Health, Maintenance, and Recovery of Soft Tissues around Implants
Yulan Wang, MD; Yufeng Zhang, PhD; Richard J. Miron, PhD
Background: The health of peri-implant soft tissues is one of the most important aspects of osseointegration necessary for the long-term survival of dental implants.
Purpose: To review the process of soft tissue healing around osseointegrated implants and discuss the maintenance requirements as well as the possible short-comings of peri-implant soft tissue integration.
Materials and Methods: Literature search on the process involved in osseointegration, soft tissue healing and currently available treatment modalities was performed and a brief description of each process was provided.
Results: The peri-implant interface has been shown to be less effective than natural teeth in resisting bacterial invasion because gingival fiber alignment and reduced vascular supply make it more vulnerable to subsequent peri-implant disease and future bone loss around implants. And we summarized common procedures which have been shown to be effective in preventing peri-implantitis disease progression as well as clinical techniques utilized to regenerate soft tissues with bone loss in advanced cases of peri-implantitis.
Conclusion:Due to the difference between peri-implant interface and natural teeth, clinicians and patients should pay more attention in the maintenance and recovery of soft tissues around implants.
KEY WORDS: osseointegration, peri-implant soft tissue, peri-implantitis, peri-mucositis
When dental implants were first discovered and used to replace missing teeth, most clinicians focused primarily on implant stability as the biggest factor in and predictor for future success, and this trend has in part continued as the primary research criterion for implants.1–6
Osseointegration was and still is considered as the most important factor in maintaining implant stability, whereas the role of soft tissue healing and maintenance around implants has been somewhat neglected.7–10 More recently, evidence has demonstrated that the long-term survival of osseointegrated implants was also partly dependent on the transmucosal healing and stability around the implant collar, termed “peri-implant mucosa.”11 This attachment of the soft tissue to the coronal portion of an implant acts to provide a protective seal which prevents the development of bacterial invasion and future inflammation.12,13 Thus, the soft tissue seal is necessary for stable osseointegration and long-term survival of implants.14–16
One of the key findings relating to peri-implant mucosa was the direction of gingival fibers compared with the natural tooth (Figure 1). This key difference explained the increased ability of bacteria to penetrate the epithelial layer and subsequent connective tissue thus increasing the breakdown of soft tissues around implants.17 Therefore, if patient compliance is not fully obtained and proper oral hygiene is not maintained, inflammatory changes in the soft tissues surrounding dental implants will develop.18 This inflammatory process in the peri-implant mucosa
The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST), Key Laboratory of Oral BiomedicineMinistry of Education, School & Hospital of Stomatology, Wuhan University,
Corresponding Author: Prof.Yufeng Zhang, The State Key Laboratory
Breeding Base of Basic Science of Stomatology (Hubei-MOST), Key
Laboratory of Oral Biomedicine Ministry of Education, School &
Hospital of Stomatology,Wuhan University, 237 Luoyu Road,Wuhan 430079, China; e-mail: email@example.com © 2015 Wiley Periodicals, Inc.
DOI 10.1111/cid.12343 1 begins with reddening and swelling, and once bleeding on probing is initiated, the condition is then termed peri-implant mucositis. If this condition is left untreated, it may lead to progressive and irreversible destruction of implant-surrounding tissues including the loss of alveolar bone around dental implants and ultimately lead to implant failure.19 Thus, the structure and biological events that take place during osseointegration and soft tissue attachment are important components of implant survival and maintenance.
This review article aims to describe the composition of soft tissues around implants, how to maintain their health and survival, and how to deal with peri-mucositis and peri-implantitis progression and its reversibility.
BIOLOGICAL EVENTS DURING
Osseointegration, which has also been called “functional ankylosis,”20 was initially defined as “a direct structural and functional connection between ordered, living bone and the surface of a load-bearing implant.”21 More recently, authors have modified the definition of osseointegration. In 2012, Zarb and Koka defined osseointegration as “a time-dependent healing process whereby clinically asymptomatic rigid fixation of alloplastic materials is achieved and maintained in bone during functional loading.”22 The definition explains in more detail that the stages of osseointegration are divided into three overlapping steps: early immune-inflammatory response, angiogenesis, and osteogenesis.23
Interestingly, more recent evidence has demonstrated that a gap of about 60 μm between the implant surface and host bone is created,24,25 and it may extend to 100 to 500 μm over time.26 This gap typically contains a titanium oxide layer which comes into contact with blood plasma proteins and body fluids and is later adsorbed onto the implant surfaces immediately after implantation, forming a “conditioning film.”23,27 Several factors such as surface roughness28 as well as surface hydrophilicity29 are key determining factors influencing protein adsorption and are subsequently able to stimulate and induce cell attachment on the implant surface.30
The cell population which first occupies the implant surface is primarily composed of inflammatory cells, and many investigators refer to this original phase of implant healing as the “immune-inflammatory response.”23 Within 24 hours following implant insertion, neutrophils dominate the implant site. In the 2 to 4 days following, an increasing number of infiltrating macrophages and monocytes appear in the peri-implant gap. These cells are responsible for removing the debris, as well as secreting large quantities of cytokines and growth factors responsible for stimulating future mesenchymal cell recruitment and proliferation, angiogenesis, and collagen matrix deposition.31,32