BLIZANACA EVALUATION OF HELKIMO ANAMNESTIC AND DYSFUNCTION INDEX IN IDENTICAL TWINS

Uvod: Marti Helkimo je 1974. godine dizajnirao posebne upitnike za unošenje adekvatnih podataka dobijenih anamnezom, analizom funkcija orofacijalnog sistema i analizom okluzije. Podaci se vrednuju numerički sa 0, 1 ili 5, u zavisnosti od odgovarajuće izraženosti nalaza i težine kliničkog znaka, odnosno simptoma disfunkcije. Cilj: Cilj oralno-epidemiološkog i funkcionalnog ispitivanja je utvrđivanje i vrednovanje specijalno dizajniranog anamnestičkog indeksa i indeksa disfunkcije po Helkimu kod jednojačanih blizanaca. Materijal i metode: Longitudinalno prospektivno ispitivanje izvršeno je na randomizovanom uzorku od 30 parova jednojajčanih blizanaca, podjednake polne zastupljenosti i hronološkog uzrasta od 20 do 40 godina. Namenski istraživački dizajn kliničkog upitnika omogućio je izračunavanje anamnestičkog indeksa (Ai) po Helkimu, na osnovu subjektivnog osećaja i pozitivnih ili negativnih odgovora ispitanika o stanju njihovog mastikatornog aparata. Klinički indeks disfunkcije (Di) predstavlja objektivnu funkcionalnu analizu strukturnih i funkcionalnih poremećaja orofacijalnog kompleksa, zahvaljujući zbiru parametara dobijenih vrednovanjem kinematike donje vilice, stanja i limitirane funkcije temporomandibularnih zglobova, prisustva ili odsustva bolnih senzacija pri kretnjama mandibule, tokom palpacije donjoviličnih zglobova i mastikatornih mišića, odnosno sveukupnoj kvantifikaciji učestalosti kraniomandibularnih disfunkcija. Istraživanja su sprovedena u skladu s lokalnim i međunarodnim pravima i etičkim normama. Rezultati: U anamnezi 47 (78,3%) blizanaca ne navodi znake i simptome kraniomandibularnih disfunkcija, odnosno ima Аi=0. Subjektivno svesni postojanja blagih znakova kraniomandibularnih disfunkcija (KMD) bilo je 12 ispitanika, a akutni, izraziti kraniomandibularni poremećaji identifikovani su kod jednog blizanca Ai II 1 (1,7% ). Vrednovanjem i analizom rezultata dobijenih kliničkom funkcionalnom analizom po Helkimu, pozitivni indeks disfunkcije (Di >0), odnosno određeni znaci i simptomi poremećene funkcije TMZ ,utvrđeni su kod 23 jednojajčana blizanca (38,3%), dok je indeks disfunkcije jednak 0 (Di=0) registrovan kod 37 (61,7%) blizanaca, koji nemaju kraniomandibularne poremećaje (KMD). Spiarmanоva korelacija (0,728) dokazuje da postoji koeficijent međuzavisnosti, odnosno obostrane povezanosti anamnestičkog indeksa ( Аi) i indeksa disfunkcije (Di) statistički značajan na nivou 1% (p=0,000). Zaključak: Оvа komparativna statistička analiza pokazala je da postoji uzajamna povezanost anamnestičkog indeksa (Ai) i kliničkog indeksa disfunkcije (Di) po Helkimu.


Introduction
Identical (monozygotic) twins is a multidisciplinary phenomenon.In scientific studies, they are equally interesting to geneticists, gynecologists, paediatricians, ENT specialists, anthropologists, prosthetists, orthodontists, physiologists, educators, psychologists.However, only in the second decade of the 21st century, twins, torn between behavioral genetics and embryology, brought supporters of natural and reconstructed occlusion closer.Their current research contributed to detecting individual diversity, beautifully composed into a functional whole -today gnatology -a relatively young science.
Gnathological concept insists on functional diagnostics.It relies on the latest findings in the field of neurophysiology, physiology and pathology of the TM joint, which significantly contributed to introducing new concepts of occlusion role in programmed function of the orofacial system, diagnosing its functional disorders and possible treatments.Functional anatomy of the orofacial system deals with the skeletal structures of the viscerocranium, orofacial muscles, temporomandibular joints, teeth and their supporting tissues, oral tissue, blood vessels and nerves that supply and innervate these tissues.That is why the orofacial system, in the literature also known by the synonyms "orofacial system "," maxillofacial system "," masticatory system "," masticatory apparatus "and "chewing organ ", represents a set of organs and tissues that carry out masticatory, phonetic and physiognomically function and participate in the functions of breathing and digestion.
Following the example of other systems in the human body, the orofacial system is characterized by interdependence of form and function.The function of this system is accomplished owing to the muscles and nerve impulses, while skeletal structure of the jaw, TM joints, ligaments and occlusal complex serves as passive conductors.They are specific for each individual, which is particularly important in the reconstruction, even when it comes to the tiniest anatomical details in the orofacial system.
Osnovni kriterijum za izbor i formiranje studijske grupe bila je očuvana funkcija orofacijalnog sistema, kod jednojajčanih blizanaca s prebivalištem u četiri opštine numerically with 0, 1 or 5, depending on the severity of the relevant findings and severity of clinical sign or symptoms of dysfunction.
Thanks to the results of longitudinal epidemiological studies, Helkimo has defined the orofacial system dysfunction, as a clinical condition characterized by the presence of one or more of the following signs: disrupted flow and range of motion of the lower jaw, impaired function of one or both TM joints, the presence of deviation larger than 2mm at mouth opening, the presence of sounds from the TM joints during movements of the lower jaw, hypersensitivity of masticatory muscles and joints on palpation, pain provoked by lower jaw movements 3 .
Based on the obtained numerical value, anamnestic dysfunction index (Ai) and clinical dysfunction index (Di) were calculated.

