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At least 37 records · Page 2Linked to original sources
PubMed1997

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↗
PubMed2003

A comparison of the depths produced using three different tooth preparation techniques.

STATEMENT OF PROBLEM: Inadequate preparation of teeth for metal ceramic crowns can significantly influence the ultimate form and longevity of the definitive restoration, as well as adversely affect the supporting tissues. PURPOSE: The purpose of the study was to determine the effect that 3 different tooth preparation techniques had on an operator's ability to appropriately and consistently prepare teeth for metal ceramic crowns. MATERIAL AND METHODS: Thirty typodont maxillary central incisor teeth were mounted individually and randomly allocated to 3 equal groups (A, B, and C). One operator was asked to prepare each tooth for a metal ceramic crown. A freehand approach was used to prepare the teeth in Group A, which acted as a control. Groups B and C were prepared with the assistance of a silicone index and a suitable depth gauge bur, respectively. A silicone index of the unprepared tooth, into which contrasting silicone was injected to occupy the space created by tooth preparation, was sectioned in the midline. Images of the sectioned index were captured with an optical microscope (resolution +/- 0.02 mm), which was attached to a personal computer. A calibrated image analysis program was used to measure the depth of preparation (in millimeters) at 5 points (labial cervical, mid-labial, incisal, mid-palatal, and palatal cervical) on 2 occasions. These results were pooled and averaged to give a mean labial and palatal preparation depth (in millimeters) and incisal edge reduction. The data were analyzed by use of a 1-way analysis of variance and Scheffe's post hoc statistical test (P<.05). RESULTS: The mean depths of labial and palatal preparation for Groups A, B, and C were 1.28 and 0.47 mm; 1.46 and 0.56 mm; and 1.45 and 0.63 mm, respectively. The difference between the groups' labial preparation depth was not significant (P=.06), but the difference for palatal preparation depth was significant (P=.01). The mean incisal reduction was 3.00 mm for Group A, 2.74 mm for Group B, and 2.13 mm for Group C (P=.00). CONCLUSION: Within the limitations of this study, it was concluded that preparation of teeth for metal ceramic crowns without the use of devices to help gauge reduction depth can result in insufficient labial reduction and incisal overreduction.

Analysis of Variance↗
PubMed1990

Effects of the temperature of cooling water during high-speed and ultrahigh-speed tooth preparation.

In vitro measurements of heat production in the pulp chamber during tooth preparation were performed on intact third molars. The experiments were designed to simulate physiologic temperature conditions in the tooth and oral cavity and to standardize parameters of tooth preparation. Two drive systems, the turbine and the high-speed angle, were compared by using two ranges of cooling water temperature. The critical temperature of 41 degrees C to 42 degrees C that is irreversibly harmful to pulpal tissue was not reached with a cooling water temperature of 30 degrees C to 34 degrees C. Because the temperature elevation during turbine preparation was dependent on the diminishing thickness of remaining dentin, in preparing teeth close to the pulp, a high-speed angle was advantageous.

Dental Cavity Preparation↗
PubMed1999

Comparison of resin-bonded prosthesis groove parallelism with the use of four tooth preparation methods.

STATEMENT OF PROBLEM: A precise preparation is required to develop resistance form resulting in mechanical stability of the framework for resin-bonded prostheses (RBPs). PURPOSE: The effects of 4 methods of tooth preparation (freehand, guiding pin, extraoral parallelometer, and intraoral parallelometer) on the deviation of proximal grooves from a preestablished path of insertion (guide planes) were investigated under clinical conditions. MATERIAL AND METHODS: Tooth preparation of proximal grooves was performed by 32 dentists on resin substitutes of posterior segments intraorally with a single test patient. A Latin-square randomized cross-over design was selected as the experimental design. RESULTS: The significant least angular deviation of proximal grooves from path of insertion was achieved with an intraoral parallelometer (mean +/- SD 3.15 +/- 1.67 degrees). Compared with freehand tooth preparations (4.37 +/- 2. 11 degrees), neither use of a guiding pin (4.10 +/- 1.62 degrees) nor an extraoral parallelometer (5.06 +/- 2.33 degrees) improved the results. CONCLUSION: Divergence of guiding grooves from path of insertion was reduced with the use of an intra-oral parallelometer. This should improve mechanical stability of posterior RBPs.

Acrylic Resins↗
PubMedDate not supplied

[Guided impression in tooth preparation for the application of full veneer crowns].

In this study the authors emphasize the importance of the guiding impression for checking the depth of the tooth preparation for full veer crowns. For this purpose they took two impressions in heavy-body silicone before any tooth preparation was made. One of these impressions was cut from the buccal to the lingual aspect across the middle of the imprint of the tooth to be prepared. The other one was cut horizontally in a cervical and an occlusal half. We kept and repositioned from time to time over the preparation in order the distal half of the first impression and the cervical half of the second one to check for the adequate tooth reduction. This method of checking the tooth reduction is useful especially for undergraduates and young practitioners and has better results than the articulation paper.

