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At least 109 records · Page 6Linked to original sources

PubMed2002

The accuracy of dual-arch impressions: a pilot study.

STATEMENT OF PROBLEM: Dual-arch impression trays often are used for addition silicone final impressions of fixed prosthodontic preparations, but concerns about distortion of the impression are common because such trays lack rigidity. PURPOSE: This in vitro pilot study was designed to determine the accuracy of addition silicone impressions made with custom trays or made with either passive or stressed dual-arch trays. MATERIAL AND METHODS: Complete crown preparations of a mandibular molar, premolar, and incisor were made on a dentoform. These tooth preparations received flat, parallel indexes on the facial and lingual axial walls for accurate and reproducible positioning of a digital caliper. Gypsum dies were produced with an addition silicone impression material in either custom trays or dual-arch trays seated passively or with induced flexure (3 dies per tray group). The facio-lingual dimensions of the dies were measured with a digital caliper accurate to +/-5 microm and compared to the dimensions of the original preparations. Flexure in the latter group was induced by contact of the tray with a simulated torus, made of resin, in the lingual vestibule of the dentoform. Data were analyzed with 2-way analysis of variance and Tukey's multiple comparison test (alpha=.05). RESULTS: Dies fabricated with either the custom or passive dual-arch tray reproduced the facio-lingual dimensions of the preparations within a -27 to +13 microm range. Dies fabricated with the flexed dual-arch tray exhibited greater discrepancy, in the range of -47 to -67 microm relative to the preparations. Tray type was a significant factor (P=.002): the flexed tray group was significantly different than the other 2 groups, which did not differ from each other. CONCLUSION: Within the limitations of this pilot study, dual-arch impressions were comparable in accuracy to impressions made with custom trays. Accuracy was reduced, however, when the trays were flexed during closure of the arches.

Acrylic Resins↗

PubMed1996

The use of removable partial dentures amongst private dental practitioners in Singapore.

A questionnaire survey was carried out in 1995 amongst university trained general dental practitioners in the city state of Singapore to assess the use of removable partial dentures (RPD). 37% of the original sample of 469 completed and returned the questionnaire. The results of this survey indicate that RPDs are a common treatment modality in Singapore. Acrylic partial dentures appear to be the preferred choice for RPD treatment. The work profile of those who had a postgraduate qualification in removable prosthodontics did not differ from that of the general dental practitioner.

Acrylic Resins↗

PubMed2001

Vital pulp therapy with bipolar electrocoagulation after intentional pulp exposure of fixed prosthodontic abutments: a clinical report.

A clinical protocol is described for the treatment of intentional and unavoidable exposed pulps during crown preparation. The protocol includes a definitive cavity preparation to create space in the exposed dentin for an adhesive pulp barrier; procedures to develop the highly desirable hybrid zone to prevent microleakage; the use of a specific resinous material that serves as a long-term pulp barrier with a relatively neutral and biocompatible impact on the pulp; and the use of precise bipolar electrocoagulation to provide durable hemostasis for restoration of the pulp wall and a relatively clot-free surgical wound to facilitate healing. The protocol involves the application of gentle surgical and restorative procedures to support the inherent healing process to restore the health of the pulp. The patient presented was part of a larger investigation and was selected in an attempt to identify a fixed prosthodontic application of the proposed pulp therapy protocol.

Acrylic Resins↗

PubMed1999

Long-term survival characteristics of 832 resin-retained bridges and splints provided in a post-graduate teaching hospital between 1978 and 1993.

The clinical performance of 832 resin-retained bridges and splints provided in the adult fixed prosthodontic clinic of a post-graduate teaching hospital was reviewed. Recall data was available for 58.4% of cases and the median survival was 7 years and 10 months. Analysis of clinical variables influencing survival revealed that the design and retainer coverage were significant factors. The experience of the operator carrying out treatment also had a pronounced effect which was not readily explained in terms of the distribution of other significant factors. Resin-retained restorations made with minimal tooth preparation are shown to be capable of extended clinical service and their failure rarely resulted in adverse consequences for the patient. Patient satisfaction with their treatment was reportedly high.

Adolescent↗

PubMed1997

An alternative method for direct custom tray construction using a visible light-cured resin.

The use of a properly made tray is highly desirable for impression making. To avoid the extra time required for tray fabrication, the alternative techniques of the putty wash or "reline" technique and intraoral fabrication of a custom tray by relining a stock tray with self-curing resin are proposed. This article illustrates a new technique of direct custom tray fabrication used for impression making for fixed prosthodontics. The proposed technique allows the direct fabrication of custom trays with light-cured resin and is time-saving, efficient, and inexpensive.