Aim of research
The aim of the research was to establish and evaluate specially designed anamnestic index and Helkimo index of dysfunction in monozygotic twins.

Materials and Methods
A longitudinal prospective study was carried out on a randomized sample of 30 pairs of twins, 20 to 40 years old, of both sexes.
Excluded from the study were: subjects in whom clinical examination indicated pain of odontogenic, neurogenic, vascular and inflammatory origin, or in connection with tumor lesions from the surrounding anatomical structures (ear, throat, eye, nose, sinuses ), respondents who had some other chronic disease that impairs or endangers general health condition and gives a false picture, respondents younger than 20 and older than 40 years, and potential respondents who did not agree to participate in the study.
The main criteria for selection and formation of the target group was the preserved function of the orofacial system in identical twins, residents of four municipalities from Serbia and two from Montenegro (Tutin, Novi Pazar, Sjenica, Raška, Rožaje and Bijelo Polje).
All examinations were performed in the dental office on the physiological chair, with artificial lighting.We used the standard equipment for specialist dental examination, with obligatory polyethylene gloves.Instruments for visual inspection, muscle palpation, determination of potential anomalies of the temporomandibular joint (TMJ) and occlusal relationships included ekarter and mirror.
Anamnestic structure was composed of general medical history of respondents and their parents, with special attention to the family history and chronology of twin births.Data were then collected on postpartum body weight, length and possible characteristics of MZ twins, possible febrile conditions, trauma, seizures, hospitalization and surgical interventions.Research design of the questionnaire made it possible to calculate the anamnestic index and clinical dysfunction index by Helkimo.1.Anamnestic index (Ai) is based on a subjective feeling of respondents.Questionnaire design made it possible to calculate Ai by Helkimo, obtained based on positive and negative responses, on targeted but not leading questions.The obtained data were numerically evaluated with 0, 1 or 5, depending on the severity of the symptoms earlier mentioned.Anamnestic index is graded in three levels: • Ai 0 -if respondent has no symptoms of CMD, or does not provide an affirmative answer to any posed question.In this case, the respondent answers negatively to questions.Therefore, the index value Ai = 0. • Ai I -if respondent has mild symptoms of CMD.In this situation, the interviewee responds positively to some of the following questions: Is there pain in the cheek area?Are there audible sounds in the temporomandibular joint while moving the lower jaw?Has respondent had jaw clenching, teeth grinding and jaw stiffness during movements?Is there muscle fatigue (especially after waking up)?Is there pain in the neck?In these cases, the value of anamnestic index is 1, e.i., Ai = I. pokretima i zamora mišića (naročito posle buđenja), bolovi u vratu.U ovim slučajevima, vrednost anamnestičkog indeksa je 1, odnosno Ai I =1.

•
Ai II -if symptoms are expressed.The interviewee responds positively to some of the following questions: Was there pain in the masticatory muscles (temples, cheek, tongue)?Has respondent experienced pain in the temporomandibular joint, or when moving the mandible?Are limited mouth opening, limited movements aside and difficulty in closing mouth present?The anamnestic index value Ai II = 5.
The values of dysfunction index range from 0 to 25 points, and based on its value, the degree of craniomandibular dysfunction can be determined.According to Helkimo, mobility of the lower jaw (Mi) is calculated by summing the points received trough the evaluation of: opening and closing the mouth, protrusive movements of the lower jaw and possible sounds in TM joints during movements., a uz odobrenje lokalnog etičkog komiteta 6 .Od početka do kraja istraživačkog dizajna, u istoj ravni, bili su interesi ispitanika i svrha istraživanja, negovana je etičnost, tj.apsolutno poštovanje ličnosti i potpuna anonimnost svih ispitanika, tretiranih, vođenih i prikazanih kao osobe, a ne kao "slučaj" ili "varijabilna struktura".Rezultati su statistički analizirani u programu SPSS-a.
Study is carried out in accordance with the local and international laws and ethical standards (the Universal Declaration on Bioethics, Convention on Human Rights and Biomedicine, United Nations Declaration of Human Rights, Helsinki Declaration, World Medical Association (WMA) on Human Rights 4 5 , and with the approval of the local ethical committee 6 .From start to the end of the research, interests of patients and the aim of study were taken as equal, i.e. respondents were treated with due respect and presented as people and not as ''subjects'' , ''cases'' or ''variables''.

