|Year : 2012 | Volume
| Issue : 2 | Page : 110-114
Implanto-gingival complex: An indispensable junctional complex for the clinical success of an implant
Inderpreet S Narula, Krishna K Chaubey, Vipin K Arora, Rajesh K Thakur, Zeba Jafri
Department of Periodontics, Kothiwal Dental College Research Centre, Kanth Road, Moradabad, Uttar Pradesh, India
|Date of Web Publication||10-Oct-2012|
Inderpreet S Narula
Senior Lecturer, Kothiwal Dental College Research Centre, Mora Mustaqueem, Moradabad, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Meticulous assessment of gingival and periodontal status around a future implant site is must for optimizing healthy esthetic gingival appearance and to establish a functionally successful implant-supported restoration. A successful osseointegrated implant requires a direct bone-to-implant interface to provide long-term support for a prosthesis. However a cause-effect relationship between bacterial plaque accumulation and the development of inflammatory changes in the soft tissues surrounding oral implants has been shown and known to exist. Thus maintaining a healthy peri-implant status becomes an integral component for the success of implant-supported restorations.
Keywords: Biologic-width, interfacial micro-gap, osseointegration, osteopreservation, peri-implantitis
|How to cite this article:|
Narula IS, Chaubey KK, Arora VK, Thakur RK, Jafri Z. Implanto-gingival complex: An indispensable junctional complex for the clinical success of an implant. J Dent Implant 2012;2:110-4
|How to cite this URL:|
Narula IS, Chaubey KK, Arora VK, Thakur RK, Jafri Z. Implanto-gingival complex: An indispensable junctional complex for the clinical success of an implant. J Dent Implant [serial online] 2012 [cited 2018 Apr 21];2:110-4. Available from: http://www.jdionline.org/text.asp?2012/2/2/110/102225
| Introduction|| |
Meticulous assessment of gingival and periodontal status around a future implant site is must for optimizing healthy esthetic gingival appearance and to establish a functionally successful implant-supported restoration. It entails to achieve psychologically, esthetically, and functionally successful implant supported restoration. Early osseointegration research concentrated on the adaptation of bone to the alloplastic implant surface and on the clinical survival of implants. A successful osseointegrated implant requires a direct bone-to-implant interface to provide long-term support for a prosthesis. A cause-effect relationship between bacterial plaque accumulation and the development of inflammatory changes in the soft tissues surrounding oral implants has been shown.  If this condition is left untreated, it may lead to the progressive destruction of the tissues supporting an implant (peri-implantitis), which may compromise its future and ultimately lead to its failure. 
Peri-implant soft tissues: The keratinized tissue and its significance
Relationship has been studied several times between periodontal health and width of attached gingiva. As stressed and concluded by Lang and Loe,  2 mm of keratinized gingival with 1 mm of attached gingival was sufficient to preserve periodontal health. On the contrary, Berglundh et al.  concluded that gingival health could be maintained in the absence of keratinized tissue, provided patient maintained proper home care or if the keratinized gingiva was augmented by soft tissue grafting around teeth or dental implants. However it has been found that regardless of plaque control, width of keratinized tissue either around teeth or implant does not influence periodontal or peri-implant or peri-implant health. 
Few studies have evaluated soft tissue around dental implants. Presence of keratinizing mucosa surrounding an implant is thought to be a positive factor in maintaining soft-tissue health. ,,,
However, at present evidence-based format has failed to show any correlation between the reduced width of keratinized gingiva and peri-implant health.
The connective tissue and epithelium may actually integrate with the titanium surfaces of dental implants, suggesting that the health and resistance to peri-implant disease states may be a reflection of the overall integration process contributing to the functional and esthetic success of implant. ,,,
| Chemistry of Bone-Implant Interfacial Healing|| |
The integrating and investing peri-implant tissues during implant healing includes cortical and cancellous bone, marrow collagenous tissue and the neurovascular structures, as observed at the healing interface at microscopic level. 
Alveolar bone housing around a natural teeth serves to provide tooth integrity and transmit the stress of occlusal forces to absorbed by force-dissipating periodontal ligament and surrounding bone. New bone and collagenous investing tissues are laid down to become part of the healed tissue around the implant. The biomechanical stress pattern at the bone-implant interface determines the amount and distribution of collagenous connective tissue during healing and under subsequent loading of implant superstructures. One stage hypofunctional healing with controlled micromovement is believed to promote the controlled deposition of a collagenous, osteogenic peri-implant ligament, and the osteopreservation mode of tissue integration. ,
The surface oxide thickness has been found to increase much faster at the implant position in bone than in air. 
The mechanism involved may include metal atom/ion diffusion out of the oxide surface followed by oxidation or oxygen diffusion from an oxygen carrying species at the oxide surface to the metal oxide interface. Other components that can contribute to the growth and modification of the oxide include hydrogen atoms (forming hydroxide) mineral ions of calcium and phosphorus.
