TMJ
Effect of the dental arches morphology on the masticatory muscles activities in normal occlusion young adults Teresa Sierpinska1, Piotr Jacunski1, Joanna Kuc2, Maria Golebiewska2, Aneta Wieczorek3, Stanislaw Majewski3 1
Department of Dental Technique, Medical University of Bialystok, Poland, 2Department of Prosthetic Dentistry, Medical University of Bialystok, Poland, 3Department of Prosthetic Dentistry, Collegium Medicum of Jagiellonian University, Cracow, Poland
Objectives: The aim of this study was to assess the relationship between the morphology of dental arches and the activity of the masticatory muscles activities in healthy volunteers with full natural dentition. Methods: Two-hundred youthful Class I volunteers (113 females, 87 males) were clinically investigated. Alginate impressions of dental arches were taken, and plaster casts were prepared and measured. EMG data from eight masticatory muscles was recorded to assess their activities in central occlusion, lateral and protrusive movements. Results: Clinical measurements and plaster casts analyses confirmed normal values of parameters investigated. Most of the arch measurements were significantly larger in the males than in the females. Weak positive correlations were found between overbite and masseter activity in centric occlusion (the right Mm R50.151, P#0.05; the left Mm R50.191, P#0.05). Also, the range of protrusive movement positively correlated with masseter activities in central occlusion (the right Mm R50.194, P#0.05; the left R50.201, P#0.05). Conclusions: The null hypothesis that morphology of dental arches does not affect the masticatory muscles’ activities was rejected. The findings of this investigation indicate that systemic, longitudinal analyses of morphology of occlusion and muscular response, even in normal subjects, are needed. Keywords: Dental arches morphology, Overbite, Overjet, Masticatory muscle activity, Occlusal parameters
Introduction The study of dental anatomy, physiology and occlusion provides one of the basic components of the skills needed to practice all phases of dentistry. For some clinicians, the general principle that becomes operant is ‘‘form follows function.’’ It reflects a concept of interrelating the shape or attributes of something with its function. The form of the teeth is consistent with the function they are to perform and with their position and arrangement in the structures involved in oral motor behavior, especially mastication.1 From the occlusal surface point of view teeth are positioned on the maxilla and the mandible in such a way as to produce a curved arch. Both dental arches contact
Correspondence to: T. Sierpinska, Department of Dental Technique, Medical University of Bialystok, Washington Str. 13, 15-276 Bialystok, Poland. Email: [email protected]
each other in occlusion. The coordination of occlusal contacts, jaw motion, and tongue movement during mastication requires a very intricate control system involving a number of guiding influences from the teeth, their supporting structures, the temporomandibular joints, the masticatory muscles, and the higher centers in the central nervous system.2,3 The dynamic occlusion refers to the occlusal contacts that are made while the mandible is moving, relative to the maxilla.4 The mandible is moved by the muscles of mastication, and the pathways along which it moves are determined not only by these muscles but also by two guidance systems. The posterior guidance system is provided by temporomandibular joints. The anterior guidance system refers to the relation between anterior teeth being in contact during eccentric movements of the mandible.4,5 The application of force from the muscles through occlusal contacts results in a load that could
ß W. S. Maney & Son Ltd 2015
134
DOI 10.1179/2151090314Y.0000000005
CRANIOH: The Journal of Craniomandibular & Sleep Practice
2015
VOL.
33
NO.
2
Sierpinska et al.
produce damage to tissues.4 The purpose of guidelines of good occlusal practice is to reduce the risk of damage occurring to the interrelated tissues of the masticatory system, and increase the chances of a healthy function.6 Although occlusal relationships such as overbite, non-working side interferences and a discrepancy between the intercuspal position and the retruded contact position have often been considered as contributing factors to temporomandibular dysfunction, there is no consistency among even those studies that support such an occlusal factor.7,8 However, in the relationship between all the elements of the masticatory system, it appears to be clear that there is not one statistically confirmed theory explaining how they relate to each other.9–11 The aim of this investigation was to assess the relationship between the morphology of the dental arches, the masticatory muscle activities, and the occlusal parameters in this group of young adults with full natural dentition and normal-appearing occlusion.
Figure 1 Maxillary plaster cast width measured between 17 and 27.
5. any complains concerning pain in any region of the masticatory system; 6. prosthetic treatment before recruitment to the study.
Ethical approval
Material Two hundred healthy, fully dentate Caucasian participants (F5113, M587) with Angle’s class I occlusion, 18–21 years of age (mean: 1961 years) were included in this study. The data were collected in the Department of Prosthodontics at the Medical University of Białystok, Poland, and the protocol conformed to the criteria of The Helsinki Declaration, ICH Guideline for Good Clinical Practice.12 All of the subjects participated in the study voluntary. They were recruited from the high schools in Bialystok, Poland, and qualified for the study only if they had no past contact with either of the investigators or instruments involved in the investigation.
Inclusion criteria Inclusion in the study required participants to satisfy the following criteria: 1. class I molar and canine relations; 2. full natural dentition with well-aligned arches; 3. overbite and overjet within normal range (normal ranges: 3.260.7; 3.260.4); 4. proper occlusal vertical dimension with wellrelated vertical, transverse, and antero-posterior relationships; 5. normal growth and good health.
Exclusion criteria Subjects were excluded from the study when they demonstrated: 1. 2. 3. 4.
Dental arches morphology and functional parameters
previous orthodontic treatment; edentulous spaces and extensive fillings; history of trauma; significant cuspal wear;
This protocol was approved by the Ethical Committee of Jagiellonian University, Poland, with an approval number of KBET/89B/2009. Informed consent was obtained from each participant at the beginning of the study before confirmation of their eligibility for the study. The participants were able to withdraw from the study at any time and for any reason without prejudice.
Methods All of the participants were clinically examined with assessment of overbite, overjet, the range of maximal opening, the range of lateral movements, and protrusive movement. The alginate impressions of the maxilla and mandible were taken, and plaster casts were prepared. Subsequently, maxillary and mandibular plaster casts were measured. The measurements were as follows: the length and width of dental arches between canines, between premolars, and between molars separately for the maxilla and the mandible (Figs. 1–3). The same investigator, familiar with the methods used, performed all the clinical data and laboratory measurements. Electromyographic examination of the muscle activity levels of four pairs of the masticatory muscles was performed. The anterior temporalis, the superficial masseter, the anterior belly of the digastric, and the sternocleidomastoid muscles, were all recorded simultaneously with the BioEMG (BioResearch, Inc., Milwaukee, WI, USA), which was synchronized with the T-Scan II (Tekscan, Inc., South Boston, MA,
CRANIOH: The Journal of Craniomandibular & Sleep Practice
2015
VOL .
33
NO .
2
135
Sierpinska et al.
Dental arches morphology and functional parameters
Figure 2 Maxillary plaster cast length measured between 17 and 27.
