Tooth preparation is a common operation in dental clinical practice. This procedure is irreversible and invasive from the point of view of tooth preservation. Conditions of the abutment tooth, treatment methods, and restoration materials for target restoration affect tooth preparation. To achieve the goals of tooth tissue preservation, dental pulp protection, and periodontal health, dentistry professionals agreed on the importance of minimizing the amount of tooth reduction. The foundations for realizing this consensus are as follows. First, the available restoration materials with improved comprehensive performance need less target restoration space. Next, teeth can be prepared under a digital guide, and the real-time measurement of restoration space can be verified due to the invention of digital technologies for the analysis of the quantity and shape of the prepared tooth and tooth measurement. Moreover, guiding methods for preparation have been developed from freehand operation under the naked eye based on accumulated personal experience to digital-guidance jointing microscope. These innovations indicate the creation of a prototype of guided prosthodontics that is precise and applies real-time measurement throughout the process of tooth preparation. From the perspective of the evolution of digital, guided, and micro prosthodontics, this article raised seven questions about the numerical value and quantitative data transfer of tooth preparation and evaluated the authenticity of existing numerical requirements from the perspective of the four elements of measurement. Identifying unified measuring methods and developing measuring tools with a precision of hundred or ten microns will be the key to solving the problem about the authenticity of numerical measurement. Furthermore, this paper summarizes the methods of how to control tooth reduction and explains in depth why the currently dominant tooth preparation technology, which is based on empiricism, cannot effectively achieve the goals in digital prosthodontics. Therefore, we strongly call for rebuilding the digital foundation of prosthodontic treatment immediately.
Prosthodontics ; Tooth ; Tooth Preparation

The target restoration space (TRS) is a required tooth space that should be occupied by an esthetically formed and optimally functioned crown, veneer, or other fixed restoration. It can be either internal of or external of a tooth. Since minimal invasive can't be achieved without a minimal TRS, a precise preparation of slightest damage should conform to the transfer guide based on TRS. This paper introduces the concept, design of TRS, explains how it can be applied in tooth preparation, and helps to better understand a precise and minimal invasive tooth preparation technique.
Crowns ; Humans ; Tooth Preparation

A clear shoulder platform that can be easily identified by doctors and technicians or machines (mouth scan and warehouse scan) is important to obtaining a good long-term and stable fixed prosthesis treatment effect. At present, the pre-paration of the shoulder platform is usually based on free hands, and the practical operation is mainly guided by experience. Moreover, no comprehensive and objective preoperative design, intraoperative verification, and final test are available. Thus, the accuracy of shoulder platform preparation needs to be improved. In this study, the clinical pathway of "three determination, three selection, and three steps" with high accuracy of preparation and the precise shoulder preparation method of "bur-tip guidance" are proposed in detail.
Critical Pathways ; Shoulder ; Tooth ; Tooth Preparation ; Tooth Preparation, Prosthodontic

All contours of the restoration not directly related to occlusion are related to the gingival tissues only. And proper contour of restoration is essential for the health of the periodontal tissues. But there are so many controversies about the contour of the restoration, and there is no uniform agreement in the literature as to which contour of restoration is best for periodontium. In general, the contour of restoration means the supragingival contour only but in the case of the intracrevicular restorative procedure the subgingival contour of restoration must be considered. Because a portion of the restoration is placed in a gingival sulcus which is extremely vulnerable to periodontal disease. In this article the concepts or theories of the supragingival contour, the subgingival contour, and the emergence profile were discussed. The contour of the restoration and the biotype of the periodontium must be considered in intracrevicular restorative procedure. And sufficient tooth preparation is important factor to develop the proper contour of restoration which is kind to periodontium.
Periodontal Diseases ; Periodontium ; Tooth Preparation

The aim of this study was to evaluate the microleakage of teeth according to root canal preparation with & without apical enlargement in various size of apical foramen. 60 extracted one canal roots were cross-cutted at 5 mm from root apex and divided into two groups according to their apical foramen size of large (L) and small (S). Each group was subdivided into two groups accordance with their cross-sectional configuration at 5 mm from apex, round (R) and ovoid (O); SR Group, SO Group, LR Group, LO Group. Each group was shaped in .02 taper by Quantec series Nickel-Titanium (NiTi) rotary file, obturated by lateral condensation method. Leakage was measured using a fluid transport model under 40 cmH2O pressure. After the leakage test, blocks which had showed the leakage retreated with .04 taper and .06 taper and evaluated the degree of fluid filtration in each group. The data was analysed statistically using chi-square test and fisher's exact test. The results obtained were as follows: 1. Significant difference in leakage was found in groups which had different apical foramen size in .02 taper instrumentation (p < 0.05), but not in .04 taper instrumentation (p > 0.05). 2. The difference in microleakage according to the shape of canal was not evident at 5 mm from apex (p > 0.05). 3. There was correlation between .02 taper instrumentation and .04 taper instrumentation in LR group , LO group (p < 0.05).
Filtration ; Root Canal Preparation ; Tooth Apex ; Tooth*