Acrylic Resins↗

PubMed1996

The C-POST system.

This article represents a clinical report from daily experience with the C-POST system, a carbon-fiber post for core build-up. The C-POST was invented in France in 1988 and introduced in Sweden in 1992. When I first started using the system, little literature about it had been published. Because the C-POST fits well in the modern bonding concept, it has become my therapy of choice. In my practice, more than 900 treated teeth have been registered in a computer so that treatment progress can be followed. Every treated tooth was registered according to the type of primer, cement, core material, number of posts, and type of prostheses used. The prosthetics included large composite fillings, porcelain crowns, and/or metal crowns or bridges from 3 to 12 units. Of the 900 treated teeth, 173 of them are between 3 and 4 years old, 2 contain fractured roots, and 1 had a post fracture. This article describes how to fabricate a C-POST core build-up and contains clinical hints and advice. Other applications for the post, such as splinting, bridges, and repair of fixed prosthodontics and vital teeth, are discussed.

Carbon↗

PubMed2005

Trends in indirect dentistry: 2. post and core restorations.

Modern post preparation techniques reflect a change from what was once considered a prosthodontic procedure to one which marries endodontic principles with sound understanding of mechanical objectives. This article presents a rationale for techniques in materials selection and post-space preparation. A review of literature is presented and practical clinical guidelines are suggested when post placement is considered the treatment of choice.

Crowns↗

PubMedDate not supplied

Influence of posts and cores on light transmission through different all-ceramic crowns: spectrophotometric and clinical evaluation.

PURPOSE: The influence of different types of posts and cores on light transmission through all-ceramic crowns was assessed by spectrophotometric analysis and clinical evaluation. MATERIALS AND METHODS: Three extracted natural teeth were replicated in acrylic resin, with roots prepared to receive standardized posts and cores. Using a silicone impression material as a template, various prosthodontic reconstructions were obtained by combining four types of posts and cores (polished and matte-finished gold alloy, all-ceramic, and ceramized metal alloy) and three types of all-ceramic crowns (IPS-Empress 2 surface-colored, IPS-Empress 2 stratified, and In-Ceram). The spectrophotometric analysis was performed in the dark at 25 degrees C. The teeth were backlit with an incandescent lamp at the color temperature of A illuminant and shielded to avoid spurious light entering the spectrophotometer. The transmitted light was analyzed in terms of luminance at four points of the sample surface (cervical, middle, incisal, and proximal). Twelve measurements were performed for the natural teeth, and 144 were performed for the artificial teeth. RESULTS: Natural teeth had the highest luminance. Among all-ceramic crowns, surface-colored IPS-Empress 2 had the highest luminance, and stratified IPS-Empress 2 had the lowest. Regarding posts and cores, the luminance was highest with the all ceramic, lower with the ceramized and the polished gold alloy (which had very similar luminance), and lowest with the matte-finished gold alloy. No significant difference among prosthodontic combinations was detected under clinical observation. CONCLUSION: The surface-colored glass ceramic (IPS-Empress 2) was the most translucent crown. At the standard crown thickness used, there were small, significant spectrophotometric, but not clinical, differences among the combinations tested. These findings show no esthetic contraindications for the use of polished gold alloy posts and cores with all-ceramic crowns.

Acrylic Resins↗

PubMed1998

Nontraumatic immediate complete denture placement: a clinical report.

This clinical report presents a treatment procedure that makes immediate denture placement a more predictable and less stressful procedure. It provides greater control over the prosthodontic aspects of denture delivery by the restorative dentist, and the convenience of performing the placement procedures in a clean, blood-free environment. The delivery of the prosthesis is less traumatic because extractions and/or surgery are deferred. In addition, by the time the remaining roots are extracted, all denture adjustments will have been made and the patient will have accommodated to the prosthesis.

Denture Design↗

PubMed2004

The use of sectional impressions and a transfer index for extensive fixed prosthodontic treatment.

The philosophy of positioning the margins of crowns supragingivally may not be applicable with the presence of caries, erosion, abfraction (noncarious cervical lesion), short clinical crown length, or esthetic concerns. In such situations, it is essential not only to record precise subgingival details of all of the prepared teeth but also to accurately transfer them to a working master cast. If a patient presents with oral and/or gingival conditions that compromise the clinician's ability to obtain a single full-arch impression for extensive fixed restorations, a technique using sectional impressions, an intraoral transfer index, and a transfer impression for transfer dies will play a vital role in the patient's treatment.

Crowns↗

PubMed2003

Gingival prostheses--a review.

