Chewing pattern and muscular activation in open bite patients

Maria Grazia Piancino, Gaetano Isola !, Andrea Merlo, Domenico Dalessandri, Cesare Debernardi,Pietro BraccoOrthodontic and Gnathology – Masticatory Function Department, Dental School, University of Turin, Turin, Italy

a r t i c l e i n f o

Article history:Received 17 August 2011Received in revised form 17 November 2011Accepted 6 December 2011

Keywords:Chewing patternMasticationSurface EMGJaw musclesOpen bite

a b s t r a c t

Different studies have indicated, in open bite patients, that masticatory muscles tend to generate a smallmaximum bite force and to show a reduced cross-sectional area with a lower EMG activity. The aim ofthis study was to evaluate the kinematics parameters of the chewing cycles and the activation of mass-eters and anterior temporalis muscles of patients with anterior dental open bite malocclusion. There havebeen no previous reports evaluating both kinematic values and EMG activity of patients with anterioropen bite during chewing. Fifty-two young patients (23 boys and 29 girls; mean age ± SD 11.5 ± 1.2and 10.2 ± 1.6 years, respectively) with anterior open bite malocclusion and 21 subjects with normalocclusion were selected for the study. Kinematics parameters and surface electromyography (EMG) weresimultaneously recorded during chewing a hard bolus with a kinesiograph K7-I Myotronics-Usa. Theresults showed a statistically significant difference between the open bite patients and the control groupfor a narrower chewing pattern, a shorter total and closing duration of the chewing pattern, a lower peakof both the anterior temporalis and the masseter of the bolus side.

In this study, it has been observed that open bite patients, lacking the inputs from the anterior guid-ance, that are considered important information for establishing the motor scheme of the chewing pat-tern, show narrower chewing pattern, shorter lasting chewing cycles and lower muscular activation withrespect to the control group.

Published by Elsevier Ltd.

1. Introduction

The craniofacial development, the facial shape and the dentalocclusion, are controlled by genetic and environmental factors(Proffit, 2000). These influences during growth and developmentof the face, jaws and teeth consist mainly of variable pressuresand forces related to physiological muscular activity such as mas-tication (Kiliaridis, 1995). The precise level and mode of interac-tions between facial form and muscle function have representeda question for several decades. Different studies have shown thatdifferent vertical facial heights are associated with strong or weakmasticatory muscles which are involved in the facial dimension(Ingervall and Helkimo, 1978). Muscle function and its underlyingstructure are directly related.

Open bite malocclusion is influenced by many aetiological fac-tors affecting the craniofacial skeleton as well as the dentoalveolarbone and the soft tissues. Orthodontists know the difficulties intreating skeletal open bites because of the increased vertical facialdimension. Patients with skeletal open bite show characteristicssuch as backward and downward rotation of the mandible

(Arvystas, 1977), increased vertical growth in posterior dentoalve-olar structures (Sassouni and Nanda, 1964; Schudy, 1964), shortposterior facial height (Lopez-Gavito et al., 1985), downward rota-tion of the posterior portion of the palatal plane (Kim, 1987), in-creased lower anterior facial height (Richardson, 1969), largeinterlabial gap (Cangialosi, 1984), upward and forward rotationof the anterior maxilla (Trouten et al., 1983).

The aetiology of open bite remains uncertain, but is thought tobe multi-factorial (Ngan and Fields, 1997). Differences in the com-position of masticatory musculature, resting tongue size and posi-tion are considered important aetiological factors. The influence ofthe tongue in open bite malocclusions has been recognized with amajor focus on its role as an epidemiologic factor that contributesto the development of the open space (Lowe and Johnson, 1978). Acommon feature among patients with this type of malocclusion isthe presence of tongue thrust between the upper and lower inci-sors during swallowing. Vertical malocclusion develops as a resultof the interaction of many different etiologic factors includingthumb and finger sucking, lip and tongue habits, airway obstruc-tion and true skeletal growth abnormalities. A normal, stable,and harmonious relationship of the teeth and their surroundingstructures is an essential goal of orthodontic treatment and theidentification of the aetiology improves the chances of treatmentsuccess.

