Regeneration of the Alveolar Crest Using Titanium Micromesh with Autologous Bone and a Resorbable Membrane

ORAL IMPLANTOLOGYThursday Feb 27 2003 03:12 PMAllen Press x DTPro SystemREGENERATION OF THE ALVEOLAR CRESTUSING TITANIUM MICROMESH WITHAUTOLOGOUS BONE AND A RESORBABLEMEMBRANECLINICALMarco Degidi, MD, DDSAntonio Scarano, DDSAdriano Piattelli, MD, DDSKEY WORDSAlveolar crestGuided bone regenerationMarco Degidi, MD, DDS, is in privatepractice in Bologna, Italy, and is a visitingprofessor at the Dental School, University ofChieti, Chieti, Italy.Antonio Scarano, DDS, is a research fellowat the Dental School, University of Chieti,Chieti, Italy.Adriano Piattelli, MD, DDS, is a professorin the Department of Oral Medicine andPathology, Dental School, University of Chieti,Chieti, Italy. Address correspondence to ProfAdriano Piattelli, Via F. Sciucchi 63, 66100Chieti, Italy.86 Vol. XXIX/No. Two/2003INTRODUCTIONGuided bone regeneration (GBR) has been used for the regeneration of bone inconjunction with the placement of oral implants. The aim of the present studywas to clinically and histologically evaluate the use of a titanium micromesh anda resorbable membrane in the GBR technique in patients with alveolar crestdefects due to periodontitis, trauma, and extractions. Eighteen patientsparticipated in this study, and 50 implants were inserted. The postoperativehealing was uneventful, no dehiscences were observed, and all implants werefunctioning successfully at 7-year follow-up. At reentry, in all cases, the spaceunder the titanium mesh was completely filled by bone. From a clinical point ofview, in all patients, no residual bone defects were observed and a significantincrease of the alveolar width or height was found. In all cases, a good estheticresult of the restorative procedures was present.orim 29_206 Mp_86File # 06emmembrane can be used either in a2-stage technique, where bone isformed before the implantation or directlyat the time of implant insertion.11One of the most important aspects inobtaining results with membranes forlateral ridge augmentation is the creationand maintenance of a secludedspace under the membrane.9 The developmentof this space is the primedeterminant of the amount of newlyformed bone.2 The sites for localizedridge augmentation are non-spacemakingdefects because they are notsupported by the bone walls.9 In theseided bone regeneration(GBR) has been used inrecent years for the regenerationof bone in conjunctionwith the placementof oral implants,augmentation of resorbed alveolarridges, and treatment of localizedridge deformities.1-9 An adequate bonevolume for complete circumferentialcoverage of the implants is importantfor obtaining long-term success of oralimplants.10 The minimum amount ofbone seems to be 4 mm horizontallyand 7 mm vertically.10 The barrierORAL IMPLANTOLOGYThursday Feb 27 2003 03:12 PMAllen Press x DTPro Systemsituations, an excessive soft tissue pressurecould cause a membrane collapsetoward the defect.2 Possible solutionsto avoid the membrane collapse and toincrease the regenerative capabilities ofthe bone in non-space-making situationshave been the use of reinforcede-PTFE membranes2,10 or miniscrewsand pins to support the membrane.9Recently, the use of self-reinforced polyglycolidemembranes has been advocated.12 However, even with miniscrews,it is possible to have a lateralcollapse of the membrane.9 The use ofdifferent types of grafts has been proposedto maintain the space betweenimplant and surrounding defect.13Semirigid membranes are especiallyuseful to treat the vertical componentof the ridge deformity.8 Recently, theFIGURES 1-4. FIGURE 1. A lower incisor has been lost due to advanced periodontal disease. FIGURE 2. A Twin Plus (3.3 mm diameter and15 mm length) IMZ implant has been inserted approximately 5 mm above the lowest border of the defect. FIGURE 3. The defect has beenfilled with autologous bone retrieved from the chin area. A titanium mesh and a resorbable membrane are used to cover the autologousbone. The mesh is fixed with microscrews. FIGURE 4. Reentry procedure after 4 months.orim 29_206 Mp_87File # 06emMarco Degidi et alders of the defects (Figure 2), and thedefects were filled with autologousbone obtained from intraoral sites(usually the chin area). The defectswere then covered with a titanium micromesh(Cortical Mesh, Micronova,Bologna, Italy) (Figure 3) above whichwas positioned a resorbable membrane(Biogide, Geistlich, Wohlhusen, Switzerland)or a polyurethane membrane.The