The axis of the initial prepara-tion into the carious ssure is aligned with the long axis of the tooth crown so as to prevent iatrogenic removal of adjacent healthy tooth structure. e extracoronal r, anatomic crown, depending on whether any enamel is r, from the carious loss of tooth structure. An even more durable wall conguration results when the preparation has full-length enamel rods buttressed by shorter enamel rods on the preparation side of the wall (Fig. Mach Z, Regent J, Staninec M, et al: e integrity of bonded amalgam restorations: A clinical evaluation after ve years. Careless, iatrogenic removal of healthy dentin further compromises the diseased tooth and must be avoided. The adjacent tooth has been restored with a full porcelain-fused-to-metal crown (c). 128 CHAPTER 4 Fundamentals of Tooth Preparationdeveloped during initial tooth preparation may be adequate to retain the restorative material in the tooth.e design of preparation primary retention form is directly related to the retention needs of the anticipated restorative material. e use of sharp spoon excavators and sharp rotary instru-ments, with intermittent light pressure, may help limit pulpal irritation. Preparations for polymeric restoratives generally only require removal of the diseased tooth structure as these materials have no minimum material thickness requirement. Angles cs and cs′ are equal because opposite angles formed at the intersection of two straight lines are equal. Such treatments may include enameloplasty, application of pit-and-ssure sealant, and preventive resin or conservative composite restoration.7Esthetic considerations not only aect the choice of restorative material but also the design of the tooth preparation in an eort to maximize the esthetic result of the restoration. Additionally, when the conditions in the lesion have allowed remineralization to occur, the dentin may be distinctly discolored or “stained.” In this case host defenses not only have enabled remineralization of the dentin, which is often clinically comparable in rmness (hard-ness) with surrounding normal dentin, but also have, for the most part, successfully lled in the dentinal tubules with mineral. In addition to this host-defense mechanism, the presence of reparative dentin deposited as a result of pulpal insult constitutes a signicant deterrent to bacterial invasion. If you continue browsing the site, you agree to the use of cookies on this website. d, dentin; od, odontoblasts; p, pulp. On occlusal surfaces for Class I and II amalgam restorations, the incline planes of the cusp and the converging walls (for retentive purposes) of the preparation approximate the desirable 90-degree butt joint junction, even though the actual occlusal enamel margin may be greater than 90 degrees (see Figs. Additional retention of the restorative material may be obtained by arbitrarily extending the preparation for molars onto the facial or lingual surface to include a facial or lingual groove. When properly prepared, skirts provide additional, opposing vertical walls that increase retention of the restoration. Note that the ssure is parallel to the long axis of the posterior tooth crown. Occasionally the tooth preparation outline for a new restora-tion contacts or extends slightly into a sound, existing restoration (e.g., a new MO abutting a sound DO). Designed to be used by students throughout their dental education program and into professional clinical practice. Skirts are preparation features used in cast gold restora-tions that extend the preparation around some, if not all, of the line angles of the tooth. facial and lingual surfaces of molars, and (3) the lingual surfaces, that develop in the proximal surfaces of posterior teeth are termed, that develop in the proximal surfaces of anterior teeth that do not, caries lesions or other defects that develop in the gingival thir, the facial or lingual surfaces of all teeth are termed, that develop in the incisal edges of anterior teeth or the occlusal, preparation techniques was introduced by B, and techniques; and from the increased kno. Fundamentals of extracoronal tooth preparation Part I. Sturdevant s Art and Science of Operative Dentistry. Tooth preparation is the mechanical alteration of a defective, Once the initial stage is completed, the nal stage of preparation design may be accomplished.e nal stage is focused on (1) accurate management of the lesion/defect that has been isolated, (2) optimal protection of remaining tooth structure, and (3) preparation enhancements consistent with best long-term prognosis (durability) of the restora-tion. CHAPTER 4 Fundamentals of Tooth Preparation 127 to be altered so as to improve occlusal relationships). Using a heavily illustrated, step-by-step approach, Sturdevant’s Art and Science of Operative Dentistry, 7th Edition helps you master the fundamentals and procedures of restorative and preventive dentistry and learn to make informed decisions to solve patient needs. CHAPTER 4 Fundamentals of Tooth Preparation 131 of tooth structure. 