Fixed dentures require a certain amount of grinding of natural teeth, and a denture edge that fits tightly to ensure long-term results after placement. If the marginal fit is poor, saliva and bacteria will invade the gap between the denture and the natural teeth, resulting in secondary caries and pulpitis. If the marginal fit is poor, almost 100% of the teeth will develop gingivitis, gum congestion, redness and swelling, easy bleeding when brushing teeth, bad breath. Then it will develop into periodontitis and eventually the tooth will loosen and fall off.