Endodontics

Invasive cervical résorption:An analysis of potential predisposing factorsGeoffrey S, Heithersay, MDS (Adel). FDS, RCS (Edin), FRACDS

Objective: An investigation was undertaken to assess potentiai predisposing factors to invasive cervicairesorpi/on. Method and materials: A group of 222 patients with a totai of 257 teeth displaying varying de-grees of invasive cervical résorption were analyzed. Fotentiai predisposing factors, induding trauma, intra-coronal bleaching, surgery orthodontics, periodontal root scaling or pianing, bruxism. deiayed eruption,developmental defects, and restorations were assessed from the patients'history and orai examination.Results: Ot the potentiai predisposing factors identified, orthodontics was the most common sole factor,constituting 21.2% of patients and 24.1 % of teeth examined. Other factors were present in an additionai5.0% of orthodonticaiiy treated patients (4.3% of teeth), and these consisted principatiy ot trauma and/orintracoronai bieaching. Trauma was the second most frequent soie factor (14.0% of patients and 15.1% otteeth). Trauma in combination with intracoronai bleaching, orthodontics, or delayed eruption constituted anadditionai 11.2% ot patients (10.6% ot teeth), intracoronai bieaching was found to be the sole potentialpredisposing factor in 4.5% of patients and 3.3% ot teeth, and an additionai 10 4% ot patients and 9.7% ofteeth showed a combination of intracoronai bieaching with trauma and/or orthodontics. Surgery particu-larly invoiving the cementoenamel ¡unction area, was a sole potential predisposing factor in 6.3% of pa-tients and 5.4% of teeth. Periodontai therapy induding deep root scaiing and pianing. showed a low inci-dence, as did other factors, such as bruxism and developmental defects. The presence of an intracoronairestoration was the oniy identifiabie factor in 15.3% of patients and 14.4% of teeth, while 15.0% of patientsand 16.4% of teeth showed no identifiabie potentiai predisposing factors. Conclusion: These resuits indi-cated a strong association between invasive cervical résorption and orthodontic treatment, trauma, and in-tracoronai bieaching. either alone or in combination. (Quintessence int 1999:30:83-95)

Key words: externai résorption, invasive cervical résorption

CLINICAL RELEVANCE: Ciinicians should be alert tothe possibility of invasive cervicai résorption, especiaiiyfciiowing trauma, intracoronai bleaching, or orthodontictreatment aione or in combination. Periodic radiographiechecks are necessary for those teeth that might be con-sidered to be at risk.

Invasive cei^ical résorption is an insidious and oftenaggressively destructive form of external root résorp-

tion that is characterized by invasion of the cervicalregion of the root by fibrovascular tissue derived fromthe periodontal ligament. This pathologic process pro-gressively resorbs cementum, enamel, and dentin, toeventually involve the pulp space late in the process.

•Clinical Associate Professor, Department of Dentistry, University of Ade-laide. Adelaide, South Australia, Australia.

Reprint requests: Dr Geoffrey S. Heithersay, Gawler Chambers, IBS NorttiTerrace, Adelaide, South Austraiia 5000, Australia. Fax: 61-8-8410-0709.

Ectopic calcifications can also be obset^ed in advancedlesions, both within the invading fibrous tissue anddeposited on the resorbed dentin surface. The clinicaland histopathologic features of this condition havebeen outlined in a previous publication.'

The etiology of invasive cervical résorption is un-known, but several potential predisposing factors havebeen suggested. Of these, intracoronai bleaching-reiated résorption has heen the most widely docu-mented factor, following the initial report by Harring-ton and Natldn in 1979̂ (for a review, see Heithersayet aP). Trauma has also been recognized as a potentialcause of "late external root résorption," the clinicaldescription of invasive cervicai résorption adopted byCvek in 1981.'' Other potential predisposing factorsthat have also been explored include orthodontics,orthognathic and other dentoalveolar surgery, andperiodontai treatment.̂ -^

The present investigation was undertaken to assessvarious potential predisposing factors in a relativelylarge group of patients presenting with varying degreesof invasive cervical résorption.

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Class 4

Fig 1 Clinical classilicalion ol invasive cervical résorption.

METHOD AND MATERIALS

The subject material consisted of 257 teeth displayinginvasive cervical résorption in 222 patients who hadbeen referred to the specialist endodontic practice ofthe author. Patients underwent a clinical and radiologieexamination, and photographic records were taken

where appropriate. Specific details of age, sex, andmedical and dental history were recorded. Complete-mouth radiographie surveys were taken whenever mul-tiple résorptions were deemed a possibility.