4.15).When a preparation has extended onto the root surface (i.e., no enamel present), the root-surface cavosurface angle should be either 90 degrees (for amalgam, composite, or ceramic restorations) or beveled (for intracoronal cast-metal restorations). All preparations in stress-bearing areas, once completed, should ensure healthy dentinal support of remain-ing enamel.Tunnel Tooth Preparations for Amalgam, Composite Resin, and Glass IonomersIn an eort to be conservative in the removal of tooth structure, some investigators advocate a “tunnel” tooth preparation. e only dierence in the restora-tion is that the thickness of the restorative material, at the enameloplastied margin, is slightly decreased because the pulpal depth of the preparation external wall is slightly decreased. C, The preparation cavosurface angle (cs), axial wall (a), pulpal wall (oor) (p), enamel wall (e), dentinal wall (d), preparation margin (m), and DEJ ( j ). ese alterations require additional selective removal of healthy tooth structure.Retention Grooves and Coves. principles of tooth preparation. 4.10).e anatomic orientation of caries lesion formation in the pit and ssure areas of posterior teeth requires alignment of the rotary instrument shank axis (through proper positioning of the handpiece) so that it is parallel with the long axis of the tooth crown prior to initiation of the preparation (see Online Chapter 14 for information on handpieces and rotary instruments, specically Fig. e information presented is comprehensive and specic primarily for tooth preparations designed to receive direct restorative materials that are not adhesively attached to the tooth structure and are polycrystalline in nature (i.e., amalgam). Adjacent cusps may be considerably compromised and, as such, may need to be reduced, enveloped, and covered with restorative material to prevent subsequent cata-strophic fracture when under occlusal load.10,11 In general, the greater the occlusal load, the greater is the potential for future fracture of the tooth and/or restoration. book referred : Sturdevant's. Careful orientation of remaining horizontal and vertical walls during tooth preparation results in “steps” that increase retention and resistance form of the restoration. In addition to richly illustrated, step-by-step descriptions of procedures, it offers essential information on basic topics, such as dental instruments and equipment, nomenclature and general principles of tooth preparation, isolation of the operating field, matrix and wedge systems, light curing, and pulpal protection. Fundamentals in tooth preparation SlideShare. Agnihotry A, Fedorowicz Z, Nasser M: Adhesively bonded versus non-bonded amalgam restorations for dental caries. e design of the cavosurface margins for these materials is therefore as close to 90 degrees as possible as this marginal conguration allows maximum thickness of the polycrystalline material that will subsequently be placed in the preparation (Fig. 4.15 Vertical section of Class II tooth preparation. This article sheds light on Operative Dentistry & the list of Questions MERITERS experts will answer that are essential for an effective and efficient preparation: Current factors that dictate extension on smooth surfaces include (1) the extent of caries or injury and (2) the restorative material to be used. Tooth preparations for complete crowns: an art form based on scientific principles J Prosthet Dent. In addition, missing dentin may need to be replaced with an appropriate restorative material to act as a dentin substitute. No. 4.10 Occlusal contact areas identied through the use of articulat-ing paper. Resaratnam L: Review suggests direct pulp capping with MTA more eective than calcium hydroxide. e thin remaining wall of dentin provides little protection from (1) heat generated by rotary instruments during subsequent steps, (2) noxious ingredients of various restorative materials, (3) thermal changes conducted through restorative materials, (4) forces transmit-ted through materials to the dentin, (5) galvanic shock, and (6) the ingress of bacteria and/or noxious bacterial toxins through microleakage.14,15 Deep dentin also is a very poor substrate for subsequent bonding procedures. Quintessence Int 27:129–135, 1996.20. e preparation involving the mesial, occlusal, and distal surfaces is a mesioocclusodistal preparation. Demineralization of the exposed dentin surface results in exposure of the dentin matrix (collagen), which may then be inltrated with adhesive resin materials. Osmotic gradients cause a rapid, transi-tory increase in the amount of marginal microleakage