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@#As the main means of mastication, teeth can withstand countless functional contacts. The mechanical properties of teeth are closely related to their tissue structure. Enamel and dentin have a high hardness and modulus of elasticity, and their graded structure allows them to withstand bite forces without being susceptible to fracture. When tooth tissue is defective, full crown restoration is often needed to restore the normal shape and function of the tooth. Metal materials, ceramic materials, and polyetheretherketone (PEEK) materials are commonly used for crown restoration. Metal materials have certain disadvantages in terms of aesthetics and are relatively rarely used in clinical practice. Ceramic materials with different compositions exhibit differences in performance and aesthetics, but their elastic modulus and hardness are much higher than those of dental tissue, resulting in mismatching mechanical properties. In contrast, the elastic modulus of PEEK is lower than that of tooth tissue and similar to that of bone tissue, but its properties can be improved by fiber reinforcement. Notably, when the mechanical properties of a restoration material and tooth tissue are not fully matched, the interface between them often forms a potential weak link, which ultimately affects the stability and long-term effect of the restoration. This article introduces the mechanical properties and corresponding structural characteristics of enamel and dentin. On this basis, the advantages and limitations of existing restoration materials are analyzed, and the possibility of biomimetic design of full crowns is further explored.
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Post-and-core crown is one of the most common forms of restoration of tooth after root canal therapy (RCT). Infection control is the core objective of RCT, which is usually well realized by endodontists. However, many prosthodontists often neglect the infection control of the tooth and the maintenance of the curative effect of RCT during the process of post-and-core crown, which may lead to the failure of the final restoration. The concept of integrated crown-root treatment advocated recently requires clinicians to consider the RCT and final restoration as a whole, rather than simply divided into two parts-endodontic treatment and restorative treatment. As the core content of integrated crown-root treatment, infection control should be taken seriously by clinicians and implemented throughout the whole treatment process, especially in the restorative treatment that is easily overlooked after RCT. Therefore, this article describes the infection control of post-and-core crown restoration, classifies the tooth requiring post-and-core crown restoration, and puts forward the measures of infection control before and during post-and-core crown restoration, in order to provide reference and guidance for clinical practice.
Subject(s)
Humans , Crowns , Tooth Crown , Post and Core Technique , Root Canal Therapy , Infection Control , Tooth FracturesABSTRACT
Objective@# To investigate the adverse reactions of resin cement used for dentin bonding and its influencing factors.@*Methods@# Patients with dental defects treated with resin cement dentin adhesive for direct composite resin repair or full crown indirect repair were selected as the research objects. The occurrence and causes of adverse reactions, such as dental pulp lesions, soft tissue adverse reactions, and restoration loosening and falling off 7 days, 1 month, 3 months, 6 months, and 1 year after treatment, were analyzed retrospectively.@*Results @# Among the 14 776 teeth of 5 971 patients who used resin cement dentin adhesive, 580 cases (3.93%) had adverse reactions. Univariate analysis showed that the incidence of adverse events was highest in teeth with the "full crowns (fixed partial dentures)" restoration type at 7 days, 1 month, and 12 months after treatment. At 7 days after treatment, the incidence of adverse events was the highest in teeth with a preparation depth of "near pulp after preparation". At 7 days and 3 months after treatment, the incidence of adverse events was the highest in teeth with " dentin conditioner-adhesive-resin" treatment of the bonding surface. Multivariate analysis indicated that pulp perforation and pulp capping after tooth preparation were risk factors for adverse events 7 days after treatment (OR=2.610), and the “dentin primer-adhesive-resin” bonding surface treatment method was a protective factor for adverse events 7 days and 3 months after treatment (OR<1). @*Conclusion@#affect the occurrence of adverse events. pulp perforation, and pulp capping after tooth preparation, and self-etching bonding may contribute to adverse reactions.
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Objective@# To compare the stress distribution of different all-ceramic restoration materials and thicknesses in dental crown restorations using the finite element method and provide a reference for the selection and design of clinical crown restoration materials.@*Methods@#A finite element model of mandibular first molar implant crown restoration was created, and 6 crown thickness designs and 4 different crown restoration materials were evaluated, namely, resin-based ceramics (Lava Ultimate and Vita Enamic), lithium disilicate glass-ceramics (IPS e.max CAD), and zirconia ceramic (Cercon) designs. The mandibular first molars were loaded at 600 N, and the stress distribution was analyzed by using the finite element software ANSYS 10.0.@*Results@#The crown stress analysis showed that 156.05 MPa was the highest in 4 mm Cercon group and 18.85 MPa was the lowest in 1 mm Lava Ultimate group. The stress analysis of resin cement showed that 62.52 MPa was the highest in the 4 mm Lava Ultimate group and 16.74 MPa was the lowest in 1 mm IPS e.max CAD group. During the use of the finished platform, the stress concentration of the Lava Ultimate group in the crown prosthesis and resin cement was higher than that of the personalized platform with the same crown thickness.@*Conclusion@# With increasing crown thickness, the maximum principal stress concentration in crown restoration and resin cement increases. Personalized abutments are more conducive to reducing stress concentrations for resin-based ceramics.
