the international journal of periodontics & restorative...

The International Journal of Periodontics & Restorative Dentistry

413

To Conserve or Implant: Which Choiceof Therapy?

Mithridade Davarpanah. MD. DDS'i-lenry Martinez, DDS*'Jean François Tecucianu, MD, DDS***Olivier Fromentin, DDS****Renato Celletti, DDS*****

The longevity of teeth depends directly on the state of the periodontal tissues.Many etiologic factors can lead to the loss of a tooth. Tooth toss is frequently asso-ciated with bone résorption. The diagnosis of a condition and knowledge of its eti-ology are essential to assess the prognosis ofthe remaining teeth and to formu-late the correct treatment plan. Many parameters must be investigated to ascer-tain an accurate diagnosis An understanding of the patient's needs and the lengthand likely success of treatment guides the decision of whether to preserve teeth orextract them and place implants Advanced periodontitis poses a major therapeu-tic dilemma. Judicious, strategic extractions rnay permit the piacemeDt of longimplants in ideal positions. (Int J Periodontics Restorative Dent 2000:20:413-422.1

^Assistant Professor, Department of Periodontoiogy, University ofParis VI; Private Practice, Paris, France; and Clinical AssistantProfessor, Department of Periodontoiogy, Uniuersity of SouthernCalifornia. Los Angeles, California.

"ClinicBl Assistant, Department of Oral Surgery, Faculty ofOdontology, University ot Paris VII, France.

•*Professor, Department of Periodontoiogy, University of Paris VI, andPnvate Practice. Paris, France

•"Clinical Assistant, Department of Prosthodontics, Faculty ofOdontology, University of Paris VII, France.

"Assistant Professor. Department of Periodontoiogy, University "G.d'Annunzio," Chieti; and Private Practice, Rome, Italy.

Reprint requests: Dr Mithridade Davarpanah, 174 RuedeCourcelles, 75017 Paris, France.

The use of implants has added tothe range of treatments availablefor different types of tooth loss.Many studies have confirmed anexcellent long-term prognosis (suc-cess rates of 78% to 100%).'-^Previously, teeth with a poor prog-nosis were preserved to postponethe inevitable removable prosthe-sis. Nowadays, the opt ion toimplant is too readily delayed.Before formulating a treatmentplan, the practitioner must establishthe diagnosis and its etiology,determine the prognosis of theremaining teeth, and predict thefinal functional and esthetic result.Equally, the prognosis ofthe differ-ent therapeutic options must befully analyzed.

The practitioner must always bemindful ofthe possibility of retainingthe teeth. However, an unfavorableprognosis must cause considerationof the need to extract. Retention ofteeth with a poor prognosis can leadto significant loss of tissues. Alveolarbone loss reduces therapeuticoptions, considerably lengthenstreatment, and risks compromisingthe final result.^'^

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414

^ ^ ^ ^ ^ 1 General and local risk factors

Factor

GeneralGeneral state of patientMedical historySmokerGenetic test (PST)Immune systemMedicationsNutritional StatusDrug addiction

LocalBacterial fioraLoss of attachmentActivity within pocketArnount of bone lossRapidity of disease progressFurcation involvementMobilityPlaque controlResidual teethCrown-to-root ratioOcclusal traumaParafunctionTooth alignmentRoot morphologyCariesRestorationsEndodontic considerations

Unfavorableto prognosis

"At-risk" factors presentSignificant factors detectedYesPositiveImmunosuppressedCyclasporine,phenytoinProtein deficiencyYes

Putative pathogens presentMore than 50%Bleeding, pusMore than 50%RapidYesIncreasedInadequateFew,isolatedInadequatePresentPresent (bruxism)PoorUnfavorablePresentPoor qualityComplicated

Favorableto prognosis

Good healthNone detectedNoNegativeNormalNoSupplementsNo

Normal floraLes5thanS0%NormalLess than 50%SlowNoNormalAdequateMajority presentAdequateAbsentAbsentGoodFavorableAbsentGoodFavorable

The aim of this article is to pre-

sent the parameters that should be

considered when making a decision

on appropriate therapy. It will try to

establish which path to take when

faced with the dilemma of whether

to retain a tooth orfavorthe implant

option.

