Two in one diamond rotary instruments.
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Dental High-Speed Equipment↗
SEARCH · PubMed Health
Results for “Tooth Preparation, Prosthodontic”
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
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Effect of dowel lubrication on resistance to dislodgment of dowels cemented with a 4-META resinous cement.
Dentatus stainless steel dowels were cemented 5 mm into prepared canals of extracted human teeth with C&B Metabond cement. One half the dowels were lubricated before cementation to ensure easy subsequent retrieval. Significantly less tensile force was required to dislodge the lubricated dowels (p = 0.0209). Retrievable lubricated dowels could provide dentists the option of nonsurgical endodontic retreatment in lieu of endodontic surgery. However, lubrication cannot be recommended for clinical use at this time because of the potential for the dowel to unscrew during normal oral function. Further studies are required to determine the effects of rotational forces on the lubricated dowel, surface design of the dowel on retention, and chemical interaction of the lubricant on the resinous cement. Long-term effects of the lubricant on the cement are unknown.
Acrylic Resins↗
Clinical performance of resin-bonded fixed partial dentures.
Resin-bonded fixed partial dentures (RBFPDs) initially recorded poor survival rates because of indefinite tooth preparations and arbitrary selection of composite resin cements. In this study, 46 RBFPDs were inserted for a longitudinal study up to 45 months. The influence of location--anterior/posterior, or maxilla/mandible--and the inclusion of pontics in occlusal excursions on the survival rates was investigated. Periodontal parameters were recorded from abutments and controls (teeth). Eight RBFPDs lost retention and two RBFPDs failed because of porcelain fractures. The anterior to posterior location and the maxillary or mandibular arch had significant influence on the survival rates. Gingival scores of abutments and controls differed significantly, but statistically significant differences were not recorded for plaque scores.
Adolescent↗
Survey lines revisited: finding nonundercut surfaces for retainers that approach from the occlusal surface.
This study investigated survey lines on abutments in the partially edentulous mouth. Various methods that were used to determine the path of insertion had little impact on the position of survey lines except on tooth surfaces with minimal undercuts. Typical survey lines are described and according to the survey lines, few tooth surfaces could accommodate the rigid portion of an occlusally approaching retainer and permit it to be positioned on a nonundercut tooth surface. Although some degree of enameloplasty to improve the situation on some tooth surfaces is possible, the degree to which this can be done is limited by the thickness of the enamel and considerations of tooth conservation.
Dental Abutments↗
Full veneer versus traditional veneer preparation: a discussion of interproximal extension.
STATEMENT OF PROBLEM: Traditional veneer preparation has come to represent an almost universally accepted guideline of veneer preparation. It calls for an interproximal finish line at or just into the contact point. However, in certain situations, such an approach can have functional and esthetic limitations. PURPOSE: This article reviews those functional and esthetic limitations and discusses an alternative technique, the full veneer preparation. The advantages and disadvantages of this approach are discussed in relation to veneer cases with malaligned teeth, diastema, discoloration, black spaces, restorations, and/or veneers next to crowns.
Crowns↗
Surveying removable partial dentures: the importance of guiding planes and path of insertion for stability.
STATEMENT OF PROBLEM: Although removable partial dentures are a favored option for the restoration of many situations that involve partial tooth loss, some patients are not satisfied with a removable partial denture, especially when it is not stable during mastication. A dental surveyor can be used to prevent countless problems related to the production of removable partial dentures. Many professionals working with oral rehabilitation fail to take advantage of the many uses of a surveyor in planning and designing chromium alloy and other metal removable partial denture frameworks. PURPOSE: This article uses an academic approach to describe the criteria used to determine the path and removal of a removable partial denture. A fundamental requirement for understanding the correct use of the dental surveyor is to prevent indiscriminate use of a path of insertion perpendicular to the occlusal plane, and extreme inclinations of the cast in the attempt to create undercuts on some teeth.
Chromium Alloys↗
In vitro failure load of metal-collar margins compared with porcelain facial margins of metal-ceramic crowns.
