Volume 97 Issue 6
22. Aalam AA, Nowzari H. Clinical evaluation of dental implants with surfaces roughened by anodic oxidation, dual acid-etched im-plants, and machined implants. Int J Oral Maxillofac Implants 2005;20:793-8. 23. Nowzari H, Chee W, Yi K, Pak M, Chung
WH, Rich S. Scalloped dental implants: a retrospective analysis of radiographic and clinical outcomes of 17 NobelPerfect implants in 6 patients. Clin Implant Dent Relat Res 2006;8:1-10.
24. Goodacre CJ, Bernal G, Rungcharassaeng K, Kan JY. Clinical complications with implants and implant prostheses. J Prosthet Dent 2003;90:121-32.
25. Cochran DL, Hermann JS, Schenk RK, Higginbottom FL, Buser D. Biologic width around titanium implants. A histometric analysis of the implanto-gingival junction around unloaded and loaded nonsub-merged implants in the canine mandible. J Periodontol 1997;68:186-98.
26. Herrman JS, Schoolfield JD, Schenk RK, Buser D, Cochran DL. Influence of the size of the microgap on crestal bone changes around titanium implants. A histometric evaluation of unloaded non-submerged im-plants in the canine mandible. J Periodontol 2001;72:1372-83.
27. Hammerle CH, Bragger U, Burgin W, Lang NP. The effect of subcrestal placement of
the polished surface of ITI implants on marginal soft and hard tissues. Clin Oral Implants Res 1996;7:111-9.
28. Glauser R, Ruhstaller P, Windisch S, Zem-bic A, Lundgren A, Gottlow J, et al. Immedi-ate occlusal loading of Branemark System TiUnite implants placed predominantly in soft bone: 4-year results of a prospective clinical study. Clin Implant Dent Relat Res 2005;7 Suppl 1:52-9.
29. Jemt T. Regeneration of gingival papillae after single-implant treatment. Int J Peri-odontics Restorative Dent 1997;17:326-33. 30. Smith DE, Zarb GA. Criteria for success
of osseointegrated endosseous implants. J Prosthet Dent 1989;62:567-72.
31. Adell R, Lekholm U, Rockler B, Branemark PI, Lindhe J, Eriksson B, et al. Marginal tissue reactions at osseointegrated titanium fixtures (I). A 3-year longitudinal pro-spective study. Int J Oral Maxillofac Surg 1986;15:39-52.
32. Berglundh T, Lindhe J, Marinello C, Erics-son I, Liljenberg B. Soft tissue reactions to de novo plaque formation on implants and teeth. An experimental study in the dog. Clin Oral Implants Res 1992;3:1-8. 33. Apse P, Zarb GA, Schmitt A, Lewis DW.
The longitudinal effectiveness of osseointe-grated dental implants. The Toronto Study: peri-implant mucosal response. Int J
Peri-odontics Restorative Dent 1991;11:94-111. 34. Henry PJ, Tolman DE, Bolender C. The
applicability of osseointegrated implants in the treatment of partially edentulous patients: three-year results of a prospec-tive multi-center study. Quintessence Int 1993;24:123-9.
35. Kan JY, Rungcharassaeng K, Lozada JL. Bilaminar subepithelial connective tissue grafts for immediate implant placement and provisionalization in the esthetic zone. J Calif Dent Assoc 2005;33:865-71.
Reprint requests to:
Dr Joseph Kan
Department of Restorative Dentistry Loma Linda University School of Dentistry Loma Linda, CA 92354
Fax: 909-558-4803 E-mail: jkan@llu.edu
Acknowledgments
The authors thank Mr Shinishiro Maruo for statistical analysis, and Drs Kotaro Oyama and Sueng-Hwan Chung for their assistance with the study.
0022-3913/$32.00
Copyright © 2007 by the Editorial Council of The Journal of Prosthetic Dentistry.
Clinical Implications
Using concave transmucosal profiles for implant components
seems to allow for better and more predictable soft tissue
sta-bility in esthetic areas than divergent profiles.
Statement of problem. The literature indicates that 0.5 to 1.5 mm of gingival recession most often occurs within the first months after implant placement or abutment connection.
Purpose. The purpose of this pilot study was to evaluate the effect of a concave transmucosal profile on the vertical stability of soft tissues at the facial aspect of dental implants.
Material and methods. Fifty-four implants were placed in esthetically demanding sites in 41 patients (17 women, 24 men; age range of 23 to 62 years, mean 40.3 years; 5 smokers), primarily following a 1-stage approach. Twenty-five implants were placed immediately after extraction. Experimental concave titanium (n=49) and zirconia abutments (n=5) were used, and a provisional crown was placed at the same session. Digital photographs were made perpen-dicularly to the facial aspect of the teeth at abutment placement, and at 1, 3, 6, 12, 18, and 24 months, and enlarged views were subsequently analyzed by an independent examiner. Vertical changes in soft tissue levels were measured, and the definitive esthetic result was evaluated subjectively (poor to excellent). Data were analyzed with descriptive statistics.
Results. Twenty-four implants were evaluated at 24 months, 20 at 18 months, and 8 at 12 months. Vertical augmen-tation or no recession in soft tissue was observed in 87% of the situations, and in no situation was recession greater than 0.5 mm found. The gingival level remained stable at 12, 18, and 24 months. The average esthetic outcome was rated as 4.5 (very good to excellent) on a 0- to 5-point scale.
Conclusions. The concave, gingivally converging abutments used in the study allowed for above-average soft tissue outcomes. (J Prosthet Dent 2007; 97: S119-S125.)
Soft tissue stability at the facial aspect
of gingivally converging abutments in
the esthetic zone: A pilot clinical study
Eric Rompen, DDS, PhD,
aNicolas Raepsaet, DDS,
bOlivier Domken, DDS,
cBernard Touati, DDS, MS,
dand
Eric Van Dooren, DDS
eUniversity of Liege, Liege, Belgium
Implant components for the present study were provided by Nobel Biocare AB, Goteborg, Sweden.
aProfessor; Head, Department of Periodontology, University of Liege.
bPostgraduate student, Department of Periodontology, Dental Surgery, University of Liege. cSenior Lecturer, Department of Prosthodontics, University of Liege.
dPrivate practice, Paris, France. ePrivate practice, Antwerp, Belgium.
