One case of complicated crown root fracture of upper anterior teeth managed by multidisciplinary joint approaches.

Complicated crown root fracture is a serious combined fracture of the enamel, dentin, and cementum in dental trauma. The treatment method is complicated. During the procedure, the condition of pulp, periodontal, and tooth body should be thoroughly evaluated, and a multidisciplinary approach combined with sequential treatment is recommended. This case reported the different treatment and repair processes of one case of two affected teeth after complicated crown root fracture of upper anterior teeth, including regrafting of broken crown after flap surgery at the first visit, direct resin repair to remove broken fragments, and pulp treatment and post-crown repair at the second visit. After 18 months of follow-up, the preservation treatment of the affected teeth with complicated crown root fracture was achieved. Therefore, fragment reattachment and post-crown restoration are feasible treatment options for children with complicated crown root fracture.

The effect of root canal treatment and post-crown restorations on stress distribution in teeth with periapical periodontitis: a finite element analysis.

AIM: To evaluate the effects of root canal treatment (RCT) and post-crown restoration on stress distribution in teeth with periapical bone defects using finite element analysis. METHODOLOGY: Finite element models of mandibular second premolars and those with periapical bone defects (spherical defects with diameters of 5, 10, 15, and 20 mm) were created using digital model design software. The corresponding RCT and post-crown restoration models were constructed based on the different sizes of periapical bone defect models. The von Mises stress and tooth displacement distributions were comprehensively analyzed in each model. RESULTS: Overall analysis of the models: RCT significantly increased the maximum von Mises stresses in teeth with periapical bone defects, while post-crown restoration greatly reduced the maximum von Mises stresses. RCT and post-crown restoration slightly reduced tooth displacement in the affected tooth. Internal analysis of tooth: RCT dramatically increased the maximum von Mises stress in all regions of the tooth, with the most pronounced increase in the coronal surface region. The post-crown restoration balances the internal stresses of the tooth and is most effective in periapical bone defect - 20-mm model. RCT and post-crown restoration slightly reduced the tooth displacement in all regions of the affected tooth. CONCLUSIONS: Root canal treatment seemed not to improve the biomechanical state of teeth with periapical bone defects. In contrast, post-crown restoration might effectively balance the stress concentrations caused by periapical bone defects, particularly extensive ones.

Comparison of stress distribution between zirconia/alloy endocrown and CAD/CAM multi-piece zirconia post-crown: three-dimensional finite element analysis.

OBJECTIVES: This study aimed to evaluate a digital multi-piece zirconia post-crown to restore a mandibular second molar with extensive coronal loss and limited restoration space, and to compare the stress distribution between endocrowns made of zirconia or alloy and CAD/CAM multi-piece zirconia post-crowns. MATERIAL AND METHODS: Four three-dimensional finite element analysis models of a mandibular second molar with extensive coronal loss and limited restoration space were created as follows: (A) intact molar; (B) zirconia endocrown restored molar; (C) multi-piece post-crown restored-molar with tapered nail; (D) multi-piece post-crown restored molar with T-shaped nail. Models C and D were divided into two subgroups according to the material type: C1/D1, zirconia; C2/D2, NiCr alloy. The maximum modified von Mises failure criterion (mvM) stresses were calculated, and the stress distribution was recorded to analyze the effects of the restoration and material types on the biomechanical properties of dentin and prosthesis. RESULTS: The maximum mvM stress of dentin in model B (33.80 MPa) was lower compared with models C (C1, 37.81 MPa; C2, 36.36 MPa) and D (D1, 36.34 MPa; D2, 34.97 MPa) under vertical load, but the opposite was observed under oblique load. The highest mvM stress was concentrated in the nail region located in the root canal, and the T-shaped nail values were greater than the tapered nail, whereas model D with T-shaped nail showed a lower mvM stress level in dentin compared with Model C with tapered nail. CONCLUSIONS: The digital multi-piece zirconia post-crown is a potential approach to restore mandibular second molars with extensive coronal loss and limited restoration space. CLINICAL RELEVANCE: The digital multi-piece zirconia post-crown has potential to restore mandibular second molars with extensive coronal loss and limited restoration space using an innovative approach.