Results
Medical records of 47 (78.3%) twins did not present the signs and symptoms of craniomandibular dysfunction, i.e., Ai = 0 specified.Twelve respondents were aware of the existence of mild signs of craniomandibular disorders (CMD); acute and expressed craniomandibular disorder was identified in one of the twins Ai II 1 (1.7%).
By evaluating and analyzing the results obtained using Helkimo analysis,positive dysfunction index (Di> 0), or certain signs and symptoms of impaired function of TMJ were established in 23 twins (38.3%), while the dysfunction index n equal to 0 (dI = 0) was found in 37 (61.7%)twins.
The average difference of -0.467 between these groups of twins (for a group of male twins: M = 0.57, SD = 1,547; for a group of female twins: M = 1.03,SD = 1.866) was not statistically significant at the level α = 5%, t (58) = -1.055,p = 0.296 (two-sided).95% confidence interval extended from -1.352 to 0.41.Also, by comparing males in same twin pair (intra-pair comparison), the t-test did not reveal statistically significant difference in the total number of dysfunction points, between the members of the same male twin pairs.
When intra-pair analysis of the female twin pairs is concerned, the t-test also did not reveal statistically significant difference in the total number of dysfunction points in the members of the same twin pairs.
In intra-pair analysis of dependent paired samples, the t-test did not find a statistically significant difference in the total number of dysfunction points between groups of female twins.Таbela 10.Uporedni odnos anamnestičkog indeksa (Ai) i indeksa disfunkcije (Di) Table 10.Correlation between anamnestic index (Ai) and dysfunction index (Di)
This comparative statistical analysis showed there is a correlation between anamnestic and dysfunction indexes.This means that if Ai = 0, then every tenth respondent (10%) has symptoms of CMD, and 90% of respondents have no such manifestations.If Ai is greater than 0, 89% of respondents have dysfunctional disorders, and 11% do not.Comparative analysis shows that most of respondents were aware of the presence of disorder, as well as that medical history can help in the diagnosis of CMD.
Also, there is a statistically significant difference between the frequency and theoretical frequency of anamnesis index (Ai) and dysfunction index (Di).This statistical significance was obtained within certain groups, Chi-square=0,000 = .
By crossing the variables, for anamnesis (Ai) and dysfunction index (Di) of identical twins, statistically significant difference between the frequency of Ai and Di modalities was found; p = Asymp.Sig.

