An engineering perspective of ceramics applied in dental reconstructions

Abstract The demands for dental materials continue to grow, driven by the desire to reach a better performance than currently achieved by the available materials. In the dental restorative ceramic field, the structures evolved from the metal-ceramic systems to highly translucent multilayered zirconia, aiming not only for tailored mechanical properties but also for the aesthetics to mimic natural teeth. Ceramics are widely used in prosthetic dentistry due to their attractive clinical properties, including high strength, biocompatibility, chemical stability, and a good combination of optical properties. Metal-ceramics type has always been the golden standard of dental reconstruction. However, this system lacks aesthetic aspects. For this reason, efforts are made to develop materials that met both the mechanical features necessary for the safe performance of the restoration as well as the aesthetic aspects, aiming for a beautiful smile. In this field, glass and high-strength core ceramics have been highly investigated for applications in dental restoration due to their excellent combination of mechanical properties and translucency. However, since these are recent materials when compared with the metal-ceramic system, many studies are still required to guarantee the quality and longevity of these systems. Therefore, a background on available dental materials properties is a starting point to provoke a discussion on the development of potential alternatives to rehabilitate lost hard and soft tissue structures with ceramic-based tooth and implant-supported reconstructions. This review aims to bring the most recent materials research of the two major categories of ceramic restorations: ceramic-metal system and all-ceramic restorations. The practical aspects are herein presented regarding the evolution and development of materials, technologies applications, strength, color, and aesthetics. A trend was observed to use high-strength core ceramics type due to their ability to be manufactured by CAD/CAM technology. In addition, the impacts of COVID-19 on the market of dental restorative ceramics are presented.

Research progress on the application of Er: YAG laser removing all-ceramic restorations / 口腔疾病防治

@#All-ceramic restorations are widely used in oral restoration because of their beauty and high strength. Glass ceramics and zirconia all-ceramic materials are the two most widely used all-ceramic materials in the clinic. However, when all-ceramic restorations need to be removed due to marginal microleakage and secondary caries, its high strength and high bonding strength greatly increase the difficulty of removal. In recent years, clinicians have tried to use Er: YAG lasers to remove all-ceramic restorations. The Er: YAG laser can be safely and efficiently applied to the removal of glass restorations, and it can also play a role in thinner zirconia restorations. Various factors, such as the material and thickness of the all-ceramic restoration, the type of cement, and the laser power, can affect the speed of removal of the Er: YAG laser. However, the current research is limited to case reports and in vitro studies, lacking systematic clinical research. The specific mechanism of Er: YAG laser removal of all-ceramic restorations and the influence of laser frequency, adhesive type, and abutment on the removal speed need to be further demonstrated by follow-up research.

Evaluation of fracture strength of two kinds of zirconia all-ceramic crowns with different edge compensation angles / 北京大学学报(医学版)

OBJECTIVE@#To evaluate the effects of different edge compensation angles on the fracture strength of multilayer zirconia all-ceramic crowns and traditional uniform zirconia all-ceramic crowns.@*METHODS@#The resin tooth preparation specimen of the mandibular first molar with a knife-edge was fabricated. A 3D digital model of the specimen was obtained by scanning it with a 3D dental model scanner. The 3D digital model was imported into computer aided design (CAD) software, and three 3D digital models of the full crown with the same surface shape are designed with the edge compensation angles of 30°, 45° and 60°, respectively. Then, the designed 3D digital model is imported into computer aided manufacturing (CAM) software. Three kinds of multilayer and homogeneous zirconia all-porcelain crowns with different edge compensation angles were fabricated, 10 each for a total of 60. The fracture load of each crown was measured under the electronic universal testing machine.@*RESULTS@#Fracture load of multilayer and uniform zirconia all-ceramic crowns, (4 322.86±610.07) N and (5 914.12±596.80) N in the 30° group, (5 264.82±883.76) N and (5 220.83±563.38) N in the 45° group and (4 900.42±345.41) N and (5 050.22±560.24) N in the 60° group, respectively. The fracture load of multi-layer zirconia all-ceramic crowns in the 30° group was significantly lower than that of homogeneous zirconia all-ceramic crowns(P < 0.05); there was no statistical significance in 45° group and 60° group(P>0.05). In the multi-layer zirconia all-ceramic crowns: the fracture load of the 30° group was significantly lower than that of the 45° group (P < 0.05); there was no significant difference between the 30° group and the 60° group, the 45° group and the 60° group (P>0.05).In uniform zirconia full crown group: the 30° group was higher than the 45° group, the 30° group was higher than the 60° group (P < 0.05), and there was no significant difference between the 45° group and the 60° group (P>0.05).@*CONCLUSION@#The fracture loads of three kinds of uniform and multilayer zirconia all ceramic crowns with different edge compensation angles can meet the clinical requirements. A smaller edge compensation angle is recommended when using traditional zirconia all-ceramic crowns, while 45° is recommended when using multi-layer zirconia all-ceramic crowns.