USA). T-Scan II allowed assessment of the time of occlusion and the time of disclusion as the parameters describing occlusion. (The data recording rate for TScan was 100 frames/second). The sample rate for each channel of EMG data was 1000 samples/second. The filtering of the EMG data was to a bandwidth from 30 to 500 Hz. The T-Scan II/BioEMG software continuously time-stamps both data streams to synchronize them. This allows for simultaneous acquisition of occlusal function and the muscle activity that produces occlusal function.13 For each subject, the maximal clench in centric occlusion and lateral excursive movements were recorded three times, with 1 minute of rest between recordings. The same, well-qualified and trained investigator made all of the EMG/T-Scan registrations. A statistical analysis of all of the studied attributes was carried out. In the case of quantitative attributes, average and dispersion measures were used, i.e. arithmetic mean and standard deviation. A Student’s two-tailed t-test was used to determine if the differences in the parameters analyzed between the male and female groups were significant. The strength of relationships between pairs of measurable parameters was determined using Pearson’s correlation coefficient, and
Figure 3 The length of the model measured from the central incisors contact point perpendicular to the distance between 16 and 26 (B) or 17 and 27 (A).
its significance was assessed also using Student’s t-test to evaluate the correlation coefficient. In order to evaluate intra investigator error, 10 maxillary and 10 mandibular plaster casts were remeasured after four weeks. Their mean differences were evaluated using Student’s paired t-test and Pearson’s correlation coefficient to determine significance. The intra-subject variability was assessed by repeated EMG/occlusal analyses of 10 randomly chosen persons. Two different investigators performed three independent measurements on each of 10 persons. The measurements were performed every other day according to the same protocol and data analysis. Accuracy and precision were assessed by computing the intra-class correlation coefficient and the Student’s paired t-test. Differences and relationships were considered to be statistically significant at P,0.05.
Results Clinical measurements regarding overbite, overjet, maximal opening, the range of lateral movements and the range of protrusive movement revealed normal values of the parameters investigated (Table 1). However, significant differences between female and
Table 1 Clinical examination results in study, female and male groups. Means and SD are presented Study group (n5200)
Overbite (mm) Overjet (mm) Maximal opening (mm) Lateral movement left (mm) Lateral movement right (mm) Protrusive movement (mm)
Female (n5113)
Male (n587)
Mean
6SD
Mean
6SD
Mean
6SD
3.11 2.30 51.16 9.60 9.98 6.43
1.82 1.54 9.24 2.74 2.70 2.38
3.06 2.41 49.09* 9.42 9.75 5.79*
1.62 1.34 9.50 2.74 2.60 2.17
3.17 2.19 53.31* 9.79 10.22 7.12*
2.02 1.73 8.49 2.74 2.80 2.42
Note: *Significant difference between female and male groups (two-paired Student’s t-test, P#0.05).
136
CRANIOH: The Journal of Craniomandibular & Sleep Practice
2015
VOL .
33
NO .
2
Sierpinska et al.
Dental arches morphology and functional parameters
Table 2 Maxillary and mandibular plaster casts analyses in study, females and males groups. Means and SD are presented
Maxilla
Mandible
Study group (n5200)
Female (113)
Parameter
Mean
6SD
Mean
13–23 14–24 15–25 16–26 17–27 Length Length A B 33–43 34–44 35–45 36–46 37–47 Length Length A B
33.80 36.47 41.42 47.18 52.91 101.02 121.38 29.65 15.57 25.71 30.61 36.11 42.23 47.64 91.81 112.94 25.46 10.87
2.38 2.31 3.21 3.28 3.07 5.43 6.03 2.63 2.13 1.85 2.01 2.95 2.83 3.23 5.08 5.75 2.46 2.03
33.34* 35.96* 40.69* 46.22* 51.97* 99.60* 119.65* 29.21* 15.29 25.54 30.19* 35.42* 41.44* 46.83* 90.12* 111.43* 25.12* 10.55*
between 16 and 26 between 17 and 27
between 36 and 46 between 37 and 47
Male (87) 6SD 2.19 2.08 2.98 2.57 2.21 5.63 5.67 2.62 1.63 1.86 1.70 2.59 2.45 2.57 4.79 5.32 2.42 1.78
Mean
6SD
34.27* 36.96* 42.19* 48.18* 53.89* 102.47* 123.18* 30.10* 15.84 25.88 31.03* 36.84* 43.07* 48.47* 93.59* 114.51* 25.83* 11.19*
2.47 2.42 3.28 3.64 3.51 4.82 5.89 2.58 2.51 1.84 2.20 3.13 2.98 3.63 4.78 5.79 2.46 2.21
Note: A: length of the arch measured from the point between central incisors contact point and t. B: length of the arch measured from the point between central incisors contact point. *Significant difference between female and male groups (two-paired Student’s t-test, P#0.05).
male groups were observed for the ranges of maximal opening and protrusive movement. The male group demonstrated larger values of these two parameters listed above. Maxillary and mandibular plaster cast analyses demonstrated normal ranges of width and length between points measured. Higher values were obtained for males for most of the parameters measured, and they were statistically significant compared to females (Table 2). Analysis of the masticatory muscle activity levels for the masseter, anterior temporalis, sternocleidomastoid and digastric muscles in centric occlusion and during lateral movements for female and male groups were presented in Tables 3 and 4. Significant differences were observed between male and female groups for masseter and sternocleidomastoid muscles
in centric occlusion. Regarding lateral movements, the statistical significance between groups analyzed was noted only for masseter activity levels, both for the right and left movements. Analyzing T-Scan occlusal timing parameters, the normal range of values was noted both in centric occlusion (mean50.17 seconds) and lateral movements (mean50.24 seconds). Statistical difference was not observed between genders (Table 5). Relationships between parameters obtained in clinical measurements, plaster casts measurements, and functional analysis revealed weak significant positive correlations between overbite and the right and left masseter activities in centric occlusion (right Mm, R50.153, P#0.05; left Mm, R50.191, P#0.05) (Figs. 4 and 5). Also, the range of protrusive movement revealed a weak positive correlation with masseter activities in centric occlusion (R50.194,
Table 3 Muscular activities in central occlusion during maximal clench in study, females and males groups. Means and SD are presented Study group (n5200)
TA-R (mV) TA-L (mV) MM-R (mV) MM-L(mV) SCM-R (mV) SCM-L (mV) DA-R (mV) DA-L (mV)
Female (113)
Male (87)
Mean
6SD
Mean
6SD
Mean
6SD
72.14 73.91 115.14 104.65 9.92 9.92 17.22 15.36
38.75 42.29 59.38 54.60 7.78 6.95 8.35 7.48
72.48 71.76 106.09* 93.64* 8.62* 8.93* 17.17 15.07
40.29 39.86 57.76 48.36 5.05 5.41 8.71 6.73
71.78 76.18 124.67* 116.24* 11.29* 10.97* 17.27 15.66
37.26 44.80 59.88 58.53 9.72 8.16 8.00 8.23
Note: TA: temporalis anterior; MM: masseter; SCM: sternocleidomastoid; DA: digastric; R: right; L: left. *Significant difference between female and male groups (two-paired Student’s t-test, P#0.05).
CRANIOH: The Journal of Craniomandibular & Sleep Practice
2015
VOL .
33
NO .
2
137
Sierpinska et al.
