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  • 2. 713A Novel Diagnostic andPrognostic Classification for theClinical Management of EndodonticallyTreated Single Anterior TeethRafael Murgueitio, DDS* Restorative criteria for endodon-Gustavo Avila-Ortiz, DDS, MS, PhD** tically treated teeth should dis- tinguish between anterior and posterior teeth.1 Morphologic char- acteristics of anterior teeth make them more delicate than posteriorThe restoration of endodontically treated anterior teeth (ETAT) may pose a teeth since they usually presentsignificant clinical challenge given the wide variety of therapeutic options with less remaining dental struc-available. Accurate analysis of the remaining tooth structure is critical in the ture.2 Additionally, the anatomicaldiagnostic process, leading to selection of the proper treatment option. position and natural angulation ofA novel, simple, and precise classification that allows the evaluation of anterior teeth contribute to a lessETAT is presented. Important factors related to the crown or abutment favorable biomechanical responsesuch as height, wall thickness, and circumferential integrity and root- under masticatory forces comparedrelated factors such as diameter of the canal, depth of the preparation, to posterior teeth.3 Restorativeand canal shape are discussed. This classification may serve to establish treatment of anterior teeth greatlya comprehensive diagnosis and assign prognosis to ETAT, which may be varies depending on the amount ofhelpful for interclinician communication and standardized comparisons in residual tissue. For endodonticallyclinical research. (Int J Periodontics Restorative Dent 2012;32:713–720.) treated anterior teeth (ETAT) with minimal structure loss, the use of direct restorative materials such as composite resin without the need for a post and full crown is gener- ally recommended.4 On the other hand, ETAT presenting with exten- sive tissue loss may require the use  * ssistant Professor, Advanced Prosthodontic Graduate Program, School of Dentistry, A of a post and abutment to allow Universidad del Valle, Cali, Colombia; Assistant Professor, Unicoc, Cali, Colombia. retention of a full crown.5,6 Proper** ssistant Professor, Department of Periodontics, University of Iowa College of Dentistry, A case analysis to assign prognosis, Iowa City, Iowa, USA. determination of the restorability Correspondence to: Rafael Murgueitio, Cra. 35 A #3bis-65, Cali, Colombia; of ETAT, and selection of an ad- fax: 572 5579880; email: equate restorative therapy should Volume 32, Number 6, 2012© 2012 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY.NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
  • 3. 714 Fig 1    Supragingival dental remanent or abutment height. Type I = intact crown except for the endodontic access opening and minor restorations (preparation for a full crown is not needed); type II = abutment height 3 mm; type III = abutment height between 1.5 and 3 mm; and type IV = abutment height 1.5 mm. Type I Type II Type III Type IVbe based on a precise classification posterior teeth. In 2006, Naumann canal) to the external surface ofthat considers specific structural and coworkers1 proposed a classi- the residual tooth structure. In thischaracteristics of ETAT. To the au- fication to define structural defects classification, abutment walls pre-thors’ knowledge, there are three of endodontically treated teeth as senting a thickness less than 1 mmclassification systems available to a function of wall height, thickness, are considered nonexistent.9 Walldate to diagnose and treat end- and depth in both anterior and thickness should be measured us-odontically treated teeth. In 1991, posterior teeth. Interestingly, it was ing a caliper, but a periodontalKurer7 proposed a classification for recognized that confusion may be probe can also be used.nonvital single-rooted teeth that generated when therapeutic alter- Likewise, height of the residualtook into account variables such as natives are proposed that apply the dental structure should be consid-abutment height, post length and same system for both anterior and ered since it is a critical factor in theshape, and presence of infraosse- posterior teeth. The purpose of this process of determining the viabilityous root fractures. Yet, it did not paper is to present a classification of residual structure. Height mayconsider other variables such as the system that considers multiple fac- be defined as the distance fromdiameter of the canal or thickness tors related to the residual tooth the gingival margin to the highestof the abutment walls. In 2005, structure to facilitate a restorative point of the abutment or crown inPeroz et al8 proposed a system treatment plan for ETAT. a vertical direction, parallel to theto classify endodontically treated major axis of the tooth, and canteeth taking into account the fea- be assessed using a periodontaltures of the residual tooth struc- Classification probe. A wall