Journal of Perwdonlal Research 1984: 19: 666 669 Proceedings

New attachment formation on citric acidand non-citric acid treated roots

T. KARRING. F. IsinoR, S. NYMAN AND J. LINDHE

Department of Periodontology. Royal Dental College, Aarhus. Denmark and Department ofPeriodontology, Faculty of Odontology, University of Gothenburg. Gothenburg, Sweden

IntroductionA number of investigations have been pub-lished describing the regenerative potentialsof the periodontal tissues following varioustypes of surgical procedures (for review seeWirthlin 1981). The findings reported havebeen interpreted to demonstrate the possi-bility of establishing new connective tissueatlachment to root surfaces which duringthe progression of periodontitis have beenexposed to the oral environment and plaqueinfection in deepened pathological pockets.

Several authors have reported that theplacement of bone grafts in angular bonydefects in conjunction with flap surgerypotentiates the regeneration of bone and theformation of a new connective tissue attach-ment (for review see Ellegaard 1976). Otherinvestigators have claimed that new attach-ment may be obtained by combining theflap procedure with techniques designed toretard or prevent the apical migration of thedentogingival epithelium during healing(Bjorn 1961, Ellegaard, Karring & Loe1974). It has also been demonstrated thatthe mere prevention of plaque infectionduring healing following surgery invariablyresults in "bone fill"" within infrabony de-fects (Rosling, Nyman & Lindhe 1976), andfinally a number of studies have been pub-hshed in recent years suggesting that citricacid conditioning of exposed root surfaces

promotes the reestablishment of connectivetissue attachment following surgical treat-ment (for review see Nightingale & Sheridan1982).

Experiments in wbich the conditionsclaimed to promote new attachment wereestablished have been carried out in order tostudy various aspects of heahng (Karring,Nyman & Lindhe 1980, 1984a, Nyman etal.1980, Gottlow, Nyman & Karring 1984).An experimental animal model was used inwhich periodontitis involved roots werescaled and planed and subsequently ex-tracted and implanted into bone and gin-gival connective tissue in edentulous aveasof the jaws. The roots were covered by amucosal flap so that the epithelium wasprevented from migrating into the wound.The results of these experiments have shownthat (I), granulation tissue derived frombone and gingival connective tissue induceroot resorption rather than the formation ofa new connective tissue attachment whengrowing into contact with a root surfacedeprived of its periodontal hgament tissueand that (2), new attachment is established ifceils originating from the periodontal hga-ment repopulate the wound area adjacent tothe root surface. Treatment of the roots withcitric acid prior to implantation did notimprove new attachment formation (Gott-low et al. 1984), but healing consistentlyresulted in root resorption. Root resorption.

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however, was a common finding not only in iation tissue around the experimental rootsthe coronal scaled and planed part of the was excised and the cementum of theimplanted roots but to some extent also in periodontitis involved part were removedthe apical root portion where the periodon- using a diamond bur. At this time half thetal ligament tissue was preserved at the number of roots were subjected to topicalimplantation. This observation was inter- apphcation of eitric acid at pH 1 for ?,preted to mean that the periodontal liga- minutes. Subsequently, all roots were cover-ment was severed during the transplantation ed with a mucosal flap raised mesial to theprocedure since it proved incapable of pre- experimental teeth and distally displacedventing granulation tissue from bone and and sutured. The animals were sacrificedgingival connective tissue to grow into con- after 3 months of healing. The jaws weretact with the roots. Such a compromised removed and tissue blocks containing thecondition of the periodonta! ligament tissue roots and their surrounding tissues werecould explain why virtually no new attach- processed for embedding in paraffin. Serialment was formed in these experiments since sections 8 fim thick were eut in mesio-distalcells of a damaged periodontal ligament direction and stained with hematoxylin andmost likely have reduced capacity for coro- eosin or Luxol fast blue G connective tissuenal migration. stain. With this experimental design a total

The present investigation was designed to of 54 root surfaces were available for micro-examine if new attachment will form on scopic analysis. In 5 sections representingpreviously periodontitis involved roots the central portion of the root, the amountwhen a reduced but non-compromised of new connective tissue attachment formedperiodontal ligament tissue persists follow- on each experimental root surface wasing periodontal treatment (Karring et al. assessed.1984b) and if citric acid treatment of theroot surfaces may promote this result ofhealing (Isidor et al. 1984). Results

Six citric acid treated roots and 6 non-citricacid treated roots penetrated the covering

Material and Methods ^^C, (j^j.^^. ^^^^^ ^^jj^i^ u^^ f^^f ^^ej, „[In each of 4 monkeys, periodontal tissue healing. The microscopic analysis disclosedbreakdown was induced around maxillary that in all roots new cementum with insert-and mandibular incisors, second premolars, ing collagen fibers had formed in the apicaland first molars by placing orthodontic portion of the previously exposed rootelastics around the teeth. The elastics were surfaces.kept in situ until about 50% of the support- This newly formed cementum was alwaysing tissues had been lost. Prior to the start of in continuity with the original cementumperiodontal breakdown the crown of the layer apical to the instrumented part of theneighboring tooth mesial to each experi- root and was thickest in its apical portionmental tooth was resected and its roots were becoming gradually thinner in coronal di-covered by a laterally displaced mucoperios- rection. In the non-citric acid treated rootsteal flap. Three months following removal which for the entire length of the studyof the elastics the crown of each experi- remained covered by the oral mucosa, themental tooth as well as the crown of the extension in coronal direction of this newlyneighboring tooth distal to it were resected, formed fibrous attachment amounted to anThe pocket epithelium and subjacent granu- average of 1.0 mm± 0.7 mm (s.d.) and in the

