Indian Journal of Dental ResearchIndian Journal of Dental ResearchIndian Journal of Dental Research
HOME | ABOUT US | EDITORIAL BOARD | AHEAD OF PRINT | CURRENT ISSUE | ARCHIVES | INSTRUCTIONS | SUBSCRIBE | ADVERTISE | CONTACT
Indian Journal of Dental Research   Login   |  Users online: 130

Home Bookmark this page Print this page Email this page Small font sizeDefault font size Increase font size         

 


 
Table of Contents   
ORIGINAL RESEARCH  
Year : 2011  |  Volume : 22  |  Issue : 2  |  Page : 303-308
An electromyographic study to assess the minimal time duration for using the splint to raise the vertical dimension in patients with generalized attrition of teeth


1 Department of Prosthodontics, MAIDS, New Delhi, India
2 Department of Prosthodontics, CDER, AIIMS, New Delhi, India
3 Department of Neurology, AIIMS, New Delhi, India

Click here for correspondence address and email

Date of Submission20-Jun-2010
Date of Decision14-Sep-2010
Date of Acceptance10-Nov-2010
Date of Web Publication27-Aug-2011
 

   Abstract 

Background: To investigate the effect of restoration of lost vertical by centric stabilizing splint on electromyographic (EMG) activity of masseter and anterior temporalis muscles bilaterally in patients with generalized attrition of teeth.
Materials and Methods: EMG activity of anterior temporalis and masseter muscle was recorded bilaterally for 10 patients whose vertical was restored with centric stabilizing splint. The recording was done at postural rest position and in maximum voluntary clenching for each subject before the start of treatment, immediately after placement of splint and at subsequent recall visits, with splint and without the splint.
Results: The EMG activity at postural rest position (PRP) and maximum voluntary clench (MVC) decreased till 1 month for both the muscles. In the third month, an increase in muscle activity toward normalization was noted at PRP, both with and without splint. At MVC in the third month, the muscle activity without splint decreased significantly as compared to pretreatment values for anterior temporalis and masseter, while with the splint an increase was seen beyond the pretreatment values.
Conclusion: A definite response of anterior temporalis and masseter muscle was observed over a period of 3 months. This is suggestive that the reversible increase in vertical prior to irreversible intervention must be carried out for a minimum of 3 months to achieve neuromuscular deprogramming. This allows the muscle to get adapted to the new postural position and attain stability in occlusion following splint therapy.

Keywords: Electromyography, splint, vertical

How to cite this article:
Nanda A, Jain V, Srivastava A. An electromyographic study to assess the minimal time duration for using the splint to raise the vertical dimension in patients with generalized attrition of teeth. Indian J Dent Res 2011;22:303-8

How to cite this URL:
Nanda A, Jain V, Srivastava A. An electromyographic study to assess the minimal time duration for using the splint to raise the vertical dimension in patients with generalized attrition of teeth. Indian J Dent Res [serial online] 2011 [cited 2019 Dec 10];22:303-8. Available from: http://www.ijdr.in/text.asp?2011/22/2/303/84309
Tooth surface loss is a normal physiological process that occurs throughout life. [1] However, if the rate of wear challenges the viability of teeth, then it is considered to be pathological. [2],[3] Occlusal wear leads to a reduction in tooth length and significant dimensional changes in facial morphology. [3] The loss of vertical due to attrition causes excessive closure, which drives the mandible forcefully upward to maintain contact with maxillary teeth. This leads to gradual closure of space between the head of the condyle and articular disc causing degenerative changes, accompanied with pain and discomfort during mandibular movements. If the bite is not raised and restored, then the condition may worsen. The effective management of such patients is an ongoing challenge for dental professionals as the condition can affect both ends of the age spectrum and, thus, a large proportion of people. [1]

Management of patients with tooth surface loss can be done with reversible means or irreversible means. [2] Any irreversible methodology must be preceded by prior observation with reversible means. The recommended period for observation of reversible means is between 4 and 6 weeks. [4] Reversible methods comprise the use of permissive splints or Dahl's appliance. A permissive splint allows the teeth to move on the splint unimpeded thus allowing the condyle head and disk to function anatomically, for example, stabilization splint. [4]