must present a mini-ture. This classification was based mum height of 1.5 mm (ferrule ef-on a numeric scale (from I to V) Crown or abutment factors fect) to be considered existent.depending on the number of re- Based on this description, the au-maining walls (considering a mini- Wall thickness and height of the thors propose four categories ac-mum of 2 mm for ferrule effect and crown or abutment cording to abutment height (Fig 1).1 mm for wall thickness) and was Abutment wall thickness is mea- Teeth presenting with intact crownsequally applied for anterior and sured from the inner surface (root (excluding minor defects relatedThe International Journal of Periodontics Restorative Dentistry © 2012 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
  • 4. 715 1 mm 1 mm 3.5 mm 3.5 mm 100% 60% a b a b Figs 2a and 2b    Type II classification: wall thick- Figs 3a and 3b    Type II classification: wall thick- ness ≥1 mm, wall height 3 mm, and abutment ness ≥ 1 mm, wall height 3 mm, and abutment circumferential integrity = 100%. circumferential integrity ≥ 50%. Figs 4a and 4b    Type IV classification. Vestibular 1 mm portion: wall thickness ≥ 1 mm, wall height 3 mm, and abutment circumferential integrity = 50%. Lingual portion: wall thickness = 0 mm, wall height 1.5 mm, and abutment circumferential integrity loss = 50%. A missing wall that affects at least 50% of the circumferential integrity dictates the classification. 50% a bto endodontic access opening type III (abutment height between the circumferential integrity. In theseand small restorations that do not 1.5 and 3.0 mm), or type IV (abut- instances, the fraction of the abut-compromise its structural integrity) ment height less than 1.5 mm). ment that presents a circumferentialare classified as type I. Preparation integrity greater than 50% dictatesfor a full crown is not necessary in Circumferential integrity and the classification for wall thicknessthese teeth. However, clinicians of- irregular abutments and height (Figs 3a and 3b). In casesten have to treat teeth presenting Anterior teeth prepared for a full in which abutments with two differ-compromised clinical crowns that crown in which the abutment main- ent walls present similar circumfer-need to be prepared to receive full tains all of its walls have a circum- ential proportions (50%:50%), thecrowns. These are classified accord- ferential integrity of 100% (Figs 2a classification is dictated by theing to their height into type II (abut- and 2b). Nonetheless, tooth prepa- fraction that presents the shortestment height greater than 3.0 mm), ration may result in partial loss of abutment height (Figs 4a and 4b). Volume 32, Number 6, 2012© 2012 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY.NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
  • 5. 716 Short Medium Long Narrow Medium Large MD Large BLFig 5    Canal diameter: narrow = canal diameter less Fig 6    Canal depth: short = canal depth lessthan one-third of the total root diameter; medium = than one-half of the root length; medium =canal diameter equal to one-third of the total root canal depth equal to one-half of the root length;diameter; and large = canal diameter less than one- and long = canal depth longer than one-half ofthird of the total root diameter. MD = mesiodistal; the root length.BL = buccolingual.Root factors this analysis should be accom- Canal depth panied by a clinical examination Canal depth is the remaining lengthRoot factors should also be taken since some teeth, particularly the of the root canal after the tooth hasinto consideration when insertion canines, present a greater canal been prepared to receive a post.of a post has been indicated for the diameter in the buccolingual direc- This measurement should be ob-retention of a crown. Such factors tion, and this must be considered tained from the most apical level ofinclude the canal diameter, depth, for the fabrication of posts. the preparation margin to the api-and shape. This classification considers the cal end of the canal, as assessed by largest diameter of the canal, regard- a periapical radiograph obtainedCanal diameter less of the direction and apico- using a parallel technique (Fig 6).The canal diameter is the ampli- coronal location. Three categories Three categories are proposed:tude of the root canal in relation to are proposed: narrow (canal ampli- short (intraradicular post length isthe root diameter in both a bucco- tude is less than one-third of the total less than one-half of the radicularlingual and mesiodistal dimension. root diameter), medium (canal ampli- length), medium (intraradicular postA periapical radiograph usually tude is equal to one-third of the total length is equal to one-half of theprovides valuable information to root diameter), and large (canal radicular length), and long (intra­assess the dimension of the canal in amplitude is greater than one-third radicular post length is longer thana mesiodistal direction. However, of the total root diameter) (Fig 5). one-half of the radicular length).The International Journal of Periodontics Restorative Dentistry © 2012 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
