Full Crown Restorations Research Articles

Microleakage and Marginal Gap of Adhesive Cements for Noble Alloy Full Cast Crowns

Very limited comparative information about the microleakage in noble alloy full cast crowns luted with different types of adhesive resin cements is available. The purpose of this study was to evaluate the microleakage and marginal gap of two self-adhesive resin cements with that of other types of adhesive luting cements for noble alloy full cast crowns. Fifty noncarious human premolars and molars were prepared in a standardized manner for full cast crown restorations. Crowns were made from a noble alloy using a standardized technique and randomly cemented with five cementing agents as follows: 1) GC Fuji Plus resin-modified glass ionomer cement, 2) Panavia F 2.0 resin cement, 3) Multilink Sprint self-adhesive resin cement, 4), Rely X Unicem self-adhesive resin cement with pretreatment, and 5) Rely X Unicem with no pretreatment. The specimens were stored in distilled water at 37°C for two weeks and then subjected to thermocycling. They were then placed in a silver nitrate solution, vertically cut in a mesiodistal direction and evaluated for microleakage and marginal gap using a stereomicroscope. Data were analyzed using a nonparametric Kruskal-Wallis test followed by Dunn multiple range test at a p<0.05 level of significance. The Rely X Unicem (with or with no pretreatment) exhibited the smallest degree of microleakage at both tooth-cement and cement-crown interfaces. The greatest amount of microleakage was found for Panavia F 2.0 resin cement followed by GC Fuji Plus at both interfaces. No statistically significant difference in the marginal gap values was found between the cementing agents evaluated (p>0.05). The self-adhesive resin cements provided a much better marginal seal for the noble alloy full cast crowns compared with the resin-modified glass ionomer or dual-cured resin-based cements.

Galvano- vs. metal-ceramic crowns: up to 5-year results of a randomised split-mouth study

Full-crown restorations made by galvano forming may be considered as highly biocompatible, stable and aesthetic restorations. Therefore, they represent an alternative to conventional metal-ceramic crowns (MC), which might be associated with an allergic or toxic reaction due to metal oxides. In current literature, there are few clinical reports available, but no comparative clinical evaluation of these two systems. Thus, the purpose of this clinical observation was to compare the long-term success of galvano-formed crowns (GC) and MC and to evaluate post-operative complications. The working hypothesis was that there was no difference in clinical success between crowns based on galvano-forming procedure or conventional metal-ceramic crowns. A prospective, randomised, double-blinded clinical trial was conducted. 48 GC and 48 MC were placed in 48 periodontal healthy patients (male = 24; female = 24) in a split-mouth design. Prosthetic parameters as technical, biological and endodontic problems were recorded. Restoration survival--MC vs. GC--was compared using a non-parametric Chi-square test by McNemar at 5% level of significance. The crown restorations were re-evaluated after an observation time of 13 to 64 months (mean = 40.5; SD = 11 months). 45 GC and 45 MC (94%) were in situ without any complications. No significant differences were found between GC and MC. Surface conditions differed only in part. Fractures of the veneering material were observed in one (2%) and two (4%) for MC and GC, respectively. The presented data indicate that GC appears to be a successful alternative to conventional MC systems.

Three-dimensional computer aided design for individualized post-and-core restoration

To develop a method of three-dimensional computer aided design (CAD) of post-and-core restoration. Two plaster casts with extracted natural teeth were used in this study. The extracted teeth were prepared and scanned using tomography method to obtain three-dimensional digitalized models. According to the basic rules of post-and-core design, posts, cores and cavity surfaces of the teeth were designed using the tools for processing point clouds, curves and surfaces on the forward engineering software of Tanglong prosthodontic system. Then three-dimensional figures of the final restorations were corrected according to the configurations of anterior teeth, premolars and molars respectively. Computer aided design of 14 post-and-core restorations were finished, and good fitness between the restoration and the three-dimensional digital models were obtained. Appropriate retention forms and enough spaces for the full crown restorations can be obtained through this method. The CAD of three-dimensional figures of the post-and-core restorations can fulfill clinical requirements. Therefore they can be used in computer-aided manufacture (CAM) of post-and-core restorations.

