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The socket-shield technique: aproof-of-principle report

Hurzeler MB, Zuhr O, Schupbach P, Rebele SF, Emmanouilidis N, Fickl S. The socket-shield technique: a proof-of-principle report. J Clin Periodontol 2010; 37: 855–862.doi: 10.1111/j.1600-051X.2010.01595.x.

AbstractAim: Clinical studies have suggested that retaining roots of hopeless teeth may avoidtissue alterations after tooth extraction. Therefore, the objective of this proof-of-principle experiment was to histologically assess a partial root retention (socket-shieldtechnique) in combination with immediate implant placement.

Material and Methods: In one beagle dog, the third and fourth mandibular pre-molarwere hemisected and the buccal fragment of the distal root was retained approximately1 mm coronal to the buccal bone plate. Following application of enamel matrixderivate, a titanium implant was placed lingual to that tooth fragment either with orwithout contact to the buccal tooth fragment and a healing abutment was connected.Four months after implant placement, histological evaluation, and backscatterscanning electron microscopy were performed.

Results: All four implants were osseointegrated without any histologic inflammatoryreaction and the tooth fragment was devoid of any resorptional processes. On thebuccal side, the tooth fragment was attached to the buccal bone plate by a physiologicperiodontal ligament. On the lingual side of the fragment, newly formed cementumcould be detected. In the areas where the implant was placed into the fragment, newlyformed cementum was demonstrated directly on the implant surface.

Conclusions: Retaining the buccal aspect of the root during implant placement doesnot appear to interfere with osseointegration and may be beneficial in preserving thebuccal bone plate.

Key words: extraction socket; immediateimplant placement; tooth-retention

Accepted for publication 1 May 2010

Numerous publications have verifiedthat tooth extraction is followed bydimensional changes of the alveolarridge contour (Amler et al. 1960, Pie-trokovski & Massler 1967, Schroppet al. 2003, Araujo & Lindhe 2005,Fickl et al. 2008b). The resorption ofthe alveolar ridge is more pronouncedon the buccal than on the lingual aspectof the extraction socket (Pietrokovski &Massler 1967, Araujo & Lindhe 2005).In particular in the aesthetic zone, thesuccessive soft and hard tissue deficien-

cies can interfere with optimal implantpositioning and hamper the overall aes-thetic outcome of implant-supportedprostheses.

In order to overcome the negativeconsequences of tooth extraction, var-ious treatment approaches such asimmediate implants (Botticelli et al.2004, Araujo et al. 2005), graft materi-als (Carmagnola et al. 2003, Nevins etal. 2006, Araujo et al. 2008, Fickl et al.2008a, Araujo et al. 2009) and/or barriermembranes (Lekovic et al. 1997, Leko-vic et al. 1998) have been advocated anddescribed in the literature. As a conclu-sion, the majority of the studies showthat socket preservation is a suitabletechnique for socket augmentation withthe ability to maintain the ridge dimen-sion to a certain amount (Araujo et al.2008, Fickl et al. 2008a, Araujo et al.

2009). However, a complete preserva-tion and/or entire regeneration of theextraction socket have not been docu-mented yet.

The marked alterations after toothextraction appear to be attributable tothe loss of periodontal ligament and theconsecutive trauma in particular at thebuccal bone plate (Araujo & Lindhe2005). Thus, it can be assumed thatroot retention may have an influenceon the occurring resorption process.

Clinical studies have tested thehypothesis that root retention, either ofvital or pulpless teeth, may be able toavoid tissue alterations after toothextraction. Filippi et al. (2001) showedin a case report that decoronation of anankylosed tooth preserved the alveolarbone before implant placement. Fewstudies have demonstrated that the pre-

Markus B. Hurzeler1,2, Otto Zuhr1,Peter Schupbach3, Stephan F.Rebele1, Notis Emmanouilidis4 andStefan Fickl4,5

