Consequências do Clareamento Interno dos Dentes

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<p>By Dr Alexander Bearham, 5th Floor, 766 Elizabeth Street, Melbourne, Victoria, 3OOO</p><p>The Consequences Of Internal Tooth</p><p>Bleaching</p><p>Introduction</p><p>Tooth bleaching has long been recognised as an integral part of</p><p>both endodontic and general dental practice for management of</p><p>intrinsically and extrinsically stained teeth. Causes ranging from</p><p>tetracycline staining to discolouration associated with a non-vital</p><p>tooth. present different management needs. Each case will require</p><p>individual assessment in relation to bleach application and delivery</p><p>and a tailor-made treatment plan to obtain a satisfactory outcome.</p><p>Historically. teeth have been bleached with a variety of</p><p>techniques and delivery systems depending on the location of the</p><p>discolouration and the speed with which results are desired. These</p><p>include heat activation of hydrogen peroxide carried out in the</p><p>surgery under rubber dam for expedient results; home delivery</p><p>systems using carbamide peroxide in a custom tray for external</p><p>application taking several weeks; and sodium perborate in</p><p>combination with water or hydrogen peroxide placed in the pulp</p><p>chamber as a "walking bleach". Each of these techniques may have</p><p>various modifications, such as acid etching, depending on operator</p><p>preference.</p><p>The application of bleaching agents to the teeth is not without</p><p>risks. Each technique has its own potential side effects ranging from</p><p>the inconsequential such as failure of the bleach to positively modify</p><p>the discolouration. to severe root resorption and loss of the tooth.</p><p>Whilst home bleaching with carbamide peroxide appears to be</p><p>relatively "risk free" to the patient, the use of bleaching agents inside</p><p>the pulp chamber is not.</p><p>Harrington and Natkin ( I ) in I 979 reported four cases of cervical</p><p>external root resorption following internal bleaching with "a caustic</p><p>bleaching agent and a heat source". In all cases "the resorptive</p><p>lesions occurred in the cervical third of the root with no evidence</p><p>of resorption elsewhere" and all occurred within two years of</p><p>bleaching. The authors drew no firm conclusions but set the scene</p><p>for further investigation, as other potential causes of resorption</p><p>could not be ruled out.</p><p>Tronstad (2) states "in most instances cervical resorption is seen</p><p>as a late complication to traumatic injuries of the teeth". "It may also</p><p>occur after . . . bleaching of teeth and a wide variety of traumatic</p><p>conditions".</p><p>Other case reports (3-6) also relate recent bleaching with</p><p>hydrogen peroxide using chairside and walking techniques to</p><p>cervical root resorption without trauma playing a prominent role.</p><p>Various hypotheses have been discussed in relation to the cause of</p><p>resorption. Most seem to point to the action of hydrogen peroxide</p><p>permeating the cervical dentine below the level of soft tissue</p><p>attachment and acting on the periodontal ligament or cementum in</p><p>such a way as to initiate the resorptive process.</p><p>Madison and Walton (7) studied the effect of intra-chamber</p><p>hydrogen peroxide in beagle dogs and found "when heat and</p><p>hydrogen peroxide were used in combination. resorption was</p><p>induced in a few cases".</p><p>Friedman et ol (8) in a review of 58 bleached pulpless teeth</p><p>noted advanced external resorption in two cases and arrested</p><p>I36</p><p>resorption in a further two cases. All cases were bleached with</p><p>hydrogen peroxide and there was no history of trauma. This</p><p>equated to an incidence of 6.9%. however it is important to note</p><p>that no barner was placed over the exposed gutta-percha and no</p><p>mention is made of the depth of root filling removal below the level</p><p>of soft tissue attachment.