Dental arches morphology and functional parameters
Table 4 Muscular activities during lateral movements in study, females and males groups. Means and SD are presented Study group (n5200)
TA-R (RM) TA-L (RM) MM-R (RM) MM-L(RM) SCM-R(RM) SCM-L(RM) DA-R (RM) DA-L (RM) TA-R (LM) TA-L (LM) MM-R (LM) MM-L(LM) SCM-R(LM) SCM-L (LM) DA-R (LM) DA-L (LM)
Female (113)
Male (87)
Mean
6SD
Man
6SD
Mean
6SD
72.32 67.41 107.04 98.70 8.42 7.99 14.37 11.64 63.74 71.76 103.58 99.76 8.26 8.51 14.11 11.76
35.26 36.75 57.45 50.37 6.97 5.79 8.35 4.88 33.95 36.83 55.67 54.32 7.75 7.37 9.29 5.96
72.81 66.21 89.86* 89.96* 7.94 7.77 14.87 12.03 66.09 69.74 95.10* 87.53* 7.97 8.17 14.37 11.97
33.97 34.06 57.27 48.88 6.18 5.46 9.83 4.81 32.99 35.43 51.95 46.68 6.42 5.76 11.09 6.48
71.79 68.67 114.59* 107.89* 8.92 8.21 13.84 11.24 61.25 73.89 112.51* 112.63* 8.55 8.87 13.83 11.53
36.74 39.53 56.97 50.54 7.72 6.13 6.45 4,96 34.94 38.33 58.29 58.89 8.95 8.76 6.98 5.40
Note: TA, temporalis anterior; MM: masseter; SCM: sternocleidomastoid; DA: digastric; RM: lateral movement into right; LM: lateral movement into left. *Significant difference between female and male groups (two-paired Student’s t-test, P#0.05).
P#0.05; R50.201, P#0.05), (Figs. 6 and 7). When analyzing one hundred models, a statistically significant weak correlation was observed between the length of the dental arch, measured between the maxillary first molars (16–26), and the anterior temporalis activity levels in centric occlusion (R520.255, P#0.05; R520.225, P#0.05) (Figs. 8 and 9). However, when the number of the models measured increased to 200, this correlation was no longer significant.
Discussion It is obvious that morphology affects function in the human body. The male body construction in the Caucasian population is customarily stronger, and the morphologies of all of the elements are bigger in size, the dental arch length, and width are also larger in males compared to females.14,15 It was confirmed without any doubt in the study presented. Clinical characteristics of functional analyses revealed the normal range of values for overbite, overjet, maximal opening, the range of lateral movements, and protrusion. Moreover, they were recorded from subjects without any complaints of the temporomandibular joint. This confirms that the participants
followed the inclusion and exclusion criteria for this study. And, it is interesting to note that the values of the maximal opening and protrusive movement ranges were significantly larger in males. The values obtained from plaster model measurements were comparable with previously published normal range of values for Angle’s class I subjects in this age group. However, some authors mentioned that during longitudinal observation, the dental arch width of young adults was slightly narrowed from adolescence dependent on mandibular first molars’ mesiolingual rotation and maxillary molars’ upright displacement during late occlusal development, but they also indicated the wide variability of the changes.16 From this point of view, data that did not reveal such changes also appeared to be clear.17 Morphologies of teeth and subsequently dental arches form interocclusal contacts. It is well known that muscular activities are influenced by the extent of occlusal contacts;3 however, it was also confirmed that occlusal stability would be more important in muscular function.18–20 It is controversial whether the extent of occlusal contacts are more important in neuromuscular coordination or if only the presence of teeth and dental roots with their receptors
Table 5 Occlusal analysis in study, females and males groups. Means and SD are presented
Occlusion time Disclusion time left Disclusion time right
138
Study group (n5200)
Female (n5113)
Mean
6SD
Mean
6SD
Mean
6SD
0.17 0.24 0.24
0.07 0.07 0.08
0.16 0.24 0.25
0.07 0.07 0.08
0.17 0.23 0.23
0.07 0.07 0.08
CRANIOH: The Journal of Craniomandibular & Sleep Practice
2015
VOL .
33
NO .
2
Male (n587)
Sierpinska et al.
Dental arches morphology and functional parameters
Figure 4 Regression analysis between overbite and muscular activity levels of right masseter in central occlusion.
Figure 6 Regression analysis between the range of protrusion and muscular activity levels of right masseter in central occlusion.
localized in periodontal membranes and supporting tissues play the key role.2 Several investigators reported a strict relationship between dentofacial morphology and mastication (related to electromyography of masticatory muscles, fiber direction and the cross sectional area of the muscles).21–23 However, jaw-closing and jaw-opening muscles appeared to be similarly valid in this correlation.24 Muscles analyzed in the research were anteriores temporalis, masseters, digastric, and sternocleidomastoids. Masseters are active during closing and may assist in protrusion of the mandible. Anteriores temporales may act as synergists with masseters in clench. Digastric muscles are active during various phases of jaw opening, whereas the sternocleidomastoid muscle often co-contracts with jaw clenching.1 Symmetry and synergy appear to be the most important in the proper muscular function during open/close and protrusive movements. When any parafunctional activities (clenching, grinding, different
intraoral habits) occur, the muscular system may respond by prolongation of muscular activity and derangement in its function.5,19 Muscular hyperfunction causes an increased mechanical loading of the jaws.15 In any case, it may lead to temporomandibular joint dysfunction.5 It is very interesting to note that anterior overbite has some effect on muscular activity of masseters in maximal intercuspation. A similar finding was published in Japan, when the relationship between the dentofacial morphology and the function of masticatory muscles were analyzed.24 In contrast, some investigations did not report such a finding.25 The disagreement between both studies could have its source in the different methods used for muscular activities measurements.24 A longitudinal study conducted in Brazil revealed that during the seventh year period of an evaluation, the overbite increased in the
Figure 5 Regression analysis between overbite and muscular activity levels of left masseter in central occlusion.
Figure 7 Regression analysis between the range of protrusion and muscular activity levels of left masseter in central occlusion.
CRANIOH: The Journal of Craniomandibular & Sleep Practice
2015
VOL .
33
NO .
2
139
Sierpinska et al.
140
Dental arches morphology and functional parameters
Figure 8 Regression analysis between length of maxillary arch between 16 and 26 and muscular activity levels of temporalis anterior right in central occlusion.
Figure 9 Regression analysis between length of maxillary arch between 16 and 26 and muscular activity levels of temporalis anterior left in central occlusion.
normal occlusion of adults.17 However, the reason for the finding was not explained. It would be reasonable to hypothesize that long-term high muscular activities of elevating muscles (i.e. masseters) might lead to an increased overbite. The rationalization of this finding would project that the alveolodental ligaments could allow the tooth to be pressed into alveoli, altering relations between front teeth. As a matter of fact, the overbite and overjet relate to the anterior guidance system, which can be changed through orthodontic, prosthetic and sometimes also conservative treatment.5 However, these correlations are not clear and well documented with regard to muscular activities. In the light of the study presented above, such a correlation could exist, but it demands future, more detailed investigation. The data presented demonstrated the significant correlation between masseter activity in clench and the range of protrusive movement. It is possible to explain this finding since the masseters cooperate with lateral pterygoids during contraction in protrusive movement with the teeth in very light occlusion.1,5 The findings of the investigation did not indicate the relationship between morphology of dental arches, muscular activities and occlusal parameters, even if fewer numbers of the models analyzed could suggest that such a relation could exist. The authors’ method of investigation was focused on plaster model analysis. Some other investigations concerning the problem mentioned above related to the morphological analyses were performed on lateral cephalograms. They found a significant relationship between dental arch width and facial vertical morphology.15 However, studies involving the effect of the bite force on the arch width did not indicate any relationship.26 On the other hand, there are some contrary opinions that emphasize
a significant relationship between mandibular length and jaw closing muscles.27 Although the null hypothesis that the morphology of dental arches could affect masticatory muscle activities was rejected, some limitations of the study require discussion. Even though the protocol of clinical investigation and plaster cast analysis appears to be clear and common, perhaps more detailed measurements concerning not the only morphology of dental arches, but also their occlusal characteristics should be undertaken. Functional analysis made with T-Scan II/ BioEMG could influence the subject’s behaving during the investigation. One previous study questioned the thickness of the T-Scan occlusal sensor, claiming that it may affect the mechanics of occlusion and lead to invalid tooth contact data.28 However, in that study, the sensor was cut in half and placed only on one side of the arch, and as a consequence, they did not obtain a balanced response from the muscles. In the light of the data presented in this and other studies, their finding appears to be invalid. The findings of this investigation indicate that systemic, longitudinal analyses of morphology of occlusion and muscular response in normal subjects are required.
