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At least 37 records · Page 2Linked to original sources
PubMed2004

Interdisciplinary management of dental implant patient: a case report.

Maxillary molars can over-erupt when their antagonists are lost and there are no replacements. When the opposing molars severely extrude into the edentulous space, it is difficult to replace the missing teeth with either fixed or removable prostheses. We present the following case report, providing a solution for this type of problem. A two-stage posterior subapical osteotomy was used to reestablish the intermaxillary space. Following orthodontic treatment and implant placement, the patient regained occlusal harmony and normal masticatory function.

Adult↗
PubMed2001

An in vitro study into the effect of the ferrule preparation on the fracture resistance of crowned teeth incorporating prefabricated post and composite core restorations.

AIM: This in vitro study investigated the effect of a ferrule preparation on the fracture resistance of crowned central incisors incorporating a prefabricated post (Parapost) cemented with Panavia-Ex and with a composite core. METHODOLOGY: The test group consisted of 10 post crowned natural central incisor teeth with a 2-mm wide ferrule preparation, whilst the control group of 10 teeth had no ferrule. The specimens were mounted on a Lloyd universal testing machine and a compressive load was applied at an angle of 135 degrees to the palatal surface of the crown until failure occurred. RESULTS: In both groups, failure occurred at higher loads compared with previous studies. The mean failure load was 1218 N for the unferruled group and 1407 N for the ferruled group. Statistical analysis showed no significant difference between the groups. CONCLUSIONS: Under the conditions of this study, when composite cement and core materials are utilized with a Parapost prefabricated system in vitro the additional use of a ferrule preparation has no benefit in terms of resistance to fracture.

Cementation↗
PubMed2000

Pulp reactions to different preparation techniques on teeth exhibiting periodontal disease.

To evaluate the histopathological outcome of two preparation techniques (featheredge preparation/shoulder preparation) on teeth exhibiting pulp reactions due to age and periodontal disease, 11 teeth were prepared for full veneer crowns. Laboratory made resin crowns were fixed with a zinc phosphate cement for a period of 90 days. After extraction, adjacent pulpal areas were histopathologically rated according to the BRD criteria comprising the parameters (i) Bacterial invasion, (ii) Regenerative parameters, (iii) Degenerative parameters. Degenerative reactions were more correlated with tooth preparation than with advanced periodontal disease. The severity of endondontal reactions depends more on remaining dentin thickness than on the type of preparation.

Acrylic Resins↗
PubMed2002

Effect of length and diameter of tapered posts on the retention.

The force transmission of tapered unthreaded posts along the root has been reported to be homogenous but their retentive strength was found to be lower compared with those of parallel unthreaded or other kinds of threaded posts. The purpose of this in vitro study was to investigate the effect of length and diameter on the retentive strength of sandblasted tapered prefabricated titanium posts (Erlangen post system). Posts with constant taper angle but with three different lengths (9, 12, 15 mm) and apical diameters (0.5, 0.9, 1.1 mm) were cemented using zinc phosphate cement into the prepared and roughened post spaces of 90 intact anterior teeth. The post retention concerning length and diameter, being independent from each other, was measured by a tensile force test. The retentive strength was found to be proportional to the length as well as to the diameter of the posts. The mean minimum strength (181 +/- 14 N) recorded for the thinnest and shortest post was significantly lower than that of mean maximum strength (612 +/- 85 N) obtained from those of the thickest and longest post. Proportional bond strengths of the posts comprising their surface areas ranged between 6.8 and 7.9 N mm(-2) which were not significantly different between any group. The retention was effected strongly with the increase in the length (approximately 100%) than with the increase in the diameter (approximately 60%). Concerning the posts tested in this study, it is concluded that some caution should be exercised in the choice of post with appropriate length rather than diameter for the tooth concerned.

Cementation↗
PubMed2005

Endodontic management of dens evaginatus of maxillary central incisors: a rare case report.

Dens evaginatus is a disturbance in tooth development that produces a tubercle of hard tissue on the surface of the tooth. While prophylactic pulp capping is recommended for vital teeth, teeth with necrotic pulps require endodontic therapy or extraction. This rare case of a 24-yr-old Indian male with affected maxillary central incisors demonstrates the clinical consequences of dens evaginatus.

Adult↗
PubMed2006

A finite element analysis of ferrule design on restoration resistance and distribution of stress within a root.