Influence of CAD/CAM Material and Preparation Design on the Long-term Fracture Resistance of Endocrowns Restoring Maxillary Premolars / Influência do material de CAD / CAM e tipo de preparo na resistência à fratura a longo prazo de coroas endodônticas adesivas na restauração de pré-molares superiores

Objective: To evaluate the effect of different occlusal preparation designs and CAD/CAM materials on the fracture resistance of maxillary premolars end crowns. Materials and Methods: sixty-four endodontically treated upper first premolars were randomly divided into four groups according to ceramic materials (Vita Enamic and IPS emax CAD) and occlusal preparation designs (Anatomical and horizontal butt joint). After teeth preparation, the restorations were all made by CAD/CAM system (Cerec MCXL). Half of each group had undergone cyclic fatigue testing of 105 cycles with 50N loading force at a frequency of 0.5Hz in a mechatronic chewing simulator machine, and then all samples were loaded to fracture using a universal testing machine with a cross head speed of 0.5 mm/min recording the fracture resistance values in N . The specimens were measured and statistically analyzed using using three-way analyses of variance (ANOVA), followed by serial two-way and one-way ANOVAs at each level of the study. P-values were adjusted for multiple comparisons using BENFORRONI correction and the significance level was set at P ≤ 0.05 for all tests. Results: Vita Enamic endocrowns showed higher fracture resistance values than IPS e max specimens. Conclusions: Vita Enamic endocrowns with anatomical preparations were found to be more favourable restoring endodontically treated maxillary premolars (AU)

Objetivo: Avaliar o efeito de diferentes tipos de preparo oclusal e materiais CAD/CAM na resistência à fratura de coroas endodônticas adesivas em pré-molares. Materiais e Métodos: Sessenta e quatro primeiros pré-molares superiores tratados endodonticamente foram divididos randomicamente em quatro grupos de acordo com os materiais cerâmicos (Vita Enamic e IPS emax CAD) e tipos de preparo oclusal (Recobrimento Incisal Anatômico e Horizontal). Após o preparo dental, as restaurações foram confeccionadas pelo sistema CAD/CAM (Cerec MCXL). Metade de cada grupo foi submetido a testes de fadiga cíclica de 105 ciclos com força de carga de 50N a uma frequência de 0,5Hz em uma máquina simuladora de mastigação mecatrônica, e então todas as amostras foram submetidas a fratura por uma máquina de teste universal com uma velocidade de 0,5 mm / min registrando os valores de resistência à fratura em N. As amostras foram medidas e analisadas estatisticamente usando análises de variância de três fatores (ANOVA), seguidas por ANOVAs de dois fatores e de um fator em cada nível do estudo. Os valores de p foram ajustados para comparações múltiplas usando a correção BENFORRONI e o nível de significância estabelecido foi de P ≤ 0,05 para todos os testes. Resultados: Coroas endodônticas adesivas da Vita Enamic mostraram maiores valores de resistência à fratura do que as amostras de IPS emax. Conclusões: Verificou-se que as coroas endodônticas adesivas da Vita Enamic com preparos com recobrimento incisal anatômico foram mais favoráveis para restaurar os pré-molares superiores tratados endodonticamente (AU)