The potential predisposing factors were assessedfrom the patients' history and oral examination. Datesof specific incidents or treatments were also recorded.

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Q.

OJ

m

60-64•

55-59

5G 54

45-4940-44

35-3930-34

25-29 ^ K20-2415-19tO-14

0

' 1

5

a Female• Male

10 15 £0 25No. ol patients

5 10 15 20 25 30

No. oí patients

Fig 2 Invasive cervioal résorption: Sex and age distribution altime ol diagnosis.

Fig 3 Invasive cervical résorption: Tiie number o( patients ac-cording to age group and severity of résorption.

The following factors were caiegorized and described:

1. Trauma. The age at the time of trauma along withseverity of trauma. Details of tionsurgical rootcanal treatment or adjunctive treatment, eg, intra-coronal bleaching.

2. Intracoronal bleaching. In patients with a historyof intracoronal bleaching, details of previousinjuries or treatment, and the number and timingof intracoronal bleaching treatments.

3. Surgery. The type of surgerj' in the related area,eg, surgical removal of unerupted or partiallyerupted teeth, or transplantation.

4. Orthodontic treatment. The ages at the commence-ment and completion of orthodontics, and theorthodontic method employed.

5. Periodontal root scaling or planing. The severityof periodontal involvement and the duration oftreatment.

6. Bruxism. The approximate duration of bruxingand the degree of tooth wear.

7. Delayed eruption.8. Developmental defects.9. Other potential factors. Any other treatments or

incidences that may he considered to be related tothis condition.

10. Intracoronal restorations. When no other poten-tial predisposing factor was identifiable, the pres-ence of coronal restoration was recorded.

The degree of invasive cervical résorption for eachtooth was recorded according to the following clinicalclassification (Fig 1):

1. Class 1. Denotes a small invasive resorptive lesionnear the cervical area with shallow penetration intodentin.

2. Class 2. Denotes a well-defined invasive resorptivelesion that has penetrated close to the coronal pulpchamber but shows little or no extension into theradicular dentin.

3. Class 3. Denotes a deeper invasion of dentin byresorbing tissue, not only involving the coronaldentin but also extending at least to the coronalthird of the root.

4. Class 4. Denotes a large invasive resorptiveprocess that has extended beyond the coronalthird of the root canal.

The data were subjected to frequency analysis,which was the only statistical method deemed applica-ble to this study.

RESULTS

Of the 222 patients, 114 were females and 108 weremales. The sex and age distribution at the time of diag-nosis is shown in Fig 2. The ages varied from 11 to 75years; the mean age was 37 years. Figure 3 indicatesthe severity of invasive cervical résorption, as definedin Fig 1. by age group. The total number of teeth fromthis patient sample was 257, and their distribution isoutlined in Table 1.

The analysis of potential predisposing factors forthe patients is sutnmarized in Fig 4.

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TABLE 1 Distribution of teeth showing invasivecervical résorption

Tooth

Central incrsorLateral incisorCanineFirst premolarSecond premolarFirst molarSecond molarThird molar

Maxillary

75233423

2072

Mandibular

12131347

26133

TABLE 2 Distribution of patietits and teethassociated with trauma aione or in cotnbinationwith other factors

Polentialpredisposing factors

Trauma as a sole factorTrauma and bleachingTrauma and orlbodonticsTrauma, bleaching, and

orthodonticsTrauma and delayed eruptionTotal

No, ofpatients (%)

31 (14.0%)17 (7.7%)3 (1.4%)4 (1.8%)

1 (0,5%)56 (25,2%)

No,otteeth (%)

39(15,1%)19 (7,4%)3 (1.2%)4 (1,6%)

1 (0,4%)66 (25,7%]

TraumaIntracoronalbleacbing

SurgeryOrthodonticsPenodoniics

BruxismDelayed eruption

Developmental defectsInterproximal stripping

RestorationUnknown

• Sole factorsD Additional factors

10 20 30 40 50 60 70No ol patients

Fig 4 Invasive cervical résorption. Distribution of potential pre-disposing factors lor patients.

Trauma

The distribution of teeth and patients showing traumaand related factors is shown in Table 2, The teeth mostfrequently affected by a sole history of trauma werethe (1) maxillary central incisors {7.8°/ii), (2) mandibu-iar lateral incisors (2,3%), (3) mandibular central in-cisors fl,6"/o), and (4) maxillary canines (1,2%).

