients were recalled after 3 months of implant installation. The region from canine-to-canine was reopened following the same protocols of surgery and healing caps were installed. After 2 weeks, healing caps were removed and ball attachments (ADIN Dental Implant System Ltd.) were installed and tightened to 35–40 N/cm. On the intaglio surface of mandibular denture, metal housings (RS2675SS, stainless steel ball cap, ADIN Dental Implant System Ltd.) and nylon caps (RS2660, plastic ball cap white, 0.35GPa Young' modulus, ADIN Dental Implant System Ltd) were installed using standard technique.
Readings for implant-supported overdenture were then recorded as per the predetermined protocol.
Statistical analysis was done using IBM SPSS statistical software 21.0 statistical software. Shapiro–Wilk test was accustomed to ensure that all variables followed statistical distribution. Bivariate analyses were performed using independent t-test and one-way ANOVA.
| Results|| |
Masticatory muscle activity
The mean values of masseter muscle for patients with ISOD during clenching were 44.3 ± 11.2 μV, during cotton roll clenching were 41.1 ± 13.4 μV, and during chewing were 45.2 ± 17.5 μV, whereas for patients with CCD, the mean values during clenching were 26.0 ± 11.3 μV, during cotton roll clenching were 22.6 ± 9.7 μV, and during chewing were 24.2 ± 9.5 μV. The mean values of temporalis muscle for patients with ISOD during clenching were 47.9 ± 11.2 μV, during cotton roll clenching were 45.6 ± 11.9 μV, and during chewing were 51.0 ± 14.4 μV, whereas for patients with CCD, mean values during clenching were 31.0 ± 12.2 μV, during cotton roll clenching were 29.7 ± 15.3 μV, and during chewing were 31.9 ± 14.2 μV. Thus, from these values, it infers that the activity of masseter and temporalis muscle for patients rehabilitated with ISOD is significantly higher (P = 0.00) than with CCD during all three actions [Table 1].
|Table 1: Mean comparison of the masseter and temporalis muscle activity among implant-supported overdenture and conventional complete denture group|
Click here to view
No statistically significant result was seen in right and left masseter and temporalis muscle activity, indicating symmetry on both the sides [Graph 1] and [Graph 2].
With CCD, the mean activity of temporalis muscle was significantly higher in males than females during cotton roll clenching (P = 0.02) and chewing (P = 0.01), although no significant difference was observed between genders for masseter muscle during all three actions [Table 2].
|Table 2: Gender-wise comparison of masseter and temporalis muscle activity in patients with conventional complete denture|
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With ISOD, the mean activity of temporalis muscle was significantly higher in males than in females during chewing (P = 0.01) though there was no statistically significant difference during clenching and cotton roll clenching. No significant difference was observed among male and female for masseter muscle during all three actions [Table 3].
|Table 3: Gender-wise comparison of masseter and temporalis muscle activity in patients with implant-supported overdenture|
Click here to view
| Discussion|| |
In this study, the null hypothesis that there is a difference in masticatory muscle activity between ISOD and CCD was accepted. The crossover study design used in this study reduces patient variability as comparison of denture was done on the same patient.
In this study, both muscle groups exhibited increased muscle activity in patients with ISODs. This result is congruous with the results of van der Bilt et al. where the mean wave range (MWR) of both masseter and temporalis muscle during mastication with recently constructed CRCDs was significantly reduced as compared to ISODs. Their study also showed that maximum bite is 60–200 times more for ISOD as compared to CCD patients. Dakhilalian et al. in their study also reported decreased MWR of the masseter and temporalis muscles while clenching after removing the attachments. Increase in muscular activity as well as bite force can be attributed to greater retention and stability of the ISODs in relation to CCDs.,,, According to Misch, removable denture exhibits less efficiency in comparison to fixed dentures. This fact was verified in this study as ISOD group showed higher muscle efficiency.
van der Bilt et al. proclaimed that during maximum bite force, the temporalis presents significantly reduced activity with CCD compared to masseter muscle. The muscle activity was comparable for patients with ISOD. In this research, when subjects clenched and chewed with an implant-supported denture, temporalis muscle activity was significantly pronounced compared to the masseter muscle. This recommends that the temporalis muscle is active to a greater extent as opposed to the masseter muscle when ISOD is employed. It implies patients using ISODs had conspicuous excursive movements. The result of the present study, however, is congruous to the research done by Soni et al. where masseter muscle exhibited larger electromyographic activity compared to other muscle group.
In this study, EMG values masseter and temporalis muscle on both sides reported no comparable differences pre- and postattachment installation demonstrating a balance in muscle activity on both sides. This result is analogous to Bersani et al. and Ferrario et al. study, where the wave range of masticatory muscles on both sides did not show appreciable differences when rehabilitated with ISODs., Contrary to this study, Dakhilalian et al. in their study reported significant differences in masseter muscle activity while chewing (P = 0.03), indicating asymmetrical activity with CCD. They also stated that the temporalis muscles showed asymmetrical activity with ISOD.
Temporalis muscle activity with ISOD observed in the study during cotton roll clenching and with CCD was appreciably high in males (P < 0.05). This suggests that the force of contraction of temporalis muscle is reduced when attachments are removed, but the contraction rate of muscle increases. During chewing with ISODs, temporalis muscle shows statistically significant results (P = 0.01) between men and women, indicating that temporalis is more active in men as compared to females during mastication.
In this study, digital sEMG device was used which gives precise value of muscle activity in microvolts. Digital device reduces operator error and data are also easy to interpret. In the past, digital EMG has never been used. In previous studies, either needle electrodes were used or the electrodes were replaced by superficial electrodes wherein the device was calibrated. Therefore, the error margin was higher compared to the present study.
Also, in this study, the same dentures were used for ISOD and CCD electromyographic evaluation. The vertical dimension at rest and vertical dimension at occlusion were therefore sustained throughout the period of research to ensure a similar direction of forces and muscle action.
This research surmises that advocating implant-supported overdentures with two implants in the lower canine region proves to be a beneficial treatment modality to enhance masticatory efficiency for completely edentulous patients. The results of the present study brace the advantages of implant therapy, and patients can be acquainted about the enhancement of oral function with ISOD. Thus, rehabilitating with mandibular implant-supported overdenture will improve masticatory muscle efficiency and chewing efficiency in completely edentulous patients.
Limitations of the study
- Ball attachment was used in this study. Future studies should be done using different attachment systems such as locators
- This study included a limited number of subjects. Future studies should include more subjects for more reliable conclusions
- Future studies should compare muscle efficiency between ISOD and implant-supported fixed prosthesis.
| Conclusions|| |
In accordance with the finding of this in vivo study, the conclusions drawn were that the overall masticatory efficiency enhances in patients with implant-supported overdenture compared to a conventional denture. For both implant-supported overdenture and CCD, temporalis was found to be more active in males than females during chewing and cotton roll clenching. Coordinated and symmetrical muscle activity on both sides was observed in the masseter and temporal muscle with CCD and ISOD both during clenching and chewing.
Rehabilitation with two implants in the mandible remarkably enhances oral function by enhancing overall masticatory efficiency and bite force giving a better quality of life to edentulous patients.
Ethical policy and institutional review board statement
Ethical approval for this study was provided by the Institutional Ethical Committee of K.D. Dental College and Hospital, Mathura (Ref. KDDC/EC/9956A/2021) on December 21, 2018.
Patient declaration of consent statement
The authors certify that appropriate consent was obtained from all the patients included in the study in which they approve to use their photograph and clinical information in the journal. Patients understood that appropriate measures will be taken to conceal their identity and their names will not be published, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3]