Gingival replacement is often a component of comprehensive prosthodontics. Gingival prostheses may be fixed or removable and may be made from acrylics, composite resins, silicones or porcelain-based materials. Undercuts or dental attachments are used to secure removable prostheses, which are esthetically pleasing and easy to maintain. This paper describes several clinical situations in which gingival prostheses were used effectively.

Acrylic Resins↗

PubMedDate not supplied

Resin-bonded fixed partial dentures: ten-year follow-up.

PURPOSE: The aim of the study was to evaluate the survival rate of resin-bonded fixed partial dentures delivered between 1993 and 2003 in the Department of Prosthodontics of the University of Turin and in several private practices. MATERIALS AND METHODS: The analysis took into consideration the following variables: preparations, metallic alloys, metal preparation and conditioning of the inner surfaces, isolation during cementation, type of cement, kind of prostheses, number of abutments, and number of missing teeth included in the prostheses. RESULTS: The estimated survival probability for the first debonding or failure was 85% after 5 years and 71% after 10 years. CONCLUSIONS: The use of dental dam during cementation reduced the risk of debonding. No differences in survival rate were found for the other parameters.

Cementation↗

PubMed1996

The aesthetic guidelines of the mucogingival complex for fixed prosthodontics.

Until the 1980s, aesthetic dentistry focused its attention primarily on the replication and improvement of tooth structure by developing modifications of porcelain-fused-to-metal crown restorations, incorporated in porcelain systems in combination with adhesive technology. The introduction of new, improved, or modified periodontal surgical techniques addresses nearly all mucogingival challenges, except for the loss of papillae. Therefore, it is of critical importance to develop and define aesthetic guidelines for treatment of the mucogingival complex. In these guidelines, the aesthetic analysis of a treatment is divided into an evaluation of the mucogingiva and that of the tooth structure. Correction of mucogingival discrepancies is a prerequisite for aesthetic success in dental treatment. The learning objective of this article is to review the mucogingival discrepancies and examine a variety of potential solutions.

Adolescent↗

PubMed1999

Effective taper criterion for the full veneer crown preparation in preclinical prosthodontics.

PURPOSE: Effective taper criteria must define a realistic, measurable goal that the student can visualize and achieve. Six degrees is widely accepted as the taper criterion for the full veneer crown preparation. However, studies show the actual taper of most preparations to be greater than 12 degrees. The purpose of this study was to determine whether 12 degrees is an effective taper criterion for the full veneer crown preparation in preclinical prosthodontics instruction. MATERIALS AND METHODS: A group of 191 full veneer crown preparations with 6 degrees as the taper criterion, and a group of 130 full veneer crown preparations with 12 degrees as the taper criterion were evaluated. All preparations were accomplished by preclinical dental students working on typodonts under examination conditions. RESULTS: The overall mean taper for each group exceeded the targeted criterion. The overall mean taper for the 6 degrees group was 14,490. When 12 degrees was the criterion, the overall mean taper was 15,580. The t test results indicate significant differences (p < .0001) between the targeted criterion and the actual preparation mean taper in all samples except one: the faciolingual measurements in the 12 degrees group. The faciolingual measurement of 12,920 was not statistically significantly different (.0542) from the targeted criterion of 12 degrees. CONCLUSION: The use of a 12 degrees taper criterion did not result in preclinical students achieving the goal of a 12 degrees taper. However, a 12 degrees criterion is more realistic than a 6 degrees criterion for full veneer crown preparations.

Crowns↗

PubMed2006

Internal adaptation of fixed prosthodontics at shoulder preparation level evaluated by horizontal sections.

AIM: The precision of fixed prosthodontic restorations is fundamental for clinical success: well-fitting crowns reduce the risk of recurrent caries and periodontal disease. The aim of this study is to evaluate the internal fit of fixed prosthodontics at the shoulder preparation level by examining horizontal sections. METHODS: Twenty-four extracted teeth were resin-embedded and prepared on the platform of an iso-parallelometer with a 90 degrees shoulder with a rounded internal angle. Auro Galva Crown (AGC) copings were cemented in place. The preparations were observed by 3 different assessors at 8 points, first externally and then internally at 2 levels by grinding the specimen perpendicular to the long axis at 0.5 mm and at 0.2 mm from the margin of the preparation. A correction factor was calculated to derive real values from measured values. The results were analyzed using a linear regression with robust standard errors, accounting for within-subject correlation introduced by multiple measurements. Shrout-Fleiss Intraclass Correlation Coefficient (ICC) for Inter-Rater Reliability were calculated at each stage. RESULTS: Internal measurements at 0.5 and 0.2 mm from the margin provided data similar to the external margin data. Average inter-assessor differences were in the range of 2 mm. ICC ranged from 0.93 for the 0.5 mm level to 0.97 for the external level. CONCLUSIONS: External measurements effectively predict the internal precision at the shoulder level. Horizontal perimarginal sections allow the fit to be studied through the evaluation of a great number of points. Traditional vertical sections for the evaluation of internal fit enable only a few points to be observed. This internal observation method may be suitable for testing new materials.