Fracture load of nano-ceramic composite material for anterior endocrown restorations / Carga de fratura de material compósito nano-cerâmico para restaurações endocrown anteriores

Objective: to evaluate ability of Nano Ceramic Composite endocrown to withstand occlusal forces when used in the anterior region. Material and Methods: eighty endodontically treated maxillary central incisors teeth were randomly divided into two main groups according to the restoration type. Forty of these teeth were post, core and crown restorations and 40 were endocrown restorations. Then they were divided by halves into two subgroups according to the material used 20 were made with Lava Ultimate and the other 20 with IPS e.max. Each subgroup was then further subdivided into two divisions according to the remaining tooth structure above the CEJ (n = 10): 2 mm and 0.5 mm above the CEJ. After teeth preparation, the restorations were all made by CAD/CAM system (Cerec MCXL). All samples had undergone cyclic fatigue testing, and then loaded to fracture using a universal testing machine. The specimens were measured and statistically analyzed using Mann-Whitney test for comparing the mean changes between the groups. Results: Lava Ultimate showed higher mean fracture load values than IPS e.max specimens. Conclusions: endocrowns were found to be more favorable when used on endodontically treated teeth than the conventional post, core and crown restorations.(AU)

Objetivo: Avaliar a capacidade do compósito nanocerâmico endocrown para suportar forças oclusais quando usado na região anterior. Material e Métodos: Oitenta incisivos centrais superiores tratados endodonticamente foram divididos aleatoriamente em dois grupos principais, de acordo com o tipo de restauração. Quarenta desses dentes receberam restaurações com retentor intrarradicular, núcleo e coroa e 40 receberam restaurações endocrown. Em seguida, foram divididos pela metade em dois subgrupos, de acordo com o material utilizado, sendo 20 confeccionados com Lava Ultimate e os demais 20 com IPS e.max. Cada subgrupo foi posteriormente subdividido em dois, de acordo com a estrutura dentária remanescente acima da JEC (n = 10): 2 mm e 0,5 mm acima do JEC. Após o preparo dos dentes, todas as restaurações foram realizadas pelo sistema CAD/ CAM (Cerec MCXL). Todas as amostras foram submetidas a testes de fadiga cíclica e submetidas ao esforço até a fratura em uma máquina universal de testes. As amostras foram medidas e analisadas estatisticamente pelo teste de MannWhitney para comparação das alterações médias entre os grupos. Resultados: lava Ultimate apresentaram valores médios mais altos de carga até a fratura do que as amostras IPS e.max. Conclusões: as endocrowns mostraram-se mais favoráveis quando utilizadas em dentes tratados endodonticamente do que as restaurações convencionais com retentor intrarradicular, núcleo e coroa.(AU)

Application of single-retainer all-ceramic resin-bonded fixed partial denture in the maintenance of missing incisor gap after orthodontic treatment in adolescents: a case report / 华西口腔医学杂志

This article reports a case of an orthodontic adolescent patient without a right inferior incisor. The right lower canine was used as the abutment. The single-retainer all-ceramic resin-bonded fixed partial denture was used to restore the complete dentition. Thus, the missing space was filled, and the function and aesthetics were restored.

Evaluation of the efficacy of CAD/CAM glass-ceramic onlays in molars with complicated oblique crown fracture / 口腔疾病防治