associated with recently placed amalgam restorations, which may result in sensitivity. Become a DentistryKey membership for Full access and enjoy Unlimited articles, eeth require intervention (i.e., need some type of preparation), for various reasons: (1) caries lesion progr, in need of reestablishment of form or function; (4) previous r, tion with inadequate occlusal or proximal contact, defective (open), margins, or poor esthetics; or (5) as par, of iatrogenic damage to adjacent tooth surfaces while seeking to, intervention are prepared such that various r, is chapter denes tooth preparation and the historical classica, tion of anatomic locations aected by caries lesions. Sturdevant JR, Wilder AD, Roberson TM, et al: Clinical study of conservative designs for Class II amalgams (abstract 1549). Generally, the objectives of tooth preparation are to (1) conserve as much healthy tooth structure as possible, (2) remove all defects while simultaneously providing protection of the pulp–dentin complex, (3) form the tooth preparation so that, under the forces of mastication, the tooth or the restoration (or both) will not fracture and the restoration will not be displaced, and (4) allow for the esthetic placement of a restorative material where indicated.G.V. Carious tissue that has been demineralized and structurally damaged to this level feels tactilely soft and is therefore referred to as soft dentin. Teeth requiring intervention are prepared such that various restorative materials have the most predictable outcome.is chapter denes tooth preparation and the historical classica-tion of anatomic locations aected by caries lesions. It is essential that the outline form be visualized (i.e., mentally anticipated) as much as possible before any mechanical alteration of the tooth has begun. 126 CHAPTER 4 Fundamentals of Tooth Preparation• Fig. 4.14 Basic primary retention form in Class II tooth preparations for amalgam (A) with vertical external walls of proximal and occlusal por-tions converging occlusally and for inlay (B) with similar walls slightly diverging occlusally. Because of the low edge strength of amalgam and glass-ceramic, a 90-degree cavosurface angle produces maximal strength for these materials. Hemorrhage is the usual evidence of a vital pulp exposure, but with microscopic exposures, such evidence may be lacking. For example, a diamond abrasive cutting instrument may be chosen to increase the roughness, and thereby surface area, of prepared walls and This procedure technically included a preparation stage but no restoration stage. Extreme prudence was exercised in the selection of these areas and in the depth of enamel removed. Research studies support the lling of ssures/pits and narrow grooves/fossae (i.e., “sealing”) with low viscosity composite resin materials, without any mechanical alteration (enameloplasty) of the at-risk tooth anatomy.9Additionally, “prophylactic odontotomy” procedures were used in the past. Consideration, is given to factors that directly impact pr, by description of the logic and procedural organization of prepara, tion steps. e attachment between polymeric materials and enamel remains stable over time. e decision to reduce a cusp should be approached judiciously. Dent Clin North Am 15:219, 1971.6. Craig RG, Powers JM, editors: Restorative dental materials, 11th ed, St. Louis, 2002, Mosby.19. J Am Dent Assoc 119:725, 1989.38. Sectional view (C) of initial stage of tooth preparations for lesions in A and B when planning for a polycrystalline restorative material such as amalgam. ese include preparations on (1) occlusal surfaces of premolars and molars, (2) occlusal two thirds of the facial and lingual surfaces of molars, and (3) the lingual surfaces of maxillary incisors. In A, initial depth is approximately two thirds of 3-mm rotary instrument head length, or 2 mm, as related to prepared facial and lingual walls, but is half the rotary instrument (specically the No. When the defect results in a preparation outline form that places the marginal interface at the point of contact, then the nal position of the preparation outline is modied slightly so that the marginal junction is away from the occlusal contact (review section Occlusal Contact Identication and Rotary Instrument Axis Alignment).It is appropriate, for clinical practicality, to consider that enamel rods are oriented perpendicular to the external tooth surface. Comprehensive coverage spans the entire spectrum of operative dentistry, including fundamentals, diagnosis, instrumentation, preparation, restoration, and prevention. In vivo studies do not substantiate the necessity of these grooves in proximocclusal preparations with occlusal dovetail outline forms or in MOD preparations.4 ey are recommended, however, for extensive tooth preparations for amalgam involving wide faciolingual proximal boxes resulting in notable proximal wall divergence, cusp reduction procedures, or both. Although proposed bonding techniques vary, the essential procedure is to prepare the tooth in a fashion similar to that typical for amalgam and then utilize an adhesive to bond the amalgam restoration into the preparation. 