micromesh was fixed with 3-mmtitanium microscrews. After a healingperiod of 4 months in the mandibleand 6 months in the maxilla, the meshwith the surrounding and underlyingtissues was removed.Specimen processingAll specimens and surrounding tissueswere washed in saline solution and im-Journal of Oral Implantology 87use of barriers made of titanium micromeshhas been advocated.14-17 Theaim of the present study was to clinicallyand histologically evaluate the resultsobtained using GBR with a titaniummicromesh and a resorbablemembrane.MATERIALS AND METHODSEighteen patients (14 women and 4men), with a mean age of 47.5 years(range, 20-63 years), participated inthis study. All patients gave their informedconsent. In all patients, alveolarcrest defects due to advanced periodontitis,trauma, or extractions werepresent (Figure 1). Fifty Frialit 2 orIMZ Twin Plus implants (Friadent,Mannheim, Germany) were inserted,usually 4 to 5 mm above the lower bor-RESULTSORAL IMPLANTOLOGYThursday Feb 27 2003 03:12 PMAllen Press x DTPro SystemREGENERATION OF THE ALVEOLAR CRESTmediately fixed in 4% paraformalde- with a specially designed grinding mahydeand 0.1% glutaraldehyde in 0.15 chine. The slides were stained withM cacodylate buffer at 48C and pH 7.4 acid fuchsin and toluidine blue. Theto be processed for histologic analysis. slides were observed in normal trans-The specimens were processed to ob- mitted light under a Leitz Laborluxmitainthin ground sections with the Pre- croscope (Leitz, Wetzlar, Germany).cise 1 Automated System (Assing,Rome, Italy). The specimens were dehydratedin an ascending series of al- The postoperative healing was uncoholrinses and embedded in a gly- eventful in all patients, and no incisioncolmethacrylate resin (Technovit 7200 dehiscences were observed. All im-VLC, Kulzer, Wehrheim, Germany). plants were functioning successfully atAfter polymerization, the specimens 7-year follow-up. At the reentry proweresectioned along their longitudinal cedure, the titanium micromesh apaxiswith a high-precision diamond peared to be surrounded by a densedisk at approximately 150 mm and connective tissue with no clinical signsground down to approximately 30 mm88 Vol. XXIX/No. Two/2003FIGURES 5-13. FIGURE 5. Underneath the mesh, it is possible to observe the presence of a tissue with the macroscopic features of maturebone; this tissue cannot be entered with a dental probe. FIGURE 6. Lingual view after removal of the mesh. It is possible to observe theamount of the vertical regeneration (about 3 mm of newly regenerated bone is present on top of the implant). FIGURE 7. A single crownhas been placed on the implant and the restoration is completed. FIGURE 8. Macroscopic view of the mesh: the mesh is surrounded bydense connective tissue. FIGURE 9. At low magnification, dense connective tissue is present around the mesh (acid fuchsin-toluidine blue,original magnification 350). FIGURE 10. At higher magnification, no inflammatory cells are visible (acid fuchsin-toluidine blue, originalmagnification 3100). FIGURE 11. Under polarized light, the connective fibers run in a parallel way around the titanium (acid fuchsintoluidineblue, original magnification 350). FIGURE 12. In some areas, it is possible to observe the remnants of the resorbable polyurethanemembrane and newly formed bone in tight contact with the membrane (acid fuchsin-toluidine blue, original magnification 350). FIGURE13. At higher magnification, newly formed bone with wide osteocyte lacunae is in close contact with the titanium (acid fuchsin-toluidineblue, original magnification 3200).orim 29_206 Mp_88File # 06emmesh appeared to adhere to the newlyformed tissues, and, after its removal,a whitish soft tissue was present underneath;this tissue was carefully removedwith a curette, and it was possibleto observe that the space underthe titanium mesh and the resorbablemembrane was completely filled by atissue with the macroscopic features ofnewly formed bone (Figure 5). It wasnot possible to enter this tissue with adental probe. From a clinical point ofview, in all patients, no residual bonedefects were observed, and a signifi-cant increase of the alveolar width orheight was found (Figure 6). In all cases,it was possible to observe a good of inflammation (Figure 4). The micro-ORAL IMPLANTOLOGYThursday Feb 27 2003 03:12 PMAllen Press x DTPro Systemesthetic result of the restorative procedure(Figure 7). From a macroscopicpoint of view, the mesh was surroundedby dense connective tissue (Figure8). Histologic analysis showed that inall specimens the resorbable membranewas still present and fragmented andtended to surround, in many fields, thetitanium mesh. Few macrophages werevisible near the membrane, but no multinucleargiant cells were present. Theresorbable membrane and the titaniummesh were surrounded by a dense connectivetissue with few cells (Figure 9);no inflammatory infiltrate was present(Figure 10). In a few areas, capillarieswere visible near the membrane. Underpolarized light, connective tissue fiberswere seen running in a parallel wayaround the titanium (Figure 11). Insome specimens, it was possible to observenewly formed bone under the resorbablemembrane. In only a few areasunder the titanium mesh was itpossible to see newly formed bonewith wide osteocyte lacunae in tightcontact with the metal (Figures 12 and13); this bone was lined by osteoblasts.DISCUSSIONOne of the main problems in using occlusivemembranes is their lack of stiffness,which can produce a collapse ofthe barrier toward the bone defect, reducingthe space needed for the boneregeneration.15-18 This problem can be,in part, overcome with the use of graftsbeneath the membrane, but the influenceof the overlying soft tissues in collapsingthe membrane could still bepresent. For this reason, we decided, inpatients with deficient ridges in the lateraland vertical dimensions, to use atitanium micromesh to try to eliminatein a more complete way the negativeinfluence of the soft tissues. The higherthe stiffness of a material, the lesser thetendency to collapse. However, we alsohave to take into consideration theneed to adapt a barrier to the bonecontours.16 In all our patients, the titaniummicromesh was easy to handle,was ductile, and appeared to have excellentspace-making capabilities. Noinconveniences (dehiscences, infections)were observed in the healing ofthe soft tissues. On the contrary Cellettiet al,19 in an experimental study indogs using titanium membranes,found that at 3 weeks all these membraneswere slightly exposed. Thesedifferent results could be due to thefact that our barrier was made by a micromeshwith pores where the surroundingtissue could grow, whereasCelletti et al19 used a membrane withoutpores. The high biocompatibility ofthe titanium micromesh used is attestedto by the presence, in some specimens,of newly formed bone in closeand tight contact with the metal.20 Inall our patients, the use of grafts underthe mesh and the membrane appearedto have a beneficial effect on theamount of bone regeneration in non-space-making defects. The dense connectivetissue that we found under thetitanium mesh and the resorbablemembrane could be due to differentfactors, such as insufficient peripheralhealing between material and bone, ingrowthof connective tissue throughthe pores of the barrier, and insuffi-cient stability of the wound area.7These findings are in contrast tothe study by Lundgren et al,5 where,with the use of a completely occlusivetitanium barrier, no presence of connectivetissue was found under themembrane. In our cases, the connectivetissue under the mesh was probablycaused by an insufficient adaptation ofthe mesh to the contours of the bonedefects due to the stiffness of the material.Regarding this issue, Zellin etal21 found that, in a histologic comparisonof 10 different types of membranesin rats, a 50-mm membranemade of a titanium foil had the leasttendency to collapse, but problemswere present concerning the adaptabilityof the material. In conclusion, theclinical and histologic results of thepresent study show that most certainlythe space for the bone regeneration isone of the most critical factors in thesuccess of the regenerative techniquesand that the primary closure of theorim 29_206 Mp_89File # 06emMarco Degidi et almucoperiosteal flap has a relevant rolein the protection of the blood clot andin the prevention of infection.8,22,23 Theuse of a bioresorbable membrane andof grafting material under the barriermembranes is certainly helpful andbeneficial.ACKNOWLEDGMENTSThis work was supported in part bythe National Research Council, Rome,Italy, and the Ministry of Education,University, and Research, Rome, Italy.REFERENCES1. Jovanovic SA, Nevins M. Boneformation utilizing titanium-reinforcedbarrier membranes. Int J PeriodonticsRestorative Dent. 1995;15:57-69.2. Jovanovic SA, Schenk RK, OrsiniM, Kenney EB. Supracrestal bone formationaround dental implants: an experimentaldog study. 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