Endosteal dental implants, as well as natural teeth, have to pierce the oral mucosa and enter the oral cav-ity to be functionally useful. This es-tablishes a transmucosal connection
between the inner parts of the body and the external environment, which can be an entrance for toxic organ-isms or substances. To avoid bacte-rial penetration that could jeopardize
either the initial healing or long-term success of implant-supported res-torations, the formation of an early, long-standing, effective barrier ca-pable of biologically protecting the
Volume 97 Issue 6
June 2007
periimplant structures is mandatory. The soft tissue barrier, often called bi-ological width, has a dimension of 3 to 4 mm in the apicocoronal direction, is critical for tissue stability around im-plants, and is likely a prerequisite for osseointegration.1-7
The interface consists of 2 zones, 1 of epithelium, which covers approxi-mately 2 mm of the surface, while the remainder forms a connective tis-sue adhesion. Both tistis-sues contrib-ute to the establishment of the soft tissue interface, which may prevent oral bacteria and their by-products from penetrating into the body. It is generally recognized that the epithe-lium lining the periimplant sulcus is similar to the junctional epithelium adjacent to teeth.8-10 In contrast,
connective tissue attachment to im-plant components is different from that observed for teeth. In periodon-tal tissues, cementum lines the root until enamel is reached, thus offer-ing a substrate in which bundles of collagen fibers can deeply insert.11-13
These bundles reinforce the gingiva and provide high cohesive strength to the dento-gingival attachment, neces-sary for maintaining its architecture and integrity in spite of repeated trau-ma due to trau-mastication. With endoste-al dentendoste-al implants, due to the absence of cementum and the solid nature of transmucosal implant components, there is no true anchorage of supra-alveolar connective tissue, but only a brittle adhesion.4,6,14,15 As the
con-nective tissue interface is considered of paramount importance to support the epithelium and block its apical migration, this lack of mechanical re-sistance can potentially endanger the prognosis of dental implants. Tearing can occur at the connective tissue/ implant interface as a consequence of mastication or a lack of soft tissue stability, which can then induce an apical migration of the junctional epi-thelium, bone resorption and pocket formation, or gingival recession.16
Several studies have examined changes in soft tissue levels after im-plant placement.17-26 Despite
signifi-cant differences in experimental de-signs, the majority of studies conclude that gingival recession grossly varying from 0.6 to 1.5 mm is unavoidable. No significant difference could be de-termined between the 2-stage and the 1-stage surgical approaches,25 nor
be-tween 1- or 2-piece implants.24,25 One
clinical study17 reported 1.3-mm
re-cession from 1 month to 1 year, then an additional loss of 0.4 mm from 1 to 3 years. Another study21 found 1.6
mm of mean recession in the mandi-ble, versus 0.9 mm in the maxilla. In contrast, some authors found lower levels of recession.18,19,22,26 It is
impor-tant to note that these studies began measuring soft tissue recession just 1 month,18,19 6 weeks,22 or even 3 to 5
months26 after mucosal piercing. This
is important, as Small and Tarnow25
demonstrated that 50% of the reces-sion occurs after only 1 month and 90% after 3 months, with a stable lev-el reached at 9 months. This was later confirmed in another clinical study by Kan et al.23
With the multiple factors that can induce or influence gingival recession from the moment implants pierce the oral mucosa, there is little doubt that the low level of connective tissue at-tachment to implant components is important.16 Various methods for
im-proving the quality of the soft tissue interface have been proposed, such as alterations in the microdesign27,28 or
changes in the macrodesign of trans-mucosal implant components.
The purpose of this pilot clini-cal study was to evaluate the verticlini-cal stability of soft tissues at the facial aspect of endosteal dental implants to which experimental concave abut-ments were connected. The research hypothesis was that a concave, gingi-vally converging transmucosal profile would permit improved stabilization of the soft tissues as compared to the divergent transmucosal components used in previous studies.17-26
MATERIAL AND METHODS A prototype version of a 2-piece
implant with an internal connection (Replace Select Groovy; Nobel Bio-care AB, Goteborg, Sweden), with a diameter of 4.3 mm and a length of 10 or 13 mm, was used. The implant had 0.15-mm-deep microgrooves on its parallel-walled emerging neck, with an intergroove distance of 0.35 mm. The implant was inserted in such a manner that the top of the implant was located at the level of the bone crest on the facial side.
Experimental abutments made of machined titanium were specially designed (Nobel Biocare AB) for the study, first with a concave, inwardly narrowed profile at the transmucosal level, and then an emerging diameter of 5.0 mm29 (Figs. 1 and 2). The
re-sulting circumferential macrogroove was 0.45 mm in depth (Fig. 2). Two microgrooves (0.05 mm in depth, 0.25 mm apart) were also added in-side of the macrogroove. On the fa-cial aspect, the vertical distance from abutment shoulder to implant was 2 mm, while the developed distance (soft tissue to titanium interface) in the same area was 3 mm (Fig. 2). Zirconia abutments with the same inwardly narrowed design were also fabricated by CAD-CAM technology (Procera; Nobel Biocare AB), but on a narrower platform of abutment-to-implant connection. The zirconia abutments had no additional micro-grooves.
Forty consecutive patients (24 men, 17 women; age range of 23 to 62 years, mean 40.3 years) request-ing implant treatment in esthetically demanding areas and willing to par-ticipate in the study were included between October 2004 and Novem-ber 2005. Treatment was provided by 2 clinicians at 1 academic institution (University Hospital of Liege) and 1 private practice (Antwerp). The Eth-ics Committee of the University Hos-pital of Liege approved the study, and patients provided oral informed consent. Inclusion criteria consisted of the willingness of the patient to attend recall appointments and the technical feasibility of making
per-pendicular photographs of the facial aspect of the implant(s). Otherwise, routine criteria for implant placement in the esthetic zone were used, such as the absence of any serious systemic illness that would have impaired im-plant placement, the presence of ad-equate bone volume for implantation in the desired position, and the pres-ence of healthy keratinized gingiva on the facial aspect. No exclusion criteria were set concerning the type of occlu-sion or opposing dentition. Five pa-tients were smokers.
Fifty-four implants were placed in the following regions: 43 maxillary an-terior, 9 maxillary premolars, 1 man-dibular anterior, and 1 manman-dibular premolar. Twenty-five implants were placed in immediate extraction sock-ets, while 29 were placed in healed sites. Fifty-two implants were placed with a 1-stage surgical approach, and 2 were covered with a flap. At first-stage (n=52) or second-stage (n=2) surgery, a definitive abutment and provisional crown were placed in all situations, and care was taken to avoid direct occlusal contact with the opposing dentition. Definitive res-torations (Procera AllCeram crowns; Nobel Biocare AB) were placed 2 to 6 months later. For 5 patients, the tita-nium abutments were replaced with a zirconia abutment with a comparable transmucosal design for reasons of translucency.
Digital photographs were made at the time of placement of the abut-ment and provisional restoration (baseline). Additional photographs were made at 1, 3, 6, and 12 months, and at 18 and 24 months when appli-cable, as well as at placement of the definitive restoration. Care was taken to make these pictures in an axis per-pendicular to the facial aspect of the edentulous space, and the orientation was carefully evaluated after the im-ages were transferred to the comput-er. The digital photographs were then analyzed by an independent examiner after the images made at the various treatment stages were placed in a single computer file, and magnified to
1 Experimental abutments tested with concave, inwardly narrowed profile at transmucosal level and with emerging diameter of 5.0 mm.