Humans↗

PubMed1997

A long-term study of transverse stability of maxillary teeth in patients with unilateral complete cleft lip and palate.

The aim of this study was to investigate the long term post-treatment transverse stability of the maxillary dental arch in subjects with unilateral complete cleft lip and palate (UCLP) treated by the Harvold/Bøhn method of orthodontic expansion and prosthodontic retention. The treatment of 22 consecutive patients, primarily operated on during the period 1957-60, was completed at a mean age of 18.1 years by the provision of a fixed partial retention prosthesis across the cleft using the cleft side central incisor and canine only as abutment teeth. The cleft side lateral incisor was missing in each case. Dental casts were made at the time of abutment preparation and at six subsequent times with the final observation 13.5 years after treatment completion. Measurements of any shift in the transverse position of cleft side and non-cleft side canines, premolars and first molars were made on standardized photographs of the casts. A constructed anteroposterior palatal line served as 'midline' reference. A mean reduction of width at the final observation, as recorded from the palatal surface to the reference line, was for the cleft side canine: -0.4 mm, the premolar immediately distal to the prosthesis and the first molar: both -1.2 mm. The corresponding mean width reductions on the noncleft side were: canine -0.9 mm, premolar -1.2 mm, first molar -1.6 mm. The rate of movement towards the midline decreased linearly with In(time) for all variables (P < 0.02) but for the cleft side canine.

Adolescent↗

PubMed2006

Reducing subjectivity in the evaluation of pre-clinical dental preparations for fixed prosthodontics using the Kavo PrepAssistant.

The evaluation of pre-clinical technical achievement in fixed prosthodontics cannot be objective when using visual examination of dental preparations. This is, however, still the main method used in dental schools. The present study introduces a new method, based on a mathematical formula, to reduce the problem. The idea emerged when using the Kavo PrepAssistant system (software version 1.05). This system is a 3D-scanner with software that can quantify geometrical differences between an instructor and student dental preparation in model teeth. Therefore, a mathematical formula was created, integrating selected clinically relevant geometric characteristics of dental preparations measured by the system. In this new formula, 70% of the evaluation parameters were computer analysed, whilst 30% were visually evaluated. This new method was compared with the traditional visual evaluation system during a pre-clinical practical examination, with the participation of 25 students. Using both methods to evaluate the 25 preparations, results showed similar grading for both methods (K-S test = 0.16; P < 0.05). Although this method does not provide overall clinical evaluation of student performance these results suggest that it can be helpful accessing technical achievement. In this method, the student has the guarantee that 70% of his/her grade results from an objective computer evaluation, with the possibility to visualise the mistakes with the software. It also reduces problems related to the calibration between different examiners. The Kavo PrepAssistant is a powerful tool in pre-clinical teaching, but has some drawbacks. It has to be developed towards the actual needs of pre-clinical departments, in order to achieve its full potential, as described in this study.

Computer-Aided Design↗

PubMed2000

Fit of titanium and a base metal alloy metal-ceramic crown.

STATEMENT OF PROBLEM: Titanium has been widely used in dental implantology. However, problems remain for use of titanium in prosthodontics. PURPOSE: This study evaluated the marginal and inner fit of metal-ceramic restorations and frameworks made with a nickel-chromium alloy (Remanium CS) and a commercially pure titanium (Rematitan). Fit was compared with SEM before and after firing of ceramic materials. MATERIAL AND METHODS: Sixteen metal frameworks were cast with each casting material, 8 frameworks were used directly to evaluate measurements for fit (RCS: Remanium CS frameworks and TI: Rematitan frameworks). Porcelain was applied on the other 8 frameworks (RCSP: Remanium CS-porcelain and TIP: Rematitan-porcelain), fired, and then the fit was measured. Measurements were recorded at 3 points for marginal fit evaluation and at 3 points for inner fit. RESULTS: Significant differences were recorded among the occlusal (JK) values of groups tested (P <.05). Marginal fit and inner fit of Remanium CS frameworks were better than Rematitan frameworks. However, there were no substantial differences detected among groups after firing the ceramic superstructures. CONCLUSION: The fit of the base metal alloy metal-ceramic crowns was better than the commercially pure titanium metal-ceramic crowns. However, both artificial crowns were clinically acceptable.

Analysis of Variance↗