CRANIOH: The Journal of Craniomandibular & Sleep Practice
2015
Conclusions 1. Measurements of the maxillary and mandibular dental arches revealed statistical differences between the females and males in this large, youthful, normal group. 2. Muscular activities of masseters in clench and during lateral movements were sufficiently different between the females and males of the group. 3. The muscular activities of the masseters in centric occlusion exhibited a weak positive correlation between the amount of overbite and the range of protrusive movement. VOL .
33
NO .
2
Sierpinska et al.
4. The morphology of the dental arches has limited influence on masticatory muscle activities.
11
Disclaimer Statements Contributors Special thanks to John Radke for his guidance in the preparation of this manuscript.
12
13
Funding Polish Ministry of Education and Research. Conflicts of interest All authors contributed to the work and the final version of the manuscript has been seen and approved by all co-authors. There is no conflict of interest between all the co-authors. This research was financially supported by a grant from the Polish Ministry of Education and Research (no. 40358139). Ethics approval The protocol conformed to the criteria of The Helsinki Declaration, ICH Guideline for Good Clinical Practice This protocol was approved by the Ethical Committee of Jagiellonian University, Poland, with an approval number of KBET/89B/2009.
14
15
16
17
18
19
References 1 Ash MM, Nelson SJ. Dental anatomy, physiology and occlusion. Philadelphia, PA: Elsevier; 2003. p. 430, 437–9. 2 Tartaglia GM, Testori T, Pallavera A, Marelli B, Sforza C. Electromyographic analysis of masticatory and neck muscles in subjects with natural dentition, teeth-supported and implantsupported prostheses. Clin Oral Implants Res. 2008;19:1081–8. 3 Bakke M. Mandibular elevator muscles: physiology, action, and effect of dental occlusion. Scand J Dent Res. 1993;101: 314–31. 4 Davies S, Gray RM. What is occlusion? Br Dent J. 2001;191:235–45. 5 Okeson JP. Management of temporomandibular disorders and occlusion. 5th ed. St Louis, MO: Mosby; 2003. p. 109–26. 6 Zarb G. The interface of occlusion revisited. Int J Prosthodont. 2005;18:270–1. 7 McCoy G. Occlusion confusion. Gen Dent. 2013;61:69–75. 8 Tu¨rp JC, Schindler H. The dental occlusion as a suspected cause for TMDs: epidemiological and etiological considerations. J Oral Rehabil. 2012;39:502–12. 9 Farella M, Bakke M, Michelotti A, Rapuano A, Martina R. Masseter thickness, endurance and exercise-induced pain in subjects with different vertical craniofacial morphology. Eur J Oral Sci. 2003;111:183–8. 10 Garcia-Morales P, Buschang PH, Throckmorton GS, English JD. Maximum bite force, muscle efficiency and mechanical
20
21 22 23
24
25 26
27
28
Dental arches morphology and functional parameters
advantage in children with vertical growth patterns. Eur J Orthod. 2003;25:265–72. Ferrario VF, Tartaglia GM, Galletta A, Grassi GP, Sforza C. The influence of occlusion on jaw and neck muscle activity: a surface EMG study in healthy young adults. J Oral Rehabil. 2006;33:341–8. Helsinki Declaration, ICH guideline for good clinical practice. In: Proceedings of the 59th WMA General Assembly: 1–8; October 2008; Seoul, Korea. WMA: Ferney-Voltaire, France. Kerstein RB. Combining technologies: a computerized occlusal analysis system synchronized with a computerized electromyography system. J Craniomandib Pract. 2004;22:96–109. Eroz UB, Ceylan I, Aydemir S. An investigation of mandibular morphology in subjects with different vertical facial growth patterns. Aust Orthod J. 2000;16:16–22. Forster CM, Sunga E, Chung CH. Relationship between dental arch width and vertical facial morphology in untreated adults. Eur J Orthod. 2008;30:288–94. Heikinheimo K, Nystro¨m M, Heikinheimo T, Pirttiniemi P, Pirinen S. Dental arch width, overbite, and overjet in a Finnish population with normal occlusion between the ages of 7 and 32 years. Eur J Orthod. 2012;34:418–26. Tibana RH, Palagi LM, Miguel JA. Changes in dental arch measurements of young adults with normal occlusion- a longitudinal study. Angle Orthod. 2004;74:618–23. Wang XR, Zhang Y, Xing N, Xu YF, Wang MQ. Stable tooth contacts in intercuspal occlusion makes for utilities of the jaw elevators during maximal voluntary clenching. J Oral Rehabil. 2013;40:319–28. Kerstein RB, Radke J. Masseter and temporalis excursive hyperactivity decreased by measured anterior guidance development. J Craniomandib Pract. 2012;30:243–54. Saifuddin M, Miyamoto K, Ueda HM, Shikata N, Tanne K. A quantitative electromyographic analysis of masticatory muscle activity in usual daily life. Oral Dis. 2001;7:94–100. Ingervall B, Helkimo E. Masticatory muscle force and facial morphology in man. Arch Oral Biol. 1978;23:203–6. Proctor AD, de Vicenzo JP. Masseter muscle position relative to dentofacial form. Angle Orthodontist. 1970,40:37–45. Weijs WA, Hillen B. Correlations between the cross-sectional area of the jaw muscles and craniofacial size and shape. Am J Phys Anthropol. 1986;70:423–31. Watanabe K, Watanabe M. Activity of jaw-opening and jawclosing muscles and their influence on dentofacial morphological features in normal adults. J Oral Rehabil. 2001;28:873–9. Ringqvist M. Isometric bite force and its relation to dimensions of the facial skeleton. Acta Odontologica Scand. 1973;31:35–42. Thongudomporn U, Chongsuvivatwong V, Geater AF. The effect of maximum bite force on alveolar bone morphology. Orthod Craniofac Res. 2009;12:1–8. Watanabe K. The relationship between dentofacial morphology and the isometric jaw-opening and closing muscle function as evaluated by electromyography. J Oral Rehabil. 2000;27: 639–45. Forrester SE, Presswood RG, Toy AC, Pain MT. Occlusal measurement method can affect SEMG activity during occlusion. J Oral Rehabil. 2011;38:655–60.
CRANIOH: The Journal of Craniomandibular & Sleep Practice
2015
VOL .
33
NO .
