The Effect of Some Parameters on Natural Occlusion in Different Ethnicities

Abstract

Natural occlusion is the resultant of many components, such as muscles, temporomandibular joints, teeth, and neuromuscular systems, and thus plays an essential role in any dental treatment. This research aims to analyze some important features of occlusion in Malaysians. A clinical examination was conducted on 120 students at MAHSA University. The sample was equally divided by gender and ethnicity (Malays, Chineses, and Indians), their age ranged between 18 to 25 years. Results showed that the incidence of canine guidance and group function occlusions was 36% and 64% respectively. Angle’s classification analysis revealed that Class I included the highest ratio of group function, class II, division 1 incorporated more group function than canine protection, while class II division 2 had more canine protection. In Class III, the occurrence for both occlusal patterns was almost equal. Other findings were that subjects with reduced horizontal overlap (0-0.9mm.) showed a 45% group function occlusal pattern, while subjects with increased (7-8.9 mm.) horizontal overlap all had group function. On the other hand, when vertical overlap exceeds 3mm., the percentage of canine protection spikes sharply and it reaches more than 80% of the cases when vertical overlap stands out at 5mm. During edge-to-edge protrusion, 45 % of individuals had anterior and posterior teeth contact, while 55% had anterior teeth contact with posterior teeth disocclusion. Class II division 2 had only anterior teeth contact with posterior teeth disocclusion, while Class III had nearly only anterior teeth contact with posterior teeth contact. There was no statistical difference in types of occlusion among ethnic groups and genders. In conclusion, Angle’s Classification, horizontal and vertical overlaps affect the occlusal pattern types during lateral excursion and protrusion. A simple formula is presented to predict the vertical and horizontal overlaps.