Influence of application site of provisional cement on the marginal adaptation of provisional crowns

Introduction: Marginal discrepancies may lead to cement washout and marginal leakage, damaging periodontal and pulp tissues or causing premature loss of the restoration. Purpose: This study evaluated the influence of application site of provisional cement on the marginal adaptation of provisional crowns. Material and Methods: Four different application sites of provisional cement (Temp Bond NE, Kerr Corporation) were used for cementation of provisional crowns on phantom teeth prepared for full crown restorations, performing 4 experimental groups (n=10): cement applied to all internal surfaces of the crown (CAO); cement applied to all internal surfaces of the crown, except for the occlusal surface (CA); cement applied to the cervical crown margin (CM); and cement applied to the cervical tooth margin (TM). A comparison microscope (Mitutoyo America Corporation) was used to measure the distances between the internal tangents of two circular marks, one made on the provisional crown and one made apical to the tooth preparation margin, in areas corresponding to buccal, lingual, mesial and distal surfaces. Marginal adaptation was determined before and after cementation, with 0.0001-mm accuracy. Data were analyzed statistically by ANOVA and Tukey's test at 5% significance level. Results: Mean values of marginal opening obtained for each group were: CAO: 145 μm; CA: 67 μm; CM: 46 μm; TM: 34 μm. CA, CM and TM presented significantly lower marginal openings than CAO (p<0.05). Conclusion: complete filling of the crown with provisional cement, including the occlusal surface, provided grater marginal discrepancies when compared to the other methods evaluated.

Erratum

It has been brought to our attention that there may be some confusion regarding a statement in the Summary section of our article, Crown Restoration of the Endodontically Treated Tooth: Literature Review ( J Vet Dent 2007 24: 9 – 12). Because there is virtually no published research detailing crown restoration in veterinary patients, a majority of the reviewed literature was human research. The first sentence of the Summary section should more accurately state: The reviewed literature supports full crown restoration in all endodontically treated teeth other than incisors in humans. Respectfully, Curt Coffman, DVM Louis Visser, DDS

Internal adaptation of cast titanium crowns.

As the adaptation of titanium crowns obtained by Rematitan Plus investment, specific for titanium, is not recognized to be suitable, this study evaluated the effect of the concentration of the specific liquid and the temperature of the mold of investments on the internal misfit of crowns cast on commercially pure titanium. Individual dies of epoxy resin were obtained, representing teeth prepared for full-crown restoration with a 6-degree axial surface convergence angle and shoulder (1.0 mm). For the waxing of each crown, a ring-shaped stainless steel matrix (8.0mm internal diameter; 7.5 mm height) was adapted above the individual dies of epoxy resin. The Rematian Plus investment was mixed according to the manufacturer's instructions using two different concentrations of the specific liquid: 100%, 75%. Casting was performed in a Discovery Plasma Ar-arc vacuum-pressure casting machine with molds at temperatures of 430°C, 515°C and 600°C. The crowns were cleaned individually in a solution (1% HF + 13% HNO3) for 10 min using a ultrasonic cleaner, with no internal adaptations, and luted with zinc phosphate cement under a 5 kg static load. The crown and die assemblies were embedded in resin and sectioned longitudinally. The area occupied by cement was observed using stereoscopic lens (10X) and measured by the Leica Qwin image analysis system (mm2). The data for each experimental condition (n=8) were analyzed by Kruskal-Wallis non-parametric test (á=0.05). The results showed that liquid dilution and the increase in mold temperature did not significantly influence the levels of internal fit of the cast titanium crowns. The lowest means (±SD) of internal misfit were obtained for the 430°C/100%: (7.25 mm2 ±1.59) and 600°C/100% (8.8 mm2 ±2.25) groups, which presented statistically similar levels of internal misfit.