2 Details of inwardly narrowed transmucosal profile: depth of macrogroove (a) is 0.45 mm. Distance from abutment shoulder to implant level (b) is 2 mm. Total length of concave profile in contact with soft tissues (c) is 3 mm.
Volume 97 Issue 6
June 2007
periimplant structures is mandatory. The soft tissue barrier, often called bi-ological width, has a dimension of 3 to 4 mm in the apicocoronal direction, is critical for tissue stability around im-plants, and is likely a prerequisite for osseointegration.1-7
The interface consists of 2 zones, 1 of epithelium, which covers approxi-mately 2 mm of the surface, while the remainder forms a connective tis-sue adhesion. Both tistis-sues contrib-ute to the establishment of the soft tissue interface, which may prevent oral bacteria and their by-products from penetrating into the body. It is generally recognized that the epithe-lium lining the periimplant sulcus is similar to the junctional epithelium adjacent to teeth.8-10 In contrast,
connective tissue attachment to im-plant components is different from that observed for teeth. In periodon-tal tissues, cementum lines the root until enamel is reached, thus offer-ing a substrate in which bundles of collagen fibers can deeply insert.11-13
These bundles reinforce the gingiva and provide high cohesive strength to the dento-gingival attachment, neces-sary for maintaining its architecture and integrity in spite of repeated trau-ma due to trau-mastication. With endoste-al dentendoste-al implants, due to the absence of cementum and the solid nature of transmucosal implant components, there is no true anchorage of supra-alveolar connective tissue, but only a brittle adhesion.4,6,14,15 As the
con-nective tissue interface is considered of paramount importance to support the epithelium and block its apical migration, this lack of mechanical re-sistance can potentially endanger the prognosis of dental implants. Tearing can occur at the connective tissue/ implant interface as a consequence of mastication or a lack of soft tissue stability, which can then induce an apical migration of the junctional epi-thelium, bone resorption and pocket formation, or gingival recession.16
Several studies have examined changes in soft tissue levels after im-plant placement.17-26 Despite
signifi-cant differences in experimental de-signs, the majority of studies conclude that gingival recession grossly varying from 0.6 to 1.5 mm is unavoidable. No significant difference could be de-termined between the 2-stage and the 1-stage surgical approaches,25 nor
be-tween 1- or 2-piece implants.24,25 One
clinical study17 reported 1.3-mm
re-cession from 1 month to 1 year, then an additional loss of 0.4 mm from 1 to 3 years. Another study21 found 1.6
mm of mean recession in the mandi-ble, versus 0.9 mm in the maxilla. In contrast, some authors found lower levels of recession.18,19,22,26 It is
impor-tant to note that these studies began measuring soft tissue recession just 1 month,18,19 6 weeks,22 or even 3 to 5
months26 after mucosal piercing. This
is important, as Small and Tarnow25
demonstrated that 50% of the reces-sion occurs after only 1 month and 90% after 3 months, with a stable lev-el reached at 9 months. This was later confirmed in another clinical study by Kan et al.23
With the multiple factors that can induce or influence gingival recession from the moment implants pierce the oral mucosa, there is little doubt that the low level of connective tissue at-tachment to implant components is important.16 Various methods for
im-proving the quality of the soft tissue interface have been proposed, such as alterations in the microdesign27,28 or
changes in the macrodesign of trans-mucosal implant components.
The purpose of this pilot clini-cal study was to evaluate the verticlini-cal stability of soft tissues at the facial aspect of endosteal dental implants to which experimental concave abut-ments were connected. The research hypothesis was that a concave, gingi-vally converging transmucosal profile would permit improved stabilization of the soft tissues as compared to the divergent transmucosal components used in previous studies.17-26
MATERIAL AND METHODS A prototype version of a 2-piece
implant with an internal connection (Replace Select Groovy; Nobel Bio-care AB, Goteborg, Sweden), with a diameter of 4.3 mm and a length of 10 or 13 mm, was used. The implant had 0.15-mm-deep microgrooves on its parallel-walled emerging neck, with an intergroove distance of 0.35 mm. The implant was inserted in such a manner that the top of the implant was located at the level of the bone crest on the facial side.
Experimental abutments made of machined titanium were specially designed (Nobel Biocare AB) for the study, first with a concave, inwardly narrowed profile at the transmucosal level, and then an emerging diameter of 5.0 mm29 (Figs. 1 and 2). The
re-sulting circumferential macrogroove was 0.45 mm in depth (Fig. 2). Two microgrooves (0.05 mm in depth, 0.25 mm apart) were also added in-side of the macrogroove. On the fa-cial aspect, the vertical distance from abutment shoulder to implant was 2 mm, while the developed distance (soft tissue to titanium interface) in the same area was 3 mm (Fig. 2). Zirconia abutments with the same inwardly narrowed design were also fabricated by CAD-CAM technology (Procera; Nobel Biocare AB), but on a narrower platform of abutment-to-implant connection. The zirconia abutments had no additional micro-grooves.
Forty consecutive patients (24 men, 17 women; age range of 23 to 62 years, mean 40.3 years) request-ing implant treatment in esthetically demanding areas and willing to par-ticipate in the study were included between October 2004 and Novem-ber 2005. Treatment was provided by 2 clinicians at 1 academic institution (University Hospital of Liege) and 1 private practice (Antwerp). The Eth-ics Committee of the University Hos-pital of Liege approved the study, and patients provided oral informed consent. Inclusion criteria consisted of the willingness of the patient to attend recall appointments and the technical feasibility of making
per-pendicular photographs of the facial aspect of the implant(s). Otherwise, routine criteria for implant placement in the esthetic zone were used, such as the absence of any serious systemic illness that would have impaired im-plant placement, the presence of ad-equate bone volume for implantation in the desired position, and the pres-ence of healthy keratinized gingiva on the facial aspect. No exclusion criteria were set concerning the type of occlu-sion or opposing dentition. Five pa-tients were smokers.
Fifty-four implants were placed in the following regions: 43 maxillary an-terior, 9 maxillary premolars, 1 man-dibular anterior, and 1 manman-dibular premolar. Twenty-five implants were placed in immediate extraction sock-ets, while 29 were placed in healed sites. Fifty-two implants were placed with a 1-stage surgical approach, and 2 were covered with a flap. At first-stage (n=52) or second-stage (n=2) surgery, a definitive abutment and provisional crown were placed in all situations, and care was taken to avoid direct occlusal contact with the opposing dentition. Definitive res-torations (Procera AllCeram crowns; Nobel Biocare AB) were placed 2 to 6 months later. For 5 patients, the tita-nium abutments were replaced with a zirconia abutment with a comparable transmucosal design for reasons of translucency.
Digital photographs were made at the time of placement of the abut-ment and provisional restoration (baseline). Additional photographs were made at 1, 3, 6, and 12 months, and at 18 and 24 months when appli-cable, as well as at placement of the definitive restoration. Care was taken to make these pictures in an axis per-pendicular to the facial aspect of the edentulous space, and the orientation was carefully evaluated after the im-ages were transferred to the comput-er. The digital photographs were then analyzed by an independent examiner after the images made at the various treatment stages were placed in a single computer file, and magnified to
1 Experimental abutments tested with concave, inwardly narrowed profile at transmucosal level and with emerging diameter of 5.0 mm.