  • 6. 717 Tapered Parallel Fig 7    Canal preparation shape: tapered and parallel.Canal shape ETAT restorability is the crown- to define the minimum thicknessRoot canal shape is highly deter- to-root ratio, which in most cases for abutment wall integrity. None-mined by the technique and in- is directly related to the extent of theless, most studies consider astruments used to perform the periodontal support loss. Ideal- wall with a thickness ≥ 1 mm to bepreparation for a post. There are ly, it should be at least 1:1. A 2:1 acceptable therapeutically.1,8,9 Yet,basically two types of canal shape relationship contraindicates the whether to measure before or afterpreparations: tapered and parallel restoration of ETAT because of tooth preparation procedures have(Fig 7). unfavorable biomechanics.10,11 An- been completed may be controver- other critical question concerning sial. While Creugers et al12 recom- the restorability of ETAT is whether mended that the measurement bePractical application and a post must be inserted and how taken before tooth preparation, thediscussion much structure would remain after authors’ opinion is that this could post placement. This decision is di- be problematic from a clinicalPrior to the initiation of ETAT re- rectly related to crown factors, such standpoint because after preparingconstruction, tooth restorability as the number, distribution, thick- a tooth to receive a new restora-must be carefully evaluated. From ness, and height of the residual tion, the actual amount and shapea restorative standpoint, the most abutment wall.7,8 Regarding wall of the change in residual dentalimportant factor that determines thickness, there is limited evidence structure and the application of Volume 32, Number 6, 2012© 2012 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY.NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
  • 7. 718 Table 1 Recommended therapeutic options for single ETAT considering the residual crown and root canal diameter* Canal diameter Recommended post Recommended type of restoration StudiesType I Narrow and medium No post: glass ionomer† and/or Composite resin or ceramic veneer§ 4, 5,11 composite resinType I Large Metal or fiber prefabricated post Composite resin or ceramic veneer§ 12,13,14Type II Narrow and medium Metal or fiber prefabricated post Ceramic or metal-ceramic crown 12,13,14Type II Large Metal or zirconia custom-made post Ceramic or metal-ceramic crown 5, 6, 15, 16 and abutmentType III Narrow, medium, and large Prefabricated metal or fiber post‡ Ceramic or metal-ceramic crown 5, 6, 15, 16 Metal or zirconia custom-made post and abutmentType IV Narrow, medium, and large Metal or zirconia custom-made post Ceramic or metal-ceramic crown 5, 6, 15, 16 and abutmentETAT = endodontically treated anterior teeth.*Not applicable for fixed partial denture abutments.†To be used like a liner over the gutta-percha followed by acid etching and final obturation with composite resin.‡Selection should be made by the clinician since there is no clear clinical evidence supporting its use for these indications.§Indicated when vestibular enamel is compromised by more than 30% or if fracture lines are noticed. the classification may be unreliable. Hence, they should receive differ- For this reason, the authors propose ent treatment regimens depending that measurements of the remain- on these factors. This classification ing dental structure be taken and proposes four alternatives regard- recorded when all restorative proce- ing the height and remaining den- dures and other tooth preparation tal structure of ETAT. These four procedures, such as crown length- groups are correlated with different ening, have been completed. recommended restorative options In a conventional treatment depending on the canal diameter, plan, determination of tooth re- which are summarized in Table 1. storability is typically followed by ETAT with almost intact crowns the selection of the restorative (eg, endodontic access opening or treatment. Endodontically treated minor restorations) do not require teeth exhibit different wall heights a post. In fact, an adhesive resto- and canal diameters and shapes. ration is usually enough to achieveThe International Journal of Periodontics Restorative Dentistry © 2012 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
