Dr. Darko Veljanovski, oral surgeon
Just like the whole dental science,implantology has been evolving constantly and quickly. Its principles have been permanently changing. We are witnesses of “game changers” and “paradigm shifts” that appear almost every year. Even the “ gold standards” are not “ gold standards” any more.
However, some things in human medicine never change: the body’s anatomy and its healing “agenda” are ones of those.Therefore the dental practitioners should always follow the principles of biology. We must have deep respect for the body’s anatomy (for instance vascularity) and physiology ( for instance wound healing mechanisms). As for me, the famous phrase said by Dr. David Garber from the Atlanta group, “ the bone sets the tone but the tissue is the issue “ still stands.
What, in fact, is“ soft tissue” and why is soft tissue so important for the implants?
The oral mucosa is divided into masticatory mucosa( gingiva and hard palate), lining mucosa( lips, cheeks, vestibule, mouth floor) and sensory mucosa (tongue). The gingiva consists of connective tissue and epithelium. The surface of the gingiva is keratinized except for the interdental region. The gingiva extends from the gingival margin to the mucogingival junction. The free gingiva extends from the gingival margin to apical margin of the epithelial attachment. Buccal and lingual to the rows of the teeth, the free gingiva becomes continuous with the attached gingiva, which is connected to the cementum and alveolar bone. At the mucogingival junction it merges into the mobile mucosa whole palatally and lingually it makes transition into palatal masticatory mucosa and lingual mucosa.
Implant surgery brings certain degree of trauma to the patients. The created surgical wounds can heal by primary intention and by secondary intention, through a formation of a granulation (scar) tissue. Primary healing brings better esthetics and less postoperative morbidity. Our goal in implant surgery should be to achieve primary healing whenever possible, but never ar the cost of tension free closure.This is extremely important in periodontal plastic and implant surgery, where the microsurgical approach is superior in terms of results and predictability.
The attached gingiva has pink color and has a tendency of keratinization of the epithelium. This is a result of the genetic factors affecting the underlying connective tissue and is not an adaptive mechanism( Zuhr et al).
Since the attached gingiva is keratinized, clinicians often use the term ”keratinized” mucosa even though the term “attached”is more adequate.
Attached gingiva is important for the oral hygiene around implants which is prerequisite for long term implant success. The more attached gingiva around implants, the better the conditions for hygiene maintenance are. The sufficient amount of attached gingiva around implants keeps the crestal bone around implants stable. However, the minimal amount of keratinized tissue required for long term implants success around implants is still controversial (Tunkel, Khoury 2013).
So when installing or uncovering the implants we should always make efforts to maintain or create a band of healthy, attached gingiva around them.
The gingiva around implants should be:
5. Free from muscle pull and mobile mucosa tension
To achieve this we should pay attention to:
1. Implant uncovery flap design
2. The need for soft tissue grafts
Implant flap design
As a rule of thumb, the implant uncovery should be as minimally invasive as possible. The periosteum should be left on the bone to preserve vascularity and avoid possible bone resorption. One can choose among punch technique, half punch technique, midcrestal incision, middrestal incision palatally displaced, papilla preservation technique, apically positioned flap and palatal roll technique. Each techniques has its modifications and can be used depending on the clinical situation.These techniques can be done together with soft tissue grafts.
Soft tissue grafts
The role of the soft tissue grafts is to:
1. Increase soft tissue thickness
2. Increase the amount of attached gingiva
Soft tissue grafts can be divided into free gingival grafts (FGG) and connective tissue grafts (GTG) also referred to as subepithelial connective tissue grafts. The latter do not have the epithelial layer and can be harvested with or without periosteum.
FGGs have two great limitations: volume augmentation and aesthetic result (sometimes the color and surface do not blend with the recipient site).Subepithelial connective tissue graft do not have this disadvantages.( Langer & Langer 1985).
There are two major donor site available for CTGs:
A.Anterrior palate, with an extensive surface
B.Posterior palare, which includes:
1. Tuberosity, which is very voluminous and good for alveolar ridge augmentation
2. Lateral palate, good for recession coverage. They are both dense and firmer than the anterior palatal grafts so they rarely undergo postoperative shrinkage. But, they are more prone to necrosis due to their thickness, which is why they need to be completely covered. Zucchelli et al. (2010) proposed assessment of the donor site thickness with an endodontic needle with a silicon disc.
Soft tissue grafts shrink in time. The expected shrinkage at 12 months postoperatively is about one third of the original graft volume.
There are also alternatives for soft tissue grafts: acellular dermal matrix and 3D collagen matrix. They tend to achieve similar clinical results as autogenous soft tissue grafts, but they still can not totally replace them.
Which factors determine if the graft will succeed/fail?
1. Patient related factors: genetics, oral hygiene habits,smoking,malnutrition, alcohol abuse, systemic diseases
2. Site related factors: anatomy of defect, location of defect, depth of vestubule, soft tissue thickness,amount of keratinized tissue,clinical attachment level,plaque/infection
3. Technique related factors: operator skills, preparation of wound bed, graft volume, graft thickness, flap tension
The soft tissue manipulation in around teeth, especially around implants, is very technique sensitive. Being gentle to the soft tissues is prudent.We should always have in mind that there is no success in soft tissue surgery without:
1. Blood supply
This brings us back to the introduction of this article. If we respects the patient’s anatomy and know the ways of body’s healing, we have the key to success.