AIM: To analyse the effect of ferrule height upon the mechanical resistance and stress distribution within a root to explain variations in the pattern of root fracture. METHODOLOGY: An extracted, intact, caries free, maxillary right central incisor was scanned by laser and then reconstructed on a computer to produce a model of the tooth and associated periodontal ligament. A simulated post/core/crown restoration was constructed on conventional tooth preparations with various ferrules. The crown was loaded with a simulated 500 N force and the simulated displacement of components and the tensile and compressive stress within the tooth structure were recorded. RESULTS: Without a ferrule preparation, the simulated crown tilted to the labial and rotated distally. With increasing ferrule height the displacement and rotation of the crown reduced in conventional and crown-lengthening models with maximum reduction occurring when the ferrule height reached 1.5 mm. In ferrule models, higher levels of tensile stress developed in internal (by a factor of 8) and mid-root palatal (by a factor of 90) dentine at the cervical margin of the preparation. With an increase in ferrule height, the area of tensile stress within the palatal mid-dentine expanded towards the cervical margin. Similar patterns and stress values were recorded for the crown-lengthening models. CONCLUSION: The study confirms that a ferrule increases the mechanical resistance of a post/core/crown restoration. However a ferrule creates a larger area of palatal dentine under tensile stress that may be a favourable condition for a crack to develop. Crown-lengthening did not alter the levels or pattern of stress within compared with conventional ferrule preparations.

Computer Simulation↗
PubMed2006

An ex vivo study of the effects of retained coronal dentine on the strength of teeth restored with composite core and different post and core systems.

AIM: To investigate the fracture resistance and fracture patterns of teeth restored with composite cores supported by different pre-fabricated post systems and different heights of remaining coronal dentine. METHODOLOGY: Four groups of 30 single rooted teeth were used. Each group was divided into three subgroups of 10 teeth each and restored with carbon fibre, glass fibre, or Radix titanium posts luted with dual cure resin cement. The control group A had no retained coronal dentine. Groups B, C and D had 2, 3 and 4 mm of retained buccal and lingual coronal dentine, respectively. Teeth were tested to failure using an Instron Universal Testing Machine. Subsequently, the fracture mode of specimens was recorded. RESULTS: Teeth with retained dentine were more resistant to fracture (P = 0.001). Tooth fracture resistance was not significantly different between groups B, C and D. Within group A, titanium posts were associated with higher fracture resistance than fibre posts. Within the other groups, tooth fracture resistance was not related to post material. Within groups C and D, fracture resistance of teeth restored with carbon fibre posts was significantly higher than those restored with glass fibre posts. The dominant fracture mode in group A was core and vertical oblique root fracture whilst a combination of core, coronal dentine and root fracture occurred in the other groups. CONCLUSIONS: Fracture resistance of teeth increased with the presence of retained coronal dentine. The use of glass and carbon fibre posts did not improve the fracture resistance or the fracture pattern of teeth when compared with metal titanium posts regardless of the presence of retained coronal dentine. The dominant fracture pattern of teeth was not related to the amount of retained dentine if it was >2 mm high.

Carbon↗
PubMed2006

In vitro fracture behavior of maxillary premolars with metal crowns and several post-and-core systems.

The in vitro fracture behavior of severely damaged premolars, restored with metal crowns with limited ferrule and several post-and-core systems, was investigated. Crowns of maxillary premolars were removed and canals were prepared with Gates Glidden drills and with Parapost drills. Groups of 11 samples were each treated with cast post-and-cores (Parapost XP, Wironium Plus) (group 1), prefabricated metal posts (Parapost XH) (group 2), prefabricated glass fiber posts (Parapost FiberWhite) (group 3), and custom-made glass fiber posts (EverStick Post) (group 4). Posts and composite cores and metal crowns in groups 2, 3, and 4 were adhesively cemented. Post-and-cores and crowns in group 1 were cemented with phosphate cement. Thermocycling was performed (6,000x, 5-55 degrees C). Two static load tests (30 degrees ) were applied. During the first load test (preloading) no failures occurred. Failure modes from the second load test were categorized into favorable and unfavorable failures. Mean failure loads among the four groups (group 1, 1,845 N; group 2, 1,718 N; group 3, 1,812 N; and group 4, 1,514 N) were not significantly different. Unfavorable failures were root fractures and favorable failures were postcrown displacements. No differences in frequencies of unfavorable/favorable failures were seen among the groups. The results suggest that different post-and-core systems have no influence on the fracture behavior of severely damaged premolars restored with metal crowns with limited ferrule.