Illustrative case report. A 45-year-old man pre-sented for a routine examination. His maxillary leftcentral incisor had been luxated palatally 21 years ear-lier, repositioned, and splinted. The tooth was asymp-tomatic but showed a pink discoloration near the gin-gival margin on the palatal aspect (Fig 5a), and thelabial surface showed a small, dark surface defect (Fig

5b). A radiograph (Fig 5c) showed a large, irregular ra-diolucent area extending to the crown and root. Therésorption was classified as class 3,

Intracoronal bleaching

The distribution of patients and teeth showing intra-coronal bleaching and related factors is shown inTabie 3, The teeth most frequently affected by a solehistory of intracoronal bleaching were the (1) maxil-lary central incisors (3,1%) and (2) maxillary lateralincisors (0,3%),

Illustrative case report. The patient, a 42-year-oldman, noticed an irregularity on the palatal aspect oíhis maxillary left lateral incisor. Examination revealedan erosive defect containing soft tissue on the palatalsurface of the incisor (Fig 6a); the labial surface wasintact (Fig 6b). No symptoms were associated withthis lesion. The patient had received fixed orthodontictreatment at 20 years of age, when he was a dentalstudent.

When he was 23 years old, his lateral incisor wasluxated palatally while playing soccer. It was reposi-tioned within 30 minutes and splinted, Nonsurgicalroot canal treatment proved necessary. This was fol-lowed by intracoronal bleaching with 30% hydrogenperoxide activated thcrniocatalytically by an ultravio-let lamp applied intermittently for 5 minutes.

This was followed by a "walking bleaeh," in which acofton pellet, saturated with 30% hydrogen peroxide,was sealed into the pulp chamber with Cavit (ESPE)for 6 days. The procedure was repeated, and 8 dayslater the access cavity was restored. The tooth wasreassessed 2 and 7 years later, at which times therewas no radiographie evidence of invasive eervicalrésorption or periapical pathosis (Fig 6c),

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Fig 5a Palatal view of the anterior teeth of a 45-year-olcl man•,vnose maxillary left central incisor had been palatally luxaled 21years previously. Note the pink discoloration in tfie gingival third ofthe crown

Fig 5b "The enamel of Ihe labial surface of the maxillary leftcentral incisor displays a defect resulting from the trauma thai hadoccurred 21 years earlier

Fig 5c (lefi) The radiograph of the maxillary left centrai incisorreveals a large radiolucency superimposed over the outline ol theroot canal

TABLE 3 Distribution of patients and teethassociated with intracoronal bleaching aloneor in combination with other factors

Potentialpredisposing faetcrs

Bleaching as a sole faetorBleaching and traumaBieaching and orthodcnticsBleaching, trauma, and

orthodonticsTolal

No. ofpatients (%)

10 (4.5%)17 (7.7%)2 (0.9%]4 (1.8%)

33(14.9%.)

No. cfteeth (%)

10 (3.9%)19 (7,4%)2 (0.8%)4 (1 6%)

35(13.6%)

lntracoronai bleaching using the same procedurewas repeated at the 7-year recall. The subsequentradiographie records suggest that, during the rehleach-ing procedure, additional gutta-percha had beenremoved and replaced with another material withinthe canal, presumably as an additional seal.

The patient presented 12 years after the second¡ntraeoronal bleaching procedure, when he noticed anirregularity on the palatal aspect of the same left lateralineisor. Evidence of an extensive resorptive process in:he previously root-filled incisor was shown•adiographically by the presence of a radiolucent areait the mesiocervical region of the left lateral incisor, ex-

tending 3 to 4 mm into radicular dentin and cementum(Fig 6d). In addition, a periapical radiolucency couldbe observed, indicative of a periapical inflammatory re-sponse probably resulting from microbial leakage of theroot canal filling via the resorptive defect. The lesionwas classified as a class 3 invasive cervical résorption.

Surgery

The distribution of patients and teeth showing surgeryand related factors is shown in Table 4. The type ofsurgery varied. The removal of adjacent partially orfully unerupted third molars or superntimerary teeth

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Fig 6a Palatal view ot the anterior ¡eetii of a 42-year-oid manwhose maxillary left incisor tooth had been luxated 19 years ear-lier, 2 years after reoeiving orlhodohtic treatmeht. Nonsurgicai rootcahal treatment and intraooronal bleaohing proved neoessary,and intraooronal bleaohing was repeated 7 years later Note theerosive defect at the mesiogirgivai surface, evident 12 years afterthe second intracoronai bieaching procedure.

Fig 6b The ¡abiai surface oí the maxiiiary left lateral incisorshows some discoloration near the gingival margin but is other-wise intact.