Objective@#To evaluate the clinical efficacy of CAD/CAM glass-ceramic onlays in molars with complicated oblique crown fracture within 3.0 mm subgingival. @*Methods@#Fifty-six molars from 56 patients with complicated oblique crown fracture within 3.0 mm subgingival were recruited after endodontic treatment and divided into 2 groups according to the restorative methods used. The glass-ceramic onlays group was restored with CAD/CAM glass-ceramic onlays, while the all-ceramic crown group received CAD/CAM all-ceramic crowns. The success rates of the restorations were analyzed, and the sulcus bleeding index (SBI), plaque index (PLI), and gingival index (GI) were recorded at the prerestoration and postrestoration stages. @*Results @#After one year of follow-up, the success rate of the glass-ceramic onlay group was 96.4%, and the success rate of the all-ceramic crown group was 92.9%. The difference was not statistically significant (P > 0.05). No differences in SBI, PLI, or GI were found between the glass-ceramic onlay group and the all-ceramic crown group (P > 0.05).@*Conclusion@#Conclusion

All-ceramic premolar guiding plate retains resin-bonded fixed partial dentures / 华西口腔医学杂志

OBJECTIVE@#This study aims to investigate the fracture resistance and short-term restorative effects of resin-bonded fixed partial dentures (RBFPDs) made from heat-pressed lithium-disilicate-based glass-ceramic (IPS e.max press) and zirconia ceramic (WIELAND) and retained by all-ceramic guiding plates when used to restore missing mandibular second premolars.@*METHODS@#A total of 64 human mandibular first premolars and first molars were prepared as abutments, then were randomly divided into 4 groups (n=8): E0, heat-pressed ceramic RBFPDs, no cyclic loading; E1, heat-pressed ceramic RBFPDs exposed to 300 000 cycles of dynamic loading; W0, zirconia ceramic RBFPDs, no cyclic loading; and W1, zirconia ceramic RBFPDs exposed to 300 000 cycles of dynamic loading. Fracture strength was tested in a universal testing machine.@*RESULTS@#The medians of fracture strength were 1 242.85 N±260.11 N (E0), 1 650.85 N±206.77 N (W0), 1 062.60 N±179.98 N (E1), and 1 167.61 N±265.50 N (W1). Statistical analysis showed that all the groups exhibited significantly higher fracture strength compared with the maximum bite force in the premolar region (360 N; P0.05). Significant statistical differences were found between the zirconia ceramic groups (W0 and W1, P0.05) after dynamic loading.@*CONCLUSIONS@#The RBFPDs retained by all-ceramic guiding plates exhibited promising fracture properties and optimal short-term restorative effects when used to restore missing mandibular second premolars.

Expert consensus on clinical application of all-ceramic esthetic restorative materials / 中华口腔医学杂志

All-ceramic materials have become the most commonly used dental esthetic restorative material in clinic due to their excellent esthetic and mechanical properties and biocompatibility. However, there are still many confusions about the clinical application of all-ceramic materials. Society of Esthetic Dentistry in conjunction with Society of Dental Material Science, Chinese Stomatological Association organized multidisciplinary experts in prosthodontics, dental materials, implantology and dental esthetics to develop a consensus on the clinical application of all-ceramic esthetic restorative materials. The expert consensus covers such aspects of all-ceramic materials as the classification, major properties, selection of clinical indications and treatment of bonding interfaces. It is hoped that the consensus may help the clinicians to make correct decisions in selecting adequate materials in all-ceramic restoration according to various specific cases in the clinic.

Effect observation of onlays on the posterior teeth with subgingival defects after deep margin elevation / 口腔疾病防治

Objective@#Objective To evaluate the effect of repairing posterior teeth with subgingival defects with onlays after deep margin elevation and to provide a reference for clinical application.@*Methods @#Eighty-six cases of posterior teeth with subgingival defects were treated with resin filling to elevate the subgingival margin to the superior gingival margin and were then restored with onlays of cast porcelain. Patients were followed up at 1 week, 6 months and 12 months. The wear and tear of the restorations, fractures of the restorations, loss of the restorations, marginal closeness, marginal staining, secondary caries and gingival health were examined. Assessment of efficacy with reference to American public health service standards was conducted.@*Results @#One week after the operation, there was no loss of follow-up. Eighty-six cases of onlays had no prosthetic wear, prosthetic fracture, prolapse of the prosthesis, edge adhesion, edge coloration, secondary caries, etc., and the gums were healthy. At 6 months after surgery, 2 patients were lost to follow-up and 4 of the remaining 84 onlays were detached. After re-adhesion, there was no shedding. At 12 months after surgery, 5 cases were lost to follow-up and 81 cases of onlays demonstrated no further prosthetic wear, prosthetic fracture, prolapse of the prosthesis, edge adhesion, edge coloration, secondary caries, etc., and the gums were healthy. The success rate after 12 months of repair was 95.1% (77/81).Conclusion For posterior teeth with a subgingival defect, onlays of cast porcelain have the advantages of a high success rate, co@*Conclusion@# For posterior teeth with a subgingival defect, onlays of cast porcelain have the advantages of a high success rate, convenient clinical operation and no influence on periodontal health to restore posterior teeth after deep margin elevation.

