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At least 19 recordsLinked to original sources
PubMed1997

Enamel subsurface damage due to tooth preparation with diamonds.

In clinical tooth preparation with diamond burs, sharp diamond particles indent and scratch the enamel, causing material removal. Such operations may produce subsurface damage in enamel. However, little information is available on the mechanisms and the extent of subsurface damage in enamel produced during clinical tooth preparation. The aim of this study, therefore, was to investigate the mechanisms of subsurface damage produced in enamel during tooth preparation by means of diamond burs, and to examine the dependence of such damage on enamel rod orientation, diamond particle size, and removal rate. Subsurface damage was evaluated by a bonded-interface technique. Tooth preparation was carried out on two enamel rod orientations, with four clinical diamond burs (coarse, medium, fine, and superfine) used in a dental handpiece. The results of this study showed that subsurface damage in enamel took the form of median-type cracks and distributed microcracks, extending preferentially along the boundaries between the enamel rods. Microcracks within individual enamel rods were also observed. The median-type cracks were significantly longer in the direction parallel to the enamel rods than perpendicular to the rods. Preparation with the coarse diamond bur produced cracks as deep as 84 +/- 30 microns in enamel. Finishing with fine diamond burs was effective in crack removal. The crack lengths in enamel were not significantly different when the removal rate was varied. Based on these results, it is concluded that subsurface damage in enamel induced by tooth preparation takes the form of median-type cracks as well as inter- and intra-rod microcracks, and that the lengths of these cracks are sensitive to diamond particle size and enamel rod orientation, but insensitive to removal rate.

Dental Enamel↗
PubMed1999

Assessment of tooth preparation designs for posterior resin-bonded porcelain restorations.

Tooth preparation designs advocated for posterior resin-bonded porcelain restorations were evaluated for clinical application. This study examined the design of tooth preparations from stone dies for individual posterior resin-bonded porcelain onlays and complete porcelain crowns placed in a specialist practice, and compared features that provided retentive and porcelain fracture-resistance with those in the dental literature. Stone dies of tooth preparations for 57 onlay and 46 crown preparations were provided. Measurements were recorded for the tooth preparations with the aid of interocclusal silicone impressions. Proximal boxes, grooves and occlusal steps resulting from removal of amalgam restorations were common. These retentive features were more evident with onlays, and appeared larger on the distal than the mesial surfaces. Internal tooth preparation tapers or convergence angles were frequently greater than 20 degrees, leading to relatively-wide occlusal isthmus widths, especially for onlays. There were wide variations in occlusal surface reductions for the central fossae and supporting cusps. Tapers for tooth preparations were frequently more extensive, and occlusal surface reductions were often less than recommended. The implications of these differences for long-term clinical success should be resolved.

Adult↗
PubMed1980

Periodontal considerations in tooth preparation for crowns and bridges.

Correct tooth preparation and adequate reconstruction of the anatomy of the crown are essential to the maintenance and preservation of a healthy periodontium. Adequate tooth preparation requires careful attention to many details and clear knowledge of the features of the finished product. The anatomic reconstruction of the crown with a perfect marginal adaptation will provide an adequate environment for maintaining the health of surrounding periodontal tissues.

Crowns↗
PubMed2001

Tooth preparations for complete crowns: an art form based on scientific principles.