Fig 6c A radiograph taken 7 years aftertrauma, nonsurgical root canai treatment,and intracoronai bieaching shows no evi-dence of résorption or periapicai pathosis.

Fig 6d A radiograph of the ma^iiiary leftiaterai incisor taken 12 years after a secondinlracoronai bleaching procedure showsevidence of e>;tensive invasive cervical ré-sorption extending into the radicuiar andccronai looth structure. A periapicai radiolu-cency, indicative of periapicai patfiosis. isaiso evident.

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Fig 7a Labial surface ot the maxillary lefi canine of a 28-year-oldwoman wtio had surgery to expose an unerupted canine at theage ot 14 years. Protracted orthodontic treatment followed. Notethe irregularity at the distogingival surface with an associated softtissue ulcération.

Fig 7b The palatai surtace of the maxillary left canine is intactand shows no clinical signs of résorption.

Fig 7c (left) The radiographie appearance at the maxiilary ieltcanine reveáis an irregular ladioiucency extending to the radicuiarIhird of the tooth and to the ccronai tooth structure in a crescentaipatlern.

TABLE 4 Distribution of patients and teethassociated with surgery alone or in combinationwith other factors

Potentialpredisposing factors

Surgery as a soie factorSurgery and orthodonticsSurgery and periodontai

therapyTotai

No. ofpatients (%)

13 (5,9%]1 (0,5%)1 (0.5%)

t5(6.8%)

No. Otteeth (%|

13(5.1%)1 (0.4%)1 (0.4%)

15(5 8%)

occurred in eight patients (eight teeth). Transplan-tation of canine teeth had been carried out in threepatients (three teeth) and the surgical exposure of anunenipted canine was performed in one patient {onetooth). Periodontal surgery involving root amputationhad been performed in one patient (one tooth).

Illustrative case report. A 28-year-old woman pre-sented with localized swelling of the gingival tissuesassociated with her maxillary left canine, which dis-

played a resorptive defect near the distogingival mar-gin [Figs 7a and 7b), Her dental history indicated thatthe previously unerupted canine had been surgicallyexposed when she was 14 years old, prior to orthodon-tic treatment. Records indicated that orthodonticmovement of this tooth was difficult and protracted.The radiograph (Fig 7c) indicated a class 3 résorptiondefect, with extensions both eoronally and apically forat least a third of its depth.

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Fig 8a Labial view o( tiie anterior teeth of a 2e-year-old womanwho haa received li\ed orthodontic treatment 14 years eariier. Tiiemaxiilary right centrai incisor shows a pink disco i oration near thegingivai margin.

Fig 8b The paiaiai surface of the maxiiiary righ\ centrai incisorappears normai

Fig 8c (ieft) The radiograph of the maxillary right central incisorreveals an irregular radioiucency overlying the rool canai outline.

TABLE 5 Distribution of patients and teethassociated with orthodontics alone or incombination with other factors

Potentialpredisposing factors

Orthodontics as a sole factorOrthodontics and traumaOrthodontics and bleachingOrthodontics, trauma, and

bieachingOrthodontics and surgeryOrthodontics and periodontal

therapyTotal

No. ofpatients (%)

47(21.2%)3 (1.4%)2 (0.9%l4 (1.8%)

1 (0.5%)1 (0.5%)

58 (26.2%]

No. ofteeth (%)

62(24.1%)3 (1.2%)2 (0.8%)4 (1.6%)

1 (0-4%¡1 (0.4%)

73 (28-4%)

Orthodontics

The distribution of patients and teeth showing ortho-dontics and related factors is shown in Tahle 5. Theteeth tnost frequently affected by orthodontics were (Ijmaxillary canines (6.2%), (2) maxillary central incisors(4.3%), (3) mandibular molars (2.3'>/o), and (4) maxillaryand mandibular incisors (\.9%). In those patients with ahistory of orthodontics alone, multiple résorptions wererecorded in six patients (2.7%). Of these patients, onehad seven teeth involved, two patients had four teeth

involved, and three patients had two teeth involved.Illustrative case report. A 28-year-old woman pre-

sented with a pink discoloration of the crown of herasymptotTiatic maxillary right central incisor (Figs 8aand 8b). The patient had received fixed applianceorthodontic therapy 14 years earlier, apparently un-eventful both during and after the 2-year treatment pe-riod. The radiograph revealed an irregular radioiu-cency extending from the cervical area into the crown(Fig 8c). This lesion was classified as class 2 invasivecervical résorption.

