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Clinical Application of the Mucogingival Subepithelial Connective Tissue Graft

October 1, 2013
by Eugene Kryshtalskyj, DDS, Dip. Perio, MSc, FRCD(C); Eugene Gerald Kryshtalskyj, BHSc; Alexander Krys


INTRODUCTION
In 1999, Albandar et. al1 estimated that more than 20 percent of the population presents with one or more tooth surfaces with gingival recession. When root exposure occurs, it can be quite uncomfortable causing root sensitivity and can lead to cosmetic and functional impairment. The treatment of gingival recession therefore is indicated for esthetic reasons, to reduce root sensitivity, and to restore the integrity of the keratinized tissue.2 The treatment aims to improve esthetics, comfort and function.

ETIOLOGY OF GINGIVAL RECESSION3
Predisposing Factors:
1. Inadequate attached gingiva (thin biotype)

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2. A high frenum attachment

3. Malposition of teeth (prominent roots)

4. Osseous dehiscence/fenestra­tions

Of all of these factors, the most critical is the width of attached gingiva. Gingival recession is unlikely to occur if the attached gingiva is adequate and the contributing factors are controlled.3

Contributing Factors:3
1. Vigorous tooth brushing, especially with stiffer brushes and most power brushes

2. Bruxism causing abfraction lesions

3. Laceration (chronic direct trauma to the marginal gingiva which may include hard crusty foods like toast and crusty rolls)

4. Gingival inflammation secondary to poor plaque control

5. Iatrogenic factors (Figs. 1-3)

Iatrogenic factors include:
1. Restorative procedures extending subgingivally in areas of inadequate attached gingiva

2. Subgingival placement of rubber dam clamp – direct trauma

3. Close apposition and direct impingement of removable partial denture clasps and components, often referred to as “gum-stripping.”

4. Orthodontic bonding coupled with vigorous brushing efforts can precipitate gingival recession. Also, labial movement of predisposed teeth with thin gingiva, thin bone and frenum pull can lead to gingival recession and root exposure during tooth movement. Alternatively, lingual movement of teeth can improve labial attached gingiva provided an adequate zone of attached gingiva is present and teeth are positioned well within basal bone.

5. Intraoral and perioral piercings can cause mucogingival defects. In fact, the likelihood of labial gingival recession is 7.5 times greater amongst people with a labret (lip piercing) than amongst non-pierced individuals.

TREATMENT OPTIONS
In the past, the gold standard of mucogingival treatment was the free autogenous gingival graft originally described by Sullivan and Atkins.6 Over the years many permutations and modifications were made to the technique, such as the laterally positioned pedicle sliding flap and coronally repositioned flap/graft were developed and documented.7 The subepithelial connective tissue graft (SCTG) was introduced in 1985,8,9 and is now the first choice treatment for mucogingival defects. Many biological mediators, bone substrates, non-resorbable and resorbable barrier membranes have been investigated with varying outcomes. However, none of these approaches outperforms the effectiveness of the SCTG and coronally advanced flap (CAF) with regard to improved clinical parameters.10

McGuire and Nunn11 reported an average of 4.5mm (range of 4-8mm) root coverage with the SCTG. The outcome was maintained over 10 years averaging 3.89mm coverage.12 Chambrone et. al13 averaged 84-95 percent mean root coverage with SCTG and CAF. The authors had promising results with enamel matrix derivative and the CAF as well. Unfortunately, acellular dermal matrix allograft (ADM) and guided tissue regenerative (GTR) techniques fell short of long-term expectations. ADM, for example, had excellent one-month results compared with the SCTG at 93.4 percent vs. 96.6 percent root coverage. This dropped to 65.8 percent versus 97 percent success after four years.14 After 10 years, Nickles et. al15 demonstrated that GTR dropped from 43.7 percent success to 1.92 percent success as opposed to the SCTG which went from 72.7 percent to 43.7 percent success after 10 years. The SCTG has the advantage of being harvested from the patient and usually has the best colour match of any other material available. Graft rejection is uncommon and occurs most likely due to less than ideal surgical technique, due to trauma during the healing period or in case of post-surgical infection.