66K K A R R I N G E T A L .

citric acid treated roots to an average of 1.1mm±0.7 mm (s.d.). The length of the newlyformed connective tissue attachment wassignificantly smaller in those roots whichhad penetrated the soft fiaps during healingthan in those which remained coveredthroughout the study. No statistically sig-nificant difference was found between citricacid and non-citric acid treated roots withrespect to the amount of newly formedconnective tissue attachment. In both citricacid treated and non-citric acid treated teethwhich remained covered throughout thestudy the parts of the roots coronal to thenewly formed cementum exhibited resorp-tion as the predominant feature. In the rootportions showing resorption. areas withcollagen fibers oriented perpendicular to theroot surface without evidence of cementumwere occasionally seen.

Discussion

The results of the present study demon-strated that new connective tissue attach-ment had formed in the apical parl of theinstrumented root portion while the rootarea coronal to this was characterized byresorption. This observation differs fromfindings in the new attachment studies onthe transplanted roots (Karring et al. 1980,1984. Nyman et al. 1980, Gottlow et al.1984) on which only minute amounts of newattachment had formed. The lack of newattachment formation in these studies wassuggested to be due to an impaired coronalmigration of periodontal ligament cellsbecause of the injury inflicted to these cellsduring the transplantation procedure.Hence, the lack of new attachment forma-tion in these studies and the accomphsh-ment of new attachment in the presentmaterial in which the remaining periodontalligament was not compromised indicate thatnew attachment is formed by cells derivedfrom the periodontal ligament tissue. Treat-

ment of the roots with citric acid failed topromote the formation of new connectivetissue attachment. It has been suggested thatcitric acid treatment results in the exposureof dentinal collagen fibrils which subse-quently are interdigitated with collagen fi-brils of the adjacent connective tissue duringhealing (Register & Burdick 1975). Thisdescription of a fibrous reattachment for-mation resembles the observations in thepresent study that within areas exhibitingactive root resorption collagen fibers ap-peared to be attached to the dentin surfacewithout cementum fortnation. Thus, thepossibility exists that such healing pheno-mena may have been interpreted as newattachment.

References

Bjorn. H. 196 L Experimental studies on reattach-ment. Dental Practitioner. Dental Reconstruc-tion II: 351-354.

Ellegaard. B.. Karring, T. & Loe. H. 1974. Newperiodontai attachment procedure based onretardation of epithelial migration. Journal ofClinical Periodontology 1: 75-88.

Kliegaard, B. 1976. Bone grafts in periodontalattachment procedures. Journal of ClinicalPeriodontologv 5: 5 54 (extra issue).

Gottlow, J., Nyman. S. & Karring. T. 1984.Healing following citric acid conditioning ofroots implanted into bone and gingival connec-tive tissue. Journal of Periodomal Research 9:214-220,

Isidor, F., Karring, T., Nyman, S. & Lindhe, J.1984. New attachment formation on citric acidtreated roots- Journal of Periodontal Research.In press.

Karring, T-, Nyman, S. & Lindhe, J. 1980, Heal-ing following implantation of periodontitis af-fected roots into bone tissue. Journal of ClinicalPeriodontology 1: 96-105.

Karring, T., Nyman, S., Lindhe, J, & Sirirat. M.1984a. Potentials for root resorption duringperiodontal healing. Journal of Clinical Perio-dontology 11: 41-52.

Karring, T., Isidor, F., Nyman, S. & Lindhe, J.1984b. New attachment fonnation on teethwith a reduced but healthy periodontal liga-ment. Journal of Clinical Periodontologv. Inpress.

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Nightingale. S. H. & Sheridan, P. J. 1982. Rootsurface demineralization in periodontal thera-py: Subject review. Journal of Periodontology53: 611-616.

Nyman, S., Karring, T., Lindhe, j . & Planten. S.1980. Healing following implantation ofperio-dontitis-affected roots into gingiva! connectivetissue. Journal of Clinical Periodontology 7:394-401.

Register, A. A. & Burdich, F. A. 1975. Ac-celerated reattachment with cementogenesis todentin demineralized in situ. L Optimum range.Journal of Periodontologv 46; 646-655.

Rosling, B., Nyman, S. & Lindhe. J. 1976. The

effect of systematic plaque control on boneregeneration in infrabony pockets. Journal ofClinical Periodontology 3: 38- 53.

Wirthiin. M. R. I98L The current status of newattachment therapy. Journal of Periodontology52: 523 544.

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Department of PeriodontologyRoyal Dental CollegeVennelyst BoulevardDK-SOOO Aarhus CDenmark