Mouthguards were used to protect boxers from lip lacerations and other soft tissue injuries in the late 19th century. Now they are used various parts of dental treatment, which are sports protective aid, bleaching tray, orthodontic retainer, implant insertion guide tray, splint and so on.

Repeated dislodgement of Class V restoration due to habitual clenching stress should be restored with stress control. Mouthguard can be used as stress relief device.

This case describes methods that can relieve occlusal force to teeth by using mouthguard.

Satisfactory results can be obtained by using mouthguard for retention of repeated dislodgement Class V restorations.

If patients suffered from repeated restorations of Class V due to clenching, mouthguard can be used additional device to relieve the occlusal stress in conservative dentistry.