The purpose of this study is to compare and evaluate the influence of two different cement space settings and two different cement types on the stress distribution under occlusal surfaces of tooth ...restored with two different types of crowns and studied by using three-dimensional (3D) finite element analysis (FEA).
Eight 3D finite element models (FEMs) representing a mandibular first molar tooth restored with crowns of, porcelain-fused-to-metal (PFM) and porcelain-fused-to-zirconia (PFZ) crowns with two cement space settings (50 and 80 µm) and with two different types of cement were constructed, using an FEA software (ANSYS, version 10). Each model was subjected to a distributed load simulating normal masticatory bite force of 225 N and was applied axial direction. Also, von Mises stress of each individual part in the system of models was calculated.
The PFM crowns undergo less stress distribution than the PFZ crowns. The PFM crowns are more compatible with self-adhesive cements, and the PFZ crowns are more compatible with resin-modified glass ionomer cements.
The PFM crowns with G-Cem Link Ace with 50 µm and PFZ crowns with RelyX Luting Plus with 80 µm combinations displayed less amount of stress distribution under normal masticatory bite force.
Self-adhesive resin cements with PFM crowns and PFZ with resin-modified glass ionomer cements show more benefits in stress distribution under occlusal surfaces under normal masticatory bite force.
Objectives: To assess the biological and technical complication rates of single crowns on vital teeth (SC‐V), endodontically treated teeth without post and core (SC‐E), with a cast post and core ...(SC‐PC) and on implants (SC‐I).
Material and methods: From 392 patients with chronic periodontitis treated and documented by graduate students during the period from 1978 to 2002, 199 were reexamined during 2005 for this retrospective cohort study, and 64 of these patients were treated with SCs. Statistical analysis included Kaplan–Meier survival functions and event rates per 100 years of object‐time. Poisson regression was used to compare the four groups of crowns with respect to the incidence rate ratio of failures, and failures and complications combined over 10 years and the entire observation period.
Results: Forty‐one (64%) female and 23 (36%) male patients participated in the reexamination. At the time of seating the crowns, the mean patient age was 46.8 (range 24–66.3) years. One hundred and sixty‐eight single unit crowns were incorporated. Their mean follow‐up time was 11.8 (range 0.8–26.4) years. During the time of observation, 22 biological and 11 technical complications occurred; 19 SC were lost. The chance for SC‐V (56) to remain free of any failure or complication was 89.3% (95% confidence interval CI 76.1–95.4) after 10 years, 85.8% (95% CI 66–94.5) for SC‐E (34), 75.9% for SC‐PC (39), (95% CI 58.8–86.7) and 66.2% (95% CI 45.1–80.7) for SC‐I (39). Over 10 years, 95% of SC‐I remained free of failure and demonstrated a cumulative incidence of failure or complication of 34%. Compared with SC‐E, SC‐I were 3.5 times more likely to yield failures or complications and SC‐PC failed 1.7 times more frequently than did SC‐E. SC‐V had the lowest rate of failures or complications over the 10 years.
Conclusions: While SCs on vital teeth have the best prognosis, those on endodontically treated teeth have a slightly poorer prognosis over 10 years. Crowns on teeth with post and cores and implant‐supported SCs displayed the highest incidence of failures and complications.
To cite this article: Schmidlin K, Schnell N, Steiner S, Salvi GE, Pjetursson B, Matuliene G, Zwahlen M, Brägger U, Lang NP. Complication and failure rates in patients treated for chronic periodontitis and restored with single crowns on teeth and/or implants Clin. Oral Impl. Res. 21, 2010; 550–557. doi: 10.1111/j.1600‐0501.2009.01907.x
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BFBNIB, CMK, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Aim
The aim of this prospective cohort study was to evaluate clinical, radiographic, technical, esthetic, and patient‐centered outcomes of implants using two different restoration materials after ...5–9 years.