4.6 and 4.7). An internal wall is a prepared surface that does not extend to the external ddsc• Fig. e desired pulpal eects may include sedation and stimulation, the latter resulting in reparative dentin formation. 4.14B).Step 4: Convenience FormConvenience form is the shape or form that provides adequate observation, accessibility, and ease in the preparation and restoration of the tooth. e line angle that forms where two walls meet, regardless of whether it is acute or obtuse, should be slightly curved (“softened”) (Fig. In this way, when the amalgam is placed in the preparation and hardens, it cannot be dislodged. e dentin substitute, along with remaining healthy dentin, acts to support the new restorative material that is replacing the enamel. Placement of the adhesive will allow subsequent formation of strong, durable mechanical bond between the etched enamel and the composite. Firm dentin, if isolated from the oral environment by some type of restoration, will remineralize and therefore should not be removed.12 Boksman L, Swift EJ, Jr: Current usage of glutaraldehyde/HEMA. e amount of divergence required depends on the length of the prepared walls: e greater the vertical height of the walls, the more divergence is permitted and recommended, but within the range described. Water spray (along with high-volume evacuation) is used when removing old amalgam material to reduce exposure to mercury vapor.In preparations that remain primarily in enamel, isolated faulty areas (remnants of diseased enamel ssure or pit) on the pulpal wall may require additional minimal extensions. 4.12). When the external walls of the preparation converge toward each other, as they approach the external surface of the tooth, then no additional or “secondary” retention is required. e 90-degree root-surface margin provides a butt joint relationship between the restorative material and the dentin (with overlying cementum) preparation wall, a conguration that provides appropriate strength to both.An acute, abrupt change in a preparation wall outline form increases the diculty of optimal adaptation of the restorative material. Line angles are distofacial (df), faciopulpal (fp), axiofacial (af), faciogingival (fg), axiogin-gival (ag), linguogingival (lg), axiolingual (al), axiopulpal (ap), linguopulpal (lp), distolingual (dl), and distopulpal (dp). Charbeneau GT, Peyton FA: Some eects of cavity instrumentation on the adaptation of gold castings and amalgam. The process of tooth preparation is dfpdlp mlpmfmpmldldpdflpfp mfp• Fig. Enamel rods that do not run uninterrupted from Mechanical FeaturesA variety of mechanical alterations to the preparation enhance retention form. In moderate caries lesions, removal of the masses of bacteria and subsequent sealing of the preparation by a restoration at best destroy those comparatively few remaining microorganisms and at worst reduce them to inactivity or dormancy.13 Even in advanced caries lesions, in which actual invasion of the pulp may have occurred, the recovery of the pulp requires only that a favorable balance be established between the virulence of the bacteria and the resistance of the host. The dentinoenamel junction (DEJ) and the cementoenamel junction (CEJ) are indicated in B. is material should be removed if any of the following conditions are present: (1) the old material may negatively aect the esthetic result of the new restoration (i.e., old amalgam material left under a new composite restoration), (2) radiographic evidence indicates caries lesion development under the old material and clinical evaluation conrms the radiographic interpretation, (3) the tooth pulp was symptomatic preoperatively, (4) the dentin along the periphery of the remaining old restorative material is soft, or (5) retention of the existing material is compromised and the material is easily dislodged. Internal wall: Prepared (cut) surface that does not extend to external tooth surface. Furthermore, it is necessary to recall that pulpal and axial dentin in an advanced lesion (see Step 5 above) has been damaged by the caries process and any bond to this deep dentin is compromised. C, The, may be visualized by imaginary projections of the pr, formed at the intersection of two straight lines are equal. 