Diagnosis and prognosis

Over the last 30 years, the conceptsof the etiology and treatment of peri-odontal diseases have changed con-siderably. The longevity of teeth de-pends directly on the health of theperiodontal tissues. Other etiologic

factors [trauma, endodontic lesions,caries, developmental anomalies,bone lesions) can also lead to theloss of a tooth. However, tooth lossis frequently associated with boneloss,^

The evaluation of a tooth, or anabutment foran eventual prosthesis,requires consideration of periodon-tal, prosthetic, and endodontic fac-tors, as well as the esthetic expecta-tions ofthe patient. The prognosis ofthe residual teeth must be estab-lished, along with a number of localand general factors (Table 1)."'°These parameters affect the deci-sion to extract a tooth^" (Fig 1),

It must also be considered thatsome patients do not respond asexpected to periodontal therapy.These "downhill" patients exhibitcontinuing attachment loss aftertreatment. These cases are definedas refractory periodontitis, which forunknown reasons does not respondto therapy and/or recurs soon afteradequate treatment," This diseaseshould be distinguished from recur-rence, in which a complete remis-sion occurs after therapy. To classifysuch cases as refractory periodonti-tis, the clinician must clearly differ-entiate them from maltreated or in-completely treated cases (Fig 2),

A genetic test (PST, Medical Sci-ence Systems) for susceptibility topendontal disease has been recentlyintroduced. This new informationsupplements existing microbiologieand immunologie tests. It providescritical information that, when com-bined with other risk factors, can beused to determine optimal peri-odontal care. The PST genotype is a

The Internationai Journal of Penodontics St Restoratiue Dentistry

415

Fig 1 a (left) MaxjJJary left canine withadvanced borre loss.

Fig 1b (right) Radiograph tafeen I yearafter loading.

Fig 2a Radiograph of a patient appar-ently suffering from adult periodontitis.

Fig 2b Significant bone loss after I yeardespite periodontsi treatment.

Fig 2c Fo"ow-ijp radiograph after 2years: the progress of the /esions suggestsrefractory periodontitis ürifortunately,coni-entJonai implant treatmeni can nolonger be considered a possibility.

major contributor to a risk factorassessment. Patients with this spe-cific genotype (IL-1) have beenfound to progress more rapidly to-ward severe periodontal disease andshovi/ increased bleeding on prob-ing,'^''^ This genetic test can identifythe subset of patients that is highly

susceptible to rapid disease pro-gression and severe periodontitis.This discovery allows individual pa-tients to be managed in a more tar-geted and proactive way. It is impor-tant to keep in mind that the geneticmarker is not diagnostic; rather, it isa prognostic tool and should be

used to identify patients who are

more susceptible to plaque.

Per/odonta/ considerations

A clinical examination permits an as-sessment of the loss of attachment

Volume 20, Number4, 2000

416

of the remaining teeth. The radi-ographie evaluation is based mainlyon long-cone radiographs. Theseenable determination of the extentand type of bone loss. They may besupplemented by tomography or adental scanner when the extractionof teeth with a poor prognosis is en-visaged. In the posterior segments,the degree of furcation involvementand their morphology will affect thetherapeutic options (conservativetherapy, use of regenerative tech-niques, tunneling, root amputation,hemisection, extraction, or implan-tation).'"

The overall periodontal assess-ment is essential for long-term suc-cess. This allows correct diagnosis,identification of the infecting micro-organisms, and determination ofwhetherthe disease is active or in re-mission and the severity of the peri-odontal damage.

Prosthetic considerations

The clinical crown-to-root ratio isevaluated by radiography. A crown-lengthening procedure could jeop-ardize adjacent teeth. ^ An unfavor-able crown-to-root ratio can occur.The extraction of teeth and the inser-tion ofimplants must be consideredif this ratio is unfavorable. Prepros-thetic orthodontic treatment (forcederuption) must also be consid-ered, i^ ' "

Teeth with short clinical crownsare too often fitted with subgingivalrestorations (which encroach uponthe biologic space) and/or posts thatmay be of a size that weakens the

teeth are inserted into root canals.Encroachment on the biologic spaceleads to chronic inflammation, loss ofattachment, or, in the case of thingingiva, recession.'^ Given a shortclinical crown, the indications for pre-prosthetic surgery must be consid-

Endodontic considerations

Whenever there is a periapicallesion, the possibility of a periodon-tal-endodontic condition must beconsidered in the differential diag-nosis.^^ A lapse of several monthsbefore réévaluation is often neces-sary to allow for healing after rootcanal therapy.

Esthetic requirements

The esthetic requirements of thepatient (especially in the anteriorparts of the mouth) and the "smileline" are among the faaors that de-termine the choice and sequence oftreatment^^ (Fig 3].