Materials and Methods
The study included 28 patients (test group: 13 patients with all‐ceramic crowns on aluminum oxide‐based abutments; control group: 15 patients with metal abutments on porcelain‐fused‐to‐metal crowns). Evaluation of patient satisfaction, clinical (periodontal probing depth, bleeding on probing, plaque index, mucosal recession, and width of keratinized mucosa), esthetical (papilla index, clinical crown length), technical (loss of retention, marginal adaptation, chipping of ceramic, anatomical shape, occlusal wear, color match), and radiological parameters were assessed. The statistical analyses included comparison of all‐ceramic vs. metal abutments and between the groups using Mann–Whitney U‐tests. For esthetic parameters, changes over time were assessed using Friedman test and post hoc Wilcoxon test of all complete cases.
Results
The survival rate of the restoration was 100% in both groups. Patient's satisfaction revealed 9.7 on the visual analog scale. A low satisfaction correlated with low ratings in color or anatomical shape. The mucosal recession in the test group was less than that in the control group. An increase in distal papilla height in the year 0 to 1, and a decrease from year 1 to 8, was detected. Sites, which received a soft tissue graft, revealed stable papillae over the observation period. Clinical crown length showed higher values in the control group.
Conclusions
Within the limitations of the study, it can be concluded that all‐ceramic restorations reveal a high survival rate of 100% and show no difference to metal after a mean observation period of 7.2 years.
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BFBNIB, CMK, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The work is part of the research “The dental health restore in patients with common dental diseases and their rehabilitation”. 0116U004191. Galvanosis is a disease caused by the action of galvanic ...currents, which are initiated due to the occurrence of electrochemical processes in the oral cavity between metal dental restorations. The development of galvanosis phenomena is accompanied by the increasing of electric potentials difference, current strength, electric conductivity of oral liquid. Moreover, intra-oral reactions, oral and gingival lichenoid reactions, and some instances of systemic reactions of intolerance to metal alloys is observed. The aim of the study was to improve the prosthodontic methods of prevention and treatment of galvanosis by creating the design of porcelain-fused-to-metal crown. Patients with galvanosis have a high level of complaints, which is characterized by a bright intra-oral reactions (such as redness, swelling, and pain of the oral mucosa and lips), high quantitative indicators of subjective symptoms 42 + 2.53 points per patient, high potential difference and low saliva pH of the oral cavity. After removal of metal prosthodontic constructions in patients there is a significant reduction of the symptoms of galvanosis (subjective symptoms of 4.22 + 1.49 points), reducing the potential difference and increasing the saliva pH of the oral cavity. The use of our treatment method of and the galvanosis management due to porcelain-fused-to-metal crown has led to almost complete reduction of galvanosis symptoms, normalization of biopotentials and saliva pH of the oral cavity. The offered design of porcelain-fused-to-metal crown for the prevention of galvanosis is consisted of a solid metal frame with the application of a facing ceramic layer. The edge of the crown metal framework is made distant from the edge of the ledge by 1-1.5 mm. The crown facing ceramic layer is made at the edge of the metal framework on the width of the ledge and completely replace the metal in the ledge, in this way isolating the metal frame from contact with oral fluid. So, occurrence of galvanic currents and in general the phenomenon of galvanosis has eliminated. This offered design of the metal-ceramic crown for the prevention of galvanosis can completely isolate the metal frame from contact with oral fluid, prevents the occurrence of galvanic currents, and, as a result, increases the prosthetics efficiency. The offered design of porcelain-fused-to-metal crown for the prevention of galvanosis can be applied in different dentition areas of the lower and upper jaws. So, the widespread use of this treatment method to prevent adverse reactions of oral mucosa due to galvanosis in clinical practice.