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Periodontal therapy

The distribution of patients and teeth showingperiodontal therapy and related factors is shown inTable 6,

Bruxism

Six patients (2,8%) with SL\ teeth (2,4%) showed a his-tory of bruxism,

Deiayed eruption

Delayed eruption resulting from tooth impaction wasfound in three patients (1,4%) with four teeth (1,6%),One other patient had an additional history of trauma,which resulted in a total of four patients (1,8%) withfive teeth (1,9%) where delayed eruption was involved.

Illustrative case report. The mandibular right ca-nine of a 35-year-old man had been submerged untilthe patient was in his early 20s, at which stage its fulleruption was still impeded by crowding in themandibular arch (Fig 9a), Radiographic evidence ofinvasive cervical résorption could be observed inboth the mandibular right canine (Fig 9b) and thefirst premolar (Fig 9c), The lesions were classified asclass 3,

Developmental defects

Developmental defects were recorded in two lateralincisors (0,8%) of one patient (0,5%),

Other factors

Interproximal stripping was the only other potentialpredisposing factor identified.

Illustrative case report. A 22-year-old woman'smaxillary anterior teeth had been treated 3 years ear-lier by a general dental practitioner who performed in-terproximal stripping in an attempt to reduce anteriorcrowding. Advanced invasive cervical résorption waspresent in the maxillary right canine tooth, as was evi-dent clinically (Fig 10a), Radiographie examinafion re-vealed evidence of a deeply infiltrating resorptiveprocess surrounding an apparently intact ruot canal(Fig 10b). The lesion was classified as class 3,

intracoronal restorations

The presence of an intracoronal restoration was theonly identifiable factor in 34 patients (15,3%) with 37teeth (14,4%),

In 33 patients (14,9%) with 36 teeth (16.4%), nopredisposing factors could be identified.

TABLE 6 Distribution ot patients and teethassociated with periodontal therapy alone or incombitiation with other factors

Polentialptedisposing factors

Periodontal therapy as asole lactor

Periodontal therapy andorthodontics

Periodontal therapy andsurgery

Total

No, ofpatients (%)

4(1.8%)

1 (0 57c)

1 (0,5%)

6 (2,8%¡

No.olteeth (%)

4(1,6%]

1 (0,4%)

1 (0.4%)

6 (2,4%)

DISCUSSION

To date, there do not appear to have been any previ-ous epidemiologic studies that specifically indicatethe proportion of a population group that may de-velop invasive cervical résorption. The present sampleof patients referred to the author, a specialist en-dodontist with a special interest in the condifion, rep-resents approximately 0,02''.''o of the population ofAdelaide, a city of approximately 1,2 million people,Several statistical tests were considered for this study,including analysis of variance, but the nonrandom-ized nature of subjects indicated that the only validstatistical method applicable was that of frequencyanalysis.

There was little overall difference between malesand females in the incidence of invasive cervical ré-sorption, but there were some interesting age groupvariations. In the 35- to 39-year-old group, the major-ity were males, which contrasted with the 45- to 49-year-old group, where the sex distribution was re-versed. While an analysis of potential predisposingfactors for the two groups gave no indication for thepredominance of females in the 45- to 49-year-oldgroup, males in the 35-year-old group had a pre-dictably greater history of dental trauma than females,no doubt resulfing from a greater participafion in con-tact sports. Surprisingly, males in this group also had agreater history of orthodonfic treatment.

For invasive cervical résorption to be inifiated, tbenormally protective cementum-eementoid layer mustbe deficient or damaged,' This may have occurreddevelopmentally or can be caused by physical orchemical trauma. Chemical trauma may be involved inthe initiation of invasive cervical résorption associatedwith intracoronal bleaching with hydrogen peroxide,Intracoronal bleach-related cervical résorption hasreceived the attention of the dental profession sincethe first case reports in 1979,'

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Fig 9a Delayed eruption of the mandibular right canine in a 35-year-oid man because of arch crowding.

Fig 9b Tine radiograph cf the mandibularright canine reveals an extensive radiolu-cency extending principally into the crown.

Fig 9c An irregular radiolucency indicativeof Invasive cervicai résorption is also evi-dent in the adjacent mandibuiar premoiar.The pulp outiine is demarcated from the ra-diolucency by a radiopaque line.

The results of the present study show that ¡ntra-eoronal bleaching was the sole potential predisposingfactor in 4,5% of patients (3.9''/o of teeth). When com-bined with other potential predisposing factors, 14.9%of the patients surveyed, or 13.6"/o of the teeth, showeda history, at some stage, of intracoronal bleaching withhydrogen peroxide. The intracoronal bleachingmethod varied between a thenitocatalytic techniquewith hydrogen peroxide and the walking bleachingmethod using hydrogen peroxide alone or mixed withsodium perborate. A combination of the two methodshad also been used.

