Computerized occlusal analysis in bruxism

Abstract

Introduction. Sleep bruxism as nocturnal parafunction, also known as tooth grinding, is the most common parasomnia (sleep disorder). Most tooth grinding occurs during rapid eye movement - REM sleep. Sleep bruxism is an oral habit characterized by rhythmic activity of the masticatory muscles (m. masseter) that causes forced contact between dental surfaces during sleep. Sleep bruxism has been associated with craniomandibular disorders including temporomandibular joint discomfort, pulpalgia, premature loss of teeth due to excessive attrition and mobility, headache, muscle ache, sleep interruption of an individual and problems with removable and fixed denture. Basically, two groups of etiological factors can be distinguished, viz., peripheral (occlusal) factors and central (pathophysiological and psychological) factors. The role of occlusion (occlusal discrepancies) as the causative factor is not enough mentioned in relation to bruxism. Objective. The main objective of this paper was to evaluate the connection between occlusal factors and nocturnal parafunctional activities (occlusal disharmonies and bruxism). Method. Two groups were formed- experimental of 15 persons with signs and symptoms of nocturnal parafunctional activity of mandible (mean age 26.6 years) and control of 42 persons with no signs and symptoms of bruxism (mean age 26.3 yrs.). The computerized occlusal analyses were performed using the T-Scan II system (Tekscan, Boston, USA). 2D occlusograms were analyzed showing the occlusal force, the center of the occlusal force with the trajectory and the number of antagonistic tooth contacts. Results. Statistically significant difference of force distribution was found between the left and the right side of the arch (L%-R%) (t=2.773; p lt 0.02) in the group with bruxism. The difference of the centre of occlusal force - COF trajectory between the experimental and control group was not significant, but the trajectory of COF was longer in the group of bruxists (67.3±24.4mm). In addition, the significant difference of COF position in relation to the center of the elliptic fields was not found in bruxists (χ2=1.63; p> 0.05), but obtained results directly revealed uneven distribution of the occlusal forces which caused the excessive attrition and mobility of tooth. Conclusion. Our study failed to find direct correlation between occlusal factors and bruxism, so they are basically contributing factors.

Uvod. Bruksizam je noćna parafunkcionalna aktivnost mandibule i svrstava se u parasomniju ili poremećaj spavanja. Javlja se u REM fazi sna u vidu ritmične hiperaktivnosti mastikatornih mišića (m. masseter) koja destruktivno deluje skoro na sve komponente orofacijalnog sistema. Posledice ovog fenomena su trošenje zubnog tkiva, bol usled spazma mišića, miogene i artrogene disfunkcije sa mogućim degenerativnim intrakapsulnim promenama, pulpalgija, oboljenja parodoncijuma, glavobolje, naročito u jutarnjim časovima, i problemi različite prirode na pokretnim i fiksnim zubnim nadoknadama (trošenje akrilatnih zuba i akrilatnih faseta). U etiologiji bruksizma najčešće učestvuju periferni okluzalni i centralni psihogeni faktori. Uloga okluzije u etiologiji bruksizma nije dovoljno istražena niti definisana. Cilj rada. Cilj istraživanja je bio da se utvrdi veza između okluzalnih disharmonija i bruksizma, odnosno da se proceni značaj okluzije u nastanku bruksizma. Metod rada U istraživanje su uključene eksperimentalna i kontrolna grupa ispitanika. Eksperimentalnu grupu činilo je 15 ispitanika s evidentnim znacima i simptomima bruksizma, prosečne starosti od 26,6 godina, a kontrolnu grupu 42 osobe s izostankom bruksizma, prosečne starosti od 26,3 godine. Okluzija je analizirana kompjuterski, T-Scan II sistemom. Na dvodimenzionalnim kompjuterskim okluzogramima komentarisani su sledeći parametri: okluzalna opterećenja, centar okluzalnih sila i njegova putanja i broj antagonističkih parova zuba. Rezultati Kompjuterska analiza okluzije ukazuje na značajne razlike u opterećenju leve i desne strane (L%-D%) zubika (t=2,773; p lt 0,02) u korist ispitanika sa bruksizmom. Razlika u trajektorijumu centra okluzalnih sila (COF) nije značajna, ali je kod osoba sa bruksizmom trajektorijum COF duži (67,3±24,4 mm). Kod ispitanika sa bruksizmom takođe nije utvrđena statistički značajna razlika u položaju COF u odnosu na centar eliptičnih polja (χ2= 1,63; p>0,05), međutim, dobijeni rezultati ukazuju na evidentno neuravnoteženo opterećenje okluzije kod njih. Zaključak. Na osnovu rezultata kompjuterske analize okluzije može se zaključiti da okluzalni faktor doprinosi nastanku bruksizma.