2
141
Effect of the dental arches morphology on the masticatory muscles activities in normal occlusion young adults Teresa Sierpinska1, Piotr Jacunski1, Joanna Kuc2, Maria Golebiewska2, Aneta Wieczorek3, Stanislaw Majewski3 1
Department of Dental Technique, Medical University of Bialystok, Poland, 2Department of Prosthetic Dentistry, Medical University of Bialystok, Poland, 3Department of Prosthetic Dentistry, Collegium Medicum of Jagiellonian University, Cracow, Poland
Objectives: The aim of this study was to assess the relationship between the morphology of dental arches and the activity of the masticatory muscles activities in healthy volunteers with full natural dentition. Methods: Two-hundred youthful Class I volunteers (113 females, 87 males) were clinically investigated. Alginate impressions of dental arches were taken, and plaster casts were prepared and measured. EMG data from eight masticatory muscles was recorded to assess their activities in central occlusion, lateral and protrusive movements. Results: Clinical measurements and plaster casts analyses confirmed normal values of parameters investigated. Most of the arch measurements were significantly larger in the males than in the females. Weak positive correlations were found between overbite and masseter activity in centric occlusion (the right Mm R50.151, P#0.05; the left Mm R50.191, P#0.05). Also, the range of protrusive movement positively correlated with masseter activities in central occlusion (the right Mm R50.194, P#0.05; the left R50.201, P#0.05). Conclusions: The null hypothesis that morphology of dental arches does not affect the masticatory muscles’ activities was rejected. The findings of this investigation indicate that systemic, longitudinal analyses of morphology of occlusion and muscular response, even in normal subjects, are needed. Keywords: Dental arches morphology, Overbite, Overjet, Masticatory muscle activity, Occlusal parameters
Introduction The study of dental anatomy, physiology and occlusion provides one of the basic components of the skills needed to practice all phases of dentistry. For some clinicians, the general principle that becomes operant is ‘‘form follows function.’’ It reflects a concept of interrelating the shape or attributes of something with its function. The form of the teeth is consistent with the function they are to perform and with their position and arrangement in the structures involved in oral motor behavior, especially mastication.1 From the occlusal surface point of view teeth are positioned on the maxilla and the mandible in such a way as to produce a curved arch. Both dental arches contact
Correspondence to: T. Sierpinska, Department of Dental Technique, Medical University of Bialystok, Washington Str. 13, 15-276 Bialystok, Poland. Email: [email protected]
each other in occlusion. The coordination of occlusal contacts, jaw motion, and tongue movement during mastication requires a very intricate control system involving a number of guiding influences from the teeth, their supporting structures, the temporomandibular joints, the masticatory muscles, and the higher centers in the central nervous system.2,3 The dynamic occlusion refers to the occlusal contacts that are made while the mandible is moving, relative to the maxilla.4 The mandible is moved by the muscles of mastication, and the pathways along which it moves are determined not only by these muscles but also by two guidance systems. The posterior guidance system is provided by temporomandibular joints. The anterior guidance system refers to the relation between anterior teeth being in contact during eccentric movements of the mandible.4,5 The application of force from the muscles through occlusal contacts results in a load that could
ß W. S. Maney & Son Ltd 2015
134
DOI 10.1179/2151090314Y.0000000005
CRANIOH: The Journal of Craniomandibular & Sleep Practice
2015
VOL.
33
NO.
2
Sierpinska et al.
produce damage to tissues.4 The purpose of guidelines of good occlusal practice is to reduce the risk of damage occurring to the interrelated tissues of the masticatory system, and increase the chances of a healthy function.6 Although occlusal relationships such as overbite, non-working side interferences and a discrepancy between the intercuspal position and the retruded contact position have often been considered as contributing factors to temporomandibular dysfunction, there is no consistency among even those studies that support such an occlusal factor.7,8 However, in the relationship between all the elements of the masticatory system, it appears to be clear that there is not one statistically confirmed theory explaining how they relate to each other.9–11 The aim of this investigation was to assess the relationship between the morphology of the dental arches, the masticatory muscle activities, and the occlusal parameters in this group of young adults with full natural dentition and normal-appearing occlusion.
Figure 1 Maxillary plaster cast width measured between 17 and 27.
5. any complains concerning pain in any region of the masticatory system; 6. prosthetic treatment before recruitment to the study.
Ethical approval
Material Two hundred healthy, fully dentate Caucasian participants (F5113, M587) with Angle’s class I occlusion, 18–21 years of age (mean: 1961 years) were included in this study. The data were collected in the Department of Prosthodontics at the Medical University of Białystok, Poland, and the protocol conformed to the criteria of The Helsinki Declaration, ICH Guideline for Good Clinical Practice.12 All of the subjects participated in the study voluntary. They were recruited from the high schools in Bialystok, Poland, and qualified for the study only if they had no past contact with either of the investigators or instruments involved in the investigation.
Inclusion criteria Inclusion in the study required participants to satisfy the following criteria: 1. class I molar and canine relations; 2. full natural dentition with well-aligned arches; 3. overbite and overjet within normal range (normal ranges: 3.260.7; 3.260.4); 4. proper occlusal vertical dimension with wellrelated vertical, transverse, and antero-posterior relationships; 5. normal growth and good health.
Exclusion criteria Subjects were excluded from the study when they demonstrated: 1. 2. 3. 4.
Dental arches morphology and functional parameters
previous orthodontic treatment; edentulous spaces and extensive fillings; history of trauma; significant cuspal wear;
This protocol was approved by the Ethical Committee of Jagiellonian University, Poland, with an approval number of KBET/89B/2009. Informed consent was obtained from each participant at the beginning of the study before confirmation of their eligibility for the study. The participants were able to withdraw from the study at any time and for any reason without prejudice.
Methods All of the participants were clinically examined with assessment of overbite, overjet, the range of maximal opening, the range of lateral movements, and protrusive movement. The alginate impressions of the maxilla and mandible were taken, and plaster casts were prepared. Subsequently, maxillary and mandibular plaster casts were measured. The measurements were as follows: the length and width of dental arches between canines, between premolars, and between molars separately for the maxilla and the mandible (Figs. 1–3). The same investigator, familiar with the methods used, performed all the clinical data and laboratory measurements. Electromyographic examination of the muscle activity levels of four pairs of the masticatory muscles was performed. The anterior temporalis, the superficial masseter, the anterior belly of the digastric, and the sternocleidomastoid muscles, were all recorded simultaneously with the BioEMG (BioResearch, Inc., Milwaukee, WI, USA), which was synchronized with the T-Scan II (Tekscan, Inc., South Boston, MA,
CRANIOH: The Journal of Craniomandibular & Sleep Practice
2015
VOL .
33
NO .
2
135
Sierpinska et al.
Dental arches morphology and functional parameters
Figure 2 Maxillary plaster cast length measured between 17 and 27.