1Private Office Huerzeler/Zuhr, Munich,

Germany; 2Department of Operative

Dentistry and Periodontology, Albert Ludwigs

University, Freiburg, Germany; 3Schupbach

Histology Ltd., Horgen, Switzerland;4Department of Periodontology and Implant

Dentistry, New York University, NY, USA;5Department of Periodontology, Julius-

Maximilians-University, Wuerzburg,

Germany

Conflict of interest and source offunding statement

The authors declare that they have noconflict of interest.This study was funded by an unconditionalresearch grant from Thommen Medical,Waldenburg, Switzerland

J Clin Periodontol 2010; 37: 855–862 doi: 10.1111/j.1600-051X.2010.01595.x

855r 2010 John Wiley & Sons A/S

servation of decoronated roots in thealveolar process not only helps main-taining existing bone volume but alsoenables vertical bone growth, which canbe observed coronally to the decoronatedroot (Malmgren et al. 1984, Malmgren etal. 1994, Andersson et al. 2003). Bjorn(1963) confirmed regeneration of alveo-lar bone around endodontically treatedteeth that were submerged and coveredby a surgical flap. Reames et al. (1975)demonstrated in an animal study thateven though epithelium commonlyoccurred over the amputation sites ofsubmerged teeth, bone formation coro-nal to the submerged roots was evident.O’Neal et al. (1978) showed histologicaland radiographic evidence that newcementum and connective tissue willform over the coronal surface of submer-ged roots separating the dentin from thenew bone. Conclusively, histologicaland radiographic evidences suggest fewinflammatory changes and bone apposi-tion around roots that had been sub-merged for alveolar bone preservation.Bowers et al. (1989) submerged vitalteeth with infrabony defects in ninepatients and created notches at regionson the root that had been covered withdental calculus. After 6 months, no rootresorption, ankylosis, or pulp death wasobserved.

Salama et al. (2007) reported that theRoot Submergence Technique (RST)maintains the natural attachment appa-ratus of the tooth in the pontic site,which in turn allows for complete pre-servation of the alveolar bone frame andassists in the creation of an aestheticresult in adjacent multiple-tooth-repla-cement cases.

Davarpanah & Szmukler-Moncler(2009) reported implant placement incontact with ankylosed root fragmentsin a five-case-report study without anyspecific pathological sign after a periodof 12–42 months of loading.

No study yet has evaluated partialroot retention around dental implants.Thus, the goal of this proof-of-principleexperiment in conjunction with a casereport was to histologically assess andclinically demonstrate the effect of buc-cal root retention (socket-shield techni-que) in combination with immediateimplant placement.

Material and Methods

The research protocol was approved bythe ethical committee of Biomatech – aNAMSA company. One beagle dog (1

year old and weighting 17.5 kg) wasused for this experiment. Supragingivalscaling was performed 5 days beforetooth extraction and implant placement.Anaesthesia was induced by injectingatropine (Atropines, Aguettant, Lyon,France; 0.05 mg/kg intramuscular) andtiletamine-zolazepam (Zoletils100, Vor-bac, Carros, France; 5–10 mg/kg intra-muscular). Subsequently, an injection ofthiopental sodium was given (Nesdo-nalND, Merial, Lyon, France; 10–15 mg/kg intravenous) and the animalwas placed on an O2–N2O isoflurane(1–4%) mixture. In both quadrants ofthe mandible, the third and fourth pre-molars (3P3 and 4P4) were used as experi-mental sites.

The third and fourth mandibular pre-molars were hemisected using a fissurebur. Consecutively, a coarse-graineddiamond bur was used to decoronatethe distal aspect of the pre-molar.After performing the osteotomy drillsfor the dental implant on the lingual partof the root, residual tooth fragmentswere completely removed on the lin-gual, distal, and mesial region of theextraction socket (Fig. 1). Consecu-tively, enamel matrix derivate(Emdogains, Straumann, Basel, Swit-zerland) was administered on the inter-nal aspect of the fragment. The buccalfragment of the root was retainedapproximately 1 mm coronal to the buc-cal bone plate.