4.5). Chapters that are devoted to the preparation and restoration of specic lesions/defects elaborate on these additional factors. e preparation may be complete after the initial tooth preparation stage when the caries lesion (or other defect) is minimal. Placement of the RMGI may theoretically limit the ability of any free glutaraldehyde or HEMA to gain access to tubules in closest proximity to the pulp. Such an extension, when performed for cast-metal restorations, results in additional vertical (almost parallel) walls for retention. the physical limitations of the planned restorative material. Correcting or improving occlusal relationships also may necessitate altering the tooth preparation to accommodate such changes, even when the involved tooth structure is not faulty (i.e., a cuspal form may need e periphery of preparations for polycrystalline, (edges) of the planned restoration. Controlled, conservative removal of any remaining tooth structure, based on the needs of the restorative material, is always accomplished with the awareness that the intracoronal restoration will not add strength to the tooth over the long term, regardless of the nature of the restorative material being used.ABCcsjmapdemAxis of preparationAxis ofpreparationrmus’cs’w’rm’• Fig. Allow for the esthetic and functional placement of the restorative material. 4.9 and Box 4.2).Tooth Preparation: Stages and Procedural StepsOverviewIt is imperative that the end result (i.e., the overall shape/goals of the preparation procedure) be envisioned/considered before the initiation of any step. J Dent Res 86:529–533, 2007.40. e more extensive the preparation, the greater the risk of iatrogenic damage of adjacent structures or restorations during procedures. Dentistry has developed terminology useful in the communica, tion of all aspects of preparation design and associated procedur, the name of the involved tooth surface(s)—for example, a defect, When discussing or writing a term denoting a combination of, surfaces of an anterior tooth would be termed, the mesial, occlusal, and distal surfaces is a, tion of a tooth preparation is abbreviated b, capitalized, of each tooth surface involved. Cusp reduction should be considered when the outline form has extended half the distance from a primary groove to a cusp tip. Proper nishing of the external walls allows the creation of an optimal marginal junction between the restorative material and the tooth structure. When discussing or writing a term denoting a combination of two or more surfaces, the -al ending of the prex word is changed to an –o. Carious dentin in more peripheral areas is removed until the dentin is rm.In dentin, as the caries lesion progresses, a zone of deminer-alization precedes the invasion of, or infection by, bacteria. Dennison JB, Sarrett DC: Prediction and diagnosis of clinical outcomes aecting restoration margins. erefore every eort should be made to limit further pulpal irritation and limit the likelihood of pulpal involvement during the caries removal process. Caries removal in advanced lesions usually is immediately followed by eorts to aord protection to the pulp tissue adjacent to the deepest area of the preparation.Step 6: Pulp ProtectionDeep dentin is very porous and susceptible to desiccation. Eur J Oral Sci 105:414–421, 1997.33. Eur J Oral Sci 125:63–71, 2017.36. e actual amount of space required depends directly on the physical properties of the restorative material to be used. Bacterial proteases are not able to degrade intact, native collagen. It is important not to dehydrate the tooth by overuse of air as this may damage the odontoblasts associated with the desiccated tubules (Fig. 4.4 Extracoronal “stumplike” tooth preparation with dentin (d) and dentin substitute (core component of a cast post and core, ds). Point angles are distofaciopulpal (dfp), distolinguopulpal (dlp), mesiolin-guopulpal (mlp), and mesiofaciopulpal (mfp). When caries (or any defect) has com-promised the DEJ, then associated supercial enamel becomes prone to fracture under cyclic occlusal loading. Composite resin materials, which are thermal insulators, do not require the same bulk of material (dentin + liner/base) between the restoration and the pulp. occlusal forces. In addition, a thin gold margin is more readily burnished and adapted to the preparation margin.Beveling enamel margins in composite preparations is indicated primarily for large restorations that have increased retention needs and insucient amount of prepared enamel for proper retention. Generally, the objectives of tooth preparation are to (1) remove all defects and provide necessary protection to the pulp, (2) extend the restoration as conservatively as possible, (3) form the tooth preparation so that under the forces of mastication, the tooth or the restoration (or both) will not fracture and the restoration will not be displaced, and (4) allow for the esthetic and functional placement of a … CHAPTER 4 Fundamentals of Tooth Preparation 133 preparation joins an occlusal lesion with a proximal lesion by means of a prepared tunnel under the