  • 8. 719an acceptable clinical outcome.13 cated, there are therapeutic alter- ates less biomechanical stress.29,30A similar criterion is applied when natives that can be used to achieve However, this type of preparationporcelain veneers are planned.14 the ferrule effect, such as crown needs more dentin removal toOn the other hand, ETAT present- lengthening or orthodontic extru- shape the canal walls to the paralleling extensive crown defects can- sion.22–24 However, these alterna- intraradicular segment of the post.not be restored using conservative tives cannot always be applied, This may increase the weakness oftechniques. They must be prepared especially in teeth with short roots the root in the finish area of theto receive crowns and often posts. or in situations where esthetics are post.31 On the other hand, the ta-Placement of prefabricated glass- highly involved. When post place- pered preparation is more naturalfiber or metal posts followed by a ment is indicated to provide sup- because it respects the canal anat-composite resin abutment buildup port for a restoration because of omy. Another variable that was notis a commonly used approach to insufficient residual structure, root considered in this classificationincrease the ferrule effect, which factors such as diameter, depth, but has been investigated previ-may be useful in cases of abut- and shape of the canal should be ously is the post depth in relationments classified as type II or III.17,18 taken into account. When possible, to the osseous level. Some inves-For abutments shorter than 3 mm, the diameter of the canal must not tigations suggest that post depthplacement of a cast post and core is exceed one-third of the mesiodis- must exceed the osseous level byrecommended.15,16 Abutments are tal or buccolingual thickness of the at least 4 mm.32,33 This is poten-classified as type IV when there is root to preserve healthy dentin tially problematic in cases of ETATnonexistent supragingival residual and avoid significant weakening with reduced periodontal support,structure (height less than 1.5 mm) of the tooth.25,26 Some research- making it impossible to follow thisto meet the ferrule effect criterion, ers suggest that the depth of the recommendation with a tooth thatwhich may be detrimental from a canal must be equal to two-thirds presents ≥ 50% circumferential al-biomechanical standpoint. None- of the radicular length or at least veolar bone loss.theless, studies that longitudinally equal to the clinical crown lengthevaluated the integrity of teeth (1:1 ratio) to achieve sufficient sta-restored in absence of the ferrule bility of the intraradicular element.5 Conclusionseffect have shown long-term sur- However, in some clinical scenari-vival rates comparable to those os, this concept may contradict an- This classification may serve to es-reported for teeth restored with a other variable rule suggesting that tablish a comprehensive diagno-minimum 1.5-mm ferrule.15 Based a minimum 4-mm gutta-percha sis and assign prognosis to ETAT,on this information, the restoration apical seal be preserved to dimin- which may be helpful for intercli-of ETAT that present an insufficient ish microleakage.27,28 Therefore, nician communication and stan-ferrule effect can be performed as the length of a post must follow dardized comparisons in clinicallong as patients are informed of two requirements: be long enough research. The classification is cor-the potential risks and other pos- to achieve stability and have a related with a therapeutic guidesible therapeutic alternatives to 4- to 5-mm apical seal. With regard that may assist clinicians in mak-ETAT preservation. to the shape of the intraradicular ing therapeutic decisions depend- Controversy exists with regard canal preparation, there are ba- ing on the clinical scenario. Theseto whether implant therapy should sically two alternatives: tapered recommendations may also servebe performed or an attempt should and parallel. Some researchers as a complement to previous clas-be made to preserve highly com- suggest that a parallel prepara- sifications aimed at assigning toothpromised single teeth.19–21 When tion improves the retention of the prognosis based on restorative andnatural tooth preservation is indi- intraradicular element and gener- periodontal parameters. Volume 32, Number 6, 2012© 2012 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY.NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
  • 9. 720References  1. Naumann M, Blankenstein F, Barthel CR. 13. Guzy GE, Nicholls JI. In vitro comparison 24. Carvalho CV, Bauer FP, Romito GA, Pan- A new approach to define defect exten- of intact endodontically treated teeth nuti CM, De Micheli G. Orthodontic ex- sions of endodontically treated teeth: with and without endo-post reinforce- trusion with or without circumferential Inter- intra-examiner reliability. J Oral Re- ment. J Prosthet Dent 1979;42:39–44. supracrestal fiberotomy and root plan- habil 2006;33:52–58. 14. Magne P, Belser U. Bonded Porcelain ing. Int J Periodontics Restorative Dent 2. Ash M Jr. Wheeler’s Dental Anatomy, Restorations in the Anterior Dentition: 2006;26:87–93. Physiology and Occlusion, ed 7. Philadel- A Biomimetic Approach, ed 1. Chicago: 25. Lloyd M, Palik JF. The philosophies of phia: WB Saunders, 1993. Quintessence, 2002. dowel diameter preparation: A literature  3. Fernandes AS, Shetty S, Coutinho I. 15. 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