PURPOSE: This in vitro study compared the load necessary to cause porcelain failure on traditionally fabricated metal-ceramic crowns cemented to metal tooth analogs with two different types of margins. MATERIAL AND METHODS: Metal-ceramic crowns were constructed with either metal facial collars or porcelain facial margins. The metal tooth analogs were embedded in polymethyl methacrylate resin blocks, so that a load applied to the lingual surface compressed the facial margins. Increasingly greater loads were applied to specimens until failure occurred and the failure load values of all specimens were statistically evaluated. RESULTS: The load required to cause porcelain fracture in the crowns with porcelain facial margins was statistically significantly greater than the load required to cause porcelain fracture for crowns with metal collars (p < 0.02).
Cementation↗
Alternative method of conservative esthetic treatment for gingival recession.
The health and appearance of gingival tissue play an essential role in esthetics. The esthetic function of the tissue is enhanced when it frames the restoration. With gingival recession, the effect of natural gingiva is created with pink composites or ceramics on the cervical part of the crown, as described in this clinical report. This goal depends on the absence of adverse effects on the color, shape, and health of the surrounding tissue. The new composites are more color stable and wear resistant, and the latest generation of dental bonding agents allows the bonding of composites to dentin, various metals, and porcelain. The application of soft-tissue colored composite on dentin cementum, enamel, or porcelain is a good solution for correcting gingival recessions.
Acid Etching, Dental↗
Enhanced permeability of acid-etched or ground dental enamel.
STATEMENT OF PROBLEM: Acid etching creates retentive microcraters on enamel surfaces. Designing of a partial denture often involves reshaping the supporting and retentive teeth by grinding the enamel. Unfortunately, both these procedures damage the enamel surface. In vivo such surface damage takes several months to recover. PURPOSE: This study evaluated the effect of 1-minute etching, prolonged etching, and grinding on the permeability of dental enamel for water-soluble molecules. MATERIAL AND METHODS: With the electron paramagnetic resonance and a two-chamber diffusion cell, the influence of etching and grinding on the diffusion of spin label molecules through the enamel was studied quantitatively. The enamel permeability was measured in 30 sound enamel samples, of which 10 samples were exposed to 1-minute etching with 37% phosphoric acid, 10 samples were etched for 5 minutes, and 10 samples were ground with a diamond bur. RESULTS AND CONCLUSIONS: All procedures significantly increased the permeability of dental enamel. These results demonstrate that in vivo the acid-etched and ground dental enamel surfaces are less protected and consequently, unless the tooth is properly protected, are more susceptible to carious lesions. Therefore ground or accidentally etched enamel should be protected.
Acid Etching, Dental↗
Retrofitting a dowel and core to an existing crown.
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Cementation↗
Effect of convergence angle on retention of resin-bonded retainers cemented with resinous cements.
STATEMENT OF PROBLEM: Poor retention is a common cause of failure for resin-bonded restorations. PURPOSE: This study evaluated the effect of the convergence angle of tooth preparations on retention of resin-bonded restorations, luted with adhesive and conventional resinous cements. MATERIAL AND METHODS: A total of 80 posterior retainers with four different tooth preparation angles were cemented with two different resinous cements, and retentive strength was measured. RESULTS: The results indicated that (1) increased tapering of tooth preparations resulted in loss of retention and this variable was statistically significant for both cements used when convergence angles exceeded 10 degrees and (2) sandblasted nickel-chromium retainers, combined with adhesive resins, should provide sufficient retention for posterior resin-bonded fixed partial dentures.
Adhesives↗
Crown foundations with a custom matrix, composites, and reverse carving.
This article describes a restorative technique for the formation of composite cores for artificial crowns. The procedure uses a semirigid matrix with reverse carving to form the cores on substantially compromised teeth. The matrix allows the placement of the composite under pressure to reduce voids and gaps and permits completion of multiple cores simultaneously. Reverse carving enables development of a common axis for multiple cores. The dentist can perform the tooth preparation for the crown at the time of the core restoration. The effort commonly applied to developing tooth morphologic features in the core can be invested instead in the formation of the interim restoration. The remaining tooth structure, pin or post placement, and location of the finish line can be evaluated with the insight of a crown foundation and not merely as a traditional restoration.