PURPOSE: To compare the accuracy of marginal and internal adaptation of zirconia (Zr) copings fabricated on anatomic (A), semi-anatomic (SA) and non-anatomic (NA) occlusal surface preparations. MATERIALS AND METHODS: 45 extracted bicuspid teeth were prepared for receiving zirconia crowns, with different occlusal preparation designs A=15, SA=15 & NA=15. The Zr copings were fabricated by using CAD4DENT, CAD/CAM. The copings were adjusted, cemented and were cross sectioned centrally from buccal cusp tip to lingual cusp tip into mesial and distal halves. The copings were examined under electron microscope at x200 magnification and the measurements were recorded at 9 predetermined areas in micrometers. RESULTS: Overall mean gap values for the three groups was found to be 155.93+/-33.98 microm with Anatomical Occlusal preparation design having the least gap value of 139.23+/-30.85 microm showing the best adaptation among the groups. Post Hoc Tukey's test showed a statistically significant difference (P=.007) between the means of gap for A & NA preparation designs. Measurements recorded at 9 predetermined points showed variations for the three groups. CONCLUSION: Anatomical occlusal preparation designs resulted in better marginal and internal adaptation of Zr copings. There is a considerable variation between the measured marginal and internal gap values for the Zr copings fabricated by the (CAD4DENT-CAD/CAM). This variation may be associated with the lack of standardization of the preparation of teeth, computerized designing of the coping for each tooth, cement used, uniform pressure application during the cementation of the copings, sectioning of the copings and the microscopic measurements.
Bicuspid ; Cementation ; Crowns ; Tooth ; Tooth Preparation*

PURPOSE: The purpose of this study was to investigate the cutting efficiency of coarse grit diamond burs with air-turbine handpiece on natural tooth. MATERIALS AND METHODS: Four groups of coarse grit diamond bur were selected: Komet (A), Shofu (B), Premier (C), and Mani (D). The extracted maxillary central incisors were used, and ten cuts were made on each specimen, using the rotary diamond burs. The surface of each bur was measured at the upper, middle, and bottom of the bur with confocal laser scanning microscope and imaged with SEM. The data were analyzed with one-way ANOVA and t-test at the significance level of 0.05. RESULTS: The surface roughness was measured. At the A diamond bur, the Sa values were 52.93 microm, 48.32 microm, 46.79 microm, 45.06 microm, and 43.43 microm for control, test 1, 2, 3, and 4 respectively. The Sa values were 50.68 microm, 45.62 microm, 44.41 microm, 44.10 microm, and 42.46 microm for B diamond bur, 58.02 microm, 55.53 microm, 52.22 microm, 48.26 microm, and 45.36 microm for C diamond bur, and 50.11 microm, 46.73 microm, 45.46 microm, 42.58 microm, and 41.80 microm for D diamond bur. Surface roughness after each bur use showed significant changes, but no significant difference was found in surface roughness change between bur systems. CONCLUSIONS: Surface roughness in the same bur system showed significant differences after each tooth preparation. However no statistically significant differences were found in surface roughness between bur systems. The SEM images between control and test 4 showed the abraded particles.
Diamond ; Humans ; Incisor ; Tooth ; Tooth Preparation

Tooth preparation design is essential for successful laminate veneer treatment. Preservative tooth preparation limited on enamel, supra-margin advantageous for plaque control, and maintaining contact points known as a standard concept. However, the tooth preparation design has been the controversial issue. In biomechanical considerations, the incisal coverage should be decided on esthetic needs and necessity for the anterior guidance reconstruction. In occasion for sufficient enamel thickness, preparation can prolong to the palatal side but not recommended at palatal concavity. Elongation to contact point is selective option according to the cases. If an old resin restoration located at contact area, laminate veneer should cover over half area of that after surface treatment. The laminate veneer can be also selected at a partially discolored tooth root canal therapy (RCT) and at this occasion, the fiber-reinforced composite (FRC) posts are recommended.
Dental Enamel ; Dental Veneers* ; Tooth Preparation* ; Tooth Root ; Tooth*

STATEMENT OF PROBLEM: The effects of various core buildup materials which differs in the mechanical properties on the fracture strength of metal-free crowns is unknown. PURPOSE: This study was carried out to evaluate the fracture strengths of Artglass ceromer crowns supported by 3 different core materials in clinically simulated anterior tooth preparation. Material and methods. Ten crowns from each group were constructed to comparable dimensions on the various dies made by gold alloy, Ni-Cr alloy, and composite resin. The ten crowns were then cemented onto the dies and loaded until catastrophic failure took place. Fracture resistance to forces applied to the incisal edges of the anterior crowns supported by three types of dies was tested. RESULTS: The ceromer crowns on the composite resin dies fractured at significantly lower values(287.7 N) than the ceromer crowns on the metal dies(approximately 518.4 N). No significant difference was found between the fracture values of the ceromer crowns on the dies of gold alloy and Ni-Cr alloy. CONCLUSION: The failure loads of the ceromer crowns on the metal dies were almost the same and not affected by the differences of casting alloys. However, the fracture values of the ceromer crowns on the resin dies were significantly reduced by the relative weak properties of composite resin core material.
Alloys ; Crowns* ; Resin Cements ; Tooth Preparation

Although traditional tooth preparation techniques (e.g., depth-groove-guided and index-guided techniques) are designed to improve preparation precision, the results are unsatisfactory because of the lack of proper estimating tools. This study proposed a novel technique, in which relevant details for preparation of drilling holes are provided and corresponding depth is estimated using a quantitive bur under a microscope. This technique offers a viable option for precise tooth preparation.
Humans ; Microscopy, Confocal ; Tooth Preparation ; methods