The implant (SPIsELEMENT 4 �11 mm, Thommen Medical, Walden-burg, Switzerland) was placed accord-ing to the manufacturer’s recommenda-tion and was situated at the height of thebuccal root segment (Fig. 2). Randomly,two out of four implants were placedintentionally in direct contact with thebuccal root fragment. Healing abut-ments of 4 mm in height were connected(Fig. 3).

After surgery, the following regimenwas administered:

� Antimicrobial prophylaxis: spiramy-cine 750,000 IU and metronidazole125mg/os/day for 7 days (Stomorgyls,Merial).

� Anti-inflammatory drug: carprofene50 mg/os/day for 6 days (Rimadyls,Pfizer Sante Animale, Orsay, France).

� The animal received an injection ofbutorphanol (0.3mg/kg) (TorbuGesics,Fort Dodge Animal Health, South-ampton, UK) post-surgically and onthe following day. Tooth cleaningwith toothbrush and dentifrice andadministration of 0.2% chlorhexi-dine was performed three times perweek for 4 weeks.

The animal was terminated 4 monthsafter implant placement. After anaesthe-sia with an intramuscular injection ofZoletils (50 mg/kg), heparin was admi-nistered by intravenous injection (100 IU/kg). The animal was euthanized by alethal dose injection of Dolethals (Pen-tobarbital sodique, Vetoquinol, Paris,France) before formalin injection. Tissuefixation was achieved by injectingapproximately 300 ml of 10% formalinin the common carotid artery. Following

Fig. 1. Following hemisection, the buccalaspect of the root was retained approxi-mately 1 mm apically to the coronal margin.

Fig. 2. The implant is placed lingually toretained root fragment. In two out of fourimplants the fixture is intentionally placed indirect contact with the root.

Fig. 3. Following implant placement, heal-ing abutments were connected.

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this initial fixation, the mandible wasdissected behind the first molar andresected. Each ramus was separated bya frontal section and fixed in 10% buf-fered formalin solution.

Histological evaluation

The specimens were cut longitudinallyin the bucco-lingual direction throughthe centre axis of the implants using anExakt cutting unit (Exakt, Norderstedt,Germany) equipped with a diamond-coated bandsaw. The two resultinghalves of the original specimen wereembedded following complete dehydra-tion in ascending grades of ethanol ina light-curing one-component resin(Technovit 7200 VLC, Kulzers, Frie-drichsdorf, Germany). One half wasanalysed using a backscatter detectorof a scanning electron microscope (B-SEM). The other half was processed forground sections and evaluated with lightmicroscopy (LM).

B-SEM

For the B-SEM evaluation, the speci-men was glued on an aluminium holder.The surface to be examined was highlypolished with diamond pastes and thor-oughly cleaned in an ultrasonic cleaner.Thereafter, the polished surface wassputtered with a 6-nm-thick carbonlayer using an SCD-500 sputter coater(Bal-Tec, Balzers, Liechtenstein). Thespecimen was examined with a ZeissVPN-40 (Antwerp, Belgium) field cath-ode SEM using the backscatter detector.

LM

For LM evaluation, the sampleswere processed for the preparationof non-demineralized ground sectionsaccording to the technique of Donath& Breuner (1982). Polymerized blockswere sliced longitudinally on an Exaktcutting unit (Exakt). The slices werereduced by microgrinding and polishingusing an Exakt grinding unit to an eventhickness of 30–40 mm. Sections werestained with toluidine blue/pyronine Gand examined using both a Leica MZ16stereomicroscope (Leica Microsystems,Leica, Wetzlar, Germany) and a Leica6000DRB light microscope (LeicaMicrosystems).

Results

Implants placed lingual to a toothfragment

The bucco-lingual overview illustratedthe presence of a tooth fragment locatedbuccally from the implant (Fig. 4). Thetooth fragment consisted of a small por-tion of enamel and an up to 0.5 mm-wide piece of root dentin. On its buccalside, the tooth fragment was still attac-hed to the buccal bone plate by a physio-logic periodontal ligament. Towards theimplant, a small, up to 0.5 mm-widegap, filled with connective tissue wasinterposed between the tooth fragmentand the implant. The implant wasosseointegrated into the alveolar boneon the lingual side. The height of thealveolar bone crest was identical on thebuccal and on lingual side. The peri-implant soft tissue revealed a physiolo-gic junctional epithelium and was freeof any inflammatory reaction.

