a biometric approach to aesthetic crown lengthening

7/26/2019 A Biometric Approach to Aesthetic Crown Lengthening

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A BIOMETRIC APPROACH TO AESTHETIC

CROWN LENGTHENING

Stephen J. Chu, DMD, MSD, CDT*Mark N. Hochman, DDS

contemporary periodontal therapy also encompasses aesthetic treatment where needs are freuentlyassociated with chan!es in tooth si"e, shape, proportion, and #alance that can ne!ati$ely affect smileappearance.%There e&ists a syner!y #etween periodontics and restorati$e dentistry, where the disciplines areinterdependent. 'n aesthetic dentistry where de$elopment of the proper tooth si"e, form, and color ofrestorations are critical to clinical success, often the periodontal component is considera#le and must #eaddressed for a predicta#le aesthetic outcome. The need to esta#lish the correct tooth si"e and thusindi$idual tooth proportion dri$es the periodontal component of aesthetic restorati$e dentistry. (ne specificarea of concern is e&cessi$ely short teeth,) where the lack of tooth display and e&cessi$e !in!i$al displayreuire clinical crown len!thenin! that can present a clinical dilemma for the aestheticoriented

periodontist.There are a myriad of techniues that ha$e e$ol$ed o$er se$eral decades to treat this situation.Techniues that simplify as well as enhance the uality of treatment can pro$ide su#stantial #enefit to #othpatients and treatin! practitioners alike. This article descri#es an inno$ati$e approach to periodontalaesthetic crown len!thenin! utili"in! measurement !au!es specifically desi!ned for a predicta#le sur!icaloutcome, thus settin! a new standard of dia!nosis and treatment within the aesthetic "one. Midfacialsur!ical crown len!thenin! has traditionally #een performed to esta#lish a healthy #iolo!ic dimension ofthe dento!in!i$al comple& +DC- as an adunct to aesthetic restorati$e procedures. /hile considera#le$ariation in the ma!nitude or len!th of this comple& has #een reported, the mean sulcus depth was 0.12mm, epithelial attachment was 0.23 mm, and the connecti$e tissue was %.03 mm.4 Therefore, the totallen!th of the DC was ).34 mm. 5ased on these dimensions, se$eral authors ha$e su!!ested that 4 mmof supracrestal tooth structure #e o#tained durin! sur!ical crown len!thenin!.6,7 (ther authors ha$esu!!ested that supracrestal tooth structure ran!es from 4.7 mm to 7.)7 mm, dependin! on the placementof the restorati$e mar in.1,3 't is important, therefore, to esta#lish a consistent measurementrepresentati$e of the DC dimension, which is critical for health and restorati$e success when performin!

sur!ical crown len!thenin!


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Figure 1. Diagram of T-Bar Proportion Gauge tip (ie, Chus AestheticGauges, Hu-Frie! "nc, Chicago, "#$. %nce the esire tooth imensionsare etermine, the a&uncti'e perioonta proceure can )eperforme *hether treatment entais cro*n engthening or co'erage

Figure +. The Proportion Gauge tip is esigne for simutaneous

*ith an ength measurements of the maiar! anterior entition.The a'erage centra incisor measures . mm in *ith )! 11 mm inength (see re mar/ings-

Herrero et al noted that esta#lishin! a constant and desired surpracrestal tooth len!th is not routinelyachie$ed durin! sur!ical crown len!thenin!.8/alker and Hansen descri#ed the fa#rication of a sur!icaltemplate for aesthetic restorati$e crown len!thenin!.2 This, howe$er,reuired multiple $isits to fa#ricate such a template prior to sur!ery. 'n addition, sta#ility of the templatedurin! the sur!ical procedure was uestiona#le and could lead to inconsistent and unsatisfactory results.9ee descri#ed a toothformed pro$isional restoration to #e used as a remo$a#le template for sur!icalcrown len!thenin!.%0 Thisapproach reuires multiple presur!ical $isits to fa#ricate,

Figure 0. The T-Bar tip encompasses the tota range of tooth *ithan ength imensions of the maiar! anterior entition. Themeasurements are mathematica! aigne *ith a preset ini'iua

tooth proportion ratio of 2


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Figure 3. The 4ouning Gauge is fa)ricate to pierce the supracrestagingi'a fi)ers. The cur'e tip is 1 mm *ie an esigne to foo*the tooth an C56 anatomic contourspresents sta#ili"ation concerns at the time of sur!ery, and increases the cost of treatment. Thesetechniues attempted to standardi"e the amount of supracrestal len!th of the DC to #e esta#lished, yetthey all reuired additionaltime and la#oratory procedures to accomplish.Traditionally, dental instruments such as periodontal pro#es ha$e #een used as clinical indicators ofdiseases such as periodontitis, with their numerical $alues indicati$e of health or sta!es of disease.%%More recently, instrumentation +ie, Chu:s ;esthetic au!es, Huwhether it is clinical root co$era!e or len!thenin!. The =roportion au!eis desi!ned as a sin!lehandle, dou#leended instrument with ?T5ar@ and ?'n9ine@ tips screwed into thehandle at opposin! ends.%4 TheT5ar !au!e is used to measure a noncrowded anterior dentition and the 'n9ine for a crowded dentition.TheT5ar tip features an esta#lished rest position at the incisal ed!e position +ie, an incisal stop-A when the!au!e is seated accordin!ly, the practitioner can accurately e$aluate its len!th +$ertical arm- and width+hori"ontal arm- dimensions simultaneously and, therefore, $isually assess the correct tooth si"e andproportion. The width is indicated in 0.7mm increments of color, each with a $ertical mark incorrespondin! color. Thus, a central incisor witha ?red@ width of 8.7 mm will #e in proper proportion if itshei!ht is also the ?red@ hei!ht +ie, %% mm- +