STATEMENT OF THE PROBLEM: No recent literature has reviewed the current scientific knowledge on complete coverage tooth preparations. PURPOSE: This article traces the historic evolution of complete coverage tooth preparations and identifies guidelines for scientific tooth preparations. MATERIAL AND METHODS: Literature covering 250 years of clinical practice was reviewed with emphasis on scientific data acquired during the last 50 years. Both a MEDLINE search and an extensive manual search were used to locate relevant articles written in English in the last 50 years. RESULTS: Teeth should be prepared so that they exhibit the following characteristics: 10 to 20 degrees of total occlusal convergence, a minimal occlusocervical dimension of 4 mm for molars and 3 mm for other teeth, and an occlusocervical-to-faciolingual dimension ratio of 0.4 or greater. Facioproximal and linguoproximal line angles should be preserved whenever possible. When the above features are missing, the teeth should be modified with auxiliary resistance features such as axial grooves or boxes, preferably on proximal surfaces. Finish line selection should be based on the type of crown/retainer, esthetic requirements, ease of formation, and personal experience. Expectations of enhanced marginal fit with certain finish lines could not be validated by recent research. Esthetic requirements and tooth conditions determine finish line locations relative to the gingiva, with a supragingival location being more acceptable. Line angles should be rounded, and a reasonable degree of surface smoothness is desired. CONCLUSIONS: Nine scientific principles have been developed that ensure mechanical, biologic, and esthetic success for tooth preparation of complete coverage restorations.

Bicuspid↗
PubMed1998

Temperature response in the pulpal chamber during ultrahigh-speed tooth preparation with diamond burs of different grit.

STATEMENT OF PROBLEM: Ultrahigh-speed tooth preparation can traumatize the hard dental tissues and the dental pulp. PURPOSE: This in vitro study examined the relationship between different grits of diamond burs on the temperature response within a pulpal chamber during tooth preparation with a turbine. MATERIAL AND METHODS: Newly extracted, undamaged third molars were secured by a rapid-tensioning device mounted on an air-supported slide. NiCrNi thermocouples were inserted apically and used to determine the temperature within a pulpal chamber. The grinding tests used cylindrical fine, coarse, and ultracoarse diamond burs. RESULTS: The maximal temperature elevation within the pulp was 3.2 degrees C, and the most pronounced rise in temperature occurred with ultracoarse burs. Temperature increases in the pulpal chambers and grinding times or temperatures of the cooling water were approximately proportional. Residual dentinal thickness was inversely proportional to temperature elevation within the pulpal chamber. CONCLUSIONS: This study demonstrated that coarse diamond burs resulted in more pronounced temperature increases within the pulpal chamber during tooth preparation. In addition, the benefit of short intervals between grinding steps and a cooling water temperature between 30 degrees C and 32 degrees C was confirmed. A cooling temperature of 38 degrees C to 43 degrees C did not afford actual cooling.

Body Temperature Regulation↗
PubMedDate not supplied

The effects of tooth preparation on pressure measured in the pulp chamber: a laboratory study.

PURPOSE: The purpose of this study was to determine pressure changes in the pulp space during tooth preparation with either diamond or tungsten carbide burs in a high-speed dental handpiece in the laboratory. MATERIALS AND METHODS: Twenty premolar teeth were collected and randomly assigned to two groups: group 1 received preparation with diamond burs and group 2 with tungsten carbide burs. The teeth were mounted on a pressure transducer and the pulp chambers were filled with saline. A 0.1-mm thickness of tooth tissue was removed from the proximal surface of each tooth, alternating dry and wet cutting, until the pulp chamber was exposed. Pressure and temperature changes were recorded during tooth preparation. RESULTS: At 0 to 1 mm of remaining dentin depth dry cutting with diamond and tungsten carbide burs generated a mean positive pulpal pressure of 12 kPa and 6 kPa, respectively. Wet cutting under the same conditions produced 0.6 kPa and 0.15 kPa, respectively. The difference between wet and dry cutting was highly significant (P < 0.001). Diamond burs produced significantly higher pressure increases than carbide burs at all levels for both wet and dry techniques (P < 0.05). When cutting farther than 2 mm from the pulp, tooth preparation created a mean 0.09-kPa pressure increase, which was not influenced by either coolant use or bur type. The temperature change was minimal during wet cutting and only minor temperature increases were recorded during dry cutting. CONCLUSION: From this laboratory study it is concluded that significant pressure changes occur in the pulp chamber during tooth preparation of extracted teeth when the remaining dentin thickness is less than 2 mm.

Body Temperature↗
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↗
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↗
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↗