</p><p>Irrespective of the exact mechanism of action, confinement of</p><p>the bleaching agent to supragingival attachment levels would seem</p><p>prudent. Many authors in their conclusions advocate the sealing off</p><p>of the root filling at the level of attachment to prevent periodontal</p><p>irritation from the bleaching agent (3-8).</p><p>Holmstrup et ol(9) in a controlled study used Cavit as a barrier</p><p>over the existing root filling and bleached with sodium perborate</p><p>and water in a walking bleach technique. The technique produced</p><p>aesthetic results which were considered good or acceptable in 80%</p><p>of cases after three years. with no incidence of cervical root</p><p>resorption.</p><p>Rotstein et a1 (10) in an in vitro study found that sodium</p><p>perborate with water proved a successful bleaching agent in teeth</p><p>discoloured with human erythrocytes at the one-year mark.</p><p>In those cases where subgingival bleaching is essential for a</p><p>successful aesthetic outcome, then the follow-up use of calcium</p><p>hydroxide in the pulp chamber has been shown to arrest the</p><p>progression of cervical root resorption (6) and may be of benefit in</p><p>the prevention of cervical root resorption. As yet this is an empirical</p><p>hypothesis which needs further investigation.</p><p>Case Report</p><p>In January 1990 a female patient then aged 28 presented for</p><p>emergency dental care with "clicking" coming from her left maxillary</p><p>central incisor (tooth 2. I). Clinical examination revealed a tooth that</p><p>appeared periodontally sound and firm; however, radiographically</p><p>(Figs. I & 2) severe cervical root resorption was evident. After</p><p>discussions, the patient left without any firm commitment to follow-</p><p>up care. The thought of an immediate partial denture was not</p><p>appealing. Copies of the patient's previous dental record were</p><p>obtained and are listed chronologically for each tooth as follows:</p><p>I ) Tooth 2. I : Root filled on 2811 0/88 (Fig. 3). Internal bleaching on</p><p>28/10/88, 411 1/88 and 1711 1/88.</p><p>2) Tooth 2.2: lntemal bleaching on 1711 1/88. 9/12/88. 13/1/89</p><p>and 24/2/89.</p><p>3) Tooth I. I : Vnal bleaching on 2/3/89 and 23/3/89. Root canal</p><p>treatment commenced on 13/4/89 and finished on 19/4/89.</p><p>lntemal bleaching on 19/4/89. 24/4/89 and I 1/5/89.</p><p>The cause of loss of vitality in the 2. I and 2.2 is not indicated in</p><p>the record but from preoperative radiographs there were large</p><p>interproximal restorations present and a dens invoginatus which may</p><p>have contributed to pulp necrosis. There was no identifiable history</p><p>of trauma but this could not be ruled out positively. Unfortunately</p><p>there was no description of the type of bleach used, whether or not</p><p>heat was applied and/or acid etch modifcation of the dentine prior</p><p>to bleaching. No mention is made of isolating the root filling with a</p><p>AUSTRALIAN ENDODONTIC JOURNAL VOLUME 25 No. 3 DECEMBER 1999</p><p>Figure 3. An eorly rodiogroph (October 1988) of teeth I I , 2. I ond 2.2.</p><p>FiRure I : Rodiogroph token in jonuory 1990. Tooth 2. I cleorly has o</p><p>problem. Tooth I . I oppors norniol.</p><p>Figure 2: This viewof2. I shows the extent ofdestruction of the root</p><p>AUSTRAI.IAN FNOODONTI<: IOURNAL VOLUME 25 No 3 DECtHEER 1999</p><p>coronal seal or measurement of the colour improvement achieved</p><p>These omissions raise many questions about record keeping and</p><p>make it difficult to potentially isolate the cause of the cervical root</p><p>resorption in this case. It is also pertinent to note that no</p><p>documentation exists in the record regarding discussions with the</p><p>patient regarding the risks of internal bleaching.</p><p>Over the ensuing two years the patient re-presented for regular</p><p>routine care, resisting any treatment of the 2. I until January 1992.</p><p>At this time a follow-up radiograph was taken (Fig. 4) which is not</p><p>significantly different from the preceding film taken two years earlier.</p><p>A partial denture was made and inserted after the 2. I was extracted</p><p>with plans to proceed with a three-unit bridge after soft tissue</p><p>healing had taken place. On 28/5/92 preparation for a three-unit</p><p>post and core retained bridge was commenced and mid procedure</p><p>radiographs were taken to assess post preparation depth (Figs. 5 &</p><p>6). As can now be clearly seen the 1 . 