Bicuspid↗
PubMed2004

Computer-aided direct all-ceramic crowns: preliminary 1-year results of a prospective clinical study.

The objective of this study was to investigate the clinical performance of: (1) adhesively placed Cerec crowns with reduced stump preparations, and (2) Cerec endo crowns. The crowns were examined at baseline using modified USPHS criteria in 20 patients with 10 Cerec crowns with reduced stump preparations and 10 Cerec endo crowns. All crowns had been produced chairside with the Cerec 3 CAD/CAM method using the function mode. The crowns were machined from Vita Mk II feldspathic ceramic blocks, polished manually, and placed with dual-curing composite luting agent using a functional adhesive. After 1 year, a follow-up examination of the crowns was conducted; all 20 Cerec crowns were rated with a clinically acceptable A or B rating. Fractures or loss of retention were not observed. The method of producing and placing all-ceramic crowns with reduced stump preparations and endo crowns chairside in one appointment can be implemented successfully in private practice.

Adult↗
PubMed2003

Pulpal death.

Explore the source record for details and available documents.

Crowns↗
PubMed1998

Effects of repeated hand instrumentation on the marginal portion of a cast gold crown.

A study was conducted to evaluate the effects of repeated hand instrumentation on the marginal portion of a cast gold crown. Seven extracted periodontally diseased premolars were used. The finishing line of the preparation was placed on the root surface and then the crown was cast and cemented in the usual manner. One proximal surface of each sample was divided into 2 areas: root planing (RP) area and RP plus polishing (RPP) area. The marginal portion of the crown was measured to give a baseline value using a surface roughness- and profile-analyzing system. Then, the marginal portion was painted with a waterproof pen. RP was performed to remove paint in the RP area with the curets. In the RPP area, RP followed by polishing was done by silicone polishing points and a rubber cup with polishing paste. The relevant procedures and measurements were repeated 3 times in each area. Changes in the sample roughness and profile were evaluated and compared between the 2 techniques. The results showed that repeated instrumentation altered the surface of the marginal portion of the cast gold crown, resulting in increased roughness in both areas (P < 0.01). However, the roughness of the RPP area was considerably restored to the baseline value by polishing after RP. Therefore, it is suggested that polishing after RP smoothes the marginal portion of the cast gold crowns and appears to be an efficient prophylactic system.

Bicuspid↗
PubMed2006

The Carolina bridge: a novel interim all-porcelain bonded prosthesis.

UNLABELLED: Numerous bonded bridge designs have been advocated over the years for the temporary or permanent replacement of missing teeth. Both metal and all-porcelain designs of bonded bridges have been advocated, with varying degrees of success. However, all of these designs involve some degree of tooth preparation, making them irreversible in nature. The Carolina bridge, a novel all-porcelain bonded pontic, requires no significant tooth preparation, making it an outstanding option as an interim prosthesis. The key to success is the availability of adequate surface area interproximally to ensure optimally strong resin composite connectors. CLINICAL SIGNIFICANCE: This article describes the indications, contraindications, and clinical technique for the placement of an ultraconservative all-porcelain bonded bridge for the interim replacement of single incisors.

Composite Resins↗
PubMed1999

[Ready-made crowns in the deciduous dentition].

The following review of the literature on "prefabricated crowns for deciduous teeth" attempts to highlight the benefits and limitations of this treatment modality. The use of prefabricated crowns is indicated in the following situations: severe destruction of the clinical crown, deep approximal cavities, bilateral approximal cavities, circumferential caries, history of root canal treatment, and need for fixed space retention. Compared to amalgam restorations involving two or more surfaces, prefabricated crowns on deciduous molar teeth gave very high survival rates. They consist of a chromium-nickel-steel alloy and are reported to have an acceptable gingival tolerance profile. In contrast to the Anglo-American countries this treatment modality is quite uncommon in Germany. A probable reason for this reservation could be that many clinicians often fail to see the need for a filling in the deciduous dentition. Besides, many dentists are reluctant to use local anesthesia in children, which is inevitable in preparing and fitting a prefabricated crown. In the United States and UK dentists are less frequently confronted with this problem, as complex treatments are often carried out under nitrous oxide sedation or insufflation anesthesia. Modern filling materials have been introduced which have the potential to narrow the indications for prefabricated stainless steel crowns. Against this background, future studies are necessary to compare the survival rates of prefabricated crowns and modern filling materials.

Child↗