When in contact with air or water, titanium quickly forms and surface oxide layer of thickness 3 to 5 nm at room temperature owing to which titanium is one of the most resistant metals contributing to its high bio-compatibility.
However, there also exists possibility of dissolution of oxide layer termed as corrosion.
Adequate host tissue response at the bone-implant interface involves bone remodeling with a gradual functional adaptation to the loads applied at the host site.
The implanto-gingival tissues serve as barrier function and necessitate the integration of three types of tissues: bone, soft connective tissue, and epithelium. The morphology of the healthy soft tissue adjacent to teeth has many features in common with that adjacent to implants: Both types of tissue have (a) a well-keratinized oral epithelium, (b) a junctional epithelium, and (c) a connective tissue lateral to the junctional epithelium and between the bone crest and the most apical extension of the junctional epithelium.
Whenever the oral mucosa is pierced by any structure, be it tooth during eruption or an implant, the epithelial cells are known to proliferate and migrate over the structure. Epithelial cells have the ability to synthesize basal lamina and form hemidesmosomal attachment. Several experimental studies have demonstrated a satisfactory epithelial attachment between oral mucosa and a dental implant.
| Dento-Gingival Unit V/S Implant-Gingival Complex|| |
The tooth and its supporting tissues have a precise embryological origin from dental follicle and therefore the investing tissue cells are genetically determined to form periodontium and its surrounding structures. Thus formed periodontal ligament has unique feature of adaptive remodeling owing to the presence of fibroblast population remodeling the collagen and ground substance. On the other hand, the soft tissues formed around the implant surface are not directly derived from the dental follicle, and thus do not have the ability to remodel and adapt to the stresses exerted upon the implant.
It is currently accepted that the implant-soft-tissue interface has certain similarities with that of natural teeth, including an oral epithelium, a sulcular epithelium, and a junctional epithelium with underlying connective tissue.  The most striking difference from the natural dentition is in the structure of the underlying connective tissue, which has been studied in vitro and in vivo.
Berglundh et al.  have demonstrated a cuff-like barrier of well-keratinized oral epithelium adhering to both teeth and implants. One difference was that collagen fibers of the peri-implant mucosa appeared to run parallel with the surface of the transmucosal abutment. Berglundh et al.  observed that the peri-implant tissues may have an impaired defense system, due to the finding that peri-implant tissues are virtually devoid of vascular supply. The vascular topography of the soft tissues around implants demonstrates that the soft tissue blood supply is derived from terminal branches of larger vessels from the bone periosteum at the implant site. Blood vessels adjacent to junctional epithelium around implants reveal a characteristic "crevicular plexus", but blood vessels adjacent to the connective tissue are sparse and often lacking.
Moon et al.  postulated that the fibroblast-rich layer adjacent to the titanium surface has a role in the maintenance of a proper seal between the oral environment and the peri-implant tissue.
Several weeks are required to obtain sufficient soft tissue dimensions and connective tissue quality of the peri-implant mucosa as well as an adequate degree of osseointegration. ,, Soft tissue healing around implants results in the establishment of a barrier epithelium and a zone of connective tissue integration, the dimensions of which constitutes the biological width. ,, Repeated abutment disconnection and reconnection resulted in an apical shift of the barrier epithelium and connective tissue attachment as well as loss of marginal bone. A single shift from a healing abutment to a permanent abutment, however, did not cause apparent effects on the soft and hard tissue integration to the implant. 
Buser et al.  concluded that the different surface textures of the dental implants did not influence the healing pattern of the soft tissues and found nonkeratinized sulcular epithelium with a zone of dense circular fibers close to the implant surface.
The depth of the implant in the bone affects the peri-implant soft tissues. Todescan et al.  placed implants at varying heights in the bone: 1 mm above the crest, even with the crest, and 1 mm below the crest of alveolar bone and found that there was a tendency for the epithelium and connective tissue to be longer when the implants were placed deeper. Abrahamsson et al.  and Berglundh et al.  that the epithelium establishes an attachment of approximately 2 mm, and the connective tissue, an attachment of approximately 1 mm around dental implants.
Implant-abutment interfacial "Micro-Gap".
