The Relationship Between Oral Tori and Bite Forces
The relationship between oral tori and bite forces
Chan-Woo JEONG1*, Kyung-Ho KIM2 , Jengbin PARK1, Hye-Sun KIM1, Jong- Ki HUH1, Kwang-Ho PARK1
1Department of Oral and Maxillofacial Surgery and 2Department of Orthodontics, Gangnam Severance Hospital, College of Dentistry, Yonsei University, SOUTH KOREA
The tori are exostosis that is formed by a dense cortical and limited amount of bone marrow, and these are developed very slowly but progressively. Although exact cause of appearance of the tori is not clear, the tori are influenced by genetic and environmental factors. The oral parafunctional habits such as bruxism and occlusal stress are importantly considered to be environmental factors. As former study that was published in our department, patients who had oral parafunctional habits or TMD had more mandibular torus than none of parafunctional habits or TMD. As excessive bite force is common co-factor of the oral parafunctional habits and TMD, we intended to investigate the relationship between size of oral torus and bite force.
Patients and methods:
Data for this study were utilized from cast and bite force measurement of which patients were to get orthodontic treatment in Department of Orthodontics, Gangnam Severance Hospital, Yonsei University from 2010 to 2013. The size of torus palatinus and torus mandibularis were measured by sliding caliper on patient’s diagnostic cast. The size of torus palatinus was classified as small (3mm>), medium (3~5mm) and large (5mm<) according to elevation. The size of torus mandibularis was classified as small (3mm>), medium (3~6mm) and large (6mm<) according to height.(Reichart et al., 1988). The general inclusion criteria were as follows; no history of orthodontic treatment, presence of healthy full permanent dentition and no damage of cast. According to these criteria, 345 (105 male, 240 female) subjects were found acceptable for the study.
The type of torus palatinus was classified as flat, nodular, spindle and lobular.(Thoma and Goldman, 1960). The type of torus mandibularis was classified as bulging, double lobulated, multiple lobulated and single lobulated. (Reichart et al., 1988)
The bite force was measured by follows. The patient was trained to bite the pressure sensitive sheet (Dental Prescale 50H, type R, Fuji Film Corp., Tokyo, Japan) on consistent point. And the patient bite the sheet with maximal bite force on 5 seconds and the sheet was deciphered by CCD camera (Occluzer FPD 707, Fuji Film Corp., Tokyo, Japan).
Result :
Correlation between bite force and type of torus palatinus is not significant. Although Patients who had torus mandibularis had bigger bite force than none of torus mandibularis, their statistical significance was low. There was significant correlation between the size of mandibularis and bite force (P<0.05), but not in type of torus mandibularis.
Conclusions :
There was significant correlation between the size of torus mandibularis and bite force. We suspect that the formation of torus mandibularis affected by bite force and clenching period of time. In TMD patient torus mandibularis which could be used to indicator of the bite force help get useful information about distribution of biting force to teeth or condyles.
References :
Al-Bayaty H, Murti P, Matthews R, Gupta P: An epidemiological study of tori among 667 dental outpatients in Trinidad & Tobago, West Indies. International dental journal 51(4): 300-304, 2001.
Al Quran F, Al-Dwairi Z: Torus palatinus and torus mandibularis in edentulous patients. J Contemp Dent Pract 7(2): 112-119, 2006.