PREDICTABILITY OF ROOT COVERAGE WITH SCTG

Root Coverage with SCTG

We don’t wish to disappoint our patients. There are some situations where root coverage would be impossible to achieve. Fortunately, a useful classification system has been prepared by Miller,16 which includes four categories in order of increasing severity and decreased root coverage expectations.

Classification of recession:
Class I: Marginal tissue recession which does not extend to the mucogingival junction. There is no loss of periodontium (bone or soft tissue) in the interdental area, and 100% root coverage can be anticipated (Fig. 1).

Class II: Marginal tissue recession which extends to or beyond the mucogingival junction. There is no loss of periodontium (bone or soft tissue) in the interdental area, and 100 percent root coverage can be attempted (Figs. 1, 4A & 7A).

Class III: Marginal tissue recession extends to or beyond the mucogingival junction. There is bone or soft tissue loss in the interdental area, and/or there is malpositioning of the teeth which prevents attempting 100 percent root coverage. Partial root coverage can be anticipated provided the patient satisfies criteria for surgery stated in this paper (Figs. 5A & 6A).

Class IV: Marginal tissue recession which extends to or beyond the mucogingival junction. The bone or soft tissue loss in the interdental area and/or malpositioning of teeth is so severe that root coverage cannot be anticipated (Fig. 3).

Indications for SCTG:
1. A history of increasing gingival recession.

2. Root sensitivity that cannot be solved by root desensitization efforts, small bonded restorations, or in the case of abfraction/bruxism lesions, a night guard.

3. Esthetic, cosmetic considerations.

4. In preparation for prosthetic or orthodontic treatment.

5. Facilitation of oral hygiene in sit­uations where thin gingiva interferes with proper oral hygiene due to gingival sensitivity.

Situations where 100 percent root coverage with the SCTG is unlikely to occur:

1. Compromised general health

2. Smoking (less root coverage is achieved in smokers versus non-smokers)

3. Low compliance (non-collaborative patients)

4. Miller Class III and IV recession defects

In general, the best results for root coverage are achievable with mucogingival surgery when the gingival recession is characterized by:

1. Thin, short area of root exposure;

2. Isolated and localized presentation;

3. Minimal frenum involvement;

4. Healthy interdental bone and attached gingiva support;

5. Absence of root prominence (which usually is associated with a thin labial bony plate);

6. Absence of facial dehiscence or fenestrations which may be exposed during surgery

Cairo et. al5 developed a useful root coverage esthetic score which can be used to objectively assess the outcome of mucogingival surgery. Six points are given for complete root coverage, 0 for none, and 1 point each awarded for marginal tissue contour, soft tissue texture, mucogingival junction alignment and gingival colour.

CONCLUSIONS
Mucogingival defects can result from a myriad of conditions. Successful management requires that all predisposing and precipitating factors are identified ahead of the treatment and that the treatment addressed the once that can be altered. Unfortunate
ly, in advanced cases (i.e. Miller Class III and IV defects), 100 percent root coverage cannot be achieved.

The gold standard presently for managing mucogingival defects is the subepithelial connective tissue graft, and is currently the first choice treatment for handling mucogingival pathology.

Connective tissue grafting and implants
Connective tissue grafting has applications in the field of dental implantology as well. It is known that tooth extraction can be associated with a severe depletion of the alveolar process.18 Schrepp et. al19 reported that nearly 66% of the alveolar bone undergoes resorption within the first three months of tooth extraction. Efforts were therefore directed towards the concept of immediate placement of implants in fresh extraction sockets. Unfortunately, immediate implant placement does not stop buccal bone and soft tissue remodelling following tooth extraction. Boticelli et. al20 found a 56% reduction of buccal tissue volume versus 27% lingual tissue reduction following immediate implant placement resulting in related esthetic problems reported in a high percentage (40%) of immediate implants. Chen et. al,21,22 also reported that almost of their immediate implants showed unsatisfactory esthetic results which were also associated with several factors including (a) the thickness of the facial bone wall, (b) tissue biotype, and (c) implant positioning within the extraction sockets. Factors such as thin biotype constitution are successfully and predictably corrected with connective tissue grafting procedures.