Implant-abutment interface creates a small micro-gap that has been implicated in the ongoing health of soft tissue surrounding implants. ,,,,,, In two-part implants, the interface or "gap" between the transmucosal and intraosseous components was suggested to have a detrimental effect on the marginal bone level. Thus, results from animal experiments indicated that crestal bone loss of about 2 mm occurred around custom-made two-part implants with a gap size of about 50 mm. ,
Hermann et al.  in an experimental study in dogs evaluated healing around one- and two-part implants. The two-part implants were placed in such a way that the interface or "gap" between the two components was located either in level with 1 mm above or 1 mm below the crestal bone. Histological examinations made 6 months after implant installation revealed that the presence of a "gap" or interface between implant components had a significant effect on the resulting bone level. Thus, at two-part implants crestal bone loss in combination with an apical shift of the soft tissue margin was more pronounced than at one-part implants. However, marginal bone support at level with or even above the abutment-implant borderline, with osseointegration coronal to the abutment-implant interface has also been reported. 
An increased probing depth is a sign of reduced tissue resistance to probing, which in turn is interpreted as an indication of the presence of an inflammatory cell infiltrate in the gingival tissue.  Periodontal probing is commonly used to monitor tissue heights. Quirynen et al.  assessed various types of periodontal probes to determine which was the most reliable method to measure clinical attachment level and whether a relationship between bone and attachment levels around dental implants exists. The authors concluded that for implants with healthy gingiva, the clinical attachment level is a reliable indicator of bone level. Etter et al.  determined that healing of the epithelial attachment after probing around dental implants is complete after 5 days and does not appear to have any detrimental effects on the soft-tissue seal and the longevity of oral implants. In the periodontium, connective tissue fibers insert more or less perpendicular into the root surface. This type of attachment does not exist between the peri-implant mucosa and the implant; instead, the collagen fibers of the supracrestal connective tissue at implants lack a true attachment and have an orientation parallel to the implant surface. , This different type of supracrestal fiber arrangement could be one source of difference in probe penetration.
Tarnow et al.  noted the amount of space between implants and the relationship to bone height. Tarnow suggested that dental implants should have at least 3 mm between them and noted that implants placed closer than 3 mm had increased amounts of crestal bone loss. Implants should be placed in the optimal position mesio-distally, apico-coronally, and bucco-palatally. The mesio-distal dimension between adjacent teeth should be 6 to 9 mm to ensure minimal (1.5 mm) distance between implant fixture and adjacent teeth. , Natural buccal and proximal restorative contour can be ensured by correctly orienting the implant in a bucco-palatal position. A minimum space of 2 mm should be maintained on the buccal side in front of the external implant collar surface.
Criteria of success
Albrektsson et al.  included the following: absence of persistent subjective complains, such as pain, foreign body sensation, and/or dysestesia; absence of peri-implant infection with suppuration; absence of mobility; absence of a continuous radiolucency around the implant; and vertical bone loss less than 1.5 mm in the first year of function.
"Biologic Width" around implant
A biologic width has been reported in several studies which demonstrated that the mean height of the supra alveolar soft tissue at implant sites was 3 to 4 mm. The dimensions of the peri-implant soft tissues (i.e. the Biologic Width), as evaluated by histometric measurements, are significantly influenced by the presence/ absence of a microgap (interface) between the implant and the abutment, and the location of this microgap (interface) in relation to the crest of the bone. Biologic-width around one-piece implants is more similar to natural teeth dimensions as compared to two-piece implants, either being placed according to a submerged or a nonsubmerged technique.  Cochran et al.  showed that an area of epithelial attachment with the implant surface occurs similar in morphology to that which is found around natural teeth. In addition, an area of connective tissue contact was found between the apical extension of the junctional epithelium and the alveolar bone comprising the first bone-to-implant contact. The dimensions of these tissues, the biologic width, for nonsubmerged, one-piece implants were demonstrated to be similar to the dimensions for the same tissues described for natural teeth. , Sicher  indicated that the connective tissue attachment was the most stable component of the soft tissue unit while the junctional epithelium was more variable in its dimension. Weber et al.  found significant differences between implant types. Epithelium had a mean length of 1.18 mm for nonsubmerged implants and a 1.71 mm length around submerged implants.
| Summary|| |
Early osseointegration research concentrated on the adaptation of bone to the alloplastic implant surface and on the clinical survival of implants. A successful osseointegrated implant requires a direct bone-to-implant interface to provide long-term support for a prosthesis. A cause-effect relationship between plaque and implant may lead to the progressive destruction of the supporting tissues (peri-implantitis), which may compromise its future and ultimately lead to its failure. Hence a pre-treatment planning of a future implant-supported restoration requires an insight into the factors governing the restoration which includes the implanto-gingival complex, inter-implant distance, peri-implant probing depth, the interfacial micro-gap and the biologic width.
| Acknowledgment|| |
It takes me immense pleasure to acknowledge the hard-work of my collegues and my seniors including Dr. KK Chaubey, Prof. (Periodontics), Dr. VK Arora Prof. (Periodontics), Dr. Rajesh Thakur, Asso. Prof. (Periodontics), and Dr. Zeba Jafri, Senior Lecturer (Periodontics) without whom this work would not have been possible to carry out.
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