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len!thenin! procedures to determine the le$el of the #one crest prior to flap reflection.This !au!e helps pro$ide uick and simple analysis of the osseous crest location midfacially andinterdentally.%1,%3 't has a deli#erate cur$ature of the tip coincident with the cur$ature of the tooth and root> especially at the cementoenamel unction where it is most prominent. This allows easier ne!otiation ofthe osseous crest location, particularly in thin #iotype cases where the crest is thin and difficult to detect.The tip of the !au!e is also wider than that of a periodontal pro#e at % mm in dimension. This increaseddimension allows !reater sta#ility and confidence durin! the soundin! process.

The Soundin! au!e is fa#ricated from sur!ical!rade stainless steel honed to precisely andatraumatically pierce the supracrestal !in!i$al fi#ers +


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Figure . Cro*n #engthening Gauge accesses cinicacro*n ength (CC#$ re9uire )ase on the resuts of the TBarProportion Gauge tip in Figure 1. 4hort arm of tip pro&ectscinica cro*n height an ong arm pro&ects *here the)one crest shou )e reati'e to CC# after surger!

Figure :. The coor coing enotes preetermine teeth ata preset proportion ratio an tooth ength. The same coorsenote the same teeth no matter *hat instrument tip isseecte an use

Figure 17. During aesthetic cro*n-engthening proceures,simutaneous 'isuai;ation of CC# an )ioogic cro*nength (BC#$ ao*s the cinician to focus on the goa oftreatment *ithout 9uestion, since the )ueprint for osseousresection is cear! eineate

Figure 11. The B#PG tip of the Cro*n #engthening Gaugeao*s precise 'isua 'erification that the proper amount

an shape of osseous resection *as performe to thehighest e'e


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Figure 1+. Post-orthoontic therap! re'eas a s/e*eincisa pane on the patients right sie an ecess space)et*een the centra incisors in the effort to re-esta)ishthe miineCrown Lengthening Gauge

The Crown 9en!thenin! au!e +ie, Chu:s ;esthetic au!es, Hu


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Figure 1. 4ucus epth of 1 mm to + mm, mifaciaosseous crest epth of 0 mm, an interproima osseouscrest ocation of 3 mm can )e accurate! assesse *ith the4ouning GaugeCase Presentation

; 76yearold female patient presented for an aesthetic restorati$e consultation durin! orthodontictreatment. She was under!oin! orthodontic treatment to correct a deep o$er#ite relationship as well ascorrect a midline discrepancy.The patient did not like her smile #ecause the pree&istin!, )0yearold, fullco$era!e restorations werewearin! and looked artificial. Comprehensi$e clinical and radio!raphic e&amination re$ealed loss ofmar!inal inte!rity of the fullco$era!e restorations with !in!i$al recession e&posin! the restorati$e mar!ins.'n addition, mild tooth rotations and e&cess spacin! was present followin! orthodontic treatment +


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cro*n simutaneous!. The incisa stop heps position thegauge uring measurement

Objective Analysis of Tooth Proportion;n initial phase of treatment included orthodontic tooth mo$ement to correct arch form, spacin!, ando$ereto$er#ite relationships. The second phase of treatment addressed fa#rication of pro$isionalrestorations from a dia!nostic wa&up to reesta#lish a functional occlusion as well as the correct incisal

ed!e position that harmoni"ed with the aesthetic and phonetic needs of the patient +


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Proportion Gauge an *as 'erifie cinica! prior to finacementation

Figure +7. Aesthetic-restorati'e integration an harmon!of the ;irconia-)ase restorations is achie'e through preicta)epanning *ith the Proportion an Cro*n

#engthening Gaugesand Soundin! au!e to accurately identify the !in!i$al sulcus, !in!i$al attachment, and crest of #one,respecti$ely +


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tau!ht in the dental curriculum, much too often clinicians witness restorations of teeth that are notproportional to one another +=ersonal communication, J. reen#er!, )003-.These restorations should also ha$e a #asic proportional relationship to periodontal supportin! tissues asan essential aspect of dental anatomy.This is the first techniue that uses optimal tooth proportions to determine the correct position of theosseous topo!raphy supportin! those teeth. Measurements are performed directly on the teeth withdisposa#le and remo$a#le aesthetic !au!es so that they will not interfere with sur!ical instrumentation.

The !au!es can #e used repeatedly to confirm the amount of midfacial osseous tissue to #e remo$ed.Gisual precision without !uessin! or emotional estimation is $ital for successful, predicta#le, costefficienttreatment.

AcknowlegentsThe authors wish to e&press their !ratitude to Jennifer Sal"er, DDS, for the orthodontic therapy and ;damMieles"ko, CDT, for the fa#rication of the restorations depicted herein. Special thanks to Dennis Tarnow,DDS, for his re$iew of this manuscript. Dr. Chu is the creator of Chu:s ;esthetic au!es and ser$es as aconsultant for Hu


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%3.Tarnow D=, Ma!ner ;/,

a biometric approach to aesthetic crown lengthening

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