USA). T-Scan II allowed assessment of the time of occlusion and the time of disclusion as the parameters describing occlusion. (The data recording rate for TScan was 100 frames/second). The sample rate for each channel of EMG data was 1000 samples/second. The filtering of the EMG data was to a bandwidth from 30 to 500 Hz. The T-Scan II/BioEMG software continuously time-stamps both data streams to synchronize them. This allows for simultaneous acquisition of occlusal function and the muscle activity that produces occlusal function.13 For each subject, the maximal clench in centric occlusion and lateral excursive movements were recorded three times, with 1 minute of rest between recordings. The same, well-qualified and trained investigator made all of the EMG/T-Scan registrations. A statistical analysis of all of the studied attributes was carried out. In the case of quantitative attributes, average and dispersion measures were used, i.e. arithmetic mean and standard deviation. A Student’s two-tailed t-test was used to determine if the differences in the parameters analyzed between the male and female groups were significant. The strength of relationships between pairs of measurable parameters was determined using Pearson’s correlation coefficient, and
Figure 3 The length of the model measured from the central incisors contact point perpendicular to the distance between 16 and 26 (B) or 17 and 27 (A).
its significance was assessed also using Student’s t-test to evaluate the correlation coefficient. In order to evaluate intra investigator error, 10 maxillary and 10 mandibular plaster casts were remeasured after four weeks. Their mean differences were evaluated using Student’s paired t-test and Pearson’s correlation coefficient to determine significance. The intra-subject variability was assessed by repeated EMG/occlusal analyses of 10 randomly chosen persons. Two different investigators performed three independent measurements on each of 10 persons. The measurements were performed every other day according to the same protocol and data analysis. Accuracy and precision were assessed by computing the intra-class correlation coefficient and the Student’s paired t-test. Differences and relationships were considered to be statistically significant at P,0.05.
Results Clinical measurements regarding overbite, overjet, maximal opening, the range of lateral movements and the range of protrusive movement revealed normal values of the parameters investigated (Table 1). However, significant differences between female and
Table 1 Clinical examination results in study, female and male groups. Means and SD are presented Study group (n5200)
Overbite (mm) Overjet (mm) Maximal opening (mm) Lateral movement left (mm) Lateral movement right (mm) Protrusive movement (mm)
Female (n5113)
Male (n587)
Mean
6SD
Mean
6SD
Mean
6SD
3.11 2.30 51.16 9.60 9.98 6.43
1.82 1.54 9.24 2.74 2.70 2.38
3.06 2.41 49.09* 9.42 9.75 5.79*
1.62 1.34 9.50 2.74 2.60 2.17
3.17 2.19 53.31* 9.79 10.22 7.12*
2.02 1.73 8.49 2.74 2.80 2.42
Note: *Significant difference between female and male groups (two-paired Student’s t-test, P#0.05).
136
CRANIOH: The Journal of Craniomandibular & Sleep Practice
2015
VOL .
33
NO .
2
Sierpinska et al.
Dental arches morphology and functional parameters
Table 2 Maxillary and mandibular plaster casts analyses in study, females and males groups. Means and SD are presented
Maxilla
Mandible
Study group (n5200)
Female (113)
Parameter
Mean
6SD
Mean
13–23 14–24 15–25 16–26 17–27 Length Length A B 33–43 34–44 35–45 36–46 37–47 Length Length A B
33.80 36.47 41.42 47.18 52.91 101.02 121.38 29.65 15.57 25.71 30.61 36.11 42.23 47.64 91.81 112.94 25.46 10.87
2.38 2.31 3.21 3.28 3.07 5.43 6.03 2.63 2.13 1.85 2.01 2.95 2.83 3.23 5.08 5.75 2.46 2.03
33.34* 35.96* 40.69* 46.22* 51.97* 99.60* 119.65* 29.21* 15.29 25.54 30.19* 35.42* 41.44* 46.83* 90.12* 111.43* 25.12* 10.55*
between 16 and 26 between 17 and 27
between 36 and 46 between 37 and 47
Male (87) 6SD 2.19 2.08 2.98 2.57 2.21 5.63 5.67 2.62 1.63 1.86 1.70 2.59 2.45 2.57 4.79 5.32 2.42 1.78
Mean
6SD
34.27* 36.96* 42.19* 48.18* 53.89* 102.47* 123.18* 30.10* 15.84 25.88 31.03* 36.84* 43.07* 48.47* 93.59* 114.51* 25.83* 11.19*
2.47 2.42 3.28 3.64 3.51 4.82 5.89 2.58 2.51 1.84 2.20 3.13 2.98 3.63 4.78 5.79 2.46 2.21
Note: A: length of the arch measured from the point between central incisors contact point and t. B: length of the arch measured from the point between central incisors contact point. *Significant difference between female and male groups (two-paired Student’s t-test, P#0.05).
male groups were observed for the ranges of maximal opening and protrusive movement. The male group demonstrated larger values of these two parameters listed above. Maxillary and mandibular plaster cast analyses demonstrated normal ranges of width and length between points measured. Higher values were obtained for males for most of the parameters measured, and they were statistically significant compared to females (Table 2). Analysis of the masticatory muscle activity levels for the masseter, anterior temporalis, sternocleidomastoid and digastric muscles in centric occlusion and during lateral movements for female and male groups were presented in Tables 3 and 4. Significant differences were observed between male and female groups for masseter and sternocleidomastoid muscles
in centric occlusion. Regarding lateral movements, the statistical significance between groups analyzed was noted only for masseter activity levels, both for the right and left movements. Analyzing T-Scan occlusal timing parameters, the normal range of values was noted both in centric occlusion (mean50.17 seconds) and lateral movements (mean50.24 seconds). Statistical difference was not observed between genders (Table 5). Relationships between parameters obtained in clinical measurements, plaster casts measurements, and functional analysis revealed weak significant positive correlations between overbite and the right and left masseter activities in centric occlusion (right Mm, R50.153, P#0.05; left Mm, R50.191, P#0.05) (Figs. 4 and 5). Also, the range of protrusive movement revealed a weak positive correlation with masseter activities in centric occlusion (R50.194,
Table 3 Muscular activities in central occlusion during maximal clench in study, females and males groups. Means and SD are presented Study group (n5200)
TA-R (mV) TA-L (mV) MM-R (mV) MM-L(mV) SCM-R (mV) SCM-L (mV) DA-R (mV) DA-L (mV)
Female (113)
Male (87)
Mean
6SD
Mean
6SD
Mean
6SD
72.14 73.91 115.14 104.65 9.92 9.92 17.22 15.36
38.75 42.29 59.38 54.60 7.78 6.95 8.35 7.48
72.48 71.76 106.09* 93.64* 8.62* 8.93* 17.17 15.07
40.29 39.86 57.76 48.36 5.05 5.41 8.71 6.73
71.78 76.18 124.67* 116.24* 11.29* 10.97* 17.27 15.66
37.26 44.80 59.88 58.53 9.72 8.16 8.00 8.23
Note: TA: temporalis anterior; MM: masseter; SCM: sternocleidomastoid; DA: digastric; R: right; L: left. *Significant difference between female and male groups (two-paired Student’s t-test, P#0.05).
CRANIOH: The Journal of Craniomandibular & Sleep Practice
2015
VOL .
33
NO .
2
137
Sierpinska et al.