2 Details of inwardly narrowed transmucosal profile: depth of macrogroove (a) is 0.45 mm. Distance from abutment shoulder to implant level (b) is 2 mm. Total length of concave profile in contact with soft tissues (c) is 3 mm.
Volume 97 Issue 6
June 2007
allow direct comparison. The height and width of the adjacent teeth, as well as of the edentulous space and provisional crown, were measured at the first treatment session. The verti-cal stability or instability of the soft tissues was evaluated by the indepen-dent examiner in relation to the posi-tion of the marginal tissues on adja-cent teeth or implants, the position of the soft tissues relative to abutment shoulder/crown margin/incisal edge, and the known length of the provi-sional crown. The computer-assisted views allowed for enlargement of the figures, and, thus, for easier and more precise evaluation than direct exami-nation. The results were classified into 4 groups: recession > 0.5 mm, reces-sion ≤ 0.5 mm, stability (recesreces-sion = 0 mm), or vertical gain.
The esthetic outcome was also evaluated separately by the clinician who rendered the treatment and by an independent examiner. Evaluations were based on the soft tissue position and volume, the color, shape, and texture of the definitive restoration, and the overall final outcome. The outcomes were recorded subjectively as 0 (bad), 1 (poor), 2 (satisfying), 3 (good), 4 (very good), or 5 (excellent) by each examiner. In the event of dis-agreement, the average between ex-aminers was taken as the final result. The data were analyzed using descrip-tive statistics.
RESULTS
All 54 implants remained stable during the investigation period; 24 implants were evaluated 24 months after abutment and provisional crown placement, 20 after 18 months, and 10 after 12 months. The vertical soft tissue behavior is shown in Table I.
No implant demonstrated facial recession greater than 0.5 mm at any point in time. Seven implants (13.0%) demonstrated recession of <0.5 mm from abutment and provisional res-toration placement (baseline) to 3 months, with no further recession detected during the remainder of the evaluation period. In none of these patients was a correction of the ver-tical soft tissue level by means, for instance, of a connective tissue graft, necessary from an esthetic standpoint. Eighteen implants (33.3%) showed no detectable change in the soft tis-sue level from baseline through the entire follow-up period. Twenty-nine patients (53.7%) exhibited a vertical gain of keratinized soft tissue from baseline to 3 months (Fig. 3). For es-thetic reasons, in 9 of the situations in the anterior maxilla, the morphol-ogy of the provisional restoration re-quired intentional modification once, to as many as several times, to pro-gressively reposition the gingival
mar-gin in a more apical position before making the impression for the defini-tive restoration. All situations (100%) exhibited a stable level of facial soft tissues from placement of the defini-tive restoration (2 to 6 months after implant or abutment placement) to the end of the follow-up period.
No clinically significant difference could be detected between implants placed in healed sites and implants placed in immediate extraction sock-ets; 25 implants were placed immedi-ately after extraction and 29 in healed edentulous sites. The vertical soft tissue behavior proved to be compa-rable in both groups: 3 immediate im-plants (12%) versus 4 delayed (13.8%) had slight recession of <0.5 mm, 8 immediate (32%) versus 10 delayed (34.5%) showed a stable level, and 14 immediate (56%) versus 15 delayed (51.7%) had a vertical gain of soft tis-sue. Changing from a titanium to a zirconium-oxide abutment did not in-fluence clinical stability of facial soft tissues. When the esthetic outcome was evaluated by the practitioners and an independent examiner at 12 months (n=10), 18 months (n=20), or 24 months (n=24), 5 implants were rated as 3 (good), 24 were rated as 4 (very good), and 25 were rated as 5 (excellent), with a resulting mean score of 4.37 (Table II) (Fig. 3).
Table I.
Vertical behavior of soft tissues at facial aspects of concave, inwardly narrowed abutments (n=54) Baseline to 3 months (%) Definitive restoration placement to end of follow-up period (%) Vertical Soft Tissue Alteration 0 0 0 0 7 (13.0%) 18 (33.3%) 54 (100%) 29 (53.7 %) Recession > 0.5 mm Recession < 0.5 mm Recession = 0 mm Vertical Gain3 A, Note vertically fractured maxillary first premolar which was gently extracted and immediately replaced by im-plant, with simultaneous placement of concave abutment and provisional crown. B, Healing 1 week after tooth extrac-tion and implant, abutment, and provisional crown placement. Provisional crown is somewhat shorter to avoid direct occlusal contact with opposing teeth. C, Definitive result after 18 months following single-stage, graftless procedure. Note increase of keratinized gingival height as compared to initial situation. Esthetic outcome was judged excellent.
A
B
C
Table II.
Evaluation of esthetic outcome of implants (n=54) at final examinationNumber of implants Percent Score 0 0 0 5 9.25 24 44.4 25 46.3
Bad Poor Satisfying Good Very Good Excellent
DISCUSSION
Multiple parameters, such as the presence or absence of keratinized gingiva, facial bone level, and surface topography of transmucosal implant components, can influence the soft tissue interface and gingival recession at implant components.16 The
au-thors hypothesize that the lack of an-chorage of the periimplant connective tissue into implant components4,6,14-16
can be partly compensated for by using a concave, inwardly narrowed macrodesign of the transmucosal
im-plant components. At present, diver-gent profiles are used in most clinical situations because clinicians desire to have a wide emergence diameter to mimic natural teeth. However, diver-gent transmucosal profiles can have a negative effect: the transmucosal components create a centrifuge pres-sure at the internal side of the soft tissues. This can result in a tendency for recession. Several authors exam-ined changes in soft tissue levels af-ter implant placement.17-26 Despite
significant differences in experimen-tal designs, the vast majority of
au-thors conclude that gingival recession grossly varying from 0.6 to 1.5 mm is unavoidable.
The results of the present study contrast with these previous data since it was found that the reces-sion was always less than 0.5 mm and occurred in a minority of situa-tions (13%). A vertical gain of soft tissues was observed in a majority of situations (53.7%), supporting the research hypothesis that a concave, inwardly narrowed transmucosal pro-file permits improved stabilization of the soft tissues. Clinical data
Volume 97 Issue 6
June 2007
allow direct comparison. The height and width of the adjacent teeth, as well as of the edentulous space and provisional crown, were measured at the first treatment session. The verti-cal stability or instability of the soft tissues was evaluated by the indepen-dent examiner in relation to the posi-tion of the marginal tissues on adja-cent teeth or implants, the position of the soft tissues relative to abutment shoulder/crown margin/incisal edge, and the known length of the provi-sional crown. The computer-assisted views allowed for enlargement of the figures, and, thus, for easier and more precise evaluation than direct exami-nation. The results were classified into 4 groups: recession > 0.5 mm, reces-sion ≤ 0.5 mm, stability (recesreces-sion = 0 mm), or vertical gain.