involved marginal ridge. Investigators have veried the presence of bacteria in the dentinal tubules within the preparation walls. Gingival oor enamel (and margin) is unsup-ported by dentin and friable unless removed. e term longitudinal may be used in lieu of vertical. ese preparation modications provide resistance to parallel and also obliquely (laterally) directed Initial Tooth Preparation Stage: Steps 1-4Step 1: Initial Depth and Outline Forme rst step in tooth preparation is to establish the initial depth and then, at that depth, extend the walls of the preparation until the junction between the enamel and supporting dentin is uncom-promised (i.e., a “sound DEJ” has been reached; see Fig. Preparations required to correct caries lesions or other defects that develop in the proximal surfaces of anterior teeth that include the incisal edge are termed Class IV preparations. (B, From Mitsiadis TA, De Bari C, About I: Apoptosis in development and repair-related human tooth remodeling: A view from the inside, Exp Cell Res 314(4):869–877, 2008.) e esthetic quality of composite restorations of anterior teeth may be improved by use of a bevel to create an area of gradual increase in composite thickness from the margin to the bulk of the restoration. A–C, Extensions in all directions are to healthy, mineralized (“sound”) tooth structure, while maintaining a specic limited pulpal or axial depth regardless of whether end (or side) of rotary instrument is in a caries lesion or old restorative mate-rial. Summitt JB, Burgess JO, Berry TG, et al: Six-year clinical evaluation of bonded and pin- retained complex amalgam restorations. Linn J, Messer HH: Eect of restorative procedures on the strength of endodontically treated molars. It has been suggested that this technique may limit the likelihood of the development of postoperative sensitivity, staining of the dental structure, secondary caries, fracture of the tooth, or partial/total loss of the restora-tion. Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. Now customize the name of a clipboard to store your clips. erefore it may become necessary to strategically modify internal aspects of the preparation so as to mechanically retain the restoration.Because many preparation features that improve retention form also improve resistance form, and the reverse is true, they are presented together. Most preparation designs remove enamel that has lost its attachment to the underlying dentin (see Chapter 8 for exceptions). is bulk may include remaining dentin, liner, or base. 4.17). Each anatomically distinct area requiring restoration must be independently retentive. 120 CHAPTER 4 Fundamentals of Tooth Preparation1204 Fundamentals of Tooth PreparationLEE W. BOUSHELL, RICARDO WALTERTeeth require intervention (i.e., need some type of preparation) for various reasons: (1) caries lesion progression to the point that loss of tooth structure requires restoration; (2) tooth fracture compromising form and function with or without associated pain or sensitivity; (3) congenital malformation or improper position in need of reestablishment of form or function; (4) previous restora-tion with inadequate occlusal or proximal contact, defective (open) margins, or poor esthetics; or (5) as part of fullling other restorative needs (see Chapter 3). 14.18). Avoidance of unnecessary apical extension of the preparation. Restorative materials that need beveled margins require tooth preparation outline form extensions that must anticipate the nal cavosurface position and form that will result after the bevels have been placed.Step 2: Primary Resistance FormPrimary resistance form may be dened as the shape and placement of the preparation walls (oors) that best enable the remaining tooth structure, as well as the anticipated restoration, to withstand masticatory forces primarily oriented parallel to the long axis of the tooth. Consideration is given to factors that directly impact preparation design, followed by description of the logic and procedural organization of prepara-tion steps. 5 2. Also, If this book is hard to find is there another one that will do the trick? Chlorhexidine (2 weight percent [wt%]) solutions have been successfully used in preparations for disinfection purposes. Reeves R, Stanley HR: e relationship of bacterial penetration and pulpal pathosis in carious teeth. e amalgam is condensed into this adhesive material before polymerization, and a mechanical bond develops between the amalgam and adhesive. e enamel wall is that portion of a prepared external wall consisting of enamel (see Fig. Although diering in amounts, marginal leakage has been shown for current restorative materials.18,29,30 Caries is unlikely to develop in association with marginal gaps that are less than 250 µm.29 Limited protection from further carious activity may