Three-dimensional finite element analysis of cuspal-coverage thickness influence on the stress distribution of all-ceramic onlay-restored premolars / 华西口腔医学杂志

OBJECTIVE@#To investigate the influence of cuspal-coverage thickness on the stress distribution of all-ceramic onlay-restored premolars by using 3D finite element (FE) analysis and to provide references for the design of all-ceramic onlays for clinical application.@*METHODS@#3D FE models of all-ceramic onlays with three cuspal-coverage thicknesses (2, 3, and 4 mm) of endodontically treated maxillary premolar were constructed based on micro-CT images. Stress distributions in the onlay, adhesive resin cement layer, and dentin of models were analyzed under vertical load (600 N) and oblique load (200 N).@*RESULTS@#When the cuspal-coverage thickness increased, the peak maximum principal stress value decreased inside the onlay but increased in the margin of the adhesive resin cement layer. In addition, stress concentration areas increased in the coronal residual dentin on the palatal side under oblique load.@*CONCLUSIONS@#An increase in the cuspal-coverage thickness of all-ceramic onlays may reduce the risk of rupture of the restoration but may deteriorate the restoration and cause palatal dentin fracture.

Survival rate of modern all-ceramic FPDs during an observation period from 2011 to 2016

PURPOSE: In literature, many studies compare survival rates of different types of FPDs. Most of them compared restorations, which originated from one university, but from different clinicians. Data about restoration survival rates by only one experienced dentist are very rare. The aim of this study was to evaluate the survival rate of allceramic FPDs without the blurring effects of different clinicians. MATERIALS AND METHODS: 153 veneeredzirconia FPDs were observed for follow-up. 22 patients received 131 single crowns and 22 bridges. Because of the different bridge lengths, one unit was defined as a restored or replaced tooth. In total, 201 units were included. Only the restorations performed by the same clinician and produced in the same dental laboratory from 2011 to 2016 were included. Considered factors were defined as “type of unit”, “type of abutment”, “intraoral region”, and “vitality”. Modified UHPHS criteria were used for evaluation. Statistical analysis was performed using cox-regression. RESULTS: 189 units (94.0%) showed no kind of failure. 5 chippings (2.4%) could be corrected by intraoral polishing. 4 units (1.9%) exhibited spontaneous decementation. These polishable and recementable restorations are still in clinical use. Chippings or decementations, which lead to total failure, did not occur. One unit was completely fractured (0.5 %). Biological failures (caries, periodontitis or periimplantitis) did not occur. The statistical analysis of the factors did not reveal any significant differences. CONCLUSION: Modern all-ceramic FPDs seem to be an appropriate therapy not only for single restorations but for complex occlusal rehabilitations.