1050-6411/$ - see front matter Published by Elsevier Ltd.doi:10.1016/j.jelekin.2011.12.003

! Corresponding author.E-mail address: gaetanoisola@unito.it (G. Isola).

Journal of Electromyography and Kinesiology 22 (2012) 273–279

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Different studies have indicated, in patients with a long verticalfacial height and open bite, that masticatory muscles tend to showreduced cross-sectional area, reduced EMG activity (Moller, 1966)and to generate a smaller maximum bite force (Sassouni, 1969)than patients with a shorter face (Benington et al., 1999). Aboutthe EMG activity, the results in literature are not in agreement.Some authors reported that the longer the face of an individual,the greater the EMG activity of the temporalis muscle (Uedaet al., 1998). Many papers have observed that the amplitude ofEMG, in some jaw muscles, such as masseter (Serrao et al., 2003)and temporalis (Ingervall, 1976), is greater in short-face subjects.Other reports confirmed that the muscle activity is not related withvertical face morphology (Ueda et al., 2000). Other authors did notfound differences in the EMG activity of the masseter musclebetween normal and hyperdivergent individuals (Cha et al.,2007) or between short-face, normal or long-face subjects (Farellaet al., 2003).

Mastication is a highly coordinated neuromuscular functioninvolving fast effective movements of the jaw and continuousmodulation of force, influenced by the dental occlusion. The activa-tion of the masticatory muscle depends on the size and texture ofthe food bolus to facilitate efficient crushing of the bolus on thechewing side (Piancino et al., 2008). The commands underlyingthe basic rhythmical movements of the mastication are centrallygenerated, but those involving adaptive control are regulated byafferent information, particularly related to oral-facial kinesteticinputs (Nakamura, 2000). Concomitant assessment of the chewingpattern and EMG activity of the masticatory muscles providesimportant information about the chewing function (pattern andmuscular activation) (Lewin, 1985; Piancino et al., 2009).

The aim of this study was to evaluate the kinematic parametersof the chewing cycles and the surface EMG activity of massetersand anterior temporalis muscles, simultaneously recorded, of pa-tients with dentoalveolar anterior open bite compared with a con-trol group of subjects with normal occlusion.

2. Materials and methods

2.1. Subjects

Seventy-three patients were selected for the study. 52 youngpatients (23 boys and 29 girls; mean age ± SD 11.5 ± 1.2 and10.2 ± 1.6 years, respectively), with dentoalveolar anterior openbite, and 21 subjects with normal occlusion were selected for thestudy out of 1200 patients who referred to the Orthodontic Depart-ment of the University of Turin, Italy, from January 2009 to March2011. Before entering the study informed consent was obtainedfrom each subject or their parents. Inclusion criteria were: (1)anterior dentoalveolar open bite, at least, 1 mm or more, (2) molarocclusion bilateral Angle Class I, (3) mixed dentition. Exclusion cri-teria: (1) any crossbite, (2) any functional shift of the mandible, (3)any erupting teeth, (4) any severe skeletal facial lateral asymmetry(4 mm) and (5) any signs or symptoms of temporomandibular dis-orders. The control group (mean age ± SD 11.9 ± 0.6 years of age)was strictly selected for normal occlusion and mixed dentitionand was matched with the patient group for age and gender.