A higher magnification of the coronalpart of the tooth fragment revealedbuccally a physiologic junctional epi-thelium terminating at the cemento-enamel junction (supporting informationFig. S1). The uppermost end of the toothfragment was in contact with the junc-tional epithelium tapering down alongthe implant. Initiating from this contactpoint, a thin layer of junctional epithe-lium was present on the internal surfacesof the tooth fragment and tapered down

in the apical direction (Fig. S2). Api-cally to the latter, the dentin surface wascovered by a thin layer of newly formedcementum (Fig. S2) The thickness of thecementum layer increased continuouslyin the apical direction (Fig. 5). The most

Fig. 4. Bucco-lingual ground section of aspecimen showing an up to 0.5 mm widegap between implant and the root fragment(arrows). Note the height of both, buccalbone plate (BB) and the lingual bone (LB).Also note the healthy peri-implant softtissues. Toluidine blue/Pyronine G stain.

Fig. 5. Detailed view of Fig. 4 showing newcementum (NC) covering the treated dentin(D) surface. Note that the thickness of thenew cementum layer gradually increase inthe apical direction indicating its formationin the same direction. Also note the absenceof any osteoclastic remodelling at the crestof the buccal alveolar crest (BB). Toluidineblue/Pyronine G stain. Scale bar 5 200 m.

Fig. 6. High magnification of the internalpart of the root fragment with new cemen-tum (NC) formation on the treated dentinsurface (D). Note the presence of an cemen-toid (O) and cementoblasts (arrows).Toluidineblue/Pyronine G stain. Scale bar5 20mm.

The socket shield technique 857


coronal part of the new cementum wasan acellular type of cementum, whichwas apically continuous with cellularcementum (Fig. 5). At a higher magni-fication, the acellular cementum showedongoing formation of cementum by thepresence of a cementoid and cemento-blasts (Fig. 6) and was characterized bythe insertion of collagen fibre bundlesanchored in cementum (Fig. S3). Cellu-lar cementum was deposited in multiplelayers (Fig. 7). The connective tissue

interposed between the newly formedcementum and the implant surface washealthy and was adherent to the implantsurface (Fig. 7). Occasionally, new for-mation of woven bone was observed onthe latter (Fig. 7). Backscatter SEM

micrographs of the newly formedcementum demonstrated its firm attach-ment towards the dentin (Fig. 8).The apical end of the tooth fragmentshowed no resorption processes. Thesurface also was partially covered by athin layer of newly formed cementum(Fig. S4).

The buccal side of the tooth fragmentshowed the intact periodontal ligament

Fig. 7. Detailed view of Figure 1 demon-strating layers of new cementum (NC) aswell as mineralized tissue (MT) on theimplant surface. Toluidine blue/Pyronine Gstain.

Fig. 8. B-SEM micrograph illustrating newlyformed cementum (NC) on dentin (D) andthe presence of cementocyte lacunae (whitearrows).

Fig. 9. Bucco-lingual ground section of aspecimen placed without a gap betweenimplant and the root fragment (arrows).Note the height of both, the intact buccalbone plate (BB) and the lingual bone (LB).Also note the healthy peri-implant soft tis-sues. Toluidine blue/Pyrodine G stain.

Fig. 10. Detailed view of Figure 9 showingthe tooth fragment in contact with the tips ofthe implant threads. Note that treated dentin(D) is covered by newly formed cementum(arrows) and that the space between thethreads is partially filled with an amorphousmineralized tissue. BB = buccal bone. Tolui-dine blue/Pyronine G stain. Scale bar 5200mm.