Two studies have assessed the incidence of intra-coronal bleaching-related résorption. Friedman et a\'found an incidence of 6.8"/o in a sample of 58 teethtreated by either a thermocatalytic or a walkingbleaching technique. None of the teeth had a historyof trauma, A more recent study of 202 patientstreated with a comhination of thermocatalytic andwalking bleaching reported an incidence of 1.96%.'All teeth with résorption in this study had a history oftratima.

This was also the case in each of the seven cases ofinvasive cervical résorption reported by Harrington

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Fig 10a Pdlatal view of the maxiliary right canine ol a 22-year-oldpatient who had a history ot interproximal stripping. The palatalsurface of the maxillary right canine shews extensive tooth loss;(he cavity contains reddish-pink soft tissue.

Fig 10b A radiograpn of Ihe maxiliary right canine showsevidence of an extensive iesion extending coronaily and deeplyinto the radicular dentin. Nole the retained outline ot the root canalsurrounded by the irreguiar radiolucency.

and Natkin in 1979.- These authors suggested thatleakage of bleaching agent from the pulp chamberthrough patent dentinal tubules into the cervical peri-odontal tissues may he sufficient to initiate the resorp-tive process. Furthermore, a passage of hydrogen per-oxide from the pulp chamber of root-filled teeth to theexternai surface during intracoronai bleaching with30% hydrogen peroxide was demonstrated by Rotsteinin 1991* and found to be facilitated by the presence ofcémentai defects at the cementoenamel junction."^

Further information regarding the possible patho-genesis of intracoronai bleaching-related résorptionhas been provided by recent studies that demonstratedhydroxyl radical activity at the external root surfacefollowing the thermocatalytic intracoronai bleachingof root-filled teeth." The hydroxyl radical is one of anumber of oxygen-derived free radicals that can de-stroy components of connective tissue, inciuding theperiodontal ligament. These hydroxyl radicals couldbe involved in the initiation of postbleaching invasivecervical résorption, particularly if a tbermocatalyticmethod has been employed.

Invasive cervical résorption has been identified as along-term eomplication of luxation and exarticulationinjuries,-* and the relatively high incidence of 25.2% ofpatients (or 25.7% of teeth) in this study confirmstrauma as a potential predisposing factor. It suggeststhat the injury has left the cementum surface dam-aged, deficient, or altered in character, thereby allow-

ing the possibiiity of ingrowth of potentially resorbingcells from the periodontal ligament. Maxillary centralincisors were those predominant recorded in thisstudy, and this observation is consistent with theirstrategic vulnerability to dental trauma. The presentstudy also showed that more than one factor may beinvolved in the same patient, and this was particularlysignificant when there had been a history of traumaand bleaching.

Surgical procedures involving the sensitive cemen-toenamei junction were identified as potential predis-posing factors in 6.80/0 of patients (5.8% of teeth). Thisrepresents a comparatively low incidence, consideringthe frequency of such treatment procedures. The re-moval of unerupted third molars has the potential fordamage to the cementoenamel junction of the adja-cent second molar, while the exposure of uneruptedcanines for orthodontic purposes may cause similardamage, especially if a cervical wire ligature is usedrather than a bonded bracket. Similar damage to thecementoenamel junction also occurred in one patientwho had a history of interproximal stripping.

There were three patients with a history of orthog-nathic surgery who displayed root résorption withsimilarities to invasive cervical résorption. However,these patients were excluded from this study, becausethe predominating type of résorption was replacementrésorption resulting from loss of the periodontal liga-ment and progressive root replacement by bone.

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The highest incidence of invasive cervical résorp-tion was found in patients with a history of orthodon-tic treatment; the résorption was detected as early as18 months after tbe removal of appliances or as late as33 years. There was no correlation between the orth-odontic technique employed and the development ofthis type of résorption. Some degree of surface résorp-tion can occur during orthodonric treatment,'^ This ré-sorption is usually transitory and wili undergo repairafter the removal of orthodontie forées,'̂ However, ifsurface résorption of eementum exposes the underly-ing dentin, then a potential will exist for résorption tobe initiated by mononuclear precursor cells from tbeperiodontal ligament, sbould tbey be stimulated byotber factors. For example, pressure caused by exces-sive orthodontic forces may result in localized tissuenecrosis adjacent to denuded eementum. The resultingtissue metabolites may stimulate mononuclear precur-sor cells to differentiate into specific clastic cells,which couid cause active résorption.