Dental arches morphology and functional parameters
Table 4 Muscular activities during lateral movements in study, females and males groups. Means and SD are presented Study group (n5200)
TA-R (RM) TA-L (RM) MM-R (RM) MM-L(RM) SCM-R(RM) SCM-L(RM) DA-R (RM) DA-L (RM) TA-R (LM) TA-L (LM) MM-R (LM) MM-L(LM) SCM-R(LM) SCM-L (LM) DA-R (LM) DA-L (LM)
Female (113)
Male (87)
Mean
6SD
Man
6SD
Mean
6SD
72.32 67.41 107.04 98.70 8.42 7.99 14.37 11.64 63.74 71.76 103.58 99.76 8.26 8.51 14.11 11.76
35.26 36.75 57.45 50.37 6.97 5.79 8.35 4.88 33.95 36.83 55.67 54.32 7.75 7.37 9.29 5.96
72.81 66.21 89.86* 89.96* 7.94 7.77 14.87 12.03 66.09 69.74 95.10* 87.53* 7.97 8.17 14.37 11.97
33.97 34.06 57.27 48.88 6.18 5.46 9.83 4.81 32.99 35.43 51.95 46.68 6.42 5.76 11.09 6.48
71.79 68.67 114.59* 107.89* 8.92 8.21 13.84 11.24 61.25 73.89 112.51* 112.63* 8.55 8.87 13.83 11.53
36.74 39.53 56.97 50.54 7.72 6.13 6.45 4,96 34.94 38.33 58.29 58.89 8.95 8.76 6.98 5.40
Note: TA, temporalis anterior; MM: masseter; SCM: sternocleidomastoid; DA: digastric; RM: lateral movement into right; LM: lateral movement into left. *Significant difference between female and male groups (two-paired Student’s t-test, P#0.05).
P#0.05; R50.201, P#0.05), (Figs. 6 and 7). When analyzing one hundred models, a statistically significant weak correlation was observed between the length of the dental arch, measured between the maxillary first molars (16–26), and the anterior temporalis activity levels in centric occlusion (R520.255, P#0.05; R520.225, P#0.05) (Figs. 8 and 9). However, when the number of the models measured increased to 200, this correlation was no longer significant.
Discussion It is obvious that morphology affects function in the human body. The male body construction in the Caucasian population is customarily stronger, and the morphologies of all of the elements are bigger in size, the dental arch length, and width are also larger in males compared to females.14,15 It was confirmed without any doubt in the study presented. Clinical characteristics of functional analyses revealed the normal range of values for overbite, overjet, maximal opening, the range of lateral movements, and protrusion. Moreover, they were recorded from subjects without any complaints of the temporomandibular joint. This confirms that the participants
followed the inclusion and exclusion criteria for this study. And, it is interesting to note that the values of the maximal opening and protrusive movement ranges were significantly larger in males. The values obtained from plaster model measurements were comparable with previously published normal range of values for Angle’s class I subjects in this age group. However, some authors mentioned that during longitudinal observation, the dental arch width of young adults was slightly narrowed from adolescence dependent on mandibular first molars’ mesiolingual rotation and maxillary molars’ upright displacement during late occlusal development, but they also indicated the wide variability of the changes.16 From this point of view, data that did not reveal such changes also appeared to be clear.17 Morphologies of teeth and subsequently dental arches form interocclusal contacts. It is well known that muscular activities are influenced by the extent of occlusal contacts;3 however, it was also confirmed that occlusal stability would be more important in muscular function.18–20 It is controversial whether the extent of occlusal contacts are more important in neuromuscular coordination or if only the presence of teeth and dental roots with their receptors
Table 5 Occlusal analysis in study, females and males groups. Means and SD are presented
Occlusion time Disclusion time left Disclusion time right
138
Study group (n5200)
Female (n5113)
Mean
6SD
Mean
6SD
Mean
6SD
0.17 0.24 0.24
0.07 0.07 0.08
0.16 0.24 0.25
0.07 0.07 0.08
0.17 0.23 0.23
0.07 0.07 0.08
CRANIOH: The Journal of Craniomandibular & Sleep Practice
2015
VOL .
33
NO .
2
Male (n587)
Sierpinska et al.
Dental arches morphology and functional parameters
Figure 4 Regression analysis between overbite and muscular activity levels of right masseter in central occlusion.
Figure 6 Regression analysis between the range of protrusion and muscular activity levels of right masseter in central occlusion.
localized in periodontal membranes and supporting tissues play the key role.2 Several investigators reported a strict relationship between dentofacial morphology and mastication (related to electromyography of masticatory muscles, fiber direction and the cross sectional area of the muscles).21–23 However, jaw-closing and jaw-opening muscles appeared to be similarly valid in this correlation.24 Muscles analyzed in the research were anteriores temporalis, masseters, digastric, and sternocleidomastoids. Masseters are active during closing and may assist in protrusion of the mandible. Anteriores temporales may act as synergists with masseters in clench. Digastric muscles are active during various phases of jaw opening, whereas the sternocleidomastoid muscle often co-contracts with jaw clenching.1 Symmetry and synergy appear to be the most important in the proper muscular function during open/close and protrusive movements. When any parafunctional activities (clenching, grinding, different
intraoral habits) occur, the muscular system may respond by prolongation of muscular activity and derangement in its function.5,19 Muscular hyperfunction causes an increased mechanical loading of the jaws.15 In any case, it may lead to temporomandibular joint dysfunction.5 It is very interesting to note that anterior overbite has some effect on muscular activity of masseters in maximal intercuspation. A similar finding was published in Japan, when the relationship between the dentofacial morphology and the function of masticatory muscles were analyzed.24 In contrast, some investigations did not report such a finding.25 The disagreement between both studies could have its source in the different methods used for muscular activities measurements.24 A longitudinal study conducted in Brazil revealed that during the seventh year period of an evaluation, the overbite increased in the
Figure 5 Regression analysis between overbite and muscular activity levels of left masseter in central occlusion.
Figure 7 Regression analysis between the range of protrusion and muscular activity levels of left masseter in central occlusion.
CRANIOH: The Journal of Craniomandibular & Sleep Practice
2015
VOL .
33
NO .
2
139
Sierpinska et al.
140
Dental arches morphology and functional parameters
Figure 8 Regression analysis between length of maxillary arch between 16 and 26 and muscular activity levels of temporalis anterior right in central occlusion.
Figure 9 Regression analysis between length of maxillary arch between 16 and 26 and muscular activity levels of temporalis anterior left in central occlusion.
normal occlusion of adults.17 However, the reason for the finding was not explained. It would be reasonable to hypothesize that long-term high muscular activities of elevating muscles (i.e. masseters) might lead to an increased overbite. The rationalization of this finding would project that the alveolodental ligaments could allow the tooth to be pressed into alveoli, altering relations between front teeth. As a matter of fact, the overbite and overjet relate to the anterior guidance system, which can be changed through orthodontic, prosthetic and sometimes also conservative treatment.5 However, these correlations are not clear and well documented with regard to muscular activities. In the light of the study presented above, such a correlation could exist, but it demands future, more detailed investigation. The data presented demonstrated the significant correlation between masseter activity in clench and the range of protrusive movement. It is possible to explain this finding since the masseters cooperate with lateral pterygoids during contraction in protrusive movement with the teeth in very light occlusion.1,5 The findings of the investigation did not indicate the relationship between morphology of dental arches, muscular activities and occlusal parameters, even if fewer numbers of the models analyzed could suggest that such a relation could exist. The authors’ method of investigation was focused on plaster model analysis. Some other investigations concerning the problem mentioned above related to the morphological analyses were performed on lateral cephalograms. They found a significant relationship between dental arch width and facial vertical morphology.15 However, studies involving the effect of the bite force on the arch width did not indicate any relationship.26 On the other hand, there are some contrary opinions that emphasize
a significant relationship between mandibular length and jaw closing muscles.27 Although the null hypothesis that the morphology of dental arches could affect masticatory muscle activities was rejected, some limitations of the study require discussion. Even though the protocol of clinical investigation and plaster cast analysis appears to be clear and common, perhaps more detailed measurements concerning not the only morphology of dental arches, but also their occlusal characteristics should be undertaken. Functional analysis made with T-Scan II/ BioEMG could influence the subject’s behaving during the investigation. One previous study questioned the thickness of the T-Scan occlusal sensor, claiming that it may affect the mechanics of occlusion and lead to invalid tooth contact data.28 However, in that study, the sensor was cut in half and placed only on one side of the arch, and as a consequence, they did not obtain a balanced response from the muscles. In the light of the data presented in this and other studies, their finding appears to be invalid. The findings of this investigation indicate that systemic, longitudinal analyses of morphology of occlusion and muscular response in normal subjects are required.