be aorded by some restorative materials.31 e germicidal or protective eect may be from the uoride content of some tooth-colored restorative materials or from the deposition of corrosion products at the interface between the preparation wall and an amalgam restoration.e natural defense mechanisms of the tooth, which result in the mineralization of the dentinal tubules under a caries lesion, help limit the potential for invasion of any remaining bacteria. e caries lesion will not progress if the defect is correctly restored.12Even when surface disinfection of the preparation has been attempted, it is doubtful that potential benets will continue for any appreciable length of time because of the dierence between the thermal coecients of expansion of the tooth and restorative materials. Quintessence Int 9:69–76, 1978.8. 4.1 and 4.2C). All, design takes into consideration that dental restorative materials. Removal of excess glu-taraldehyde and HEMA by rinsing with water may signicantly reduce any risk. 4.16).e design of the cavosurface angle depends on the restorative material being used. 4.5). J Oral Rehab 39:301–318, 2012.30. e structural makeup of enamel allows the creation of a microscopically roughened mineral surface when supercially demineralized by acidic condi-tions. See Chapters 8 and 10 for exceptions to these general principles.Black theorized that, in tooth preparations for smooth-surface caries, the initial preparation should be further extended to areas that are normally self-cleansing so as to prevent recurrence of caries around the periphery of the restoration.1 is principle was known as extension for prevention and was broadened to include the exten-sion necessary to remove remaining enamel imperfections, such as deep, noncarious fossae and grooves, on occlusal surfaces. e pulpal and axial caries removal of an advanced lesion should therefore extend to approximately 1 mm from the pulp with the recognition that dentin in this deep region may still be soft (soft dentin) to tactile sense. is process usually results in a preparation with fairly uniform (at least uniformly minimal) depths. Oper Dent 29:319–324, 2002.27. If the ends of these grooves were to be included in the tooth preparation, the cusp may be weakened to the extent that it would need to be reduced and covered with restorative material. If you continue browsing the site, you agree to the use of cookies on this website. Prophylactic odontotomy is no longer advocated as a preventive measure.42Enameloplasty and Prophylactic Odontotomy• BOX 4.2Initial Tooth Preparation StageFinal Tooth Preparation StageSteps of Tooth Preparation• BOX 4.3 If you wish to opt out, please close your SlideShare account. The preparation is based on biological and mechanical principles, protecting the pulp vitality and periodontal health while creating a strong restoration that protects the restored tooth. Reduction of cusps occurs as early as possible in the preparation process so as to improve access and visibility for the operator.Special consideration is given to teeth that have lost an excessive amount of dentin support in the central area of the tooth secondary to endodontic procedures. Likewise, when the aected tooth was treated, the cutting or preparation of the remaining tooth structure (to receive a restorative material) was referred to as cavity preparation. J Prosthet Dent 8:514, 1958.9. Get a better picture of operative dentistry from the most complete text on the market. 4.1 All enamel walls must consist of either full-length enamel rods on sound dentin (a) or full-length enamel rods on sound dentin supported on preparation side by shortened rods also on sound dentin (b). Currently, many indications for treatment are not related to carious destruction, and the preparation of the tooth no longer is referred to as cavity preparation, but as tooth preparation.Tooth Preparation: Denition and Foundational ConceptsTooth preparation is the mechanical alteration of a defective, injured, or diseased tooth such that placement of restorative material reestablishes normal form (and therefore function) including esthetic corrections, where indicated. e ability of a hard-setting CaOH2 material to stimulate the formation of reparative dentin when in contact with pulpal tissue makes it the usual material of choice for applica-tion to very deep excavations and known pulpal exposures (direct pulp cap procedures).16 Alternatively, mineral trioxide aggregate (MTA) liners have been found to be eective for direct pulp capping.17,20 Liners and bases in exposure areas should be applied without pressure.Usually, a RMGI is used for “base” needs. Note staining that has subsequently developed in areas of iatrogenic damage (arrow). Alternatively, there are some who advocate the use of an adhesive on the prepared tooth structure so as to