The first reports describing the use of surface electro-myography in dentistry was published in 1950s. Since then it has been useful in documenting changes in muscle function before and after therapeutic interventions. [5] The clinical use of surface electromyography has been proposed for discerning various physiological states as well as during several states of dysfunction. Studies on normal masticatory apparatus have concluded that maximum muscle activity (and hence maximum muscle function) requires mandible to be in a stable centric position and bilateral posterior contacts. This position also ensures symmetry in muscle activity of left and right sides. [6],[7] Also, it has been noted that lower muscle activity is recorded with fewer number of occlusal contacts at maximum voluntary clench conditions than with more number of occlusal contacts. [8],[9] It has also been concluded by these studies that masseter contributes to most of the isometric force made by clenching, [10],[11] while temporalis is a postural muscle controlling mandibular movement during excursive movements. [9] Temporalis muscle shows maximum changes during swallowing and chewing. In maximum voluntary clenching, men achieve higher muscle activity than females for masseter muscle and during deglutition women achieve higher muscle activity than men for the digastrics muscles. [6]

The routine use of splints as a diagnostic modality prior to any irreversible permanent alteration of tooth structure is done, necessitates correlation of clinical findings with a sound scientific basis with an understanding of the physiology over a longer than stipulated duration (of 4?6 weeks). A sufficient amount of time should allow biological adaptive changes to occur in lengthened muscle fiber. [12] The present study provides a scientific investigation to the use of splints in healthy individuals with generalized attrition of teeth over a 3 month duration. The working hypothesis of the study is that restoration of lost vertical dimension in patients with generalized attrition of teeth does not have any influence on electromyographic (EMG) activity of anterior temporalis and masseter muscle.


   Materials and Methods Top


Ten patients (six male and four female) with generalized attrition and full complement of teeth, within the age group of 35?50 years were selected. Patients with neuromuscular disorder, TMD problems, occlusal correction, low IQ, and any drug therapy were excluded. Reduction in vertical was clinically assessed by extraoral features and intraorally by the morphology of teeth as well as increased interocclusal space. Interocclusal distance was confirmed by facial measurements at physiological rest position and maximum intercuspation and deducting the latter from the former. Any case of compensated lost vertical was ruled out. All patients were treated by the same operator and informed written consent was obtained from the subjects after explaining the treatment plan.

Face bow transfer was done with quick mount face bow to Whipmix semi adjustable articulator. To guide the mandible in centric relation bimanual palpation along with Lucia jig was used. Reduced vertical was assessed and it was raised by 1.5?2 mm in second molar region. Centric relation was recorded with help of bite wax. Protrusive relation was recorded to adjust the condylar guidance. The extent of the maxillary splint was made up to incisal one-third of all teeth labially/ bucally and 10?12 mm palatally. Occlusal surface was made relatively flat so that posterior mandibular buccal cusps contacted the flat surface with equal force. Canine guidance on lateral excursive movement and posterior disclusion on anterior excursive movement was provided. The splints were processed in clear heat cure resin.

Lateral cephalogram radiographs were taken without the splint at postural rest position, with splint at postural rest position and with splint at maximum intercuspation. These cephlograms were superimposed to confirm only vertical down ward movement of condyle with splint, without any anteroposterior movement.

Bilateral EMG signals for each patient were recorded simultaneously for anterior temporalis and masseter muscles. EMG activity was recorded pretreatment, immediately after splint insertion, 1 week, 1 month, and 3 months after splint insertion. All post-splint insertion recordings were recorded at postural rest and maximum voluntary clench position with and without splint. Eight channel electromyography was performed using surface electrodes (Nicolet Biomedical Madison, WI, USA). Prior to recording, the patients were introduced to EMG apparatus and seated in a comfortable position with head supported and in natural erect position. The electromyography was standardized with a fixed calibration being followed for each patient. Both anterior temporalis and masseter muscles were palpated and the bipolar silver chloride surface electrodes were placed using conduction gel and secured with an adhesive tape. Electrode placement was standardized for the left and right sides. A common ground electrode was placed at the forehead. Hence, one body electrode and one reference electrode was used for each muscle and a total of eight surface electrodes for both temporalis and masseter muscle were used bilaterally and one earth electrode for 8 channel electromyography. A section of recording of signals where the activity in all channels was steady over a 5-s period was taken [Figure 1]. Quantitative values of amplified motor unit potentials (AMUP) in microvolts were measured from base to peak of recorded graph using the computer-assisted programming (Medelec, Synergy, UK) and mean value of three readings were computed and tabulated on XL sheet.
Figure 1: Representative EMG at various instances

Click here to view


Descriptive analysis including arithmetic mean and standard deviation were calculated for all the EMG values recorded at the postural rest position and maximum voluntary clench position with and without the splint. The STATA 10.0 version of software was used to statistically compare the readings with splint (WS) and without splint (WOS) within the group, for which paired t- test was applied to find the level of significance. For comparison at different time intervals, multivariate repeated measure ANOVA (RMANOVA) with Bonferroni post-hoc adjustments was applied using SPSS software.