Purpose: The purpose of this study was to investigate the influence of inner crown thickness on the bonding strength of porcelain fused to Co-Cr alloy endocrown by shear strength test.Methods: ...According to the molar average anatomical data to obtain a simplified model for endocrowns, porcelain fused to Co-Cr alloy endocrowns were fabricated with four inner crown thicknesses: 0.3 mm, 0.5 mm, 0.8 mm, and 1.0 mm group, eight specimens were fabricated for each thickness group. Shear bond strength test was used to observe the metal-porcelain bonding strength, scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) analysis were performed after the test to evaluate the interface of metal-porcelain.Results: The shear bond strength means (in MPa) were: 10.50 ± 2.55 (0.3 mm), 13.21 ± 2.27 (0.5 mm), 14.47 ± 1.46 (0.8 mm), and 15.78 ± 2.81 (1.0 mm), one-way ANOVA showed that there was a statistically significant difference among the thicknesses (P < 0.05). The SEM observation showed tight bonding, and the EDS analysis showed element diffusion phenomenon at the metal-porcelain interface.Conclusion: The bonding strength of porcelain fused to Co-Cr alloy endocrown varied according to the different thickness of inner crown and the thinner inner crown was recommended for tooth defects with limited prosthodontic space.
Palladium-silver (Pd–Ag) alloys are important as an alternative to gold-based alloys. The purpose of this study was to investigate the effect of an argon-arc vacuum pressure casting process on the ...recasting of the Pd–Ag alloy.
The recasting Pd–Ag alloys were compared with conventional horizontal centrifugal (HC) casting to an argon (Ar)-arc vacuum pressure (Ar-arc/VP) casting. The first-generation castings were made from a Pd–Ag alloy purchased from a supplier. Next-generation castings were made from 50 wt% Pd–Ag alloy before casting and 50 wt% from previous castings. This sequence was repeated over three generations to form the 2nd, 3rd and 4th recasting ingots. The ingots were then measured for marginal accuracy, interfacial oxidation, hardness and phase identification.
The recasting success rate of recastibility reached 100%. Compared with the HC group, the Ar-arc/VP group had better edge precision, smaller oxide layer thickness and lower hardness. The comparison of X-ray diffraction intensity showed that the relative intensities of Pd and Ag in the first, second and third generations recasting of the Ar-arc/VP group were significantly higher than those of the HC group. Phase analysis showed that the trace elements of indium and tin contents in the Pd–Ag recasting ingots of the Ar-arc/VP group were higher than those of the HC group.
The results showed that the casting process used for recasting affected the quality of the Pd–Ag alloy. Therefore, Ar-arc/VP casting process could improve the effect of Pd–Ag recasting and maintain the alloy properties in comparison with HC casting.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Purpose: The purpose of this study was to investigate the influence of inner crown thickness on the bonding strength of porcelain fused to Co-Cr alloy endocrown by shear strength test.Methods: ...According to the molar average anatomical data to obtain a simplified model for endocrowns, porcelain fused to Co-Cr alloy endocrowns were fabricated with four inner crown thicknesses: 0.3 mm, 0.5 mm, 0.8 mm, and 1.0 mm group, eight specimens were fabricated for each thickness group. Shear bond strength test was used to observe the metal-porcelain bonding strength, scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) analysis were performed after the test to evaluate the interface of metal-porcelain.Results: The shear bond strength means (in MPa) were: 10.50 ± 2.55 (0.3 mm), 13.21 ± 2.27 (0.5 mm), 14.47 ± 1.46 (0.8 mm), and 15.78 ± 2.81 (1.0 mm), one-way ANOVA showed that there was a statistically significant difference among the thicknesses (P < 0.05). The SEM observation showed tight bonding, and the EDS analysis showed element diffusion phenomenon at the metal-porcelain interface.Conclusion: The bonding strength of porcelain fused to Co-Cr alloy endocrown varied according to the different thickness of inner crown and the thinner inner crown was recommended for tooth defects with limited prosthodontic space.