Tooth Preparation and Impression for Full Metal Crown Restoration

Tooth Preparation and Impression for Full Metal Crown Restoration

Crown Restoration of the Endodontically Treated Tooth: Literature Review

The reviewed literature supports full crown restoration in all endodontically treated teeth other than incisors in humans [corrected] In general terms, a crown is a cemented, extra-coronal restoration that covers the entire outer surface of the clinical crown. Prosthodontic treatment, and particularly crown restoration in veterinary patients has been the subject of general informational articles and veterinary dental texts. These publications have discussed techniques for crown preparation, fabrication, and cementation as well as the general principles of prosthodontic treatment. The purpose of this review is to present available information on this topic in an organized manner which will help veterinary dentists to use an evidence-based approach when deciding on a type of final restoration for their endodontic patients.

When is a full-crown restoration indicated?

Full-crown restorations are commonly placed today, and the revenue produced from this procedure makes up a significant portion of a typical general dentist's income, as I have observed in the past. 1 Christensen GJ Ceramic vs. porcelain fused to metal crowns: give your patients a choice. JADA. 1994; 125: 311-314 PubMed Google Scholar , 2 Christensen GJ The confusing array of tooth-colored crowns. JADA. 2003; 134: 1253-1255 PubMed Google Scholar , 3 Christensen GJ Why all-ceramic crowns?. JADA. 1997; 128: 1453-1455 PubMed Google Scholar Practitioners may wonder if full crowns still are indicated, since there are so many resin-based composite materials that rival tooth structure in physical properties. Properly placed resin-based composite restorations are indeed beautiful and can serve for many years. However, placing large, resin-based composite restorations is difficult and time-consuming, which explains their lower rate of acceptance among practitioners. My feeling is that placement of full-crown restorations still is one of the most accepted procedures in restorative dentistry.

Development of a novel articulator that reproduced jaw movement with six-degree-of-freedom

A novel robotic articulator that reproduced a six-degree-of-freedom jaw movement was developed and tested. A precise six-axis micro-positioning stage was employed for this articulator. A high-resolution jaw-tracking device measured the functional jaw movement of the patient and a six-axis micro-positioning stage reproduced recorded jaw movement data. A full veneer crown restoration was fabricated with this articulator system. A working cast was mounted on the positioning stage of the articulator. An occlusal table with soft wax was attached on the cast tooth die, and the jaw movements were reproduced to create a functionally generated path on the occlusal table. The finished occlusal record was used to obtain the wax pattern for the crown. In this subject, no intra-oral occlusal adjustment was necessary for setting the finished full veneer crown. Since this articulator could perform a precise reproduction of the dynamic jaw motion during the functional jaw movement, this system has potential to improve accuracy of the prosthetic teeth occlusion.

Influence of different post core materials on the color of Empress 2 full ceramic crowns

For esthetic consideration, dentin color post core materials were normally used for all-ceramic crown restorations. However, in some cases, clinicians have to consider combining a full ceramic crown with a metal post core. Therefore, this experiment was conducted to test the esthetical possibility of applying cast metal post core in a full ceramic crown restoration. The color of full ceramic crowns on gold and Nickel-Chrome post cores was compared with the color of the same crowns on tooth colored post cores. Different try-in pastes were used to imitate the influence of a composite cementation on the color of different restorative combinations. The majority of patients could not detect any color difference less than DeltaE 1.8 between the two ceramic samples. So, DeltaE 1.8 was taken as the objective evaluative criterion for the evaluation of color matching and patients' satisfaction. When the Empress 2 crown was combined with the gold alloy post core, the color of the resulting material was similar to that of a glass fiber reinforced resin post core (DeltaE = 0.3). The gold alloy post core and the try-in paste did not show a perceptible color change in the full ceramic crowns, which indicated that the color of the crowns might not be susceptible to change between lab and clinic as well as during the process of composite cementation. Without an opaque covering the Ni-Cr post core would cause an unacceptable color effect on the crown (DeltaE = 2.0), but with opaque covering, the color effect became more clinically satisfactory (DeltaE = 1.8). It may be possible to apply a gold alloy post core in the Empress 2 full ceramic crown restoration when necessary. If a non-extractible Ni-Cr post core exists in the root canal, it might be possible to restore the tooth with an Empress 2 crown after covering the labial surface of the core with one layer of opaque resin cement.