   Results Top


The pretreatment EMG activity of anterior temporalis and masseter was as shown in [Table 1]. The EMG activity at PRP [Table 2], [Figure 2] and [Figure 3] and MVC [Table 3], [Figure 4] and [Figure 5] decreased till 1 month for both the muscles. Significant decrease was seen at immediate insertion of splint only for masseter, at PRP (0.05) and at MVC (0.039) with the splint. Significant decrease was seen at 1 week only for masseter at PRP (WOS=0.04, WS=0.028) and at MVC (WOS=0.045, WS=0.028). Significant decrease was seen at 1 month for masseter at PRP (WOS=0.01, WS=0.008) and at MVC (WOS=0.028, WS=0.017) as well as for anterior temporalis at PRP (WOS=0.05, WS=0.04) and at MVC (WOS=0.05, WS=0.049). In the third month, an increase in muscle activity toward normalization was noted at PRP, both with and without splint, with a significant increase only in masseter with splint (0.046). At MVC in the third month, the muscle activity without splint decreased significantly as compared with pretreatment values for both, the anterior temporalis (0.046) and masseter (0.014), while with the splint an increase was seen beyond the pretreatment values, which was significant only in masseter (0.000).
Figure 2: Comparison of muscle activity for anterior temporalis and masseter muscle without splint at different time intervals in postural rest position

Click here to view
Figure 3: Comparison of muscle activity for anterior temporalis and masster muscle with splint at different time intervals in postural rest position

Click here to view
Figure 4: Comparison of muscle activity for anterior temporalis and masseter muscle without splint at different time intervals during maximum voluntary clenching

Click here to view
Figure 5: Comparison of muscle activity for anterior temporalis and masseter muscle with splint at different time intervals during maximum voluntary clenching

Click here to view
Table 1: EMG muscle activity for left and right side anterior temporalis and masseter muscle before start of treatment

Click here to view
Table 2: Comparison of muscle activity for the anterior temporalis and masseter at postural rest position

Click here to view
Table 3: Comparison of muscle activity for the anterior temporalis and masseter at maximum voluntary clench

Click here to view



   Discussion Top


A prudent approach to increase OVD is to assess with a removable appliance (like an occlusal splint) for a trial period of observation. [13] In the present study, after immediate insertion of splint an immediate drop in muscle activity was noted at both the states of postural rest and maximal voluntary clenching. This is explained by the fact that there is insufficient time for altered subconscious behavior pattern or reflexes to develop, due to changes in peripheral receptors and not muscle spindles per se. These peripheral receptors likely to be involved include those of temperomandibular joint (due to altered condylar position), from muscles (due to longer working length), from periodontal ligament (due to altered tooth contacts) and from lips, tongue, and oral mucosa due to a foreign object (splint). [14] The lower muscle activity while wearing the splint compared with without the splint is again due to the peripheral inputs. Alternatively, it can be accounted for because of the relative inexperience with the wearing of the appliance and apprehension of soft tissue damage together with breakage of the splint by the patient.