Crowns↗
PubMed2004

Designing tooth preparations for optimal success.

The form of prepared teeth and the amount of tooth structure remove dare important contributors to the mechanical, biologic,and esthetic success of the overlying crown or fixed partial denture.Therefore, it is important to develop clinical guidelines that can be used to optimize success in fixed prosthodontics.

Crowns↗
PubMed1990

[A study on tooth preparation by means of the newly developed parallelometer and its educational effect, with primary regard to convergence angles of abutment tooth].

Proper tooth preparation is one of the fundamental requirements in crown & bridge prosthodontics. However, it is difficult for students in particular to prepare adequate convergence angles of abutment tooth in the limited environment of patient's mouth. Therefore, the parallelometer was developed to improve the preparations as a supplementary device which informs the person by a signal of alarming simultaneously when a bur is not properly installed to convergence angles of abutment tooth. Sixty subjects were selected from students of Kanagawa Dental College and they were divided into two groups (A and B) to prepare abutment tooth of lower right 1st molar for full cast crown on typodont mounted into the manikin. A preliminary training was performed for once without the parallelometer for group A and with it for group B prior to a comparative experiment. The following results were obtained with primary regard to convergence angles of abutment tooth. 1. Related to each of four convergence angles, group B is superior to group A in all mean values with a statistical significance (P less than 0.01). 2. Related to a total of four convergence angles by the maximum number of subjects, group B is also superior to group A in a mean value by about ten degrees. 3. A newly developed parallelometer proved to be an efficient supplementary device for training of students to master a technique of preparation for adequate abutment tooth.

Crowns↗
PubMed1994

Tooth preparation and fabrication of porcelain veneers using a double-layer technique.

This article discusses proper tooth preparation when using the double-layered porcelain technique for constructing porcelain veneers designed to produce strength and translucency. Indications for this technique include color correction, restoration of lost tooth structure or improper tooth size, and overall smile design. A new indication--misalignment--has been added. The objective of this article is to review tooth preparation and double-layered laboratory techniques using hydrothermal ceramics in combination. Four cases are used to illustrate the procedure, concentrating on the correction of misaligned teeth.

Dental Bonding↗
PubMedDate not supplied

Metal ceramic crowns--a review of tooth preparation.

The metal ceramic crown has become the most popular extra-coronal restoration in the armamentarium of the dentist, certainly within the UK. It combines the aesthetic qualities of porcelain with the strength of cast metal. This review discusses a number of issues relating to these crowns, and considers the principles of tooth preparation and marginal fit. The physical requirements of tooth preparation are considered in terms of shoulder width, emergence profile, shoulder angle and effects on the pulp. It also considers the teaching of metal ceramic crown preparation, the failure of metal ceramic crowns and the influence that preparation quality has on these failures.

Crowns↗
PubMedDate not supplied

The effect of tooth preparation design on the breaking strength of Dicor crowns: Part 1.

Six maxillary first premolar all-ceramic tooth preparation designs were tested for their effect on the strength of Dicor crowns. Ten crowns were fabricated for each preparation design, and their breaking strengths were measured. Three finish line designs (1.2-mm shoulder with sharp axiogingival line angle, 1.2-mm shoulder with rounded axiogingival line angle, and 0.8-mm chamfer) and two total occlusal convergence angles (10 degrees and 20 degrees) were tested. All preparations possessed 2.0 mm of occlusal reduction. The average breaking strengths of the 10 Dicor crowns were compared to that of 10 metal ceramic control restorations. The tooth preparation with a 1.2-mm shoulder finish line, sharp axiogingival line angle, and 10 degrees of total occlusal convergence produced the strongest Dicor crowns (88.6 kg). The weakest restorations were observed when a 0.8-mm chamfer finish line (66.8 kg) was used. The metal ceramic restorations were significantly stronger (247.45 kg) than the strongest Dicor crowns (88.6 kg).

Ceramics↗
PubMed2005

Assessment of convergence angles of tooth preparations for complete crowns among dental students.

OBJECTIVES: Convergence angles for complete crown preparations have been recommended at 4-12 degrees . However, practitioners have difficulty meeting these recommendations. This study measured and compared the convergence angles of tooth preparations for complete crowns prepared at three Colleges of Dentistry: the University of Tanta, Egypt, King Abdulaziz University, Saudi Arabia, and The Ohio State University, Columbus, Ohio. METHODS: The convergence angles of 499 tooth preparations for complete crowns were evaluated. These comprised of a random sample of 262 teeth prepared by third-year dental students at the University of Tanta on extracted molars under normal preclinical conditions, 37 preparations on molar teeth on typodonts done by first-year dental students. The Ohio State University and 200 molar typodont complete crown preparations done by fourth-year dental students at King Abdulaziz University, Saudi Arabia. The bucco-lingual and mesio-distal convergence angles of each preparation were measured with a goniometer microscope. Mean convergence angles were calculated, and differences between groups were tested for statistical significance with analysis of variance (ANOVA) at 5% level of confidence. RESULTS: Convergence angle measurements were significantly different between the groups and the dimensions (P<0.001). The greatest convergence value (19.8+/-10.0) was for bucco-lingual measurements prepared by Egyptian dental students. The smallest convergence value (14.1+/-3.8) was for mesio-distal measurements prepared by Saudi dental students. CONCLUSIONS: This study emphasized the difference between what is taught at dental schools (what is theoretically possible) and the school results of actual practice. There was a considerable disparity between the convergent angles recorded in this study and the ideal configurations recommended in fixed prosthodontic textbooks and the dental literature.