1 has a severe resorptive</p><p>defect on the distal aspect which did not communicate via the</p><p>periodontal sulcus with the oral cavity nor with the post</p><p>preparation. The 2.2 did not appear to show any radiographic signs</p><p>of cervical</p><p>root resorption (Fig. 6). At this point a temporary bridge</p><p>was constructed whilst treatment options were considered.</p><p>On 8/7/92 the patient presented with a labial swelling associated</p><p>with the 1 . 1 which was managed by surgical drainage and</p><p>antibiotics. This complication forced the issue and the tooth was</p><p>extracted on 20/8/92. Examination of the extracted fragments</p><p>revealed a severely compromised root that would not have been a</p><p>suitable brldge abutment. An addition was made to the existing</p><p>partial denture and reinserted. A subsequent radiograph of the 2.2</p><p>was taken on the 27/10/92 (Fig. 7) which displayed a radiolucency</p><p>in the apical half of the tooth. Although tooth 2.2 was</p><p>asymptomatic. prosthetic unreliability led to its removal. Prosthetic</p><p>restoration of the edentulous space was achieved using dental</p><p>implants.</p><p>I J I</p><p>figure 4: 7cvo yea6 later ond tooth 2. I has not chonged significontly.</p><p>Note rhe cervical region on the distal of tooth I . I</p><p>figure 5: Rodiogroph token to check the post spoce preprotion. The</p><p>distal cervicol lesron of I . I is obvious</p><p>figure 6: Tooth 2.2 shows no cervicol obnorrnolity but note the mid-root</p><p>rodiolucenc y.</p><p>Discussion</p><p>Multiple teeth treated with an unknown bleaching agent and</p><p>unknown technique have undergone various degrees of cervical</p><p>root resorption. By the time of radiographic detection this process</p><p>had progressed beyond reliable restoration of each tooth. The time</p><p>from bleaching to onset of cervical resorption as seen</p><p>radiographically varied from I 4 months for the 2. I to 36 months for</p><p>the I. I. Forty four months elapsed before the radiolucency</p><p>appeared in the 2.2. The times between exposure to bleaching and</p><p>diagnosis of cervical resorption as reported in the literature have</p><p>varied from I to 7 years (I , 3). The reasons for this variation are</p><p>unknown, but may relate to the degree of sub-attachment dentine</p><p>exposed to the caustic agent, the type of bleaching agent used.</p><p>modification of the dentine with acid etching. whether heat</p><p>application was part of the bleaching process or just individual</p><p>biological variation and so on. Any or all of these factors or some</p><p>other unknown element may explain the significant differences</p><p>between the radiographic severity as seen in figures I. 2 and 5.</p><p>Another interesting aspect to this case is the development of the</p><p>"lesion" on the 2.2 in the apical half of the tooth. Reports in the</p><p>literature all seem to support the notion that lesions occur in the</p><p>coronal third of the tooth (I, 3-8). The differential diagnosis based</p><p>on the radiographic findings for tooth 2.2 (Fig. 7) would include</p><p>perforation, artefact and/or radiographic distortion. It is impossible</p><p>to exclude these given no histological review. However, the clinical</p><p>impression upon extraction was of a resorptie defect.</p><p>Gimlin (6) successfully used calcium hydroxide to arrest an</p><p>existing cervical resorptive defect, and perhaps with more</p><p>aggressive management of this case. tooth 1 . 1 may have been</p><p>spared the ravages of resorption.