2.2. Procedures

The children were comfortably seated on a chair. They wereasked to fix their eyes on a target (a red beak of a Donald Duckdrawing) on the wall, 90 cm directly in front of their seating posi-tion, and to avoid movements of the head. The measures were per-formed in a silent and comfortable environment. Each recordingbegan with the largest number of teeth in contact. The children

were asked to find this starting position by lightly tapping theiropposing teeth together and clenching. They were asked to holdthis position with the test bolus on the tongue, prior to startingthe recording. Each recording consisted of chewing for a time-period of 10 s and was repeated, for each experimental session,three times for mastication deliberately on the right side and threetimes on the left side, using a hard bolus. Repetitions of relativelyshort chewing tasks were acquired to avoid swallowing duringrecording (Jankelson, 1980) An operator controlled (visual inspec-tion) the side of mastication. The type of bolus used was a winegum, sized 20 mm in length, 1.2 mm in height, and 0.5 mm inwidth and weighted 3 g. The wine gum was chosen to provide arubber-like resistance without sticking to the teeth.

2.3. Kinematic analysis

The mandibular motion was tracked using a kinesiograph (K7-I;Myotronics, Tukwila, WA, USA) that measures jaw movementswith an accuracy of 0.1 mm. Multiple sensors (Hall effect) in alight-weight (113 g) array tracked the motion of a tiny magnetattached at the lower interincisor point. The kinesiograph wasinterfaced with a computer for data storage and subsequentanalysis.

2.4. EMG recordings

Surface EMG signals were recorded from the masseter and ante-rior temporalis muscles of both sides using a multichannel electro-myograph that is part of the K7-I WIN Diagnostic System(Jankelson, 1980). Hardware characteristics were: input ran-ge ± 5 V, fixed gain 10,000, 12 bits for analog to digital conversionand sampling frequency equal to 720 Hz. Four electrodes (Duo-trode silver/silver chloride EMG electrodes; Myotronics) were lo-cated on the masseter and anterior temporalis muscles of bothsides with an interelectrode distance of 20 mm. Before electrodeplacement, the skin was cleaned with ethanol. The location ofthe electrodes was based on anatomical landmarks (Castroflorioet al., 2005). Kinetic and EMG data were simultaneously recorded.

2.5. Signal analysis

The kinematic signals were analyzed using custom-made soft-ware (Department of Orthodontics and Gnathology, DentalSchool, Turin University, Turin, Italy) developed in Matlab (TheMathworks, Natick, MA, USA). The first cycle, during which thebolus was transferred from the tongue to the dental arches, wasexcluded from the analysis. Other cycles were excluded if theypresented at least one of the following characteristics: (1) mini-mum opening smaller than 4 mm; (2) duration shorter than300 ms; or (3) vertical opening smaller than 3 mm. The variablesevaluated during chewing deliberately on left or right side were(26): Total duration of the cycle (mean ± SD), opening duration(mean ± SD), closing duration (mean ± SD), axis angle, closure an-gle (mean ± SD), cycle width (mean ± SD), maximum lateralexcursion (mean ± SD), maximum EMG peak of left anterior tem-poralis (mean ± SD), occlusal pause of left anterior temporalis(mean ± SD), maximum EMG peak of right anterior temporalis(mean ± SD), occlusal pause of right anterior temporalis(mean ± SD), maximum EMG peak of left masseter (mean ± SD),occlusal pause of left masseter (mean ± SD), maximum EMG peakof right masseter (mean ± SD), occlusal pause of right masseter(mean ± SD). The occlusal pause is the time calculated in msec.from the end of the EMG activity of the masseter until the begin-ning of the next opening phase.

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2.6. Statistical analysis

Valid cycles from the three repetitions of each task weregrouped, thus obtaining about 30–40 cycles per subject. The vari-ables listed above were computed for each valid cycle of a givensubject. To summarize the subject’s performance, the median valuewas computed for each variable, which is robust to the eventualpresence of outliers. Most of the kinematic variables (closing angle,lateral displacement, cycle axis) and all the EMG related variable

are side dependent, e.g. the peak of the EMG envelope of the leftmasseter during a left (omolateral) mastication is different fromthe peak of the right masseter during the same (counterlateral)mastication. Thus, data obtained from mastications deliberatelyon the right side and on the left side were analyzed separately.For each variable, results from both cases and controls were thencompared by the Wilcoxon rank sum test, with the statistical sig-nificance set at 0.05. The non-parametric approach was selecteddue to the reduced size of the control sample (N = 21 Controls).