CRANIOH: The Journal of Craniomandibular & Sleep Practice
2015
Conclusions 1. Measurements of the maxillary and mandibular dental arches revealed statistical differences between the females and males in this large, youthful, normal group. 2. Muscular activities of masseters in clench and during lateral movements were sufficiently different between the females and males of the group. 3. The muscular activities of the masseters in centric occlusion exhibited a weak positive correlation between the amount of overbite and the range of protrusive movement. VOL .
33
NO .
2
Sierpinska et al.
4. The morphology of the dental arches has limited influence on masticatory muscle activities.
11
Disclaimer Statements Contributors Special thanks to John Radke for his guidance in the preparation of this manuscript.
12
13
Funding Polish Ministry of Education and Research. Conflicts of interest All authors contributed to the work and the final version of the manuscript has been seen and approved by all co-authors. There is no conflict of interest between all the co-authors. This research was financially supported by a grant from the Polish Ministry of Education and Research (no. 40358139). Ethics approval The protocol conformed to the criteria of The Helsinki Declaration, ICH Guideline for Good Clinical Practice This protocol was approved by the Ethical Committee of Jagiellonian University, Poland, with an approval number of KBET/89B/2009.
14
15
16
17
18
19
References 1 Ash MM, Nelson SJ. Dental anatomy, physiology and occlusion. Philadelphia, PA: Elsevier; 2003. p. 430, 437–9. 2 Tartaglia GM, Testori T, Pallavera A, Marelli B, Sforza C. Electromyographic analysis of masticatory and neck muscles in subjects with natural dentition, teeth-supported and implantsupported prostheses. Clin Oral Implants Res. 2008;19:1081–8. 3 Bakke M. Mandibular elevator muscles: physiology, action, and effect of dental occlusion. Scand J Dent Res. 1993;101: 314–31. 4 Davies S, Gray RM. What is occlusion? Br Dent J. 2001;191:235–45. 5 Okeson JP. Management of temporomandibular disorders and occlusion. 5th ed. St Louis, MO: Mosby; 2003. p. 109–26. 6 Zarb G. The interface of occlusion revisited. Int J Prosthodont. 2005;18:270–1. 7 McCoy G. Occlusion confusion. Gen Dent. 2013;61:69–75. 8 Tu¨rp JC, Schindler H. The dental occlusion as a suspected cause for TMDs: epidemiological and etiological considerations. J Oral Rehabil. 2012;39:502–12. 9 Farella M, Bakke M, Michelotti A, Rapuano A, Martina R. Masseter thickness, endurance and exercise-induced pain in subjects with different vertical craniofacial morphology. Eur J Oral Sci. 2003;111:183–8. 10 Garcia-Morales P, Buschang PH, Throckmorton GS, English JD. Maximum bite force, muscle efficiency and mechanical
20
21 22 23
24
25 26
27
28
Dental arches morphology and functional parameters
advantage in children with vertical growth patterns. Eur J Orthod. 2003;25:265–72. Ferrario VF, Tartaglia GM, Galletta A, Grassi GP, Sforza C. The influence of occlusion on jaw and neck muscle activity: a surface EMG study in healthy young adults. J Oral Rehabil. 2006;33:341–8. Helsinki Declaration, ICH guideline for good clinical practice. In: Proceedings of the 59th WMA General Assembly: 1–8; October 2008; Seoul, Korea. WMA: Ferney-Voltaire, France. Kerstein RB. Combining technologies: a computerized occlusal analysis system synchronized with a computerized electromyography system. J Craniomandib Pract. 2004;22:96–109. Eroz UB, Ceylan I, Aydemir S. An investigation of mandibular morphology in subjects with different vertical facial growth patterns. Aust Orthod J. 2000;16:16–22. Forster CM, Sunga E, Chung CH. Relationship between dental arch width and vertical facial morphology in untreated adults. Eur J Orthod. 2008;30:288–94. Heikinheimo K, Nystro¨m M, Heikinheimo T, Pirttiniemi P, Pirinen S. Dental arch width, overbite, and overjet in a Finnish population with normal occlusion between the ages of 7 and 32 years. Eur J Orthod. 2012;34:418–26. Tibana RH, Palagi LM, Miguel JA. Changes in dental arch measurements of young adults with normal occlusion- a longitudinal study. Angle Orthod. 2004;74:618–23. Wang XR, Zhang Y, Xing N, Xu YF, Wang MQ. Stable tooth contacts in intercuspal occlusion makes for utilities of the jaw elevators during maximal voluntary clenching. J Oral Rehabil. 2013;40:319–28. Kerstein RB, Radke J. Masseter and temporalis excursive hyperactivity decreased by measured anterior guidance development. J Craniomandib Pract. 2012;30:243–54. Saifuddin M, Miyamoto K, Ueda HM, Shikata N, Tanne K. A quantitative electromyographic analysis of masticatory muscle activity in usual daily life. Oral Dis. 2001;7:94–100. Ingervall B, Helkimo E. Masticatory muscle force and facial morphology in man. Arch Oral Biol. 1978;23:203–6. Proctor AD, de Vicenzo JP. Masseter muscle position relative to dentofacial form. Angle Orthodontist. 1970,40:37–45. Weijs WA, Hillen B. Correlations between the cross-sectional area of the jaw muscles and craniofacial size and shape. Am J Phys Anthropol. 1986;70:423–31. Watanabe K, Watanabe M. Activity of jaw-opening and jawclosing muscles and their influence on dentofacial morphological features in normal adults. J Oral Rehabil. 2001;28:873–9. Ringqvist M. Isometric bite force and its relation to dimensions of the facial skeleton. Acta Odontologica Scand. 1973;31:35–42. Thongudomporn U, Chongsuvivatwong V, Geater AF. The effect of maximum bite force on alveolar bone morphology. Orthod Craniofac Res. 2009;12:1–8. Watanabe K. The relationship between dentofacial morphology and the isometric jaw-opening and closing muscle function as evaluated by electromyography. J Oral Rehabil. 2000;27: 639–45. Forrester SE, Presswood RG, Toy AC, Pain MT. Occlusal measurement method can affect SEMG activity during occlusion. J Oral Rehabil. 2011;38:655–60.
CRANIOH: The Journal of Craniomandibular & Sleep Practice
2015
VOL .
33
NO .
2
141