With the above concerns in mind, many clinicians favour a delayed implant placement protocol. Contour augmentation using connective tissue grafts with coincidental bone grafts can improve the chances for better esthetic outcomes because they compensate for ridge alterations which always occur after tooth extractions.23 Facial bundle bone is very vulnerable to surgical trauma compromising blood supply to the surgical site.18

When simultaneous hard and soft tissue augmentation were provided with a delayed or immediate implant placement, Fagan et. al24 reported results of great interest. 100% of 25 implants were successfully restored without any cosmetic complications in the delayed implant placement group; 11 of 12 implants succeeded (91.6% integrated) in the immediate implant placement group where cosmetics was described as “adequate” vertical height of hard tissue.

A tremendous variety of bone and membrane grafting materials are available for ridge augmentation and socket preservation treatment, and include allografts, xenografts, and synthetic materials. However, no protocol for ridge preservation has been proven superior to another.25 The importance of the membrane cannot be overemphasized, because it contains the graft material and presents epithelial down growth into the healing site. This author’s preference is the connective tissue graft because it is easily available, it is an auto-graft which the body will embrace as its own, it works very well when placed correctly, and patients embrace it as a choice compared to foreign materials derived from human or animal donors. The disadvantages of delayed implant placement are the need to wear a transitional tooth replacement appliance (Essex appliance (Fig. 8H); conventional and less comfortable acrylic RPD (Fig. 9D); or bonded acrylic tooth) and a 3-6 month healing window before the implant can be placed. Greater predictability of hard and soft tissue positioning may be worthy of this consideration before implant placement in the esthetic zone.

General considerations
Ridge augmentation/preservation is a delicate procedure requiring minimal flap elevation, gentle atraumatic tooth extraction with degranulation of socket.26 The connective tissue graft is placed over the bone graft and gently sutured within the socket and any transitional tooth replacement choice is adjusted with full clearance from the surgical site preventing direct pressure on the site. Direct application of antimicrobials, such as chlorhexidine gluconate 0.12 percent are useful in plaque control of post-surgical site.

Contraindications:
1. Compromised general health (e.g. uncontrolled diabetes)

2. Severe occlusal or intermaxillary discrepancy

3. Severe parafunctional habits (bruxism)

4. Smoking in general (smoking decreases predictability of regenerative treatments significantly4)

5. Drug or alcohol abuse

6. Poor oral hygiene (low compliance level, non-collaborative patients)

7. Previously untreated periodontitis

8. Acute infection of the tooth site

9. Absence or >50 percent loss of the buccal plate

(The above are exclusion criteria from the major studies cited in this article)19,22

CONCLUSIONS
The SCTG has many applications in the field of periodontology for treatment of gingival recession and includes surgical management of implants in the esthetic zone as well. These grafts are highly desirable because of their autogenous nature and colour match potential. They are, however, technique-sensitive. Discussing this procedures in detail and in advance informs patients about their choices of treatment and avoids dissatisfaction with the end-results. Having the benefits of the Miller classification of gingival defects and the benefits of delayed implant placement following socket bone grafting with SCTG ridge augmentation in the esthetic zone we can improve our chances to achieve desired results. The SCTG is not a panacea, but it is an excellent adjunct to our armamentarium for solving many mucogingival challenges that we face every day in our dental practices. OH


Dr. Eugene Kryshtalskyj was an associate clinical instructor at the University of Toronto Faculty of Dentistry Periodontics Division for over 10 years and published many articles on periodontics in referenced journals. He has lectured on periodontics and implant dentistry and presently has a private practice restricted to periodontics and implant dentistry in Toronto, Ontario.

Eugene Gerald Kryshtalskyj is a second year dental student at the University of Western Ontario in London, Ontario.

Alexander Kryshtalskyj is a third year student in biological sciences at McMaster University in Hamilton, Ontario.

Oral Health welcomes this original article.