Axial-wall inclination angle and vertical height interactions in molar full crown preparations

This study has been designed to evaluate the interaction of axial wall heights with inclination angles in full crown tooth preparations. The interaction of these parameters was related to the resulting preparation surface area. A right regular pyramid was used to simulate a single mandibular molar preparation with known convergence angles and vertical heights. Various combinations of these two variables allowed the calculation of surface areas with a formula for the area of a pyramid and right triangles through trigonometric manipulations. The pyramidal model system had a 9-mm square base with vertical heights from 3- to 5-mm and single-side inclination angles from 2 to 25 degrees. The occlusal surface was a flat, square or rectangular surface and was included in the total area. A percentage of surface area lost or gained served as the dependent variables. The significance levels were set at 10.0% or greater magnitude of loss/gain in a surface area compared to the ideal 2 degree-level. Significant area loss was demonstrated in all alpha-level comparisons. The largest change was found in the 5-mm height grouping compared to the 3-mm height grouping, -36.6% difference between groups at the 2 degree-level. Axial single-side inclination angles greater than 10 degrees in 3- and 4-mm height-molars are detrimental to maximum surface area in full crown restorations. The 5-mm axial wall height with < or = 10 degree single wall has been shown to maximize the luting agent surface area between restoration and tooth structure.

The Effect of Die Spacer on Retention and Fitting of Complete Cast Crowns

This study evaluated the effect of die spacer on the fit and retention of complete cast crowns by using three different cements. Standardized full crown restoration preparations were completed on 99 extracted molar teeth, impressions were made with poly(vinyl siloxane), and stone dies were made. Dies were covered with four layers of die spacer using three techniques: (1) covering the occlusal and 1/3 of the axial surfaces, (2) covering the occlusal and 2/3 of the axial surfaces, and (3) covering the entire preparation except the apical 0.5 mm of the preparation. Complete metal crowns were cast using Pors-on 4 alloy. Crowns were then assigned to one of three luting agent groups: resin modified glass ionomer cement, resin cement, or zinc phosphate cement. The castings were placed on their respective teeth and the marginal opening was recorded by two methods: 72 specimens were examined before and after cementation using optical microscopy with 0.001 mm resolution, and 27 specimens were examined after cementation with scanning electron microscopy. After cementation, the teeth were thermocycled for 700 cycles between 5 degrees C and 55 degrees C. The tensile retentive strength was measured on a universal testing machine with a crosshead speed of 0.5 mm/min. The data obtained for the fitting were recorded in millimeters and the data for the tensile retentive strength were recorded in KgF. The statistical analysis was performed by analysis of variance and post hoc Tukey's test (p< 0.05). Before cementation, better marginal fit was obtained when the die spacer covered all but the area 0.5 mm short of the margin of the preparation; however, after cementation, the resin modified glass ionomer cement group had the best fit with the same application of die spacer. Castings luted with resin cement required the greatest tensile force to produce cement failure. Increasing the area of the die surface covered with spacer improved the fit of the cast restoration. After cementation, the resin modified glass ionomer showed better adaptation; however, the optical microscopy and scanning microscopy correlate well. Resin cement had the highest resistance to tensile forces.