Table 1Median values of the kinematic and electromyographic variables computed from the open bite patients (N = 52) and the age-matched control group (N = 21). Between groupcomparisons were carried out by the Wilcoxon rank sum test, with statistical significance set at 5%. Legend: MOP = Mean Occlusal Pause.

Variable Side of mastication Open bite patients (median value) Control group (median value) P

Total duration (ms) Right 542 588 0.05 ⁄Left 546 594 0.05 ⁄

Opening duration (ms) Right 224 228 0.41Left 225 228 0.24

Closure duration (ms) Right 306 353 0.02 ⁄Left 303 361 0.01 ⁄

Cycle axis (frontal plane) (!) Right 77 76 0.67Left 84 81 0.01 ⁄

Closure angle (!) Right 135 134 0.93Left 51 49 0.87

Cycle width (frontal plane. mm) Right 2.8 4.1 0.02 ⁄Left 2.8 4.0 0.03 ⁄

Maximum lateral excursion (mm) Right !4.8 !5.5 0.10Left 3.4 5.3 <0.01 ⁄

Left Anterior Temporalis, Peak (lV) Right 85 152 0.01 ⁄Left 117 176 <0.01 ⁄

Left Anterior Temporalis, MOP (ms) Right 29 39 0.19Left 32 33 0.81

Right Anterior Temporalis, Peak (lV) Right 123 180 0.02 ⁄Left 103 154 0.01 ⁄

Right Anterior Temporalis, MOP (ms) Right 22 28 0.12Left 22 33 0.29

Left Masseter, peak (lV) Right 95 124 0.30Left 139 174 0.02 ⁄

Left Masseter, MOP (ms) Right 38 49 0.06Left 33 36 0.10

Right Masseter, peak (lV) Right 148 192 0.02 ⁄Left 103 129 0.32

Right Masseter, MOP (ms) Right 28 33 0.04 ⁄Left 33 49 0.02 ⁄

Fig. 1. Raw EMG data along with the vertical displacement of the jaw. Vertical dotted lines separate the cycles. The cycle onset was computed based on the start of the jaw-opening movement. Legend: LTA (Left Anterior Temporalis); LMM (Left Masseter Muscle); RMM (Right Masseter Muscle); RTA (Right Anterior Temporalis); mV (MilliVolt);Jaw Vertical displ (Jaw Vertical Displacement).

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All statistical analysis was performed using the statistical toolboxof Matlab (The Mathworks Inc.).

3. Results

The results and significance (P < 0.05) during chewing on theright and left side are reported in Table 1. Fig. 1 presents 5 s ofEMG data from a control subject, along with the vertical displace-ment of the jaw. Cycles are separated by vertical lines, on the basisof the beginning of the opening movement. The results showed astatistically significant difference between the open bite patientsand the control group, during chewing a hard bolus, on the rightand left side, for the following kinematic and EMG values: the cyclewidth resulted significantly decreased in open bite patient withrespect to the control group; the temporal parameters showed alower total duration of the chewing cycles, being the closing phaseduration significantly decreased in the patient group. The EMGpeak of left and right anterior temporalis and the EMG peak ofthe masseter of the bolus side resulted significantly lower in thepatient group. (Figs. 2 and 3). The occlusal pause showed atendency to a shorter duration for all muscles, but especially forthe masseter of the bolus side, in the patient group.

4. Discussion

In this study the kinematic parameters of the chewing patternand surface EMG activity of bilateral masseters and anterior

temporalis muscles of dentoalveolar anterior open bite patientswere compared with a control group with normal occlusion duringchewing a hard bolus (Fig. 4). There have been no previous reportsin literature evaluating both kinematic values and EMG activity ofpatients with open bite during chewing a hard bolus.

