Mandibular recessions: the challenge of the anterior zone

The management of antero-mandibular gingival recessions (Miller Classes I and II) represents a unique clinical challenge due to frequent anatomical constraints: narrowness of the keratinized gingiva, thin phenotype, and shallow vestibular depth. While the coronally advanced flap combined with a connective tissue graft remains the gold standard, donor site morbidity and local tissue limitations sometimes lead practitioners toward the Double Laterally Sliding Bridge Flap (DLSBF) technique, which combines the principles of coronal repositioning and Edlan-Mejchar vestibuloplasty.

The objective of this comparative study was to evaluate the clinical efficacy of adding Plasma Rich in Growth Factor (PRGF) to the DLSBF protocol. PRGF, a leukocyte-free autologous platelet concentrate, is tested here for its ability to stimulate angiogenesis and gingival fibroblast proliferation via the release of growth factors (VEGF, PDGF, FGF). The authors hypothesized that this biological synergy would not only optimize the percentage of root coverage (PRC) and gingival thickness (GT), but also reduce postoperative morbidity (pain, bleeding, edema) compared to DLSBF used alone.

Experimental protocol: DLSBF and biological synergy

This comparative clinical study involved 30 patients, aged 25 to 60 years, presenting a total of 95 Miller Class I and II gingival recessions in the mandibular incisors and canines. The objective was to measure the clinical contribution of Plasma Rich in Growth Factor (PRGF) combined with the Double Lateral Sliding Bridge Flap (DLSBF) technique.

Les sites de récession ont été répartis en deux groupes :

• Test Group (15 patients, 50 sites): Treatment by DLSBF combined with local application of PRGF.
• Control Group (15 patients, 45 sites): Treatment with DLSBF alone.

The protocol was performed by a single experienced operator. PRGF, obtained by centrifugation of venous blood, was activated with calcium chloride immediately before application to induce fibrin clot formation and the release of growth factors. A calibrated examiner measured clinical parameters (gingival thickness, recession depth, attachment gain, keratinized gingiva) at baseline, then at 3 and 6 months of follow-up.

L'évaluation a également intégré les résultats rapportés par les patients (PRO), incluant la douleur, l’œdème et les saignements postopératoires. La robustesse des données a été vérifiée par les tests de Wilcoxon, Mann-Whitney U et le test t apparié, avec un seuil de significativité de p < 0,05.

Clinical superiority of PRGF at 6 months

The analysis of the 95 treated recessions (50 sites with DLSBF + PRGF and 45 sites with DLSBF alone) reveals a significant improvement in clinical parameters in the test group after a 6-month follow-up. The addition of Plasma Rich in Growth Factor (PRGF) resulted in superior clinical attachment gain and tissue thickening compared to the surgical technique alone.

The percentage of root coverage (PRC) constitutes the most significant result, with an advantage of more than 8 percentage points for the PRGF group. The increase in gingival thickness (GT) is highly significant (p < 0.001), suggesting that PRGF actively stimulates gingival fibroblast proliferation and collagen synthesis.

Patient-Reported Outcomes (PROs)

Beyond biometric measurements, the study evaluated postoperative morbidity during the early healing phase. Patients in the PRGF group reported significantly lower scores for the following indicators:

• Postoperative pain: Marked reduction compared to the control group.
• Bleeding: Lower incidence and intensity.
• Swelling (Oedema): Faster and less inflammatory clinical healing.

These qualitative observations confirm the interest of PRGF, not only for its regenerative properties (via the release of growth factors such as VEGF and PDGF), but also for its role in patient comfort during the immediate post-surgical phase.

Discussion: A biological lever for the mandibular sector

The results of this clinical study highlight the major benefit of adding PRGF to the Double Laterally Sliding Bridge Flap (DLSBF) technique. Clinically, the gain in percentage of root coverage (PRC) increasing from 64.63% to 72.83% (p = 0.019) at 6 months demonstrates that the biological contribution optimizes an already proven surgical technique for anterior mandibular recessions. The most significant point for the practitioner lies in the significant increase in gingival thickness (GT, p < 0.001), a critical factor for the long-term stability of soft tissues and the prevention of recurrence.

On a biological level, the observed efficacy is explained by the release of growth factors (VEGF, FGF, PDGF) that stimulate fibroblast proliferation and collagen synthesis. Unlike other platelet concentrates, the PRGF used here is leukocyte-free, which reduces the release of pro-inflammatory cytokines. This correlates directly with the improvement in postoperative outcomes: patients in the test group reported significantly less pain, bleeding, and edema during the early healing phase.

The study confirms the trends observed in previous works regarding the coronally advanced flap (CAF + PRGF), while validating the specific application to DLSBF. However, the scope of the results remains limited by a 6-month follow-up, which is insufficient to evaluate tissue stability over several years, and by the exclusion of Miller III and IV recessions.

Conclusion

L'adjonction de PRGF au lambeau doublement glissé (DLSBF) surpasse la technique conventionnelle seule en améliorant le recouvrement radiculaire, l'épaisseur gingivale et le gain d'attache, tout en simplifiant les suites post-opératoires pour le patient.

Summary of results

The addition of PRGF to the DLSBF technique significantly improves the root coverage rate, reaching 72.83% ± 20.53% compared to 64.63% ± 21.03% for the flap alone (p = 0.019). At 6 months, patients treated with PRGF also show superior clinical attachment gain (p = 0.049) and a marked increase in gingival thickness (p < 0.001), while reporting a notable reduction in postoperative pain and bleeding.

In concrete terms, for the practitioner:

• Optimize the anterior mandibular sector: For Miller class I and II recessions with a shallow vestibule, the addition of PRGF to DLSBF offers superior attachment gain and coverage compared to the conventional technique.
• Improve the gingival phenotype: Use PRGF as a biological adjuvant to thicken soft tissues, a key factor for the long-term stability of aesthetic results.
• Reduce post-operative morbidity: The integration of PRGF allows for a reduction in inflammatory sequelae (pain, oedema), a strong argument for patient treatment acceptance compared to connective tissue grafts.

Technical lexicon of the study

PRGF (Plasma Rich in Growth Factor): Autologous platelet concentrate of the first generation, characterized by the absence of leukocytes (thus reducing pro-inflammatory cytokines). Activated by calcium chloride, it releases key growth factors (VEGF, FGF, PDGF) that stimulate angiogenesis and the proliferation of gingival fibroblasts.

DLSBF (Double Laterally Sliding Bridge Flap): Surgical technique combining the principles of the coronally advanced flap and the modified Edlan-Mejchar vestibuloplasty. It allows for the treatment of multiple recessions while increasing vestibular depth, without the need for a palatal donor site.

RAL (Relative Attachment Level): Clinical measurement of the attachment level relative to a fixed reference point. The study shows a significant gain (p = 0.049) at 6 months thanks to the addition of PRGF, confirming better connective tissue reattachment.

GT (Gingival Thickness): Thickness of the gingival tissue, a crucial parameter for long-term aesthetic stability. The addition of PRGF resulted in a very significant improvement (p < 0.001) in this tissue phenotype compared to the flap alone.

PRC (Percentage of Root Coverage): Ratio expressing the effectiveness of root coverage. In this protocol, the PRGF group achieved 72.83% coverage compared to 64.63% for the control group, marking a statistically validated clinical superiority (p = 0.019).

APC (Autologous Platelet Concentrates): A family of biological adjuvants derived from the patient's blood, including PRGF and PRF. They are used here for their ability to transform soft tissue healing kinetics in periodontal plastic surgery.

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