At 1 week, there was a further decrease in the activity of masseter and temporalis both during rest and at maximum clenching, though not to a significant level. This may be attributed to increase in the vertical dimension of jaw elevator muscles during maximal clenching. The fall in amplitude with an increased vertical is due to the reduction in activation of and increased inhibition of motor neurons in the temporal and masseter muscles. The inhibitory effect by secondary endings of muscle spindle and golgi organ is most likely responsible for fall of electrical activity in temporalis muscle and masseter muscle activity. The inhibitory activity takes place in trigeminal motor nucleus. [6],[15] Additionally, on maximum biting on the splint, the fear of pain and fracturing of teeth may inhibit from performing at full capacity, despite of the fact that patients were instructed to clench as hard as possible. This might have also been augmented by an unfitted position of tooth in the occlusal splint. [16] In the third month, the trend toward normalization at postural rest might indicate a gradual adaptation to new position of mandible as induced by the splint during 3 months of active treatment. This is in contrast to various studies, which show a trend toward decrease in activity and relaxation of muscles. However, these studies are of a shorter duration of time period in the range of immediate, 1?6 weeks. The results of this study are also in agreement with these studies for the same duration. However, lack of follow up for a longer duration by other studies [16],[17],[18] provides in complete support. However, animal studies [19],[20] of increased OVD demonstrate changes at histological and morphological level. These studies do not represent collapse or breakdown at microstructural level, but are suggestive of compensation and adaptation, with problems being encountered only when extreme changes were made or when increased OVD was maintained only on a few teeth. The third reason to explain an increase in muscle activity is explained on the basis of myotactic (stretch) reflex, i.e., stretch of muscle gives rise to a stretch reflex/myotactic reflex contraction. It is monosynaptic, protective jaw reflex, which is elicited when the muscles that elevate the mandible are stretched and in turn activate the muscle spindle afferents. The extent of spindle discharge and thus the rise in muscle tonus will be directly related to the amount of stretch on the elevator muscle and the gamma motor pathway. The gravitational component increases with jaw positioning, causing a higher stimulation of neuromuscular spindles of jaw muscles and thus reflexly increasing the jaw muscle activity. This reflex is responsible for the increased mechanical output. It is noteworthy that at the end of 3 months, the increase in muscle activity toward normalization at postural rest and beyond the pretreatment values at maximal voluntary clenching was not associated with any clinical signs and symptoms.

At maximal voluntary clenching with the splint in the third month, an increase in the activity beyond the pretreatment levels was observed which can be explained on the basis of stretch reflex and increased and better number of tooth contacts and improved stability of occlusion. [7],[8],[9] Factors which might explain an increase in EMG activity on maximal biting may be the reduction of pain and unpleasant feelings, whereby full coverage of occlusal surfaces of teeth and absorption of pressure from periodontal structures of all teeth allows greater muscular activity to develop during maximal clenching on occlusal splint. This may be augmented by the fact that insertion of occlusal splint alters the relationship of maxilla and mandible causing changes such as redistribution of forces over a higher periodontal area in masticatory system and reduction of jaw elevator muscle inhibitory feed back to central nervous system.

The activity without the splint showed a decrease that might be explained based on reduced number of tooth contacts, as a new position is induced by the splint. [7],[8],[9] Under unstable conditions, the potential masseter biting activity is severely reduced possibly to avoid damage to the structures involved in compensatory stabilization.

In conclusion, the main feature which enables dentists to restore the teeth of patient at increased vertical height is the adaptive capacity of the muscle fiber to modify their length and the suppleness of the mandibular sling muscles. This allows the dentist an expanded concept of vertical dimension, embracing neuromuscular determinants besides facial form and occlusal plane. The present study suggests using reversible means to increase vertical for a minimum period of 3 months prior to irreversible intervention to achieve neuromuscular deprogramming, to allow the muscle to get adapted to the new postural position and attain stability in occlusion following splint therapy.

 
   References Top

1.Poyser NJ, Porter RW, Briggs PF, Chana HS, Kelleher MG. The Dahl Concept: Past, present and future. Br Dent J 2005;198:669-76.  Back to cited text no. 1
[PUBMED]  [FULLTEXT]  
2.Kelleher M, Bishop K. Tooth surface loss: An overview. Br Dent J 1999;186:61-6.  Back to cited text no. 2
[PUBMED]    
3.Davies SJ, Gray RJ, Qualtrough AJ. Management of tooth surface loss. Br Dent J 2002; 92:11-6.  Back to cited text no. 3
    
4.Dylina TJ. A common - sense approach to splint therapy. J Prosthet Dent 2001;86:539-45.  Back to cited text no. 4
[PUBMED]  [FULLTEXT]  
5.Klasser GD, Okeson JP. The clinical usefulness of surface electromyography in the diagnosis and treatment of temporomandibular disorders. J Am Dent Assoc 2006;137:763-71.  Back to cited text no. 5
[PUBMED]  [FULLTEXT]  
6.Moreno I, Sanchez T, Ardizone I, Aneiros F, Celemin A. Electromyographic comparisons between clenching, swallowing and chewing in jaw muscles with varying occlusal parameters. Med Oral Patol Oral Cir Bucal 2008;13:E207-13.  Back to cited text no. 6
    