The esthetic outcome was also evaluated separately by the clinician who rendered the treatment and by an independent examiner. Evaluations were based on the soft tissue position and volume, the color, shape, and texture of the definitive restoration, and the overall final outcome. The outcomes were recorded subjectively as 0 (bad), 1 (poor), 2 (satisfying), 3 (good), 4 (very good), or 5 (excellent) by each examiner. In the event of dis-agreement, the average between ex-aminers was taken as the final result. The data were analyzed using descrip-tive statistics.
RESULTS
All 54 implants remained stable during the investigation period; 24 implants were evaluated 24 months after abutment and provisional crown placement, 20 after 18 months, and 10 after 12 months. The vertical soft tissue behavior is shown in Table I.
No implant demonstrated facial recession greater than 0.5 mm at any point in time. Seven implants (13.0%) demonstrated recession of <0.5 mm from abutment and provisional res-toration placement (baseline) to 3 months, with no further recession detected during the remainder of the evaluation period. In none of these patients was a correction of the ver-tical soft tissue level by means, for instance, of a connective tissue graft, necessary from an esthetic standpoint. Eighteen implants (33.3%) showed no detectable change in the soft tis-sue level from baseline through the entire follow-up period. Twenty-nine patients (53.7%) exhibited a vertical gain of keratinized soft tissue from baseline to 3 months (Fig. 3). For es-thetic reasons, in 9 of the situations in the anterior maxilla, the morphol-ogy of the provisional restoration re-quired intentional modification once, to as many as several times, to pro-gressively reposition the gingival
mar-gin in a more apical position before making the impression for the defini-tive restoration. All situations (100%) exhibited a stable level of facial soft tissues from placement of the defini-tive restoration (2 to 6 months after implant or abutment placement) to the end of the follow-up period.
No clinically significant difference could be detected between implants placed in healed sites and implants placed in immediate extraction sock-ets; 25 implants were placed immedi-ately after extraction and 29 in healed edentulous sites. The vertical soft tissue behavior proved to be compa-rable in both groups: 3 immediate im-plants (12%) versus 4 delayed (13.8%) had slight recession of <0.5 mm, 8 immediate (32%) versus 10 delayed (34.5%) showed a stable level, and 14 immediate (56%) versus 15 delayed (51.7%) had a vertical gain of soft tis-sue. Changing from a titanium to a zirconium-oxide abutment did not in-fluence clinical stability of facial soft tissues. When the esthetic outcome was evaluated by the practitioners and an independent examiner at 12 months (n=10), 18 months (n=20), or 24 months (n=24), 5 implants were rated as 3 (good), 24 were rated as 4 (very good), and 25 were rated as 5 (excellent), with a resulting mean score of 4.37 (Table II) (Fig. 3).
Table I.
Vertical behavior of soft tissues at facial aspects of concave, inwardly narrowed abutments (n=54) Baseline to 3 months (%) Definitive restoration placement to end of follow-up period (%) Vertical Soft Tissue Alteration 0 0 0 0 7 (13.0%) 18 (33.3%) 54 (100%) 29 (53.7 %) Recession > 0.5 mm Recession < 0.5 mm Recession = 0 mm Vertical Gain3 A, Note vertically fractured maxillary first premolar which was gently extracted and immediately replaced by im-plant, with simultaneous placement of concave abutment and provisional crown. B, Healing 1 week after tooth extrac-tion and implant, abutment, and provisional crown placement. Provisional crown is somewhat shorter to avoid direct occlusal contact with opposing teeth. C, Definitive result after 18 months following single-stage, graftless procedure. Note increase of keratinized gingival height as compared to initial situation. Esthetic outcome was judged excellent.
A
B
C
Table II.
Evaluation of esthetic outcome of implants (n=54) at final examinationNumber of implants Percent Score 0 0 0 5 9.25 24 44.4 25 46.3
Bad Poor Satisfying Good Very Good Excellent
DISCUSSION
Multiple parameters, such as the presence or absence of keratinized gingiva, facial bone level, and surface topography of transmucosal implant components, can influence the soft tissue interface and gingival recession at implant components.16 The
au-thors hypothesize that the lack of an-chorage of the periimplant connective tissue into implant components4,6,14-16
can be partly compensated for by using a concave, inwardly narrowed macrodesign of the transmucosal
im-plant components. At present, diver-gent profiles are used in most clinical situations because clinicians desire to have a wide emergence diameter to mimic natural teeth. However, diver-gent transmucosal profiles can have a negative effect: the transmucosal components create a centrifuge pres-sure at the internal side of the soft tissues. This can result in a tendency for recession. Several authors exam-ined changes in soft tissue levels af-ter implant placement.17-26 Despite
significant differences in experimen-tal designs, the vast majority of
au-thors conclude that gingival recession grossly varying from 0.6 to 1.5 mm is unavoidable.
The results of the present study contrast with these previous data since it was found that the reces-sion was always less than 0.5 mm and occurred in a minority of situa-tions (13%). A vertical gain of soft tissues was observed in a majority of situations (53.7%), supporting the research hypothesis that a concave, inwardly narrowed transmucosal pro-file permits improved stabilization of the soft tissues. Clinical data
Volume 97 Issue 6
June 2007
tion began the day of abutment and provisional crown placement, which must be emphasized, since it has been reported that 50% of the recession can occur within the first 4 weeks.25
The tissue remained stable from the time the definitive restoration was placed (2 to 6 months after implant placement or abutment connection) to the end of the evaluation period. It should also be noted that all implants had attached facial gingiva before implant placement, and it remained throughout the evaluation period.
With comparable time periods for data collection, but for diverging abutments and with comparable pro-portions of attached gingiva, reces-sion at the buccal aspect of 80% of the implants was reported by Small and Tarnow.25 The authors reported
a mean recession value of 0.88 mm. These results were confirmed by other studies of divergent abutments.22,24
The type of transmucosal design used is, unfortunately, poorly described in previously published data. A clini-cal study of a 1-piece implant with a machined, tulip-shaped, divergent transmucosal profile (Straumann, Basel, Switzerland), demonstrated recession at 60% of implants with a continuous loss over the 24-month evaluation period.24 The authors also
showed stability or gain of soft tissues with 40% of their implants, which is contrary to the findings of the present study where 87.0% of implant sites demonstrated an absence of gingival recession or gain of soft tissue at the facial aspect.