Advanced periodontal lesions

Cases of advanced periodontitis arecharacterized by severe bone loss,tooth mobility, and previous loss ofteeth.^" Splinting natural teeth andimplants to support prostheses insuch cases is controversial. The dif-ferences in mobi l i ty betweenimplant and tooth give rise to par-ticular biomechanical problems. Insome cases, the use of combined

abutments to support fixed partialdentures (FPD) to restore the entirearch is advocated.^^'^"^ The aim ofthis prosthesis is to control toothmobility and to resist the forces ofmastication. This type of prosthesisdemands perfect occlusal equili-bration, a high degree of patientcooperation, and regularfollow-up.Some authors have reported favor-able long-term clinical results.^^'^^

Langer and Sullivan^^ considerthat this type of prosthesis, sup-ported on natural teeth, has its lim-itations. Success rates do not exceed5 to 10 years.^^ The main causes offailure are caries and vertical frac-ture of abutments. Failures are usu-ally biomechanical, but are some-times caused by recurrence ofperiodontal disease. The sameauthors believe that the decision toconserve the teeth must be takenon biomechanical considerations. Atooth is retained if it is not mobileand if it does not require root canaltherapy or a coronal restoration.Langer and Sullivan^' also considerthat 4- implants appropriately posi-tioned around the arch and attachedto remaining teeth can adequatelysupport a complete denture. Theanterior teeth are preferably retainedto maintain esthetics and preventfunctional problems.

According to Arnoux,^^ in casesof advanced periodontitis, the useof implants linked to mobile teethmust be seriously questioned. Infact, the difference in mobil i tybetween tooth and implant carriesa risk of biomechanical breakdown.According to this author, it may bebeneficial to retain teeth with


417

reduced periodontal support. Thismay be the case in, for example,the anterior segments where it isdifficult to ensure a good estheticresult, or in the posterior segmentswhere there is insufficient residualbone for reliable implant placement.

The concept of bacterial infec-tion from a periodontal reservoirposing a riskof periimplantitis comesto mind. In the overall treatmentplan, when faced with terminal peri-odontitis, one is sometimes led tothe extraction of the remainingteeth. This strategy avoids the risk of"infectious" periimplantitis.

Fig 3a (left) internal résorption of maxil-lary nght central incisor.

Fig 3 b (above) Cíinícaf appearance afterextraction. Note the horizontal and verticalridge collapse.

Strategic extractions

An extraction is considered to bestrategic if it significantly improvesthe prognosis of the adjacent teethortheoverall prognosis.'"The recentclassifications of periodontitis andthe concept of periods of diseaseactivity and inactivity mean that theconcept of strategic extractions mustbe applied with care. This notion isbased on a rigorous analysis of theprognosis for each tooth (Fig 4).From the prosthetic viewpoint, it ispreferable to extract teeth that arelikely to lead to complications in themedium term. A tooth with a poorprognosis that Is located at a siteappropriate for the placement of along implant must be extracted.^'Also, these strategic extractions per-mit the placement of longer implantsin better positions from the pros-thetic viewpoint. For Lewis,^' thetemporary retention of residual teethcan be necessary for psychologic

Fig 3c Clinical view after 2 years Natejhe regeneration of the papittae. fPros-ihelics by Dr Ed Cohen.)

Fig 3d (right) Follow-up radiograph after2 years.


418

Fig 43 Radiograph shows aduancod pcn-odontilis at masiiiary left first and secondpremoters and terminai periodontitis atsecond mo'ar.

reasons or as support for a transi-tional denture.

Discussion

The type of periodontal disease,

the age of the patient, the loss of

Fig 4b Scan of anterior maxii/a st f/ie levelof the second molar. Note the significanceof bone volume. Two implants were placedimmediately in the premolar extraction sites.

Fig 4c [left] Occhsal view alter 8months. Note the bone regeneration afterremoval ol the membrane.

Fig 4d (above) Foliow-up radiographafter 5 years.

attachment, the degree of bone loss,the number of residual teeth, theresidual bone volume, the wishes ofthe patient, and the predictability of

the outcome of the proposed treat-ment are some of the factors to beconsidered in deciding whetherteeth should be extracted or

retained. Conventional treatmentsfor periodontal diseases have beenshown to be effective^""^^ (Table 2).However, the extraction of a toothwith a poor prognosis must be con-sidered. Prior to the use of endos-seous implants, teeth presentingwith advanced periodontal lesionswere often treated heroically. Today,these teeth are frequently extractedand replaced with dental implants. Anumber of reasonsjustifies this ther-apeutic option: a guarded progno-sis with some periodontal treatmentoptions (for example, root resec-tion^^'^'), or the implant offers a bet-terlong-term prognosisthan naturalteeth.•^'' In the absence of a precisediagnosis and a properly thought-out treatment plan, this approach, ie,implant treatment, borders on over-treatment. According to Lindhe,^^the endosseous implant is an alter-native therapy for missing teeth (asdistal abutments); it is better to treatthe diseased tooth than to place animplant.