The results showed significantly shorter total duration of thechewing pattern; particularly, the duration of closing pattern re-sulted shorter in the open bite group with respect to the controlgroup. Interestingly the duration of opening was not significantlydifferent. The neuromuscular aspects of opening and closingtracings, are, of course, very different especially the end of clo-sure, which is characterized by the occlusal pause. The occlusalpause is the time calculated in msec. from the end of the EMGactivity of the masseter until the beginning of the next openingphase. It is controlled by reflexes and automatic mechanismsstrictly dependent from peripheral inputs (muscles, teeth, ton-gue, gum etc.), neural network and motor control. The occlusalpause resulted steadily shorter in open bite patients in compar-ison with the control group (Table 1). The shorter duration of thechewing cycles seems, consequently, due to the shorter durationof both the closing phase (masseters activity) and the occlusalpause. Moreover, the EMG amplitude showed, steadily, lowerpeak values in open bite patients, significant for the anteriortemporalis of both sides and for the masseter of the bolus side.We know that the anterior temporalis, right and left, controlthe posture of the mandible during chewing while the masseterof the bolus side is mainly involved in grinding the bolus(Jankelson, 1980).

Fig. 2. Difference between ‘‘open’’ patients and controls, expressed as a percentage of the control value. Gray bars are used for the deliberate right chewing. Black bars areused for the deliberate left chewing. An asterisk indicates a statistically significant difference between patients and controls.

Fig. 3. Difference between ‘‘open’’ patients and controls, expressed as a percentage of the control value. Gray bars are used for the deliberate right chewing. Black bars areused for the deliberate left chewing. An asterisk indicates a statistically significant difference between patients and controls.

276 M.G. Piancino et al. / Journal of Electromyography and Kinesiology 22 (2012) 273–279

In this study, the open bite patients showed a shorter total andclosing duration of the chewing pattern and a lower EMG ampli-tude with respect to the subjects with normal occlusion; thesefindings might be correlated to previous biomolecular reportsdemonstrating that different force contraction level could be posi-tively related with the slow-type MyHC and with fast-type MyHCat different activity levels. The myosin heavy chain (MyHC) contentof muscle fibers mainly determines the force – velocity properties(Bottinelli et al., 1996). The dynamic nature of the masticatorymuscle fibers allows them to change their phenotype to optimizecontractile function and energy uptake. These phenotype modifica-tions are reflected in the different velocity of contraction and in themaximum force generated by the masticatory muscles, especiallythe masseter. In this field, biopsies taken from human massetershowed that the different percentage of fiber-types varied signifi-cantly between subjects with different overbites; greater areas oftype I fibers were found in open bite subjects, whereas greaterareas of type II fibers were found in masseter muscles of deep bitesubjects (Rowlerson et al., 2005). In comparison with subjects withanterior open bites, subjects with deep bites have greater cross-sectional areas of the masseter fibers muscles (Gedrange et al.,2005). These changes indicate that the muscles respond to thefunctional request and the increased stretch by shifting their fi-ber-type composition towards a higher percentage of slow fibers.These findings also show that the jaw muscles adapt increasingthe length of their fibers, which involves the production of moresarcomeres in series (Goldspink, 1998).

The kinematic variables, as a consequence, also showed animportant difference that is a reduced width of the chewing pat-tern resulting in a narrow chewing pattern. Our results are inagreement with Gibbs (Lundeen, 1982) and Lewin (Lund et al.,