In another study with the same 1-piece implant with a machined, tulip-shaped, divergent transmucosal pro-file,22 a 3-stage surgery at previously
healed sites attempted to augment the thickness of the tissues before im-plant placement, first through guided bone regeneration using a nonresorb-able membrane and bovine hydroxy-apatite, and then through connective tissue grafting. Despite preparation of sites with surgical augmentation, the author demonstrated a mean reces-sion of 0.6 mm. In addition, it must
be noted that the soft tissue measure-ments in that study were initiated 5 to 6 weeks after implant placement; that is, when more than 50% of the reces-sion process had likely occurred. These data suggest that attempts to prepare sites before implant placement do not necessarily limit soft tissue recession with divergent transmucosal profiles. However, favorable results with slight-ly concave abutments have also been previously described..20 Using
abut-ments with a diameter narrower than the body of the implants, the authors showed a mean vertical gain of 0.34 mm of soft tissue.
No attempt was made in the cur-rent study to correlate vertical soft tis-sue behavior with marginal bone re-modeling. The aim of the authors was to focus on facial soft tissue stability, which is a significant issue in the es-thetic zone. Unfortunately, periapical radiographs only show the proximal bone level and not the facial bone levels, meaning that radiographic ob-servations are of little interest, if any, in terms of correlation with facial soft tissue recession. Surgical reopening would have been more reliable, but it has been demonstrated that raising a flap has detrimental effects on facial bone.19
The present study has some limi-tations due to the limited sample size and to its open, noncomparative design, which provides less powerful information than a randomized clini-cal trial. The use of a visual analogue scale to evaluate the esthetic outcome could also have been more sensitive.
The authors hypothesize that the positive soft tissue behavior with the particular transmucosal component design evaluated in the present study is linked to a combination of 3 fac-tors. First, the circumferential mac-rogroove creates a void chamber in which a blood clot forms that provides space for soft tissue regeneration. The result is a nonsurgical, localized thick-ening of the soft tissues. Second, the curved profile allows for increased length of the soft tissue-to-implant interface, meaning that a biological seal of 3 mm can be obtained despite a shorter crown-to-implant distance (Fig. 2). Third, after maturation of the soft tissues, a type of ring-like seal is created (Fig. 4) that could stabilize the connective tissue adhesion and, to some degree, functionally mimic the effect of Sharpey’s fibers attach-ing to teeth.
A randomized clinical trial compar-ing concave to divergent abutments in
4 Fibrous ring formed around abutment after healing.
controlled clinical conditions should be conducted to provide further evi-dence of the effect of the design of transmucosal components on soft tissue behavior. Animal studies may also be helpful in gathering histologi-cal data on soft tissue integration at concave transmucosal components as compared to divergent ones.
CONCLUSIONS
Within the limitations of this pilot study focusing on soft tissue stabil-ity of implants placed in the esthetic zone with concave, gingivally converg-ing abutments, the followconverg-ing conclu-sions may be drawn:
1. In contrast with existing data from the literature, which demon-strates that 0.5 to 1.5 mm of reces-sion may be expected with a majority of implants, 87% of the present sites showed facial soft tissue stability or gain, while recession (13% of the sites) was never greater than 0.5 mm.
2. These results remained stable from the time of placement of the de-finitive restoration to 12, 18, and 24 months, suggesting that using inward-ly narrowed transmucosal profiles for implant components allows for more predictable soft tissue stability in es-thetic areas than divergent profiles.
REFERENCES
1. Abrahamsson I, Berglundh T, Wennstrom J, Lindhe J. The peri-implant hard and soft tissues at different implant systems. A comparative study in the dog. Clin Oral Implants Res 1996;7:212-9.
2. Abrahamsson I, Berglundh T, Lindhe J. The mucosal barrier following abutment dis/re-connection. An experimental study in dogs. J Clin Periodontol 1997;24:568-72. 3. Abrahamsson I, Berglundh T, Moon IS,
Lindhe J. Peri-implant tissues at submerged and non-submerged titanium implants. J Clin Periodontol 1999;26:600-7.
4. Berglundh T, Lindhe J, Ericsson I, Marinello CP, Liljenberg B, Thomsen P. The soft tissue barrier at implants and teeth. Clin Oral Implants Res 1991;2:81-90.
5. Berglundh T, Lindhe J. Dimension of the periimplant mucosa. Biological width
revis-ited. J Clin Periodontol 1996;23:971-73. 6. Buser D, Weber HP, Donath K, Fiorellini JP, Paquette DW, Williams RC. Soft tissue reactions to non-submerged unloaded tita-nium implants in beagle dogs. J Periodontol 1992;63:225-35.
7. Cochran DL, Hermann JS, Schenk RK, Higginbottom FL, Buser D. Biologic width around titanium implants. A histometric analysis of the implanto-gingival junction around unloaded and loaded nonsub-merged implants in the canine mandible. J Periodontol 1997;68:186-98.
8. Carmichael RP, McCulloch CA, Zarb GA. Quantitative immunohistochemical analysis of keratins and desmoplakins in human gingiva and peri-implant mucosa. J Dent Res 1991;70:899-905.
9. Mackenzie IC, Tonetti MS. Formation of normal gingival epithelial phenotypes around osseo-integrated oral implants in humans. J Periodontol 1995;66:933-43. 10.Liljenberg B, Gualini F, Berglundh T, Tonetti
M, Lindhe J. Composition of plaque-as-sociated lesions in the gingiva and the peri-implant mucosa in partially edentulous subjects. J Clin Periodontol 1997;24:119-23.
13.Gargiulo AW, Wentz FM, Orban B. Mitotic activity of human oral epithelium exposed to 30 per cent hydrogen peroxide. Oral Surg Oral Med Oral Pathol 1961;14:474-92. 14.Listgarten MA, Buser D, Steinemann SG,
Donath K, Lang NP, Weber HP. Light and transmission electron microscopy of the intact interfaces between non-submerged titanium-coated epoxy resin implants and bone or gingiva. J Dent Res 1992;71:364-71.
15.Chavrier CA, Couble ML. Ultrastructural immunohistochemical study of interstitial collagenous components of the healthy human keratinized mucosa surrounding implants. Int J Oral Maxillofac Implants 1999;14:108-12.
16.Rompen E, Domken O, Degidi M, Farias Pontes AE, Piatelli A. The effect of material characteristics, of surface topography and of implant components and connections on soft tissue integration: a literature re-view. Clin Oral Implants Res 2006;17 Suppl 2:55-67.
17.Adell R, Lekholm U, Rockler B, Branemark PI, Lindhe J, Eriksson B, et al. Marginal tissue reactions at osseointegrated titanium fixtures (I). A 3-year longitudinal pro-spective study. Int J Oral Maxillofac Surg 1986;15:39-52.
18.Bengazi F, Wennstrom JL, Lekholm U. Recession of the soft tissue margin at oral implants. A 2-year longitudinal prospective study. Clin Oral Implants Res 1996;7:303-10.
19.Cardaropoli G, Lekholm U, Wennstrom JL. Tissue alterations at implant-supported sin-gle-tooth replacements: a 1-year prospec-tive clinical study. Clin Oral Implants Res 2006;17:165-71.