In particular, the group of ag-gressive periodontal diseases illus-trates this point Because the choiceof appropriate therapy in thesepatients is incredibly difficult, thor-ough evaluation ofthe periodontalcondition is absolutely essential. Thegreatest caution is advised prior toextracting a single tooth. Wilson etal'"' consider that these patients donot respond to conventional treat-ments. According to Kornman andcoworkers,^^'"^ refractory periodon-titis is characterized by an inade-quate response to traditional peri-odontal treatment. Their resultsshowed that 86% to 90% of the

The Internationa! Journal of Penodontics & Restorative Dentistry

419

refractory periodontitis cases werein smokers. The association of severeperiodontitis with smoking and theIL-1 genotype reported above sug-gests a role for these factors in thepathogenesis and clinical course ofadult periodontitis,'^

In 1996, Priest"" presented areview ofthe literature showing themedium- and long-term results forconventional and adhesive FPDs,The long-term success rates re-ported by the author are very difficultto evaluate (Table 3), They vary from97% for 103 conventional FPDs after23 years"^ to 68% for 59 adhesiveones after 15 years,"^ According toPriest, the lack of standardized para-meters (patients, type of prosthesis,and tooth loss) in the evaluation ofthe results renders an objectiveanalysis ofthe literature difficult,

A statistical examination oftheresults of studies involving dentalimplants for cases of partial eden-tulism (surgical success rates) showsthat they are comparable to thoseobtained with conventional prosthe-ses (Table 4), Haas et al^° obtained a99% success rate for 76 implantsafter 1 to 6 years, Jemt et al* re-ported an 81% success rate for 43implants followed up for from 6 to 15years. The prosthetic success ratesfor implant-supported FPDs in par-tially edentulous cases are very favor-able (Table 4), However, the numberof studies and the smaller number ofpartially edentulous patients treatedwith implant-supported prosthesesare of less significance,

Wiskott^' gives several reasonsthat would lead to making com-promises in choosing whether to

Table 2 Long-term results of periodontal therapy (modifiedafter Carnevale"^)

Study

Hirschfeld and Wasserman 1978'^Ross and Thompson 1978^^McFall 1982^^Goldman etal 1986"Wood et al 1989^^Wang et al 1994"

Period ofobservation (yj

155-2415-2915-3410-34

8

No. of teethobserved

146438716363616487

Successrate (%)

989765938666

Table 3 Long-term success rates for conventional and adhesiveFPDs* (after Priest''")

study

ConventionalReuter and Brose 1984''^Leempoeietal 1985^'Karlsson 1986"Karlsson 1989^^Valderhaug1991^''Giantzetai 1993*^Palmqvist and Swartz 1993**

AdhesiveOlinetal 1991*'Creugersetal 1992*^Wood etal 1993^^Smalesetal 1993™BarrackandBretz1993'*'Thayer et al 1993"^Samama 1995*^Priest 1995"

Totalunits studied

121 prostheses917 units238 prostheses140 prostheses59 prostheses77 patients103 prostheses

103FPDs203 FPDs136 FPDs189FPDs127FPDs85 FPDs145 FPDs77 FPDs

Period ofobservation (y)

11

11,5

10

14

15

15

23

77,5

108

11151011

Successrate (%)

94959383686897

8763705390618361

•FPDs meie made up of a variable No of unirs.

conserve or to implant: (V generalstate of the patient's mouth; (2)length of treatment; (3) motivationofthe patient and the need for theprosthesis; and C4J prognosis ofthedifferent therapeutic opt ions.Equally, the financial cost must alsobe borne in mind when consideringthe treatment options. This is a

frequent cause of refusal of implanttreatment.

After analyzing the results of var-ious types of treatment, the choiceof the appropriate treatment oftenremains difficult (Tables 2 to 4). Theoption chosen should be based onthe best available scientific evidencefor long-term success.


420

Table 4 Medium-term success rates for FPDs in cases of partialedentulism^'^""^''

Tota units studiedStudy ¡implants/prostheses)

ImplantsJemt et al 1989^Jemtetal 1989^Buser etal 1991 "Lekholm et al 1994"Haas etal 1995^*'

ProsthesesJemt et al 1989^Zarb and Schmitt 1993"Lekholm etal 1994^^

44843

5 4

558

76

16746

197

Period ofobservation (y)

1-56-15

31-51-6

1-52-71-5

Successrate {%)

97

81

96

93

99

98100

94

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