1999), being the meaning a reduced efficiency of the chewing pat-tern (Wilding and Lewin, 1994) Fig. 3; they generally described thechewing pattern in open bite patients, but in our study, new dataon the motor control, that is velocity parameters and EMG ampli-tude, have been added. Some of the most important peripheral in-puts influencing the chewing pattern, come from the dentalocclusion. This is clearly demonstrated in cross bite studies andit is particularly evident in the unilateral posterior crossbite maloc-clusion which is characterized by reverse chewing cycle (Piancinoet al., 2006). The cortex signals the collection of neurones in thebrain stem which elaborate different patterns of mastication in re-sponse to variations in inputs from the masticatory cortex andfrom the periphery (Katoh et al., 1982; Enomoto et al., 1987). Sen-sory receptors, such as muscle spindles, periodontal, and evenintradental pressure receptors, exert strong influences on thechewing pattern being generated by the central pattern generator,eventually modifying both the frequency of motor neurone burstsand their intensity (Lund et al., 1999). Inputs from mechanorecep-tors are critical, not only for various trigeminal reflexes such as thejaw-opening reflex or the periodontal-masseter reflex but also formasticatory control (Ishii et al., 2002; Johnsen and Trulsson, 2003).

In our study, the patients were selected on the basis of the den-tal occlusion, but we do not really know which peripheral dentalinputs are mainly responsible for the pattern of masticationfounded. It is intriguing to speculate that even if the crushing ofthe bolus is due to the molar teeth, which are in contact in openbite patients, the inputs from the anterior teeth, which are not incontact in these cases, are fundamental for an efficient chewing(Johnsen et al., 2007; Johnsen and Trulsson, 2005). This hypothesisis supported by the fact that the periodontal mechanoreceptors aremore concentrated and more specialized in the anterior incisal

Fig. 4. Masticatory pattern of patients with normal occlusion (A) and with anterior open bite malocclusion (B) during chewing a hard bolus deliberately on the left and rightside. The solid line, light gray (downward arrow): opening and dark gray (upward arrow): closing, represents the average chewing cycle of 3 trials lasting 10 s each; the lightgray and dark gray areas represent the standard deviation over the average cycle (Piancino MG, Bracco P, Vallelonga T, Merlo A, Farina D. Effect of bolus hardness on thechewing pattern and activation of masticatory muscles in subjects with normal dental occlusion. J Electromyogr Kinesiol. 2008 Dec;18(6):931–7).

M.G. Piancino et al. / Journal of Electromyography and Kinesiology 22 (2012) 273–279 277

region with respect to the posterior molar region (Johnsen andTrulsson, 2003; Trulsson and Johansson, 1996). Moreover, abouthalf of them are directly connected to the trigeminal mesencefalicnucleus, without any ganglion interruption. The peripheral inputsfrom the frontal and posterior dental guidance are very preciseand reach the cortex very quickly enabling the central nervous sys-tem to program the most convenient chewing pattern. The openbite patients lack completely the information from the anteriorteeth to establish the physiologic pattern; consequently, as it hap-pens in animals with this characteristic, this might be the reasonwhy they show a faster muscular contraction and a narrow, shortlasting and less efficient, chewing pattern, during chewing a hardbolus, with respect to the control group. Moreover, we know thatthe open bite malocclusion is often associated with reduced palataldiameters, which may result in a dental arch with a lower mastica-tory capability. Time going on, these patients, may show an alteredloading of the joint and an altered function of the masticatory sys-tem. The results of this study highlight the involvement of the neu-romuscular system in dentoalveolar anterior open bite patients,characterized by a frequent muscular activation, a lower amplitudeof the EMG peaks, a shorter duration of the chewing cycle, espe-cially of the closing pattern, and of the occlusal pause and a narrowchewing pattern. Hence, the clinical consequence is a reduced mas-ticatory efficiency and a reduced capacity of physiologic recovery,that may result in an impaired adaptation to load.

5. Conflict of Interest

The authors declare that they have no conflict of interest.

Acknowledgment

This research is partially supported by a grant of the ItalianMinistry of Research. Prin protocol 2008. Protocol number:2KAZKN.