It is of interest to note that, of the teeth with a his-tory of ortbodontics, maxillary canines were the mostcommonly recorded in this study, occurring as multi-ples in two patients. Recause of their position, toothlengtb, and bone support, canines often are more resis-tant to ortbodontic movement tban other teeth in thedental arch. Furthermore, if class 2 elastics are used intreatment, they are attached to the maxillary caninesand the mandibular first molars. This may translateinto greater forces on one root surface, whieh couldpredispose the area to invasive cervical résorption.

Maxillary central incisors were tbe next most fre-quently affected teeth. This bigh incidence may be dueto tbe position of the maxillary central incisors at theapex of the dental areh, where they couid be subjectedto greater tooth movement tban other teetb in thedentition. Mandibular molars were tbe third most fre-quently affected teeth. These teeth are often used asanchor teeth, and the orthodontie treatment may sub-ject some root surfaces to localized and perhaps exces-sive pressure during treatment.

Multiple résorptions were present in six patientswitb a history of ortbodontics, the number varyingfrom two to seven teeth per patient. This suggests aneed for a complete-mouth radiographie examinationfor any patient with a history of orthodontic treatmentwho develops invasive cervical résorption.

The apparent association between invasive cervicalrésorption and orthodontic treatment must be viewedwithin the context of the frequency of orthodontictreatment within tbe community. There has been a sig-nificant inerease in the use of orthodontic serviceswithin South Australia since 1973, when a study indi-cated that only 7% of patients to the age of 14 yearswere using specialist orthodontic services.'"^ However,

that study did not assess the extent of orthodontictreatment provided by the State School Dental Serviceand general dental practitioners at tbat rime. A morerecent study of the use of orthodontic services by a co-bort of adolescents enrolled in tbe South AustralianSchool Dental Service program'^ showed that, by age15 years, 27,30/o of young patients had received fixedorthodontic treatment, and 15.3% had also beentreated by removable appliances.

An association between invasive cervical résorptionand orthodontics has been reported previously,̂ * Theendodontic implications of orthodontic treatment havebeen studied in 87 patients, aged 20 to 25 years, whohad received ortbodontic treatment earlier in tbeirlives. The authors recorded only one case of cervical ré-sorption in an incisor, representing 1.5% of the group,'*A control group of a similar age range showed no evi-dence of cervical résorption. It should be noted thatoniy anterior teeth were examined in tbat study. In ad-dition, tbe lag time between ortbodontic treatment tothe diagnosis of invasive cervical résorption can vary,and tbis sbould be taken into consideration in atiycomparative study. In the present study, the average ageof detection of invasive cervical résorption in patientswith a history of orthodontic treatment was 31,5 years.

Despite the opinion that cémentai defects appear topredispose teeth to this type of résorption,' periodon-tai therapy with deep scaling or root planing was notidentified in this study as a major potential predispos-ing factor, being recorded as a sole factor in only fourpatients (1,8%) witb four teetb (1.6%), When com-bined with other factors, namely, surgery or orthodon-tics, the incidence was still low (2,8% of patients; 2,4%of teeth}, Tbis may be due to the fact that in chronicperiodontal disease there may be inhibition or de-struction of the precursor resorbing cells in the peri-odontai ligament in the area of denuded eementum, orrapid epithelial downgrowth may effectively preventcontact of connective tissue eells with that surface,=

Of the six patients with invasive cervical résorptionassociated with bruxism, it was perhaps significant tothe occupational stress of our profession that twowere dentists and one a medical practitioner

The presence of intracoronal restorations may havelittle significance in anterior teeth, but in posteriorteeth they can be associated with the development ofdcntinai and cémentai cracks, especially if the restora-tions are supplemented with pins. Such cracks oftenextend into the periodontal ligament and, accordingly,may ailow invasion of resorbing tissue.

Delayed eruption resulting from tooth impaction,observed in four patients (1.8%) and five teeth (LWo),tends to leave a tooth crown partially surrounded byattached gingival tissues. This may result in eonditionssimilar to those obtained experimentally when gingival

94 Volume 30, Number 2, 1999

Heithersay

flaps are coronally repositioned.'' In these experi-ments, invasive cervical résorption was observed in as-sociation with a high proportion of root surfaces.

While 14.9% of patients (16.4% of teeth) did nothave a registrable potential predisposing factor, it ispossible tbat some may have had undetectable devel-opmental defects, such as hypoplasia or hypomineral-ization of cementum.

In 28.90.0 of patients, there was more than onepotential predisposing factor (for example, 7.5% ofpatients had a history of trauma and intracoronalbleaching). These observations confirm a need forcareful follow-up examinations for such patients.

