Full Crown Restorations Research Articles

Long‐term success rate of resin‐bonded metal crowns on the canine teeth of working dogs

Summary In this clinical study, 19 full metal crown restorations of canine teeth were placed in seven working dogs. Thirteen canine teeth were severely abraded with no involvement of the pulp cavities; six fractured canine teeth were endodontically treated. At least 1/3 of the coronal part of the canine tooth was available for a supragingivally performed, minimal tooth crown preparation. An adhesive technique to bond the electrolytically etched crown (an alloy of cobalt‐chrome‐molybdenum) to the tooth was used. The metal crowns, slightly shorter and with a rounder tip than the original tooth, were bonded to the enamel and dentine by using a resin luting cement. Posts or postand‐core techniques were not used. Mean follow‐up period was 32 months (range 24 ‐ 52 months), at which stage 17 crowns were found to be intact and functional. Two crowns were lost as a result of trauma resulting in a fracture of the tooth below the crown.

Cements used for full crown restorations: a survey of the American Academy of Esthetic Dentistry.

Journal of Esthetic and Restorative DentistryVolume 9, Issue 1 p. 20-26 Cements Used for Full Crown Restorations: A Survey of the American Academy of Esthetic Dentistry GORDON J. CHRISTENSEN DDS, MSD, PhD, Corresponding Author GORDON J. CHRISTENSEN DDS, MSD, PhD Director, Practical Clinical Courses, Senior Consultant, Clinical Research Associates, Adjunct Professor, Brigham Young University, Provo, and Clinical Professor. University of Utah, Salt Lake City, UtahReprint requests: Dr. Cordon J. Christensen, 3707 North Canyon Road, Suite 7A, Prom, UT 84604Search for more papers by this author GORDON J. CHRISTENSEN DDS, MSD, PhD, Corresponding Author GORDON J. CHRISTENSEN DDS, MSD, PhD Director, Practical Clinical Courses, Senior Consultant, Clinical Research Associates, Adjunct Professor, Brigham Young University, Provo, and Clinical Professor. University of Utah, Salt Lake City, UtahReprint requests: Dr. Cordon J. Christensen, 3707 North Canyon Road, Suite 7A, Prom, UT 84604Search for more papers by this author First published: 01 July 2007 https://doi.org/10.1111/j.1708-8240.1997.tb00911.xCitations: 6AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume9, Issue1January 1997Pages 20-26 RelatedInformation

Esthetic principles for full crown restorations. Part II: Provisionalization.

Esthetic principles for full crown restorations. Part II: Provisionalization.

Deformation of vented crowns with fluids of differing viscosities

Venting of full crown restorations is an effective aid to seating during cementation. Vent hole repair complicates placement procedures and potentially disturbs the coronal integrity of the restoration. Cervical deformation of crowns during cementation was measured with circumferential strain gauges. Crowns were able to be vented occlusally, and two silicone fluids of widely differing viscosities were used. Venting significantly decreased the time to seat for both viscosities. It also decreased deformation of crowns cemented with low viscosity fluid, but increased deformation during cementation with high viscosity fluid. The values of deformation were nearing clinical significance for ceramic systems. Increased axial wall separation gave a similar decrease in seating times, but with no increase in deformation. The advisability of venting is questioned when high viscosity cements are used, and methods of increasing axial wall separation are recommended.

Esthetic principles for full crown restorations. Part I: Tooth preparation.

Esthetic principles for full crown restorations. Part I: Tooth preparation.

Thermal cycling distortion of metal ceramics: Part I—Metal collar width

The complex three-dimensional geometry of conventional full crown restorations severely complicates the study of thermal cycling distortion in metal ceramic castings. A simplified experimental geometry was developed to (1) maximize the measuring sensitivity, (2) eliminate the casting variables, (3) allow the direct measurement of casting distortion, and (4) evaluate the thermal cycling distortion of a wide range of metal collar widths. It was found that all of the one-walled castings distorted during the initial thermal cycling (oxidation) of the alloy. There was no significant distortion associated with porcelain application or glazing. The castings with an 0.8 mm metal collar had significantly less distortion than those with 0.1 and 0.4 mm collars at 2 of the 10 sites measured (inferior or facial margins).