The functional and aesthetic reconstruction of tetracycline stained teeth with a virtual articulator in a CAD/CAM system / 口腔疾病防治

Objective@#To investigate the reliability of using virtual articulator in the fabrication of zirconia crowns for tetracycline discolored teeth.@*Methods@#To treat the patient with serious tetracycline stained teeth, we use zirconia crowns to shield the stained abutment teeth. To retain the characteristics of patient′s original occlusal contacts, meanwhile, to establish a stable and evenly distributed occlusal contacts, we recorded the functional movements of the patient′s jaw before preparing the teeth and transferred this relations to a physical articulator. Afterwards, relationship of the upper and lower arches was scanned through a specified fixature. Then we can customized the fabrication of the occlusal contacts of the restorations conveniently and efficiently with virtual articulator in CAD/CAM system.@*Results@#When the final restorations were inserted , a charming smile was achieved on patient′s face with satisfactory esthetics. With the application of virtual articulator in designing process, we made evenly distributed and stable bilateral occlusal contacting spots, smooth protrusive and lateral guidance on the lingual aspects of the upper anteriors. One year follow-up, this patient was observed in good oral hygiene, and was satisfied with her esthetic and functional outcome. The soft tissue around the restorations was assessed to be healthy and no signs of inflammation.@*Conclusion@# Applying the virtual articulator kits in CAD/CAM system in designing and fabricating the function-driven restorations could be an efficient way to obtain an satisfactory long-term outcome.

Numerical Study on Effects of Different Adhesive Materials for Ceramic Restoration on Stress Distributions / 医用生物力学

Objective To investigate the effect of different adhesive materials on all-ceramic restoration. Methods The all-ceramic restoration system model of mandibular first molar was established by spiral computed tomography (CT) scanning and computer-aided design (CAD) modeling. Four types of resin adhesive materials (Duo Cement,Lute-It,Rely-X ARC,Variolink II) used in clinics were selected, and the stress distribution was calculated using the ABAQUS software. Results The stress at the bonding interface was the highest when low filler adhesive Lute-It was used. Based on the viscoelasticity analysis, resin adhesives with a larger storage modulus and loss modulus could yield lower stress extremes. Conclusions The study suggests that high-filler type resin adhesives with a large energy storage modulus and loss modulus should be used clinically.

Application of single-retainer all-ceramic resin-bonded fixed partial denture in replacing single anterior tooth / 华西口腔医学杂志

Objective In this study, we aimed to evaluate the clinical effect of single-retainer all-ceramic resin-bonded fixed partial denture (RBFPD) on the single anterior tooth loss patients. Methods A total of 20 single-retainer all-ceramic RBFPD
were fabricated and evaluated in a two-year follow-up observation. The restorations were examined on the basis of the American Public Health Association (APHA) criteria. Results A total of 20 single-retainer all-ceramic RBFPD achieved class A evaluation after a six-month follow-up observation. One single-retainer all-ceramic RBFPD was classified as class B for secondary caries after a one-year follow-up observation. After a two-year follow-up observation, one single-retainer all-ceramic RBFPD was classified as class B because of secondary caries, and one single-retainer all-ceramic RBFPD was classified as class B because of fracture. Conclusion Single-retainer all-ceramic RBFPD is a promising and optional method in replacing single anterior tooth.

Influence of Convergence Angle and Cement Space on Margin and Internal Adaptation of CAD/CAM All-ceramic Crowns / 中国医科大学学报

Objective To study the influence of the convergence angle and cement space on the fit of CAD/CAM all-ceramic crowns.Methods The PMMA resin was produced in two groups,group A (2 degrees) and group B (4 degrees),30 in each group,and each group was divided into 3 sub-groups A 1,A2,A3;or B 1,B2,B3.Each subgroup included 10 patients with a CAD/CAM all-ceramic crown with PMMA resin generation type,but the cement space was 40 μm,60 μm,or 80 μm.The internal clearance edge of the double color silicone rubber impression reproduction technology of the all-ceramic crown was observed under the microscope.Analysis Micro-image software was used to measure the edge gap,and the resulting data were analyzed using SPSS 20.0 software.Results When the cement space is the same,the difference between 2 degrees and 4 degrees was statistically significant.Conclusion The fit is the best when the cement space is 60 μm and the convergence angle space is 4 degrees.