20.Cooper L, Felton DA, Kugelberg CF, Ellner
S, Chaffee N, Molina AL, et al. A multi-center 12-month evaluation of single-tooth implants restored 3 weeks after 1-stage surgery. Int J Oral Maxillofac Implants 2001;16:182-92.
21.Ekfeldt A, Eriksson A, Johansson LA. Peri-implant mucosal level in patients treated with implant-supported fixed prostheses: a 1-year follow-up study. Int J Prosthodont 2003;16:529-32.
22.Grunder U. Stability of the mucosal topography around single-tooth implants and adjacent teeth: 1-year results. Int J Peri-odontics Restorative Dent 2000;20:11-7. 22.Grunder U. Stability of the mucosal
topography around single-tooth implants and adjacent teeth: 1-year results. Int J Peri-odontics Restorative Dent 2000;20:11-7. 23.Kan JY, Rungcharassaeng K, Lozada J. Im-mediate placement and provisionalization of maxillary anterior single implants: 1-year prospective study. Int J Oral Maxillofac Implants 2003;18:31-9.
24.Oates TW, West J, Jones J, Kaiser D, Cochran DL. Long-term changes in soft tissue height on the facial surface of dental implants. Implant Dent 2002;11:272-9. 25.Small PN, Tarnow DP. Gingival recession
around implants: a 1-year longitudinal prospective study. Int J Oral Maxillofac Implants 2000;15:527-32.
26.Weber HP, Kim DM, Ng MW, Hwang JW, Fiorellini JP. Peri-implant soft-tissue health surrounding cement- and screw-retained implant restorations: a multi-center, 3-year prospective study. Clin Oral Implants Res 2006;17:375-9.
27.Brunette DM, Tengvall P, Textor M. Tita-nium in medicine. 13th ed. Heidelberg: Springer-Verlag New York, LLC; 2001. p. 485-512.
28.Glauser R, Schupbach P, Gottlow J, Ham-merle CH. Periimplant soft tissue barrier at experimental one-piece mini-implants with different surface topography in humans: A light-microscopic overview and histomet-ric analysis. Clin Implant Dent Relat Res 2005;7:44-51.
29.Rompen E, Van Dooren E, Touati B, Duric S, inventors; Nobel Biocare AB, assignee. Dental Implant Arrangement. Swedish pat-ent application no SE 04001 57-4, January 1, 2004.
Reprint requests to:
Dr Eric Rompen
Department of Periodontology Dental Surgery, University of Liege CHU Sart Tilman, Medecine Dentaire Allée de l’Hôpital 1 4000 Liege BELGIUM Fax: 32 4 366 82 90 E-mail: Eric.Rompen@chu.ulg.ac.be 0022-3913/$32.00
Copyright © 2007 by the Editorial Council of The Journal of Prosthetic Dentistry.
Volume 97 Issue 6
June 2007
tion began the day of abutment and provisional crown placement, which must be emphasized, since it has been reported that 50% of the recession can occur within the first 4 weeks.25
The tissue remained stable from the time the definitive restoration was placed (2 to 6 months after implant placement or abutment connection) to the end of the evaluation period. It should also be noted that all implants had attached facial gingiva before implant placement, and it remained throughout the evaluation period.
With comparable time periods for data collection, but for diverging abutments and with comparable pro-portions of attached gingiva, reces-sion at the buccal aspect of 80% of the implants was reported by Small and Tarnow.25 The authors reported
a mean recession value of 0.88 mm. These results were confirmed by other studies of divergent abutments.22,24
The type of transmucosal design used is, unfortunately, poorly described in previously published data. A clini-cal study of a 1-piece implant with a machined, tulip-shaped, divergent transmucosal profile (Straumann, Basel, Switzerland), demonstrated recession at 60% of implants with a continuous loss over the 24-month evaluation period.24 The authors also
showed stability or gain of soft tissues with 40% of their implants, which is contrary to the findings of the present study where 87.0% of implant sites demonstrated an absence of gingival recession or gain of soft tissue at the facial aspect.
In another study with the same 1-piece implant with a machined, tulip-shaped, divergent transmucosal pro-file,22 a 3-stage surgery at previously
healed sites attempted to augment the thickness of the tissues before im-plant placement, first through guided bone regeneration using a nonresorb-able membrane and bovine hydroxy-apatite, and then through connective tissue grafting. Despite preparation of sites with surgical augmentation, the author demonstrated a mean reces-sion of 0.6 mm. In addition, it must
be noted that the soft tissue measure-ments in that study were initiated 5 to 6 weeks after implant placement; that is, when more than 50% of the reces-sion process had likely occurred. These data suggest that attempts to prepare sites before implant placement do not necessarily limit soft tissue recession with divergent transmucosal profiles. However, favorable results with slight-ly concave abutments have also been previously described..20 Using
abut-ments with a diameter narrower than the body of the implants, the authors showed a mean vertical gain of 0.34 mm of soft tissue.
No attempt was made in the cur-rent study to correlate vertical soft tis-sue behavior with marginal bone re-modeling. The aim of the authors was to focus on facial soft tissue stability, which is a significant issue in the es-thetic zone. Unfortunately, periapical radiographs only show the proximal bone level and not the facial bone levels, meaning that radiographic ob-servations are of little interest, if any, in terms of correlation with facial soft tissue recession. Surgical reopening would have been more reliable, but it has been demonstrated that raising a flap has detrimental effects on facial bone.19
The present study has some limi-tations due to the limited sample size and to its open, noncomparative design, which provides less powerful information than a randomized clini-cal trial. The use of a visual analogue scale to evaluate the esthetic outcome could also have been more sensitive.
The authors hypothesize that the positive soft tissue behavior with the particular transmucosal component design evaluated in the present study is linked to a combination of 3 fac-tors. First, the circumferential mac-rogroove creates a void chamber in which a blood clot forms that provides space for soft tissue regeneration. The result is a nonsurgical, localized thick-ening of the soft tissues. Second, the curved profile allows for increased length of the soft tissue-to-implant interface, meaning that a biological seal of 3 mm can be obtained despite a shorter crown-to-implant distance (Fig. 2). Third, after maturation of the soft tissues, a type of ring-like seal is created (Fig. 4) that could stabilize the connective tissue adhesion and, to some degree, functionally mimic the effect of Sharpey’s fibers attach-ing to teeth.
A randomized clinical trial compar-ing concave to divergent abutments in
4 Fibrous ring formed around abutment after healing.
controlled clinical conditions should be conducted to provide further evi-dence of the effect of the design of transmucosal components on soft tissue behavior. Animal studies may also be helpful in gathering histologi-cal data on soft tissue integration at concave transmucosal components as compared to divergent ones.
CONCLUSIONS
Within the limitations of this pilot study focusing on soft tissue stabil-ity of implants placed in the esthetic zone with concave, gingivally converg-ing abutments, the followconverg-ing conclu-sions may be drawn:
1. In contrast with existing data from the literature, which demon-strates that 0.5 to 1.5 mm of reces-sion may be expected with a majority of implants, 87% of the present sites showed facial soft tissue stability or gain, while recession (13% of the sites) was never greater than 0.5 mm.