The present analysis shows that the majority ofcases referred for treatment were classified as class 3severity (see Fig 3)- In lesions with this classification,there has been invasion of resorptive tissue into thecrown and at least one third the length of the root.Résorptions of this magnitude usually have a compli-cated structure.' Not only is there invasion hy fibro-vascular tissue, but ectopic calcifications both occurwithin the fibrovascular tissue and are deposited onthe resorbed dentin. A series of channels containingresorptive tissue are present, and they usually haveconnections furtber apically with the periodontal liga-ment. The pulp space is surrounded by tbe resorbingtissue, but generally this is walled off by a thin layer ofintact dentin and predentin.

Detection of invasive cervical résorption at an earlystage is important, because it provides a clinician withthe possibility of treating such lesions with a satisfac-tory degree of success. While several methods of treat-ment can be employed, a technique involving the topi-cal application of trichloracetic acid, curettage,nonsurgicai root canal treatment, where necessary,and restoration with glass-ionomer cement will heoutlined in a further report, along witb the long-termresults of such a treatment regimen for each of thefour classes of invasive cervical résorption as definedin this study.

CONCLUSION

This study has attempted to identify potential predis-posing factors in the development of invasive cervicalrésorption. There appear to be strong associations be-tween the incidence of invasive cervical résorptionand orthodontic treatment, intracoronal bleaching,and dental trauma, alone and in cotnbination, butfurther investigations with randomized samples arewarranted.

REFERENCES

1. Heithersay GS. Clinical, radiologie, and histopathologic fea-tures of invasive cervical résorption. Quintessence Int1999;30:27-37.

2. Harrington GW, Natkin E. Esternal résorption associatedwith the bieiitliing of pulpless teeth. | Endod 1979;5-344-348.

3. Heithersay GS, Dahlstrom SW, Marin PD. Incidence ofinvasive tervical résorption in bleached root-filled teeth.Aust Dent I 1994 ;39:82-87.

4. Cvek M. Endodontic treatment of traumatiscd teeth. In;Andreasen )0 (ed). Ttaumatic Injuries of the Teeth, ed 2.Copenhagen: Munksgaard, 1981:362-363.

5. Tronstad L. Root resorption-Etiologi', terminology and elin-icai manifestations. Endod Dent Traumatoi 1988;4:241-252.

6. Trope M, Chivan N. Root résorption. In: Cohen S, BurnsRC (eds). Pathways of the Pulp, ed 6. St Louis: Mosby,1994:493-503.

7. Hammarstrom L, Lindskog S. Factors regulating and modi-fying dental root résorption. Pri>c Finn Dent Soc 1992;88(suppll):115-123.

8. Friedman S, Rotstein I, Libfield H, Stabliolz A, Heling TIncidence of external root résorption and esthetic results in58 bleached pulpless teeth. Endod Dent Traumatoi 1988;4:23-26.

9. Rotstein I. In-vitro determination and quantification of 30%hydrogen peroxide penetration through dentin and cemen-tum during bleaching. Oral Surg Oral Med Oral Fathol1991:72:602-506.

10. Rotstein 1, Torek Y, Misgav R. Effect of cementum defectson radicular penetration of 30"''Û H^O^during intracoronalbleaching. I Endod 1991;17:230-233.

11. Dahlstrom SW, Bridges TE, Heithersay GS. Hydroxyl radi-cal activity in thermocatalytically bleached root filled teeth.Endod Dent Traumatoi 1997:13:119-125.

12. Barber AF, Sims MR. Rapid maxillary expansion and exter-nal root résorption in man: An SEM study. Am ) Orthod1981:79 630-652.

13. Langford SR, Sims MR Root résorption, repair, and peri-odontal attachment following rapid maxillary expansion inman. Am J Orthod 1982:81:108-115

14. Bajada S. Ulilisation of Orthodontic Services in SouthAustralia |thcsis|. University of Adelaide, 1973.

15. Allister JH, Spencer AJ, Brennan DS Provision of ortho-dontic care to adolescents in South Australia: The type, theprovider, and the place of treatment. Aust Dent J 1996:41:405-410.

15. Cwyk F, Saint-Perre F, Tronstad L. Endodontic implicationsof orthodontic tooth movement [abstract 1039]. J Dent Res1984:63.

17. Bogle G, Claffey N, Egelberg |. Healing of horizontal cir-cumferential periodontal defects following regenerativesurgery in beagle dogs. J Clin Pcriodontol 1985:12:837-849.

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