Digital analysis of the relationship between maximum bite force and 3-dimensional arrangement of mandibular first molars.

Abstract

Background: Bite force is one of the important factors that determine the chewing efficiency of molars. This study aimed to investigate the relationship of the maximum bite force (MBF) to the 3-dimensional (3D) arrangement of the first mandibular molars in Angle's class I healthy adults using a digital protocol.

Material and methods: Subjects were 33 adults (16 males and 17 females) aged 18-25, with Angle's class I occlusions and healthy dentitions. MBF was recorded by a digital occlusal force gauge (BFM 4th generation, Vietnam). 3D models were scanned using TRIOS 3 intra-oral scanner (3Shape, Denmark), and analyzed using Geomagic Design X software (Artec, Luxembourg). The digital measurement included two steps: reorientation and measuring. First, all the virtual upper models were reoriented into the same Oxyz coordinates using 3 landmarks: one at the incisive papilla and two at the intersection of the palatal sulci of the first permanent molars with the gingival margin. Next, 3D position of the first mandibular molars was measured using crown angulation (CA), crown inclination (CI), and depth of curve of Spee (DCOS). t-tests were conducted to compare the mean values between sides and gender. Pearson's correlation coefficient was performed to evaluate the statistical relationships.

Results: Mean MBF was 619.66±36.25 N; mean DCOS was 1.73±0.30 mm; mean CA and CI were 2.21±1.70° and -29.65±6.93°, respectively. Male adults showed greater MBF than females significantly. Correlation coefficient between MBF and CA was -0.60, and between MBF and CI was -0.43 significantly. MBF and DCOS were not related.

Conclusions: MBF was influenced by gender and the first mandibular molar CA and CI. Hence, it should be considered carefully when the treatment plan includes restoration or any change in the position of the first mandibular molars. Key words:Bite force, curve of Spee, crown angulation, crown inclination, digital dentistry.