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Maria Grazia Piancino MD (1984), DDS (1988), PhD(1998) University of Turin, Italy. Actually, she isResearcher at the Orthodontic Department, Professorin Orthodontics at the Dental School and Post-GraduateSchool in Orthodontics at the University of Turin. Since1984, she studies the physiology and pathology ofmastication and temporo-mandibular joint in normalsubjects, in orthodontic, prosthodontic and neurologicpatients. She gives lectures at national and interna-tional congresses, publishes and referees articles in thefield in national and international revues. She works inprivate practice as orthodontist since 1985.

Gaetano Isola graduated in dentistry at the Universityof Messina, Messina, Italy, in 2009. He obtained, in thesame year, a PhD Program in ‘‘Phisiopathology of theStomatognatic Apparatus and Dental Materials’’ at theUniversity of Turin, Turin, Italy. He continues to beinvolved with several research projects in the field ofthe masticatory function, gnatolology, orthodonticsand periodontology. His research interests are mainlyfocused on the biomolecular aspects and basic phys-iology of the jaw muscles, craniofacial growth, theaetiology, diagnosis and management of the differentmalocclusion and the relationship between jaw mus-culature and orthodontics. He is an active member ofThe European Orthodontic Society (EOS) and member

of the Italian Society of Periodontology (SIdP). He is author of several national andinternational peer reviewed publications about the topic of orthodontics, mastica-tory function and periodontology.

Andrea Merlo graduated in Electronics Engineering atPolitecnico of Torino, Italy, in 2000. During 2001 he wasa Fellow of the Laboratory for Neuromuscular SystemEngineering in Torino, Italy. Since 2003 he is professorat the University of Modena and Reggio Emilia, facultyof Medicine, degree in Physiotherapy. He also works asa freelance consultant for movement analysis labora-tories in Italy and Switzerland, dealing with bothclinical and research activities. He published severalpapers in international peer-reviewed journals in thefields of surface EMG and motion analysis. He wasmember of the board of the Italian society of clinicalmotion analysis in the years 2007-2011. Andrea Merlois a Registered Professional Engineer in Italy.

Domenico Dalessandri, DDS, PhD Student, DoctoralSchool in Medicine and Experimental Therapy,Department of Biomedical Sciences and HumanOncology, University of Turin, Turin, Italy andDepartment of Orthodontics, School of Dentistry,University of Brescia, Brescia, Italy. DomenicoDalessandri received his DDS from the University ofBrescia (Italy) in October 2003 and his Master in‘‘Orthodontics and Gnatology. Masticatory Function’’from the University of Turin (Italy) in December 2007.Since 2008 he is PhD Student at the Doctoral School inMedicine and Experimental Therapy - University ofTurin (Italy). He is the (co-) author of 5 peer reviewedinternational publications. His primary research

interests focus on orthodontics, masticatory function and 3D imaging. Since 2008he serves as reviewer for international peer reviewed journals.

Cesare Lorenzo Debernardi Professor Cesare LorenzoDebernardi was born in Torino on 1954 november the9th. MD (1979) and DDS (1982), since 2002 is fullprofessor in Odontostomatologic Deseases at TorinoUniversity, where is active in the Department ofOrthodontics and Gnathology, Dental School. He isPresident of the graduation program in DentalHygiene. He is Director of the Post-graduate Programin Orthodontics. He is Author of 103 papers, publishedon International and National Journals. He attended asa speaker to several International and National Con-gresses. His main interests are oriented to the ortho-dontic treatment of the adult patient.

Pietro Bracco MD (1967), DDS (1969), DOS (1979).Chairman of the Chair of Orthodontics and Gnathol-ogy (masticatory function), Dental School, Universityof Turin. Director of the Dental School at the Univer-sity of Turin 1992-1997. Chief of the Hospital Ortho-dontic Department. Chief of the dental PhD schoolXXI-XXIII cycle. Director of the Master in Orthodontics2004-2008. Vice-president of the OrthodontistsUnion. Author and co-author of 250 scientific articlespublished on national and international revues.

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