Crowns↗
PubMed1995

A study on prevention of hospital infection control caused by tooth preparation dust in the dental clinic. Part 1. Preventive measures against environmental pollution in the dental clinic caused by microbial particles.

Tooth preparation dust, an indispensable part of dental treatment, contains bacteria and viruses. In order to examine environmental pollution in the dental clinic during tooth preparation, we monitored microorganism spread by counting colony forming units (CFU) with the "Andersen Microbe Sampler." This test was conducted in a "Clean Booth." Mitis-salivarius medium was used to count the oral-streptococcus species. The ability of the "Extra-Oral Vacuum Aspirator (EOVA)" to effectively eliminate contamination was also tested, and the EOVA was found to reduce the spread of oral-streptococci, significantly. The EOVA was therefore viewed as an effective method for reducing air pollution in the dental clinic, and should be used when treating patients with certain infectious diseases.

Air Microbiology↗
PubMedDate not supplied

Predictable, precise, and repeatable tooth preparation for porcelain laminate veneers.

Advances in dental materials and techniques have enabled porcelain laminate veneers to evolve into the treatment of choice for minimally invasive aesthetic dentistry. Treatment planning and tooth preparation are crucial for optimal function and aesthetics. While minimal invasion is important, sufficient space must be provided for the appropriate porcelain buildup. Various preparation guidelines have been advocated for porcelain veneers, yet they vary in accuracy and by indication. This article provides a simple, precise technique for veneer preparation regardless of tooth position and condition.

Dental Porcelain↗
PubMed1998

New paradigms for anterior tooth preparation. Rationale and technique.

A biologic and esthetic rationale has been presented along with a simplified controlled technique to achieve predictable results (Figures 13A and 13B). The clinician is constantly faced with the challenge of developing room for esthetic material while preserving the biologic objectives. Using the three essential anterior tooth preparation keys (incisal edge, reduction requirements, and the biologic zone) enhances predictability. Developing the incisal edge relative to the dynamics of facial esthetics provides the initial starting point of tooth preparation. The reduction requirements are designed to satisfy the mechanical principles, address the pulpal concerns, and preserve the structural requirements of the tooth. The biologic zone can be developed by using the total dentogingival complex measurements and will clinically aid in the determination of cervical limitations to providing intracrevicular margin location.

Humans↗
PubMed2005

Influence of tooth preparation design on the stress distribution in maxillary central incisors restored by means of alumina porcelain veneers: a 3D-finite element analysis.

AIM: The present study aimed at providing 3D-FEA engineering tools for the understanding of the influence of tooth preparation design on the stress distribution and localization of critical sites in maxillary central incisors restored by means of alumina porcelain veneers under functional loading. METHODS: A 3D-FEM model of a maxillary central incisor is presented. An arbitrary chewing static force of 10 N was applied with an angulation of 60 and 125 degrees to the tooth longitudinal axis at the palatal surface of the crown. The model was considered to be restored by means of alumina porcelain veneers with different tooth preparation designs. The differences in occlusal load transfer ability of the two restorative systems are discussed. RESULTS: The maximum Von Mises equivalent stress values were observed in the window restorative system for both 125 and 60 degrees load angulations. When the chamfer with palatal overlap preparation was simulated, the stress distributed uniformly in the cement layer, whereas in the window preparation the stress mainly occurred in the incisal area of the cement layer. SIGNIFICANCE: When restoring a tooth by means of porcelain veneers, the chamfer with palatal overlap preparation better restores the natural stress distribution under load than the window technique.

Aluminum Oxide↗
PubMed1997

Tooth preparation and pulp degeneration.

Conscious attention must be directed toward providing atraumatic tooth preparations for crowns, and to constructing adequate provisional restorations. If meticulous care is not taken, pulpal damage or death can occur. Patients should be warned that pulpal death and endodontic therapy can result from crown placement.

Burns, Chemical↗
PubMed1989

Tooth preparation for porcelain laminates.

A simple controlled technique is suggested for porcelain laminate tooth preparation that promotes exact tooth reduction and length which insures the maximum esthetic results.

Dental Cavity Preparation↗