Comparison of the effects of polymer ceramic onlay and all ceramic crown in short crown molar / 口腔疾病防治

Objective @#To compare the clinical effects of polymer ceramic onlay and all ceramic crown in short crown molars@*Methods @# 45 cases of polymer ceramic onlay and 45 cases of Zirconium dioxide all ceramic crowns which repaired the short crowm molars after root canal therapy were compared clinically from the aspects of beauty of restoration, fracture and dislodgement, marginal adaptation and the preservation of abutment teeth. @*Results @# One polymer ceramic onlay had fall out form the teeth after half year, while the all ceramic crowns have been 8 cases after 6~12 months. There were significant differences in fracture and dislodgement between the two groups (χ2=4.44, P < 0.05). @*Conclusion @# Polymer ceramic onlay has good clinical effects in the restoration of short crown molars.

Clinical application of custom all-ceramic crown based on CT data in maxillary anterior implant tooth / 口腔疾病防治

Objective @#To evaluate the clinical outcomes of custom all-ceramic crown fabricated in zirconia based on CT data in maxillary anterior implant tooth. @*Methods@#15 patients with single anterior tooth missing were applied to this treatment. Crown remodeling according to the opposite tooth, fabrication of the all-ceramic crown was finished based on the data capture via CT scan. The observation period extended 2-7 years on average.@*Results@#The survival and success rates were 100%. Soft tissue was stabile in follow up photos. All of the patients were satisfied with the restorations. @*Conclusion @#The custom all-ceramic crown based on CT data showed good interface friendship with both of the hard and soft tissues and the aesthetics result is predictable.

Analysis of reasons for failure of chair-side CAD/CAM ceramic restorations / 口腔疾病防治

Objective@#To investigate the failure reasons of all-ceramic restorations fabricated with chair-side CAD-CAM technology (CEREC®) and to improve the clinical survival of all-ceramic restorations. @*Methods @#All-ceramic single-tooth restorations of CEREC® in stomatology hospital of Jiangsu province between 2013 and 2016 were summarized. By clinical examination and CEREC Biogeneric surveying, the failure reasons and related restoration types were evaluated. These results were analyzed with Chi-square test and Spearman correlation analysis. @*Results@#A total of 61 cases with restoration types of 11 inlays, 38 onlays, 2 endocrowns, and 11 all-crowns, resulted in a failure rate of 5.4% in all-ceramic single-tooth restorations in 1-4 years follow-up. The reasons for failure included ceramic fracture (n=33), debonding (n=13), tooth fracture (n=15), which attributed to thin ceramic thickness (n=27), acute line angle (n=6), insufficient enamel bulk (n=3), insufficient retention type (n=10), insufficient resistance type (n=15).@*Conclusion @# The most common reason for failure in CEREC® restorations was insufficient preparation space in occlusal surface.

Clinical effect of all-ceramic restorations and metal-ceramic restorations:A Meta-analysis / 实用口腔医学杂志

Objective:To evaluate the clinical outcome of all-ceramic and metal-ceramic restorations by means of Meta-analysis. Methods:The relevant randomized controlled trials ( RCTs) were electronically searched from PubMed, the Cochrane Library, EM-base, SinoMed, Weipu databases, CNKI and Wanfang. After data extraction and bias evaluation the Meta-analysis was conducted using RevMan 5. 3 software. Results:Finally 15 RCTs involving 768 all-ceramic restorations and 1386 Metal-ceramic restorations met the eli-gibility criteria. The results showed that, compared with metal-ceramic restorations, all-ceramic restorations could significantly decrease the risk of gingivitis(RR=0. 30,95%CI=0. 10-0. 90, P=0. 03),could decrease secondary caries and improve the satisfaction of cervical discoloration and marginal adaptation but without significant difference. There was no difference in color match and chipping of the veneering ceramics. However, all-ceramic restorations may lead to loss of the abutment tooth vitality. The risk of all-ceramic frame-work fracture while adopting fixed bridges was significantly higher(RR=6. 24, 95%CI=1. 20 -32. 41, P=0. 03). Conclusion:Based on the existing limited evidence,the efficacy of all-ceramic restorations is better than metal-ceramic restorations. But the intensity of all-ceramic bridges needs to be improved.