7.Forrester SE, Allen SJ, Presswood RG, Toy AC, Pain MT. Neuromuscular function in healthy occlusion. J Oral Rehabil 2010;37:663-9.   Back to cited text no. 7
[PUBMED]  [FULLTEXT]  
8.Ferrario VF, Serrao G, Dellavia C, Caruso E, Sforza C. Relationship between the number of occlusal contacts and masticatory muscle activity in healthy young adults. Cranio 2002;20:91-8.  Back to cited text no. 8
[PUBMED]    
9.Kerstein RB. Combining technologies: A computerized occlusal analysis system synchronized with a computerized electromyography system. Cranio 2004;22:96-109.  Back to cited text no. 9
[PUBMED]    
10.Christensen LV, Kundinger KK. Activity index and isometric contraction velocity of human jaw muscles. J Oral Rehabil 1991;18:555-61.  Back to cited text no. 10
[PUBMED]    
11.Visser A, McCarroll RS, Naeije M. Masticatory muscle activity in different jaw relations during submaximal clenching efforts. J Dent Res 1992;71:372-9.  Back to cited text no. 11
[PUBMED]  [FULLTEXT]  
12.Gross MD, Nissan J, Ormianer Z, Dvori S, Shifman A. The effect of increasing occlusal vertical dimension on face height. Int J Prosthodont 2002;15:353-7.  Back to cited text no. 12
[PUBMED]    
13.Capp NJ. Occlusion and splint therapy. Br Dent J 1999;186:217-22.  Back to cited text no. 13
[PUBMED]    
14.Al-Quran FA, Lyons MF. The immediate effect of hard and soft splints on the EMG activity of masseter and temporalis muscles. J Oral Rehabil 1999;26:559-63.  Back to cited text no. 14
[PUBMED]  [FULLTEXT]  
15.Visser A, McCarroll RS, Naeije M. Masticatory muscle activity in different jaw relations during submaximal clenching efforts. J Dent Res 1992;71:372-9.  Back to cited text no. 15
[PUBMED]  [FULLTEXT]  
16.Holmgren K, Sheikholeslam A, Riise C, Kopp S. The effects of an occlusal splint on the electromyographic activities of the temporal and masseter muscles during maximal clenching in patients with a habit of nocturnal bruxism and signs and symptoms of craniomandibular disorders. J Oral Rehabil 1990;17:447-59.  Back to cited text no. 16
[PUBMED]    
17.Savabi O, Nejatidanesh F, Khosravi S. Effect of occlusal splints on the electromyographic activities of masseter and temporal muscles during maximum clenching. Quintessence Int 2007;38:e129-32.  Back to cited text no. 17
[PUBMED]    
18.Carr AB, Christensen LV, Donegan SJ, Ziebert GJ. Postural contractile activities of human jaw muscles following use of an occlusal splint. J Oral Rehabil 1991;18:185-91.  Back to cited text no. 18
[PUBMED]    
19.Yabushita T, Zeredo JL, Fujita K, Toda K, Soma K. Functional adaptability of jaw- muscle spindles after bite- raising. J Dent Res 2006;85:849-53.  Back to cited text no. 19
[PUBMED]  [FULLTEXT]  
20.Yabushita T, Zeredo JL, Toda K, Soma K. Role of occlusal vertical dimension in spindle function. J Dent Res 2005;84:245-9.  Back to cited text no. 20
[PUBMED]  [FULLTEXT]  

Top
Correspondence Address:
Aditi Nanda
Department of Prosthodontics, MAIDS, New Delhi
India
Login to access the Email id

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0970-9290.84309

Rights and Permissions


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
 
 
    Tables

  [Table 1], [Table 2], [Table 3]

This article has been cited by
1 Intrusion of Supraerupted Maxillary Molar Using a High Interim Restoration on the Defective Opposing Tooth: A Clinical Report
Ye Tao,Xiao Ping Luo,David W. Bartlett
Journal of Prosthodontics. 2014; : n/a
[Pubmed] | [DOI]
2 occlusal vertical dimension and dental implants [oklüzyon dikey boyutu ve dental implantlar]
tekeroǧlu, f. and çömlekoǧlu, m.d. and cömlekoǧlu, m.e. and artunç, c.
cumhuriyet dental journal. 2012; 15(4): 357-363
[Pubmed]



 

Top
 
 
 
  Search
 
    Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
    Email Alert *
    Add to My List *
* Registration required (free)  
 


    Abstract
    Materials and Me...
   Results
   Discussion
    References
    Article Figures
    Article Tables

 Article Access Statistics
    Viewed5009    
    Printed159    
    Emailed15    
    PDF Downloaded158    
    Comments [Add]    
    Cited by others 2    

Recommend this journal