Discusion
Latest research on natural teeth has shown that stability and functional value of natural occlusion are not conditioned only by perfect order and the relation of natural teeth 7 ,on the contrary, such a harmony in nature is a real rarity.Numerous studies showed there's a high incidence of interjaw relations and orofacial system function disorders.Population group analyzed during this longitudinal study is an exception.
Evaluation of the functional capabilities of orofacial (OFS) system was carried out using Helkimos anamnestic and clinical dysfunction index 8 .Their application is traditional and precious, regardless of criticism in epidemiological studies [9][10][11][12] .Also, the latest indexes are trying to reduce the disadvantages of Helkimos indexes 13,14 .
The role of occlusal disharmony in etiology of craniomandibular dysfunction (CMD) is still a controversial issue in scientific literature and clinical practice.Even after several years of research, the role of occlusal factors in the development of TMJ dysfunction has not been defined yet.Numerous studies confirmed the role of occlusal factors in the development of CMD, while stressing that their impact is not of primary significance [15][16][17][18] .Also, there are studies that deny the role and importance of occlusion in development of CMD 19 .
Despite numerous controversies, prevailing opinion is that occlusal factors do not play a primary role in the etiology of CMD, but certainly, at least partially, participate and can lead to the exacerbation of symptoms in individuals in which CMD occurred as a result of trauma, congenital disorders, systemic diseases or emotional stress, which role is increasingly stressed lately [20][21][22] .Also, compared to healthy subjects, subjects with CMD show extremely high prevalence of various orofacial manifestations, such as xerostomia, glosodinia, dysphagia and dysgeusia 23 .Further, the results of numerous epidemiological studies have shown a significant presence of occlusal disharmony in patients with evident signs and symptoms of CMD's [24][25][26] .
Using Helkimos anamnestic index, we established the prevalence of subjective symptoms in temporo-mandibular disorders.Fifty-four percent of respondents had some of the symptoms, with sound in TMJ being the most common symptom.Similar results came from the study conducted by Egermarck 28 and Mazenga and associates 29 who found that sound in the temporomandibular joints are the most common symptom in medical history.Egermark 28 and Magnuson and associates 30 concluded that sound in the temporomandibular joints was a striking indicator of TMJ dysfunction.
However, Magnus 31 has emphasized that the sound in the TMJ is not an indication for medical treatment, which is still a current issue: whether the painless sound is sign or symptom of TMD.Also, the Nurallah and Johanson 32 , Okeson 33 Stanisic-Sinobad 34 , Bumann and Lotzmann 35 state that the sound occurs without obvious pain and disorders in muscles or TMJ.
Obviously, the results of epidemiological studies are difficult to compare due to different sample selection criteria, different methodology and a different way of evaluating certain signs and symptoms of CMD.Using Helkimos clinical TMD index, we established the prevalence of signs in temporomandibular disorders.It was noted that slightly decreased mobility of the mandible, the most common sign of TMD, occurred in 54% of patients.Ajanović 36 concludes that in the initial phase, the restricted mobility of the mandible is one of the most common signs of temporomandibular dysfunction.
According to our results, after crossing the Helkimos variables Ai and Di indexes, and after the interpretation of occlusal relations, an unexpectedly high significant dispersion of results between twin pairs was not recorded, nor was affirmed a long-run thesis about the phenotypic variation by Horovitz et al (1958).High incidence of distal occlusion is in favor of some studies that have suggested that distal occlusion can be potential factors in the development of CMD.kao najčešći znak TMP-a, javila kod 54% ispitanika.Ajanović 36 zaključuje da je u početnoj fazi ograničena pokretljivost mandibule jedan od najčešćih znakova temporomandibularnih disfunkcija.
High incidence of distal occlusion in favor of some studies that have suggested that Distal occlusion can be a potential factor in the development of CMD.Particularly, in extreme amounts, while the average value of vertical and horizontal overlap mutually conflicting as possible ethological factors [33][34][35][36][37] , although John MT and his associates offered the opposite experience.
In contrast, numerous study which deny existence of direct correlation between the occlusal disharmony and symptoms (signs) of CMD, stating that the structures of the orofacial system adapted to the presence of occlusal interferences and function normally within tolerance limits without having signs (symptoms) of MD [38][39][40][41] .
At the same time, careful evaluation of clinical symptoms and diagnostic procedures connection with applicable classification systems are the most common key to successful diagnosis of anatomical and functional disorders in the orofacial region.Therefore, in modern dental practice, in these cases, interdisciplinary diagnostic evaluation, dependent on the symptoms, heritage and psychosocial factors is necessary.
Lack of an universally accepted classification system of orofacial disorders and the use of various inclusive and exclusionary criteria for defining similar subgroups and conditions in different taxonomic systems, are resulting in confusion and inability to compare existing results.

Conclusions
After the clinical and functional analysis of the orofacial system on a sample of 60 pairs of twins, aged 20 to 40 years, of both sexes, the obtained results pointed to the following conclusions: 1.By establishing various degrees of CMD manifestations according to Helkimo, we obtained the values of anamnestic index (Ai) 71% and dysfunction index (Di) 54.55%,

2 .
The clinical dysfunction index (Di) represents the sum of parameters obtained by evaluating kinematics of the lower jaw, condition and limited function of the temporomandibular joints, the presence or absence of painful sensations during mandible movements, or during the palpation of the lower jaw joints and masticatory muscles.Dysfunction index, objectively expresses the level of dysfunction, and it is numerically presented based on data obtained during objective functional analysis of the orofacial complex.Based on Helkimos anamnestic dysfunction index data about the symptoms of temporomandibular disorders were received and clinical examination confirmed the signs of dysfunction.Helkimos clinical dysfunction index (Di), formed based on five signs of temporomandibular disorders, numerically expressed the degree of craniomandibular dysfunction (CMD), obtained by adding points of analysis and evaluation of the: Lower jaw mobility (Mi) Painful sensation when moving the mandible (B) Function of temporomandibular joints (C) Temporomandibular joint palpation sensitivity (D) and Masticatory muscles palpation sensitivity (E):

Table 2 .
Parameters of Helkimos clinical dysfunction index (Di)

Table 4 .
Frequency of distribution of MZ twins according to anamnestic dysfunction index

Table 6 .
Inter-pair comparison of dysfunction points in relation to sex

Table 7 .
Intra-pair comparison of male twin pairs

Table 8 .
Intra-pair comparison of female twin pairs