Evaluation on clinical effect of cast pure titanium split post crown restoration of molars with low occlusogingival distance and large root furcation / 吉林大学学报(医学版)

Objective:To observe the clinical effects of split post crown and split post-core crown in restoring the molars with low occlusogingival distance and large root furcation,and to clarify its advantages and analyze its improvement methods.Methods:Forty-nine molars of twenty-nine patients,which had been completely treated with root canal therapy,were restored by split post crown or split post-core crown according to their wills.Split post crown was used in twenty-three cases,and split post core crown was applied in the other twenty-six cases.The clinical effects of the patients in two groups were observed after 12 and 24 months follow-up.The levels of MMP-8 in gingival crevicular fluid were checked and compared 12 months after restoration.Results:The restoration success rates of split post crown were 95.7％ after 12-month treatment and 82.6 ％ after 24-month treatment,respectively;there was no significant difference between them (P＞ 0.05).The success rates of split post-core crown were 84.6％ after 12-month treatment and 52.2％ after 24-month treatment,respectively;there was significant difference between them (P＜0.05).The success rate of split post crown was significantly higher than that of split post-core crown after 24-month treatment (P＜0.05).The levels of MMP-8 in gingival crevicular fluid of the patients were close to each other,there was no statistical significance (P＞0.05).Conclusion;The split post crown shows better clinical effect in restoring the molars with low occlusogingival distance in 24 months than split postcore crown.Targeted improvement will help to improve the clinical success rate.

Evaluation on clinical effect of cast pure titanium split post crown restoration of molars with low occlusogingival distance and large root furcation / 吉林大学学报(医学版)

Objective:To observe the clinical effects of split post crown and split post-core crown in restoring the molars with low occlusogingival distance and large root furcation,and to clarify its advantages and analyze its improvement methods.Methods:Forty-nine molars of twenty-nine patients,which had been completely treated with root canal therapy,were restored by split post crown or split post-core crown according to their wills.Split post crown was used in twenty-three cases,and split post core crown was applied in the other twenty-six cases.The clinical effects of the patients in two groups were observed after 12 and 24 months follow-up.The levels of MMP-8 in gingival crevicular fluid were checked and compared 12 months after restoration.Results:The restoration success rates of split post crown were 95.7％ after 12-month treatment and 82.6 ％ after 24-month treatment,respectively;there was no significant difference between them (P＞ 0.05).The success rates of split post-core crown were 84.6％ after 12-month treatment and 52.2％ after 24-month treatment,respectively;there was significant difference between them (P＜0.05).The success rate of split post crown was significantly higher than that of split post-core crown after 24-month treatment (P＜0.05).The levels of MMP-8 in gingival crevicular fluid of the patients were close to each other,there was no statistical significance (P＞0.05).Conclusion;The split post crown shows better clinical effect in restoring the molars with low occlusogingival distance in 24 months than split postcore crown.Targeted improvement will help to improve the clinical success rate.

Technique to repair iatrogenically-damaged roots during post canal preparation using resin composite and optic fibre posts

During post crown restoration, the preparation of the post canal can be fraught with difficulties resulting in widening, gouging and transportation of the post canal; sometimes with near root perforation. A technique is described to repair such iatrogenically damaged internal root canal walls using reinforcing resin composite and optic glass fibre posts. The root dentine, resin composite and glass fibres, having similar moduli of elasticity, will result in a repaired root with a ‘monolithic’ structure and possessing numerous desirable characteristics. This repair technique can easily be carried out in one sitting at the chairside thereby allowing the continued serviceability of the iatrogenically compromised root-filled tooth.

The application of the post crowns with wings to the restoration of the subgingival residual roots and residual crowns of anterior maxillary teeth / 医学研究生学报

Objective:To presents a new way of constructing post crowns for the anterior maxillary teeth which had the subginginval crown fracture more than 3 mm.To discusse the difficulties in the restoration of the subgingival residual roots and residual crowns of anterior maxillary teeth,and to explore the principles of the new restoration by the casting post-core and the porcelain fused mental crowns with wings. Methods: 23 patients(26 teeth) which had crown fracture more than 3 mm under the gingival were enrolled in this study.After those residual roots and crowns were endodontically treated following the conventional root canal therapy,the casting post-core and the porcelain fused mental crowns with wings were applied to reconstructing those missing crowns. Results: After 3 months to 5 years clinic observation,restored crowns were still stable with good retention and fracture resistance. Conclusion: Those residual roots and crowns can be preserved by this innovative way and can also acquire satisfactory effects in esthetics and functions.