Composite Resins↗
Tissue stops aid in improving accuracy of impressions.
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Dental Impression Materials↗
Bactericidal eradication from carious lesions of prepared abutments by an antibacterial temporary cement.
PURPOSE: The aim of this study was to observe the antibacterial potential of polycarboxylate temporary cement containing a mixture of metronidazole, ciprofloxacin, and cefaclor on carious lesions of prepared abutments that were designed to leave caries on the abutments. MATERIAL AND METHODS: Antibacterial efficacy was estimated in vitro and in vivo by measuring bacterial recovery from the lesions. Bacteria counts ranged from 10(4) to 10(7) both in vitro (nine samples) and in vivo (five samples) in time-zero samples, just before the application of the antibacterial cement. RESULTS: No bacteria were recovered from carious lesions in vitro (six samples) or in vivo (four samples) after the lesions were covered by the antibacterial temporary cement. For the remaining samples, some bacteria (5 to 80 counts per sample) were recovered, with one notable exception in which marginal leakage provided a bacteria count of 10(3). Bacteria counts ranging from 10(3) to 10(5) occurred in carious lesions covered by temporary cement without antibacterial agents, which indicated that temporary cement alone was not a potent disinfectant. CONCLUSIONS: The results of this study indicated that the antibacterial temporary cement can be useful for eradicating bacteria from carious lesions of prepared abutments.
Adult↗
Effect of tooth preparation design on bond strengths of resin-bonded prostheses: a pilot study.
STATEMENT OF PROBLEM: The success rate of resin-bonded fixed partial dentures is directly related to the adhesive system and the tooth preparation design for good retention. PURPOSE OF STUDY: This in vitro study evaluated the effect of various tooth preparation designs on the bond strength of retainers for adhesive fixed partial dentures. MATERIAL AND METHODS: Molar teeth were prepared in the conventional form or with occlusal coverage and opposing grooves and retainers were silicoated and bonded to etched enamel by a bis-glycerol methacrylate adhesive. Bond strengths were determined after water storage and thermocycling. RESULTS: The least mean bond strength was recorded for the conventional form of tooth preparation (p < 0.05). CONCLUSION: A combination of 180-degree opposing groove placement at line angles "wraparound" and occlusal coverage resulted in the greatest bonding values.
Analysis of Variance↗
Influence of tooth surface roughness and type of cement on retention of complete cast crowns.
STATEMENT OF PROBLEM: Bond strength of luting cements to dentin is a critical consideration for success of cast restorations. PURPOSE OF STUDY: This study determined the relationship between surface characteristics of teeth prepared for complete cast crowns and retention of respective cemented restorations. MATERIAL AND METHODS: Ninety artificial crowns were cast for standardized complete crown tooth preparations accomplished with the use of a milling machine on extracted human teeth. Diamond, tungsten carbide finishing, and cross-cut carbide burs of similar shape were used. The crowns in each group were randomly subdivided into three subgroups of 10 for the three luting cements selected for this study: zinc phosphate cement (Fleck's), glass ionomer cement (Ketac-Cem), and adhesive resin cement (Panavia-EX). Retention was evaluated by measuring the tensile load required to dislodge the artificial crowns from tooth preparations with an Instron testing machine. RESULTS: Analysis of forces with parametric analysis of variance and Tukey's Studentized Range (HSD) disclosed a statistically significant difference for both luting cement and finishing burs (p < 0.001). A statistically significant interaction effect (p < 0.001) was also found. The greatest retention value (372.9 N) was for tooth preparations refined with carbide burs and cemented with Panavia-EX cement. However, the least retention value (201.6 N) was for tooth preparations completed with finishing burs and luted with zinc phosphate cement. CONCLUSIONS: Significant differences were found among all three cements for finishing burs. However, there was a difference only between Panavia-EX cement and the other two cements for tungsten carbide burs. For diamond rotary instruments, zinc phosphate cement was significantly different from glass ionomer and Panavia-EX cements.
Analysis of Variance↗
Precision of fit: the Procera AllCeram crown.