Microleakage of various cementing agents for full cast crowns

Objectives To evaluate microleakage and marginal gaps in full cast crown restorations bonded with six different types of cementing agents. Methods Sixty non-carious human premolars and molars were prepared in a standardized manner for full cast crown restorations. The mesial and distal margins were located in dentin, while the vestibular and palatal/lingual margins were located in enamel. Crowns were made from a high-gold alloy using a standardized technique. The specimens were randomized to six groups of cementing agents: one zinc-phosphate cement (Harvard cement), one conventional glass–ionomer cement (Fuji I), one resin-modified glass–ionomer cement (Fuji Plus), two standard resin cements (RelyX ARC, Panavia F), and one self-adhesive universal resin cement (RelyX Unicem). After 4 weeks of storage in distilled water at 37°C, the specimens were subjected to 5000 thermocycles ranging from 5 to 55°C. Then, they were placed in a silver nitrate solution, embedded in resin blocks, and vertically cut in buccolingual and mesiodistal direction. Subsequently, the objects were evaluated for microleakage and marginal gap using a high-resolution digital microscope camera. Results A number of inter-group differences were statistically significant. RelyX Unicem showed the smallest degree of microleakage both in enamel and in dentin. Panavia F und RelyX Unicem were associated with significantly larger marginal gaps than all other cementing agents. No association was observed between microleakage and marginal gap other than a weak direct correlation when using Harvard cement on enamel. Significance The cementing agents investigated revealed different sealing abilities. These differences were not associated with specific types of materials.—Reprinted with permission of The Academy of Dental Materials.

A comparative study on the retention of full coverage cast crowns cemented with zinc phosphate cement with and without die relief agent on prepared human teeth

Purpose of study: The purpose of this study is to analyze the effect of die spacer on retention of full coverage crowns. The success of a full cast crown restoration depends on the marginal fit and the retention of the restoration. The application of die spacer helps to improve the fit of the crown, but its effect on postcementation retention has been a subject of controversy. The present study was undertaken to compare the retentive force required to dislodge the unspaced and spaced crowns. Methodology: Twenty-five freshly extracted molar teeth were prepared and two stone dies were prepared for each tooth. One die from each pair was coated with four layers of die spacer. A pair of castings was obtained for each tooth. Force required to dislodge the cemented castings was measured using a constant displacement-rate-testing machine. Conclusion: Die spacer reduces the retention of the castings. Die spacing must be used carefully to maximize its potential and eliminate the loss of retention.

Microleakage of various cementing agents for full cast crowns

To evaluate microleakage and marginal gaps in full cast crown restorations bonded with six different types of cementing agents. Sixty non-carious human premolars and molars were prepared in a standardized manner for full cast crown restorations. The mesial and distal margins were located in dentin, while the vestibular and palatal/lingual margins were located in enamel. Crowns were made from a high-gold alloy using a standardized technique. The specimens were randomized to six groups of cementing agents: one zinc-phosphate cement (Harvard cement), one conventional glass-ionomer cement (Fuji I), one resin-modified glass-ionomer cement (Fuji Plus), two standard resin cements (RelyX ARC, Panavia F), and one self-adhesive universal resin cement (RelyX Unicem). After 4 weeks of storage in distilled water at 37 degrees C, the specimens were subjected to 5000 thermocycles ranging from 5 to 55 degrees C. Then, they were placed in a silver nitrate solution, embedded in resin blocks, and vertically cut in buccolingual and mesiodistal direction. Subsequently, the objects were evaluated for microleakage and marginal gap using a high-resolution digital microscope camera. A number of inter-group differences were statistically significant. RelyX Unicem showed the smallest degree of microleakage both in enamel and in dentin. Panavia F und RelyX Unicem were associated with significantly larger marginal gaps than all other cementing agents. No association was observed between microleakage and marginal gap other than a weak direct correlation when using Harvard cement on enamel. The cementing agents investigated revealed different sealing abilities. These differences were not associated with specific types of materials.