Introduction: A near-ideal preparation lays the foundation and is required for adequate retention and resistance for fixed partial dentures. It is advisable to achieve a near-ideal preparation for ...the longevity of the prosthesis. Materials and Methods: Thirty maxillary left central incisors were mounted on the acrylic block. The samples were divided into groups with ten specimens: Group A-Free hand, Group B-Index, and Group C-Depth gauge. Group A was prepared using the freehand method, Group B was prepared using the putty index, and Group C was prepared using depth gauge bur. An index was prepared before and placed back on the tooth after preparation, and the gap was filled with low-viscosity elastomer. The thickness of the impression was measured at five different points under the microscope. The statistical analysis was done using one-way analysis of variance and Student's t-tests. Results: The preparations (dimensions) achieved by the freehand method were 2.02 mm, 1.70 mm, 1.11 mm, 0.90 mm, and 0.60 mm respectively at five predetermined points. Similarly, for putty index these were 1.76 mm, 1.21 mm, 0.95 mm, 1.32 mm, 0.71 mm respectively at five predetermined points. Likewise, with depth gauge bur it were 1.88 mm, 1.35 mm, 0.77 mm, 1.09 mm, 0.73 mm, respectively, at five predetermined points. There was a significant difference between the Groups (P < 0.001). Intergroup comparisons between Group A, Group B and Group C showed a significant difference. Group A showed near-ideal preparation in the palatal cervical region compared to Group B and Group C. Conclusion: The freehand technique was the least effective of the three techniques. The use of depth gauge bur had yielded the preparation near the ideal and should be considered during tooth preparation.
Background: The failure of endodontic treatment caused by failure of the restoration and bacterial invation. Alongside proper chemical and mechanical preparation and hermetic obturation of the root ...canal system, another essential factor is ensuring a permanent and hermetically-sealed restoration following endodontic treatment. Endodontic retreatment encompasses the efforts to salvage a failing previously endodontically treated tooth. As a result of advances in endodontic materials and adhesive systems, restorations in the form of fiber post and adhesively cemented crown are becoming a choice in cases of teeth that have extensive damage. Case: A case is presented a 45-year-old female was referred to Prof. Soedomo Dental Hospital with a complaint of pain in mandibular second premolar which was earlier endodontically treated. Clinical and radiographic examinations showed damaged restorations, gutta percha filling that are not hermetic and radiolucent on periapical. A successful endodontic retreatment premolar using rotary retreatment file and preparation with crown down technique using rotary progressive multiple tapering file, with comprehensive endo-prosthetic treatment using prefabricated fiber post and porcelain fused to metal crown. Conclusion: Clinical and radiographic evaluation after 6 months showed complete healing and good adaptation of the restoration. The outcomes of this case showed that failure of endodontic retreatment respond favorably to endodontic retreatment, with proper indication, prefabricated fiber post and porcelain fused to metal crown can provide an effective conservative and esthetic option for reinforcing endodontically treated teeth.
Background: Full-coverage porcelain fused to metal crowns is commonly recommended for restoration of extensively damaged teeth. Ability of the dentist to adequately prepare teeth is fundamental to ...success and longevity of these restorations. Aims: This study was designed to compare recommended convergence angle and taper values of tooth preparation with clinically practiced values and to assess the factors such as tooth position, operator experience, vitality, and restorative status on convergence angle of prepared teeth. Setting and Design: It was a descriptive, cross-sectional study design and held at The Aga Khan University Hospital, Dental Section, for a period of 1 year. Materials and Methods: A minimum of 197 crown preparation models of molar and premolar teeth prepared by residents and specialists were collected in order to achieve the objectives of the study on the basis of convenient sampling technique. Statistical Analysis: One sample t-test used to compare the mean practiced convergence angle values with its recommended values. Independent sample t-test and one-way ANOVA was used to see difference in the convergence angle values of the teeth prepared by different operators, tooth type, vitality status, and restorative status of teeth. Results: Mean reported convergence angle and axial wall taper values were 23.7+-8.9 and 11.3+-7.8, respectively, which is significantly greater (P<0.001) than the recommended values. Convergence angle values were greater for molars as compared to premolars. Conclusion: There was a considerable disparity between the convergent angles values recorded in this study and the recommended guidelines and are affected by tooth type, vitality, and restorative status of tooth.
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