</p><p>I38 AUSTRALIAN ENDODONTIC JOURNAL VOLUME 2 s No 3 DECEMBER I999</p><p>Figure 7. Five months loter and the mid-root radiolucency of 2 2 is</p><p>obvious</p><p>Conclusion</p><p>A review of the literature reveals a plethora of case reports and</p><p>studies implicating internal bleaching as a causative factor in cervical</p><p>root resorption. The incidence has been reported at 6.9% (8) for</p><p>hydrogen peroxide bleaching and 0.0% for sodium perborate with</p><p>water and a Cavit seal over the root canal (9) Sodium perborate</p><p>with water has been shown to be 80% effective in internal</p><p>bleaching of dentine stained with human erythrocytes ( 10). The</p><p>method as described by Holmstrup et ol(9) would seem to be a far</p><p>superior technique to historical methods involving heat and</p><p>hydrogen peroxide without pulp canal sealing</p><p>Expression</p><p>A case has been presented that demonstrates the potential</p><p>biological costs of internal bleaching. The financial cost to this patient</p><p>has also been quite significant: endodontic treatment. bleaching.</p><p>dentures followed with implant based prosthodontics represents</p><p>quite a trip around all facets of dentistry This case also demonstrates</p><p>a poor account of record keeping. It cannot be stressed enough that</p><p>accurate patient records must be kept both from a litigious point of</p><p>view and a scientific research point of view.</p><p>References</p><p>I . HCJf~iflgtOfl 5. W . Notkin E . External resorption associated</p><p>with bleaching of pulpless teeth. J Endod 1979; 5: 344-8.</p><p>2. Tronsrod 1 Root resorption-etiology, terminology and clinical</p><p>manifestations. Endod Dent Traumatol 1988. 4. 24 1-52,</p><p>3. lado E A.. Stonley H.R.. Weismon M.1. Cervical resorption in</p><p>bleached teeth. Oral Surg Oral Med Oral Path 1983: 55. 78-</p><p>80.</p><p>4. Mont.qoniev S External cervical resorption after bleaching a</p><p>pulpless tooth. Oral Surg Oral Med Oral Path 1984: 57: 203-</p><p>6.</p><p>5. Goon WWY. Cohen S.. Borer R.E External cervical root</p><p>resorption following bleaching. J Endod 1986; I 2: 4 14-8.</p><p>6. Girnliri D.R , Schmdler WG. Case report. The management of</p><p>postbleaching cervical resorption. J Endod 1990; 16: 292-7.</p><p>7. Mudison 5.. Wolton R. Cervical root resorption following</p><p>bleaching of endodontically treated teeth. J Endod 1990; 16:</p><p>8. friedman S.. Rotstein 1.. libfeld H.. Stobholz A.. Heling 1.</p><p>Incidence of external root resorption and esthetic results in</p><p>58 bleached pulpless teeth. Endod Dent Traumatol 1988; 4:</p><p>9. Holmstrup G.. Polrn A.M.. lomberg-Honsen H. Bleaching of</p><p>discoloured root-filled teeth. Endod Dent Traumatol 1988; 4:</p><p>10. Rotstein 1.. Choim M.. Friedrnon S. Prognosis of intracoronal</p><p>bleaching with sodium perborate preparations in vitro: I -year</p><p>study. J Endod 1993; 19: 10- I 2.</p><p>570-4.</p><p>23-6.</p><p>197-20 I.</p><p>From The Journals</p><p>Of Adhesion Molecules In Normal And Inflamed Human Dental Pulp</p><p>h j i c Z.. Savage N.W. Bortold PM.. Wolsh 1.J IADR Abstracts. A N Z</p><p>Diviuon. Brrsbane I' 998; p37. obs 8</p><p>Adhesion molecules (AM) allows cells to interact with one</p><p>another or with components of the extracellular matnx In the</p><p>development of inflammation. their pattem of expression influences</p><p>the migration of immune cells from the blood into the tissues. The</p><p>purpose of this retrospectwe study was to map the cellular</p><p>distribution and expresslon of adhesion molecules in normal and</p><p>inflamed dental pulp using immunohmchemistv. NCAM was</p><p>expressed on neural elements. whilst VIA-6 was expressed on</p><p>both neural and vascular basement membranes. Of the endothelial-</p><p>leukocyte adhesion molecules, PECAM- I was constitutively</p><p>expressed by endothelial cells in both normal and inflamed dental</p><p>pulp. VCAM- I and E-selectin were confined to the endothelium in</p><p>inflamed sites, while their counter-receptors VIA-4 and L-selectin</p><p>were expressed on subpopulations of leukocytes, particularly</p><p>lymphocytes. ICAM- I was constitutively expressed at low levels in</p><p>normal tissues, and was increased in inflamed sites. Low levels of</p><p>these AM coincided with low levels of inflammation. These findings</p><p>indicate that dental pulp blood vascular endothelium is capable of</p><p>selective recruitment of cells from the peripheral blood.</p><p>Interference with these mechanisms may be a useful therapeutic</p><p>approach in the treatment of pulpitis.</p><p>AUSTMLIAN ENDODONTIC JC)URNAL VOLUME 25 No 3 DECEMBER I999 I39</p>