Fig. 11. Higher magnification of the tipof a thread integrated into newly formedcementum (NC) and amorphous mineralizedtissue (MT). Toluidine blue/Pyronine Gstain. Scale bar 5 100 mm.

Fig. 12. B-SEM micrograph demonstratingthe integration of the implant surface (IMP)into newly formed cementum (NC). Note thecontinuity between dentin (D) and cemen-tum and the intimate contact betweencementum and implant.

858 Hurzeler et al.


(Fig. S2). The alveolar bone crestwas free of any resorption processes.In contrary, new formation of wovenbone was observed (Fig. S2).

Implants placed in contact to a tooth

fragment

The bucco-lingual overview illustratesthe presence of a tooth fragment apicallyin contact with threads of the implant(Fig. 9). The coronal part of the toothfragment was separated by connectivetissue interposed between tooth frag-ment and implant (Fig. 9). Along thisportion of the tooth fragment, a junc-tional epithelium and the formation ofnew cementum was observed asdescribed above. Again, the borderbetween the apical end of junctionalepithelium and the newly formed acel-lular cementum was clearly visible (Fig.S5). The more apical portion of thetooth fragment was in direct contactwith the tips of the implant threads andcovered by a cellular type of cementum(Figs 10, 11; Fig S6). The areas betweenthe threads were partially filled with anamorphous mineralized tissue and con-nective tissue (Figs 10, S6). Highermagnifications of the tips of the implantthreads demonstrated their integration inthe newly formed cementum interposedbetween dentin and the implant (Fig.11). In some areas, formation of newcementum via cementoblasts and a

cementoid occurred directly on andalong the implant surface (Fig. 11).Backscatter SEM micrographs demon-strated newly formed cementum brid-ging the space between the dentin andthe implant surface (Fig. S7). Highermagnifications showed the intimate con-tact, without any fibrous tissues inter-posed, between the new cementum andthe implant surface (Fig. 12).

The buccal side of the tooth fragmentrevealed a normal and intact periodontalligament (Fig. S6). No signs of boneresorption were observed at the alveolarbone crest (Fig. S8).

Case Report

A 45-year-old patient presented witha non-contributory medical history,requesting replacement of tooth #21due to a vertical root fracture (Fig. 13).The patient gave his informed consent tothe root-retention technique in conjunc-tion with immediate implant placement.Tooth #21 was decoronated with acoarse-grained diamond approximately1 mm apical to the gingival margin (Fig.S9). Consecutively, the osteotomy drillswere performed through the lingualaspect of the root. Then, all root frag-ments were removed on the lingual,mesial and distal aspect, retaining onlythe buccal portion of the root (Fig. 14).Following application of enamel matrix

derivate (Emdogains, Straumann), theimplant (SPIsELEMENT, ThommenMedical 4 � 13 mm) was inserted andpositioned slightly apical to the preservedroot fragment (Fig. 15). A screw-retainedprovisional was fabricated and hand tigh-tened onto the implant (Fig. S10). Carewas taken to remove all centric andeccentric functional contacts from theprovisional crown. A soft diet was recom-mended for the duration of the implant-healing phase. The patient was advisedagainst functioning or activities to theimplant site.

The gingival architecture around theimplant was well preserved after 6months (Fig. 16). The final impressionswere made and the definitive restorationconsisted of a full-ceramic abutment anda full-ceramic crown (Figs 17, 18).

Discussion

This proof-of-principle experimentconfirms that buccal root retention inconjunction with immediate implantplacement is able to achieve osseointe-gration without any inflammatory orresorptional response. Within the limitsof that preliminary trial, the histologicalanalysis suggests that the buccal boneplate was preserved. Therefore, it maybe speculated that this technique mayhave the potential to avoid the markedresorption of the buccal bone plate aftertooth extraction.

Fig. 13. The patient presented with a verticalroot fracture in the left central incisor.

Fig. 14. Occlusal view of the retained rootfragment on the buccal aspect.

Fig. 15. Occlusal view showing the rootfragment in direct contact with the implant.