A simple model of crack propagation in dental restorations

Although natural teeth often exhibit microcracks, they rarely demonstrate bulk fracture. However, conventional fullcrown restorations periodically exhibit failure due to fracture. Presented here is evaluation of a simple model of crack propagation that estimates crack growth during cyclic loading. A finite element model of a premolar tooth provides the tensile stresses adjacent to cusp loading. If the crack propagation rates for natural teeth, porcelain-fused-to-metal crowns and composite crowns are compared with the wear rates of their respective materials as determined in an artificial mouth, it is evident that the low wear rate of composites may predispose them to fracture. Natural teeth disperse occlusal stresses throughout the dentin so that the effect of high occlusal stress is minimized. Porcelain tends to wear the opposing dentition, which reduces areas of high occlusal stress. Composite, however, demonstrates crack propagation rates higher than those of either natural teeth or porcelain. This, in addition to its low wear rate, might predispose the material to fracture. This model should be used only as a qualitative indicator of fracture tendency. The high calculated crack propagation rates in composites may explain the observed clinical failures and microchipping at the area of occlusal contact, as noted in SEM analysis.

Full crown restorations

Full crown restorations

Bleaching of discoloured root-filled teeth.

Abstract In this study a simple and time–saving method for bleaching of discoloured root‐filled teeth is presented. The method used sodium perborate moistened with water and the access cavity is temporarily sealed with Cavit® between visits. Bleaching was carried out in 95 teeth, with a satisfactory initial result in 90% of the cases. After 3 years of observation, recurrence of discolouration was found in 20% of the teeth seen at follow‐up examination. The method is easy, fast and essentially without complications. It is therefore recommended as an alternative to full crown restoration, assuming the tooth is not too weakened because of large fillings.

ポリカルボキシレートセメントの合着強さと歯髄反応に関する研究

In order to determine the clinical assessment of the polycarboxylate cements, some test were made on four commercially available polycarboxylate cements and one zinc phosphate cement as control.The findings are as follows:1. Tensile strength of the polycarboxylate cements obtained with the crown model was similar or stronger than that of zinc phosphate cement. Tensile strength with taper 1/10 crown model was significantly stronger than that with taper 2/10 crown model.2. In case of the shear strength at dentine-polycarboxylate interface on smooth surface was stronger than on rough surface, and the result showed that adhesion was due to chelate bond. While the shear strength at dentinecement interface obtained with polycarboxylate cements was variable, it was certainly superior to that obtained with zinc phosphate cement.3. The shear strength of polycarboxylate cements was more than twice that of zinc phosphate cement.4. The polycarboxylate cements were not irritant to dental pulp.5. The properties obtained with these test made the polycarboxylate cement the material of choice for cementing full crown restorations and bridge work on vital teeth.

Full crown restorations and gingival inflammation in a controlled population

The volume of crevicular fluid around full crown restorations was measured with a Periotron instrument to compare the gingival inflammation between restored and nonrestored teeth in the same patient. Thirty-eight full crown restorations were compared to nonrestored teeth used as controls in 26 patients. Forty-six full crown restorations in 28 patients were also evaluated according to gingival margin placement to determine if there was a difference in inflammation in gingival tissues. The highly motivated patients were selected from a private practice because of their interest and investment in long-term dental health. The results revealed the following findings. 1. Full crown restorations have the potential for causing gingival inflammation. However, they need not be associated with a significant increase in gingival inflammation when placed in the oral environment of a highly motivated patient in a rigid dental recall program. 2. Gingival inflammation surrounding full crown restorations may be controlled regardless of gingival margin placement when the gingiva is healthy, the restorations are adequate, and the patient is in a strict recall program.

A comparative evaluation of three post and core techniques

An in vitro study was performed evaluating three post and core techniques with and without full crown coverage on extracted mandibular molar teeth. The materials evaluated were amalgam, composite resin, and stainless steel posts, and a combination of cast-gold and stainless steel posts. The results indicate that the method of post and core technique may not be as significant as the placement of full coverage cast-gold crown restorations with sound design and placement of margins beyond the buildup restoration.

The effect of various finish line preparations on the marginal seal and occlusal seat of full crown preparations

The influence of the marginal design of a full crown on the occlusal seat and marginal seal of a cemented full crown restoration was examined. Under the conditions of the study, the featheredge and parallel bevel preparations demonstrated the best marginal seal, followed in order by the full shoulder, 45-degree shoulder, and finally the 90-degree shoulders with 30-degree and 45-degree bevels. With regard to seating of the restoration, the 90-degree full shoulder demonstrated the best seat, followed in order by the 45-degree shoulder, 90-degree shoulder with 45-degree bevel, featheredge, 90-degree shoulder with 30-degree bevel, chamfer with parallel bevel, and finally 90-degree shoulder with parallel bevel.

Analysis of the geometry of finishing lines for full crown restorations

The geometry exhibiting the least marginal discrepancy in this investigation was the shoulder of the slightly oversize casting (Fig. 4). This was significantly better (p = .05) than the oversize bevel, the control shoulder, or the control bevel.

