Abstract: Objective: To analyze the force distribution in the repair of maxillary central incisor trauma during the replacement stage using composite resin materials under different occlusal modes. Methods: The maxillary central incisors in the young permanent teeth with normal shape and size were selected, and three-dimensional finite element model of the maxillary central incisors was established by reverse engineering technology with the crown was cut and designed. According to different occlusal methods, it is divided into three groups of working conditions, working condition one: 0-degree to the long axis of the tooth; working condition 2: 45-degree to the long axis of the tooth; working condition 3: 60-degree to the long axis of the tooth. According to the different types of crown folds, each group contained 5 groups, i.e. group A: normal crowns; Group B: crown folded 2 mm; Group C: crown transverse fold 4 mm; Group D: crown obliquely folded 2 mm; Group E: crown obliquely folded 4 mm. Using the three-dimensional finite element method, the maximum stress and strain values of the tooth tissue after resin restoration of the central incisor with different crown and fold types were calculated under different occlusal modes. Results: When the traumatic tooth was loaded with a force at 0-degree, the maximum stress peak value of the transverse 4 mm group was 39.755 MPa, and the maximum strain peak value of the transverse 2 mm group was 0.0013441 mm. When the injured tooth was loaded with a force at 45-degree, the stress-strain peak value of the oblique fold 2 mm group was the largest with the stress peak at 426.10 MPa and the strain peak at 0.0099519 mm. When the wounded tooth was loaded with a force at 60-degree, the stress-strain peak value of the oblique fold 2 mm group was the largest with the stress peak value at 531.88 MPa and the strain peak value at 0.0124230 mm. Conclusion: The transverse fracture group had the highest loss rate when the traumatic teeth were subjected to a 0-degree occlusal force after composite resin restoration of the traumatic crown of the upper anterior teeth of young permanent teeth. When the injured tooth was subjected to a bite force of 45-degree and 60-degree, the loss rate was the highest in the oblique 2 mm group.

Key words: young permanent teeth, anterior tooth trauma, crown fracture, resin restoration, finite element, stress analysis