limit rapid uid movement by “sealing” the dentin before amalgam placement and in this way limit the potential for postoperative sensitivity.37Composite restorations require some treatment of the preparation before insertion of the restorative material, which may primarily be considered as part of the restoration procedure (see Chapter 8); however, some discussion is appropriate at this point. Boyer DB, Roth L: Fracture resistance of teeth with bonded amalgams. Tooth preparation features or sections that are parallel (or nearly so) to the long axis of the tooth crown are commonly described as vertical, such as vertical height of cusps, or vertical walls. Endod Topics 5:49–56, 2003.17. Generally, it is desirable to have approximately a 2-mm dimension of bulk between the pulp and a metallic restorative material. e ability to utilize the information, solid understanding of concepts presented in, that had progressed to the point that ther, surface integrity of the tooth. 4.6 Schematic representation (for descriptive purpose) of a Class I tooth preparation illustrating line angles and point angles. This comprehensive text presents a detailed, heavily illustrated, step-by-step approach to restorative and preventive dentistry. AB• Fig. 4.9 A, Enameloplasty on area of imperfect coalescence of enamel. a Class I amalgam preparation or a Class I amalgam restoration). Establishment of the initial depth is always accomplished even when there is a large caries lesion (i.e., no healthy tooth structure immediately adjacent to the point of entry) or when previous restorative material is present. Correct alignment of the long axis of the shank limits the likelihood of iatrogenic removal, and thereby weakening, of adjacent healthy (occasionally referred to as “sound”) coronal tooth structure. Rasiines Alcaraz MG, Veiz-Keenan A, Sahrmann P, et al: Direct composite llings versus amalgam llings for permanent or adult posterior teeth. e objective of this approach is to remove the caries lesion and leave the marginal ridge essentially intact. Adhesive bonding of etchable glass-ceramic materials to enamel and dentin increase their resistance to fracture development when under occlusal load.Step 8: External Wall FinishingFinishing the external preparation walls is the further development, when indicated, of a specic design (e.g., degree of smoothness or roughness, the placement of a bevel) immediately adjacent to or including the cavosurface margin such that the anticipated restorative material has the greatest likelihood of clinical success. e bevels for cast-metal restorations are used primarily to aord a better junctional relationship between the metal and the tooth. 134 CHAPTER 4 Fundamentals of Tooth Preparationwall treatment for composites includes the etching (surface demineralization) of enamel and dentin followed by placement of a resin-based adhesive. However, this natural occlusion of the dentinal tubules only will occur beneath a slowly progressing caries lesion. Natural tooth structure is able to withstand the cyclic loading of mastication because of its ability to undergo small amounts of exure without fracture or separation of the enamel from the dentin. Also, it was thought that retention grooves may increase the resistance form of the restoration against fracture at the junction of the proximal and occlusal portions. An appropriate text focused on the emergency management of dental trauma should be consulted for current treatment strategies.Step 7: Secondary Retention and Resistance FormsPlacement of secondary retention and resistance forms, as part of a preparation, follows management of the caries lesion and any indicated pulpal protection. Biological Principles of Tooth Preparation help in preserving the health and integrity of the remaining tooth structure, where the Principles of Tooth Preparation deal with obtaining the proper shape, retention, resistance form of the cavity for restoration. Clearance with the adjacent proximal surface is mandatory for glass-ceramic and cast gold restorations because of the need to nish the preparation walls, make an accurate impression of the prepared tooth, and accomplish insertion/nishing. Pulpal wall: Internal wall perpendicular to long axis of the tooth, occlusal to pulp. Likewise, extension for prevention to include the caries-prone areas on occlusal surfaces has been reduced by treatments that conserve tooth structure. Long-term hybrid layer stability, as a result of chlorhexidine use, has not been demonstrated. e placement of skirts also enables increased resistance to fracture by allowing the envelopment of the remaining com-promised tooth structure with the restorative material.Beveled Enamel MarginsSome cast-metal and composite preparations include beveled marginal congurations. 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