Fig. 16. Five months after implant place-ment tissue loss on the buccal aspect couldbe avoided.

Fig. 17. Final restoration with all-ceramicabutment.

Fig. 18. Harmonic gingival conditions withthe final prosthetic reconstruction.



Tooth extraction and its trauma to thehard tissues are followed by pronouncedresorptions in particular of the buccalbone plate (Schropp et al. 2003, Araujo& Lindhe 2005). This is also true fortooth extraction in combination withimmediate implant placement. Scientificevidence has shown that immediateimplant placement is able to predictablyachieve osseointegration (den Hartog etal. 2008), but does not appear to have aninfluence on the biological response ofthe extraction socket (Botticelli et al.2004, Araujo et al. 2005, Vignoletti etal. 2009a, b).

Preserving the periodontal ligamentand the supra-crestal attachment of thetooth on the buccal aspect in conjunc-tion with immediate implant placementappears to have the potential to avoidbuccal bone remodelling. The techniqueof retaining roots to avoid alveolar boneremodelling was adopted from dentaltraumatology, where Malmgren et al.(1984) suggested the decoronation tech-nique of ankylosed teeth. Decoronationmay be considered a type of guidedbone regeneration due to the fact thatthe remaining residual root will undergoa resorptive process by osteoclasts fromthe adjacent bone marrow and graduallybe replaced by bone. Multiple experi-mental and clinical studies have shown,that the decoronation of ankylosed teethpredictably preserves the alveolar ridgecontour (Malmgren 2000, Filippi et al.2001, Malmgren & Malmgren 2002,Cohenca & Stabholz 2007, Sapir &Shapira 2008). However, the results ofthe present study illustrate that a non-ankylosed tooth fragment does notappear to undergo resorptional pro-cesses. Furthermore, the retained rootportion appears to preserve its charac-teristics with particular respect to itsperiodontal ligament and the supra-peri-osteal attachment. This can be seen inaccordance with studies assessing theuse of submerged roots to improve theretention of overdentures. O’Neal et al.(1978) reported on a study of 16 sub-merged endodontically treated mandib-ular pre-molar roots in four dogs.Results after 1–4 months depicted cor-onal overgrowth of bone, no periapicaland limited pericoronal inflammation(O’Neal et al. 1978). Reviews concludethat submerging teeth appear to be aviable and safe technique to preservealveolar bone (Casey & Lauciello 1980,Dugan et al. 1981).

However, in this study – contrary tothe above-cited studies – only the buccal

part of the root and its supra-periostealattachment were preserved and further-more no primary closure was obtained.The major findings of the histologicalanalysis were that the internal aspect ofthe root was covered with new cemen-tum and new periodontal attachment. Inaddition, in areas where the implant hasbeen placed into the root fragment,cementum could be detected on theimplant surface. This can be seen inaccordance with the study conductedby Buser et al. (1990) concluding thatin areas where the implant has beenplaced in close relationship to the rootfragment, the examination of the unde-calcified sections revealed a cementumlayer on the implant surface with insert-ing collagen fibres. The fact that a newperiodontal attachment could bedetected on the inside of the root frag-ment may be explanative by the use ofenamel matrix derivate, which plays amajor role in the development of perio-dontal tissues and show effectiveness inthe regeneration of the periodontium(Hammarstrom 1997, Heijl et al. 1997,Sculean et al. 2000). Enamel matrixderivative have also been documentedto prevent epithelial proliferation andto have an antimirobial capacity (Bos-shardt 2008). In order, to prevent epithe-lial down-growth along the retained rootand to preserve the characteristics of theroot fragment, enamel matrix derivativewas used as an adjunct to immediateimplant placement.