Mathematical analysis of tooth and restoration contour using image analysis

The aim of this study was to develop a methodology for comparison of the contour of artificial crowns in the mid bucco-lingual plane with their equivalent natural teeth on the opposing side of the same arch (antimeres) using a novel application of image analysis software. The objective was to determine whether artificial crowns were overcontoured. Specimens consisted of thin sections of silicone putty impressions of the buccal and lingual surfaces of 55 full crown restorations and their natural antimeric teeth. A thin slice of the putty was obtained in the mid-tooth bucco-lingual plane and a digital image was captured and this was analysed to produce a data set (x, y) representing the curvature of the tooth surface. Further analysis was performed in order to describe the profile in optimum mathematical terms. The curves were best represented by three equations: y = a + bx(0.5), ln(y) = a + bx2, and y2 = a + bx. In all equations parameter (b), which expresses the contour curvature, was used as a deciding factor in comparing the degree of contour of the crown restorations with their natural antimeres. Most artificial crowns were found to be either similarly or undercontoured when compared with their natural antimeres. When overcontouring was present in the artificial crowns this tended to occur on the lingual aspects of anterior and posterior crowns. Simplifying tooth contour into a mathematical model can be useful in determining whether restorations are overcontoured. Clinically, particular attention should be directed towards the lingual aspects of restorations which were more likely to be overcontoured.

The influence of the impression tray on the accuracy of impressions for crown and bridge work--an investigation and review.

To evaluate the accuracy of working casts for crown and bridge restorations made from twin mix putty/wash silicone elastomeric impression materials using different types of stock tray. A master cast was made from ivorine teeth in a mandibular model. Three teeth were prepared for full crown restorations to simulate a single unit and a three unit bridge. Impressions were taken using four different types of impression tray and two different viscosities of silicone putty, together with a wash. Full metal crowns were constructed and seated on duplicate master casts and measurements made of the marginal discrepancies. The work was carried out in a dental technology laboratory in a university department of restorative dentistry in 1995/1996. Metal and rigid plastic impression trays showed the least discrepancy (about 50 microns), the latter slightly greater with the normal putty than the soft one. Impressions taken with flexible plastic trays produced considerable discrepancy with both putties, approximately 210 microns and 180 microns respectively. Metal and rigid plastic stock trays give greater accuracy in the putty/wash silicone twin mix impression technique compared with flexible plastic ones for crown and bridge work. Those using the latter should be aware of their shortcoming in this respect.

"The view" and the canine connection: an atlas of mandibular anterior tooth esthetics.

Restoring splinted mandibular incisors and canines with full crown restorations has always presented a challenge in creating an esthetic illusion of reality of normal individual teeth. This treatise is designed to present the rules for mandibular anterior esthetics that have been distilled from almost 4 decades of clinical practice of restoring dentitions that have been severely compromised by the deformities of disease or accident. The resultant formula systematically creates the desired results with a high degree of predictability.

Evaluation of the clinical performance and effectiveness of adhesively-bonded metal crowns on damaged canine teeth of working dogs over a two- to 52-month period.

In this clinical study, 41 metal full crown restorations of canine teeth were placed in 18 working dogs. Twenty-six canine teeth had severe attrition with no involvement of the pulp cavities; 15 fractured canine teeth were endodontically treated. With the exception of one tooth, at least one-third of the coronal part of each canine tooth was available for a supragingivally performed, minimal tooth crown preparation. A dental resin luting cement technique was used to bond the electrolytically etched crown (made from an alloy of cobalt-chrome-molybdenum) to the tooth. The metal crowns were slightly shorter and with a more rounded tip than the original tooth. Posts or post-and-core techniques were not used. Median follow-up period was 30 months (range 2 to 61 months), at which time 36 crowns were found to be intact and functional. Five crowns were lost; three as a result of subsequent injury and fracture of the tooth below the crown; one as a result of use of less than one-third of the coronal portion of the tooth for retention of the crown; and one as a result of an oblique fracture of the root.