STATEMENT OF PROBLEM: Strength, color stability, and precision of fit are requirements for all-ceramic restorations. The Procera AllCeram crown system, composed of a densely sintered high-purity alumina core combined with a low fusing surface porcelain, appears to satisfy most of these requirements. However, evaluation of marginal fit has not been reported. PURPOSE: This study measured the precision of fit of the Procera AllCeram crown fabricated with Procera CAD/CAM technology for the premolar and molar teeth fit to a die. MATERIAL AND METHODS: Five ivorine maxillary first premolars and first molars were prepared for full-coverage crowns. Preparations were standardized with a convergence angle of 10 degrees, chamfer margins of 1.3 to 1.5 mm circumferentially, and occlusal reduction of 2.0 mm. AllCeram crowns were fabricated for the dies, and the fit of the crown to the die was determined by using a standardized procedure with a silicone impression material that served a dual role: (1) as a retrievable luting agent, and (2) to replicate the internal aspects of the crown. Laser videography was used to measure the gap dimension between the crowns and the dies at the marginal opening, the axial wall, the cusp tip, and the occlusal adaptation measurement locations. Mean gap dimensions and standard deviations (SDs) were calculated for marginal opening, internal adaptation, and precision of fit. RESULTS: Mean gap dimensions and standard deviations at the marginal opening for the premolar and molar crowns were 56.0 microns SD +/- 21 and 63.0 microns SD +/- 13 microns, respectively. The mean gap dimensions and SDs of the internal adaptation were 69.0 microns SD +/- 17 microns for axial wall, 48.0 microns SD +/- 12 microns for cusp tip, and 36.0 microns SD +/- 7 microns for occlusal adaptation for the premolar crowns; and 49.0 microns SD +/- 3 microns axial wall, 67.0 microns SD +/- 21 microns cusp tip, and 74.0 microns SD +/- 29 microns occlusal adaptation for molar crowns. Precision of fit and SDs for premolar and molar crowns were 52.0 microns SD +/- 19 microns and 63.0 microns SD +/- 20 microns, respectively. Mean marginal openings and precision of fit gap dimensions for the crown groups were not significantly different at the .05 level. However, gap dimensions that defined the internal adaptation at the measurement locations were different (P < or = .05). CONCLUSION: Mean gap dimensions for marginal openings, internal adaptation, and precision of fit for the crown groups were below 70 microns. These findings show that the crowns studied can be prescribed with confidence knowing that the precision of fit will consistently be less than 70 microns.
Aluminum Oxide↗
Evaluation of resistance form of dislodged crowns and retainers.
STATEMENT OF PROBLEM: The concept of limiting taper has been described as a boundary between tapers that do and those that do not provide resistance form for a preparation. There is controversy as to whether this boundary that divides preparations with from those without resistance form translates clinically into a boundary for success. PURPOSE: This investigation evaluated the resistance form of abutments of crowns or retainers that have been dislodged to determine the clinical correlation between restoration dislodgment and lack of resistance form in the preparation. MATERIAL AND METHODS: Dies were fabricated from single crowns and retainers of fixed partial dentures that came loose and evaluated for resistance form. A total of 44 abutments were evaluated and included 1 incisor, 15 premolars, and 28 molars. Data from a previous study on the percentage of abutments lacking resistance form for restorations leaving a large dental laboratory was used for comparative statistical tests. RESULTS: Forty-two of the 44 abutments (95%) lacked resistance form. All molar abutments and 93% of premolar abutments lacked resistance form in one or more directions. The one incisor abutment did not lack resistance form. Chi-square test revealed a statistically significant difference in the percentage lacking resistance form between the group composed of clinical failure (uncemented crowns) and the group leaving a dental laboratory with P = .0005 for the molars, and P = .0005 for the premolars. CONCLUSION: The clinical dislodgment of cast restorations is associated with the lack of resistance form in the preparations. In this study, there was a relationship between clinical success or failure and the all-or-none nature of resistance form; dislodged crowns come almost exclusively from preparations with tapers that did not provide resistance form.
Bicuspid↗