On the other hand, Nyman et al.(1982) has shown that exclusion ofepithelial cells leads to periodontalregeneration due to cells from the perio-dontal ligament. Within the limits of thisexperiment, it may be speculated thatthe blood clot between implant and rootmay have prevented the epithelium fromcolonizing the root surface. Amler et al.(1960) and Cardaropoli et al. (2003)have histologically demonstrated that ittakes approximately 4 weeks after toothextraction to cover the extraction socketwith epithelium. It may be assumed thatthe same process occurs between theimplant and the retained tooth fragment.As the blood clot prevents the epithe-lium from growing along the internalroot surface, it appears that cellsfrom the remaining periodontal liga-ment are capable of colonizing the rootsurface and regenerate new periodontalattachment.

It may be concluded that retaining thebuccal aspect of the root in conjunctionwith immediate implant placement is a

viable technique to achieve osseointe-gration without any inflammatory orresorptive response. Yet, as this is aproof-of-principle experiment, furtherhistological evidence and long-term fol-low up has to be conducted to recom-mend the socket-shield technique on ageneral basis.

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Supporting Information

Additional supporting information maybe found in the online version of thisarticle:

Figure S1. Detailed view showing thecoronal part of the tooth fragment. Notethe apical end of the natural junctionalepithelium (aJEP). Junctional epithelialcells also cover the root fragment (smallarrows) in the apical direction. E 5enamel; D 5 dentin. Toluidine blue/Pyr-onone G stain. Scale bar 5 100mm.Figure S2. Detailed view of the toothfragment showing on the left side theperiodontal attachment and cementum(C) and on the right side the borderbetween downgrowing junctionalepithelium (arrows) and new cementum(NC) covering the dentin surface (D).Toluidine blue/Pyronine G stain. Scalebar 5 100mm.Figure S3. High magnification of theinternal part of the root fragment

demonstrating new attachment by fiberbundles (arrows) inserting into newlyformed cementum (NC). Toluidineblue/Pyronine G stain. Scale bar 5100mm.Figure S4. Detailed view demonstratingthe apical end of the tooth fragment.Note the periodontal ligament (PL) onthe untreated left side and the thick layerof new cementum (NC) on the treateddentin (D) side. Also note the absence ofroot resorption and new formation ofcementum on the apical wall (arrows).Figure S5. Detailed view of Figure 13showing the border between the down-growing junctional epithelium (arrows)and the most coronal layer of newlyformed cementum (NC). D 5 dentin.Toluidine blue/Pyronine G stain. Scalebar 5 100mm.Figure S6. Ground section demonstrat-ing new cementum (arrows) on thetreated dentin (D) surface and minera-lized tissue (MT) partially filling thespace between the threads. Toluidineblue/Pyronine G stain. Scale bar5 100mm.Figure S7. B-SEM micrograph illustrat-ing newly formed cementum (NC) brid-ging the space between implant surface(Imp) and dentin (D).Figure S8. Detailed view of Figure 10showing the alveolar crest of thebuccal bone (BB). Note the absence ofany resorption processes. Toluidineblue/Pyronine G stain. Scale bar 5100mm.Figure S9. The tooth was decoronatedand separated and the buccal aspect ofthe root retained. A diamond bur wasused to reduce the root fragmentapproximately 1 mm apical to the gin-gival margin.Figure S10. Occlusal view with a pro-visional hand tightened on the implant.

Please note: Wiley-Blackwell is notresponsible for the content or functional-ity of any supporting materials suppliedby the authors. Any queries (otherthan missing material) should be direc-ted to the corresponding author for thearticle.

Address:

Markus Hurzeler

Private Office Hurzeler/Zuhr

Rosenkavalierplatz 18

81925 Munich

Germany

E-mail: [email protected]



mailto:[email protected]

Clinical Relevance

Scientific rationale for this study: Thegoal of this proof-of-principle experi-ment was to histologically assess thebiological response following partialtooth retention in combination withimmediate implant placement.

Principal findings: The retained rootwas devoid of any inflammatory orresorptive reactions. A newly formedroot cementum could be detected onthe internal part of the root fragmentand on top of the implant surface,when placed in direct contact to it.

Practical implications: Retainingparts of the root is a viable techniqueto achieve osseointegration. It mayalso have the potential to preservethe buccal bone plate.

862 Hurzeler et al.


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