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Objective:To investigate the curative effect of different restorations for deciduous teeth defect of children.Methods:67 children with teeth defecting seriously and being unable to fill restore were enrolled from January 2011 to January 2015 and randomly divided into three groups,one group of patients accepted metal crown restoration (Group A,n=22),one group adopted ceramic inlay restoration (Group B,n=22),and the last one accepted silver amalgam filling (Group C,n=23),the curative effect and incidence of adverse reactions among three groups in the period follow-up were compared.Results:In the period of 18-month follow-up,6 patients of toothache,5 patients of food impaction and crevices between restorations and teeth,3 cases of gingival congestion,2 cases of secondary caries were observed in group C;3 cases of toothache,1 case of food impaction,gingival congestion,crevices between restorations and teeth and secondary caries were observed in group B;2 cases of toothache and food impaction,1 case of gingival congestion were observed in group A.The incidence of adverse reactions in group A and group B was lower than those in group C (P＜0.05),which was lower in group A than that in group B,but no significant difference was found between group A and group B (P＞0.05).Conclusion:The restoration of metal crown and ceramic inlay deserved popularization had better curative effect and safety for deciduous teeth defect of children than silver amalgam filling.
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Objective To investigate the clinical effect of porcelain fused for metal crown restoration after root canal therapy.Methods Totally 90 patients with pulpitis or periapical periodontitis from December 2013 to December 2015 had their clinical data analyzed,who underwent root canal therapy and were divided equally into an observation group and a control group.The observation group took porcelain endocrowns repair and the control group applied ceramic crown.The two groups were compared on the restoration integrity,edge sealing,residual rate,gum,food impaction and color 3 months,6 months and 1 a after treatment.Results The observation group behaved significantly better than the control group in the edge sealing and restoration integrity (P＜0.05).There were significant differences between the residual rates,gum and food impaction in the two groups (P＜0.05).Conclusion Porcelain endocrowns repair gains advantages over ceramic crown repair in edge sealing,integrity,gum,food impaction and color after root canal therapy,though its long-term effect needs further investigation.
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Objective To investigate the clinical effect of porcelain fused for metal crown restoration after root canal therapy.Methods Totally 90 patients with pulpitis or periapical periodontitis from December 2013 to December 2015 had their clinical data analyzed,who underwent root canal therapy and were divided equally into an observation group and a control group.The observation group took porcelain endocrowns repair and the control group applied ceramic crown.The two groups were compared on the restoration integrity,edge sealing,residual rate,gum,food impaction and color 3 months,6 months and 1 a after treatment.Results The observation group behaved significantly better than the control group in the edge sealing and restoration integrity (P＜0.05).There were significant differences between the residual rates,gum and food impaction in the two groups (P＜0.05).Conclusion Porcelain endocrowns repair gains advantages over ceramic crown repair in edge sealing,integrity,gum,food impaction and color after root canal therapy,though its long-term effect needs further investigation.
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Objective:To observe the clinical effect of endodontic therapy and full crown restoration in the treatment of cracked teeth. Methods:The trace and depth of 50 cracked teeth were carefully examined under root canal microscope.According to the depth and scope of the cracks,the cracked teeth were classficated into the degree of Ⅰ,Ⅱ and Ⅲ,treated endodontically and restored with full crown.Results:During 1 year follow-up,34 cases showed successful effect,5 progressive,1 1 failure.The general effectiveness rate was 78.0%.The effectiveness rate of group Ⅰ,Ⅱ and Ⅲ was 93.3%,82.1 % and 28.6% respectively.Group Ⅰand Ⅱ vs Ⅲ,P 0.05.Conclusion:The treatment effect of cracked teeth is closely related to the depth and scope of cracks.
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Objective To compare the influence of resin core on overall bending strength of fiber post-core restoration.Methods 60 mandibular first premolar extracted because of orthodontic treatment was selected.3M light -cured composite resin P60,medental dual-cured resin,pulpdent dual-cured resin combined with viva carbon fiber reinforced glass fiber post were applied.The changes of teeth in vitro were observed when strength was given on.Results The flexural strength of 3M light-cured composite resin was (80.182 ±9.512)N,Medental dual-cured resin was (87.805 ± 11.649) N,Pulpdent dual-cured resin was (85.458 ± 10.845) N.The flexural strength of 3 M light-cured composite resin was lower than that of medental dual-cured resin and pulpdent dual-cured resin (t =5.758,3.084,both P ＜ 0.05).There was no statistical differences of flexural strength between medental dual-cured resin and pulpdent dual-cured resin(t =0.718,P ＞ 0.05).There was large area of resin broken off after 3M light-cured composite resin core fracture.There was only fracture of medental dual-cured resin core and pulpdent dual-cured resin core.Conclusion The bending strength of dual-cured resin is better than that of highly filled light curing composite resin in large tooth hard tissue defect restoration with fiber post-core,and core broken off is rare.Dual-cured resin is better post-core materials.
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0.05 ). And the fitness values(?m) of the crown of DA9-4 alloy were:the margin gap of the crown 71.3 ?8.34, the shoulder gap 53.4?4.83, the axial wall gap 41.85?8.08, the occlusal lift amount 55.2?9.21.Conclusion:DA9-4 alloy has good fitness and can meet the require of clinic.