Development of dental plaque on epoxy resin crowns in man. A light and electron microscopic study.

A method was presented to fabricate epoxy resin crowns to be worn by human subjects requiring full crown restorations. These crowns were utilized in six young adults to study the internal structure of plaque after plaque formation periods of 1 and 3 days, 1 and 3 weeks and 2 months. This study confirmed previous findings that early plaque contains primarily coccal forms, with a shift to predominantly filamentous forms by 3 weeks. Early plaque growth seems to occur by the formation of columnar microcolonies which coalesce and grow by cell division within the colony in a direction perpendicular to the crown surface. Filamentous microorganisms appear in large numbers by 1 week. They appear to colonize the surface of the predominantly coccal plaque, eventually growing into it and replacing the coccal forms. The subgingival, mature plaque contains many motile forms including bacteria with unusual cell wall ultrastructures. Certain bacteria combine into distinctive bacterial aggregations resembling "corn cobs" and "test tube brushes," the latter occurring exclusively in subgingival plaque. Spirochetes appear to grow preferentially on the external surface of subgingival plaque in close contact to the gingival tissue of the deepened sulcus. Their high concentration in the external layer of subgingival plaque suggests that because of their strategic location they may play an important role in the etiology of periodontal disease. Studies of well preserved plaque, possibly combined with the use of serological markers, can serve a useful role in identifying certain microorganisms in dental plaque. Because of their numbers and/or location in relation to periodontal tissues, some of these bacteria may warrant further studies as potential etiologic agents of certain forms of periodontal disease.

Measurement of the cement film thickness beneath full crown restorations.

Measurement of the cement film thickness beneath full crown restorations.

Relationship of crown margin placement to gingival inflammation

T he treatment of dental defects by the pIacement of full crown restorations suggests that we consider the proper location of the margin of the restoration with respect to the gingiva. The choice to be made, either subgingival or supragingival, is particularly important to the full crown restoration, because the extent of the margin next to the gingival tissue is much greater than that for other types of restorations. However, the same biologic principles are common to all restorations. and therefore, any additional light shed on this problem should be of considerable significance. There are a number of contraindications to the placement of supragingival finish lines. For example, supragingival placement is not indicated when ( 1) the clinical crown is short, (2) old restorations with subgingival margins are present, (3) crowns with facings are to be placed in areas requiring an esthetic appearance. and (4) caries, abrasion, or erosion has degraded the gingival third of the clinical crown. Yet, there are many circumstances where a choice can be made (such as, restorations involving lingual surfaces and posterior crowns) which do not fall into the categories listed above. In these situations, perhaps the most significant factor in consideration of the location of the margin is the health of the gingival tissues in close approximation to this margin. The venerable concept of “extension for prevention” must be critically examined in light of the difficulty in achieving subgingival marginal excellence. In 1925, Gottlieb contended that this principle was not valid. He repeated his statements many times and particularly in 1933 in his and Orban’s text.” In the English translation of this text, the following statement can be found”:

Porcelain-veneered full-crown restorations made with cadmium patterns

A technique with cadmium for direct metal patterns has been described. Previously, the use of this technique was limited to full gold crowns and acrylic resin veneer crowns. Clinical experience has shown that it can be used for making porcelain fused-to-metal restorations. The technique is not intended to supplant other techniques, but it will eliminate the need for copper band impressions, transfers, copings, and extensive occlusal registration procedures. Because patterns are preformed and are No. 30 gauge in thickness, it is possible to minimize the cutting necessary for preparing the tooth. Therefore, thermal sensitivity is reduced. The technique conserves time for both the dentist and the patient.

Experimental stress analysis of dental restorations: Part II. Two-dimensional photoelastic stress analysis of crowns

The general stress distribution in full crown restorations was investigated using a two-dimensional photoelastic stress analysis method. Crowns on tipped molar abutments as well as on normally aligned molars were analyzed. The maximum compressive stresses on the interior of crowns were generally found to be on the reduced cusp surface of the restorations. Maximum tensile stresses were observed in the central fossa and along the axis of symmetry of the crown, when the crowns were loaded bilaterally to simulate oral conditions. Stresses were also investigated at the free boundaries of the crown, and tensile stresses were observed at the cervical margins of the restoration with compressive loads of 133 pounds and at a cusp angle of 39 degrees.

The construction of accurate full crown restorations for an existing clasp by using a direct metal pattern technique

A direct technique for making full crowns for teeth which carry partial denture clasps has been described. A cadmium crown form is adapted to the prepared tooth, and its contours are modified with wax to fit the clasp. The laboratory procedures are described in detail.