Specify the limits of the maximum opening of the oral cavity in adults?

• A. 20-40 mm
• B. 40-50 mm
• C. 40-60 mm
• D. 50-70 mm

Answer: (C)

Normal maximal mouth opening reflects how well the temporomandibular joints and surrounding muscles function, and is measured as the distance between the upper and lower incisors at the widest comfortable opening. In adults, a typical normal range is about 40–60 mm, with around 50 mm being average. Opening below 40 mm can indicate trismus or TMJ dysfunction, while openings above 60 mm are less common. So the 40–60 mm range best represents the normal limits for adults.