2. These results remained stable from the time of placement of the de-finitive restoration to 12, 18, and 24 months, suggesting that using inward-ly narrowed transmucosal profiles for implant components allows for more predictable soft tissue stability in es-thetic areas than divergent profiles.
REFERENCES
1. Abrahamsson I, Berglundh T, Wennstrom J, Lindhe J. The peri-implant hard and soft tissues at different implant systems. A comparative study in the dog. Clin Oral Implants Res 1996;7:212-9.
2. Abrahamsson I, Berglundh T, Lindhe J. The mucosal barrier following abutment dis/re-connection. An experimental study in dogs. J Clin Periodontol 1997;24:568-72. 3. Abrahamsson I, Berglundh T, Moon IS,
Lindhe J. Peri-implant tissues at submerged and non-submerged titanium implants. J Clin Periodontol 1999;26:600-7.
4. Berglundh T, Lindhe J, Ericsson I, Marinello CP, Liljenberg B, Thomsen P. The soft tissue barrier at implants and teeth. Clin Oral Implants Res 1991;2:81-90.
5. Berglundh T, Lindhe J. Dimension of the periimplant mucosa. Biological width
revis-ited. J Clin Periodontol 1996;23:971-73. 6. Buser D, Weber HP, Donath K, Fiorellini JP, Paquette DW, Williams RC. Soft tissue reactions to non-submerged unloaded tita-nium implants in beagle dogs. J Periodontol 1992;63:225-35.
7. Cochran DL, Hermann JS, Schenk RK, Higginbottom FL, Buser D. Biologic width around titanium implants. A histometric analysis of the implanto-gingival junction around unloaded and loaded nonsub-merged implants in the canine mandible. J Periodontol 1997;68:186-98.
8. Carmichael RP, McCulloch CA, Zarb GA. Quantitative immunohistochemical analysis of keratins and desmoplakins in human gingiva and peri-implant mucosa. J Dent Res 1991;70:899-905.
9. Mackenzie IC, Tonetti MS. Formation of normal gingival epithelial phenotypes around osseo-integrated oral implants in humans. J Periodontol 1995;66:933-43. 10.Liljenberg B, Gualini F, Berglundh T, Tonetti
M, Lindhe J. Composition of plaque-as-sociated lesions in the gingiva and the peri-implant mucosa in partially edentulous subjects. J Clin Periodontol 1997;24:119-23.
13.Gargiulo AW, Wentz FM, Orban B. Mitotic activity of human oral epithelium exposed to 30 per cent hydrogen peroxide. Oral Surg Oral Med Oral Pathol 1961;14:474-92. 14.Listgarten MA, Buser D, Steinemann SG,
Donath K, Lang NP, Weber HP. Light and transmission electron microscopy of the intact interfaces between non-submerged titanium-coated epoxy resin implants and bone or gingiva. J Dent Res 1992;71:364-71.
15.Chavrier CA, Couble ML. Ultrastructural immunohistochemical study of interstitial collagenous components of the healthy human keratinized mucosa surrounding implants. Int J Oral Maxillofac Implants 1999;14:108-12.
16.Rompen E, Domken O, Degidi M, Farias Pontes AE, Piatelli A. The effect of material characteristics, of surface topography and of implant components and connections on soft tissue integration: a literature re-view. Clin Oral Implants Res 2006;17 Suppl 2:55-67.
17.Adell R, Lekholm U, Rockler B, Branemark PI, Lindhe J, Eriksson B, et al. Marginal tissue reactions at osseointegrated titanium fixtures (I). A 3-year longitudinal pro-spective study. Int J Oral Maxillofac Surg 1986;15:39-52.
18.Bengazi F, Wennstrom JL, Lekholm U. Recession of the soft tissue margin at oral implants. A 2-year longitudinal prospective study. Clin Oral Implants Res 1996;7:303-10.
19.Cardaropoli G, Lekholm U, Wennstrom JL. Tissue alterations at implant-supported sin-gle-tooth replacements: a 1-year prospec-tive clinical study. Clin Oral Implants Res 2006;17:165-71.
20.Cooper L, Felton DA, Kugelberg CF, Ellner
S, Chaffee N, Molina AL, et al. A multi-center 12-month evaluation of single-tooth implants restored 3 weeks after 1-stage surgery. Int J Oral Maxillofac Implants 2001;16:182-92.
21.Ekfeldt A, Eriksson A, Johansson LA. Peri-implant mucosal level in patients treated with implant-supported fixed prostheses: a 1-year follow-up study. Int J Prosthodont 2003;16:529-32.
22.Grunder U. Stability of the mucosal topography around single-tooth implants and adjacent teeth: 1-year results. Int J Peri-odontics Restorative Dent 2000;20:11-7. 22.Grunder U. Stability of the mucosal
topography around single-tooth implants and adjacent teeth: 1-year results. Int J Peri-odontics Restorative Dent 2000;20:11-7. 23.Kan JY, Rungcharassaeng K, Lozada J. Im-mediate placement and provisionalization of maxillary anterior single implants: 1-year prospective study. Int J Oral Maxillofac Implants 2003;18:31-9.
24.Oates TW, West J, Jones J, Kaiser D, Cochran DL. Long-term changes in soft tissue height on the facial surface of dental implants. Implant Dent 2002;11:272-9. 25.Small PN, Tarnow DP. Gingival recession
around implants: a 1-year longitudinal prospective study. Int J Oral Maxillofac Implants 2000;15:527-32.
26.Weber HP, Kim DM, Ng MW, Hwang JW, Fiorellini JP. Peri-implant soft-tissue health surrounding cement- and screw-retained implant restorations: a multi-center, 3-year prospective study. Clin Oral Implants Res 2006;17:375-9.
27.Brunette DM, Tengvall P, Textor M. Tita-nium in medicine. 13th ed. Heidelberg: Springer-Verlag New York, LLC; 2001. p. 485-512.
28.Glauser R, Schupbach P, Gottlow J, Ham-merle CH. Periimplant soft tissue barrier at experimental one-piece mini-implants with different surface topography in humans: A light-microscopic overview and histomet-ric analysis. Clin Implant Dent Relat Res 2005;7:44-51.
29.Rompen E, Van Dooren E, Touati B, Duric S, inventors; Nobel Biocare AB, assignee. Dental Implant Arrangement. Swedish pat-ent application no SE 04001 57-4, January 1, 2004.
Reprint requests to:
Dr Eric Rompen
Department of Periodontology Dental Surgery, University of Liege CHU Sart Tilman, Medecine Dentaire Allée de l’Hôpital 1 4000 Liege BELGIUM Fax: 32 4 366 82 90 E-mail: Eric.Rompen@chu.ulg.ac.be 0022-3913/$32.00
Copyright © 2007 by the Editorial Council of The Journal of Prosthetic Dentistry.
